Robust strain-tolerant metallic phase in Cs-based halide perovskite CsAsBr$_3$

Abstract

Halide perovskites have emerged as a class of materials with exceptional optoelectronic properties. While most research has focused on their semiconducting nature, the exploration of metallic states in these materials is a burgeoning field. This study investigates the electronic properties of the halide perovskite CsAsBr$_3$ for the first time, which is predicted to exhibit a metallic character. Using first-principles calculations based on Density Functional Theory (DFT), we analyze the stability of this metallic state under the application of uniaxial external strain along [100] crystallographic directions. Our results demonstrate that the metallic nature of CsAsBr$_3$ is remarkably robust, persisting under both compressive and tensile strains of up to 10\%. The band structure and density of states (DOS) show that the states crossing the Fermi level, primarily composed of As 4p and Br 4p orbitals, are not significantly perturbed by the applied strain. This intrinsic stability suggests that CsAsBr$_3$ is a promising candidate for flexible and strain-tolerant electronic applications where a stable metallic conductivity is required.