Enhanced atomic ordering leads to high thermoelectric performance in AgSbTe2

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Science  12 Feb 2021:
Vol. 371, Issue 6530, pp. 722-727
DOI: 10.1126/science.abb3517

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Ordering up better conductivity

Improving a thermoelectric material's ability to convert heat to electricity involves optimizing one property without changing another in a detrimental way. Roychowdhury et al. found that cadmium doping of silver antimony telluride enhances cationic ordering, which simultaneously improves electric properties and helpfully decreases thermal conductivity (see the Perspective by Liu and Ibáñez). This strategy markedly improves thermoelectric properties and could be used for other materials.

Science, this issue p. 722; see also p. 678


High thermoelectric performance is generally achieved through either electronic structure modulations or phonon scattering enhancements, which often counteract each other. A leap in performance requires innovative strategies that simultaneously optimize electronic and phonon transports. We demonstrate high thermoelectric performance with a near room-temperature figure of merit, ZT ~ 1.5, and a maximum ZT ~ 2.6 at 573 kelvin, by optimizing atomic disorder in cadmium-doped polycrystalline silver antimony telluride (AgSbTe2). Cadmium doping in AgSbTe2 enhances cationic ordering, which simultaneously improves electronic properties by tuning disorder-induced localization of electronic states and reduces lattice thermal conductivity through spontaneous formation of nanoscale (~2 to 4 nanometers) superstructures and coupling of soft vibrations localized within ~1 nanometer around cadmium sites with local strain modulation. The strategy is applicable to most other thermoelectric materials that exhibit inherent atomic disorder.

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