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Investigation on the Intensity Dependence of Upconversion Systems

: Steinkemper, H.; Fischer, S.; Krämer, K.W.; Biner, D.; Hermle, M.; Goldschmidt, J.C.

Volltext urn:nbn:de:0011-n-2210647 (213 KByte PDF)
MD5 Fingerprint: bac1bd43cd55735aa3d4371cd9de3930
Erstellt am: 7.12.2012

European Commission:
26th European Photovoltaic Solar Energy Conference and Exhibition, EU PVSEC. Proceedings : 5th to 9th September 2011 at the CCH - Congress Centre and International Fair Hamburg in Germany
München: WIP-Renewable Energies, 2011
ISBN: 3-936338-27-2
European Photovoltaic Solar Energy Conference and Exhibition (EU PVSEC) <26, 2011, Hamburg>
Konferenzbeitrag, Elektronische Publikation
Fraunhofer ISE ()
Solarzellen - Entwicklung und Charakterisierung; Silicium-Photovoltaik; Farbstoff; Organische und Neuartige Solarzellen; Alternative Photovoltaik-Technologien; Photonenmanagement; Neuartige Konzepte

Silicon solar cells lose about 20% of the energy of the solar spectrum due to sub-band-gap losses. Upconversion (UC) materials, which generate one high-energy photon out of two or more low-energy photons, can be used to minimize these losses and to significantly enhance the solar cell efficiency. Since UC is a non-linear process, the quantum yield of an upconverter increases with increasing irradiance. In this paper, we investigate the intensity dependence of the upconverter ß-NaY0.8Er0.2F4 under broad-band excitation. An UC quantum yield of UC,lamp = 2.5% was achieved for broad-band excitation with a photon flux of 56·1020 s-1m-2 for the considered excitation spectrum which corresponds to an irradiance of 730 Wm-2 under monochromatic illumination at 1523 nm. The results are compared to monochromatic laser illumination and simulations with a rate equation model. The observed intensity dependences for broad-band and monochromatic excitation show the same curve shape and the values are approximately equivalent. These results suggest that UC is efficient under broad-band excitation as well.