Shear-Aligned Assembly of Photonic Band Gap Coatings

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National Science Foundation - Division of Chemical &Transport Systems Particulate & Multiphase Processes Program (1415)Proposal Number: 0651780 Principal Investigators: Jiang, Peng Affiliation: University of Florida Proposal Title: Shear-Aligned Assembly of Photonic Band Gap Coating Intellectual MeritThis proposal aims to develop understanding and control of a robust spin-coating technology that enables large-scale production and integration of photonic crystals and a diverse range of nanostructured materials. Although simpler and less expensive than nanolithography for creating photonic crystals, the colloidal self-assembly approach suffers from low throughput and limited crystal structures. By contrast, the spin-coating method developed by the PI combines the simplicity and cost benefits of traditional self-assembly with the scalability and compatibility of nanolithography, allowing for the creation of wafer-scale colloidal crystals with non-close-packed structures.The mechanism by which the colloidal single crystals, with remarkably large domain sizes and unusual non-close-packed structures, form is not understood. Consequently, the research team will perform an experimental and theoretical investigation of the shear-aligned crystallization process. The team will employ light diffraction, laser scanning confocal microscopy, optical spectroscopy, and rheology to elucidate the microstructures and disorder-order transition during spin-coating. The team will use Stokesian dynamics simulations to model the applied hydrodynamic, colloidal, and Brownian forces; the microstructures and rheological properties of colloidal dispersions subjected to uniform and non-uniform shear flow, as appropriate for the spin-coating process, will be calculated. The photonic band gaps of the photonic crystals will be compared with theoretical calculations using scalar wave approximation and the MIT Photonic-Bands package.Broader ImpactThe proposed research program will lead to significant breakthroughs in fabricating and integrating photonic-crystal-based nanooptical devices for all-optical integrated circuits and quantum information processing, as well as important technological applications in subwavelength optics, plasmonic sensors, efficient OLEDs and photovoltaics, high-density magnetic recording media, and bio-microanalysis. Improved understanding of the fundamental aspects of flow-induced crystallization, melting, and relaxation within non-uniform shear flows, a topic that has received little or no examination, will also result.The educational program will impact students at all education levels. Outreach efforts through a local museum will bring modern technology to young students and adults through a fun learning experience and participation of high school students in the research program will benefit the students and their larger communities. Finally, collaborative efforts with high school teachers to develop classroom materials will favorably impact numerous students at the secondary level.