Hierarchical structures lead to high thermoelectric performance in Cu_{: M + n} Pb₁₀₀Sb_m Te₁₀₀Se_{2 m} (CLAST)

Ternary compound CuSbSe2-alloyed PbTe, CumPb100SbmTe100Se2m (CLAST), presents outstanding n-type thermoelectric transport behavior and features hierarchical Cu-based precipitates and interstitials that can balance phonon and carrier transport. Results show that a small amount of CuSbSe2 (~3%) alloying in CLAST can realize a room-temperature carrier concentration of ~1.7 × 1018 cm-3 and then optimize the power factor, and simultaneously precipitate out embedded Cu-based nanostructures in the matrix to lower the lattice thermal conductivity. Additionally, extra Cu atoms adding in CLAST can form interstitials and further improve both the carrier concentration to ~3.0 × 1018 cm-3 and carrier mobility to ~1227.8 cm2 V-1 s-1 at room temperature, which benefits a maximum power factor of ~20.0 µW cm-1 K-2 in Cu3.3Pb100Sb3Te100Se6. Moreover, the Cu interstitials together with massive Cu-based nanoprecipitates can strongly scatter a wide set of phonons, and largely lower the lattice thermal conductivity to ~0.44 W m-1 K-1 in Cu3.4Pb100Sb3Te100Se6 at 623 K. Finally, these Cu-based hierarchical structures in CLAST samples can synergistically optimize the phonon and carrier transport properties and contribute to a high ZT of ~0.5 at 300 K and a peak ZT of ~1.4 at 723 K. A remarkably high ZTave of ~0.94 at 300-723 K is achieved in Cu3.3Pb100Sb3Te100Se6 due to high ZT values in the low temperature range, outperforming other high-performance n-type PbTe-based thermoelectric materials.