DFT combined to Boltzmann transport theory for optoelectronic and thermoelectric properties investigations for monoclinic metallic selenide: Cu5Sn2Se7

We combined a density functional theory (DFT) and Boltzmann transport theory to investigate the optoelectronic and thermoelectric properties of the monoclinic selenide Cu5Sn2Se7 compound. The present selenide is found metallic and has shown similarities with the recent selenides based on transition metals. The Fermi level is surrounded by the Cu-d, Sn-s and Se-p states along with the small contribution of Cu-s/p, Sn-p/d and Se-d states. The investigated optical properties illustrated that the major transitions take place from Cu-d and Se-p states below EF to the Sn-s states above EF. DFT calculations were combined to Boltzmann transport theory to extract the thermoelectric properties depending on temperature such as the resistivity, thermal and electrical conductivity, Seebeck coefficient and figure of merit (ZT). Our theoretical thermoelectric properties show a very close agreement with available experimental data.