Solid-State Crystallization Regulation Enables High-Performance Thermally Evaporated CsPbI₂Br Perovskite Solar Cells

Thermal evaporation is an industry-compatible deposition technique with strong potential for scalable inorganic perovskite solar cells (PSCs), yet the performance of fully thermally evaporated CsPbI₂Br devices remains constrained by poorly controlled solid-state crystallization, defect formation, and the unrevealed solid-state diffusion-crystallization mechanisms. Here, we report an effective solid-state crystallization regulation strategy for thermally evaporated CsPbI₂Br, enabled by a thermally evaporated molecular regulator, dibenzo-18-crown-6 (DC), as a transient crystallization modulator. In situ measurements demonstrated that DC coordinates with Pb^{2 +} in the evaporated precursor stack, retarding solid-state nucleation and enabling more complete precursor diffusion and ordered grain growth during annealing. As a result, the DC-modified CsPbI₂Br films exhibit substantially enhanced crystallinity, enlarged grain size, reduced trap-state density, and enhanced optoelectronic properties, while preserving the intrinsic bandgap of 1.92 eV. Solar cells fabricated with these films deliver a champion power conversion efficiency of 15.85%, representing the highest efficiency reported to date for thermally evaporated CsPbI₂Br PSCs. Moreover, large-area (50 × 50 mm²), sharply patterned perovskite films are readily fabricated using shadow masks, highlighting the scalability and manufacturing compatibility of this approach.