Dual Passivation of SnO2 by Tetramethylammonium Chloride for High-Performance CsPbI2Br-Based Inorganic Perovskite Solar Cells

Here, the modification of the SnO2 electron transport layer (ETL) by tetramethylammonium chloride (TMACl) is described. The theoretical and experimental studies in this work demonstrate that TMA and Cl ions complementarily passivate the oxygen vacancies on the surface of SnO2 ETL, while TMACl passivation also contributes to increase the conduction band edge of SnO2 by reducing the work function. As a result, the charge carrier recombination and electron transfer/extraction behaviors at the interface of CsPbI2Br and SnO2 ETL are significantly improved, leading to inorganic perovskite solar cells with efficiencies of up to 13.84% and 28.68% under 1-sun illumination and indoor lighting, respectively. TMACl-passivated SnO2 also boosts the operative stability of the device under humidity and thermal stress, which reveals the potential of TMACl as a promising passivation agent of SnO2 for high-performance perovskite optoelectronics.