Synergistic Regulation of Thermopower and Reduced Thermal Conductivity Achieving Higher Thermoelectric Properties in p-Type AgSbTe₂ via Selenium Alloying

P-type AgSbTe2 demonstrates significant potential for thermoelectric (TE) applications, particularly in the temperature range of 300–600 K, owing to its low thermal conductivity. In this study, we report a remarkable enhancement in the thermoelectric properties of Se-alloyed AgSbTe2, achieving a maximum figure of merit (ZT) value of 1.6 at 530 K and an average ZT value of 1.1 across the temperature range of 300–550 K. These values represent substantial increases of approximately 94% and 72%, respectively, compared to the unalloyed AgSbTe2. This enhancement is attributed to the synergistic optimization of both electrical and thermal transport properties. The thermal conductivity of AgSbTe2–xSex samples is significantly reduced relative to that of pristine AgSbTe2, primarily due to the introduction of solid solution point defects that enhance phonon scattering. Furthermore, the alloying of Se at Te sites in AgSbTe2 leads to an increase in state density effective mass, causing an enhancement in Seebeck coefficient and power factor. These findings underscore that Se alloying is a highly effective strategy for improving the thermoelectric performance of p-type AgSbTe2.