Simultaneous Defect Passivation and Crystallization Kinetics Regulation of Perovskite Thin Films Using a Nitro‐Rich Additive for Efficient Inverted Solar Cells

ABSTRACT Metal halide perovskite solar cells are fundamentally limited by uncontrollable crystallization kinetics during film formation and defect‐induced non‐radiative recombination. To address this challenge, 4‐Chloro‐3,5‐dinitrobenzotrifluoride (CNBF) is designed and introduced to simultaneously achieve precise regulation of the crystallization pathway and chemical passivation of defects. The nitro group (─NO 2 ) in the CNBF molecule acts as a strong Lewis base site, coordinating strongly with Pb 2+ , thereby effectively modulating film crystallization and passivating deep‐level trap states. In situ GIWAXS reveals that CNBF significantly accelerates the transformation from the photo‐inactive δ‐phase to the photoactive α‐phase. Benefiting from the optimized crystallization kinetics, the CNBF‐modified film exhibits an increased grain size from 400 nm to 640 nm, reduced surface roughness, and the formation of a single‐grain structure throughout the entire film thickness. Optical characterization shows substantially enhanced PL intensity and prolonged carrier lifetime, indicating effective suppression of non‐radiative recombination. Consequently, the CNBF‐modified inverted PSC achieves a champion PCE of 25.66%. Furthermore, the device retains 86.21% of its initial efficiency after storage under high humidity and elevated temperature for 1200 h.