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The aim of this document is to investigate through industrial design the potential of a high efficiency photovoltaic concentrator theory. The investigation directs a proposed layout for the design of a device, which specifically addresses the incorporation of the concentrator theory into the design of a photovoltaic ????????roof tile????????. The focus of the investigation has been the integration of theoretical constructs and physical realities. The objective is to facilitate this transition from theory to reality: to contribute to the quest of creating viable manufacturable designs for the generation of clean low cost electrical power. The use of a roof tile as the focus of the incorporating device served two purposes. Number one: it provided a sensible, existing platform, which is under utilised, presented potential and fitted within established building practices. It was not the objective of this thesis to argue that tile integration is the best, only or even the most financially viable direction to pursue; it was one option among many. This brings us to the second purpose; the consideration of existing roofing tiles forced the theory to be applied within set limitations, in particular existing size restrictions. The imposition of a framework to work within highlighted the design issues, which would have to be addressed in the actualisation of the theory. The theory????????s broad strategy for economic viability has been to reduce the actual silicone cell content of panel designs by approximately one third. This is achieved by the use of numerically fewer cells in combination with a concentration method, which does not cost more than the savings gained by the use of fewer cells. This document records the design process undertaken and presents the findings so that further development can be undertaken.

Thin-film silicon photovoltaics are seen as a good possibility for reducing the cost of solar electricity. The focus of this thesis is the ALICIA cell, a thin-film polycrystalline silicon solar cell made on a glass superstrate. The name ALICIA comes from the fabrication steps - ALuminium Induced Crystallisation, Ion Assisted deposition. The concept is to form a high-quality crystalline silicon layer on glass by Aluminium Induced Crystallisation (AIC). This is then the template from which to epitaxially grow the solar cell structure by Ion Assisted Deposition (IAD). IAD allows high-rate silicon epitaxy at low temperatures compatible with glass. In thin-film solar cells, light trapping is critical to increase the absorption of the solar spectrum. ALICIA cells have been fabricated on textured glass sheets, increasing light absorption due to their anti-reflection nature and light trapping properties. A 1.8 μm thick textured ALICIA cell absorbs 55% of the AM1.5G spectrum without a back-surface reflector, or 76% with an optimal reflector. Experimentally, Pigmented Diffuse Reflectors (PDRs) have been shown to be the best reflector. These highly reflective and optically diffuse materials increase the light-trapping potential and hence the short-circuit currents of ALICIA cells. In textured cells, the current increased by almost 30% compared to using a simple aluminium reflector. Current densities up to 13.7 mA/cm2 were achieved by application of a PDR to the best ALICIA cells. The electronic quality of the absorber layer of ALICIA cells is strongly determined by the epitaxy process. Very high-rate epitaxial growth decreases the crystalline quality of the epitaxial layer, but nevertheless increases the short-circuit current density of the solar cells. This indicates that the diffusion length in the absorber layer of the ALICIA cell is primarily limited by contamination, not crystal quality. Further gains in current density can therefore be achieved by increasing the deposition rate of the absorber layer, or by improving the vacuum quality. Large-area ALICIA cells were then fabricated, and series resistance reduced by using an interdigitated metallisation scheme. The best measured efficiency was 2.65%, with considerable efficiency gains still possible from optimisation of the epitaxial growth and metallisation processes.

Photovoltaics is currently the fastest growing energy source in the world. Increasing the conversion efficiency towards the thermodynamic limits is the trend in research development. ???Third generation??? photovoltaics involves the investigation of ideas that may achieve this goal. Among the third generation concepts, the tandem cell structure has experimentally proven to have conversion efficiencies higher than a standard p-n junction solar cell. The alternative hot carrier solar cell design is one of the most elegant approaches. Energy selective contacts are crucial elements for the operation of hot carrier solar cells. Besides the carrier cooling problem within the absorber, carrier extraction has to be done through a narrow range of energy to minimise the interaction between the hot carriers in the absorber and the cooler carriers in the contacts. Resonant tunnelling through localised states, such as associated with atomic defects or with quantum dots in a dielectric matrix, may provide the required energy selectivity. A new model in studying the properties of resonant tunnelling through defects in an insulator is proposed and investigated. The resulting calculations are simple and useful in obtaining physical insight into the underlying tunneling processes. It is found that defects having a normal distribution along the tunnelling direction do not reduce the transmission coefficient dramatically, which increases the engineering prospects for fabrication. Silicon quantum dots embedded in an oxide provide the required deep energy confinement for room temperature resonant tunnelling operation. A single layer of silicon quantum dots in the centre of an oxide matrix are prepared by RF magnetron sputtering. The method has the advantage of controlling the dot size and the dot spatial position along the tunnelling direction. The presence of these crystalline silicon dots in the oxide is confirmed by high resolution transmission electron microscopy (HRTEM). A negative-differential resistance characteristic has been measured at room temperature on such structures fabricated on an N-type degenerated silicon wafer, a feature that can be explained by the desired resonant tunnelling process. A silicon quantum dot superlattice can be made by stacking multiple layers of silicon quantum dots. A model is proposed for calculating the band structure of such a silicon quantum dot superlattice, with the anisotropic silicon effective mass being taken into account. It suggests a high density of silicon quantum dots in a carbide matrix may provide the bandgap and required mobility for the top cell in the stacks for the recently proposed all-silicon tandem solar cell. The resonant tunnelling modeling and silicon quantum dot experiments developed have demonstrated new results relevant to energy selective contacts for hot carrier solar cells. Building on this work, the modeling study on silicon quantum dots may provide the theoretical basis for bandgap engineering of all-silicon tandem cells.

Thesis (M. Des. (Hons.))--College of Fine Arts, University of New South Wales, 2001. / Also available online.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 141-186). Also available via the Internet.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 182-185). Also available via the Internet.

Thesis (M.S.)--University of Wyoming, 2006. / Title from PDF title page (viewed on June 13, 2008). Includes bibliographical references (p. 104-105).

Thesis (M.S.)--University of Wisconsin--Madison, 1989. / Typescript. Title from title screen (viewed July 2, 2008). Includes bibliographical references (p. 278-282). Online version of the print original.