1LA-4: Entirely crystallized photonic balls and their structural coloration

Colloidal photonic crystals are one of the representative structural colored materials. A structural color of colloidal crystals can be tuned simply by adjusting the size of colloidal particle. Specifically, colloidal crystals with a spherical geometry (i.e., spherical colloidal crystal particles) are promising for their application as coloration particles for displays or pigments. The spherical colloidal crystals particles have been obtained by evaporation of colloidal droplets in the form of emulsion or aerosol. Most of spherical colloidal crystal particles reported previously exhibited an ordered, layered crystalline structures only near the surface due to the spherical confinement geometry. Here, we report a fully crystallized structure by reducing the evaporation time much longer than the diffusional equilibration time. The crystalline structure gives strong coherent reflection due to their long range crystalline structure.