TMPU-Based Phase-Locking Strategy for Spatiotemporally Homogeneous Crystallization Enables Ambient Scalable Perovskite Photovoltaics

• • Phase-locked films maintained over 84% of initial photoluminescence intensity across all regions under identical aging conditions, whereas control devices exhibited only 34% efficiency retention at early-coated positions after thermal cycling, demonstrating that morphological homogeneity suppresses autocatalytic degradation pathways. • • Encapsulated modules retained over 90% of initial efficiency after 1500 h of 85°C maximum power point tracking in ambient air (ISOS-L-2 protocol) and after 2300 h under 85°C/85% RH damp-heat testing (ISOS-D-3 protocol), representing among the best stability benchmarks for large-area perovskite modules. • • The TMPU-based phase-locking strategy achieved a module efficiency of 21.5%, significantly surpassing the 20% threshold for scalable modules fabricated in ambient air, while maintaining compatibility with high-throughput blade-coating processes. • • The strategy uniquely addresses the kinetic and spatial dimensions of upscaling, linking crystallization kinetics with environmental robustness and large-area homogeneity, whereas previous approaches focused solely on thermodynamic stabilization or moisture-tolerant formulations.