Dissertations / Theses on the topic 'Encapsulation devices'

This thesis demonstrates the effective use of low temperature molecular beam epitaxy to encapsulate planar Si:P (phosphorus-in-silicon) devices lithographically patterned by scanning tunnelling microscopy (STM) without significant redistribution of the dopants. To achieve this goal, low temperature magnetotransport is used in combination with STM, Auger electron spectroscopy and secondary ion-mass spectrometry to analyse Si:P ??-doped samples fabricated under different doping and growth conditions. An important aspect of this project is the use of large 1 ?? 1 cm2 Si(001) samples which are about five times larger than standard STM samples. The larger sample size is necessary for post-STM fabrication lithography processes in a cleanroom but presents problems for preparing atomically clean surfaces. The ability to prepare clean and atomically flat Si(001) surfaces for STM lithography on such 1 ?? 1 cm2 samples is demonstrated, and it is shown that Si:P ??-doped layers fabricated on these surfaces exhibit complete electrical activation. Two dopant sources (gaseous PH3 and solid GaP source) were investigated to assess their compatibility with STM-lithography on the H:Si(001) surface. The findings show that while the PH3 and GaP sources result in near identical electrical qualities, only PH3 molecules are compatible with H-resist based lithography for controlled nano-scale doping. For achieving complete activation of the P dopants, it is shown that an anneal to ??? 350 ???C to incorporate P atoms into the Si surface prior to encapsulation is critical. While it is known that the presence of H during growth degrades the quality of Si epitaxy, investigations in this thesis indicate that it has no significant effect on dopant activation. Systematic studies performed to assess the impact of growth temperature recommend an encapsulation temperature of 250 ???C for achieving optimal electrical qualities with minimal dopant segregation. In addition, it is shown that rapid thermal anneals (RTAs) at temperatures < 700 ???C provide only marginal improvement in the electrical quality of Si:P ??-doped samples encapsulated at 250 ???C, while RTA temperatures > 700 ???C should be avoided due to the high probability of dopant redistribution. To elucidate the nature of 2D transport in Si:P ??-doped devices, a detailed analysis of the low temperature magnetotransport for Si:P ??-doped layers with doping densities in the range ??? 0.2 ??? 2 ?? 1014 cm???2 was carried out. Using conventional 2D theories for disordered systems, both weak localisation (WL) and electron-electron interactions (EEI) are shown to contribute almost equal corrections to the 2D conductivity. In particular, it is found that EEI can introduce a significant correction in the Hall coefficient RH (hence Hall density) especially in the low density/temperature regime and the need to correct for this when using the Hall density to estimate the activated electron density is highlighted. While the electronic mean free path in such highly doped ??-layers is typically < 10 nm making ballistic transport in these devices difficult to observe, the phase coherence length can extend to almost 200 nm at about 0.3???0.5 K for doping densities of ??? 1 ??? 2 ?? 1014 cm???2. Finally, the optimised encapsulation strategy developed in this thesis is applied to a 2D square device fabricated by STM. The device exhibits Ohmic conductivity with complete dopant activation. An analysis of its low temperature magnetotransport shows that the device behaves similarly to a Si:P ??-doped layer encapsulated under similar conditions, thus highlighting that the STM patterning process had no adverse effect on device quality.

Organic electronic devices like organic solar cells and organic light-emitting diodes quickly degrade in ambient conditions if left unprotected. High susceptibility to moisture necessitates their encapsulation. The maximum water ingress acceptable to achieve reasonable lifetimes ranges several orders of magnitudes below industrial flexible barrier solutions. In this work, an electrical Ca-Test is used to optimize and investigate moisture barriers towards their application in device encapsulation. Aside from substantial improvement of the measurement system, atomic layer deposited, sputtered, and thermally evaporated barriers are screened and their water vapor transmission rates measured down to 2*10^(-5) g(H2O)/(m²*d) at 38 °C and 90% RH. Completely new encapsulation techniques are presented using novel molecular layer deposition interlayers or lamination of independently processed barriers. This way, simple Al layers become high-end moisture barriers. Furthermore, different single layer barriers are exposed to a wide variety of climates. An in-depth analysis of water permeation mechanics reveals sorption governed by Henry's law as well as dominance of interface diffusion below the barrier at late test stages. Investigated moisture barriers are applied to organic light-emitting diodes as well as solar cells and great improvements of lifetimes are observed. In addition, significant improvements in stability towards water ingress are witnessed upon the integration of adhesion layers at the cathode interface. Lastly, the great potential and applicability of this technology is showcased by the production and aging of fully flexible, highly efficient, stable organic solar cells
Organische Elektronik-Bauteile wie organische Solarzellen und organische Leuchtdioden degradieren in kürzester Zeit, wenn sie ungeschützt feuchter Luft ausgesetzt sind. Ihre starke Anfälligkeit gegenüber Wasserdampf macht ihre Verkapselung notwendig. Der maximale Wassereintritt, der für sinnvolle Lebensdauern noch zulässig erscheint, liegt jedoch noch mehrere Größenordnungen unter dem, was mit existierenden Technologien erreicht werden kann. In der vorliegenden Arbeit wird ein elektrischer Kalzium-Korrosionstest benutzt, um Barrieresysteme auf ihre Anwendbarkeit als Verkapselung organischer Bauelemente hin zu untersuchen und zu optimieren. Abgesehen von signifikanten Verbesserungen am Messsystem werden Wasserdampfbarrieren aus Atomlagenabscheidungs-, Kathodenzerstäubungs- und Verdampfungsprozessen vermessen. Dabei werden außerordentlich niedrige Wasserdampfdurchtrittsraten von nur 2*10^(-5) g(H2O)/(m²*d) in einem Alterungsklima von 38 °C und 90% relativer Feuchte verzeichnet. Vollkommen neue Verkapselungstechniken werden realisiert, wie etwa die Integration von Zwischenschichten durch Molekularlagenabscheidung oder die Lamination zweier Barrieren, die unabhängig voneinander prozessiert werden. Dieser Prozess verwandelt einfache Al Schichten in qualitativ hochwertige Wasserdampfbarrieren. Des Weiteren werden verschiedene Einzelschicht-Barrieren einer breiten Klimavariation ausgesetzt. Dies ermöglicht die genaue Analyse der Permeationsmechanismen des Wassers. Es wird gezeigt, dass Sorption hier dem Henry'sche Gesetz folgt. Diffusion entlang der Grenzfläche unterhalb der Barriere dominiert die Permeation zu späten Testzeiten. Die untersuchten Wasserdampfbarrieren werden an organischen Leuchtdioden und Solarzellen erprobt und zeigen große Verbesserungen bezüglich ihrer Lebensdauern. Darüber hinaus zeigt sich eine stark verbesserte Resistenz gegenüber Wassereintritt, wenn eine zusätzliche Adhäsionsschicht unter der Kathodengrenzfläche integriert wird. Letztendlich zeigt sich das große Potential und die Anwendbarkeit der Ergebnisse in der hohen Effizienz und langen Lebensdauer vollflexibler, verkapselter organischer Solarzellen

The investigation into the encapsulation of gold nanoparticles (AuNPs) by poly(methyl methacrylate) (PMMA) was undertaken. This was performed by three polymerisation techniques including: grafting PMMA synthesised by reversible addition-fragmentation chain transfer (RAFT) polymerisation to AuNPs, grafting PMMA synthesised by atom transfer radical polymerisation (ATRP) from the surface of functionalised AuNPs and by encapsulation of AuNPs within PMMA latexes produced through photo-initiated oil-in-water (o/w) miniemulsion polymerisation. The grafting of RAFT PMMA to AuNPs was performed by the addition of the RAFT functionalised PMMA to citrate stabilised AuNPs. This was conducted with a range of PMMA of varying molecular weight distribution (MWD) as either the dithioester or thiol end-group functionalities. The RAFT PMMA polymers were characterised by gel permeation chromatography (GPC), ultraviolet-visible (UV-vis), Fourier transform infrared-attenuated total reflectance (FTIR-ATR), Fourier transform Raman (FT-Raman) and proton nuclear magnetic resonance (1H NMR) spectroscopies. The attachment of PMMA to AuNPs showed a tendency for AuNPs to associate with the PMMA structures formed, though significant aggregation occurred. Interestingly, thiol functionalised end-group PMMA showed very little aggregation of AuNPs. The spherical polymer-AuNP structures did not vary in size with variations in PMMA MWD. The PMMA-AuNP structures were characterised using scanning electron microscopy (SEM), transition electron microscopy (TEM), energy dispersive X-ray analysis (EDAX) and UV-vis spectroscopy. The surface confined ATRP grafting of PMMA from initiator functionalised AuNPs was polymerised in both homogeneous and heterogeneous media. 11,11’- dithiobis[1-(2-bromo-2-methylpropionyloxy)undecane] (DSBr) was used as the surface-confined initiator and was synthesised in a three step procedure from mercaptoundecanol (MUD). All compounds were characterised by 1H NMR, FTIR-ATR and Raman spectroscopies. The grafting in homogeneous media resulted in amorphous PMMA with significant AuNP aggregation. Individually grafted AuNPs were difficult to separate and characterise, though SEM, TEM, EDAX and UV-vis spectroscopy was used. The heterogeneous polymerisation did not produce grafted AuNPs as characterised by SEM and EDAX. The encapsulation of AuNPs within PMMA latexes through the process of photoinitiated miniemulsion polymerisation was successfully achieved. Initially, photoinitiated miniemulsion polymerisation was conducted as a viable low temperature method of miniemulsion initiation. This proved successful producing a stable PMMA with good conversion efficiency and narrow particle size distribution (PSD). This is the first report of such a system. The photo-initiated technique was further optimised and AuNPs were included into the miniemulsion. AuNP encapsulation was very effective, producing reproducible AuNP encapsulated PMMA latexes. Again, this is the first reported case of this. The latexes were characterised by TEM, SEM, GPC, gravimetric analysis and dynamic light scattering (DLS).

In this paper a novel stimuli responsive hydrogel material, methacrylated sodium alginate beta-cyclodextrin (Alg-MA-β-CD), was used in combination with a microfluidic device to create microspheres. Currently there is no reliable method for fabricating homogeneous stimuli-responsive microspheres, in-house microfluidic devices are not reliable in manufacture quality or long-term use. Alginate hydrogels have many attractive characteristics for bioengineering applications and are commonly used to mimic the features and properties of the extracellular matrix (ECM). Human mesenchymal stem cells (hMSCs) are of top interest to tissue engineers. hMSCs are widely available and can be harvested and cultured directly out of human bone marrow. hMSCs have the ability to differentiate into osteoblasts, adipocytes, chondrocytes, muscle cells, and stromal fibroblasts depending on mechanical signals transmitted through surrounding ECM. The biomechanical properties of alginate based stimuli-responsive hydrogels can be tuned to match those of different types of tissues. When trying to transport and control the differentiation of hMSCs into generating new tissues or regenerating damaged tissues, it is highly beneficial to encapsulate the cells inside a microsphere made from these hydrogels. The proposed research objectives are: 1) To optimize fabrication techniques and create functional microfluidic devices; 2) Analyze the effects of flow parameters on microsphere production; and 3) Encapsulate viable hMSCs inside multi-stimuli responsive alginate microspheres using the fabricated microfluidic devices (MFDs). In this study, photolithography microfabrication methods were used to create flow-focusing style MFDs. The hydrogel materials were characterized via rheological methods. Syringe pumps controlled flow rates of fluids through the devices. Active droplets formation was monitored through a camera attached to an inverted microscope, where images were analyzed. Microsphere production was analyzed optically and characterized. Alg-MA-β-CD polymer solutions containing hMSCs were encapsulated, and a live/dead florescence assay was preformed to verify cell viability. Using a modified fabrication process it was possible to manufacture Alg-MA-β-CD microspheres and encapsulate and maintain viable hMSCs inside.

L’oxygène et l’eau présents dans l’atmosphère sont des acteurs important dans la dégradationdes matériaux contenus dans les dispositifs opto-électroniques organiques. Dans le but d’améliorerla stabilité et la durée de vie de ces dispositifs, ces dispositifs sont encapsulés avec desmatériaux barrière aux gaz par lamination ou par l’utilisation de couches minces. Cette dernière,notamment utilisée pour les OLED, permet de fournir des barrières aux gaz performantes parle dépôt de couches inorganiques denses directement sur les dispositifs. Cependant, elles sontassujetties aux défauts des surfaces sur lesquelles elle sont déposées.L’objectif de ces travaux est de développer une couche de planarisation afin d’homogénéiserla surface des dispositifs photovoltaïques organiques (OPV) et de réduire la rugosité dans lebut d’obtenir une protection barrières aux gaz améliorée, conférée par le dépôt subséquent decouches denses inorganiques selon divers moyens (voie liquide et gazeuse).Dans un premier temps, des couches de planarisation ont été développées à partir de 6 copolymèresp(VDF-HFP). Ces derniers ont été caractérisés afin d’améliorer nos connaissances sur cesmatériaux.Grâce à une étude de solubilité, des encres à différentes concentrations dans l’acétate d’éthyleont été réalisées. Ces dernières ont été étudiées par des mesures rhéologiques et de tension desurface permettant de mieux appréhender leur étalement, et les états de surface obtenus sur dessubstrats PET et sur les dispositifs OPV. Ces recherches ont été complétées par un contrôlede la topographie et par conséquent de la planarisation des dispositifs OPV par microscopieconfocale.Pour finir, l’étude des performances barrière des structures d’encapsulations hybrides (organiqueinorganique)ont dévoilé une bonne compatibilité lorsque la rugosité de la couche de planarisationest très faible. Ces résultats sont confirmés par des mesures barrières aux gaz et des tests devieillissement accélérés des dispositifs OPV encapsulés en enceinte climatique qui permettentd’illustrer l’intérêt de l’encre planarisante développée.Ce travail a été réalisé au laboratoire LMPO au CEA/LITEN en collaboration avec l’industrielArkema dans le but de fournir des technologies d’encapsulations performantes
Oxygen and water present in the atmosphere are important actors of the degradation of materialscontained in optoelectronic devices. In order to increase the stability and the lifetime ofOPV, the devices are encapsulated with gas-barrier materials by lamination encapsulation orthin film encapsulation. These latter, espacially used in OLED technology, provides high performancegas barriers by depositing dense inorganic layers directly onto the devices. However,they are subject to the defects of the surfaces on which they are deposited.The purpose of this study is to develop a planarinzing layer in order to homogenize the surfaceof organic photovoltaic devices (OPV) and to reduce the roughness with the aim to obtain animproved gas barrier protection, conferred by the subsequent deposition of dense inorganic layersby various ways (liquid and gaseous routes).In a first step, the planarization layers were developed from six p(VDF-HFP) co-polymers. Thesehave been characterized to improve our knowledge on those materials.Through a solubility study, inks at different concentrations in ethyl acetate were made. Thelatter were studied by rheological measurements and surface tension to understand better theirspread, and the surface conditions obtained on PET substrates and OPV devices. Those researchswere completed with a topography control and consequently the planarization of OPVdevices by confocal microscopy.Finally, the study of the barrier performance of hybrid encapsulation structures (organic-inorganic)revealed a good compatibility when the rugosity of the planarization layer is very low. Theseresults are confirmed by permeation measurements and accelerated aging tests of OPV devicesencapsulated in climatic chambers that illustrate the interest of the planarized ink developed.This work has been performed in the LMPO Laboratory at CEA/LITEN in collaboration withthe chemical company Arkema in order to be able to provide performant encapsulation technologies

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

L’objectif scientifique de ce travail de thèse était de proposer des structures de films d’encapsulation améliorées et bon marché, fabriquées par dépôt de couches atomiques (Atomic Layer Deposition, ALD) à basse température. Des oxydes largement utilisés, l'alumine (oxide d'aluminium) et l'oxyde de titane, ont été étudiés en utilisant des précurseurs chimiques bon marché (triméthyl aluminium – TMA, tetraisopropoxide de titane – TTIP). L'utilisation d’un traitement plasma pour améliorer les propriétés barrière intrinsèques des couches d'oxydes a été proposée et testée sur de l'alumine. Le traitement plasma consiste en une exposition périodique au plasma argon/oxygène durant un dépôt thermique. Il a permis de produire des films présentant de meilleures propriétés barrière que les films déposés en mode thermique pure ou en mode plasma pure.Un effort a été porté sur la compréhension de l’origine de la faible résistance chimique des films en oxyde de titane faits à basse température avec du TTIP. Il a été démontré que la perméabilité de ces films est liée à l’incorporation de ligands du TTIP dans la couche lors des synthèses à basse température. L’utilisation d’un traitement thermique à une température supérieure au seuil de cristallisation du TiO2 (ca. 340°C) s’est révélée efficace pour éliminer les ligands et restaurer la résistance chimique. Une méthode rapide de caractérisation des macro-défauts, déjà utilisée à Encapsulix, a été davantage développée: la décoration des macro-défauts à l'acide sulfurique.Ces travaux constituent une contribution à l'amélioration des propriétés barrière intrinsèques des oxydes utilisés dans les films de type nanolaminés
The scientific goal of this work was to propose improved, cost-efficient encapsulation film structures with the use of atomic layer deposition at low temperature. Widely used oxides, alumina and titania, have been investigated with the use of low-cost chemical precursors (trimethyl aluminum – TMA, titanium tetraisopropoxide – TTIP).The use of plasma treatment to improve the intrinsic barrier properties of the oxide layers has been proposed and tested on alumina. Alumina has been synthesized at 80°C, using TMA and water (thermal mode) or TMA and an argon / oxygen plasma (plasma-enhanced mode).Plasma treatment consists of periodic exposure to an argon / oxygen plasma during a thermal deposition. It has made it possible to produce films having better barrier properties than films deposited in pure thermal mode or in pure plasma-enhanced mode.An effort has been made on the understanding of the reason for the very low barrier performances of titania made at low-temperature. The permeability of these films has been shown to be related to the incorporation of TTIP ligands into the layer during low-temperature syntheses. The use of heat treatment at a temperature above the crystallization threshold of TiO2 (ca. 340 ° C.) has proved effective in eliminating ligands and restoring chemical resistance.It has been necessary to also work on the characterization methods to evaluate the barrier properties. A rapid method of macro-defects characterization, already used at Encapsulix, has been further developed: defects decoration with sulfuric acid.This work is a contribution to the improvement of the intrinsic barrier properties of the oxides used in nanolaminates for encapsulation

Cell encapsulation is a promising concept in regenerative medicine and stem cell treatment of diseases. Cells encapsulated in hydrogels have shown to yield better therapeutic outcome over cells in suspension. Microfluidic platforms have facilitated the process of cell encapsulation through the controlled mixing of aqueous cell solution and hydrogel with an immiscible liquid to yield a monodispersed population of microcapsules at a high throughput. However, given that the microfluidic process of placing cells in microcapsules is completely random, yielded samples are often riddled with empty microcapsules, raising the need for a post-encapsulation purification step to sort empty microcapsules from cell-laden ones. Sorting of microcapsules can be achieved through several techniques, most desirable of which are electrokinetic such as dielectrophoresis (DEP) and electrophoresis (EP). The advantages of DEP and EP techniques are that they support label-free sorting and yield a high throughput. However to achieve true effective DEP or EP sorting, there is a need to understand how empty microcapsules react to these electrokinetic forces versus occupied microcapsules. This study developed microfluidic devices for characterising the electrokinetic effects on microcapsules using DEP and EP. Results of both characterization techniques showed notable differences in the response of empty microcapsules versus cell-laden ones, reinforcing their potentials for sorting. Furthermore, this study proposed designs for microcapsules sorting devices that leverage EP and DEP.

The consumption of omega-3 fatty acids and phytosterol promotes the reduction of cholesterol and triacylglycerol levels. However, such compounds are susceptible to oxidation, which hampers their application. First, the aim of this work was to encapsulate echium oil (Echium plantagineum L.), source of omega-3 fatty acids, with hydrophilic phenolic compounds (sinapic acid and rutin) by double emulsion followed by complex coacervation in order to evaluate the best hydrophilic phenolic compound. In this case, sinapic acid showed better performance as antioxidant. Then, the second objective of this work was to study the microencapsulation of echium oil by complex coacervation using gelatin-arabic gum and gelatin-cashew gum as wall materials and sinapic acid and transglutaminase as crosslinkers. In this step, it was possible to observe that sinapic acid, besides to be an antioxidant, could also act as crosslinker. So, the third objective was to study the effect of sinapic acid in echium microparticles obtained by emulsion followed by spray or freeze drying using arabic gum as carrier agent in order to compare different encapsulation techniques. In addition to these methods, the fourth objective was to compare these techniques already mentioned to the combination of microfluidic devices and ionic gelation in order to encapsulate echium oil. In this case, sinapic acid and quercetin were also incoporated in the microcapsules. All the microcapsules/ microparticles obtained in the mentioned different techniques presented characteristics feasible for application and also promoted the protection of the oil. However, the encapsulation by complex coacervation and the addition of sinapic acid as crosslinkers was the method choosen for the coencapsulation of echium oil and phytosterols since presented the better results. Moreover, the treatment GA075 (microcapsule with gelatin-arabic gum as wall materials and 0.075g sinapic acid/ g gelatin) promoted the better protection to the encapsulated compounds. In this way, this treatment was applied into yogurt and compared to the one with the compounds nonencapsulated and the yogurt control. The yogurt containing microcapsules, presented a pH range from 3.89-4.17 and titratable acidity range from 0.798-0.826%, with good sensorial acceptance. It was possible to apply the microcapsules in yogurt, without compromising the rheological properties and physicochemical stability of the product, obtaining a functional product rich in omega-3 fatty acids, phytosterols and phenolic compound.
O consumo de ácidos graxos ômega-3 e fitosterol promove a redução dos níveis de colesterol e triacilglicerol. No entanto, esses compostos são susceptíveis à oxidação, o que dificulta sua aplicação. Primeiramente, o objetivo deste trabalho foi encapsular o óleo de echium (Echium plantagineum L.), fonte de ácidos graxos ômega-3, com compostos fenólicos hidrofílicos (ácido sinápico e rutina) por emulsão dupla seguida de coacervação complexa com intuito de avaliar o melhor composto fenólico hidrofílico. Neste caso, o ácido sinápico apresentou melhor desempenho como antioxidante. Em seguida, o segundo objetivo deste trabalho foi estudar a microencapsulação do óleo de echium por coacervação complexa utilizando as combinações gelatina-goma arábica e gelatina-goma de caju como materiais de parede e ácido sinápico e transglutaminase como agentes de reticulação. Nesta etapa, foi possível observar que o ácido sinápico, além de ser um antioxidante, também pode atuar como agente de reticulação. Assim, o terceiro objetivo foi estudar o efeito do ácido sinápico em micropartículas de óleo de echium obtidas por emulsão seguida de atomização ou liofilização utilizando goma arábica como agente carreador, com a finalidade de comparar diferentes técnicas de encapsulação. Além desses métodos, o quarto objetivo foi comparar essas técnicas já mencionadas com a combinação de dispositivos microfluídicos e gelificação iônica utilizando o óleo de echium como composto bioativo. Neste caso, o ácido sinápico e a quercetina também foram incorporados nas microcápsulas. Todas as microcápsulas/ micropartículas obtidas pelas diferentes técnicas mencionadas apresentaram características viáveis para aplicação e também promoveram a proteção do óleo. No entanto, a encapsulação por coacervação complexa e a adição de ácido sinápico como reticulante foi o método escolhido para a coencapsulação de óleo de echium e fitosteróis, uma vez que apresentou melhor resultado. Além disso, o tratamento GA075 (microcápsula com gelatina-goma arábica como materiais de parede e 0,075g de ácido sinápico/ g gelatina) promoveu a melhor proteção aos compostos encapsulados. Desta forma, este tratamento foi aplicado em iogurte e comparado com o mesmo adicionado dos compostos não encapsulados e o iogurte controle. O iogurte contendo microcápsulas apresentou faixa de pH de 3,89-4,17 e acidez titulável de 0,798-0,826 %, com boa aceitação sensorial. Foi possível a aplicação das microcápsulas no iogurte, sem comprometer as propriedades reológicas e a estabilidade físico-química do produto, obtendo um produto funcional rico em ácidos graxos ômega-3, fitosteróis e compostos fenólicos.

Les prothèses neuronales implantables offrent de nos jours une réelle opportunité pour restaurer des fonctions perdues par des patients atteints de lésions cérébrales ou de la moelle épinière, en associant un canal non-musculaire au cerveau ce qui permet la connexion de machines au système nerveux. La fiabilité sur le long terme de ces dispositifs, se présentant sous la forme d'électrodes implantables, est un facteur crucial pour envisager des applications dans le domaine des interfaces cerveau-machine. Cependant, les électrodes actuelles pour l'enregistrement et la stimulation se détériorent en quelques mois voire quelques semaines. Ce défaut de fiabilité sur le long terme, principalement lié à une réaction chronique contre un corps étranger, est induit au départ par le traumatisme consécutif à l'insertion du dispositif et s'aggrave ensuite, durant les mouvements du cerveau, à cause des propriétés mécaniques inadaptées de l'électrode par rapport à celles du tissu. Au cours du temps, l'ensemble de ces facteurs inflammatoires conduit à l'encapsulation de l'électrode par une couche isolante de cellules réactives détériorant ainsi la qualité de l'interface entre le dispositif implanté et le tissu cérébral. Pour s'affranchir de ce phénomène, la biocompatibilité des matériaux et des procédés, ainsi que les propriétés mécaniques de l'électrode doivent être pris en considération. Durant cette thèse, nous avons abordé la question en développant un procédé de fabrication simple pour réaliser des dispositifs implantables souples en parylène. Les électrodes flexibles ainsi obtenues sont totalement biocompatibles et leur compliance est adaptée à celle du tissu cérébral ce qui limite fortement la réaction inflammatoire occasionnée par les mouvements du cerveau. Après avoir optimisé le procédé de fabrication, nous avons focalisé notre étude sur les performances du dispositif et sa stabilité. L'utilisation d'une grande densité d'électrodes micrométriques, avec un diamètre de 10 à 50 µm, permet de localiser les zones d'enregistrement en rendant possible, par exemple, la conversion d'un ensemble de signaux électrophysiologiques en une commande de mouvement. En contrepartie, la réduction de la taille des électrodes conduit à une augmentation de l'impédance ce qui dégrade la qualité d'enregistrement des signaux. Ici, un polymère conducteur organique, le poly(3,4-ethylenedioxythiophene), PEDOT, a été utilisé pour améliorer les caractéristiques électriques d'enregistrement d'électrodes de petites dimensions. Le PEDOT a été déposé sur la surface des électrodes par électrochimie avec une grande reproductibilité. Des dépôts homogènes avec des conductivités électriques très élevées ont été obtenus en utilisant différents procédés électrochimiques. Grâce à l'augmentation du rapport surface/volume induit par la présence de la couche de PEDOT, une diminution significative de l'impédance de l'électrode (jusqu'à 3 ordres de grandeur) a été obtenue sur une large plage de fréquences. De tests de vieillissement thermique accéléré ont également été effectués sans influence notable sur les propriétés électriques démontrant ainsi la stabilité de la couche de PEDOT durant plusieurs mois. Les dispositifs ainsi obtenus, fabriqués en parylène avec un dépôt de PEDOT sur la surface active des électrodes, ont été testés in vitro et in vivo sur des cerveaux de souris. Un meilleur rapport signal sur bruit a été mesuré durant des enregistrements neuronaux en comparaison avec des résultats obtenus avec des électrodes commerciales. En conclusion, la technologie décrite ici, associant stabilité sur le long terme et faible impédance, a permis d'obtenir des électrodes implantables parfaitement adaptées pour le développement d'interfaces neuronales chroniques
Implantable neural prosthetics devices offer, nowadays, a promising opportunity for the restoration of lost functions in patients affected by brain or spinal cord injury, by providing the brain with a non-muscular channel able to link machines to the nervous system. The long term reliability of these devices constituted by implantable electrodes has emerged as a crucial factor in view of the application in the "brain-machine interface" domain. However, current electrodes for recording or stimulation still fail within months or even weeks. This lack of long-term reliability, mainly related to the chronic foreign body reaction, is induced, at the beginning, by insertion trauma, and then exacerbated as a result of mechanical mismatch between the electrode and the tissue during brain motion. All these inflammatory factors lead, over the time, to the encapsulation of the electrode by an insulating layer of reactive cells thus impacting the quality of the interface between the implanted device and the brain tissue. To overcome this phenomenon, both the biocompatibility of materials and processes, and the mechanical properties of the electrodes have to be considered. During this PhD, we have addressed both issues by developing a simple process to fabricate soft implantable devices fully made of parylene. The resulting flexible electrodes are fully biocompatible and more compliant with the brain tissue thus limiting the inflammatory reaction during brain motions. Once the fabrication process has been completed, our study has been focused on the device performances and stability. The use of high density micrometer electrodes with a diameter ranging from 10 to 50 µm, on one hand, provides more localized recordings and allows converting a series of electrophysiological signals into, for instance, a movement command. On the other hand, as the electrode dimensions decrease, the impedance increases affecting the quality of signal recordings. Here, an organic conductive polymer, the poly(3,4-ethylenedioxythiophene), PEDOT, has been used to improve the recording characteristics of small electrodes. PEDOT was deposited on electrode surfaces by electrochemical deposition with a high reproducibility. Homogeneous coatings with a high electrical conductivity were obtained using various electrochemical routes. Thanks to the increase of the surface to volume ratio provided by the PEDOT coating, a significant lowering of the electrode impedance (up to 3 orders of magnitude) has been obtained over a wide range of frequencies. Thermal accelerated ageing tests were also performed without any significant impact on the electrical properties demonstrating the stability of the PEDOT coatings over several months. The resulting devices, made of parylene with a PEDOT coating on the active surface of electrodes, have been tested in vitro and in vivo in mice brain. An improved signal to noise ratio during neural recording has been measured in comparison to results obtained with commercially available electrodes. In conclusion, the technology described here, combining long-term stability and low impedance, make these implantable electrodes suitable candidates for the development of chronic neural interfaces

Over the last decade, microfluidics has emerged as a distinct new field with promising applications for diverse research areas. The ability to precisely control fluids at the microscale allows the execution of a variety of programmable semi-automatic operations on the same device, effectively forming a lab-on-a-chip. In particular, droplet-based microfluidic systems – which reliably generate highly uniform microdroplets at a high throughput – enable the controlled compartmentalization of biological material and have the potential to influence mainstream biomedical research. In this thesis, a microfluidic platform is presented that allows the encapsulation of viable cells in agarose microcapsules for applications in cell–based therapy. As an improvement to pre-existing methods of cell encapsulation, the proposed system combines continuous high throughput cell-encapsulation with on-chip microcapsule gelation and purification.

Islet transplantation for the purpose of treating insulin-dependent diabetes is currently limited by several factors, most significantly, islet survival post transplantation. In the following dissertation, a tissue-engineered prevascularized pancreatic encapsulating device (PPED) was designed, developed, and evaluated. Microvessel fragments placed within a 3-dimensional collagen-based matrix produce and secrete vascular endothelial growth factor, and inosculate with the host circulation. Isolated islets placed within collagen gels exhibited four-fold more insulin release in response to glucose stimulation than islets in tissue culture. The insulin released by β-cells in islets encapsulated in collagen exhibited unobstructed diffusion within the collagen gels. Subsequent studies evaluated the ability to create a sandwich comprised of two layers of prevascularized collagen gels around a central collagen gel containing islets. In vitro characterization of the islets within these constructs showed that islets are functional and respond to glucose stimulation. The PPEDs were implanted subcutaneously into SCID mice. Islet survival was assessed after 7, 14, and 28 days. Immunohistochemical analysis was performed on the implants to detect insulin and the presence of intraislet endothelial cells. At all time points, insulin was localized in association with intact and partially dissociated islets. Moreover, cells that exhibited insulin staining were co-localized with intraislet endothelial cells. Lastly, dextran-perfused PPEDs showed host perfusion throughout the implant, including perfusion to structures that are morphologically consistent with pancreatic islets. These data indicate that the PPED enhances islet survival by supporting islet viability, by maintaining intraislet endothelial cells, and by enhancing reperfusion to the islets.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico
A encapsulação de moléculas bioativas é utilizada há décadas pelas industrias de alimentos e representa uma real oportunidade de desenvolvimento de produtos inovadores. Dada a sua versatilidade funcional, as proteínas do leite, em particular as proteínas do soro de leite, tem sido utilizadas para fins de encapsulação por meio de diferentes técnicas. Complementarmente, estudos recentes mostraram a habilidade de proteínas alimentares de carga oposta de se co-associar formando micro-esferas através da coacervação complexa. Compreender as forças que governam o processo de coacervação de hetero-proteínas e o efeito da presença de pequenos ligantes (bioativos) são pré-requisitos para o uso de coacervados complexos de hetero-proteínas como agentes de encapsulação. Neste contexto, o objetivo do meu projeto de tese foi entender o mecanismo de coacervação complexa entre β-lactoglobulina (β-LG) e lactoferrina (LF) na ausência ou na presença de pequenos ligantes. As condições ótimas para a coacervação entre β-LG e LF foram identificadas como sendo entre os pH 5.4 – 6.0 e em presença de um excesso molar de β-LG. Interessantemente, LF demonstrou uma seletividade de coacervação com a β-LG A, a isoforma ligeiramente mais eletronegativa. A nivel molecular, a presença de dois sítios de interação da β-LG com a LF foram evidenciados. Em complemento, hetero-complexos como o pentâmero LF(β-LG 2 ) 2 e outros complexos maiores (LFβ- LG 2 ) n foram identificados como constituintes da fase coacervada. Para avaliar o efeito da presença de pequenos ligantes na coacervação complexa entre β-LG e LF, foram usados modelos de moléculas hidrofóbica (ANS) e hidrofílica (ácido fólico). Embora nas condições experimentais os pequenos ligantes não tenham interagido com a β-LG, ambos interagiram com a LF induzindo sua auto-associação em nano- partículas. Concentrações relativamente elevadas de pequenos ligantes afetaram a interação entre as duas proteínas levando a uma transição entre os regimes de coacervação e agregação.
Le bénéfice de l’encapsulation des molécules bioactives a séduit les industries agroalimentaires depuis plusieurs décennies et constitue toujours un levier de développement pour des produits innovants. Plus récemment des études ont montré la capacité de protéines alimentaires de charge opposée à s’assembler en microsphères par coacervation complexe. La compréhension des forces gouvernant le processus de coacervation complexe entre protéines et l’influence exercée par la présence de petits ligands (bioactifs) demeurent des prérequis pour l’utilisation des coacervats complexes de protéines comme agent d’encapsulation. Dans ce contexte, l’objectif de mon projet de thèse a été de comprendre le mécanisme de coacervation complexe entre une protéine chargée négativement, la β-lactoglobuline (β-LG), et une protéine chargée positivement, la lactoferrine (LF), issues du lactosérum en absence et en présence de petits ligands. Les conditions optimales de coacervation entre la β-LG et la LF ont été définies entre pH 5.4 et 6.0 ainsi qu’en présence d’un excès de β-LG. La LF a présenté une coacervation préférentielle avec le variant A de la β-LG qui se distingue du variant B par la substitution de 2 acides aminés. Au niveau moléculaire, deux sites de fixation de la β-LG sur la LF ont été identifiés. En outre, par la mesure d’une part des coefficients de diffusion rotationnel et d’autre part de la cinétique de diffusion des entités moléculaires constituant les coacervats, il est suggéré que ces derniers sont formés à partir de β-LG libre, de pentamère, LF(β- LG 2 ) 2 , ainsi que des entités plus larges, (LFβ-LG 2 ) n . Afin d’évaluer l’effet de la présence de petits ligands sur la coacervation complexe entre la β-LG et la LF, des ligands modèles, l’un hydrophobe (ANS), l’autre hydrophile (acide folique) ont été utilisés. Dans les conditions expérimentales testées ces deux ligands n’ont pas d’affinité pour la β-LG, mais après interaction avec la LF ils sont capables d’induire son auto-association en nanoparticules. En concentrations élevées de ligands, la coacervation complexe entre la β-LG et la LF est perturbée et une transition vers un régime d’agrégation est observée.
Encapsulation of bioactives has been used by the food industries for decades and represents a great potential for the development of innovative products. Given their versatile functional properties, milk proteins in particular from whey have been used for encapsulation purposes using several encapsulation techniques. In parallel, recent studies showed the ability of oppositely charged food proteins to co-assemble into microspheres through complex coacervation. Understanding the driving forces governing heteroprotein coacervation process and how it is affected by the presence of ligands (bioactives) is a prerequisite to use heteroprotein coacervates as encapsulation device. In this context, the objective of my thesis work was to understand the mechanism of complex coacervation between β-lactoglobulin (β-LG) and lactoferrin (LF) in the absence and presence of small ligands. The conditions of optimal β-LG - LF coacervation were found at pH range 5.4-6 with a molar excess of β-LG. Remarkably, LF showed selective coacervation with β-LG A, the slightly more negative isoform. At molecular level, the presence of two binding sites on LF for β-LG was evidenced. Moreover, the heterocomplexes such as pentamers LF(β-LG 2 ) 2 and quite large complexes (LFβ-LG 2 )n were identified as the constituent molecular species of the coacervate phase. To evaluate the β-LG - LF complex coacervation in the presence of small ligands, models of hydrophobic (ANS) and hydrophilic molecules (folic acid) were used. Although under the experimental conditions tested the small ligands did not interact with β-LG, both interacted with LF inducing its self- association into nanoparticles. High relative concentrations of small ligands affected the interaction between the two proteins leading to a transition from coacervation to aggregation regime.

Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2010.
Committee Chair: Samuel Graham; Committee Member: Bernard Kippelen; Committee Member: David McDowell; Committee Member: Sankar Nair; Committee Member: Suresh Sitaraman. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Les dispositifs médicaux miniaturisés sont de plus en plus répandus dans le monde médical, car ils offrent de nouvelles opportunités de traitement et de surveillance. La miniaturisation des systèmes permet notamment une chirurgie minimalement invasive, une portabilité améliorée et une facilité d'utilisation. Parmi les exemples on peut mentionner les micro-stimulateurs cardiaques, les micro-implants cochléaires et les micro-capteurs ex-situ de glucose. Cependant, les micro-dispositifs implantables qui utilisent des technologies d'assemblage autres que les boîtiers métalliques sont encore à découvrir. La surveillance de paramètres physiologiques à l'aide de capteurs in-situ de pression et BioMEMS pourraient bénéficier des progrès faits sur les études d'encapsulation en couche mince destinées à protéger les micro-dispositifs de silicium contre la corrosion. En effet, une barrière qui empêche la diffusion et la pénétration des substances nocives est indispensable pour protéger à la fois le patient et le micro-dispositif. Les couches minces céramiques déposées par des procédés chimiques en phase vapeur sont de bons candidats grâce à leurs faibles perméabilités aux gazes, faibles réactivités chimique et conformités de dépôt élevées. Cependant, dans des milieux biologiques représentatifs du corps humain, peu d'études ont été réalisées dans le domaine de la protection des dispositifs microélectroniques contre la corrosion.Au cours de cette thèse, dix matériaux, choisis à l'issue d'une étude bibliographique, ont été étudiés: Al2O3, BN, DLC, HfO2, SiC, SiN, SiO2, SiOC, TiO2 et ZnO. Des couches ultrafines de ces matériaux (de 5 à 100 nm) ont été déposées par voie chimique en phase vapeur assisté par plasma (PECVD) ou par couches atomiques (ALD) sur des substrats silicium recouverts de matériaux généralement présents dans des dispositifs microélectroniques tels que le silicium cristallin, le cuivre, le tungstène nitrure et le poly-imide. Des mesures de cytotoxicité ont été réalisées et des tests de vieillissement ont été effectués pendant plusieurs semaines à des températures différentes dans une solution saline phosphatée (PBS) mais aussi dans une solution à base de sérum de veau fœtale (NaCl/SVF). Les changements dans la composition chimique et l'épaisseur ont été suivies par VASE, XPS et spectroscopie de masse d'ions secondaires à temps de vol (TOF-SIMS). Il a été montré que les couches de SiO2 et de SiN (généralement utilisées pour la protection dans l'industrie de la microélectronique) n'étaient pas stables dans le PBS et le NaCl/SVF à 37°C, même si en revanche elles offraient une bonne barrière aux gazes. L'Al2O3 a lui montré une très bonne tenu en milieu salin et une remarquable herméticité mais en revanche, il s'est corrodé rapidement dans le NaCl/SVF. Les couches de DLC, SiOC et TiO2 ont donné les meilleurs résultats de stabilité dans le PBS et le sérum de veau. Enfin, il a aussi été montré dans cette thèse que l'empilement TiO2 sur Al2O3 offrait la meilleure efficacité comme barrière hermétique et diffusive pour la protection des microsystèmes de silicium contre la corrosion dans les milieux salins
Miniaturized medical devices are becoming increasingly adopted by doctors and patients because they enable new treatment and monitoring capabilities, minimally invasive surgery, improved portability and ease of use. Recent examples include micro pacemakers, micro cochlear implants and ex-situ micro glucose sensors. However, implantable micro devices employing packaging technologies other than metallic enclosures are yet to be seen. Physiological monitors such as in-situ pressure sensors and BioMEMS could profit significantly from advances in thin barrier films for corrosion protection of silicon micro devices. Coating films that stop the diffusion and permeation of harmful substances are necessary to protect both the patient and the micro device. Ceramic films deposited by chemical vapor deposition techniques are good candidates for this task due to their low permeability to gases, low chemical reactivity and high conformality. However, few studies are available about the corrosion protection offered by biocompatible coatings to microelectronic devices in representative biological environments.Ten materials were selected in this thesis after a bibliographic study: Al2O3, BN, DLC, HfO2, SiC, SiN, SiO2, SiOC, TiO2 and ZnO. Ultra-thin films of these materials (5-100 nm) were deposited by plasma enhanced chemical vapor deposition (PECVD) or atomic layer deposition (ALD) on substrates commonly found in electronic micro devices: crystalline silicon, copper, tungsten nitride and polyimide. In vitro cytotoxicity tests and degradation tests were performed for several weeks at different temperatures in Phosphate Buffer Saline (PBS) and NaCl supplemented with 10% Fetal Bovine Serum (NaCl/FBS). Changes in thickness and chemical composition were monitored by VASE, XPS and time-of-flight secondary ion mass spectroscopy (TOF-SIMS). It was found that SiO2 and SiN films (generally used for protection in the microelectronics industry) are not stable in PBS and NaCl/FBS at 37°C, even though they act as good hermetic barriers. Al2O3 showed very good stability in saline solution and excellent behavior as gas barrier, but it was rapidly dissolved in NaCl/FBS.In contrast, films of DLC, SiOC and TiO2 showed very low chemical reactivity in both mediums. Finally, it was shown that multilayers of TiO2 on Al2O3 offer the best performance as hermetic and diffusion barriers for corrosion protection of silicon micro systems in saline environments

Les dispositifs électrochromes sont des dispositifs qui permettent de moduler la réflexion ou la transmission de la lumière. Ils recouvrent une grande variété d’applications dans le domaine du visible (vitrages intelligents) et dans le domaine de l’infrarouge (protection thermique des satellites et discrétion optique infrarouge). Les travaux présentés dans ce manuscrit répondent essentiellement à une problématique visant à élaborer un dispositif électrochrome tout solide à émissivité infrarouge variable par un procédé unique de pulvérisation cathodique magnétron. Une nouvelle architecture d’empilement avec une électrode de travail monocouche bi fonctionnelle a été choisie pour réunir les propriétés apportées classiquement par deux couches ou plus sur le haut des empilements électrochromes. Cette nouvelle architecture a nécessité la mise en place d’un procédé de dépôt original de pulvérisation cathodique réactive hydratée. Ce procédé a permis d’obtenir une électrode monocouche à base de trioxyde de tungstène réunissant les propriétés optiques et électroniques souhaitées. Il a également permis de déposer les autres couches de l’empilement, la contre-électrode à base de trioxyde de tungstène et les électrolytes solides conducteurs protoniques à base d’oxyde de tantale ou de zirconium. L’étude de l’ajout d’une couche d’encapsulation à base de dioxyde de cérium a également été menée. Cette architecture a permis d’obtenir un empilement électrochrome tout solide fonctionnel. Ce dispositif complet ainsi élaboré présente de bonnes propriétés optiques dans l’infrarouge en terme de modulation d’émissivité dans les bandes spectrales d’intérêt, à savoir 13 % en bande II et 31 % en bande III
Electrochromic materials are devices for modulating the reflection or transmission of light. They cover a wide variety of applications in the visible range (smart windows) and the infrared range (thermal protection for satellites and optical infrared discretion). The works presented in this manuscript were essentially responding to the problem of developping an all solid electrochromic device with a variable infrared emissivity by a single process of magnetron sputtering. A new stacking architecture with a working bi functional monolayer electrode was chosen to bring the properties conventionally made by two or more layers on top of electrochromic device. This new architecture has required the establishment of an original deposit process of hydrated reactive sputtering. This process yielded a monolayer electrode based on tungsten trioxide combining the desired optical and electronic properties. It allowed to deposit other layers of the stack, the counter electrode based on tungsten trioxide and the proton conductive solid electrolyte based on tantalum or zirconium oxide. The study of the addition of an encapsulation layer based on cerium dioxide was also conducted. This architecture has resulted in a functional all-solid electrochromic stack. The complete device thus prepared exhibits good optical properties in the infrared emissivity in terms of modulation and in particular in the spectral bands of interest, namely 13 % in MW and 31 % in LW

碩士
國立交通大學
理學院應用科技學程
102
In this study, UV-curable epoxy resins were used to encapsulate the organic devices. The epoxy resin shows a high glass transition tem-perature (Tg ≧110℃）, good adhesion to the glass substrate (≧2.0 kgf/mm2） after UV curing. The encapsulant reveals a very low volume shrinkage （≦4%）, high water vapor transmission resistance ability （WVTR ≦10 g/m2-day）. In this study, the epoxy resins were used to encapsulate the organic device such as organic light-emitting diode（OLED） and organic photovoltaics（OPV） devices. The results demonstrate that the lifetime of the encapsulated devices is enhanced. For the OPV devices, their PCE values are around 60% of original values af-ter keeping the encapsulated device in atmosphere for 1,000 hrs.

Organic electronic devices like organic solar cells and organic light-emitting diodes quickly degrade in ambient conditions if left unprotected. High susceptibility to moisture necessitates their encapsulation. The maximum water ingress acceptable to achieve reasonable lifetimes ranges several orders of magnitudes below industrial flexible barrier solutions. In this work, an electrical Ca-Test is used to optimize and investigate moisture barriers towards their application in device encapsulation. Aside from substantial improvement of the measurement system, atomic layer deposited, sputtered, and thermally evaporated barriers are screened and their water vapor transmission rates measured down to 2*10^(-5) g(H2O)/(m²*d) at 38 °C and 90% RH. Completely new encapsulation techniques are presented using novel molecular layer deposition interlayers or lamination of independently processed barriers. This way, simple Al layers become high-end moisture barriers. Furthermore, different single layer barriers are exposed to a wide variety of climates. An in-depth analysis of water permeation mechanics reveals sorption governed by Henry's law as well as dominance of interface diffusion below the barrier at late test stages. Investigated moisture barriers are applied to organic light-emitting diodes as well as solar cells and great improvements of lifetimes are observed. In addition, significant improvements in stability towards water ingress are witnessed upon the integration of adhesion layers at the cathode interface. Lastly, the great potential and applicability of this technology is showcased by the production and aging of fully flexible, highly efficient, stable organic solar cells.
Organische Elektronik-Bauteile wie organische Solarzellen und organische Leuchtdioden degradieren in kürzester Zeit, wenn sie ungeschützt feuchter Luft ausgesetzt sind. Ihre starke Anfälligkeit gegenüber Wasserdampf macht ihre Verkapselung notwendig. Der maximale Wassereintritt, der für sinnvolle Lebensdauern noch zulässig erscheint, liegt jedoch noch mehrere Größenordnungen unter dem, was mit existierenden Technologien erreicht werden kann. In der vorliegenden Arbeit wird ein elektrischer Kalzium-Korrosionstest benutzt, um Barrieresysteme auf ihre Anwendbarkeit als Verkapselung organischer Bauelemente hin zu untersuchen und zu optimieren. Abgesehen von signifikanten Verbesserungen am Messsystem werden Wasserdampfbarrieren aus Atomlagenabscheidungs-, Kathodenzerstäubungs- und Verdampfungsprozessen vermessen. Dabei werden außerordentlich niedrige Wasserdampfdurchtrittsraten von nur 2*10^(-5) g(H2O)/(m²*d) in einem Alterungsklima von 38 °C und 90% relativer Feuchte verzeichnet. Vollkommen neue Verkapselungstechniken werden realisiert, wie etwa die Integration von Zwischenschichten durch Molekularlagenabscheidung oder die Lamination zweier Barrieren, die unabhängig voneinander prozessiert werden. Dieser Prozess verwandelt einfache Al Schichten in qualitativ hochwertige Wasserdampfbarrieren. Des Weiteren werden verschiedene Einzelschicht-Barrieren einer breiten Klimavariation ausgesetzt. Dies ermöglicht die genaue Analyse der Permeationsmechanismen des Wassers. Es wird gezeigt, dass Sorption hier dem Henry'sche Gesetz folgt. Diffusion entlang der Grenzfläche unterhalb der Barriere dominiert die Permeation zu späten Testzeiten. Die untersuchten Wasserdampfbarrieren werden an organischen Leuchtdioden und Solarzellen erprobt und zeigen große Verbesserungen bezüglich ihrer Lebensdauern. Darüber hinaus zeigt sich eine stark verbesserte Resistenz gegenüber Wassereintritt, wenn eine zusätzliche Adhäsionsschicht unter der Kathodengrenzfläche integriert wird. Letztendlich zeigt sich das große Potential und die Anwendbarkeit der Ergebnisse in der hohen Effizienz und langen Lebensdauer vollflexibler, verkapselter organischer Solarzellen.

博士
國立中興大學
材料科學與工程學系所
104
Recently, the consumer electronics have gained a huge demand and the flexible electronic products become indispensable in the modern life. One of the important challenges for the flexible electronics is to improve thermal stability, dimensional stability and moisture resistivity. Among various thin-film techniques, high-density-plasma deposition has several advantages such as large area deposition, low temperature, low ion bombardment, good step coverage and uniformity. In this dissertation, the inductively-coupled-plasma technology was utilized to deposit inorganic silicon oxide (SiOx) and organic silicon (Org.-Si) films for the encapsulation of optoelectronic devices. The gas mixture of tetramethylsilane (TMS) and oxygen was used for the SiOx deposition, and the TMS and Ar for the Org.-Si deposition. These films were deposited on the polyethylene terephthalate (PET) substrates. The effects of deposition parameters such as substrate temperature, power density and gas mixture ratio on film properties were investigated. Under the optimal condition where the substrate temperature of 90°C, power density of 2120 W/m2 and O2/TMS gas ratio of 30, the SiOx films with high Si-O-Si bond intensity and dense structure can be obtained. At a temperature of 90°C, power density of 1580 W/m2 and TMS/(TMS+Ar) ratio of 20%, the Org.-Si can be deposited with an optimal deposition rate and film density. The Org.-Si insertion layer was used as a buffer layer to reduce internal stress and improve the adhesion between the PET substrate and SiOx barrier. It was found that six-pair SiOx/Org.-Si stacked layer can yield a hardness of 7H, water-vapor transmission rate (WVTR) of smaller than 5.66×10-6 g/m2day, and a water contact angle of 116°. For the encapsulation application, the lifetime of the organic light-emitting diode (OLED) increases from 7 h for devices without encapsulation to more than 200 h for devices with SiOx/Org.-Si stacked layer encapsulation. The lower WVTR value of the SiOx/Org.-Si stacked layer can reduce the dark spots in OLEDs. For the encapsulation application in flexible thin-film solar cells, the conversion efficiency can increase from 7.19% for modules encapsulated with conventional ethylene vinyl acetate to 7.36% for modules encapsulated with the SiOx/Org.-Si stacked layer. From outdoor environmental tests results, the SiOx/Org.-Si encapsulated devices can retain 88% performance, and will not be discolored as observed on EVA-encapsulated devices. As a result, the SiOx/Org.-Si stack multifunction layer with hydrophobilicty, hardness, stability and water-vapor resistance have great potential for flexible electronic device application.

碩士
國立屏東科技大學
機械工程系所
98
In this work, we deposited the passivation layer on devices by vacuum evaporation to investigate the effect of OLED with passivation layer and encapsulation. The device structure was ITO/NPB/Alq3/LiF/Al. A m-MTDATA/SiO2 passivation layer was deposited to separate hydrosphere and prevent the degradation. The electrical and emissive properties of device with and without passivation layer are compared and the degradation was observed. In this case, a passivation layer process did not influence the electrical and emissive characteristic of device and enhanced the lifetime in the air. The current density of device was set at 10 mA/cm2 and the initial luminance was 300 cd/m2. Under R.H 50 % and R.H 70 % in the air, the half-life of device with passivation layer improves by 6 times and 5 times, respectively. Besides, the half-life of device with passivation layer and encapsulation improves by 24 times and 27 times, respectively. According to the experiment results, we conclude that adding a passivation layer in the encapsulation device effectively separates hydrosphere and enhances the device lifetime.

博士
國立交通大學
應用化學研究所
98
Electroluminescence (EL) performance of flexible organic light-emitting device (FOLED) was found to be highly related to the surface morphology of the indium tin oxide (ITO)/plastic substrate as well as the patterning and processing conditions of the substrate. This thesis presents evidences showing that luminance efficiency of FOLED can be greatly improved by ITO pretreatment. Surface analysis of the ITO/PET by means of atomic force microscope (AFM) and optical microscope was compared with that of the ITO/glass and the influence of flexible OLEDs substrate treatment by various methods on EL performance were discussed. It was found that LiF as modified layer of ITO on plastic substrates led to the decrease of the operating voltage of FOLED devices. In fabrication of anode, ITO thin films were deposited onto polyethersulfone (PES) substrate at room temperature by negative ion-beam sputtering deposition technology of Plasmion Corporation. The optical and electrical properties of ITO/PES thin films were improved by introducing the Cs vapor during sputtering. Under the optimal condition, the resistivity of ITO/PES can reach 4.3 × 10-4 Ω-cm, which is lower than 1.58 × 10-3 Ω-cm of the conventional RF sputtered films. The optical transmittance is 85% throughout visible region. Surface morphology of the optimal ITO/PES films is 0.95 nm of the surface roughness under this condition. In addition, we use negative ion- beam sputtering deposition technology to deposit gas barrier layer on the plastic substrate. Under the optimal condition, we got the Rms of 1.54 nm and 0.63 nm for SixNy and AlxOy, respectively. In thin film encapsulation, we have developed a novel thin film encapsulation method for top-emitting and transparent OLED by introducing organic (not polymer)/inorganic multiple thin films to protect the devices, which is shown to suppress the permeation rate of moisture and oxygen. From the stability test of devices, the projected lifetime of transparent OLED with such a thin film encapsulation technique was similar to that with glass lid encapsulation.

博士
臺灣大學
材料科學與工程學研究所
98
This study utilized atomic layer deposition (ALD) to develop solutions to critical problems of organic electronics, including patterning-enabling and electron-injection- enhancing dual-functioning films for organic light-emitting diodes (OLEDs), gas-permeation barriers for the thin-film encapsulation of organic solar cells (OSCs), and permeation-blocking and electron-collecting dual-functioning films for flexible air-stable OSCs. On OLEDs, we demonstrated that with a 10-Å ALD Al2O3 film overcoated on a poly[1-methoxy-4-(2’-ethyl-hexyloxy)-2,5-phenylenevinylene] (MEH-PPV) electro- luminescent layer, the OLEDs not only withstood an aggressive photolithographic patterning process without any degradation but unprecedentedly showed increased luminous efficiency. Although the ALD precursor, trimethylaluminum (TMA), was found to damage MEH-PPV through addition to MEH-PPV’s vinylene groups, its damaging effect was eliminated by pre-treating the MEH-PPV surface with isopropyl alcohol (IPA), whose hydroxyl groups scavenged TMA throughout the ALD process. On the encapsulation of OSCs, we developed ALD processes that both prevented degradations caused by ambient gases and served as an annealing step that increased the initial power conversion efficiency (PCE) of the cells. With the ALD temperature set at 140 ºC and the deposition time set at 1 hr, OSCs based on blended poly-3- hexylthiophene (P3HT) and [6,6]-phenyl C61 butyric acid-methylester (PCBM), were optimally annealed during encapsulation, achieving a PCE of 3.66%. Encapsulating the cells with a 26-nm Al2O3/HfO2 nanolaminated film overcoated with an epoxy-resin protection layer enabled the cell to obtain an in-air degradation rate that was similar to cell stored in O2/H2O-free atmosphere. The Al2O3/HfO2 nanolaminated structure resolved the problem of hydrolysis-induced aging that occurred in single Al2O3 films, owing to the hydrophobicity of the HfO2 layers. Additionally, extended exposure of the ALD precursors during the ALD process ensured complete coverage of ALD films over the P3HT:PCBM layer at the perimeter of the cells. On flexible air-stable OSCs, we developed low-temperature (90 ºC) ALD ZnO films as both gas barriers and electron-collection layers for P3HT:PCBM-based inverted OSCs. By utilizing a long purge time (25-s) and a low deposition temperature (90 ºC) in the ALD process, we obtained high electron mobility (9.6 cm2/V s) and low carrier concentration (2.1×1017 cm-3) in the ZnO films, thereby optimizing their electron- collecting function and achieving 4.06% PCE in the resultant inverted OSCs. Moreover, when deposited on poly(ethylene terephthalate) (PET) substrates, the ALD ZnO films at 70 nm of thickness showed excellent barrier properties: water vapor transmission rate (WVTR) < 10-3 g/m2 day and helium transmission rate (HeTR) of 5.03 cc/m2 day. This moisture-blocking capability was crucial for achieving air-stable inverted OSCs, as we determined that air-induced degradations of inverted OSCs mainly originated from moisture uptake by the poly(3,4-ethylene-dioxythiophene):polystyrene sulfonate (PEDOT:PSS) layer. Using an 70 nm ALD ZnO film for the electron-collection/barrier dual functions as well as a 26-nm Al2O3/HfO2 nanolaminate as the encapsulation layer, we demonstrated flexible OSCs on PET substrates with initial PCE of 2.77% and with negligible air-induced degradation: the OSCs showed near identical degradation rate as the control devices stored in an O2/H2O-free environment, and they retained 73% of their initial PCE over 1800 hr of storage under a 65 ºC/60% RH accelerated aging condition. The results of my study will facilitate the practical applications of OLEDs and OSCs, as well as other types of organic electronics that require precise patterning, interface engineering and hermetic sealing.

The rapid development of polymers and polymer based materials is leading to a number of promising organic devices e.g., solar cells and solid-state lighting, advancing display technology, sensors, and thin-film transistors. One obstacle to this development is the susceptibility of these devices to water vapor and oxygen that causes rapid degradation in many organic electronic devices. In order to maintain the efficiency and guarantee the minimum lifetime needed for various applications, high barrier performance encapsulation materials and structures must be developed. In this work, radio frequency (RF) plasma deposited γ–terpinene thin films were considered as a potential candidate for OPVs, specifically as encapsulation coatings, and as insulating layers in flexible electronics. γ-terpinene is a non-synthetic isomeric hydrocarbon derived from Melaleuca alternifolia essential oil. Thin films from this monomer were fabricated using plasma enhanced chemical vapor deposition in this research work under varied process conditions. The resultant polymer, plasma polymerized γ-terpinene (pp–GT) thin films were found to be optically transparent, with refractive indices in a range of 1.57–1.58 (500 nm). The optical band gap (Eᵍ) of pp–GT thin films were ~3 eV that fell into the insulating Eᵍ region. Independent of deposition conditions, the surfaces were smooth and defect-free, with uniformly distributed morphological features. Films fabricated at higher deposition power displayed enhanced resistance to delamination and wear, and improved hardness, from 0.40 GPa (10 W) to 0.58 GPa (75 W). Investigations on the wetting, solubility and chemical composition of pp–GT thin films revealed that the polymers were structurally dissimilar to the original monomer and highly cross-linked. The polymer surfaces were hydrocarbon-rich, with oxygen present in the form of O–H and C=O functional groups. The oxygen content decreased with deposition power, with films becoming more hydrophobic and, thus, less wettable. The polymers were determined to resist solubilisation in solvents commonly used in the deposition of organic semiconducting layers, including chloroform and chlorobenzene, with higher stability observed in films fabricated at higher RF power. Electrically, pp–GT thin films were highly insulating, possessing decreasing conductivity from 1.39 × 10⁻¹²S/cm (10W) to 1.02 × 10⁻¹³S/cm (75W), attributed to the change in the chemical composition and structure of the polymer. At a frequency of 100 kHz, the dielectric constant varied from 3.69 (10 W) to 3.24 (75 W). The current density–voltage (J−V) characteristics revealed that at higher applied voltage region, Richardson Schottky conduction was the dominant DC conduction mechanism. pp–GT thin films were demonstrated to be optically, physically and chemically stable under the ambient conditions. The bulk of aging occurred after fabrication was attributed to oxidation and volumetric relaxation. Photostability experiments showed that photooxidation takes place under UV irradiation in oxygen–rich conditions. With UV–C light, photodegradation occurred by additional cleavage pathways. Photostability could be improved (UV-C) or completely achieved (UV-A) in an oxygen-poor environment. Finally, fully characterized pp–GT encapsulation layers were integrated with organic PCPDTBT:PC₇₀BM solar cell to validate the effectiveness of the barrier layers. The encapsulated solar cell exhibited very slow decrease in efficiency compared to the nonencapsulated device.

碩士
國立交通大學
材料科學與工程學系所
103
Delamination from the surface of gold (Au)-clad copper (Cu) leadframe occurred when the highly transparent, two-component epoxy molding compound (EMC) was applied to the encapsulation of optical devices. The mismatch of coefficients of thermal expansion (CTE) in between EMC and Cu as well as the relatively poor adhesion of EMC on Au are likely the causes of such a manufacture defect. This study aims to overcome this difficulty by modulating the physical properties of EMC via the concept of nanocomposites. In the prerequisite of preserving the transparency of the EMC, an appropriate amount of nano-scale SiO2 powders serving as the inorganic filler was added in the EMC to reduce its CTE. As to the study of adhesion enhancement, a suitable thiol compound was coated on the leadframe so as to form a strong covalent bond in between Au and the polymeric matrix during the curing treatment of EMC. First, the type of chemical dispersion agents and the size of nano-scale SiO2 powders suitable for the preparation of EMC-SiO2 nanocomposite resin were determined. Via the analyses of transmittance and CTE, GPTMS ((3-glycidoxypropyl)methyldiethoxysilane) and the SiO2 powder with average size of 10 nm were selected as the dispersant agent and inorganic filler for subsequent study. Appropriate amounts of GPTMS and SiO2 were added in EMC precursor under the optimized processing condition and relevant physical properties were characterized. Analytical results indicated the formation of nanocomposite may suppress the CTE of the EMC and mildly increase the adhesion strength on Au-clad leadframe. In the portion of study regarding of the adhesion enhancement, the addition of MPTMS ((3-mercaptoproply)trimethoxysilane) in the EMC was found to efficiently improve the adhesion property. In conjunction with the adhesion enhancement by forming the nanocomposite, more than two-fold increment in adhesion strength of the EMC on Au-clad leadframe was achieved.

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 advancement in smart technologies for organic conducting polymers as flexible substrates in LEDs, PVs and solid state lighting necessitates the development of ultra-high barrier films to protect the devices from moisture and oxygen. The current encapsulation methodology of using layers of plastics and inorganic oxides has several deficiencies. Alternatively, the use of single layer of polymer nanocomposites is a promising substitute for these inorganic based encapsulation layers. The use of polymer materials have the advantage of flexibility, active electrodes printability and easy to make the devices for large area applications. The nano-fillers with high aspect ratio as nanocomposites ingredient in polymers reinforces its mechanical strength and also acts as a scavenging material for moisture and increases the residence time and/or for the penetrating moisture in the film. Chapter 1 gives the basic overview in the field of barrier technology films and coatings from polymers and inorganic oxide as either mono/multi layer hermetic encapsulation methods. The understanding of both chemistry and physics behind the moisture permeation and its interaction with the film material was discussed. The inclusion of functional nano-fillers as moisture trapping agents in the film provide better device protection achieved. The methods and instruments to measure such ultra-low permeation within the films are discussed. Finally, the advantage of polymer based nanocomposites for low-permeable films with existing materials are briefly discussed in this chapter. In this thesis, we employed both thermoplastic and thermoset polymer nanocomposites as encapsulation layer for device sealing. The use of ion-containing polymers (ionomers) as a sealant layer was also studied. Chapter 2 presents the detailed experimental procedures with materials and methods used in this thesis along with the synthesis methodologies to make films from the polymer. In chapter 3, we used cyclic olefin copolymer COC (copolymer of ethylene and norbornene) as an encapsulation layer with silica and layered silicate nano-fillers. The compatibility between hydrophilic silica and hydrophobic COC was achieved by maleic anhydride grafted PE with anchoring on COC as a compatibilizer and then silica filler was added to make the nanocomposite films. FTIR spectroscopy confirms the bond formation of silica with COC/MA-g-PE. The mechanical (tensile and DMA) and thermal studies (DSC) suggested that there is an improvement observed when adding silica/silicate layers in the polymer matrix with increased tensile strength, storage modulus and Tg. The calcium degradation test show enhanced performance towards moisture impermeation in the film. Chapter 4 deals with the synthesis of PVB based nanocomposite film with silica/layered silicate as nanofillers in the base matrix with varying degree of acetalization in the film. The FTIR and NMR spectroscopy show the evidence for acetal link formation in the in-situ synthesized PVB with silica/silicate nanofillers with three different acetyl contents. The tensile and DMA studies show the observed improvement in mechanical strength (increased tensile strength, storage modulus) were due to the intercalation of clay galleries during PVB formation and the interaction of silica particles interactive bond formation with –OH groups of PVA in PVB. The higher clay/silica particles show agglomerated nature and reduction in film strength. Thermal studies (DSC) show that there is an improvement observed in Tg when adding silica/silicate layers in the polymer matrix with moderate to low acetal content. The calcium degradation test show enhanced performance towards moisture impermeation in the film. Chapter 5 describes the inclusion of ionic groups (ionomers) in PVB and its effects on moisture permeation and mechanical properties. PVB ionomer was synthesized using formyl benzene 2-sulfonic acid sodium salt and 2-carboxy benzaldehyde (both sulfonic and carboxylic acid sources) as co-aldehyde with butyraldehyde and PVA. These acid groups were neutralized with potassium, magnesium and zinc ions. The level of acid content in the films was maintained between 6 to 28 mol percent. The sulfonic acid films with zinc and magnesium ions of 14 mol% exhibit good mechanical strength and low moisture permeation. Chapter 6 deals with the epoxy terminated silicone polymer nanocomposites as moisture barrier coatings for device encapsulation. Both silica and clay silicate layers were used to reinforce the silicone matrix. The silica nanoparticles were grafted with amino-silane groups, this would help in better mixing of silica particles in the silicone matrix due to the amine groups interaction in curing with epoxy groups. The calcium degradation test was used to determine the WVTR of the nanocomposites and device encapsulation was employed to estimate the degradation after exposure to ambient environment. Chapter 7 presents the concluding remarks of the results presented. The benefits as well as limitations of the polymer nanocomposite film and the future developmental work to be carried out are discussed in this chapter.

The ultra high barrier films for packaging find applications in a wide variety of areas where moisture and oxygen barrier is required for improved shelf-life of food/beverage products and for microbial free pharmaceutical containers. These materials also find applications in micro electro mechanical systems such as ICs, and for packaging in industrial and space electronics. Flexible and portable organic electronics like OLEDs (Organic Light Emitting Diodes), OPVDs (Organic Photo Voltaic Devices) and dye sensitized solar cells (DSSCs) have a good potential in next generation solar powered devices. In fact, organic insulators, semiconductors, and metals may be a large part of the future of electronics. However, these classes of materials are just an emerging class of materials mainly because of their life time constraints. Thus significant research is required to bring them into the forefront of electronic applications. If the degradation problems can be diminished, then these polymers could play a major role in the worldwide electronic industry. A flexible polymer film itself cannot be used as an encapsulation material owing to its high permeability. While a glass or metal substrate possesses ultra high barrier properties, it cannot be used in many electronic applications due to its brittleness and inflexibility. Polymer/ nanocomposites based hybrid materials are thus a promising class of material that can be used for device encapsulation. Chapter I summarizes some of the recent developments in the polymer/nanocomposites based materials for packaging and specifically its use in flexible as well as portable organic electronic device encapsulation. While the development of low permeable encapsulant materials is a chemistry problem, an engineering/instrumentation problem is the development of an accurate technique that can measure the low levels of permeability required for electronic application. Therefore, there is a keen interest in the development of an instrument to measure permeability at these limits. The existing techniques to measure the low permeabilities of barrier films, their importance and accuracy of measurements obtained by these instruments have been briefly discussed in this chapter. Different polymer based hybrid composite materials have been developed for the encapsulation of organic devices and their materials properties have been evaluated. Broadly, two diverse strategies have been used for the fabrication of the composites: in-situ curing and solution casting. Chapters II, III and IV discuss the fabrication of nanocomposite films based on in-situ curing while chapter V discusses fabrication based on solution casting. In chapter II, amine functionalized alumina was used as a cross-linking agent and reinforcing material for the polymer matrix in order to fabricate the composites to be used for encapsulation of devices. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were used to elucidate the surface chemistry. Thermogravimetric and CHN analysis were used to quantify the grafting density of amine groups over the surface of the nanoparticles. Mechanical characterizations of the composites with various loadings were carried out with dynamic mechanical analyzer (DMA). It was observed that the composites have good thermal stability and mechanical flexibility, which are important for an encapsulant. The morphology of the composites was evaluated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The work presented in chapter III is a technique based on grafting between surface decorated γ-alumina nanoparticles and the polymer to make these nanocomposites. Alumina was functionalized with allyltrimethoxysilane and used to conjugate polymer molecules (hydride terminated polydimethylsiloxane) through platinum catalyzed hydrosilylation reaction. As in the previous chapter, the surface chemistry of the nanoparticles after surface modification was characterized by different techniques (FTIR, XPS and Raman). The grafting density of alkene groups over the surface of the modified nanoparticles was calculated using CHN analyzer. Thermal stability of the composites was also evaluated using thermogravimetric analysis. Nanoindentation technique was used to analyze the mechanical characteristics of the composites. The densities of the composites were evaluated using density gradient column and the morphology of composites was evaluated using SEM. All these studies reveal that the composites have good thermal stability and mechanical flexibility and thus can be potentially used for encapsulation of organic photovoltaic devices. In addition, rheological studies of the composites were carried out to investigate the curing reaction. The platinum-catalyzed hydrosilylation reaction was studied using both DSC and rheological measurements. The competitive reactions occurring in the system was also monitored in real time through DSC and rheology. Based on the curing curves obtained from these two studies, the mechanistic detail of the curing process was proposed. In addition, swelling studies and contact angle measurements of the composites were also carried out to determine the capability of these materials as encapsulants. Chapter IV deals with a thermally stable and flexible composite that has been synthesized by following a hydrosilylation coupling between silicone polymer containing internal hydrides and mesoporous silica. The results of the characterization of the composites indicates that the composites are thermally stable, hydrophobic, flexible and can be potentially used for encapsulating flexible electronic devices. Chapter V discusses the solution casting method for the development of composites. This chapter is divided into two parts: Part I discusses the synthesis and characterization of flexible and thermally stable composites using polyvinyl alcohol as the base polymer matrix and reactive zinc oxide nanoparticles as the dispersed phase. Various studies like thermal analysis, mechanical analysis, surface analysis and permeability studies were used to characterize the composite films for their possible use as a passivation material. The material was used to encapsulate Schottky structured devices and the performance of these encapsulated devices under accelerated weathering was studied. Part II of this chapter discusses the fabrication of hybrid organic/inorganic based polymer-composite films, based on polyvinylbutyral (PVB) and organically modified mesoporous silica. PVB and amine functionalized mesoporous silica were used to synthesize the composite. An additional polyol (‘tripentaerythritol’) component was also used to enhance the –OH group content in the composite matrix. The thermal, barrier and mechanical properties of these composites were investigated. The investigation of these films suggests that these can be used as a moisture barrier layer for encapsulation. Chapter VI gives the concluding remarks of the results presented. The advantages as well as disadvantages of the in-situ cured and solution casted films and the scope for future work is discussed in this chapter.

The generation of new nanoscale fabrication techniques is both novel and necessary for the generation of new devices and new materials. Graphene, a heavily studied and versatile material, provides new avenues to generate these techniques. Graphene’s 2-dimensional form remains both robust and uncommonly manipulable. In this project we show that graphene can be combined with the yeast cell, Saccharomyces cerevisiae, arguably the most studied and utilized organism on the planet, to generate these new techniques and devices. Graphene oxide will be used to encapsulate yeast cells and we report on the development of a method to electrically read the behaviour of these yeast cells. The advantage of an encapsulation process for a cell sensor is the ability to create a system that can electrically show both changes in ion flow into and out of the cell and mechanical changes in the cell surface. Since the graphene sheets are mechanically linked to the surface of the cell, stresses imparted to the sheets by changes in the cell wall or cell size would also be detectable. The development process for the encapsulation will be refined to eradicate excess gold on the yeast cells as well as to minimize the amount of stray, unattached graphene in the samples. The graphene oxide encapsulation process will also be shown to generate a robust substrate for material synthesis. With regards to cell sensing applications, sources of noise will be examined and refinements to the device setup and testing apparatus explored in order to magnify the relevant electrical signal. The spherical topography of an encapsulated yeast cell will be shown to be an advantageous substrate for material growth. Zinc oxide, as a sample material being investigated for its own applications for photovoltaics, will be grown on these substrates. The spherical nature of the encapsulated cell allows for radial material growth and a larger photo-active area resulting in a device with increased efficiency over a planar complement. The zinc oxide nanorods are grown via an electrochemical growth process which also reduces the graphene oxide sheets to electrochemically reduced graphene. XRD analysis confirms that the material synthesized is infact zinc oxide. The nanorods synthesized are 200nm to 400nm in width and 1µm in length. The increase efficiency of the non-planar device and the effectiveness of the encapsulated cell as a growth substrate indicate encapsulated cells as a research avenue with significant potential.

碩士
國立清華大學
化學工程學系
103
We are using a wide range of electronic products in our daily life, and we can hardly live without them. Due to our requirements for modern electronic product - lighter, slimmer , shorter, and smaller, the smaller dimensional specification is expected to fit under the evolution of continuous process. On the other hand, under the highly competitive environment and the pressure of time-to-market, how to provide qualified modern electronic products is a new challenge for the associated package process. Specifically, one of the important defects is non-uniform property result from un-even filler particle distribution, temperature profile, and local gelation change during the package process.To catch the phenomena, CAE simulation is commonly applied. However, most CAE simulations assume the material property is homogeneous, and this assumption will be far from the situation in reality such as regarding to shear-induced migration and particle settling. In this study, a three-dimensional simulation model of non-colloidal filler suspension is proposed to predict the filler concentration in microchips. Firstly, the proposed model is validated using two-dimensional channel and axisymmetrical circular pipe geometry model. Results showed that the trend of filler distribution is in a good agreement. Furthermore, there are various factors caused the inhomogeneity of fillers during the encapsulation of transfer molding processes. Therefore, it's important to figure out what the driving forces or causes are. Study shows there are two main reasons in the processes induce distinct filler concentration distributions after molding - settling and shear migration. We focus on the transfer molding processes in this study, and we discuss different conditions such as transfer time, mold temperrature, resin temperature, which affect the filler distribution. The results show that the transfer time may be the major factor than the others, and they will provide a comprehensive understanding uneven filler concentration after encapsulation. By using the integrated analysis, filler concentration under deferent working condition during encapsulation can be easily predicted, so as to efficiently reduce manufacturing cost and design cycle time.

碩士
國立臺北科技大學
材料科學與工程研究所
101
Recently, the optoelectronic industry develops rapidly to increase the requirement of thinner and lighter properties for flat panel display products. Undoubtedly, the fabrication of organic light emitting diode (OLED) on flexible plastic substrate was the major technique in the next flat display generation. The encapsulation of organic semiconductor devices with the concept of multilayer films onto the devices and conductors is the major trend of producing thin and light weight devices for the industrial and research. However, ,the low process temperature of the multilayer films onto the devices exhibits with poor film quality and will cause leakage path by moisture and oxygen which will induce the failure of products after the opening process of contact pads. In this study, to minimize the possible leakage path by moisture and oxygen in the devices, a new technique fortifying the lifetime and reliability of flexible device will be introduced on protecting the sidewall of contact pads after the opening process. The study started with the photolithography process producing 100 x100 μm2 pattern devices to simulate the opening position of contact pads. We encapsulated the device by gas barriers that were produced with magnetron-sputtering system. The gas barriers of thin film layer structure are made with SiO2, Al, SiO2/Al, SiO2/Al (two pairs) respectively and etched in blanket way to form the SiO2 spacer films onto the sidewall of contact pads. By measuring the water vapor transmission rate (WVTR, at 32°C and RH 100%), it was found that the gas barriers of the two sidewall of Al/SiO2 (two pairs) performed well to prevent degradation; It was reduced from the original 2.50x10-5 g/m2-day to 1.21x10-5 g/m2-day after processing. This study has successfully developed a simple sidewall structural design barrier technology.

碩士
國立雲林科技大學
化學工程與材料工程系
107
This study research that the pectin polysaccharide extracted from Ficus awkeotsang Makino seeds 0.1 M EDTA was added during the extraction of Ficus awkeotsang Makino and the capsule encapsulating hydrophobic substance was produced by a milli-fluidic device. First, the characteristics of the fabricated Ficus awkeotsang Makino the film was transformed by Fourier transform Infrared light, moisture content, water permeability and then analysis. Ficus awkeotsang Makino the seed is a rich source of polysaccharides gel, its main component is low-methyl pectin, low-methyl pectin and metal ions will form a network cross-linking, so come evaluation of the suitability as a capsule. Studies have shown that the film produced by Ficus awkeotsang Makino extracted with EDTA has a stronger structure than the film without EDTA extraction and the loss rate of the film of the calcium ion and the EDTA extraction film in the in vitro erosion test. 52% and 47%, respectively, demonstrating that the film extracted using EDTA has less solubility in the gastrointestinal tract than the unused EDTA. And adding glycerin as a plasticizer, the gel structure is increased in elasticity, and the capsule is not easily broken when dried. Under the optical micrograph. By controlling the flow, the core diameter of 1.4 mm -1.9 mm and the gel has an outer diameter of 2.1 mm -2.8 mm core-shell capsules, it can be seen that there is a successful encapsulate of soybean oil with red dye in the capsule, and there is a clear boundary, which proves that the milli-fluidic device can successfully encapsulate the capsule with the hydrophobic substance and can also be stable control the production of capsules of different diameter Keywords: Ficus awkeotsang Makino polysaccharide, hydrophobic bioactives, milli-fluidic device.

博士
國立交通大學
材料科學與工程系所
97
This thesis studied the preparation of various ultraviolet (UV)-curable polymeric composite resins (i.e. PU-acrylate/silica (weight ratio = 90 wt.%/10 wt.%), silicone-acrylate/Alumina (weight ratio = 90 wt.%/10 wt.%) as well as epoxy-acrylate/silica/Invar (weight ratio = 35 wt.%/50 wt.%/15 wt.%) and their applications for the packaging of organic light-emitting devices (OLEDs), organic solar cells (OSCs) and light-emitting diodes (LEDs). In the part of study relating to OLEDs, the lifetimes of devices were successfully enhanced by modulating the LiF thickness and utilizing the UV-curable silicone-acrylate adhesives for encapsulation. It was found that the LiF and lab-made encapsulating adhesives can effectively block the invasion of moisture as well as oxygen in the atmosphere into the OLEDs so that an 18-folds increment of lifetimes was achieved after encapsulation. A low turn-on voltage (3 V), high luminance (4850 cd/m2 at 9 V), color/luminance tunable OLED with device structure as ITO glass/naphthyl phenyl benzidine (NPB; 80 nm)/4,4’-bis(diphenylvinylenyl)- biphenyl (ADS082BE; 35 nm)/1,3-bis[2-(2,2’-bipyridine-6-yl)-1,3,4-oxadiazo-5-yl] benzene (Bpy-OXD; 20 nm)/tris-[8-hydroxy- quinoline]aluminum (Alq3; 50 nm)/lithium fluoride (LiF; 3 nm )/aluminum (Al; 80 nm) was successfully fabricated in this study. Its electroluminescent properties (e.g., hue, luminescent intensity, etc.) could be modulated by the manipulation for the layer thickness of NPB/ADS082BE/Bpy-OXD and the applied bias. In addition, the UV-curable silicone-acrylate encapsulating resin exhibited excellent gas barrier capability so that the half-lifetimes of OLEDs and LEDs reached 98 and 18300 hrs while those without encapsulation were only 9 and 2400 hrs. The UV-curable epoxy-acrylate nanocomposite resins with good thermal stability, moderate adhesion strength and excellent gas barrier capability were also prepared in this work. In order to improve the gas blocking properties, the Invar alloy was also blended into the resins so as to increase the gas resistance and decrease resin shrinkage after UV curing. Experimental results revealed that introduction of epoxy-acrylate nanocomposite resins could effectively block the penetration of moisture as well as oxygen in the air into the devices and consequently promoted the lifetimes of OSCs. Fabrication of polymeric reflector cups for LEDs by using polyphenylene sulfide/poly(ethylene terephthalate) (PPS/PET) and PPS/nylon 6,6/glass fiber alloys via injection molding process was also presented in this work. In order to enhance their mechanical properties, the compatibilizer, PE-g-GMA, was first developed by grafting the glycidyl methacrylate (GMA) into the low-density polyethylene (LDPE) with initiators by reactive extrusion procedure in a twin screw extruder. PPS/PET and PPS/nylon 6,6/glass fiber alloys with various amounts of PE-g-GMA (PPS/PET/PE-g-GMA (wt./wt./wt.)=100/50/12.5; PPS/Nylon 6,6/Glass Fiber Alloy/ PE-g-GMA(wt./wt./wt./wt.) =100/50/45/12.5) were then prepared and their physical properties as well as feasibilities for the high-brightness LEDs were also analyzed.

碩士
國立清華大學
奈米工程與微系統研究所
104
In this study, a cell-in-droplet encapsulation using dean flow in spiral microchannel device is applied for microalgae separation. Researchers are interested in separating microparticles by using microfluidic chips in recent years due to great advantages for variety kinds of related applications such as biotechnology, medical examinations, or cell studies. However, the main disadvantage of these microfluidic chips is that it usually would experience particles clogging which reduces the separation yield and hard for particles investigation. The microfluidic chip being introduced in this study is a combination of 2 distinct designs: (1) spiral microchannel design used for separating different sizes of microalgae and (2) microdroplet generation design used for cell encapsulation. The reason is to enhance the separation yield by using different dominant forces concept (Dean drag force and lift force) in spiral microchannel design together with microdroplet generation design narrow down the volume for easier cell observation. The microfluidic chip was fabricated by using soft lithography techniques. Polydimethylsiloxane (PDMS) is well known as biocompatible material, low cost of production, disposable, more over it is transparency makes it possible to observe particles inside the microchannel clearly. Due to all of these benefits, this device might be an alternative for cell applications using droplet-based platforms.

碩士
國立雲林科技大學
電子與資訊工程研究所
95
In this research, effects of dual-metal gate oxide layer－HfTiOx on MIS capacitor with different gate metals are studied first. We use RF sputtering to deposit Hf and Ti metal layers on n-type (100) Si substrate, and then use anodic oxidation to transfer them into an oxide layer of HfTiOx at room temperature. Finally, we deposit different gate metals with Al, Hf and Ti to fabricate MIS capacitors. C-V and I-V measurements were performed respectively by using Keithley 236 and Keithley 590 I-V & C-V analyzer. From experimental results, the sample of HfTiOx with Ti electrode shows a higher dielectric constant k（~ 75）and better electrical characteristics. It indicates that the method of film deposition in this research shows lower prime cost and increases dielectric constant（k > 25）effectively. Different gate electrodes have shown similar results. It also indicates that the gate metal of Ti has the ability of oxygen decomposition, identical physical thicknesses with a higher capacitance storage density and a lower EOT (Equivalent Oxide Thickness). Furthermore, we apply results of the high-k oxide layer to MOSFETs with device encapsulation. At first, we use RF sputtering to deposit the metal layer of Hf or dual-metal gate oxide layer of Hf and Ti on MOSFET with doped n+ region, and then use anodic oxidation to transfer them into an oxide layer of HfO2 or HfTiOx at room temperature. Finally, we use device encapsulation to fabricate MOSFETs. Variations of ID－VDS and ID－VGS for I-V measurements were measured by using Keithley 236 I-V analyzer. Results show that the threshold voltage of oxide layers of HfO2, HfTiOx, HfTiOx ( 72 hours later ) are 1.75 V, 0.5 V and 0.3 V, respectively. The effective mobility ( μeff ) of HfO2, HfTiOx, HfTiOx ( 72 hours later ) are 120 cm2/V-s, 223 cm2/V-s and 227 cm2/V-s, respectively. It indicates that MOSFETs with device encapsulation shows lower prime cost, lower fabrication risks and reproducible characteristic. It not only raises mobility effectively but also reduces substrate bias effects and channel length modulation. It also enhances device stability, ambient-enduring performance, convenience and re-use times for measuring.