Associate Prof Hideo Ohkita and his collaborators at Kyoto University have succeeded in developing perovskite solar cells with different grain sizes of CH3NH3PbI3 crystals, which exhibit a high power conversion efficiency of more than 19% and small hysteresis. By analyzing the photovoltaic properties in details, they found that the photocurrent generation efficiency is almost 100% for all the grain sizes and that the open-circuit voltage (Voc) increases because of the less trap-assisted recombination in the larger gain sizes. If the trap density were reduced to less than 1013 cm-3 as reported for single crystalline perovskites, the Voc would be further improved to ~1.27 V, which is close to the theoretical limit. Our finding suggests that CH3NH3PbI3 perovskite solar cells have potential to exhibit the theoretical limit voltage as well as the 100% efficient photocurrent generation.
Research Area “Photoenergy conversion systems and materials for the next generation solar cells”
Research Theme “Specrtoscopic exploration of photon-electron conversion mechanisms in polymer solar cells”
Hyung Do Kim, Hideo Ohkita, Hiroaki Benten, and Shinzaburo Ito. “Photovoltaic Performance of Perovskite Solar Cells with Different Grain Sizes”. Advanced Materials, Published online 7 December 2015, doi: 10.1002/adma.201504144.
Hideo Ohkita, Ph.D.
Associated Professor, Graduate School of Engineering, Kyoto University
Sofia Saori Suzuki
Green Innovation Group, Department of Innovation Research, JST