Sb Alloying for Engineering High‐Thermoelectric zT of CuGaTe₂

Abstract

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.

Thermoelectrics for nuclear fusion reactors: opportunities and challenges

“…2. Although many of the TE materials can achieve high zT s of >2, such as GeTe, 23–34 PbTe, 35–39 and SnSe, 40–44 and others exhibit peak performances in the medium temperature range (473–973 K), 45–53 such TE materials will not be considered for discussion in this review, as they overlap with the operating temperature range of the much more efficient existing heat cycle of the molten salt coolant. Instead, for reliable performance on the plasma-facing surfaces, one should select from the tried and tested high temperature (873–1273 K) TE materials that have been used or assessed for RTGs in deep space probes, such as Si 1− x Ge x , La 3− x Te 4 and Yb 14 MgSb 11 zintls.…”

“…As the research on TE materials advanced over the years, many effective strategies and paradigms have been explored and developed to not only enhance the peak zT but also the average zT over a wide temperature gradient (from room temperature to the highest measured temperature). Such strategies include band convergence, 8,43–51 resonant levels, 52–58 all-scale hierarchal defect architectures, 59–65 off-centred and discordant atoms, 66–68 metavalent bonding, 69–74 minority carrier blocking additives, 75–78 and wide band-gap and layered structures. 10,79–84 While there has been a general push in recent years to enhance the average zT , perhaps for the plasma-facing applications, with a useful temperature range of 973–1273 K or above, it would be more feasible to revert back to the old focus of enhancing peak zT at the highest temperature as the minimum cold side temperature is still rather high (∼973 K).…”

Suppressing Ag2Te nanoprecipitates for enhancing thermoelectric efficiency of AgSbTe2

“…[11][12][13][14][15] Furthermore, researchers have explored a range of strategies to effectively reduce lattice thermal conductivity, including the introduction of various types of defects, the manipulation of lattice anharmonicity, the utilization of complex structures, and the application of lattice strain. [16][17][18][19][20][21][22][23][24] In recent years, several standout materials have risen to prominence as top performers in the field of thermoelectrics. Notable among these are compounds based on GeTe, SnSe, Cu 2 Se, Mg 3 Sb 2 , and AgSbTe 2 .…”