Reactive Anti-Solvent Engineering via Kornblum Reaction for Controlled Crystallization in Perovskite Solar Cells

Regulating the crystallization dynamics of perovskite films is key to improving the effi-ciency and operational stability of perovskite solar cells (PSCs). However, precise regula-tion of the crystallization process remains challenging. Here, we introduce a reactive an-ti-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 carbon-yl-containing products and sulfur ions. The carbonyl oxygen coordinates with Pb²⁺ ions to form Pb–O bonds, which retards rapid crystallization, suppress heterogeneous nucleation, and facilitate the growth of larger perovskite grains with improved film uniformity. Addi-tionally, the exothermic nature of the reaction accelerates local supersaturation and nu-cleation. This synergistic crystallization control significantly enhances the film morphol-ogy 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 scala-ble fabrication of high-performance PSCs.