Doping engineering of ZnO electron transporting layer for high performance CsPbI2Br inorganic perovskite solar cells

Abstract

An inorganic CsPbI2Br perovskite has garnered significant interest due to its outstanding photoelectrical properties in recent years. However, CsPbI2Br-based perovskite solar cells (PSCs) generally suffer from large energy loss, hindering their further development. Herein, we proposed a facile and effective approach to dope the ZnO electron transporting layer (ETL) with alkaline earth metal ions to boost the photovoltaic performance of CsPbI2Br PSCs. Particularly, the ZnO ETL doped with Ca2+ can simultaneously ameliorate electron transport, energy level alignment, and the quality of the upper CsPbI2Br film, thus resulting in faster charge extraction and suppressed charge recombination. Consequently, the ZnO:Ca-based PSC achieves a champion power conversion efficiency (PCE) of 16.39% with an excellent VOC of 1.292 V, while the control ZnO-based PSC just exhibits an inferior PCE of 14.22% with a VOC of 1.178 V. Furthermore, the ZnO:Ca-based devices also present considerable enhancements in device stability without encapsulation. Our work offers a promising strategy to mitigate the energy loss toward efficient and stable PSCs.