Ultra-high thermoelectric performance in SnTe by the integration of several optimization strategies

Using nanostructures to improve the performance of bulk thermoelectric materials is a very effective and prevailing method. The integration of several optimization strategies into a single thermoelectric material using multi-nanostructure doping can optimize the properties at multiple levels. In this work, we use the combination of the energy filtering effect and conductive channels to greatly optimize the thermoelectric performance of SnTe. Specifically, we first incorporated Mg3.2Sb0.6Bi1.4 alloy nanoparticles into Sn1.03Te. As an n-type semiconductor, Mg3.2Sb0.6Bi1.4 can not only effectively neutralize the excessive hole in p-type SnTe, but also generate energy filtering effect due to the P–N junction barrier. Thus, the electronic thermal conductivity and the Seebeck coefficient are optimized. Then, the conductive channel constructed by doping multi-walled carbon nanotubes (MWCNTs) was used to further improve the thermoelectric properties of SnTe. When carriers are transported in the conductive channel, the interference of lattice structure and other factors can be effectively reduced so that the mobility of carriers can be further improved. In addition, we introduce Bi elemental elements to enhance the high frequency phonon scattering based on the existing optimization. As a result of this synergistic effect, an ultralow κtot ∼0.96 Wm−1K−1 and a high ZT ∼1.56 are obtained at 873 K in SnBi0.03Te-1% Mg3.2Sb0.6Bi1.4-0.2% MWCNTs.