Crystallization Pathway Optimization and High‐Index Facet Stabilization for Perovskite Photovoltaics

Abstract

ABSTRACT Perovskite solar cells (PSCs) face a critical challenge in balancing high power conversion efficiency (PCE) with operational stability, largely governed by the crystallization kinetics and facet configuration of perovskite films. Here, we report a kinetically segmented crystallization strategy mediated by a conformationally preorganized macromolecular regulator, cellulose 2,4,6‐trichlorophenylcarbamate (3Cl‐NC). Through multidentate coordination, 3Cl‐NC establishes localized precursor‐rich microenvironments that promote heterogeneous nucleation. During thermal annealing, this association transitions into a thermally activated dynamic coordination state that retards long‐range precursor transport while maintaining local availability for controlled crystal growth. This segmented regulation suppresses metastable δ‐phase accumulation and facilitates photoactive α‐phase formation. Furthermore, 3Cl‐NC thermodynamically stabilizes the high‐Miller‐index (210) orientation, establishing a synergistic architecture that intrinsically enhances lattice structural stability. Consequently, the resulting perovskite films exhibit higher phase purity, relieved residual stress, and suppressed ion migration, enabling devices to achieve a champion PCE of 26.59% (certified 26.29%) with improved long‐term stability.