The research provided in this thesis focuses on the development of high-gain multilayer millimeter-wave (mm-Wave) antenna structures through additive inkjet printing fabrication processes. This work outlines the printing processes of thick dielectric films for use as printed radio frequency (RF) substrates and provides a proof-of-concept demonstration of the first fully-printed RF structures. Using the outlined processes, demonstrations of high-gain mm-Wave proximity-coupled patch array and Yagi-Uda array antennas are presented, achieving the highest realized gain within the 24.5 GHz ISM band for inkjet-printed antennas in literature.

Transparent electrodes (TEs) require materials that have both transparency and electrical conductivity, a combination not usually found in nature. They are in increasing demand for use in solar cells, touch screens, displays, transparent heating films and several other devices. Most TEs used today are made of indium tin oxide (ITO). However, it has several disadvantages, such as high fabrication cost, rigidity and brittleness. Many ITO alternatives are being pursued, among which metallic nanowire (NW) networks on transparent substrates such as glass or polymer, have received much attention. This thesis demonstrates ordered silver NW networks on polyimide, fabricated by the field-directed chaining technique. We achieved a sheet resistance of 27 Ω/sq and 95.4% transparency at 550nm, with a Figure of Merit (FOM) 0.023Ω-1, which is higher than the FOM of commercial ITO, 0.005Ω-1. We have demonstrated that ordered NW networks, directed by alternative current (AC) electric fields, are easy to fabricate over a large area and at low cost, on rigid and flexible substrates. The AC electric field changes with different experiment setup. In this work, the effect of polymer thickness, electric field frequency, and gap size between electrodes are explored by COMSOL simulation and validated experimentally. By choosing the appropriate frequency and gap size, ordered NW networks are successfully created on a 23μm polyethylene terephthalate (PET) sheet. Fluid motion is one of the disruptors during NW chaining. We demonstrate control of this disruptor by the use of sandwiched channels for the NW suspension. Post-fabrication treatments are important and necessary for improving the connectivity and conductivity of Ag NW networks. In this work, we explore Joule heating and show its potential to improve the conductivity over other post-treatment approaches. However, Joule heating can also cause failures of NW networks. Ordered NW networks present better optical-electrical properties than random NW networks. Post-fabrication treatment can improve the properties, but there is a limit. In this work, a mathematical model is built for optical-electrical properties of perfectly ordered NW networks, which sets the upper bound of performance for transparent electrodes made of NW networks. A linear relationship is found between the transmittance and inverse sheet resistance. The model is then modified with factors to account for departure from the ideal. / Graduate / 2019-12-12

<p>  </p> <p>Integration of functional thin films on flexible substrates has piqued interests owing to the needs of flexible devices. Selecting a suitable flexible substrate is crucial for such integration. Recently, muscovite mica has been developed as a flexible platform for functional thin film epitaxy growth. Mica can be easily peeled off due to the weak van der Waals interaction between different layers of mica, along with other advantages including cheap, high elasticity and thermal stability, biocompatible, <em>etc</em>. On the other hand, vertically aligned nanocomposites (VANs) have been attractive because of their unique anisotropic structures, which can achieve physical property anisotropy, easy tunability, out-of-plane strain engineering as well as combined multifunctionality. However, limited work on the integration of nanocomposite thin films on mica with tunable physical properties has been reported due to growth challenges. </p> <p>In this dissertation, different ceramic-metal VAN systems integrated on mica substrates towards different functionalities using pulsed laser deposition (PLD) have been demonstrated. The first chapter is on the integration of BaTiO3-Au nanocomposite system on mica. Tunable optical properties have been achieved by controlling the geometries of the Au nanostructures between nanoparticles and nanopillars by varying the growth temperature. The laser energy was also found to play a role in terms of the Au pillar dimension. The second chapter is on the integration of BaZrO3-Co VAN system on mica towards flexible spintronics. Tunable, anisotropic ferromagnetic property has been realized by controlling the aspect ratio of the Co pillars. The third chapter is on integration of BaTiO3-Fe VAN system on mica towards multiferroics. Different buffer layers have been tried out to facilitate the growth of VAN structure. Room temperature ferroelectric and anisotropic ferromagnetic properties of the films have been confirmed. The last chapter is focused on multiphase nitride-metal nanocomposite design and integration, with films showing unique optical and magnetic properties. The reliability and stability of the physical properties of the films have been verified though bending tests. The growth mechanism and criteria of ceramic-metal nanocomposite on mica have also been discussed. These demonstrations all pave a new way towards the integration and design of multifunctional nanocomposites towards flexible nanodevices.</p>

No description available.

Dans le contexte de la mise au point de dispositifs photovoltaïques efficaces, bon marché et respectueux de l’environnement, la synthèse d’oxydes métalliques semi-conducteurs tels que SnO2, Zn2SnO4 et WO3 de morphologies et textures diverses a été développée afin d’élaborer des photoanodes poreuses pour cellules solaires à colorant. D’après les études réalisées par différentes méthodes (MEB, MET, DRX et BET), les matériaux obtenus présentent des caractéristiques texturales, morphologiques et structurales appropriées pour l’application visée. Des cellules solaires à colorant ont donc été réalisées à partir de ces oxydes, puis différents paramètres influençant leurs performances ont été optimisés afin d’améliorer l’efficacité de la conversion photovoltaïque. Notamment l’influence positive de différents traitements des photoanodes (i.e. solution aqueuse de TiCl4 ou traitement à l’eau) sur les rendements de conversion énergétique et la stabilité des dispositifs a été démontrée. Ainsi, des performances comparables ou supérieures à l’état de l’art ont été atteintes pour les systèmes à base de SnO2. Ces performances ont ensuite été interprétées en déterminant les processus électroniques et ioniques ayant lieu dans ces cellules par différentes méthodes physiques (mesures de tension de seuil et de décroissance de circuit-ouvert, spectroscopie d’impédance). Enfin, des électrodes réalisées à partir de WO3 déposé sur substrats flexibles ont démontré des propriétés électrochromes très prometteuses ce qui ouvre de nouvelles perspectives dans le domaine de l’affichage. / In the context of the development of efficient, low-cost and environmentally friendly photovoltaic devices, the synthesis of metal-oxide semiconductors such as SnO2, Zn2SnO4 and WO3 with various textures and morphologies have been developed in order to achieve nanoporous photoanodes for dye-sensitized solar cells. According to studies carried out by different characterization methods (SEM, TEM, XRD and BET), the resulting materials show interesting features for the expected application. Dye solar cells were then fabricated from photoanodes processed with these oxides and several parameters influencing their performance were optimized to improve the overall conversion efficiency. In particular, the beneficial effect of different treatments of the photoanodes (ie aqueous TiCl4 or water treatment) on the power conversion efficiency and the stability of the devices has been evidenced. Thus, state-of-the art or, even, record efficiencies were reached in the case of SnO2-based systems. These performances were then rationalized by determining the electronic and ionic processes occurring in these devices by various physical methods (threshold voltage and open-circuit photovoltage decay measurements, electrochemical impedance spectroscopy). Finally, electrodes based on WO3 and deposited on flexible substrates have shown very promising electrochromic properties, which opens up new prospects in the field of smart displays.

A new manufacturing paradigm may lower the cost and environmental impact of existing products, as well as enable completely new products. Large scale, roll-to-roll manufacturing of flexible electronics and other functionality has great potential. However, a commercial breakthrough depends on a lower consumption of materials and energy compared with competing alternatives, and that sufficiently high performance and reliability of the products can be maintained. The substrate constitutes a large part of the product, and therefore its cost and environmental sustainability are important. Electrically conducting thin films are required in many functional devices and applications. In demanding applications, metal films offer the highest conductivity.   In this thesis, paper substrates of various type and construction were characterized, and the characteristics were related to the performance of inkjet-printed metal patterns. Fast absorption of the ink carrier was beneficial for well-defined pattern geometry, as well as high conductivity. Surface roughness with topography variations of sufficiently large amplitude and frequency, was detrimental to the pattern definition and conductivity. Porosity was another important factor, where the characteristic pore size was much more important than the total pore volume. Apparent surface energy was important for non-absorbing substrates, but of limited importance for coatings with a high absorption rate. Applying thin polymer–based coatings on flexible non-porous films to provide a mechanism for ink solvent removal, improved the pattern definition significantly. Inkjet-printing of a ZnO-dispersion on uncoated paper provided a thin spot-coating, allowing conductivity of silver nanoparticle films. Conductive nanoparticle films could not form directly on the uncoated paper.   The resulting performance of printed metal patterns was highly dependent on a well adapted sintering methodology. Several sintering methods were examined in this thesis, including conventional oven sintering, electrical sintering, microwave sintering, chemical sintering and intense pulsed light sintering. Specially designed coated papers with modified chemical and physical properties, were utilized for chemical low-temperature sintering of silver nanoparticle inks. For intense pulsed light sintering and material conversion of patterns, custom equipment was designed and built. Using the equipment, inkjet-printed copper oxide patterns were processed into highly conducting copper patterns. Custom-designed papers with mesoporous coatings and porous precoatings improved the reliablility and performance of the reduction and sintering process.         The thesis aims to clarify how ink-substrate interactions and sintering methodology affect the performance and reliability of inkjet-printed nanoparticle patterns on flexible substrates. This improves the selection, adaptation, design and manufacturing of suitable substrates for inkjet-printed high conductivity patterns, such as circuit boards or RFID antennas.

Depuis les années 2000, l'impression fonctionnelle connait un grand succès pour la fabrication de composants électroniques. Elle se positionne de manière complémentaire par rapport aux technologies du silicium et vise principalement les marchés de l'électronique grande surface (écrans, panneaux photovoltaïques) et de l'électronique flexible (RFID, capteurs, textiles intelligents). Dans ce travail, des couches d'argent imprimées par jet d'encre ont été caractérisées en fonction des conditions d'impression et de recuit. L'évolution de leur microstructure, de leurs propriétés électriques et mécaniques a été étudiée. Dans ce cadre, des méthodes expérimentales ont été développées et validées par la bonne corrélation entre les mesures et les modèles. La maîtrise des propriétés de ces couches et l'optimisation de leur procédé de fabrication nous ont conduits à concevoir, fabriquer et caractériser plusieurs composants flexibles: un filtre passe bande centré à 17 GHz sur un substrat polyimide, un micro-capteur de vide fonctionnant sur le principe de Pirani et un bouton-poussoir d'épaisseur inférieure à 250 µm pour des claviers souples. Enfin, des condensateurs RF ont été réalisés par la superposition de couches imprimées diélectriques (BaSrTi) et conductrices (Ag). Les performances des prototypes réalisés sont proches de l'état de l'art et ouvrent la voie à de nouvelles applications pour les technologies d'impression. Cette étude démontre le potentiel des couches d'argent imprimées par jet d'encre pour la fabrication de dispositifs flexibles. / In the last decade, functional printing has gained a large interest for the manufacturing of electronic components. It stands aside to silicon technologies and specifically targets markets of large area devices (screens, photovoltaics) and flexible electronics (RFID antennas, sensors, smart textiles). In this work, inkjet printed silver layers are characterized depending on the printing conditions and the required post-printing annealing. The evolution of their microstructure, electrical and mechanical properties is investigated as a function of the annealing temperature. The correlation of the measurements with theoretical models supports the experimental methods that were developed. The knowledge of the printed silver layers assets and the optimization of the printing process lead to the design, fabrication and characterization of flexible electronics devices: a 17 GHz band-pass filter printed on polyimide, a flexible vacuum micro-sensor working on the Pirani principle, and a 250 µm thick membrane switch for keyboards. Finally, all printed RF capacitors were realized by stacking Barium Strontium Titanate (dielectric) and silver printed layers. These prototypes exhibit performances near the state-of-the-art and suggest new opportunities for printing technologies. This thesis offers a thorough study of inkjet printed silver layers and assess their potential for the manufacturing of flexible devices.

Les travaux précédents du laboratoire Hubert Curien ont permis d’élaborer des films photosensibles Ag : TiO2 sur verre, support de marquage de motifs actualisables ou permanents. Une adaptation de ces travaux aux supports plastiques et papiers est ici proposée afin d’élargir les domaines d’application potentiels au marquage sécurité des produits par exemple. Des techniques d’élaboration de films Ag : TiO2 compatibles avec les substrats considérés ont donc été développées. Deux voies ont été envisagées. La première utilise la chimie du Sol-Gel combinée à la méthode EISA et des procédés de dépôt tel le spin-coating, le jet d’encre ou la flexographie pour former un film mésoporeux de TiO2 sur les supports. Des traitements basés sur une extraction par solvant ou un recuit infrarouge ont été imaginés afin de libérer la porosité du film sans dégradation du support. Pour réaliser les films sur papier, un sel d’argent est ajouté au Sol avant son dépôt. Dans les cas des films élaborés sur plastique, l’argent est incorporé par imprégnation du matériau dans une solution de sel d’argent. La deuxième voie d’élaboration propose de formuler une encre aqueuse jet d’encre de nanoparticules de TiO2 et d’ions argent, en adaptant la composition d’une suspension commerciale de TiO2 aux exigences du jet d’encre. Après dépôt, l’encre est séchée par recuit infrarouge. Le comportement photochromique sous expositions lumineuses UV et visible des différents films permet leur coloration et décoloration de façon réversible. Les films Sol-Gel déposés sur plastique peuvent également être support de photo-inscriptions permanentes générées par irradiation par une lumière visible d’une certaine intensité / Previous research conducted at laboratory Hubert Curien led to the development of photosensitive Ag: TiO2 films on glass as support for updatable or permanent patterns. An adaptation of this work to plastic and paper substrates is proposed here to broaden the possible application areas such as goods secure labeling, for example. Fabrication techniques of Ag: TiO2 films compatible with flexible substrates have been developed, using two different paths. The first uses the combination of Sol-Gel chemistry with the EISA method. Deposition processes such as spin coating, inkjet or flexographic printing are used to form a mesoporous film of TiO2 on substrates. Treatments based on solvent extraction or infrared annealing have been devised to release the porosity of the film without damaging the supports. Silver salt is either introduced into the titania pores by soaking the films into a silver salt solution or added to the sol before its coating. The second developed option proposes formulating an aqueous ink jet ink made of TiO2 nanoparticles and silver ions by adapting the composition of a commercial suspension of TiO2 with the requirements of the ink jet process. After printing, the ink is dried by infrared annealing. The photochromic behavior under UV and visible light exposures of fabricated films allows to get coloring and bleaching reversibly. Sol-Gel films coated on plastic can also be a support for permanent colored patterns realized by irradiation with a visible light of certain intensity

Deposition of nanoscale thickness films is ubiquitous in micro- and nano-scale device manufacturing. Current techniques such as spin-coating and chemical vapor deposition are designed to create only uniform thin films, and can be wasteful in material consumption. They lack the ability to adaptively prescribe desired film thickness profiles. This dissertation presents a novel inkjet-based zero-waste polymer deposition process referred to as Jet and Coat of Adaptive Sustainable Thin Films or J-CAST. The core of this process is built on an experimentally validated multi-scale fluid evolution model, based on extensions of lubrication theory. This model involves a nano-scale fluid film sandwiched between two flat plates: a compliant superstrate and a rigid substrate, with spatial topography on both surfaces. Accounting for the flexural elasticity of the compliant superstrate, and describing the temporal evolution of the fluid film in the presence of different boundary conditions reveals that instead of seeking process equilibrium, non-equilibrium transients should be exploited to guide film deposition. This forms the first core concept behind the process. This concept also enables robust full-wafer processes for creation of uniform films as well as nanoscale films with prescribed variation of thickness at mm-scale spatial wavelengths. The use of inkjets enables zero-waste adaptive material deposition with the preferred drop volumes and locations obtained from an inverse optimization formulation. This forms the second core concept behind the process. The optimization is based on the prescribed film thickness profile and typically involves >100,000 integer parameters. Using simplifying approximations for the same, three specific applications have been discussed - gradient surfaces in combinatorial materials science and research, elliptical profiles with ~10km radius of curvature for X-ray nanoscopy applications and polishing of starting wafer surfaces for mitigation of existing nanotopography. In addition, the potential of extending the demonstrated process to high throughput roll-roll systems has also been mentioned by modifying the model to incorporate the compliance of the substrate along with that of the superstrate. / text

Depuis une vingtaine d'années, des composants électroniques flexibles sont développés. Ces composants étant amenés à se tordre, à s'étirer et à se fléchir au cours de leur utilisation, le développement de composants ayant une bonne fiabilité mécanique est primordial. Ce travail s'est concentré sur les films métalliques d'argent déposés par impression jet d'encre ou sérigraphie sur des substrats de polyimide, servant à l’interconnexion électrique entre composants actifs. Deux mécanismes d’endommagement sont observables dans ces systèmes : la fissuration et le flambement par délaminage.Premièrement, pour caractériser expérimentalement ces deux phénomènes, des tests de traction sont réalisés sous microscope optique, afin de suivre l'évolution des fissures au cours de la déformation et sous interféromètre optique, afin de suivre les cloques de délaminage. Une analyse d'images est réalisée afin d'obtenir l'évolution de l'espacement entre fissures au cours de la déformation. L'existence de deux régimes de fissuration est observée : la fissuration longue et droite pour les films épais et la fissuration courte et en forme de zigzag pour les films minces. Le suivi des profils de cloques permet d'obtenir l'évolution de leur forme au cours de la déformation.Ensuite, afin d'éclairer les observations expérimentales, les phénomènes à l'étude sont modélisés par élément finis. Ainsi l'origine des deux régimes de fissuration est expliquée par un effet géométrique de l'épaisseur du film. Un modèle élastoplastique bidimensionnel de relaxation de contraintes dans le film permet d'obtenir un encadrement de l'espacement entre fissures au cours de la déformation. À partir du suivi des cloques, un modèle tridimensionnel permet de réaliser une identification des paramètres de la zone cohésive à l'interface film/substrat, où une énergie d'adhésion de 2 J.m-2, une contrainte critique de 20 MPa et un paramètre de mixité modale de 0,4 sont déterminés. Ces valeurs sont en accord avec la littérature. / Over the past 20 years, new improvements in materials and processes led to the development of printed flexible electronics. Flexible electronics devices subjected to bending, twisting, or stretching during their lifetime, the development of device with high reliability is therefore of great importance for the efficiency of electrical connection. This work investigates the mechanical reliability of inkjet or screen-printed Ag thin films on polyimide substrates dedicated to the electrical interconnection of active components. Expected mechanical failure modes are film cracking and buckling delamination.First of all, in order to characterized the two mechanisms, tensile tests are performed under an optical microscope to follow cracks and under an optical interferometer to follow buckles. In order to obtain crack spacing evolution during deformation, an image processing is realized. Two types of cracks are observed: long and straight cracking for thick films and small and zigzag shape cracking for thin films. The evolution of buckles shape with imposed tensile deformation is characterized.In a second time, in order to understand experimental observations, mechanical failure modes are analysed with finite elements models. The origin of the two types of cracking are explained by a geometrical effect of film thickness. A elastoplastic shear lag bidimensional model gives upper and lower bonds of crack spacing during deformation. A three-dimensional model allows identification of cohesive zone model parameters at film/substrate interface, from experimental buckle shape. An adhesion energy of 2 J.m-2 , a critical strength of 20 MPa and a mode mixity parameter of 0.4 are determined. These values are in good agreement with literature.