Dynamic Molecular Scaffold Enables Thermomechanical Stress Regulation and Adaptive Defect Healing for Stable Perovskite Solar Cells

Thermally induced stress accumulation is a major origin of lattice disorder, defect evolution, and ion migration in perovskite solar cells (PSCs), limiting their long‐term operational stability. We develop a dynamic molecular scaffold strategy based on the adduct of α‐lipoic acid and N‐hydroxysuccinimide ester to mitigate thermomechanical degradation through simultaneous thermomechanical stress buffering, lattice anchoring, and adaptive defect healing. During film formation, DL‐α‐lipoic acid‐N‐hydroxysuccinimide ester (LA‐NHS) undergoes in situ polymerization to establish a crosslinked polydisulfide scaffold at grain boundaries. The dynamic scaffold accommodates thermally induced lattice expansion and contraction, dissipates accumulated stress, anchors the perovskite lattice, and continuously passivates stress‐generated defects through reversible disulfide‐bond exchange, thereby preserving lattice ordering and improving the thermal durability. Consequently, the optimized PSCs achieve a champion power conversion efficiency (PCE) of 27.19%. The devices retain 91.71% of their initial efficiency after 150 thermal cycles between 15°C and 100°C, and 85.72% after 1500 h at 85°C. The strategy is successfully translated to large‐area PSCs (25.02% for 1 cm 2 and 22.06% for 10 × 10 cm 2 ). This work establishes a dynamic molecularscaffold framework for managing thermomechanical degradation through stress buffering, lattice anchoring, and adaptive defect healing, providing a route toward efficient, durable, and scalable perovskite photovoltaics.