Modulated growth of high-quality CsPbI3 perovskite film using a molybdenum modified SnO2 layer for highly efficient solar cells

Abstract

The electron transport layer (ETL) plays a critical role in charge extraction and perovskite thin film growth in planar n–i–p heterojunction perovskite solar cells. Herein, we modulated the nucleation and growth rate of CsPbI₃ crystals by using a Mo doping strategy to synthesize high-quality SnO₂ crystals as an ETL nano-film in n–i–p heterojunction perovskite solar cells. We revealed that such a nano-film with low surface energy and high roughness induced by Mo doping provides seed-like nucleation sites for CsPbI₃ inorganic perovskite growth, leading to improved perovskite film morphology. The charge extraction at the ETL/perovskite interface is also enhanced due to the improved energy level alignment. As a result, a high power conversion efficiency of 17.41% can be achieved under one sun irradiation for a planar n–i–p heterojunction structured CsPbI₃ solar cell by using this novel Mo–SnO₂ ETL. This work provides a simple pathway to simultaneously modulate CsPbI₃ inorganic perovskite crystallization and interfacial charge extraction in planar heterojunction perovskite devices.