INOR 393 |
| Highly uniform inorganic colloidal particles (e.g. titania) and their self-assembled arrays are of great technological interest in solar cells and photonic crystals. Existing strategies for preparing monodisperse colloids, and thus colloidal crystals, generally manipulate the chemistry of colloid formation by trial and error. Here we present a generalized templating approach to fabricate wafer-scale, two-dimensional, non-close-packed (ncp) colloidal crystals from inorganic sol-gel precursors. Polymer nanocomposites consisting of monolayer ncp colloidal crystals prepared by a spin-coating process are used as sacrificial templates. After removing colloidal silica templates, the voids in the polymer matrix are infiltrated with other materials, such as sol-gel titania, zirconia, and alumina. By plasma-etching the polymer matrix, wafer-scale ncp colloidal crystals can be made. The technique is scalable and compatible with standard microfabrication. Binary colloidal crystals with complex micropatterns can also be fabricated by the templating technique. Normal-incidence reflectivity spectra show well-defined peaks due to Bragg diffraction. The peak positions match with the theoretical prediction using Scalar Wave Approximation. |
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Synthesis and Characterization of Materials
1:30 PM-5:30 PM, Monday, August 20, 2007 BCEC -- 206 A/B, Oral
Division of Inorganic Chemistry |