Advances in Mg₃Sb₂ thermoelectric materials and devices

Thermoelectric technology offers a green-viable and carbon-neutral solution for energy problems by directly converting waste heat to electricity. For years, Bi₂Te₃-based compounds have been the main choice materials for commercial thermoelectric devices. However, Bi₂Te₃ comprises scarce and toxic tellurium (Te) elements, which might limit its large-scale application. Recently, Mg₃Sb₂ compounds have drawn increasing attention as an alternative to Bi₂Te₃ thermoelectrics due to their excellent thermoelectric performance. Enabled by effective strategies such as optimizing carrier concentration, introducing point defects, and manipulating carrier scattering mechanisms, Mg₃Sb₂ compounds have realized an improved thermoelectric performance. In this review, optimizing strategies for both Mg₃Sb₂-based thermoelectric materials and devices are discussed. Moreover, the flexibility and plasticity of Bi-alloyed Mg₃Sb₂ mainly stemming from the dense dislocations are outlined. The above strategies summarized here for enhancing Mg₃Sb₂ thermoelectrics are believed to be applicable to many other thermoelectrics.