Thermoelectric modules can convert waste heat directly into useful electricity, providing a clean and sustainable way to use fossil energy more efficiently. Mg3Sb2-based alloys have recently attracted considerable interest from the thermoelectric community due to their nontoxic nature, abundance of constituent elements, and excellent mechanical and thermoelectric properties. However, robust modules based on Mg3Sb2 have progressed less rapidly. Here, we develop multiple-pair thermoelectric modules consisting of both n-type and p-type Mg3Sb2-based alloys. Thermoelectric legs based on the same parent fit in each other in terms of thermomechanical properties, facilitating module fabrication and ensuring low thermal stress. By adopting a suitable diffusion barrier layer and developing a new joining technique, an integrated all Mg3Sb2-based module demonstrates a high efficiency of 7.5% at a temperature difference of 380 K, exceeding the state-of-the-art same-parent thermoelectric modules. Moreover, the efficiency remains stable during 150 thermal cycling shocks (∼225 h), demonstrating excellent module reliability.

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 Bi0.42Sb1.58Te3 hot‐pressed sample by incorporating Ag5SbSe4. 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 Bi0.42Sb1.58Te3 + 0.10 wt% Ag5SbSe4 and zone‐melted n‐type Bi2Te2.7Se0.3, 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.

The resonant levels can be introduced into GeTe by In element, however, the effect of its microstructure on thermoelectric properties still remained unclear. In this study, a series of Ge 1-x In x Te samples were prepared by smelting-quenching-annealing combined with spark plasma sintering (SPS). The XRD, SEM, laser thermal conductivity instrument and thermoelectric performance analysis system (ZEM-3) were applied to study the microstructure and thermoelectric properties. Results show that, with the incorporation of In content, the unit cell volume decreases, and Herringbone structure has become smaller and grain boundaries increase, which result in a decrease in the lattice thermal conductivity. Thereby, a minimum thermal conductivity of 2.16 W•m-1 •K-1 is obtained. Meanwhile, In doping introduces the resonant levels and decreases the carrier concentration, so the Seebeck coefficient and the power factor increase. Consequently, the maximum ZT value of 1.15 is obtained in the 0.03 sample at 600 K, which is 26.4% higher than that of GeTe. This indicates that the thermoelectric properties of Ge 1-x In x Te can be effectively improved by the microstructure regulation.