Crystallization Control Based on the Regulation of Solvent–Perovskite Coordination for High‐Performance Ambient Printable FAPbI<sub>3</sub> Perovskite Solar Cells
Yachao Du, Qingwen Tian, Shiqiang Wang, Lei Yin, Chuang Ma, Zhiteng Wang, Lei Lang, Yingguo Yang, Kui Zhao, Shengzhong Liu
Abstract
Abstract The critical requirement for ambient‐printed formamidinium lead iodide (FAPbI 3 ) lies in the control of nucleation–growth kinetics and defect formation behavior, which are extensively influenced by interactions between the solvent and perovskite. Here, a strategy is developed that combines a cosolvent and an additive to efficiently tailor the coordination between the solvent and perovskite. Through in situ characterizations, the direct crystallization from the sol–gel phase to α‐FAPbI 3 is illustrated. When the solvent exhibits strong interactions with the perovskite, the sol–gel phases cannot effectively transform into α‐FAPbI 3 , resulting in a lower nucleation rate and confined crystal growth directions. Consequently, it becomes challenging to fabricate high‐quality void‐free perovskite films. Conversely, weaker solvent–perovskite coordination promotes direct crystallization from sol–gel phases to α‐FAPbI 3 . This process exhibits more balanced nucleation–growth kinetics and restrains the formation of defects and microstrains in situ. This strategy leads to improved structural and optoelectronic properties within the FAPbI 3 films, characterized by more compact grain stacking, smoother surface morphology, released lattice strain, and fewer defects. The ambient‐printed FAPbI 3 perovskite solar cells fabricated using this strategy exhibit a remarkable power conversion efficiency of 24%, with significantly reduced efficiency deviation and negligible decreases in the stabilized output.