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Increasing fluorescent concentrator light collection efficiency by restricting the angular emission characteristic of the incorporated luminescent material - the "Nano-Fluko" concept

 
: Goldschmidt, J.C.; Peters, M.; Gutmann, J.; Steidl, L.; Zentel, R.; Bläsi, B.; Hermle, M.

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Fulltext urn:nbn:de:0011-n-1563769 (5.5 MByte PDF)
MD5 Fingerprint: 6bb812a76b0b0479a042f3b2e4012e7f
Created on: 4.8.2012


Wehrspohn, R.B. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Photonics for Solar Energy Systems III : 13.-15.4.2010, Brussels, Belgium
Bellingham, WA: SPIE, 2010 (Proceedings of SPIE 7725)
ISBN: 978-0-8194-8198-6
Paper 77250S
Conference "Photonics for Solar Energy Systems" <3, 2010, Brussels>
English
Conference Paper, Electronic Publication
Fraunhofer ISE ()
Fluoreszenzkonzentratoren; Solarzellen - Entwicklung und Charakterisierung; Silicium-Photovoltaik; Farbstoff-; Organische und Neuartige Solarzellen; Alternative Photovoltaik-Technologien; Photonenmanagement; Konzentratorsysteme; Neuartige Konzepte

Abstract
Fluorescent concentrators concentrate both diffuse and direct radiation without requiring tracking of the sun. In fluorescent concentrators, luminescent materials embedded in a transparent matrix absorb sunlight and emit radiation with a different wavelength. Total internal reflection traps the emitted light and guides it to solar cells attached to the concentrator's edges. The escape cone of total internal reflection, however, limits the light collection efficiency. Spectrally selective photonic structures, which transmit light in the absorption range of the luminescent material and reflect the emitted light, reduce these losses. In this paper, we review different realizations of such structures and show that they increase collection efficiency by 20%. However, light emitted into steep angles in respect to the front surface, which would be lost without the photonic structures, has a very long effective path inside the concentrator until it reaches a solar cell. Therefore it suffers from path length dependent losses. We discuss how emission into the unfavorable directions can be suppressed by integrating the luminescent material into photonic structures, thus reducing these losses. We present possible realizations both for the concentrator design and for the solar cells used in such systems.

: http://publica.fraunhofer.de/documents/N-156376.html