Optical properties of nanostructured thin films and applications

点击翻译按钮获取中文摘要

The optical properties of nanostructured thin films constitute an important and strategic area of research, evolving rapidly thanks to the development of new tools for investigating single nanoparticles as well as assemblies of nanoparticles. This area has seen remarkable progress made in nanofabrication and nanoparticle synthesis that can allow the fine control of parameters such as size, shape and geometric arrangement for specific properties and applications. The proposed research will work on the optical properties of nanostructured thin films or nanoparticle systems, with an emphasis on the exceptional optical properties of plasmonic films, to further advance the current understanding of the behavior of such films or systems in relation with their nanostructures and the intended applications. In order to achieve our goals, the following is proposed. Advanced theoretical modeling will be performed to explore the different characteristics of various nanoparticles, from the simple spherical shape to complex and challenging configurations. Our work will explore in particular different types of asymmetrical nanoparticle ensembles not studied previously that, according to our recent exploratory work, can present exceptional qualities for sensing environmental changes. Electron lithography will be used for preparing optimized coupled-particle devices that can be characterized by high precision scanning near-field optical spectroscopy. The nonlinear susceptibility of metallic nanorod composites will also be studied in detail as a function of the particle orientation and filling factor, and a theoretical model developed will be used for analysis of the results. Such a type of materials would have great potential for ultrafast, low power all-optical information processing in subwavelength-scale devices. Other applications of nanostructured films will be realized, particularly in the design of innovative and efficient photovoltaics and smart switchable coatings. Plasmonic nanostructures will allow us to manage light at the nanoscale in solar cells in order to increase the device absorption that would lead to enhanced performance. An optoelectronic model with the optical properties of the plasmonic active layers described by an effective medium theory and an organic semiconductor model will be used to study the short-circuit photocurrent influenced by the plasmonic particles. High quality plasmonic organic solar cells will be fabricated and tested accordingly. For their part, nanostructured electrochromic films will likely increase the response times of smart coatings making them readily applicable to smart windows, switchable eyewears or displays. To this aim, we propose to explore fully the potential of the glancing angle deposition (GLAD) method for fabricating thin films to create the desired porosity and a network of nanochannels which would favor ion transport in the electrochromic material. Pertinent measurements will be made for establishing the relationship between nanostructures and sample porosity with the material performance and in particular the response speeds. In summary, the research program proposed is a comprehensive, original and challenging one covering aspects of fundamentals, theory, modeling of linear and nonlinear optical properties as well as device fabrication and characterization, with a potential transfer of technology to industry.