Thermoelectric Structures and Devices Based on Topological Insulators

摘要

Method and apparatus are provided for improving the thermoelectric figure of merit (zT) for thermoelectric structures and devices based on topological insulators. In one novel aspect, the zT of the TI is increased by optimizing geometric sizes of the TI. In one embodiment, the zT is increased by increasing the length of the TI to be greater than the inelastic mean free path length. In another embodiment, the zT is increased by decrease the width of a 2D TI to be about three times the localized localization width ξ of the boundary state of the TI, or to decrease the thickness of a 3D TI to be about three times of ξ. In one novel aspect of the current invention, methods are provided to increase zT of the TI by substantially maximizing a relative thermoelectric-transport contribution of the boundary state with respect to the bulk states.

主权项

1. A thermoelectric structure comprising:
a topological insulator (TI), wherein the TI has a bulk state with an insulating gap and a boundary state that is gapless and protected from any time reversal invariant perturbation; a cross sectional area A; and an electrical and thermal transport path along a longitudinal direction with a length of L, wherein an electrical conductance G of the TI does not satisfy Ohm's scaling law that G is proportional to A/L, and wherein a thermoelectric figure of merit (ZT) of the thermoelectric structure is increased by increasing L and decreasing A.