Crystal Growth Regulation of α‐FAPbI<sub>3</sub> Perovskite Films for High‐Efficiency Solar Cells with Long‐Term Stability
Shiheng Wang, Huaiqing Luo, Zhenkun Gu, Rudai Zhao, Lutong Guo, Na Wang, Yunjie Lou, Qun Xu, Shou Peng, Yiqiang Zhang, Yanlin Song
Abstract
Abstract The two‐step sequentially deposition strategy has been widely used to produce high‐performance FAPbI 3 ‐based solar cells. However, due to the rapid reaction between PbI 2 and FAI, a dense perovskite film forms on top of the PbI 2 layer immediately and blocks the FAI diffusion into the bottom of the PbI 2 film for a complete reaction, which results in a low‐efficiency and limited reproducibility of perovskite solar cells (PSCs). Here, high‐quality α‐FAPbI 3 perovskite films by crystal growth regulation with 4‐fluorobenzamide additives is fabricated. The additives can interact with FAI to suppress the fast reaction between the FAI and PbI 2 and effectively passivate the under‐coordinated Pb 2+ or I ‐ defects. As a result, α‐FAPbI 3 perovskite films with low trap density and large grain size are prepared. The modified PSCs present a high‐power conversion efficiency of 24.08%, maintaining 90% of their initial efficiency after 1400 h in high humidity. This study provides an efficient strategy of synergistic crystallization and passivation to form high‐quality α‐FAPbI 3 films for high‐performance PSCs.