Synergistic Effect of Mg–Se Co-Doping and Post-Annealing on the Thermoelectric Performance of Polycrystalline AgSbTe ₂

High Resolution Image Download MS PowerPoint Slide AgSbTe 2 is a promising mid-temperature thermoelectric material, but its practical efficiency is limited by phase instability, low carrier mobility, and the formation of Ag 2 Te and Sb 2 Te 3 secondary phases. Here, we employ a synergistic strategy that combines Mg–Se co-doping with post-annealing to overcome these limitations. Se incorporation increases carrier concentration by modifying the anion sublattice and suppressing antisite defects, while Mg stabilizes defects, reducing cation disorder and enhancing carrier mobility. Consequently, co-doping stabilizes the phase and improves electrical transport by optimizing the band structure and hole concentration. Furthermore, post-annealing enhances crystallinity, promotes atomic ordering, and improves carrier mobility by 62.7%. As a result, the optimized AgSb 0.95 Mg 0.05 Te 1.85 Se 0.15 sample achieves a high ZT of 2.15 at 560 K, and an average ZT of 1.55 (300–610 K), corresponding to an estimated thermoelectric efficiency of ∼13.9%. This combined doping and annealing approach provides an effective and scalable route to stabilize the AgSbTe 2 matrix, optimize carrier transport, and significantly enhance overall thermoelectric performance for medium-temperature waste heat energy conversion.