Thermoelectric (TE) materials have the capability of converting heat into electricity, which can improve fuel efficiency, as well as providing robust alternative energy supply in multiple applications by collecting wasted heat, and therefore, assisting in finding new energy solutions. In order to construct high performance TE devices, superior TE materials have to be targeted via various strategies. The development of high performance TE devices can broaden the market of TE application and eventually boost the enthusiasm of TE material research. This review focuses on major novel strategies to achieve high-performance TE materials and their applications. Manipulating the carrier concentration and band structures of materials are effective in optimizing the electrical transport properties, while nanostructure engineering and defect engineering can greatly reduce the thermal conductivity approaching the amorphous limit. Currently, TE devices are utilized to generate power in remote missions, solar-thermal systems, implantable or/wearable devices, the automotive industry, and many other fields; they are also serving as temperature sensors and controllers or even gas sensors. The future tendency is to synergistically optimize and integrate all the effective factors to further improve the TE performance, so that highly efficient TE materials and devices can be more beneficial to daily lives.

https://espace.library.uq.edu.au/view/UQ:722903/UQ722903_OA.pdf

High Performance Thermoelectric Materials: Progress and Their Applications

The deceptively simple material SnSe has surprised the scientific community by showing an unexpectedly low thermal conductivity and high power factor and it has become a very promising thermoelectric material. Both the electrical and thermal transport properties of SnSe are outstanding. It is remarkable that a binary compound exhibits strong anharmonic and anisotropic bonding, and after hole doping it shows an exceptionally high power factor because of a high electrical conductivity and a strongly enhanced Seebeck coefficient. The latter is enabled by the contribution of multiple electronic valence bands. In this perspective, we discuss the natural features of SnSe, including crystal structures, electronic band structures, and physical and chemical properties. We also compare the electrical transport properties of single crystals and polycrystalline SnSe. The thermal conductivities of polycrystalline samples show wide variation from laboratory to laboratory, with some values being higher than those of single crystals and some lower, which has caused confusion and controversy. To address the issues regarding the thermal transport properties of SnSe, we systematically summarize the reports for SnSe variants, discuss them along with some of our own new results, and offer possible explanations. Finally, some possible strategies are proposed toward future enhancements of the thermoelectric figure of merit of SnSe.

SnSe: a remarkable new thermoelectric material

https://espace.library.uq.edu.au/view/UQ:e38288a/UQe38288a_OA.pdf

High-performance SnSe thermoelectric materials: Progress and future challenge

Thermoelectric (TE) materials facilitate direct heat-to-electricity conversion. The performance of a TE material is characterised by its figure of merit zT (=S2 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 counter-correlated 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 phon...

Recent advances in high-performance bulk thermoelectric materials

Molybdenum diselenide (MoSe2) for energy storage, catalysis, and optoelectronics

Large-area and highly crystalline CVD-grown multilayer MoSe2 films exhibit a well-defined crystal structure (2H phase) and large grains reaching several hundred micrometers. Multilayer MoSe2 transistors exhibit high mobility up to 121 cm(2) V(-1) s(-1) and excellent mechanical stability. These results suggest that high mobility materials will be indispensable for various future applications such as high-resolution displays and human-centric soft electronics.

High-Mobility Transistors Based on Large-Area and Highly Crystalline CVD-Grown MoSe2 Films on Insulating Substrates.

Indium substitution effect on thermoelectric and optical properties of Sn1-xInxSe compounds

Enhancement of thermoelectric properties in liquid-phase sintered Te-excess bismuth antimony tellurides prepared by hot-press sintering

Researchers have long been searching for the materials to enhance thermoelectric performance in terms of nano scale approach in order to realize phonon-glass-electron-crystal and quantum confinement effects. Peierls distortion can be a pathway to enhance thermoelectric figure-of-merit ZT by employing natural nano-wire-like electronic and thermal transport. The phonon-softening known as Kohn anomaly, and Peierls lattice distortion decrease phonon energy and increase phonon scattering, respectively, and, as a result, they lower thermal conductivity. The quasi-one-dimensional electrical transport from anisotropic band structure ensures high Seebeck coefficient in Indium Selenide. The routes for high ZT materials development of In₄Se₃-δ are discussed from quasi-one-dimensional property and electronic band structure calculation to materials synthesis, crystal growth, and their thermoelectric properties investigations. The thermoelectric properties of In₄Se₃-δ can be enhanced by electron doping, as suggested from the Boltzmann transport calculation. Regarding the enhancement of chemical potential, the chlorine doped In₄Se₃-δCl0.03 compound exhibits high ZT over a wide temperature range and shows state-of-the-art thermoelectric performance of ZT = 1.53 at 450 °C as an n-type material. It was proven that multiple elements doping can enhance chemical potential further. Here, we discuss the recent progress on the enhancement of thermoelectric properties in Indium Selenides by increasing chemical potential.

Jin Hee Kim

Papers

High-Mobility Transistors Based on Large-Area and Highly Crystalline CVD-Grown MoSe2 Films on Insulating Substrates.

Indium substitution effect on thermoelectric and optical properties of Sn1-xInxSe compounds

Enhancement of thermoelectric properties in liquid-phase sintered Te-excess bismuth antimony tellurides prepared by hot-press sintering

Chemical Potential Tuning and Enhancement of Thermoelectric Properties in Indium Selenides.

Thermoelectric properties of Se-deficient and Pb-/Sn-codoped In4Pb0.01Sn0.03Se3−x polycrystalline compounds