Enabling Photostable Perovskite Solar Cells via Sustainable Operando Defect‐Passivation Strategy

Abstract The amount of passivator is usually optimized for freshly prepared devices, which is static and short‐term. However, photoinduced defects and the movement of halogen ions are dynamically generated in real time. Long‐term operational passivation, designed to address the dynamic characteristics of defect generation, is largely overlooked but is critically important. In this work, a classical photochromic compound, Spiro‐oxazine (SO), is introduced to develop a sustainable operando passivation strategy. The two configurations of this isomer fulfill different requirements: the normal form addresses the needs of freshly prepared devices with fewer defect passivation requirements, while the post‐isomeric form in situ operando captures light‐induced defects during operation, enabling sustainable passivation. As a result, the perovskite solar cell (PSC) fabricated using this operando strategy achieved an excellent power conversion efficiency (PCE) of 24.72%, with an open‐circuit voltage (V OC ) of 1.215 V, and demonstrated remarkable stability, retaining 82% of its initial PCE after 1580 h under simulated sunlight and 80% after 144 h under UV light. Large‐area PSC modules fabricated using the proposed strategy achieved a PCE of 19.07% over an active area of 61.6 cm 2 . This work provides valuable guidance for designing self‐healing perovskite films and highlights the urgent need for improved passivation durability.