Investigation of electronic and optical properties of the ternary chalcogenides for optoelectronic applications: A TB-mBJ DFT study

Ternary selenide chalcogenide Tl3AsSe3 compound was identified as one of the most promising novel materials and potentially appropriate for multifunction applications. Current computational study is focused on computation of optical properties of Tl3AsX3 (X = S and Se) system where Modified Becke Johnson (mBJ) approximation is employed. The calculations of band structure revealed that both materials were indirect bandgap semiconducting materials with bandgap 1.5 eV and 1.9 eV respectively. The valence band maxima are mainly created because of Tl/As/S/Se(s/p/p/p) orbitals and conduction band is formed thanks to hybridizations of Tl/As/S/Se(p) orbitals. The optical properties including complex dielectric function, reflectivity, energy loss function, refractive index, and real optical conductivity also calculated by using first-principles calculations. Our investigations explained that the two materials sustain their positive value of the refractive index and thus is the non-negative index of refractions, so these materials are active candidates for optoelectronic applications.