A DFT insight into lead free double halide perovskite Cs2TeI6 for clean and renewable energy sources

Abstract

In this study, we investigate the lead free double halide perovskite Cs₂TeI₆ using first-principles density functional theory (DFT) calculations to explore its potential as a photocatalyst for water splitting. We employ multiple exchange–correlation functionals to comprehensively evaluate the material's mechanical, electronic, and optical properties. The elastic constants, bulk modulus, and hardness indicate that Cs₂TeI₆ is mechanically stable and ductile, with a Vickers hardness value between 0.13–2.28 GPa. The band structure analysis reveals an indirect bandgap ranging from 1.268 to 2.058 eV, depending on the functional used. Optical property simulations demonstrate significant absorption in the visible range, with the calculated redox potentials suggesting thermodynamically favorable conditions for the water splitting mechanism. The findings indicate that Cs₂TeI₆ is a promising candidate for photocatalytic applications, including solar energy conversion and hydrogen production.