Electronic and gap properties of Sb and Bi based halide perovskites: An ab-initio study

TL;DR

This study uses ab-initio calculations to analyze the electronic and gap properties of Sb and Bi based halide perovskites with various lattice structures, considering effects like spin-orbit coupling and cation disorder, revealing their potential for optoelectronic applications.

Contribution

It provides a comprehensive ab-initio analysis of Sb and Bi based halide perovskites, including effects of spin-orbit coupling and cation disorder, which was not extensively studied before.

Findings

Most compounds exhibit absorption near the optical regime.

Spin-orbit coupling significantly influences band gaps.

Cation orientation disorder affects electronic properties.

Abstract

Halide perovskites are currently under intense investigation due to their potential applications in optoelectronics and solar cells. Among them several crystallize in low symmetry lattice structures like trigonal, hexagonal, orthorhombic and monoclinic. Employing \textit{ab-initio} electronic structure calculations in conjunction with generalized gradient approximation and hybrid functionals we study a series of perovskites with the formula A$_3$B$_2$X$_9$ which have been grown experimentally. A stands for a monovalent cation like Cs, Rb, K or the organic methylammonium molecule (MA), B is Sb or Bi, and X is a halogen. Moreover we include in our study both the effect of spin-orbit coupling in the halide perovskites and the influence of the orientation disorder of the MA cation on the energy band gaps of these compounds. Most compounds under study exhibit absorption in or close to the optical regime and thus can find application in various optoelectronic devices. Our results pave the way for further investigation on the use of these materials in technology relevant applications.