Theoretical study on electronic structure and thermoelectric properties of PbS_xTe_(1-x)(x = 0.25, 0.5, and 0.75) solid solution

The electronic structure and thermoelectric(TE) properties of PbS_xTe_(1-x)(x = 0.25, 0.5, and 0.75) solid solution have been studied by combining the first-principles calculations and semi-classical Boltzmann theory. The special quasirandom structure(SQS) method is used to model the solid solutions of PbS_xTe_(1-x), which can produce reasonable electronic structures with respect to experimental results. The maximum zT value can reach 1.67 for p-type PbS0.75Te0.25 and 1.30 for PbS0.5Te0.5 at 800 K, respectively. The performance of p-type PbS_xTe_(1-x) is superior to the n-type ones, mainly attributed to the higher effective mass of the carriers. The z T values for PbS_xTe_(1-x) solid solutions are higher than that of pure Pb Te and Pb S, in which the combination of low thermal conductivity and high power factor play important roles.