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.