Optimization of heat sink-limited thermoelectric generators

Many recent advances in thermoelectrics have focused on the nanoscale engineering of materials for higher figure of merit (Z). A thermoelectric generator using these thin-film materials can present new challenges due to its inherently large temperature gradient, but also correspondingly larger generated power if the heat can he managed. In such cases performance is expected to be limited as much by the heat sink as by intrinsic material properties. New criteria for optimizing the generated power density of devices in this regime are discussed here The effects of future material improvements on performance are studied, with the surprising result that optimizing material Z is not the best strategy for optimizing efficiency or power in this regime. The theory is tested with a numerical solution of the Onsager relations.