High‐Efficiency Thermoelectric Module Based on High‐Performance Bi 0.42 Sb 1.58 Te 3 Materials

Abstract Bismuth‐telluride‐based alloy is the sole thermoelectric candidate for commercial thermoelectric application in low‐grade waste heat harvest near room temperature, but the sharp drop of thermoelectric properties at higher temperature and weak mechanical strength in zone‐melted material are the main obstacles to its wide development for power generation. Herein, an effective approach is reported to improve the thermoelectric performance of p ‐type Bi 0.42 Sb 1.58 Te 3 hot‐pressed sample by incorporating Ag 5 SbSe 4 . A peak ZT of 1.40 at 375 K and a high average ZT of 1.25 between 300 and 500 K are achieved. Such outstanding thermoelectric performance originates from the synergistic effects of improved density‐of‐states effective mass, reduced bipolar thermal conductivity by the boosted carrier concentration, and suppressed lattice thermal conductivity by the induced phonon scattering centers including substitute point defects, dislocations, stress–strain clusters, and grain boundaries. Comprised of the p ‐type Bi 0.42 Sb 1.58 Te 3 + 0.10 wt% Ag 5 SbSe 4 and zone‐melted n ‐type Bi 2 Te 2.7 Se 0.3 , the thermoelectric module exhibits a high conversion efficiency of 6.5% at a temperature gradient of 200 K, indicating promising applications for low‐grade heat harvest near room temperature.