Traditional thermoelectric devices employ a bulk semiconductor, formed between two metallic plates through which both electrical charge flow and heat flow enter from the bulk semiconductor. The two metallic plates are geometrically in parallel or nearly in parallel. Each metallic plate concurrently maintains either a high or low temperature. Electrons accumulate on the cold side as they diffuse from the hot side to the cold side; generating an electrical voltage which appears on an external circuit between the two metallic plates for a given temperature gradient.   The electric field counteracts the motion of the diffusing electrons, causing electrons to drift in the direction opposite to the motion of the diffusion. Therefore, at the steady-state (i.e., the diffusion and the drift are in balance), the open-circuit voltage and the heat-generated current are limited by the electric field that causes electrons in a bulk semiconductor to drift in the direction opposite to the motion of the diffusion. In the invention by UCSC researchers, semiconductor nanowires are used instead of bulk semiconductor. Important feature of UCSC nanowire thermoelectric devices is that the long-axis of the nanowires are not perpendicular to the two metallic plates, which result in sizable reduction in the electric field that counteracts the motion of the diffusing electrons, significantly increasing the open-circuit voltage and heat-generated current.

File Number: 22162 

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