Synergistic Interface Stabilization and Dynamic Defect Passivation for High‐Performance Ultraviolet‐Stable Perovskite Solar Cells

Despite major efficiency breakthroughs in inverted perovskite solar cells (PSCs), their stability under ultraviolet (UV)-induced degradation remains challenging because photoinduced defect accumulation in the perovskite and deterioration of the buried ITO/SAM/perovskite interface occur simultaneously under illumination. We develop a bulk/interface synergistic stabilization strategy by combining dynamic perovskite defect regulation with buried-interface reinforcement. The photoisomerizable molecule 1,3,3-trimethylindolino-6'-bromobenzopyrylospiran (TIBBP) serves as a dynamic passivator. It responds to light and reversibly transitions from a closed form to an open form, enabling a continuous functional pathway from film formation to device operation. The closed form regulates crystallization and initial defects, while the UV-induced open form generates multiple active sites for passivating newly formed defects. To strengthen the buried hole-transport interface, [4-(3,6-difluoro-9H-carbazol-9-yl)phenyl]phosphonic acid (F-PhPACZ) is designed as a UV-durable SAM. The conjugated backbone improves SAM chemical stability and ITO anchoring under UV stress, while fluorine-related interactions contribute to buried-interface passivation and improved perovskite growth. By simultaneously suppressing perovskite defect evolution and buried-interface degradation, the inverted PSC achieves a power conversion efficiency of 27.18% (certified 26.65%) and markedly improved stability under UV irradiation, air exposure, and thermal aging. This work provides a device-failure-pathway-oriented strategy for efficient and stable inverted perovskite photovoltaics.