Synergistic Interfacial Lewis-Base Interactions Enable Wide-Bandgap Semitransparent Perovskite Solar Cells with 4.19%...

Wide-bandgap (WBG) perovskites hold significant promise for semitransparent solar cells. However, their high bromide content accelerates perovskite crystallization rate, typically resulting in small grains, suboptimal film morphology, and elevated defect densities. Here, we introduce a facile strategy that employs 2-(methylsulfonyl)thiophene (MSOT) as a multifunctional interfacial modulator to produce high-quality perovskite films for high-performance semitransparent solar cells. MSOT contains a thiophene cation and a sulfonyl group, both of which can act as Lewis bases to coordinate with Pb²⁺. 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.