High Thermoelectric Performance in Phonon‐Glass Electron‐Crystal Like AgSbTe₂

Abstract Achieving glass‐like ultra‐low thermal conductivity in crystalline solids with high electrical conductivity, a crucial requirement for high‐performance thermoelectrics , continues to be a formidable challenge. A careful balance between electrical and thermal transport is essential for optimizing the thermoelectric performance. Despite this inherent trade‐off, the experimental realization of an ideal thermoelectric material with a phonon‐glass electron‐crystal (PGEC) nature has rarely been achieved. Here, PGEC‐like AgSbTe₂ is demonstrated by tuning the atomic disorder upon Yb doping, which results in an outstanding thermoelectric performance with figure of merit, zT ≈ 2.4 at 573 K. Yb‐doping‐induced enhanced atomic ordering decreases the overlap between the hole and phonon mean free paths and consequently leads to a PGEC‐like transport behavior in AgSbTe₂. A twofold increase in electrical mobility is observed while keeping the position of the Fermi level (E_F) nearly unchanged and corroborates the enhanced crystalline nature of the AgSbTe₂ lattice upon Yb doping for electrical transport. The cation‐ordered domains, lead to the formation of nanoscale superstructures (≈2 to 4 nm) that strongly scatter heat‐carrying phonons, resulting in a temperature‐independent glass‐like thermal conductivity. The strategy paves the way for realizing high thermoelectric performance in various disordered crystals by making them amorphous to phonons while favoring crystal‐like electrical transport.