Depuis quelques années, les matériaux luminescents mécanochromiques présentant un changement réversible de leur longueur d'onde d'émission en réponse à un stimulus mécanique externe, suscitent un grand intérêt en raison de leurs applications potentielles pour les mémoires optiques ou les capteurs de pression par exemple. En effet, au cours des cinq dernières années, le nombre de composés luminescents sensibles à la pression rapportés dans la littérature a explosé avec des exemples basés principalement sur des molécules organiques. Comparativement, l’étude de complexes de métaux de transition reste relativement limitée et sont majoritairement des complexes d'or et de platine. Les travaux de recherches menés concernent l’étude des propriétés de mécanochromisme de luminescence de clusters moléculaires d'iodure de cuivre. Après broyage mécanique, leurs propriétés de photoémission sont grandement modifiées. De plus, ces composés ont la particularité de présenter à la fois des propriétés de mécanochromisme et de thermochromisme de luminescence. / In the last years, mechanochromic luminescent materials which exhibit reversible modification of the emission wavelength in response to external mechanical stimuli have attracted great attention because of their potential applications in optical memory devices, pressure sensing systems, for instance. Indeed, due to their promising development, the number of reported pressure sensitive luminescent compounds has exploded in the five last years with examples based mainly on organic dyes. Examples of transition-metal complexes are comparatively limited and essentially based on gold and platinum metals. The developed research concern the study of the mechanochromic luminescent properties of molecular copper iodide clusters. Upon mechanical grinding, their photoemission properties are greatly modified. These compounds have the particularity of exhibiting both mechanochromic and thermochromic luminescence properties.

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Photocontrol, the use of light-sensitive proteins to control events within living tissue, allows complex processes in higher organisms to be studied. The Halorhodospira halophila photoactive yellow protein (PYP) can be used to regulate transcription factor activity with blue light. Before any PYP-based system can probe complex processes in higher organisms, proof of functional expression in vivo is required. We linked d25 PYP to the C-terminus of blue fluorescent protein (BFP) and expressed variants of the fusion protein (BFPd25PYP) in E. coli and human embryonic kidney (HEK293) cells. Expression of BFPd25PYP in E. coli verified in vitro photoswitching. The fusion protein was successfully expressed in HEK293. Fluorescence studies of intact cells indicated chromophore uptake and incorporation into PYP in HEK293, while photoswitching of PYP was measured in protein isolated from HEK293. These findings are promising for the development of applications using PYP for in vivo mammalian photocontrol of biological events.

Photocontrol, the use of light-sensitive proteins to control events within living tissue, allows complex processes in higher organisms to be studied. The Halorhodospira halophila photoactive yellow protein (PYP) can be used to regulate transcription factor activity with blue light. Before any PYP-based system can probe complex processes in higher organisms, proof of functional expression in vivo is required. We linked d25 PYP to the C-terminus of blue fluorescent protein (BFP) and expressed variants of the fusion protein (BFPd25PYP) in E. coli and human embryonic kidney (HEK293) cells. Expression of BFPd25PYP in E. coli verified in vitro photoswitching. The fusion protein was successfully expressed in HEK293. Fluorescence studies of intact cells indicated chromophore uptake and incorporation into PYP in HEK293, while photoswitching of PYP was measured in protein isolated from HEK293. These findings are promising for the development of applications using PYP for in vivo mammalian photocontrol of biological events.

Polyoxoniobates (PONbs) are a small family of highly electron-rich clusters. The development of new solids composed of these clusters have applications in green energy and electronics. However, the high charge environment of PONbs typically requires alkaline synthetic conditions that are unsuitable for introducing other metals and organic molecules, making synthesis of new systems difficult. To date, very few transition metals and organic ligands have been incorporated into these PONb solids, and lanthanide metal inclusion, which generally improves photoconductivity due to longlived f-orbital excitations, has not yet been fully realized. Here, the synthesis of a new class of lanthanide niobate cluster [Ln4(H2O)8(SO4)5(NbO3)2]·3H2O; Ln= Dy, Tb under acidic conditions is reported. Structures were determined by crystallography and time-dependent density functional theory (TD-DFT) was used to provide insight into photo-induced electronic transitions. Supporting computational methods that are currently being developed for modeling these emerging cluster systems are described.

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(理学) / 甲第19521号 / 理博第4181号 / 新制||理||1600(附属図書館) / 32557 / 京都大学大学院理学研究科化学専攻 / (主査)教授 林 重彦, 教授 谷村 吉隆, 教授 松本 吉泰 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23720号 / 理博第4810号 / 新制||理||1688(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 寺嶋 正秀, 教授 林 重彦, 教授 渡邊 一也 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

Yes / The application of photoelectrochemical methods presents the researcher with a powerful set of versatile tools by which photoactive materials, such as semiconductor quantum dots, at conductive interfaces may be interrogated. While the range of photoelectrochemical techniques available is quite large, it is surprising that very few have found their way into common usage within the nanoparticle community. Here a number of photoelectrochemical techniques and the principles upon which they are based are introduced. A short discussion on the criticality of ensuring the nanoparticles are reliably anchored to the substrate is followed by an introduction to the basic set of equipment required in order to enable the investigator to undertake such experiments. Subsequently the four techniques of transient photocurrent response to square wave illumination, photocurrent spectroscopy, intensity modulated photocurrent spectroscopy (IMPS) and intensity modulated photovoltage spectroscopy (IMVS) are introduced. Finally, the information that can be acquired using such techniques is provided with emphasis being placed on a number of case studies exemplifying the application of photoelectrochemical techniques to nanoparticles at interfaces, in particular optically transparent electrodes.

Halorhodospira halophila photoactive yellow protein (PYP) is a promising candidate to act as a photoswitching domain in engineered proteins due to the structural changes that occur during its photocycle. Absorption of a photon of wavelength 446 nm triggers trans to cis isomerization of its 4-hydroxycinnamic acid chromophore leading to large structural perturbations in the protein, particularly in the N-terminus. In the dark, a slower cis to trans reisomerization of the chromophore restores the protein’s native fold. The fusion of proteins to PYP’s N-terminus may therefore enable photomodulation of the activity of the attached protein. To test this hypothesis, this thesis descibes genetically encoded photoswitchable DNA-binding proteins that were developed by fusing the prototypical leucine-zipper type DNA-binding protein GCN4 bZIP to the N-terminus of PYP. Five different fusion constructs of full length or truncated GCN4 bZIP and full length PYP as well as fusion constructs of full length GCN4 bZIP and N-terminally truncated PYP mutants were designed in a structure-based approach to determine if the dimerization and DNA binding activities could be controlled by the PYP photocycle. Extensive biophysical characterization of the fusion constructs in the dark and under blue light irradiation using electronic absorption, circular dichroism and fluorescence spectroscopic techniques were performed. As all the fusion proteins could complete photocycles, the DNA binding abilities of the dark and light-adapted states of the proteins were characterized using spectroscopic techniques as well as by the electrophoretic mobility shift assay. All the fusion constructs maintained DNA-binding abilities, however they each differed in their affinities and the extent to which they were activated by blue light irradiation. The reasons for these differences in DNA-binding abilities and photoactivation are explored. Using the results from the characterization of these constructs, proposals are also made to develop more robust genetically encoded photoactivatable DNA-binding proteins of the same type.