Thermoelectric performance of single phase p-type quaternary (PbTe)0.65–x(PbSe)0.35(PbS)x alloys

Recently, the quaternary system PbTe−PbSe−PbS has been shown to provide high thermoelectric efficiency, zT. The intent of this research is to investigate the thermoelectric properties of Na-doped pseudoternary (PbTe)0.65−x(PbSe)0.35(PbS)x with a high ratio of PbS to PbTe. The addition of a large concentration of PbSe increases the solubility limit of PbS in PbTe, allowing all samples to behave as solid solutions with a high concentration of PbS. This is proven to decrease lattice thermal conductivity due to the larger atomic mass contrast between sulfur and tellurium; however, it simultaneously causes a decrease in the Seebeck coefficient due to a larger band offset, so a high concentration of PbS shows no improvement in zT, with a maximum of ∼1.4 in the x = 0, 0.05, and 0.10 samples