2-Fluoro-4-iodoaniline passivates the surface of perovskite films to enhance photovoltaic properties

Abstract

An organic molecule, 2-Fluoro-4-iodoaniline (FID), is adopted to passivate the surface defects of (FAPbI3)0.95(MAPbBr3)0.05 perovskite films. The amino group of FID forms a coordinate bond with the uncoordinated lead ion on the perovskite surface via Lewis acid–base interaction, which significantly reduced the defect state density, suppressed carrier nonradiative recombination, and boosted carrier transport of the perovskite films, resulting in increased open circuit voltage (Voc) and fill factor (FF) of the perovskite solar cells (PSCs). Meanwhile, fluorine group of FID forms hydrogen bond with perovskite, restraining ions moving and decomposition of perovskite. Consequently, the power conversion efficiency (PCE) of the PSCs was increased from 21.07% to 23.44%. Moreover, FID passivation also improved the ambient stability of the PSCs. The unencapsulated PSC with FID passivation retained more than 90% of its initial PCE for over 1500 h of storage under ambient conditions.