Synergistic optimization of electrical and thermal transport in n-type Bi-doped PbTe by introducing coherent nanophase Cu1.75Te

Based on the calculated results of band structures and density of states, Bi doping is used to adjust its carrier concentration in order to obtain n-type PbTe materials with high power factor. Then, coherent nanophase Cu 1.75 Te is in situ formed in the n-type PbTe matrix, which can simultaneously optimize the thermal and electrical properties. As a result, at a relative lower temperature than other reports, the highest ZT value of 1.4 is obtained at 623 K for the nominal Pb 0.995 Bi 0.005 Te+0.86 wt% Cu 1.75 Te sample. More importantly, the ZT hold a higher value in the broad temperature; especially, ZT value is about 1.2–1.4 in the temperature range of 573–773 K, which is beneficial to the significant average ZT value ZT ave  ∼ 0.9 in the temperature range of 300–773 K. These results indicate that it is an effective and feasible method to enhance the thermoelectric properties via synergistic modulation of electrical and thermal transport properties by element doping and in situ coherent nanophase.