Efficient light trapping in a fluorescence solar collector by 3D photonic crystal

The escape of photons from a fluorescence collector is substantially reduced by the addition of a 3D photonic crystal which is geometrically designed for the emission wavelengths of the collector. We analyze angle dependent spectral transmission and reflection of the opal and prove the blocking effect by recording the angle dependence of the spectral fluorescence from the collector with and without the opal. By comparison of both photon fluxes a reduction of the emission in the appropriate ranges of wavelength and angle by a factor >10 is observed. For photovoltaic applications an increase in the internal photon density of the collector and likewise in the fluorescence photon flux fed to a solar cell can be expected, which might be overcompensated by the non-negligible reflection of the opal. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim