Exploring CsSnCl 3 as a Lead‐Free Halide Perovskite: Insights From Density Functional Theory

In this study, we investigate the structural, electronic, and elastic properties of the lead‐free halide perovskite CsSnCl 3 using first‐principles calculations based on density functional theory (DFT). The frequency‐dependent optical properties were evaluated through the complex dielectric function computed within time‐dependent density functional theory using the Sternheimer equation approach. The structural analysis reveals a stable cubic crystal structure with a lattice constant of 5.63 Å. The electronic band structure, calculated using the generalized gradient approximation (GGA) with the Perdew–Burke–Ernzerhof (PBE) functional, shows a direct band gap of 1.06 eV, indicating promising semiconducting behavior suitable for optoelectronic applications. The elastic constants were also evaluated to understand the mechanical behavior of the compound. Key elastic parameters at zero pressure include a bulk modulus of 22.653 GPa, Pugh’s ratio of 2.299, and Poisson’s ratio of 0.305. These values confirm that CsSnCl 3 is mechanically stable and ductile. The combination of a suitable band gap and favorable mechanical characteristics positions CsSnCl 3 as a viable, environmentally friendly alternative to lead‐based perovskites for use in light‐harvesting devices. This article provides fundamental insights that support the potential applications of CsSnCl 3 in photovoltaic and optoelectronic technologies, while also contributing to the ongoing development of sustainable materials for next‐generation energy solutions.