For its inherent advantages, such as lightweight, low cost, flexibility, and opportunity to cover large surface areas, organic solar cells have attracted more and more attention in both academia and industry. However, the efficiency of organic solar cell is still much lower than silicon solar cells, but steadily rising as it now stands above 8%. The architecture of bulk heterojunction solar cells can improve the performance of organic solar cell a lot, but these improvements are highly dependent on the morphology of photoactive layer. Therefore, by controlling the morphology of photoactive layer, most commonly composed of a P3HT donor polymer and PCBM small molecule, the performance of organic solar cells could be optimized. The use of solvent additives in the solution formulation is particularly interesting, because it is a low cost method of controlling the phase separation of the photoactive layer and possibly removing the need for subsequent thermal and solvent vapor annealing. However, the role of the solvent additive remains not well understood and much debate remains on the mechanisms by which it impacts phase separation. In the first part of this thesis, we investigate the role of the solvent additive on the individual components (solvent, donor and acceptor) of the solution and the photoactive layer both in the bulk solution, during solution-processing and in the post-processing solid state of the film. In the second part of this thesis, we investigate the role of the additive on the blended solution state and resulting thin film phase separation. Finally, we propose a new method of controlling phase separation based on the insight into the role of the solvent additive. In the first part, we used an additive [octandiethiol (OT)] in the solvent to help the aggregation of P3HT in the solution. From the UV-vis experiments, the crystallinity of P3HT in the solutions increased while it decreased in thin films with steady increase of additive concentration. This method could be used for one step, annealing-free fabrication of organic solar cell with high performance. The solution can potentially be used to prepare ink for the large scale roll-to-roll ink-jet printing of P3HT thin films. Secondly, from the experiments it is found that differences in the evaporation rate and solubility of the components of the photoactive layer may be part of the reason for morphological changes. With lower evaporation rate than the host solvent, the additive concentration in the solution keeps increasing with time during the final stages of spin coating. In addition, the phase separation is increased with the increase of additive concentration, as demonstrated by AFM and TEM. By controlling the additive concentration, it is possible to control the phase separation of photoactive layer in pristine device. It is also found that the additive can change the wetting ability of the solvent to produce films with high surface coverage. With this information in hand, we modified the solution process of BHJ layers. A layer of crystals was deposited from the OT-containing solution by postponing the start of the spin coating for several minutes (delay time) after the solution is dropped on the surface of substrate. We found this to be a very effective method of increasing the phase separation and crystallinity of the photoactive materials. This effect was not possible when using oDCB solvent without any additive.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18949号 / 工博第3991号 / 新制||工||1615(附属図書館) / 31900 / 京都大学大学院工学研究科材料化学専攻 / (主査)教授 木村 俊作, 教授 瀧川 敏算, 教授 秋吉 一成 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20001号 / 工博第4245号 / 新制||工||1657(附属図書館) / 33097 / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 作花 哲夫, 教授 安部 武志, 教授 邑瀬 邦明 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

Metal oxide nanoparticles constitute an important class of nanomaterials which has have received tremendous attention due to their distinct, specific activities comparison to their bulk. Among these, cerium oxide nanoparticles (CeNPs) have displayed outstanding promise across a wide range of applications owing to their unique redox properties. Given that the physical and chemical characteristics of nanomaterials are significantly influenced by their morphologies and sizes, the development of well-controlled synthesis methods for CeNPs holds great importance in both scientific research and industrial applications. This dissertation seeks to peer into the formation of CeNPs in solution through wet chemical synthesis. Additionally, antioxidant properties of CeNPs were examined to explore the potential use of facet CeNPs in gene delivery and promoting wound healing for diabetic. The beginning of this work provides introduction and summary of some common concepts widely used in understanding of nanoparticles formation. In chapter two and three, the spontaneous hydrolysis behavior of tetravalent cerium salts in aqueous systems were studied in detail to understand the influence of synthesis condition on the nucleation kinetic and morphology evolution in the course of growth of nanoparticle. The results obtained from these studies offer constructive insights into designing a straightforward and controlled synthesis strategy for producing nanoclusters and faceted nanoparticles through wet chemical methods. Furthermore, in chapter five, we examine the impact of faceted CeNPs on biomolecule conjugation and their performance in gene delivery for the regulation of abnormal diabetic wound healing. Overall, by taking advantage of the intrinsic properties of tetravalence cerium salt, this work highlights how manipulation of spontaneous hydrolysis could lead to formation of particles with different nanostructure and physicochemical properties.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23726号 / 理博第4816号 / 新制||理||1689(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 杉山 弘, 教授 深井 周也, 教授 秋山 芳展 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19959号 / 理博第4226号 / 新制||理||1607(附属図書館) / 33055 / 京都大学大学院理学研究科化学専攻 / (主査)教授 寺西 利治, 教授 倉田 博基, 教授 島川 祐一 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

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De nombreuses transformations de solides en solution, polymorphiques ou non, en industrie minérale ou pharmaceutique, se déroulent par la dissolution d'un premier solide en vue de la cristallisation du second. Au lieu de la voie traditionnelle de séchage, la transformation du gypse (sulfate de calcium dihydrate) en alpha-bassanite (sulfate de calcium hémihydrate) peut s’effectuer en solution aqueuse : en augmentant suffisamment la température, le gypse devient plus soluble dans l'eau que l’hémihydrate, qui a alors la possibilité de cristalliser. Un appareillage et un mode opératoire originaux ont été conçus pour investiguer la sensibilité de la cinétique de la transformation et des caractéristiques des cristaux d’hémihydrate obtenus à ces conditions opératoires. En effet, cette voie de dissolution-recristallisation permet le contrôle du facteur d'aspect des cristaux d’hémihydrate, voire celui de leur taille moyenne et de leur dispersion de taille, par le choix de ses conditions physico-chimiques : température, pH, utilisation d’additifs, et ensemencement de la solution avec des particules d’hémihydrate appropriées. Les techniques d'analyse images sont développées afin d'identifier le rapport d'aspect des particules. Un modèle cinétique prenant en compte la dissolution du gypse, la nucléation et la croissance du sulfate de calcium hémihydrate, les équilibres en phase aqueuse et de solubilité, a été élaboré, et ses équations résolues avec le logiciel MATLAB. Couplée à une méthode numérique d'optimisation, cette résolution sous MATLAB permet d'examiner la validité des hypothèses sur les processus retenus et d'identifier leurs paramètres cinétiques. / In mineral or pharmaceutical industry, many transformations of solids in solution (polymorphic or not), take place by the dissolution of the first solid and the crystallization of the second solid. Instead of the traditional drying process, the conversion of gypsum (calcium sulfate dihydrate) to alpha-bassanite (calcium sulphate hemihydrate) can be carried out in aqueous solution by increasing the temperature sufficiently. At this moment, the gypsum becomes more soluble in water than the hemihydrate, which then has the possibility to crystallize. An apparatus and an original procedure have been designed to investigate the sensitivity of the kinetics of transformation and the characteristics of the hemihydrate crystals obtained under its operating conditions. In fact, this dissolution-recrystallization route allows to control the aspect ratio of the hemihydrate crystals, and even their average size and size dispersion, by the choice of its physicochemical conditions such as temperature, pH, use of additives, and seeding the solution with the appropriate hemihydrate particles. Image analysis techniques are developed to identify the aspect ratio of the particles.A kinetic model taking into account the dissolution of gypsum, the nucleation and the growth of calcium sulphate hemihydrate and their equilibrium in aqueous phase and solubility had been developed and the equations of this model are solved with the help of MATLAB software. Coupled with a numerical optimization method, this resolution under MATLAB makes it possible to examine the validity of the assumptions on the selected processes and to identify their kinetic parameters.

Dans le cadre de ce travail, des composés de formulation Ce1−xFexO2−x2 ont été synthétisésà l’aide de deux protocoles : co-précipitation et synthèse assistée par chauffage micro-ondes.L’utilisation de cette dernière a ainsi conduit à l’obtention de nanoparticules de morphologiescubiques ou « bâtonnets » et ceci pour des temps de synthèse relativement courts. L’analysepar diffraction X a montré notamment que le paramètre de maille diminue en fonction de lateneur en fer, x. L’environnement local et le degré d’oxydation du fer ont été analysés parspectroscopies Mössbauer, RPE et XANES mettant ainsi en évidence la présence d’ions Fe3+isolés au sein de sites octaédriques distordus et sous forme de clusters. Une comparaison entreles deux voies de synthèse a montré que des différences apparaissent à l’échelle locale. Lessolutions solides obtenues ont ensuite été caractérisées au cours du traitement thermique etsous différentes atmosphères. Indépendamment de l’atmosphère de recuit, une démixtion dela solution solide intervient pour des températures proches de 600°C. / This work deals with the synthesis and characterization of Ce1−xFexO2−x2 nanoparticles.Two different synthesis routes were used : the coprecipitation technique and the microwaveassisted synthesis route. This later allowed the obtention of controled morphologies such asnanocubic or nanorod particles, characterized by HRTEM. Compared to hydrothermal synthesisroute the time of reaction was limited to one hour. X-Ray Diffraction analysis showedthat the lattice parameter decreases versus the iron content. Local environment and oxidationstate of iron were analyzed by Mössbauer, EPR and XANES spectroscopies showingthe presence of two kinds of iron sites : isolated (distorted) octahedral sites and clusters. Acomparison between both synthesis routes shows clearly the differences at a local scale. Thenanoparticles were then further characterized during annealing and under different atmospheres.The solid solution undergoes a demixtion phenomenon around 600°C which does notdepend on the atmosphere conditions.

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