This paper presents tables of key thermoelectric properties, which define thermoelectric conversion efficiency, for a wide range of inorganic materials. The 12 families of materials included in these tables are primarily selected on the basis of well established, internationally-recognised performance and their promise for current and future applications: Tellurides, Skutterudites, Half Heuslers, Zintls, Mg-Sb Antimonides, Clathrates, FeGa3–type materials, Actinides and Lanthanides, Oxides, Sulfides, Selenides, Silicides, Borides and Carbides. As thermoelectric properties vary with temperature, data are presented at room temperature to enable ready comparison, and also at a higher temperature appropriate to peak performance. An individual table of data and commentary are provided for each family of materials plus source references for all the data.

The rapid growth of industrialization has resulted in an tremendous increase in energy demands. The vast amount of untapped waste heat found in factories and power plants can be harnessed to power devices. Thermoelectric materials enable a clean conversion of heat to electrical energy and vice versa, without the need for moving parts. However, existing thermoelectric generators are limited to capturing heat from exterior surfaces. Additive manufacturing offers itself as a cost-effective process that produces complex parts which can recover waste heat from direct heat flows. Herein, we report the first ever in situ energy harvester through porous 3D thermoelectrics. Complex 3D-printed Bi 0.5 Sb 1.5 Te 3 open cellular structures of high specific surface area are fabricated to allow a high rate of heat transfer throughout the heat pipes with negligible effect on the liquid flow. This work opens up exciting possibilities of energy harvesting from natural self-sustaining thermal gradients found in exhaust pipes and heat exchangers.

No abstract

No abstract

The conversion of waste heat into electricity plays a vital role in energy harvesting since conventional non‐renewable energy sources have been rapidly approaching the limit of utilization. The thermoelectric (TE) technology relies on converting temperature difference (or waste heat) into electricity or vice versa. The performance of TE materials is gauged by zT = S2T/ρκ, where S, ρ, κ, and T represent the Seebeck coefficient, the electrical resistivity, the total thermal conductivity, and the absolute temperature, respectively. Boron‐based compounds are considered refractory materials due to their high melting points and advanced chemical and mechanical stability. Besides high thermal stability, many borides exhibit intrinsically low thermal conductivity. The discovery of good TE efficiency in boron carbides, where unexpectedly high Seebeck coefficients (S(T) ≈ 250 µVK−1) are observed at high charge carrier densities (≈1021 cm−3), has induced an intense curiosity for the TE properties of other boron‐based compounds. Intermetallic borides with high boron content (>65 at%) are of particular interest among all known TE materials due to their great potential in TE generators, which can operate under extreme environmental conditions (T > 1000 K). This article reviews the TE properties of borides and state‐of‐art TE materials upon boron/borides doping.

Decades of studies on thermoelectric materials have enabled the design of high‐performance materials based on basic materials properties, such as bandgap engineering. In general, bandgap energies correspond to the temperature at which the peak thermoelectric performance occurs. For instance, CuGaTe2 with a relatively wide bandgap of 1.2 eV has its peak zT > 1 at > 900 K. On the other hand, the zT is usually very low (<0.1) for this material at room temperature. This severely limits its average zT and hence overall performance. In this study, a phase diagram‐guided Sb alloying strategy to improve the low‐temperature zT of CuGaTe2 is used, by leveraging on the solubility limits to control the formation of the microstructural defects. The addition of Sb simultaneously improves the electrical conductivity and decreases the lattice thermal conductivity. For a low‐temperature range of 300–623 K, this Sb‐alloying strategy enables the achievement of a record high average zT of 0.33. The strategy developed in this study targets the improvement of the low‐temperature range of CuGaTe2, which is rarely focused on for wide‐bandgap ABX2 compounds, opening up more opportunities for holistic performance improvements, potentially enabling ultrahigh‐performance thermoelectrics over a wide temperature range.

Bi 2 Te 3 -based alloys are widely utilized in Peltier coolers owing to their highest thermoelectric performance at nearroom-temperatures. However, their peak dimensionless thermoelectric figure of merit, zT, is limited to a narrow temperature window due to minority carrier excitation emerging upon heating at around 400 K. Here, we show how this issue can be overcome by incorporating a synthetic rickardite mineral, Cu 3−x Te 2 , in p-type (Bi, Sb) 2 Te 3 . The significant enhancement of the electronic and thermal properties could be achieved due to small Cu incorporation into the crystal structure of (Bi, Sb) 2 Te 3 and homogeneous precipitation of Cu 3−x Te 2 at the grain boundaries. This leads to a high average zT value (zT ave ) of 1.22 between 350 and 500 K for two compositions, Bi 0.5 Sb 1.5 Te 3 (BST-5) and Bi 0.3 Sb 1.7 Te 3 (BST-3), with peak zT values of 1.32 at 467 K and 1.30 at 400 K, respectively. These high zT values result in a considerably high maximum device ZT of ca. 1.15 and a theoretical efficiency of up to 7% between 325 and 525 K. Additionally, room-temperature micro-hardness is substantially improved, which is desirable for constructing reliable and durable thermoelectric modules.

No abstract