Multiscale Coupling Between Macroscopic Mechanics and Atomic Assembly (MM–AA) of Soft‐Lattice Halide Perovskites

Halide perovskites are promising candidates for optoelectronic devices, but their solution‐processed films frequently suffer from solute aggregation, crystalline disorder, and random orientation, that is, defects that significantly compromise device performance. These issues arise from complex multiscale interactions during film formation, where macroscopic mechanical forces could hypothetically influence atomic‐scale assembly. This review elucidates the critical role of multiscale mechanical coupling (linking surface/interface mechanics, fluid dynamics, and crystallization kinetics) in governing perovskite film quality, which ultimately enhanced the uniformity of film thickness, photoelectric performance, and long‐term stability. We first analyze how solvent evaporation, interfacial energy, and flow‐induced shear shape the spatiotemporal evolution of solute distribution and crystal growth. Building on this understanding, we present mechanical regulation strategies aimed at directing film formation: modifying wettability through surfactants and surface energy modulators; manipulating flow behavior via Marangoni convection and shear stress; and mitigating interfacial stress through lattice and thermal expansion matching. To further enhance structural control, we highlight fabrication techniques that couple multiple external fields (e.g., thermal, electrical, mechanical, and chemical fields) and leverage in situ characterization for real‐time feedback. Finally, we explore machine learning‐assisted multiscale modeling as a powerful tool to connect atomic interactions with macroscopic processing variables, enabling predictive optimization. By integrating these insights, this review establishes a unified framework for guiding high‐quality, scalable perovskite film fabrication toward industrial deployment.