Synergistic Interfacial Lewis‐Base Interactions Enable Wide‐Bandgap Semitransparent Perovskite Solar Cells with 4.19% Light‐Utilization Efficiency and Enhanced Stability

. Consequently, the MSOT-treated perovskite films exhibit enlarged grain sizes and significantly improved morphology. As a result, the corresponding semitransparent devices achieve a power conversion efficiency (PCE) of 12.79%, an average visible transparency (AVT) of 32.79%, and a light-utilization efficiency (LUE) of 4.19%. More importantly, the unencapsulated devices retain 90.1% of their initial efficiencies after 1200 h of continuous illumination under an open-circuit configuration at 60°C (ISOS-L-2I), demonstrating their exceptional operational stability. This work offers a facile approach to improving the film quality of wide-bandgap perovskites through the use of a multifunctional interfacial modulator, enabling the development of high-performance semitransparent solar cells for building-integrated photovoltaics.