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

Abstract

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 Mg3Sb2-based materials, can greatly impact the transport properties of this compound. Here we demonstrate that the Mg vacancies in the n-type Mg3Sb2-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 cm2 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 Mg3Sb2-based materials.