Hierarchical structures lead to high thermoelectric performance in Cum+nPb100SbmTe100Se2m (CLAST)

Ternary compound CuSbSe2-alloyed PbTe, CumPb100SbmTe100Se2m (CLAST), presents outstanding n-type thermoelectric transport behavior and features with the hierarchical Cu-based precipitates and interstitials that can balance phonon and carrier transports. Results show that small amount of CuSbSe2 (~ 3%) alloying in CLAST can realize the room-temperature carrier concentration ~ 1.7×1018 cm-3 and then optimize the power factor, and simultaneously precipitate out embedded Cu-based nanostructures in matrix to lower 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-3and carrier mobility to ~ 1227.8 cm2v-1s-1 at room temperature, which benefits a maximum power factor of ~ 20.0 μWcm−1K−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 Wm−1K−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 remarkable high ZTave of ~ 0.94 at 300-723 K is achieved in Cu3.3Pb100Sb3Te100Se6 due to high ZT values in low temperature range, outperforming other high-performance n-type PbTe-based thermoelectric materials.