Imidazole derivative spacers functional-group-induced regulation of interfacial recrystallization and defect passivation ability for high-performance perovskite solar cells

The formation of numerous defects in perovskite films during the annealing process will damage the performance and operational stability of perovskite solar cells (PSCs). Interfacial reconstruction by organic cations is an effective and promising strategy to repair terminal defects and improve stability of perovskite films. Herein, we employed three imidazole derivative spacer cations with different functional groups (- MeNH2, -MeOH and - MeCOOH) to in-situ grow multifunctional 2D perovskite passivation layers. The imidazole derivative cations not only induce interfacial recrystallization during secondary annealing but also regulate the interfacial reconstruction process and the defect passivation capability of the 2D perovskite layers. The modified perovskite film based on 2-(1H-Imidazol-5-yl)acetic acid hydrochloride (4-MeCOOH*IM) with highest adsorption energy displays increased grain sizes, higher crystallinity and lower surface roughness, resulting in faster charge carrier transport and suppressed non-radiative recombination. As a result, the carrier lifetime of the 4-MeCOOH*IM perovskite film increases from 691.43 (control) to 3213.19 ns, and the corresponding photovoltaic device yields highest PCE of 24.59 % with high open-circuit voltage (Voc) of 1.20 V. Furthermore, the modified devices exhibit excellent long-term stability under humidity and high temperature conditions. The study demonstrates that the interfacial recrystallization process and defect passivation ability of perovskite films can be regulated by modulating the introduced spacer cations with different functional groups, which provides a reference for regulating multifunctional interface in high-performance PSCs.