Reactive Anti-Solvent Engineering via Kornblum Reaction for Controlled Crystallization in (FA0.83MA0.17Cs0.05)Pb(I0.85Br0.15)3 Perovskite Solar Cells

Regulating the crystallization dynamics of perovskite films is key to improving the efficiency and operational stability of (FA0.83MA0.17Cs0.05)Pb(I0.85Br0.15)3 perovskite solar cells (PSCs). However, precise regulation of the crystallization process remains challenging. Here, we introduce a reactive anti-solvent strategy based on the Kornblum reaction to modulate crystallization via in-situ chemical transformation. Specifically, trans-cinnamoyl chloride (TCC) is employed as a single-component anti-solvent additive that reacts with dimethyl sulfoxide (DMSO) in the perovskite precursor solution. The resulting acylation reaction generates carbonyl-containing products and sulfur ions. The carbonyl oxygen coordinates with Pb2+ ions to form Pb–O bonds, which retard rapid crystallization, suppress heterogeneous nucleation, and facilitate the growth of larger perovskite grains with improved film uniformity. Additionally, the exothermic nature of the reaction accelerates local supersaturation and nucleation. This synergistic crystallization control significantly enhances the film morphology and device performance, yielding a champion power conversion efficiency (PCE) of 23.02% and a markedly improved fill factor (FF). This work provides a new pathway for anti-solvent engineering through in-situ chemical regulation, enabling efficient and scalable fabrication of high-performance PSCs.