Effect of S, Se and Te replacement on structural, optoelectronic and transport properties of SrXO4 (X= S, Se, Te) for energy applications: A first principles study

Optoelectronic and thermoelectric properties of SrXO4 (X = S, Se, Te) have been investigated with the help of WIEN2K code by using FP-LAPW method and GGA approximation of the DFT approach. The obtained results show that SrSO4 and SrSeO4 are direct wide band gap semiconductors, while, SrTeO4 is an indirect band gap semiconductor. Based on theoretical study of optical properties, it has been established that the investigated compounds are promising candidates for active optical devices operating in the UV and visible range. These compounds have also been found to be weak reflectors for incident photons as they reflect up to 60% of the incident photons in the upper UV region. The semi-classical Boltzmann transport kinetic equations are used to study thermoelectric properties such as electrical conductivity, thermal conductivity, power factor, Seebeck coefficient and Figure of merit of the considered compounds. The research shows that SrSeO4 and SrTeO4 are promising compounds for thermoelectric devices.