Ag doping enables high thermoelectric performance of cubic p-type (SnSe)_0.55(PbTe)_0.45 polycrystals

Thermoelectric materials possess the capability to directly convert thermal energy into electrical energy, demonstrating huge potential for waste heat recovery and power generation. Cubic SnSe is impressive due to its excellent mechanical properties and high carrier mobility in the SnSe-based thermoelectric field. In this study, Ag acceptor doping was introduced into PbTe-alloyed cubic SnSe polycrystals to decouple the phonon-electron transport. We found that the thermoelectric transport exhibits different optimization mechanisms with temperature changes. The enhanced carrier concentration and the enlarged effective mass contribute to the improvement of the electrical transport properties near room temperature. The boosted carrier mobility (665.3 cm² V^-1 s^-1 at 673 K) and the suppressed bipolar diffusion dominate the increase of ZT at medium and high temperatures. The ZT value of the best-optimized (SnSe)_0.55(PbTe)_0.45-0.03Ag at 823 K increased to ∼0.8, and the fabricated single-leg device attained a power generation efficiency of ∼2% at a temperature difference of approximately 525 K. This strategy offers a valuable reference for the application of cubic phase SnSe-based materials in thermoelectric power generation.