Dual Interfacial Tin-Oxide Layer with Chloride Salt for High-Performance and Durable Perovskite Solar Cells

A tailored SnO2 layer using double electron transport layers (ETLs) was designed to overcome interfacial energy barriers, enhance charge transport, and decrease charge recombination at the perovskite/ETL interfaces. Through this dual interfacial engineering approach, compact SnO2 layers with an
ideal interfacial energy-level alignment were prepared using SnCl2 and NH4Cl salts, leading to efficient charge extraction. Stable perovskite solar cells with a power conversion efficiency of 21.46%, a high open-circuit voltage of 1.10 V, and a fill factor of 0.79 were successfully achieved using this approach. The devices also
exhibited negligible hysteresis and no significant efficiency loss after a 2400 h stability test at ambient conditions without encapsulation. These results demonstrate an efficient approach to achieving high-quality ETL layers for efficient and stable solar cells.