Dynamic Strain Homogenization Regulation for Thermomechanically Robust Sn─Pb Perovskite Solar Cells

Tin‐lead perovskite solar cells (PSCs) feature an ideal bandgap, making them approach the Shockley‐Queisser limit. However, under cyclic temperature fluctuations, asynchronous Sn/Pb crystallization‐induced compositional inhomogeneity aggravates defect evolution, lattice distortion, and tensile‐strain accumulation, ultimately amplifying thermomechanical degradation and limiting device durability. Herein, we introduce a “dynamic strain homogenization regulation strategy” by in situ forming supramolecular networks featuring multisite interactions and dynamic hydrogen bonding. This network modulates the coordination environment of Sn 2+ ‐related species, thereby suppressing compositional segregation and improving crystallization uniformity to achieve strain homogenization. The reversible reconstruction of hydrogen bonds under temperature fluctuations enables continuous strain dissipation and redistribution, effectively alleviating local stress concentration and lattice distortion. Meanwhile, the supramolecular species located at grain boundaries provide multisite defect passivation. Based on this strategy, the device achieves a power conversion efficiency of 24.1%, retaining 84.7% of its initial efficiency after 450 h at the maximum power point under one‐sun illumination, and 92.1% after 50 thermal cycles.