Perovksite solar cells are an important new technology for photovoltaic energy conversion. High conversion efficiencies exceeding 20% have been achieved in this material. However, the devices suffer from several different degradation mechanisms-thermal, environmental and light-induced. In this talk, I will discuss the physics of perovskite solar cells and each of the instabilities with particular emphasis on light-induced degradation. I will show that ions are responsible for light-induced degradation. I will also show that there are two distinct instabilities, one related to generation of ions by light within the material, and one related to the trapping of ions at the interfaces. I will also show how ions can degrade the ohmic contacts to the device, and how to prevent this degradation.
Vikram Dalal is Distinguished Professor of Engineering at Iowa State University in the U.S. He is a Fellow of IEEE, American physical Society and American Association for the Advancement of Science, having been recognized by all three organizations for the excellence of his research on thin film PV materials and devices. He has published nearly 200 articles in journals and refereed proceedings, and has graduated 33 Ph.D. students and 40 M.S. students. He got his B.E.(Elec.) degree from VJTI in 1964 and Ph.D. in EE from Princeton University in 1969. He also holds a M.P.A. in Economics from Princeton.