Recent advances in high-performance bulk thermoelectric materials

Abstract

Thermoelectric (TE) materials facilitate direct heat-to-electricity conversion. The performance of a TE material is characterised by its figure of merit zT (=S 2 σT/κ) that depends on both electronic transport properties, i.e. the Seebeck coefficient S and the electrical conductivity σ, and on thermal transport properties, i.e. the thermal conductivity κ of a material. The intrinsically countercorrelated behaviour between electronic and thermal transport properties makes the enhancement of zT a very challenging task. In the past 10 years, the zTs in bulk TE materials have been significantly enhanced due to intensive exploratory efforts, the discovery of new physical phenomena and effects, and applications of advanced synthesis methods. In this review, we summarise the recent progress in bulk TE materials. After the introduction of fundamental principles of thermoelectricity, the recently achieved enhancements in the TE performance encompassing the use of electronic band structure engineering, lattice phonon engineering and nanostructure tailoring will be emphasised. Next, the highlights of typical TE materials will be presented, focusing especially on the great progress achieved during the past decade. Finally, new techniques and approaches developed to fabricate TE materials will be outlined and their impact on the performance and economic viability of large-scale TE applications will be considered. The progress made during the past dozen or so years provides great opportunities for the use of bulk TE materials in a much broader range of applications and bodes well for a more efficient utilisation of energy.

Enhancing the thermoelectric performance of Cu3SnS4-based solid solutions through coordination of the Seebeck coefficient and carrier concentration

“…Here κ e is expressed by the Wiedemann-Franz law, κ e = L 0 σT, where L 0 is the Lorenz number, estimated as 2.0×10 -8 WΩK -2 for the current semiconductors, 23 close to the value (~2.2×10 -8 WΩK -2 ) reported in ref. [24].…”

Valleytronics in thermoelectric materials

“…16 Some excellent reviews focusing on the thermal transport aspects of TE study 17,18 as well as several good comprehensive TE reviews introducing the synergistic design strategies of TE materials have been published in recent years. 1,11,19,20 Nevertheless, there exists a threshold for zT improvement from reducing the thermal conductivity, which is limited to a theoretical minimum (amorphous limit). 21 In contrast there is no theoretical bound to the PF, which leads to the boundless nature of zT.…”

High thermoelectric performance and low thermal conductivity in Cu2−yS1/3Se1/3Te1/3 liquid-like materials with nanoscale mosaic structures

“…Thermoelectric (TE) materials, which are capable of direct and reversible conversion between heat and electricity, have attracted widespread research interests due to their advantages of no moving parts, no mechanical or chemical processes involved, emission free, high durability, and reliability [1][2][3][4][5]. TE technology shows a great potential in a variety of applications such as spot cooling and power generation using waste heat [6].…”