La automatización de métodos de preparación de muestra es un tema de gran actualidad para reducir tiempos de análisis y mejorar las propiedades analíticas de ensayos químicos. Como consecuencia, en esta tesis doctoral se proponen nuevos métodos de preparación de muestra automáticos y acoplados a técnicas analíticas usando las diferentes generaciones de análisis en flujo para la determinación de contaminantes inorgánicos y orgánicos en muestras de interés ambiental y en residuos industriales. La tesis doctoral se compone de dos partes: La primera se centra en el desarrollo de nuevos métodos automáticos de fraccionamiento químico dinámico e investigación de la bioaccesibilidad de trazas de contaminantes inorgánicos en muestras sólidas, como por ejemplo, cenizas volantes y biomasa vegetal. La segunda parte incluye nuevos métodos automáticos de (ad/ab)sorción previos a ensayos cromatográficos para la extracción, preconcentración, separación y determinación de niveles traza de varias familias de pesticidas (ej., triazinas y sus metabolitos, y compuestos bifenilos policlorados (PCBs)) en muestras ambientales a concentraciones inferiores a las legisladas. A diferencia de los métodos de fraccionamiento basados en equilibrio, los métodos dinámicos en flujo son capaces de cuantificar con mayor exactitud la fracción de metales potencialmente bioaccesible al cambiar las condiciones ambientales como consecuencia del desplazamiento de los equilibrios sólido/líquido y la inexistencia de efectos de readsorción de metales. De hecho, los procesos naturales ocurren en condiciones dinámicas en vez de estáticas, que son asumidas en los métodos clásicos. En este contexto, se diseñó un sistema en flujo miniaturizado basado en la extracción en un reactor agitado para la cuantificación de forma automática de la fracción bioaccesible de elementos traza (Cu, Cd, Ni, Pb y Zn) en tres muestras simultáneamente y con cantidades de muestra variable hasta 1.0 g. Se utilizó un método de extracción secuencial de dos etapas basado en el uso de agua y ácido acético (o tampón ácido acético/acetato) como extractantes para la determinación de las máximas fracciones móviles de elementos traza en cenizas volantes mediante el procedimiento americano de lixiviación característica de toxicidad (US-TCLP). Los resultados experimentales se detallan en el capítulo 3 titulado “Fraccionamiento automático y simultáneo de elementos traza en cenizas volantes usando un sistema múltiple de reactores agitados”. En las extracciones dinámicas la muestra a analizar se coloca en un recipiente adecuado y se expone continuamente a nuevos volúmenes de extractante mediantes sistemas en flujo. En esta tesis, se comparan dos sistemas de extracciones dinámicas basados en el uso de microcolumnas o reactores agitados en sistemas en flujo (Inyección secuencial, SIA) en cuanto al tipo de recipiente para la muestra, representatividad y homogeneidad de la muestra y resultados analíticos, con el objetivo final de armonizar esta nueva metodología de lixiviación. Para ello se evaluó la extractabilidad de Cu, Ni, Pb and Zn en un material de referencia certificado de cenizas de carbón (NIST 1633b) utilizando el método BCR de tres etapas recomendado por la UE. Este trabajo se incluye en el capítulo 4 títulado: “Evaluación crítica de nuevos métodos dinámicos en flujo para la extracción automática de metales traza en cenizas usando el método BCR de extracción secuencial”. Para investigar la posible disponibilidad de elementos responsables de la generación de cenizas (ej., K, Ca, Na y Mg) en biomasa (corteza y ramas de árboles) en gases de combustión se diseñó un sistema en-línea acoplando extracción dinámica basada en reactores agitados a un espectrómetro de plasma acoplado inductivamente con detección óptica. Las fracciones móviles de metales alcalinos y alcalino-térreos son indicadoras de posibles problemas en los sistemas de combustión (formación de depósitos y pérdida de eficacia del reactor) dónde se utilice la biomasa como combustible. Los resultados experimentales se describen en el capítulo 5 titulado: “Método de fraccionamiento químico dinámico con detección elemental por espectrometría de plasma para la caracterización avanzada de biocombustibles sólidos”. El objetivo final de este trabajo es disponer de un método analítico fiable para decidir a la mayor brevedad posible si diferentes tipos de biomasa podrían ser utilizados como combustibles en base a los riesgos de corrosión en reactores. Para elucidar asociaciones entre ceniza/biomasa y metales e investigar la selectividad real de los extractantes, se combinaron los resultados de extracción dinámica con técnicas de caracterización espectroscópica, como por ejemplo, la microscopía electrónica de barrido con espectrometría de fluorescencia de rayos X dispersiva (SEM-EDX) y difracción de rayos X (RXD). Estos estudios se incluyen en el capítulo 6 titulado: “Elucidación de asociaciones de elementos responsables de la generación de cenizas en residuos de biomasa”. En la segunda parte de la tesis se incluyen nuevos métodos automáticos de preparación de muestra basados en la extracción en fase sólida (SPE) en sistemas en flujo acoplados a técnicas cromatográficas (GC o LC) para la determinación de contaminantes orgánicos. En el capítulo 7 titulado: “Microextracción en fase sólida basada en bead-injection multimodal usando polímeros de impresión molecular y materiales de fase reversa para análisis automático de multi-residuos de herbicidas/pesticidas” se propone un método μSPE selectivo con fase sólida renovable de forma automática, denominado Bead-Injection-SPE multidimensional, combinando polímeros de impresión molecular (MIP) y materiales de fase reversa (Oasis HLB) para la preconcentración selectiva de residuos de triazinas y sus metabolitos en extractos crudos de suelos. Se demostró que el acoplamiento μSPE-LC proporciona suficiente sensibilidad y fiabilidad para la determinación de los analitos a niveles de concentración inferiores a los legislados en aguas de consumo humano y aguas superficiales. En el capítulo 8 titulado: “Método de extracción en fase sólida miniaturizado basado en la dispersión de nanofibras de carbono en sistemas en flujo para la determinación automática de niveles traza de contaminantes orgánicos prioritarios mediante LC” se utilizaron nanomateriales de carbono como adsorbentes en técnicas en flujo sin problemas de aglomeración ni aumento de la sobrepresión en el sistema automático. Para demostrar el potencial analítico de este método se analizaron trazas de herbicidas de la familia de las clorotriazinas (atrazina, simazina y propazina) y sus metabolitos (desisopropiltriazina (DIA) y desetilatrazina (DIA) en aguas y extractos de suelos previa preconcentración por μSPE. En el capítulo 9 titulado: “Acoplamiento en-línea de bead-injection-Lab-on-Valve a cromatografía de gases (BI-LOV-GC). Aplicación a la determinación de niveles traza de bifenilos policlorados (PCBs) en lixiviados de residuos sólidos” se propone por primera vez en la bibliografía el acoplamiento de plataformas mesofluídicas con μSPE renovable a GC para la monitorización de contaminantes orgánicos. Mediante este nuevo método se determinaron PCBs en lixiviados crudos de residuos en vertederos previa extracción y concentración automática seguida de separación por GC. / Automatic sample preparation methods are nowadays imperative to meeting compressed analytical timeline. As a result, mechanized sample preparation methods hyphenated with analytical techniques exploiting the different generations of flow analysis were in this dissertation developed and characterized for determination of organic and inorganic pollutants in environmentally relevant samples and industrial wastes. The thesis consists of two parts; the first is devoted to the development of automatic methods for dynamic chemical fractionation and investigation of bioaccessibility of inorganic trace contaminants in solid samples including coal fly ash and biomass fuels. The second part involved the development of automatic sorptive methods prior to chromatographic assays for extraction, preconcentration, separation and determination of trace concentration levels of selected pesticides (namely, triazine and metabolites thereof, and polychlorinated biphenyl compounds (PCBs)) in environmental samples at levels below those endorsed in current Directives. Dynamic flow-through fractionation is proven to afford more accurate evaluation of potentially bioaccessible metal pools under environmentally changing conditions than the equilibrium-based counterparts as a consequence of the solid/liquid equilibria shift and absence of metal redistribution effects. In fact, natural processes are occurring under dynamic rather than static conditions as assumed in classical methods. In this context, a novel miniaturized flow-based configuration capitalized on stirred-flow cell extraction was devised for automatic assessment of bioaccessible pools of trace metals (namely, Cu, Cd, Ni, Pb and Zn) in three samples at a time with no limitation of sample amount up to 1.0 g. A two-step sequential extraction scheme involving water and acetic acid (or acetic acid/acetate buffer) was utilized for reliable estimation of readily mobilisable fractions of trace elements in fly ash under worst-case conditions following the US-Toxicity Characteristic Leaching Test (TCLP), the results of which are reported in chapter 3 entitled “Multiple stirred-flow chamber assembly for simultaneous automatic fractionation of trace element in fly ash samples using a multisyringe-based flow system”. In dynamic extraction approaches, the solid sample under investigation is loaded into a suitable container, and exposed continuously to fresh extractant volumes by resorting to flow-based approaches. In this thesis, two dynamic extraction systems, the so-called sequential injection microcolumn extraction (SI-MCE) and sequential injection stirred-flow chamber extraction (SI-SFCE) were critically compared on the basis of the sample-containing container, sample representativeness, homogeneity of the sample, and analytical results aimed at further harmonization of this novel leaching methodology. The three-step EU approved BCR sequential extraction scheme was performed in both automatic dynamic fractionation systems to evaluate the extractability of Cr, Cu, Ni, Pb and Zn in a standard reference material of coal fly ash (NIST 1633b) as detailed in chapter 4 entitled “Critical evaluation of novel dynamic flow-through methods for automatic sequential BCR extraction of trace metals in fly ash”. On-line coupling of SI-SFCE with ICP-OES was resorted to the exploration of the potential availability of ash-forming elements (e.g., K, Ca, Na and Mg) of biomass fuels (namely, bark and twigs) in flue gases, which is regarded as indicative of potential fireside problems (fouling and slagging in combustion devices). Experimental results are compiled in chapter 5 entitled “Automated dynamic chemical fractionation method with detection by plasma spectrometry for advanced characterization of solid biofuels”. The ultimate aim is to have a reliable system at hand to assist in deciding on a short notice whether or not firing biomass fuels on the basis of potential corrosion risks in combustion devices. For elucidation of metal-biomass/ash associations and investigation of the actual selectivity of extractants, dynamic extraction data was judiciously combined with spectroscopic characterization techniques, namely, scanning electron microscopy with energy dispersive X-ray fluorescence spectrometry (SEM-EDX) and X-ray diffraction (RXD) assays. These studies are shown in chapter 6 entitled “Elucidation of associations of ash-forming matter in woody biomass residues”. In the second part of the thesis, automatic sample preparation methods have been developed using solid-phase extraction (SPE) approaches in flowing stream systems as a “front end” to chromatography techniques (GC or LC). Selective μSPE in a Bead-Injection (automatic renewable SPE) mode in the so-called multi-dimensional SPE combining molecular imprinted polymers (MIP) and reversed-phase sorbents (Oasis HLB) was utilized in Chapter 7 (Multimodal bead injection-based flow-through microextraction involving renewable molecularly imprinted and reversed-phase sorbents as a front end to liquid chromatography for automatic multiresidue assays) for selective preconcentration of triazine residues and their metabolites in crude soil extracts. The hyphenated μSPE-HPLC system was proven to provide sufficient sensitivity and reliability for determination of the target herbicides (namely, atrazine, simazine and propazine) and their dealkylated metabolites (namely, deisopropyltriazine (DIA) and deethylatrazine (DEA)) at concentration levels below those specified by current legislations for human water consumption and surface waters. In chapter 8 entitled “Flowthrough dispersed carbon nanofiber-based microsolid-phase extraction coupled to liquid chromatography for automatic determination of trace levels of priority environmental pollutants” dispersed carbon nanomaterials were handled as sorptive surfaces in an automatic flow-mode with minimum nanoparticle agglomeration and negligible pressure drop. The proof-of-concept of the method was demonstrated for μSPE and clean-up of chlorotriazine residues (namely, atrazine, simazine and propazine) and their dealkylated metabolites (namely, deisopropyltriazine (DIA) and deethylatrazine (DEA)) in both environmental waters and soil extracts. In Chapter 9 entitled “On-line coupling of bead injection-lab on valve analysis to gas chromatography (BI-LOV-GC). Application to the determination of trace levels of polychlorinated biphenyls (PCBs) in solid waste leachates” is for the first time demonstrated the coupling of mesofluidic platforms with renewable μSPE to GC for monitoring of organic pollutants. This new approach fostered the isolation, concentration, separation and determination of PCBs from raw landfill leachates.

Les cellules solaires en couches minces à base de Cu(In,Ga)Se2 peuvent atteindre des rendements de conversion supérieurs à 20 % par un procédé de dépôt sous vide. Afin de diminuer les coûts de production, d’autres méthodes de dépôts sont envisagées. L’une d’elle, déjà développée à l’échelle industrielle, consiste à électrodéposer Cu, In et Ga successivement sur un substrat de molybdène, puis à sélénier la couche par traitement thermique réactif. L’alternative étudiée dans ce travail consiste à tirer partie de l’affinité de l’indium et du gallium pour l’oxygène en électrodéposant les trois éléments simultanément sous forme d’oxydes, puis à les réduire par recuit. Le mécanisme de dépôt est étudié par voltampérométrie et chronoampérométrie. Celui-ci est basé sur une augmentation locale du pH par réduction d’ions nitrates, permettant la précipitation des oxydes/hydroxydes de Cu, In et Ga. Les conditions d’électrodépôt sont optimisées et les dépôts sont caractérisés. La réduction des dépôts d’oxydes par recuit est ensuite étudiée sous atmosphère d’hydrogène dilué dans un gaz inerte. La cinétique de réduction de l’oxyde de Ga est très lente et les conditions de recuit mises au point conduisent à la formation de la phase GaMo3, en plus des phases Cu-In-Ga attendues. La sélénisation à 550°C conduit à la formation de CuInSe2 et à la ségrégation de Ga vers la face arrière de la cellule. Les premiers résultats de cellules obtenues par ce procédé ont donné un rendement de conversion maximal de 9,4 %. Un procédé de sélénisation en plusieurs étapes est développé et permet une meilleure homogénéisation du Ga dans la couche. / Thin film solar cells based on Cu(In,Ga)Se2 can reach conversion efficiency higher than 20 % by vacuum deposition techniques. In order to decrease the production costs, other techniques are considered. One of them, already developed at the industrial level, consists in the electrodeposition of Cu, In and Ga by stacks on a molybdenum substrate, and then to selenize the layer by reactive thermal treatment. The alternative way developed in this work consists in taking advantage of the strong affinity of indium and gallium for oxygen by electrodeposition of the three elements as oxides, then to reduce the layer by reactive annealing. The electrodeposition mechanism is studied by voltamperometry and chronoamperometry. It is based on a local pH increase at the electrode surface by nitrate reduction that enables copper, indium and gallium oxides/hydroxides precipitation. Electrodeposition conditions are optimized and deposits are characterized. The reduction of the oxide layer by annealing is then studied under hydrogen atmosphere diluted in an inert gas. The reduction kinetic of gallium oxide is very slow and the optimized annealing conditions lead to the formation of GaMo3 phase in addition to the expected Cu-In-Ga alloys. The selenization at 550°C leads to the formation of CuInSe2 and the segregation of Ga near the cell back contact. First cell results obtained by this process show conversion efficiency up to 9.4%. A multi-step selenization process is developed and enables a better Ga homogeneity in the layer.

Ce projet a pour ambition de concevoir et de réaliser une nouvelle filière de cellule photovoltaïque utilisant la conversion directe de l’énergie solaire en électricité à base de la filière InGaN permettant d'atteindre un rendement de 50% de conversion directe de l’énergie solaire en électricité. Cette nouvelle approche constitue un défi technologique majeur pour la recherche académique et les applications industrielles dans les années avenir. Les cellules solaires actuelles à base de Silicium approchent leur limite théorique de rendement de conversion d’énergie (environ 25%). Les cellules solaires multi-jonctions permettent de repousser ces limites en empilant plusieurs matériaux possédant différentes énergies de bande interdite, chacun absorbant une petite portion du spectre solaire de manière plus efficace. Alors que les LEDs violettes et bleu à base du matériau InGaN sont déjà commercialisées, il apparaît essentiel de relever le défi qui consiste à fabriquer et utiliser ce matériau InGaN avec de fort taux d’Indium (i.e. des énergies de bandes interdites plus faibles) afin de couvrir l’ensemble du spectre solaire et ainsi réaliser des cellules photovoltaïques à très haut rendement, bien au-delà de l’état de l’art international. Au vu des limitations des cellules au silicium, des travaux théoriques ont montrés que des cellules à jonctions multiples à base de couches absorbantes d’InGaN permettraient d’atteindre un rendement de 50%. L’amélioration du rendement des cellules solaires aura un impact majeur sur de nombreuses applications. L’objectif de ce travail concerne la conception et de réalisation d'une nouvelle génération de cellule solaire à base d’InGaN. Ce travail concerne dans une première phase : la caractérisation du matériau InGaN à fort taux d’Indium (> 20%) élaboré à l'EPFL en collaboration avec l'IEMN ayant pour but de démontrer une énergie de bande interdite en dessous de 2 eV. Dans une seconde phase, après la validation électrique et structurelle de ce nouveau matériau, il s’agit de concevoir et de réaliser une nouvelle génération de cellule solaire mono-jonction sur saphir et sur substrat GaN. Cette nouvelle cellule solaire pourra être intégrée au sein d’une microsource d’énergie pour réseau de capteur autonome. / This PhD thesis reports on the structural and optical characterization of solar cell structures with various active region designs and different substrates as well as the subsequent fabrication and electrical characterization of InGaN solar cells. The epitaxial growth of solar cell designs with pGaN/i-InGaN/n-GaN structures were performed by metal-organic vapor phase epitaxy (MOCVD) by the company NovaGaN. The structural and optical characterization is assessed by X-Ray diffraction, scanning transmission electron microscopy, atomic force microscopy and photoluminescence spectroscopy. A structural comparison of solar cell designs including bulk 200 nm thick InGaN layer and InGaN/GaN multiple quantum wells (MQWs) with similar indium compositions (~30%) is presented. Furthermore, structural quality of designs with InGaN/GaN MQWs were analyzed with variation of the indium content, thickness of InGaN quantum wells and type of the substrate, i.e. (0001) sapphire or bulk GaN substrate. An optimized and reproducible processing has been developed for fabrication of InGaN based solar cells. The challenges in device processing such as mesa etching of GaN and contamination on the device sidewalls, which caused high reverse leakage currents were studied and solutions of using SiO2 mask and protection of sidewalls by SiO2 layers were proposed. An optimization study of thermal treatment of Ni/Au current spreading layer is also presented. The electrical activity in the active region and the spectral response of the solar cells are investigated by electron beam induced current (EBIC) analysis and external quantum efficiency measurements. EBIC analysis is used to clarify the origin of the S-shape behavior in illuminated current-voltage characteristics of the solar cell with 25×In0.15Ga0.85N/GaN MQWs, which has performed the best performance in this study with a conversion efficiency of 0.59% under 1sun illumination (AM1.5G).

Ce travail de recherche porte sur l’élaboration et la caractérisation de films minces photo-absorbants de CuInS2, CuIn1-xGaxS2, et de Cu2ZnSnS4 destinés aux applications photovoltaïques. Les films minces ont été préparés par voie sol-gel puis déposés par enduction centrifuge sur substrat de silicium ou de verre. Les sols, formés à partir d’acétates métalliques et d’alcanolamines, ont été étudiés par spectroscopie IR, viscosimétrie et ATD-ATG. Les paramètres de dépôts des sols, et les traitements de calcination, ont ensuite été optimisés. Des films d’oxydes multi-couches, sans fissuration, et de faibles rugosités ont ainsi été élaborés. Une dernière étape de sulfuration des films d’oxydes a été effectuée afin de former les composés souhaités. Les films sulfurés ont fait l’objet d’une étude approfondie par DRX, EDX, MEB, AFM, spectroscopie UV-VIS-nIR et mesures par effet Hall. Leurs structures, leurs morphologies, mais aussi leurs propriétés optiques et électriques ont ainsi pu être étudiées. L’interface des films de CuInS2 avec le film de Mo, utilisé comme contact ohmique arrière de la cellule solaire, a également été étudiée par micro-EDX à l’aide d’analyses MET. Les résultats obtenus montrent que le procédé sol-gel, bien que très peu développé dans le domaine des cellules photovoltaïques, est une voie de synthèse bien adaptée à l’élaboration de films minces à structure chalcopyrite et kësterite. Ces résultats sont très prometteurs pour la réalisation d’une cellule solaire par voie sol-gel. / This research activity concerns the elaboration and characterization of photo-absorbing thin films of CuInS2, CuIn1-xGaxS2, and Cu2ZnSnS4 devoted to photovoltaic applications. The thin films were prepared by sol-gel process and deposited by spin-coating technique on silicon and glass substrates. The sols, synthesized from metallic acetates and alcanolamines, were studied by IR-spectroscopy, viscosimetry, and TDA-TGA. The deposition parameters of the sols, and the calcination treatments were then optimized. The multi-layers oxides films produced were obtained without cracks and with low roughness. The last step was to produce the desired compounds through the sulfurization of the oxides films. The sulfurized films were studied by XRD, EDX, SEM, AFM, UV-VIS-nIR spectroscopy, and Hall Effect measurements. Their structures, morphologies, as well as their optical and electrical properties have been investigated. The interface between CuInS2 films and Mo film, defined as a back-contact of the solar cell, was also studied by micro-EDX with TEM analysis. Despite the fact that sol-gel process is not well-developed in the photovoltaic field, the obtained results show that sol-gel process is a well-adapted technique for elaboration of thin films with chalcopyrite and kesterite structures. These results are very promising for the achievement of a sol-gel solar cell.

Dans les cellules solaires planaires silicium, le matériau doit être assez épais pour que l’absorption des photons soit efficace, et dans le même temps, l’accroissement de l’épaisseur augmente les chances de recombinaison des porteurs. Afin d’avoir à la fois absorption et couche mince, des structures radiales (nanopiliers ou nanocones) peuvent être utilisées, qui ont des diamètres inférieurs à la longueur de diffusion des porteurs minoritaires, ce qui garantit une bonne collecte des porteurs. Ce travail présente la réalisation et la caractérisation de cellules solaires silicium bas coût, basées sur des nanostructures (piliers ou cônes). Pour la nanostructuration, l’usage d’un masqueur électronique est évité grâce à l’utilisation de microbilles de silice, déposées par technique Langmuir-Blodget et servant de masque à la gravure sèche des nanostructures. L’électrode face avant est en ZnO, obtenue par technique sol-gel. Avant la fabrication, une simulation des propriétés optiques des nanostructures en fonction de leur forme (densité, hauteur, diamètre,) a été réalisée à l’aide de calculs FDTD (Finite Difference Time Domain). La synthèse des films ZnO par sol gel a été optimisée (concentration des dopants, recuit thermique, hydrogénation, …) afin d’avoir la meilleure transparence optique et la plus faible résistivité. Finalement, des cellules solaires n+- i - p ont été réalisées, assemblant nanostructures et couche ZnO. Des étapes supplémentaires de passivation des défauts de surface et d’interfaces associés aux nanostructures ont été finalement menées. / For planar p-n junction solar cell, the material must be thick enough to have enough absorption, whereas increasing the thickness leads to the increase of recombination of carriers. In order to decouple the requirement of light absorption and carrier collection, nanopillars (or nanocones) radial p-n junction are introduced. Nanopillars (or nanocones) have greater absorption and radial geometry offers minimal recombination if the diameter of nanopillars ( or nanocones ) is smaller than the minority carrier diffusion length. This work presents the realization and characterization of low-cost Si nanostructures (nanopillars and nanocones) solar cell with sol-gel derived ZnO transparent electrodes. In order to decrease the fabrication price, silica balls and Lamguir-Blodgett techniques are used as the substitutes of photoresist and electrical beam lithography, respectively. Besides, ZnO thin film transparent electrodes are synthesized by low-cost sol-gel methods For pursuiting high efficiency, first of all, we have tested the absorption of nanopillars and nanocones by varying their periods, diameters, lengths and sidewalls. Second, we have optimized the electrical properties of ZnO thin film by changing the synthesis parameters, such as doping concentration, baking temperature, anneal temperature and hydrogen treatment. In the end, solar cells were fabricated based on optimized Si nanostructures and optimized ZnO thin films. Due to their bad electrical properties associated with surface defects, surface passivation methods were performed to reduce the defects concentration in p-i-n junction and improve the efficiency of solar cells.

La viabilité de la filière silicium pour la conversion photovoltaïque n’est plus à démontrée, notamment au regard du nombre croissant d’industries de cellules solaires qui s’implantent dans les pays développés. Le développement de nouvelles structures ou dispositifs optiques afin d’améliorer le piégeage de la lumière au sein des cellules solaires est un véritable défi. Les travaux de cette thèse portent sur une nouvelle génération de capteurs solaires performants en s’appuyant sur l’association d’une nanostructuration de la surface, d’un réseau de nano-objets métalliques et de terres rares au sein d’une matrice vitreuse. Dans un premier temps, nous avons optimisé deux formes de textures à la surface du silicium qui ont augmenté l’absorption de 15 % pour les formes à nanopiliers et de 28 % pour les nanocônes. La gravure du silicium engendre l’apparition de défauts sur la surface. Nous avons travaillé sur trois approches de passivation pour limiter les phénomènes de recombinaison avec les matériaux Al2O3 et SiNx. La deuxième étape de ces travaux a porté sur l’étude des plasmoniques d’un réseau de nano-objets d’argent fabriqués à travers des microsphères de silice auto-assemblées déposées par la technique Langmuir-Blodgett. Leur intégration dans la matrice vitreuse a augmenté significativement le rendement de nos cellules solaires. Dans la dernière partie, nous avons étudié l’association de ces nano-objets métalliques avec une couche down-conversion constituée d’une matrice SiNx avec les terres rares Tb3+ et Yb3+.Cette association a montré une augmentation de l’intensité de photoluminescence d’un facteur 2,3. L’application de la couche DC seule sur nos cellules a augmenté l’efficacité d’un facteur 1,68. / The viability of the silicon sector for the photovoltaic conversion is not any more in demonstrated, in particular with regard to the increasing number of industries of solar cells which become established in the developed countries. To obtain a large absorption of the light, the development of new structures or optical devices to improve the light trapping within solar cells is a real challenge. The works of this thesis concern a new generation of solar cells on the association of a network of metallic nano-objects and rare earth within a SiNx matrix. At first, we optimized two forms of textures on the surface of the silicon which increased the absorption in 15 % for the forms with nanopillars and 28 % for nanocones. The etching process of the silicon engenders the appearance of defects on the surface. We worked on three approaches of the surface passivation using thin layers of Al2O3 and SiNx materials to limit the phenomena of recombination. The second step of these works concerned the study of the plasmonics of a silver nanoparticles arrays fabricated through auto-assembled silica microspheres deposited by the Langmuir-Blodgett technique. The incorporation of silver nanoparticles in the matrix increased significantly our solar cells efficiency. In the last part, we studied the association of these metallic nano-objects with a layer down-conversion established of a matrix SiNx with rare earth Tb3+ and Yb3+. This association showed an increase of the intensity of photoluminescence of a factor 2,3. The application of the DC layer alone on our cells increased the efficiency of a factor 1,68.

Dans cette thèse, nous avons étudié le couplage entre le transport de charge dans un conducteur quantique et le rayonnement émis dans son environnement électromagnétique. En effet, le caractère probabiliste du transport électrique dans ce type de conducteurs engendre des fluctuations de courant qui dissipent de l'énergie dans l'environnement sous forme de photons.Pour étudier cette interaction, nous avons utilisé un circuit dans lequel une Jonction Josephson couplée à un résonateur micro-onde est polarisée avec une tension continue. Quand la tension de polarisation atteint la condition pour laquelle le travail fourni par le générateur lorsque la charge d'une paire de Cooper traverse le circuit correspond à l'énergie d'un nombre entier de photons du résonateur, on observe un courant continu de paires de Cooper associé à l'émission de rayonnement dans le résonateur. Ce rayonnement est ensuite collecté dans une ligne de mesure micro-onde. En fabriquant des résonateurs hautes impédances basés sur des inductances planaires, nous avons pu atteindre le régime de fort couplage et observer les effets spectaculaires de cette interaction lumière-matière. D'une part, le régime de fort couplage exacerbe les processus multi-photoniques et nous avons observé jusqu'à l'émission simultanée de neuf photons part une paire de Cooper. De plus en utilisant un montage de type Hanbury-Brown and Twiss, nous avons pu mesurer la statistique des photons émis. Nous avons ainsi démontré que la rétroaction de l'environnement sur la dynamique du transport permet de créer une source non-classique de photons sous-Poissonniens, en accord avec les prédictions théoriques. / In this thesis, we investigate the coupling between the charge transport in a quantum conductor and the associated radiation emitted in the electromagnetic environment. In fact, the probabilistic character of the electric transport in this type of conductors generates current fluctuations which dissipate energy in the environment in the form of photons.To study this interaction, we used a circuit in which a Josephson junction is coupled to a microwave resonator and dc voltage biased. When the bias voltage reaches the condition so that the work supplied by the generator when the charge of a Cooper pair passes through the circuit corresponds to the energy of an integer number of photons of the resonator, we observe a dc current of Cooper pairs associated with the emission of radiation in the resonator. This radiation is then collected in a microwave measuring line. By carefully engineering high impedance resonators based on planar inductances, we were able to reach the strong coupling regime and observed the dramatic effects of this light-matter interaction. First, the strong coupling regime favors multi-photon processes and we observed up to the simultaneous emission of nine photons by a single tunneling Cooper pair. In addition, using a Hanbury-Brown and Twiss type, we were able to measure the statistics of the emitted photons. We have demonstrated that the feedback of the environment on the transport dynamics creates a non-classical source of antibunched photons, in agreement with the theoretical predictions.

Genetic alterations and deregulation of the epigenetic mechanisms collaborate in the initiation and progression of cancer. In contrast to the genetic defects, the epigenetic abnormalities are potentially reversible. This fact has driven the search for drugs that induce selectively changes in the epigenetic patterns of the tumor cells and thus lead to differentiation, cell death and/or cell growth arrest. Inhibitors of DNA (cytosine-5)-methyltransferases (DNMTs) and inhibitors of Zn(II)-dependent histone deacetylases (HDACs) have been developed with this purpose. The DNMTs inhibitors allow the reactivation of genes, including tumor-suppressor genes, silenced through hypermethylation of the CpG island at their promoter. The HDACs inhibitors allow the reexpression of genes silenced by ypoacetylation of the histones associated at their promoters. Despite all these chemicals have promising effects on cultured cancer cells, many of them have side-effects that limit their use in anticancer chemotherapy. Because of that, we analyzed the properties of the anesthetic procaine (4-aminobenzoic acid 2-diethylaminoethyl ester) as a new inducer of DNA demethylation and we also compared the effects of seven HDACs inhibitors. In both cases, the breast cancer cell line MCF7 was the model system.1. Procaine reduces the proportion of 5-methylcytosine into global genomic DNA, achieving its maximum effect within 24-48 h of treatment. Low concentrations of procaine decrease the amount of 5- methylcytosine at RAR¦Â2 promoter, which is hypermethylated in MCF7 cells, and reactivate its expression with only small decrease in global DNA methylation. This fact could be an advantage, since global DNA hypomethylation leads to chromosomal instability. Finally, procaine reduces cell proliferation and arrests cell cycle in mitosis, but does not induce apoptosis in MCF7 cells after treatments 3 days long.2. The seven inhibitors of Zn(II)-dependent HDACs chosen for comparison were: two carboxylic acids (butanoic and valproic acid); one N-(2¡¯-aminophenyl) benzamide (MS-275); and four hydroxamic acids(trichostatin A, suberoylanilide hydroxamic acid, CX and CY). The results of in vitro HDAC activity assays performed on MCF7 nuclear extracts show the existence of a relationship between the chemical structure of these compounds and their activity: low micromolar concentrations of hydroxamic acids are sufficient for inhibiting almost completely the deacetylase activity, whereas millimolar concentrations of carboxylic acids are required for similar effects. Also the alterations that the drugs cause on cell growth and cell cycle arrest depend on its chemical structure. The IC50 for cell treatments 24 h long is in the range of millimolar concentrations for butanoic and valproic acids and low micromolar for the rest of the chemicals. At the IC50, MS-275 induces cell growth arrest in G1/G0, whereas the hydroxamic acids stop cell cycle mostly at G2/M and the carboxylic acids seems to arrest the cycle at both G1/G0 and G2/M. Despite all these inhibitors induce similar changes in the global acetylation of H4 and H3 when employed at their respective IC50, not all of them are able of reactivate the expression of the same genes. Moreover, it seems that the induced expression levels of CDKN1A and GADD45¦Â determine the alterations induced by the drugs on cell cycle. The changes on histone modifications at the promoters of six genes ( CDKN1A, GADD45¦Â, JunD, IGFBP3, MT1X and MT2A) upon CY treatment were studied. HDACs inhibition induces an increase in histone H4 tetraacetylation and in dimethylation of lysine 4 in H3, as well as a decrease in dimethylation of lysine 9 in H3. Additionally, HDAC2 is released from the promoters upon CY treatment. These changes take place also in the promoters of MT1X and MT2A, the genes whose expression remains unaltered after the treatment with CY. / Las alteraciones genéticas y la desregulación de los mecanismos epigenéticos colaboran en la iniciación y progresión del cáncer. Los defectos epigenéticos son potencialmente reversibles, lo que ha suscitado la búsqueda de fármacos que selectivamente causen cambios en los patrones epigenéticos de las células tumorales, con la consiguiente diferenciación, muerte y/o parada de crecimiento de las mismas. Se han estudiado especialmente inhibidores de metiltransferasas de DNA (DNMTs) e inhibidores de desacetilasas de histonas (HDACs) dependientes de Zn(II). Los inhibidores de DNMTs posibilitan la reactivación de genes silenciados mediante hipermetilación de la isla CpG de su promotor y los inhibidores de HDACs, de genes silenciados vía hipoacetilación de las histonas asociadas a su promotor. A pesar de sus prometedores efectos en cultivos celulares, muchas de estas sustancias presentan inconvenientes que limitan su aplicación en quimioterapia. Por ello, en esta tesis:1. Se ha estudiado por primera vez la capacidad del anestésico procaína para reducir la metilación de DNA genómico y la proliferación de la línea celular MCF7. Procaína reduce la cantidad de 5-metilcitosina en DNA, reactiva genes silenciados por hipermetilación ( RAR¦Â2) e induce parada del ciclo celular en mitosis.2. Se han comparado siete inhibidores de HDACs dependientes de Zn(II): ácido butanoico, ácido valproico, MS-275, tricostatina A (TSA), SAHA, CX y CY. Existe una relación estructura-actividad para los efectos de estas sustancias en ensayos in vitro y en el crecimiento de MCF7. Además, aunque estos inhibidores inducen cambios similares en acetilación global de histonas, no todos reactivan los mismos genes. Los niveles expresión de CDKN1A y GADD45¦Â parecen determinar los efectos de estos compuestos en el ciclo celular. En los promotores de los seis genes estudiados, la inhibición de HDACs aumenta la acetilación de H4 y la dimetilación de la lisina 4 de H3, mientras disminuye la dimetilación de lisina 9 de H3.

No description available.

Durante las últimas décadas muchos trabajos se han concentrado en el desarrollo de nuevos materiales retardantes a la llama con altas prestaciones, para aplicaciones en industrias electrónicas y aeroespaciales. Éstos deben exhibir además de la alta resistencia a la llama otras buenas propiedades, tales como: alta temperatura de transición vítrea, bajo stress interno, buena adhesión, baja constante dieléctrica y baja toxicidad. Las resinas epoxi bromadas, se encuentran entre los polímeros más usado en la fabricación de dispositivos electrónicos. Sin embargo, durante la combustión liberan productos tóxicos como bromuro de hidrógeno, dibenzodioxina y dibenzofurano. El concepto de desarrollo sostenible requiere la utilización de tecnologías de retardantes a la llama con un mínimo impacto en la salud y el medioambiente. Así, la incorporación de fósforo o silicio en la estructura polimérica se reconoce como uno de los caminos más eficientes para obtener un sistema retardante a la llama respetuoso con el medio ambiente. El objetivo general de este trabajo ha sido el desarrollo de nuevos sistemas poliméricos termoestables resistentes al fuego, sin detrimento en las propiedades del material y no agresivos medioambientalmente. Se pretende mejorar las buenas propiedades de algunos materiales estándar actualmente empleados, tales como resinas epoxi y resinas fenólicas, pero introduciendo la condición de no inflamabilidad mediante nuevos sistemas de ignifugación alternativos a los sistemas halogenados clásicos. Para ello se propone la síntesis y caracterización de nuevos tipos de sistemas en los que se ha incorporado fósforo y/o silicio a resinas epoxi y benzoxazinas y se han evaluado sus propiedades. Se sintetizó diglicidiléter de 2,5 (dihidroxifenil)difenilfosfina (Gly‐P) y se investigó su comportamiento térmico y su reactividad. Se examino la incorporación de diferentes cantidades de fósforo en la resina epoxi por curado del Gly‐P/DGEBA con DDM. También fueron preparadas resinas epoxi conteniendo distintas proporciones de fósforo y silicio en su estructura poniendo de manifiesto el Gly‐P, fenildiglicidiloximetilsilano (Gly-Si) y/o 1,4(glicidiloxidimetilsilil) benceno (BGDMSB) como monómeros epoxi y diaminodifenilmetano (DDM), óxido bis(m‐aminofenil)metilfosfina (BAMPO) y bis(4aminofenoxi) dimetil silano (APDS) como agentes de curado. Se evaluaron sus propiedades térmicas, dinamomecánicas y de retardancia a la llama. Utilizando el índice limitante de oxígeno (LOI) se confirmo que las resinas epoxi que contienen heteroátomos son eficientes retardantes a la llama, pero no se observó efecto sinérgico. Por otro lado, en este trabajo, se incorporó el fósforo en la estructura de la benzoxazina derivada del óxido de bis(m‐aminofenil)metilfosfina (Bz‐BAMPO) utilizando un método sintético en tres etapas a partir de la diamina BAMPO y del 2‐hidroxibenzaldehído como productos de partida. Se estudió su cinética de curado por análisis isoconversional y por espectroscopía de IR. También, se estudió la copolimerización de Bz‐BAMPO con la benzoxazina derivada del bisfenol A y el diglicidiléter de bisfenol A (DGEBA) con diferentes proporciones de fósforo. Se evaluaron sus propiedades térmicas y dinamomecánicas y se determinaron los valores del LOI que dieron buenas propiedades en la retardancia a la llama. Otra alternativa para incorporar fósforo o silicio en los sistemas de benzoxazina ha sido por copolimerización de la benzoxazina derivada del bisfenol A con el Gly‐P y el Gly‐Si. Así, se han preparado sistemas benzoxazinas‐epoxi con distinto contenido de fósforo o silicio. Se evaluaron sus propiedades térmicas, dinamomecánicas y se determinaron los valores del LOI poniendo de manifiesto el notable efecto del fósforo y la baja eficiencia del silicio. / During the last decades much work has been concentrated on developing new flameretardant materials with high performance for applications such as, electronic and aerospace industries. These must exhibit high glass transition temperature, low internal stress, good adhesion, low constant dielectric, low toxicity and high flame retardancy. The bromine‐containing epoxy, are found among the most used polymers in the manufacture of electronic devices. However, the bromine‐containing advanced epoxy resin release hydrogen bromide, dibenzo‐p‐dioxin and dibenzo‐furan during combustion, which cause corrosion and toxicity. The concept of sustainable development requires fire retardant technologies to be developed, which have minimum impact on health and the environment. The incorporation of phosphorus or silicon functionality in the polymeric structure is recognized as one of the most efficient ways to obtain an environmentally friendly flame retardant system. The general objective of this work has been the development of new fire retardant thermosettings systems, keeping the material properties and environmentally friendly, The goals is to improve the good properties of some standard materials, phenolic and epoxy resins, but introducing the non inflammability character by means of new ignifugation systems, alternative to the classic halogenated systems. We propose the synthesis and characterization of new types of flame retardant systems ‐phosphorus‐and/or silicon containing in the structure of epoxy resins and polybenzoxazines and we evaluated their properties. We synthesized the diglycidyl ether of (2,5‐dihydroxyphenyl)diphenyl phosphine oxide (Gly‐P) and we investigated its thermal behaviour and reactivity. We examined the incorporation of different amounts of phosphorus into the epoxy resin by curing the Gly‐P/DGEBA system with DDM. Also, phosphorus and silicon‐containing epoxy resins were prepared from (2,5‐dihydroxyphenyl) diphenyl phosphine oxide (Gly‐P), diglycidyloxy methylphenyl silane (Gly‐Si) and 1,4‐bis(glycidyloxidimethyl silyl)‐benzene (BGDMSB) as epoxy monomers and diaminodiphenylmethane (DDM) , bis(3‐aminophenyl)methyl phosphine oxide (BAMPO) and bis(4‐aminophenoxy)dimethyl silane (APDS) as curing agents. Epoxy resins with different phosphorus and silicon content were obtained. Their thermal, dynamic mechanical and flame retardant properties were evaluated. The high Limiting oxygen index (LOI) values confirmed that epoxy resins heteroatom‐containing are effective flame retardants, but a synergistic efficiency of phosphorus and silicon on flame retardation was not observed. Moreover, in this work, a the phosphoru was incorporated into the structure of the benzoxazine in the form of phenylphosphine oxide thus a diamine‐based benzoxazine was obtained using a three‐step synthetic method from the aromatic diamine and 2hydroxybenzaldehyde as starting materials. Curing kinetics was investigated by nonisothermal differential scanning calorimetry (DSC) at different heating rates and by FTIR spectroscopy. The curing of mixtures of bis(m‐aminophenyl)methylphosphine oxide based benzoxazine and glycidylether or benzoxazine of bisphenol A has been studied. In all samples the molar ratio of benzoxazine monomers or the benzoxazine‐epoxy system was varied to achieve different phosphorus content. The phosphorus‐containing polybenzoxazines have been characterized by dynamic mechanical and thermogravimetric analysis. Limiting oxygen index values indicate good flame retardant properties. Another alternative to incorporate phosphorus or silicon in benzoxazine‐epoxy systems have been by copolymerisation of the benzoxazine of bisfenol A with Gly‐P and Gly‐Si. In all samples the molar ratio of the benzoxazine‐epoxy system was varied to achieve different phosphorus or silicon content. Their thermal, dynamomechanical and flame retardant properties were evaluated. The high limiting oxygen index values confirmed that the phosphorus‐containing benzoxazine‐epoxy resins are effective flame retardants, but no efficiency of silicon on flame retardation was observed.