Several fluorenone alkynyl based oligo conjugated molecules were synthesized and characterized. Most compounds exhibited UV-Vis absorption onset at ca. 500 nm and a PL emission onset of ~329-370 nm, with excimer emission suspected from most systems near ~530-560 nm. Experimentally determined EHOMO and ELUMO energies range from -6.02 to -5.73 eV and -3.47 and 3.55 eV, respectively, with the lowest experimental Eg lying at -2.26 eV for 2-(trimethoxyphenylacetylene)-fluorenone. Cyclic voltammetry indicates quasi-reversible reduction for all systems, with 2,7-bis(nitrophenylacetylene)fluorenone exhibiting a high reduction potential of -1.25 eV. Only 2,7-bis(trimethoxyphenylacetylene)fluorenone exhibited a quasi-reversible oxidation, due to electron rich methoxy substituents. Diketopyrrolopyrrole systems as electron acceptors were also explored.

The tandem solar cell concept is a promising approach to improve the efficiency of photovoltaic devices. However, characterization of tandem solar cell devices is challenging since correct efficiency determination demands special experimental infrastructure as well as suitable characterization procedures. Even though the appropriate IEC and ASTM measurement standards define all that very precisely, they cannot be applied without special care to organic photovoltaics (OPV) because they were originally developed for inorganic devices. As a consequence, nowadays almost all tandem organic solar cell publications are not using correct characterization procedures, often resulting in questionable efficiency values. The aim of this work is developing a measurement procedure for tandem organic solar cells assuring their correct characterization. Therefore, at first the existing standards and measurement procedures for tandem solar cells are reviewed and challenges when applying these standards to organic solar cells are identified. As main challenges the relatively low fill factors and distinct nonlinearities of organic solar cells are identified. As preliminary experiments, single junction organic solar cells are investigated to analyze the influence of measurement parameters like bias irradiance, bias voltage, and chopper frequency on the external quantum efficiency (EQE) of organic solar cells. This results in parameter sets assuring minimized artifacts for the subsequent EQE determination of the subcells of tandem organic solar cells. The main part of this thesis presents the detailed characterization of a tandem OPV example device. First, EQE is measured and validated by two independent institutes. The EQE results are used to calculate the illumination conditions to reach AM1.5g conditions for both subcells with a multi-source sun simulator. The resulting efficiency value under standard reporting conditions (SRC) is found to be 5% lower than the efficiency measured with a single-source sun simulator. A full spectrometric characterization shows that differing fill factors of the subcells are the reason for this behavior. To overcome the main reason for the complicated measurement procedure of tandem solar cells, the inaccessibility of the individual subcells, three different approaches for the jV-characteristics determination of the subcells are presented. The so-called Bias Voltage Approach is based on EQE-measurements under varying bias voltage and needs no additional electrical contacts. Therefore, it can be applied to existing devices. The Voltage Contact Approach as well as the Current Contact Approach require in changed stack designs. Therefore, they cannot be applied to existing devices but give more accurate results. Finally, a procedure for characterizing tandem organic solar cells is formulated. This procedures aims at giving practical advice how to characterize tandem organic solar cells to achieve results conforming to the measurement standards and being as accurate and reproducible as possible. Hence, this thesis attempts to establish standards for a correct measurement of tandem organic solar cells of which other emerging solar cell technologies can profit as well.

Organic solar cells promise electricity generation at very low cost, and higher installation flexibility as compared to inorganic solar cells. The lower cost is achieved by cheaper semiconductors and easier manufacturing processes. The flexibility is naturally given by these ultra-thin, amorphous layers. Also the power conversion efficiency can be high enough for many applications. The organic molecules have to withstand the constant excitation by photons, transport of energy in form of excitons and charge. A small but significant amount of these photons has energy over the absorption gap, the excess of energy must be released without breaking the molecular bonds. In consequence, the solar cells can also heat up to temperatures at above 80°C. The objective of this work is to answer the question if the small molecules organic solar cells can be stable enough to operate under a very long time. The stability of organic doped layers in an organic solar cell is also addressed. This work starts with a general introduction followed by the description of the experimental procedures. The aging experiments of the solar cell were done with a self developed equipment. The fabrication of this equipment (a set of measurement boxes) was necessary to maintain the conditions, under which a solar cell can be aged, as constant as possible. The measurement boxes were used to control the electrical load of the cell, its temperature, the illumination intensity, and its electric connection to the IxV measurement equipment. A software package was also developed to control the equipment and to facilitate the work and visualization of the high volume of collected data. The model solar cells chosen for the aging experiments were donor-acceptor heterojunctions devices formed with the well-known materials C60 and ZnPc. Two basic different structures were analyzed, because they offered reasonable performance and potentially long lifetime: the flat heterojunction (FHJ) and the mixed heterojunction in a Metal-Insulator-p-Semiconductor (m-i-p) configuration. Variations of the FHJ and of the m-i-p structures are also used to verify the limits of the stability of electrically p- and n- doped organic semiconducting layers. The least stable solar cells are the FHJ devices. These devices show a fast initial decrease of all their characteristic conversion parameters but the Voc. After a few hundred hours, the saturation current (current under a reverse bias of 1 V) was almost stable. The saturation current is related to the number of absorbing centers, the decrease indicates that the degradation of the absorbing centers has stopped. With wavelength resolved external quantum efficiency measurements and chemical analysis, it was found that the degradation is related to the oxidation of C60. It was also shown that the use of organic dopants do not significantly affect the lifetime. The results show that the m-i-p solar cells are more stable than the FHJ devices. They are also stable under high temperatures up to 105°C. Outdoor testing also showed that the solar cells remained chemically, electrically and mechanically stable during a 900 h test.

In today’s society many non-renewable and environmentally harming energy sources are used to facilitate people’s everyday energy demands. This causes ecosystems to break down, global temperatures to rise, pollution and many more critical long lasting problems. By replacing non-renewable energy sources and taking advantage of the 100% renewable energy source, light, these problems will diminish. This project has been in collaboration with a company called Epishine who develop indoor organic solar cell devices to be able to replace conventual battery driven electrical devices with solar power harvested from indoor light. Since there is no good existing contacting solution, for Epishine to be able to enter the market, a contact solution between their solar cell device and the electrical devices it will power has to be developed. This thesis focuses on developing, designing, testing and evaluating the performance of new contact solutions for encapsulated flexible organic printed solar cells with the feasibility, viability, scalability and durability in focus. This project was conducted by first performing a literature study, thereafter, establishing a baseline for future referencing of new contact solutions and the main part, developing new concepts and evaluating them. By using the design thinking method, an iterative process could take place, allowing for a constant flow of new ideas whilst testing concepts throughout the project. The baseline tests were successful and the hypothesis of organic materials degrading over time was confirmed. From the many sub-concepts and production methods for a new contacting solution, two concepts showed promising results and were merged into one main concept. Two devices were created with the new concept, one functional device and one showing the design. To conclude, the thesis resulted in a functional solar cell device with a new contact solution which shows great potential and a new production method which enables all organic printed electronics to be design and developed in a more compact and component dense design. This production method is beneficial to not only Epishine, but everywhere where printed electronics are used and need to be optimized due to restrictions such as space and weight. / I dagens samhälle används många icke-förnybara energikällor för att underlätta människans vardagliga behov men skadar samtidigt miljön. Detta leder till att hela ekosystem fallerar, den globala temperaturen stiger, giftiga ämnen släpps fria och flera kritiska, långvariga problem skapas. Genom att byta ut icke-förnybara energikällor och istället dra nytta av den 100 % förnybara energikällan, ljus, kommer dessa ovanstående problem att minska. Detta projekt har varit i samarbete med ett företag vid namn Epishine som utvecklar organiska solcellsenheter för inomhusbruk, för att kunna ersätta konventionella batteridrivna elektriska apparater med solenergi tillvaratagen av inomhusbelysning. I dagsläget finns det ingen bra kontaktlösning mellan solcellsenheten och den apparat den ska driva, vilket är ett av Epishines större problem i nuläget, som hindrar dem från att kunna slå igenom på marknaden. Denna avhandling fokuserar på att utveckla, designa, testa och utvärdera prestandan av nya kontaktlösningar för inkapslade flexibla organiska solceller. Projektet började med en litteraturstudie, därefter etablerades en ”baseline” för att kunna jämföra de nya kontaktlösningarna. Största delen av rapporten handlar om att utveckla och testa nya kontaktlösningar för att sedan utvärdera dem. Genom att använda ”Design thinking” processen, kunde en iterativ process äga rum, vilket möjliggjorde ett konstant flöde med nya idéer som genererades samtidigt som koncept och prototyper utvecklades och utvärderades. Resultaten av ”baseline”-testerna var framgångsrika och hypotesen om att de konduktiva egenskaperna av organiska material försämras med tiden bekräftades. Från alla delkoncept och potentiella produktionsmetoderna för en ny kontaktlösning visade två koncept lovande resultat och slogs därför samman till ett huvudkoncept. Två olika solcellsenheter skapades med den nya kontaktlösningen implementerad. En funktionell enhet skapades och en enhet som visar layouten och designen. Sammanfattningsvis resulterade avhandlingen i en funktionell solcellsenhet med en ny kontaktlösning som visar stor potential samt en ny produktionsmetod som gör att all organisk tryckt elektronik kan designas och tillverkas i en mer kompakt och komponenttät design. Denna produktionsmetod är en fördel inte bara för Epishine utan också överallt där tryckt elektronik används och behöver optimeras i form av utrymme och vikt.

Le contexte actuel de forte croissance des besoins en énergie dans le monde nécessite une diversification de sa production, notamment vers des sources renouvelables tout en limitant autant qu’il est possible l’émission de gaz à effet de serre. Parmi les énergies renouvelables une des plus prometteuses et abondantes est l’énergie solaire et il apparaît évident que l’énergie solaire, thermique ou photovoltaïque, représente un enjeu crucial pour diminuer la consommation d’énergie fossile. Actuellement 90 % des générateurs solaires sont élaborés en silicium cristallin, ce qui pose un problème d’approvisionnement en matière première, les producteurs de silicium n’ayant pas su anticiper la forte expansion de la filière solaire. Des concepts innovants présentent une forte potentialité en termes de coût de production et d’application, notamment les filières organiques et hybrides (organique/oxyde métallique). En Europe, la France est très active dans ce domaine de recherche, en particulier en ce qui concerne l’utilisation de nouveaux matériaux nanostructurés organiques ou de structures hybrides. C'est pourquoi Disasolar, une start-up française spécialisée dans le photovoltaïque souple, souhaite développer cette activité en élaborant des modules solaires souples par impression jet d'encre. Les objectifs de cette thèse sont d'étudier des nouveaux matériaux d'interface imprimables et d'évaluer l'effet de la dimension des nanoparticules sur la topologie et les performances des dispositifs. Et dans un deuxième temps l'étude portera sur l'impression des matériaux d'interface et la stabilité des cellules solaires organiques. / The current context of strong growth in energy demands in the world requires diversification of its production, in particular towards renewable sources while limiting as far as possible the emission of greenhouse gases. Among the most promising and abundant renewable energies is solar energy and it is evident that solar, thermal or photovoltaic energy represents a crucial issue to reduce the consumption of fossil energy. Currently 90% of the solar generators are made of crystalline silicon, which poses a problem of supply of raw material, as silicon producers did not know how to anticipate the strong expansion of the solar sector. Innovative concepts present a high potential in terms of cost of production and application, in particular organic and hybrid (organic / metal oxide) dies. In Europe, France is very active in this area of research, particularly with regard to the use of new organic nanostructured materials or hybrid structures. This is why Disasolar, a French start-up specializing in flexible photovoltaics, wants to develop this activity by developing flexible solar modules by inkjet printing. The objectives of this thesis are to study new printable interface materials and to evaluate the effect of nanoparticle size on the topology and performance of devices. And secondly, the study will focus on the printing of interface materials and the stability of organic solar cells.

This work investigates the encapsulation of organic light-emitting diodes (OLEDs) and organic solar cells (OSCs) in order to extend their lifetimes. Despite their unquestioned benefits, such as low material consumption and flexibility, their short lifetime span in ambient atmosphere is a clear disadvantage. For protection purposes, the devices are required to be encapsulated with permeation barriers. An appropriate barrier must have a water vapor transmission rate (WVTR) below 10^(-4) g(H2O) m^(-2) d^(-1) – below a monolayer of water permating through the barrier per day. Thus to design such barriers, a highly sensitive method for their evaluation is the primary requirement. Much fundamental research and setup development is thus performed in this work in order to improve the electrical calcium test to a sufficient level of sensitivity, reliability, and measurement capacity. The electrical calcium test uses a thin film of ignoble calcium and determines the amount of incoming water based on the decrease in its electrical conductance. In order to obtain highly precise results, this work identifies the reaction product (calcium hydroxide) and electrical resistivity of evaporated calcium films ((6.2 +- 0.1) 10^(-6-) Ohm cm). In contrast to a common assumption for the evaluation of calcium tests, calcium is found to corrode laterally inhomogeneous. However, it is shown theoretically and experimentally that this inhomogeneity does not distort the WVTR-measurement. Besides these fundamental investigations, calcium test design problems – as well as their solutions – are shown such as the damaging of an inorganic barrier film by an adjacent calcium sensor. As a result, a powerful and reliable measurement setup has been created. Subsequently, an investigation of a variety of barriers is presented, based on calcium tests, but also on device encapsulation and electroplating into defects: Permeation through evaporated aluminum thin films is found to occur mainly through macroscopic defects (radii > 0.4 μm) characterizable by optical inspection. Barriers made via atomic layer deposition (ALD) show improved performance with increasing layer thickness. Using ALD on foils provides excellent but, thus far, unreliable barriers. Permeation through bare polymer foils as well as sputtered zinc tin oxide (ZTO) increases roughly linear with increasing humidity and the measured WVTRs are highly comparable to reference values. The POLO barrier with a WVTR in the lower 10^(-4) g(H2O) m^(-2) d^(-1)-regime reaches the sensitivity limit of the current calcium test layout. In summary, in-depth investigations on permeation through different barriers are conducted here which reveal basic WVTR-dependencies from process- and climate parameters. Finally, water is identified as the predominant cause for device degradation, reducing the active area. For one type of both OLEDs and OSCs, the amount of water causing a 50% loss in active area (T50- water-uptake) is quantified via a comparative aging experiment involving calcium tests. Further for the case of the OSC, this T50-water-uptake of (20 +- 7) mg(H2O) m^(-2) is shown to be independent of climate conditions. As a result, the previously unspecific request for an aimed device lifetime can now be translated into a specific requirement for the permeation barrier: a water vapor transmission rate. Regarding the field of encapsulation, this work improves an essential measurement technique, characterizes a variety of permeation barriers, and investigates degradation of devices by ambient gases. The encapsulation field still poses several open questions. This work, however, strengthens the belief that organic devices will outlive them. / Diese Arbeit untersucht die Verkapselung organischer Leuchtdioden (OLEDs) und organischer Solarzellen (OSCs), um ihre Lebensdauer zu verlängern. Trotz unbestrittener Vorteile wie geringer Materialaufwand und mechanische Flexibilität stellt die kurze Lebensdauer dieser Bauteile an Luft einen deutlichen Nachteil dar. Um sie zu schützen, müssen sie mit Permeationsbarrieren verkapselt werden. Eine geeignete Barriere zeichnet sich durch eine Wasserpermeationsrate (WVTR) unterhalb von 10^(-4) g(H2O) m^(-2) d^(-1) aus – weniger als eine Monolage Wasser pro Tag. Folglich wird zur Entwicklung einer solchen Barriere primär eine äußerst empflindliche Methode zu ihrer Vermessung benötigt. Um für den elektrischen Calcium-Test ein hinreichendes Maß an Messgenauigkeit, Zuverlässigkeit und Probendurchsatz zu erzielen, werden in dieser Arbeit Grundlagenuntersuchungen sowie die Entwicklung des Messaufbaus umfassend behandelt. Der elektrische Calcium-Test bestimmt die Menge eindringenden Wassers anhand der Leitfähigkeitsabnahme einer dünnen Schicht Calcium – eines unedlen Metalls. Um eine hohe Genauigkeit zu erlangen, werden das Reaktionsprodukt (Calciumhydroxid) und der spezifische Widerstand ((6,2 +- 0,1) 10^(-6) Ohm cm) aufgedampfter Calcium-Filme bestimmt. Entgegen einer für die Auswertung von Calcium-Tests üblichen Annahme wird für Calcium ein lateral inhomogenes Korrosionsverhalten festgestellt. Allerdings kann theoretisch und experimentell nachgewiesen werden, dass hierdurch die WVTR-Messung nicht verfälscht wird. Neben diesen Grundlagenuntersuchungen werden Design-Probleme des Calcium-Tests und deren Lösung vorgestellt, z. B. die Schädigung der anorganischen Barriere durch direkten Kontakt mit dem Calcium-Sensor. Im Ergebnis ist damit ein ebenso leistungsstarker wie zuverlässiger Messaufbau entwickelt worden. Im nächsten Schritt wird die Untersuchung einer Vielzahl von Barrieren mithilfe von Calcium-Tests, aber auch Bauteil-Verkapselung und galvanischer Abscheidung in Defekten, vorgestellt: Die Permeation durch aufgedampfte Aluminium-Dünnfilme geschieht demnach im Wesentlichen durch Makro-Defekte (Radien > 0,4 μm), die einer optischen Charakterisierung zugänglich sind. Barrieren, die durch Atomlagenabscheidung (ALD) hergestellt werden, verbessern sich mit steigender Schichtdicke, wobei solche Schichten auf Folien ausgezeichnete – aber bisher unzuverlässige – Permeationsbarrieren darstellen. Sowohl für einfache Polymerfolien als auch für gesputterte Zink-Zinn-Oxid-Barrieren (ZTO) werden zum einen gute Übereinstimmungen der gemessenen WVTR mit Vergleichswerten erzielt, zum anderen wächst in beiden Fällen die WVTR grob linear mit der anliegenden Luftfeuchte. Die POLO-Barriere mit einer WVTR im unteren 10^(-4) g(H2O) m^(-2) d^(-1)-Bereich erreicht die Messgrenze des aktuellen Messaufbaus. Kurzgesagt, es werden tiefgehende Untersuchungen zur Permeation durch verschiedene Barrieren durchgeführt, die grundlegende Zusammenhänge zwischen WVTR und Prozess-/Klimabedingungen beleuchten. Schließlich wird Wasser, das die aktive Fläche reduziert, als die vorrangige Degradationsursache identifiziert. Für je eine Sorte OLEDs und OSCs wird mittels eines vergleichenden (gegenüber Calcium-Tests) Alterungsexperiments dieWassermenge bestimmt, die die aktive Fläche um 50% verringert (T50-Wasser-Aufnahme). Für die OSC wird zudem gezeigt, dass die T50-Wasser-Aufnahme von (20 +- 7) mg(H2O) m^(-2) unabhängig von den Klimabedingungen ist. Folglich kann die zuvor unspezifische Forderung nach einer angestrebten Lebensdauer nun in eine konkrete Anforderung an die Barriere übersetzt werden: eine Wasserpermeationsrate. Mit Blick auf das Feld der Verkapselung verbessert diese Arbeit eine wichtige Messmethode, charakterisiert eine Vielzahl an Permeationsbarrieren und untersucht die Bauteilalterung durch Lufteinwirkung. Auch wenn das das Forschungsfeld der Verkapselungen nach wie vor eine Reihe offener Fragen aufweist, so bestärkt diese Arbeit doch in der Hoffnung, dass die organischen Bauteile selbige überdauern werden.

This work investigates the encapsulation of organic light-emitting diodes (OLEDs) and organic solar cells (OSCs) in order to extend their lifetimes. Despite their unquestioned benefits, such as low material consumption and flexibility, their short lifetime span in ambient atmosphere is a clear disadvantage. For protection purposes, the devices are required to be encapsulated with permeation barriers. An appropriate barrier must have a water vapor transmission rate (WVTR) below 10^(-4) g(H2O) m^(-2) d^(-1) – below a monolayer of water permating through the barrier per day. Thus to design such barriers, a highly sensitive method for their evaluation is the primary requirement. Much fundamental research and setup development is thus performed in this work in order to improve the electrical calcium test to a sufficient level of sensitivity, reliability, and measurement capacity. The electrical calcium test uses a thin film of ignoble calcium and determines the amount of incoming water based on the decrease in its electrical conductance. In order to obtain highly precise results, this work identifies the reaction product (calcium hydroxide) and electrical resistivity of evaporated calcium films ((6.2 +- 0.1) 10^(-6-) Ohm cm). In contrast to a common assumption for the evaluation of calcium tests, calcium is found to corrode laterally inhomogeneous. However, it is shown theoretically and experimentally that this inhomogeneity does not distort the WVTR-measurement. Besides these fundamental investigations, calcium test design problems – as well as their solutions – are shown such as the damaging of an inorganic barrier film by an adjacent calcium sensor. As a result, a powerful and reliable measurement setup has been created. Subsequently, an investigation of a variety of barriers is presented, based on calcium tests, but also on device encapsulation and electroplating into defects: Permeation through evaporated aluminum thin films is found to occur mainly through macroscopic defects (radii > 0.4 μm) characterizable by optical inspection. Barriers made via atomic layer deposition (ALD) show improved performance with increasing layer thickness. Using ALD on foils provides excellent but, thus far, unreliable barriers. Permeation through bare polymer foils as well as sputtered zinc tin oxide (ZTO) increases roughly linear with increasing humidity and the measured WVTRs are highly comparable to reference values. The POLO barrier with a WVTR in the lower 10^(-4) g(H2O) m^(-2) d^(-1)-regime reaches the sensitivity limit of the current calcium test layout. In summary, in-depth investigations on permeation through different barriers are conducted here which reveal basic WVTR-dependencies from process- and climate parameters. Finally, water is identified as the predominant cause for device degradation, reducing the active area. For one type of both OLEDs and OSCs, the amount of water causing a 50% loss in active area (T50- water-uptake) is quantified via a comparative aging experiment involving calcium tests. Further for the case of the OSC, this T50-water-uptake of (20 +- 7) mg(H2O) m^(-2) is shown to be independent of climate conditions. As a result, the previously unspecific request for an aimed device lifetime can now be translated into a specific requirement for the permeation barrier: a water vapor transmission rate. Regarding the field of encapsulation, this work improves an essential measurement technique, characterizes a variety of permeation barriers, and investigates degradation of devices by ambient gases. The encapsulation field still poses several open questions. This work, however, strengthens the belief that organic devices will outlive them.:1 Introduction 2 Fundamentals 2.1 Organic Semiconductors 2.2 Organic Solar Cells 2.3 Organic Light-Emitting Diodes 2.4 Humidity, Evaporation, and Condensation 2.5 Principles of Permeation 3 State of the Art in Barrier Production and Evaluation 3.1 Barrier Technologies 3.2 Permeation Measurement Techniques 4 Experimental 4.1 Description of the As-Delivered Substrates 4.2 Treatment of Substrates 4.3 Deposition of Calcium Tests and Devices by Thermal Evaporation 4.4 Permeation Barriers by Atomic Layer Deposition 4.5 Defect Evaluation by Electrodeposition 5 Calcium for Permeation Tests Properties and Corrosion Behavior 5.1 Electrical Conductance and Optical Transmission 5.2 Corrosion Product 5.3 Laterally Inhomogeneous Calcium Corrosion 5.4 Implications for Optical and Electrical Calcium Corrosion Tests 6 Electrical Calcium Test 6.1 Measurement Setup 6.2 Calcium Test Layout 6.3 Comparability with Other Methods – OE-A Round Robin 6.4 Limitations and Future Prospects of the Electrical Calcium Test 6.5 Setup and Layout – Conclusions 7 Barrier Investigation 7.1 Thermally Evaporated Aluminum as Thin Film Encapsulation 7.2 ZnSnO (Magnetron Sputtered) on Polymer Foil 7.3 Al2O3 (ALD) on Polymer Substrate and as Thin Film Encapsulation 7.4 Summary and Conclusions for the Investigated Barriers 8 Encapsulation and Lifetime of Devices 8.1 Phenomenology of Device Degradation in Ambient Atmosphere 8.2 OLED Degradation Investigated by Calcium Tests 8.3 OSC Degradation Investigated by Calcium Tests 8.4 Discussion 8.5 Conclusions 9 Conclusions and Future Prospects Bibliography Acknowledgements Statement of Authorship / Diese Arbeit untersucht die Verkapselung organischer Leuchtdioden (OLEDs) und organischer Solarzellen (OSCs), um ihre Lebensdauer zu verlängern. Trotz unbestrittener Vorteile wie geringer Materialaufwand und mechanische Flexibilität stellt die kurze Lebensdauer dieser Bauteile an Luft einen deutlichen Nachteil dar. Um sie zu schützen, müssen sie mit Permeationsbarrieren verkapselt werden. Eine geeignete Barriere zeichnet sich durch eine Wasserpermeationsrate (WVTR) unterhalb von 10^(-4) g(H2O) m^(-2) d^(-1) aus – weniger als eine Monolage Wasser pro Tag. Folglich wird zur Entwicklung einer solchen Barriere primär eine äußerst empflindliche Methode zu ihrer Vermessung benötigt. Um für den elektrischen Calcium-Test ein hinreichendes Maß an Messgenauigkeit, Zuverlässigkeit und Probendurchsatz zu erzielen, werden in dieser Arbeit Grundlagenuntersuchungen sowie die Entwicklung des Messaufbaus umfassend behandelt. Der elektrische Calcium-Test bestimmt die Menge eindringenden Wassers anhand der Leitfähigkeitsabnahme einer dünnen Schicht Calcium – eines unedlen Metalls. Um eine hohe Genauigkeit zu erlangen, werden das Reaktionsprodukt (Calciumhydroxid) und der spezifische Widerstand ((6,2 +- 0,1) 10^(-6) Ohm cm) aufgedampfter Calcium-Filme bestimmt. Entgegen einer für die Auswertung von Calcium-Tests üblichen Annahme wird für Calcium ein lateral inhomogenes Korrosionsverhalten festgestellt. Allerdings kann theoretisch und experimentell nachgewiesen werden, dass hierdurch die WVTR-Messung nicht verfälscht wird. Neben diesen Grundlagenuntersuchungen werden Design-Probleme des Calcium-Tests und deren Lösung vorgestellt, z. B. die Schädigung der anorganischen Barriere durch direkten Kontakt mit dem Calcium-Sensor. Im Ergebnis ist damit ein ebenso leistungsstarker wie zuverlässiger Messaufbau entwickelt worden. Im nächsten Schritt wird die Untersuchung einer Vielzahl von Barrieren mithilfe von Calcium-Tests, aber auch Bauteil-Verkapselung und galvanischer Abscheidung in Defekten, vorgestellt: Die Permeation durch aufgedampfte Aluminium-Dünnfilme geschieht demnach im Wesentlichen durch Makro-Defekte (Radien > 0,4 μm), die einer optischen Charakterisierung zugänglich sind. Barrieren, die durch Atomlagenabscheidung (ALD) hergestellt werden, verbessern sich mit steigender Schichtdicke, wobei solche Schichten auf Folien ausgezeichnete – aber bisher unzuverlässige – Permeationsbarrieren darstellen. Sowohl für einfache Polymerfolien als auch für gesputterte Zink-Zinn-Oxid-Barrieren (ZTO) werden zum einen gute Übereinstimmungen der gemessenen WVTR mit Vergleichswerten erzielt, zum anderen wächst in beiden Fällen die WVTR grob linear mit der anliegenden Luftfeuchte. Die POLO-Barriere mit einer WVTR im unteren 10^(-4) g(H2O) m^(-2) d^(-1)-Bereich erreicht die Messgrenze des aktuellen Messaufbaus. Kurzgesagt, es werden tiefgehende Untersuchungen zur Permeation durch verschiedene Barrieren durchgeführt, die grundlegende Zusammenhänge zwischen WVTR und Prozess-/Klimabedingungen beleuchten. Schließlich wird Wasser, das die aktive Fläche reduziert, als die vorrangige Degradationsursache identifiziert. Für je eine Sorte OLEDs und OSCs wird mittels eines vergleichenden (gegenüber Calcium-Tests) Alterungsexperiments dieWassermenge bestimmt, die die aktive Fläche um 50% verringert (T50-Wasser-Aufnahme). Für die OSC wird zudem gezeigt, dass die T50-Wasser-Aufnahme von (20 +- 7) mg(H2O) m^(-2) unabhängig von den Klimabedingungen ist. Folglich kann die zuvor unspezifische Forderung nach einer angestrebten Lebensdauer nun in eine konkrete Anforderung an die Barriere übersetzt werden: eine Wasserpermeationsrate. Mit Blick auf das Feld der Verkapselung verbessert diese Arbeit eine wichtige Messmethode, charakterisiert eine Vielzahl an Permeationsbarrieren und untersucht die Bauteilalterung durch Lufteinwirkung. Auch wenn das das Forschungsfeld der Verkapselungen nach wie vor eine Reihe offener Fragen aufweist, so bestärkt diese Arbeit doch in der Hoffnung, dass die organischen Bauteile selbige überdauern werden.:1 Introduction 2 Fundamentals 2.1 Organic Semiconductors 2.2 Organic Solar Cells 2.3 Organic Light-Emitting Diodes 2.4 Humidity, Evaporation, and Condensation 2.5 Principles of Permeation 3 State of the Art in Barrier Production and Evaluation 3.1 Barrier Technologies 3.2 Permeation Measurement Techniques 4 Experimental 4.1 Description of the As-Delivered Substrates 4.2 Treatment of Substrates 4.3 Deposition of Calcium Tests and Devices by Thermal Evaporation 4.4 Permeation Barriers by Atomic Layer Deposition 4.5 Defect Evaluation by Electrodeposition 5 Calcium for Permeation Tests Properties and Corrosion Behavior 5.1 Electrical Conductance and Optical Transmission 5.2 Corrosion Product 5.3 Laterally Inhomogeneous Calcium Corrosion 5.4 Implications for Optical and Electrical Calcium Corrosion Tests 6 Electrical Calcium Test 6.1 Measurement Setup 6.2 Calcium Test Layout 6.3 Comparability with Other Methods – OE-A Round Robin 6.4 Limitations and Future Prospects of the Electrical Calcium Test 6.5 Setup and Layout – Conclusions 7 Barrier Investigation 7.1 Thermally Evaporated Aluminum as Thin Film Encapsulation 7.2 ZnSnO (Magnetron Sputtered) on Polymer Foil 7.3 Al2O3 (ALD) on Polymer Substrate and as Thin Film Encapsulation 7.4 Summary and Conclusions for the Investigated Barriers 8 Encapsulation and Lifetime of Devices 8.1 Phenomenology of Device Degradation in Ambient Atmosphere 8.2 OLED Degradation Investigated by Calcium Tests 8.3 OSC Degradation Investigated by Calcium Tests 8.4 Discussion 8.5 Conclusions 9 Conclusions and Future Prospects Bibliography Acknowledgements Statement of Authorship

The work presented in this thesis is primarily concerned with the synthesis and characterization of large, linear heteroacenes and their derivatives. We have been able to significantly expand on the types of materials available for application in organic electronic device architectures. In particular, the work focused on solution processible and novel derivatives of thiadiazoles, diazatetracenes, diazapentacenes, tetrazapentacences, and N,N-dihydrotetraazaheptacene. Extensive computational studies have been performed in order to better understand the optoelectronic properties of these materials. Although no devices have been fabricated that show appreciable hole or electron mobility, the properties of these materials are very promising. Besides our work on organic electronic materials for application in optoelectronic devices, we have also been able to develop, via the Click reaction, a series of aqueous metal sensors for copper (II), nickel (II), and silver (I) based upon fluorescence quenching. The use of a modified Stern-Volmer equation was necessary to fit the data in order to obtain binding constants. The exploration of new materials and their properties in the area of organic electronics is an exciting field for the synthetic organic chemist, as the goals associated with this work strive to impact humanity in a positive manner by reducing energy costs.

La technologie photovoltaïque (PV) est considérée une solution très prometteuse à la crise de l'énergie. Bien que le marché du PV soit actuellement dominé par des dispositifs à base de minéraux, ces systèmes présentent des coûts de production élevés et de nombreux problèmes environnementaux. Ces aspects limitent leur application. Les cellules solaires organiques à base de polymères (OPV) sont de prometteuses sources d'énergie renouvelable en raison de leur faible coût de production et grâce à leur nature déformable. En raison de ses propriétés électroniques et de la haute mobilité d'électrons, de petites molécules dérivées du fullerène C60 sont largement utilisées dans la production OPV à grande échelle. Toutefois, les propriétés morphologiques des dérivés du C60 diminuent la stabilité des dispositifs. En effet, le C60 subit facilement le phénomène d’auto-agrégation lors de l'utilisation de la cellule. L'aptitude au traitement du C60 peut être améliorée en l’incorporant dans un polymère. Ces systèmes sont déjà décrits dans la littérature, mais reposent en général sur une synthèse en plusieurs étapes qui pourraient affecter les propriétés électroniques du C60 ainsi que donner des produits insolubles en raison de la réaction de réticulation. L'objectif de ce travail est de préparer des polymères innovants basés sur le fullerène (C60) pour les dispositifs photovoltaïques et électroniques, à l'aide d’une chimie du C60 bien connue et en se basant sur des procédés fiables. À l'Université de Pau (au sein de l’équipe EPCP), après les synthèses de petites molécules qui ont étés utilisées en tant que co-monomères, deux différentes voies de synthèse ont été exploitées afin d'obtenir oligo- et polyfullerènes contenant le C60 dans leur chaîne principale. La première voie exploitée, est basée sur la réaction « Atom Transfer Radical Addition Polymerisation » (ATRAP), qui a déjà été utilisée pour la préparation de main-chain polyfullerenes. Avec cette méthode, des composés très solubles ayant des poids moléculaires variables ont été préparés. La deuxième voie a été découverte dans ce travail de thèse et exploite une chimie du C60 bien connue pour obtenir des « main-chain » polyfullerènes qui présentent un haut poids moléculaire et qui sont bien solubles dans les solvants courants. Des études préliminaires ont été effectuées dans le but de comprendre les effets des paramètres de réaction et la cinétique de la polymérisation. Les matériaux ont été caractérisés par chromatographie d’exclusion stérique, SEC, spectroscopie RMN, et à travers spectroscopie UV-vis et IR. Des analyses thermiques (TGA et DSC) complètent les caractérisations. Le C60, ainsi que son dérivé, [6,6] -phényl-C61-butyrique ester méthylique d'acide (PCBM), ont été exploités en tant que monomères dans les réactions de polymérisation. Un séjour de neuf mois (cotutelle) à l'université de Tübingen, en Allemagne, a permis d'étudier les matériaux synthétisés par spectroscopies XPS et UPS. Le but de ces études était d'obtenir une meilleure compréhension des niveaux énergétiques des oligo- et polyfullerènes. Des couches minces de composés ont été déposées sur différents substrats par des procédés en solution (doctor blade ou spin coating) pour obtenir des échantillons ex-situ pour les analyses. Des échantillons de couches actives contenant des polyfullerène ont également été préparés lors d'un court séjour (une semaine) à BELECTRIC OPV GmbH, Nuremberg (Allemagne). Les échantillons ont été analysés par microscopie optique et microscopie AFM dans le cadre d’une étude sur la stabilité thermique de la couche active à l'Université de Tübingen. Ces études ont été réalisées aussi grâce à la collaboration avec des chercheurs de BELECTRIC OPV GmbH, qui ont intégré les composés dans des dispositifs et réalisé des expériences complémentaires et comparables. Comme tendances générales, les composés améliorent la stabilité des dispositifs quand les derniers sont soumis à un stress thermique. / Photovoltaic technology (PV) makes it possible to directly convert sunlight into electricity and it is seen as a very promising solution to the current energy crisis. Although the PV market is dominated by inorganic-based devices, those systems present high production costs and deployment issues that limit their application. Polymer-based organic solar cells (OPVs) are promising sources of renewable energy due to their facile, low cost production, and formable nature. Due to its electronic properties and high electron mobility, small molecule fullerene (C60 ) derivatives are widely used in large scale OPVs. However the morphological properties of C60 derivatives decrease device stability as C60 easily undergoes self-aggregation during OPV use. The processibility of C60 can be improved by incorporating it into a polymer. These systems are already described in literature but have in general a multistage synthesis that could affect the electronic properties of C60 as well as give insoluble products due to reticulative reactions. The objective of the work here presented was to prepare innovative polymers based on C60 for photovoltaic and electronic devices using reliable, well-known C60 chemistry. At the University of Pau (EPCP Lab), after the syntheses of small molecules to be used as co-monomers, two synthetic routes were used in order to obtain main- chain oligo- and polyfullerenes. The first route is based on the atom transfer radical addition polymerization (ATRAP), which has already been used for the preparation of main-chain polyfullerenes. With this method, soluble compounds with various molecular weights were prepared. The second route was discovered in this work and exploits a well-known fullerene chemistry to prepare soluble polyfullerenes with reasonably high molecular weights. Preliminary studies to understand the effect of the reaction parameters (reagents, reagents concentration, temperature, time and solvent) and the kinetics of the polymerisation were performed. Material characterisations were carried out via GPC chromatography, NMR spectroscopy, and UV-visible and IR spectroscopies. Thermal analyses (TGA and DSC) were also run to complete the characterisations. Both C60 and its derivative, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), have been exploited as monomers in the reactions. A nine-month (cotutelle) stay at Tübingen University, Germany, permitted a study of the synthesized materials by means of XPS and UPS spectroscopies. The aim of these studies was to obtain a better understanding of the energy levels pictures of the oligo- and polyfullerenes. Thin films of the compounds were deposited on different substrates via solution processes (doctor blade or spin coating) to obtain ex-situ samples for characterisation. Samples of polyfullerene-containing active layers were prepared during a short stay (1 week) at BELECTRIC OPV GmbH, Nuremberg (Germany), and analysed by optical microscopy and AFM microscopy during thermal-degradation studies at Tübingen University. These studies were completed thanks to collaborations with researchers at BELECTRIC OPV GmbH, who have incorporated the compounds into devices and performed complementary and comparable experiments. As general trends, the compounds are found to improve the stability of the devices upon thermal stresses.

Research in recent years on novel materials in organic solar cells (OSCs) have contributed to a rapid advancement in OSC efficiency. Here, OSCs with the well-studied organic semiconductors poly(3-hexylthiophene):[6,6]-phenyl C60-butyric acid methylester (P3HT:PCBM) in a bulk heterojunction structure were prepared to establish a baseline procedure for fabrication and spin-sensitive spectroscopy. Spin-sensitive spectroscopy can be used to probe the spin-dependent processes and loss mechanism in OSCs. Understanding the microscopic processes enables research targeting loss mechanisms directly, which opens up for higher efficiency OSCs. Measurements with continuous wave electrically detected magnetic resonance (cwEDMR), continuous wave electron paramagnetic resonance (cwEPR) and transient (tr)EDMR were set up and followed by an initial study on the spin-dependent processes and their influence on the photocurrent. Signals from spin-dependent processes in the samples were seen for the three experiment series carried out, and well-functioning OSCs with consistent results were prepared. This thesis and the presented baseline fabrication and experimental setup procedures provide with valuable learnings for future research in the group AG Behrends enabling fabrication and spin-sensitive studies on novel materials in OSCs. It was found that post-processing annealing at 120 C for 5 min reduces S-shape behaviour in current-voltage curves, and over all improves poor current-voltage characteristics of the OSC samples fabricated. Further, influence from PEDOT:PSS was seen in cwEPR spectroscopy, indicating the presence of traps or free radicals in the PEDOT:PSS. In cwEDMR spectroscopy of the OSCs it was shown that the spin processes of bias-induced and photo-induced charge carriers influence the photocurrent in the same way. Finally, the authors suggest that results from spin-sensitive spectroscopy of degraded OSCs cannot be applied to non-degraded OSCs.