Realizing the Interface Tuned Thermoelectric Transport Performance in Bi₂Te₃-Based Hierarchical Nanostructures

Hierarchical Te/Bi₂Te₃ and Bi₂Te₃ nanostructures are synthesized by using a one-pot solvothermal method and sintered into pellets by spark plasma sintering (SPS), individually. The thermoelectric properties measurement indicates the electrons/phonon transport is directly influenced by interface state of the hierarchical nanostructures. As compared to Te/Bi₂Te₃ heterostructures, the higher energy barrier at the interface of homostructured Bi₂Te₃ (71 meV) leads to the energy filtering effect on the electronic transport and the optimized power factor in the Bi₂Te₃ pellet. The thermal conductivity is remarkably reduced because of the strong scattering between phonons and high-density defects in both samples. As a result, an enhanced ZT value (0.58) of the Bi₂Te₃ nanowires was obtained at 353 K. Importantly, the average ZT (0.56), which is comparable to the peak ZT of both samples, is dramatically improved in these hierarchical nanostructures in the temperature range of 313-433 K.