Photo/Thermo‐Triggered Self‐Healing Mechanism Enabling Highly Efficient and Stable Perovskite Solar Cells

ABSTRACT Perovskite solar cells (PSCs) face operational stability challenges due to dynamic interfacial stress accumulation and defect regeneration under photo‐thermal stresses. Here, we introduce a photo/thermo‐responsive dynamic molecule, 5‐sulfosalicylic acid (5‐SAS), to construct an intelligent adaptive interface. 5‐SAS undergoes reversible solid–liquid transitions: in its molten state, it diffuses to repair grain boundaries and fill voids; upon cooling, it resolidifies into a flexible buffer layer, enabling dynamic self‐healing and stress relaxation. Unlike static passivation methods, our strategy enables continuous defect repair during operation, addressing the trade‐off between efficiency and stability. This physical healing mechanism synergizes with its multi‐dentate ligand coordination chemistry (sulfonic acid, carboxyl, and phenolic hydroxyl groups), which passivates undercoordinated metal ions and defects. The champion device achieves a record PCE of 26.23% with an FF of 85.93%, retaining over 91% of its initial PCE after 1500 h of continuous operation and light‐soaking aging. This work validates a novel self‐healing strategy to address PSCs stability bottlenecks.