Sb induces both doping and precipitation for improving the thermoelectric performance of elemental Te

Abstract

As one of the focus areas, phonon scattering by boundary interfaces enables an effective reduction in the lattice thermal conductivity for improving thermoelectrics. Introduction of boundary interfaces is expected through precipitation by low-temperature processing of over-saturated solids or melts. In this study, a single step of both doping and precipitation is achieved in elemental tellurium with a few percent of Sb, leading to a high thermoelectric figure of merit, zT, of 0.9. This is quite comparable with the As-doped Te reported previously, but without involving any toxic elements. Evolutionarily, Sb-substitution of Te within 0.5% sufficiently increases the hole concentration leading to an optimized thermoelectric power factor, while higher concentration of Sb introduces Sb₂Te₃ precipitates, enabling an effective phonon scattering for a reduced lattice thermal conductivity by ∼25%. This study further demonstrates tellurium as a promising elemental thermoelectric material from 300 to 700 K.