Dipole‐Driven Adaptive Solid–Liquid Reaction and Carrier Extraction in Two‐Step‐Method Halide Perovskite Photovoltaics

ABSTRACT The diffusion reaction of cationic salts in lead iodide during the sequential deposition process determines the homogeneity and photoelectric properties of the photovoltaic perovskite film, making it momentous to control this process from the perspective of peculiar mass transfer dynamics. Here, we propose a dipole‐driven diffusion strategy for adaptive interface reactions by introducing a strongly bipolar intramolecular salt (PPS) to generate additional attractive dipole forces, which drive the energetic diffusion of cations and mediate the crystallization process, thus improving the mass transfer efficiency of cations and the phase conversion degree of lead iodide to perovskite films. The resulting perovskite films exhibit higher formation quality in multiple aspects with fewer detrimental defects. In addition, the PPS with a dipole structure contributes to substantially increasing the built‐in potential, facilitating more efficient photogenerated carrier transport and extraction in perovskite devices. The champion power conversion efficiency of the final optimized perovskite solar cell is increased to 25.83%, and the long‐term stability under multiple stress conditions is synchronously significantly improved, maintaining 98% and 86% of its initial efficiency after nearly 1500 h under the ISOS‐D‐1 and ISOS‐D‐2 protocol conditions, respectively.