High thermoelectric performance at room temperature of n-type Mg3Bi2-based materials by Se doping

Bi2Te3 based alloys have been the most widely used thermoelectric material at low temperature for many decades. Here we report Se doped n-type Mg3Bi2 based materials with a thermoelectric figure-of-merit ZT of 0.82 at 300 K and a peak ZT of 1.24 at 498 K, which is comparable to the n-type Bi2Te3 and Te doped Mg3Bi1.4Sb0.6. The improved thermoelectric performance is benefited from the high carrier concentration and mobility as well as the thermal conductivity reduction. The reduced resistivity increased the power factor at all measured temperatures, leading to a higher engineering ZT (ZTeng) and engineering power factor (PFeng) for n-type Mg3Bi2. The n-type Mg3Bi1.4Sb0.6 materials are promising for thermoelectric power generation and cooling applications near room temperature.