International Research Fellowship Program: Self-Assembly of Coated Colloidal Particles for Optical Applications

University Of Rochester, Rochester NY

Investigators

Abstract

0107357 Yates The International Research Fellow Awards Program enables U.S. scientists and engineers to conduct three to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad. This award will support a six-month postdoctoral research fellowship by Dr. Matthew Z. Yates of the University of Rochester, to work with Dr. Frank Caruso at Max Planck Institute for Colloids and Interfaces in Potsdam, Germany. Photonic crystals are materials that are opaque to certain wavelengths of light while allowing the transmission of other wavelengths. The wavelength region where these materials are opaque is referred to as the photonic band gap. Photonic crystals offer promise for use in the next generation of communications and computing technology in which light is used instead of electrons for information transmission and processing. The unique optical properties of photonic crystals arise from the periodic variation in the refractive index of the material on a length scale near the wavelength of light. One promising route for the synthesis of photonic crystals is the ordered stacking of colloidal particles. When monodisperse sized colloidal particles are allowed to sediment slowly, they will form a hexagonally stacked structure referred to as a "colloidal crystal". It is the goal of this research project to form colloidal crystals from polymer particles coated with a thin layer of nanoparticles to modify optical properties of the colloidal crystal. Both high refractive index nanoparticles such as titanium dioxide or lead sulfide, and luminescent nanoparticles such as CdS and CdTe will be used to modify the optical properties of the photonic crystals. Caruso and coworkers have recently formed colloidal crystals of polystyrene coated with luminescent nanoparticles. The presence of the luminescent nanoparticles enhanced the photonic band gap of the polystyrene photonic crystal, as shown with UV-Vis spectroscopy. The optical properties of coated colloidal crystals remain to be investigated in detail. Key questions to answer are how the photonic band gap varies with the thickness of the coating layer, overall particle size, and optical properties of the nanoparticles in the coating layer.