High thermoelectric cooling performance of n-type Mg ₃ Bi ₂ -based materials

Thermoelectric materials have a large Peltier effect, making them attractive for solid-state cooling applications. Bismuth telluride (Bi₂Te₃)-based alloys have remained the state-of-the-art room-temperature materials for many decades. However, cost partially limited wider use of thermoelectric cooling devices because of the large amounts of expensive tellurium required. We report n-type magnesium bismuthide (Mg₃Bi₂)-based materials with a peak figure of merit (ZT) of ~0.9 at 350 kelvin, which is comparable to the commercial bismuth telluride selenide (Bi₂Te₃₋ x Se x ) but much cheaper. A cooling device made of our material and p-type bismuth antimony telluride (Bi0.5Sb1.5Te₃) has produced a large temperature difference of ~91 kelvin at the hot-side temperature of 350 kelvin. n-type Mg₃Bi₂-based materials are promising for thermoelectric cooling applications.