KF-Doped SnO2 as an electron transport layer for efficient inorganic CsPbI2Br perovskite solar cells with enhanced open-circuit voltages

Tin oxide (SnO2) has recently emerged as a promising electron transport layer (ETL) for all-inorganic perovskite solar cells (PVSCs) owing to its excellent optical and electrical properties. However, the defects of the perovskite film and the mismatch of the energy levels between the SnO2 ETL and the perovskite film result in an increased energy loss (E-loss) which therefore leads to PVSCs with reduced open-circuit voltages (V(OC)s) and efficiencies. Herein, we demonstrate the use of KF-doped SnO2 as an ETL for high efficiency all-inorganic CsPbI2Br PVSCs. Through KF doping, the conduction band of the SnO2 film can be regulated to better match that of the perovskite film thereby enhancing the electron mobility and the V-OC of the corresponding PVSCs. In addition, fluorine ions from the ETL can migrate to the bottom of the perovskite layer and passivate the interface between the ETL and the perovskite layer. As a result, the V-OC of PVSCs increases from 1.18 V to 1.31 V and the power conversion efficiency (PCE) of the resulting PVSCs increases from 13.40% to 15.39%. This facile defect passivation strategy on the ETL should be valuable for fabricating PVSCs with enhanced performance.

Automated summary

KF-doped SnO2 is used as an ETL to enhance the performance of CsPbI2Br PVSCs, improving electron mobility and V-OC through regulation of the conduction band of SnO2 film and passivation of the interface with fluorine ions, resulting in increased V-OC and PCE of PVSCs.