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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
161

HOW ELECTRODE MATERIAL AFFECTS THE PERFORMANCE OF POLYMER LIGHT-EMITTING ELECTROCHEMICAL CELLS

Hohertz, DONNA 23 September 2008 (has links)
Polymer light emitting electrochemical cells (LECs) are solid-state devices containing an active layer blend of luminescent polymer, ion transport material and salt sandwiched between two electrodes. They operate on the principal of in situ electrochemical doping. Doping entails the injection of electronic charge from the electrodes, causing the reduction/oxidization of the luminescent polymer, and accompanied by charge compensation through the redistribution of salt counter-ions. Due to the high conductivity of the doped polymer, a fully turned on LEC has a dramatically reduced contact and bulk resistance. This gives the LEC certain intrinsic advantages such as balanced charge injection, low operating voltage and high quantum efficiencies, even when stable metal or symmetric electrodes are used. These properties have led to the popular assumption that the electrode work function is not a critical device parameter for LEC operation. In this thesis, I describe my original research to determine how the electrode composition influences LEC performance. A series of sandwich and planar configuration LECs with various electrodes on identical MEH-PPV (poly[5-(2-ethylhexyloxy)-2-methoxy-1,4-phenylene vinylene]):PEO (poly ethylene oxide):LiTr (Lithium trifluoromethanesulfonate) based films are constructed. I demonstrate that the doping profile, doping propagation speed, emission zone shape, emission zone location, electro-luminescence (EL) turn-on, and EL efficiency are all strongly affected by the choice of electrode materials. LECs with asymmetrical electrodes optimized for both electron and hole injection result in the best overall performance. Using an optimized electrode configuration, I am able to realize extremely large crown ether based planar LECs. MEH-PPV: dicyclohexano-18-crown-6 (DCH18Cr6): LiTr and 108GE:DCH18Cr6:LiTr devices with various symmetric and asymmetric electrode configurations were constructed, where 108GE is the fluorene copolymer poly[(9,9-dioctyl-2,7-divinylene-fluorenylene)-alt-co-(2-methoxy-5-(ethylhexyloxy)-1,4-phenylene)]. I demonstrate ii i and image the first ever crown ether-based planar LECs with millimeter inter-electrode spacing. Due to minimal phase separation, crown ether-based LECs display highly uniform doping propagation and very smooth emission zones. Junction relaxation, de-doping and reverse bias operation experiments are also presented, and results compared to behavior in PEO based LECs. Additionally, I demonstrate that crown ether-based LECs do not exhibit frozen junction behavior at room temperature. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2008-09-23 16:15:06.569
162

Classical and Quantum Optical Properties of Slow Light Photonic Crystal Waveguides

Patterson, Mark 03 September 2009 (has links)
Photonic crystals are optical materials where patterning of dielectrics on sub-wavelength length scales creates unusual optical properties such as waveguides with propagation speeds much slower than the vacuum speed of light. In this thesis, I examine the classical and quantum optical properties of such structures, specifically the enhancement of photon emission rate from a single quantum dot embedded in the waveguide (the Purcell Effect) and extrinsic scattering from an injected waveguide mode due to fabrication imperfections. The photon emission rate is found to be significantly enhanced over a large bandwidth in slow light photonic crystal waveguides and I provide detailed results for optimizing the emission properties of a novel photonic crystal ridge waveguide to suite a given application. Using an incoherent scattering theory, I show how slow light propagation enhances extrinsic scattering from unavoidable manufacturing imperfections leading to back scattering and radiation loss that scale with the group velocity v_g, as v_g^{-2} and v_g^{-1} respectively. I then improve the modeling of scattering using a coherent, multiple scattering approach to explain the experimental observation of disordered resonances in slow light waveguide modes. The theoretical predictions show good agreement with experimental measurements. This document provides a thorough introduction to the properties and problems of slow light photonic crystal waveguides. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2009-09-03 12:29:01.696
163

A new community park for wellness: revitalizing and healing the mind and body

Hoag, Jana J. 29 March 2011 (has links)
A New Community Park for Wellness presents a new vision for parks. It proposes a new era of park programming, the ‘Community Wellness and Holistic Health Era’ in order to improve our communities with design that highlights natural phenomena. Today, health is no longer about disease or death; it’s about maintenance - getting outside, having access to fresh food and living a balanced lifestyle. Drawing on historical and contemporary wellness precedents, this practicum aims to create a community destination that promotes health and prevents disease in Winnipeg, Manitoba. It documents investigations into park programming and design, current trends in health and wellness, potential roles of light and water in landscape architecture, and light in modern and post-modern Scandinavian architecture. The final design emphasizes natural phenomena and processes related to light, water and energy in order to promote health and reconnect urban residents with time, place and the changing seasons.
164

Global reactor effects on homogenized parameters for nodal diffusion theory analyses of light water reactors

Malo, James Walter 05 1900 (has links)
No description available.
165

Natural lighting as a design issue in architecture

de St. Aubin, William Joseph 05 1900 (has links)
No description available.
166

The effect of light intensity on root growth and net assimilation rate of barley.

Daniels, Keith Egbert. January 1968 (has links)
No description available.
167

Non-classical effects in optics

Fearn, H. January 1989 (has links)
No description available.
168

The quantum theory of optical parametric amplification

Hussain, N. A. January 1991 (has links)
No description available.
169

Theory of plasmon-polaritions in superlattices

Constantinou, N. C. January 1988 (has links)
No description available.
170

Ljus Utomhus : För var mans trädgård

Hummel, Anna January 2014 (has links)
Jag skall i mitt projekt först och främst få erfarenhet av hur det är att samarbeta som designer med ett företag och även få ut en produkt som är klar att använda och som skall kunna säljas i butiker runt om i landet. Den skall följa företagets riktlinjer, vara energisnål och vara funktionell men samtidigt tilltalande. / Produktdesign/Självständigt projektarbete – Examensarbete

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