Phys. Rev. X 1, 021012 (2011)

Thermoelectric materials can transform waste heat into electricity. To maximize efficiency, the ratio between the thermopower — which is proportional to the electrical conductivity — and thermal conductivity has to be as high as possible. Granular materials have potentially good thermoelectric properties, particularly if they are selected so that their grain boundaries reduce the propagation of heat and do not affect the motion of charges — electrons or holes. Stefano Curtarolo and colleagues have now used high-throughput ab initio calculations to estimate the thermoelectric performance of more than 2,500 granular compounds obtained by powder sintering. The basic assumption for their calculations was that the electrons move ballistically within each grain. The calculated thermoelectric properties of all these materials — available with the paper — suggest that the most efficient are those with a wide bandgap, high effective electron mass and a high number of atoms per primitive cell. The results will provide useful guidelines for thermoelectric experimentalists that are otherwise mostly limited by a time- and effort-consuming trial-and-error procedure.