This work is led by Prof. Qingbo Meng, Prof. Dongmei Li (Institute of Physics, the Chinese Academy of Sciences) and Dr. Hongshi Li (Nankai University). Interfacial stability and open-circuit voltage of perovskite solar cells have been mainly limited by defect states in perovskite films. Here, aiming at outstanding interfacial passivation, Prof. Meng’s team have investigated 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 R 4 NBr 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 via the R 4 NBr 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 for ultralong carrier lifetime over 10 μs. The resulting perovskite solar cells yield the 23.89% efficiency with a steady-state efficiency of 23.70%. Besides, the passivated cells can sustain 86% of initial efficiency after 200-h operation. This work provides an avenue for reconfiguring perovskite surface by QABs. More interestingly, a sticky solid material based on this Pb-X adduct has further used to encapsulate photoelectronic devices, which can retain its initial performance even after being placed in water for a period of time.
Science China Chemistry