Theoretical Studies on the Electronic Structures of Halide Perovskites: A Critical Review

Halide perovskites have the advantages of high light absorption, low cost, and high charge mobility for applications in next-generation solar cells. Understanding the energy levels of halide perovskites is crucial for optoelectronic applications. Recently, density functional theory (DFT) calculations have been widely used for calculating energy levels by considering the electronic structure of each component of this material. In this review, we discuss the origins of the changes in the energy levels in halide perovskites in relation to (1) structural changes, (2) atomic orbital levels, and (3) interatomic interactions based on the DFT calculations. Based on the findings of this review, we provide useful insights for the rational design of perovskite solar cells.