TMPU-Based Phase-Locking Strategy for Spatiotemporally Homogeneous Crystallization Enables Ambient Scalable Perovskite Photovoltaics
Organic-inorganic hybrid lead halide perovskites exhibit exceptional photovoltaic properties, yet their low crystallization energy promotes defect generation and necessitates precise control over synthesis parameters, hindering scalable fabrication. Ambient large-area coating methods suffer from environmental disturbances, leading to nonuniform crystallization and mixed α/δ phases, resulting in module efficiencies below 20% compared to >27% for lab-scale spin-coated cells. This work introduces a phase-locking strategy using 3-ureidopropyltrimethoxysilane (TMPU) incorporated into the PbI2 precursor solution during two-step blade coating. TMPU undergoes simultaneous cross-linking and interaction with the perovskite intermediate, forming a dynamically evolving intergranular network that blocks moisture and reduces the energy barrier for α-FAPbI3 formation. This approach achieves spatiotemporally homogeneous crystallization, eliminating directional inhomogeneity. Under segmented and monolithic aging protocols, control devices exhibited severe position-dependent degradation with only 34% efficiency retention at early-coated positions after thermal cycling, whereas phase-locked films maintained over 84% of initial photoluminescence intensity across all regions. Encapsulated modules retained over 90% of initial efficiency after 1500 h of 85°C maximum power point tracking (ISOS-L-2) and after 2300 h under 85°C/85% RH damp-heat testing (ISOS-D-3). The TMPU-based strategy combines exceptional performance (21.5% module efficiency) with robust stability, offering a distinct advantage over alternative approaches. This work addresses the kinetic and spatial dimensions of upscaling, demonstrating that morphological uniformity is a fundamental contributor to stability, marking a critical advance toward practical deployment of perovskite photovoltaics.