Abstract

Graphene quantum dots (GQDs) have grasped the attention of researchers from many fields, mainly due to their unique optoelectronic properties. These properties made GQDs of potential use in various applications, such as photocatalysis, optoelectronics, bioimaging, solar cells, sensors, and surface-enhanced Raman scattering. However, the dependence of their fluorescence spectra on the excitation wavelength has been the focus of several recent studies. While some studies attributed their multi-chromophoric behavior to core and surface states, others related it to the differently-sized nanodomains of sp2-hybridized carbon in an amorphous matrix. Herein, colloidal GQDs were directly synthesized via low-temperature catalytic chemical vapor deposition (CVD). These graphene nanostructures were found to exhibit well-resolved multi-emission bands in the visible region. Based on the X-ray photoelectron, FT-IR and Raman spectroscopies, as well as density functional theory (DFT) calculations, the role of polycyclic aromatic hydrocarbons (PAHs), was identified as the building blocks of GQDs. Also, the fluorescence spectra of GQDs thin films were investigated. Moreover, the effect of plasmonic nanomaterials, such as silver nanodisks (AgNDs), on their fluorescence was investigated. A Polyvinylpyrrolidone (PVP) polymer is used as a dielectric material to prevent the diffusion of the AgNDs particles in the GQDs layer and minimize the quenching effect. Different four concentrations of GQDs were used (0.2%, 1%, 3% and 5%) to get the optimum conditions of GQDs/spacer/AgNDs hybrid-nanomaterial. The 1% weight concentration of GQDs shows the optimum fluorescence emission of GQDs/spacer/AgNDs composite.

Department

Physics Department

Degree Name

MS in Physics

Graduation Date

2-1-2017

Submission Date

January 2018

First Advisor

Nageh, Allam

Committee Member 1

El Sheikh, Salah

Committee Member 2

Salah, Lobna Mohamed

Extent

84 p.

Document Type

Master's Thesis

Rights

The author retains all rights with regard to copyright. The author certifies that written permission from the owner(s) of third-party copyrighted matter included in the thesis, dissertation, paper, or record of study has been obtained. The author further certifies that IRB approval has been obtained for this thesis, or that IRB approval is not necessary for this thesis. Insofar as this thesis, dissertation, paper, or record of study is an educational record as defined in the Family Educational Rights and Privacy Act (FERPA) (20 USC 1232g), the author has granted consent to disclosure of it to anyone who requests a copy.

Institutional Review Board (IRB) Approval

Not necessary for this item

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