Defect‐Engineering‐Stabilized AgSbTe₂ with High Thermoelectric Performance

Abstract

Thermoelectric (TE) generators enable the direct and reversible conversion between heat and electricity, providing applications in both refrigeration and power generation. In the last decade, several TE materials with relatively high figures of merit (zT) have been reported in the low‐ and high‐temperature regimes. However, there is an urgent demand for high‐performance TE materials working in the mid‐temperature range (400–700 K). Herein, p‐type AgSbTe2 materials stabilized with S and Se co‐doping are demonstrated to exhibit an outstanding maximum figure of merit (zTmax) of 2.3 at 673 K and an average figure of merit (zTave) of 1.59 over the wide temperature range of 300–673 K. This exceptional performance arises from an enhanced carrier density resulting from a higher concentration of silver vacancies, a vastly improved Seebeck coefficient enabled by the flattening of the valence band maximum and the inhibited formation of n‐type Ag2Te, and ahighly improved stability beyond 673 K. The optimized material is used to fabricate a single‐leg device with efficiencies up to 13.3% and a unicouple TE device reaching energy conversion efficiencies up to 12.3% at a temperature difference of 370 K. These results highlight an effective strategy to engineer high‐performance TE material in the mid‐temperature range.

Thermoelectric Performance of Surface-Engineered Cu1.5–xTe–Cu2Se Nanocomposites

“…17−20 As TE devices are generally produced using high-density bulk materials and operate at relatively high temperatures, the sintering and stabilization of the TE materials are fundamental steps. 21 A key challenge of sintering nano-/microsized powders is to prevent uncontrolled grain growth while still achieving full densification. While sintering and grain growth depend on surface diffusion, 22−24 surface engineering is a powerful approach to control grain growth and further adjust the final composite composition and its functional properties.…”

“…As TE devices are generally produced using high-density bulk materials and operate at relatively high temperatures, the sintering and stabilization of the TE materials are fundamental steps . A key challenge of sintering nano-/microsized powders is to prevent uncontrolled grain growth while still achieving full densification.…”

Engineering of Thermoelectric Composites Based on Silver Selenide in Aqueous Solution and Ambient Temperature

“…Thermoelectric (TE) devices allow for direct, solid state, and reversible conversion between heat and electricity. − TE devices can harvest heat from the ambient environment, potentially increasing the efficiency of a plethora of processes. They also allow precise control of the temperature and effective cooling of hot spots.…”

Surface Chemistry and Band Engineering in AgSbSe2: Toward High Thermoelectric Performance

“…I–V–VI 2 ternary chalcogenide semiconductors have gathered increasing attention due to their excellent functional properties. At the same time, the multiple possibilities of these materials, associated with their numerous degrees of freedom, leave plenty of room for improvement and optimization. , AgSbTe 2 is widely studied as a promising TE material for low-medium temperature power generation due to its intrinsically low κ (0.6–0.7 W m –1 K –1 ) and large S (>300 μV K –1 ), − especially when alloyed with PbTe (LAST-m) − or GeTe (TAGS). ,, Very recently, Cd-doped polycrystalline AgSbTe 2 achieved an ultrahigh zT ≈ 2.6 at 573 K by tuning disorder-induced localization of electronic states and reduced lattice thermal conductivity (κ L ) through the spontaneous formation of nanoscale superstructures. , However, at temperatures below 633 K, AgSbTe 2 slowly decomposes into secondary phases: α-Ag 2 Te and Sb 2 Te 3 , which together with the scarcity of Te hampers the practical application of AgSbTe 2 -based materials. , The straightforward Te-free alternative to AgSbTe 2 is AgSbSe 2 , which despite its potential has been relatively underexplored.…”

“…30,31 However, at temperatures below 633 K, AgSbTe 2 slowly decomposes into secondary phases: α-Ag 2 Te and Sb 2 Te 3 , which together with the scarcity of Te hampers the practical application of AgSbTe 2 -based materials. 30,32 The straightforward Te-free alternative to AgSbTe 2 is AgSbSe 2 , which despite its potential has been relatively underexplored.…”