Orientador: Lucas Fugikawa Santos / Banca: Marcelo Andres Fossey / Banca: Dante Luis Chinaglia / Resumo: Esta dissertação de mestrado apresenta um estudo sobre as propriedades de foto-geração de portadores de carga e sua condução em dispositivos optoeletrônicos orgânicos construídos em estruturas de diodo tipo sanduíche - ITO/Polímero/Metal - sendo empregados como sua camada ativa dois polímeros orgânicos conjugados distintos, o poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene) ou MDMO-PPV, e o copolímero fenil substituído do poli(p-fenileno vinileno) conhecido como Super Yellow® ou SY-PPV. As características da foto-geração e de transporte de cargas dos dispositivos foram determinada através da análise de medidas de corrente-tensão (I-V) em regime d.c., e de espectroscopia de impedância/capacitância no regime da frequência (1Hz-1MHz). As propriedades elétricas dos dispositivos foram estudadas com os dispositivos iluminados em diferentes faixas de comprimentos de onda na região do visível, a diferentes intensidades, e comparadas com as propriedades dos dispositivos no escuro. Para iluminação através do eletrodo transparente (ITO), tanto um efeito fotovoltaico quanto fotocondutivo foram claramente observados. Em particular, o efeito da foto-geração no espectro de capacitância em função da frequência foi estudado em maiores detalhes. Um modelo semiempírico, levando em conta as distribuições de cargas espaciais devidas à foto-geração de portadores de carga e propriedades de transporte como, por exemplo... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This dissertation presents a study on the properties of photo-generation and conduction of charge carriers in organic optoelectronic devices built in sandwich diode structures - ITO/Polymer/Metal - with the active layer comprised by two different organic conjugated polymers: poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene) MDMO-PPV, and a phenyl-substituted copolymer of poly(p-phenylene vinylene) known as Super Yellow®, SY-PPV. The photo-generation and charge transport properties have been determined from the analysis of current-voltage (I-V) measurements in the d.c. regime and impedance/capacitance spectroscopy in the regime of frequency (1Hz-1MHz). The electrical properties of the devices were studied with the devices under illumination, in different ranges of wavelength in the visible region, at different intensities and compared with the properties of devices in the dark. By illuminating the devices through the transparent electrode (ITO), both photovoltaic and photoconductive effects were clearly observed. Particularly, the photo-generation effect in the frequency-dependent capacitance spectrum was studied in detail. A semiempirical model taking into account the spatial distribution of charges due the photo-generation and material properties... (Complete abstract click electronic access below) / Mestre

The study shows strong influence of the conformation of the main chains of polythiophenes in solutions on their spectroscopic properties. The conformational changes affect strength of interactions between neighboring chains and lead to the formation of aggregates of stacked polythiophene chains. Stacked chains show red shift of the optical absorption and lead to visible vibronic structure of absorption bands. Multilayered systems prepared by periodic adsorption of the cationic and anionic polythiophene polyelectrolytes on various substrates show proportionality of the overall layer thickness to the number of coatings, which allows a control of the layer thickness. Adsorption of the conjugated polyelectrolytes on the anatase form of titanium dioxide show better penetration of the anionic polythiophene to porous anatase. The adsorption of polymer into the mesoporous structure is not complete: maximum adsorption of PTTA (poly(thiophene-3-ylacetic acid)) adsorbed on anatase do not correspond to the inner surface of mesoporous anatase. Alternating adsorption from the solutions of polythiophene with anionic and cationic side groups on mesoporous anatase allows preparation of the Graetzel-like photovoltaic cell provided that the adsorption process starts with the anionic polythiophene and the layers are deposited...

Ever since their discovery, Carbon nanotubes (CNTs) have been renowned to be potential candidates for a variety of applications. Nevertheless, the difficulties accompanied with their dispersion and poor solubility in various solvents have hindered CNTs potential applications. As a result, studies have been developed to address the dispersion problem. The solution is in modifying the surfaces of the nanotubes covalently or non-covalently with a desired dispersant. Various materials have been employed for this purpose out of which polymers are the most common. Non-covalent functionalization of CNTs via polymer wrapping represents an attractive method to obtain a stable and homogenous CNTs dispersion. This method is able to change the surface properties of the nanotubes without destroying their intrinsic structure and preserving their properties. This thesis explores and studies the surface modification and solublization of pristine single and multiwalled carbon nanotubes via a simple solution mixing technique through non-covalent interactions of CNTs with various anionic and cationic conjugated polyelectrolytes (CPEs). The work includes studying the interaction of various poly(phenylene ethynylene) electrolytes with MWCNTs and an imidazolium functionalized poly(3-hexylthiophene) with SWCNTs. Our work here focuses on the noncovalent modifications of carbon nanotubes using novel CPEs in order to use these resulting CPE/CNT complexes in various applications. Upon modifying the CNTs with the CPEs, the resulting CPE/CNT complex has been proven to be easily dispersed in various organic and aqueous solution with excellent homogeneity and stability for several months. This complex was then used as a nanofiller and was dispersed in another polymer matrix (poly(methyl methacrylate), PMMA). The PMMA/CPE/CNT composite materials were cast or electrospun depending on their desired application. The presence of the CPE modified CNTs in the polymer matrix has been proven to enhance the composites thermal, mechanical and electrical properties compared to pristine CNTs. Various spectroscopic and microscopic techniques such as UV-vis, fluorescence, TEM, AFM and SEM were used to study and characterize the CPE/CNT complexes. Also, TGA, DSC and DMA were used to study the thermal and mechanical properties of the composite materials. Our current work represents a fundamental study on the non-covalent interactions between CNTs and CPEs on one hand and gives a real life example on the CPE/CNT application in composite materials and electronics.

This thesis targets the development of conjugated polymers with improved process ability from solutions. Two types of ionic polymers are addressed: (i) conjugated metallo-supramolecular polymers (MSPs) composed of conjugated heteroaromatic unimers (building blocks) linked to chains by various metal ions giving charged main chains, and (ii) polythiophene polyelectrolytes containing ionic pendants. Processing advantages of conjugated polyelectrolytes consist in the possibility of their processing from solutions in green solvents such as alcohols or even water. The advantages of MSPs consist in the thermodynamic control of the degree of polymerization (length) of their chains in solutions by the choice of solvent and temperature. As a result, MSPs reversibly provide systems of low viscosity that can be processed from solutions more easily than high-molar-mass polymers giving highly viscous solutions. Synthesis of appropriately designed unimer(s) is the key step of preparation of an MSP. Within this thesis, a series of novel unimers composed of linear oligothiophene type (mono-, bi-, ter- a thieno-thiophene- diyl) central blocks capped with 2,6-bis(oxazoline-2-yl)pyridine (pybox) or 2,6-bis(imidazole-2-...

Alzheimer's disease is a widespread disease that has devastating effects on the human brain and mind. Ultimately, it leads to death and there are currently no treatment methods available that can stop the disease progression. The mechanisms involved behind the disease are not fully understood although it is known that amyloid fibrils play an important role in the disease development. These fibrils are able to form plaques that can trigger neuronal death, by interacting with receptors on the cell surface and the synaptic cleft or by entering the cell and disturb important functions such as metabolic pathways. To study the plaque formation of amyloid proteins, both in vitro and in vivo methods are used to investigate the characteristics of the protein. Luminescent conjugated oligothiophene probes are able to bind in to amyloid beta fibrils and emit light when excited by an external light source. This way fibrillation properties of the protein can be studied. Developing probes that can serve as biomarkers for detection of amyloid fibrils could change the way Alzheimer's is treated. Being able to detect the disease in its early disease course, and start treatments early, is suggested to stop the progression of neural breakdown. In this project a software is developed to analyze fluorescent microscopy images, taken on tissue stained with these probes. The software is able to filter out background noise and capture parts of the picture that are of interest when studying the amyloid plaques. This software generates results similar to if the images were to be analyzed using any software where the regions to analyze are selected manually, suggesting that the software developed produce reliable results unbiased by background noise.

<p>  </p> <p>Organic semiconductors have been considered a promising candidate to replace Silicon-based inorganic semiconductors in our electronics due to their lightweight, high flexibility, and solution processability. Recently, conjugated polymers were shown to be functional at up to 200°C, expanding organic semiconductors application territory into high-temperature electronics, which sorely depends on wide-bandgap semiconductors. To push the operational temperature boundary of polymer transistors even further than 200°C, our understanding of temperature impacts on the materials and charge transport mechanism in such harsh conditions needs to be improved. Here, we study the high temperature effect on polymer transistors from two main directions: via molecular design and via device engineering. First, via sidechain design, we explored the impact of close π-π packing on the thermal stability of semiconducting polymers. We discovered that maintaining close π-π packing can lead to lower chain distortion, thus improving the polymer transistors' operational stability at high temperatures. Then we study the impact from device factor, specifically contact resistance in device behavior at extreme conditions. We found that the contact area is more susceptible to high temperatures than other regions in the channels and is the main reason for the degraded performance. We then propose a facile method to minimize the contact problem, to achieve stable devices at above 200°C. And last, we proposed a simple method to attain quasi-temperature independent charge transport in polymer transistors from room temperature to 140°C by simply applying a prolonged bias gate voltage before heating. This research expands our knowledge on charge transport in conjugated polymers at high temperatures and provides a guide to make conjugated polymer transistors for extreme conditions in the future.</p>

The re-emergence of interest in organic semiconducting small molecules and polymers during past several decades can be attributed to their advantage of utility, flexibility, ease of access, and turnability over silicon based inorganic semiconductors. The library of organic semiconductors containing p-type (hole conducting) and n-type (electron conducting) materials have grown in numbers and efficiency. The p-type semiconducting materials hold an advantage over n-type materials owing to their stability and ease of synthesis. The widespread use of fullerenes (C60 and C70) as n-type materials in organic photovoltaics OPVs and their known downsides of poor absorption in visible and NIR region and limited charge carrier transport have triggered the development of non-fullerene based electron accepting (NFEA) materials . By taking advantage of the electron accepting behavior of cyclopenta[hi]aceanthrylene fragment of C70, we have synthesized a new class of cyclopentafused polyaromatic hydrocarbons (CP-PAHs). These new contorted CP-PAHs have been prepared utilizing the modified version of our previously developed palladium catalyzed cyclopentannulation strategy. The target molecules broaden the scope of annulation chemistry to 1,2-bis(5-hexylthiophen-3-yl)ethyne with aryl dibromo derivatives of anthracene, pyrene and perylene to yield 4,4',4'',4'''-(cyclopenta[hi]aceanthrylene-1,2,6,7-tetrayl)tetrakis(2-hexylthiophene), 4,4',4'',4'''-(dicyclopenta[cd,jk]pyrene-1,2,6,7-tetrayl)tetrakis(2-hexylthiophene) and 1,2,7,8-tetrakis(5-hexylthiophen-3-yl)-1,2,7,8-tetrahydrodicyclopenta[cd,lm]perylene. Scholl cyclodehydrogenation of the cyclopentafused thiophene units with suitably substituted hydrocarbons chains provided access to p-extended polyaromatic systems including 2,5,11,14-tetrahexylrubiceno[5,4-b:6,7-b':12,11-b'':13,14-b''']tetrathiophene, 2,5,11,14-tetrahexyldithieno-[4,5:6,7]indeno[1,2,3-cd]dithieno[4,5:6,7]indeno-[1,2,3-jk]pyrene, and 2,9,12,19-tetrahexyldithieno[4,5:6,7]indaceno[1,2,3-cd]dithieno[4,5:6,7]indaceno[1,2,3-lm]perylene. The fully conjugated p-electronic core of these small molecules provide low optical band gaps, decent mobilities and broad absorption. The HOMO and LUMO energies of these CP-PAHs were found to be in the range of -5.48 to -5.05 eV and -3.48 to -3.14 eV, respectively. Besides showing broad band absorption features, some derivative were found to operate as a p-type semiconductor when tested in organic field effect transistors. Anthradithiophene (ADT) is an isoelectronic analogue of pentacene and became a point of interest. A soluble, and functionalizable ADT derivative, 5,11-dibromoanthradithiophene was prepared and then polymerized utilizing Stille, Sonogashira and Yamamoto cross coupling strategies. The newly developed ADT polymers were found to operate in p-type regime when tested in organic field effect transistors. To explore the effects of solvent on growing polymer chains in step-growth polymerizations, we developed a library of Yamamoto and Glaser polymers. The hypothesis tested was that growing polymer chains can recruit further monomer units to create block character in the growing polymer chains. Our investigations reveals that the solvent conditions altering the polarity of the reaction mixture can cause up to 40% preference of blockiness in the growing polymer chains.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18290号 / 工博第3882号 / 新制||工||1596(附属図書館) / 31148 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 秋吉 一成, 教授 澤本 光男, 教授 松原 誠二郎 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18295号 / 工博第3887号 / 新制||工||1596(附属図書館) / 31153 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 中條 善樹, 教授 赤木 和夫, 教授 辻 康之 / 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18297号 / 工博第3889号 / 新制||工||1597(附属図書館) / 31155 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 赤木 和夫, 教授 山子 茂, 教授 秋吉 一成 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM