A numerical study on the design trade-offs of a thin-film thermoelectric generator for large-area applications

Abstract

Thin-film thermoelectric generators with a novel folding scheme are proposed for large-area, low energy-density applications. Both the electrical current and heat transfer are in the plane of the thermoelectric thin-film, yet the heat transfer is across the plane of the module - similar to conventional bulk thermoelectric modules. With such designs, the heat leakage through the module itself can be minimized and the available temperature gradient maximized. Different from the previously reported corrugated thermoelectric generators, the proposed folding scheme enables high packing densities without compromising the thermal contact area to the heat source and sink. The significance of various thermal transport, or leakage, mechanisms in relation to power production is demonstrated for different packing densities and thicknesses of the module under heat sink-limited conditions. It is shown that the power factor is more important than ZT for predicting the power output of such thin-film devices. As very thin thermoelectric films are employed with modest temperature gradients, high aspect-ratio elements are needed to meet the - usually ignored - requirements of practical applications for the current. With the design trade-offs considered, the proposed devices may enable the exploitation of thermoelectric energy harvesting in new - large-area - applications at reasonable cost.