Structural and optical characterization of 3D binary colloidal crystal and inverse opal films prepared by direct co-deposition

Abstract

Colloidal particles of two sizes have been co-deposited from mixed suspensions by vertical transfer to prepare binary colloidal crystals (bCC) and inverse opals (IO) with long-range ordering, as deduced from structural characterization by SEM and Vis-NIR spectroscopy. As such, the described procedure allows hierarchical structure formation with colloidal particle mixtures by vertical lifting deposition in a single step. The particular features of the lattice geometries in these binary structures was theoretically analyzed. From the obtained silica IO templates, gold-silica hybrid IOs and gold opal replicas with hierarchical pore structures were fabricated. The gold-silica hybrid IOs showed in their Vis-NIR spectra a plasmonic response upon refractive index changes of the surrounding medium, which may be exploited for chemo- and biosensing applications.