Lead(II) 2‐Ethylhexanoate for Simultaneous Modulated Crystallization and Surface Shielding to Boost Perovskite Solar Cell Efficiency and Stability

Abstract The bulk and surface of a perovskite light‐harvesting layer are two pivotal aspects affecting its carrier transport and long‐term stability. In this work, lead(II) 2‐ethylhexanoate (LDE) is introduced via an antisolvent process into perovskite films to change the reaction kinetics of the crystallization process, resulting in a high‐quality perovskite film. Meanwhile, a carboxyl functional group with a long alkyl chain coordinates with the Pb cation, reducing the defect density related to unsaturated Pb atoms. Moreover, the long alkyl chains form a protecting layer at the surface of the perovskite film to prevent chemical attack by water and air, prolonging the lifetime of perovskite devices. Consequently, the assembled device demonstrates a power conversion efficiency (PCE) of 24.84%. Both of the thermal and operational stability are significantly improved due to reduced ion‐migration channels.