Introduction . Thermoelectric (TE) materials are capable of converting heat energy into electricity without additional pollution, promising to alleviate the energy shortage and environmental pollution caused by energy use1 , 2 , 3. Conventionally, the conversion efficiency of TE materials is measured by the figure of merit \(zT=\frac{{S}^{2}\sigma T}{{\kappa }_{{{{\rm{e}}}}}+{\kappa }_{{{{\rm{L}}}}}}\), in which S , σ , κe , κL , and T are the thermopower, e...