Theoretical study on electronic structure and thermoelectric properties of PbSxTe1-x (x=0.25, 0.5, and 0.75) solid solution

The electronic structure and thermoelectric (TE) properties of PbSxTe1-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 PbSxTe1-x , which can produce reasonable electronic structures with respect to experimental results. The maximum T-Z 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 PbSxTe1-x is superior to the n-type ones, mainly attributed to the higher effective mass of the carriers. The T-Z values for PbSxTe1-x solid solutions are higher than that of pure PbTe and PbS, in which the combination of low thermal conductivity and high power factor play important roles.