Electronic and Thermoelectric Properties of SnSe1−xS x (x = 0, 0.25, 0.5, 0.75, and 1) Alloys: First-Principles Calculations

Abstract

Ab initio investigations of the electronic and thermoelectric (TE) properties of SnSe1−xS x (x = 0, 0.25, 0.5, 0.75, and 1) alloys are performed using density functional theory. The TE properties are calculated using the semi-classical Boltzmann transport theory within the constant relaxation time approximation. Band gap values are found to range between 0.94 eV and 1.02 eV in agreement with the experimental findings and previous calculations. All alloys tend to exhibit p-type TE properties, indicated by a sharp peak near the Fermi level that indicates a heavy carrier concentration. Electrical conductivity is found to decrease, whereas the Seebeck coefficient and the power factor increase for higher concentrations. The three alloys, SnS, SnSe and SnSe0.75S0.25 alloys exhibit the same power factor of 3.5 × 10−3 W/m K2, which is promising for thermoelectric applications.