Large Thermoelectric Power Factor at Low Temperatures in One-Dimensional Telluride Ta4SiTe4

TL;DR

This study discovers that one-dimensional telluride Ta4SiTe4 exhibits exceptionally high thermoelectric power factors at low temperatures, promising for cryogenic cooling applications due to its unique electronic structure.

Contribution

It reports the first observation of large thermoelectric power factors in Ta4SiTe4, highlighting the role of one-dimensional Dirac semimetal characteristics in thermoelectric performance.

Findings

Achieved a power factor of 80 microW cm-1 K-2 at 130 K

Doping increased power factor to 170 microW cm-1 K-2 at 220-280 K

Outperforms Bi2Te3-Sb2Te3 alloys at room temperature

Abstract

We report the discovery of a very large thermoelectric power over -400 microV K-1 in the whisker crystals of a one-dimensional telluride Ta4SiTe4, while maintaining a low electrical resistivity of rho = 2 mohm cm, yielding a very large power factor of P = 80 microW cm-1 K-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 microW cm-1 K-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.