Enhanced atomic ordering leads to high thermoelectric performance in AgSbTe ₂

Abstract

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.

Slowing down the heat in thermoelectrics

“…The introduction of multiscale extrinsic defects to reduce κ lat has become a very advanced approach in the thermoelectric field 26,86–94 . Additionally, the new concepts of atomic ordering and high‐entropy engineering have recently been found to be effective in decreasing κ lat and enhancing the ZT values of various materials 27,95 . The heat in the lattice is carried by phonons of several modes and frequencies, and κ lat is the sum of all thermal conductivities 1 .…”

Enhanced Band Convergence and Ultra‐Low Thermal Conductivity Lead to High Thermoelectric Performance in SnTe

“…Waste heat is ubiquitous end or side product of most of the energy usage cycle.U se of thermoelectric (TE) material to convert wasted heat to electricity is an emerging solution. [1][2][3][4][5][6] Theperformance of aTEmaterial is governed by fundamental parameters such as Seebeck coefficient (S), electrical conductivity (s)a nd total thermal conductivity ((k tot ) = electronic (k e ) + lattice (k lat )t hermal conductivity), which all together give rise to the dimension less figure of merit:z T= S 2 sT/(k e + k lat ). However,the extreme entangled relationship among these parameters deters to achieve high zT.T hus, decoupling the electronic and thermal transport with maximization of power factor (S 2 s)a nd minimization of thermal conductivity are desirable to develop efficient TE material.…”

Modulation of the electronic structure and thermoelectric properties of orthorhombic and cubic SnSe by AgBiSe2 alloying

“…In a typical degenerate semiconductor, all the above mentioned parameters except κ lat are intertwined with each other in a trade-off fashion. 1 Reduction in the κ lat can be acquired by introducing crystal defects, alloying and nanostructuring, [4][5][6][7][8][9] or by intrinsic phenomena. 10,11 Amplification of the power factor (S 2 σ) is generally achieved by the improvement of the Seebeck coefficient through band convergence 12,13 and resonance level formation.…”