Silica colloidal crystals with uni- and multi-photonic bandgaps and controlled reflective properties

High quality silica colloidal crystals with one or multi-photonic bandgaps that can be controlled in the whole range of the visible and near infrared lights have been designed. A comprehensive set of parameters that can predetermine the particle sizes from 150 to 750 nm of the resulting silica colloids and their polydispersities was established. Self-assembly of such silica spheres produced highly organized colloidal crystals, leading to the photonic crystals of which the reflectance wavelengths can cover the whole range of visible lights and parts of the ultraviolet and infrared lights. Multiple deposition of silica spheres of two or more different sizes produced a heterostructured with multiple photonic bandgaps.