Program
 
Tue Feb 27 2018
07:30 - 08:45
Registration
08:45 - 08:50
Announcement of the day
08:50 - 09:00
Opening ABXPV
Session G1: GOTSolar Session
Chair: Jacky Even
09:00 - 09:30
Session-I1
Mendes, Adélio
LEPABE-FEUP
New Advancements in Perovskite Solar Cells
Adélio Mendes
LEPABE-FEUP

Professor Adélio Mendes (born 1964) received his PhD degree from the University of Porto in 1993.

Full Professor at the Department of Chemical Engineering of the Faculty of Engineering of the University of Porto. Coordinates a large research team with research interests mainly in dye sensitized solar cells and perovskite solar cells, photoelectrochemical cells including water splitting and solar redox flow batteries, photocatalysis, redox flow batteries, electrochemical membrane reactors (PEMFC, H-SOFC, chemical synthesis), methanol steam reforming, membrane and adsorbent-based gas separations and carbon molecular sieve membranes synthesis and characterization.

Professor Mendes authored or co-authored more than 300 articles in peer-review international journals, filled 23 families of patents and is the author of a textbook; received an Advanced Research Grant from the ERC on dye-sensitized solar cells for building integrated of ca. 2 MEuros and since 2013 he is partner in 4 more EU projects and leads one EU project. Presently he is the leader of a FET Open project, GOTSolar, on perovskite solar cells. He received the Air Products Faculty Excellence 2011 Award (USA) for developments in gas separation and Solvay & Hovione Innovation Challenge 2011 prize, the Prize of Coimbra University of 2016, and the prize of Technology Innovation - 2017 by the University of Porto. Presently, he is the Coordinator of CEner-FEUP, the Competence Center for Energy of the Faculty of Engineering at the University of Porto.

Authors
Adélio Mendes a
Affiliations
a, FEUP - Faculdade de Engenharia da Universidade do Porto, University of Porto, Rua Dr. Roberto Frias, Porto, 4200-465, PT
Abstract

Perovskite solar cell (PSC) is a quite recent new thin-film PV technology, which promises to challenge a top place in the ranking of the PV technologies. A standard PSC cell is made of a TiO2 blocking layer – electron extracting layer – applied over a TCO glass substrate. Over this layer, a TiO2 mesoporous layer is applied, filled with an organic–inorganic halide perovskites. A hole extracting layer (otherwise known as hole transport material – HTM) of Spiro-OMeTAD covers the perovskite layer and over it, a counter-electrode of gold is applied.

GOTSolar project – FET-OPEN program no 687008 – begun in January 2016 aiming to improve the PSC efficiency and stability and to address the glass encapsulation using low temperature laser-assisted glass sealing approach, the development of a scalable embodiment and the challenge of decrease the lead content to meet the European relevant legislation.

The research project will soon initiate the third year of development and achieved already an astonish energy conversion efficiency of 21.6 % and a stability of 500 h @ 85 °C [1]; besides, new HTMs [2] and a new low temperature (≤ 120°C) laser-assisted glass sealing process were developed. A 10 × 10 cm2 displaying at least 8 % energy conversion efficiency with life expectancy of 20 years or more is expected by the end of the project.


References

[1] - Michael Saliba, Taisuke Matsui, Konrad Domanski, Ji-Youn Seo, Amita Ummadisingu, Shaik M. Zakeeruddin, Juan-Pablo Correa-Baena, Wolfgang R. Tress, Antonio Abate, Anders Hagfeldt, Michael Grätzel, "Incorporation of rubidium cations into perovskite solar cells improves photovoltaic performance", Science, 2016.

[2] - Neha Arora, M. Ibrahim Dar, Alexander Hinderhofer, Norman Pellet, Frank Schreiber, Shaik Mohammed Zakeeruddin, Michael Grätzel, "Perovskite solar cells with CuSCN hole extraction layers yield stabilized efficiencies >20%", Science, 2017.

09:30 - 10:00
Session-I2
Graetzel, Michael
École Polytechnique Fédérale de Lausanne EPFL
Metal halide perovskites as powerful light harvesters for the generation of electricity and fuels from sunlight
Michael Graetzel
École Polytechnique Fédérale de Lausanne EPFL, CH

Professor of Physical Chemistry at the Ecole Polytechnique Fédérale de Lausanne (EPFL) Michael Graetzel, PhD, directs there the Laboratory of Photonics and Interfaces. He pioneered research on energy and electron transfer reactions in mesoscopic systems and their use to generate electricity and fuels from sunlight. He invented mesoscopic injection solar cells, one key embodiment of which is the dye-sensitized solar cell (DSC).  DSCs are meanwhile commercially produced at the multi-MW-scale and created a number of new applications in particular as lightweight power supplies for portable electronic devices and in photovoltaic glazings. They engendered the field of perovskite solar cells (PSCs) that turned our to be the most exciting break-through in the recent history of photovoltaics. He received a number of prestigious awards, of which the most recent ones include the RusNANO Prize, the Zewail Prize in Molecular Science, the Global Energy Prize, the Millennium Technology Grand Prize, the Samson Prime Minister’s Prize for Innovation in Alternative Fuels, the Marcel Benoist Prize, the King Faisal International Science Prize, the Einstein World Award of Science and the Balzan Prize. He is a Fellow of several learned societies and holds eleven honorary doctor’s degrees from European and Asian Universities. According to the ISI-Web of Science, his over 1500 publications have received some 230’000 citations with an h-factor of 219 demonstrating the strong impact of his scientific work.

 

Authors
Michael Graetzel a
Affiliations
a, Laboratory of Photonics and Interfaces Ecole Polytechnique Fédérale de Lausanne, Suisse
Abstract

A planetary emergency has arisen from the continued depletion of fossil fuels, producing green house warming and unprecedented environmental pollution. Future energy options for renewable and carbon-free sources will need to fill the terra-watt gap that will open up during the next few decades due to the growth of the world population. A promising development is the recent emergence of a new generation of low cost and highly efficient photovoltaic converters based on perovskite pigments as light harvesters.. Perovskite solar cells (PSCs) [1] have attracted enormous interest due to their low cost ease of preparation and steep rise of their solar to electric power conversion efficiency (PCE) reaching now 22.7 % exceeding already the performance of polycrystalline silicon solar cells. Nevertheless achieving operational stability remains a major challenge for PSCs. I shall present new cell architectures using inorganic materials as hole and electron specific contacts that that attain PCE > 20 % and excellent stability under full sun light soaking at maxiumum power point and 60 °C [2]. . The high photovoltage (Voc > 1.2 V) achieved with these systems renders them very attractive for the generation of fuels from sunlight, e.g. by the splitting of water into hydrogen and oxygen [3] and the cleavage of CO2 into CO and 1/2 O2.  


References:
[1] M. Grätzel, The light and shade of perovskite solar cells., Nature Materials 2014, 13, 838-842.
[2] N. Arora, M.I. Dar, A.Hinderhofer, N. Pellet, F. Schreiber, S.M. Zakeeruddin, M. Grätzel, Perovskite solar cells with CuSCN hole extraction layers yield stabilized efficiencies greater than 22%. 
    Science 2017, doi:10.1126/science.aam5655.
[3] J. Luo, J.-H. Im, M.T. Mayer, M. Schreier, Md.K. Nazeeruddin, N.-G. Park, S.D.Tilley, H.J. Fan, M. Grätzel. Water photolysis at 12.3% efficiency via perovskite photovoltaics and Earth abundant catalysts. Science 2014, 345, 1593-1596. 

10:00 - 10:30
Session-I3
Saliba, Michael
Adolphe Merkle Institute, University of Fribourg, CH-1700 Fribourg, Switzerland
Incorporation of multiple cations for Highly Efficient, Phase and Temperature Stable Perovskite Semiconductors
Michael Saliba
Adolphe Merkle Institute, University of Fribourg, CH-1700 Fribourg, Switzerland
Authors
Michael Saliba a
Affiliations
a, École Polytechnique Fédérale de Lausanne, CH
Abstract

Perovskites have emerged as low-cost, high efficiency photovoltaics with certified efficiencies of 22.1% approaching already established technologies. The perovskites used for solar cells have an ABX3 structure where the cation A is methylammonium (MA), formamidinium (FA), or cesium (Cs); the metal B is Pb or Sn; and the halide X is Cl, Br or I. Unfortunately, single-cation perovskites often suffer from phase, temperature or humidity instabilities. This is particularly noteworthy for CsPbX3 and FAPbX3 which are stable at room temperature as a photoinactive “yellow phase” instead of the more desired photoactive “black phase” that is only stable at higher temperatures. Moreover, apart from phase stability, operating perovskite solar cells (PSCs) at elevated temperatures (of 85 °C) is required for passing industrial norms. Recently, double-cation perovskites (using MA, FA or Cs, FA) were shown to have a stable “black phase” at room temperature. These perovskites also exhibit unexpected, novel properties. For example, Cs/FA mixtures supress halide segregation enabling band gaps for perovskite/silicon or perovskite/perovskite tandems. In general, adding more components increases entropy that can stabilize unstable materials (such as the “yellow phase” of FAPbI3 that can be avoided using the also unstable CsPbI3). Here, we take the mixing approach further to investigate triple cation (with Cs, MA, FA) perovskites resulting in significantly improved reproducibality and stability. We then use multiple cation engineering as a strategy to integrate the seemingly too small rubidium (Rb) (that never shows a black phase as a single-cation perovskite) to study novel multication perovskites. One composition containing Rb, Cs, MA and FA resulted in a stabilized efficiency of 21.6% and an electroluminescence of 3.8%. The Voc of 1.24 V at a band gap of 1.63 eV leads to a very small loss-in-potential of 0.39 V, one of the lowest measured on any PV material indicating the almost recombination-free nature of the novel compound. Polymer-coated cells maintained 95% of their initial performance at 85°C for 500 hours under full illumination and maximum power point tracking. This is a crucial step towards industrialisation of perovskite solar cells. Lastly, to explore the theme of multicomponent perovskites further, molecular cations were revaluated using a globularity factor. With this, we calculated that ethylammonium (EA) has been misclassified as too large. Using the multication strategy, we studied an EA-containing compound that yielded an open-circuit voltage of 1.59 V, one of the highest to date. 

10:30 - 11:00
Coffee Break
11:00 - 11:30
Session-I4
Nie, Wanyi
Los Alamos National Laboratory
The critical role of structural dynamics on the optoelectronic device performance in hybrid perovskites
Wanyi Nie
Los Alamos National Laboratory, US
Authors
Wanyi Nie a, Hsinhan Tsai a, b, Reza Asadpour a, Jean-Christophe Blancon a, Jacky Even a, Pulickel Ajayan a, Muhammad Alam a, Mercouri Kanatzidis a, Aditya Mohite a
Affiliations
a, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
b, Rice University, Department of Material Science and Nanoengineering, US
c, Purdue University, West Lafayette, Indiana 47907
d, Fonctions Optiques pour les Télécommunications (FOTON), UMR 6082, CNRS, INSA Rennes, Université de Rennes 1, France
e, Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208, USA
Abstract

The dynamic nature of hybrid perovskite crystal structure has enabled unusual optoelectronic properties. Subtle changes the structure can lead to dramatic changes in optical and electronic properties of perovskite based materials. In addition, external stimuli (light or electric field) significantly impacts the properties all the way from the molecular to the macroscale. While such a dynamic nature of the structure poses challenges using those material for device operation but also offer opportunity to discover new functionalities. Therefore, understanding the interplay between structure, light and electrical field using in-situ correlated measurements is critical not only for understanding optoelectronic transport processes, and but also for elucidating design principles for operation of perovskite based devices.

In my talk, I will introduce our study on the correlation of perovskite structure and deformation in response to external stimulation (e.g. light and electrical field) to the device operation in perovskite based optoelectronic devices. Using correlated in-situ structure and transport measurements, I will focus on understanding these complex effects arising from the interaction between structure, light and field during perovskite cell operation in both 3D and 2D systems. Briefly, in a 3D perovskite system, we discover that continuous light illumination leads to a uniform lattice expansion in hybrid perovskite thin-films, which is critical for obtaining high-efficiency photovoltaic devices, boosting the power conversion efficiency from 18.5% to 20.5% in a planar perovskite solar cell. This is a direct consequence of lattice strain relaxation and increase in the crystallite size that dramatically suppresses the interface non-radiative recombination, resulting in enhanced photovoltage and photocurrent collection near low field. Similar studies on Ruddlesden-Popper 2D perovskites, a naturally formed quantum-well system, elucidates that the overall power conversion efficiency of solar cells is limited by the internal structure and built-in internal electrical field.

Our results directly connect the electronic and optical processes with the structural properties and provides guidance on design principles perovskite based materials for high-efficiency and stable optoelectronic devices.

11:30 - 12:00
Session-I5
Stoumpos, Constantinos
Northwestern University
Halide Perovskites: Unconventional High-Performance Semiconductors
Constantinos Stoumpos
Northwestern University, US
Authors
Constantinos Stoumpos a
Affiliations
a, Northwestern University, Department of Chemistry, K114 2145 Sheridan Road Evanston, IL 60208, US
Abstract

Halide perovskites is an emerging class of high performance semiconductors which operate in the visible and infrared energy range. These materials were brought back from indifference in the last 5 years owing to the development of efficient photovoltaic devices, spearheaded by CH3NH3PbI3. Starting from the modest 3% in 2009, halide perovskites have evolved to a record power-conversion-efficiency of over 22%, thus representing the fastest developing solar cell technology known to date. The remarkable physical properties of the halide perovskites stem from their unique electronic structure, which lends the semiconductors high absorption coefficients and charge-carrier mobilities.

In this talk I will outline the compositional space of the halide perovskites, AMX3, (A+ = Cs, CH3NH3, HC(NH2)2); (M2+ = Ge, Sn, Pb); (X- = Cl, Br, I) and explain the structural chemistry of the materials, from “perovskitoids” to “hollow” perovskites. I will discuss how small changes in the crystal structure can significantly alter the optical, electrical and electronic properties of the perovskites and I will elaborate on how these can be controlled by subtle modifications in their chemical synthesis. I will further describe how these materials can be applied in functional devices, tackling the problems of i) toxicity -by substituting the toxic Pb metal- and of ii) environmental stability -by employing the two dimensional layered perovskites-.

12:00 - 12:30
Session-I6
Zhao, Yixin
Shanghai Jiao Tong University, CN
High Performance All-inorganic CsPbI3 Perovskite Stabilized by (110) Oriented 2D Perovskite
Yixin Zhao
Shanghai Jiao Tong University, CN
Authors
Yixin Zhao a
Affiliations
a, Shanghai Jiao Tong University, CN
Abstract

All-inorganic halide perovskites without volatile compounent could exhibit better stability than organic-inorganic halide perovskites. Among them, α-CsPbI3 with the most suitable band gap for tandem solar cell application faces an issue of phase instability under ambient conditions and requirment of high temperature annealing for crystallization. We discovered that the I excess precursor of PbI2.xHI (x>1.2)could help realize a low temperature crystallization of α-CsPbI3. To further enhence their room temperature stability, a small amount of (11) oriented 2D EDAPbI4 perovskite containing ethylene diamine (EDA) cation stabilizes the α-CsPbI3 to avoid the undesirable formation of the non-perovskite delta phase. Moreover, the 2D perovskite of EDAPbI4 not only facilitate the formation of α-CsPbI3 perovskite films exhibiting high phase stability at room temperature for months and at 100 °C for >150 h, but corresponding α-CsPbI3 perovskite solar cells (PSCs) also display highly reproducible efficiency of 11.8%, a record for all-inorganic lead halide PSCs. Therefore, using the bication EDA presents a novel and promising strategy to design all-inorganic lead halide PSCs with high performance and reliability.

12:30 - 12:40
Industrial talk ZAHNER
12:45 - 14:00
Lunch
Session A1
Chair: Claudine Katan
14:00 - 14:15
A1-O1
Shao, shuyan
University of Groningen
Sn-based Hybrid Perovskite Solar Cells with 9% Efficiency
shuyan Shao
University of Groningen, NL
Authors
Shuyan Shao a, Jian Liu a, Giuseppe Portale a, Hong-Hua Fang a, Graeme R. Blake a, Gert H. ten Brink a, L. Jan Anton Koster a, Maria Antonietta Loi a
Affiliations
a, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, The Netherlands
Abstract

The low power conversion efficiency (PCE) of tin based perovskite solar cells (HPSCs) is mainly attributed to the high background carrier density due to a high density of intrinsic defects such as Sn vacancies and oxidized species (Sn4+) that characterize Sn-based HPSCs. Herein, we report on the successful reduction of the background carrier density by more than one order of magnitude by depositing near-single-crystalline formamidinium tin iodide (FASnI3) films with the orthorhombic a-axis in the out-of-plane direction. Using these highly crystalline films, obtained by mixing a very small amount (0.08 M) of layered (2D) Sn perovskite with 0.92 M (3D) FASnI3, we achieve for the first time a PCE as high as 9.0% in a planar p-i-n device structure. These devices display negligible hysteresis and light-soaking, as they benefit from very low trap-assisted recombination, low shunt losses and more efficient charge collection. This represents a 50% improvement in PCE compared to the best reference cell based on a pure FASnI3 film using SnF2 as a reducing agent.

 

14:15 - 14:30
A1-O2
Menendez Proupin, Eduardo
Universidad de Chile
Hole-electron asymmetry in diffusion pathways induced by ferroelectric nanodomains in CH3NH3PbI3
Eduardo Menendez Proupin
Universidad de Chile, CL

I was born in Cuba, in 1972. I studied physics at Havana University, completing my PhD in 2001. In 2003 I moved to Chile. I joined the University of Chile in 2004.  I am interested in the applications of computer simulation of the atomic scale to the prediction and elucidation of materials properties. I have expertise in calculations of electronic structure, molecular dynamics, elastic properties, phonons, optical spectra and core-level spectra. Most of my electronic structure calculation are based on density functional theory, but I have also used wavefunction methods. Currently, am interested in semiconductor materials for photovoltaic devices, such as CdTe and metal-organic halide perovskites.

Authors
Eduardo Menéndez-Proupin a, Ana L. Montero-Alejo a, Pablo Palacios a, Perla Wahnón a, José C. Conesa a
Affiliations
a, Universidad de Chile, Las Palmeras 3425, Santiago, CL
b, Universidad Politécnica de Madrid, Avenidad Complutense s/n, Madrid, ES
c, Instituto de Catálisis y Petroleoquímica, CSIC, Marie Curie 2, Madrid, ES
Abstract

We investigate the possibility that formation of ferroelectric domains in CH3NH3PbI3 can separate the diffusion pathways of electrons and holes. This hypothesis has been proposed [1] to explain the large recombination time and the remarkable performance of the solar cells of hybrid perovskites. We find that a two-dimensional hole confinement in CH3NH3PbI3 is possible under room temperature conditions. Our models of the tetragonal phase show that the alignment of dipole layers of organic cations induces the confinement of holes but not of electrons. We find that holes can localize on PbI2 planes closest to CH3 groups. This behavior does not change even by varying the strength of the ordered dipoles. The confinement of holes is enhanced by the deformation of the inorganic PbI3 sublattice. For the conduction band electrons, the inorganic sublattice distortions counteract the effect of the oriented organic dipoles preventing the localization of the electrons. The positive charges of CH3NH3+ cations, at the locations driven by its aspherical shape, are responsible of the electron-hole asymmetry. We find that spherical cations like Cs+ cannot provide this effect. The localization/delocalization pattern in real space is reproduced in the reciprocal space. The dispersion of the top valence band is reduced in the directions perpendicular to the confinement planes, while the lowest conduction band remains isotropic.

[1] J. M Frost et al., Nano Lett. (2014), 14, 2584–2590.

14:30 - 14:45
A1-O3
Cossi, Maurizio
Università del Piemonte Orientale “A. Avogadro”
Ab Initio Design of 2D Hybrid Organohalide Perovskites with Tunable Band Gap
Maurizio Cossi
Università del Piemonte Orientale “A. Avogadro”, IT
Authors
Maurizio Cossi a, Alberto Fraccarollo a, Leonardo Marchese a
Affiliations
a, Università del Piemonte Orientale “A. Avogadro”, Viale T. Michel 11, Alessandria, 15121, IT
Abstract

Different series of layered perovskites, based on lead and tin tetrahalide sheets intercalated by organic cations, are modeled with ab initio techniques. The structures are optimized at the DFT level, with inclusion of dispersion contributions, in several symmetry groups or without symmetry constraints.

The electronic properties (mainly, band structures and gaps) are computed at the state-of-the-art level with inclusion of spin-orbit-coupling (SOC) and post-DFT (GW) corrections.

A number of structure/properties relationships are discussed: in particular, we describe how the nature of the intercalated cations influences the perovskite band gap either directly or indirectly (through geometrical changes, e.g. to the interlayer distance).

Then we can sketch what combination of inorganic and organic counterparts can be used to select the desired electronic properties.

For photovoltaic applications, the computed band gaps of these layered systems are often too large. However, some of the modeled systems exhibit smaller gaps, sometimes as low as 1.4 eV, due to the electronic effects of suitable doubly charged cations: we discuss such effects, as well as effective molecular descriptors to predict the formation of such low band gap perovskites.

14:45 - 15:00
A1-O4
Hirsch, Lionel
University of Bordeaux, CNRS, Bordeaux INP, IMS, UMR 5218
Experimental evidence for proton tunneling in methylammonium lead triiodide perovskites
Lionel Hirsch
University of Bordeaux, CNRS, Bordeaux INP, IMS, UMR 5218, FR
Authors
Lionel Hirsch a, Yan-Fang Chen a, Yu-Tang Tsai a, Dario M. Bassani a
Affiliations
a, CNRS/Univ. Bordeaux
Abstract

Hybrid organic−inorganic perovskite (HOIP) solar cells are a promising technology that combines the advantage of solution process technology with high power conversion efficiency (PCE), still in constant improvement. This success story started in 2009 with the report by Kojima et al. of a HOIP solar cell with 3.8% PCE. The highest certified PCE is currently at 22.1% in a single-junction device. While the toxicity of lead and long-term device stability are still major obstacles to be overcome for their widespread deployment in solar cells and electroluminescent devices, HOIPs represent a class of materials that combine promising electronic properties with solution processing technology.

Perovskites in general are known to possess ionic conductivity and ion movement has been postulated to be directly or indirectly responsible for their lack of long-term stability and unusual behavior, including hysteresis. Therefore, understanding ion migration in perovskites is of major importance in improving their performance. Ion movement in HOIPs may occur extrinsically, i.e. from one of the contacts, or take the form of ion migration, where an ion is displaced from an occupied to a vacant site. Numerous studies confirmed the rotational movement of the MA ions within the inorganic cage formed by the PbI2 octahedra, which has been associated to the temperature and frequency dependence of the complex permittivity.[1]

To test the relationship between MA rotation and the frequency dispersion in the dielectric response in HOIP materials, we conducted a series of experiments in which the hydrogen atoms in MAI were selectively substituted with deuterium. Our results unambiguously demonstrate that MA migration or rotation is not directly responsible for the frequency dependence of the dielectric constant at intermediate frequencies at 1 – 3 kHz.[2] Instead, we observe that deuteration of the ammonium group leads to a large inverse kinetic isotope effect and show that proton tunneling is responsible for the mid-range frequency-dependence of the dielectric constant in HOIP materials. Deuteration of the methyl group in MA induces a normal secondary KIE that is consistent with these findings

 

[1] Frost, J. M.; Walsh, A. Acc. Chem. Res. 2016, 49, 528-535

[2] Y-F Chen, Y-T Tsai, L. Hirsch and D. M. Bassani, J. Am. Chem. Soc., Article ASAP DOI: 10.1021/jacs.7b09526

15:00 - 15:15
A1-O5
Boyer-Richard, Soline
UMR FOTON
Tight-Binding modeling of CsPbI3 in several perovskite phases
Soline Boyer-Richard
UMR FOTON
Authors
Soline Boyer-Richard a, Laurent Pédesseau a, Arthur Marronnier a, Guido Roma a, Boubacar Traoré a, Claudine Katan a, Yvan Bonnassieux a, Jean-Marc Jancu a, Ram Seshadri a, Constantinos Stoumpos a, Mercouri Kanatzidis a, Jacky Even a
Affiliations
a, Laboratoire FOTON, INSA, Université Rennes, F35708 Rennes, France
b, Institut des Sciences Chimiques de Rennes (ISCR), UMR 6226 Université de Rennes 1 - CNRS, France
c, LPICM, CNRS, Ecole Polytechnique, Université Paris-Saclay, France
d, DEN - Service de Recherches de Métallurgie Physique, CEA, Université Paris-Saclay, France
e, Materials Research Laboratory, University of California Santa Barbara, CA 93106-5121, USA
f, Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208, USA
Abstract

Among perovskite solar cells, fully inorganic perovskite solar cells can compete as a stable and efficient alternative to hybrid cousins, with the recent report of a 13.4% efficient CsPbI3 perovskite quantum dot solar cell. Using synchrotron X-ray powder diffraction (SXRD), the detailed experimental structures of the three perovskite-phases of CsPbI3 (gamma at 325K, beta at 510K and alpha at 645K) have been recently reported. Based on these experimental results, we investigate the electronic properties of all three phases using a recently developed symmetry-based tight-binding (TB) model [1] as well as DFT calculations including both spin-orbit coupling (SOC) and many-body (GW approximation) effects.

In fact, TB models afford an atomic-scale description to computing various properties, including distorted structures, at a significantly reduced computational cost compared to first-principles approaches. It allows tackling more difficult issues in terms of size, with complex heterostructures, nanostructures or composite materials, as well as properties with a great diversity of physical phenomena.

The original empirical sp3 tight-binding (TB) model has been built for the reference Pm3m cubic phase of halide perovskite structures of general formula ABX3 and the TB parameters have been calibrated using available experimental and theoretical data for MAPbI3 (MA=CH3NH3+) [1]. To investigate less symmetric structure, such as the beta and gamma phases of CsPbI3, we show that this model can be extended by means of a simple d-2 Harrisson law, which allows tackling bond length variation. Given that very few experimental results are available on these phases of CsPbI3, we used the initial parameterization performed on MAPbI3. In order to gauge the quality and performances of this TB model, we further performed DFT calculations including both self-consistent GW corrections and relativistic effects (SOC). The band structure obtained with our TB model agrees nicely with results obtained from first-principles calculations. The model is then further exploited to inspect effect related to anharmonicity and results support the hypothesis of dynamical Rashba effects in CsPbI3. We may expect that such a model will be as relevant to the future of perovskite device modeling, as it has proved efficient for conventional semiconductors.

This project has received funding from the European Union’s Horizon 2020 programme, through a FET Open research and innovation action under the grant agreement No 687008.

References: [1] S. Boyer-Richard et al., J. Phys. Chem. Lett. 2016, 7, 3833.

15:15 - 15:30
A1-O6
Tsai, Hsinhan
Stable Light-Emitting Diodes Using Phase-Pure Ruddlesden-Popper Layered Perovskites
Hsinhan Tsai
Authors
Hsinhan Tsai a, b, Wanyi Nie a, Jean-Christophe Blancon a, Constanrinos C. Stoumpos a, Chan M.M. Soe a, Jinkyoung Yoo a, Sergei Tretiak a, Jacky Even a, Aditya Sadhanala a, Jered Crochet a, Giovanni Azzellino a, Roberto Brenes a, Pulickel M. Ajayan a, Vladimir Bulovic a, Samuel D. Stranks a, b, Richard Friend a, Mercuri G. Kanatzidis a, Aditya Mohite a
Affiliations
a, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
b, Rice University, Department of Material Science and Nanoengineering, US
c, Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208, USA
d, Fonctions Optiques pour les Télécommunications (FOTON), UMR 6082, CNRS, INSA Rennes, Université de Rennes 1, France
e, Massachusetts Institute of Technology (MIT), 77 Massachusetts Ave. Cambridge, MA 02139, US
f, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom, JJ Thomson Avenue, 9, Cambridge, GB
Abstract

State-of-the-art light emitting diodes (LEDs) are made from high-purity alloys of III-V semiconductors or small molecules, but high fabrication cost and conplicated synthetic process have limited their widespread use for large area solid-state lighting applications. Here we report efficient and stable LEDs processed from solution with tunable color enabled by using phase-pure two-dimensional (2D) Ruddlesden-Popper (RP) layered perovskites with a formula (CH3(CH2)3NH3)2(CH3NH3)n-1PbnI3n+1 (n=3-5 in this report). By using controlled vertically oriented of crystal in the thin-films that facilitate efficient charge injection and transport, we obtain efficient electroluminescence with a radiance of 35 W Sr-1 cm-2 at 744 nm with an ultra-low turn-on voltage of 1V. Finally, operational stability tests suggest that phase purity is strongly correlated to stability. Phase-pure 2D perovskites exhibit >14 hours of stable operation at peak operating conditions with no droop at current-densities of several Amperes/cm2 in comparison to mixtures of 2D/3D mixture or 3D perovskites, which degrade within minutes.

15:30 - 15:45
A1-O7
LEBLANC, Antonin
MOLTECH-Anjou
Lead and iodide deficient (CH3NH3)PbI3, d-MAPI: the bridge between 2D and 3D hybrid perovskites
Antonin LEBLANC
MOLTECH-Anjou
Authors
Antonin Leblanc a, Nicolas MERCIER a, Magali ALLAIN a, Jens DITTMER a, Vincent FERNANDEZ a, Thierry PAUPORTE a
Affiliations
a, University of Angers, CNRS UMR 6200, MOLTECH-Anjou, Linear Conjugated Systems, UFR Sciences, 2 Bd Lavoiser, Angers, 49045, FR
b, Institut des Molécules et Matériaux du Mans, CNRS UMR 6283, Le Mans Université, Avenue Olivier Messiaen, 72085 Le Mans cedex 9, France
c, Institut des Matériaux Jean Rouxel, UMR-CNRS 6502, Université de Nantes, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3, France
d, Chimie ParisTech, PSL Research University, CNRS, Institut de Recherche de Chimie Paris (IRCP), 11 rue P. et M. Curie, F-75005 Paris, France.
Abstract

The last years, the Hybrid Perovskite solar cells showed a high photoconversion efficiency (PCE) up to 22,7%.[1] The best performances were obtained with the three-dimensional CH3NH3PbI3 and derivatives such as mixed small cations and mixed halogens (Rb,Cs,FA,MA)PbI(3-x)Br(x) compounds, where MA+=methylammonium and FA+=formamidinium.[2]

Very recently, we have discovered a new family of hybrid perovskites, named d-MAPI, which can be prepared as single crystals, crystallized powders and crystallized thin films. A d-MAPI phase is lead and iodide deficient compared to MAPI (CH3NH3PbI3): a (PbI)+ unit being substituted by an organic monocation, while keeping a 3D architecture. By using two kinds of organic cations, the methylammonium and the ethanolammonium (HEA+), a series of d-MAPI compounds whose general formulation is (MA)1-2.48x(HEA)3.48x[Pb1-xI3-x] (0<x<0.20) has been obtained. The substitution of (PbI)+ unit leads to the formation of channels along c axis. Channels of this network can be filled by extra Pb2+ and I- ions and organic cations (when x<0.20) or only by organic cations (when x= 0.20). First experiments using d-MAPI layers for an application as absorber materials in regular FTO/compact-TiO2/meso-TiO2/Perovskite/SpiroOMeTAD/Ag PSCs have shown that d-MAPI (x= 0.10) exhibits a PCE of 6%. Moreover, a relative stability test of thins films of MAPI and d-MAPI (x= 0.10) has revealed that d-MAPI thin films are more stable than the MAPI ones. This new type of hybrid perovskite (A,A’)1+x[Pb1-xX3-x ] (A= MA+, A’= HEA+) offers increased flexibility of its chemical composition with potential substitutions on the A, A’, Pb and X sites.

 

 

References:

[1] NREL efficiency chart: https://www.nrel.gov/pv/assets/images/efficiency-chart.png

[2] Michael Gratzel, Acc. Chem. Res. 2017, 50, 487-491.

[3] Antonin Leblanc, Nicolas Mercier, Magali Allain, Jens Dittmer, Vincent Fernandez, Thierry Pauporté, Angew. Chem. 2017 Oct 27. doi: 10.1002/anie.201710021. Accepted manuscript.

15:45 - 16:00
A1-O8
Bartesaghi, Davide
Delft University of technology
Synthesis and characterization of mixed-metal MAPb1-xMnxI3
Davide Bartesaghi
Delft University of technology, NL
Authors
Davide Bartesaghi a, b, Aniruddha Ray a, Benjamin Feleki a, Martijn Wienk a, Rene Janssen a, Tom Savenije a
Affiliations
a, 1 Department of Chemical Engineering, Delft University of Technology, Delft, Netherlands
b, Materials innovation institute (M2i), 2600 GA, Delft, NL
c, Eindhoven University of Technology, NL
Abstract

Tailoring the physical properties of metal halide ABX3 perovskites by means of compositional engineering is one of the key factors contributing to the development of highly efficient and stable perovskite solar cells. The effect of blending ions at the A-site and X-site of the perovskite lattice has been thoroughly studied, and most efficient perovskite solar cells are now based on mixed-cation, mixed-halide lead perovskites. On the contrary, partial replacement of lead at the B-sites is relatively less explored. Besides the possible beneficial effects on the materials properties, blending other metals in the perovskite structure can mitigate the toxicity of corresponding cells. Here, we investigate the partial substitution of Pb2+ with Mn2+ in methylammonium lead iodide (MAPbI3). We developed a solution-based procedure to fabricate uniform and pin-hole free thin films of mixed metal MAPb1-xMnxI3 perovskite, which we used to fabricate single junction solar cells. Although Mn2+ ions have a size that can potentially fit in the B-sites of MAPbI3, using a combination of XRD and XPS we show that only ca. 3 to 10% of Pb2+ can be replaced by Mn2+. Further addition results in amorphous Mn-rich impurities concentrated at the bottom of the perovskite film. We characterized the optoelectronic properties of MAPb1-xMnxI3 for x in the range 0 – 0.1 by means of UV-vis absorption and photoluminescence spectroscopy and by time-resolved microwave conductance measurements. The bandgap of MAPb1-xMnxI3 is not substantially different from that of MAPbI3. However, we demonstrate that incorporation of Mn2+ in the perovskite lattice negatively impacts the transport and recombination of charges. The mobility of electrons and holes decreases by a factor 6 when 3% of Pb2+ is replaced with Mn2+. For the same amount of Pb2+ replacement, the photoluminescence lifetime is significantly decreased. Reduction in mobility and lifetime of charge carriers severely limits the performance of MAPb1-xMnxI3 solar cells. The best device fabricated for x = 0.03 does not exceed a power conversion efficiency of 2%.

 

Session B1
Chair: Wanyi Nie
14:00 - 14:15
B1-O1
Geffroy, Bernard
CEA
Effect of Halide ion migration on current-voltage hysteresis in CH3NH3PbI3-xClx based perovskite solar cells
Bernard Geffroy
CEA, FR
Authors
Bernard Geffroy a, Heejae Lee a, Sofia Gaiaschi a, Patrick Chapon a, Arthur Marronnier a, Denis Tondelier a, Yvan Bonnassieux a, Jean-Eric Bourée a
Affiliations
a, LICSEN, NIMBE, CEA, CNRS, Université Paris-Saclay, CEA Saclay, F-91191 Gif-sur-Yvette, France
b, LPICM, CNRS, Ecole Polytechnique, Université Paris-Saclay, F-91128 Palaiseau, France
c, Horiba France S.A.S., CS 45002, 91120 Palaiseau, France
Abstract

Hybride perovskite solar cells (PSCs) have rapidly emerged as a promising candidate for the next generation photovoltaics with power conversion efficiencies (PCE) attaining 22.7%. Low temperature solution processing, low cost raw material and relative insensitivity to intrinsic point defects are some of the attractive qualities of this emerging class of devices. But one of the major obstacles for the commercialization of PSCs lies in the long-term stability of the perovskite films subjected to different environmental conditions such as temperature, humidity and illumination.

In this work, we focused on experimental evidence of halide ion migration in CH3NH3PbI3-xClx based solar cells and its effect on current-voltage hysteresis for which various mechanisms have been proposed.

The inverted planar structure adopted for the PSCs was: glass/ITO/PEDOT:PSS/perovskite/PCBM/Ag. The perovskite thin films were deposited by 1-step spin-casting process and the PEDOT:PSS (hole-transporting layer) and PCBM (electron-transporting layer) layers were deposited by spin-coating process. The PCE under 1 sun equivalent illumination reached 12.7% for the best cell of a series of 10 samples with an active area of 0.28 cm2. By using glow discharge optical emission spectrometry (GD-OES) we have shown that halide ions (I- and Cl-) migrate inside the perovskite films under an applied bias in both directions, the time of migration being typically 2 min. Furthermore no migration of lead and nitrogen ions was observed in the same time scale.

Under dark conditions, thus without any photo-generated carriers, we observed a current-voltage hysteresis versus voltage scanning rate and temperature. The activation energy value of 0.253 eV derived from the Nernst-Einstein relation above 264 K, for which the perovskite phase is tetragonal, indicates that the conduction is dominated by the ions. The conduction is ascribed to the migration of anion vacancies, which is well known in the perovskite-type halides such as CsPbCl3 or CsPbBr3. These experiments prove that there is a direct link between halide ion migrations in CH3NH3PbI3-xClx based perovskite thin films and current-voltage hysteresis.

14:15 - 14:30
B1-O2
Mora-Seró, Iván
Institute of Advanced Materials (INAM), Universitat Jaume I
Hole Selective Contacts in Perovskite Solar Cells
Iván Mora-Seró
Institute of Advanced Materials (INAM), Universitat Jaume I, ES

Iván Mora-Seró (1974, M. Sc. Physics 1997, Ph. D. Physics 2004) is researcher at Universitat Jaume I de Castelló (Spain). His research during the Ph.D. at Universitat de València (Spain) was centered in the crystal growth of semiconductors II-VI with narrow gap. On February 2002 he joined the University Jaume I. From this date until nowadays his research work has been developed in: electronic transport in nanostructured devices, photovoltaics, photocatalysis, making both experimental and theoretical work. Currently he is associate professor at University Jaume I and he is Principal Researcher (Research Division F4) of the Institute of Advanced Materials (INAM). Recent research activity was focused on new concepts for photovoltaic conversion and light emission based on nanoscaled devices and semiconductor materials following two mean lines: quantum dot solar cells with especial attention to sensitized devices and lead halide perovskite solar cells and LEDs, been this last line probably the current hottest topic in the development of new solar cells.

Authors
Iván Mora-Seró a
Affiliations
a, Institute of Advanced Materials (INAM), Universitat Jaume I, 12006 Castellón de la Plana, Castellón, España, Castellón de la Plana, ES
Abstract

Hybrid Halide Perovskite are probably the current hottest materials for photovoltaics. Certified photoconversion efficiencies as high as 22.7% has been reported. Beyond the intrinsic goodness of the halide perovskite materials for the light absorption, efficient carrier transport and low non-radiative recombination, it is not enough to produce a high efficient device and the role of electron and hole selective contacts is dramatic. In this presentation, we will show the effect of different kind of electron selective contacts molecular, polymeric and inorganic. New molecular inorganic contacts will be introduced and compared with the most standard hole selective contact, the Spiro-OMeTAD that present problems for long stability devices. Cells prepared with different selective contact have been optoelectronicaly analyzed by impedance spectroscopy and photoluminescence decay in order to evaluate the charge transfer rate and carrier recombination at the interface. The use of additives in order to increase the performance of hole transporting contact will be also discussed.

 

14:30 - 14:45
B1-O3
Abdi Jalebi, Mojtaba
University of Cambridge
Enhanced optoelectronic quality of metal halide perovskite via additive engineering
Mojtaba Abdi Jalebi
University of Cambridge, GB
Authors
Mojtaba Abdi-Jalebi a, Zahra Andaji-Garmaroudi a, Stefania Cacovich a, Giorgio Divitini a, Samuel D. Stranks a, Richard H. Friend a
Affiliations
a, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom, JJ Thomson Avenue, 9, Cambridge, GB
b, Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FY, GB
Abstract

Metal halide perovskites display remarkable intrinsic properties including high absorption coefficient, sharp and tunable bandedge, long charge carrier diffusion length, low trap densities, high luminescence quantum yields, and the photon recycling capability. These materials have shown a relatively fast evolution in the performance of both light emitting diodes and solar cells (e.g. power conversion efficiency (PCE) exceeding 22%) since their first appearance in the devices. However, non-radiative losses originating from sub gap charge carrier trap states on the grain surfaces (e.g. halide vacancies) and low luminescence efficiency of metal halide perovskite in a complete device are the main barriers against reaching the efficiency limit in both solar cells and LEDs.

Here, we explore the impact of doping with different cation additives on the optoelectronic quality and structural properties of metal halide perovskite. We find significant enhancement in both micro-photoluminescence and photoluminescence quantum efficiency (e.g. internal yields exceeding 95%) while maintaining high mobilities over 42 cm2V-1s-1, giving the elusive combination of both high luminescence and excellent charge transport. We also demonstrate the inhibition of transient photo-induced ion migration processes via decorating the grain boundaries and interfaces with self-assembly passivating species. We validate these enhancements in operating solar cells where we obtain a remarkable increase in PCE along with entire elimination of hysteresis upon addition of cation additives. We also analyse the local structural changes and the corresponding effects on the electronic structure and chemical bonding of metal-iodide in the additive based perovskite using periodic DFT calculations where the corresponding negative formation energies confirm the feasibility of formation of the doped structures.

Our findings pave the way for further improvements in the optoelectronic quality of metal halide perovskite thin films and subsequent devices. It also reveals promising approaches to eliminate non-radiative losses and maximize luminescence efficiency in metal halide perovskite. 

14:45 - 15:00
B1-O4
Yasin, Amrita
Swansea University
Modification of TiO2/CH3NH3PbI3 interface with KCl, KI, or KBr in planar perovskite solar cells
Amrita Yasin
Swansea University, GB
Authors
Amrita Yasin a, Adam Pockett a, Catherine De Castro a, James McGettrick a, Cecile Charbonneau a
Affiliations
a, SPECIFIC IKC, College of Engineering, University of Swansea, Swansea, U.K
Abstract

This work showcases our research on modification of compact TiO2 electron transport layers (ETLs) at the TiO2/CH3NH3PbI3 interface for application in planar lead halide perovskite solar cells. Compact TiO2 ETLs were formed via spraying of a commercially available titanium diisopropoxide bis(acetylacetonate) precursor on fluorine-doped tin oxide (FTO) glass followed by annealing at 550 C. These layers were subsequently spin coated with aqueous solutions of 10mM and 40mM of KX (X = Cl-, I-, Br-, prior to CH3NH3PbI3 deposition. Presence of potassium and X- ions on the TiO2 surface is evident via X-ray photoelectron spectroscopy (XPS) analysis, and individual crystals can be seen on the modified TiO2 films via scanning electron microsope (SEM) images. Furthermore, the KX crystals provide a template for denser crystallization of the overlying CH3NH3PbI3 layers resulting in higher perovskite coverage and reduction in pinhole density, as compared to untreated TiO2/CH3NH3PbI3 films. For KCl and KI treated layers the CH3NH3PbI3 grain size is higher for 40 mM compared to 10 mM treatment; however for KBr treated layers, the grain size does not change significantly between the two treatments. The absorbance of TiO2/KX/ CH3NH3PbI3 films does not show much difference, however photoluminescence spectra show improved photoluminescence quenching for the all modified TiO2/KX/ CH3NH3PbI3 films compared to the TiO2/CH3NH3PbI3. Preliminary results show that against a stabilized power conversion efficiency of 8.25% in the reverse direction for unmodified planar devices, KI modified devices reach up to 11.57%, followed by KBr at 10.22%. and finally KCl at 8.09% .

15:00 - 15:15
B1-O5
Fang, Hong-Hua
University of Groningen
Long-lived Hot-carrier Emission and Large Blue Shift in the Thin Film of FASnI3
Hong-Hua Fang
University of Groningen, NL
Authors
Hong-Hua Fang a, Sampson Adjokatse a, Shuyan Shao a, Jacky Even a, Maria Loi a
Affiliations
a, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen, 9747 AG, NL
b, Fonctions Optiques pour les Technologies de l’Information, FOTON UMR 6082, CNRS, INSA de Rennes, Rennes 35708, France
Abstract

Slowed photoexcited carrier cooling is highly desirable for developing hot-carrier solar cell, as it allows potential efficiency close to the thermodynamical limit in ideal conditions. Here, the optoelectronic properties of FASnI3 as a function of excitation density and temperature are investigated. Hot-carrier light emission in tin-based hybrid perovskite (FASnI3) with lifetime > 1 nanosecond is observed. An unusual large blue shift of the time-integrated photoluminescence with increasing the excitation power (150 meV at 24 K, and 75 meV at 293 K) is displayed. On the basis of an analysis of energy- and time-resolved photoluminescence, these phenomena are likely associated with slow hot carrier relaxation and state-filling of band edge states. Noteworthy, we measured highly efficient hot carrier emission also under continuous-wave excitation, which is a fundamental step towards hot carrier solar cells. The observation of these phenomena provides important physical insight into the relatively unexplored excited-state character of tin halide perovskites, which is essential for the further development of lead-free solar cells and other optoelectronic devices based on hot carriers.

15:15 - 15:30
B1-O6
Tarasov, Alexey
Lomonosov Moscow State University
Strategic advantages of reactive polyiodide melts for scalable perovskite photovoltaics
Alexey Tarasov
Lomonosov Moscow State University, RU
Authors
Alexey Tarasov a, b, Ivan Turkevych a, Said Kazaoui a, Nikolai Belich a, Aleksei Grishko a, Sergey Fateev a, Andrey Petrov a, Michael Graetzel a, Eugene Goodilin a
Affiliations
a, 3Laboratory of New Materials for Solar Energetics, Faculty of Materials Science, Lomonosov Moscow State University (MSU)
b, Chemical Materials Evaluation and Research Base (CEREBA), Higashi 1-1-1, AIST Central 5-2, Tsukuba, Ibaraki, 305-8565
c, 2National Institute of Advanced Industrial Science and Technology (AIST)
d, 6Laboratory of Photonics and Interfaces, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL)
e, 5Chemistry Department, Faculty of Materials Science, Lomonosov Moscow State University (MSU)
Abstract

We present a new formation strategy of hybrid lead halide perovskites using novel reactants – reactive polyiodide melts (RPM). These compounds, namely, CH3NH3I3+x and HC(NH2)2I3+x, are liquid at room temperature and exhibit extremely high reactivity towards metallic lead and lead compounds (e.g. PbI2, PbO). As a result, perovskite crystals and thin films can be easily obtained through the direct reaction between reactive polyiodide melts and metallic lead.

RPM can be readily prepared by mixing powders of I2 with MAI (FAI). The reaction proceeds instantly at room temperature and results in a highly-viscous liquid. Due to its unique composition the RPM acts simultaneously as a liquid medium and a highly reactive precursor that swiftly converts metallic lead into perovskite. This new approach allows fabrication of high quality polycrystalline perovskite films with micron-size grains without use of solvents and heating. The perovskite solar cells made via this approach yield a solar to electric power conversion efficiency (PCE) of over 12% even without optimization of the film deposition procedure.

We demonstrate applicability of this method for the fabrication of highly uniform perovskite films with micron-size grains over large substrates of 10x10 cm2 and 20x30 cm2, including flexible supports. The proposed strategy has a high potential for industrial scale mass-production of perovskite modules including roll-to-roll manufacturing on flexible substrates, because the initial lead thin films can be easily deposited in a highly controlled way by various methods, such as evaporation, sputtering, electrochemical deposition, etc.

We also demonstrate that mixed perovskites MAxFA1-xPbI3-xBrx can be easily obtained using RPM with various compositions. In particular, single-phase MA-stabilized FAPbI3 films with long charge carrier lifetimes were obtained. In addition, using this approach, we  show that the perovskite films with the arbitrary pattern can be obtained by applying the mold with the pattern against the metallic lead film with RPM deposited on top of it. This approach allows one to evenly distribute the highly reactive melt over the substrate and obtain the smooth layer of perovskite.

[1] Petrov A.A. et al. New formation strategy of hybrid perovskites via room temperature reactive polyiodide melts // Mater. Horiz. 2017. doi: 10.1039/C7MH00201G

A.B., E.G., A.P. and A.G. acknowledges the financial support of this study from Ministry of Education and Science of Russian Federation, project identification number: RFMEFI60716X0147

15:30 - 15:45
B1-O7
Hossain, Ihteaz Muhaimeen
Institute of Microstructure Technology, Karlsruhe Institute of Technology
Printable Low-temperature TiO2 Nanoparticles for High Efficiency Stable Perovskite Solar Cells
Ihteaz Muhaimeen Hossain
Institute of Microstructure Technology, Karlsruhe Institute of Technology, DE
Authors
Ihteaz Muhaimeen Hossain a, b, Florian Mathies a, Tobias Abzieher a, Somayeh Moghadamzadeh a, Bryce S. Richards a, b, Uli Lemmer a, b, Damien Hudry a, Ulrich W. Paetzold a, b, Afshin Hadipour a
Affiliations
a, Institute of Microstructure Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, DE
b, Light Technology Institute, Karlsruhe Institute of Technology (KIT), Engesserstrasse 13, Karlsruhe, 76131, DE
c, InnovationLab GmbH, Heidelberg, Heidelberg, DE
d, Imec vzw, Kapeldreef 75, B-3001 Leuven
Abstract

In recent years, there has been an increasing interest in the field of perovskite solar cells (PSCs) that led to an unprecedented power conversion efficiency (PCE) of >22 % on the lab-scale devices. State-of-the-art PSCs utilize high temperature (> 450 °C) processed TiO2 as their electron transport layer. However, this high temperature processing remains a key challenge to upscaling techniques such as roll-to-roll processing on flexible substrates or inkjet printing on large area devices. In this work, we tackle this challenge using TiO2 nanoparticles (TiO2-np) instead. The synthesis process allows precise control over several variables such as particle size, doping and dispersing capability in different solvents. Here, we show high performance solar cells achieved using not only with spin-coated CH3NH3PbI3 (initial: >19 %, stabilized: 18.2 %) but also with other perovskites absorber layers that includes co-evaporated CH3NH3PbI3 (initial: >17 %) and triple cation perovskite, Cs0.1(MA0.17FA0.83)0.9Pb(I0.83Br0.17)3 (initial: >19 %). Moreover, we show that these TiO2-np can be used to achieve efficient PSCs both in thin (30 nm) and thick (75 nm) layer configurations. In addition, the doping of the TiO2-np with niobium (Nb) results in a significant improvement for the thicker layers. Furthermore, when dispersed in appropriate solvents, we demonstrate both inkjet printing and slot die coating processes for the TiO2-np. PSCs fabricated with such processes show high initial PCE of >17%, paving the way for high throughput and digitally printed PSCs.

15:45 - 16:00
B1-O8
Ghosh, Dibyajyoti
Physics, University of Bath
Good Vibrations: Locking of Octahedral Tilting in Mixed-Cation Iodide Perovskites for Solar Cells
Dibyajyoti Ghosh
Physics, University of Bath, GB
Authors
Dibyajyoti Ghosh a
Affiliations
a, Physics, University of Bath, Department of Physics, University of Bath, Bath, 0, GB
Abstract

 

Metal halide perovskite solar cells have rapidly emerged as leading contenders in photovoltaic technology. Compositions with a mixture of cation species on the A-site show the best performance and have higher stability. However, the underlying fundamentals of such enhancement are not fully understood. Here, we report new atomic-scale insights into the local structures and dynamics of mixed A-cation compositions based on formamidimium lead iodide (CH(NH2)2PbI3 ) doped with Cs+, Rb+ and MA+. Our specific findings include the first indication that substitution of low concentrations of smaller cations on the A-site in CH(NH2)2PbI3 results in a global ‘locking’ of the PbI6 octahedra tilting and reduced lattice dynamics. A key impact of this feature is that the rotational or tumbling motion of the CH(NH2)2+ molecular ion in a locked cage is severely restricted. We discuss the impact of locking on the photovoltaic performance and stability. The results presented here provide key fundamental insights into the origin of the significant enhancements in solar cell performance achieved by using mixed A-site species in lead halide perovskites and will have wide impact on future design strategies.

Reference : Ghosh et al. ACS Energy Lett. 2017, 2, 2424

 
Wed Feb 28 2018
Session G2
Chair: Aditya Mohite
09:00 - 09:30
G2-I1
Loi, Maria Antonietta
University of Groningen
Sn-based Hybrid Perovskite Solar Cells from solar cells to hot electrons
Maria Antonietta Loi
University of Groningen, NL

Maria Antonietta Loi studied physics at the University of Cagliari in Italy where she received the PhD in 2001. In the same year she joined the Linz Institute for Organic Solar cells, of the University of Linz, Austria as a post doctoral fellow. Later she worked as researcher at the Institute for Nanostructured Materials of the Italian National Research Council in Bologna Italy. In 2006 she became assistant professor and Rosalind Franklin Fellow at the Zernike Institute for Advanced Materials of the University of Groningen, The Netherlands. She is now full professor in the same institution and chair of the Photophysics and OptoElectronics group. She has published more than 130 peer review articles in photophysics and optoelectronics of nanomaterials. In 2012 she has received an ERC starting grant.

Authors
Maria Antonietta Loi a
Affiliations
a, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, The Netherlands
Abstract

Thanks to the intensive research efforts of a large scientific community over the past 7 years, lead (Pb)-based hybrid perovskite solar cells have achieved an impressive power conversion efficiency. Large improvements in the thermal and photo stability of this kind of solar cell by using more stable precursors, and robust hole/electron transport layers have been achieved. Despite these outstanding accomplishments, the toxicity of lead causes concerns about the possible large-scale utilization of this new type of solar cell.

Among the various alternatives to lead, Sn has been recognized to have a great potential, as the Sn-based hybrid perovskites display excellent optical and electrical properties such as high absorption coefficients, small exciton binding energies and high charge carrier mobilities. In my talk I will show that Sn-based perovskites display evidences of photoluminescence from hot-carriers with unexpectedly long lifetime. The asymmetry of the PL spectrum at the high-energy edge, is accompanied by the unusually large blue shift of the time-integrated photoluminescence with increasing the excitation power. These phenomena are associated with slow hot carrier relaxation and state-filling of band edge states.

I will further show all-tin-based hybrid perovskite solar cells with efficiencies of up to 9%. This record result is obtained with the addition of trace amount of 2D tin perovskite, which initiates the homogenous growth of highly crystalline and oriented FASnI3 grains at low temperature.

09:30 - 10:00
G2-I2
Shen, Qing
The University of Electro-Communications
Effects of Interface Engineering on Photoexcited Carrier Dynamics and Photovoltaic Performance in Perovskite Solar Cells
Qing Shen
The University of Electro-Communications, JP

Prof. Qing Shen received her Bachelor’s degree in physics from Nanjing University of China in 1987 and earned her Ph.D. degree from the University of Tokyo in 1995. In 1996, she joined the University of Electro-Communications, Japan and became a full professor in 2016. In 1997, she got the Young Scientist Award of the Japan Society of Applied Physics. In 2003, she got the Best Paper Award of the Japan Society of Thermophysical Properties and the Young Scientist Award of the Symposium on Ultrasonic Electronics of Japan. In 2014, she got the Excellent Women Scientist Award of the Japan Society of Applied Physics. She has published nearly 140 peer-reviewed journal papers and book chapters. Her current research interests focus on solution processed nano-materials and nanostructures, semiconductor quantum dot solar cells and perovskite solar cells, and especially the photoexcited carrier dynamics (hot carrier cooling, multiple exciton generation, charge transfer at the interface) in perovskite solar cells, quantum dot and dye sensitized solar cells, organic-inorganic hybrid solar cells.

Authors
Qing Shen a, Yuhei Ogomi a, Chao Ding a, Taro Toyoda a, Kenji Yoshino a, Takashi Minemoto a, Shuzi Hayase a
Affiliations
a, The University of Electro-Communications, Japan
b, Kyushu Institute of Technology, Japan
c, Miyazaki University, Japan
d, Ritsumeikan University, Japan
Abstract


The interest in organometal trihalide Pb perovskite (CH3NH3PbI3)-based solar cells has increased more and more in recent years because of the high efficiencies achieved, with a record of over 22%, and the simple low temperature preparation method. The high efficiency was thought to mainly originate from the strong optical absorption over a broader range (up to 800 nm for Pb ), low Urbach energy due to low defect states, and longer lifetimes of photoexcited charge carriers of the organometal trihalide Pb perovskite absorbers. Further improvements in the photovoltaic performance can be obtained by increasing the light harvesting in the NIR region up to 1000 nm by using Sn/Pb cocktail halide based perovskite materials [2]. On the other hand, a good understanding of the key factors governing the photovoltaic performance of the Pb and Sn/Pb perovskite solar cells, especially photoexcited carrier dynamics, is very vital for uncovering the mechanism of achieving high efficiency. In this presentation, we would like to focus on the photoexcited carrier dynamics of Pb and Sn/Pb perovskite solar cells, including photoexcited carrier lifetime, charge separation and recombination dynamics at the interfaces of electron transport material/perovskite and hole transport material/perovskite, and the relationships between these dynamics and the photovoltaic properties. The mechanism for improving the energy conversion efficiency of the perovskite solar cells by means of interface engineering will be discussed [3-7].

References: [1] http://www.nrel.gov/ncpv/.  [2] Y. Ogomi et al., J. Phys. Chem. Lett. (2014), Vol. 5, 1004. [3] Y. Ogomi et al., J. Phys. Chem. C (2014) Vol. 118, 16651. [4] Q. Shen et al., Phys. Chem. Chem. Phys.(2014), Vol. 16, 19984. [5] Q. Shen et al., J. Mater. Chem. A (2015), Vol. 3, 9308. [6] Q. Shen et al., Perovskite Materials - Synthesis, Characterisation, Properties, and Applications, Chapter 13, Likun Pan (Ed.), (INTECH, Feb. 2016). [7] M. Moriya et al., ChemSusChem (2016), Vol. 9, 2634.

10:00 - 10:30
G2-I3
Etgar, Lioz
Hebrew University
Two Dimensional organic-inorganic perovskite from nanostructures to solar cells
Lioz Etgar
Hebrew University, IL

Lioz Etgar obtained his Ph.D. (2009) at the Technion–Israel Institute of Technology and completed post-doctoral research with Prof. Michael Grätzel at EPFL, Switzerland.  In his post-doctoral research, he received a Marie Curie Fellowship and won the Wolf Prize for young scientists. Since 2012, he has been a senior lecturer in the Institute of Chemistry at the Hebrew University. On 2017 he received an Associate Professor position. Prof. Etgar was the first to demonstrate the possibility to work with the perovskite as light harvester and hole conductor in the solar cell which result in one of the pioneer publication in this field. Recently Prof. Etgar won the prestigious Krill prize by the Wolf foundation. Etgar’s research group focuses on the development of innovative solar cells. Prof. Etgar is researching new excitonic solar cells structures/architectures while designing and controlling the inorganic light harvester structure and properties to improve the photovoltaic parameters.

Authors
Lioz Etgar a
Affiliations
a, Instiute of Chemistry, Casali Center for Applied Chemistry, The Hebrew University of Jerusalemt, Edmond Safra Campus, Givat Ram, Jerusalem, 9101204
Abstract

Perovskite is a promising light harvester for use in photovoltaic solar cells. In recent years, the power conversion efficiency of perovskite solar cells has been dramatically increased, making them a competitive source of renewable energy.

This work will discusses new directions related to organic inorganic perovskite and their applications in solar cells. In low dimensional systems, stability of excitons in quantum wells is greatly enhanced due to the confined effect and the coulomb interaction. The exciton binding energy of the typical 2D organic-inorganic perovskites is up to 300 meV and their self-assembled films exhibit bright photoluminescence at room temperature.

♦ In this work we will show the dimensionality in the perovskite structure. The 2D perovskite structure should provide stable perovskite structure compare to the 3D structure. The additional long organic cation, which is added to the perovskite structure (in the 2D structure), is expected to provide hydrophobicity, which will enhance the resistivity of the perovskite to humidity. Moreover we will demonstrate the use of 2D perovskite in high efficiency solar cells.

♦ Organometal halide perovskite is used mainly in its “bulk” form in the solar cell. Confined perovskite nanostructures could be a promising candidate for efficient optoelectronic devices, taking advantage of the superior bulk properties of organo-metal halide perovskite, as well as the nanoscale properties. In this work, we present facile low temperature synthesis of two-dimensional (2D) lead halide perovskite nanorods (NRs). These NRs show a shift to higher energies in the absorbance and in the photoluminescence compared to the bulk material, which supports their 2D structure. X-ray diffraction (XRD) analysis of the NRs, demonstrates their 2D nature combined with the tetragonal 3D perovskite structure. In addition, by alternating the halide composition, we were able to tune the optical properties of the NRs. Fast Fourier Transform, and electron diffraction show the tetragonal structure of these NRs. By varying the ligands ratio (e.g. octylammonium to oleic acid) in the synthesis, we were able to provide the formation mechanism of these novel 2D perovskite NRs. 2D perovskite NRs are promising candidates for a variety of optoelectronic applications, such as light emitting diodes, lasing, solar cells and sensors.

10:30 - 11:00
Coffee Break
11:00 - 11:30
G2-I4
Di Carlo, Aldo
CHOSE - University of Rome
Scaling perovskite cells to large area modules
Aldo Di Carlo
CHOSE - University of Rome
Aldo Di Carlo is Full Professor of Optoelectronics and Nanoelectronics at the Department of Electronics Engineering of the University of ROme "Tor Vergata". His research focuses on the study and fabrication of electronic and optoelectronic devices, their analysis and their optimization. Di Carlo is Director of the Center for Hybrid and Organic Solar Cells (CHOSE) which involve more than 30 researchers dealing with the development of organic solar cells (DSC, OPV and Perovskite) and on scaling-up of these technologies for industrial applications. CHOSE has generated 5 spin-off company and a public/private partnership. Di Carlo is author/coauthor of more than 300 scientific publications in international journals, 13 patents and has been involved in several EU projects (two as EU coordinator)
Authors
Aldo Di Carlo a, b
Affiliations
a, CHOSE – Centre for Hybrid and Organic Solar Energy, University of Rome Tor Vergata, Roma, Italy
b, National University of Science and Technology “MISiS”, Moscow, Russia
Abstract

In the energy field, the use of hybrid organic-inorganic perovskite materials such as CH3NH3PbI3 (MAPI) has opened up new directions to fabricate cost effective and high efficient photovoltaic (PV) devices. Power conversion efficiency (PCE) of solution processed perovskite solar cells (PSCs) reached a record value of 22.7% that pushes the scientific community to focus further on the scaling up of this PV technology.  However, the manufacture of large area perovskite solar cells and modules need proper coating procedures and a direct use of techniques used for small area deposition are not always possible. Moreover, interconnection between cells forming the module requires additional processes often based on advanced laser techniques. In this communication, I will present our latest achievement on perovskite modules fabrication. We will show that the optimization of carrier transporting layers, perovskite absorbing layers, laser patterning, interlayer engineering and deposition technique should be pursued at the same time to improve module efficiency of aperture area and stability of the device.  In particular, a new paradigm to tailor interface properties based on Graphene and Related Materials (GRM) was recently proposed and applied to PSC and modules with the aim to increase both PCE and stability. [1-6] We indeed demonstrated a PCE of 12.6% on a monolithic module with an active area exceeding 50 cm2. Larger area modules were also fabricated by using automated blade coating with gas quenching strategy for perovskite crystallization. Particular efforts were devoted to increase the aperture ration. By using a proper combination of IR and UV laser radiation, we demonstrated that it is possible to reduce interconnection dead area of a module below 400 mm making an aperture ratio of 95%. [7]

References

[1] A. Agresti et al., Advanced Functional Materials 2016, 26, 2686;  ChemSusChem 2016, 9,  2609
[2] A. Capasso et al. Adv. Energy Mat. 2016, 6, 1600920
[3] T. Gatti et al. Adv. Funct. Mat. 2016, 26, 7443
[4] A. L. Palma et al. Nano Energy 2016, 22, 349
[5] A. Agresti et al. ACS Energy Lett. 2017, 2, 279
[6] F. Biccari et al. Adv. Energy Mat. 2017, 7, 1701349
[7] A. Palma et al. IEEE J. Photovoltaics 2017, 7, 1674

 

 

11:30 - 12:00
G2-I5
Ogale, Satishchandra
Indian Institute of Science Education and Research (IISER) Pune
Molecular Engineering of the dimensionality and properties of hybrid perovskite systems in search of novel functionalities and applications
Satishchandra Ogale
Indian Institute of Science Education and Research (IISER) Pune
Authors
Satishchandra Ogale a
Affiliations
a, Indian Institute of Science Education and Research (IISER) Pune
Abstract

Hybrid perovskite systems have attracted great attention lately in view of their unique and tunable optical and optoelectronic properties, and their applicability in high efficiency solar cell architectures. With growing insights into the processing methods and properties of these materials revealed by recent research, it is fairly well established that these systems are quite amenable to facile molecular and dopant related engineering and synthetic manipulations. These can lead to interesting forms including low dimensional ones, with interesting and tunable properties. In this talk I will present and discuss some of our recent research results in this field, highlighting some novel device related opportunities. The specifics will include in situ molecular control of the microstructure and its consequences for highly enhanced photoluminescence of interest to LED application, changes in the dimensionality via small molecule incorporations and the corresponding consequences for white luminescence and new charge storage application, molecular anion doping effects in hybrid perovskites and mechanical properties of interest to flexible devices based on these materials.

References: ChemSusChem, 2017, 10, 3722, J. Mater. Chem. A, 2017, 5, 18634, Adv. Mater. Interfaces, 2017, 4,1700562, J. Appl. Phys. 2017, 121, 133107, J. Phys. Chem. Lett. 2016, 7, 4757, ACS Appl. Mater. & Interfaces, 2016, 8, 854, ChemComm, 2014, 50, 9741.

Funding: Department of Science and Technology (Govt. of India) under the DST Nanomission Thematic Unit and Clean Energy Research Initiative programs.

12:00 - 12:30
G2-I6
Manceau, Matthieu
Alternative Energies and Atomic Energy Commission
Processing of Large area Perovskite-based Solar Modules
Matthieu Manceau
Alternative Energies and Atomic Energy Commission
Authors
Matthieu Manceau a, Solenn Berson a, Ibrahim Bulut a, Noëlla Lemaître a
Affiliations
a, CEA-LITEN ; Univ. Grenoble Alpes, 17 rue des Martyrs, Grenoble, 38054, FR
Abstract

Over the last few years perovskite solar cells (PSCs) have attracted a considerable amount of research and record efficiency has then been quickly increasing. Performance well over 20% are now achieved, but yet, a number of challenges are still to be met to ensure a bright industrial future for PSCs. Significantly improving device active area while maintaining similar power conversion efficiency is probably one of the most important.  

The main focus of this work is to provide new processing routes towards the large scale fabrication of efficient and stable solar modules.

When going from cells to modules there are a variety of challenges one has to consider to build efficient devices: the serial association of the multiple cells (and hence the presence of so-called “interconnection or dead” areas that do not actually contribute to the power conversion) ; the resistive power losses associated with the geometrical design ; the layers homogeneity of the stack over larger areas (encompassing processing & drying / curing issues).

Building up on a process enabling single cells with efficiencies greater than 12%, we propose to present our current advances in development of laser structured modules. Different laser-patterned structures, materials and coating processes were investigated. Opportunities, challenges, issues and performances will be discussed with the support of different electrical and optical characterization techniques such as contact resistance measurements, microscopies and power losses calculations.

12:30 - 12:40
____________
12:45 - 14:00
Lunch
Session A2
Chair: Satishchandra Ogale
14:00 - 14:15
A2-O1
Kim, Ji-Seon
Imperial College London
Energetics and Surface Photovoltage of Perovskites for Thin Film Photovoltaics
Ji-Seon Kim
Imperial College London, GB

Ji-Seon Kim is Professor of Solid State Physics and Director of the Plastic Electronics Centre for Doctoral Training (https://www.imperial.ac.uk/plastic-electronics/) at Imperial College London. She has previously taken up an EPSRC Advanced Research Fellowship at the University of Cambridge, obtained a PhD in Physics in 2000. Her research focuses on the basic science and technology of Nanoscale Functional Materials such as organics, organic/ inorganic hybrids, nanomaterials and their related applications, as well as developing novel Nanometrology for these functional materials (http://www.imperial.ac.uk/nanoanalysis-group).

Authors
Iain Hamilton a, Matyas Daboczi a, Iain Baikie a, Ji-Seon Kim a
Affiliations
a, Department of Physics and Centre for Plastic Electronics, Imperial College London, London, SW7 2AZ, UK., South Kensington, London SW7 2AZ, UK, London, GB
b, KP Technology, Burn Street, Wick, Caithness, KW1 5EH, UK
Abstract

Continuous increase in the device performance of lead halide perovskite-based solar cells is strongly related to better understanding of optical and electronic properties of the perovskite layer. There are still many electronic processes in perovskites that are critical to device performance (e.g. ionic movement, charge carrier recombination, trapping of electrons and holes) and are not yet fully understood. Here we report our recent results of mixed-halide lead perovskites (MAPBr3-xIx) in terms of their energy levels and especially the illumination generated surface photovoltage (SPV) and its transient behaviour.

First, dark work function measurements show that the Fermi level of mixed halides increases with bromide content. We further show the work function of the perovskites used are significantly influenced by the substrate and the mixed halide perovskite films are intrinsically p-type semiconductors. Ambient pressure air photoemission spectroscopy shows that the HOMO values for the samples are mainly governed by MAPI3 domains (~5.3 eV), with the only significant increase in HOMO energy is for MAPBr3 (~5.6 eV), implying a variation in p-doping with halide composition.

Second, SPV transient measurements of mixed halide perovskite films show at least two distinctive processes taking place at different time scales, which are attributed to the generation/recombination of charge carriers and ionic migration. The magnitude (and direction) of each process depends upon both halide composition of the perovskite and the substrate used. We will discuss the impact of these findings on device performance.

14:15 - 14:30
A2-O2
Era, Masanao
Saga University, JP
Optical and Electroluminescent Properties of Lead Iodide-Based Layered Perovskite Self-Organized Quantum-Well
Masanao Era
Saga University, JP

1979-1988 Departmen of Chemisty, Kyushu University

Awased the degree of BSc

1988-1990 Department of Materials Science and Technology, Kyushu Unviersity

Awarded the degree of MSc.

1990-1991 PhD course, Department of Materials Science and Technology, Kyushu Unviersity

1991-1998 Research Associate, Department of Materials Science and Technology, Kyushu Unviersity

1992 Awarded PhD fro Kyushu University. Title of the doctral thesis is "Control of melecular orientation and second-order optical nonlinearity in asymmetric Langmuir-Blodgett films.

1994 Visiting researcher, Cavendish Laboratory, University of Cambridge

1998-present Associate professor at the Department of Chemsity and Applied Chemistry, Saga University

Authors
Masanao Era a, Kazuhiro Ema a
Affiliations
a, Saga University
b, Sophia University, 7-1 KIoi-cho, Chiyoda-ku, Tokyo, 1028554, JP
Abstract

In our previous work1, we found that a lead iodide-based layered perovskite with cyclohexenylethy ammonium molecular cation as an organic layer exhibits highly efficient PL originated from an exciton having large binding energy of several hundred meV. Further, highly efficient EL was observed in a device consisting of emissive layer of a spin-coated film of the layered perovskite and an electron-transporting layer of an oxadiazole. Here, we would like to present detailed optical and electroluminescent (EL) properties in the layered perovskite.

Kramers-Kronig transformation of reflection spectrum measured using a crystal sample of the layered perovskite demonstrated that an exciton band locates at 2.452 eV at RT. Polarization dependencies of its PL at 4 K revealed that emission bands assigned to singlet-dominant exciton and triplet-dominant exciton are located at 2.408 eV and 2.398eV, respectively. The PL excitation spectrum measured by detecting emission of the triplet-dominant exciton demonstrated the formation of an exciton-polariton in the crystal sample; L-T splitting = 94 meV, transverse exciton energy ET = 2.410 eV, and longitudinal exciton energy EL =2.504 eV. From the values, oscillator strength of the exciton band was estimated to be 0.74, and band gap Eg and binding energy Eb of the exciton were estimated to be 2.68 eV and 282 meV, respectively. The PL quantum efficiency was evaluated to be about 0.7 at 110 K from the quantum efficiency measurement using integrated optical sphere.

Efficient EL was observed in the hetero-structure devices consisting of the layered perovskite emissive layer and organic electron-transporting layer. We will present the detailed EL properties in the devices.

M. Era el al., Appl. Phys. Lett., 65, 676 (1994).

14:30 - 14:45
A2-O3
Wang, Haoyi
Renmin University of China
Interpretation of the Biphasic Charge Carrier Recombination Process Observed in Mesoporous-Structured Perovskite Solar Cells
Haoyi Wang
Renmin University of China, CN
Authors
Hao-Yi Wang a, Yi Wang a, b, Man Yu a, Yujun Qin a, Xi-Cheng Ai a, Jian-Ping Zhang a
Affiliations
a, Department of Chemistry, Renmin University of China, Beijing 100872, P. R. China
b, Department of Chemistry, National University of Singapore, 21 Lower Kent Ridge Road, Singapore, 119077, SG
Abstract

Organic-inorganic perovskite solar cells have surged great waves in photovoltaic field owing to their peculiar advantages. At the state-of-the-art, the mesoporous-structured perovskite solar cells (MPSCs) hold the efficiency record, and have already exceeded 22%. In our work, the charge carrier recombination dynamics of MPSCs are investigated by transient photovoltage decay methods. A biphasic charge carrier recombination process is observed, i.e., at low quasi-Fermi level, photo-generated electrons predominately populate in perovskite phase, while at high quasi-Fermi level, most electrons occupy traps in mesoporous TiO2, and then the charge carrier recombination process is determined by the two different phases, respectively.[1] This phenomenon is observed according to the different trap-states distributions of the perovskite and meso-TiO2 phases in MPSCs. Further investigation suggests that the biphasic charge carrier recombination process is also influenced by the trap-states density, especially the density of perovskite phases, under the assistance of temperature-dependent fluorescence.[2] Considering that MPSCs are initially originated from DSSCs, and the structures of the two devices are highly similar with each other. The charge carrier recombination processes of the conventional DSSCs and MPSCs are compared, a novel physical model based on multiple-trapping theory is proposed by taking into account both the contributions of perovskite phase and mesoporous TiO2 phase, which is suitable to describe the biphasic charge carrier recombination process in MPSCs.[3] These findings provide an innovative horizon for the understanding of the charge carrier recombination process in perovskite solar cells.

 

 

[1] H. Y. Wang, Y. Wang, M. Yu, J. Han, Z. X. Guo, X. C. Ai, J. P. Zhang and Y. Qin, Phys. Chem. Chem. Phys. 2016, 18, 12128-12134.

[2] H. Y. Wang, M. Y. Hao, J. Han, M. Yu, Y. Qin, P. Zhang, Z. X. Guo, X. C. Ai and J. P. Zhang, Chem. Eur. J. 2017, 23, 3986-3992.

[3] H. Y. Wang, Y. Wang, M. Y. Hao, Y. Qin, L. M. Fu, Z. X. Guo, X. C. Ai and J. P. Zhang, ChemSusChem 2017, 10.1002/cssc.201701780.

14:45 - 15:00
A2-O4
Panigrahi, Shrabani
Fct/unl
Cross-sectional Analysis of Surface Potential inside Solar Cells Using Kelvin Probe Force Microscopy
Shrabani Panigrahi
Fct/unl
Authors
Shrabani Panigrahi a, Santanu Jana a, Tomás Calmeiro a, Daniela Nunes a, Rodrigo Martins a, Elvira Fortunato a
Affiliations
a, Departamento de Ciência dos Materiais, CENIMAT/i3N, Faculdade de Ciências e Tecnologia–Universidade Nova de Lisboa and CEMOP/Uninova, Caparica, Portugal.
b, Laboratoire de Physique des Solides, Université Paris-Saclay, Université Paris-Sud, Orsay, France.
Abstract

The internal potential of the solar cell devices depends on the basic mechanism of photovoltaic effect, such as charge carrier generation, separation, transport, recombination etc. Here we report the direct observation of the surface potential depth profile across the cross-section of the solar cell at different wavelengths of light using Kelvin probe force microscopy (KPFM). However, KPFM, a modified version of Atomic Force Microscopy (AFM), is a non-contact surface technique used to measure the local contact potential difference (CPD) between a conducting AFM tip and the sample.1,2 We have plotted the CPD profiles across the cross-section of the device and correlated the measured potentials with the material interface positions in the device. The topography and phase images across the cross-section of the solar cell were also observed, where the interfaces of the different layers in the device were well defined in nanoscale range. The influence of the different spectra of light on the generation and transport processes of the charge carriers inside the solar cell have been investigated here. Under steady state solar illumination, a sharp difference in electrical potential is observed across the active layers of the solar cell.3,4 The results on the distribution of the charge carriers inside the solar cells under different illuminations help to understand the basic charge transport mechanism across the interfaces which open the possibility to design the high performance solar cells in future.

References

1.  W. Melitz, J. Shen, A. C. Kummel, S. Lee, Surf. Sci. Rep 66 (2011) 1-27.

2.  J. B. Li, V. Chawla, B. M.Clemens, Adv. Mater. 24 (2012) 720-723.

3. S. Panigrahi, T. Calmeiro, R. Martins, D. Nunes, E. Fortunato, ACS Nano 10 (2016) 6139−6146.

4. S. Panigrahi, S. Jana, T. Calmeiro, D. Nunes, R. Martins, E. Fortunato, ACS Nano, 11 (2017) 10214 – 10221.

15:00 - 15:15
A2-O5
Aranda Alonso, Clara
Universidad Jaume I
High open – circuit voltatge of pure bromide perovskite solar cells using spiro-ometad as a hole-selective material
Clara Aranda Alonso
Universidad Jaume I, ES
Authors
Clara Aranda a, Juan Bisquert a, Antonio Guerrero a
Affiliations
a, Institute of Advanced Materials (INAM), Universitat Jaume I, 12006 Castellón de la Plana, Castellón, España, Castellón de la Plana, ES
Abstract

Perovskite solar cells based in bromide derivatives have potential high open-circuit voltage, due to their band gap value of 2.3 eV. This represents an important tool in the efforts for solar energy harvesting, both to function as high-energy photon absorber to improve utilization of the solar spectrum and drive electrochemical reactions.
With a facile route synthesis using MABr and PbBr 2 as unique precursors, with TiO 2 as electron selective material and Spiro-OMeTAD as hole selective material, we reported an unprecedented Voc of 1.6 V. The beneficial effect of having LiTFSI both in ESM and HSM, was studied as a function of the exposure to light and bias and was explained through the lithium ion migration. Having lithium ion at the mesoporous TiO2 leads to an improvement in the charge extraction as well as a faster photo-oxidation of Spiro-OMeTAD. Controlling the quality of the perovskite film and the extrinsic ion migration, it is possible to obtain a remarkably open-circuit voltage device with the simplest contacts and procedure. In addition, the semi-transparent absorber film with high Voc in the final device has great potential for further applications.

15:15 - 15:30
A2-O6
Stranks, Samuel D.
University of Cambridge
Passivation approaches to eliminate non-radiative losses and inhibit ion migration in halide perovskites
Samuel D. Stranks
University of Cambridge, GB
Authors
Samuel D. Stranks a, Mojtaba Abdi-Jalebi a, Zahra Andaji-Garmaroudi a, Stefania Cacovich a, Camille Stavrakas a, Eline H. Hutter a, Tom J Savenije a, Giorgio Divitini a, Richard H. Friend a
Affiliations
a, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom, JJ Thomson Avenue, 9, Cambridge, GB
b, Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FY, GB
c, Delft University of Technology, Julianalaan 136, Delft, 2628, NL
Abstract

Halide perovskites are generating enormous interest for their use in solar photovoltaic and light-emission applications. One property linking the high performance of these devices is a high radiative efficiency of the materials; indeed, a prerequisite for these devices to reach their theoretical efficiency limits is the elimination of all non-radiative decay. However, there still exists substantial parasitic non-radiative losses and ionic migration in the materials, both of which lead to performance limitations and instabilities.

Here, we will detail several new and promising passivation approaches through additives aimed at eliminating these problematic processes in triple cation (MA,FA,Cs)Pb(I0.8Br0.2)3 thin films. We find internal photoluminescence quantum efficiencies over 90% along with the removal of transient photo-induced ion migration processes. We use time-resolved microwave conductivity measurements to reveal mobilities exceeding 40 cm2/V/s. STEM-EDX measurements on film cross-sections reveal that the passivation treatments facilitate the presence of minimal halide vacancies (defects) by acting as a source of excess halide while also immobilizing the surplus halides into benign chemical products.

Our work reveals promising approaches to fabricate metal halide thin films with the highest optoelectronic quality. The work also provides further evidence that non-radiative decay and ionic motion are intimately related, generalizing the conjecture that there are common solutions to both problems.

15:30 - 15:45
A2-O7
Adjokatse, Sampson
Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen 9747 AG, The Netherlands
Effect of substrate layer and Device Architecture on Photophysics and Device Performance of Planar Perovskite Solar Cells
Sampson Adjokatse
Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen 9747 AG, The Netherlands
Authors
Sampson Adjokatse a, Hong-hua Fang a, Jane Kardula a, Maria Antonietta Loi a
Affiliations
a, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, The Netherlands
Abstract

Hybrid perovskite solar cells (PSCs) have attracted an unprecedented research attention due to their skyrocketing record power conversion efficiency (PCE), which now exceeds 22% in less than a decade from the initial PCE of 3.8%. Besides the excellent optoelectronic properties of the perovskite absorbers, the high efficiencies are also dependent on device architecture, preparation methods and advanced device engineering. In this study, the role of device architecture (planar n-i-p versus inverted p-i-n structure) and charge-selective interlayer on the photophysical properties of the perovskite absorber and device performance are explored. We employ FA0.85MA0.15PbBr0.45I2.55 as the perovskite absorber and chloride-capped TiO2 colloidal nanocrystals (TiO2-Cl) and poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the substrate layers in the conventional and inverted structures, respectively. Extremely different device performances are demonstrated by the two structures. The one with the TiO2-Cl at the substrate interface display a PCE of 19.9%, while the one using PEDOT:PSS shows about 15.1% efficiency. The photophysical and electrical investigations indicate that the TiO2-Cl interface has lower number of traps, underlining the importance of interfaces for achieving highly performing perovskite solar cells.

15:45 - 16:00
A2-O8
Uchida, Satoshi
The University of Tokyo
A new discovery of double phase coexistence inside the perovskite solar cells
Satoshi Uchida
The University of Tokyo, JP

Prof. Satoshi Uchida is a professor (born in 1965) in Research Center for Advanced Science and Technology (RCAST), The University of Tokyo.  He received his PhD from Tohoku University in 1995 and moved to current position in 2006.  For more than 15 years his research focused on the field of dye-sensitized solar cells (DSSCs), specifically cell assembling technique such as full-plastic, light-weight, film type as a ubiquitous power source.  He is now also showing strong activity of Perovskite Solar Cells research based on the crystallography, surface engineering and electronic simulation.

Authors
Satoshi Uchida a, Tae Woong Kim a, Ludmila Cojocaru a, Takashi Kondo a, Hiroshi Segawa a
Affiliations
a, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, JP
b, Albert-Ludwigs University of Freiburg
Abstract

Recently, organometal halide perovskite solar cells (PSCs) have received great attention. The power conversion efficiency (PCE) of PSCs have shown a dramatic increase and certified PCEs adopting mixed organic cations and halide anions have reached up to 22%. The PCE is considerably affected by photovoltaic property of each component of a PSC. Particularly, because crystal quality of materials is strongly concerned with the electronic properties such as carrier transport, investigation of detailed crystallographic information of the perovskite light absorber is essential. In spite of the significance in the crystallographic information, however, microstructural observation for crystal structure analysis of the perovskite layer has not been actively conducted. In this talk, we will report a microstructural observation about phase coexistence in the perovskite light absorber through transmission electron microscope (TEM) observation.

To obtain the crystallographic information of the perovskite light absorber, a pure methylammonium lead iodide (MAPbI3) layer was formed through spin-coating method assisted by antisolvent in a planar type PSC (Au/Spiro-MeOTAD/ MAPbI3/TiO2/FTO/Glass). MAPbI3 precursor solution used is 1.4 M and the spin-coated MAPbI3 film was annealed at 100˚C for 30 min.

Surprisingly, during the high resolution (HR) TEM observation, we found coexistence of both tetragonal and cubic  structures in the same perovskite layer at room temperature. This new observation is expected to be an important clue of the enhancement of perovskite crystal quality for highly efficient PSCs.

Session B2
Chair: Maria Antonietta Loi
14:00 - 14:15
B2-O1
Mastroianni, Simone
Fraunhofer Institute for Solar Energy Systems
Optimization of electron selective layer and perovskite crystallization for efficient outdoor and indoor light harvesting in graphite-based perovskite solar cells
Simone Mastroianni
Fraunhofer Institute for Solar Energy Systems
Authors
Simone Mastroianni a, b, Lukas Wagner a, Lakshmi S. Subramaniam a, Sijo Chacko a, Kübra Yasaroglu a, Wolfram Kwapil a, Laura D. Mundt a, Martin .C. Schubert a, Thomas Kroyer a, Andreas Hinsch a
Affiliations
a, Fraunhofer Institute for Solar Energy Systems, Heidenhofstrasse 2, 79110 Freiburg, Germany
b, Materials Research Center FMF, University of Freiburg
c, University of Strasbourg, Strasbourg, 67081, France.
Abstract

Solar cells for low light harvesting are acquiring in the recent years an increasing interest for their commercial application in the market of Electronic and Product Integrated Photovoltaics (EIPV and PIPV). The solar technology based on perovskite crystals (PSCs) has a huge potential in this field.
In this work, we show that, for low light application, the reduction of electron recombination at the front contact and improved crystal quality are very crucial. Thus, a 2-fold optimization of the monolithic carbon-graphite based PSC used in this study is performed to achieve low non-radiative recombination and, hence, high VOC and efficiency under both full Sun and indoor light conditions:

1. Four different up-scalable electron selective layer (ETS) processes (sputtering, spray pyrolysis, screen-printing and atomic layer deposition) have been investigated through Dark Lock-In Thermography (DLIT) and optimized to achieve a pin-hole/defect free layer and reduced electron-hole recombination. With a spatial resolution < 100 μm, the DLIT analysis (vs. applied voltage) allows the determination of shunts in the layer. Furthermore, shunts can be distinguished into linear (ohmic) and non-linear through plotting the local I-V curve. Transmittance, SEM, AFM, XRD and ellipsometry support the whole analysis. Among the investigated ESLs, the PSCs fabricated with the c-TiO2 ALD-processed ESL showed the maximized VOC.

2. The high quality of the perovskite crystals into the porous structure of the carbon-graphite based PSC is achieved by a molten-salt based MAPbI3 precursor solution. This approach allows a dense pore filling (demonstrated by SEM and EDX maps) and a very fast charge transport through the porous layers (analysed by JSC, VOC and photoluminescence transients). Thereby, a stabilized photovoltage as high as 1 V is a reached, which is the highest for monolithic hole-transport-layer (HTL) free MAPbI3-based devices. We measured a stabilized PCE of 13.8% under 1 Sun and we report the certified stabilized efficiency of 12.6 %.

Following these two optimizations, the resulting high-efficient and low-cost HTL-free PSC is measured under low light intensity as well as under compact fluorescent lamp (CFL) and light-emitting diode (LED) illumination.

14:15 - 14:30
B2-O2
McGettrick, James
SPECIFIC, Swansea University
Perovskite Materials for Scale-Up: Surface Analysis of a Range of Scalable Architectures
James McGettrick
SPECIFIC, Swansea University
Authors
James McGettrick a, Trystan Watson a, Katherine Hooper a, Adam Pockett a, Matthew Carnie a, Joel Troughon a
Affiliations
a, Specific, Swansea University, Apartment 5, Ice House, Kings Road, GB
Abstract

The family of ABX3 lead halide perovskite materials continues to forge forward with record efficiencies. The ease of manufacture and numerous simple structural modifications make perovskites attractive for both research and for potential scale-up. As the photoactive layer within the device, the surfaces of perovskite materials themselves have provoked considerable interest. Techniques such as X-ray Photoelectron Spectrometry (XPS), Ultraviolet Photoelectron Spectrometry (UPS) provide insight into the surface chemistry and physics. The surface itself is important as if forms the interface with subsequent layers in the device. The surface would also be especially sensitive to degradation, showing evidence of materials failure before bulk analytical techniques.

We have studied methyl ammonium lead triiodide (MAPI) and triple cation films in several architectures utilising both 1) a simple planar FTO(fluorine doped tin oxide)/TiO2 substrate architecture and 2) the triple mesoporous TiO2/ZrO2/carbon substrate favoured by many as a scale-up architecture due to its manufacturing simplicity. We have examined influence of both the manufacturing consistency and the stability of the perovskite films on the surface composition. Quantified surface analyses show three clear defects that vary with manufacturing. The first two offer insight into the quality of the perovskite manufacturing process: 1) The presence of film pinholes in the perovskite layer reveal the chemistry of the underlying n-type selective film, and are an obvious direct measure of coating quality; 2) The presence of excess PbI2 varies with both age and manufacturing technique, and suggests that the sequential deposition route allows strong control of lead halide to perovskite conversion in the samples studied. 3) A Pb(0) component is observed in some cases suggesting the presence of metallic lead at the surface, which it is speculated may contribute to losses within the photovoltaic cell. Although not omnipresent across the literature, that Pb(0) is present in some analyses is beyond dispute: XPS has previously shown a distinct shift of the classic perovskite Pb(II) peak to a lower binding energy consistent with Pb(0); UPS has shown metallic behaviour at the valence level with electron density continuing up to the Fermi level; and several other techniques have noted presence of Pb(0). In fact, we demonstrate reproducible appearance of Pb(0) on otherwise pristine films and hence suggest it as a useful indirect measure of film quality.

14:30 - 14:45
B2-O3
Mesquita, Isabel
FEUP -Faculty of Enginerring of University of Porto
Temperature influence in the perovskite solar cell operation
Isabel Mesquita
FEUP -Faculty of Enginerring of University of Porto
Authors
Isabel Mesquita a, Luísa Andrade a, Adélio Mendes a
Affiliations
a, LEPABE, Departamento de Engenharia Química, Universidade do Porto – Faculdade de Engenharia, Rua Dr. Roberto Frias s/n 4200-465 Porto, Portugal
Abstract

Perovskite solar cells (PSC) have emerged as a new family of photovoltaic devices and a surprising power conversion efficiency increase from 3.8 % to 22.7 % was reached in only few years [1]. This type of solar cells is a very promising alternative to conventional photovoltaic panels that use harmful chemicals and complex purification processes [2]. Although the astonishing power conversion efficiency evolution, these cells present some practical drawbacks as instability when submitted to high temperatures [3].

The temperature effect on triple cation perovskite solar cells during operation is studied within this work; the cells were prepared according to [4]. IV and EIS analyses were conducted in a temperature range from -5 to 80 °C with help of a peltier element for temperature control. To prevent the influence of ambient humidity during measurements, the cells were sealed with Kapton® as main sealing and high temperature epoxy as edge sealing. The sealing was successfully achieved since the performance of the cells before and after sealing was maintain. Electrochemical, morphological and structural analyses of the aged devices were also performed through EIS, SEM and XRD for assessing the effect of the temperature stress.

At temperatures below 22 °C the performance of the cells showed to remain stable. Nevertheless, at higher temperatures (T > 40°C), the performance of the tested cells decreased irreversibly with temperature. These results will be presented and the contribution of each layer for the deactivation will be discussed along with the proposed corresponding deactivation mechanism.

 

[1]          National Renewable Energy Laboratory. Available from: www.nrel.gov [December, 2017].

[2]          Mulvaney D. Hazardous Materials Used In Silicon PV Cell Production: A Primer. Solar Industry. September 2013.

[3]          Malinauskas T, Tomkute-Luksiene D, Sens R, Daskeviciene M, Send R, Wonneberger H, et al. Enhancing Thermal Stability and Lifetime of Solid-State Dye-Sensitized Solar Cells via Molecular Engineering of the Hole-Transporting Material Spiro-OMeTAD. ACS Applied Materials & Interfaces. 2015;7(21):11107-16.

[4]          Saliba M, Matsui T, Seo J-Y, Domanski K, Correa-Baena J-P, Nazeeruddin MK, et al. Cesium-containing triple cation perovskite solar cells: improved stability, reproducibility and high efficiency. Energy & Environmental Science. 2016;9(6):1989-97.

14:45 - 15:00
B2-O4
Dally, Pia
CEA Liten/DTS/SMPV/LMPO
Advanced characterization of Perovskite systems: Understanding and improving the performance and stability of photovoltaic devices
Pia Dally
CEA Liten/DTS/SMPV/LMPO, FR
Authors
Pia Dally a, Noella Lemaitre a, Stéphanie Pouget a, Stéphane Cros a, Serge Gambarelli a, Solenn Berson a
Affiliations
a, CEA Liten/DTS/SMPV/LMPO, 50 Avenue du Lac Léman, Le Bourget du Lac, 73375, FR
b, Univ. Grenoble Alpes, CEA, INAC, MEM, 38000 Grenoble, France
c, Univ. Grenoble Alpes, CEA, SyMMES, 38000 Grenoble, France
Abstract

Over the last few years, perovskite solar cells (PSCs) have attracted a considerable amount of research and evolved in an exponential manner. The power conversion efficiency has then been rapidly increasing and has recently exceeded 22% [1]. However, the major factor that has been limiting practical application is intrinsic and extrinsic stability [2]. There are various issues associated with the stability of PSCs and the degradation’s mechanisms of perovskite are still under investigations. The main aim of this work is to understand the fundamental mechanisms, the properties and defaults of these materials via X-ray diffraction (XRD) and Electronic Paramagnetic Resonance (EPR).

In this study, perovskite layer (CH3NH3PbI3) is coated on glass/ITO/ Aluminum doped zinc oxide (AZO). Several aging experiments in different conditions are carried out: aging in glovebox, aging in light (35°C/1 sun), aging in temperature (65°C) and aging in ambient air.

 XRD measurements revealed the growth of PbI2 and the decrease of perovskite peaks during different aging times. Through these studies, we have been able to determine the kinetics of perovskite’s degradation. In order to correlate this kinetics with the degradation of devices (glass/ITO/AZO/Perovskite/P3HT/Au), we performed a differential aging of solar cells, which consists in aging perovskite layers in different conditions before the evaporation of top electrode. These studies revealed that the stability of perovskite thin films is not the main parameter responsible of perovskite solar cells degradation. XRD measurement has shown that perovskite thin films are stable even after storage for more than 1000h in glove box. This differential aging’s study will be discussed in details.

In addition, the interest of EPR spectroscopy, in which electron spins are excited, is the identification of ions and organic radicals formed during perovskite’s degradation. EPR spectra of perovskite thin films spin-coated on different substrates will be discussed in details.

These analyses pave the route towards an understanding of the degradation way of perovskites in order to enhance the performance of perovskite solar cells.

 

 

[1] M. A. Green, K. Emery, Y. Hishikawa, W. Warta, E. D. Dunlop, Prog. Photovolt. 2016, 24, 905.

[2] T.A. Berhe et al, Energy Environ. Sci. 2016, 9, 323.

15:00 - 15:15
B2-O5
Guo, Dengyang
Delft University of Technology
How Charge Dynamics Change in Mixed Halide Perovskites on Light Soaking
Dengyang Guo
Delft University of Technology, NL
Authors
Dengyang Guo a, Zahra Garmaroudi a, Samuel Stranks a, Tom Savenije a
Affiliations
a, Chemical Engineering, Optoelectronic Materials, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
b, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
Abstract

The highest efficiency of solar cells based on metal halide perovskites as light absorber has reached 22.1%. Interestingly, the used perovskite comprise a mixture of cations (MA+, FA+, and Cs+ ) and halides (I-, Br-). Despite the excellent performance, these perovskites exhibit some phase segregation on light soaking as demonstrated by photoluminescence and XRD. However, it is unclear how the segregation affects the dynamics of charge carriers. In this work we carried out time-resolved microwave-conductivity (TRMC) measurements to investigate the dynamics of mobile charge carriers before and after light soaking using a similar light intensity as AM1.5. We have studied thin spin-coated layers on quartz of (FA0.79MA0.16Cs0.05) Pb (I1-xBrx)3 with x ranging from 0 to 1. For x < 0.5 we find that on light soaking in nitrogen environment the charge carrier lifetime increases, while for x > 0.5 the lifetime is reduced. The charge carrier mobilities of the mixed perovskites reduce gradually from 36 cm2/Vs for x = 0 to 16 cm2/Vs for x = 1. Interestingly, these values are not affected by light soaking, which implies that the major part of the perovskite is not influenced by light soaking, whereas the decay pathways have changed. By analysing the TRMC traces with a mathematical model, we propose that for x< 0.5 light soaking leads to a reduction of the number of shallow states. Two months after light soaking, samples with x < 0.5 are only partially recovered including the shallow states, while samples with x > 0.5 are fully recovered. In summary, the above results provide guidelines for which I/Br ratio we can expect the best performance and stability.

15:15 - 15:30
B2-O6
Caprioglio, Pietro
University of Potsdam, Soft Matter Physics
Reducing recombination and enhancing open circuit voltage by Strontium-alloying in multiple cation perovskite solar cells
Pietro Caprioglio
University of Potsdam, Soft Matter Physics, DE
Authors
Pietro Caprioglio a, b, Fengshuo Zu a, Christian M. Wolff a, Martin Stolterfhot a, Norbert Koch a, Bernd Rech a, Steve Albrecht a, Dieter Neher a
Affiliations
a, University of Potsdam Institut für Physik und Astronomie Physik weicher Materie, Potsdam
b, Humboldt-Universität, Institut für Physik, Berlin
c, Helmholtz-Zentrum Berlin, Institute for Silicon Photovoltaics, Berlin
d, Helmholtz-Zentrum Berlin, Young Investigator Group Perovskite Tandem Solar Cells, Berlin
Abstract

Metal halide perovskite solar cells are now effectively competing with their inorganic counterparts in terms of power conversion efficiencies and estimated production costs. State of the art perovskite solar cells still suffer from too low fill factor and open circuit voltage (Voc), which has been related to non-geminate losses mostly happening at the surface of the perovskite absorber.  Here,  we present  the  enhancement  of  the  Voc   by  addition  of  Strontium  (Sr)  to  a  quadruple cation  perovskite  Rb5(Cs5(MA0.17FA0.83)Pb(I0.83 Br0.17)3)95)95  in  a  p-i-n  solar  cell structure with PTAA and C60  forming the  hole and  electron  transport  layer,  respectively. When alloying the perovskite with Sr, the resulting material displays significantly enhanced PL lifetime and absolute PL yield. This indicates a reduction of surface recombination thereby enlarging the splitting of the quasi-Fermi-levels in the neat perovskite absorber, giving promise for a increased Voc in the device. This finding is confirmed by the enhancement in Voc and in electroluminescence efficiency observed in actual devices, where the Voc increase from 1.11 V to 1.18 V and electroluminescence efficiency rises up by one order of magnitude upon Sr addition, denoting impressing emissive behaviour.  As a result, the power conversion efficiency increases by up to 1% (absolute), reaching a PCE of 20.3% under AM1.5G illumination. We  show  through  various photoelectron  spectroscopy  techniques (UPS/XPS  and  IPES), how the addition of Sr changes the energetic  landscape, inducing a more n-type surface and enabling a  more  electron selective contact between the perovskite and the  C60. We propose that such  a  change  in  energetics  is  responsible  for  a  substantial  suppression  of  surface recombination in the neat material and a reduction of interface recombination with the electron transport layer (ETL). Through Secondary Ion Mass Spectroscopy (SIMS), XPS and Scanning Electron Microscopy (SEM) we show that Sr is mostly segregated close to the charge transport layers, affecting only the interface and leaving the bulk almost unaltered. In conclusion, we propose that Sr-addition enables an appropriate  interface  modification  between  the  perovskite  and  the  charge transport  layers that helps  to  suppress  surface  recombination  and  reduce Voc  losses.  Our  results  can  be  representative  of  a  more  general methodology  for  device  modification,  therefore  they  can  be  applicable  to  other compositions  and  cell  architectures  enabling  future  efficiency  enhancements  of perovskite solar cells.

 

15:30 - 15:45
B2-O7
Belchi, Raphaëlle
CEA, France
TiO2/graphene-based nanocomposite as electron transport layer for perovskite solar cells: synthesis and properties
Raphaëlle Belchi
CEA, France
Authors
Raphaëlle Belchi a, b, Aurélie Habert a, Nathalie Herlin-Boime a, Johann Bouclé a
Affiliations
a, NIMBE, CEA, CNRS, Université Paris-Saclay, CEA Saclay 91191 Gif-sur-Yvette, France
b, Univ. Limoges, CNRS, XLIM, UMR 7252, F-87000 Limoges, France
Abstract

Since 2012, hybrid solar cells based on perovskite materials demonstrated several significant advances, with power conversion efficiencies now over 22%, attracting strong interest within the scientific community [1][2]. Still, efforts remain to be performed to improve photo-current extraction, especially concerning the development of efficient and reliable charge transporting electrodes and selective contacts. Titanium dioxide mesoporous layer, while remaining an important component for perovskite structuration and electron transport in high efficiency devices, can however still promote charge trapping and recombination. To reduce these phenomena and improve electron collection, our strategy consists in using the excellent conductivity properties of graphene materials through its incorporation within the TiO2 electrode. 

In this context, we develop high quality TiO2/graphene composites in a single step by using the singular technique of laser pyrolysis that enables to synthesize nanoparticles with well-controlled properties, tuned for an optimal energy conversion. We combine here this specific know-how on material synthesis with our know-how on perovskite solar cells processing.

We pay particular attention to material characterizations such as morphological and structural analysis as well as physical properties evaluation of the nanocomposites and their role and effects within solar cells. Our first results show a larger conductivity of the TiO2 layer in presence of graphene, as well as larger photocurrents and smaller series resistance under standard illumination, traducing the benefits of graphene for a better charge collection in the device. More generally, a significant increase in power conversion efficiency is observed for perovskite solar cells containing graphene in the TiO2 mesoporous layer, demonstrating the benefit of the laser pyrolysis process for the production of high quality electron transport layer.

 

[1] www.nrel.gov/ncpv/
[2] H. Zhou et al., Science 2014, vol 345, page 542-546

15:45 - 16:00
B2-O8
RAMOS MELLADO, F. Javier
IPVF
A 22.42 % 4-terminal perovskite/silicon tandem device with a 3 % boost over commercially available silicon cell.
F. Javier RAMOS MELLADO
IPVF
Authors
F. Javier Ramos a, b, Sebastien Jutteau a, b, c, Jorge Posada a, b, c, Amelle Rebai a, b, Thomas Guillemot a, Adrien Bercegol a, b, c, Romain Bodeux a, b, c, Nathanaelle Schneider a, b, Nicolas Loones a, b, c, Daniel Ory a, b, c, Cedric Broussillou a, Laurent Lombez a, b, Jean Rousset a, b, c
Affiliations
a, IPVF, Institut Photovoltaïque d’Ile-de-France, 30 RD 128, 91120 Palaiseau, France
b, IRDEP, Institute of Research and Development on Photovoltaic Energy (IRDEP), UMR 7174 CNRS-EDF- Chimie ParisTech, France
c, EDF R&D, 6 Quai Wattier, 78400 CHATOU, France
Abstract

Hybrid organic-inorganic Perovskite Solar Cells (PSC) have emerged during the last five years as one of the most promising PV technologies due to their excellent properties such as high absorption coefficient, long diffusion lengths for both carriers, tunable wide bandgap and versatile fabrication. Those properties make them very promising candidates as top cell absorber in tandem solar cells. Two main stacking possibilities are distinguished: 2 terminal (2T) and 4 terminal (4T). While 2T geometry can maximize the overall efficiency, certain difficulties such as producing a tunnel junction without electrical or optical losses and the mandatory current matching between top and bottom cells make 2T tandems more complex under an industrial point of view. In contrast, 4T architectures allow to maintain separated the optimization of top and bottom cells, being only necessary to prepare a semitransparent rear contact at the top cell and minimize the reflection losses between both solar cells.

Hence, in this work we present a tandem solar cell composed by: a top cell made of triple cation perovskite with a precise composition of (Cs0.05MA0.16FA0.79)Pb(Br0.5I2.5) where the back contact is sputtered-ITO, in combination with a commercially available silicon solar cell as bottom one to be assembled in a 4-T tandem. The selected architecture for the semitransparent perovskite solar cell was FTO/bl-TiO2/mp-TiO2/perovskite/spiro-OMeTAD/ITO. It is remarkable the absence of MoOx layer between spiro-OMeTAD and ITO since it was found not necessary in order to limit spiro-OMeTAD degradation and to ensure good reproducibility. Different thicknesses of perovskite layer and several deposition conditions for sputtered-ITO were tested to optimize the system.

Therefore, the semitransparent perovskite solar cell showed JSC=21.53mA cm-2, VOC=1065mV, FF=73.0%, for a final power conversion efficiency of 16.72% for an active area of 0.25cm2. The original efficiency of the silicon wafer was 19.5% (JSC=38.46mA cm-2, VOC=639mV, FF=79.4%), which was reduced to 18.5% (JSC=38.86mA cm-2, VOC=619mV, FF=77.0%) after laser cutting to adjust perovskite size. After filtering with the top cell, the cut commercially available Si bottom solar cell exhibited JSC=12.75mA cm-2, VOC=585mV, FF=77.0%, for a power conversion efficiency of 5.7%. To have a successful 4-T integration, an optical coupling by dripping a liquid between top and bottom devices was needed. Consequently, an overall efficiency of 22.42% was achieved by the 4-T tandem, a 3% boost regarding the commercially available Si wafer.

16:00 - 16:15
Closing ABXPV
16:00 - 17:15
Registration PEROPTO
16:15 - 17:45
Poster session ABXPV and PEROPTO
17:45 - 18:00
Poster awards ceremony
19:00 - 21:30
Social Dinner ABXPV and PEROPTO
 
Thu Mar 01 2018
08:15 - 08:45
Registration
08:45 - 08:50
Announcement of the day
08:50 - 09:00
Opening PEROPTO
Session H1
Chair: Samuel D. Stranks
09:00 - 09:30
H1-I1
Kovalenko, Maksym
ETH Zurich
Colloidal nanocrystals of APbX3 [A=Cs+, CH(NH2)2+, X=Cl-, Br-, I-] perovskites with bright photoluminescence spanning the entire visible spectral range
Maksym Kovalenko
ETH Zurich, CH

Maksym Kovalenko has been a tenure-track Assistant Professor of Inorganic Chemistry at ETH Zurich since July 2011 and Associate professor from January 2017. His group is also partially hosted by EMPA (Swiss Federal Laboratories for Materials Science and Technology) to support his highly interdisciplinary research program. He completed graduate studies at Johannes Kepler University Linz (Austria, 2004-2007, with Prof. Wolfgang Heiss), followed by postdoctoral training at the University of Chicago (USA, 2008-2011, with Prof. Dmitri Talapin). His present scientific focus is on the development of new synthesis methods for inorganic nanomaterials, their surface chemistry engineering, and assembly into macroscopically large solids. His ultimate, practical goal is to provide novel inorganic materials for rechargeable Li-ion batteries, photovoltaics, and optoelectronics. He is the recipient of an ERC Starting Grant 2012, Ruzicka Preis 2013 and Werner Prize 2016

Authors
Maksym Kovalenko a
Affiliations
a, ETH Zurich & EMPA, HCI, D 126-128, Wolfgang-Pauli-Str. 10, 8093 Zurich
Abstract

Chemically synthesized inorganic nanocrystals (NCs) are considered to be promising building blocks for a broad spectrum of applications including electronic, thermoelectric, and photovoltaic devices. In this lecture we will discuss the synthesis methodology, crystallography and basic photophysics of colloidal lead halide perovskite NCs. First, we have synthesized monodisperse colloidal nanocubes (4-15 nm edge lengths) of cesium lead halide perovskites (CsPbX3, X=Cl, Br, and I or mixed halide systems Cl/Br and Br/I) using inexpensive commercial precursors [1]. The bandgap energies and emission spectra of these NCs are readily tunable over the entire visible spectral region of 410-700 nm. The photoluminescence of CsPbX3 NCs is characterized by narrow emission line-widths of 12-42 nm, wide color gamut covering up to 140% of the NTSC color standard, high quantum yields of up to 90% and also low thresholds for stimulated emission [2]. Post-synthestic chemical transformations of colloidal NCs, such as ion-exchange reactions, provide an avenue to compositional fine tuning or to otherwise inaccessible materials and morphologies [3]. Similar synthesis methodologies are well suited also for hybrid perovskite NCS based on methylammonium (MA) and formamidinium cations (FA): MAPbX3 [4], FAPbBr3 [5], Cs1-xFAxPbI3 and FAPbI3 [6], with the latter reaching near-infrared wavelengths of 800nm. These Cs- and FA-based perovskite NCs are highly promising for luminescence downconversion (bright and narrow emission at 530 and 640 nm; backlighting for displays), for light-emitting diodes and as precursors/inks for perovskite solar cells.

09:30 - 10:00
H1-I2
Rand, Barry
Princeton University
Light emitting devices and lasers from metal halide perovskites
Barry Rand
Princeton University, US
Authors
Barry Rand a
Affiliations
a, Department of Electrical Engineering, Princeton University, Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, US
Abstract

Hybrid organic-inorganic halide perovskite materials such as methylammonium lead iodide have garnered significant interest in the thin film optoelectronics community due to their promising optoelectronic properties. We have determined that the fabrication of perovskite thin films displays all of the hallmarks of sol-gel processing, an aspect that we exploit to improve the quality of spin coated thin films. In particular, we realize films with roughness on the order of 1 nanometer that consist of nanoscale crystallites, formed by incorporating a bulky organoammonium halide in addition to the stoichiometric 3D perovskite precursors. These bulky ligands passivate the 3D crystal, lead to considerably enhanced luminescence quantum yields, and increase stability. LEDs produced in this way are capable of exceeding 10% external quantum efficiency and rigid glass or flexible (and ITO free) substrates, and exhibit significantly improved stability and flexibility. Also, we will show how these smooth films can be employed in pulsed and cw optically pumped laser structures.

10:00 - 10:30
H1-I3
Herz, Laura
University of Oxford
Fundamental mechanisms determining charge-carrier recombination and mobility in hybrid perovskites at the intrinsic limit
Laura Herz
University of Oxford, GB

Laura Herz is a Professor of Physics at the University of Oxford. She received her PhD in Physics from the University of Cambridge in 2002 and was a Research Fellow at St John's College Cambridge from 2001 - 2003 after which she moved to Oxford. Her research interests lie in the area of organic and organic/inorganic hybrid semiconductors including aspects such as self-assembly, nano-scale effects, energy-transfer and light-harvesting for solar energy conversion.

Authors
Laura Herz a
Affiliations
a, Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom
Abstract

Photovoltaic devices based on hybrid metal halide perovskites are rapidly improving in power conversion efficiency. At the Shockley-Queisser limit, the recombination and mobility of charge-carriers will be limited only by intrinsic properties. Yet, the mechanisms for these parameters, and their link with material stoichiometry, is still poorly understood.

We show that bimolecular (band-to-band) recombination of charge-carriers in methylammonium lead triiodide perovskite can be fully explained as the inverse process of absorption. The sharpening of photon, electron and hole distribution functions therefore significantly enhances bimolecular charge recombination as the temperature is lowered, mirroring trends in transient spectroscopy [1]. We show that typical measurements of the radiative bimolecular recombination constant in CH3NH3PbI3 are also strongly affected by photon reabsorption that masks a much larger intrinsic bimolecular recombination rate constant [2]. By investigating films whose thickness varies between 50 and 533 nm, we show that the bimolecular charge recombination rate indeed appears to slow by an order of magnitude as the film thickness increases. However, by using a dynamical model that accounts for photon reabsorption and charge-carrier diffusion we determine that a single intrinsic bimolecular recombination coefficient of value 6.8×10−10cm3s−1 is common to all samples irrespective of film thickness [2]. We also examine the critical role of photon confinement on free charge-carrier retention in thin photovoltaic layers.

We further discuss the role of Fröhlich interaction is the dominant source of electron-phonon coupling determining the charge-carrier mobility in high-quality perovskites near room temperature [3]. We show that while mobilities in some of these hybrid perovskites are near the intrinsic limit of what is fundamentally achievable, others are still dominated by effects of alloying, structural instabilities and doping [4,5].

[1] R. L. Milot, G. E. Eperon, H. J. Snaith, M. B. Johnston, and L. M. Herz, Adv. Func. Mater., 25, 6218 (2015).

[2] T. W. Crothers, R. L. Milot, J. B. Patel, E. S. Parrott, J. Schlipf, P. Müller-Buschbaum, M. B. Johnston, and L. M. Herz, Nano Lett. 17, 5782 (2017).

[3] A. D. Wright, C. Verdi, R. L. Milot, G. E. Eperon, M. A. Pérez-Osorio, H. J. Snaith, F. Giustino, M. B. Johnston, and L. M. Herz, Nature Communications 7, 11755 (2016).

[4] L. M. Herz, ACS Energy Lett. 2, 1539 (2017).

[5] W. Rehman, D. P. McMeekin, J. B. Patel, R. L. Milot, M. B. Johnston, H. J. Snaith, and L. M. Herz, Energy Environ. Sci. 10, 361 (2017).

10:30 - 11:00
Coffee Break
11:00 - 11:30
H1-I4
Mora-Seró, Iván
Institute of Advanced Materials (INAM), Universitat Jaume I
Perovskite Optical Amplifying Waveguides
Iván Mora-Seró
Institute of Advanced Materials (INAM), Universitat Jaume I, ES

Iván Mora-Seró (1974, M. Sc. Physics 1997, Ph. D. Physics 2004) is researcher at Universitat Jaume I de Castelló (Spain). His research during the Ph.D. at Universitat de València (Spain) was centered in the crystal growth of semiconductors II-VI with narrow gap. On February 2002 he joined the University Jaume I. From this date until nowadays his research work has been developed in: electronic transport in nanostructured devices, photovoltaics, photocatalysis, making both experimental and theoretical work. Currently he is associate professor at University Jaume I and he is Principal Researcher (Research Division F4) of the Institute of Advanced Materials (INAM). Recent research activity was focused on new concepts for photovoltaic conversion and light emission based on nanoscaled devices and semiconductor materials following two mean lines: quantum dot solar cells with especial attention to sensitized devices and lead halide perovskite solar cells and LEDs, been this last line probably the current hottest topic in the development of new solar cells.

Authors
Iván Mora-Seró a
Affiliations
a, Institute of Advanced Materials (INAM), Universitat Jaume I, 12006 Castellón de la Plana, Castellón, España, Castellón de la Plana, ES
Abstract

Halide perovskites have emerged as an outstanding material for photovoltaic applications with certified efficiencies higher than 22.5%. In order to obtain efficiencies as the ones reported for PSCs it is needed a low non-radiative recombination. Consequently Hybrid halide perovskite present an outstanding properties for light emission. Here, we report the use of HPVKs as gain materials in a planar waveguide configuration integrated on a silicon substrate or in a flexible substrate. We have designed a solution processed optical amplifier, as demonstrated by the production of amplification of the spontaneous emission (ASE) at 780 nm with low energy threshold. Samples were prepared by a low cost solution processing method and no degradation of the device has been observed after more than one year. In addition, we show the monolithic integration of a perovskite-based optical waveguide amplifier, together with a photodetector to demonstrate the feasibility of a stretchable signal manipulation and receptor system fabricated on both rigid and flexible substrate.

11:30 - 12:00
H1-I5
Sum, Tze-Chien
Nanyang Technological University
Towards Hot Carrier Perovskite Solar Cells
Tze-Chien Sum
Nanyang Technological University

Dr. Tze-Chien Sum is an Associate Professor at the Division of Physics and Applied Physics, School of Physical and Mathematical Sciences (SPMS), Nanyang Technological University (NTU) where he leads the Femtosecond Dynamics Laboratory. He is presently the Associate Dean (Research) at the College of Science. Tze-Chien received his Ph.D. in Physics from the National University of Singapore (NUS) in 2005, for the work in proton beam writing and ion-beam spectroscopy. His present research focuses on investigating light matter interactions; energy and charge transfer mechanisms; and probing carrier and quasi-particle dynamics in a broad range of emergent nanoscale and light harvesting systems. Tze-Chien received a total of 11 teaching awards from NUS and NTU, including the coveted Nanyang Award for Excellence in Teaching in 2006 and the 2010 SPMS Teaching Excellence Honour Roll Award. Most recently, he received the 2013 SPMS Young Researcher Award; the Institute of Physics Singapore 2014 World Scientific Medal and Prize for Outstanding Physics Research; the 2014 Nanyang Award for Research Excellence (Team); and the 2015 Chemical Society of Japan Asian International Symposium Distinguished Lectureship Award. More information can be found at http://www.ntu.edu.sg/home/tzechien/spms/index.html

Authors
Tze Chien Sum a
Affiliations
a, Nanayang Technological University, Singapore
Abstract

Perovskite solar cells, with efficiencies exceeding 22%, are presently the forerunner amongst the next generation photovoltaic technologies. However, in the past year, further efficiency improvements have decreased significantly. For any new efficiency breakthroughs, fresh perspectives and approaches must be developed. Recent discoveries of slow hot carrier cooling phenomenon in halide perovskites [1-3] revealed that such perovskites are highly promising hot-carrier absorber materials capable of unlocking disruptive high-efficiency hotcarrier photovoltaics to overcome the Shockley-Queisser limit. In this talk, I will trace the developments on the slow hot carrier cooling properties of halide perovskites beginning with the discovery of slow hot hole cooling in 2013. [1] Our group further uncovered that hot electrons cooling is slow as well and is relatively balanced with the hot holes. [4] I will also focus on our group’s efforts: (i) to further retard the hot carrier cooling using perovskite nanoparticles; (ii) to achieve efficient extraction of the hot carriers; [3] and (iii) to understand origins and mechanisms of slow hot-carrier cooling in halide perovskites [5]. Opportunities and challenges for hot-carrier perovskite photovoltaics will also be discussed.

References: [1] G. C. Xing et al., “Long-Range Balanced Electron and Hole Transport Lengths in Organic-Inorganic CH3NH3PbI3”, Science, 342,344-347 (2013),[2] Y. Yang et al., “Observation of a hot-phonon bottleneck in lead-iodide perovskites”, Nature Photonics 10, 53–59 (2016),[3] M. J. Li et al., “Slow Cooling and Highly Efficient Extraction of Hot Carriers in Colloidal Perovskite Nanocrystals”, Nature Communications 8 14350 (2017),[4] T. C. Sum et al., “Spectral Features and Charge Dynamics of Lead Halide Perovskites: Origins and Interpretations (Invited Article)”, Accounts of Chemical Research 49,294-302 (2016),[5] J. Fu et al., “Hot carrier cooling mechanisms in halide perovskites”, Nature Commununications 8:1300 (2017)

12:00 - 12:30
H1-I6
Meredith, Paul
Swansea University
Organohalide Perovskite Photodetectors
Paul Meredith
Swansea University, GB

Professor Meredith is professor of materials physics at the University of Queensland in Brisbane, Australia. He is currently an Australian Research Council Discovery Outstanding Research Award Fellow, co-director of the Centre for Organic Photonics and Electronics, and Director of the UQ Solar Initiative. His research involves the development of new sustainable high-tech materials for applications such as solar energy and bioelectronics, and he particularly specialises in the transport physics and electro-optics of disordered semiconductors. Professor Meredith is also the co-founder of several start-up companies including XeroCoat and Brisbane Materials Technology. He is the recipient of numerous awards including the Premier of Queensland’s Sustainability Award (2013) and is widely recognised for his contributions to innovation and the promotion of renewable energy in Australia. He serves on several advisory boards including the Premier of Queensland’s Climate Change Council, the Australian Solar Thermal Research Initiative Strategic Advisory Board, and the Australian Renewable Energy Agency Technical Advisory Board. He originally hails from South Wales, was educated at Swansea University and Heriot-Watt University, and was DTI Postdoctoral Fellow at the Cavendish Laboratory in Cambridge before spending 6 years as an industrial scientist with Proctor and Gamble.

Authors
Paul Meredith a, Qianqian Lin a, Paul Burn a, Ardalan Armin a
Affiliations
a, Swansea University,, Singleton Park, Swansea, GB
b, Wuhan University, School of Physics and Technology,Wuhan University, Wuhan, Hubei Province, 430072, CN
c, Centre for Organic Photonics & Electronics (COPE), School of Mathematics and Physics and School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane 4072 , AU
Abstract

Abstract

The light harvesting performance and tunability of organohalide perovskite semiconductors demonstrated in photovoltaic applications, leads to the obvious question as to whether they can be deployed as the junction in photodetectors. Indeed, these materials should in principle be able to rival other solution processed semiconductors such as the organics and inorganic quantum dots [1-3]. In my talk, I will describe recent progress to create a family of organohalide perovskite photodetectors based upon a simple thin film diode architecture. Applications include high detectivity broad-band photodiodes for the UV-Visible [4], single crystal NIR detectors [5], and narrow-band red, green, blue (RGB) systems [6] which deliver truly colour discriminative performance without the need for input optical filtering. The latter represent a completely new photodiode platform which could ultimately deliver the type of illuminant-independent imaging needed for machine and artificial vision.

 

[1] Solution-processed semiconductors for next-generation photodetectors”, F.P. García de Arquer, A. Armin, P. Meredith & E.H. Sargent, Nature Reviews Materials, 2, 16100 (2017).

[2] Thick junction broadband organic photodiodes, A. Armin, M. Hambsch, I.K. Kim, P.L. Burn, P. Meredith & E.B. Namdas, Laser and Photonics Reviews, 8(6), 924-932 (2014).

[3] Narrowband light detection via internal quantum efficiency manipulation of organic photodiodes, A. Armin, R. D. Jansen-van Vuuren, N. Kopidakis P. L. Burn & P. Meredith, Nature Communications, 6, 6343 (2015).

[4] Low noise, IR-blind organohalide perovskite photodiodes for visible light detection and imaging, Q. Lin, A. Armin, D.M. Lyons, P.L. Burn & P. Meredith, Advanced Materials, 27(12), 2060-2064 (2015);

[5] Near infrared photodetectors based on sub-gap absorption in organohalide perovskite single crystals, Q. Lin, A. Armin, P.L. Burn & P. Meredith, Laser and Photonics Reviews, 10(6), 1047-1053 (2016);

[6] Filterless, narrowband RGB photodetectors, Q. Lin, A. Armin, P.L. Burn & P. Meredith, Nature Photonics, 9, 687-694 (2015).

12:30 - 12:45
_________
12:45 - 14:00
Lunch
Session C1
Chair: Barry Rand
14:00 - 14:15
C1-O1
Delport, Géraud
Micro-photoluminescence study of 2D-layered perovskites crystals and thin films. Correlation between the structural and optoelectronics properties.
Géraud Delport
Authors
Géraud Delport a, Ferdinand Lédée a, Hiba Diab a, Gaëlle Trippé-Allard a, Damien Garrot a, Jean-Sébastien Lauret a, Emmanuelle Deleporte a
Affiliations
a, Laboratoire Aimé Cotton, CNRS, Univ. Paris-Sud, ENS Paris-Saclay, Université Paris-Saclay,91405 Orsay Cedex, FR
b, Groupe d'Etude de la Matière Condensée, UVSQ, 45 Avenue des Etats Unis, 78035, Versailles, FR
Abstract

Over the past few years, organic inorganic halide 3D perovskites (3D-HOP) were found to present remarkable optoelectronic properties. A great attention has been paid to perovskites thin films, as an ideal building block for PV and LED devices.  On the other hand, the study of single crystals has proven necessary to unveil some of the intrinsic properties of these semiconductors [1,2].

While the 2D perovskites have been known for decades, there is growing interest in their structure, for their strong PL properties, their chemical versatility and their low sensitivity to external degradation mechanisms ( due to UV light, water,…) .

In this poster, we will study the optical properties of phenylethylammonium based 2D perovskites (C6H5C2H4NH3)2PbI4 and their 2d/3d derivatives. A cryogenic micro-photoluminescence study will be presented (with a sub micrometer precision).  This technique allows to finely correlate the optoelectronic properties (excitons/phonons, …) of the produced films with their morphology. These properties are then compared to the ones of spin coated polycrystalline perovskites films. This study allows to extract the intrinsic properties of the perovskites crystals (electron phonon/ coupling, PL lifetimes). Finally, we will also compare our results to the one published on butylammonium based 2D perovskites, that  were recently used to create efficient  and long-lived solar cells [3], despite their large binding energies.

[1] Shi, Dong, et al. Science 347.6221 (2015): 519-522.

[2] H. Diab, G. Trippé-Allard, F. Lédée, K. Jemli, C. Vilar et al., J. Phys. Chem. Lett. 10.1021/acs.jpclett.6b02261

[3] Tsai, Hsinhan, et al. ." Nature 536.7616 (2016): 312-316.

The project leading to this application has received funding from the European Union’s Horizon 2020 programme, through a FET Open research and innovation action under grant agreement No 687008. The information and views set out in this abstract are those of the authors and do not necessarily reflect the official opinion of the European Union. Neither the European Union institutions and bodies nor any person acting on their behalf may be held responsible for the use which may be made of the information contained herein.

 

 

14:15 - 14:30
C1-O2
Devesa Canicoba, Noelia
Institute of Electronics and Telecommunications of Rennes
High-performance, hysteresis free, ambipolar hybrid perovskite based field-effect transistors
Noelia Devesa Canicoba
Institute of Electronics and Telecommunications of Rennes
Authors
Noelia Devesa Canicoba a, b, Kasun Fernando a, Jean-Christophe Blancon a, Fangze Liu a, Laurent Le Brizoual a, Regis Rogel a, Jacky Even a, Bruce W. Alphenaar a, Wanyi Nie a, Aditya D. Mohite a
Affiliations
a, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos NM, 87545, USA
b, Institute of Electronics and Telecommunications of Rennes (IETR), UMR CNRS 6164, University of Rennes 1, 35042 Rennes, France
c, Department of Electrical Engineering, University of Louisville, Louisville, KY 40292, USA
d, Fonctions Optiques pour les Technologies de l’Information (FOTON), Institut National des Sciences Appliquées (INSA) de Rennes, CNRS, UMR 6082, 35708 Rennes, France
Abstract

Hybrid perovskites are solution processed crystalline materials with excellent electronic and optical properties, which enables high-efficiency optoelectronic devices. However, hybrid perovskites-based field effect transistor operation at room temperature has remained elusive. This is due to the non-reproducibility induced by polar nature of the structure coupled with ionic motions, which screens the capacitively coupled gate voltage. In this study, we report high-performance, hysteresis-free ambipolar FETs using highly crystalline hybrid perovskites thin films, operating at room temperature. We systematically improved the film quality, the effect of high-K dielectrics between the perovskites and gate. As a result, we obtained FETs with high trans-conductance with low subthreshold slopes leading to an on/off ration >104. Moreover, we achieve ambipolar transport at room temperature that strongly correlates to the choice of the gate-dielectric, that allow to tune the Fermi energy of perovskites for electrons and holes injections. We anticipate these results will open up the systematic investigation on the electronic properties in hybrid perovskites materials, for the opportunities to discover novel devices functionalities such as ultrasensitive photo-transistors and spin FETs.

 

 

 

 

 

 

14:30 - 14:45
C1-O3
Aversa, Pierfrancesco
Effect of Defect Production on Photoluminescence Properties in He ion Implanted Methylammonium Lead Tri-Iodide Perovskite Layers
Pierfrancesco Aversa
Authors
Pierfrancesco Aversa a, Heejae Lee a, Minjin Kim a, Olivier Plantevin a, Olivier Cavani a, Nadége Ollier a, Bernard Geffroy a, b, Catherine Corbel a
Affiliations
a, LSI, UMR 7642 /CEA - CNRS - Ecole Polytechnique
b, LPICM, CNRS, Ecole Polytechnique, Université Paris-Saclay, F-91128 Palaiseau, France
c, CSNSM, CNRS, Université Paris-Sud, Université Paris-Saclay
d, LICSEN, NIMBE, CEA, CNRS, Université Paris-Saclay, CEA Saclay, F-91191 Gif-sur-Yvette, France
Abstract

Hybrid inorganic-organic halide perovskites attract much attention for their application in optoelectronic devices. However, the performance in domain such as photovoltaics still strongly depends on the quality of the active layers and their capacity to withstand device operation without irreversible damage.  Applying a bias in dark in CH3NH3PbI3 (MAPI) based solar cells results in ion migration [1]. This questions the generation and role of defects under bias and light illumination [2] on photovoltaics performance.

In this work, Helium ion implantation is used as a tool for the introduction of point defects in a controlled way in polycrystalline MAPI layers spin coated on glass/ITO/PEDOTT:PSS. The created point defects may introduce energy levels and modify electronic and light emitting properties of the material.  The defect production has a strong effect on the photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectra. The results illustrate how the PL and RTPL properties depend on the layer history before and after He ion implantation.

 

[1] Lee et al., Direct Experimental Evidence of Halide Ionic Migration under Bias in CH3NH3PbI3-xClx Based Perovskite Solar Cells using GD-OES Analysis, ACS Energy Lett., 2017 DOI: 10.1021/acsenergylett.7b00150

[2] DeQuilettes et al., Photo-induced halide redistribution in organic–inorganic perovskite films, Nature Communications, 2016 DOI: 10.1038/ncomms11683

14:45 - 15:00
C1-O4
Garrot, Damien
Groupe d'Etude de la Matière Condensée (GEMAC)
Impact of Reabsorption on the Emission Spectra and Recombination Dynamics of Hybrid Perovskite Single Crystals
Damien Garrot
Groupe d'Etude de la Matière Condensée (GEMAC), FR
Authors
Hiba Diab a, Christophe Arnold a, Ferdinand Lédée a, Gaëlle Trippé-Allard a, Géraud Delport a, Christèle Vilar a, Fabien Bretenaker a, Julien Barjon a, Jean-Sébastien Lauret a, Emmanuelle Deleporte a, Damien Garrot a
Affiliations
a, LAC, Ecole Normale Supérieure de Cachan, 61, avenue du Président Wilson, Cachan, 94235, FR
b, Groupe d'Etude de la Matière Condensée (GEMAC), 45 Avenue des Etats-Unis, 78035 Versailles Cedex, FR
Abstract

A better understanding of the surface and bulk photophysics of hybrid perovskite is crucial to improve the efficiency of devices. The study of high quality single crystals should enable to highlight the intrinsic properties of hybrid organic-inorganic perovskites (HOPs).1 However, there are important discrepancies in the literature regarding the basic optical properties of HOP single crystals, such as the emission spectra.2,3 Here, we have investigated the surface and bulk properties of CH3NH3PbBr3 single crystals with a combination of cathodoluminescence (CL), steady-state and time-resolved photoluminescence (PL) spectroscopy. Firstly, depth-resolved CL has been used to probe the near surface region on depth ranging from a few nanometers to several micrometers. Secondly, we have studied the transmitted PL through different thicknesses between 50 and 600 µm. In both cases, experimental emission spectra were compared with simulated spectra, taking into account reabsorption effect. The results reveal the strong impact of reabsorption on the emission of hybrid perovskites. Reabsorption effect explains mainly the large variation of the emission spectra reported for hybrid perovskite single crystals, as well as the existence of two PL peaks at room temperature. In addition, we show that hybrid perovskite single crystals, even with millimeter size, are partially transparent to their own luminescence and radiative transport is the dominant mechanism for the propagation of the excitation in thick crystals The transmitted PL presents a long rising time and a lengthening of its decay due to photon recycling and light-trapping.4

(1)      Diab, H.; Trippé-Allard, G.; Lédée, F.; Jemli, K.; Vilar, C.; et al. Narrow Linewidth Excitonic Emission in Organic-Inorganic Lead Iodide Perovskite Single Crystals. J. Phys. Chem. Lett. 2016, 7 (24), 5093–5100.

(2)      Yamada, T.; Yamada, Y.; Nakaike, Y.; Wakamiya, A.; Kanemitsu, Y. Photon Emission and Reabsorption Processes in CH3NH3PbBr3 Single Crystals Revealed by Time-Resolved Two-Photon-Excitation Photoluminescence Microscopy. Phys. Rev. Appl. 2017, 7 (1), 14001.

(3)      Sarmah, S. P.; Burlakov, V. M.; Yengel, E.; Murali, B.; Alarousu, E.; et al. Double Charged Surface Layers in Lead Halide Perovskite Crystals. Nano Lett. 2017, 17 (3), 2021–2027.

(4)      Diab, H.; Arnold, C.; Lédée, F.; Trippé-Allard, G.; Delport, G.; et al. Impact of Reabsorption on the Emission Spectra and Recombination Dynamics of Hybrid Perovskite Single Crystals. J. Phys. Chem. Lett. 2017, 8 (13), 2977–2983.

 

15:00 - 15:15
C1-O5
Gelvez-Rueda, María Camila
Delft University of Technology
Effect of the organic cation on 2D organic-inorganic Perovskites
María Camila Gelvez-Rueda
Delft University of Technology, NL
Authors
María Gélvez-Rueda a, Eline Hutter a, Duyen Cao a, Nicolas Renaud a, Constantinos Stoumpos a, Joseph Hupp a, Tom Savenije a, Mercouri Kanatzidis a, Ferdinand Grozema a
Affiliations
a, Chemical Engineering, Optoelectronic Materials, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
b, Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
Abstract

The opto-electronic properties of 2D organic-inorganic perovskites are largely affected by the nature of the organic cation and the number of inorganic octahedrals layers in between the organic cation. It has been shown that varying the length of alkyl chains, valency, functioning group and thickness of if inorganic layers affect the band gap and effective confinement. There is a lack of understanding on how this changes affect the charge and excited state dynamics. In this work we have studied the charge and excited state dynamics of 2D organic-inorganic perovskites with different organic groups and thickness of layers  by temperature dependent absorption, photo-luminescence and microwave conductivity measurements. We have found that properties such as mobility, yield of charge dissociation, exciton binding energy, and electronic transitions are also affected by the organic cation nature, thickness of inorganic layers and temperature. For example, in 2D (BA)2(MA)n-1PbnI3n+1 Ruddlesden-Popper hybrid perovskites, our combined experimental results show a clear increase of the mobility, probability of exciton dissociation and lifetime of charges with the thickness of the [(MA)n-1PbnI3n+1]2- slabs. The increase in mobility is consistent with DFT calculations that show a decrease of the effective mass of holes. In addition, the temperature trend of the yield of exciton dissociation was analyzed in the framework of the Saha equation to show that the exciton binding energies range between ~80 meV and ~370 meV depending on the thickness of the [(MA)n-1PbnI3n+1]2- slabs. Understanding these interactions will help to design 2D organic-inorganic perovskites with specific functionalities.

15:15 - 15:30
C1-O6
Asuo, Ivy
Institut National de la Recherche Scientifique - Énergie, Matériaux et Télécommunications, Université du Québec
High performance and stable pseudohalide perovskite nanowires photodetector
Ivy Asuo
Institut National de la Recherche Scientifique - Énergie, Matériaux et Télécommunications, Université du Québec, CA
Authors
Ivy M. Asuo a, b, Dawit Gedamu a, Ibrahima Ka a, Luis Felipe Gerlein a, Alain Pignolet a, Sylvain G. Cloutier a, Riad Nechache a
Affiliations
a, Département de Génie Électrique, École de Technologie Supérieure, 1100 rue Notre-Dame Ouest, Montréal, QC, Canada
b, INRS, Centre for Energy, Materials and Telecommunications, 1650 Boul. Lionel Boulet, Varennes, QC, Canada
Abstract

High-speed photodetectors are in high demand in many fields including imaging, optical communications, chemical species detection, and other types of optical instrumentation. Mostly, these photodetectors use silicon or semiconductor alloys to build devices that require costly fabrication methods. Recently, organometal halide perovskites have demonstrated outstanding optoelectronic properties such as tunable optical properties, high charge mobility, and long charge diffusion length. In the work, we report a stable, reproducible and reliable pseudohalide perovskite nanowire network based photodetector with superior photodetection performance. The perovskite nanowire networks are deposited onto micropatterned substrates under ambient conditions of relative humidity (RH), higher than 50 % through a two-step spin coating method. Because of the 1D perovskite structure, our devices require no charge extractors which is advantageous for low-cost fabrication and processing simplicity. The photoresponse measurements indicate broad spectral response from 300 to 850 nm, high spectral responsivity, time response and photocurrent. This results indicate that photocurrent generation is due to the charge transfer within the nanowire networks and present a simple, fast and low-cost solution fabrication technique of perovskite nanowire-based photodetectors in ambient air.

15:30 - 15:45
C1-O7
Pedesseau, Laurent
INSA, FOTON, UMR CNRS 6082
Layered/3D Halide Hybrid Perovskite Semiconductors: Advances and Promises
Laurent Pedesseau
INSA, FOTON, UMR CNRS 6082, FR

He obtained his MSc in condensed matter from the University of Montpellier in 2001. In 2004, he received his PhD in physics from the University of Toulouse for atomistic empirical simulations applied to Civil Engineering materials. In 2013, he was appointed as assistant professor at FOTON laboratory (INSA Rennes) to work on III–V semiconductor nanostructures for silicon photonics, hybrid-perovskites for photovoltaics, and optoelectronic device simulations for optical telecommunication.

Authors
Laurent Pedesseau a, Daniel Sapori a, Boubacar Traore a, Roberto Robles a, Hong Hua Fang a, Maria A Loi a, Hsinhan Tsai a, Wanyi Nie a, Jean Christophe Blancon a, Amanda Neukirch a, Sergei Tretiak a, Aditya Mohite a, Claudine Katan a, Jacky Even a, Mikael Kepenekian a
Affiliations
a, Fonctions Optiques pour les Technologies de l'information (FOTON), UMR 6082 INSA de Rennes - CNRS, France
b, Institut des Sciences Chimiques de Rennes (ISCR), UMR 6226 Université de Rennes 1 - CNRS, France
c, Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona, Spain
d, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen 9747 AG, The Netherlands
e, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
Abstract

Layered halide hybrid organic–inorganic perovskites (HOP) have been intensively studied in the past for applications in optoelectronics and microelectronics before the rise of three-dimensional (3D) HOP and their impressive performance in solar cells. Recently, layered HOP have also been proposed as attractive alternatives for photostable solar cells and revisited for light-emitting devices. The ability to modify the composition and shape of these hybrid heterostructures allows tuning quantum and dielectric confinements of charge carriers. These effects are of prime importance for photovoltaic and optoelectronic applications.

We combine classical solid-state physics concepts with atomistic codes based on the density functional theory to analyze the optoelectronic properties of layered HOP. A detailed comparison between layered and 3D HOP is performed to highlight differences and similarities. It allows for thorough analysis of the spin–orbit coupling effects and structural transitions with corresponding electronic band structure folding. We further investigate the effects of octahedral tilting on the band gap, the loss of inversion symmetry and the related Rashba effect, the quantum confinement, the dielectric confinement related to the organic barrier and finally to the excitonic properties. Finally, our study provides an interpretive and predictive framework for the optoelectronic properties of 3D and 2D layered HOP.

15:45 - 16:00
C1-O8
Andaji Garmaroudi, Zahra
University of Cambridge
Efficient Energy Transfer in Mixed Halide Perovskite Semiconductors
Zahra Andaji Garmaroudi
University of Cambridge, GB
Authors
Zahra Andaji Garmaroudi a, Mojtaba Abdi Jalebi a, Sam Stranks a
Affiliations
a, University of Cambridge, The Old Schools, Trinity Ln, Cambridge CB2 1TN, UK, Cambridge, GB
Abstract

Solution-processable metal halide perovskites show immense promise for use in photovoltaics and other optoelectronic applications. Expanding the perovskite family to materials with a range of different bandgaps is opening up the potential of this materials system for a range of different applications, including the design of tandem PV cells and other optoelectronic components such as lasers and light emitting diodes. Introducing a mixture of bromide and iodide in the halide composition allows tuning of the optical bandgap. However, these perovskites are not stable against phase segregation in the entire range of composition, which can affect measurements and performance when the material is photoexcited. In this work we studied photo-physical properties of novel mixed-halide perovskite systems using different characterization techniques. We conducted steady-state and transient studies, enabling determination of the mechanism of segregation and charge transport in mixed-halide perovskites. Our results demonstrate that charge transfer to iodide-rich domains happens in a very efficient way, and we observed a significant increase in PLQE in these mixed halide perovskites, in which almost all the recombination is radiative.

  

Session D1
Chair: Maksym Kovalenko
14:00 - 14:15
D1-O1
Wright, Adam
University of Oxford
Band Tail States in FAPbI3: Characterization and Simulation
Adam Wright
University of Oxford, GB
Authors
Adam Wright a, Rebecca Milot a, Giles Eperon a, Henry Snaith a, Michael Johnston a, Laura Herz a
Affiliations
a, Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom
Abstract

The success of perovskite photovoltaics is underpinned by their favourable optoelectronic properties, notably their combination of high charge-carrier mobilities with low rates of charge-carrier recombination[1]. Sub-bandgap trap states in hybrid lead halide perovskites can act as nonradiative recombination centres, leading to shorter charge-carrier lifetimes and limiting the open-circuit voltage (Voc) in perovskite solar cells[2]. It is therefore essential to understand the nature and energy scale of these trap states for the development and optimization of technology based on these materials.

In this study[3] we investigated the influence of sub-bandgap trap states on charge-carrier recombination through an analysis of the low-temperature photoluminescence (PL)  of FAPbI3, a perovskite material used in some of the most efficient and stable perovskite solar cells [4]. We observed a power-law time dependence in the emission intensity and an additional low-energy emission peak that exhibits an anomalous relative Stokes shift. Using a rate-equation model and a Monte Carlo simulation, we revealed that both phenomena arise from an exponential trap-density tail with characteristic energy scale of ≈3 meV. Since charge-carrier recombination from sites deep within the tail causes emission with energy downshifted by up to several tens of meV, such phenomena may in part be responsible for Voc losses commonly observed in these materials. We propose that the origin of the band-tail states in FAPbI3 may lie in the rotational freedom of the polar organic cation. These results underline the suitability of viewing hybrid perovskites as classic semiconductors, whose electronic bandstructure picture is moderated by a modest degree of energetic disorder.

[1]         C. Wehrenfennig, G. E. Eperon, M. B. Johnston, H. J. Snaith, L. M. Herz, Adv. Mater. 2014, 26, 1584.

[2]         A. Baumann, S. Väth, P. Rieder, M. C. Heiber, K. Tvingstedt, V. Dyakonov, J. Phys. Chem. Lett. 2015, 6, 2350.

[3]         A. D. Wright, R. L. Milot, G. E. Eperon, H. J. Snaith, M. B. Johnston, L. M. Herz, Adv. Funct. Mater. 2017, 27, 1700860.

[4]         W. S. Yang, J. H. Noh, N. J. Jeon, Y. C. Kim, S. Ryu, J. Seo, S. Il Seok, Science 2015, 348, 1234.

 

14:15 - 14:30
D1-O2
CHE, Xiaoyang
UMR FOTON CNRS 6082, INSA, 35708 Rennes, France
First principles study of surface defects and luminescence recovery of CH3NH3PbBr3 by H2O and O2 gas
Xiaoyang CHE
UMR FOTON CNRS 6082, INSA, 35708 Rennes, France
Authors
Xiaoyang Che a, b, Hong-Hua Fang a, Maria Antonietta Loi a, Claudine Katan a, Mikael Kepenekian a, Jacky Even a
Affiliations
a, Institut des Sciences Chimiques de Rennes (ISCR), UMR 6226, CNRS, Université de Rennes 1, Ecole Nationale Supérieure de Chimie de Rennes INSA Rennes, France
b, Fonctions Optiques pour les Télécommunications (FOTON), UMR 6082, CNRS, INSA Rennes, Université de Rennes 1, France
c, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, The Netherlands
Abstract

The recent revolutionary increase of power conversion efficiency demonstrated by perovskite-based solar cells has given rise to great interest from the scientific community. In the last few years, an ever-increasing number of experimental and theoretical studies have been performed on 3-dimensional hybrid halide perovskite  such as CH3NH3PbX3 (X=Br, I). Here, we consider CH3NH3PbBr3 that is known to have good luminescent properties. So far, the surface defects are one of the major factors for fluorescence quenching [1]. It has recently been reported that exposition to moisture and O2 gas can recover the luminescent properties [2-4]. In order to elucidate the luminescence quenching-reactivation mechanism, we herein carefully inspect the structural, electronic and optical properties both for bulk and (001) surface of CH3NH3PbBr3 using atomic scale simulations.

References: [1] G. Grancini et al. Chem. Sci. (2015), 6, 7305-7310; [2] H.-H Fang et al. Sci. Adv. (2016), 2, 7; [3] H. Wei et al. Nature Photonics (2016), 10, 333;  [4] Yin, W.-J et al. Adv. Electron. Mater. (2015), 1, 1500044.

14:30 - 14:45
D1-O3
Infante, Ivan
Vrije Universiteit Amsterdam
Computational Chemistry to Design Colloidally Stable and Trap-free Perovskite Nanocrystals
Ivan Infante
Vrije Universiteit Amsterdam, NL
Authors
Ivan Infante a, Simon Boehme a
Affiliations
a, Department of Chemistry and Pharmaceutical Sciences, Division of Theoretical Chemistry, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
Abstract

Colloidal metal halide perovskite nanocrystals recently emerged as promising candidate materials for optoelectronic applications such as light-emitting diodes (LEDs), lasing, fluorescence lifetime imaging (FLIM), and solar cells. Despite the superior optoelectronic properties found in fundamental studies, building efficient and long-lasting devices from perovskite nanocrystals remains a challenge: the unstable composition, related to its ionic core, combined with the labile ligand binding5 lead to structural degradation; it complicates the post-synthesis purification routines, limits the options for ligand exchange, and reduces the colloidal stability. A higher degree of control over nanocrystal surface properties may mitigate those effects, i.e. increase the nanocrystals’ purity, versatility, and durability, respectively.

In this study, we introduce a structural framework for classification of the perovskite nanocrystal core and the surface, deduce the most commonly found aging mechanism using density functional theory, and compute its effect on the electronic structure. Based on our detailed insight into the aging process at the perovskite nanocrystal surface, we propose a general strategy for increasing colloidal stability and eliminating traps. The latter may also serve as a guideline for developing passivation strategies for grain boundaries in thin-film devices (e.g. solar cells), possibly also of other semiconducting materials.

14:45 - 15:00
D1-O4
LEGRAND, Laurent
Sorbonne Universités, UPMC Univ Paris 06, UMR CNRS 7588, Institut des Nanosciences de Paris (INSP)
Fine Structure of Excitons and their Interactions with Phonons in Polymorphic CsPbBr3 Single Nanocrystals
Laurent LEGRAND
Sorbonne Universités, UPMC Univ Paris 06, UMR CNRS 7588, Institut des Nanosciences de Paris (INSP)
Authors
Laurent Legrand a, Julien Ramade a, Léon Marcel Andriambariarijaona a, Violette Steinmetz a, Thierry Barisien a, Frédérick Bernardot a, Christophe Testelin a, Emmanuel Lhuillier a, Quentin Glorieux a, Alberto Bramati a, Maria Chamarro a
Affiliations
a, Sorbonne Universités, UPMC Université Paris 06, CNRS-UMR 7588, Institut des NanoSciences de Paris, 4 place Jussieu, 75005 Paris, France
b, Laboratoire Kastler Brossel, UPMC – Sorbonne Universités, CNRS, ENS-PSL, Research University, Collège de France, 4, place Jussieu, case 74, 75005 Paris, France
Abstract

We investigate the exciton fine structure (EFS) and exciton-phonon coupling (EPC) of individual CsPbBr3 nanocrystals (NCs). These NCs belong to the novel class of confined inorganic metal-halide perovkites that currently arouses enthusiasm and stimulates a huge activity due to its outstanding attendant properties within several fields of optoelectronics. The NCs studied in this work are synthesized in a form of colloidal solution through a previously described method [1] and present a cubic shape, which length dispersion is very sensitive to the temperature synthesis.

Micro-photoluminescence (μ-PL) measurements at cryogenic temperature reveal an EFS composed by either two or three Lorentzian-shaped ultrasharp peaks, which directly mirrors the adopted crystalline structure [2], namely tetragonal (doublet) or orthorhombic (triplet). We show through polarization-resolved μ-PL that these peaks are orthogonally polarized. Fine analysis of the energy structure allows to determine both exchange energy terms and crystal field terms for both structure, as well as an estimation of the dark state position in the EFS.

In a second time, EPC is studied in single polymorphic NCs. For this purpose, we perform for the first time μ-PL measurements on selectively polarized lines under various temperature from 4K to 80K. The temperature-dependence of emission linewidth follows the empirical Bose-Einstein model [3], which accounts for charge-phonon coupling for both acoustic and LO (Fröhlich) phonons. We find that acoustic coupling dominates the low temperature regime (up to 30K) while in the higher temperatures, broadening is mainly ruled by the Fröhlich term.

Our results bring fundamental information for the understanding of the CsPbBr3 excitonic response as single emitters and provide new insights into their optical properties and performances for future integration in devices such as quantum sources.

[1] L. Protesescu, S. Yakunin, M.I. Bodnarchuk et al., Nano Lett. 15, 3692 (2015)

[2] M. Fu, P. Tamarat, H. Huang et al., Nano Lett. 17, 2895 (2017)

[3] S. Rudin, T.L. Reinecke and B. Segall, Phys. Rev. B. 42, 11218 (1990)

15:00 - 15:15
D1-O5
Tao, Shuxia
Technology University of Eindhoven
Accurate and efficient band gap predictions of metal halide perovskites using the DFT-1/2 method: GW accuracy with DFT expense
Shuxia Tao
Technology University of Eindhoven
Authors
Shuxia Tao a, Xi Cao a, Peter Bobbert a
Affiliations
a, Department of Applied Physics, Eindhoven University of Technology (TU/e), the Netherlands
Abstract

The outstanding optoelectronics and photovoltaic properties of metal halide perovskites, including high carrier motilities, low carrier recombination rates, and the tunable spectral absorption range are attributed to the unique electronic properties of these materials. While DFT provides reliable structures and stabilities of perovskites, it performs poorly in electronic structure prediction. The relativistic GW approximation has been demonstrated to be able to capture electronic structure accurately, but at an extremely high computational cost. Here we report efficient and accurate band gap calculations of halide metal perovskites by using the approximate quasiparticle DFT-1/2 method. Using AMX3 (A = CH3NH3, CH2NHCH2, Cs; M = Pb, Sn, X = I, Br, Cl) as demonstration, the influence of the crystal structure (cubic, tetragonal or orthorhombic), variation of ions (different A, M and X) and relativistic effects on the electronic structure are systematically studied and compared with experimental results. Our results show that the DFT-1/2 method yields accurate band gaps with the precision of the GW method with no more computational cost than standard DFT. This opens the possibility of accurate electronic structure prediction of sophisticated halide perovskite structures and new materials design for lead-free materials.

15:15 - 15:30
D1-O6
Kepenekian, Mikael
CNRS
Making and breaking of the exciton in layered halide hybrid perovskites
Mikael Kepenekian
CNRS, FR
Authors
Mikaël Kepenekian a, Boubacar Traore a, Jean-Christophe Blancon a, Hsinhan Tsai a, Wanyi Nie a, Constantinos Stoumpos a, Laurent Pedesseau a, Claudine Katan a, Sergei Tretiak a, Mercouri Kanatzidis a, Jacky Even a, Aditya Mohite a
Affiliations
a, Institut des Sciences Chimiques de Rennes (ISCR), UMR 6226, CNRS, Université de Rennes 1, Ecole Nationale Supérieure de Chimie de Rennes INSA Rennes, France
b, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
c, Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
d, Fonctions Optiques pour les Télécommunications (FOTON), UMR 6082, CNRS, INSA Rennes, Université de Rennes 1, France
Abstract

Layered halide hybrid organic−inorganic perovskites [1] have been the subject of intense investigation before the rise of three-dimensional (3D) halide perovskites and their impressive performance in solar cells. Recently, layered perovskites have also been proposed as attractive alternatives for photostable solar cells [2] and revisited for light-emitting devices. Interestingly, these performances can be traced back to extremely efficient internal exciton dissociation through edge states identified on thin films and single crystals [3].

Layered perovskites present fascinating features with inherent quantum and dielectric confinements imposed by the organic layers sandwiching the inorganic core, and computational approaches have successfully help rationalized their properties (excitonic, Rashba effects, etc.) [4-6]. Here, we propose a joint spectroscopic and computational investigation to unravel the origin of the recently identified layer-edge states in layered Ruddlesden-Popper phases with inorganic layers containing n = 1 to 4 octahedra. We show that for n > 2, the system presents a localized surface state within the band gap.

 

References

[1] L. Pedesseau et al., ACS Nano (2016), 10, 9776.

[2] H. Tsai et al., Nature (2016), 536, 312.

[3] J.-C. Blancon et al., Science (2017), 355, 1288.

[4] M. Kepenekian et al., ACS Nano (2015), 12, 11557.

[5] D. Sapori, M. Kepenekian, L. Pedesseau, C. Katan, J. Even, Nanoscale (2016), 8, 6369.

[6] M. D. Smith et al., Chem. Sci. (2017), 8, 1960.

15:30 - 15:45
D1-O7
Kostadinov - Mutzafi, Alyssa
Technion-Israel Institute of Technology
Rashba effect as a source for a long carrier diffusion length in nanostructures assembly and bulk halide perovskites
Alyssa Kostadinov - Mutzafi
Technion-Israel Institute of Technology, IL
Authors
Alyssa Kostadinov - Mutzafi a, Maya Isarov a, Liang Zheng Tan a, Andrew Rappe a, Efrat Lifshitz a
Affiliations
a, Technion – Israel Institute of Technology
b, University of Pennsylvania, 200 South 33rd Street, Philadelphia, 19104, US
Abstract

During the past few years, hybrid organic-inorganic perovskites have become one of the most promising materials in the photovoltaic field, when in less than four years, the efficiency of perovskite solar cells has quickly leapt from 3.81% to > 22.0%. Perovskites have also been demonstrated as suitable materials for detecting visible light, x-ray, or γ-ray.

The talk will include description of a research work associated with all-inorganic bromide- perovskite, CsPbBr3, as nanocrystals and bulk forms.  This compound was selected for the study due to its relative chemical and photochemical stability.  The nature of carriers at the excited state were investigated by following the interplay of Rashba and band-edge exciton effects in a single colloidal nanocrystals (NCs) or a single bulk specie.  The samples were supplied by the group of Prof. Maksym Kovelenko at ETH. In a single NC, pronounced evidence for the Rashba effect in the excitonic magneto-photoluminescence spectra was observed.  It was measured via examination of the linearly and circularly polarized photoluminescence of a single particle under an applied magnetic field. The experiments resolve discrete narrow excitonic transitions with an energy splitting that increases nonlinearly with the magnetic field strength. The nonlinearity in the exciton photoluminescence (PL) splitting observed in the experiment is supported by theoretical calculations (in collaboration with the group of Prof. Andrew Rappe), suggesting a crossover between the Rashba effect at low magnetic fields to a Zeeman effect at higher fields.  Current observations on bulk CsPbBr3 single crystal, reflect similar observations for those viewed in the analogous NCs, particularly when examined along unique crystallographic direction.  In addition, the observations found in the bulk samples indicate a plausible contribution of cubic Rashba effect, which may indicate a mixing of high lying states to the band-edge properties. The Rashba effect splits the band edge extrema to a k¹0 a Brillouin point with momentum forbidden transitions, thus, extending the carriers lifetime at the excited state.  It is currently proposed that the Rashba effect is one of the main sources that endows a long diffusion length for carriers in perovskites materials.

15:45 - 16:00
D1-O8
Mayou, Didier
CNRS
Modelisation of disorder and localisation effect for electrons and holes in MAPI
Didier Mayou
CNRS, FR
Authors
Antoine Lacoix a, Guy Trambly de Laissardière a, Jean-Pierre Julien a, Didier Mayou a
Affiliations
a, Institut Néel, CNRS and Université Grenoble-Alpes /Grenoble
b, LPTM Université de Cergy Pontoise/CNRS /Cergy Pontoise
Abstract

The electron and hole mobilities in MAPbI3 are of the order of a few 10cm2/Vs and in view of the effective mass estimated by band structure calculations of the order of 0.2 me the scattering time is expected to be very short of the order of a few Femto seconds. Recent ARPES measures indicate also a very short scattering time [1]. This suggest that the electronic mean-free path is short, of the order of a few unit cells. One may therefore expect the occurence of strong quantum effects on the transport.

We consider a tight-binding model, which parameters have been determined from band structure calculations [2] for the perfect structure. Our model takes into account in addition the presence of diagonal or off diagonal disorder at a level compatible with the measured mobilities. We compute the diffusion by a method that we used recently to analyze the mobility of organic semi-conductors [3]. We find that the semi-classical models (Drude like or Bloch-Boltzmann) cannot be applied to describe the hole transport in MAPI. We find that localization effects due to disorder take place in these systems at all energies in a window of 1 eV below the top of the valence band . The ratio between the mobility estimated by a semi-classical theory and the exact mobility can be of the order of 10-30 , at energies close to the top of the valence band.

We compute also the ac-conductivity in the Terahertz range. Our results compare well with recent experiments which also suggest the existence of quantum localisation [4].

 

[1] M. Lee et al. J.Phys.D. Appl. Phys 50 , p 26LT02 (2017)

[2] S. Boyer Richard et al. Physical Chemistry Letters ,7,p 3833 (2016)

[3] S. Fratini et al. Nature Materials 16, p 998 (2017)

[4] L.Luo et al. Nature Communications 8, p 15565 (2017)

16:00 - 16:15
Closing PEROPTO
 
Posters
Shuxia Tao, Jie Cao, Ni Zhao, Peter Bobbert
Atomistic View of Interstitial Occupation of Small Alkali Cations in Perovskites and Its Impact on Ion Migration
Afonso da Cunha Ferreira, Antoine Létoublon, Serge Paofai, Stéphane Raymond, Claude Ecolivet, Benoit Rufflé, Stéphane Cordier, Claudine Katan, Makhsud Saidaminov, Ayan Zhumekenov, Osman Bakr, Philippe Bourges, Jacky Even
Elastic softness of hybrid lead halide perovskites
Manon Spalla, Emilie Planes, Lara Perrin, Muriel Matheron, Matthieu Manceau, Solenn Berson, Lionel Flandin
Perovskite solar cell intrinsic stability: elucidation of degradation processes using a combination of characterization techniques
Man Yu, Hao-Yi Wang, Xi-Cheng Ai, Yujun Qin, Jian-Ping Zhang
Power Output, Carrier Dynamics, Hysteresis Studies of Perovskite Solar Cells
Sudeep Maheshwari, Nicolas Renaud, Tom Savenije, Ferdinand Grozema
Computational design of novel 2D lead iodide perovskites
Boubacar Traore, Laurent Pedesseau, Linda Assam, Xiaoyang Che, Jean-Christophe Blancon, Hsinhan Tsai, Wanyi Nie, Constantinos C. Stoumpos, Mercouri G. Kanatzidis, Sergei Tretiak, Aditya D. Mohite, Jacky Even, Mikaël Kepenekian, Claudine Katan
Composite approach towards layered hybrid perovskites: Implications on band alignment and quantum and dielectric confinements
Yong Huang, Sigalit Aharon, Alexandre Gheno, Sylvain Vedraine, Laurent Pedesseau, James Connolly, Claudine Katan, Mikaël Kepenekian, Jean-Philippe Burin, Oliver Durand, Johann Bouclé, Lioz Etgar, Jacky Even, Alain Rolland
Numerical investigation of the effect of interface conditions in HTM-free, printable WOx based and inverted perovskite solar cells
Alain Rolland, L. Pédesseau, Y. Huang, S. Wang, D. Sapori, C. Cornet, O. Durand, J. Even, M. Kepenekian, C. Katan
Computational design of high performance hybrid perovskite on silicon 2-T tandem solar cells based on a tunnel junction
Merabet Boualem
Effects of Bismuth Incorporation in CsPbI3 on All Inorganic Perovskite Solar Cells Performances
Li-Li Gao, Guan-Jun Yang
Small molecule-driven directional movement enabling pin-hole free perovskite film via fast solution engineering
Carlos Echeverría-Arrondo, Juan Bisquert
Surface Polarization by Schottky Disorder in Perovskite Solar Cells from First Principles
Simon Boehme
How can we dispose of heat in semiconductor nanocrystals?
N. H. Nickel, F. Lang, V. V. Brus, J. Rappich
Light-induced degradation of methylammonium and formamidinium lead iodide perovskites
Vera La Ferrara, Antonella De Maria, Gabriella Rametta, Marco Della Noce, Lucia Vittoria Mercaldo, Carmela Borriello, Annalisa Bruno, Paola Delli Veneri
Improvement of performance for ZnO nanorods/AZO photoanode based perovskite solar cells fabricated in ambient air
Yuiga Nakamura, Tomonori Matsushita, Shu Yamaguchi, Takashi Kondo
Defect chemistry analysis on CH3NH3PbI3 toward conductivity control of lead-halide perovskites
Hilal Balout, Marcelo Andres Carignano, Laurent Le Pollès, Claire Roiland, Eric Furet, Jacky Even, Claudine Katan
CH3NH3+ Dynamics in CH3NH3PbBr3 by Combining Solid-State NMR and Molecular Dynamics Calculations
Hong ZHANG, Jiaqi Cheng, Dan Li, Francis Lin, Jian Mao, Chunjun Liang, Alex K.-Y. Jen, Michael Grätzel, Wallace Choy
High-performance and stable perovskite solar cells achieved by a new all room-temperature solution-process
Yoshiki Uematsu, Masahiro Yoshizawa-Fujita, Yuko Takeoka, Masahiro Rikukawa
Perovskite Solar Cells Using Novel Amines (IV) -Modification of Photovoltaic Cells by Adding Acetamidinium Cation-
Ryosuke Arai, Masahiro Yoshizawa-Fujita, Yuko Takeoka, Masahiro Rikukawa
Functionalization of two-dimensional perovskites by incorporating carboxy group
azin babaei, Maria-Grazia La-Placa, Yousra El-Ajjouri, Laura Martínez-Sarti, Pablo p.boix, Michele Sessolo, Henk J. Bolink
Vacuum-Processed Methylammonium Lead Halide Light-Emitting Diodes
Kazuya Yamamoto, Noriyuki Takada, Masanao Era, Hideyuki Kunugita, Kazuhiro Ema
Optical properties of cavity polaritons in microcavities containing organic-inorganic two-dimensional perovskite materials
Jennifer Dewalque, Damien Baron, Gilles Spronck, Audrey Schrijnemakers, Anthony Maho, Pierre Colson, Rudi Cloots, Jérôme Loicq, Catherine Henrist
Opal-like photoanodes with photonic effects in macroporous perovskite solar cells
Matthew Schulz, Yosuke Udagawa, Yuiga Nakamura, Kohei Kimura, Chinami Yura, Kazuya Yamamoto, Tomonori Matsushita, Takashi Kondo, Hideyuki Kunugita, Kazuhiro Ema
Exciton Structure of Perovskite Single Crystals (CH3NH3PbBr3 and CH3NH3PbI3)
Karla Jiménez-Meza, Eduardo Menéndez-Proupin
Theoretical study of the band alignment of the Cu2O/CH3NH3PbI3 interface
Junke Jiang, Peter A. Bobbert, Shu Xia Tao
Influence of Ion-Exchange on Lead-Free Inorganic Sn Halide Perovskites
Enrico Cescon, Francesco Lamberti, Moreno Meneghetti, Lorenzo Franco
EPR investigation on the origin of suppressed hysteresis in laser-ablated hybrid perovskite nanoparticles
Fiona McGrath, Kevin Ryan
Lead free, tin and germanium perovskites
Audrey Schrijnemakers, jennifer Dewalque, Gilles Spronck, Anthony Maho, Pierre Colson, Rudi Cloots
Spray coating as scalable deposition technique of TiO2 blocking layer to boost the perovskite solar cell performances
Philipp Tockhorn, Ganna Chistiakova, Mathias Mews, Lars Korte, Steve Albrecht, Bernd Rech
Comparative Study of differently processed Tin Oxide Layers in regular perovskite solar cells
Ferdinand Lédée, Gaëlle Trippé-Allard, Hiba Diab, Pierre Audebert, Damien Garrot, Jean-Sébastien Lauret, Emmanuelle Deleporte
Monocrystalline thin films of low-dimensionnal hybrid perovskites by rapid vapor-assisted process
Samy Almosni, Takeru Bessho, Satoshi Uchida, Takaya Kubo, Hiroshi Segawa, Tang Zeguo
Hysteresis-less and efficient planar perovskite solar cells using amorphous TiO2
Piotr Krupinski, Anna M. Cieslak, Daniel Prochowicz, Janusz Lewinski
Challenges in design and synthesis of zinc oxide nanocrystalline materials for applications in planar and mesoporous perovskite solar cells
Ricardo M. R. Adão, Udayabhaskararao Thumu, Bruno Romeira, Yury V. Kolen’ko, Tangyou Sun, Jana B. Nieder
Optical Characterization of Functional Materials for Improved Light Emitting Devices
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