In this work, we demonstrate the use of high performance nanostructured PbTe-based materials in high conversion efficiency thermoelectric modules. We fabricated the samples of PbTe–2% MgTe doped with 4% Na and PbTe doped with 0.2% PbI₂ with high thermoelectric figure of merit (ZT) and sintered them with Co–Fe diffusion barriers for use as p- and n-type thermoelectric legs, respectively. Transmission electron microscopy of the PbTe legs reveals two shapes of nanostructures, disk-like and spherical. The reduction in lattice thermal conductivity through nanostructuring gives a ZT of ∼1.8 at 810 K for p-type PbTe and ∼1.4 at 750 K for n-type PbTe. Nanostructured PbTe-based module and segmented-leg module using Bi₂Te₃ and nanostructured PbTe were fabricated and tested with hot-side temperatures up to 873 K in a vacuum. The maximum conversion efficiency of ∼8.8% for a temperature difference (ΔT) of 570 K and ∼11% for a ΔT of 590 K have been demonstrated in the nanostructured PbTe-based module and segmented Bi₂Te₃/nanostructured PbTe module, respectively. Three-dimensional finite-element simulations predict that the maximum conversion efficiency of the nanostructured PbTe-based module and segmented Bi₂Te₃/nanostructured PbTe module reaches 12.2% for a ΔT of 570 K and 15.6% for a ΔT of 590 K respectively, which could be achieved if the electrical and thermal contact between the nanostructured PbTe legs and Cu interconnecting electrodes is further improved.

The thermoelectric performance of room temperature Ag ₂ Se was greatly enhanced by stabilizing the crystal structure and eliminating metastability.

ZnO is a high melting point, high charge carrier mobility semiconductor with potential as a thermoelectric material, but its high thermal conductivity κ is the limiting factor for increasing the thermoelectric figure of merit ZT. Here, we demonstrate that doping ZnO with heavy elements can significantly enhance ZT. Indium doping leads to ultralow κ ∼ 3 W m⁻¹ K⁻¹ and a high power factor α²σ ∼ 1.230 × 10⁻³ W m⁻¹ K⁻², yielding ZT_1000K ∼ 0.45 that is ∼80% higher than non-nanostructured In–Zn–O alloys. Although Bi doping also yields a high Seebeck coefficient of α_300K ∼ 500 μV K⁻¹, Bi segregation, grain growth and defect complexing are unfavorable for increasing ZT. Thus, besides increased impurity scattering of phonons, the concurrence of nanostructuring and charge carrier concentration control is key to ZT enhancement. Our results open up a new means to realize high ZT thermoelectric nanomaterials based on ZnO.