Authors: Shixuan Liu, Yong Yu, Di Wu, Xiao Xu, Xiaolian Chao, Zupei Yang, Jiaqing He
Published: 2021-10-21
Source: Full article
AbstractLead telluride (PbTe) has long been regarded as an excellent thermoelectric material at intermediate temperature range (573–873 K); however, n‐type PbTe's performance is always relatively inferior to its p‐type counterpart mainly due to their different electronic band structures. In this work, an ultrahigh thermoelectric quality factor (µ/κL ≈ 1.36 × 105 cm3 KJ−1 V−1) is reported in extra 0.3% Cu doped n‐type (PbTe)0.9(PbS)0.1 as‐cast ingots. Transmission electron microscopy (TEM) characterization reveals that excess PbS exists in PbTe matrix as strained endotaxial nanoprecipitates, which affect electrical and thermal conduction discriminately: (1) coherent PbTe/PbS lattice minimizes the interface scattering of charge carriers; (2) periodic strain centers at PbTe/PbS interface exhibit intensive strain contrast, which can strongly scatter heat‐carrying phonons. Electron backscattered diffraction (EBSD) characterization illustrates very large PbTe grains (≈1 mm) in these as‐cast ingots, ensuring an extremely low grain boundary scattering rate thus a very high charge carrier mobility. Eventually, a remarkably high ZTmax ≈ 1.5 at 773 K and an outstanding ZTavg ≈ 1.0 between 323 and 773 K are simultaneously achieved in the (PbTe)0.9(PbS)0.1 +0.3%Cu sample; these values are highly competitive with reported state‐of‐art n‐type PbTe materials.