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

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 cm². This work provides valuable guidance for designing self-healing perovskite films and highlights the urgent need for improved passivation durability.