Thesis (M. Phil.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 89-102). Also available in print.

Thesis (M. Sc.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on Dec. 11, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science, Department of Chemicals and Materials Engineering, University of Alberta." Includes bibliographical references.

Thesis (M.S.)--University of Florida, 2002. / Title from title page of source document. Includes vita. Includes bibliographical references.

Thesis (M.S.)--Mississippi State University. Department of Computational Engineering. / Title from title screen. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 137-145).

Thesis (M. Phil.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 184-197).

Organic solar cells (OSCs) are promising candidates for solar light harvesting due to their standout advantages both in material properties and manufacturing process. During past decades, remarkable progress has been achieved. Efficiency for single-junction cells over 9% and tandem cells over 10% has been reported. For high performance OSCs towards commercialization, sufficient light absorption and high quality buffer layers are still two challenges, which are addressed in this thesis by investigating the plasmonic effects on OSCs and interface engineering. Here, the mechanisms of plasmonic effects on OSC are explored by incorporating metallic Au nanoparticles (NPs) in individual anode buffer layer and active layer, respectively, and finally in both layers simultaneously. When Au NPs are incorporated into the buffer layer, surface plasmonic resonance (SPR) induced absorption enhancement due to incorporation of Au NPs is evidenced theoretically and experimentally to be only minor contributor to the performance improvement. The increased interfacial contact area between the buffer layer and active layer, together with the reduced resistance of the buffer layer due to the embedded Au NPs, are revealed to benefit hole collection and thus are main contributors to the performance improvement. When Au NPs are embedded in the active layer, Au NPs induced SPR indeed contributes to enhanced light absorption. However, when large amount of Au NPs are incorporated, the negative effects of NPs on the electrical properties of OSCs can counter-diminish the optical enhancement from SPR, which limits the overall performance improvement. When Au NPs are embedded into both layers, both advantages of incorporating NPs in individual layers can be utilized together to achieve more pronounced improvement in photovoltaic performance; as a result, accumulated enhancements in device performance can be achieved. The results herein are applicable to other metallic NPs such as Ag NPs, Pt NPs, etc. The study herein has clarified the degree of contribution of SPR effects on OSCs and revealed the mechanisms behind. It has also highlighted the importance of considering both optical and electrical effects when employing metallic NPs as strategies to enhance the photovoltaic performance of OSCs. Consequently, the study contributes both physical understanding and technological development of applying metallic NPs on OSCs. Regarding interface engineering, we first propose a simple method to modify the substrate work function for efficient hole collection by using an ultra-thin ultraviolet-ozone treated Au. The method can be used in other situations such as modifying the work function of multilayer graphene as transparent electrode. Then we propose a general method to synthesize solution-processed transition metal oxides (TMOs). Besides high material quality, desirable electrical properties, and good stability, our method stands out particular in that the synthesized TMOs can be dispersed in water-free solvents and the TMO films require only low temperature treatment, which is very compatible with the organic electronics. Our method can also be used to synthesize other TMOs other than the demonstrated molybdenum oxide and vanadium oxide. The proposed method herein is applicable in semiconductor industry. / published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

Recent work by a number of researchers has highlighted areas in which conservative numerical methods give poor solutions. One such situation is in the modelling of material interfaces. A number of methods for overcoming this shortfall of conservative numerical methods are developed. The flow situations that are considered include multicomponent gases and systems of gases and liquids. It is shown that the errors associated with conservative methods when applied to model gas-liquid interfaces are considerably larger than those for gas-gas interfaces. The first approach used for overcoming the errors in conservative methods is a hybrid primitive-conservative method. This method is used in conjunction with a number of new Riemann solvers for a liquid ambient to provide accurate solutions to a number of challenging one and two dimensional test problems. These test problems include the interaction of a shock wave with a bubble in a gas and an underwater explo.; ion. The application of these hybrid methods to the problem of the interaction of a shock wave with a gas bubble in aa liquid demonstrate that they are unable to provide an accurate solution. Two one dimensional methods are described that are able to provide solutions to such test problems. These methods are the moving grid-Chimera approach and a cut cell approach. The cut cell approach is extended into two dimensions and is shown to be able to provide solutions to the problem of the interaction of a shock wave with a gas bubble in a liquid. This method is also shown to be able to provide more accurate solutions to multicomponent gas problems than those on a standard Cartesian grid.

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