Defect Engineering for Realizing High Thermoelectric Performance in n-Type Mg₃Sb₂-Based Materials

Point defects, which scatter electronic carriers as well as phonons, play a vital role in the transport properties of thermoelectric materials. Therefore, defect engineering can be utilized for tuning thermoelectric properties. Mg vacancies, as the dominant defects in the n-type Mg 3 Sb 2 -based materials, can greatly impact the transport properties of this compound. Here we demonstrate that the Mg vacancies in the n-type Mg 3 Sb 2 -based materials can be successfully manipulated by simply tuning the preparation conditions. A substantial enhancement in the Hall mobility is obtained, from ∼39 to ∼128 cm 2 V –1 s –2, an increase of ∼228%. The significantly improved Hall mobility noticeably boosts the power factor from ∼6 to ∼20 μW cm –1 K –2 and effectively enhances the thermoelectric figure of merit. Our results demonstrate that defect engineering could be very effective in improving the thermoelectric performance of n-type Mg 3 Sb 2 -based materials.