Enhanced Buried Interface Engineering for Efficient Inverted Perovskite Solar Cells Fabricated via Vapor–Solid Reaction

Abstract Vapor‐deposited inverted perovskite solar cells utilizing self‐assembled monolayer (SAM) as hole transport material have gained significant attention for their high efficiencies and compatibility with silicon/perovskite monolithic tandem devices. However, as a small molecule, the SAM layer suffers low thermal tolerance in comparison with other metal oxide or polymers, rendering poor efficiency in solar device with high‐temperature (> 160 °C) fabricating procedures. In this study, a dual modification approach involving AlO _x and F‐doped phenyltrimethylammonium bromide (F‐PTABr) layers is introduced to enhance the buried interface. The AlO _x dielectric layer improves the interface contact and prevents the upward diffusion of SAM molecules during the vapor–solid reaction at 170 °C, while the F‐PTABr layer regulates crystal growth and reduces the interfacial defects. As a result, the AlO _x /F‐PTABr‐treated perovskite film exhibits a homogeneous, pinhole‐free morphology with improved crystal quality compared to the control films. This leads to a champion power conversion efficiency of 21.53% for the inverted perovskite solar cells. Moreover, the encapsulated devices maintained 90% of the initial efficiency after 600 h of ageing at 85 °C in air, demonstrating promising potential for silicon/perovskite tandem application.