Thesis (Ph.D.)--Bowling Green State University, 2009. / Document formatted into pages; contains xix, 184 p. : ill. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (p. 76-82).

The problem of heavy material and radiative losses in plasmonic devices has held back their implementation for compact and high-speed data storage and interconnects. One of the most interesting solutions to this problem currently under exploration is the addition of a gain material in close proximity to the metallic nanostructures for loss compensation. Here the physics of light transport in a nanoparticle array, and the operation of gain media in contact with the structure, are described and analytically modeled. A two-dimensional array of closely spaced gold nanoparticles has been fabricated by focused ion beam milling, and its electromagnetic response in the presence or absence of a dye coating has been simulated in preparation for pump-probe optical testing. The compensation of losses via a fluorophore coating has been proven for the first time in this geometry, for a physically realized sample. / text

Zinc oxide (ZnO) is a wide band-gap semiconductor that is of interest for application in dye sensitized solar cells (DSSCs) because of similarity of its properties to TiO2. Unlike TiO2, ZnO can readily be grown in a wide variety of morphologies, using inexpensive, simple, and low temperature methods. Recent research on ZnO-based DSSCs focuses on modifying the ZnO layer morphology in order to maximize surface area, and enhance the electron collection by providing fast electron transport. It is expected that the improvement in cell performance by morphology modification is due to higher dye loading, increased electron lifetime and fast electron transport. However, ZnO properties may be affected by various synthesis methods. It is difficult to make a conclusion whether the change of performance are attributed to change of morphology or a change in the defect types and/ or defect concentrations. In this study, the influence of ZnO nanoparticle properties on cell performance has been investigated. Commercial ZnO nanoparticles with different sizes and optical properties were utilized. It was found that there is a complex relationship between native defects, dye loading, charge transport and photovoltaic performance. In particular, the presence of non-radiative defects was found to be detrimental to photovoltaic performance. In addition, with the similar defect emission intensities, sample exhibiting orange-red defect emission showed better performance than the samples emitting green defect emission. Nanoparticle properties and their relationship between dye adsorption, electron injection, electron lifetime and electron transport, and photovoltaic performance will be discussed. / published_or_final_version / Physics / Master / Master of Philosophy

Textile dyes are molecules designed to impart a permanent colour to textile fabrics. They pose an environmental problem because they are toxic and they decrease the aesthetic value of rivers and lakes. Current technologies for dye removal cannot remove all classes of dyes and two or more technologies are usually combined to achieve statisfactory decolourization efficiencies. Lignin-degrading enzymes like laccases are potential technologies for dye decolourization and decolourization with immobilized laccase has been intensively investigated. The majority of those studies however have focused on dye disappearance and several reported that significant dye adsorption had occured during the dye removal, making the role of the enzyme unclear. Moreover, textile wastewaters contain auxiliary chemicals that can impact enzymatic dye decolourization and very few studies have evaluated the impact of those substances on laccase. This research evaluated the feasibility of treating dye-contaminated textile wastewaters with an immobilized laccase system. The first sub-objective was to examined the decolourization of Reactive blue 19 (an anthraquinone dye) by Trametes versicolor laccase immobilized on controlled porosity carrier (CPC) silica beads and the second was to analyze the kinetic effects of a non-ionic surfactant Merpol, sodium sulfate, and sodium chloride on laccase decolourization of Reactive blue 19. Decolourization of Reactive blue 19 by immobilized laccase was mainly enzymatic although dye some adsorption occurred. Decolourization led to less toxic by-products from azo and indigoid dyes whereas increased toxicity was observed for anthraquinone dyes. The feasibility of immobilizing laccase on poly(methyl methacrylate) (PMMA) through its sugar residues with a simple procedure was demonstrated and the mass of enzyme immobilized compared well with other commercial acrylic supports. The decolorization of Reactive blue 19 by laccase was inhibited by the non-ionic surfactant, Merpol by substrate depletion. A model describing this inhibition was developed and was validated by a saturated equilibrium binding experiment. While sodium sulfate (ionic strength) had no effect on either ABTS oxidation or dye decolourization, sodium chloride inhibited laccase during dye decolourization and the type and nature of the inhibition depended on the substrate. With ABTS, the inhibition was hyperbolic non-competitive whereas it was parabolic mixed with Reactive blue 19. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2009-06-16 16:58:47.753

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Excitonic photovoltaic devices, including organic, hybrid organic/inorganic, and dye-sensitized solar cells, are attractive alternatives to conventional inorganic solar cells due to their potential for low cost and low temperature solution-based processing on flexible substrates in large scale. Though encouraging, they are currently limited by the efficiency from not yet optimized structural and material parameters and poor overall knowledge regarding the fundamental details. This dissertation aims to achieve improved performance of hybrid solar cells by enhancing material property and designing new device architecture. The study begins with the addition of XD-grade single-walled carbon nanotube (XDSWNT) into poly(3-hexylthiophene) (P3HT) to improve the current density. By having a weight ratio of XDSWNT and P3HT equaled to 0.1:1, short-circuit current was quadrupled from 0.12 mA cm-2 to 0.48 mA cm-2 and solar cell efficiency was tripled from 0.023% to 0.07%, compared to devices with pure P3HT as a hole transport material. Secondly, a significant improvement in device efficiency with 250 nm long ZnO nanorod arrays as photoanodes has been achieved by filling the interstitial voids of the nanorod arrays with ZnO nanoparticles. The overall power conversion efficiency increased from 0.13% for a nanorod-only device to 0.34% for a device with combined nanoparticles and nanorod arrays. The higher device efficiency in solid-state DSSCs with hybrid nanorod/nanoparticle photoanodes is originated from both large surface area provided by nanoparticles for dye adsorption and efficient charge transport provided by the nanorod arrays to reduce the recombinations of photogenerated carriers. Followed by the novel layer-by-layer self-assembly deposition process, the hybrid photoanode study was extended to the longer ZnO nanorod arrays. The best performance, 0.64%, was achieved when the thickness of the photoanodes equaled to 1.2 ?m. Finally, the photovoltaic devices were modified by adding ZnO nanoarpticles into P3HT to increase interfacial area between ZnO and P3HT. The efficiency was enhanced from 0.18% to 0.45% when the ZnO nanorod arrays were 625 nm in length. Our successful design of the device morphology significantly contributes to the performance of solid-state hybrid solar cells.

Over the past decade, intensive academic and commercial interests have been paid on compounds possessing photochemical properties, namely for their preparation, chemical properties, high efficiency and potential low-cost. Compounds having intense photochemical properties gained great interest due to wide range of potential applications. The sensitizers are one of the key components for high power-conversion efficiency in the dye sensitized solar cells (DSSCs). They are the core components in the organic light-emitting devices (OLEDs) due to their ability to emit light with the wavelengths largely red- shifted from their absorption wavelength. Ruthenium based sensitizers have been tagged “molecular light switches” because, although the fluorescence of these complexes in aqueous solutions is negligible, it increases of greater than 10000 fold in the presence of DNA. Many polypyridyl and dipyrido phenazine ruthenium complexes have achieved high power conversion efficiencies and therefore are of practical interest. Several research groups stated that the dipyrido phenazine ligand may be thought of as comprising two components: a bipyridyl unit and a phenazine unit. These two subunits behave essentially separately, with many molecular orbitals being localised over only one subunit and a redox properties of central phenazine moiety in the dipyrido phenazine ligand are important for the photochemical applications. Therefore a phenazine ligand was selected as a model for the present investigation. The chemistry of phenazine ligand is mostly limited to the late transition metal and f - element complexes. Our laboratory has a rich backgroung in the aluminum and early transition metal chemistry. The aluminum chemistry and early transition metal chemistry are of great interest since aluminum and early transition metal complexes are environmentally friendlier and cheaper than the late transition metal compounds. Another drawback of the ruthenium-based sensitizers is the lack of absorption in the red region of the visible spectrum, and also low molar extinction coefficients. An essential requirement for efficient conversion of solar energy is the good spectral match of the sensitizer absorption to the emission spectrum of solar radiation. In this regard, the ruthenium sensitizers’ spectral response in the lower energy regions is not sufficient. The current project has three parts. In the first part we collected and reviewed known literature regarding the certain classes of non-innocent ligands containing the six-membered carbon- nitrogen heterocycles and regarding the ligands potentially important for the photochemical applications. We also reviewed all available to the data information about the complexes supported by the phenazine ligand. In the second part we have investigated interaction of alkylaluminum compounds and phenazine and observed reduction of phenazine accompanied by formation of dialuminum cage type compounds containing two formally mononegative phenazine ligand. The derivatization of phenazine has been also observed. It resulted in formation of compounds having a stable organic radical. In a third part of our project we have explored interaction of phenazine or thiophenazine with the alkylaluminum compounds and chromium dichloride. The reaction in the three component system resulted in reduction of phenazine ligand and lead to the heterometallic Cr(II) - aluminum complexes containing a formally dinegative phenazine or thiophenazine ligands. When a large excess of triethylaluminum was taken, reduction of phenazine and chromium has been observed leading to the heterometallic multinuclear Cr(I) - aluminum complex containing a formally dinegative phenazine ligands and two chromium atoms in one complex in the rare oxidation state one.

Thesis (Ph. D.)--University of Hong Kong, 2010. / Includes bibliographical references. Also available in print.

Thesis (M.Sc.)--Victoria University of Wellington, 2009. / Includes bibliographical references.