Browsing by Subject "nanomaterials"

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Open Access
Novel design-based complex nanostructures in hybrid core-shell architectures for high-efficiency light generation
(2010) Özel, İlkem Özge
Recent developments in nanoscience and nanotechnology have given rise to the discovery of hybrid nanostructured multi-component materials that serve several tasks all at once. A very important and rapidly growing field of these materials is the development of highly efficient fluorophores to meet the urgent demand of low-energy consuming, high-quality light emitters for future solid-state lighting applications. Such hybrid nanomaterials are entailed to exhibit extraordinary optoelectronic properties compared to the bulk case of their single components such as enhanced quantum efficiency, tunable multi-color emission, and reduction of multiple processing steps. Herein, to address these requirements, we propose and demonstrate novel design-based complex nanomaterials in hybrid multi-shell architectures for high-efficiency light generation. These requirements are made possible by using the concept of hybrid core-shell-… nanostructures comprising at least two units, including hybrid metalcore/dielectric-shell nanoparticles furnished with an outer shell of semiconductor nanocrystals for enhanced emission and different conjugated polymers forming a single multi-polymer nanoparticle and emitting simultaneously at different wavelengths. In the first part of this thesis, we developed and demonstrated Au-silica core/shell nanoparticles that successfully assemble CdTe nanocrystals right on their silica shells for enhanced plasmonexciton interactions, while solving the common problems of lacking control in dielectric spacing and limited film thickness typically encountered in such plasmon-coupled nanocrystals. Here we present the synthesis and characterization results of this new set of multi-shell decorated nanoparticle composites with a tunable dielectric spacing thickness of silica shell precisely controlled by synthesis to optimize plasmon-exciton interactions for enhanced emission. Experimental data obtained from steady-state and time-resolved photoluminescence measurements together with extensive computational analysis clearly verify the strong plasmon-exciton interactions in these designbased multi-shell nanocomposites. In the second part, we construct bi-polymer nanoparticle systems in various architectures of core/shells, for each of which thorough investigations of the non-radiative energy transfer mechanisms are made. Here we present the synthesis and characterization results of these core/shell bi-polymer nanoassemblies. The flexibility of designing such bipolymer nanostructures allows for the optimization of maximum energy transfer efficiency. This concept of complex hybrid nanostructures for high-efficiency light generation opens up new paths for optoelectronic devices and nanophotonics applications including those in solid-state lighting.
Open Access
Self-assembled peptidic nanostructures
(Elsevier, 2009) Toksoz, S.; Güler, Mustafa O.
Understanding the mechanisms of molecular self-assembly processes in natural materials is an important step to developing new functional materials with useful properties. Recently, various self-assembled materials have gained attention because of their interesting properties in nanoscale. Nanostructures composed of peptides are especially of interest in materials development because of their many advantageous properties such as biodegradability, biocompatibility and customizable bioactivity. Self-assembled peptidic nanostructures have been studied by many research groups and found use as three-dimensional cell scaffolds for bone regeneration, dental implants, neural tissue engineering, biosensors for detection of viruses and other pathogens, antibacterial agents and in drug, protein and gene delivery.