Improved Thermoelectric Performance of p-Type PbTe by Entropy Engineering and Temperature-Dependent Precipitates.

Entropy engineering is aneffective scheme to reduce the thermal conductivity of thermoelectric materials, but it inevitably deteriorates the carrier mobility. Here, we report the optimization of thermoelectric performance of PbTe by combining entropy engineering and nanoprecipitates. In the continuously tuned compounds of Pb0.98Na0.02Te(1-2x)SxSex, we show that the x = 0.05 sample exhibits an exceptionally low thermal conductivity relative to its configuration entropy. By introducing Mn doping, the produced temperature-dependent nanoprecipitates of MnSe cause the high-temperature thermal conductivity to be further reduced. A very low lattice thermal conductivity of 0.38 W m-1 K-1 is achieved at 825 K. Meanwhile, the carrier mobility of the samples is only slightly influenced, owing to the well-controlled configuration entropy and the size of nanoprecipitates. Finally, a high peak zT of ∼2.1 at 825 K is obtained in the Pb0.9Na0.04Mn0.06Te0.9S0.05Se0.05 alloy.