Enhancing the thermoelectric properties of SnTe via introducing PbTe@C core-shell nanostructures

SnTe is an emerging IV-VI metal chalcogenide, but its low Seebeck coefficient and high thermal conductivity mainly originating from the high hole concentration limit its thermoelectric performance. In this work, an amorphous carbon core-shell-coated PbTe nanostructure prepared by a bottom-up method is first incorporated into the Sn1-ySbyTe matrix to enhance the thermoelectric performance of SnTe. The square-like PbTe nanoparticles maintain their original cubic morphology and do not grow up obviously after the SPS process due to the coating of the C layer, bringing about the formation of nanopores locally, while Sb alloying induces Sb point defects and Sb-rich precipitates. All these unique hierarchical microstructures finally lead to an ultralow lattice thermal conductivity (similar to 0.48 W-1 m(-1) K-1) approaching amorphous limits (similar to 0.40 W-1 m(-1) K-1). In addition, the incorporation of PbTe@C core-shell nanostructures decreases the carrier mobility obviously with a slight loss in carrier concentration, resulting in the deterioration of electrical properties to a certain extent. As a result, a peak thermoelectric figure of merit (ZT) of 1.07 is achieved for Sn0.89Sb0.11Te-5%PbTe@C at 873 K, which is approximately 154.76% higher than that of pristine SnTe. This work provides a new strategy to enhance the thermoelectric performance of SnTe and also offers a new insight into other related thermoelectric systems.

Automated summary

The study introduces PbTe@C core-shell nanostructures to enhance the thermoelectric performance of SnTe, achieving a significant increase in ZT value. However, the structure also has some impact on the electrical properties to some extent.