Boltzmann transport calculation of thermoelectric properties in Ag2Se1-xTex (x = 0.0 and 0.5)

Abstract

We calculated the thermoelectric properties of the Ag-based chalcogenides Ag2Se and Ag2Se0.5Te0.5 (AST) at room temperature using the Boltzmann transport equations within the density functional theory. We confirmed that the power factor S-2 sigma and electronic figure-of-merit ZT(e) of the Ag2Se0.5Te0.5 compound can be enhanced by hole doping as compared with Ag2Se due to enhancement of the Seebeck coefficient and electrical conductivity. The localized electrons introduced by Te doping give rise to heavy valence bands and a small band gap near the Fermi energy. We also investigated the thermoelectric properties of the compounds in terms of the two-band model within the assumption of arbitrary isotropic band dispersions. We suggest that the hole doping in the AST compound can produce a good candidate for p-type thermoelectric material by controlling the effective mass of valence band and small band gap opening. Using large atomic size elements for chemical potential tuning and isostructural substitution in Ag2Se related chalcogenides can be a good route to increase the thermoelectric performance. Published by AIP Publishing.