UV-ozone passivated semi-transparent inorganic perovskite solar cells achieving 5.44% light utilization efficiency

The trade-off between high visible transmittance and high photoelectric conversion efficiency poses a great challenge in the development of high-performance semi-transparent solar cells, which ultimately limits their light utilization efficiency (LUE) and practical deployment. Inorganic perovskite CsPbBr₃ is a promising candidate for semi-transparent perovskite solar cells (ST-PSCs) owing to its wide bandgap and naturally high average visible transmittance (AVT > 40%). However, the relatively low power conversion efficiency (PCE) of semi-transparent CsPbBr₃ devices has hindered the improvement of their LUE. Herein, a UV-ozone passivation strategy is proposed for depositing high-quality perovskite films. Undercoordinated Pb²⁺ in the perovskite is effectively passivated by introduced oxygen atoms, forming stable Pb-O bonds, which reduce the defect-state density and related nonradiative recombination. Consequently, the optimized device achieved a record PCE of 9.42% among all reported CsPbBr₃ ST-PSCs. Combined with the high AVT of 57.74%, the device delivers a remarkable LUE (5.44%) for semi-transparent photovoltaics without complex optical regulation. Furthermore, the unencapsulated devices demonstrated excellent operational stability, maintaining 92.2% of their initial efficiency after 500 h under continuous 1-sun illumination. This study provides available guidance for effective passivation without residue and realizes highly efficient, stable and cost-effective all-inorganic ST-PSCs suitable for different applications.