Goniopolar materials for transverse thermoelectric device

Abstract

Thermoelectric generators are solid-state devices capable of directly converting heat to electricity. The performance of these modules is limited by the tendency of metal-semiconductor contacts at the hot-side to degrade due to chemical reactions and/or elemental diffusion. Transverse thermoelectric modules can be employed to address these issues, because the temperature gradient and electricity are orthogonal to one another. Consequently, the exposure of metal-semiconductor contacts to high-temperature environments can be avoided, thereby improving the long-term thermal stability of the device. One approach to the design of transverse thermoelectric devices is to use materials having goniopolarity, which simultaneously exhibit p-type and n-type conduction along different crystallographic directions. Here, we report goniopolarity of Mg₃Sb₂ and Mg₃Bi₂ due to their band anisotropy.