Screening for potential thermoelectric materials using an electronic fitness function*

High performance thermoelectric (TE) materials require materials with complex electronic structures which may come from complex iso-energy surfaces, multiple valleys, valley anisotropy, heavy-light band combination and band convergence. Here we present a simple transport function that can be directly evaluated based on the first-principles electronic structures and the Boltzmann transport theory and it is a universal function that incorporates all these features. We applied the transport function for the screening of 75 potential TE materials and we find an efficient screening with the transport function. The well-known binary TE materials (GeTe, PbTe) can be efficiently screened amomg all the candidates. Moreover, we also identified two alkali metal Zintl phases (Na₂AuBi, KSnSb), two half-Heuslers (RhNbSn,IrNbSn) and one full-Heusler, Li₂NaSb with favorable electronic properties.