Enhanced thermoelectric performance of Se-doped PbTe bulk materials via nanostructuring and multi-scale hierarchical architecture

- Increased grain boundaries and dislocations introduced by solely doping Se.
- Annealing treatment in hydrothermal synthesis results in relatively high power factor.
- Multi-scale hierarchical architecture is established.
- The low lattice thermoelectric conductivity with multi-wavelength phonon scattering.
- The peak ZT of 0.98 is achieved in n-type PbTe1-xSex (x = 0.06) alloys.

The combination of feasible bottom-up hydrothermal synthesis is demonstrated to notably enhance thermoelectric performance of the PbTe matrix with different Se-doped contents. The instinct electrical properties are improved by annealing with reducing gas to achieve relatively high power factor. Furthermore, multi-scale hierarchical architecture is established together with the point defects and dislocations introduced by doping Se and the formation of nanoscale participates, couple with increased boundaries and a large grain size scale from 20 nm to 1.5 μm and, resulting in scattering an even broader frequency spectrum of phonon mean free path to reduce the lattice thermal conductivity effectively. Consequently, it plays an essential synergistic optimization to achieve a maximum ZT value of 0.98 at 625 K from the as-prepared n-type PbTe1-xSex (x = 0.06) alloys. This study provides a facile and low-cost method to fabricate multi-scale hierarchical architecture materials on a large scale with significant enhancement of thermoelectric performance.

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