Multifunctional Passivator Enables High-Efficient Gas-Quenching Sn–Pb Perovskite Solar Cells

Tin–lead (Sn–Pb) perovskites deliver ideal bandgaps (∼1.25 eV) for both single-junction and tandem photovoltaics; however, their rapid crystallization kinetics and Sn2+ oxidation vulnerability propagate severe defect densities that limit efficiency and stability. Herein, we design a multifunctional passivator, n-dodecylammonium acetate (DOAAc), in which acetate anions (Ac–) simultaneously passivate halide vacancies and coordinate undercoordinated surface Pb2+/Sn2+ sites. Consequently, DOAAc demonstrated superior passivation efficacy, enhanced interfacial binding strength, and exceptional oxidation resistance. XPS validation reveals that surface Sn4+ content reduces from 24.41% to 8.62% with DOAAc treatment. Transient ion migration measurements further show a 4.5-fold reduction in mobile ion density, while XPS/FTIR analyses confirm robust complex-induced interfacial adhesion. UPS/SCLC/TRPL collectively verifies optimized energy-level alignment, reduced trap density, and enhanced carrier dynamics. Finally, DOAAc-passivated Sn–Pb PSCs achieve a record efficiency of 23.33% for gas-quenching fabricated devices. Under continuous AM 1.5G illumination (65 °C, xenon lamp), T80 lifetime is extended by nearly 2-fold compared to the control devices.