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Proceedings Paper

Overview of optical rectennas for solar energy harvesting
Author(s): Zixu Zhu; Saumil Joshi; Bradley Pelz; Garret Moddel
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Paper Abstract

Although the concept of using optical rectenna for harvesting solar energy was first introduced four decades ago, only recently has it invited a surge of interest, with dozens of laboratories around the world working on various aspects of the technology. An optical rectenna couples an ultra-high-speed diode to a submicron antenna so that the incoming radiation received by the antenna is rectified by the diode to produce a DC power output. The result is a technology that can be efficient and inexpensive, requiring only low-cost materials. Conventional classical rectification theory does not apply at optical frequencies, necessitating the application of quantum photon-assisted tunneling theory to describe the device operation. At first glance it would appear that the ultimate conversion efficiency is limited only by the Landsberg limit of 93%, but a more sober analysis that includes limitation due to the coherence of solar radiation leads to a result that coincides with the Trivich-Flinn limit of 44%. Innovative antenna designs are required to achieve high efficiency at frequencies where resistive losses in metal are substantial. The diode most often considered for rectennas make use of electron tunneling through ultra-thin insulators in metal-insulator-metal (MIM) diodes. The most severe constraint is that the impedances of the antenna and diodes must match for efficient power transfer. The consequence is an RC time constant that cannot be achieved with parallel-plate MIM diodes, leading to the need for real innovations in diode structures. Technologies under consideration include sharp-tip and traveling-wave MIM diodes, and graphene geometric diodes. We survey the technologies under consideration.

Paper Details

Date Published: 25 September 2013
PDF: 11 pages
Proc. SPIE 8824, Next Generation (Nano) Photonic and Cell Technologies for Solar Energy Conversion IV, 88240O (25 September 2013); doi: 10.1117/12.2024700
Show Author Affiliations
Zixu Zhu, Univ. of Colorado (United States)
Saumil Joshi, Univ. of Colorado (United States)
Bradley Pelz, Univ. of Colorado (United States)
Garret Moddel, Univ. of Colorado (United States)


Published in SPIE Proceedings Vol. 8824:
Next Generation (Nano) Photonic and Cell Technologies for Solar Energy Conversion IV
Oleg V. Sulima; Gavin Conibeer, Editor(s)

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