TODAY at 10 am! Please post and forward to your groups. CENTER FOR EXCITONICS - PEROVSKITE SEMINAR SERIES PRESENTS: Accelerated testing of organic and perovskite photovoltaics using concentrated sunlight* December 21, 2016 at 10 am in rm: 36-462 Eugene A. Katz Ben-Gurion University of the Negev, Israel/Dept. of Solar Energy and Environmental Physics/ J. Blaustein Institutes for Desert Research, Ilse-Katz Institute for Nanoscale Science and Technology [katz] A significant challenge en route to commercialization of such novel photovoltaic (PV) technologies as organic PV (OPV) and perovskite-based solar cells is the development of devices combining high efficiency and operational stability. While the efficiency can be measured within seconds, the timescale for stability assessment may be of the order of months or years, raising the need for relevant accelerated stability tests. We suggested to use concentrated sunlight for accelerated studies of OPV degradation [1] and demonstrated experimental methodology that allows an independent control of light intensity (up to 4,000 suns) and the sample temperature during the exposure [2]. This allows to study various routs of OPV degradation [3] and to separate light induced mechanisms from those controlled just by the cell temperature. Recently, we used this experimental approach for study of photochemical stability of halide perovskites MAPbX3 films (X = I or Br) [4] and their solid solutions MAPb(I1-xBrx)3 [5]. The relevance of accelerated testing to standard operational conditions of solar cells was confirmed by comparison to degradation experiments under outdoor sunlight exposure. We found that MAPbBr3 films exhibited no degradation, while MAPbI3 and mixed halide films decomposed yielding crystallization of inorganic PbI2 accompanied by degradation of the perovskites' solar light absorption. The rate of such decomposition was found to depend on light intensity, the halide content and the exposure temperature. The crystal coherence length was found to correlate with the stability of the films. 1. T. Tromholt, et al, A. Appl. Phys. Lett. 96, 073501 (2010); A. Manor, E. A. Katz, T. Tromholt and F. C. Krebs. Adv. Energy Mater., 1, 836 (2011). 2. I. Visoly-Fisher, et al, Sol. Energy Mater. Sol. Cells, 134, p. 99-107 (2015). 3. Y. Galagan, et al, Phys. Chem. Chem. Phys., 17, 3891 (2015); 94; E.A. Katz, et al, Sol. Energy Mater. Sol. Cells, 144, 273 (2016).. 4. R. K. Misra, et al, J. Phys. Chem. Lett., 6, 326 (2015). 5. R. K. Misra, et al,. ChemSusChem, 9, 2572 (2016). Eugene A. Katz received his MSc degree in Semiconductor Materials Science in 1982 and Ph. D. in solid state physics in 1990 from the Moscow Institute of Steel and Alloys. He has research experience in field of photovoltaic materials and devices for more than 30 years. The topic of his Ph. D. thesis was "Atomic structure and electronic properties of grain boundaries in polycrystalline silicon solar cells". In 1995, he joined the Ben-Gurion University of the Negev and has been working in the Department for Solar Energy and Environmental Physics ever since (now as a full professor). His research interests include areas of applied solar energy, photovoltaics based on non-traditional semiconductors (fullerenes, nanotubes, conjugated polymers, perovskites), photovoltaic characterization of AIIIBV concentrator solar cells at ultra-high concentration of natural sunlight (up to 10,000 suns) and synthesis of nanomaterials by concentrated sunlight. He has published more than 100 peer-reviewed papers on these topics. In addition, has published a book and articles for broader audiences on the history of science and fullerene-like structures in nanomaterials, living organisms and architecture. *This talk is part of the Perovskites Seminar Series organized by Juan-Pablo Correa-Baena and sponsored by the Center for Excitonics. For more info contact Juan-Pablo: jpcorrea@mit.edu<mailto:jpcorrea@mit.edu> The Center For Excitonics Is An Energy Frontier Research Center Funded By The U.S. Department Of Energy, Office Of Science And Office Of Basic Energy Sciences