Potential thermoelectric material : a first-principles study

Abstract

The electronic structures and thermoelectric properties of are investigated by first-principles calculations and semiclassical Boltzmann transport theory. Both electron and phonon transport are considered to attain the figure of merit ZT. A modified Becke–Johnson exchange potential, including spin–orbit coupling (SOC), is employed to investigate the electron part of . It is found that SOC has an obvious effect on valence bands, producing huge spin–orbital splitting, which leads to a remarkable detrimental effect on the p-type power factor. However, SOC has negligible influence on conduction bands, so the n-type power factor hardly changes. The temperature dependence of lattice thermal conductivity by assuming an inverse temperature dependence is attained from a reported ultralow lattice thermal conductivity of 0.31 at room temperature. Calculating scattering time τ is challenging, but a hypothetical τ can be adopted to estimate thermoelectric conversion efficiency. The maximal figure of merit ZT is up to about 0.70 and 0.60 with scattering time τ = 10−14 s and τ = 10−15 s, respectively. These results convince us that may be an efficient thermoelectric material for real devices.