A Coordination‐Regulated Anti‐Solvent‐Free Strategy by Sulfolane for High‐Performance Perovskite Solar Cells

ABSTRACT Anti‐solvent quenching has been widely adopted to fabricate high‐efficiency perovskite solar cells (PSCs). However, this strategy suffers from poor process tolerance and limited scalability, motivating the development of anti‐solvent‐free methods. Here, we report a coordination‐regulated anti‐solvent‐free strategy by introducing sulfolane as an additive into a 2‐methoxyethanol (2ME)‐based perovskite precursor. Owing to the weak coordination capability of 2ME toward Pb 2+ , conventional 2ME processing often leads to uncontrolled intermediate‐phase evolution and needle‐like morphology. However, the interaction between sulfolane and Pb effectively regulates the perovskite precursor environment, stabilizes the iodoplumbate coordination complex, particularly PbI 3 − ‐related species, and thereby modulates perovskite crystallization dynamics. In addition, the residual sulfolane is shown to passivate the defects and traps in the perovskite films. Consequently, the perovskite films exhibit compact and uniform morphology with enhanced grain packing and reduced pinholes. Our resulting champion device with sulfolane additive achieves significantly improved efficiency from 15.03% to 26.02%, with an open‐circuit voltage (V oc ) of 1.18 V. Moreover, the device with sulfolane additive maintains over 87% of its initial efficiency after 2000 h under N 2 atmosphere at 25°C. This work highlights the effectiveness of coordination engineering in enabling scalable and reproducible perovskite fabrication by an anti‐solvent‐free method.