Fabrication technique for filling-factor tunable titanium dioxide colloidal crystal replicas

Abstract

Filling-factor tunable titanium dioxide replicas of colloidal crystals were fabricated by using a liquid phase deposition (LPD) technique. Ammonium hexafluorotitanate [(NH4)2TiF6] was used as a precursor, which was converted slowly to titanium dioxide by hydrolysis with boric acid. After the oxide was formed in voids of latex colloidal crystals, the latex was removed by calcination. By applying the LPD process to the replica again, the filling factor of the replica could be increased in a controllable fashion. With 203 nm template spheres, the peak shift in the ∼490 nm stop band depended linearly on the deposition time for the first 20 min, at a rate of 4.4 nm/min. Thus the position of the Bragg reflection peak could be adjusted precisely by controlling the filling factor of the replica structure.

Full spectrum enhancement of the light harvesting efficiency of dye sensitized solar cells by including colloidal photonic crystal multilayers

“…The ͑111͒ planes of the crystals are parallel to the solar cell conducting substrate and therefore perpendicular to the incident light in our study. In all cases the refractive index of these nanocrystalline titania spherical shells is n shell = 2.39, a value that takes into account both the fact that titania synthesized in an opal from a liquid precursor is typically porous, as it has been experimentally reported, 13 and that it must be infiltrated by the redox electrolyte. The number of close packed sphere monolayers composing the PhCs is arbitrarily fixed at 17 ML ͑ML denotes monolayer͒, which is the thickness of the colloidal lattice grown in Ref.…”

Review of roles for photonic crystals in solar fuels photocatalysis

“…15 The exact frequency of the photonic bandgap is highly sensitive to the refractive indices of the solid and voids and will redshift as the refractive index of the pore-filling fluid increases (Fig. 3).…”

“…These structures are typically prepared by templating monodisperse polystyrene spheres in an opal arrangement and infiltrating the voids of the face-centered cubic (fcc) array with oxide precursors before removing the template by calcination 12,[14][15][16][17][18] (Fig. 2).…”

Preparation of Hollow Titanium Dioxide Shell Thin Films from Aqueous Solution of Ti-Lactate Complex for Dye-Sensitized Solar Cells

“…The process seems to be simple and time-saving compared with other conventional methods: PS template followed by infiltration of Ti oxides or Ti compounds sol. (Galusha et al, 2008;King et al, 2005;Liu et al, 2010;Nishimura et al, 2002) The immersion of substrate in the initial suspension which contains both PS and TALH, followed by evaporation of water, forms a PS template coated with TALH (PS-TALH) precursor ( Fig. 2 (a)).…”