ABSTRACT
Despite the remarkable progress of perovskite solar cells (PSCs), the substantial inherent defects within perovskites restrict the achievement of higher efficiency and better long-term stability. Herein, we introduced a novel multifunctional imidazole analogue, namely, 1-benzyl-3-methylimidazolium bromide (BzMIMBr), into perovskite precursors to reduce bulk defects and inhibit ion migration in inverted PSCs. The electron-rich environment of -N- in the BzMIMBr structure, which is attributed to the electron-rich adjacent benzene ring-conjugated structure, effectively passivates the uncoordinated Pb2+ cations. Moreover, the interaction between the BzMIMBr additive and perovskite can effectively hinder the deprotonation of formamidinium iodide/methylammonium iodide (FAI/MAI), extending the crystallization time and improving the quality of the perovskite precursors and films. This interaction also effectively inhibits ion migration to subsequent deposited films, leading to a noteworthy decrease in trap states. Various characterization studies show that the BzMIMBr-doped films exhibit superior film morphology and surface uniformity and reduced nonradiative carrier recombination, consequently enhancing crystallinity by reducing bulk/surface defects. The PSCs fabricated on the BzMIMBr-doped perovskite thin film exhibit a power conversion efficiency of 23.37%, surpassing that of the pristine perovskite device (20.71%). Additionally, the added BzMIMBr substantially increased the hydrophobicity of perovskite, as unencapsulated devices still retained 93% of the initial efficiency after 1800 h of exposure to air (45% relative humidity).
