Peierls distortion as a route to high thermoelectric performance in In4Se3-δ crystals

Abstract

Thermoelectric energy harvesting-the transformation of waste heat into useful electricity-is of great interest for energy sustainability. The main obstacle is the low thermoelectric efficiency of materials for converting heat to electricity, quantified by the thermoelectric figure of merit, ZT. The best available n-type materials for use in mid-temperature (500-900 K) thermoelectric generators have a relatively low ZT of 1 or less, and so there is much interest in finding avenues for increasing this figure of merit. Here we report a binary crystalline n-type material, In(4)Se(3-delta), which achieves the ZT value of 1.48 at 705 K-very high for a bulk material. Using high-resolution transmission electron microscopy, electron diffraction, and first-principles calculations, we demonstrate that this material supports a charge density wave instability which is responsible for the large anisotropy observed in the electric and thermal transport. The high ZT value is the result of the high Seebeck coefficient and the low thermal conductivity in the plane of the charge density wave. Our results suggest a new direction in the search for high-performance thermoelectric materials, exploiting intrinsic nanostructural bulk properties induced by charge density waves.

High-performance nanostructured thermoelectric materials

“…Th is review covers the latest advancements in TE technology focusing on such nanostructural approaches, and in doing so aims to highlight the potential routes for improvement in the major TE material systems, including Bi-Te alloys, skutterudites, Ag-Pb-Sb-Te or 'LAST', half-Heusler alloys and some high-ZT oxides. Certainly, there are also other useful approaches for enhancing TE properties, such as band structure engineering by doping [17,20] and exploring new materials with complex crystalline structure [21,22], but such approaches are beyond the scope of the current review.…”

High-temperature thermoelectric properties of the β-As2−xBixTe3 solid solution

“…Of note, these values are significantly lower than those measured in Bi 2 Te 3 -based alloys but similar to those achieved in α-As 2 Te 3 or in other chalcogenides. 2,10,[22][23][24][25][26][27] In the parallel direction, κ L approaches the lowest limit of the thermal conductivity (Figure 2(c)) estimated using the model developed by Cahill and Pohl and the measured longitudinal and transverse sound velocities. 13,[28][29][30] Figure 2(d), which shows the variations in temperature of the ZT values, indicates that ZT increases with temperature for all samples.…”

Estimating Energy Conversion Efficiency of Thermoelectric Materials: Constant Property Versus Average Property Models

“…We first reproduced the calculations of Kim et al 11 for the compounds SnSe, 12 In 4 Se 3-x , 13 24 The ZT values (calculated from the extracted transport coefficients) as a function of temperature for the three materials are shown in Fig. 2a; the calculated efficiencies g (T C = 373 K) based on Eqs.…”

“…11 For large temperature differences and/or materials with strongly temperature-dependent transport properties, e.g. the binary compounds SnSe 12 and In 4 Se 3-x , 13 Kim et al demonstrated that Eq. 1 can significantly overestimate the energy conversion efficiency in comparison to predictions from finite difference numerical simulations.…”