Crosslinking‐Induced Chelation and Stress Compression for High‐Efficiency All‐Inorganic CsPbBr 3 Perovskite Solar Cells

ABSTRACT Optimizing the structural quality of perovskite films through molecular crosslinking has emerged as an effective strategy for achieving high‐efficiency and durable perovskite solar cells (PSCs). Despite notable progress in improving film crystallinity and defect passivation, residual tensile stress generated during thermal annealing is still a major challenge, leading to lattice distortion, trap formation, and accelerating the degradation of perovskite thin films. To overcome it, we propose a dual‐molecule crosslinking strategy to enhance film quality and regulate internal stress simultaneously. Specifically, a DOP‐BTA crosslinked complex was incorporated into the CsPbBr 3 precursor solution. The complex forms stable multidentate chelation bonds with Pb 2+ ions, which could effectively passivate defect states and relieve residual tensile stress by inducing a favorable compressive stress within the film. This synergistic regulation not only facilitates uniform grain growth and improves crystallinity but also mitigates interfacial stress accumulation. As a result, the optimized CsPbBr 3 PSCs possess a significantly enhanced power conversion efficiency with remarkably improved environmental and operational stability. Even under elevated temperature and humidity conditions, the unencapsulated devices still maintain outstanding performance. This work provides a new molecular‐level insight into stress‐defect synergy in all‐inorganic perovskite films and offers a versatile approach for constructing high‐performance and stable perovskite optoelectronic devices.