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

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.