All-scale hierarchical thermoelectrics: MgTe in PbTe facilitates valence band convergence and suppresses bipolar thermal transport for high performance

We report a high ZT of ∼2.0 at 823 K for 2% Na-doped PbTe with 6% MgTe with excellent thermal stability. We attribute the high thermoelectric performance to a synergistic combination of enhanced power factor, reduction of the lattice thermal conductivity and simultaneous suppression of bipolar thermal conductivity. MgTe inclusion in PbTe owns triple functions: the Mg alloying within the solubility limit in PbTe modifies the valence band structure by pushing the two valence bands (L and Σ bands) closer in energy, thereby facilitating charge carrier injection. When the solubility limit of Mg is exceeded, ubiquitous endotaxial nanostructures form, which when coupled with mesoscale microstructuring results in a…

• UD
  U.S. Department of Energy
• SU
  South University of Science and Technology of China
• OO
  Office of Energy Efficiency and Renewable Energy