Photonic Crystals from Coated Colloids

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Three-dimensional photonic crystals (both colloidal crystals and inverse opals) are to be prepared from novel coated colloid (i.e. core-shell) building blocks that afford precise tunability of the optical characteristics of the crystals. The coreshell colloids will be constructed by the layer-by-layer adsorption of various polyelectrolytes as well as preformed inorganic nanoparticles. This strategy will allow independent control over shell thickness and composition. Serval methods will be examined to construct highly ordered three-dimensional photonic crystals, including sedimentation, centrifugation, and electrophoretic deposition. Subsequent removal of the core from the coated colloids yields hollow particles; photonic crystals of these particles will also be constructed in a similar fashion. The advantage of these particles is that they provide an increased refractive index contrast, a parameter essential for a complete stopband. Creating three-dimensional assemblies of these novel and well-defined colloidal entities will yield photonic crystals with unique and tailored photonic properties.