First principles study of the effect of spin-orbit coupling on thermoelectric properties of Bismuth telluride

Abstract

Thermoelectric materials regain attention due to its capability as a solution of the environmental crisis. Bi2Te3 is one of the most efficient thermoelectric materials known that capable to operate at room temperature. A comprehensive analysis was conducted using density functional theory (DFT) that implemented in CASTEP to perform structural optimization. WIEN2K and BoltzTraP are used to calculate electronic and thermoelectric properties respectively. Local density approximation and spin–orbit coupling (SOC) were chosen within the calculation. SOC has developed multi-valleys band and increased degeneracy on band structure which indicates the increase of electrical and thermal conductivity. The occupancy of electrons also have increased. The SOC has increased the change rate of thermopower, electrical conductivity and thermal conductivity over temperature. However, SOC has decreased thermopower and overall performance of Bi2Te3. Nevertheless, the results are consistent with the other. SOC can be used to manipulate the properties of thermoelectric material for enhancement purpose.