Highly conductive flat grains of cesium lead bromide perovskite via additive engineering with methylammonium bromide

Abstract

Perovskite solar cells made of inorganic cesium lead bromide (CsPbBr3) have displayed unusually high open-circuit potentials. Yet, the photovoltage efficiency is still lagging behind that of iodide-based halide perovskites. In this study, a multistep solution spin coating process is used to create CsPbBr3 film. The CsPbBr3 perovskite film consists of flat and rounded grains, and the photocurrent of each grain type is imbalanced. Interestingly, a significant current increase in flat grains was observed by conducting atomic force microscopy (c-AFM) at the nanoscle after the addition of methyl ammonium bromide (MABr) as an additive. The addition of MABr results in good optoelectronic quality of perovskite films with highly conductive grains and provides better charge transport and hence improved power conversion efficiency.