Photonic crystals for energy transfer experiments

Incorporation of two dyes into polystyrene beads was achieved through a core-shell emulsion free polymerization. The beads consisted of a central core, a dye containing emissive layer, and an overcoat layer. The overcoat layer thickness determined the final size of the nanospheres. The nanospheres were monodisperse and spherical. The nanospheres were used to assemble two photonic crystals. One in which the stop band overlapped with the dye emission of the donor dye, and one which had no overlap. The crystals formed were characterized by photoluminescence and reflectance studies. The crystal's emission was suppressed where the stop band overlapped the emission. This suppression shows the expected angular dependence and contributes to changes in the efficiency of energy transfer from Coumarin 334 to Nile Red. Suppression of emission and energy transfer impart an angular dependence of the color of emission to the crystal. This results in a material that is tunable with angle of both its reflectivity and its emission.