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Proceedings Paper

Efficient electroluminescent cooling with a light-emitting diode coupled to a photovoltaic cell (Conference Presentation)

Paper Abstract

The new breakthrough in photovoltaics, exemplified by the slogan “A great solar cell has to be a great light-emitting diode (LED)”, has led to all the major new solar cell records, while also leading to extraordinary LED efficiency. As an LED becomes very efficient in converting its electrical input into light, the device cools as it operates because the photons carry away entropy as well as energy. If these photons are absorbed in a photovoltaic (PV) cell, the generated electricity can be used to provide part of the electrical input that drives the LED. Indeed, the LED/PV cell combination forms a new type of heat engine with light as the working fluid. The electroluminescent refrigerator requires only a small amount of external electricity to provide cooling, leading to a high coefficient of performance. We present the theoretical performance of such a refrigerator, in which the cool side (LED) is radiatively coupled to the hot side (PV) across a vacuum gap. The coefficient of performance is maximized by using a highly luminescent material, such as GaAs, together with device structures that optimize extraction of the luminescence. We consider both a macroscopic vacuum gap and a sub-wavelength gap; the latter allows for evanescent coupling of photons between the devices, potentially providing a further enhancement to the efficiency of light extraction. Using device assumptions based on the current record-efficiency solar cells, we show that electroluminescent cooling can, in certain regimes of cooling power, achieve a higher coefficient of performance than thermoelectric cooling.

Paper Details

Date Published: 20 April 2017
PDF: 1 pages
Proc. SPIE 10121, Optical and Electronic Cooling of Solids II, 1012107 (20 April 2017); doi: 10.1117/12.2252631
Show Author Affiliations
Tianyao P. Xiao, Univ. of California, Berkeley (United States)
Kaifeng Chen, Stanford Univ. (United States)
Parthiban Santhanam, Stanford Univ. (United States)
Shanhui Fan, Stanford Univ. (United States)
Eli Yablonovitch, Univ. of California, Berkeley (United States)

Published in SPIE Proceedings Vol. 10121:
Optical and Electronic Cooling of Solids II
Richard I. Epstein; Denis V. Seletskiy; Mansoor Sheik-Bahae, Editor(s)

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