Generally, an excess of PbI₂ is used in the perovskite precursor solution to increase the crystallinity of the perovskite. However, excessive PbI₂ will form PbI₂ clusters during the annealing process of the perovskite film, which will cause the decomposition of perovskite solar cells (PSCs) and affect the stability of the device. Here we use 4-Difluoromethyl-Benzylamine Hydrochloride (4F₂M-BACl) to do interfacial doping of the perovskite film to passivate the defects on the surface of the perovskite film and disperse the PbI₂ clusters through the interaction with PbI₂. Under the passivation effect of 4F₂M-BACl, the power conversion efficiency (PCE) of PSCs was increased from 18.51% to 21.51%, and the hysteresis indicator (HI) was lower. In addition, the hydrophobic functional group F and benzene ring of 4F₂M-BACl and the dispersing effect of 4F₂M-BACl on PbI₂ have significantly improved the stability of the device. Unencapsulated devices with 4F₂M-BACl modification were able to maintain over 85% of the initial PCE after 170 h at 80% relative humidity (RH).