Improve the oxide/perovskite heterojunction contact for low temperature high efficiency and stable all-inorganic CsPbI2Br perovskite solar cells

Oxide/perovskite heterojunction contact is important for realizing high performance and stable perovskite solar cells (PSCs). However, the development of ZnO/perovskite heterojunction contact is plagued by the poor chemical compatibility at ZnO/organic-inorganic perovskite interface. Nevertheless, the ZnO/inorganic perovskite heterojunction contact exhibits potential applications in all-inorganic PSCs. In this study, all-inorganic CsPbI2Br PSCs based on ZnO/perovskite heterojunction contact have been successfully realized at low temperature process below 150 °C and delivered an excellent power efficiency conversion of 14.78% with a high open-circuit voltage (Voc) of 1.21 V and a truly extraordinary fill factor (FF) of 81.42%. Compared to SnO2-based PSCs, the better band alignment between ZnO ETL and perovskite contributed larger built-in potential, resulting in superior electron extraction capability and effective interfacial recombination suppression. The better perovskite film quality and improved interface contact of ETL/perovskite contributed to better air and thermal stability of ZnO-based perovskite devices. These researches have proved the unlimited possibilities for ZnO as ETL in all-inorganic perovskite solar cells.