Residual Solvent Management Enables High-Efficiency Antisolvent-Free Perovskite Solar Cells

During the formation of the perovskite films via the antisolvent-free method, commonly employed in scalable large-area fabrication processes, the solvent tends to lock inside the perovskite layer. The residual N-methyl-2-pyrrolidone (NMP) in the perovskite films hinders the complete reaction between perovskite components, adversely affecting the perovskite crystal crystallinity, crystal orientation, and stability. To address this issue, we introduced propionic acid (PA) into the perovskite solution to facilitate the removal of the NMP. PA weakened the intermolecular interaction between PbI2 with NMP, increased the volatility of the perovskite solvent system, and thus promoted more efficient NMP evaporation during the perovskite film formation. As a result, the optimized perovskite films exhibit significantly improved crystal quality, and the devices exhibit a champion power conversion efficiency (PCE) of 25.86% in the small-area device. In addition, by enlarging the perovskite film area, we achieved 23.08% PCE for the rigid module (4 cm2) and 16.27% PCE for the flexible module (over 100 cm2), showing them to be well-suited for the commercial manufacturing of perovskite photovoltaics.