Structural, electronic and optical properties of ABTe2 (A = Li, Na, K, Rb, Cs and B = Sc, Y, La): Insights from first-principles computations

In this contribution, ternary telluride ABTe2 compounds are proposed as promising candidates for n-type semiconductor materials in photovoltaic and photochemical devices. We report the successful calculations of the most fundamental properties needed in the previous applications such as the effective mass, dielectric constant and the exciton binding energy. This latter one has been evaluated from the density functional theory (DFT) method in the first time for these materials. An easy dissociation for hole-electron pair is suggested due to the small value of exciton binding energy at room temperature (i.e., lower than the thermal energy, 25 meV) for most of the studied compounds. The band structure and density of states of ABTe2 are calculated using the hybridHSE06 functional, PBE0 and in addition the pure GGA-PBE functionals. Additionally, to elucidate the optical properties of these compounds, the complex dielectric function and optical reflectivity were computed for a wide range of photon radiation. Therefore, ABTe2 materials are expected to be promising candidates for visible light driven photovoltaic and photocatalytic devices. Crystal structure of ABTe2 compounds (a: rhombohedral with R3‾m; b: trigonal with P-3m1; c: hexagonal structure with P63/mmc space group). [Display omitted]