Optimization of Thermoelectric Property of n‐Type Mg3Sb2 Near Room Temperature via Mn&Se Co‐Doping

Abstract

AbstractThe Bi2Te3 family has been considered a state‐of‐the‐art thermoelectric material for room‐temperature applications for over half a century. However, scarcity of the material Te has been a persistent issue. Recently, the discovery of n‐type Mg3(Bi, Sb)2‐based materials provides new hope for replacing traditional Bi2Te3, but their thermoelectric properties near room temperature still need improvement for application to practical devices. Herein, a competitive figure of merit of ≈0.8 at 300 K and a high power factor greater than 30 µW cm−1 K−2 at 300 K in n‐type Mg3.14Mn0.06Bi1.4Sb0.59Se0.01 is reported, benefiting from the rationally tuned carrier concentration of 2.29×1019 cm−3 at room temperature. Substituting the Mg site with Mn in Mg3.2Bi1.4Sb0.59Se0.01 changes the dominant carrier scattering mechanism from a mixed scattering of acoustic phonons and ionized impurities to acoustic phonon scattering. Mn doping in Mg3.2Bi1.4Sb0.59Se0.01 also enhances the mobility to 180 cm2 V−1 s−1, reduces the thermal conductivity, and significantly increases the quality factor β of the material. The high room temperature thermoelectric performance of n‐type Mn&Se co‐doped Mg3(Bi, Sb)2‐based materials makes them a highly competitive substitute for commercialized n‐type Bi2Te3.