Anledningen till att skriva om cellulosalack är att från år till år det finns allt fler möbler med sådan ytbehandlingsom hamnar på konserverings- och restaureringsverkstäder. Dessa möbler kommer framför allt från1950- och 1960-talet (när det var en av dem vanligaste typerna av ytbehandling) men även från 1920- och1930-talet. Idag har möblerna från 1900-talet blivit antikviteter och eftersökta på marknaden. Därför är demvärdefullast med sin ursprungliga ytbehandling som behöver skyddas och bevaras.Den här typen av transparent ytbehandling orsakar många problem för en konservator men jag harkoncentrerat mig på hur man partiellt kan bättra lakuner, som man kan tolka här som tomrum, brist, bortfallav transparent ytbehandling (ordet kommer från latin – lacuna, lacunae).Tidigare har den vanligaste metoden för att restaurera en möbel med förstörd cellulosaytbehandlingvarit att rensa bort den gamla och lägga på helt ny. I moderna tider är det uppenbart att det är inte särskiltmiljövänlig och hälsosamt att rensa bort och lägga på nytt cellulosalack samt med bevaringsattityd är det bättreatt reparera den gamla ytbehandlingen som är originell och autentisk. Som möbelkonservator borde manlära sig att hantera sådan ytbehandlingsproblematik.Därför finns det behov att hitta metoder och material som hjälper att fylla lakuner på ett effektivt sätt.Där har jag också värderat dem utifrån konserverings- och restaureringsgrundregler. Baserade på skriftligakällor samt på min och min handledarens erfarenhet i detta område, har jag i mitt examensarbete genompraktiska experiment presenterat och utvärderat några metoder att fylla lakuner. / The reason to write about cellulose lacquer is that from year to year there are more and more furniture withsuch transparent coatings that come to the conservation and restoration workshops. The furniture comesmainly from the 1950´s and 1960´s (when it was one of the most common type of transparent finishes) butalso from the 1920´s and 1930´s. Today the furniture from the 20th century has become antiques and soughtafter on the market. Therefore, they are still valuable with their original coatings that would need to be protectedand preserved.This type of transparent finishes causes many problems for the conservator, but I have concentratedon how to partially improve the lacunae that you can interpret here as a break in continuity, gaps in transparentcoatings (the word comes from Latin – lacuna, lacunae).Earlier, the most common method of restoring a furniture with damaged transparent coatings was toremove the old and add a whole new one. In modern times, it is obvious that it is not very environmentallyfriendly and healthy to clean up and add new nitrate cellulose laquer, with conservation attitude is better torepair old finishes that are original. One should learn how to handle such transparent coatings problems.Therefore, there is a need to find methods and materials that help fill gaps effectively. I have also evaluatedthem based on preserving and restoration ground rules.Through practical experiments, based on written sources as well as on my and my supervisors experiencein this area, I have presented and evaluated some methods of filling lacunae in my bachelor thesis.

Le déterminisme du sexe est un processus qui aboutit à la séparation physique des structures à l’origine des gamètes mâles et femelles, soit sur des fleurs séparées sur une même plante, pour les espèces monoïques, soit sur des individus séparés, dans le cas des espèces dioïques. Ce mécanisme favorise la fécondation croisée et augment ainsi la variabilité génétique. Il pourrait être influencé par les facteurs endogène (génétique ou hormonal) ou environnementaux. Chez le melon, le déterminisme du sexe est contrôlé par le gène A (andromonoecious) et le gène G (gynoecious). Le gène A code pour 1-aminocyclopropane-1-carboxylique acide synthase (ACS), un enzyme impliqué dans la voie de biosynthèse d’éthylène qui inhibe le développement des étamines dans les fleurs femelles. Le gène G code pour une protéine C2H2 à doigt de zinc appartenant à la famille WIP de facteurs de transcription qui inhibe le développement des capelles dans les fleurs mâles. Chez Arabidopsis thaliana, Il y a six gènes WIP et on en sait très peu sur leur fonction moléculaire. TT1/AtWIP1 est impliqué à l’accumulation de PA dans endothélium de graines. NTT/AtWIP2 est impliqué dans le développement de TRANSMITTING TRACT de carpelle. Dans cette thèse, nous avons essayé de mettre en évidence la fonction moléculaire de gènes WIP. Dans cette étude, nous avons montré que les gènes WIP des espèces différents partiellement restaurent le phénotype de graines jaune de tt1-3 mutants et régulent positivement les gènes tardifs de biosynthèse de flavonoïdes chez Arabidopsis thaliana La complémentation fonctionnelle de mutants tt1-3 par le gène WIP de melon et le gène WIP de la mousse montre que les gènes WIP ont la même fonction globale mais diffèrent à l’échelle spatio-temporelle. Il a été montré que le second motif conservé, à l’extrémité N-terminal, du gène TT1 était essentiel pour qu’il soit fonctionnel. La substitution d’acides aminés de ce motif (N2) par des alanines diminue l’accumulation de proanthocyanidines (PA) dans l’endothélium de la graine. TT1 perturbe également le développement des pétales, des étamines et des carpelles quand il est surexprimé de manière ectopique sous le contrôle des promoteurs d’AP3 et CRC. Il a été exprimé dans les racines secondaires sous le promoteur du gène SOLITARY ROOT (SLR/IAA14) ainsi que dans les stipules sous le promoteur du gène GLABROUS1 (GL1). TT1 inhibe le développement des racines secondaires et la formation des trichomes sur les feuilles. Dans cette étude, nous avons constaté que TT1 agit comme un inhibiteur de la formation d’organes quand il est exprimé de manière ectopique. On cherchera dans cette étude à comprendre les mécanismes mis en jeu lors de l’arrêt du développement de ces organes au cours du déterminisme du sexe et a évoqué de nouvelles pistes pour expliquer ce processus. / Sex determination in plants is a process that results the development of either male or female flower on the same or different individuals. This mechanism enhances the cross pollination and raises the genetic variability. It can be influenced by endogenous (genetic or hormonal) and/or external environmental factors. In melon, gene A arrests the stamen development in the female flowers and gene G arrests the development of carpel in the male flowers hence these two genes control the sex determination mechanism in melon. Gene A encodes 1-aminocyclopropane-1-carboxylic acid synthase (ACS), an enzyme which is involved in the ethylene biosynthesis pathway. Gene G encodes a C2H2 zinc finger proteins that belongs to WIP family of transcription factors. In Arabidopsis thaliana, there are six WIP genes and very little is known about their molecular function. TT1/AtWIP1 is involved in the accumulation of PA in the seed endothelium. NTT/AtWIP2 is involved in the development of transmitting tract in the carpel. In this thesis, we tried to highlight the molecular function of the WIP genes. Here we show that WIP genes from different species partially restore the yellow seed coat color phenotype of tt1-3 mutant and upregulate the late flavonoid biosynthetic genes. The functional complementation of tt1-3 mutants by WIPs from Cucumis melo and Physcomitrella patens indicates that WIP genes have the same global function but differ on the spatio-temporal level. Second conserved motif in the N-terminus of TT1 protein was found to be essential for its proper function as alanine scanning of N2 motif of TT1 decreased the accumulation of PAs in the seed endothelium. TT1 disturbed the development of petals, stamens and carpels in flower when ectopically expressed under AP3 and CRC promoter. TT1 was expressed in the lateral roots under the promoter of SOLITARY ROOT (SLR/IAA14) and in the stipules under the promoter of GLABROUS1 (GL1). TT1 was able to inhibit the development of the lateral roots and leaf trichomes. In this study, we found that TT1 can act as organ inhibitor when ectopically expressed. Our study will help us to understand the organ arrest during sex determination mechanism and will evoke new dimensions for further explanations of this process.

Denna uppsats är en beskrivning på utvecklingen av detta projekt, där fokuset handlar om teorier och fakta på ljus i samband med transparanta medium. Målet med projektet var att testa och experimentera inom det nämna området fast i 3D grafik, där resultatet är renderade bilder med analys, diskussioner och slutsatser. / This essay describes the development of this project, where the focus is on theories and facts about light and transparent mediums. The aim of the project was to test and experiment the mentioned area in 3D graphics, where the results are single rendered images with analysis, discussions and conclusions.

En av grundpelarna i alla hållbara system är införandet av en cirkulär ekonomi, som främjar återanvändning och återvinning av material. Plast är en av i utmaning i detta avseende på grund av den stora produktionsvolymen variation i sorter och långsamma nedbrytn. Ett förslag till lösning på dessa problem, som det har forskats allt mer om under de senaste decennierna, är att ersätta syntetiska plaster med lämpliga biobaserade alternativ. Detta arbete syftade till att utforska två möjligheter i detta avseende, (1) Transparent trä (TW) och (2) Lim för trä från en förnybar källa.  Utvärderingen av chitosan som ersättning för de syntetiska delarna av dessa material var det primära syftet med denna studie. TW utnyttjar de inneboende önskvärda egenskaperna hos trä och ökar dess användningsområden genom att ändra dess optiska egenskaper, men behöver en impregneringsmatris, som är en syntetisk polymer, för sin tillverkning. I detta arbete studerades variationen av kitosanimpregnering med tryck och torkningsförhållanden. Mikroskopi, gravimetri, kontaktvinkel och dynamisk mekanisk analys användes för att mäta effektiviteten hos de utvecklade metoderna. Alternativ till syntetiska lim för trä och träkompositer behövs på grund av problem med toxicitet. Chitosans användbarhet som lim för trä har dokumenterats i stor utsträckning. Det har dock inte gjorts så mycket arbete med trälaminat, som valdes som en ett sekundärt fokus för detta arbete. Testning av limmet utfördes med hjälp av skjuvmätningar. Resultaten visade att kitosan, istället för att infiltrera trästrukturen, främst deponerades på dess yta och specifika tester för att bestämma laminatets hållfasthet föll utanför ramen för denna studie. / One of the mainstays of any sustainable system is the implementation of a circular economy, which promotes the reuse and recycling of materials. Plastics are one of the most problematic entities in this regard because of the sheer scale of production, their variety, and their recalcitrant nature. A proposed solution to this problem, one which has seen increasing research in the past decades, is replacing synthetic plastics with suitable bio-based alternatives. This work aimed to explore two possibilities in this regard, (1) Transparent wood (TW) and (2) Adhesives for wood. Evaluating the utility of chitosan as a replacement for the synthetic portions of these materials was the primary aim of this study. TW utilizes the inherently desirable properties of wood and increases its avenues of application by changing its optical properties but needs an impregnation matrix, which is a synthetic polymer, for fabrication. This work studied the variation of chitosan impregnation with pressure and drying conditions. Microscopy, gravimetry, water contact angle and dynamic mechanical analysis were used to gauge the efficacy of our methods. Alternatives to synthetic adhesives for wood and wood-composites are needed because of their associated problems with toxicity. Chitosan’s utility as an adhesive for wood has been documented to a considerable extent. However, not much work has been done with wood laminates, which were chosen as a secondary focal point of this work. Adhesive testing was carried out via lap-shear measurements. Results indicated that chitosan, instead of infiltrating the wood structure, was primarily deposited on its surface and specific tests for determining laminate strength fell out of the scope of this study.

In dieser Arbeit wurden einerseits die elektronischen Eigenschaften von Graphenen und andererseits die Verwendung von Graphenen und Kohlenstoff-basierten Hybridmaterialien als transparente Elektroden untersucht. Entsprechend ist der erste, umfangreichere Teil der Arbeit Grundlagen-orientiert und fokussiert auf die elektrostatische Wechselwirkung zwischen Graphen und dem Substrat Glimmer. Der zweite, kleinere Teil befasst sich mit der Entwicklung leitfähiger Tinten auf der Basis von Graphenen und anderen Kohlenstoff-basierten Hybridmaterialien für Anwendungen in der druckbaren Elektronik, insbesondere für die Herstellung transparenter Elektroden. Graphen auf Glimmer ist ein sehr wohldefiniertes System, in dem das Graphen über mehrere Quadratmikrometer atomar flach ist. Schichtdickenabhängige Variationen des Oberflächenpotentials von einzel- und mehrlagigen Graphenen auf Glimmer wurden mittels Kelvin Probe Rasterkraftmikroskopie untersucht. Damit konnte die elektrostatische Abschirmlänge von Graphen auf Glimmer bestimmt werden. Lokale Variationen des Oberflächenpotentials innerhalb einer Graphenlage, verursacht durch eingeschlossene Wasserschichten zwischen Graphen und Glimmer, wurden mit Rasterkraftmikroskopie, elektrostatischer Rasterkraftmikroskopie und der Raman-Spektroskopie untersucht. Dies ermöglichte es, die Dotierung von Graphen durch eingeschlossene Wasserschichten zu quantifizieren. Außerdem wurde gezeigt, dass Graphen auf molekular modifiziertem Glimmer lokal auf der Nano-Skala dehnbar ist. Dabei wurde der Glimmer durch das Aufbringen von dendronisierten Polymeren verschiedener Generationen auf Nanometer-Skala modifiziert. Dies eröffnet neue Möglichkeiten, die lokalen elektronischen Eigenschaften von Graphen durch Dehnung zu kontrollieren.Schließlich wurden Kohlenstoff-basierte leitfähige Tinten hergestellt, daraus transparente Elektroden hergestellt, und die Formulierungen der Tinten für das Drucken auf Plastiksubstrate optimiert. / This work focusses on the electronic properties of graphene on the one hand, and on the application of graphenes and other carbon-based hybrid materials for transparent electrodes on the other hand. Accordingly, the first part of the work, which is the larger one, is of fundamental nature and focusses on the electronic interaction between graphene and mica as a substrate. The second, smaller part deals with the design of novel conductive inks based on graphene and other carbon-based hybrid materials for applications in printed electronics, in particular for the production of transparent electrodes. Graphene on mica is a very well defined system, which provides atomically flat graphene extending over several square micrometers. Layer-dependent surface potential variations of single and few layered graphenes on mica were probed with Kelvin Probe Force Microscopy. This allowed to estimate the screening length of graphene on mica. Local variations of the surface electrostatic potential above single layer graphene, originating from confined fluid interfacial monolayers of water between the mica and the graphene, were monitored with Scanning Force Microscopy, Electrostatic Scanning Force Microscopy and Raman spectroscopy. This allowed to quantify the doping of graphene by the confined water layers. Exfoliation of graphene onto adsorbed nanostructures on mica allowed to control the strain of graphene at the nano-scale. Nanostructuring was achieved by first coating mica with submonolayers of dendronized polymers of different generations and subsequently depositing graphene. This approach provides new opportunities for the control of the electronic properties of graphene by strain.Finally, novel conducting carbon-based inks were designed and transparent electrodes were fabricated therefrom. The formulations of the inks were optimized for printing on plastic substrates.

Amorphous oxide semiconductor (AOS) thin-film transistors (TFTs) constitute the central theme of this thesis. Within this theme, three primary areas of focus are pursued. The first focus is the realization of a transparent three-stage ring oscillator with buffered output and an output frequency in the megahertz range. This leads to the possibility of transparent radio frequency applications, such as transparent RFID tags. At the time of its fabrication, this ring oscillator was the fastest oxide electronics ring oscillator reported, with an output frequency of 2.16 MHz, and a time delay per stage of 77 ns. The second focus is to ascertain whether a three-terminal device (i.e., a TFT) is an appropriate structure for conducting space-charge-limited-current (SCLC) measurements. It is found that it is not appropriate to use a diode-tied or gate-biased TFT configuration for conducting a SCLC assessment since square-law theory shows that transistor action alone gives rise to I proportional to V² characteristics, which can easily be mistakenly attributed to a SCLC mechanism. Instead, a floating gate TFT configuration is recommended for accomplishing SCLC assessment of AOS channel layers. The final focus of this work is to describe an assessment procedure appropriate for determining if a dielectric is suitable for use as a TFT gate insulator. This is accomplished by examining the shape of a MIM capacitor's log(J)-ξ curve, where J is the measured current density and ξ is the applied electric field. An appropriate dielectric for use as a TFT gate insulator will have a log(J)-ξ curve that expresses a clear breakover knee, indicating a high-field conduction mechanism dominated by Fowler-Nordheim tunneling. Such a dielectric produces a TFT with a minimal gate leakage which does not track with the drain current in a log(I[subscript D])-V[subscript GS] transfer curve. An inappropriate dielectric for use as a TFT gate insulator will have a log(J)-ξ curve that does not express a clear breakover knee, indicating that the dominate conduction mechanism is defect driven (i.e., pin-hole like shunt paths) and, therefore, the dielectric is leaky. It is shown that experimental log(J)-ξ leakage curves can be accurately simulated using Ohmic, space-charge-limited current (SCLC), and Fowler-Nordheim tunneling conduction mechanisms. / Graduation date: 2010

This work demonstrates an approach to develop low-cost, semi-transparent, long-term stable, and efficient organic photovoltaic (OPV) cells and organic light-emitting diodes (OLEDs) using various alternative electrodes such as conductive polymers, doped ZnO, and carbon nanotubes. Such electrodes are regarded as good candidates to replace the conventional indium tin oxide (ITO) electrode, which is expensive, brittle, and limiting the manufacturing of low-cost, flexible organic devices. First, we report long-term stable, efficient ITO-free OPV cells and transparent OLEDs based on poly(3,4-ethylene-dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) electrodes by using a solvent post-treatment or a structure optimization. In addition, a high performance internal light out-coupling system for white OLEDs based on PEDOT:PSS-coated metal oxide nanostructures is developed. Next, we demonstrate highly efficient ITO-free OPV cells and OLEDs with optimized ZnO electrodes doped with alternative non-metallic elements. The organic devices based on the optimized ZnO electrodes show significantly improved efficiencies compared to devices with standard ITO. Finally, we report semi-transparent OPV cells with free-standing carbon nanotube sheets as transparent top electrodes. The resulting OPV cells exhibit very low leakage currents with good long-term stability. In addition, the combination of various kinds of bottom and top electrodes for semi-transparent and ITO-free OPV cells is investigated. These results demonstrate that alternative electrodes-based OPV cells and OLEDs have a promising future for practical applications in efficient, low-cost, flexible and semi-transparent device manufacturing. / Die vorliegende Arbeit demonstriert einen Ansatz zur Verwirklichung von kostengünstigen, semi-transparenten, langzeitstabilen und effizienten Organischen Photovoltaik Zellen (OPV) und Organischen Leuchtdioden (OLEDs) durch die Nutzung innovativer Elektrodensysteme. Dazu werden leitfähige Polymere, dotiertes ZnO und Kohlenstoff-Nanoröhrchen eingesetzt. Diese alternativen Elektrodensysteme sind vielversprechende Kandidaten, um das konventionell genutzte Indium-Zinn-Oxid (ITO), welches aufgrund seines hohen Preises und spröden Materialverhaltens einen stark begrenz Faktor bei der Herstellung von kostengünstigen, flexiblen, organischen Bauelementen darstellt, zu ersetzten. Zunächst werden langzeitstabile, effiziente, ITO-freie Solarzellen und transparente OLEDs auf der Basis von Poly(3,4-ethylene-dioxythiophene):Poly(styrenesulfonate) (PEDOT:PSS) Elektroden beschrieben, welche mit Hilfe einer Lösungsmittel-Nachprozessierung und einer Optimierung der Bauelementstruktur hergestellt wurden. Zusätzlich wurde ein leistungsfähiges, internes Lichtauskopplungs-System für weiße OLEDs, basierend auf PEDOT:PSS-beschichteten Metalloxid-Nanostrukturen, entwickelt. Weiterhin werden hoch effiziente, ITO-freie OPV Zellen und OLEDs vorgestellt, bei denen mit verschiedenen nicht-metallischen Elementen dotierte ZnO Elektroden zur Anwendung kamen. Die optimierten ZnO Elektroden bieten im Vergleich zu unserem Laborstandard ITO eine signifikant verbesserte Effizienz. Abschließend werden semi-transparente OPV Zellen mit freistehenden Kohlenstoff-Nanoröhrchen als transparente Top-Elektrode vorgestellt. Die daraus resultierenden Zellen zeigen sehr niedrige Leckströme und eine zufriedenstellende Stabilität. In diesem Zusammenhang wurde auch verschiedene Kombinationen von Elektrodenmaterialen als Top- und Bottom-Elektrode für semi-transparente, ITO-freie OPV Zellen untersucht. Zusammengefasst bestätigen die Resultate, dass OPV und OLEDs basierend auf alternativen Elektroden vielversprechende Eigenschaften für die praktische Anwendung in der Herstellung von effizienten, kostengünstigen, flexiblen und semi-transparenten Bauelement besitzen.

Optically-transparent solids have a significant role in many emerging topics of fundamental and applied research, in areas related to Applied Optics and Photonics. In the functional devices based on them, the presence of ‘time-varying temperature fields’ critically limit their achievable performance, when used particularly for high power laser-related tasks such as light-generation, light-amplification, nonlinear-harmonic conversion etc. For optimization of these devices, accurate knowledge of the material thermal parameters is essential. Many optical and non-optical methods are currently in use, for the reliable estimation of the thermal parameters. The thermal diffusivity is a key parameter for dealing with ‘transient heat transport’ related problems. Although its importance in practical design for thermal management is well understood, its physical meaning however continues to be esoteric. The present effort concerns with a few investigations on the “Optical interrogation of ‘transient thermal conduction’ in dielectric solids”. In dielectric solids, the current understanding is that the conductive heat transport occurs only through phonons relevant to microscopic lattice vibrations. Introducing for the first time, a virtual linear translator motion as the basis for heat conduction in dielectric materials, the present investigation discusses an alternative physical mechanism and a new analytical model for the transient heat conduction in dielectric solids. The model brings into limelight a ‘new law of motion’ and a ‘new quantity’ which can be defined at every point in the material, through which time-varying heat flows resulting in time-varying temperature. Physically, this quantity is a measure for the linear translatory motion resulting from transient heat conduction. For step-temperature excitation it bears a simple algebraic relation to the thermal diffusivity of the material. This relationship helps to define the thermal diffusivity of a dielectric solid as the “translatory motion speed” measured at unit distance from the heat source. A novel two-beam interferometric technique is proposed and corroborated the proposed concept with significant advantages. Two new approaches are introduced to estimate thermal diffusivity of optically transparent dielectric solid; first of them involves measurement of the position dependent velocity of isothermal surface and second one depend on the measurement of position dependent instantaneous velocity of normalized moving intensity points. A ‘new mechanism’ is proposed and demonstrated to visualize, monitor and interrogate optically, the ‘linear translatory motion’ resulting from the transient heat flow due to step- temperature excitation. Two new approaches are introduced, first one is ‘mark’ and ‘track’ approach, it involves a new interaction between sample supporting unsteady heat flow with its ambient and produces optical mark. Thermal diffusivity is estimated by tracking the optical mark. Second one involves measurement of instantaneous velocity of optical mark for different step-temperature at a fixed location to estimate thermal diffusivity. A new inverse method is proposed to estimate thermal diffusivity and thermal conductivity from the volumetric specific heat capacity alone through thought experiment. A new method is proposed to predict volumetric specific heat capacity more accurately from thermal diffusivity.

This work demonstrates an approach to develop low-cost, semi-transparent, long-term stable, and efficient organic photovoltaic (OPV) cells and organic light-emitting diodes (OLEDs) using various alternative electrodes such as conductive polymers, doped ZnO, and carbon nanotubes. Such electrodes are regarded as good candidates to replace the conventional indium tin oxide (ITO) electrode, which is expensive, brittle, and limiting the manufacturing of low-cost, flexible organic devices. First, we report long-term stable, efficient ITO-free OPV cells and transparent OLEDs based on poly(3,4-ethylene-dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) electrodes by using a solvent post-treatment or a structure optimization. In addition, a high performance internal light out-coupling system for white OLEDs based on PEDOT:PSS-coated metal oxide nanostructures is developed. Next, we demonstrate highly efficient ITO-free OPV cells and OLEDs with optimized ZnO electrodes doped with alternative non-metallic elements. The organic devices based on the optimized ZnO electrodes show significantly improved efficiencies compared to devices with standard ITO. Finally, we report semi-transparent OPV cells with free-standing carbon nanotube sheets as transparent top electrodes. The resulting OPV cells exhibit very low leakage currents with good long-term stability. In addition, the combination of various kinds of bottom and top electrodes for semi-transparent and ITO-free OPV cells is investigated. These results demonstrate that alternative electrodes-based OPV cells and OLEDs have a promising future for practical applications in efficient, low-cost, flexible and semi-transparent device manufacturing. / Die vorliegende Arbeit demonstriert einen Ansatz zur Verwirklichung von kostengünstigen, semi-transparenten, langzeitstabilen und effizienten Organischen Photovoltaik Zellen (OPV) und Organischen Leuchtdioden (OLEDs) durch die Nutzung innovativer Elektrodensysteme. Dazu werden leitfähige Polymere, dotiertes ZnO und Kohlenstoff-Nanoröhrchen eingesetzt. Diese alternativen Elektrodensysteme sind vielversprechende Kandidaten, um das konventionell genutzte Indium-Zinn-Oxid (ITO), welches aufgrund seines hohen Preises und spröden Materialverhaltens einen stark begrenz Faktor bei der Herstellung von kostengünstigen, flexiblen, organischen Bauelementen darstellt, zu ersetzten. Zunächst werden langzeitstabile, effiziente, ITO-freie Solarzellen und transparente OLEDs auf der Basis von Poly(3,4-ethylene-dioxythiophene):Poly(styrenesulfonate) (PEDOT:PSS) Elektroden beschrieben, welche mit Hilfe einer Lösungsmittel-Nachprozessierung und einer Optimierung der Bauelementstruktur hergestellt wurden. Zusätzlich wurde ein leistungsfähiges, internes Lichtauskopplungs-System für weiße OLEDs, basierend auf PEDOT:PSS-beschichteten Metalloxid-Nanostrukturen, entwickelt. Weiterhin werden hoch effiziente, ITO-freie OPV Zellen und OLEDs vorgestellt, bei denen mit verschiedenen nicht-metallischen Elementen dotierte ZnO Elektroden zur Anwendung kamen. Die optimierten ZnO Elektroden bieten im Vergleich zu unserem Laborstandard ITO eine signifikant verbesserte Effizienz. Abschließend werden semi-transparente OPV Zellen mit freistehenden Kohlenstoff-Nanoröhrchen als transparente Top-Elektrode vorgestellt. Die daraus resultierenden Zellen zeigen sehr niedrige Leckströme und eine zufriedenstellende Stabilität. In diesem Zusammenhang wurde auch verschiedene Kombinationen von Elektrodenmaterialen als Top- und Bottom-Elektrode für semi-transparente, ITO-freie OPV Zellen untersucht. Zusammengefasst bestätigen die Resultate, dass OPV und OLEDs basierend auf alternativen Elektroden vielversprechende Eigenschaften für die praktische Anwendung in der Herstellung von effizienten, kostengünstigen, flexiblen und semi-transparenten Bauelement besitzen.

Afin de clarifier et caractériser les mécanismes fondamentaux de formation des réseaux étendus cellulaires et dendritiques en régime diffusif, des expériences de solidification dirigée permettant l’observation in situ en temps réel de l’interface solide-liquide d’un alliage transparent ont été réalisées dans l’instrument « DECLIC-DSI» à bord de la Station Spatiale Internationale. Des procédures spécifiques d'analyse d'images ont été développées pour caractériser les réseaux et extraire des données de référence à comparer aux modèles théoriques ou numériques. Les mécanismes d’évolution et de sélection de l'espacement primaire sont décrits et reliés à la courbure macroscopique de l'interface qui apparait comme un paramètre important de la dynamique de réseau. L’obtention de réseaux homogènes étendus nous a permis d'observer des instabilités secondaires du régime cellulaire pour la première fois dans des systèmes tridimensionnels: Oscillation et multiplet structure. Nos analyses mettent en évidence l'absence de cohérence globale de l’oscillation, exceptée dans des zones localement ordonnées dans lesquelles les oscillations de cellules voisines peuvent être synchronisées. Dans une autre gamme de paramètres de contrôle, la formation de multiplets -autre type d'instabilité secondaire- a été observée. La structure et la dynamique de ces multiplets est décrite. Enfin, des essais comparatifs ont été réalisés au sol, pour les mêmes paramètres de croissance, afin de clarifier l'influence de la convection. Les différences entre les expériences au sol et en microgravité, en particulier concernant l'espacement primaire, sont reliées à l'amplitude de la convection. / To clarify and characterize the fundamental physical mechanisms active in the formation of three-dimensional (3D) arrays of cells and dendrites, in situ monitoring of series of experiments on a transparent alloy was carried out under low gravity in the DECLIC-DSI on-board the International Space Station. Image analysis procedures have been developed to characterize the patterns and get benchmark data to compare with theoretical or numerical modelling. The mechanisms of primary spacing evolution and selection are described and related to the macroscopic interface curvature that appeared to be a critical parameter. The extended homogeneous patterns obtained in microgravity enabled us to observe secondary instabilities of the cellular pattern for the very first time in 3D patterns: cell oscillation and multiplet structure. Our analyses highlight the absence of global coherence of cell oscillations, except in locally ordered areas where synchronization of neighbor cells may happen. In another range of control parameters, another type of secondary instability has been identified that corresponds to multiplet formation; the structure and dynamics of those multiplets are also described. Finally, comparative experiments have been performed on ground with similar growth parameters to point out the influence of convection. The differences between ground and microgravity results, especially regarding the primary spacing, are related to fluid flow magnitude.