Controlled Pixelation of Inverse Opaline Structures Towards Reflection-Mode Displays

摘要

A photonic bandgap in a material arises from periodic modulations in the refractive index of the material over a length scale that is half the wavelength of the light. Photons having an energy within the bandgap range cannot pass through the photonic crystals and are reflected. Photonic crystals having a bandgap in the visible range exhibit sparking interference colors that are useful in colorimetric sensors, encoded microcarriers, and microdisplays. Significant efforts have been applied toward preparing photonic crystals by crystallizing monodisperse colloidal particles. Regular arrays of colloids arranged in a crystalline structure spatially modulate the refractive index and, therefore, display opalescent structural colors. One of most popular methods of preparing highly-ordered photonic colloidal crystals in a controllable manner involves convective assembly on a planar substrate. In this approach, a substrate is dipped in a colloidal suspension and slowly pulled out.