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Polymer-fullerene blend films are of increasing interest in the field of organic solar cells. This thesis describes the use of transient absorption spectroscopy (TAS) as a means to study charge generation and recombination in these blend films. In blend films of P3HT and PCBM, the absorption spectrum associated with the positive and negative charges have been identified and the transient decay kinetics analysed to reveal the mechanisms leading to charge recombination losses in the films. The effects of annealing treatment, along with the effects of decreasing polymer regioregularity or different polymer chain terminating end-groups on the blend film properties and morphology are also discussed. For films with a low concentration of PCBM in polystyrene, absorption and emission from the individual PCBM molecules are observed. As the PCBM concentration is increased, aggregation related changes causes the absorption in the visible region to increase disproportionately, an additional emission peak at higher energies to appear and a decrease in the lifetime of the PCBM triplet excited state. These changes are linked to electronic interactions between fullerenes in a molecular crystal form of PCBM. Blends of F8BT polymer with PCBM show poor photovoltaic device performance. This is explained by the quick deactivation of the F8BT excited state by Förster energy transfer to the PCBM. As the PCBM excited state is stable compared to the charge separated state, the PCBM triplet is formed via inter-system crossing from the singlet to be the final product of photoexcitation. The high energy of the charge separated state is interpreted as a result of the high F8BT HOMO energy.

This thesis presents the design and analysis of photo-electro catalytic oxidation technology for its potential use in water treatment applications. Doping titanium dioxide can effectively improve oxidative reactions. Using minute reactor design adjustments, such as electrolysis, the bases of degrading soluble organic compounds can be improved within the reactor. Applications of doping and secondary catalysis are effective in increasing the process of photoactivity within the catalytic reactor, theoretically increasing the production of sacrificial electron acceptors. Higher degradation's were accomplished using doped chromium titanium dioxide photocatalyst, which degraded significantly larger amounts of organics compared with pure titanium dioxide. Techniques used to accomplish the increased photo-reactivity were doping chromium (III) ion into titanium dioxide crystal lattices and silver ions into the photocatalytic coat. Degradation curves were determined by total organic carbon and the chemical oxygen demand. Calculations of the final rate constants show that lighter molar concentrations have higher rates of degradation.

Pour se protéger des fortes illuminations, les cyanobactéries ont développé un mécanisme de photo-protection nommé qEcya. Sous forte lumière, il diminue la formation d'espèces dérivées de l'oxygène très réactives et dangereuses, en augmentant la dissipation de l'énergie absorbée sous forme de chaleur. L'énergie provenant des phycobilisomes (PBS, les antennes externes des cyanobactéries) atteignant les centres réactionnels est ainsi diminuée. Le mécanisme est induit par l'absorption de la lumière bleue-verte par une protéine photoactive soluble qui attache un caroténoïde : l'Orange Carotenoïd Protein (OCP). Le processus est accompagné d'une diminution de fluorescence réversible. Dans une étude sur les mécanismes de photo-protection sous carence en fer, nous avons montré que le large quenching de fluorescence induit par la lumière bleue-verte est associé à l'OCP et au mécanisme qEcya. Et qu'il n'est pas associé à la protéine IsiA induite sous carence en fer comme cela avait été suggéré dans le passé. Ensuite, j'ai montré que l'OCP et son mécanisme de photo-protection associé sont répandus chez les cyanobactéries à phycobilisomes. Alors que les cyanobactéries contenant l'OCP augmentent leur dissipation d'énergie au niveau des phycobilisomes pour diminuer l'énergie arrivant aux centres réactionnels, il est apparu que les quelques cyanobactéries ne contenant pas l'OCP ont développé une autre stratégie basée sur la dégradation rapide de leurs phycobilisomes en condition de stress. Des résultats préliminaires sur les interactions OCP-PBS sont aussi décrits dans ce travail. Des PBS incubés en présence de l'OCP ont été co-isolés en complexes OCP-PBS dans un gradient de saccharose, même quand seulement des cœurs de PBS ont été mis en présence de l'OCP. Ces résultats suggèrent fortement que l'OCP et les PBS interagissent. Cependant le mécanisme qEcya n'a pas pu être induit in vitro sur ces complexes OCP-PBS purifiés. Le résultat principal de cette thèse est la découverte d'un nouvel acteur essentiel au mécanisme qEcya: une protéine de 13kDa fortement attachée à la membrane. Nous l'avons nommée la Fluorescence Recovery Protein, FRP, car elle est impliquée dans la récupération de l'émission de fluorescence des phycobilisomes dans le mécanisme qEcya après une forte illumination de lumière bleue-verte. La caractérisation de son gène, slr1964, a montré qu'il est conservé en aval du gène de l'OCP chez les cyanobactéries, et qu'il peut être transcrit indépendamment ou co-transcrit avec le gène de l'OCP. De plus, notre étude suggère fortement que l'OCP et la FRP interagissent.

In this thesis, novel technology for manufacturing high-performance hydrogenated amorphous silicon (a-Si:H) TFT is developed . In the bottom gate light-shied a-Si:H TFT structure, the side edge of a-Si:H island is capped with extra deposition of heavily phosphorous-doped a-Si layer. The new structure a-Si:H TFT process steps is almost unchanged. The masksteops of fabrication new structure TFT are the same as the inverter-staggered TFT. Such an ingenuity can effectively eliminate the leakage path between the parasitic contacts between source/drain metal and a-Si:H at the edge of a-Si:H island. a-Si:H is a well-known photosensitivity material. For driving LCD the TFT must be operated with illuminated environment. It will cause the leakage current. The new TFT structure is similar to the light-shield TFT proposed by Akiyama in 1989. So the new structure TFT can not only reduce the schoktty emission leakage current but also the photo-leakage current. In addition, electrical performance of the novel a-Si:H TFT device exhibits superior effective carrier mobility, as high as 1.05 cm2/Vsec due to the enormous improvement in parasitic resistance. The impressively high performance provides the potential of our proposed a-Si:H TFT to apply for AMLCD and AMOLED technology.

Currently , the STN-LCD with twist angle of 240 degree is the most popular operation mode . In this thesis , we utilize Photo-Sensitive spacer of TFT-LCD to substitute for the traditional spacer , and apply them in the above mentioned STN-LCD . The traditional spacer were used N2 air to spray on glass substrate by SUS tube . It make light leakage , decrease the transmittance , contrast ratio and aggregate spacer easily . When we pressure on glass and the phenomenon of migration has been found accordingly . It will influence quality of LCD . So we utilize Photo-Sensitive spacer to substitute for the traditional spacer in order to improve the defect . In this thesis , we fabricate different kind Photo-Sensitive spacer of size , shape and area ratio (Photo-Resist (NPS) from Everlight Chemical Industrial Corp) . We utilize Photo Lithography process to form the spacer thickness on insulation layer , and find the best type . In this experiment , the different characteristic of material between traditional spacer and Photo-Spacer were compared . And we utilize different process condition (pressure) and material(LC £Gnd) to discuss the relation . Finally , we proof the advantage of Photo-Spacer apply in STN-LCD .

In this thesis , we studied the photo-chemistry between the green emitter (C545T) and the photo-acid generator (PAG) . When the sample of C545T and PAG in solutions and thin films were exposured to UV-light , we found that a new product was produced due to protonation of C545T with the acid generated by PAG . Therefore , we measured absorption and fluorescence spectra of the samples in solutions (THF) and in polymer (PMMA) thin films . The different concentrations of C545T dopanted photo-acid generator in the solvent (THF) could increase the photo-acid generator at higher concentrations of PAG , the energy could be transferred from unprotonated to protonated . Therefore , we can easily observe the absorption and fluorescence spectra have been changed and the phenomenon of stock¡¦s shift has been found accordingly . At higher concentrations of C545T in solutions , also called concentrations quenching effect was observed because C545T molecules could collide each other easily that causes intensity to decrease in the solvent (THF) . In order to get rid of the collision effect , we use the samples of polymer thin films instead of solutions . The different of the change of spectra between solutions and thin films were observed and compared were also studied .

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