Large thermoelectric power factor at low temperatures in one-dimensional telluride Ta₄SiTe₄

We report the discovery of a very large thermoelectric power over –400 μV K⁻¹ in the whisker crystals of a one-dimensional telluride Ta₄SiTe₄, while maintaining a low electrical resistivity of ρ = 2 mΩ cm, yielding a very large power factor of P = 80 μW cm⁻¹K⁻² at an optimum temperature of 130 K. This temperature is widely controlled from the cryogenic temperature of 50 K to room temperature by chemical doping, resulting in the largest P of 170 μW cm⁻¹K⁻² at 220–280 K. These P values far exceed those of the Bi₂Te₃-Sb₂Te₃ alloys at around room temperature, offering an avenue for realizing the practical-level thermoelectric cooling at low temperatures. The coexistence of a one-dimensional electronic structure and a very small band gap appearing in the vicinity of the Dirac semimetals probably causes the very large power factors in Ta₄SiTe₄, indicating that the “one-dimensional Dirac semimetal” is a promising way to find high-performance thermoelectric materials for the low temperature applications.