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A proposta desse estudo é investigar as propriedades de migração do éxciton, transferência de energia e transporte de cargas em heteroestruturas orgânicas ultrafinas compostas pela integração de um polímero semicondutor com moléculas de clorofila. A sintonização dos estados eletrônicos desses materiais torna possível a obtenção de heteroestruturas com modulação energética capazes de aprisionar éxcitons e cargas apresentando potencialidade de aplicação em Diodos Orgânicos Emissores de Luz (OLEDs). Para tal filmes de polifuoreno (PFO) (camada transportadora de carga) totalmente amorfo e filmes de clorofila (camada ativa na forma de poço de potencial) foram preparados utilizando a técnica e automontagem (LBL) combinada com spin-coating, caracterizados por microscopia confocal por varredura a laser e técnicas espectroscópicas de absorção e emissão. Investigou-se os processos fotofísicos utilizando microscopia confocal e de tempo de vida. Os resultados foram interpretados com base no modelo de transferência de energia de Förster combinado com as taxas de Miller-Abrahams e com a equação de difusão excitônica. Com essa abordagem, obteve-se uma relação entre a migração do éxciton no PFO e a transferência de energia não radiativa deste polímero para as moléculas de clorofila. Observou-se uma eficiente transferência de energia igual a 94% no regime de filmes ultrafinos. Para compreender os mecanismos de transporte de carga, implementamos e validamos o método de simulação de Monte Carlo para o transporte de carga em sistemas orgânicos desordenados. Com essa abordagem investigou-se a dinâmica das cargas em filmes poliméricos desordenados com e sem a camada de poço de potencial. Propriedades elétricas, tais como, mobilidade elétrica e coeficiente de difusão, foram obtidas e estão de acordo com os reportados na literatura. Obteve-se uma taxa de preenchimento de cargas no poço de potencial igual a 1010 buracos/s para campo elétrico de 1 MV/cm e constatou-se que a taxa aumenta com o campo elétrico. Tal abordagem apresenta-se como uma alternativa interessante para auxiliar o planejamento experimental de OLEDs baseados em heteroestruturas orgânicas. / In this study the exciton migration, energy transfer and charge transport in ultrathin organic heterostructure formed by semiconductor polymer and chlorophyll molecules were investigated. The energetic tuning between these materials promotes organic heterostructures with energetic modulation capable of trapping excitons and charges showing an application potential in Organic Light Emitting Diodes (OLEDS). Amorphous polyfluorenes (PFO) and chlorophyll a (chla) were prepared using self-assembly combined with spin-coating methods and characterized by confocal laser scanning microscopy and spectroscopic techniques. Photophysical processes were investigated using confocal and life-time microscopy and the results interpreted from the model of Förster energy combined with the Miller-Abrahams rate as well as the exciton diffusion equation. These results provided a relationship between the exciton migration in the PFO film and the non-radiative energy transfer from polymer to chla molecules. An efficient transfer of energy equal to 94% was observed. Method of the Monte Carlo simulation were implemented to investigate the charge transport in this disordered organic system. Using this method, the charge dynamics with and no potential well layer was studied. Electrical properties obtained, such as electric mobility and diffusion coefficient, are in agreement with literature. It was estimated a charge fill rate in the potential well equal to 1010 holes/s for 1 MV/cm and this parameter increases with the electric field. This approach has been shown to be an interesting alternative for the experimental design of OLEDs composed by organic heterostructure.

<p>This work focuses on the surface and interfacial characterisation of silane films of a non-organofunctional silane, 1,2-bis(triethoxysilyl)ethane (BTSE), and an organofunctional silane, γ-mercaptopropyltrimethoxysilane (γ-MPS), deposited on Al, Zn and Al-43.4Zn-1.6Si (AlZn) alloy coated steel. Furthermore, a tribological study of a vegetable oil coupled to an aluminium surface pre-treated with γ-MPS is presented and, finally, the tribological response of thin organic coatings exposed to a sliding contact as evaluated by surface analysis is discussed. The main analyses techniques used were time-of-flight secondary ion mass spectrometry (ToF-SIMS), Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS). </p><p>The results presented in this thesis show that the combination of ToF-SIMS, AES and XPS analysis can be used in order to obtain useful and complementary information regarding the surface and interface characteristics of silane films and organic coatings deposited on metal substrates.</p><p>The major result regarding the silane films is that the silane film composition/structure is not dependent of pH-value during deposition or type of metal substrate. The presence of Si-O-Me ion fragments in the ToF-SIMS spectra is a strong indication that a chemical interaction between the silane film and the metal substrate exists. Furthermore, it has been shown that it is possible to bond a vegetable oil to a thiol functionalised aluminium surface and to produce a coating thick enough to obtain desired friction and wear characteristics. Finally, the use of ToF-SIMS analysis makes it possible to distinguish between mechanical and tribochemical wear mechanisms.</p>

This work focuses on the surface and interfacial characterisation of silane films of a non-organofunctional silane, 1,2-bis(triethoxysilyl)ethane (BTSE), and an organofunctional silane, γ-mercaptopropyltrimethoxysilane (γ-MPS), deposited on Al, Zn and Al-43.4Zn-1.6Si (AlZn) alloy coated steel. Furthermore, a tribological study of a vegetable oil coupled to an aluminium surface pre-treated with γ-MPS is presented and, finally, the tribological response of thin organic coatings exposed to a sliding contact as evaluated by surface analysis is discussed. The main analyses techniques used were time-of-flight secondary ion mass spectrometry (ToF-SIMS), Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS). The results presented in this thesis show that the combination of ToF-SIMS, AES and XPS analysis can be used in order to obtain useful and complementary information regarding the surface and interface characteristics of silane films and organic coatings deposited on metal substrates. The major result regarding the silane films is that the silane film composition/structure is not dependent of pH-value during deposition or type of metal substrate. The presence of Si-O-Me ion fragments in the ToF-SIMS spectra is a strong indication that a chemical interaction between the silane film and the metal substrate exists. Furthermore, it has been shown that it is possible to bond a vegetable oil to a thiol functionalised aluminium surface and to produce a coating thick enough to obtain desired friction and wear characteristics. Finally, the use of ToF-SIMS analysis makes it possible to distinguish between mechanical and tribochemical wear mechanisms.

Oxidation of organic species, in particular dicarboxylic and humic acids, was investigated in ice. Products were analyzed by Proton Transfer Reaction Mass Spectrometry, ion and gas chromatography, and a Total Organic Carbon analyzer. Photolysis of succinic acid with H2O2, an OH precursor, produced malonic acid and malic acid, illustrating that diacids are subject to photochemical degradation in ice. First-order decay rate constants were an order of magnitude higher at room temperature (~23 °C) than in ice (-20 °C). A smaller difference was observed for malonic acid, a more soluble diacid, suggesting that partial segregation of H2O2 and succinic acid during freezing played an important role in the kinetics. VOCs, likely to be aldehydes and ketones, were produced from ice containing humic acid through heterogeneous ozonolysis and photooxidation which was enhanced by NO3-, an OH precursor. VOCs also formed from ice made from deionized water, likely through oxidation of organic contaminants.

Oxidation of organic species, in particular dicarboxylic and humic acids, was investigated in ice. Products were analyzed by Proton Transfer Reaction Mass Spectrometry, ion and gas chromatography, and a Total Organic Carbon analyzer. Photolysis of succinic acid with H2O2, an OH precursor, produced malonic acid and malic acid, illustrating that diacids are subject to photochemical degradation in ice. First-order decay rate constants were an order of magnitude higher at room temperature (~23 °C) than in ice (-20 °C). A smaller difference was observed for malonic acid, a more soluble diacid, suggesting that partial segregation of H2O2 and succinic acid during freezing played an important role in the kinetics. VOCs, likely to be aldehydes and ketones, were produced from ice containing humic acid through heterogeneous ozonolysis and photooxidation which was enhanced by NO3-, an OH precursor. VOCs also formed from ice made from deionized water, likely through oxidation of organic contaminants.

A proposta desse estudo é investigar as propriedades de migração do éxciton, transferência de energia e transporte de cargas em heteroestruturas orgânicas ultrafinas compostas pela integração de um polímero semicondutor com moléculas de clorofila. A sintonização dos estados eletrônicos desses materiais torna possível a obtenção de heteroestruturas com modulação energética capazes de aprisionar éxcitons e cargas apresentando potencialidade de aplicação em Diodos Orgânicos Emissores de Luz (OLEDs). Para tal filmes de polifuoreno (PFO) (camada transportadora de carga) totalmente amorfo e filmes de clorofila (camada ativa na forma de poço de potencial) foram preparados utilizando a técnica e automontagem (LBL) combinada com spin-coating, caracterizados por microscopia confocal por varredura a laser e técnicas espectroscópicas de absorção e emissão. Investigou-se os processos fotofísicos utilizando microscopia confocal e de tempo de vida. Os resultados foram interpretados com base no modelo de transferência de energia de Förster combinado com as taxas de Miller-Abrahams e com a equação de difusão excitônica. Com essa abordagem, obteve-se uma relação entre a migração do éxciton no PFO e a transferência de energia não radiativa deste polímero para as moléculas de clorofila. Observou-se uma eficiente transferência de energia igual a 94% no regime de filmes ultrafinos. Para compreender os mecanismos de transporte de carga, implementamos e validamos o método de simulação de Monte Carlo para o transporte de carga em sistemas orgânicos desordenados. Com essa abordagem investigou-se a dinâmica das cargas em filmes poliméricos desordenados com e sem a camada de poço de potencial. Propriedades elétricas, tais como, mobilidade elétrica e coeficiente de difusão, foram obtidas e estão de acordo com os reportados na literatura. Obteve-se uma taxa de preenchimento de cargas no poço de potencial igual a 1010 buracos/s para campo elétrico de 1 MV/cm e constatou-se que a taxa aumenta com o campo elétrico. Tal abordagem apresenta-se como uma alternativa interessante para auxiliar o planejamento experimental de OLEDs baseados em heteroestruturas orgânicas. / In this study the exciton migration, energy transfer and charge transport in ultrathin organic heterostructure formed by semiconductor polymer and chlorophyll molecules were investigated. The energetic tuning between these materials promotes organic heterostructures with energetic modulation capable of trapping excitons and charges showing an application potential in Organic Light Emitting Diodes (OLEDS). Amorphous polyfluorenes (PFO) and chlorophyll a (chla) were prepared using self-assembly combined with spin-coating methods and characterized by confocal laser scanning microscopy and spectroscopic techniques. Photophysical processes were investigated using confocal and life-time microscopy and the results interpreted from the model of Förster energy combined with the Miller-Abrahams rate as well as the exciton diffusion equation. These results provided a relationship between the exciton migration in the PFO film and the non-radiative energy transfer from polymer to chla molecules. An efficient transfer of energy equal to 94% was observed. Method of the Monte Carlo simulation were implemented to investigate the charge transport in this disordered organic system. Using this method, the charge dynamics with and no potential well layer was studied. Electrical properties obtained, such as electric mobility and diffusion coefficient, are in agreement with literature. It was estimated a charge fill rate in the potential well equal to 1010 holes/s for 1 MV/cm and this parameter increases with the electric field. This approach has been shown to be an interesting alternative for the experimental design of OLEDs composed by organic heterostructure.

Cette thèse a pour but d’étudier la structure à l’échelle nanométrique et micrométrique de matériaux d’intérêt pour la spintronique organique, en se focalisant notamment sur deux aspects cruciaux pour la qualité des dispositifs : les interfaces molécules/métaux et les couches organiques. Pour pouvoir confronter nos résultats aux prédictions théoriques, nous avons utilisé des monocristaux métalliques et effectué des dépôts de molécules sous ultravide, permettant la réalisation d’échantillons de grande qualité. Nous avons concentré notre étude sur deux systèmes, l’un à base de C60 et de Cobalt et l’autre à base de molécules à transition de spin et d’Or. Pour élucider la structure de nos échantillons, nous avons réalisé in situ des mesures de microscopie à effet tunnel et de diffusion des rayons X, deux techniques complémentaires permettant respectivement l’obtention d’informations locales et globales sur le système. Les résultats obtenus ont été comparés à des calculs ab initio réalisés sur ces mêmes systèmes. Concernant le dépôt de molécules de C60 sur un substrat Co(0001), nous avons notamment pu mettre en évidence que le recuit de l’échantillon entraîne une transition structurale de l’interface, avec la création de lacunes dans le substrat sous chaque molécule, formant ainsi un réseau périodique. La couche moléculaire non recuite exhibe en outre une grande cristallinité. Le dépôt de Cobalt sur ce cristal moléculaire entraîne une contraction de ce dernier, due à la diffusion des atomes de Cobalt dans les sites interstitiels. Enfin, concernant les molécules à transition de spin [FeII (HB (3,5-(CH3)2Pz)3)2] déposées sur Au(111), nous avons mis en évidence une relation d’épitaxie inattendue entre le réseau moléculaire et le substrat / The aim of this thesis is to study at micrometric scale and nanoscale the structure of materials of interest for organic spintronics, focusing in particular on two crucial aspects to obtain good devices quality: molecular/metal interfaces and organic layers. In order to compare our results with theoretical predictions, we have used metallic single crystals and molecular deposition under ultra-high vacuum, allowing the obtention of high quality samples. We focused our study on two systems, one based on C60 and Cobalt and the other based on spin crossover molecules and Gold.To elucidate the structure of our samples, we used scanning tunneling microscopy and X-ray scattering, two techniques that are complementary, one probing the local organization and the other the global otganization of the system. The results obtained were compared to ab initio calculations carried out on the same systems. Regarding the deposition of C60 molecules on a Co (0001) substrate, we have been able to demonstrate that the annealing of the sample leads to a structural transition of the interface, with the creation of Cobalt vacancies under each molecules, forming a periodic network. Before annealing, the molecular layer also exhibits high crystallinity. The Cobalt deposition on this molecular crystal causes a contraction of the lattice, due to Cobalt diffusion into interstitial sites. Finally, concerning the [FeII (HB (3,5- (CH3) 2Pz) 3) 2] spin-crossover complex deposited on Au (111), we have demonstrated an unexpected epitaxial relationship between the molecular lattice and the substrate

Recently, bilayer resist processing combined with development in hydro uoroether (HFE) solvents has been shown to enable single color structuring of vacuum-deposited state-of-the-art organic light-emitting diodes (OLED). In this work, we focus on further steps required to achieve multicolor structuring of p-i-n OLEDs using a bilayer resist approach. We show that the green phosphorescent OLED stack is undamaged after lift-off in HFEs, which is a necessary step in order to achieve RGB pixel array structured by means of photolithography. Furthermore, we investigate the in uence of both, double resist processing on red OLEDs and exposure of the devices to ambient conditions, on the basis of the electrical, optical and lifetime parameters of the devices. Additionally, water vapor transmission rates of single and bilayer system are evaluated with thin Ca film conductance test. We conclude that diffusion of propylene glycol methyl ether acetate (PGMEA) through the uoropolymer film is the main mechanism behind OLED degradation observed after bilayer processing.