Defect passivation strategy for inorganic CsPbI2Br perovskite solar cell with a high-efficiency of 16.77%

Abstract

All-inorganic halide perovskite solar cells (PSCs) have acquired great progress, especially CsPbI2Br. However, their photoelectric conversion efficiency (PCE) remains far below the theoretical predictions. Non-radiative recombination is one of the important issues affecting the photoelectric performance of the PSCs, and the defective lead ions derived from the evaporation of halide ions in the inorganic perovskite are the principal non-radiative recombination centers. Herein, the non-radiative recombination is effectively suppressed by introducing the N-methyl-2-pyrrolidone (NMP) as a Lewis base molecule to passivate the defective lead ions. Therefore, by adjusting the dosage of NMP, the smooth and pinhole-free CsPbI2Br perovskite film is obtained and the optimized device exhibits a champion PCE of 16.77% with an excellent fill factor (FF) of 0.80. This work proves the effectiveness of passivation using Lewis base molecules to prevent non-radiative recombination defects in inorganic perovskite.