First-Principles Study of Cs2TlCoX6 (X = I, Br): Structural Stability, Electronic, Elastic, and Optoelectronic Properties

Abstract

In this study, density functional theory (DFT) is employed to investigate the structural, electronic, and optical properties of the double perovskites Cs₂TlCoX₆ (X = I, Br). The crystal structures of these materials are optimized to evaluate their structural stability. The electronic properties, including band structure, band gap, and density of states (DOS), are systematically analyzed. Optical properties are also calculated to understand the interaction of these materials with electromagnetic radiation. Furthermore, the effect of hydrostatic pressure ranging from 0 to 8 GPa is examined to explore its influence on the electronic and optical characteristics of Cs₂TlCoX₆ (X = I, Br). The band gaps are calculated using the HSE06 hybrid functional and are found to be 2.01 eV for Cs₂TlCoBr₆ and 1.61 eV for Cs₂TlCoI₆. The obtained results indicate that these double perovskites possess suitable electronic and optical characteristics, suggesting their potential applications in optoelectronic devices, photovoltaic solar cells, and photodetectors.