Computational study of Cs2ScXBr6 (X=Ag, Tl) for renewable energy devices

Abstract

The optical, electronic, thermoelectric (TE), elastic and structural features of Cs2ScXBr6 (X = Ag, Tl) are probed by using full-potential linearized augmented plane wave (FP-LAPW) method within first principles computations. Tolerance factor(τ) for Cs2AgScBr6 and Cs2TlScBr6 are 0.97 and 0.93, respectively, which endorse the solidity of the compound in cubic phase and negative value of enthalpy of formation (ΔHf) confirm stable nature of both compounds.The band structures (BS) show semiconductor behavior for both compounds and have direct band-gaps(Eg) of 3.34 and 3.50 eV for Cs2ScAgBr6 and Cs2ScTlBr6, correspondingly at L symmetry points. In the span of 0–10 eV, the optical properties are calculated. The α (ω) reveals that Cs2ScXBr6 (X = Ag, Tl) compounds effectively absorb light in the UV range. For the two compounds, Cs2ScTlBr6and Cs2ScAgBr6, the computed values of B/G are 2.06 and 3.94, respectively. This supports ductility and the presence of ionic bonding for both compounds. TE variables like electrical conductivity (σ/τ), power factor (PF), thermal conductivity (κ/τ), seebeck coefficient (S) and figure of merit (ZT) are computed by utilizing the BoltzTrap code. The maximum value of ZT (at 800 K) are observed to be 0.76 and 0.81 for Cs2ScAgBr6 and Cs2ScTlBr6 . Findings indicate that Cs2ScXBr6 (X=Ag, Tl) would be suitable materials for TE and solar cell usages.