Optimizing the microstructure of pure Te alloys with metals doping for improving thermoelectric properties

Abstract

Tellurium (Te) exhibits a high Seebeck coefficient and low thermal conductivity, showing broad application prospects in medium-to-low temperature thermoelectrics. However, its low electrical conductivity limits the optimization of its thermoelectric figure of merit (ZT). This study systematically investigated the regulation mechanisms of single-element doping with Sb, Bi, and Pb on the electrical and thermal transport properties of Te-based materials. Results demonstrate that while Sb and Bi doping significantly enhance electrical conductivity, they also cause a substantial increase in thermal conductivity and a severe degradation of the Seebeck coefficient (S), thereby limiting ZT optimization (Sb: ZT = 1.22 at 600 K; Bi: ZT = 0.20 at 600 K). In contrast, Pb doping not only leads to the formation of a defect structure containing nano-PbTe precipitates, but also utilizes the energy filtering effect induced by the interface barrier. This strategy simultaneously boosts electrical conductivity, suppresses thermal conductivity growth, and preserves a high S value, achieving a high ZT of 2.0 at 600 K. Thus, Pb-doping-based nanostructure engineering provides an effective strategy to mitigate the trade-off between electrical conductivity (σ), thermal conductivity (κ), and the Seebeck coefficient (S) in Te-based materials, providing valuable insights for designing high-performance thermoelectrics.