Program
 
Mon Jan 20 2020
16:00 - 18:00
Registration
17:00 - 18:30
Welcome reception_Room 202
 
Tue Jan 21 2020
08:00 - 09:30
Registration
09:20 - 09:25
Announcement of the day
09:25 - 09:30
Opening
Session G1
Chair: Michio Kondo
09:30 - 09:55
G1-I1
Miyasaka, Tsutomu
Toin University of Yokohama
Next generation of perovskite PV with all-inorganic absorbers and dopant-free hole transporters
Miyasaka, Tsutomu
Toin University of Yokohama, JP

Tsutomu (Tom) Miyasaka received his Doctor of Engineering from The University of Tokyo in 1981. He joined Fuji Photo Film, Co., conducting R&Ds on high sensitivity photographic materials, lithium-ion secondary batteries, and design of an artificial photoreceptor, all of which relate to electrochemistry and photochemistry. In 2001, he moved to Toin University of Yokohama (TUY), Japan, as professor in Graduate School of Engineering to continue photoelectrochemistry. In 2006 to 2009 he was the dean of the Graduate School. In 2004 he has established a TUY-based company, Peccell Technologies, serving as CEO. In 2005 to 2010 he served as a guest professor at The University of Tokyo.

His research has been focused to light to electric energy conversion involving photochemical processes by enhancing rectified charge transfer at photo-functional interfaces of semiconductor electrodes. He has contributed to the design of low-temperature solution-printing process for fabrication of dye-sensitized solar cells and solid-state hybrid photovoltaic (PV) cells. Since the discovery of the organic inorganic hybrid perovskite as PV material in 2006 and fabrication of high efficiency PV device in 2012, his research has moved to R&Ds of the lead halide perovskite PV device. He has promoted the research field of perovskite photovoltaics by organizing international conferences and by publishing many papers on enhancement of PV efficiency and durability, overall citation number of which is reaching more than 5,000 times. In 2009 he was awarded a Ministry of Science & Education prize on his achievements of green sustainable solar cell technology. In 2017 he received Chemical Society of Japan (CSJ) Award. He is presently directing national research projects funded by Japan Science and Technology Agency (JST) and Japan Aerospace Exploration Agency (JAXA).

Authors
Tsutomu Miyasaka a
Affiliations
a, Toin University of Yokohama, Yokohama, Japan
Abstract

Enormous efforts have been made in the last 8 years to up-grade the performance of lead halide hybrid perovskite solar cells (PSCs).1 Although efficiency level has reached 25%, PSCs face serious challenges of practical stability and durability required for industrialization. Compositional engineering of lead halide perovskites by mixing different cations and anions, using modulator molecules and mixing 2D and 3D structures have improved the stability of perovskites against heat and moisture. However, organic cations in halide perovskites (methylammonium, etc.) and use of diffusible ionic dopants in hole transport materials (HTMs) are responsible for low stability of perovskites at high temperatures (>120oC). In this respect, use of all-inorganic perovskite materials and dopant-free HTMs is highly desired.2 We have conducted some work in this direction which includes stabilization of CsPbI3 black phase3 and use of dopant-free HTMs. We could show that PSCs with all-inorganic perovskites and dopant-free HTMs are capable of efficiency up to 15%.2 Further, Open-circuit voltage was found to be enhanced over 1.4V. In preparation of all-inorganic perovskites, a big challenge should be directed to development of lead-free perovskite materials for environmental safety in practical applications.2

Among extensive applications of PSCs for outdoor and indoor power generation, use of PSCs in space environments is also promising because thin perovskite photovoltaic films demonstrate high stability and tolerance against exposure to severe space environment having high energy particle irradiations (proton and electron beams).4 Thin absorbers (<500 nm) avoid accumulation of particles and due to intrinsic defect tolerant nature of perovskites, radiation-induced collision damage is highly suppressed. Our current efforts in making PSCs based on both lead and lead-free perovskites, and future perspectives of perovskite photovoltaics will be introduced.

 

REFERENCES

1. A. K. Jena, A.,Kulkarni, T. Miyasaka, Chem. Rev. 2019, 119, 3036–3103.

2. T. Miyasaka, A. Kulkarni, Gyu Min Kim, Senol Öz, and A. K. Jena, Adv. Energy. Materials 2019, 1902500, 1-20.

3. A. K. Jena, A. Kulkarni, Y. Sanehira, M. Ikegami, and T. Miyasaka, Chem. Mater. 2018, 30,

6668-6674.

09:55 - 10:00
Discussion
10:00 - 10:45
Coffee Break
Session G2
Chair: Tsutomu Miyasaka
10:45 - 11:10
G2-I1
PARK, TAIHO
Pohang University of Science & Technology
Thermally Stable, Planar Hybrid Perovskite Solar Cells with High Efficiency
PARK, TAIHO
Pohang University of Science & Technology, KR

-Ph.D. Chemistry, University of Cambridge

-MS. Chemistry, POSTECH

-BS. Chemistry, Sogang University

Research interests

- Synthesis of smart conducting small molecules and polymers

- Development of energy devices and laser spectroscopic techniques

- Study in energy transfer at the interface between semiconductor and organic materials

Professional Experience

2014-2015 : Visiting Research Fellow, LG Chem. Research Park, Daejeon, Korea

2007–present: Assistant, Associate, Full Professor, Chemical Engineering, Adjunct Professor of Department of Chemistry, School of Interdisciplinary Bioscience and Bioengineering (i-Bio), and Division of Advanced Materials Science, POSTECH

2003–2007: Post-Doctoral Research Fellow, Chemistry, UIUC, USA

1992–1999: Researcher/Senior researcher/Team leader, LG Chem. Research Park, Daejeon, Korea

Authors
TAIHO PARK a
Affiliations
a, Pohang University of Science and Technology
Abstract

Tin oxide (SnO2) is a promising material for the electron transport layer in planar perovskite solar cells (P-PSCs) due to its suitable energy level and high electron mobility. SnO2-based P-PSCs show the highest power conversion efficiency among planar structure devices, but the PCE remains still low compared to the mesoporous TiO2-based PSCs and there is a lack of thermal stability study. In this study, we develop a simple interface engineering to improve optoelectronic properties and the thermal stability of the P-PSCs. The modified SnO2 shows high conductivity, effective charge extraction ability and high recombination resistance. Empirically, efficiencies of 21.43% and 20.5% were reached for the device with doped Spiro-OMeTAD and with dopant-free asy-PBTBDT, respectively, in the present study. The devices with modified SnO2 show excellent stability under mild (humidity of 25%) and harsh conditions (humidity of 85%; temperature of 85°C). Thus, our newly developed method guarantees highly efficient and thermal stable P-PSCs.

11:10 - 11:15
Discussion
11:15 - 11:40
G2-I2
Sum, Tze Chien
Nanyang Technological University (NTU), Singapore
Perovskite Hot Carrier Dynamics
Sum, Tze Chien
Nanyang Technological University (NTU), Singapore, SG

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

Authors
Tze Chien Sum a
Affiliations
a, NTU Singapore - Nanyang Technological University, Physics and Appld Physics, Nanyang Avenue, 50, Singapore, SG
Abstract

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

References

G. C. Xing, N. Mathews, S. Sun, S. S. Lim, Y. M. Lam, M. Graetzel, S. Mhaisalkar and T. C. Sum*, “Long-Range Balanced Electron and Hole Transport Lengths in Organic-Inorganic CH3NH3PbI3”, Science, 342 (6156) 344-347 (2013),

Y. Yang, David P. Ostrowski, R. M. France, K. Zhu, J. van de Lagemaat, J. M. Luther & Matthew C. Beard, “Observation of a hot-phonon bottleneck in lead-iodide perovskites”, Nature Photonics 10, 53–59 (2016)

M. J. Li, S. Bhaumik, T. W. Goh, M. S. Kumar, N. Yantara, M. Graetzel, S. G. Mhaisalkar, N. Mathews, and T. C. Sum*, “Slow Cooling and Highly Efficient Extraction of Hot Carriers in Colloidal Perovskite Nanocrystals”, Nature Communications 8 14350 (2017)

T. C. Sum*, N. Mathews, G. Xing, S. S. Lim, W. K. Chong, D. Giovanni, H. A. Dewi, “Spectral Features and Charge Dynamics of Lead Halide Perovskites: Origins and Interpretations (Invited Article)”, Accounts of Chemical Research 49 (2) 294-302 (2016),

J. Fu, Q. Xu, G. Han, B. Wu, C. H. A. Huan, M. L. Leek & T. C. Sum*, “Hot carrier cooling mechanisms in halide perovskites”, Nature Commununications 8:1300 (2017)

11:40 - 11:45
Discussion
11:45 - 12:10
G2-I3
Bach, Udo
Monash University / CSIRO
Single-Crystalline and Back-Contact Perovskite Optoelectronics
Bach, Udo
Monash University / CSIRO

Udo Bach is a full professor at Monash University in the Department of Chemical Engineering; the Deputy Director of the ARC Centre of Excellence in Exciton Science and an ANFF-VIC Technology Fellow at the Melbourne Centre of Nanofabrication (MCN).  He received his PhD from the Swiss Federal Institute of Technology (EPFL, Switzerland) working in the research group of Prof Michael Grätzel and worked for 3 years in a technology start-up company in Dublin (Ireland).  Subsequently he spent 15 months as a postdoc in the group of Prof. Paul Alivisatos in UC Berkeley (USA) before moving to Monash University in November 2005 to establish his own research group.

 

Prof Bach has a strong background in the area of photovoltaics and nanofabrication.  He is involved in fundamental and applied research in the area of perovskite and dye-sensitized solar cells.  He has additional research activities in the area of nanofabrication, DNA-directed self-assembly, nanoprinting, plasmonics for sensing, photovoltaic applications and combinatorial photovoltaic materials discovery.

Authors
Udo Bach a, b, Wenxin Mao a, Xiongfeng LIn a, Siqi Deng a
Affiliations
a, ARC Centre of Excellence in Exciton Science, Department of Chemical Engineering, Monash University, Clayton, VIC, Australia
b, Melbourne Centre for Nanofabrication, Australia, AU
Abstract

Solution-processed thin films of lead halide perovskites show exceptional properties, making them interesting candidates for a range of optoelectronic applications such as solar cells and light-emitting diodes. The thickness and crystallite-size in these films is typically in the sub-micron range, resulting in an abundance of grain-boundaries. Here we will describe techniques for growing thin single-crystalline lead perovskite crystallites with edge lengths of several tens of microns and thicknesses of around 1 micron, starting from single-source 1D lead halide perovskite precursors. In a first study we used platelet-shaped MAPbBr3 single-crystals to fabricate active electro-optical modulators (AEOM) exhibiting > 98% light transmission intensity modulation. In a second study we successfully grew mixed halide MAPbBr(3-x)Ix single crystals to study photoinduced halide demixing in crystalline materials, using a range of different spectroscopic techniques such as narrowband fluorescence imaging and time-resolved spectroscopy. In the final section of this talk we will report on the recent progress in the development of back-contact perovskite solar cells, including the use of mask-free lithography techniques and novel honey-comb-like back-contact architectures.

12:10 - 12:15
Discussion
12:15 - 12:40
G2-I4
Yamada, Hiroko
Nara Institute of Science and Technology - Japan
Engineering Thin Films of a Tetrabenzoporphyrin toward Efficient Charge-Carrier Transport
Yamada, Hiroko
Nara Institute of Science and Technology - Japan, JP

Hiroko Yamada was born in Kamakura. She received her Ph.D. degree in 1992 from Kyoto University, under the guidance of Prof. Kazuhiro Maruyama and Prof. Atsuhiro Osuka, focusing on the synthesis and characterization of carotenoid-linked porphyrins. She was selected as a Research Fellow of the Japan Society for the Promotion of Science (JSPS) in 1992-1994. In 1993, she did her research under Prof. Michael R. Wasielewski in Argonne National Laboratory, USA. In 1994, she joined International Research Laboratory, Ciba Geigy Ltd., then moved to Ciba Specialty Chemicals Inc. She started her academic career in 1998 as a post-doctorate researcher under Prof. Yoshiteru Sakata and Prof. Hiroshi Imahori at the Institute of Scientific and Industrial Research (ISIR), Osaka University, then a post-doctorate researcher of CREST, JST under Prof. Shunichi Fukuzumi and Prof. Hiroshi Imahori at Graduate School of Engineering, Osaka University. Since 2003, she was an associate professor in the group of Prof. Noboru Ono in Graduate School of Science and Engineering, Ehime University, and moved to an associate professor as a tenure track in Grad1uate School of Materials Science, Nara Institute of Science and Technology in 2011. She was promoted to a full professor in 2012. In 2006–2010, she was a researcher of PRESTO, JST, and in 2010-2016 a group leader of CREST project, JST.

Authors
Hiroko Yamada a
Affiliations
a, Nara Institute of Science and Technology - Japan, 8916-5 Takayama-cho, Ikoma, 630-0192, JP
Abstract

Tetrabenzoporphyrin (BP) is a p-type organic semiconductor characterized by the large, rigid p-framework, excellent stability, and good photoabsorption capability. However, the extremely low solubility of BP hampers solution processing not only for thin-film preparation, but also for chemical modification and purification. Ono and coworkers judiciously circumvented the solubility issue via the use of a thermally convertible precursor, CP[1]. CP quantitatively transforms to BP upon heating by releasing ethylene, an easily removable gaseous compound, as a solo by-product. Accordingly, a high-purity thin film of BP can be prepared by depositing CP as a solution and then heating it to effect the retro-Diels–Alder reaction in situ. However, the control of the solid-state arrangement of BP frameworks, especially in solution-processed thin films, has not been intensively explored, and charge-carrier mobilities observed in BP-based materials have stayed relatively low as compared to those in the best organic molecular semiconductors. This work concentrates on engineering the solid-state packing of BP derivatives toward achieving efficient charge-carrier transport in its solution-processed thin films[2].

12:40 - 12:45
Discussion
Industry talks
Chair not set
12:45 - 12:50
talks-S1
Sorbello, Luca
Greatcell Solar
Hyperion a bright future for solar simulators: The Greatcell Solar Italia way
Sorbello, Luca
Greatcell Solar
Authors
Luca Sorbello a
Affiliations
a, Greatcell Solar
Abstract

In the last decades to reproduce an AM1.5G spectrum, matching the A class, scientists were practically obliged to use expensive solar simulators mounting complex optics and using xenon arc bulbs as light sources. Such light source has multiple disadvantages and to this day spare bulbs are still quite expensive and with a limited life time (1000 h-1500 h) that make such technology not worth for long life testing, large area spot or frequent switching on and off.

In the last 5 years LED technology improved drastically and in the face of a constant improvement in quality, reliability and an increase in radiant power, a remarkable reduction in prices was observed, especially concerning critical bandwidth as the ones between 350 nm and 400 nm and the between 700 nm and 1100 nm. These allowed a very fast development of high efficient, long life, stable but expensive Solar Simulators based on LEDs technology.

Greatcell Solar Hyperion is, without doubts, a breakthrough on LED Solar simulators technology as it assures a high reliability, high accuracy and long life (>15000 h) at a very competitive price. Greatcell Solar Hyperion matches triple A+ class, respecting the most stringent international standards, over 16 cm X 16 cm spot (making it compatible i.e. with standard C-Si solar cells) and a triple A class over 22 cm X 22 cm illumination area, making it suitable to test multiple small and large areas devices.

Thanks to the innovative concept of Greatcell Solar Hyperion, it was possible to contain electrical consumption keeping the latter below a remarkable value of 600 W/h. Furthermore, through a dedicated driving software, it is possible to customise Hyperion spectrum modifying individually each one of the 20 LED families mounted. Greatcell Solar Hyperion LED solar simulator is was conceived as a modular structure, this opens the possibility to expand the illumination spot to host much larger substrates respect standard lab ones.

Greatcell Solar Hyperion can surely be considered a unique sun light emulator, capable to reproduce solar spectrum in a very faithful way as never done before with traditional xenon arc lamps sun simulators.

13:00 - 14:30
lunch
Session A1
Chair: Udo Bach
14:30 - 14:55
A1-IS1
Chen, Jung-Yao
National Chung Cheng University, TW
Non-Volatile Photomemory with a Ultrafast and Multi-Level Memory Behavior
Chen, Jung-Yao
National Chung Cheng University, TW, TW

Education

2011-2016  Doctor of Philosophy in National Taiwan University, Taipei, Taiwan

2008-2010  Mater of Science in National Taiwan University, Taipei, Taiwan

2004-2008  Bachelor of Science in National Cheng Kung University, Tainan, Taiwan

 

Professional Appointments

2018-now Assistant Professor, Department of Chemical Engineering, National Chung Cheng University.

2016-2018 Postdoctoral Fellow (with Professor Wen-Chang Chen), Department of Chemical Engineering, National Taiwan University.

2015-2016 Visiting student (with Professor Alex Jen), Department of Material Science Engineering, University of Washington.

 

Research Interests: Polymer physic and engineering, Perovskite, Composite material, Electrospinning, Soft optoelectronic.

Authors
Jung-Yao Chen a
Affiliations
a, National Chung Cheng University, TW, Chiayi County, Taiwán, Chiayi, TW
Abstract

Light Fidelity (Li-Fi) have been show the next-generation communication system with the features of high security, high speed and low interference. It is of great urgency to exploration of corresponding devices such as light-emitting diodes (LEDs), image sensors, opto-couplers, photodiodes, microcontrollers and non-volatile flash photomemory. Among the plethora of derivatives in optical wireless communications, non-volatile flash photomemory is of particular interest since it is the essential building block of computation technology for nowadays big database storage device with ultrafast programming rate. Herein, versatile photoactive material with exotic photo-physic properties have been utilized as floating gate to develop the ultrafast responsive non-volatile flash photomemory. Time-resolved photoluminescence and cryogenic photoluminescence have been revealed the fact that the charge transfer rate between photoactive layer and active channel. Through the delicate material selection and morphology manipulation, the devices possess wavelength/power/illumination time-distinguishable multilevel behavior within very short photo-programming time down to~ 1 ms. The ultrafast programming time of non-volatile photomemory trigger the realization of Li-Fi in the near future.

14:55 - 15:00
Discussion
15:00 - 15:15
A1-O1
Nugraha, Mohamad I.
King Abdullah University of Science and Technology (KAUST) - Saudi Arabia
Rapid Photonic Curing for the Fabrication of Strongly-Confined Colloidal Quantum Dot Transistors with High Carrier Mobility
Nugraha, Mohamad I.
King Abdullah University of Science and Technology (KAUST) - Saudi Arabia, SA
Authors
Mohamad I. Nugraha a, Emre Yarali a, Yuliar Firdaus a, Yuanbao Lin a, Nimer Wehbe a, Abdulrahman El-Labban a, Emre Yengel a, Thomas D. Anthopolous a
Affiliations
a, King Abdullah University of Science and Technology (KAUST) - Saudi Arabia, 4700 King Abdullah University of Science and Technology (KAUST), Thuwal, SA
Abstract

Colloidal quantum dots (CQDs) are attractive semiconducting materials for broad optoelectronic devices, serving an ease of device fabrication compatible with low-temperature processing and low-cost deposition methods. Fabrication of CQD thin-film transistors (TFTs), is so far finalized with conventional thermal annealing, which requires prolonged processing time; yet it leaves insulating organic residues behind, suppressing charge carrier mobility (~10-2 cm2V-1s-1). Here we demonstrate a millisecond heat treatment of lead sulfide (PbS) CQD films using photonic curing, which results in high carrier mobility in TFT devices. In comparison with conventional thermal annealing, the photonic curing is found to effectively suppress organic residues, yet it preserves quantum confinement in the films. With increasing flashing power, the electron mobility on SiO2-gated devices increases up to 0.2 cm2V-1s-1, attributed to suppression and decomposition of organic residues, as revealed from ellipsometry and x-ray photoelectron spectroscopy (XPS) measurements. At high flashing power, the electron mobility decreases which is associated with the formation of traps and hole doping in the films. According to XPS analysis, we find that some of Pb atoms are ablated from the films, responsible for hole doping and dangling bond formation at high flashing power. Finally, we operate the PbS CQD TFTs with top gate configuration using polymethyl methacrylate (PMMA) and high capacitance polymer dielectrics, with their good interface and superior trap filling, enabling us to obtain high electron mobility of 0.48 and >1 cm2V-1s-1, respectively. Our works show the great importance of photonic curing for the fabrication of high performance CQD TFTs, standing out as effective replacement of conventional thermal annealing, which is potentially applicable for other optoelectronic applications such as CQD photodetectors and solar cells.

15:15 - 15:30
A1-O2
Venkatraman, Vishwesh
Norwegian University of Science and Technology (NTNU)
Accelerated Design of Photovoltaic Dyes Using Materials Informatics
Venkatraman, Vishwesh
Norwegian University of Science and Technology (NTNU), NO
Authors
Vishwesh Venkatraman a, John de Mello a
Affiliations
a, Norwegian University of Science and Technology (NTNU), Insitutt for materialteknologi, Trondheim, 7491, NO
Abstract

The field of photovoltaics has seen significant developments in recent years. Among the available technologies, dye sensitised solar cells (DSSCs) have attracted considerable attention[1]. Here, the majority of the research efforts are centred on the dye sensitizer, since it influences many of the key electron transfer processes that impact photovoltaic performance. Designing new dyes requires various aspects (wide absorption in the visible region, high molar extinction coefficients, photochemical stability, stable oxide surface anchoring etc.) to be taken into account. The traditional routes adopted thus far involve the determination of relevant properties of a large number of potential candidates, via high-throughput experiments or computations[2]. This approach, however, is laborious and time-consuming.

 

With a view to streamline the design process, we have combined data-driven approaches with Darwin-inspired evolutionary algorithms[3,4,5]. While the former makes use of statistics and machine learning to provide on-demand property estimates, the latter optimises constituent fragments of the dye molecule in a synthetically tractable manner, leading to the design of dyes with given target properties[6]. In this presentation, we demonstrate how data-driven molecular engineering can be gainfully employed to accelerate materials discovery. We will also present other applications of the method for designing dye-based optical filters for low cost fluorescence detection.

15:30 - 15:45
A1-O3
Ishii, Ayumi
Toin University of Yokohama
Highly Efficient Near-Infrared Luminescence of Yb(III) doped Perovskite Thin Films for Light-Emitting Device Applications
Ishii, Ayumi
Toin University of Yokohama, JP
Authors
Ayumi Ishii a, Tsutomu Miyasaka a
Affiliations
a, Graduate School of Engineering, Toin University of Yokohama, Kurogane-cho 1614, Aoba-ku, Yokohama, 225-8503
Abstract

Near-infrared (NIR) light emitting diodes (LEDs) are useful in a wide range of applications including night-vision devices, optical communication, biomedical imaging and medical treatments. The NIR emitters like organic compounds and colloidal quantum dots (QDs) have been widely investigated. However, their less charge transport ability and luminescence efficiency limit the improvement of external quantum efficiency (EQE) in NIR LEDs, which is still far from practical application. As compared with QDs or organic semiconductor based LEDs, the film-based structure with high carrier mobility, such as lead halide perovskites, enhances radiative recombination by minimizing charge trapping losses, resulting in higher EQE value in LEDs. Lead halide perovskites also exhibit significant potential for applications in LEDs because of their high color purity and a narrow full-width at half-maximum (FWHM) over the entire visible light spectrum, as well as their low-cost solution processing without high temperature treatments, however, pure lead based perovskite LEDs only emit below 800 nm. In this report, we present a new approach for developing highly efficient NIR LEDs based on an energy transfer system composed of all inorganic perovskite (CsPbCl3) film as an energy donor and ytterbium ions (Yb3+) as an acceptor. The NIR emission of Yb ion at around 1000 nm is found to be sensitized by CsPbCl3 in a thin film structure with a photoluminescence quantum yield over 60%. The Yb3+:CsPbCl3 based LEDs also exhibit a bright electroluminescence around 1000 nm with the highest EQE (~6.0%) ever reported for NIR LEDs capable of emission beyond 900 nm, which was achieved by high carrier transporting ability and effective sensitized emission property in the solid-film structure.  

15:45 - 16:15
Coffee Break
16:15 - 16:30
A1-O4
Tanaka, Ellie
The University of Edinburgh
Strategies Towards Efficient and Cost-effective Dye-sensitized Solar Cells
Tanaka, Ellie
The University of Edinburgh, GB
Authors
Ellie Tanaka a, Hannes Michaels b, Marina Freitag b, Neil Robertson a
Affiliations
a, School of Chemistry, University of Edinburgh, West Mains Rd, Edinburgh, EH9 3FJ, GB
b, Uppsala University, Ångström Laboratory, Sweden, Lägerhyddsvägen, 1, Uppsala, SE
Abstract

Recent reports on dye-sensitized solar cells (DSSCs) under ambient light conditions [1][2] have reopened the path towards widespread indoor photovoltaics. DSSCs possess promising features such as solution-based fabrication, low-toxicity, colour-tunability and light-weight. However, challenges remain including the appropriate choice of the electrolyte or solid hole conductor. A 2015 report by Freitag et al.[3] proposes the use of a copper phenanthroline electrolyte towards the development of efficient liquid- and solid-state DSSCs. Their solid-state DSSCs are obtained by slow evaporation of the electrolyte in liquid-state cells.

Originating from the above work, we have studied the co-sensitization effect of two organic dyes in a copper bipyridyl electrolyte system.[4] A high-performing costly dye (XY1)[5] was co-adsorbed with a moderately-performing cheaper dye (5T)[6] to achieve similar (9.5% at 1 sun) or superior (10.2% at 0.1 sun) performance to the XY1 dye alone. This translates to a 1.4-fold increase in cost performance of the sensitizer. Photophysical measurements suggested that the co-sensitized devices (XY1+5T) have better dye coverage and exhibit longer electron lifetimes especially at lower light intensities. Further testing of XY1+5T under indoor fluorescent lighting revealed a power conversion efficiency (PCE) of 29% at 1000 lux, which is among the highest reported under similar conditions. We believe our findings revalue the co-sensitization method as a cost-reduction strategy for DSSCs. Proposals towards more practical DSSCs (e.g. solid-state) will also be discussed during the talk.

Session B1
Chair: Taiho PARK
14:30 - 14:55
B1-IS1
Arai, Ryota
RICOH Co. Ltd.,
Organic Energy-Harvesting Devices and Modules for Self-Sustainable Power Generation under Ambient Indoor Lighting Environments
Arai, Ryota
RICOH Co. Ltd.,

Ryota ARAI was born in Hiroshima, Japan in 1983. He got a master's degree from Kyushu University in 2008 under the supervision of Prof. Masahiro Irie and Kenji Matsuda . In 2008 he joined RICOH Co. Ltd., and engaged in development of Organc photoconductor materials and organic photovoltaic materials. Now, He is working for Ricoh and is completing a PhD at Kyushu University.

Authors
Ryota Arai a
Affiliations
a, RICOH Co. Ltd.,
Abstract

With the emergence of low-power electronic devices such as wireless sensor nodes, the Internet of Things (IoT) is rapidly developing and spreading. While the IoT has significant potential to benefit our lives, commerce, and industry, the use of large number of wireless or portable devices would need to be powered by distributed energy sources at the lowest possible cost, especially in regions that are limited to the range of a few milliwatts. However, conventional batteries, such as coin cells, require periodic replacement and maintenance, thus spurring the demand for emerging energy-harvesting systems that utilize ambient energy to semipermanently operate indoor electronic devices.

 Thus, various methodologies have been proposed for harvesting energy from local environments, including light, heat, movement/vibration, and electromagnetic waves. Of these technologies, photovoltaic (PV) energy conversion has shown great potential because of its higher energy density and output voltages. Thus, recent developments of PV devices not only target conventional solar cells under 1-sun illumination (i.e., 100 mW cm−2) but also dim-light indoor applications (with a factor 100–1000 lower incident power). As sunlight is not available always and at all locations, artificial indoor lighting sources, such as white light-emitting diodes (LEDs) and fluorescence lamps, can steadily supply small amounts of energy for powering sensors and electronic components inside buildings. Unlike the AM 1.5G solar spectrum, typical indoor illumination spectra are limited to the visible wavelength region, as they are optimized for the human eye. Here, eco-friendly organic photovoltaics (OPVs)9,10 serve to be a promising indoor energy-harvesting technology, which offer various inherent advantages such as lightweight, mechanical flexibility, solution processability, and cost-effective large-area manufacturing capability. Additionally, the characteristics of OPV materials such as a high absorption coefficient and a tunable absorption range are well suited for indoor applications when compared to robust inorganic silicon devices. Recently, some research groups, including us, have investigated whether OPVs can demonstrate indoor performance superior to that of silicon solar cells, and the results revealed that OPVs indeed show higher power conversion efficiencies (PCEs) under white LED lighting conditions. It is necessary to further optimize OPV materials and devices, and thereby improve their PCEs for future practical applications. Nevertheless, thus far, only a few OPV materials including representative semiconducting polymers and low-bandgap small molecules have been tested for their potential in terms of organic energy-harvesting devices; thus, a systematic study on indoor PV characteristics and mechanism is still lacking.

In this presentation, we propose some small-molecule based light absorbers and evaluate their OPV performances using a binary bulk-heterojunction (BHJ) system with fullerene acceptor under LED illumination with different illuminances (200–10000 lx). Furthermore, we demonstrated flexible energy-harvesting modules of ~10 cm2 under dimly lit conditions of 200 lx. Our research paves the way for practical indoor applications of solution-processed OPVs.

14:55 - 15:00
Discussion
15:00 - 15:15
B1-O1
Adilbekova, Begimai
KSC, KAUST
Aqueous ammonia-based exfoliation of two dimensional MoS2 and WS2 and their application in non-fullerene organic solar cells
Adilbekova, Begimai
KSC, KAUST, SA
Authors
Begimai Adilbekova a, Yuanbao Lin a, Emre Yengel a, Hendrik A. Faber a, George Harrison a, Yuliar Firdaus a, Vincent Tung a, Thomas D. Anthopoulos a
Affiliations
a, KSC, KAUST, Building 5, LFO34, KAUST, Thuwal, 23955, SA
Abstract

Recent advances in atomically thin two dimensional (2D) transition metal dichalcogenides (TMDs) have shown remarkable impacts in optoelectronic technologies which span from photodetectors, field-effect transistors, sensors, and solar cells. Several methods have been reported to synthesize atomically thin TMDs which include mechanical cleavage, chemical vapour deposition and liquid phase exfoliation (LPE). Amongst them, LPE is the most promising one since it serves as a comparably low-cost, fast and simple method, which results in high yield suspension of TMD nanosheets. LPE also enables film deposition by a solution-phase process for instance by printing or coating methods. Here we demonstrate the synthesis of MX2 nanosheets (WS2 and MoS2) using LPE in aqueous ammonia (NH3(aq)) and their application as hole transporting layer (HTL) in organic solar cells. By employing this technique, we are able to produce stable dispersion containing monolayer and multilayer  MX2 nanosheets with lateral sizes ranging between 10s-100s nanometers, for both MoS2 and WS2. The low boiling point of the NH3 and water makes them more favourable than the commonly used high boiling-point solvent such as N-Methyl-2-pyrrolidone (NMP) or N-Cyclohexyl-2-pyrrolidone (CHP). Hence no high-temperature post-deposition annealing is required. The successful exfoliation of TMDs is shown via atomic force microscopy (AFM), transmission electron microscopy (TEM) and Raman spectroscopy. The semiconducting nature of the MX2 nanosheets is revealed by X-ray photoelectron (XPS), UV-Vis and photoluminescence (PL) spectroscopies. Finally, we integrated the synthesized nanosheets in non-fullerene organic solar cells (NF-OSCs) as an HTL replacing the hygroscopic and acidic poly(3,4-ethylene dioxythiophene): poly(styrenesulfonate) (PEDOT: PSS). Ultraviolet photoelectron spectroscopy (UPS) shows that the work function of ITO increases upon deposition of TMDs. Consequently, the thin layer of MX2 can improve contact with the active layer and hole extraction. The photovoltaic measurements show that integration of the MX2-based HTLs in NF-OSCs can enhance the performance of the devices. PCE of the NF-OSC with WS2- and MoS2-based HTLs can be increased to 11.8% and 11.4%, respectively. These results are comparable to conventional PCE of PEDOT:PSS-based NF-OSCs. This study carries great importance of 2D MX2 for the performance enhancement of organic solar cells. Furthermore, the simplicity of the synthesis of MX2 by LPE in NH3(aq) and their deposition make the approach feasible to implement in broader applications.

 

15:15 - 15:30
B1-O2
Firdaus, Yuliar
King Abdullah University of Science and Technology (KAUST) - Saudi Arabia
Organic Tandem Solar Cells with 15% Efficiency Employing Novel Wide Bandgap Nonfullerene Acceptor
Firdaus, Yuliar
King Abdullah University of Science and Technology (KAUST) - Saudi Arabia, SA
Authors
Yuliar Firdaus a, Qiao He b, Yuanbao Lin a, Ferry Anggoro Ardy Nugroho c, Emre Yengel a, Ahmed H. Balawi a, Frederic Laquai a, Christoph Langhammer c, Feng Liu d, Martin Heeney b, Thomas D. Anthopoulos a
Affiliations
a, King Abdullah University of Science and Technology (KAUST) - Saudi Arabia, 4700 King Abdullah University of Science and Technology (KAUST), Thuwal, SA
b, Department of Chemistry and Centre for Plastic Electronics, Imperial College London, South Kensington Campus, London, GB
c, Chalmers University of Technology, Sweden, Fysikgränd, 3, Gothenburg, SE
d, Shanghai Jiao Tong University, CN
Abstract

Fabricating solar cells with tandem structure is an effective way for increasing the power conversion efficiency (PCE) beyond that of single-junction organic photovoltaics (OPV). To obtain high PCE of the tandem OPV, carefully engineered front-cell and back-cell are required. However, wide-bandgap materials for front cells that have both high short-circuit current density (JSC) and open-circuit voltage (VOC) are scarce. In this contribution, we developed and studied two new acceptor molecules namely IDTA and IDTTA with optical bandgaps (Egopt) of 1.90 and 1.75 eV, respectively. When blended with wide bandgap polymer PBDB-T, single-junction cells with PCE up to 7.4% for IDTA and 10.8% for IDTTA (with high VOC = 0.98 V, JSC = 15.8 mAcm-2, and FF = 70%) are demonstrated. The latter PCE value is the highest reported to date for wide-bandgap (Egopt ≥ 1.7 eV) OPVs. Our detailed transport and recombination studies show that the improved charge transport in IDTTA-based cells leads to higher fill-factor and improved charge generation than IDTA-based devices. Moreover, IDTTA-based OPVs show improved shelf lifetime and thermal stability. Nanoplasmonic spectroscopy analysis reveals that the PBDB-T:IDTTA layer exhibits significantly higher glass transition temperature, which could explain its superior thermal stability at 80°C. Finally, with the aid of optical-electrical device simulation, we were able to combine PBDB-T:IDTTA as the front-cell with PTB7-Th:IEICO-4F as the back-cell in tandem OPVs and demonstrate cells with PCE = 15%, open circuit voltage of 1.66 V and short circuit current of 13.6 mA/cm2; in good agreement with our theoretical predictions. These results highlight IDTTA as a promising acceptor for high performance tandem OPVs.

15:30 - 15:45
B1-O3
Perrin, Lara
Some Aspect of the Stability of Flexible Organic Solar Cells
Perrin, Lara
Authors
Emilie Planes a, Lara Perrin a, Manon Spalla a, Muriel Matheron b, Solenn Berson b, Lionel Flandin a
Affiliations
a, Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, Grenoble INP, LEPMI, France, Grenoble, FR
b, University Grenoble Alpes, CEA-LITEN, FR
Abstract

The stability of final setups is one of the prominent challenge for photovoltaic applications. There is thus a vital need for a better understanding of the degradation mechanisms and thereby the possible mitigation strategies. Flexible organic photovoltaic (OPV) modules are commonly encapsulated by two gas-barrier films to prevent moisture and oxygen degradations. Although this encapsulation process can significantly be diversified, its effect on both initial and in-use performances are scarcely described in the literature. In addition, several on-site studies showed that the mechanical degradation could be more critical on optoelectronic effects than the photo-chemical counterpart. It seems that the stability of the overall complex device architecture may be altered according to several very dissimilar mechanisms: 1- within the active components, 2- at the layers’ interfaces and 3- from the external envelop. Presented work focuses on the last two scales using different ageing conditions (in inert atmosphere, and in severe 85°C/85%RH conditions). For this purpose, two variants in the encapsulation process are compared: the roll-to-roll lamination of a pressure sensitive adhesive and the vacuum lamination of a hot-melt thermoplastic.

The adhesion between the different layers within the device is a key factor for the development of flexible OPV devices reliable after all the processing steps, and during in-use. We here propose a way to individually quantify the adhesion strength of each interface in samples. The 180° peeling test mechanical characterization was adapted for and then applied to the flexible devices. In addition, non-destructive imaging characterization techniques were developed: the laser-beam induced-current mapping, and the luminescence emission imaging under optical and electrical excitation. These latter techniques largely confirmed the hypothesis of a mechanical degradation during the roll-to-roll lamination process.

All these investigations revealed two weak interfaces and several methods have been tested to try and enhance them. We show that improving these interfaces directly increases both the overall performance of the device, and its resilience to roll-to roll encapsulation. Using the imaging techniques previously developed, we will finally study the stability of the encapsulated OPV devices during accelerating aging tests in inert atmosphere at 85°C and 85°C/85%RH. An occurring aging mechanism was proposed, which allows one to explain the localization of the degradation but also the failure type, either optical or electrical.

15:45 - 16:15
Coffee Break
16:15 - 16:30
B1-O4
Pant, Namrata
University of Yamanashi
Investigating the Effect of Nickel Oxide on the Crystallisation, Optoelectronic Properties and Performance of Perovskite Solar Cells
Pant, Namrata
University of Yamanashi
Authors
Namrata Pant a, Masatoshi Yanagida b, Yasuhiro Shirai b, Kenjiro Miyano b
Affiliations
a, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi
b, Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
Abstract

Nickel oxide (NiOx) has stood out as an excellent hole transporting material (HTM) for perovskite solar cell (PSCs). Its high optical transmittance, and matching valence band energy level, along with the high stability in ambient atmosphere, gives NiOx an edge over the other popularly used HTM’s for PSCs. Despite these advantages, the power conversion efficiency (PCE) values for NiOx HTM based devices lag significantly behind the high performing cells based on organic HTMs such as spiro-OMeTAD, and PTAA. Amongst the various factors, affecting the device performance, one of the major influence comes from the nature of substrate, which plays an influential role in governing the interfacial properties of the device as well as the bulk properties of the perovskite films. 

In the current study, we attempt to understand the possible reasons for low efficiency of sputtered NiOx based PSCs, by investigating how the NiOx under layer is directly affecting the growth and crystallisation of compositionally engineered perovskite film and study its correlation with the perovskite optoelectronic properties and device performance. In addition to varying perovskite composition, we also employed different deposition conditions to probe the relation between the crystal growth and charge carrier dynamics at the perovskite/NiOx interface. This work further emphasizes on the importance of specific deposition conditions and compositionally designed perovskite that are suitable for enhancing the efficiency of sputtered NiOx based perovskite solar cells. A deep insights into direct correlation of different deposition conditions, and growth mechanism of perovskite with device long term stability against ambient atmosphere (~50-60% humidity) and continuous light illumination will also be covered.

16:30 - 16:45
B1-O5
Ma, Teng
Tohoku University
Boosting the performance of back-contact perovskite solar cells by enlarging crystal size
Ma, Teng
Tohoku University, JP
Authors
Teng Ma a, Ayumi Hirano-Iwata a
Affiliations
a, Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai 980-8577, Japan
Abstract

  Organometal halide perovskite materials have emerged as the strong candidates for the next generation photovoltaic materials. The power conversion efficiency (PCE) of perovskite solar cells (PSCs) has reached 25.2%, which is the highest efficiency in thin-film photovoltaics.[1] To further boost the PCE of PSCs, we previously proposed that the replacing the widely-used sandwich structure with a new back-contact structure would lead to PSCs with higher efficiency, lower cost, and better compatibility for upscaling.[2] However, since the distance between two electrodes is longer in back-contact structure than that in the traditional sandwich structure, the performance of back-contact PSCs is significantly affected by the grain boundaries in the charge transporting path.

  Here, we report that the performance of back-contact PSCs can be boosted by forming high-quality perovskite films with large crystal size on the back-contact substrates. The results of photoluminescence microscopy explicitly demonstrate that the charge collecting efficiency is largely improved when the crystal size is close to or larger than the distance between two adjacent electrodes. I will discuss the film-formation method and the performance of the devices in the presentation.

16:45 - 17:00
B1-O6
Kuan, Chun-Hsiao
National Taiwan University of Science and Technology
A Practicable Way Combining Advantages Of Thermal Evaporation And Solution Process To Control Reaction Of MAPbI3 To Fabricate High Crystallization Perovskite
Kuan, Chun-Hsiao
National Taiwan University of Science and Technology, TW
Authors
Chun-Hsiao Kuan a, Ching-Fuh Lin a
Affiliations
a, National Taiwan University, Graduate Institute of Photonics and Optoelectronics, Taipei, No. 1, Section 4, Roosevelt Road, 10617, Taipei, TW
Abstract

Introduction

There are two methods fabricating the perovskite solar cells. In general, solution process that adds anti-solvent to spin coating solution MAPbI3 is easy to use. The process of solution shows low cost, but is difficult to control. The whole device manufacturing leads to low error tolerance. Another method of perovskite is thermal evaporation, which makes mass production possible and has high error tolerance, but it requires more time to fabricate and needs more cost.

Fabrication

Combining the advantages of thermal evaporation and solution process is the new method which has been created by our laboratory, called sandwich evaporation technique (SET).

PEDOT:PSS was spin-coated on ITO conductive glass. Then MAI/DMF solution was prepared and spin-coated on ITO substrates coated with PEDOT:PSS. Then PbI2 was evaporated and MAI powder was evaporated in low pressure chamber to complete the active layer. Finally, PC60BM was spin-coated as the electron transport layer. Then BCP was evaporated as the surface modification layer and Ag electrode respectively.

Results and discussions

Based on the above steps, we found that crystallization of perovskite improved when kept in low vacancy lower than 0.13 Pa. In order to further improve the quality, the process was applied to SET process to slow down the reaction rate.

As shown in the SEM (Scanning Electron Microscope), we compared the cross-section of devices that just finished and have been controlled at 0.13Pa for several days. The cross-section of the perovskite that has just been fabricated in Fig. (a) is not flat. The Electron-hole pairs will recombine in the crevice, which seriously affects the performance of device. The crystalline grain shown in fig. (b) after several days of preserving under low vacancy has relatively better flatness. The unreacted perovskite in the evaporation process can continue to finish completely, and the sandwich structure in MAI-PBI2-MAI further promoted the full progress of the reaction. Finally, the highly quality perovskite solar cells were formed.

The PL (Photoluminescence Spectroscopy) of perovskite which fabricated with SET also first increased for several days and reached a maximum intensity when kept at low vacancy for several days.

CH3NH3Iaq.⇋CH3NH2aq.+HIaq.

4HIaq.+O2⇋I2s+H2Oaq.

2HIaq.⇋H2g+I2s

 

The intensity of X-ray we measured was increased from 1st day to 7th day and we got the maximum X-ray pattern and 7th day.

The absorption of our samples had the same phenomenon. And the increasing absorption, explained that the improvement of the short current Jsc. Hence we got the highest Jsc , 23.66 mA/cm2 at 7th day.

Conclusion

The MAPbI3 formed with MAI-PbI2-MAI was successfully applied to the SET process. MAPbI3 film first Further optimized the crystalline by controlling at low-pressure. The continuous and uniform perovskite layer have good performance for the 0.91V of Voc, 23.66 mA/cm2 of Jsc, 76.4% of fill factor, and 16.51% of efficiency. We believe that the SET process shows the great potential and has universal use in any of ABX3 perovskite solar cells’ fabrication.

Session C1
Chair: Tze-Chien Sum
14:30 - 14:55
C1-IS1
Mori, Shigehiko
Toshiba Corporation
Film-Based Large-area Perovskite Photovoltaic Module Development
Mori, Shigehiko
Toshiba Corporation, JP

Shigehiko Mori belongs to Toshiba Corporate Research & Development Center. He finished the doctoral program without a doctoral degree of Nihon University in 2008. He joined Toshiba Corporate Research & Development Center in 2008 and engaged in the development and research of plasmonic waveguide and near-field photolithography from 2008 to 2011. Then he engaged in the development and research of organic photovoltaics from 2011 to 2015. From 2015 to present, his work focuses on the development and research of perovskite solar cells. His current research interests are perovskite solar cells, film-based optoelectronic devices.

Authors
Shigehiko Mori a, Haruhi Ohka a, Hideyuki Nakao a, Akio Amano a, Kenji Todori a
Affiliations
a, Corporate Research & Development Center, Toshiba Corporation
Abstract

Perovskite solar cells (PSCs) are one of the most promising future solar cell candidates because they show high power conversion efficiencies (PCEs) approaching those of silicon- and compound-semiconductor based solar cells. Moreover, PSCs can be produced by a low-temperature processing and coating method, so they can be fabricated on flexible substrates such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) films. This capability would make roll-to-roll processes possible, meaning that PSCs can potentially realize low-cost, flexible, lightweight, and large-area perovskite photovoltaic (PPV) modules that can be installed on roofs with low load-bearing capacity, curved surfaces, walls, and windows. However, perovskite films generally exhibit low reproducibility, and it is difficult to fabricate large, pinhole-free homogeneous perovskite films. It is therefore crucial to establish fabrication processes that realize both large and highly efficient perovskite PPV modules.

In order to fabricate uniform layers with low thickness fluctuation over a large area, we have been developing the “meniscus coating method” [1, 2]. The perovskite photoactive layer and buffer layers of the film-based PPV modules were fabricated by this coating method. It is difficult to achieve low electrical resistance between adjacent cells in organic film-based solar modules fabricated using mechanical scribing, because organic film substrates are so soft that the mechanical scribing blades can easily damage them. To address this issue, we thoroughly investigated low-pressure mechanical scribing conditions, and successfully removed the layers on an ITO electrode without damaging either the ITO electrode or the PEN film substrate. Additionally, we replaced the amorphous ITO with crystallized ITO to reduce series resistance by changing the indium-to-tin ratio.

Using the above-described meniscus coating method and experimental results, we achieved a PCE of 11.7% in a film-based PPV module with a designated area of 703 cm2, as measured by the National Institute of Advanced Industrial Science and Technology (AIST). This result is described in the “solar cell efficiency tables (version 54)” [3].

14:55 - 15:00
Discussion
15:00 - 15:15
C1-O4
RAPTIS, DIMITRIOS
College of Engineering, Swansea University, UK
Enhancing Fully Printable Mesoscopic Perovskite Solar Cells Performance by Increasing Carbon Electrode Conductivity with the Use of Metallic Grids.
RAPTIS, DIMITRIOS
College of Engineering, Swansea University, UK, GB
Authors
DIMITRIOS RAPTIS a, VASIL STOITCHKOV a, SIMONE MERONI a, CARYS WORSLEY a, ADAM POCKET a, DAVE WORSLEY a, MATTHIEW CARNIE a, TRYSTAN WATSON a
Affiliations
a, College of Engineering, Swansea University, UK, Bay Campus, Swansea SA1 8EN, GB
Abstract

Carbon based Perovskite Solar cells (C-PSCs) have emerged in recent years as the most promising candidates for commercialisation in perovskite photovoltaics. Constructed by screen-printing mesoporous Titania, Zirconia and Carbon and subsequent perovskite infiltration, these devices are highly stable, low cost and make use of easily scaled manufacturing techniques. However, while the lack of an expensive hole transport material decreases device cost and enhances stability, the limited conductivity of carbon electrodes also inhibits performance and represents a significant barrier to commercial application.

This work presents a method for electrode conductivity enhancement through the application of Aluminium and Copper grids to prefabricated C-PSCs. Adhered to cells using a low temperature carbon ink, metallic grids were found to dramatically reduce electrode series resistance, leading to a large improvement in Fill Factor and efficiency enhancement of up to 23.3 % in 1 cm2 devices. Average power conversion efficiencies (PCEs) of 13.15 ± 0.12 % and 12.83 ± 0.06 % were obtained for Copper and Aluminium respectively, up from ~11 % pre-application. Performance is also significantly augmented in the case of larger-scale 11.7 cm2 modules, where PCEs went from 7.73 % to 9.97 % and 7.70 % to 11.05 % for Aluminium and Copper grids respectively. 

Grid structures are easily applied as the mesh structure allows ink permeation and hence top down deposition. The resultant bilateral coverage protects the grid and imparts mechanical stability without damaging the underlying layer. This technique offers a fast, cheap and low temperature route to high-performance, large-scale stable C-PSCs and could therefore have serious potential for application to the high-volume manufacture of large-scale perovskite devices.

15:15 - 15:30
C1-O5
MA, Tingli
Interfacial engineering for carbon-based perovskite solar cells
MA, Tingli
Authors
Fanning MENG a, Zhu Zhang c, Tingli MA b, c
Affiliations
a, Dalian University of Technology (DUT), Dalian 116024
b, Kyushu Institute of Technology, Japan, 204 Hibikino Wakamatsu-ku, Kitakyushu - Fukuoka, 808, JP
c, China Jilliang University
Abstract

Perovskite solar cells based on carbon materials as the back electrode (C-PSCs) have attracted significant attention due to their low cost and excellent stability. In general, the device structure of based C-PSCs has two types, one is hole transport layer (HTL)-free and another one is with hole transport layer. For these two cases, the carbon paste electrodes (CPEs) both need directly collect the photo-generated holes or/and transport the holes. Therefore, the interfacial engineering between the perovskite layer and carbon electrode layer plays a crucial role in charge collection and affects the performance of C-PSCs. 

    Our group have been carried out the interfacial engineering between carbon layer and perovskite layer using several methods to improve the performance of the C-PSCs. In this paper, we will report our recent results, including development a simple process for fabricating an effective sandwich structured perovskite solar cell based on the carbon material and doing the interfacial engineering between the perovskite layer and carbon electrode layer for perovskite solar cells.

15:30 - 15:45
C1-O6
Ishikawa, Ryo
Saitama University
Fabrication of perovskite thin-film solar cells with fluorinated passivation layer using a simple one-step spin-coating method without an antisolvent.
Ishikawa, Ryo
Saitama University, JP
Authors
Ryo Ishikawa a, Yuma Moriya a, Keiji Ueno a, Hajime Shirai a
Affiliations
a, Saitama University, 255 Shimo-Okubo, Sakura, Saitama, 338, JP
Abstract

Perovskite solar cells (PSCs) using organic-inorganic halides as a light-absorbing layer exhibit high power conversion efficiencies (PCEs; 25.2%) in small-area solar cells [1]. The film quality dramatically affects the performance of PSCs and depends on the fine structure of the perovskite layers, including the crystallinity, surface coverage, and roughness. Varied fabrication methods have been employed including a one-step and, a sequential two-step process which can be either solution or vacuum processed for perovskite thin-film preparation [2]. Currently, mainly one-step spin-coating with an antisolvent is used to precipitate perovskite thin films. This method can fabricate relatively uniform and compact perovskite layers that lead to significantly increased PCEs of the PSCs [3,4], but this method requires technical skill, and a large volume of antisolvent such as toluene and chlorobenzene have an enormous environmental impact. In this conference, we report the fabrication of methylammonium-free FA+ and Cs+ mixed cation perovskite thin films with micrometer-sized grains using a simple one-step spin-coating method with the use of two additives and without an antisolvent [5,6].

 Furthermore, this organic-inorganic perovskite thin films were treated with a fluorinated ammonium iodide solution, and the thin fluorinated two-dimensional layer was formed on the surface, resulting in a significant improvement in photoluminescence intensity. When applied to PSCs, untreated PSCs exhibited PCEs of 18.6% and 17.0% during the reverse and forward scanning, respectively. The PSCs treated with the optimal concentration of fluorinated ammonium iodide showed improved open-circuit voltage, fill factor, and PCEs of 20.6% and 18.5% during reverse and forward scanning, respectively.

 Also, we report the fabrication of perovskite thin films with a fluorinated polymer (FP) additive via a one-step spin coating method for improving the perovskite-layer passivation quality and the crystalline-phase grain boundary. Here, the FP self-organizes and forms a very thin overlayer atop the perovskite layer surface during film formation upon using an FP-added precursor solvent, which suppresses the surface roughness (measured as the RMS value) of the perovskite layer. Further, the PCE increases from 17.2% for FP-free PSCs (control) to 19.1% for FP-added PSCs operating in the reverse scan (RS) mode due to the enhanced interfacial passivation capability upon addition of the surface-segregated FP.

15:45 - 16:15
Coffee Break
16:15 - 16:30
C1-O3
Kogo, Atsushi
National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba
Composition tuning of organic-inorganic perovskite crystals by post-treatment for high efficiency solar cells
Kogo, Atsushi
National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, JP
Authors
Atsushi Kogo a, Tetsuhiko Miyadera a, Masayuki Chikamatsu a
Affiliations
a, Research Center for Photovoltaics (RCPV), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan, JP
Abstract

Recently, solution-processable organolead halide perovskite materials have been attracting great interest as a cost-effective and high performance light-harvesting material of solar cells. Since perovskite crystals are formed by coating and drying process of precursor solutions, control of crystal growth has been important issue for high power conversion efficiency (PCE). Recently, it is reported that ratio of PbI2 and methylammonium iodide (MAI) in precursor solutions has great influence on perovskite crystal formation. Excess amount of PbI2 contained in a precursor solution promotes crystal growth of perovskite and yields the layer of high crystallinity, which gives high PCE of solar cells.[1] On the other hand, excess amount of MAI in precursor solutions yields perovskites with less trap density.[2] To obtain perovskites with high crystallinity and low trap density, in this study, we performed post-treatment with MAI solution to highly crystalline perovskite crystals formed from a PbI2-rich precursor solution. As a result, high PCE up to 20.7% was achieved.

   Perovskite layers was fabricated from a precursor solution containing 10 mol% excess PbI2. To the perovskite layers (PbI2-rich perovskite), MAI solution was spin-coated, and the substrates was annealed at 100 oC. Diffraction peak of PbI2 was observed in X-ray diffraction pattern of perovskite without the MAI treatment. When the perovskite was treated with 10 mM MAI solution, the PbI2 peak disappeared. This indicates that in the perovskite treated with >10 mM MAI solutions, PbI2 was removed and excess MAI was incorporated.

  Photovoltaic performance of perovskites with and without the MAI treatment was compared. The perovskites without MAI treatment exhibits PCE at 19.2%. Even when perovskite was treated with 10 mM MAI solution and PbI2 was removed, the PCE was same. However, by >10 mM MAI solution treatment, PCE increased up to 20.7%. This indicates that excess amount of MAI in perovskite layer is important for high PCE. Dark current analysis shows that trap density was drastically decreased in >10 mM MAI-treated perovskite. We conclude that PCE was improved due to decrease in perovskite trap density based on tuning MAI content by post-treatment.

16:30 - 16:45
C1-O2
Murdey, Richard
Kyoto University, Japan
Light Intensity Dependence Study of Mixed-composition Perovskite Solar Cells
Murdey, Richard
Kyoto University, Japan, JP
Authors
Richard Murdey a, Minh Anh Truong a, Kento Otsuka a, Ruito Hashimoto a, Tomoya Nakamura a, Atsushi Wakamiya a
Affiliations
a, Kyoto University, Japan, Goryo-Ohara, Nishikyo-ku, Kyoto 615-8245, JP
Abstract

  Metal-halide perovskites are exciting materials for solar cell applications due to their high photogeneration efficiencies and ease of fabrication.  The stability of perovskite solar cells, however, is poor – particularly under full sunlight and harsh outdoor conditions.  Ambient light energy harvesting in indoor environments, where stability concerns are less acute, is therefore an attractive near term application for emerging perovskite technologies.  Not all solar cells operate efficiently in low light, however, so in this study we set out to examine the properties and performance of our highly efficient mixed-composition Cs0.05FA0.80MA0.15PbI2.75Br0.25 perovskite devices1 as a function of light intensity.

  A typical cell was found to retain about 25% of the maximum efficiency down to the lowest measured light intensities of 0.03 mW/cm2 (1/3000th of full sunlight, or 30 Lux).  The maximum efficiency is observed at 10 mW/cm2 (1/10th of full sunlight, 10 000 Lux).  In addition to current-voltage analysis, impedance spectroscopy was employed to investigate the underlying mechanisms governing the change in cell performance.  The parallel resistance, r­­p, resolved by the impedance measurements, is compiled as a function of applied bias voltage and incident light intensity.   While usefully high at ambient light levels, the parallel resistance falls dramatically in stronger light, particularly at moderate voltages, resulting in significant loss of fill factor.  The FF loss is shown to be the primary cause of the reduction in cell efficiency above 10 mW/cm2.  These results can be comprehensively explained by introducing a field-dependent photocurrent into the standard equivalent circuit, and is accurately modelled using the constant-field approximation developed previously for amorphous Si photodiodes.2,3

16:45 - 17:00
C1-O1
Tumen-Ulzii, Ganbaatar
OPERA, Kyushu University
Detrimental Effect of Excess PbI2 on the Stability of Perovskite Solar Cells
Tumen-Ulzii, Ganbaatar
OPERA, Kyushu University, JP

Ph.D student. Working on Perovskite solar cells.

Authors
Ganbaatar Tumen-Ulzii a, b, Chuanjiang Qin a, b, Toshinori Matsushima a, b, c, Chihaya Adachi a, b, c
Affiliations
a, OPERA, Kyushu University, JP
b, Japan Science and Technology Agency (JST), ERATO, Adachi Molecular Exciton Engineering Project
c, Kyushu University, International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Japan, 744 Motooka, Nishi, Fukuoka, JP
Abstract

 

Abstract

 

Organic-inorganic lead halide perovskite solar cells (PSCs) are one of the most promising technologies for solar energy harvesting. The record power conversion efficiency (PCE) of PSCs has now reached 25.2%. Excess/unreacted lead iodide (PbI2) crystals are often seen in perovskite films, and are believed to increase PCEs of PSCs because of passivating the trap states. Nevertheless, how PbI2 crystals affect long-term stability of PSCs under continuous light irradiation has been rarely studied. Therefore, the clarification of basic degradation mechanisms related to unreacted PbI2 is important for improving the stability of PSCs. Here, we show that unreacted PbI2 crystals are one of the main reasons for degradation of PSCs. Under continuous illumination of light, unreacted PbI2 undergone the photo-decomposition by forming metallic Pb. Indeed, the degradation of PSCs was accelerated by metallic Pb. By carefully reducing the amount of the unreacted PbI2, the stability of PSCs is greatly improved; almost no degradation of PCEs was observed even after 500 hours of continuous illumination with maximum power point tracking.

  


 

  

17:05 - 18:45
Poster Session
19:30 - 22:00
Social dinner
 
Wed Jan 22 2020
08:55 - 09:00
Announcement of the day
Session G3
Chair: Hideo Ohkita
09:00 - 09:35
G3-K1
Hayase, Shuzi
Perovskite solar cells with wide band gap and narrow band gap
Hayase, Shuzi
Authors
Shuzi Hayase a
Affiliations
a, i-Powered Energy System Reserach Center, The University of Electro-Communications, JP
Abstract

 

The efficiency of Pb-perovskite solar cells with more than 1 cm2 is 20.9 % which became close to those of inorganic multi-crystalline solar cells such as MC-Si, CIGS, and CdTe. In small cells with less than 1cm2, the efficiency of 25.2% has just been reported for the perovskite solar cells.

 

Conventional perovskite solar cells consisting of Pb have band gap of 1.5-1.6 eV and can harvest the light in the visible region up to 850nm.  According to Shockley-Queisser limit, light harvesting layer with 1.2-1.4 eV band gap gives the highest efficiency. Mixed metal PbSn perovskite materials have a narrow band gap of around 1.2 eV.  Therefore, mixed metal SnPb perovskite solar cell is expected to give higher efficiency than Pb-perovskite solar cells.  In addition, the narrow band gap solar cell is useful for bottom cells for all perovskite tandem solar cells. When SnPb mixed metal perovskite solar cells was firstly reported by us, the efficiency was around 4%. However, the efficiency has been enhanced gradually and recently efficiency higher than 20% has been reported by several groups including our Lab.  How the efficiency was enhanced will be discussed in the presentation1-4.

 

  The conventional perovskite layer consists of Pb ions. The use of Pb ions is limited by the law such as RoHS directive in Europe.  From this view point, there is a strong request for Pb-free perovskite solar cells solar cells. Bismuth halide compounds such as Cs3Bi2I9, MA3Bi2I9 Ag3BiI6, AgBi2I7, Cs2AgBiBr6, antimony halide compounds such as Rb3Sb2I9, titanium halide compounds such as Cs2TiBr6, and copper halide compounds such as MA2CuI4 have been reported to replace lead. However, the solar cell efficiency based on these materials were less than 5% and was not satisfactory.  Among all lead-free perovskite materials, Sn-based perovskite is one of the most promising candidates as the light harvesting layer for Pb-free PSCs, because they have perovskite structure similar to Pb perovskite.  In addition, the band gap is narrow (1.4eV). The efficiency has been enhanced to 10% by several research groups including us, however, the efficiency is not still satisfactory, when compared with Pb-perovskite. The cause of the low efficiency and how the efficiency will be enhanced is discussed5-7.

 

  Perovskite solar cells with wide gap of 1.7-1.8 eV are needed for making tandem cells consisting of SnPb perovskite solar cells as the bottom layer. CsPbI2Br is one of the candidates for the top perovskite layers. However, the efficiency was not satisfactory because of large Voc losses.  We will report CsPbI2Br solar cells with 1.34V (Voc) and 14% efficiency.  We discuss how Voc loss is decreased to enhance the efficiency8,9.

 

 

 

 

 

 

09:35 - 09:45
Discussion
09:45 - 10:10
G3-O1
Negami, Takayuki
Panasonic Corporation
PEROVSKITE PHTOVOLTAIC MODULES FABRICATED by INK JET PRINTING
Negami, Takayuki
Panasonic Corporation, JP
Authors
Takayuki Negami a, Hiroshi Higuchi a, Takashi Nishihara a, Ryusuke Uchida a, Teruaki Yamamoto a, Taisuke Matsui a, Yukihiro Kaneko a
Affiliations
a, Panasonic Corporation, 1006 Kadoma, Kadoma, Osaka 571-8501, JP
Abstract

Perovskite solar cells have achieved a high efficiency over 25% in spite of solution based processes. The production cost of perovskite PV modules is expected to drastically decrease by the solution based processes with a low temperature annealing under atmospheric. In order to produce large area modules with a high efficiency and low cost, it is necessary to prepare highly uniform perovskite films with a high printing speed. We have selected an ink jet printing method from several large area coating methods because ink droplets controlled accurately from a lot of nozzles can form highly uniform thickness of films with a high-speed printing. We have investigated the uniformity of the cell performance in-plane. Precursors of the perovskite films were prepared by coating the solution containing CsI, MAI, FAI and PbI2 using the ink jet printing on 17 substrates of a structure of glass/TCO/c-TiO2/mp-TiO2 with a 2.5 x 2.5 cm2 size located randomly on a 30 x 30 cm2 area. The ink jet printing method can coat the films only on each substrate by drawing patterns. Toluene as an anti-solvent was quickly dropped onto each precursor during the substrate spun. The films were then dried to form the perovskite layers. PTAA films as a HTM prepared by spin coating on the perovskite films. Au films as a back electrode were deposited by vacuum evaporation. 66 cells with an aperture area of 0.1cm2 on 17 substrates showed an average efficiency of 19.4% with a distribution of plus minus 1.7%. High efficiencies and high uniformity in plane of 30 x 30 cm2 area have achieved by the ink jet printing. These results show that the ink jet printing is suitable to produce the large area perovskite modules with a high efficiency. We have also fabricated 30 x 30 cm2 sized modules by the ink jet printing. The performance of the modules will be described in detail at the conference.

10:10 - 10:15
Discussion
10:15 - 10:45
Coffee Break
Session G4
Chair: Shuzi Hayase
10:45 - 11:10
G4-I1
Loi, Maria Antonietta
University of Groningen, The Netherlands
Highly performing tin-based perovskite solar cells: a focus on the thin film quality
Loi, Maria Antonietta
University of Groningen, The Netherlands, NL

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

Authors
Maria Antonietta Loi a
Affiliations
a, University of Groningen, The Netherlands, Nijenborgh, 4, Groningen, NL
Abstract

Organic lead halide perovskite based solar cells (HPSCs) have achieved certified power conversion efficiency (PCE) over 25.0%. Despite the high efficiency achieved, there are still many concerns about the large-scale applicability of these solar cells because of their Pb2+ content. The simpler approach to address this issue is to find a benign or less toxic metal to replace the lead atom in the perovskite structure, obtaining a perovskite displaying similar excellent optical and electrical properties as the Pb-based compounds.

Tin based perovskite holds the promise to give rise to similar or even higher PCE compared to their Pb counterpart. However, for relatively long time the tin-based HPSCs held a PCE lower than 7% though intensive research efforts were devoted to their investigation. The facile formation of tin vacancies and easy oxidation of Sn2+ have been identified as the main reason determining the low PCE.

In my presentation I will report as a small amount of 2D tin perovskite templates the growth of highly crystalline and oriented 3D FASnI3 grains (2D/3D mixtures), suppressing effectively the appearance of tin vacancies and Sn2+ oxidation. [[1]] As a consequence of the reduced background charge carrier density and trap assisted charge recombination, the device showed a 50% improvement in the PCE (up to 9%) compared to that using pure 3D tin perovskite. We further succeeded reducing the defects in the 2D/3D tin perovskite films by adding ethylammonium iodide (EAI) into the corresponding perovskite precursor solution even starting from precursors of limited purity [2]. These films display larger crystalline grains and a more compact and uniform film morphology when compared to their counterparts without EA cation. These features lead to a much lower trap density, background charge carrier density and charge recombination loss in the corresponding devices. Results, which allow hopping for future highly efficient Sn-based hybrid perovskite solar cells.


 

 

11:10 - 11:15
Discussion
11:15 - 11:40
G4-I2
Diau, Eric Wei-Guang
National Chiao Tung University Hsinchu, Taiwan
Lead-free Perovskites for Applications of Photovoltaics and Photocatalysis
Diau, Eric Wei-Guang
National Chiao Tung University Hsinchu, Taiwan, TW

Eric Wei-Guang Diau received his Ph.D. in Physical Chemistry from National Tsing Hua University, Taiwan, in 1991. Before joining at Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan, as a faculty member since 2001, he worked as a postdoctoral fellow at Emory University (1993-1995), University of Queensland (1995-1996), Stanford Research Institute, International (1996-1997) and California Institute of Technology (1997-2001).  He is interested on studying relaxation kinetics in condensed matters, in particular interfacial electron transfer and energy transfer dynamics in many solar energy conversion systems. His current research is focusing on the developments of novel functional materials for next-generation solar cells, including perovskite solar cells (PSC). He received “Outstanding Research Award” from MRS Spring Meeting & Exhibit on April, 2014 and “Sun Yat Sen Academic Award” from Sun Yat Sen Academic and Cultural Foundation on October, 2014. He has published over 180 peer-reviewed papers with H-index 51. He has been granted over 14 patents. He is currently Distinguished Professor at Department of Applied Chemistry and Science of Molecular Science, National Chiao Tung University.

Authors
Eric Wei-Guang Diau a
Affiliations
a, National Chiao Tung University Hsinchu, Taiwan, 1001 University Road, Hsinchu, Hsinchu, TW
Abstract

My talk in this section can be divided into two parts. First, we investigated the doping effect of bulky organic cations with ethylenediammonium diiodide (EDAI2) as a co-additive to enhance the performance and stability of the FASnI3 perovskite solar cells.[1] The additive EDAI2 plays a key role to cause slow passivation of the surface and relaxation of crystal strain such that the device performance increases gradually with increasing duration of storage. In the presence of EDAI2 additive (1 %) the FASnI3 device attained the best initial efficiency 7.4 % and the device performance continuously increased as a function of duration of storage; the maximum PCE, 8.9 %, was obtained for a device stored in a glove box for over 1400 h with only slight degradation for storage beyond 2000 h. I will report hybrid tin-based perovskite solar cells that incorporate a non-polar organic cation, guanidinium (GA+), in varied proportions into FASnI3 crystal structure in the presence of 1 % EDAI2.[2] The device performance was optimized at precursor ratio GAI:FAI = 20:80 to attain PCE 8.5 % when prepared freshly; the efficiencies continuously increased to attain a record PCE 9.6 % after storage for 2000 h, which is a world record at the time the paper was published.[3] For photocatalysis, we report a new series of bismuth-based perovskite nanocrystals (PeNCs) as effective photocatalysts for CO2 reduction to produce methane and carbon monoxide with great performance by gas-solid reaction. Detailed studies have been performed by using electron paramagnetic resonance (EPR) and Diffuse Reflection Infrared Fourier Transfer (DRIFT) spectral techniques to propose the plausible mechanism for CO and CH4 formation via CO2 photoreduction by Bi-based PeNC photocatalysts.

Reference:

[1] E. Jokar, C.-H. Chien, A. Fathi, M. Rameez, Y.-H. Chang and E. W.-G. Diau,* Energy Environ. Sci., 2018, 11, 2353-2362

[2] E. Jokar, C.-H. Chien, C.-M. Tsai, A. Fathi and E. W.-G. Diau,* Adv. Mater., 2019, 19, 1804835

[3] E. W.-G. Diau,* E. Jokar and M. Rameez, ACS Energy Lett., 2019, 4, 1930-1937

11:40 - 11:45
Discussion
11:45 - 12:10
G4-I3
Jeangros, Quentin
Ecole Polytechnique Federale de Lausanne (EPFL)
A nanometric view on performance-loss mechanisms in perovskite/c-Si multi-junction solar cells
Jeangros, Quentin
Ecole Polytechnique Federale de Lausanne (EPFL), CH

Dr. Quentin Jeangros received a PhD in Materials Science from EPFL in 2014 for his work on solid oxide fuel cells degradation pathways. After a postdoc between the University of Basel and the Photovoltaics and Thin Film Electronics Laboratory (PV-Lab) of EPFL on transparent conductive oxides, Quentin has overseen the "Perovskite Cells for Tandem Applications" activities at EPFL PV-Lab since early 2018. Within the laboratory headed by Prof. C. Ballif, his team consists of 6 PhD students and postdocs dedicated to the development of high-efficiency perovskite/silicon solar cells. His research activities focus on the use and development of advanced electron microscopy characterisation methods to understand and optimise the nanostructure of solar materials materials, with the aim of improving efficiency and reliability.

Authors
Quentin Jeangros a, Florent Sahli a, Peter Fiala a, Ricardo A.Z. Razera b, Daniel A. Jacobs a, Fan Fu c, Terry C.-J. Yang d, Quentin Guesnay a, Xin Yu Chin a, Vincent Paratte a, Gizem Nogay e, Brett A. Kamino e, Saeid Rafizadeh e, Arnaud Walter e, Soo-Jin Moon e, Adriana Paracchino e, Marion Dussouillez e, Laura Ding e, Mathieu Boccard a, Sylvain Nicolay e, Andrea Ingenito a, Christophe Ballif a
Affiliations
a, École Polytechnique Fédérale de Lausanne (EPFL), Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory (PV-Lab), CH, Rue de la Maladière, 71, Neuchâtel, CH
b, Instituto de Física, Universidade Federal do Rio Grande do Sul, Brazil
c, EMPA - Swiss Federal Laboratories for Materials Science and Technology, Überland Strasse, 129, Dübendorf, CH
d, CSIRO Energy Centre, Australia, AU
e, CSEM, PV-Center, Jaquet-Droz 1, 2002 Neuchâtel, Switzerland
Abstract

Increasing the efficiency of solar cells further is now the most direct avenue to make solar electricity even cheaper and ease the energy transition. This involves designing solar cells that achieve efficiencies beyond the practical limit of 27% of crystalline silicon (c-Si) solar cells, the technology dominating the photovoltaics market. In addition, this solar cell of tomorrow should be processed at low costs, employ earth-abundant elements and exhibit a long life time in the field. One emerging cell design may meet these criteria: multi-junction solar cells combining metal halide perovskites and c-Si. The tuneable bandgap, soft processing conditions and high single-junction performance of perovskite cells indicate that a c-Si solar cell could be upgraded with one or more perovskite top cell(s) to reach efficiencies >30% through a few extra process steps and hence at low additional process costs.

Fulfilling this potential is first a processing challenge. For maximum performance and compatibility with existing c-Si process flows, the perovskite solar cell should be deposited directly on the textured front side of the c-Si solar cell, a texture that improves light management in the c-Si. But this pyramidal texture is not compatible with standard perovskite solution-based deposition protocols as these lead to non-conformal coatings and electrical shunt paths. A hybrid evaporation/solution perovskite processing route was developed at EPFL PV-Lab to enable the conformal deposition of perovskite top cell(s) on the pyramidal texture of c-Si cells to achieve high photocurrents (Panels a of TOC). This contribution will discuss how a careful analysis of the device structure on the nanometre scale enabled the identification of performance-loss mechanisms and helped guiding processing efforts. High-efficiency (>25%) perovskite/c-Si tandems were demonstrated on different n- and p-type c-Si technologies [1,2], notably by identifying i) optimal bottom cell contact structures [3], ii) crystallographic and chemical features enabling the recombination junction to quench shunts [4], iii) hole-selective contact instabilities depending on recombination junction and perovskite crystallisation conditions (Panel b). This contribution will then elaborate on the next performance-loss mechanisms that should be addressed to achieve an efficiency of >30%.

The second challenge, and likely the most difficult one to tackle before any commercialisation of the technology can be envisaged, is related to the instability of perovskite solar cells. Degradation pathways triggered by reverse voltages, which may appear when a module becomes partially shaded, or during long-term operation at maximum power point at various temperatures will be discussed [5]. These emphasise the dynamic nature of the perovskite nanostructure (ionic migration within the absorber and also into the contacts (Panel c), volatilization of species, crystallographic phase change/decomposition, shunt formation due to metal migration) depending on the external stimuli and its influence on the solar cell performance. Overall, these findings demonstrate that opaque solar cell architectures commonly employed by the community are particularly unstable in reverse bias, prompting the need for urgent research efforts.

12:10 - 12:15
Discussion
12:15 - 12:40
G4-I4
Ohkita, Hideo
Kyoto University, Japan
Charge Recombination Losses in Perovskite Solar Cells
Ohkita, Hideo
Kyoto University, Japan, JP

Hideo Ohkita is a Professor in the Department of Polymer Chemistry at Kyoto University.  He obtained a Doctoral degree in 1997 at Kyoto University.  He became an Assistant Professor in 1997, was promoted to Associate Professor in 2006, and to Professor of Department of Polymer Chemistry at Kyoto University in 2016.  He concurrently worked as an academic visitor with Professor Durrant at Imperial College London from 2005 to 2006, and as a researcher in the Precursory Research for Embryonic Science and Technology (PRESTO) program “Photoenergy Conversion Systems and Materials for the Next Generation Solar Cells”, Japan Science and Technology Agency (JST), from 2009 to 2015.  His research interests include studying photophysics and photochemistry in polymer systems.  His current research focuses on spectroscopic approach to polymer solar cells.

Authors
Hideo Ohkita a
Affiliations
a, Kyoto University, Japan, Goryo-Ohara, Nishikyo-ku, Kyoto 615-8245, JP
Abstract

Metal halide perovskite solar cells have attracted increasing attention as one of the most promising photovoltaic devices.  Currently, the power conversion efficiency (PCE) of lead-based perovskite solar cells has exceeded 25%.  Although it is approaching to the theoretical limit, there is still room for further improvement in PCE.  In most cases, charge recombinations are still one of the main loss processes in perovskite solar cells.  In this talk, I will focus on voltage losses due to various charge recombinations in perovskite solar cells.  First, I will talk about the origin of the initial improvement in open-circuit voltage (VOC) and fill factor (FF) of lead-based perovskite solar cells after storage in the ambient atmosphere.  We estimated trap density in perovskite solar cells with different storage durations by analyzing the intensity dependence of VOC with direct and SRH recombination model as reported previously [1].  As a result, we found that trap density is decreased with increasing storage time and hence VOC is also improved.  In order to address the origin of the decrease in trap density, we measured external quantum efficiency (EQE) spectra over the wide wavelength above and below the bandgap energy Eg.  Consequently, EQE signals were observed at wavelengths even below Eg for the device before the storage, suggesting that there are some defects in sub-bandgap states.  After the storage, the EQE signals below Eg were effectively reduced.  A similar reduction in the EQE at sub-bandgap was observed for the device with surface passivation treatment.  We therefore conclude that the initial improvement in VOC is due to the decreasing defects in sub-bandgap states, which are probably located at surface or boundary of perovskite grains.  We further discuss the origin of voltage losses in tin-based perovskite solar cells [2].

 

 

 

 

12:40 - 12:45
Discussion
Industry talks
Chair: Shuzi Hayase
12:45 - 12:50
talks-S1
Tanabe, Taro
TCI industry talk
Tanabe, Taro
Authors
Taro Tanabe a
Affiliations
a, TCI Chemicals
Abstract

TCI, Tokyo Chemical Industry, is a proud sponsor of this conference. Since its founding in 1946, TCI’s philosophy has been to "Serve Society through Chemical Reagents." After 73 years of business, TCI offers more than 30,000 quality reagents on a global scale. In recent years, the business has grown to the manufacture of fine chemicals for use in pharmaceuticals, cosmetics, electronics, sustainability, and other industries.

Consistent with the belief that chemistry is key to the advancement of society, TCI’s aim is to provide an expanding library of valuable research products while reaching the highest levels of quality and service. You can order TCI products anytime, anywhere in the world.

For materials science research field, TCI provides high quality organic materials, perovskite precursors, etc. You can realize high performance and reproducibility of your scientific data with our materials. You can find TCI’s unique products that no other chemical company provides. Please visit our catalog and website to find quality, variety and a difference.

12:50 - 12:55
talks-S2
Hebting, Yanek
Greatcell Solar Materials Pty Ltd
Greatcell Solar Materials
Hebting, Yanek
Greatcell Solar Materials Pty Ltd, AU
Authors
Yanek Hebting a
Affiliations
a, Greatcell Solar Materials
Abstract

Greatcell Solar Materials manufactures and supplies the very best quality materials for energy systems applications. These include high-purity third generation solid-state perovskite solar cell (PSC) and dye-sensitised solar cell (DSC) components, semi-conductors, precursors, charge transport materials and additives, LED and OLED components.

GSM is capable and ready for the industrialisation of DSC and PSC technologies. GSM is also aiming at providing materials for the commercialisation of innovative perovskite-based applications such as optoelectronic, piezoelectric and ferroelectric devices as well as molecular switches.

Greatcell Solar Materials operations range from small scale synthesis to pilot scale development; we are capable of fulfilling small orders for individual projects or large orders for production scale initiatives. We welcome the opportunity to tailor products or product quantities to suit your needs practically and cost-effectively.

We strive to provide our customers a positive online shopping experience. You can search our site if you know exactly what you are looking for or use different filters that will save you time and efforts.

13:00 - 14:30
lunch
Session A2
Chair: Jung-Yao Chen
14:30 - 14:55
A2-IS1
Aoki, Yoichi
Toray Industries, Inc.
Wireless sensor nodes with organic solar cells
Aoki, Yoichi
Toray Industries, Inc.

Yoichi Aoki is a senior research chemist in the Advanced Materials Laboratories at Toray Industries. He received his PhD degree in engineering from Kyushu University in 2017. He joined R&D Headquarters in Rohm from 2007 to 2017, during which he was engaged in development of medical POCT for diabetes, organic solar cells, and discrete module of thermal printheads. Currently his research interests are organic photovoltaics for indoor application like a wireless sensor network and focuses on printed organic electronics.

Authors
Yoichi Aoki a, Shuhei Yamamoto a, Daisuke Kitazawa a
Affiliations
a, Toray Industries, Inc.
Abstract

1. Introduction

In the IoT(Internet of Things) society, vast many types of sensors are embedded into the wireless communication module in order to collect various ambient data for energy managements like the BEMS and HEMS. These systems need a lot of self-powered sensor nodes with energy harvester instead of wired power source or primary batteries.

The organic solar cells have high photovoltaic performance in the indoor low light condition. So, this study demonstrates the energy saving verification using by wireless sensor nodes with organic solar cell under the various indoor condition.

 

2. Experimental

Organic solar cells are fabricated in our laboratories. Figure 1.(a) shows the organic solar cell panel of single cell type. The electron-donor material (TR-SCP197) of organic photovoltaic layer is also synthesized in our laboratories. The environmental sensor nodes (temperature, humidity, and brightness) are assembled by NISSHA Co., Ltd. And the occupancy sensor nodes are assembled by OPTEX Co., Ltd. The conventional amorphous silicon solar cells (a-Si) are also prepared and tested at same time in order to compare the photovoltaic performance and driving performance of wireless sensor nodes under the low light condition. The wireless sensor nodes are installed in an office and a conference room. For example, the brightness and occupancy data are wirelessly transmitted to the gateway in order to maintain the optimal brightness of room lightings by specific area and turn off the room lighting automatically if no one is there. Figure 1.(b) shows the energy management system using wireless sensor nodes in this system

 

3. Result

The photovoltaic performance of organic solar cells are 1.3 times electric power generation compared to a-Si under the 50 to 200 Lux LEDs. Though a 1-year verification test, the environmental sensor nodes and occupancy sensor nodes work with the very dim light condition at 40 and 70 Lux each. And the electrical power consumption of room lightings are saved about 40% after installing this system.

14:55 - 15:00
Discussion
15:00 - 15:15
A2-O1
REZASOLTANI, ELHAM
Department of Physics, Imperial College London
Correlating the Phase Behavior with the Device Performance in Binary P3HT: NFA Blend Using Optical Probes of Microstructure
REZASOLTANI, ELHAM
Department of Physics, Imperial College London, GB
Authors
ELHAM REZASOLTANI a, Anne Guilbert a, Jun Yan a, xabier Rodriguz b, Mohammed Azzuzi a, Sachetan Tuladhar a, Andrew Wadsworth c, Iain Mcculloch c, d, Mariano Campoy b, Jenny Nelson a
Affiliations
a, Department of Physics, Imperial College London, GB
b, Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Spain, Campus UAB, Bellaterra, ES
c, Department of Chemistry and Centre for Plastic Electronics, Imperial College London, South Kensington Campus, London, GB
d, King Abdullah University of Science and Technology (KAUST) - Saudi Arabia, 4700 King Abdullah University of Science and Technology (KAUST), Thuwal, SA
Abstract

The performance of polymer: acceptor blends for use as a light-harvesting layer in organic photovoltaic (OPV) cells depends strongly on the structural features of the active layer, including the extent of intermixing, vertical phase segregation, and generally, its phase morphology. Recent studies show that in most popular bulk heterojunction (BHJ) systems the phases are not pure and a significant volume is occupied by mixed domains that may be rich in either donor or acceptor. [1] Therefore, one crucial aspect of understanding optimized OPV performance is to find characterization techniques to gain a detailed picture of the mixed phases in BHJ systems. This is especially important with the introduction of multicomponent systems such as ternaries where multiple acceptors (A), or donors (D), with different mixing behavior with the other (donor or acceptor) component can be used. [2]

In this study, we present the observations of the phase behavior of non-fullerene acceptors (NFAs), namely non-planar O-IDFBR, planar O-IDTBR, and its branched side-chain analog EH-IDTBR, in semi-crystalline P3HT using thermal and optical characterization techniques and evaluate the optical methods we have used as probes of microstructure. We use a combination of non-destructive optical probes to analyze the microstructure of blend films of P3HT: NFAs as a function of composition. Spectroscopic ellipsometry (SE) helps analyze the optical properties of multicomponent systems in terms of the composition, and Raman spectroscopy allows us to understand the state of order of the conjugated backbone, and chemical structure.  Moreover, e demonstrate how UV-vis and PL can be used to capture the degree of mixing of the thin films. We interpret the optical properties of binary blends of different composition in terms of the phase behavior of the blends and compare our findings with a picture of the phase behavior obtained using differential scanning calorimetry (DSC). The detailed picture of the microstructure allows us to correlate the impact of NFA composition and crystallinity on the microstructure with photocurrent generation by photovoltaic devices.

These optical studies demonstrate that the less planar NFA (O-IDFBR) mixes finely into semicrystalline P3HT at weight contents up to 40 wt%, beyond which it disrupts the order of the P3HT. However, the more planar NFAs (O-IDTBR and EH-IDTBR), could be accommodated up to 70 wt% in the blend without disrupting the polymer. We observe the maximum of the power conversion efficiency (PCE) of P3HT: O-IDTBR peaks at the eutectic composition where crystals of both D/A form and based on the optical probes the binary is phase-separated. Surprisingly, we observe the maximum of the PCE of P3HT: O-IDFBR to lie around 30-50 wt% O-IDFBR, which is far below the apparent eutectic composition, as shown in the figure attached. This is assigned to the loss of P3HT transport before reaching the eutectic, based on Raman analysis.

The results show that device performance is dictated by short circuit current density (Jsc). In order to focus on understanding the interplay between the blend film morphology and the Jsc of the corresponding devices we estimate composition-dependent internal quantum efficiency (IQE) and compare with our results for phase behavior. We find that the O-IDTBR contribution to IQE is notably higher than that of O-IDFBR, which can be assigned to the higher crystallinity of O-IDTBR compared to O-IDFBR as well as due to P3HT crystallinity is rather disrupted when mixed with O-IDFBR than O-IDTBR. It appears that the optimized performance is strongly dependent on the degree of polymer and NFA crystallization.

 

15:15 - 15:30
A2-O2
KARUTHEDATH, SAFAKATH
King Abdullah University of Science and Technology (KAUST) - Saudi Arabia
Importance of Energetic Driving Force for Efficient Charge Separation in Non-fullerene Organic Solar Cells
KARUTHEDATH, SAFAKATH
King Abdullah University of Science and Technology (KAUST) - Saudi Arabia, SA
Authors
SAFAKATH KARUTHEDATH a, Julien Gorenflot a, Anastasia Markina b, Yuliar Firdaus a, Ahmed H. Balawi a, Thomas D. Anthopoulos a, Denis Andrienko b, Frédéric Laquai a
Affiliations
a, King Abdullah University of Science and Technology (KAUST) - Saudi Arabia, 4700 King Abdullah University of Science and Technology (KAUST), Thuwal, SA
b, Max Planck Institute for Polymer Research, Mainz, Ackermannweg, 10, Mainz, DE
Abstract

The minimum energy offset required to ensure efficient charge separation at organic donor-acceptor heterojunctions is a matter of current debate.1-2 Here, we investigate the charge generation in a series of donor – acceptor bulk heterojunction blends including the small molecule donor DR3, two high-efficiency donor polymers (PBDB-T-2F, PCE10), and eight different non-fullerene acceptors (NFA), spanning a power conversion efficiency range from <1% to above 15%.

In principle, both electron affinity (EA) and ionization energy (IE) offsets should equally control the charge generation. However, we demonstrate that despite large EA offsets, it is the IE offset, which controls both the exciton quenching and charge separation efficiency, as ultrafast energy transfer from the donor to the acceptor competes with photoinduced electron transfer. This implies, the IE offset cannot be reduced to zero to maximize the Voc as it leads to inefficient exciton quenching and reduced charge separation efficiencies and in turn to lower device photocurrents and performance.

15:30 - 15:45
A2-O3
Yan, Jun
Department of Physics, Imperial College London
Relating Microstructure Behaviour to Charge Transfer States Properties and Energy Losses in Organic Bulk Heterojunction Solar Cells
Yan, Jun
Department of Physics, Imperial College London, GB
Authors
Jun Yan a, Elham Rezasoltani a, Mohammed Azzouzi a, Flurin D. Eisner a, Anne A. Y. Guilbert a, Jenny Nelson a
Affiliations
a, Department of Physics, Imperial College London, GB
Abstract

The microstructure of donor: acceptor blend photoactive layers in organic solar cells directly influences the properties of interfacial charge-transfer (CT) states, and thereby influences the minimum value of the energy loss that can be achieved in the photovoltaic device. However, relatively few studies are able to relate blend phase behaviour directly to device energy losses. In this work, we study the correlation between the phase behaviour of two poly-3-hexylthiophene (P3HT): acceptor blends made using different non-fullerene acceptors, namely IDTBR and IDFBR, and the energy losses of the blend devices. Whilst the two acceptors are chemically very similar, small differences in molecular structure result in large differences in the degree of crystallisation and mixing in the blend films. In particular, P3HT:IDTBR blends shows a higher degree of crystallinity and more phase separated domains, whereas P3HT:IDFBR blends show lower crystallinity and more mixing of polymer and acceptor. The different blends exhibit different trends in terms of energy loss as a function of blend composition, indicating disparate mechanisms on energy losses. To understand this, I will quantify the radiative and nonradiative component of energy losses and apply a model of interfacial charge recombination [1] and models of charge transport in order to relate the measured energy losses to the transport and recombination dynamics in the different blends and finally to the blend microstructure.  I will bring the observations together to discuss the relationship between phase behaviour and recombination losses using the P3HT:acceptor systems as a model.

 

15:45 - 16:15
Coffee Break
16:15 - 16:30
A2-O4
Wei, Zhengfei
Swansea University, UK
Room-temperature Processed Transparent Conductive Oxides For Efficient And Semi-transparent Perovskite And Organic Solar Cells
Wei, Zhengfei
Swansea University, UK, GB
Authors
Zhengfei Wei a, Benjamin Smith a, Amirah Way a, Vasil Stoichkov a, Francesca De Rossi a, Harrison Ka Hin Lee a, Jérémy Barbé a, Wing C. Tsoi a, Justin Searle a, David Worsley a, Trystan Watson a
Affiliations
a, SPECIFIC, College of Engineering Swansea University, SPECIFIC, Baglan Bay Innovation Centre, Central Avenue, Baglan, Port Talbot, SA12 7AX, GB
Abstract

In order to achieve semi-transparency in perovskite and organic solar cells, the electrode materials must be as transparent as possible. In this work, MoOx/ITO/Ag/ITO (MoOx/IAI) and MoOx/IZO thin films with respective high-average-transmittance of 79.90% and 85% between 400 nm and 900 nm were introduced as the top transparent electrode to explore its influences on optoelectronic properties of the fabricated perovskite and organic solar cells. MoOx has been demonstrated previously as protection from sputtering damage using a conventional ITO or IZO top electrode, however it is shown here to provide protection from a sputtered IAI and IZO film that provides superior transparency and conductivity and is deposited using more favourable low temperature processing conditions. MoOx and Ag were thermally evaporated and ITO and IZO was radio-frequency magnetron sputtered at room temperature. The resulting semi-transparent solar cells showed power conversion efficiency of 12.85% for IAI based PSCs, 16.03% for IZO based PSCs and 4.58% for IZO based OPV, respectively.  The semi-transparent perovskite devices showed a much-reduced degradation rate as compared to the reference device with only an Ag/Au top electrode. Notably, we show that an unencapsulated semi-transparent perovskite cell using MoOx/IZO maintains its full performance under continuous illumination for over 770 hours in nitrogen environment. With such a combination of performance and transparency, this work shows great promise in application of perovskite solar cells into window glazing products for building integrated photovoltaic applications (BIPV), powering internet of things (IoT) and combining into tandem solar cells with industrially mature photovoltaic technologies such as silicon and copper indium gallium di-selenide (CIGS).

16:30 - 16:45
A2-O5
Leonardus, Mario
Academia Sinica
The Effect of Light-Harvesting Property of Oxasmaragdyrin and Its Impact as Hole Transporting Material in Perovskite Solar Cell
Leonardus, Mario
Academia Sinica
Authors
Mario Leonardus a, b, c, Chen-Hsiung Hung a
Affiliations
a, Institute of Chemistry, Academia Sinica, Nankang, Taipei 11529 Taiwan
b, National Chiao Tung University Hsinchu, Taiwan, 1001 University Road, Hsinchu, Hsinchu, TW
c, Sustainable Chemical Science and Technology Program, Taiwan International Graduate Program Academia Sinica Nankang, Taipei 11529 Taiwan
Abstract

Porphyrins materials such as tetraarylporphyrins, subphthalocyanines, phthalocyanines, and oxasmaragdyrins have shown compatibility as a hole transporting material (HTM) in perovskite solar cell (PSC) architecture. The devices with porphyrinic macrocycles as HTM show comparable power conversion efficiency (PCE) to those with Spiro-OMeTAD as the HTM.1-6 Nevertheless, the influence of the light-harvesting properties of porphyrinic macrocycles to the efficiency of hole migration has not been investigated. We discuss herein the overall consequence of light-harvesting of these compounds to the PCE performance using the derivatives of SM09, the best HTM among examined oxasmaragdyrins in our previous report, as model compounds.7 The alkyl chains with different chain lengths are introduced in the core position of SM09 to replace the fluorine atoms and attenuate the intermolecular distance which might alter the rate of energy transfer or self-quench. A series of core modification of SM09, encoded by SM09-B(OMe)2, SM09-B(OEt)2, SM09-B(OBut)2, SM09-B(OHex)2 and SM09-B(OOct)2 will be examined and compared.

The presence of methoxy groups in SM09-B(OMe)2 slightly improved the PCE performance of PSC in comparison with parent SM09, consistent with our previous report about the effects of the methoxy group as the HTM to PSC performance. Additionally, we have found that diminished PCE observed upon increasing the alkyl length from two-carbon SM09-B(OEt)2 to four-carbon SM09-B(OBut)2 likely due to the furtherer molecular distance which affected the hole mobility. Interestingly, we found a unique phenomenon in the J-V curves of the devices with SM09-B(OHex) and SM09-B(OOct) as HTMs, i.e. an unsteady Jsc with current continuously decrease at low voltage region. This phenomenon leads to unreasonable Fill Factor (FF) and an unusual low of short-circuit current density (JSC). After a series of examinations, we believe that this phenomenon is related to the self-quenched of SM09 derivatives. The observation that this current drop at low voltage region can be precluded by increasing the scan rate suggests that it is not a rapid exchange process. We used a filter light to measure the PCE performance and found that the dropping current was not observed while the device exposed with short-wavelength light (<600 nm) but still appear when it exposed by long-wavelength light (>600 nm). The presence of longer alkyl chains generates a larger intermolecular distance between the molecule which has not only decreased the hole mobility but also suppress self-quenched of boryl oxasmaragdyrins.  Thereafter, the excited HTM will inject photoelectrons to the LUMO of perovskite cell, which then either retards the excitation of perovskite layer or increases the rate of charge recombination from electrons at LUMO of perovskite and holes on the HOMO of HTM. Additional photophysical lifetime measurements will be conducted to provide conclusive evidence of this phenomenon. 

Searching of new HTMs as replacement of spiro-OMETAD has been a hot topic in PSC studies. Our finding for the first time reveals the effects upon using photoactive materials as HTM. Under the circumstance that there is no significant alternation on Voc and Jsc upon changing the scan rates during the measurements, the solution to obtain a more accurate PCE can be achieved through increasing scan rates. However, the competition on photon absorptions between HTM and perovskite layer appears to exert negative effects to the overall performance of PSC and should be taken into consideration upon the design of HTMs.

16:45 - 17:00
A2-O6
Aktas, Ece
Self-Assembled Hole Transporting Monolayer to Improve PiN Type Perovskite Solar Cell Performance
Aktas, Ece
Authors
Ece Aktas a, b, Jesús Jiménez-López a, c, Emilio Palomares a, d
Affiliations
a, Institute of Chemical Research of Catalonia (ICIQ), Barcelona Institute of Science and Technology (BIST), Avinguda dels Països Catalans, 16, Tarragona, ES
b, Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Marcel·lí Domingos/n, 43007 Tarragona,Spain
c, Departament d’Enginyeria Electrònica, Elèctrica i Automàtica, Univeristat Rovira i Virgili, Avda. Països Catalans 16, 43007 Tarragona, Spain
d, Institució Catalana de Recerca i Estudis Avançats (ICREA), Spain, Passeig Lluis Companys 23, Barcelona, ES
Abstract

Perovskite solar cells (PSCs) offer a magnificent opportunity to harness solar energy in an efficient and low cost way. The ambition for commercialization has been greatly encouraged by the surge in device performance from 3.8% in 2009 to the state-of-the-art 25.2%1. To obtain high power conversion efficiency altering the interfacial properties is essentially important. New charge selective contacts have been investigated to provide possible solutions to overcome this hurdle. Being in a molecular scale, self-assembled monolayers (SAMs) are promising affordable candidates for interface modification. SAMs are essentially organic assemblies formed by the adsorption of molecular constituents from solution onto the surface of solids. In the literature, several studies have shown that SAMs have many positive effects for PSCs, including the improvement of the energy level alignment, positively affecting the morphology, and passivating trap states2. They are offering the benefits of uniformly formed layers with minimized thickness that will be suitable for large-scale production3.

In the present talk, we will discuss semiconductor self-assembled monolayer to use as hole transporting layer instead of PEDOT:PSS for PiN type perovskite solar cells. We will present preparation procedure and photovoltaic characterization of devices, which have improved power conversion efficiency.

Session B2
Chair: Quentin Jeangros
14:30 - 14:55
B2-IS1
Bessho, Takeru
Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Japan
Material Amelioration of Organometal Halide Perovskite by Potassium-doping and Its Efficient Photovoltaics
Bessho, Takeru
Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Japan, JP

Dr. Takeru Bessho is a Project Lecture at the Research Center for Advanced Science and Technology (RCAST) at the University of Tokyo, Japan, who was granted Doctor of Engineering in 2009 from the Shibaura Institute of Technology as developments of optoelectronic device properties with organic-inorganic hybrid materials. His affiliations were SONY Corporation as a Researcher at
Advanced Materials Laboratories from 2011 to 2015, and École polytechnique fédérale de Lausanne as a Research Associate at laboratory of Prof. Michael Grätzel from 2009 to 2011. His main interest is on device engineering with organic-inorganic materials and its improvement of energy conversion efficiency as solar cells.

Authors
Takeru Bessho a
Affiliations
a, Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Japan, JP
Abstract

The Organometal halide perovskite solar cells (PSCs) have been dramatically researched and developed in the power conversion efficiency (PCE) certified over 24% [1] which is comparable to other solid state solar cells as crystalline silicon, CIGS, CdTe, etc. The modification of the components of perovskite is one of the key word for the refinement of quality and morphology of crystal and layer with increasing the abundance of photoactive phase such as tetragonal, cubic, trigonal, and decreasing the surface roughness and void in the layer, especially, with A-site cation in perovskite structure ABX3 [2]. In this talk, we report the potassium cation doping effect to perovskite absorber about properties of the expanded crystal lattice constant, red-shifted light absorption, up shifted conduction and valance band position, disappeared grain boundary in film, diminished hysteresis in photovoltaic I-V curve with over 20% PCE [3,4], furthermore, we have reached new composition as MA-Free system with over 21% PCE. The scaling up the photo active area with small less of FF without drop of Voc from single cells was maintained by development of device fabrication process point of view. Recently, the PCE was reached near 21% by 1 cm2 and 2.76 cm2 with less hysteresis based on the better flatness and less impurity of perovskite film by optimizing the process.

 

References

[1] Martin A. Green, et al.  Prog Photovolt Res Appl. 27, 565–575 (2019).

[2] Saliba, M., Grätzel, M., et al.  Science, 354, 206–209 (2016).

[3] Z. Tang, T. Bessho, H. Segawa, et al.  Sci. Rep., 7, 12183 (2017).

[4] Z. Tang, S. Uchida, T. Bessho, H. Segawa et al.  Nano Energy, 45, 184–192, (2018).

14:55 - 15:00
Discussion
15:00 - 15:15
B2-O1
Wang, Haibin
Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Japan
Enhance Infrared Photocurrent of PbS Quantum Dot Solar Cells toward the Bottom Subcell of Multi-junction Solar Cells
Wang, Haibin
Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Japan, JP
Authors
Haibin Wang a, Takaya Kubo a, Jotaro Nakazaki b, Hiroshi Segawa a, b
Affiliations
a, Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Japan, JP
b, University of Tokyo, Japan, JP
Abstract

Solution-processed tandem solar cells, that stack two or more single-junction subcells with different band gaps to harvest photons in the full solar spectrum more efficiently, have attracted increasing attention recently. Organic photovoltaics and perovskite solar cells are promising candidates for the top and/or middle subcells of tandem solar cells because the solar cells are able to capture visible and near-infrared photon energy. While PbS and PbSe colloidal quantum dots (CQDs) have been gaining much attention for short-wave infrared solar cells owing to their wide-range bandgap tunability and solution process compatibility. Thus, we have focused on PbS QD/ZnO nanowire (NW) structures with the aim of achieving efficient carrier transport and light absorption in the infrared region simultaneously 1-2. We then investigated the performance of PbS QD/ZnO NW solar cells using PbS CQDs with the first exciton absorption peak locating in the infrared region (940 nm-1840 nm) 3. We recently constructed high-efficiency infrared PbS QD/ZnO NW solar cells with a record high EQE of 47% (at 1560 nm). The solar cell installed with an 870 nm sharp-cut filter yielded a PCE of 2.02 % (Jsc=14.8 mAcm-2; Voc=0.285 V; FF=47.9 %) under a filtered one-sun illumination. Based on these results, we will discuss the potential of PbS QD / ZnO NW solar cells toward the bottom subcell of multi-junction solar cells. 

15:15 - 15:30
B2-O2
Hou, Cheng-Hung
Academia Sinica
Revealing Performance Governing Factors of Perovskite Solar Cells via Artifact-Free ToF-SIMS Depth Profiles
Hou, Cheng-Hung
Academia Sinica
Authors
Cheng-Hung Hou a, Shu-Han Hung a, Jing-Jong Shyue a, b, Pi-Tai Chou c
Affiliations
a, Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan.
b, National Taiwan University, Department of Materials Science and Engineering, Taipei, TW
c, National Taiwan University, Department of Chemistry, Taipei, Taipei, TW
Abstract

The emerging technology of perovskite solar cells (PSCs) has a revolutionary influence on the research community due to the unprecedent growth rate of its power conversion efficiency (PCE). Despite PSC has a history that shows a seemly promising future, most studies have been focusing on PCE and lifetime optimization instead of verifying the performance governing factor of PSCs. Recently, time-of-flight secondary-ion mass spectrometry (ToF-SIMS) has been utilized for getting insights into the perovskite material due to its extremely high detection limit and its ability of detecting molecular component signals. These features have made ToF-SIMS a powerful tool in uncovering the fundamental property of the perovskite film, which is crucial for turning PSCs into a transformative technology. Unfortunately, very few have been aware that the probing beam must be carefully chosen during ToF-SIMS analysis otherwise misleading artifacts will appear [1],[2].

During this presentation, the origin of depth profile artifacts induced by the most commonly used sputter beams, O2+ and Ar-gas cluster ion beam (Ar-GCIB), will be discussed. These artifacts, although often ignored, could be widely observed in the perovskite depth profiles. We demonstrated an approach to eliminate depth profile artifacts by replacing O2+/Ar-GCIB with either C60+ or Ar+ sputtering. Based on this finding, we were able to reveal the true component distribution of PSCs and identified the performance governing factor. We verified that different manufacturing procedures could result in different component distributions of the perovskite film, which would greatly influence the PCE and J-V response of the device. As for stability issues, we confirmed that the major compositional difference between a fresh and an aged PCS was resulted from iodide diffusion. These results provided evidences that could support and facilitate the development of a more efficient and stable PSC.

15:30 - 15:45
B2-O3
Perrin, Lara
LEPMI / Université Savoie Mont Blanc
Gold electrode mitigation impact: elucidation of both degradation and safeguard mechanisms in a mixed-ion perovskite solar device
Perrin, Lara
LEPMI / Université Savoie Mont Blanc
Authors
Lara Perrin a, Manon Spalla a, b, Emilie Planes a, Muriel Matheron b, Solenn Berson b, Lionel Flandin a
Affiliations
a, LEPMI / CNRS UMR 5279 / Université Savoie Mont Blanc
b, CEA, LITEN, Department of Solar Technologies, INES, 50 avenue du Lac Leman BP 332, Le Bourget du Lac, 73377, FR
Abstract

Gold electrode mitigation impact: elucidation of both degradation and safeguard mechanisms in a mixed-ion perovskite solar device

Lara Perrina, Manon Spallaa,b, Emilie Planèsa, Muriel Matheronb, Solenn Bersonb, Lionel Flandina

aUniv. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, Grenoble INP, LEPMI, 38000 Grenoble, France

bUniv. Grenoble Alpes, CEA, LITEN, INES, 73375 Le Bourget du Lac, France

 

In the photovoltaic field, perovskite devices have already proved their potential to overcome the performance limits of current technologies and achieve low cost and high versatility. Several challenging developments are nowadays in progress on, for instance, low temperature processes for flexible devices compatibility, semi-transparent devices for tandem applications … Nevertheless, this technology is known to be sensitive to environmental factors as temperature, oxygen and humidity.

The degradation behaviour of a selected pertinent mixed-ion perovskite device has been here draft when submitted to incremental stress conditions (see adjacent figure). The presented device architecture “ITO/SnO2/mixed-ion perovskite/PTAA/Au” is potentially compatible for both flexible and tandem applications. In order to find possible mitigation strategies, a careful study was conducted allowing to elucidate occurring degradation mechanisms thanks to an optimized characterization set composed of either imaging techniques (light beam induced current and photoluminescence), physico-chemical analyses (X-ray diffraction, UV-visible absorption and photoluminescence spectroscopy) and photovoltaic parameters measurements (power conversion and external quantum efficiencies).

 

As exposed on the presented figure (top view photographs of solar devices), it is possible to detect a strong difference in the perovskite layer already with an unaided eye, according to applied constraints (temperature only, additional air, followed by additional moisture). First of all, the talk will detail the degradation mechanisms highlighted using several complementary physico-chemistry characterizations. In particular, let us examine pictures presented on the right side (devices with gold electrode): the close yellow color resulting from conditions 1 and 3 were in fact proved to originate from a totally different downgrading product. Deeper imaging techniques were also employed and proved to be relevant to investigate the homogeneity of both the perovskite layer and its interfaces integrity.

Secondly, as evidenced on pictures on the left side (devices after top gold electrode delamination), it is obvious that gold plays a protective role against both air and moisture: degradation deceleration through a reduced permeation rate resulting in different perovskite layer chemical compositions and mechanical strengths. As regards condition 1 aging, at first sight it could seem obvious and rational that the electrode has no potential for protection against a sole temperature stress. However, advanced examinations brought to light a strong difference in the perovskite layer chemical evolution when scouting either under or apart the top electrode and here again the perovskite occurring degradation mechanism was found to be significantly lowered in the presence of gold electrode. This time gold has been proved to collaborate through an interaction with the hole transporting layer constituents. To give an idea of this significant contribution, devices were both aged with and without top electrode: completed devices loose 72% of photovoltaic efficiency after 500 h of aging at 85°C without gold, against 28% when aged with gold.

15:45 - 16:15
Coffee Break
16:15 - 16:30
B2-O4
Magaino, Shinichi
Kanagawa Institute of Industrial Science and Technology (KISTEC), Kawasaki, Japan
Standardization of Measurement Protocols for Photovoltaic Devices Exhibiting Complex Current Response to Applied Voltage
Magaino, Shinichi
Kanagawa Institute of Industrial Science and Technology (KISTEC), Kawasaki, Japan, JP
Authors
Shinichi Magaino a, Hidenori Saito a, Daisuke Aoki a, Tomoyuki Tobe a
Affiliations
a, Kanagawa Institute of Industrial Science and Technology (KISTEC), Kawasaki, Japan, 3-2-1 Sakado, Takatsu-ku, Kawasaki, JP
Abstract

For years, considerable research effort worldwide has been invested in the development of new thin-film photovoltaic (PV) technologies that may offer lower cost production, new applications or both [1]. At present dye-sensitized solar cells (DSC) have been on the market, and in the case of perovskite solar cells (PSC), a number of companies and research centres are devoted to technology transfer from laboratory to market, working on device stability and reliability, up-scaling and compatibility of the cell manufacturing with industrial process, such as roll-to-roll deposition [2]. However, there are considerable difficulties associated with reliable measurement of power conversion efficiency for some kinds of DSC and PSC that are a serious concern for technology transfer from laboratory to market. Although the measurement procedures described in the IEC 60904 series and IEC 60891 are highly effective for “well-behaved” devices, such as most wafer-based silicon solar cells, these standards lack sufficient direction to address the complex challenges presented by these devices [3]. As a consequence, these devices need some additional measurement challenges that are at present not dealt with in these standards. In this paper we present what additional measures may be needed for accurate determination of the power conversion efficiency, and how these measures might be done for the devices exhibiting complex current response to applied voltage.

16:30 - 16:45
B2-O5
Ashhab, Sahel
Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Doha
Solution-processed Perovskite-colloidal Quantum Dot Tandem Solar Cells for Photon Collection Beyond 1000 nm
Ashhab, Sahel
Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Doha, QA
Authors
Afsal Manekkathodi a, Bin Chen b, Junghwan Kim b, Se-Woong Baek b, Benjamin Scheffel b, Yi Hou b, Olivier Ouellette b, Makhsud Saidaminov b, Oleksandr Voznyy b, Vinod Madhavan a, Abdelhak Belaidi a, Sahel Ashhab a, Edward Sargent b
Affiliations
a, Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Doha, P.O. Box: 34110, Doha, 0, QA
b, Department of Electrical and Computer Engineering, University of Toronto, Canada, King's College Road, 10, Toronto, CA
Abstract

Multi-junction solar cells based on solution-processed metal halide perovskites offer a route to increased power conversion efficiency (PCE); however, the limited options for infrared (IR)-absorbing back cells have constrained progress. Colloidal quantum dot (CQD)-based solar cells, which are solution-processed and have bandgaps tunable to wavelengths beyond 1000 nm, are attractive candidates for this role. Here we report a solution-processed four-terminal (4T) tandem solar cell comprised of a perovskite front cell and a CQD back cell. The 4T tandem provides a PCE exceeding 20%, the highest PCE reported to date for a perovskite-CQD tandem solar cell. The front semi-transparent perovskite solar cell employs a dielectric-metal-dielectric (DMD) electrode constructed from a metal film (silver/gold) sandwiched between dielectric (MoO3) layers. The highest-performing front semi-transparent perovskite solar cells exhibit a PCE of ~18%. By tuning the wavelength-dependent transmittance of the DMD layer based on the zero-reflection condition of optical admittance, we build semi-transparent perovskite solar cells with a 25% increase in IR transmittance compared to baseline devices. The back cell is fabricated based on an IR CQD absorber layer complementary to the IR transmittance of the semi-transparent perovskite front cell. Solution-processed hybrid tandem photovoltaics (PV) combining these technologies offer to contribute to higher-efficiency solar cells for next-generation flexible photovoltaic (PV) devices.

16:45 - 17:00
B2-O6
Huang, Jun-Yu
National Taiwan University of Science and Technology
Analysis of Hysteresis Effect and Modeling of Ion Migration in Perovskite Solar Cells
Huang, Jun-Yu
National Taiwan University of Science and Technology, TW
Authors
Jun-Yu Huang a, En-Wen Chang a, Yuh-Renn Wu a
Affiliations
a, National Taiwan University, Graduate Institute of Photonics and Optoelectronics, Taipei, No. 1, Section 4, Roosevelt Road, 10617, Taipei, TW
Abstract

In this paper, we developed a simulation tool to analyze the hysteresis effect of JV curve in Perovskite solar cells. Some studies have shown that the ion migration is the main reason leading to the hysteresis effect of JV curve [1-3]. However, the typical commercial simulation software can only demonstrate the fixed ion distribution [4],which can only  model the effect of ion accumulation at two sides. However, it's hard to explain as the dynamic changes of ion migration under different bias scan rates. Hence, we developed a 2D simulation program that can handle the time dependent ion migration movement. This program also model  the light absorption with texture surface as well as the carrier transport in the devices. In this program, the optical field was solved by FD-TD method and electrical properties were solved by Poisson & drift-diffusion solver, the detail can be referred to Ref. [5]. The time-dependent drift-diffusion model especially for ion migration was added into this program and couple with the Poisson and drift-diffusion solver for carriers. Hence, we can consider the electrical field variation with ion migration in our modeling. Partial simulation results were shown in this abstract due to limit space.. The structure was formed by Au (80nm) / PCBM (20nm) / MAPbI3 (300nm) / PEDOT:PSS (20nm) / ITO (150nm) [6]. Fig. (a) is the ion accumulation with different pre-bias for 10 seconds. In the Fig. (b), the solid line is simulation result of conduction band without ion migration effect and the dash line is the conduction band that considered the ion accumulation. These figures show that the ion accumulation was mainly decided by pre-bias condition (the electrical field at this bias). To understand the effect of ion distribution in electrical properties, the different voltage-bias scan rate is was performed to understand the degree of ion migration. Fig. (c) shows the hysteresis effect under different scan rate. The trend of simulation results was close to the experiment data [1]. And some studies have shown that the ion migration would lead to the defect generation in Perovskite [1]. Fig. (d) shows the result with consideration of defect generation after ion migration, we can observe that the open-circuit voltage would be strongly affected by different defect state density and ion accumulation. By consideration the defects, the trend of simulation result is more close to the experiment result [1].

Session C2
Chair: Ellie Tanaka
14:30 - 14:55
C2-IS1
Mastroianni, Simone
Fraunhofer Institute for Solar Energy Systems ISE, Germany
Towards a Sustainable Energy Future: Fully Printable Carbon-Based Perovskite Solar Cells with Overcome Charge Transport Limitation and Improved Light-Harvesting Efficiency
Mastroianni, Simone
Fraunhofer Institute for Solar Energy Systems ISE, Germany, DE
Authors
Simone Mastroianni a, b, Lukas Wagner a, Gayathri Mathiazhagan a, c, Dmitry Bogachuk a, Kübra Yasaroglu Ünal a, d, Shankar Bogati a, Thomas Kroyer a, Michael Daub e, Harald Hillebrecht e, Jean-Luc Rehspringer d, Aziz Dinia d, Andreas Hinsch a
Affiliations
a, Fraunhofer Institute for Solar Energy Systems ISE, Germany, Heidenhofstraße, 2, Freiburg im Breisgau, DE
b, Freiburg Materials Research Center FMF, Albert-Ludwigs-University Freiburg, DE, Stefan-Meier-Straße, 25, Freiburg im Breisgau, DE
c, Albert-Ludwigs-University Freiburg, Department of Microsystems Engineering (IMTEK), Georges-Köhler-Allee, 103, Freiburg im Breisgau, DE
d, IPCMS, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, B. P. 43, 67034 Strasbourg Cedex 2, France
e, Albert-Ludwigs-Universität Freiburg, Institut für Anorganische und Analytische Chemie, Albertstraße, 21, Freiburg im Breisgau, DE
Abstract

A projection of worldwide CO2 emissions of the future PV industry is initially presented. We investigate the development of gross global CO2-emissions from the PV industry towards a sustainable energy future. This is the basis for our motivation to propose a fully printed integrated carbon-based PV module concept as alternative pathway to strongly reduce the carbon footprint to the ultimate lower limit of the glass substrate fabrication. For this glass-glass sealed perovskite solar cell (PSC) concept in which the perovskite is introduced “in-situ” as a last fabrication step, we show a certified-stabilized efficiency of 9.3 %. We calculated for the in-situ PSC an emission of 3.67 g CO­2-eq/kWh, which is just 4.8 % of the value for mono-Si PV modules.

With the goal to increase the efficiency towards an ambitious - yet achievable - 20%, we propose three approaches aimed at increasing the light-harvesting efficiency and at obtaining a uni-directional charge transport. These approaches have been experimented on monolithic carbon-based PSCs (C-PSCs):

1. A perovskite molten-salt approach obtained through liquefaction and recrystallization of CH3NH3PbI3 perovskite with methylamine - MA0(CH3NH2) gas. The fabricated C-PSC showed optimized perovskite self-assembling and improved crystallization with efficient charge transport and extraction, resulting in a high VOC of 1 V, which is the highest VOC reported for a monolithic HTL-free MAPbI3 device. This device has been certified under steady-state with a value of 12.6%. Furthermore, we unravel how methylamine interacts with perovskite during its liquid-to-solid transition by using a combination of Raman spectroscopy, single-crystal XRD and a real-time photoluminescence (PL) monitoring during the crystallization.

2. Monolithic C-PSCs commonly use thick >1 µm printed electrically insulating space layer to prevent charge recombination at the mp‑TiO2/carbon interface. We show a reproducible large-area procedure to replace this thick space layer with an ultra-thin dense 40 nm sputtered Al2O3, which is able to prevent ohmic shunts and to efficiently reduce the charge recombination at the mp-TiO2/carbon interface. Herewith, transport limitations related so far to the hole diffusion path length inside the thick mesoporous space layer have been omitted by concept. A stable VOC of 1 V using MAPbI3 perovskite has been achieved with stabilized device performance of 12.1%.

3. The third approach show how embedding cross-linked poly(methyl-methacrylate) (PMMA) nanoparticles of tunable size into the mesoporous TiO2 scaffold via sol-gel process can directly influence the pore size of the final film and, therefore, enhance the light-harvesting efficiency. SEM and 3D nano-tomography (from FIB-SEM) demonstrate the pore size engineering of the mp-TiO2 layer. The impregnated C-PSC filled with double-cation mixed halide FA0.83Cs0.17PbI2.64Br0.36 perovskite photoabsorber, reaches VOC close to 1 V with a power conversion efficiency (PCE) of 12.7%.

14:55 - 15:00
Discussion
15:00 - 15:15
C2-O1
Kamarudin, Muhammad Akmal
Lead-free tin halide perovskite solar cells beyond 10 % efficiency
Kamarudin, Muhammad Akmal
Authors
Muhammad Akmal Kamarudin a, Daisuke Hirotani b, Zhen Wang b, Kengo Hamada b, Kohei Nishimura a, Qing Shen c, Satoshi Iikubo b, Takashi Minemoto d, Kenji Yoshino e, Shuzi Hayase a
Affiliations
a, i-Powered Energy System Reserach Center, The University of Electro-Communications, JP
b, Kyushu Institute of Technology, Japan, 204 Hibikino Wakamatsu-ku, Kitakyushu - Fukuoka, 808, JP
c, Graduate School of Informatics and Engineering, University of Electro-Communication, 1-5-1 Chofugaoka, Chofu, Tokyo, 182-8585, Japan.
d, Department of Electrical and Electronic Engineering, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan.
e, Faculty of Engineering, University of Miyazaki, Gakuen-kibanadai-nishi-1-1, Miyazaki, 889-2192, Japan.
Abstract

Lead-free tin perovskite solar cells (PSCs) show the most promise to replace the more toxic lead-based perovskite solar cells. However, the efficiency is significantly less than that of lead-based PSCs as a result of low open-circuit voltage (VOC). This is due to the tendency of Sn2+ to oxidize into Sn4+ in the presence of air together with the formation of defects and traps caused by the fast crystallization of tin perovskite materials. Here, post-treatment of the tin perovskite layer with edamine Lewis base to suppress the recombination reaction in tin halide PSCs results in efficiencies higher than 10%, which is the highest reported efficiency to date for pure tin halide PSCs. Larger crystal sizes is obtained with EDA post-treatment and the VOC improved by as much as 0.1 V at an optimum EDA concentration. The X-ray photoelectron spectroscopy data suggest that the recombination reaction mainly originates from the nonstoichiometric Sn:I ratio in addition to the large Sn4+:Sn2+ ratio. The amine group in edamine bonded the undercoordinated tin, passivating the dangling bonds and defects, resulting in suppressed charge carrier recombination. This work provides an evident that the surface recombination also needs to be addressed especially in the case of tin perovskite solar cells in order to achieve better device performance.

15:15 - 15:30
C2-O2
Uchida, Satoshi
University of Tokyo, Japan
Evaluation of interface junction capacitance of perovskite solar cells by direct current measurement
Uchida, Satoshi
University of Tokyo, Japan, JP

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

Authors
Satoshi Uchida a, Ludmila Cojocaru b, Hiromi Tobita a, Viraji Jayaweera c, Shoji Kaneko c, Hiroshi Segawa a
Affiliations
a, Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Japan, JP
b, Universität Freiburg, Albertstr. 21, Freiburg, 79104, DE
c, SPD Laboratory, Inc., Johoku 2-35-1, Naka-ku, Hamamatsu 432-8011, JP
Abstract

The capacitance inside the perovskite solar cell device is crucial factor related with the hysteresis in I-V curve[1]. Nevertheless the understanding of capacitance is still not yet well understood because the conventional impedance analysts is a function of evaluation frequency and can not separate the charge / discharge current (capacitance) specially under the illumination condition.

Here in this study, we newly measured the internal capacitance of perovskite solar cell by using stepped light-induced transient measurements of photocurrent and voltage (SLIM–PCV) together with conventional inductance-capacitance-resistance (LCR) meter as a reference. By the SLIM-PCV measurement, we have seen a general trend of capacitance against the light intensity, that can be easily observed in the silicon solar cells. The perovskite solar cells measured by using the LCR-meter under 100 mW·cm-2 irradiation condition provides the huge capacitance values as a function of frequencies that is already reported in several literatures. The EBIC analysis is interesting and back supported the charge accumulation behavior at CH3NH3PbI3/TiO2 interface. We will discuss about this technique to correlate with the device durability by monitoring the capacitance.

Figure 1: Capacitance measurement for perovskite solar cell using LCR meter under the dark and 100 mW·cm-2 conditions

15:30 - 15:45
C2-O3
Liu, Xiao
Efficient and Stable Tin Perovskite Solar Cells by Introducing Π-conjugated Lewis Base
Liu, Xiao
Authors
Tianhao Wu a, Xiao Liu b, Liyuan Han a, b
Affiliations
a, Shanghai Jiao Tong University, 800 Dongchuan Road, Minhang District, Shanghai, China, Shanghai, 201100, CN
b, National Institute for Materials Science (NIMS), Center for Green Research on Energy and Environmental Materials, Photovoltaic Materials Group, Japan, JP
Abstract

Tin perovskite solar cells (TPSCs) as the most promising candidate for lead-free PSCs have attracted much attention all over the world. However, tin perovskite films deposited by the solution-based strategy usually undergo a much faster crystallization rate than that of the lead analogs,[1] which leads to abundant pinholes and random crystal orientation that induce serious charge recombination and poor device performance.[2] Besides, tin perovskite materials show poor environmental stability, they easily undergo phase transition or oxidization process when exposed to the air. Additive engineering is a promising way to improve both the film quality and stability, but there is a lack of design principle for the additive molecules to further improve the efficiency and long-term stability of TPSCs.

In this manuscript, we introduced the additive molecules designed with a π-conjugated unit and Lewis base functional groups to govern the crystallization kinetics of FASnI3 perovskite.[3] It's found that the π-conjugated units with strong electron-donating ability significantly increase the electron density of Lewis base groups, resulting in more stable intermediate phase formed with the Lewis acid Sn2+ components, leading to a compact and uniform perovskite film with much longer carrier recombination lifetime. Moreover, the hydrophobic nature of π-conjugated system also retards the permeation of moisture into perovskite crystal and therefore prevents the degradation of FASnI3 film in air.

As a result, we achieved a stabilizing power conversion efficiency of 10.1% for the TPSCs, and a certified steady-state efficiency of 9.2% was also obtained from the accredited test center, National Institute of Advanced Industrial Science and Technology (AIST, Japan). In addition, the TPSCs treated with CDTA maintained over 90% of its initial PCE after 1000-hours light soaking in air.

15:45 - 16:15
Coffee Break
16:15 - 16:30
C2-O4
Wright, Adam
University of Oxford
Band-tail trapping in FAPbI3 perovskite
Wright, Adam
University of Oxford, GB
Authors
Adam Wright a
Affiliations
a, University of Oxford, Department of Physics, Clarendon Laboratory, UK, Parks Road, GB
Abstract

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

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

 

 

16:30 - 16:45
C2-O5
Gao, Yajun
King Abdullah University of Science and Technology (KAUST) - Saudi Arabia
Revealing the Impact of Cesium/Rubidium Incorporation on the Photophysics of Multiple-Cation Lead Halide Perovskites
Gao, Yajun
King Abdullah University of Science and Technology (KAUST) - Saudi Arabia, SA
Authors
Yajun Gao a, Kai wang a, mingcong wang a, Jafar Khan a, Ahmed Balawi a, Stefaan Wolf a, Frederic Laquai a
Affiliations
a, King Abdullah University of Science and Technology (KAUST) - Saudi Arabia, 4700 King Abdullah University of Science and Technology (KAUST), Thuwal, SA
Abstract

The incorporation of cesium (Cs) and rubidium (Rb) ions into multiple-cation mixed lead halide perovskites increases their photovoltaic performance. In this study, the reasons for the performance increase are investigated by a set of steady-state and transient spectroscopy techniques. Analyzing the band edge absorption using Elliott’s model shows that the Cs/Rb-ion incorporation increases the band gap, while the excitonic binding energies remain low, in the range of a few milli-electronvolts. Low Urbach energies determined by photothermal deflection spectroscopy suggest optimized microstructures upon Cs/Rb incorporation. The charge carrier recombination dynamics indicate that Cs/Rb-incorporation reduces not only the first-order (trap-assisted) recombination, but also the second-order recombination in these perovskite films. Upon excitation, carrier density-induced broadening of the photo-bleaching following the Burstein-Moss model is observed and effective carrier masses are determined to be in the range of a few tenths of the electron rest mass, explaining the excellent charge carrier mobilities of these perovskite films. Sub-picosecond hot carrier cooling is observed, indicating a strong charge-phonon coupling. Our results unfold the impact of cesium/rubidium incorporation on the photophysics of multiple-anion lead halide perovskites and provide guidelines for future material engineering and device design.

Session G5
Chair: Takurou Murakami
17:00 - 17:40
G5-K1
Snaith, Henry
University of Oxford
Perovskite solar cells: materials, devices and industrialization
Snaith, Henry
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.

Authors
Henry Snaith a
Affiliations
a, University of Oxford, Department of Physics, Clarendon Laboratory, UK, Parks Road, GB
Abstract

I will present different approaches we have adopted to improving the efficiency, and fundamental stability of the perovskite absorber materials and devices. I will give further insight into what factors influence stability, and how to mitigate degradation.

In order to compete with, and deliver a superior technology to existing silicon PV, I will highlight how moving from a single absorber layer, to a multi-junction cell leads to much higher efficiencies, and I will show experimental realization of progress along such a road map for both all-perovskite and perovskite-on-silicon tandem cells.

Finally, I highlight progress towards the industrialization and manufacturing scale up of perovskite-on-silicon tandem solar cells at Oxford PV. 

1  1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

17:40 - 17:45
Discussion
17:45 - 18:00
Closing ceremony and poster awards_Room 202
 
Posters
Said Kazaoui
KI Post-Treatment Improves the Performances of Perovskite Solar Cells
Chongyang Xu, Eun-Cheol Lee
Morphology Control of SnO2 Layer for Efficient Perovskite Solar Cells through a Solvent Engineering Strategy
Dhruba B. Khadka, Yasuhiro Shirai, Masatoshi Yanagida, Kenjiro Miyano
Mitigation of the Recombination Activities with Rubidium incorporation for Efficient and Stable FASnI3 Solar Cells
Ying-Chiao Wang, Kazuhito Tsukagoshi
Silicon-Based Quantum Dot-Assisted Photoelectric Effect in Perovskite Solar Cells
Yung-Chung Chen, Yan-Heng Li, Chung-Lin Chung, Hsiang-Lin Hsu, Chih-Ping Chen
Methoxy substituents effect in triphenylamine dibenzofulvene based hole transporting materials for dopant free p-i-n perovskite solar cells
Md. Shahiduzzaman, Ashish Kulkarni, Masahiro Nakano, Makoto Karakawa, Kohshin Takahashi, Shinjiro Umezu, Atsushi Masuda, Satoru Iwamori, Masao Isomura, Koji Tomita, Tsutomu Miyasaka, Tetsuya Taima
Brookite TiO2 Nanoparticle Bridge Boosts the Stability of Perovskite Solar Cells
Thibault Lemercier, Lara Perrin, Emilie Planes, Solenn Berson, Lionel Flandin
Inverted Perovskite Solar Cells: Influence of Anti-Solvent Nature and Dripping Time on Perovskite Layer Properties and Uniformity
Nilesh Manwar, SumanLata Jain, Nitin Labhasetwar
Crystallization and Impact of B-site metal cation substitution of Lead Free Organic-Inorganic Cu (II) Perovskites structure and its optical properties
Issei Takenaka, Motoshi Nakamura, Yoshinori Kimoto, Yuta Higashino, Hiroki Sugimoto, Naoyuki Shibayama, Chie Nishiyama, Keishi Tada, Takeru Bessho, Hiroshi Segawa
Room-Temperature Sputtered SnO2 Thin Film as an Electron Transport Layer for Mixed-Cation Planar Heterojunction Perovskite Solar Cells
Ching Chang Lin, Takurou N. Murakami, Masayuki Chikamatsu, Takeru Bessho, Hiroshi Segawa
A Facile Ionic Compound Modification of SnO2 ETL to Enhance the Performance Perovskite Solar Cell
Ryuji Kaneko, Joe Otsuki, Md. Khaja Nazeeruddin, Ashraful Islam
Surface Modified NiOx Nanoparticles as Hole Transport Materials in n-i-p Structured Perovskite Solar Cells
Shuzhang Yang, Zhanglin Guo, Liguo Gao, Tingli Ma
Bifunctional Dye Molecule in All-Inorganic CsPbIBr2 Perovskite Solar Cells with Efficiency Exceeding 10%
Liang Wang, Shuzhang Yang, Fengjing Liu, Chao Jiang, Tingli Ma
A New Strategy of Methylamine Iodide Solution Assisted Repair for Pinhole-Free Perovskite Films in High-Efficiency Photovoltaic under Ambient Conditions
Takeyuki Sekimoto, Michio Suzuka, Tomoyasu Yokoyama, Yoshiko Miyamoto, Ryusuke Uchida, Maki Hiraoka, Kenji Kawano, Takashi Sekiguchi, Yukihiro Kaneko
Inverse Temperature Crystallization of Formamidinium Tin Iodide
Masatoshi Yanagida, Namrata Pant, Yasuhiro Shirai, Kenjiro Miyano
RF Sputtered NiOx as Hole Transport Layer for CH3NH3PbI3 Perovskite Solar Cell
Takashi Koida, Hitoshi Sai, Jiro Nishinaga
High-Mobility Transparent Conductive Oxide Films Fabricated under Low-Energy Ion Bombardment at Low Temperature
Chao Ding, Xing Lin, Feng Liu, Yaohong Zhang, Daisuke Hirotani, Taro Toyoda, Shuzi Hayase, Takashi Minemoto, Taizo Masuda, Kenji Katayama, Qing Shen
Photoexcited Hot and Cold Electron and Hole behavior at FAPbI3 Perovskite Quantum Dots/Metal Oxide Heterojunctions: Hot versus Cold Charge‐relaxation and transfer
Kentaro Kawabata, Feng Liu, Chao Ding, Yaohong Zhang, Qing Shen, Shuzi Hayase, Taro Toyoda
Colloidal Synthesis of Air-Stable Alloyed CsSn1−xPbxI3 Perovskite Nanocrystals for Use in Solar Cells
Dong Liu, Yaohong Zhang, Naoki Nakazawa, Chao Ding, Feng Liu, Taro Toyoda, Shuzi Hayase, Qing Shen
The Interparticle Distance Limit for Multiple Exciton Dissociation in PbS Quantum Dot Solid Films
Gayathri Mathiazhagan, Lukas Wagner, Shankar Bogati, Kübra Yasaroglu Ünal, Thomas Kroyer, Simone Mastroianni, Andreas Hinsch
Double-Mesoscopic HTM-Free Perovskite Solar Cells: Overcoming Charge Transport Limitation by Sputtered 40 nm Al2O3 Isolation Layer
Daisuke Aoki, Hidenori Saito, Tomoyuki Tobe, Shinichi Magaino
Steady-state Measurement of Maximum Power for Perovskite Solar Cell
Rojas Tarazona Fredy Enrique, Diaz-Granados Fabian, Méndez Henry, Salcedo Juan Carlos, Rodríguez Hernán, Mejía Augusto, Jiménez Luis Camilo
Optical and Electrical Properties of Organic Solar Cell prototype Based on P3HT:PCBM
Hidenori Saito, Daisuke Aoki, Tomoyuki Tobe, Shinichi Magaino
Development the Measurement Method for Maximum Power of Metastable Perovskite Solar Cells.
Nobuko Onozawa-Komatsuzaki, Yoshihiko Nishihara, Masayuki Chikamatsu, Yuji Yoshida
Effect of FABr Passivation on the Interface of Perovskite/hole-transporting Layer on Perovskite Solar Cells with Donor-Acceptor Conjugated Polymer
Tetsuhiko Miyadera, Yuto Auchi, Kohei Yamamoto, Noboru Ohashi, Tomoyuki Koganezawa, Hiroyuki Yaguchi, Yuji Yoshida, Masayuki Chikamatsu
Crystal Growth Control and Real-Time Analysis of Organolead-Halide Perovskite
Seojun Lee, Saemon Yoon, Jun Ryu, Dong-Won Kang
Additive Engineering of Sn-based Perovskites for Efficient Pb-free Solar Cells
Koichiro Kamimori, Koki Suwa, Takeo Suga, Kenichi Oyaizu, Hiroshi Segawa, Hiroyuki Nishide
Metal-dopant-free Hole-transporting Poly(triarylamine)s for a Durable Perovskite Solar Cell
DONG XUE, Shinpei Kamiya, Masahiko Saito, Itaru Osaka, Kazuhiro Marumoto
Direct Evidence of Less Charge Accumulation in Highly Durable Polymer Solar Cells Using Operando ESR Spectroscopy
Yue Qi, Takahiro Kawaguchi, Yuna Suzuki, Tomoyoshi Suenobu, Kensuke Kojima, Jun Azuma, Mitsuharu Suzuki, Ken-ichi Nakayama
Ternary Organic Solar Cells Based on Two Perylenediimide-based Acceptors
Marika Owada, Koki Suwa, Takeo Suga, Kenichi Oyaizu, Hiroshi Segawa, Hiroyuki Nishide
Perovskite Layer Formation by a Co-evaporation Method and its Application for Surface Modification
Itaru Raifuku, Ming-Hsien Li, Yu-An Chen, Peter Chen
Preparation of 2D/3D Hybrid Perovskite Films Via Low Pressure Vapor Assisted Solution Process and its Optical Characterization
Mako Nakamura, Chao Ding, Yaohong Zhang, Feng Liu, Taro Toyoda, Shuzi Hayase, Qing Shen
Suppression of Charge Recombination of PbS Quantum Dots/ZnO Nanowires Heterojunction Solar Cells by Interface Passivation
Bhaskar Parida, Seojun Lee, Saemon Yoon, Jun Ryu, Dong-Won Kang
Solution-Processed Aluminum-Doped Nickel Oxide Hole Collectors for Highly Efficient Planar Perovskite Solar Cells
Ryota Jono, Hiroshi Segawa
Structure-Bandgap Relation on the Lead Halides based Perovskite Materials
Dong-Gun Lee, Jun Ryu, Saemon Yoon, Dong-Won Kang
One-Step Fabrication Process of CsPbBr3 Inorganic Perovskite Solar Cells
Namrata Pant, Masatoshi Yanagida, Yasuhiro Shirai, Kenjiro Miyano
Importance of Surface Treatment to Enhance the Efficiency of Undoped sp-NiOx Based Perovskite Solar Cells
Kohei Kuwano, Yasuyuki Watanabe, Masayuki Chikamatsu, Yuji Yoshida, Eiichi Nishikawa
Semitransparent Organic Photovoltaic Cells Based on Long-wavelength Infrared Semiconductor Layer
Ganbaatar Tumen-Ulzii, Toshinori Matsushima, Dino Klotz, Chuanjiang Qin, Chihaya Adachi
Long-term Stable Perovskite Solar Cells under 1000 Hours Continuous Illumination
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