L'électronique organique représente une alternative réaliste aux technologies conventionnelles à base de silicium par le design, la synthèse et la mise en oeuvre des matériaux organiques fonctionnels dans des dispositifs légers et flexibles. Les matériaux organiques, tels que les petites molécules ou les polymères organiques, sont avantageux pour leur faible coût, leur flexibilité et leur facilité de traitement. Grâce aux avantages liés à l'utilisation de matériaux organiques, en termes économiques et de gain de temps, l'électronique organique est devenue un domaine innovant qui s'applique aux technologies de l'énergie, de l'environnement, de la santé, de l'information et de la communication.L'électronique organique est issue de la découverte de polymères dotés de fonctionnalités semi-conductrices. Cependant, il ne faut pas négliger une autre classe de polymères exceptionnels, les polymères ferroélectriques. La nature électroactive des polymères ferroélectriques, qui sont également pyroélectriques et piézoélectriques, combinés aux avantages intrinsèques des polymères, les a désignés comme éléments constitutifs d’une gamme étendue de dispositifs électroniques organiques.La famille de polymères ferroélectriques la plus connue est celle du poly(fluorure de vinylidène) P(VDF) et de son copolymère avec le trifluoroéthylène, P(VDF-co-TrFE). La récupération d'énergie, le stockage et la détection de données, principales applications de l'électronique organique, peuvent potentiellement tous être réalisés avec ces matériaux fonctionnels exceptionnels. La ferroélectricité étant une propriété dépendant de la structure, il est indispensable de mieux comprendre les relations réciproques entre la structure et les propriétés ferroélectriques finales afin d'améliorer les applications existantes des polymères ferroélectriques en électronique organique et de promouvoir l'introduction du P(VDF-co-TrFE) dans de nouvelles applications.P(VDF-co-TrFE) en tant que polymère semi-cristallin possède des propriétés cristallines sensibles au traitement thermique. Puisque seules les régions cristallines contribuent a le commutation électronique de la polarisation et non les amorphes, le degré de cristallinité est un facteur clé pour moduler les propriétés ferroélectriques. En autre, l'orientation des cristallites ainsi que la présence de défauts dans les cristallites sont des paramètres cruciaux qui jouent un rôle important dans la définition des performances finales des dispositifs dans lesquels P(VDF-co-TrFE) est incorporé. Tel est l'objectif de cette thèse: atteindre une compréhension exhaustive des relations traitement-structure-fonction qui serviront d'outil pour moduler les performances des dispositifs ferroélectriques.De plus, les applications potentielles de P(VDF-co-TrFE) en électronique organique sont explorées en examinant sa mise en oeuvre dans: (1) des capteurs médicaux à cathéter piézoélectrique destinés à mesurer la fonction cardiaque et éventuellement à détecter maladies cardiaques et (2) dispositifs électroniques dans lesquels P(VDF-co-TrFE) est mélangé avec le polymère poly(3-hexylthiophène) semi-conducteur, P3HT. Ce dernier a déjà été appliqué dans les diodes à mémoire ferroélectrique non volatile et l’utilisation potentielle dans le champ de l’organique photovoltaïque est explorée. / Organic electronics represent a realistic alternative to conventional silicon-based technologies through the design, synthesis and implementation of functional organic materials into light and flexible devices. Organic materials, such as small molecules or organic polymers, are advantageous for their low-cost, flexibility and easy processing. Thanks to the economical and timesaving advantages, organic electronics have emerged as an innovative field with application in energy, environment, health, information and communication technologies.Organic electronics originates from the discovery of polymers with semiconducting functionalities. However, one should not neglect another class of outstanding polymers, the ferroelectric polymers. The electroactive nature of ferroelectric polymers, which are also pyroelectric and piezoelectric, combined with the intrinsic advantages of polymers have designated them as constituent elements of a widespread range of organic electronic devices. The most well-known family of ferroelectric polymers is that of poly(vinylidene fluoride), P(VDF), and its copolymers with trifluoroethylene, P(VDF-co-TrFE). Energy harvesting, data storage and sensing, main applications of organic electronics, can potentially all be realised using these exceptional functional materials.Since ferroelectricity is a structure-dependent property an insight into the interrelations between structure and final ferroelectric properties is indispensable in order to improve existing applications of ferroelectric polymers in organic electronics and to promote the introduction of P(VDF-co-TrFE) in new application fields. P(VDF-co-TrFE) as semi-crystalline polymer possess crystalline properties which are sensitive to thermal treatment. Since only the crystalline regions contribute to ferroelectric switching and not the amorphous ones, the degree of crystallinity is a key factor to modulate the ferroelectric properties. Moreover, crystallites orientation as well as the presence of defects within the crystallites are crucial parameters playing an important role in defining the final performance of the devices in which P(VDF-co-TrFE) is incorporated.Herein stands the aim of this thesis: reach an exhaustive understanding of processing-structure-function relationships that will serve as tool to modulate ferroelectric devices performances.Going one step further, the potential applications of P(VDF-co-TrFE) in organic electronics are explored by investigating it in: (1) medical piezoelectric catheter sensors for measuring cardiac function and eventually for detecting cardiac disease and (2) electronic devices in which P(VDF-co-TrFE) is blended with the semiconducting polymer poly(3-hexylthiophene), P3HT. The latter has already been applied in non-volatile ferroelectric memory diodes and the potential use in organic photovoltaics is explored.

The rapid development of organic electronics is leading to a number of promising devices in the area of energy sources and conservation (e.g., solar cells and solid-state lighting), while also advancing display technology, sensors, and thin-film transistors. One obstacle to this development is the susceptibility of these devices to water vapor and oxygen, which are well known to cause rapid degradation in many organic electronic devices. In order to guarantee the minimum lifetime needed for various applications, high barrier performance encapsulation materials and structures must be developed and has been the object of much experimental research. However, there is a dearth of comprehensive studies which link the characterization, modeling, and integration of ultra-high barrier films with organic electronics. Such studies are necessary in order to advance the understanding of thin-film encapsulation and to find methodologies which greatly improve its performance. The present work investigates the processing and development of high quality single-layer and multilayer encapsulation architectures for ultra-high barrier films. For compatibility with organic electronics, this study focuses on low temperature fabrication processes which can lead to poor film quality. To circumvent the issue of defects, multilayer encapsulation films with alternating inorganic and organic layers were used to provide ultra-low permeation films. By reducing the complexity of typical multilayer architectures, a new encapsulation processing procedure was developed which combines a plasma enhanced chemical vapor deposition fabricated inorganic film followed by a high quality film deposited by atomic layer deposition. The improvements that this hybrid film provided were through the quick coating of the device via plasma-based deposition followed by a short atomic layer deposition exposure to seal the defects in the first film. The barrier performance of all thin-film encapsulation was characterized in terms of the effective water vapor transmission rate (WVTR) by using Ca corrosion tests. A detailed study of the water vapor permeation mechanism through thin-film layers was presented. Finally, fully characterized encapsulation layers were integrated with organic solar cells to validate the effectiveness of the barrier layers. The compatibility of the encapsulation process with organic devices was investigated by comparing the performance parameters of organic device before and after encapsulation. The parameters of encapsulated organic devices with various encapsulation structures were compared with their initial values as a function of exposure time to atmosphere to provide a link between effective WVTR and shelf-lifetime of encapsulated organic devices.

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.