Enhanced atomic ordering leads to high thermoelectric performance in AgSbTe2. Science, 2021, 371, 722-727

Enhanced atomic ordering leads to high thermoelectric performance in AgSbTe2. Science, 2021, 371, 722-727

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. 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)

Fig. Schematic of disorder-tuning of electronic structure and thermoelectric performance of Cd-doped polycrystalline AgSbTe2. (A) A schematic of disorder-tuning of mobility edge (Ec) separating the localized electronic states from the extended ones and how it affects the electrical conductivity (s) and Seebeck coefficient (S). EF denotes the Fermi energy. The horizontal red arrow denotes the shift in Ec toward the Fermi energy EF with increasing disorder. (B and C) Comparison of (B) thermoelectric figure of merit (ZT) and (C) device figure of merit (ZTdev), respectively, of Cd-doped polycrystalline AgSbTe2 with other state-of-the-art thermoelectric materials