Enhanced thermoelectric performance of PbTe bulk materials with figure of merit zT >2 by multi-functional alloying

Quarternary alloys of Pb1-xMgxTe0.8Se0.2 were designed to improve the figure of merit zT. A maximum zT of ∼2.2 at 820 K was achieved in PbTe0.8Se0.2 with 8% MgTe. High zT of ∼2.0 can also be achieved even in such a large dimension (∼200 g, ϕ42 mm × 18 mm) bulk sample. These results highlight the multi-functional roles of quarternary alloying with Mg and Se, and demonstrate the realistic prospect of large-scale commercial fabrication in high performance PbTe-based thermoelectric materials.242