Multifunctional amphiphilic molecule tailors the buried interface for highly stable perovskite solar cells

Enhancing the efficiency and stability of perovskite solar cells is critical for commercialization. As short-circuit density approaches the Shockley-Queisser limit, improving open-circuit voltage and fill factor becomes essential, achievable through interface engineering. SnO 2 , employed as a buried electron transport layer, not only influences the deposition of perovskite film but also poses significant stability. Here, we introduce a multifunctional amphiphilic molecule, hydroxyl-terminated perfluoroalkyl sulfonamide, into the buried interface. The C-F long chain facilitates hydroxyl groups anchoring on the SnO 2 surface, while the sulfonyl groups occupy oxygen vacancies, thereby reducing undercoordinated Sn 4+ . Simultaneously, the sulfonyl groups interact with uncoordinated Pb 2+ in the adjacent perovskite film, further suppressing interfacial defects. This strategy yields a champion power conversion efficiency of 23.26%. Moreover, the long C-F chains act as a hydrophobic barrier against moisture ingress, enabling the unencapsulated devices to retain 73.8% of initial PCE after 1320 h under ambient condition (50%-60% relative humidity), while only 69.4% for reference one. Furthermore, post-treatment with quaternary ammonium iodide creates a dual-passivated interface. This suppresses halide ion migration and photoinduced phase segregation, boosting the PCE to 24.64%. These results underscore the critical role of multifunctional organic molecular passivation at interface in achieving both high-performance and durable perovskite photovoltaics.