A Generic Slater-Koster Description of the Electronic Structure of Centrosymmetric Halide Perovskites

TL;DR

This paper develops a minimal Slater-Koster tight-binding model for halide perovskites that accurately reproduces their electronic structure near the Fermi level, facilitating efficient analysis of their optoelectronic and topological properties.

Contribution

It introduces a four-orbital Slater-Koster model for halide perovskites that simplifies electronic structure calculations while maintaining accuracy near the Fermi level.

Findings

The SK-TB model accurately reproduces DFT band structures.

Four orbitals are sufficient for modeling valence and conduction bands.

Electron coupling strengths are nearly independent of exchange-correlation functionals.

Abstract

The halide perovskites have truly emerged as efficient optoelectronic materials and show the promise of exhibiting nontrivial topological phases. Since the bandgap is the deterministic factor for these quantum phases, here we present a comprehensive electronic structure study using first-principle methods by considering nine inorganic halide perovskites CsBX$_3$ (B = Ge, Sn, Pb; X = Cl, Br, I) in their three structural polymorphs (cubic, tetragonal and orthorhombic). A series of exchange-correlations (XC) functionals are examined towards accurate estimation of the bandgap. Furthermore, while thirteen orbitals are active in constructing the valence and conduction band spectrum, here we establish that a four orbital based minimal basis set is sufficient to build the Slater-Koster tight-binding model (SK-TB), which is capable of reproducing the bulk and surface electronic structure in the vicinity of the Fermi level. Therefore, like the Wannier based TB model, the presented SK-TB model can also be considered as an efficient tool to examine the bulk and surface electronic structure of halide family of compounds. As estimated by comparing the model study and DFT band structure, the dominant electron coupling strengths are found to be nearly independent of XC functionals, which further establishes the utility of the SK-TB model.