High three-dimensional thermoelectric performance from low-dimensional bands.

Reduced dimensionality has long been regarded as an important strategy for increasing thermoelectric performance, for example, in superlattices and other engineered structures. Here we point out and illustrate by examples that three-dimensional bulk materials can be made to behave as if they were two dimensional from the point of view of thermoelectric performance. Implications for the discovery of new practical thermoelectrics are discussed.