The Role of Surfaces and Structural Disorder on the Core Level Chemical Shift in Perovskite Solar Cells

Abstract

The local electronic environment of atoms near interfaces in thin-film solar cells plays a crucial role in the overall performance. Core electron chemical shifts are sensitive indicators of variation in the local environment of an atom. We have used density functional theory-based methods to study the chemical shift of core electrons in methylammonium lead bromide (CH_3 NH_3 PbBr_3) due to (1) the effect of methylammonium orientational disorder and (2) different surface terminations of a CH_3 NH_3 PbBr_3 slab model. The calculations of the C 1s, N 1s, Pb 4f, Br 3d, and Br 3p core levels are shown. The electronic structure calculations are crucial to indicate the difference in the value of core-level energy in metal halide perovskite. Our results show that we can theoretically predict core electron chemical shifts using density functional theory-based method which can be correlated to confirm some energy changes of the valence band that has a major impact when designing solar cells.