Lithium ion batteries are fast becoming the consumer choice for powering their electronic devices. However, current lithium batteries energy densities are not suf- ficiently high, and cost per kWh sufficiently low, to be widely accepted as batteries in electric vehicles. In order to reduce the cost and increase the energy density it may be necessary to move away from intercalation electrode materials, that are limited by the number of vacant lithium interstitial sites available, to conversion reaction materials that can allow multiple electron transfer. This thesis looks to investigate the use of a non- transition metal fluoride as a cathode material in a primary or secondary lithium battery. Initial results for the ball milled material show specific energy densities over 2050 Wh/kg. The initial energy density rapidly faded over a period of a few cycles due to the structural change of the material and unwanted reactions with the electrolyte. These were identified by investigating the mechanism of the one stage discharge and charge profile. To further improve the cycling results nanorods were synthesised which improved the rate capability to provide an energy density of over 1250 Wh/kg at a discharge rate of 0.25C. The capacity over repeated cycling was also improved but the same problems that plagued the ball milled samples were also apparent in the nanorod samples. It was found during the initial investigation of the non-transition metal fluoride material that it is rechargeable, but for a limited number of cycles partly due to its poor kinetics. It has the potential to be a good rechargeable battery material but if not can satisfactorily compete with commercial primary batteries in terms of energy density and cost, as it is a very cheap material.

The comparative ease with which direct current machines can be controlled has led to their application in various fields and in order to achieve accurate and versatile control of the machine "Four quadrant" controllers have been developed over many years. Originally these controllers were of the "Ward Leonard" type, involving rotating machines. With the advent of mercury arc rectifiers static controllers were devised, and more recently the development of high power thyristors as the main power control element has enabled solid state four quadrant controllers to be reliable and cheap. However, the introduction of a new series of high power transistors with improved ratings, static controllers using power transistors as the power control element are becoming more feasible. Several controllers have already appeared on the market but with limited capacity since transistor development still lags behind that of the thyristor. The transistor being a fully controllable element (requiring no "turn-off" mechanism) easily lends itself to switching amplifiers for motor control applications. These switching amplifiers are capable of producing a good frequency response at high overall efficiency. It is the aim of this dissertation to investigate the possibilities of producing switching amplifiers for the control of alternating and direct current machines.

My thesis focuses on evidencing the practice of co-operative inquiry (Heron, 1996). I explore key themes and questions that emerged as I worked with this methodology for the first time, having established a co-operative inquiry group of young women managers within Procter & Gamble UK for the pUrpose of my PhD research. At the time of embarking on this work, accounts of the detail of practical engagement in inquiry process were sparse. Progress has since been made. My thesis contributes to this progress by raising questions about practice and evidencing the detail. Through this, I offer ideas about quality of practice - 'the educative edge' of action research - and a re-visioning of the co-operative inquiry extended epistemology - 'Naming as Knowing'.

The quest for renewable energy sources has led to growing attention in the research of organic photovoltaics (OPVs), as a promising alternative to fossil fuels, since these devices have low manufacturing costs and attractive end-user qualities, such as ease of installation and maintenance. Wide application of OPVs is majorly limited by the devices lifetime. With the development of new encapsulation materials, some degradation factors, such as water and oxygen ingress, can almost be excluded, whereas the thermal degradation of the devices remains a major issue. Two aspects have to be addressed to solve the problem of thermal instability: bulk effects in the photoactive layer and interfacial effects at the photoactive layer/charge-transporting layers. In this work, the interface between photoactive layer and electron-transporting zinc oxide (ZnO) in devices with inverted architecture was engineered by introducing polymeric interlayers, based on zinc-binding ligands, such as 3,4-dihydroxybenzene and 8-hydroxyquinoline. Also, a cross-linkable layer of poly(3,4-dimethoxystyrene) and its fullerene derivative were studied. At first, controlled reversible addition-fragmentation chain transfer (RAFT) polymerisation was employed to achieve well-defined polymers in a range of molar masses, all bearing a chain-end functionality for further modifications. Resulting polymers have been fully characterised, including their thermal and optical properties, and introduced as interlayers to study their effect on the initial device performance and thermal stability. Poly(3,4-dihydroxystyrene) and its fullerene derivative were found unsuitable for application in devices as they increased the work function of ZnO and created a barrier for electron extraction. On the other hand, their parental polymer, poly(3,4-dimethoxystyrene), and its fullerene derivative, upon cross-linking, resulted in enhanced efficiency and stability of devices, if compared to control. Polymers based on 8-hydroxyquinoline ligand had a negative effect on the initial stability of the devices, but increased the lifetime of the cells under accelerated thermal stress. Comprehensive studies of the key mechanisms, determining efficiency, such as charge generation and extraction, were performed by using time-resolved electrical and spectroscopic techniques, in order to understand in detail the effect of the interlayers on the device performance. Obtained results allow deeper insight into mechanisms of degradation that limit the lifetime of devices and prompt the design of better materials for the interface stabilisation.

Organic Solar Cells (OSCs) represent a photovoltaic technology with multiple interesting application properties. However, the establishment of this technology into the market is subject to the achievement of operational lifetimes appropriate to their application purposes. Thus, comprehensive understanding of the degradation mechanisms occurring in OSCs is mandatory in both selecting more intrinsically stable components and/or device architectures and implementing strategies that mitigate the encountered stability issues. Inverted devices can suffer from mechanical stress and delamination at the interface between the active layer, e.g. poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM), and the hole transport layer, e.g. poly(3,4-ethylenedioxythiophene):poly(p-styrene sulfonate) (PEDOT:PSS). This work proposes the incorporation of a thin adhesive interlayer, consisting of a diblock copolymer composed of a P3HT block and a thermally-triggerable, alkyl-protected PSS block. In this context, the synthesis of poly(neopentyl p-styrene sulfonate) (PNSS) with controlled molar mass and low dispersity (Ð ≤ 1.50) via Reversible Addition-Fragmentation chain Transfer (RAFT) polymerisation has been extensively studied. Subsequently, Atomic Force Microscopy (AFM) was explored to characterise the thermal deprotection of P3HT-b-PNSS thin layers to yield amphiphilic P3HT-b-PSS, indicating that surface deprotection prior to thermal treatment could occur. Finally, structural variation of the alkyl protecting group in PSS allowed reducing the thermal treatment duration from 3 hours (P3HT-b-PNSS) to 45 minutes for the poly(isobutyl p-styrene sulfonate) (PiBSS) analogous copolymer. Another critical issue regarding the stability of OSCs is the sunlight-driven chemical degradation of the active layer. In the study herein, the combination of experimental techniques and theoretical calculations has allowed identification of the structural weaknesses of poly[(4,4’- bis(2-ethylhexyl) dithieno [3,2-b:2’,3’-d]silole)-2,6-diyl-alt-(4,7-bis(2-thienyl)-2,1,3-benzothiadiazole)-5,5’-diyl], Si-PCPDTBT, upon photochemical treatment in air. Additionally, the study of the relative photodegradation rates in air of a series of polymers with systematically modified backbones and/or alkyl side chains has shown no direct correlation between chemical structure and stability. It is proposed instead that photostability is highly dependent on the crystalline character of the deposited films. Furthermore, it was verified that photostability of blends based on these polymers is dictated by the (de)stabilising effect that [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) has over each polymer. Finally, a multiscale analysis on the degradation of solar cells based on poly[4,4' bis(2- ethylhexyl) dithieno[3,2-b:2',3'-d]silole)-2,6-diyl-alt-[2,5 bis(3 tetradecylthiophen 2-yl)thiazole[5,4-d]thiazole)-1,8-diyl] and PCBM, indicated that by judicious selection of device layers, architectures, and encapsulation materials, operational lifetimes up to 3.3 years with no efficiency losses can be successfully achieved.

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This work investigates means of overcoming the problems of Short exciton diffusion length and low charge mobility in polymer solar cells. The first issue is addressed by using a novel polyphenylenevinylene (PPY) derivative, which has a permanent dipole on the repeat unit of the polymer, to dissociate excitons in the polymer bulk, rather than requiring exciton diffusion to a dissociating interface. The second is dealt with by adding a lithium salt to polymer/Ti02 devices to improve hole mobility. The photophysical characteristics and photovoltaic device performance of a PPY derivative with a fluorene sidegroup, with and without an electron withdrawing nitro moiety which bestows a larger dipole moment across the repeat unit of the polymer, are reported. The photoluminescence of the polymer with the nitro group (nitrofluoro-PPY) is lower than that of its non-nitro (fluoro-PPY) analogue by a factor of eight. Lightinduced electron spin resonance experiments show that the nitrofluoro-PPY has more photoinduced spins, indicating that the luminescence quenching is due to intramolecular charge separation. Photovoltaic devices made with the nitrofluoro-PPY are three times as efficient as those with the fluoro-PPY, mainly due to an increase in current. Both types of device are inefficient, similar to previously reported all-polymer devices, and their efficiency is greatly improved by the incorporation of a solubilized C60 electron transporting phase. The addition of a lithium salt (Li[CF3S02hN) to MEH-PPY/Ti02 solar cells drastically improves device performance by increasing both the fill-factor and shortcircuit current by up to 40%. The efficiency of Li[CF3S02hN modified devices is 1.05% under 80 mWIcm2 simulated solar illumination, twice that of control devices without the salt and the highest reported to date for any polymer/Ti02 solar cell. The improved performance is attributed to a large increase in the hole mobility in the polymer, as measured by space-charge-limited current measurements, in the presence of the lithium salt. Modification of devices with the salt LiCI04 is not as effective at improving device performance. Secondary ion mass spectroscopy studies suggest that this is due to poorer diffusion of lithium into the polymer layer for LiCI04 relative to Li[CF3S02hN. The novel charge separation polymers studied here may serve to inform the development of all-organic dyes, and lithium salt treatment of bulk heterojunction devices may lead to significant improvements in power conversion efficiency.

Photovoltaic thermal (PVT) solar collectors generate heat and electricity. Building Integrated (BI) facade collectors are suited to high rise buildings. Ulster University researches novel Integrated Collector-Storage Solar Water Heaters (ICSSWH). This study investigates Planar Liquid-Vapour Thermal Diode (PLVTD) heat transfer and characterises performance of a BIPVT-PLVTD-ICSSWH prototype. A thermal resistance network representing evaporation, vapour transfer, condensation, fluid conduction and convection, plate-to plate radiation, and solid conduction is established and evaluated using Stefan-Boltzmann and Fourier laws together with Rayleigh/Reynolds-Nusselt and Rohsenow correlations.

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