Tellurium as a high-performance elemental thermoelectric

Abstract

High-efficiency thermoelectric materials require a high conductivity. It is known that a large number of degenerate band valleys offers many conducting channels for improving the conductivity without detrimental effects on the other properties explicitly, and therefore, increases thermoelectric performance. In addition to the strategy of converging different bands, many semiconductors provide an inherent band nestification, equally enabling a large number of effective band valley degeneracy. Here we show as an example that a simple elemental semiconductor, tellurium, exhibits a high thermoelectric figure of merit of unity, not only demonstrating the concept but also filling up the high performance gap from 300 to 700 K for elemental thermoelectrics. The concept used here should be applicable in general for thermoelectrics with similar band features.

Low Sound Velocity Contributing to the High Thermoelectric Performance of Ag8SnSe6

“…The details on the microstructural characterizations including powder X‐ray diffraction and (scanning) transmission electron microscope [(S)TEM], the measurements of the transport properties including resistivity, Seebeck coefficient, Hall coefficient, and thermal conductivity were given elsewhere 5, 7. Measurements of sound velocities were carried out on the pellet samples at room temperature.…”

“…One successful strategy for improving zT is to enhance the power factor S 2 / ρ through band engineering,2, 3, 4, 5, 6, 7 provided the carrier concentration is optimized 8. The other effective strategy is typified by minimizing the only one independent material property, the lattice thermal conductivity ( κ L ), through nanostructuring,9, 10, 11, 12, 13, 14, 15 liquid phonons,16, 17 and lattice anharmonicity 18, 19…”

Electronic origin of the high thermoelectric performance of GeTe among the p-type group IV monotellurides

“…Effective approaches include nanostructuring, 2-7 lattice anharmonicity, 8,9 liquid phonons, 10,11 vacancy [12][13][14] or interstitial 15 point defects and a low sound velocity. 16 Band engineering concepts including a large number of degenerated bands, [17][18][19][20][21][22][23][24][25] a low band effective mass 26 and weak carrier scattering 27 have also proven to be successful in enhancing the TE performance. The knowledge of the band structure is thus critical for band engineering and optimizing the electrical transport of TE materials.…”

Self‐Tuning n‐Type Bi2(Te,Se)3/SiC Thermoelectric Nanocomposites to Realize High Performances up to 300 °C

“…With two‐thirds of the primary energy is lost as waste heat (low‐temperature region at 100–300 °C constitutes over 50%),3 there is a high demand for stable thermoelectric performance in low‐temperature range up to 300 °C. Although some new thermoelectric materials have been developed with promising performance in the temperature range of 200 to 300 °C so far,15, 16, 17 optimizing the thermoelectric performance of the widely used Bi 2 Te 3 ‐based alloys in this temperature range is technically attractive. Presently, shifting the zT to higher temperatures is still challenging considering the small band gap of Bi 2 Te 3 ( E g = 0.13 eV), in which intrinsic excitation of minority carriers happens easily at high temperatures and thus leads to a rapid decrease of Seebeck coefficient and huge increase of the thermal conductivity 18, 19.…”