Controlled Emission through Fluorescent Polymer Nanopigments

Abstract

The use is explored of 100−200 nm sized polystyrene or poly(9,9-dihexyl-2,7-fluorenediyl) (PFH) nanoparticles (“nanopigments”) containing low-MW chromophores such as perylene, coumarin 6, and Nile red for use in multicolor emission applications. Good results were obtained with PS nanoparticles at low (≤0.5 wt %) chromophore doping levels with emissions being a linear combination of the two component nanoparticles. At higher chromophore concentrations the emissions do not conform to a simple “linear” combination of the component nanoparticles. This may be due to inadvertent dye exchange between nanoparticles during preparation and processing. The emission properties of nanoparticles having blue, green, or red emitting polymer chromophores dispersed in polystyrene or PFH proved more successful in that interparticle dye exchange, and hence undesirable Förster energy transfer, is largely eliminated. Hence, the emissions of these nanopigments are independent and thus can be combined linearly to give a well-controlled emission output.