New Insights into Intrinsic Point Defects in V₂VI₃ Thermoelectric Materials

Abstract

Defects and defect engineering are at the core of many regimes of material research, including the field of thermoelectric study. The 60‐year history of V2VI3 thermoelectric materials is a prime example of how a class of semiconductor material, considered mature several times, can be rejuvenated by better understanding and manipulation of defects. This review aims to provide a systematic account of the underexplored intrinsic point defects in V2VI3 compounds, with regard to (i) their formation and control, and (ii) their interplay with other types of defects towards higher thermoelectric performance. We herein present a convincing case that intrinsic point defects can be actively controlled by extrinsic doping and also via compositional, mechanical, and thermal control at various stages of material synthesis. An up‐to‐date understanding of intrinsic point defects in V2VI3 compounds is summarized in a (χ, r)‐model and applied to elucidating the donor‐like effect. These new insights not only enable more innovative defect engineering in other thermoelectric materials but also, in a broad context, contribute to rational defect design in advanced functional materials at large.

Promising and Eco‐Friendly Cu2X‐Based Thermoelectric Materials: Progress and Applications

“…To secure high thermoelectric performance, high zT is required . As the temperature is generally limited by the application conditions or the employed material itself, the dominating factors for enhancing zT lie in enhancing S 2 σ, which is generally defined as the power factor to describe the electrical performance, as well as in reducing κ . For metals or degenerate semiconductors under the assumption of parabolic band and energy‐independent scattering approximation, S can be expressed as where k B is the Boltzmann constant, h is the Plank constant, and m * is the density of state effective mass.…”

Unique Role of Refractory Ta Alloying in Enhancing the Figure of Merit of NbFeSb Thermoelectric Materials

“…Strategies for increasing zT have focused on the reduction of the lattice thermal conductivity by hierarchical microstructure, [3,4] nanostructuring [5,6] point defects, [7,8] and the enhancement of the power factor (PF = α 2 σ) by optimal doping and band engineering [9][10][11] as well as the employment of complex crystal structures that possess intrinsically low lattice thermal conductivity. [12][13][14][15][16] Half-Heusler (HH) alloys, with a valence electron count of 8 or 18, have been extensively studied as potential hightemperature TE materials due to their excellent electrical properties, mechanical properties, and high temperature stability. [17][18][19] MNiSn-and MCoSb-based (M = Ti, Zr, Hf) HH alloys are the first two most studied families as n-type materials and p-type materials, respectively.…”

Native surface oxide turns alloyed silicon membranes into nanophononic metamaterials with ultralow thermal conductivity

“…The combination of native oxide layer and alloying with germanium in concentration as small as 5% reduces the thermal conductivity of silicon membranes to 100 time lower than the bulk. In addition, the resonance mechanism produced by native oxide surface layers is particularly effective for thermal condutivity reduction even at very low temperatures, at which only low frequency modes are populated.Controlling terahertz vibrations and heat transport in nanostructures has a broad impact on several applications, such as thermal management in micro-and nano-electronics, renewable energies harvesting, sensing, biomedical imaging and information and communication technologies [1][2][3][4][5][6][7][8]. Significant efforts have been made to understand and engineer heat transport in nanoscale silicon due to its natural abundance and technological relevance [9][10][11][12].…”