Synergistic Optimization of Thermoelectric Performance in AgSbTe ₂ via Ag Vacancy and In Doping

P-type semiconductor AgSbTe2 exhibits outstanding thermoelectric performance in the midtemperature region, indicating significant potential for thermoelectric conversion. This study employed a synergistic optimization strategy by introducing Ag vacancy and In doping to enhance the thermoelectric performance of AgSbTe2. The results show that Ag vacancies suppress the formation of Ag2Te and increase the hole concentration. In doping promotes band convergence and induces flattening near the valence band maximum. These changes synergistically enhance the density-of-states effective mass and effective orbital degeneracy, thereby enhancing the Seebeck coefficient and optimizing the power factor. Moreover, defects induced by In doping, such as point defects, grain boundaries, dislocations, and lattice distortions, significantly enhance multiscale phonon scattering, resulting in a pronounced decrease in lattice thermal conductivity to 0.38 W m–1 K–1. A peak zT of 1.12 was achieved at 573 K in the Ag0.97Sb0.96In0.04Te2 sample.