Reconfiguring perovskite interface viaR4NBr addition reaction toward efficient and stable FAPbI3-based solar cells

Defect states in perovskite films restrict the interfacial stability and open-circuit voltage of perovskite solar cells. Here, aiming at superior interfacial passivation, we investigate the reconfiguration of perovskite interface by the interaction between a series of quaternary ammonium bromides (QAB) and lead—halide (Pb—X) octahedrons. Bromide—iodide substitution reaction or R4NBr addition reaction may occur on the perovskite surface, which is related to the steric hindrance of quaternary ammonium cations. On this basis, the perovskite surface morphology, band structure, growth orientation and defect states are reconstructed viathe R4NBr addition reaction. This ordered lead—halide adduct could effectively repair the imperfect perovskite/hole transportation layer interface to suppress non-radiative recombination and ion migration toward ultralong carrier lifetime surpassing 10 µs. The resulting perovskite solar cells yield the efficiency of 23.89% with steady-state efficiency of 23.70%. The passivated cells can sustain 86% of initial efficiency after 200-h operation, which is attributed to the passivation effect and hydrophobic characteristics. This work provides an avenue for reconfiguring perovskite surface by QABs.