Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2017-10-25T13:48:38Z No. of bitstreams: 2 Tese - Antonio Carlos Chaves Ribeiro - 2017.pdf: 7554618 bytes, checksum: 07d4e319fd9dbc57989da70247e79800 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-10-25T13:49:10Z (GMT) No. of bitstreams: 2 Tese - Antonio Carlos Chaves Ribeiro - 2017.pdf: 7554618 bytes, checksum: 07d4e319fd9dbc57989da70247e79800 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-10-25T13:49:10Z (GMT). No. of bitstreams: 2 Tese - Antonio Carlos Chaves Ribeiro - 2017.pdf: 7554618 bytes, checksum: 07d4e319fd9dbc57989da70247e79800 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-07-31 / Nanostructures of diphenylalanine (FF) have been extensively studied and are quite varied. This work aims to obtain self-assembled structures of diphenylalanine, containing electroluminescent compounds, with distinct morphological and photophysical characteristics from those of the starting materials. This work also intent to describe the photophysical properties of the structures obtained, integrating the experimental information to the theoretical predictions of computational simulations. For this, FF were self-assembled having chromophores as additives and its photophysical properties determined by steady state fluorescence spectroscopy, time-resolved fluorescence spectroscopy and its morphology was studied by scanning electron microscopy. Experimental data were compared to the results of semi-empiric theoretical calculation performed by AM1 and ZINDO/S approaches. The resulting materials exhibit different time resolved and steady state fluorescence response from the starting materials and it is related to charge transfer complexes formation. On theoretical approach, dimers and trimers can be part of the early stages of self-assembling. This find is important because this type of arrangement can lead to more conductive materials, of industrial interest, when combined with luminescent materials, especially if considered for energy conversion devices. / Nanoestruturas de difenilalanina (FF) vêm sendo extensivamente estudadas e são bastante variadas. Este trabalho busca obter estruturas auto-organizadas de difenilalanina, contendo compostos eletroluminescentes, que apresentem características morfológicas e fotofísicas distintas daquelas apresentadas pelos materiais de partida. Busca também descrever as propriedades fotofísicas das estruturas obtidas, integrando informações experimentais a previsões teóricas obtidas por simulações computacionais. Amostras de FF foram autoorganizadas na presença de aditivos cromóforos e suas propriedades fotofísicas determinadas por espectroscopia de fluorescência fotoestacionária, espectroscopia com resolução temporal e morfologia caracterizada por microscopia eletrônica de varredura. Os dados experimentais foram comparados aos resultados obtidos por métodos computacionais semi-empíricos, em nível AM1 e ZINDO/S para validar as previsões. Os materiais combinados exibem espectros de fluorescência fotoestacionária e resolvida no tempo diferentes dos materiais de partida e é possível identificar a presença de transferentes de carga. Sob o aspecto teórico, dímeros e trímeros podem fazer parte dos estágios iniciais de auto-organização da FF. Esta constatação é importante pois este tipo de arranjo pode levar a materiais mais condutores, de interesse industrial, quando combinados com materiais luminescentes, principalmente se considerados para dispositivos de conversão energética.

As células eletroquímicas emissoras de luz são dispositivos eletroluminescentes cuja camada ativa é uma mistura de um material eletroluminescente e um eletrólito sólido a base de sais de metais alcalinos, geralmente lítio. A presença dos íons na camada ativa modificam o mecanismo de funcionamento das células quando comparadas ao diodos emissores de luz. Nas células, a concentração de íons nas interfaces eletródicas forma uma dupla camada elétrica que auxilia a injeção de cargas na camada ativa, por sua vez e na presença dos íons, o material eletroluminescente sofre dopagem se tornando condutor, os portadores injetados irão se encontrar numa região da camada ativa recombinando-se e emitindo luz. Compreender as interações dos diversos materiais que formam a camada ativa é fundamental para otimizar o desempenho do dispositivo. Neste trabalho estudamos a interação do ADS108GE, um polímero luminescente, e um eletrólito sólido a base de poli (óxido de etileno) (PEO) e LiCF3SO3 ou LiB(C2O4)2. O LiB(C2O4)2 foi sintetizado neste trabalho para estudar a viabilidade de se substituir o LiCF3SO3 que é o sal tipicamente utilizado nas células. Foram utilizadas técnicas de Análise Dinâmico-Mecânica (DMA), Espectroscopia Vibracional no Infravermelho (FTIR), Microscopia de Força Atômica (AFM), Difração de Raios-X (DRX), Microscopia Óptica de Varredura no Campo Próximo (IR-SNOM), Impedância Elétrica e Voltametria Cíclica. Os resultados de DMA em conjunto com DRX e AFM, permitiram estabelecer que o aumento da concentração de sal contribui para mudanças morfológicas que se relacionam com o aumento da fração de fase amorfa e independem do ânion, demonstrando que estes efeitos estão ligados à interação PEO-Lítio. Por outro lado, os espectros de FTIR e resultados de impedância elétrica mostram que o aumento da concentração de LiCF3SO3 gera agregação do sal diminuindo a condutividade, a mobilidade iônica e o número de portadores efetivos, enquanto para o LiB(C2O4)2 não se observa tal efeito. O IR-SNOM permitiu identificar nas misturas utilizadas como camada ativa que o ADS108GE forma estruturas globulares embebidas numa matriz de PEO. Do ponto de vista operacional, as células a base de LiB(C2O4)2 possuem uma eficiência maior do que as a base LiCF3SO3 e maior estabilidade. / Light-emitting electrochemical cells are electroluminescent devices whose active layer is a mixture of an electroluminescent material and a solid electrolyte based on alkaline salts, usually a lithium salt. The ions within thea ctive layer change the devices working mechanism when compared to light emitting diodes. In the cells, there is an ion build up at electrodic interfaces creating an electric double layer allowing charge injection in the active layer. The electroluminescent material is doped by these injected charges becoming conductive. These injected charges recombine emitting light. In order to optimize devices performance, it is fundamental to study materials interactions when mixed as an active layer. In this work, we studied the interactions between ADS108GE, a luminescent polymer, and a solid electrolyte based on polyethylene oxide and LiCF3SO3 or LiB(C2O4)2. LiB(C2O4)2 was prepared in this work to assess its feasibility as LiCF3SO3 substitution which is the typical choice. We used the following techniques in this work: Dynamical Mechanical Analysis (DMA), Infrared Vibration Spectroscopy (FTIR), Atomic Force Microscopy AFM), X-Ray Diffraction (XRD), Infrared Scanning Near-Field Optical Microscopy (IRSNOM), Electrical Impedance and Cyclic Voltammetry. From DMA, XRD and AFM results, it is possible to conclude that as we increase salt concentration, the active layer has morphological changes related to an increasing fraction of an amorphous phase. These effects are anion independent showing that PEO-Li interactions are the responsible ones. On the other hand, FITR and electrical impedance experiments show that increasing LiCF3SO3 concentration leads to salt aggregation decreasing conductivity, ionic mobility and the effective number of carriers, moreover, we do not see this effect with LiB(C2O4)2. IR-SNOM identified that ADS108GE were organized as globular structures embedded in a PEO matrix. The cells made with LiB(C2O4)2 were more efficient than those based on LiCF3SO3 and were even more stable.

The organic light-emitting diode (OLED) technology is emerging to be the future technology of choice for thin, flexible and efficient display and lighting panels and is a potential competitor for the existing flat panel display technologies, like liquid crystal display (LCD) and plasma display panel (PDP). OLEDs display is already making their way from both lab and industry research to display market and the pace of development of laboratory OLED design into a commercial product is very impressive. The OLED display offers several advantages over other display technologies, such as low power consumption, easy fabrication, high brightness & resolution, light weight, compact, flexible, wide viewing angle and fast response. However, OLED display is still in amateur stage in terms of their cost and lifetime. Despite of the abovementioned advantages of OLEDs, there still several issues that need to be addressed to explore the full potential of this display technology. The development of materials with high photoluminescence quantum yield (PLQY), thermal and electrochemical stability, packaging, and light extracting technology are some of the major issues. Among the emitting materials, the achievement of robust blue emitting material with high PLQY and color purity is still a challenge due to its intrinsic wide bandgap and complex device configuration. The work presented in this thesis is devoted to the development of robust blue emitting materials based on fluoranthene derivatives. Fluoranthene unit has been chosen due to its blue emission, high photoluminescence quantum yield, thermal and electrochemical stability. The thesis is organized in six chapters, and a brief discussion on the content of individual chapters is provided below. Chapter 1 provides a short description of evolution of display technology and history of OLEDs. The generation wise development of emitting materials for white OLED is concisely illustrated. The working principle, function of individual layer and factors governing external quantum efficiency of OLED device are elaborated. Finally, the important prerequisite properties of blue emitting materials for OLED application are outlined. Chapter 2 reports the design and synthesis of symmetrically and asymmetrically functionalized fluoranthene-based materials to address the issue of PL quenching in solid state, and subsequently for application in non-doped electoluminescent devices. A detailed experimental and theoretical study has been performed to understand the effect of symmetric and asymmetric functional groups on optical, thermal and electrochemical properties. The fluoranthene derivatives reported in this chapter exibited deep blue emission with high PLQY in both solution and solid state. The vacuum deposited non- doped OLED devices were fabricated and characterized utilizing these materials as emitting layer. Chapter 3 describes the rationale design of thermally stable fluoranthene derivatives as electron transport materials for OLEDs. The two derivatives investigated in this chapter comprised of two fluoranthene units linked by diphenylsulfane and dibenzothiophene linkage. The effect of rigidity provided by ring closure in molecular structure on the physical and charge transport properties has been investigated. Such materials are urgently demanded for better performance and durability of displays. In an extension to chapter 3, fluoranthene based dual functional materials possessing blue light emission and electron transport characteristics are described in Chapter 4. The application of these materials in bilayer blue OLED device successfully demonstrated. The development of such dual functional materials is an important step to not just simplify the OLED device architecture; but also has the potential to reduce the manufacturing and processing cost significantly. Chapter 5 reports the synthesis of the star-shaped fluoranthene-triazine based blue photoluminescent materials for solution processable OLEDs. The effect of chalcogen on the photophysical and electroluminescence properties has been investigated. The main advantage of such solution processable materials over small molecules is to overcome the power consuming vacuum thermal evaporation technique for deposition. Chapter 6 describes the design and synthesis of a new blue emitting material comprising of a donor moiety and an acceptor unit to observe thermally activated delayed fluorescence (TADF). However, photophysical studies did not show any sign of delayed fluorescence in this molecule. Nevertheless, a deep blue electroluminescence is achieved using a multilayer OLED device configuration.

Ce travail porte sur la conception de nouveaux composés π-conjugués, potentiellement utilisable en électronique organique en tant que matériaux actifs dans des dispositifs tels que les OLEDs, les cellules photovoltaïques et les capteurs optiques. Dans ce but, nous avons exploité le motif silacyclopentadiène appelé également silole, possédant un bon rendement quantique de fluorescence à l'état solide et une excellente conduction des électrons. Dans un premier temps, l'introduction de groupements structurants (triptycène, stilbènes..) sur le silacyclopentadiène a permis de moduler l'arrangement moléculaire dans la couche active et par conséquent, les propriétés d'électroluminescence. Des diodes possédant des performances très encourageantes furent ainsi obtenues. Dans un deuxième temps, des dérivés siloles présentant une structure tridimensionnelle et une architecture spirosilole (accepteur)-bithiophène (donneur) furent synthétisées. Une cellule photovoltaïque basée sur ces édifices présentant des performances encourageantes fut ensuite mis au point. Enfin, l'étude des mécanismes de transfert d'énergie entre un film de polymère fonctionnalisé par un groupement sensible silole et des composés nitroaromatiques nous a permis de réaliser un nouveau type de capteur optique hautement sensible pour la détection d'explosifs. / This work concerns the design of new π-conjugated compounds, potentially useful in organic electronics as active materials in devices such as OLEDs, photovoltaic cells and optical sensors. To this end, silacyclopentadiene, alias silole, groups were used exhibiting high fluorescence quantum yields in the solid state and excellent electron conductivities. Firstly, the introduction of structurizing groups (triptycene, stilbenes etc.) at the silacyclopentadiene allowed tuning of the molecular arrangement in the active layer and, consequently, the electroluminescence properties. Diodes showing very encouraging activities were thus obtained. Secondly, silole derivatives possessing a three-dimensional structure and a spirosilole (acceptor) - bithiophene (donor) architecture were synthesized. A photovoltaic cell based on these molecules was then developed exhibiting encouraging activity. Finally, a study of the mechanisms of energy transfer between a polymer film functionalized by a sensitive silole group and nitroaromatic compounds enabled the development of a new type of highly sensitive optical sensor for the detection of explosives.

Made available in DSpace on 2017-07-24T19:38:00Z (GMT). No. of bitstreams: 1 Fabio Santana dos Santos.pdf: 2096265 bytes, checksum: 6ebf2a6890fb4ea97cdb1a6d7dfae53f (MD5) Previous issue date: 2009-02-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The discussion presented in this master’s degree dissertation resulted in a study about the development of synthesis routes for obtaining the following organic compounds: 4-(decyloxy)-2,5-bis(dibromomethyl)benzonitrile and 2,5-bis(dibromomethyl)-4-(pentyloxy)benzonitrile. The interest in produced such compounds is related to the preparation, by electrochemical route, of poly(p-phenylenevinylene) (PPV) like polymers in which the decyloxy and/or penthyloxy groups act conferring solubility to the polymeric chain and the group cyano acts altering the electronic structure of the polymeric material intendy to produce a electroluminescente polymer with optimized characteristics for the application in light emitting devices. In that way this text describes the preparation and the characterization of a series of organic compounds. The compounds of interest were prepared after realization of a series of synthetic routes until to be obtained the desired structures. The characterization of these compounds was performed by means of infrared spectroscopic (FTIR) and nuclear magnetic resonance spectroscopic measurements (RMN H1). Beside the preparation and the characterization of the organic compounds aiming to the obtation of electroluminescents polymers, this text describes the preparation and the characterization of the poly(2-methoxy-5-bromo-pphenylenevinylene) (MB-PPV), a polymer which could present similar properties to those intended to the formed, prepared from the compounds described in the first phase of this work. This polymer was electrochemically prepared, and the electron transfer process that occurs during its formation was studied by means cyclic voltammetry and chronoamperometry measurements. During this synthesis it was obtained an insoluble fraction, in the form of powder, and a soluble fraction dissolved in chloroform and another one in methanol. For effect of comparison it was described the electrochemical preparation of the poly(2,5-dicyano-p-phenylenevinylene) (DCNPPV) and the PPV. These polymers were characterized by FTIR and UV-VISIBLE absorption spectroscopy and by measurements of fluorescence. / As discussões apresentadas nesta dissertação de mestrado são resultado de um estudo sobre o desenvolvimento de rotas de síntese para a obtenção dos compostos 4-(decilóxi)-2,5-bis(dibromometil)benzonitrila e 2,5-bis(dibromometil)-4- pentilóxibenzonitrila. O interesse em se obter tais compostos está relacionado à preparação, por via eletroquímica, de polímeros da classe do poli(p-fenilenovinileno) (PPV) nos quais os grupos decilóxi e/ou pentilóxi atuem conferindo solubilidade a cadeia polimérica e o grupo ciano atue alterando a estrutura eletrônica do material de forma a produzir um polímero eletroluminescente com propriedades otimizadas para a aplicação em dispositivos emissores de luz. Desta maneira descreve-se a preparação e a caracterização de uma série de compostos orgânicos. Os compostos de interesse foram preparados após a realização de várias etapas de síntese até se obter as estruturas desejadas. A caracterização destes compostos foi realizada por meio de medidas de espectroscopia de infravermelho (FTIR) e espectroscopia de ressonância magnética nuclear (RMN H1). Além da preparação e da caracterização dos compostos de partida visando à produção de polímeros eletroluminescentes, este texto descreve a preparação e a caracterização do poli(2-metóxi-5-bromo-p-fenilenovinileno) (MB-PPV), um polímero o qual se espera apresente propriedades semelhantes àquelas pretendidas ao polímero formado a partir dos compostos preparados na primeira etapa do trabalho. Este polímero foi sintetizado eletroquimicamente, sendo que o processo de transferência de carga que ocorre durante sua formação foi estudado por meio de medidas de voltametria cíclica e de cronoamperometria. Durante a síntese obteve-se uma fração insolúvel, na forma de pó, e uma fração solúvel em clorofórmio e outra em metanol. Para efeito de comparação descreve-se a preparação eletroquímica do poli(2,5-diciano-p-fenilenovinileno) (DCN-PPV) e do PPV. Estes polímeros foram caracterizados por medidas de FTIR, de espectroscopia de absorção no UV-Visível e por medidas de emissão e excitação de fluorescência.

PRESENTATION DES METHODES DE SIMULATIONS NUMERIQUES DES PHENOMENES DE TRANSPORT ET D'EMISSION RADIATIVE DES DISPOSITIFS COMPORTANT UN NOMBRE QUELCONQUE D'HETEROJONCTION. ETUDE DES DIODES ELECTROLUMINESCENTES A SIMPLE HETEROJONCTION ET A DOUBLE HETEROJONCTION. ANALYSE DE L'INFLUENCE DES PARAMETRES GEOMETRIQUES ET TECHNOLOGIQUES. ANALYSE DES COMPORTEMENTS DES DISPOSITIFS LIES AUX PROPRIETES DES MATERIAUX: ICI ON S'INTERESSE A GAAS-GA::(1-X)ALXAS. ANALYSE DE FACON APPROFONDIE DES PHENOMENES D'ELECTROLUMINESCENCE, QUI SONT LES FONDEMENTS DE TOUTE ETUDE DES PERFORMANCES DES DISPOSITIFS. ETUDE APPROCHEE DES PHENOMENES DE REFLEXION ET REABSORPTION

Pyrroles are found in various natural products and in the chemical composition of certain drugs because of their interesting biological properties. Lipitor, Tolmetin and Amtolmetin are examples of drugs with 1,2,5-substituted pyrroles in their composition, in which biological activities have been certified. Moreover, pyrroles are used as precursors of semiconductor polymers, oligomers and dendrimers useful for the synthesis of electroluminescent materials used in devices, such as organic light-emitting diodes, field-effect transistors, solar and organic photovoltaic cells. We are interested in conjugated polymers based on pyrrole due to their optical properties, electrochemical and the conductivity produced by electron delocalization along their carbon chains. The overall objective of the work presented in this thesis is the synthesis of new molecules based on pyrrole for studying their electronic and electrochemical properties as well for the synthesis of conjugated polymers. Initially, we performed the synthesis of 1,3,5-tri-(1-alkyl-5-methylpyrrol-2-yl)benzenes, which may serve as precursors for the synthesis of conjugated dendrimers. Their synthesis was made in three steps starting from trimethyl 1,3,5-benzene-tricarboxylate which was converted to 1,3,5-tri-(pent-4-enoyl)benzene using vinylmagnesium bromide in a Grignard reaction catalyzed by copper cyanide. The olefins of 1,3,5-tri-(pent-4-enoyl)benzene were oxidized to produce 1,3,5-tri-(4-oxopentanoyl)benzene using a modified protocol of the Tsuji-Wacker reaction. Subsequent, Paal-Knorr condensation reactions on 1,3,5-tri-(4-oxopentanoyl)benzene with different amines were used to synthesize 1,3,5-tri-(1-alkyl-5-methylpyrrol-2-yl)benzenes with different N-substituents in yields between 44 and 60%. Incomplete reaction of vinylmagnesium bromide with trimethyl 1,3,5-benzenetricarboxylate gave the methyl-3,5-di(pent-4-enoyl)benzoate, which was converted to methyl-3,5-dipyrrolylbenzoate following the reaction of Tsuji- Wacker and Paal-Knorr with yields between 30 and 60%. The photochemical and electrochemical properties of the 1,3,5-tri-(1-alkyl-5-methylpyrrol-2-yl)benzenes and methyl-3,5-dipyrrolylbenzoates were studied in collaboration with the research group of professor William Skene. The results have shown that both types of pyrrole have potential for the synthesis of conjugated polymers and dendrimers used in the manufacture of electroluminescent materials. Following these encouraging results, we performed the synthesis of 6,12-dimethyl-1,5-dipyrrolediazocane. Methyl N-(Boc)-β-alaninate was converted to its corresponding homoallylic ketone, which was oxidized to N-(Boc)aminoheptan-3,6-dione. The Paal-Knorr condensation between N-(Boc)aminoheptan-3,6-dione and aminoheptan-3,6-dione hydrochloride gave 6,12-dimethyl-1,5-dipyrrolediazocane in 17% yield. In sum, we have synthesized and characterized seven new molecules, six of them having photochemical and electrochemical properties interesting for the synthesis of conjugated polymers and dendrimers. The latter offering potential as precursor for the conception of compounds of therapeutic interest. / Les pyrroles sont une classe de molécules que l'on trouve dans divers produits naturels ainsi que dans la composition chimique de certains médicaments en raison de leurs propriétés biologiques intéressantes. Le Lipitor, la Tolmetin et l'Amtolmetin sont des exemples de médicaments à base de pyrroles 1,2,5 substitués dont les activités biologiques ont été certifiées. Les pyrroles sont aussi utilisés comme précurseurs de polymères, oligomères et dendrimères semi-conducteurs nécessaires à la synthèse de certains matériaux électroluminescents, tels que les diodes organiques électroluminescentes, les transistors à effets de champ et les cellules organiques photovoltaïques. Nous nous sommes intéressés à ces polymères conjugués à base de pyrroles en raison de leurs qualités de bons conducteurs, de leurs propriétés optiques et électrochimiques que leur confère la délocalisation des électrons le long de leurs chaines carbonées. L'objectif général des travaux présentés dans ce mémoire est de synthétiser de nouvelles molécules à base de pyrroles pouvant éventuellement servir de précurseurs à la synthèse de dendrimères conjugués ainsi qu'à la synthèse de molécules thérapeutiques. Une étude de leurs propriétés électroniques et électrochimiques sera effectuée afin de déterminer leur potentiel pour la fabrication de matériaux électroluminescents. Dans un premier temps, la synthèse des analogues du 1,3,5-benzènetripyrrole a été faite en trois étapes à partir du 1,3,5-benzènetricarboxylate de triméthyle. Celui-ci a été converti en premier lieu en 1,3,5-benzènetricétone-γ,δ-insaturée lors d'une réaction de Grignard catalysée par le cyanure de cuivre. Ce dernier composé fut oxydé lors de la seconde étape en 1,3,5-tri-(4-oxopentanoyl)benzène selon un protocole modifié de la réaction de Tsuji-Wacker. Enfin, la réaction de condensation de Paal-Knorr du 1,3,5-tri-(4-oxopentanoyl)benzène de l'étape précédente mène au 1,3,5-benzènetripyrrole N-substitué selon l'amine utilisée pour la condensation, avec des rendements entre 44 et 60%. La réaction incomplète du bromure de vinylmagnésium avec le 1,3,5-benzènetricarboxylate de triméthyle mène au méthyl-3,5-di-(pent-4-énoyl)benzoate, qui a été converti en méthyl-3,5-dipyrrolylbenzoate suite à la réaction de Tsuji-Wacker et de Paal-Knorr avec des rendements entre 30 et 60%. L'étude des propriétés photochimiques et électrochimiques des tripyrroles et des bipyrroles a été faite en collaboration avec le groupe de recherche du professeur William Skene. Les résultats obtenus démontrèrent que ces pyrroles auraient un potentiel pour la synthèse de dendrimères conjugués servant à la fabrication de matériaux électroluminescents. Suite à ces résultats encourageants, la synthèse du 6,12-diméthyle-1,5-dipyrrolediazocane a aussi été réalisée. Celui-ci a été synthétisé à partir de l’ester méthylique de l’acide 3-tert-butoxycarbonylaminopropionique qui a été converti en sa cétone homoallylique correspondante, puis oxydée en N-Boc-3,6-dioxoheptylcarbamate. La condensation de Paal-Knorr de ce dernier composé avec le sel d'hydrochlorure 7-aminoheptane-2,5-dione mène au 6,12-diméthyle-1,5-dipyrrolediazocane avec un rendement de 17%. En somme, la recherche effectuée a permis la synthèse et la caractérisation de six nouvelles molécules ayant des propriétés photochimiques et électrochimiques intéressantes pour la synthèse de polymères et dendrimères conjugués. Ainsi que la synthèse d'un diazacycle, qui de part sa structure pourrait servir de précurseur à la synthèse de molécules thérapeutiques.

Neste trabalho foram realizados e estudados tratamentos superficiais sobre óxidos transparentes condutivos (TCOs) depositados sobre vidro, cuja aplicação ou finalidade é a montagem de dispositivos poliméricos eletroluminescentes. A principal intenção da utilização destes processos é diminuir a tensão de limiar e também aumentar a luminância desses dispositivos, sem interferir na transmitância original dos filmes. Três diferentes técnicas de tratamentos superficiais foram utilizadas: (a) Plasma de oxigênio; (b) Água-régia e (c) UV-Ozônio. Neste último processo, um reator foi montado utilizando uma lâmpada de vapor de mercúrio a alta pressão (tipo alta intensidade de descarga), sem o bulbo externo para fornecer a disponibilidade de radiação UV para a obtenção de ozônio a partir do ar atmosférico. Este reator com baixo custo e fácil manuseio foi montado para realizar um processo alternativo comparado aos dois processos anteriormente citados (Plasma de oxigênio e Água-Régia) e constitui o principal foco, comparando a partir de resultados experimentais obtidos por dispositivos montados, utilizando diferentes TCOs. Foi possível confirmar que o procedimento a partir do UV-Ozônio é reprodutível, pois pode substituir com vantagens as outras duas técnicas que apresentam custo mais elevado ou que exige manuseio especial. Pela utilização de diferentes períodos de tratamento como a única variável, nas condições estabelecidas durante os experimentos, foi mantida uma amostra sem tratamento para comparação em cada resultado obtido. Em comparação aos outros tratamentos, a técnica de UV-ozônio apresentou reprodutibilidade. Neste caso, verificamos que houve eliminação de contaminantes indesejáveis como carbono e hidrocarbonetos detectadas pela técnica de DRIFT (Diffuse Reflectance Infra-Red Fourier Transformed) e melhor espalhamento de polímero (PEDOT:PSS) sobre a superfície através da técnica de ângulo de contato foi observado. Para os filmes de ITO e FTO o período ótimo foi observado durante 5 minutos e para o ZnO, durante 15 minutos. Os resultados das medições de resistência de folha, espessura e efeito Hall, não revelaram significantes modificações. Revelando que as superfícies foram influenciadas apenas atomicamente ou molecularmente. / In this work superficial treatment on transparent conductive oxides (TCOs) were carried out and studied by application or finality for the assembly of electroluminescent polymeric devices. The mean intention by use of these processes is to decrease the threshold voltage and also increase the luminance of the devices, without interfering in the original TCOs transmittances. Three different treatment techniques were used: (a) oxygen plasma; (b) aqua regia and (c) UV-ozozne. In the he last one, a reactor was assembled using a high-pressure mercury vapor lamp (high intensity discharge lamp type) without outer bulb to provide the available UV radiation to obtain ozone from atmospheric air. This reactor with low cost and easy handle was mounted to accomplish an alternative process compared by other (oxygen plasma and aqua regia) and it has the main focus of this work compared from experimental results obtained by mounted devices using different TCOs. It was possible to confirm that the procedure from the UV-Ozone is reproducible, because it can replaced with advantages the other techniques that have expansive costs or special handling. The use of different treatment times as only variable on the imposed condition in the experiments, a sample was reserved without treatment for comparison during each obtained result. In comparison with other treatments the UV-Ozônio presented reproducibility. In this case was verified the undesirable contaminants eliminated as carbon and hydrocarbon and detected by DRIFT (Diffuse Reflectance Infra-Red Fourier Transformed) technique and better scattering of polymer (PEDOT:PSS) on surface by contact angle was observed. For ITO and FTO films the optimum period was observed during 5 minutes and ZnO during 15 minutes. The measurements results of sheet resistance, thickness and Hall effect revealed no significant changes confirming that the surfaces were influenced only atomically or molecularly only.

Neste trabalho foram realizados e estudados tratamentos superficiais sobre óxidos transparentes condutivos (TCOs) depositados sobre vidro, cuja aplicação ou finalidade é a montagem de dispositivos poliméricos eletroluminescentes. A principal intenção da utilização destes processos é diminuir a tensão de limiar e também aumentar a luminância desses dispositivos, sem interferir na transmitância original dos filmes. Três diferentes técnicas de tratamentos superficiais foram utilizadas: (a) Plasma de oxigênio; (b) Água-régia e (c) UV-Ozônio. Neste último processo, um reator foi montado utilizando uma lâmpada de vapor de mercúrio a alta pressão (tipo alta intensidade de descarga), sem o bulbo externo para fornecer a disponibilidade de radiação UV para a obtenção de ozônio a partir do ar atmosférico. Este reator com baixo custo e fácil manuseio foi montado para realizar um processo alternativo comparado aos dois processos anteriormente citados (Plasma de oxigênio e Água-Régia) e constitui o principal foco, comparando a partir de resultados experimentais obtidos por dispositivos montados, utilizando diferentes TCOs. Foi possível confirmar que o procedimento a partir do UV-Ozônio é reprodutível, pois pode substituir com vantagens as outras duas técnicas que apresentam custo mais elevado ou que exige manuseio especial. Pela utilização de diferentes períodos de tratamento como a única variável, nas condições estabelecidas durante os experimentos, foi mantida uma amostra sem tratamento para comparação em cada resultado obtido. Em comparação aos outros tratamentos, a técnica de UV-ozônio apresentou reprodutibilidade. Neste caso, verificamos que houve eliminação de contaminantes indesejáveis como carbono e hidrocarbonetos detectadas pela técnica de DRIFT (Diffuse Reflectance Infra-Red Fourier Transformed) e melhor espalhamento de polímero (PEDOT:PSS) sobre a superfície através da técnica de ângulo de contato foi observado. Para os filmes de ITO e FTO o período ótimo foi observado durante 5 minutos e para o ZnO, durante 15 minutos. Os resultados das medições de resistência de folha, espessura e efeito Hall, não revelaram significantes modificações. Revelando que as superfícies foram influenciadas apenas atomicamente ou molecularmente. / In this work superficial treatment on transparent conductive oxides (TCOs) were carried out and studied by application or finality for the assembly of electroluminescent polymeric devices. The mean intention by use of these processes is to decrease the threshold voltage and also increase the luminance of the devices, without interfering in the original TCOs transmittances. Three different treatment techniques were used: (a) oxygen plasma; (b) aqua regia and (c) UV-ozozne. In the he last one, a reactor was assembled using a high-pressure mercury vapor lamp (high intensity discharge lamp type) without outer bulb to provide the available UV radiation to obtain ozone from atmospheric air. This reactor with low cost and easy handle was mounted to accomplish an alternative process compared by other (oxygen plasma and aqua regia) and it has the main focus of this work compared from experimental results obtained by mounted devices using different TCOs. It was possible to confirm that the procedure from the UV-Ozone is reproducible, because it can replaced with advantages the other techniques that have expansive costs or special handling. The use of different treatment times as only variable on the imposed condition in the experiments, a sample was reserved without treatment for comparison during each obtained result. In comparison with other treatments the UV-Ozônio presented reproducibility. In this case was verified the undesirable contaminants eliminated as carbon and hydrocarbon and detected by DRIFT (Diffuse Reflectance Infra-Red Fourier Transformed) technique and better scattering of polymer (PEDOT:PSS) on surface by contact angle was observed. For ITO and FTO films the optimum period was observed during 5 minutes and ZnO during 15 minutes. The measurements results of sheet resistance, thickness and Hall effect revealed no significant changes confirming that the surfaces were influenced only atomically or molecularly only.

Les nitrures d’éléments III, à savoir GaN, InN, AlN et leurs alliages, forment une famille de matériaux semi-conducteurs dont les propriétés sont particulièrement intéressantes pour la réalisation de diodes électroluminescentes (LEDs). Leur intérêt réside en particulier dans leur bande interdite qui est directe et qui couvre une large bande spectrale de l’infrarouge (0,65eV pour InN) à l’ultraviolet (6,2eV pour AlN). En raison de l’absence de substrats accordés en maille avec ces matériaux, les couches minces hétéroépitaxiées de nitrure sont généralement touchées par des problèmes de qualité cristalline. Grâce au phénomène de relaxation des contraintes en surface, les nanofils offrent une solution prometteuse pour résoudre ce problème. Ils combinent de nombreux autres avantages : en comparaison des couches minces, l’efficacité quantique interne des LEDs peut être améliorée (surface effective plus importante permettant de diminuer l’effet Auger à courant injecté identique, absence de champ de polarisation en utilisant les facettes non polaires des nanofils) et l’extraction des photons est facilitée par l’effet guide d’onde des nanofils. Cependant, une des difficultés est de parvenir à contrôler la synthèse de ces nano-objets pour garantir une homogénéité des propriétés structurales d’un fil à l’autre et au sein d’un même fil. Dans ce contexte, mon travail de thèse a consisté à étudier d’un point de vue expérimental et théorique l’impact des inhomogénéités structurales sur les propriétés optoélectroniques de dispositifs à nanofils de type LED. J’ai pu mettre en évidence et modéliser un effet de concentration du courant dans les régions riches en indium lorsque les courants injectés sont modérés. Pour de forts courants, le courant se concentre à proximité du contact sur la coquille dopée p. Théoriquement, j’ai montré que la dérive des porteurs de charge dans les puits quantiques et leur diffusion unipolaire et ambipolaire en présence d’un gradient de compositions des puits étaient négligeables. Par ailleurs, je me suis également intéressé à l’interprétation des caractéristiques courant-tension. A l’aide d’un modèle simple, j’ai également identifié la présence de courant de fuite par effet tunnel dans des structures présentant une densité importante de défaut. Dans une seconde partie de ma thèse, je me suis également intéressé à la caractérisation de nanofils à structure coeur-coquille par la technique de courant induit par faisceau d’électrons (Electron Beam Induced Current). La dépendance des cartographies EBIC en fonction de la tension appliquée et de l’énergie du faisceau incident a été modélisée. Ce travail m’a notamment amené à proposer une nouvelle méthode de caractérisation permettant de cartographier les résistivités du coeur et de la coquille des nanofils. / III-nitrides i.e. GaN, InN, AlN and their alloys are semiconductors of choice to fabricate optoelectronic devices such as Light Emitting Diodes (LEDs). One of their most interesting features relies in their direct band gap that covers a very wide spectral range, from infrared (0.65 eV for InN) to UV (6.2 eV for AlN). However, the lack of lattice-matched substrate has been responsible for strong crystalline quality issues in heteroepitaxial thin films. Thanks to stress relaxation at their surface, nanowires provide a smart solution to this problem. Besides, they have a few more assets. In comparison to thin films, nanowires can improve the internal quantum efficiency of LEDs because of their higher effective surface that leads to lowered current densities and thus mitigated Auger effect. The internal quantum efficiency also benefits from the possibility to grow the active region on non polar facets, thus getting rid of the detrimental high internal polarization-induced electric field in quantum wells. Furthermore, the photon extraction efficiency is enhanced by the guiding effect of nanowires. However, despite all this promising advantages, one of the main challenges remains the control of structural homogeneity from wire to wire but also inside single wires.In this context, my work has consisted into studying from an experimental and theoretical point of view the consequences of these structural inhomogeneities on the optoelectronic properties of nanowire based LED devices. I have shown that the current tends to gather into indium-rich regions for moderate bias. At higher bias, the dominant current path though the junction is generally located under the p-contact on the nanowire shell. I have theoretically demonstrated that the unipolar and ambipolar diffusion of carriers as well as their drift induced by a composition gradient inside the quantum wells is not significant in the devices I have studied. Moreover, I took also an interest in the detailed analyze of I-V curves. Thanks to a simple model, I have identified the presence of leakage current related to defect- and phonon-assisted tunneling effect. In the second part of my work, I have focused onto the characterization of core-shell wires using the Electron Beam Induced Current technique. The bias-dependant and acceleration voltage-dependant EBIC maps has been explained with a theoretical model based on equivalent circuits. This study leads me to suggest a new experimental method that can be used to map the nanowire core and shell resistivity.