Amphoteric Ion Bridged Buried Interface for Efficient and Stable Inverted Perovskite Solar Cells

Abstract Synergistic morphology and defects management at the buried perovskite interface are challenging but crucial for the further improvement of inverted perovskite solar cells (PerSCs). Herein, an amphoteric organic salt, 2‐(4‐fluorophenyl)ethylammonium‐4‐methyl benzenesulfonate (4FPEAPSA), is designed to optimize the film morphology and energy level alignment at the perovskite buried interface. 4FPEAPSA treatment promotes the growth of a void‐free, coarse‐grained, and hydrophobic film by inducing the crystal orientation. Besides, the dual‐functional 4FPEAPSA can chemically interact with the perovskite film, and passivate the defects of iodine and formamidine vacancies, tending to revert the fermi level of perovskite to its defect‐free state. Meanwhile, the formation of a p‐type doping buried interface can facilitate the interfacial charge extraction and transport of PerSCs for reduced carrier recombination loss. Consequently, 4FPEAPSA treatment improves the efficiency of the perovskite devices to 25.03% with better storage, heat, and humidity stability. This work contributes to strengthening the systematic understanding of the perovskite buried interface, providing a synergetic approach to realize precise morphology control, effective defect suppression, and energy level alignment for efficient PerSCs.