Modulating Solid-Solution Solubility to Enhance Thermoelectric Performance and Maintain Structural Stability in Phase-Transition Silver Chalcogenides

Silver chalcogenides exhibit exceptional transport properties but face structural instability at high temperatures, limiting their practical applications. Using Ag₂Te as a model, it is confirm that silver whisker growth above the phase transition renders Ag₂Te unsuitable for thermoelectric applications. Here, the whisker growth mechanism is investigated and propose an inhibition strategy, overcoming a major obstacle in using silver chalcogenides. The presence of highly mobile Ag and lattice strain cause by phase transition are two factors leading to the formation of silver whiskers. Adding a trace amount of Ga inhibits silver whisker growth by forming an immobile Ag-Ga solid-solution phase and optimizing thermoelectric performance simultaneously. Consequently, a single leg of Ga-Ag₂Te achieves a conversion efficiency of 2.3% with a ΔT of 300 K and remains whisker-free after high-temperature testing. A thermally robust, high-performance thermoelectric single leg based on liquid-like silver chalcogenides is successfully developed.