This thesis investigates in detail the thin film materials required for the construction of a thin film electrochromic device, their production by vacuum deposition and other techniques, and their characterisation by SEM, XRD, and optical and electrochemical methods, leading to a greater understanding of the materials and considerations required in the design of electrochromic layers and devices constructed with said layers. Working devices consisting of electrochromes, electrolytes and transparent conducting electrodes are constructed by methods and upon a scale that are amenable to commercial-scale production. The hardware and software components of a unique real-time spectroscopic electrochemical characterisation cell are described, which have enabled the novel synchronous collection of wideband optical transmittance and electrochemical information at intervals as small as 20ms. Optimal process conditions for the production of electrochromic transition metal oxides of nickel, titanium, tungsten and the novel nickel-chromium oxide by advanced sputtering and electron-beam evaporation techniques are investigated and described in-depth. For comparison, devices are also constructed using the well-known electrochromic material iron hexacyanoferrate, or 'Prussian Blue'. It is essential for devices intended for eyewear applications that materials are eye-safe and that traffic light recognition is not unduly impaired. The electrochromic performance of individual materials and working devices is reported for all materials and spectroscopic data is used to calculate tristimulus co-ordinates and thus characterise the colour performance of the various materials and devices. Working devices also require transparent conductive electrodes. The transparent conductive oxide indium tin oxide (ITO), as prepared by two different sputtering methods is investigated. The sheet resistance of the ITO is shown to have a significant quantifiable effect upon the switching speed of working devices and this is reported in detail.

This thesis looks at two different problems involving halide and oxide systems: The first problem concentrates on the form of CaF 2 films upon a BaF 2 substrate with the objective of determining the structure of CaFzlBaF2 boundaries in CaFzlBaF2 hetero-films. CaF2IBaF2 hetero-film conductivity is much larger than that found for bulk CaF2 and BaF2 systems. Additionally conductivity within these hetero-structures generally increases in proportion to the number ofCaF2IBaF2 boundaries present. The boundary between the CaF2 and Baf2 layers is strained since both bulk BaF2 and CaF2 have different lattice parameters. This lattice mismatch must be overcome at the boundary if a hetero-structure is to be stable. It is assumed that the strain in the CaF2IBaF2 boundary is reduced via the formation of a number of stress relieving defects. Since fluorites conduct via a defect mechanism it is thought that the accumulation of defects at the interface causes the increase in conductivity seen in these hetero-structures. At present little is understood about the form of the boundaries and it is therefore difficult to draw strong conclusions regarding the cause of the increased conductivity in these systems when compared to bulk. By using pair potentials and DFT I find that the structure of the films is dictated by the need to maximise the coordination of ions within the film and to find an optimal interaction with the substrate. I find that large coverages form domains as opposed to forming uniform films. Additionally I see that a number of the F- ions are attracted away from the BaF2 substrate towards the CaF2 layer. These findings indicate that the structure of CaF2IBaF2 boundaries in CaF2IBaF2 hetero-films is not atomistically flat as previously assumed. Additionally the attraction of F: ions towards the Caf'2 layers indicates that BaF2/CaF2 boundaries may form space-charge zones which lend support to the possibility of charge transfer of F' ions from BaF2 layers to CaF2 layers. The second section focuses on the development of a method to study the radiation damage caused by alpha decay in pyrochlore systems via the analysis of molecular dynamics simulation results. The nature of radiation resistance in Gd2B207 pyrochlores varies with the nature of the B cation. Two pyrochlores, Gd2Ti207 and Gd2Zr207, differ remarkably in their resistance. Gd2Ti207 amorphises under irradiation whilst Gd2Zr207 generally retains its pyrochlore structure. Many experimental and theoretical studies have attempted to rationalise the difference in resistance between the two pyrochlores with little success. Our group have performed molecular dynamics simulations to study the effect of alpha decay on both pyrochlore systems. These systems are typically very large and difficult to analyse. Many traditional methods for studying damage in solids, such as radial distribution functions, cannot be applied successfully to pyrochlore systems. I have utilised Steinhardt's bond orientational order parameters to devise a method to study the two pyrochlore systems. The approach I have devised enables in depth study of the pyrochlore structure and can detect the relative quantity of damaged and undamaged material in the two pyrochlore systems. The proportion of damaged and undamaged material in the two pyrochlore systems enables us to draw conclusions regarding the radiation resistance of both materials. My studies lead me to conclude that the main difference in radiation resistance between the titanate and ziroconate systems is due to the nature of the oxygen mobility in both systems.

High target utilisation sputtering (HiTUS) is a patented remote plasma sputtering technique for the deposition of thin films. A prototype in-line sputter deposition facility, based on the existing standard HiTUS technology, has been developed. Materials deposited by both the standard HiTUS and the prototype in-line system where characterised. This was important in examining the key deliverable of the new system which is uniform deposition of high quality coatings on large (20 cm by 30 cm) substrates. Initially characterisation of the in-line system showed that fully reacted transparent alumina coatings using reactive sputtering could be deposited. The process was found to be reproducible, with a run-to-run variation in peak positions for UV-Vis-IR transmission spectra of less than = 1 %. The process conditions and system were investigated to optimise the system performance. Theoretical and experimental investigations showed that the RF plasma and magnetic field shape both affected the uniformity of coating thickness and optical transmission for reactive sputtering processes. Changes to the system configuration to improve the magnetic field shape based on these findings have increased the usable substrate width from 10 cm to approximate ly 20 cm. Investigating the heating effect of the plasma showed that doubling the RF plasma power (at constant target power) can increase the heat flux to the substrate by a factor of two. For the deposition of tin doped indium oxide (ITO) and aluminium- doped zinc oxide (AZO) increasing the RF plasma power was shown to (i) change the material from amorphous to nanocrystalline, (ii) increase the visible transmission of coatings and (iii) increase the conductivity of the material. These effects are attributed to the increased energy of the plasma species promoting both higher surface mobility and reactivity of adsorbed species.

This thesis contains three studies on artificially roughened multilayers, with the aim of investigating how the structural disorder affects the magnetic structure. The magnetically patterned system uses a Co/Pt multilayer, which exhibits strong perpendicular magnetic anisotropy, to magnetostatically imprint a domain pattern onto a 50 Ã… thick permalloy layer.

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This thesis is concerned with the characteristics of organic light-emitting devices based on the polymer poly(2֊methoxy֊5-(5'-ethyIhexyloxy)֊p֊phenylenevinylene) (MEH-PPV).The emissive layer of each device was formed either from pure MEH-PPV or from a blend of MEH-PPV with an electron-transporting small molecule material. A film of either indium tin oxide (ITO) or aluminium-doped zinc oxide (AZO) on glass was used to provide a transparent anode. The pure or blended emissive material was spin-coated from solution onto the anode. Calcium or aluminium cathodes were deposited by thermal evaporation onto the emissive film. The cutrent-voltage, light-voltage, quantum efficiency and stability characteristics of the devices were obtained using purpose-designed measurement equipment. These characteristics were influenced, amongst other factors, by the blend composition. The devices with an aluminium cathode and an emissive layer formed from 50 % MEH-PPV and 50 % PDPyDP had among the best characteristics. Compared with the equivalent unblended devices they averaged 40 times greater light emission, 35 times higher efficiency, and they emitted light for more than 18 days in place of tens of minutes. The half life of the most stable devices was 63 һ which, though much less than the tens of thousands of hours claimed by commercial developers, represents an increase of 30 times that of an unblended device. The increased light emission and quantum efficiency data resulted from the enhanced earner injection and transport provided by the electron transport material. It is suggested that the increased stability was caused by the small molecule material performing the role of a nano-encapsulation around each polymer chain. That is to say, the data suggest that each polymer chain was individually protected from the effects of contaminants such as oxygen and water vapour by the small molecule within the film .The choice of anode material also affected the rate of degradation. The surface morphology of the anode material of devices which had previously been operated for extended periods were analysed using an AFM. Electromigration of ITO anodes to form sharp spikes was not uncommon, particularly in devices with short lifetimes. As-deposited AΖO generally had a smoother morphology than as-deposited ITO. Following device operation fewer electromigtation spikes were observed in AZO than ITO.

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