Maximizing the performance of n-type Mg 3 Bi 2 based materials for room-temperature power generation and thermoelectric cooling.

Although the thermoelectric effect was discovered around 200 years ago, the main application in practice is thermoelectric cooling using the traditional Bi 2 Te 3 . The related studies of new and efficient room-temperature thermoelectric materials and modules have, however, not come to fruition yet. In this work, the electronic properties of n-type Mg 3.2 Bi 1.5 Sb 0.5 material are maximized via delicate microstructural design with the aim of eliminating the thermal grain boundary resistance, eventually leading to a high zT above 1 over a broad temperature range from 323 K to 423 K. Importantly, we further demonstrated a great breakthrough in the non-Bi 2 Te 3 thermoelectric module, coupled with the high-performance p-type α-MgAgSb, for room-temperature power generation and thermoelectric cooling. A high conversion efficiency of ~2.8% at the temperature difference of 95 K and a maximum temperature difference of 56.5 K are experimentally achieved. If the interfacial contact resistance is further reduced, our non-Bi 2 Te 3 module may rival the long-standing champion commercial Bi 2 Te 3 system. Overall, this work represents a substantial step towards the real thermoelectric application using non-Bi 2 Te 3 materials and devices.