Critical role of interface contact modulation in realizing low-temperature fabrication of efficient and stable CsPbIBr2 perovskite solar cells

Abstract

CsPbIBr2 perovskite solar cells (PSCs) have received considerable concern due to their excellent stability. However, the interface defects and imperfect band alignment between electron transporting layer (ETL) and perovskite is one of the main reasons for hindering further efficiency improvement. Herein, we modulate the band alignment and perovskite crystallization of the ETL/perovskite interface by employing ZnO and SnO2 as ETL, which exhibit high electron mobility and can be fabricated at low temperature. Both ZnO and SnO2-based devices were fabricated at low temperature below 160℃. First, the effect of ZnO and SnO2 on the performance of CsPbIBr2 PSCs is systematically investigated. SnO2-based PSCs show a higher power conversion efficiency (PCE) of 10.81% as a consequence of improved Voc and fill factor (FF) as compared to 9.70% of ZnO counterpart, which is attributed to improved band alignment and perovskite crystallization, leading to enhanced electron extraction, reduced interface nonradiative recombination and improved carrier lifetimes. Remarkably, SnO2 ETL can also reduce hysteresis and improve device stability as compared to ZnO ETL. The present study unveils the critical role of interface contact modulation of CsPbIBr2 PSCs and provides an insightful strategy for preparing efficient and stable low-temperature inorganic PSCs.