Chiral Molecular Configuration‐Mediated Crystallization of Perovskites for High‐Performance Solar Cells

ABSTRACT Maximizing the binding affinity between molecular additives and perovskite is critical for long term device stability, yet how molecular configuration influences the interaction with perovskites remains unexplored. Here, we report a chiral stereo‐anchoring strategy to regulate the colloidal crystallization of FAPbI ₃ perovskites through stereochemical molecular design. A pair of enantiomeric additives, (R)‐4‐(pyrrolidin‐3‐yl)thiomorpholine 1,1‐dioxide dihydrochloride (R)‐Pye and (S)‐Pye, are introduced as chiral‐selective crystallization modulators. Owing to its more favorable steric accessibility, R‐Pye exhibits a more favorable adsorption geometry on the perovskite surface than S‐Pye, resulting in a higher binding energy (9.45 vs 7.33 eV) and an increased iodine vacancy formation energy (4.56 vs 2.46 eV). This strengthened interaction optimizes nucleation kinetics, and promotes ordered crystal growth, leading to high‐quality perovskite films with reduced defect density and improved crystallinity. Consequently, R‐Pye‐treated devices achieve a remarkable power conversion efficiency (PCE) of 26.13% with an open‐circuit voltage ( V _OC ) of 1.20 V. Moreover, the resulting devices show excellent operational durability, retaining 94.8% of their initial efficiency after 550 h of continuous maximum power point tracking. This study underscores that the stereochemical configuration is a factor in governing the molecular‐level interaction and crystallization pathways, opening new horizons for crystallization control in perovskite solar cells.