Publica
Hier finden Sie wissenschaftliche Publikationen aus den FraunhoferInstituten. Increasing upconversion by metal and dielectric nanostructures
:
Goldschmidt, J.C.; Fischer, S.; Steinkemper, H.; Herter, B.; Rist, T.; Wolf, S.; Bläsi, B.; Hallermann, F.; Plessen, G. von; Krämer, K.W.; Biner, D.; Hermle, M.  Freundlich, A. ; Society of PhotoOptical Instrumentation Engineers SPIE, Bellingham/Wash.: Physics, simulation, and photonic engineering of photovoltaic devices : 23  26 January 2012, San Francisco, California Bellingham, WA: SPIE, 2012 (Proceedings of SPIE 8256) ISBN: 9780819488992 Paper 825602 
 Conference "Physics, Simulation, and Photonic Engineering of Photovoltaic Devices" <2012, San Francisco/Calif.> 

 Englisch 
 Konferenzbeitrag 
 Fraunhofer ISE () 
Abstract
Upconversion (UC) of subbandgap photons can increase solar cell efficiencies. Up to now, the achieved efficiencies are too low, to make UC relevant for photovoltaics. Therefore, additional means of increasing UC efficiency are necessary. In this paper, we investigate both metal and dielectric photonic nanostructures for this purpose. The theoretical analysis is based on a rate equation model that describes the UC dynamics in NaYF 4 : 20% Er 3+. The model considers ground state and excited state absorption, spontaneous and stimulated emission, energy transfer, and multi phonon relaxation. For one, this model is coupled with results of Mie theory and exact electrodynamic theory calculations of plasmon resonance in gold nanoparticles. The effects of a 200 nm gold nanoparticle on the local field density and on the transition rates within in the upconverter are considered. Calculations are performed in high resolution for a three dimensional simulation volume. Furthermore, the effect of changed local fields in the proximity of grating waveguide dielectric nanostructure is investigated. For this purpose FDTD simulation models of such structures are coupled with the rate equation model of the upconverter. The results suggest that both metal nanoparticles and dielectric nanostructures can increase UC efficiency.