Hole transporting material with passivating group (C[tbnd]N) for perovskite solar cells with improved stability

Abstract

Defects passivation of the perovskite/hole transporting materials (HTM) interface has been proved as an effective way to improve the performance of perovskite solar cells (PSCs). Among the reported passivation chemicals, cyano (CN) functional group has been widely used to passivate interstitial or undercoordinated Pb2+. In this work, we introduce CN unit into facile carbazole-triphenylamine molecule (H123) and expect to obtain the HTM which own the dual function of passivating defects and transporting holes. A reference HTM without CN unit (H122) is also prepared for a comparative study. Despite that the introduction of CN on HTM exhibit minor difference on their optical absorption and energy levels, upon applying these compounds as HTM in PSCs, their device performance is noted to sensitively depend on the existence of CN. It is noted that CN-based HTM show relatively higher power-conversion efficiency and minor hysteresis compared with non-CN counterpart. Promisingly, the device with CN-based HTM exhibit substantively improved stability compared with that of non-CN counterpart and conventional spiro-OMeTAD. The study gives an insight for design ideal HTMs for high-performance PSCs.