Regulating the Crystallization of FAPbI₃‐Based Perovskite with a Furan Substituted Ethylammonium Additive for Achieving Highly Efficient Solar Cells

Efficient manipulation of crystallization and control over defects are crucial for optimizing the performance and durability of perovskite solar cells (PSCs). In this study, a novel organic multifunctional additive, 2‐(furan‐3‐yl)ethanamine hydrochloride (FFEACl), is introduced which plays a pivotal role in regulating the crystallization process of FAPbI3. Incorporating FFEACl into the perovskite precursor solution effectively suppresses the formation of undesirable non‐perovskite phase impurities while promoting the oriented crystallization of the α‐phase FAPbI3. Moreover, the addition of FFEACl leads to a more uniform surface potential and reduced defect density in the resulting FAPbI3 film. Consequently, the top‐performing PSC exhibits an impressive power conversion efficiency (PCE) of 25.41%, along with enhanced operational stability. Notably, the fabricated PSCs maintain over 80% of their initial PCE even after 1000 h of continuous operation under one‐sun illumination. The findings present a facile and effective strategy for fabricating perovskite photovoltaic devices with exceptional performance and long‐term reliability.