First-Principles Investigation of Structural, Electronic, Mechanical and Optical Properties of Tl Based Semiconducting Perovskites TlVX₃ (X = Br, I) for Reflective Coating Applications

Perovskite materials have garnered significant attention due to their versatile properties and potential applications in various advanced technologies. Here in this study, we investigated the structural, electronic, mechanical, and optical properties of cubic perovskite halides TlVX₃ (X = Br, I) using first-principles density functional theory (DFT) calculations. The structural analysis confirms their thermodynamic and dynamic stability. The optimized lattice constants are found to be 5.27 Å and 5.67 Å for TlVBr₃ and TlVI₃ respectively. Electronic property analysis reveals semiconducting behavior with direct bandgaps of 2.7 eV for TlVBr₃ and 2.12 eV for TlVI₃, suitable for electronic and optoelectronic applications. Density of states (DOS) analysis highlights the contributions of vanadium and halogen atoms to the valence and conduction bands, shedding light on their bonding and electronic interactions. Mechanical properties assessed via elastic constants confirm structural robustness and ductility, with TlVBr₃ exhibiting superior stiffness and anisotropy compared to TlVI₃. Optical studies reveal strong UV reflectivity, high dielectric constants, and favorable refractive indices, establishing these materials as viable candidates for UV protection, photonic devices, and reflective coatings. This comprehensive investigation positions TlVX₃ (X = Br, I) as promising materials for next-generation optoelectronic, photonic, and mechanical applications, providing a robust framework for future experimental validation and technological development.