Electronic fitness function for screening semiconductors as thermoelectric materials*

Thermoelectric performance is a contraindicated property of matter that requires combinations of transport properties that do not occur in ordinary materials. Finding new high performance thermoelectrics requires methods for efficiently screening compounds to detect the unusual electronic structures that can decouple transport quantities, especially for power factor, the Seebeck coefficient and the conductivity. Here we present and test a simple transport function that can be efficiently calculated using standard methods and which identifies materials that decouple these transport quantities. It is large for band structures that overcome the inverse relationship between σ and S regardless of the specific characteristic that does this, i.e. complex band shapes, multiple valleys, heavy-light band mixtures, band convergence, valley anisotropy, and other features. Thus this transport function provides a simple and easily used way to screen materials for potential TE performance