16:30 〜 16:45
▲ [11p-N322-13] Suppressing hysteresis effect in lead-free tin halide perovskite solar cells through incorporation of large A-site cation
キーワード：Lead-free, A-site cation, Perovskite solar cells
Tin halide perovskites are the fore-front contender for lead-free perovskite solar cells. Currently the highest efficiency now reaching 13 % which is the highest among other types of lead-free perovskites. There are several issues with tin halide perovskites that need to be address before they can really compete with lead-based perovskite solar cells. Among the issues are oxidation of easy oxidation of Sn2+ into Sn4+ in air, fast crystallization leading to uneven surface and pinholes formation, large energy mismatch between commonly used charge transport layers, and current-voltage hysteresis issue due to unbalanced charge carrier transport and ion migration. In this experiment, we incorporated Cs+ which is a large A-site cation to reduce the hysteresis effect. Although this has been explored previously even in tin halide perovskite solar cells, we showed that Cs incorporation alone will not improve the performance, however when used simultaneously with surface passivation and using [6,6]-Phenyl-C61 butyric acid butyl ester (PCBM) as the electron transport layer, we managed to improve the performance to more than 13 %. In terms of current-voltage hysteresis, upon Cs incorporation, forward and reverse current-voltage scan showed smaller discrepancy. To understand this phenomenon, we used impedance spectroscopy analysis to evaluate the charge transport mechanism. We attribute this suppressed hysteresis effect due to balanced charge carrier transport in the device. This observation has been supported by Transient Absorption spectroscopy measurement. This work will hopefully provide a reference for other researchers to further expand the field of tin perovskite research.