Multifunctional Compound‐Regulated SnO2 for High‐Efficiency and Stable Perovskite Solar Cells under Ambient Air

Abstract Perovskite solar cells (PSCs) fabricated with a low‐temperature (≤150 °C) SnO 2 ‐based electron transport layer (ETL) have been rapidly developing and demonstrate high power conversion efficiency (PCE). To further enhance the efficiency and stability of PSCs, high‐quality perovskite and SnO 2 films are needed, and the interfacial performance between the SnO 2 ETL and the perovskite layer needs to be improved. In this work, potassium p ‐aminobenzoate (KPAB) was introduced to regulate the SnO 2 ETL to obtain reduced defects and an excellent wetting property, inducing vertically aligned crystal growth of the perovskites on the interface side of the SnO 2 ETL. In addition, the potassium ions were able to interact with the halogen ions of the perovskite, which further enhanced the quality of the perovskite film. Due to the abovementioned strengths of KPAB, we demonstrated that devices based on KPAB‐SnO 2 have a higher power conversion efficiency (19.03 %), better reproducibility, and superior operational stability compared to devices with pristine SnO 2 .