Coherent Sb/CuTe Core/Shell Nanostructure with Large Strain Contrast Boosting the Thermoelectric Performance of n-Type PbTe

The exploration of n-type PbTe as thermoelectric materials always falls behind its p-type counterpart, mainly due to their quite different electronic band structure. In this work, elemental Sb and Cu2Te are introduced into an n-type base material (PbTe)(81)-Sb2Te3. The introduction of extra Sb can effectively tune the concentration of electrons; meanwhile, Sb precipitates can also scatter low-energy electrons (negatively contribute to the Seebeck coefficient) thus enhance the overall Seebeck coefficient. The added Cu2Te is found to always co-precipitate with Sb, forming an interesting Sb/CuTe core/shell structure; moreover, the interface between core/shell precipitates and PbTe matrix simultaneously shows coherent lattice and strong strain contrast, beneficial for electron transport but adverse to phonon transport. Eventually, a peak figure of meritZT(max) approximate to 1.6 @ 823K and simultaneously an averageZT approximate to 1.0 (323-823 K) are realized in the (PbTe)(81)Sb2Te3-0.6Sb-2Cu(2)Te sample, representing the state of the art for n-type PbTe-based thermoelectric materials. Moreover, for the first time the three existing forms of Cu atoms in Cu2Te alloyed PbTe are unambiguously clarified with aberration-corrected scanning transmission electron microscopy (C-s-STEM).

Automated summary

The introduction of Sb and Cu2Te into an n-type base material (PbTe)(81)-Sb2Te3 effectively tunes the electron concentration and enhances the overall Seebeck coefficient. The co-precipitation of Sb and Cu2Te forms an interesting Sb/CuTe core/shell structure, showing interface characteristics beneficial for electron transport but adverse to phonon transport. The peak ZT(max) of approximately 1.6 @ 823K and averageZT of approximately 1.0 (323-823 K) are achieved in the (PbTe)(81)Sb2Te3-0.6Sb-2Cu(2)Te sample, representing the current state of the art for n-type PbTe-based thermoelectric materials.