Tue Mar 05 2019
07:45 - 08:45
08:45 - 09:00
Opening and announcement of the day
Session 1.1
Chair: Henk Bolink
09:00 - 09:30
Nazeeruddin, Mohammad
École Polytechnique Fédérale de Lausanne EPFL
Mohammad Nazeeruddin
École Polytechnique Fédérale de Lausanne EPFL, CH

Dr. Md. K. Nazeeruddin received M.Sc. and Ph. D. in inorganic chemistry from Osmania University, Hyderabad, India. His current research focuses on Dye-sensitized solar cells, Hydrogen production, Light-emitting diodes and Chemical sensors. He has published more than 400 peer-reviewed papers, nine book chapters, and inventor of 49 patents. The high impact of his work has been recognized with invitations to speak at over 100 international conferences. He appeared in the ISI listing of most cited chemists, and has more than 10000 citations with an h-index of 93. He is directing, and managing several industrial, national, and European Union projects on Hydrogen energy, Photovoltaics (DSC), and Organic Light Emitting Diodes. He was awarded EPFL Excellence prize in 1998 and 2006, Brazilian FAPESP Fellowship in 1999, Japanese Government Science & Technology Agency Fellowship, in 1998, Government of India National Fellowship in 1987-1988. Recently he has been appointed as World Class University (WCU) professor for the period of March 1, 2009 ~ December 31, 2012 by the Korea University, Jochiwon, Korea.

Mohammad Nazeeruddin a
a, École Polytechnique Fédérale de Lausanne EPFL, CH

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09:30 - 09:45
Longo, Giulia
Department of Physics of University of Oxford
Vacuum-deposited Cs2AgBiBr6. Photovoltaic devices and fundamental characterization.
Giulia Longo
Department of Physics of University of Oxford, GB
Giulia Longo a, Suhas Mahesh a, Jongchul Lim a, Pabitra Nayak a, Henry J. Snaith a
a, Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, GB

Lead-free double-perovskites (A2M+M3+X6) have been recently proposed as a stable and environmental friendly alternative to lead-based perovskites. Among the vast number of possible double-perovskite compositions, Cs2AgBiBr6 has been the most investigated material, both from a theoretical and experimental point of view. To date, the majority of fundamental studies on this material have been conducted on single crystals or powders, which is due to the poor solubility of the material precursors and to difficulties in obtaining smooth and uniform films. Vapour deposition offers to be a promising alternative for the formation of Cs2AgBiBr6 films, overcoming the drawbacks of traditional solution chemistry methods and time-consuming growth of single crystals. In particular, physical vapour deposition can produce high-quality films with various thicknesses and smooth surfaces. In this way, numerous spectroscopic techniques which require non-scattering surfaces (like TRPL or THz spectroscopy), as well as thickness-dependent measurements can be conducted achieving an insight in the optoelectronic properties of the material. Here, we disclose our recent findings on vapour-deposited Cs2AgBiBr6, demonstrating not only efficient double-perovskite solar cells, but also presenting a fundamental understanding of the carriers dynamics in the double-perovskite thin films, not achievable otherwise.

09:45 - 10:15
Míguez, Hernán
Consejo Superior de Investigaciones Científicas (CSIC)
Perovskite Nanocrystals in Mesostructured Media: from Materials to Devices
Hernán Míguez
Consejo Superior de Investigaciones Científicas (CSIC), ES

Hernán Míguez (born in Buenos Aires, Argentina, 1971) is Research Professor of the Spanish Research Council (CSIC) in the Institute of Materials Science of Seville. He studied Physics in the Universidad Autónoma de Madrid and did his PhD in the Institute of Materials Science of Madrid. After a postdoctoral stay at the University of Toronto in the group of Prof. Ozin, he returned to Spain and joined the CSIC in 2004. He leads the group of Multifunctional Optical Materials, whose activities are devoted to the development, characterization and modeling of new photonic architectures for applications in different fields, among them solar energy conversion and light emission. He has received an ERC starting grant (2012, Consolidator Modality) and the “Real Sociedad Española de Física-Fundación BBVA 2017” Prize in the modality of “Physics, Innovation and Technology”.

Hernán Míguez a, Laura Calió a, Andrea Rubino a, Mauricio E. Calvo a
a, Multifunctional Optical Materials Group, Instituto de Ciencia de Materiales de Sevilla, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla, Américo Vespucio 49, Sevilla, 41092, ES

Mesostructured materials characterized by an open void network with narrow pore size distribution can be employed as matrices in which to synthesize perovskite nanocrystals of controlled size displaying quantum confinement effects. In this talk, the different approaches that can be taken within this methodology to obtain nanostructured perovskite films of high optical quality will be described and the properties of the resulting materials analyzed.[1,2] Electronic band gap tuning arising from quantum size effects are put into practice to controllably modify photoluminescence, electroluminescence and light harvesting properties of these nanostructures. Also, the interaction of the nanocrystals with the different types of matrices employed to host them will be studied, as well as their stability versus different environments[3] and their thermal stability. Actual integration of these films within optoelectronic devices in different configurations will be proposed and their performance and prospective applications discussed. Finally, the possibility to integrate these nanostructured films in different photonic architectures aiming at enhancing the performance of the devices will also be addressed.

10:15 - 10:30
Palazon, Francisco
Universidad de Valencia - ICMol (Institute of Molecular Science)
Perovskites and Beyond: Dry Mechanochemical Synthesis of Multinary Metal Halides
Francisco Palazon
Universidad de Valencia - ICMol (Institute of Molecular Science), ES

Last update: 01/11/2018

Born on January 7, 1988.

After completing 3-month and 5-month research internships on nanomaterials at Tohoku University (Japan; 2010) and Université de Sherbrooke (Canada; 2011) I obtained my Master of Science in Nanoscale Engineering from Ecole Centrale de Lyon (France; 2011).

I then did my PhD on “Surface functionalization of heterogeneous gold / silica substrates for the selective anchoring of biomolecules and colloids onto LSPR biosensors” under the supervision of Jean-Pierre Cloarec and Yann Chevolot at the Institut des Nanotechnologies de Lyon (2014).

From 2015 until December 2017 I was a post-doctoral researcher in the group of Liberato Manna at the Istituto Italiano di Tecnologia of Genova (Italy) working on the ERC project TRANS-NANO.

In 2017 I was awarded a Marie Curie fellowship to develop my project PerovSAMs in the group of Henk J. Bolink at the Universidad de Valencia, where I have been working since the 1st of January 2018.

Throughout this highly international career I have made significant contributions in the fields of materials’ chemistry, colloidal inorganic nanocrystals, surface analysis and halide perovskites’ optoelectronic devices among others.

I have co-authored 31 articles in international peer-reviewed journals and 1 book chapter. Most of my publications are in the most significant and highest impact factor journals of my field of research such as Nature Energy, Nature Communications and Journal of the American Chemical Society (JACS). My work has been highlighted on the cover of JACS and Chemistry of Materials. My publications cumulate a rapidly increasing number of citations (> 500 in total, out of which > 250 in 2018; source: Google Scholar). Furthermore, it is worth noting that most of these publications are without the contribution of my PhD supervisors and that I am first author and/or corresponding author in more than half of them.

Aside from research I have also maintained a teaching activity throughout my career with over 200 hours of lectures and practical courses in chemistry at undergraduate level (Ecole Centrale de Lyon; 2011-2014) as well as specific courses in surface analysis techniques for PhD students (Istituto Italiano di Tecnologia; 2015-2017). Eventually, I have supervised a Master of Science thesis and I currently supervise a PhD thesis.

Francisco Palazon a, Yousra El Ajjouri a, Michele Sessolo a, Henk J. Bolink a
a, Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, Carrer del Catedrátic José Beltrán Martinez, 2, Paterna, ES

Despite the outstanding optoelectronic properties of lead halide perovskites and the impressive performances achieved in perovskite-based devices, several concerns still hinder the widespread application of these materials. Two of the main bottlenecks today are: (i) the toxicity of Pb2+ cations, and (ii) the instability of hybrid organic-inorganic perovskites coupled with the difficulty in synthesizing fully-inorganic ones due to poor solubility of cesium halide salts in common solvents.

Here, we have used a fully-dry mechanical approach via ball-milling of different precursors to synthesize a wide range of phase-pure halide perovskites and related compounds with suitable optoelectronic properties for different applications from photovoltaics to light-emission. In particular, we have synthesized fully-inorganic CsPbX3 (X = I, Br, and Cl) compounds and investigated the structural, chemical, and optical effects of adding potassium halides (KX). We have also synthesized lead-free hybrid and inorganic perovskites based on Sn2+ as well as other related compounds such as A2Sn(IV)X6 “vacancy-ordered perovskites” and A3Bi2X9 (A = Cs, formamidinium, and methylammonium).

Eventually, we have demonstrated that the so-formed high quality dry powders can be used to make thin films via single-source vacuum deposition, thus enabling their use in different devices such as solar cells or light-emitting diodes.

10:30 - 11:00
Coffee Break
Session 1.2
Chair: Michele Sessolo
11:00 - 11:30
Lee, Tae-Woo
Seoul National University
Overcoming Fundamental Limitations for High-Efficiency Polycrystalline Perovskite Light-Emitting Diodes
Tae-Woo Lee
Seoul National University, KR

Tae-Woo Lee is an associate professor in Materials Science and Engineering at the Seoul National University, Korea. He received his Ph.D. in Chemical Engineering from the KAIST, Korea in 2002. He joined Bell Laboratories, USA as a postdoctoral researcher and worked at Samsung Advanced Institute of Technology as (2003-2008). He was an associate professor in Materials Science and Engineering at the Pohang University of Science and Technology (POSTECH), Korea until August 2016. His research focuses on printed flexible electronics based on organic, carbon, and organic-inorganic hybrid perovskite materials for displays, solar cells, and bio-inspired neuromorphic electronics.

Tae-Woo Lee a, b, c, Min-Ho Park a, b, Su-Hun Jeong a, b, Himchan Cho a, b
a, Department of Materials Science and Engineering, Seoul National University, Daehak-dong, Gwanak-gu, seoul, 151-744, KR
b, Research Institute of Advanced Materials, Seoul National University
c, BK21 PLUS SNU Materials Division for Educating Creative Global Leaders, Seoul National University

Metal halide perovskites (MHPs) are promising emitting materials for next-generation light-emitting diodes (LEDs) because MHPs have the advantages of easy solution processing, high color purity with a narrow full width at half maximum, easy synthesis and color tunability, and inexpensive material cost. Compared to the low dimensional 0D nanoparticles or 2D Ruddlesden-Popper MHPs, polycrystalline MHPs have fundamental electroluminescent (EL) limitations in terms of low exciton binding energy, long exciton diffusion length, and severe exciton quenching routes at the interface between conducting oxide anode and MHP emitting layer and in the MHP bulk. Here, we present the efficient strategies of the fine stoichiometry method, a self-organized conducting polymeric anode, nanograin engineering, and core-shell-mimicked polycrystal to achieve highly efficient polycrystalline MHP LEDs (PeLEDs). First, we suggest the highly efficient polycrystalline MAPbBr3 PeLEDs by controlling the precursor stoichiometry, improving surface morphology, and decreasing the grain size of the MAPbBr3 film. As a result, the current efficiency was improved from 0.002 cd/A to 42.9 cd/A. By unraveling the additive-based nanocrystal pinning (A-NCP) method, the limitations of EL efficiency in MHP films and PeLEDs were investigated so as to achieve an external quantum efficiency of 8.79% ph el-1. By adopting these strategies to the flexible graphene, we developed graphene-based MAPbBr3 PeLEDs that is beneficial to the out-coupling effect and exciton quenching due to In and Sn ions from ITO electrode. Then, we investigated a molecularly-decoupled ideal conducting polymeric anode for high-efficiency PeLEDs. Conducting polymers have a trade-off between a conductivity and a work function; i.e., the work function of conducting polymers decreases when the conductivity increases. Therefore, we introduce an effective molecular scale control strategy to decouple the work function with conductivity in conducting polymer anodes while maintaining the blocking capability of exciton quenching. Thereby, the high device efficiencies of 52.86 cd A-1 and 10.93% ph el-1 were achieved in MAPbBr3 PeLEDs. In addition, we developed kinetically-controlled core-shell-mimicked nanograins by incorporating a molecular semiconducting additive to shield the nanograins for suppressing defects at grain boundary region. The organic-shielded polycrystalline nanograins achieved improved photophysical and electroluminescence properties, and reduced free carrier density; and thus external quantum efficiency of 11.7% ph el-1 was achieved. Our various strategies for high-efficiency polycrystalline PeLEDs will provide broad interests to the research fields of perovskite electronics.

11:30 - 11:45
Mora-Seró, Iván
Institute of Advanced Materials (INAM), Universitat Jaume I
Different Strategies for Engineering of Halide Perovskite Interfaces
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.

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

Halide perovskite are receiving a huge attention in the recent few years. Undoubtedly this attention is mainly due to the outstanding power conversion efficiencies, surpassing 23%, reported for photovoltaic devices, fabricated with polycrystalline films from low cost techniques. This high performance is due to the high potentiality of the halide perovskite material but in order to take full advantage of it proper selective contacts have to be developed. The possibility of low temperature and solution process make that this technology can be easily integrated with very different kinds of materials and the interface properties can be tailored with a broad range of possibilities, including organic and inorganic materials and nanoparticles. In this talk we show how systems with very different nature can be used to engineering the perovskite interface in perovskite optoelectronic devices. The different systems have been systematically characterized in order to determine in which way interface modifications affect their ultimate performance.

11:45 - 12:15
Manna, Liberato
Istituto Italiano di Tecnologia
The Surface Chemistry of Colloidal Lead Halide Perovskites Nanocrystals
Liberato Manna
Istituto Italiano di Tecnologia, IT

Bio Professional Preparation M.S. in Chemistry, with Honours, University of Bari, Italy, 1996 Ph.D. in Chemistry, University of Bari, Italy, 2001 Research interests Prof. L. Manna is an expert of synthesis and assembly of colloidal nanocrystals. His research interests span the advanced synthesis, structural characterization and assembly of inorganic nanostructures for applications in energy-related areas, in photonics, electronics and biology.

Liberato Manna a
a, Department of Nanochemistry, Istituto Italiano di Tecnologia,Via Morego 30, 16163 Genova (Italy)

Following a surge of interest in lead halide perovskites, research on colloidal nanocrystals of these materials has gathered momentum in the last years. In such a narrow time span, several properties/features of halide perovskite nanocrystals have been investigated, among them electroluminescence, lasing, anion-exchange, as well as control of size and shape such that nanocrystals in the quantum confinement regime can now be easily fabricated, with narrow size distributions. One aspect that remains relatively less explored is the surface chemistry of these nanocrystals. Ligand binding in this case is very dynamic and can be strongly influenced by the external environment. The present talk will highlight the research activities of our group on understanding surface ligand binding and how this influences the synthesis, stability, optical properties, and post-synthesis transformations of colloidal lead halide perovskite nanocrystals. The various techniques that are used to investigate the surface of nanocrystals will also be critically discussed.

12:15 - 12:45
P. Boix, Pablo
Universitat de València
Interfacial Engineering for Single and Multijunction Vacuum-deposited Perovskite Solar Cells
Pablo P. Boix
Universitat de València, ES

Pablo P. Boix received his PhD. in Nanoscience and Nanotechnology from the Universitat Jaume I (2012, Castelló, Spain), with the focus on unveiling the physical processes governing optoelectronic devices such as dye sensitized, quantum dots and organic solar cells; as well as solar fuel systems. In 2012, he joined the Energy Research Institute (at Nanyang Technological University, Singapore), where he led a research line on hybrid lead halide perovskites for photovoltaic and light emission applications. As industrial R&D experience, in 2016, he worked on perovskite solar cells development (Dyesol Ltd., Lausanne, Switzerland). After that, Pablo joined ICMol (Universitat de València) as a Ramon y Cajal fellow. His research has contributed to the implementation of new materials and device concepts. As a result, his scientific production includes more than 70 articles in peer-reviewed scientific journals, with h-index: 39 (Web of Science) and 2 patents among others.

Pablo P. Boix a, Daniel Pérez-del-Rey a, Ana M. Gil-Muñoz a, Jorge Ávila a, Benedikt Dänekamp a, Michele Sessolo a, Henk J. Bolink a
a, Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, Carrer del Catedrátic José Beltrán Martinez, 2, Paterna, ES

Vacuum-deposition is one of the most technologically relevant techniques for perovskite solar cells fabrication. The intrinsically additive nature of vapor-based methods allows the design of multiple device architectures, circumventing solvent compatibility considerations. This can be a tool to maximize the photovoltaic conversion efficiency, but it is also a key factor to enable the fabrication of tailored systems for the characterization of the solar cell working mechanisms.

This work presents the progress on vapor phase deposited perovskites for single and multijunction devices. Multiple source co-deposition is employed for the fabrication of multi-cations/anions perovskite compounds, including low bandgap Pb-Sn and wider bandgap versions. We carry out a detailed study of the device interfaces, with the focus on the influence of thin organic charge extraction layers, strong dopants, ionic compounds, and conjugated polymers. With this approach, we can identify the main factors limiting the device performance, which is crucial to develop the full potential of the technology.

12:45 - 13:00
Herbol, Henry
Johns Hopkins University
Taming the Large Combinatorial Species Space for Hybrid Organic-Inorganic Perovskites via Bayesian Optimization
Henry Herbol
Johns Hopkins University
Henry Herbol a, Matthias Poloczek b, Paulette Clancy a
a, Johns Hopkins University
b, The University of Arizona., The University of Arizona. Tucson, AZ 85721.

Hybrid Organic-Inorganic Perovskites (HOIPs) have been widely researched over the last
decade, with great success in increasing their solar cell efficiency. HOIPs offer a viable
alternative to silicon solar cells, primarily in their promise for large-scale fabrication via solution
processing. Unfortunately, too much remains a mystery regarding a fundamental
understanding of the self-assembly process and precisely which solution processing variables
would be ideal (reagents, solvents, and processing conditions). This makes it a challenge to
create a member of the HOIP class with pre-specified characteristics beyond simply maximizing
device efficiency. There exists an overwhelming combinatorial problem due to the variety of
possible species: Many choices of A and B site cations (including blends of each), the choice of
halide (again, potentially a blend), choice of solvent blend, and aspects of their processing
(timing of adding anti-solvents, etc.). Exploring all possible candidates would be insurmountable
using a standard Edisonian approach. To redress this situation, we have developed a model
tailored to be used within a Bayesian optimization Gaussian Process Regression (GPR) scheme.[1]
Bayesian optimization is, arguably, the best method of maximizing an expensive objective, like
ours, and is ideal for this scenario. We tested this approach by maximizing the solvation of
HOIP salts (the smallest APbX3 molecule) using a simple computational ersatz for the enthalpy
of solvation, namely the intermolecular binding energy between the salt and solvent obtained
from DFT calculations, which served as our objective function. We hypothesized a connection
between good solvation and slow crystallization kinetics, and hence high quality thin films. We
studied two test cases for which we were able to compute the DFT intermolecular binding
energy of all possible candidates. The first was the best species composition for a pure halide in
a pure solvent (72 possible combinations). The second was for a mixed halide in a pure solvent
(240 possible combinations). We found we were able to achieve global maximization in under
half the number of iterations needed for the next best model (a Bayesian optimization
approach without using our model), and significantly better than all other common models.
We were able to identify the experimentally preferred “gold standard” compositions for pure
halides and mixed halide systems in a variety of pure solvents. Further, we were also able to
identify unexpected highly ranked predictions of high performers that deserve experimental

13:00 - 15:00
session 1.3
Chair: Natalie Banerji
15:00 - 15:30
Hadziioannou, Georges
University of Bordeaux
High Performance Polymer and Polymer/Inorganic Thermoelectric Materials
Georges Hadziioannou
University of Bordeaux, FR
Georges Hadziioannou a
a, Laboratoire de Chimie des Polymères Organiques, CNRS - ENSCPB - Université de Bordeaux

Conducting polymers have gained the rising attention of the scientific community, due to their thermoelectric efficiencies that enable the design of room temperature flexible heat harvesters, that can potentially cover the energy demands of the nomadic modern society. Their thermoelectric efficiency is usually optimized by tuning their oxidation levels, considering though, that the Seebeck coefficient (S) is decreasing with the electrical conductivity (σ), as both are antagonistically related to the carrier concentration. In this work we present a concurrent increase of S and σ and we experimentally derive the dependence of Seebeck coefficient on charge carrier mobility, for the first time in organic electronics. Through detailed control of the polymer synthesis, we enabled the formation of a more dense percolation path that facilitated the charge transport and the thermodiffusion of the charge carriers inside the conducting polymer, while the material shifted from a fermi glass to a semimetal, as its crystallinity increased. With our work not only we provide a solid understanding on the origin of the thermoelectric properties of conducting polymers, but we also highlight the importance of enhanced charge carrier mobility for the design of efficient thermoelectric polymers.

15:30 - 15:45
Strassel, Karen
EMPA - Swiss Federal Laboratories for Materials Science and Technology
All-Solution-Processed Organic Upconversion Device Comprising a Light-Emitting Electrochemical Cell
Karen Strassel
EMPA - Swiss Federal Laboratories for Materials Science and Technology, CH
Karen Strassel a, b, Santhanu Panikar Ramanandan a, b, René Schneider a, Frank Nüesch a, b, Roland Hany a
a, Empa – Swiss Federal Laboratories for Materials Science and Technology, Überlandstr. 129, CH-8600 Dübendorf, Switzerland
b, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland

Organic near-infrared (NIR) to visible upconversion devices (OUCs) are receiving interest due to manifold applications in remote sensing, night vision, NIR-imaging and biomedicine. In an OUC, an organic photodetector (OPD) is series connected with an organic light emitting component. When NIR light is absorbed by the OPD, electron-hole pairs are formed. Under an appropriate bias and for conditions of energetic interface matching, charges are easily driven in the light-emitting component where they recombine leading to visible light emission. The outcome is a NIR-to-visible upconverted image that can be captured using a conventional camera. OUCs benefit from the numerous advantages of organic electronics in general and offer the potential to convert a NIR scene into a visible image using large area devices that can be realized at low cost by high-throughput coating and printing techniques on flexible substrates. However, no all-solution processed OUC has been demonstrated so far. Here we report on the fabrication and optimization of all-solution processed OUCs based on a NIR squaraine dye OPD [1] and an emitting phenyl-substituted poly(para-phenylenevinylene) copolymer termed Super Yellow (SY). The key for multilayer solution processing is to have a layer structure which can withstand solvents used in subsequent processing. To cope with layer dissolution, poor wettability and imperfect film morphology, several approaches such as surface treatment, orthogonal solvents and cross-linkable layers were successfully used. In a first step, we fabricated OUCs with a SY/Ca/Al OLED and found that these devices are surprisingly long-term stable both during storage and in the presence of NIR light. The device converts NIR light at 980 nm efficiently to visible light at 590 nm with a high NIR light on/off ratio (800 at 4.5 V). To circumvent the vacuum thermal evaporation step of Ca, we then added a salt (Li+CF3SO3-) to the SY layer and thereby transformed the OLED into an organic light-emitting electrochemical cell (OLEC). OUCs comprising an OLEC were fabricated with top electrodes composed of Al (evaporated) or Ag (screen printed). Due to the presence of mobile ions in OLECs, such OUCs are temporal dynamic devices. Device operation involves the formation of electric double layers at the SY interfaces that facilitate the injection of electrical charges, the formation of n- and p-doped regions and an intrinsic region in between, where electron-hole recombination and light emission takes place [2]. We characterized the dynamic behavior of such all-solution processed OUCs in detail and found that an appropriate pre-conditioning voltage step results in a low turn-on voltage (~2.7 V) and a NIR-to-visible photon-to-photon conversion efficiency on a par with the SY/Ca/Al OLED. OPD-OLEC upconverters can pave the way to simplified manufacturing of low-cost and large-area NIR imagers entirely via solution-based techniques.

15:45 - 16:00
Grazulevicius, Juozas Vidas
Exploitation of interface exciplexes towards highly efficient organic light-emitting devices
Juozas Vidas Grazulevicius
Juozas Vidas Grazulevicius a, Galyna Sych a, Oleksandr Bezvykonnyi a, Dmytro Volyniuk a, Gintare Grybauskaite-Kaminskiene a, Khrystyna Ivaniuk b, Pavlo Stakhyra b
a, Kaunas University of Technology, 19, Radvilėnų pl. , Kaunas, 50254
b, Lviv Polytechnic National University, 12, S. Bandery str., Lviv, 79013

Organic emitters exhibiting thermally activated delayed fluorescence (TADF) are rare-earth-metal-free dyes which can theoretically realize 100% internal quantum efficiency (IQE) of organic light emitting diodes (OLEDs). They were demonstrated to be promising candidates for highly efficient OLEDs [1]. TADF emitter-based light-emitting layers characterized by both high photoluminescence quantum yields and small singlet-triplet energy splitting (ΔEST) have to be developed for fabrication of efficient OLEDs. Small ΔEST (typically less than 0.1 eV) can be easily obtained in exciplex-based systems. Since electron and hole are positioned on two different molecules, exciplex-based emitters are characterized by small exchange energy and efficient TADF [1]. If exciplexes are formed between layers of donating and accepting materials in OLED structures, energy barrier free interface for charges is obtained. This results in low operating voltages of OLEDs and enhanced power efficiencies (PE). Aiming to obtain both high IEQ and PE of OLEDs, exciplex-based OLED approaches demonstrated promising results [1].

Recently developed exciplex-forming donor-acceptor solid mixtures will be presented as either emitters or hosts with TADF properties for highly efficient OLEDs including interface exciplex-based OLEDs. For instance, exciplex-forming system consisting of 3,6-di(9-carbazolyl)-9-(2-ethylhexyl)carbazole as donor and 2,4,6-tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine as acceptor allowed to achieve very high value of of maximum external quantum efficiency (18%) for OLEDs based on interface exciplex emitter [2]. In addition, new approach for the development of the color-tunable OLEDs with the minimal number of the functional layers will be presented [3]. Guest-host free OLEDs combining emission from both excitons and exciplexes based on aggregation-induced emission enhancement of carbazole and tetraphenylethylene derivatives will be reported [4]. Extremely efficient warm-white OLEDs exploiting interface exciplex emission with harmless for the human eyes electroluminescence spectra will be presented [5]. Utilization of interface exciplex-host will be demonstrated for optimization and enhancement of performance of non-doped OLEDs based on new emitters showing aggregation induced emission enhancement [6].

16:00 - 16:30
Snaith, Henry
University of Oxford
Perovskite Solar Cells: Improving Device Efficiency and Stability, and Understanding Optoelectronic Processes
Henry Snaith
University of Oxford, GB

Henry Snaith undertook his PhD at the University of Cambridge, working on organic photovoltaics, then spent two years at the EPFL as a post-doc working on dye-sensitized solar cells. Since 2007 he has held a professorship at the University of Oxford Clarendon Laboratory where his group researches organic, hybrid and perovskite optoelectronic devices. Professor Snaith was elected as a Fellow of the Royal Society in 2015, he is a 2017 Clarivate Citation Laureate, and among his awards are the 2017 Royal Society James Joule Medal and Prize. In 2010 he founded Oxford Photovoltaics Ltd. which is commercializing the perovskite solar technology transferred from his laboratory.

Henry Snaith a
a, University of Oxford, GB

Perovskite solar cells continue to gain momentum in research and gain in efficiency, and multi-junction perovskite solar cells offer a roadmap to performance levels well beyond that ever possible with single junction silicon or other thin-film technologies. However, operational stability is an area which is understood to be important by the community, but consistently takes a back seat in contemporary perovskite research.    
I will present different approaches we have adopted to improving the efficiency, and fundamental stability of the perovskite absorber materials and devices, and highlight degradations which can occur in the bulk of the perovskite absorber materials and induced by the charge extraction heterojunction. I will give further insight into what factors influence stability, and how to mitigate degradation.  
Beyond stability, I will highlight how moving from a single absorber layer, to a multijunction cell should lead to much higher efficiencies, and I will show experimental realisation of progress along such a road map.  
Beyond laboratory based research, I will highlight our progress towards manufacturing scaleup through the technology company, Oxford PV Ltd., and the key challenges which need to be overcome to deliver an industrialised perovskite PV technology.

16:30 - 16:45
Bisquert, Juan
Institute of Advanced Materials (INAM), Universitat Jaume I
Interfacial phenomena governing kinetics of perovskite solar cells
Juan Bisquert
Institute of Advanced Materials (INAM), Universitat Jaume I, ES

Juan Bisquert (pHD Universitat de València, 1991) is a Professor of applied physics at Universitat Jaume I de Castelló, Spain. He is the director of the Institute of Advanced Materials at UJI. He authored 360 peer reviewed papers, and a series of books including Nanostructured Energy Devices (1. Equilibrium Concepts and Kinetics, 2. Foundations of Carrier Transport) and 3. Physics of Solar Cells: Perovskites, Organics, and Photovoltaics Fundamentals (CRC Press).  His h-index 82, and is currently a Senior Editor of the Journal of Physical Chemistry Letters. He conducts experimental and theoretical research on materials and devices for production and storage of clean energies. His main topics of interest are materials and processes in perovskite solar cells and solar fuel production. He has developed the application of measurement techniques and physical modeling of nanostructured energy devices, that relate the device operation with the elementary steps that take place at the nanoscale dimension: charge transfer, carrier transport, chemical reaction, etc., especially in the field of impedance spectroscopy, as well as general device models. He has been distinguished in the 2014-2017 list of ISI Highly Cited Researchers.


Juan Bisquert a
a, Institute of Advanced Materials (INAM), Universitat Jaume I, 12006 Castellón de la Plana, Castellón, España, Castellón de la Plana, ES

We describe the results of analysis of kinetic phenomena using frequency modulated techniques. First with impedance spectroscopy we provide an interpretation of capacitances as a function of frequency both in dark and under light, and we discuss the meaning of resistances and how they are primarily related to the operation of contacts in many cases.1 The capacitance reveals a very large charge accumulation at the electron contact, which has a great impact in the cell measurements, both in photovoltage decays, recombination, and hysteresis. We also shows the identification of the impedance of ionic diffusion by measuring single crystal samples.2 Working in samples with lateral contacts, we can identify the effect of ionic drift on changes of photoluminescence, by the creation of recombination centers in deffects of the structure.3 We also address new methods of characterization of the optical response by means of light modulated spectroscopy. The IMPS is able to provide important influence on the measured photocurrent. We describe important insights to the measurement of EQE in frequency modulated conditions, which shows that the quantum efficiency can be variable at very low frequencies.4

16:45 - 17:00
de Miguel, Gustavo
Large guanidinium cation mixed with methylammonium in lead iodide perovskites for 19% efficient solar cells
Gustavo de Miguel
Gustavo de Miguel a
a, Departamento de Química Física y Termodinámica Aplicada, Instituto Universitario de Investigación en Química Fina y Nanoquímica IUQFN, Universidad de Córdoba, Campus de Rabanales, Edificio Marie Curie, Córdoba, Spain

Organic–inorganic lead halide perovskites have shown photovoltaic performances above 20% in a range of solar cell architectures while offering simple and low-cost processability. Despite the multiple ionic compositions that have been reported so far, the presence of organic constituents is an essential element in all of the high-efficiency formulations, with the methylammonium and formamidinium cations being the sole efficient options available to date. We present a perovskite composition based on a combination of guanidinium/methylammonium cations that exhibits superior photovoltaic performance and material stability compared with MAPbI3. We demonstrate that the incorporation of large guanidinium (Gua) cations unexpectedly forms a highly stable 3D crystalline structure, plausibly mediated by the increased number of H bonds within the inorganic framework. The prepared MA1–xGuaxPbI3 perovskite preserved the good optoelectronic properties associated with the organic lead halide materials, leading to a high PCE surpassing 20% for a Gua content of 14% and stabilized performance for 1,000 h under continuous light illumination, a fundamental step within the perovskite field.

17:00 - 17:15
Panzer, Fabian
Soft Matter Optoelectronics, University of Bayreuth, 95440, Bayreuth, Germany
A completely Solvent free Route for Hybrid Perovskite Film Processing Based on Pressure Treatment of Perovskite Powders – Decoupling Material Synthesis and Film Formation
Fabian Panzer
Soft Matter Optoelectronics, University of Bayreuth, 95440, Bayreuth, Germany
Nico Leupold a, Maximilian Schulz b, Konstantin Schötz b, Ralf Moos a, Fabian Panzer b
a, Department of Functional Materials, University of Bayreuth, Bayreuth 95447, Germany
b, Soft Matter Optoelectronics, University of Bayreuth, Bayreuth 95447, Germany

Even though hybrid perovskites have undergone a remarkable development within the last years, state of the art processing approaches such as solution processing or evaporation suffer from an intrinsically high complexity, as the actual perovskite crystallization and its film processing happen simultaneously and are inextricably interconnected.

Here we present an alternative, entirely dry processing approach, which decouples perovskite crystallization and film formation, by using readily prepared perovskite powders and produce films by appropriate mechanical pressure treatment. We show how a mechanochemical synthesis approach by ball milling allows to produce a wide range of phase pure and exceptionally stable hybrid perovskite powders with a high flexibility in processing and address the impact of milling parameters on the powder properties. Using these powders, we demonstrate how the used pressure and the powder microstructure, i.e. particle size and stoichiometry affect the mechanical stability, compactness and surface roughness of the pressed layers. We further address how specific temperature treatment during the pressing step can improve the properties of the pressed layer, and show their capability to be used in perovskite based optoelectronic devices.

17:15 - 17:30
Motti, Silvia
University of Oxford
Energy Cascades in Mixed-Phase Perovskite Thin Films: Charge-Carrier Dynamics and Mobilities
Silvia Motti
University of Oxford, GB
Silvia Motti a, Timothy Crothers a, Rong Yang b, Jianpu Wang b, Laura Herz a
a, Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, GB
b, Nanjing Tech Unversity, 5 Xinmofan Road, Nanjing, 210009, CN

Perovskite semiconductors have recently emerged as promising materials for optoelectronic applications, with photovoltaic efficiencies that have now reached over 23%. However, the poor stability of the material is still a major challenge for commercial application. One possible strategy for improving environmental stability is the incorporation of large organic hydrophobic cations in the perovskite structure, which results in a layered two-dimensional (2D) material where the organic molecules form a dielectric barrier between the semiconductor layers. 2D perovskites show enhanced stability in contrast to the conventional 3D compositions,[1] however the presence of dielectric confinement results in higher exciton binding energies, wider bandgaps and limited charge carrier diffusion lengths.[2]  Mixed phase compositions can be a viable approach for obtaining films that combine the enhanced environmental stability of 2D perovskite and good charge transport properties of the 3D semiconductor for device application. We have investigated the charge transport properties of mixed-phase 2D-3D perovskite thin films deposited from solution using time resolved Photoluminescence (PL) and Optical-Pump Terahertz-Probe (OPTP) spectroscopy. We demonstrate the preferential formation of 2D domains close to the substrate and predominance of 3D crystallites on the front surface, consequently creating an energy cascade with a preferential direction across the semiconductor film.[3,4] Evidence for the charge and energy transfer through the cascade could be observed in unusual OPTP transients. Based on the experimental observations we proposed a model that reproduces the recombination and transfer dynamics, combining the effects of charge diffusion and photon reabsorption. This allows us to identify the most relevant transfer mechanisms in play in such self-assembled energy cascades. Our findings show that the presence of 2D domains does not hinder the charge transport properties of the semiconductor film with respect to the pure 3D structures, demonstrating the suitability of the mixed phase 2D-3D perovskite films for optoelectronic applications.

17:30 - 19:00
Poster Session
Wed Mar 06 2019
08:55 - 09:00
Announcement of the Day
Session 2.1
Chair: Thuc-Quyen Nguyen
09:00 - 09:30
Marder, Seth
Georgia Institute of Technology
Interface Chemistry for Organic Electronics and Opto-electronics
Seth Marder
Georgia Institute of Technology, US

Seth R. Marder obtained his Ph.D. from the University of Wisconsin-Madison in 1985.  He completed his postdoctoral research at the University of Oxford and at the Jet Propulsion Laboratory California Institute of Technology. He joined the Georgia Institute of Technology in 2003 where he is currently a Regents’ Professor of Chemistry and Materials Science and Engineering (courtesy) and the Georgia Power Chair in Energy Efficiency. His research interests are in the development of materials for nonlinear optics, applications of organic dyes for photonic, display, electronic and medical applications, and organometallic chemistry.

Seth Marder a
a, School of Chemistry and Biochemistry, School of Materials Science and Engineering, and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, GA 30332-0400 USA

Organic semiconductors and hybrid/organic materials have attracted interest for electronic applications due to their potential for use in low-cost, large-area, flexible electronic devices. Here we will report on recent developments pertaining to surface modifiers and both n- and p-dopants that could impact the charge injection/collection processes in organic light emitting diodes, organic field effect transistors, organic photovoltaics and hybrid organic/inorganic perovskite devices. We will also discuss the development of organic and metallo-organic-based dimers as n-dopants and very briefly described metal dithiolene complexes as p-dopants for organic semiconductors including their impact on device performance. The application of n-doping for the development of electron injection layers for organic light emitting diodes (OLEDs) will be highlighted, including their use for doping of electron transport materials which result in high conductivities and in some cases good thermoelectric performance.  In the case of OLEDs, it will be shown that photoactivation can lead to stable doping of materials (i.e. the doping-induced conductivity remains relatively constant over hundreds of hours) beyond the expected thermodynamic limit, which would be predicted based on an assessment of the effective reduction potential of the n-dopant and the reduction potential of the electron transport material.

Selected References:

“n-Doping of Organic Electronic Materials using Air-Stable Organometallics,” Adv. Mater. 24 (5), 699-703 (February 2012, DOI: 10.1002/adma.201103238)

“Electrode Work Function Engineering with Phosphonic Acid Monolayers and Molecular Acceptors: Charge Redistribution Mechanisms.” Adv. Funct. Mater. 1704438/1-12 (2018, DOI:10.1002/adfm.201704438)

“Solution doping of organic semiconductors using air-stable n-dopants.” Appl. Phys. Lett. 100, 083305 (February 2012)

“A universal method to produce low work function electrodes for organic electronics,” Science 336 (6079), 327-332 (April 2012, DOI: 10.1126/science.1218829)

“Surface modified fullerene electron transport layers for stable and reproducible flexible perovskite solar cells.” Nano Energy 49, 324-332 (2018, DOI:10.1016/j.nanoen.2018.04.068)

“Ultralow doping in organic semiconductors: Evidence of trap filling.” Phys. Rev. Lett. 109 (17), 176601/1-5 (November 2012, DOI: 10.1103/PhysRevLett.109.176601)

“Reduction of contact resistance by selective contact doping in fullerene n-channel organic field-effect transistors.” Appl. Phys. Lett. 102, 153303-153307 (April 2013, DOI: 10.1063/1.4802237)

“Modification of the fluorinated tin oxide/electron-transporting material interface by a strong reductant and its effect on perovskite solar cell efficiency.” Mol. Syst. Des. Eng. Advance Article (2018, DOI:10.1039/C8ME00031J)

“Production of Heavily n- and p-Doped CVD Graphene with Solution-Processed Redox-Active Metal-Organic Species," Materials Horizons Advance Article (September 2013, DOI: 10.1039/C3MH00035D

“Controllable, Wide-Ranging n-Doping and p-Doping of Monolayer Group 6 Transition-Metal Disulfides and Diselenides.” Adv. Mater. 30, 1802991 (2018, DOI: 10.1002/adma.201802991)



09:30 - 09:45
khodabakhshi, Elham
Max Planck Institute for Polymer Research
Suppression of electron trapping by quantum dot emitters using a grafted polystyrene shell
Elham khodabakhshi
Max Planck Institute for Polymer Research
Elham Khodabakhshi a, Benjamin Klöckner b, Jasper Michels a, Rudolf Zentel b, Paul Blom a
a, Max Planck Institute for Polymer Research, Ackermannweg10, 55128 Mainz, Germany
b, Institute for Organic Chemistry, Johannes Gutenberg University, Duesbergweg 10-14, 55128 Mainz, Germany

  Quantum dot (QD) based light-emitting diodes (QLEDs) are competitive alternatives to purely organic light-emitting diodes (OLEDs) in terms of color purity, luminescence intensities, and external quantum efficiencies (EQEs). Hybrid QD/organic polymer light-emitting diodes combine the advantageous emitting properties of the QDs with the flexibility in device construction of polymeric materials. In QD/polymer hybrid LEDs, adding QD emitters in the polymer host usually leads to strong charge trapping or charge transfer from the polymer host to the QDs, which adversely affects device performance. In a host-guest system comprising a blue-emitting donor polymer and a red-emitting QD acceptor, the emission process should preferably occur via long-range Förster energy transfer (FRET), without charge trapping or charge transfer. Therefore, the design challenge for such a system is to optimize energy transfer, while at the same time separating donor and acceptor sufficiently far to avoid short-range processes such as charge transfer and trapping.1,2

  To address this challenge, we designed a novel QD/semiconducting polymer hybrid material in which the surface of the QDs is covered with an electrically insulating shell with an optimized thickness. We separate donor and acceptor far enough to prevent charge transfer and trapping, while still allowing FRET by i) shielding the emitting CdSe core of the QDs with a ZnS shell having a wider bandgap than the core and ii) grafting polystyrene (PS) chains onto the ZnS surface. The PS layer furthermore enhances miscibility with the polymeric host. We studied the performance of QLEDs and single charge carrier devices based on the red-emitting CdSe/ZnS/PS core shell QDs (acceptor) blended with the blue emitter poly(dioctylfluorene) (PFO) as the host (donor). For optimal QD size, PS molecular weight, grafting density and particle loading, FRET from PFO to the QDs is the dominant process, with charge trapping being only marginal compared to active layers containing non-PS-grafted QDs.  



09:45 - 10:00
Gierschner, Johannes
IMDEA Nanoscience
Interfacing in Highly Luminescent Organic Charge-Transfer Co-Crystals
Johannes Gierschner
IMDEA Nanoscience, ES
Sangyoon Oh b, Sang Kyu Park b, Larry Lüer a, Reinhold Wanemacher a, Roland Resel c, Soo Young Park c, Johannes Gierschner a
a, Madrid Institute for Advanced Studies, IMDEA Nanoscience, Madrid, Spain
b, Center for Supramolecular Optoelectronic Materials, Department of Materials Science and Engineering, Seoul National University, Korea
c, Institute of Solid State Physics, Graz University of Technology, Austria

In the last few years co-crystals of conjugated organic compounds have attracted much attention as next-generation composite materials for organic optoelectronics. The vivid interest is driven by targeted materials design concepts inter alia via the isometric approach,1 creating segregated or mixed-stacked co-crystal systems. Reversible segregated-mixed stack conversion can be induced by external multi-stimuli, generating large color changes by switching between localized exciton vs. charge-transfer (CT) emission.2 Combined pump-probe, low-temperature PL and atomistic quantum-chemical studies reveal the spectral signatures and kinetics of exciton generation, transport and deactivation.3,5 Switching from 1D to 2D mixed-stacking motif gives rise to well-balanced ambipolar charge transport materials, being a prerequisite for optimized electrically driven light emission, and allowing for the first CT-crystal-based organic light emitting transistors (OLET).4 Systematic opening new pathways in the field. Targeted crystal design allows for systematic color variation and intermolecular TADF characteristics while keeping the structural characteristics.5

10:00 - 10:30
Miranda Perez, Laura
Oxford PV
Perovskite-Si Tandem - pathway to Commercialisation
Laura Miranda Perez
Oxford PV, GB

Dr Laura Miranda Perez is the Head of Materials Research and Characterisation at Oxford PV, a spin-out of Oxford University that is commercialising perovskites for photovoltaic applications. Laura has a strong background in materials synthesis and characterisation. Prior to joining Oxford PV she was a fellow at the University of Oxford, where her work focused on perovskites and carbon materials. Before this, Laura held a fellowship in perovskite thin film materials at the College du France in Paris. Laura undertook her PhD in Madrid, Spain and Sheffield, UK, in the screening of new families of hexagonal perovskite materials.




Laura Miranda Perez a
a, Oxford Photovoltaics, Oxford, OX5 1QU, United Kingdom

With the considerable progress in efficiency, stability and manufacturability, perovskite solar cells are now well along the path to reaching commercialisation. While single junction silicon photovoltaic technology has reached an impressive 26.7 percent power conversion efficiency, it will be forever limited to efficiencies below 30 percent. We will discuss how in a few short years, Oxford PV’s perovskite technology in tandem with silicon has achieved a certified 28 percent efficiency, and the clear roadmap to efficiencies extending well beyond 30 percent. Additionally, this talk will explain the importance of a fundamental understanding of the perovskite material properties and its relationship with the development of a stable technology; sharing long-term reliability test data based on the IEC61215 standards. We will also reflect on the challenges and progress that has been made to scale this perovskite-silicon tandem solar cell technology from the lab to commercial sized solar cells at pilot production and initial manufacturing levels.

10:30 - 11:00
Coffee Break
Session 2.1
Chair: Ellen Moons
11:00 - 11:30
Nguyen, Thuc-Quyen
University of California Santa Barbara
Doping of Conjugated Polymers by Lewis Acids
Thuc-Quyen Nguyen
University of California Santa Barbara, US

Thuc-Quyen Nguyen is a professor in the Center for Polymers and Organic Solids and the Chemistry & Biochemistry Department at University of California, Santa Barbara (UCSB). She received her Ph.D. degree in physical chemistry from the University of California, Los Angeles, in 2001 under the supervision of Professor Benjamin Schwartz. Her thesis focused on photophysics of conducting polymers. She was a research associate in the Department of Chemistry and the Nanocenter at Columbia University working with Professors Louis Brus and Colin Nuckolls on molecular self-assembly, nanoscale characterization and molecular electronics. She also spent time at IBM Research Center at T. J. Watson (Yorktown Heights, NY) working with Richard Martel and Phaedon Avouris. Her current research interests are structure-function-property relationships in organic semiconductors, electronic properties of conjugated polyelectrolytes, interfaces in optoelectronic devices, charge transport in organic semiconductors and biological systems, and device physics. Recognition for her research includes the 2005 Office of Naval Research Young Investigator Award, the 2006 NSF CAREER Award, the 2007 Harold Plous Award, the 2008 Camille Dreyfus Teacher Scholar Award, the 2009 Alfred Sloan Research Fellows, the 2010 National Science Foundation American Competitiveness and Innovation Fellows, the 2015 Alexander von Humboldt Senior Research Award, the 2016 Fellow of the Royal Society of Chemistry, and the 2015, 2016, and 2017 World’s Most InfluentialScientific Minds; Top 1% Highly Cited Researchers in Materials Science by Thomson Reuters and Clarivate Analytics. Her current research interests are electronic properties of conjugated polyelectrolytes, doping in organic semiconductors, charge transport in organic semiconductors and biofilms, bioelectronics, and device physics of organic solar cells, ratchets, transistors, and photodetectors.

Thuc-Quyen Nguyen a
a, Center for Polymers and Organic Solids and Department of Chemistry & Biochemistry, University of California, Santa Barbara, CA 93106, USA

The ability to precisely control the equilibrium carrier concentration in organic semiconducting devices is of great interest. The ability to solution process doped layers is of extreme importance for high throughput production of organic electronic devices via roll-to-roll or ink-jet printing. In this talk, I will discuss doping in conjugated polymers containing Lewis basic sites and the effects of doping on optical property and conductivity. The pyridine moiety on the polymer provides an accessible lone-pair of electrons that can associate with the Lewis acid. Under these circumstances, Lewis acid withdraws electron density from the pyridine moiety leading to a lower energy charge-transfer band. Addition of pyridine regenerates the spectra of pristine polymer due to the formation of the pyridine-Lewis acid adduct and liberation of the parent polymer, demonstrating that the binding is reversible. Addition of the Lewis acid effectively p-dopes the hole transport in the parent polymer, leading to increases in the free hole density and conductivity. This methodology is advantageous since the polymer, Lewis acid, and the adduct have excellent solubility in organic solvents, negating the need for co-solvents that uses in molecular dopant such as F4TCNQ.

11:30 - 11:45
Hayes, Sophia
Department of Chemistry, University of Cyprus, Nicosia, Cyprus
Evidence for Charged Species Formation in High Persistence Length Organic Semiconductors in Solution
Sophia Hayes
Department of Chemistry, University of Cyprus, Nicosia, Cyprus
Sophia Hayes a, Elham Rezasoltani b, Anthony Parker c, Igor Sazanovich c, Mike Towrie c, Alise Virbule b, Jenny Nelson b, Michelle Vezie b
a, Department of Chemistry, University to Cyprus
b, Department of Physics, Imperial College London, UK
c, Rutherford Appleton Laboratory, Harwell, Oxford

Electronic excitation plays a key role in the operation of organic-based semiconductor devices such as organic solar cells, photodetectors and light-emitting diodes. Thus, developing our understanding of the processes that dictate the fate of primary photoexcitations is essential in the design, optimization and longevity of such devices. In the field of organic solar cells, there has been an intense search for low energy band gap systems, based upon π-conjugated polymers, for more efficient collection of solar energy in the near IR. In our recent work,[1] three low energy bandgap polymers have been demonstrated to exemplify a significantly higher extinction coefficient compared to other conjugated polymer systems, either homopolymers or donor-acceptor polymers, to date, especially in higher molecular weights, due to their extended persistence length.

Using ultrafast Time-Resolved Infrared spectroscopy we have studied the excited state structural evolution in solution in these three polymers systems; two copolymers of diketopyrrolopyrrole and thiophene (DPP-3T) or thienothiophene (DPP-TT-T) and one a copolymer of indacenodithiophene with benzothiadiazole (IDTBT). In all three cases, vibrational features appear promptly after excitation. The vibrational features appear on a broad absorption background that decays, which is tentatively assigned to polaron absorption due to interchain interactions. For DPPTT-T, both the broad background and IR bands decay within 200 ps. However, for IDTBT we observe not only longer decay times but also significant differences in the kinetics between the broad background and IR bands, indicative of an initial intramolecular charge-transfer state formation which then evolves to the charge separated species that subsequently recombines. We will discuss the possible origin of these phenomena with the aid of calculations of vibrational spectra and models for excited state.

11:45 - 12:15
Banerji, Natalie
University of Bern
Ultrafast Properties of a Self-Doped Conjugated Polyelectrolyte
Natalie Banerji
University of Bern, CH
Demetra Tsokkou a, Lisa Peterhans a, David Xi Cao b, Cheng-Kang Mai b, Guillermo C. Bazan b, Thuc-Quyen Nguyen b, Natalie Banerji a
a, Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
b, Center for Polymers and Organic Solids, Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106, USA

The ultrafast optical processes in a self-doped conjugated polyelectrolyte, where any complications related to dopant diffusion, formation of partial charge transfer complexes or structural disruption by external dopant molecules are absent, are presented. Conjugated polyelectrolytes have conjugated backbones with ionic side chains. Their numerous applications include biosensing, cell imaging and interlayers in electronic devices. The ability to conduct both electronic and ionic charge, as well as their favorable doping, make conjugated polyelectrolytes particularly interesting. CPE-K is a narrow-bandgap conjugated polyelectrolyte, which becomes self-doped upon dialysis treatment. The doping is directly evident in the absorption spectrum, where the P2 polaron band appears around 1200 nm. By carefully determining the extinction coefficient of this band, we estimate the doping density in the polyelectrolyte doped at different levels. We carried out transient absorption (TA) spectroscopy in CPE-K solutions and thin films, with pumping in either the neutral S0-S1 or the polaronic P2 transition. We show that there is electronic coupling of polarons to nearby neutral sites, which share the same ground state for their optical transitions (both are depleted in the TA experiments, no matter which transition is excited). Similar, correlated and very short-lived dynamics are observed at both excitation wavelengths. This result contrasts with the conventional picture of localized intragap polaron states and warrants a revised model for the electronic structure and optical transitions in doped organic systems. We also show that inter-site Coulomb interactions are present (i.e. the positive polarons cause a Stark shift in the transitions of nearby neutral sites). The electronic coupling and electrostatic effects of the polarons occur independently on doping concentration and on whether the self-doped material forms a thin film or is in solution. Finally, we present the terahertz (THz) conductivity of those doped thin films, establishing the local carrier mobility.

12:15 - 12:30
Dyson, Matthew
Eindhoven University of Technology
Managing Local Order in Conjugated Polymer Blends via Polarity Contrast
Matthew Dyson
Eindhoven University of Technology, NL
Matthew Dyson a, b, Eirini Lariou c, Jaime Martin d, e, Ruipeng Li f, Harikrishna Erothu g, h, Guillaume Wantz i, Paul Topham h, Olivier Dautel j, Sophia Hayes c, Paul Stavrinou k, Natalie Stingelin b, l, m
a, Molecular Materials and Nanosystems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, Netherlands
b, Department of Chemistry and Centre for Plastic Electronics, Imperial College London, South Kensington Campus, London, GB
c, Department of Chemistry, University of Cyprus, P.O. Box 20537, 1678, Nicosia, Cyprus
d, POLYMAT, University of the Basque Country UPV/EHU, Avenida de Tolosa 72, 20018 Donostia-San Sebastián, Spain
e, Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain
f, National Synchrotron Light Source II, Brookhaven National Lab, Upton, New York, USA
g, Centre for Advanced Energy Studies (CAES), Koneru Lakshmaiah Education Foundation, Green Fields, Vaddeswaram, Guntur District, Andhra Pradesh-522 502, India
h, Aston Institute of Materials Research, Aston University, Birmingham, B4 7ET, UK
i, Université de Bordeaux, IMS, CNRS, UMR-5218, Bordeaux INP, ENSCBP, 33405 Talence, France
j, Institut Charles Gerhardt de Montpellier, Laboratoire AM2N, UMR-5253, Université de Montpellier, ENSCM, CNRS, 8 rue de l'École Normale, 34296 Montpellier cedex 5, France
k, Department of Engineering Science, University of Oxford, Parks Rd, OX1 3PJ, UK
l, School of Materials Science & Engineering and School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Ferst Drive, Atlanta, Georgia 30332, USA
m, Laboratoire de Chimie des Polymères Organiques − LCPO, UMR5629 Université de Bordeaux, Allée Geoffroy Saint Hilaire, Bâtiment B8 CS50023, 33615 Pessac Cedex, France

The optoelectronic landscape of conjugated polymers is highly dependent on their molecular arrangement and packing, with minute changes in local order, such as chain conformation and torsional backbone order/disorder, frequently having a substantial effect on macroscopic properties.[1-3] Here, we show that blending semiconducting polymers with insulating commodity plastics, an approach previously shown to benefit charge transport[4,5] and improve flexibility,[6] enables controlled manipulation of semiconductor backbone planarity. The key is to create a polarity difference between the semiconductor backbone and its side chains, while matching the polarity of the side chains and the additive. We demonstrate the applicability of this approach by judicious comparison of regioregular poly(3-hexylthiophene) (P3HT) with two of its more polar derivatives, namely the diblock copolymer poly(3-hexylthiophene)-block-poly(ethylene oxide) (P3HT-b-PEO) and the graft polymer poly[3-but(ethylene oxide)thiophene] (P3BEOT), as well as their blends with poly(ethylene oxide) (PEO). Proximity between polar side chains and a similarly polar additive reduces steric hindrance between individual chain segments by essentially ‘expelling’ the side chains away from the semiconducting backbones.  This process, shown to be facilitated via exposure to polar environments such as humid air/water vapor, facilitates backbone realignment towards specific chain arrangements, thereby enabling control of backbone planarity graft polymers with aqueous/ionic compatiblity that are usually torsionally disordered.[7]


12:30 - 13:00
Köhler, Anna
University of Bayreuth
Understanding and Controlling Aggregate Formation During Spin Coating
Anna Köhler
University of Bayreuth, DE

Professor Anna Köhler holds a chair of experimental physics at the University of Bayreuth. She received her PhD in 1996 from the University of Cambridge, UK, where she continued her research funded through Research Fellowships by Peterhouse and by the Royal Society. In 2003 she was appointed professor at the University of Potsdam, Germany, from where she moved in 2007 to the University of Bayreuth, Germany. Her research is concerned with photophysical processes in organic and hybrid semiconductors. She focusses in particular on the processes of energy and charge transfer in singlet and triplet excited states, the exciton dissociation mechanism and intermolecular/interchain interactions.

Anna Köhler a
a, Soft Matter Optoelectronics, University of Bayreuth, 95440, Bayreuth, Germany

Aggregates – that is short-ranged ordered moieties in the solid-state of π-conjugated polymers – play an important role in the photophysics and performance of various optoelectronic devices. It is often not clear what controls their formation during the spin-coating process of a film. Previously, we have shown that many polymers change from a disordered to a more ordered conformation when cooling a solution below a characteristic critical temperature. Here, I adress how we can use this knowledge to control the formation of aggregates during the deposition of films.

Using in situ time-resolved absorption spectroscopy on the prototypical semiconducting polymers P3HT, PFO, PCPDTBT, and PCE11 (PffBT4T-2OD), we show that spin-coating at a temperature below the critical temperature enhances the formation of aggregates with strong intra-chain coupling. An analysis of their time-resolved spectra indicates that the formation of nuclei in the initial stages of film formation for substrates held the critical temperature is responsible for this. We observe that the growth rate of the aggregates during film formation is thermally activated with an energy that exceeds the activation energy of the solvent viscosity . From this we conclude that the rate controlling step is the planarization of a chain that is associated with its attachment to a nucleation center.

Further, it is well known that the film formation process during spin-coating as well as the subsequent long-time film drying process differ significantly when DIO is added to a solution of P3HT. Here we show how the addition of DIO increases the time until the disorder-order transition sets in, yet it accelerates the actual transition, which impacts on the nature of the resulting aggregates. Moreover, aggregates form through an all-over solidification throughout the entire film rather than the spreading of a solidfication front in the absence of DIO in the solution.

13:00 - 15:00
Session 2.3
Chair: Fabian Panzer
15:00 - 15:30
Schulz, Philip
CNRS, Institut Photovoltaïque d’Île de France (IPVF)
Photoemission Spectroscopy for Halide Perovskites Semiconductors
Philip Schulz
CNRS, Institut Photovoltaïque d’Île de France (IPVF), FR

Philip Schulz holds a position as Research Director for Physical Chemistry and New Concepts for Photovoltaics at CNRS. In this capacity he leads the “Interfaces and Hybrid Materials for Photovoltaics” group at IPVF via the “Make Our Planet Great Again” program, which was initiated by the French President Emmanuel Macron. Before that, Philip Schulz has been a postdoctoral researcher at NREL from 2014 to 2017, and in the Department of Electrical Engineering of Princeton University from 2012 to 2014. He received his Ph.D. in physics from RWTH Aachen University in Germany in 2012.

Philip Schuz a
a, CNRS, Institut Photovoltaïque d’Île de France (IPVF), UMR 9006, 30 route départementale, Palaiseau, FR

For many semiconductor applications photoemission spectroscopy (PES) play the role of an invaluable tool to determine key electronic parameters for the description of the device functionality, such as band offsets and interface dipoles. With the rise of photovoltaic technologies based on halide perovskite (HaP) absorber layers, the use of direct and inverse PES methods has been pursued to monitor the formation of interfaces between halide perovskite films and adjacent functional layers, that are employed for charge transfer in perovskite-based optoelectronic devices.

We reported on the energy level alignment between HaP films and organic charge transport layers [1], oxide substrates [2], carbon nanotube thin-films [3] and high-work function MoO3 overlayers [4]. In this talk I will summarize these findings and describe the challenges to generalize these trends as the complex chemistry between HaP layer and adjacent semiconductor often lies at the root of the observed interfacial alignment processes and band bending.

Furthermore, I will give examples for typical pitfalls that occur, when characterizing HaP surfaces and interfaces with PES methods. Most importantly, beam damages effects have been identified as the perovskite layers can exhibit distinct signs of degradation under vacuum conditions and concomitant irradiation with high-energy photons [5]. While we generally intend to avoid these transient effects in our measurements, we can extract additional physical and chemical parameters from the evolution of energy level positions and stoichiometry during the PES measurements [6-8], with direct implications on the material stability. Finally, I will conclude my talk with a view on the perspectives of interfacial analysis for halide perovskites by PES techniques and an outlook on future experiments [9].

15:30 - 15:45
Caprioglio, Pietro
University of Potsdam, Soft Matter Physics
Interfacial Design through Poly-Ionic Liquid Surface Modification in Efficient pin Perovskite Solar cells
Pietro Caprioglio
University of Potsdam, Soft Matter Physics, DE
Pietro Caprioglio a, d, Saul Daniel Cruz Lemus b, Sabastian Caicedo-Davila c, Martin Stolterfoht a, Christian M. Wolff a, Daniel Abu-Ras c, Markus Antonietti b, Bernd Rech c, Steve Albrecht d, Dieter Neher a
a, University of Potsdam Institut für Physik und Astronomie Physik weicher Materie, Potsdam
b, Max Plank Institute of Colloids and Interfaces, Am Muehlenburg 1, Potsdam, 14424
c, Helmholtz-Zentrum für Materialien und Energie GmbH, Hahn-Meitner-Platz 1 14109 Berlin
d, Young Investigator Group Perovskite Tandem Solar Cells, Helmholtz-Zentrum Berlin, Berlin, DE

Metal halide perovskite solar cells are now effectively competing with their inorganic counterparts in terms of power conversion efficiencies. However, state of the art perovskite solar cells still suffer from limited fill factor (FF) and open circuit voltage (Voc), due to non-radiative recombination processes happening in the device. We found that selective charge transport layers (CTLs) are key components of diffusion controlled perovskite solar cells, however, the CTL/perovskite interfaces induce additional non-radiative recombination pathways which limit the Voc of the cell. In order to harvest the full thermodynamic potential of the perovskite absorber the interfaces of both the electron and hole transport layers (ETL/HTL) must be properly addressed and improved. Here, we show a significant improvement of the Voc and FF of pin-type perovskite solar cells by employing a novel surface treatment to a of triple cation perovskite Cs5(MA0.17FA0.83)95)95Pb(I0.83 Br0.17)3 using a polyionic liquid (PIL) material. The resulting solar cell devices show outstanding FF values of up to 83% and Voc of 1.17V, which lead an extraordinarily PCE of 21.5%. Through combined photoluminescence and electroluminescence studies we found that the PIL reduces the non-radiative recombination at perovskite surface by acting as a defect passivating agent of the bare perovskite surface and limiting the recombination of charges across the perovskite/C60 interface. Photoemission spectroscopy (XPS/UPS) and conductive atomic force microscopy (CAFM) show how the ionic nature of the PIL induces a specific charge redistribution at the perovskite surface, going along with improved extraction of the electrons at the perovskite/C60 interface. Ultimately, the hydrophobic nature of the PIL provides a shielding coverage of the perovsktie which reduces degradation due to moisture and air. The PIL modified devices show exceptionally long dark storage stability and enhanced maximum power point tracking (MPP) lifetimes. In conclusion, our work proposes a novel approach to efficiently suppress non-radiative recombination of charges, promote the charge extraction and improve the stability at the same time. Additionally, given the simplicity of this post treatment, our results can be representative of a more general methodology for device modification, and therefore potentially applicable to other compositions and cell architecture, opening doors for e new class of materials to be implemented in perovskite solar cells.

15:45 - 16:00
Martin, Jaime
POLYMAT - University of the Basque Country
Determining the Absolute Composition of Intermixed Domains in OPV cells by Fast Scanning Calorimetry
Jaime Martin
POLYMAT - University of the Basque Country
Jaime Martín a, Daniele Cangialosi b, Natalie Stingelin c
a, POLYMAT, University of the Basque Country UPV/EHU Avenida de Tolosa 72, 20018 Donostia-San Sebastián, Spain
b, Centro de Física de Materiales (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, 20018 San Sebastián, Spain
c, School of Materials Science and Engineering and School of Chemical & Biomolecular Engineering, Georgia Institute of Tech-nology, 311 Ferst Drive, Atlanta, Georgia, 30332, USA

Most efficient organic photovoltaic (OPV) cells comprise a polymeric donor and a small-molecule acceptor blended in a so-called bulk heterojunction (BHJ) thin film architecture. The BHJ morphology is complex; it is now, for instance, well accepted that most BHJ blends used in OPVs are at least to a certain extent finely intermixed, rarely featuring entirely phase-pure domains. This renders elucidating the nature of molecularly mixed phases, and how these relate to device characteristics, a major challenge in the field. Recently, Ade et al. [1] have introduced the so-called domain-composition-variation concept, which accounts for the relative purity of domains as compared to a reference sample and can be experimentally determined by means of soft X-ray scattering experiments. Despite the fact that it represents a great advance because it allows for a phenomenological correlation between the domain purity and device characteristics, the lack of quantitative information about the absolute domain composition in real devices is still hindering a more refined understanding of how mixed phases impact the device function. Here, we present a new methodology based on fast scanning calorimetry that allows to readily determine the absolute composition of intermixed domains in BHJs processed using the same parameters as those employed for device fabrication (e.g. spin-casting a sub-200-nm thin film on PEDOT:PSS). The method exploits the well-known fact that the devitrification temperature, i.e. the Tg, of a finely intermixed blend in the glassy state is coherently affected by the composition of the blend. Thus, by conducting a careful characterization of the Tgof donor:acceptor thin film blends as well as to OPV cell replicas – by means of physical-ageing experiments [2] –, we are able to determine the composition of the intermixed domains of the OPV cells replicas. We demonstrate the applicability of our method for various donor:acceptor systems and discuss the impact of the knowledge gained on materials selection, device fabrication and long-term stability

16:00 - 16:30
Moons, Ellen
Karlstad university
Interface Engineering by Hole Transport Materials in Polymer Solar Cells
Ellen Moons
Karlstad university, SE

Professor in Materials Physics at Karlstad University, Sweden. Research area: morphology of conjugated polymer thin films and molecular self-organisation. Previously employed as Research Scientist at Cambridge Display Technology in Cambridge,UK, and as Research Assistant at University of Cambridge. Post-doc research related to dye-sensitized solar cells at EPFL Lausanne and TU Delft. PhD. from the Weizmann Institute of Science in Rehovot, Israel.

Dargie Deribew a, Axel Hedengren a, Leif Ericsson a, Ellen Moons a
a, Karlstad university, Universitetsgatan, 1, Karlstad, SE

It is well known that charge transport layers, selective for electrons (ETL) or for holes (HTL), have a profound effect on the performance and stability of polymer solar cells. The most common HTL material in polymer solar cells, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), has a high conductivity and transparency and is solution-processable. Knowing that PEDOT:PSS layer is also a significant cause of degradation due to its hygroscopic nature, alternative HTL materials, such as, for instance, thermally evaporated Molybdenum oxide (MoO3), are needed to obtain longer device life time. Here we explored solution-processed interfacial layers of Copper thiocyanate (CuSCN) and phosphomolybdic acid (PMA) as HTLs and found similar to improved device performance compared to the conventional HTLs. We present the surface morphology, optical properties, and surface electronic properties of thin films of these HTL materials using Atomic Force Microscopy (AFM), UV-Vis spectroscopy and Kelvin probe. The HTL layers were applied in polymer solar cells with the conventional architecture ITO/HTL/AL/LiF/Al devices, where the active layer (AL) is the polymer:fullerene blend, TQ1:PC70BM (1:3). The performance and charge carrier recombination behaviourof these solar cells with different HTL were compared.

16:30 - 16:45
Holmes, Russell
University of Minnesota
Intrinsic Measurements of Exciton Transport in Photovoltaic Cells
Russell Holmes
University of Minnesota, US
Tao Zhang a, Dana Dement a, Vivian Ferry a, Russell Holmes a
a, Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, United States

Exciton transport dictates the design and operation of a variety of optoelectronic devices based on organic semiconductors.  This is particularly true in organic photovoltaic cells (OPVs), where excitons diffuse to a dissociating interface to realize a photocurrent.  The sensitivity of OPV performance to the exciton diffusion length (LD) has made these devices a useful platform for the characterization of this important material property.  While device photocurrent spectroscopy is a straightforward method to extract LD, it is frequently limited by unknown recombination losses at dissociating interfaces, making the extracted LD a lower bound. We resolve this limitation and demonstrate a general, device-based photocurrent-ratio measurement to extract the intrinsic LD. Since interfacial losses are not active layer specific, a ratio of the donor and acceptor internal quantum efficiencies cancels this quantity, allowing LD to be extracted.  The generality of this method is demonstrated by extracting LD for both luminescent and dark organic semiconductors, as well as for both small molecule and polymer active materials.  We demonstrate the broader applicability of this approach by also examining semiconductor quantum dots.  Finally, we show that with intrinsic measurements of LD, additional device-relevant information can be extracted regarding the efficiency of exciton relaxation and interfacial charge separation processes.

16:45 - 17:00
Lee, Jaemin
University of Warwick
Dramatically improving the stability of transparent silver electrodes for high performance organic photovoltaics using a molecular monolayer
Jaemin Lee
University of Warwick, GB
Jaemin Lee a, Ross Hatton a
a, University of Warwick, Department of Chemistry, Gibbet Hill Road, Coventry, GB

Vacuum evaporation is proven as a low cost method for the large area deposition of metal films and so is widely used in the food packaging industry. At the same time silver (Ag) films with a thickness of 6-10 nm are promising as the basis for flexible transparent electrodes for organic photovoltaics and displays. However, due to the high surface energy of silver and its slow rate of oxidation in air, very thin evaporated Ag films are morphologically unstable even at room temperature. Consequently, for practical application there is a need to identify an easily implementable and versatile means of imparting long term stability. This talk will describe how a single layer of a bifunctional small molecule deposited from the vapor phase can greatly enhance the morphological and chemical stability of optically thin Ag film electrodes. Due to its very low thickness (~1 nm) this organic layer does not electrically isolate the electrode. It is shown that in 10% efficient inverted, top-illuminated and semi-transparent OPVs substantial improvements in device stability are achieved by inclusion of this layer, which is remarkable give its very low thickness.

17:00 - 17:15
Ruscello, Marta
InnovationLab, Heidelberg
Beneficial Interaction between nickel oxide nanoparticles and polyethylene oxide as printable nanocomposite hole injection layer for organic solar cells
Marta Ruscello
InnovationLab, Heidelberg
Marta Ruscello a, g, Tanmoy Sarkar b, Artem Levitski b, Giovanni Maria Matrone c, Nikolaos Droseros d, Stefan Schlisske a, e, Eleni Sachs a, e, Patrick Reiser a, f, Eric Mankel a, f, Wolgang Kowalsky a, g, Natalie Banerji d, Natalie Stingelin c, Gitti L. Frey b, Gerardo Hernandez-Sosa a, e
a, InnovationLab, Heidelberg
b, Department of Materials Science and Engineering, Technion – Israel Institute of Technology, Haifa 3200003, Israel
c, Department of Materials and Centre for Plastic Electronics, Imperial College London., Exhibition Road, London, GB
d, University of Bern, Department of Chemistry and Biochemistry, Freiestrasse, 3, Bern, CH
e, Light Technology Institute, Karlsruhe Institute of Technology, Engesserstr. 13, 76131 Karlsruhe, Germany
f, Institute of Material Science, TU Darmstadt, 64287 Darmstadt (Germany)
g, Institute for High Frequency Technology, TU Braunschweig, Speyerer Str. 4, Heidelberg, 69115, DE

In the field of organic electronics, rising research attention has been dedicated to the investigation of novel interlayers. A family of materials that has been deserving increasing interest for such purposes is the one of transition metal oxide nanoparticles, which can provide high quality interlayers for both charge injection or extraction. Metal oxide nanoparticles are suitable for solution-processed electronics thanks to many advantages: they can be dissolved in organic solvents and used as printable inks, can be processed at relatively low temperatures and can offer an increased stability compared to conjugated polymers. However, they also present certain technical challenges due to the higher surface to bulk ratio (i.e. surface trap states) or present problems during film formation (i.e. agglomeration).[1] For this reason, various kinds of polymers can be employed to offer a hybrid solution to these issues.

We present here the improvement of the processability of non-stoichiometric nickel oxide (NiOx) nanoparticle ink by blending with high molecular weight polyethylene oxide (PEO). Recently, NiOx has attracted increasing attention as a hole extraction layer in organic and perovskite photovoltaics due to its excellent optical transparency, p-type conductivity and good electron blocking properties. Nonetheless, the fabrication of highly efficient NiOx thin films is challenging due to the low viscosity of the inks or the high sintering temperatures of the precursor approaches. Here, we show how PEO can help dispersing the nanoparticles hindering their aggregation after deposition without compromising film functionality. Through Kelvin Probe, Contact Angle measurement, X-ray Photoelectron Spectroscopy and Transmission Electron Microscopy we observe that the presence of PEO is beneficial for a better tunability of the NiOx film thickness and morphology. We also show that such effect on the film formation is observed to be beneficial when the NiOx:PEO blends are applied as a hole extraction layer on OPV devices, improving device performance. Moreover, the inclusion of the polymer in the nanoparticle ink allows, for the first time, the inkjet-printing of the NiOx layer without requiring high temperature post-treatment. [Manuscript in preparation]

17:15 - 17:30
Nickel, Bert
Organic Nanosheet Transfer for Hybrid 2D/3D Devices
Bert Nickel
Ludwig-Maximilians-University, DE
Bert Nickel a, Batuhan Kalkan a, Antony George b, Andrey Turchanin b
a, Ludwig-Maximilians-University, Physics & CENS, Geschwister-Scholl-Platz 1, 80539 München, Germany
b, Universität Jena, Institute for Physical Chemistry, Lessingstrasse 10, 07743 Jena, Germany

We developed a method to stabilize and transfer organic semiconductor nanofilms. The method is based on crosslinking of the topmost layers of organic films by low energy electron irradiation. The irradiated films, which are deposited on a dissoluble interlayer, are detached from their original substrates and subsequently deposited onto a new substrate [1]. This allows for the fabrication of highly ordered interfaces of organic 3D films and 2D materials. We demonstrate the versatility of this approach by the fabrication of ambipolar MoS2-pentacene field effect transistors. First we study transport properties in order to confirm ambipolar behaviour. Second we apply raster scanning techniques such as photocurrent microscopy and photoluminescence spectroscopy in order to study the local characteristics of such devices with submicron resolution. This technique allowed us previously to identify in unipolar devices injection barriers at contacts and trapping effects in the channel [2]. In ambipolar devices, we can probe also the generation of free carriers by exciton splitting and charge separation at the 2D/3D heterojunction. In order to excite the two materials separately, we have implemented several laser lines which match the respective absorption maxima and minimal of the 3D and 2D materials. Our initial experiments focus on pentacene and MoS2 as 3D and 2D material, however, the transfer method should also be applicable also to C60, which would open a wide range of possible hybrid p/n junctions and related devices.

1) S . J. Noever, M. Eder, F. del Giudice, J. Martin, F. Werkmeister, S. Hallwig, S. Fischer, O. Seeck, N.-E. Weber, C. Liewald, F. Keilmann, A. Turchanin, B. Nickel
Transferable organic semiconductor nanosheets for application in electronic devices
Advanced Materials (2017)

2) C. Liewald, S. Strohmair, H. Hecht, E. D. Głowackic, B. Nickel
Scanning photocurrent microscopy of electrons and holes in the pigment semiconductor epindolidione
Organic Electronics 60, 51 (2018) 

17:30 - 19:00
Poster Session
20:30 - 23:00
Social Diner
Thu Mar 07 2019
08:55 - 09:00
Announcement of the Day
Session 3.1
Chair: Anna Köhler
09:00 - 09:30
Draxl, Claudia
Theoretical Spectroscopy at Hybrid Interfaces
Claudia Draxl
Humbold-Universität, DE

Claudia Draxl is Einstein Professor at the Humbold-Universität zu Berlin, Germany. She received her PhD at the University of Graz, was awarded a honorary doctorate of Uppsala University, Sweden (2000), and was full professor at the Montanuniversität Leoben (2006-2011). Her research interests cover theorectical concepts and methodology, the development of computer codes, and their application to answer questions related to a variety of materials and their properties. A particular focus of the group concerns the quantum-based description of radiation-matter interaction based on many-body perturbation theory and time-dependent DFT, covering various types of excitations, like photoemission, optical and X-ray absorption, electron-loss spectroscopy, and Raman scattering. A recent research focus is on data-driven science, within the NOMAD (Novel Materials Discovery) Centre of Excellence.

Claudia Draxl a
a, Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany

Hybrid materials open new perspectives towards the design and tailoring of materials with desired features and functions for applications in opto-electronics. From a theory point of view, the ab initio description of organic materials and, in particular, their interfaces to inorganic counterparts remains an exciting though challenging issue. Only having proper theoretical concepts and numerical tools in hand which consistently capture the features of molecular materials, from single molecules to hybrid interfaces, allows for getting insight into the leading excitation processes. As many-body effects play a dominant role forefront methodology, that is capable of reliably predicting the electronic structure and optical excitations, is a must. Theoretical spectroscopy, combining Green-function based methods and density-functional theory provide powerful tools for the in-depth understanding of the response of such materials to excitations by electromagnetic radiation. I’ll discuss recent progress and critical challenges in understanding level alignment and light-matter interaction in selected examples, including organic/inorganic interfaces and hybrid perovskites.

09:30 - 09:45
Abbas, Mamatimin
Low optical turn-on voltage in solution processed hybrid light emitting transistor
Mamatimin Abbas
Mamatimin Abbas a, Abdulaziz Ablat a, c, Adrica Kyndiah a, Alexandre Bachelet a, Kazuo Takimiya b, Lionel Hirsch a, Sophie Fasquel a
a, CNRS, University Bordeaux, Bordeaux INP, France
c, Xinjiang University, China

Fabrication of the devices from solvents is the essence of future printed electronics which embodies easy processability, low cost and flexibility.  One particularly interesting device is Light Emitting Field Effect Transistor (LET), as it integrates both the switching and emitting property in a single optoelectronic device, which can significantly simplify the design of active matrix displays.[1] Moreover, as the emission zone is relatively small,  LET can act as future nano light sources.[2] More importantly, LET can render very high current density,[3] a prospective for realizing electrically pumped lasers which still remains as one of the biggest challenges in flexible electronics.

One of the major issues in achieving high performance LET is obtaining both high carrier mobility and high electroluminescence from the active semiconducting layer, requiring complex device engineering.  Here in this work, we present a number of approaches that were applied to decrease optical switch on voltage in hybrid LETs. Firstly, solution processed indium oxide (In2O3) was used as electron transport layer to achieve high current density. Interlayer tungsten polyoxometalate (POM) between the indium oxide and the source-drain electrodes improved the overall performance of the device. Electron mobility reached 11 cm2/Vs, which is 3 times higher than that of the control device. Current on/off ratio increases by 2 orders of magnitude reaching 107.[4] Subsequently, organic emissive layer (Super Yellow) was introduced, and light emission visible for naked eye was observed using asymmetric source/drain electrodes.  In the next step, p-channel organic transport layer (C8-BTBT) was further integrated after improving hole injection. For that, various metal and oxide combinations were applied to determine the optimum hole injection electrode. Finally, we applied hole transport layer and emissive layer blend approach, which considerably decreased the optical switch on voltage as well as enhanced the luminance.  

09:45 - 10:15
Cahen, David
Weizmann Institute of Science & Bar Ilan University
Some Basics to Solve Riddles of Halide Perovskites
David Cahen
Weizmann Institute of Science & Bar Ilan University

Born in the Netherlands,David Cahen studied chemistry & physics at the Hebrew Univ. of Jerusalem (HUJ), Materials Research and Phys. Chem. at Northwestern Univ, and biophysics of photosynthesis (postdoc) at HUJ and the Weizmann Institute of Science, WIS. After joining the WIS faculty he focused on alternative sustainable energy resources, in particular various types of solar cells. In parallel he researches hybrid molecular/non-molecular systems, focusing on understanding and controlling electronic transport across (bio)molecules. He is a fellow of the AVS and the MRS. He heads WIS' Alternative, sustainable energy research initiative.

David Cahen a, b
a, Institute of Nanotechnology and Advanced Materials, Bar Ilan University, ISRAEL
b, Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100, Israel.

When everything is said and done, the most remarkable property of Halide Perovskites is that they can have defect densities that approach those that can be estimated from thermodynamics, i.e, a near-absence of kinetically stabilized defects, which naturally is  the kind on which (external and internal) doping is based. This is especially surprising if we consider the quick and “chimie douce” way of preparation of films as well as of most single crystals. Note though that the experimentally "determined"  defect densities are all deduced from  common (indirect) measurements for charged or neutral defects, using mosels that include assumptions, explicitly and/or implicitly.

In this talk I will show how this behaviour likely reflects a  fundamental property of these materials, with a rather simple basis. In the talk I will combine experimental results from several sources, including our own, for thermodynamic, optical, and electrical data and will ponder the possibility that the conclusions can be generalized to help look for other ultra-low defect density materials.


10:15 - 10:30
Srimath Kandada, Ajay Ram
Center for Nano Science and Tecnology, Istituto Italiano di Tecnologia
Phonon coherences reveal the polaronic character of excitons in two-dimensional lead halide perovskites
Ajay Ram Srimath Kandada
Center for Nano Science and Tecnology, Istituto Italiano di Tecnologia, IT
Ajay Ram Srimath Kandada a, b, c, Felix Thouin b, David Valverde-Chavez c, Claudio Quarti d, Daniele Cortecchia a, Ilaria Bargigia c, David Beljonne d, Annamaria Petrozza a, Carlos Silva b, c
a, Center for Nano Science and Tecnology, Istituto Italiano di Tecnologia, Via Pascoli 70/3, Milano, IT
b, School of Physics, Georgia Institute of Technology
c, School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA
d, Department of Chemistry, Universite de Mons, Belgium

Two-dimensional hybrid lead halide perovskite derivatives have garnered considerable interest for opto-electronic applications, due to the presence of strongly bound and stable excitons even at room temperature. While the excitons in these systems seem to be analogous to those in semiconductor quantum wells, polar lattice fluctuations and dynamic disorder give rise to strong exciton-phonon coupling effects. We have recently identified clear signatures of polaronic effects on the excitonic correlations via quantitative analysis of linear and non-linear optical spectral[1][2]. Here, we establish that the dynamic structural complexity in a prototypical 2D lead iodide perovskite results in the coexistance of diverse exciton resonances, each with distict degree of polaronic character. We coherently excite and probe vibrational wavepacket dynamics by means of high resolution impulsive stimulated Raman spectroscopy, that evolve along different configurational coordinates defined by the normal vibrational modes of the lattice. Based on density functional theory calculations, we assign the observed vibrational modes to various low-frequency (< 50 cm-1) optical phonons involving the motion within the lead iodide layer. We demonstrate that different excitons induce specific lattice reorganizations, which are signatures of their polaronic binding. 




10:30 - 11:00
Coffee Break
Session 3.2
Chair: Marta Ruscello
11:00 - 11:30
Wetzelaer, Gert-Jan
Max Planck Institute For Polymer Research
Charge Injection and Transport in Organic Semiconductors
Gert-Jan Wetzelaer
Max Planck Institute For Polymer Research, DE

Gert-Jan Wetzelaer obtained an MSc degree in Applied Physics at the University of Groningen in 2009. In 2014, he obtained a PhD degree from the University of Groningen. His doctoral research focused on charge transport and recombination in organic light-emitting diodes and solar cells, under supervision of Prof. Paul W.M. Blom. Subsequently, he continued as a postdoctoral researcher on biophotovoltaic cells involving photosynthetic proteins. In 2015, he obtained a position as group leader at the Max Planck Institute for Polymer Research in Mainz, Germany. His research focuses on device physics of organic light-emitting diodes and solar cells, as well as perovskite solar cells. He has co-authored more than 60 articles in peer-reviewed scientific journals.

Gert-Jan Wetzelaer a
a, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany

Organic semiconductors are used in optoelectronic devices, such as organic light-emitting diodes, organic and perovskite solar cells, and organic field-effect transistors. The performance of such devices depends heavily on charge injection and transport. Here, we describe a universal strategy to create Ohmic contacts on organic semiconductors, even with ionization energies of up to 6 eV. The method is based on the use of an interlayer that causes electrostatic decoupling of the electrode from the semiconductor, while establishing alignment of the Fermi level with the energy levels of the organic semiconductor. This interface engineering method to create Ohmic contacts enables us to characterize charge transport in a large range of organic semiconductors. From these measurements we are able to extract important parameters, such as the charge-carrier mobility, energetic disorder and the molecular site spacing. These experimental parameters are then compared to theoretical multiscale simulations, which compute these parameters considering the molecular arrangement and electronic interaction between the molecules. Excellent agreement is found between experiment and theory, which paves the way for predictive charge-transport simulations from the molecular level. Furthermore, the use of this injection startegy will be demonstrated to create efficient organic devices.

11:30 - 11:45
Züfle, Simon
Fluxim AG Katharina-Sulzer-Platz 2, 8400 Winterthur, Switzerland
Comprehensive Analysis of Third-Generation Solar Cells Supported by Drift-Diffusion Simulations
Simon Züfle
Fluxim AG Katharina-Sulzer-Platz 2, 8400 Winterthur, Switzerland
Simon Züfle a, b, Martin Neukom a, b, Sandra Jenatsch b, Beat Ruhstaller a, b
a, Institute of Computational Physics, ZHAW, Wildbachstr. 21, Winterthur, 8401, CH
b, Fluxim AG Katharina-Sulzer-Platz 2, 8400 Winterthur, Switzerland

In order to improve the understanding of the device physics, specifically charge generation, transport and recombination, of organic and perovskite solar cells, a multitude of experimental techniques is available today. In this work we present an overview of opto-electronic characterization techniques including current-voltage curves, impedance spectroscopy, intensity-modulated photocurrent/photovoltage spectroscopy, and various transient experiments such as charge extraction by linearly increasing voltage, transient photocurrent, transient photovoltage and charge extraction. Using our drift-diffusion model we are able to simulate all of the above techniques and investigate how nonidealities like interface barriers, traps or low mobilities can manifest themselves as specific signatures in the data. The combination of different experiments therefore allows us to provide guidelines for the interpretation of measurement results and to unambiguously identify the limiting processes and dominant loss mechanisms. Furthermore, the simulation can be employed inside global fitting routines in order to determine material and device parameters. Hereby we show that the combination of steady-state, transient and modulated techniques is a key to increase the reliability of the extracted parameter values.

11:45 - 12:15
Tvingstedt, Kristofer
University of Würzburg EPVI
Impact of Interfaces and Active Layer Thickness on the Assignment of Charge Carrier Recombination Dynamics in Thin Film Solar Cells.
Kristofer Tvingstedt
University of Würzburg EPVI

Kristofer studied material physics at Linköping University in Sweden and started working on organic solar cells in 2003 under the guidance of prof. Olle Inganäs at the Department of Physics, Chemistry and Biology (IFM). His thesis work was devoted to light trapping and the development of novel electrodes for organic solar cells. After defending his Ph.D in 2008 he continued as a Post doc. focusing his studies on charge transfer state spectroscopy. After a short period in industry he got a Marie Curie grant in 2013 to go to the University of Würzburg in Germany where he devoted research efforts to study recombination dynamics in organic solar cells. These studies were soon extended to also include hybrid perovskite solar cells. He was awarded with a principal investigator DFG grant in 2017 to pursue perovskite solar cell recombination research at the University of Würzburg. He has published more than 50 peer reviewed papers, has co-authored two book chapters on organic solar cells and has currently an h-index of 31.

Kristofer Tvingstedt a
a, Experimental Physics VI, Julius Maximillian University of Würzburg, 97074 Würzburg, Germany

Accurately identifying and understanding the dominant charge carrier recombination mechanism in perovskite solar cells is of crucial importance for further improvements of this already promising photovoltaic technology. Understanding the order, rate and spatial whereabouts of the recombination processes as a function of excess carrier concentration is imperative towards identifying the remaining culprits behind the voltage deficit to the thermodynamic radiative limit (1.33 V for MaPbI3). With this objective, various electrical transient methods based on photovoltage decay have previously been employed. However, these techniques can be strongly influenced by the device capacitive response which overlays with the steady state relevant bulk carrier recombination. Herein, we will first outline the main limiting parameters in the assignment of correct and steady state relevant charge carrier lifetimes in both organic and perovskite thin film solar cells. To ascertain the identification of steady state relevant bulk charge carrier dynamics, we will highlight the benefit of evaluating thicker films at higher light intensity to minimize the impact of spatial capacitance artifacts. We focus our study on the electrical transient response in very efficient planar co-evaporated solar cells with an increased active layer thickness, up to 820 nm. While the increased capacitance for the thin cells leads to longer perceived decay times in the lower voltage regime, the higher voltage regime shows kinetics becoming independent of active layer thickness, allowing us to identify the transition from capacitance affected to the sought-after bulk charge carrier dynamics. Finally, we determine that the recombination order in thicker devices is ranging in between 1.6-2. These values are noticeably lower than what has previously been reported by these or equivalent electrical methods and are, more in line with dynamics observed in pure film, pointing towards trap-assisted and free carrier recombination under operating conditions in complete perovskite photovoltaic devices.

12:15 - 12:30
Ahmadpour, Mehrad
Southern University of Denmark
Crystalline metal oxide contact layers in organic and hybrid photovoltaics
Mehrad Ahmadpour
Southern University of Denmark
Mehrad Ahmadpour a, André L. F. Cauduro F. Cauduro b, Mina Mirsafaei a, John Lundsgaard Hansen c, Brian Julsgaard c, Horst-Günter Rubahn a, Peter Balling c, Nadine Witkowski d, Andreas K. Schmid b, Morten Madsen a
a, SDU NanoSYD, Mads Clausen Institute, University of Southern Denmark, Alsion 2, Sønderborg, DK-6400, Denmark
b, National Center for Electron Microscopy, The Molecular Foundry, Berkeley, California, 94720, US
c, Department of Physics and Astronomy and iNano, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C
d, Sorbonne Universités, UPMC Univ Paris 06, UMR CNRS 7588, Institut des Nanosciences de Paris (INSP), 4 place Jussieu, 75005 Paris


Thin metal oxide films have attracted a lot of attention in the past years due to their unique ability to act as electrode contact layers in novel electronic and optoelectronic devices. Prominent examples are molybdenum oxide (MoOx) and titanium oxide (TiOx) thin films used as hole and electron contact layers, respectively, in organic and hybrid photovoltaics. Amongst many different methods used for fabrication of these films, reactive sputtering remains as a promising technique, due to the unique composition tuning and industrial scale processing possibilities[1]. In the work presented here, crystalline MoOx and TiOx layers are developed from reactive sputtering and vacuum annealing, and implemented as contact layers in organic and hybrid solar cells.


The film composition is characterized using X-Ray Photoelectron Spectroscopy (XPS), work function using Low Energy Electron Microscopy (LEEM) and Ultraviolet Photoelectron Spectroscopy (UPS), structure using Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD), morphology using Atomic Force Microscopy (AFM) and optical properties using UV-VIS spectroscopy. Importantly, we find that both the structure and work function of the developed thin films can be tuned by the annealing process, spanning an almost 2eV tuning range in the case of MoOx.[2] Furthermore, due to the formation of the crystalline films with a low defect density, made possible via the reactive sputtering method, more efficient and stable contact layers for photovoltaic devices are developed. Non-encapsulated DBP/C70 solar cell devices based on the sputtered MoOx are demonstrated to remain with impressive 80% of the initial performance after 240 hours of light soaking under 1 sun (1000W/m2) at ~60°C, which is superior to similar devices based on conventional thermally evaporated MoOx layers. Fabricated PTB7/PCBM solar cells devices based on the sputtered TiOx are demonstrated to lead to s-shape-free high performing devices, otherwise typically appearing when employing TiOx as contact layers. The underlying film properties leading to these appealing device properties are evaluated based on the extensive surface and film characterization performed.


 The work thus demonstrates a viable method for tuning the electronic and optoelectronic properties of metal oxide thin films, which can be applied in combination with a wide range of materials in e.g. organic and hybrid photovoltaics.


12:30 - 13:00
Sooraj Kumar, Md. Imteyaz Ahmad
Rapid Thermal Processing of Absorber Layer (FAPbI3) and Compact-TiO2 Layer of Perovskite Solar Cell.
Ankur Solanki, Pankaj Yadav, Silver Tureen, Swee Sien Lim, Saliba Michael, Tze Chien Sum
The role of inorganic cations (Cs+ and Rb+) on charge carrier dynamics in perovskite solar cells
Denys Priadko, Christina Saller, Frank-Julian Kahle, Thomas Müller, Tobias Hahn, Steffen Tscheuschner, Peter Strohriegl, Heinz Bässler, Anna Köhler
Studying interlayer molecular diffusion in donor-acceptor systems
Eirini Lariou, Giovanni Maria Matrone, Natalie Stingelin, Hazem Bakr, Konstantin Schötz, Fabian Panzer, Anna Köhler, Sophia C.Hayes
Temperature Dependent Structural Evolution of PCE11
Roghayeh Imani, Zhen Qiu, Reza Younesi, Meysam Pazoki, Daniel L. A. Fernandes, Pavlin D. Mitev, Tomas Edvinsson, Haining Tian
Perovskite solar cells powered electrochemical cell for efficient CO2 conversion into hydrocarbons over Cu-based catalyst: in-situ monitoring of catalyst deformation
Shengyang Chen, Bastian Haehnle, Ioan Botiz, Alexander J.C. Kuehne, Paul Stavrinou, Natalie Stingelin
How Can We Engineer Hierarchical Structures and Pattern Functional Organic Materials?
Mihirsinh Chauhan, Yu Zhong, Sven Hüttner, Anna Köhler, Fabian Panzer
Understanding film formation of hybrid perovskites: Optical in situ characterization of MAPbI3 thin film formation during solution processing
Sofia Masi
Room-temperature processed films of colloidal carved rod-shaped nanocrystals of reduced tungsten oxide as interlayers for perovskite solar cells
Agustín Bou, Bisquert Juan
Surface Polarization in Perovskite Solar Cells and Inductive Loop in their Impedance Spectroscopy Response
Xiao Ma, Giulio Simone, Matt Dyson, Koen Hendriks, René Janssen, Gerwin Gelinck
High Detectivity Near-Infrared Organic Photodiodes
Giovanni Maria Matrone, artem Levitsky, fabian panzer, konstantin Schotz, felix Thouin, ilaria bargigia, sebastian engmann, carlos silva, anna kohler, gitti frey, lee j. richter, natalie stingelin
Beyond a facile definition of phase separation ― A polymer science approach to predict and manipulate the morphology of bulk heterojunctions solar cells.
Marisé García-Batlle, Osbel Almora, Germà García-Belmonte
Jesús Rodríguez-Romero, Bruno Clasen Hames, Iván Mora-Seró, Eva M Barea
Effect of the fabrication´s temperature in morphological and electrical properties of 2D/3D perovskites
Tanmoy Sarkar, Basel Shamieh, Gitti Frey, Gerwin Gelinck
Self-segregated interlayers in organic field effect transistors
Dmytro Volyniuk, Galyna Sych, Oleksandr Bezvikonnyi, Juozas Vidas Grazulevicius
Versatile exciplex-forming materials for simplified non-doped white OLEDs based on dual interface emission
Konstantin Schötz, Abdelrahman Askar, Wei Peng, Dominik Seeberger, Tanaji P. Gujar, Mukundan Thelakkat, Sven Hüttner, Osman Bakr, Karthik Shankar, Anna Köhler, Fabian Panzer
Unravelling the origin of double peak emission of hybrid perovskites
Vittal Prakasam, Daniel Tordera, Gerwin Gelinck, henk Bolink
Device Stability of Perovskite Light-Emitting Diodes
Benedikt Dänekamp, Nikolaos Droseros, Christian Müller, Michael Sendner, Francisco Palazon, Robert Lovrinčic, Natalie Banerji, Michele Sessolo, Henk Bolink
Photo physical properties of stoichiometrically tuned methylammonium lead iodide (MAPI) films
Ana María Igual-Muñoz, Henk Bolink, Pablo P.Boix
Tin-lead perovskite synthesized through sublimation methods as the absorber of a solar cell
Jan Pospisil, Oldrich Zmeskal, Stanislav Nespurek, Jozef Krajcovic, Martin Weiter, Alexander Kovalenko
Density of bulk trap states of hybrid lead halide perovskite single crystals: temperature modulated space-charge-limited-currents
Sergio Castro-Hermosa, Janardan Dagar, Matteo Gasbarri, Fabio Matteocci, Alessandro Lorenzo Palma, Emanuele Calabrò, Lucio Cina, Andrea Marsella, Aldo Di Carlo, Thomas Meredith Brown
Effective Low Temperature Electron Transport Layers for Flexible Perovskite Solar Cell on Plastic and Paper Substrates
Maria Grazia La Placa, Daniel Pérez-del-Rey, Lidon Gil-Escrig, Michele Sessolo, Henk J. Bolink
Ultrathin Films as Cathode Interfaces in Efficient Vacuum Deposited Perovskite Solar Cells
Nikolaos Droseros, Giulia Longo, Jan C. Brauer, Michele Sessolo, Henk J. Bolink, Natalie Banerji
Correlation between the Photoluminescence Properties and the Crystal size in MAPbBr3 Perovskite Thin Films
Matthias Diethelm, Quirin Grossman, Maciej Kawecki, Balthasar Blülle, Sandra Jenatsch, Andreas Schiller, Evelyne Knapp, Frank Nüesch, Roland Hany
Unravelling the Dynamic Evolution of the Emission Zone in Sandwich Polymer Light-Emitting Electrochemical Cells
Junqing Shi, Anna Isakova, Abasi Abudulimu, Marius van den Berg, Oh Kyu Kwon, Alfred J. Meixner, Soo Young Park, Dai Zhang, Johannes Gierschner, Larry Luer
Photoexcitation Dynamics of Solution-processable All-small-molecule Bulk Heterojunction Photovoltaic Blends
Sara Marina, Jaime Martin
Exploring the Microstructure and Thermotropic Phase Behaviour of ITIC.
Timur Burganov, Sergey Katsyuba, Liliya Islamova, Guzel Fazleeva, Alexey Kalinin, Andreas Köhn
Insight into the Peculiarities of the Excited State Properties in the Series of Novel Donor-acceptor Indolizine-based Systems
Faisal Almana, Weidong Tang, Oliver Fenwick, Ajay Taraiya, Martyn McLachlan, Natalie Stingelin
Chain Morphology Effect on Thermal Conductivity of Polymer-Based Materials
Ioan Botiz, Diana Zaharie-Butucel, Cosmin Leordean, Bogdan Marta, Simion Astilean, Otto Todor-Boer, Markus Reichenberger, Natalie Stingelin, Anna Köhler
Enhancing Polyfluorene Photoluminescence Through Ilumination
Raluca Tarcan, Otto Todor-Boer, Ioan Petrovai, Simion Astilean, Ioan Botiz
Dispersing Reduced Graphene Oxide in Organic Solvents for Optoelectronic Devices
Laura Canil, Antonio Abate
Work Function Tuning through Self-Assembling Monolayers of Fluorinated Molecules
Daniel Pérez-del-Rey, Pablo Boix, Henk Bolink
Interfacially Modified Molybdenum Oxide in NiP and PiN Vacuum Deposited High Efficiency Perovskite Solar Cells
Levente Máthé, Ioan Grosu
Graphene-based Single Electron Transistor: Transition from the Coulomb Blockade to Kondo Effect
Otto Todor-Boer, Ioan Petrovai, Raluca Tarcan, Adriana Vulpoi-Lazar, Simion Astilean, Leontin David, Roger Hiorns, Natalie Stingelin, Ioan Botiz
Enhancing the Photoluminescence Quenching in Donor-acceptor PCE11:PPCBMB Films Through Optimization of the Film Microstructure
Ioan Petrovai, Otto Todor-Boer, Raluca Tarcan, Leontin David, Simion Astilean, Ioan Botiz
Crystals of Perovskites Prepared Via Convective Self-assembly
Hazem Bakr, Mihir Chauhan, Fabian Panzer, Mukundan Thelakkat, Anna Köhler
Film Formation in Blends of PCE11 Polymer Donor with Perylene Diimide Based Acceptors
Jongmin Kim, Andris Gulans, Claudia Draxl
Modification of Work Function of Au(111) Upon Adsorption of PEG(thiol)
Rashmi Runjhun, Daniel Prochowicz, Mohammad Tavakoli, Pankaj Yadav, Marcin Saski, Anwar Alanazi, Dominik Kubicki, Zbigniew Kaszkur, Shaik Zakeeruddin, Janusz Lewiński, Michael Grätzel
Engineering of Perovskite Materials Based on Formamidinium and Cesium Hybridization for High-Efficiency Solar Cells
Cecilia Vona, Dmitrii Nabok, Claudia Draxl
Electronic and Optical Properties of Pb and Sn Based Halide Perovskites from First Principle
Karen Strassel, Surendra Babu Anantharaman, Jakob Heier, Frank Nüesch, Roland Hany
Making the Invisible Visible Using Cyanine J-aggregate Based Upconversion Devices
Minh Triet Nguyen, Dane McCamey
Toward Ge-based Singlet Fission Solar Cells
Zafer Hawash, Jorge Ávila, Ana M. Igual, Pablo P Boix, Henk J Bolink, Ellen Moons
Photoemission Spectroscopy Study of SnF2 Treated FASnPbI3
Agustin Alvarez, Nadja Isabelle Desiree Klipfel, Cristina Roldán-Carmona, Mohammad Khaja Nazeeruddin, Francisco Fabregat-Santiago, Hiroyuki Kanda, Maria Cristina Momblona Rincón
Effects of Charge Selective Contacts in Perovskite Solar Cells Through Impedance Spectroscopy Measurements.
Marcel Ross, Lidon Gil-Escrig, Amran Al-Ashouri, Marko Jost, Steve Albrecht
Methylammonium Lead Iodide Perovskite Solar Cells from direct Co-Evaporation
Rocio Garcia-Aboal, Sonia Remiro-Buenamañana, Fernando Ramiro-Manzano, Pedro Atienzar
Quasi-3D Lead Bromide Perovskite Encapsulating Subphthalocyanine
Elena Segura-Sanchis, Rocio Garcia-Aboal, Fernando Ramiro-Manzano, Pedro Atienzar
Optoelectronic Properties of Hybrid Halide Perovskite Single Crystals
Sandheep Ravishankar, Clara Aranda, Sandy Sanchez, Juan Bisquert, Michael Saliba, Germa Garcia-Belmonte
Perovskite Solar Cell Modeling using Light and Voltage Modulated Techniques
Kassio PS Zanoni, Pablo P Boix, Andrea SS de Camargo, Henk J Bolink
The Use of Molybdenum Oxide Bronze (HXMoO3) in Perovskite Solar Cells
Wiria Soltanpoor, Gence Bektaş, Mehmet Cem Şahiner, Hava Zekiye Kaya, Esra Bag, Görkem Günbaş, Selçuk Yerci
All vacuum processed perovskite solar cells using sputtered NiOx as hole transport layer
David Poussin, Artem Levitsky, Jonathan Ngiam, Bob Xu, Gitti Frey, Natalie Stingelin, Martyn McLachlan
3D Ordered Porous Fluorine Tin-Oxide Transparent Electrodes for Improved Photovoltaics
Clara Aranda, Antonio Guerrero, Juan Bisquert
Enhancing bulk light emission of methylammonium lead bromide perovskite solar cell by reducing surface recombination
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