Novel design-based complex nanostructures in hybrid core-shell architectures for high-efficiency light generation
Author
Özel, İlkem Özge
Advisor
Demir, Hilmi Volkan
Date
2010Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
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Abstract
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.
Keywords
Nanostructuresnanomaterials
plasmonics
localized plasmons
metal-enhanced luminescence
exciton migration
non-radiative energy transfer
Förster resonance energy transfer (FRET)
hybrid nanoparticles
metal nanoparticles
semiconductor nanocrystals
colloidal quantum dots
conjugated polymers
excitons
spontaneous emission
photoluminescence
time-resolved fluorescence
FDTD