Silver nanowire transparent electrodes have recently received much attention as a replacement for indium tin oxide (ITO) for use in various electronic devices such as touch panels, organic solar cells, and displays. The fabrication of silver nanowire electrodes on glass substrates with a sheet resistance as low as 9 Ω/□ and 90% optical transparency at 550 nm is demonstrated. These resistance and transparency values match that of commercially available indium tin oxide and are superior to other alternatives such as carbon nanotube electrodes. The nanowire electrodes are low cost and easy to fabricate. Moreover, by depositing nanowire films on plastic substrates, mechanically flexible electrodes are obtained. The silver nanowire electrodes are integrated into several electronic devices: transparent heaters, organic solar cells, and switchable privacy glass. The concerns about the suitability of silver nanowire electrodes for use in commercial electronic devices are discussed. High surface roughness, one of the major concerns, is addressed by introducing a new method of embedding silver nanowires in a soft polymer. The instability of silver nanowire electrodes under current flow is also demonstrated for the first time. It is shown that silver nanowire electrodes fail under current flow after ass little as 2 days. This failure is caused by Joule heating which causes the nanowires to break up and thus create an electrical discontinuity in the nanowire film. Suggestions for improving the longevity of the electrodes are given.

Thesis (M.S.)--Oregon State University, 2006. / Printout. Includes bibliographical references (leaves 54-56). Also available on the World Wide Web.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第13781号 / 工博第2885号 / 新制||工||1426(附属図書館) / 25997 / UT51-2008-C697 / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 井手 亜里, 教授 木村 健二, 教授 河合 潤 / 学位規則第4条第1項該当

Cette thèse se focalise sur l’étude du procédé de désalliage de couches minces d’alliages métalliques Au- Cu et Ag-Al déposés par pulvérisation cathodique magnétron. Une très large gamme de morphologie et de composition est obtenue grâce à ce procédé de dépôt. L’influence des paramètres de dépôt et des paramètres de désalliage sur la morphologie finale des couches minces nanoporeuses d’or et d’argent est étudiée. La possibilité de créer une structure lamellaire nanoporeuses d’or par la gravure chimique dans l’acide nitrique d’un empilement de couches d’or et de cuivre est également démontrée. Nous montrons aussi qu’il est possible de réaliser des réseaux bien organisés de nanofils d’or nanoporeux de plusieurs centimètres de long en combinant des dépôts sur des surfaces « template » et un désalliage par électrochimie. L’évaluation des couches minces d’or nanoporeux pour application comme capteur à effet SERS de petites molécules a été réalisée. On obtient des limites de détection de l’ordre du picomolaire (entre 10-12 et 10- 14 mol.L-1) pour la bipyridine comme molécule sonde sur des structures lamellaires d’or nanoporeux. Enfin, nous avons développé un nouveau procédé de désalliage basé sur l’utilisation de vapeur d’acide permettant la création de membranes nanomaillées d’or pour des applications comme électrodes flexibles transparentes. On atteint des performances de 44 Ω/□ avec une transmittance de 79 % avec une variation de résistance de moins de 8 % après 10 000 cycles de courbure sous une déformation de 1 %. / The main objective of this thesis is to study the dealloying process of metal alloy thin films and nanowires deposited by magnetron sputtering which is a versatile process allowing growing alloys with a large panel of morphologies. We explore the influence of the deposition parameters on the morphology of the alloy films and nanowires and how in turn they impact the dealloying process. We further demonstrate that it is possible to create nanoporous lamellar films by selective etching in nitric acid of multilayered thin films consisting of stacks of gold/copper nanolayers. Furthermore, we show how by combining the deposition of gold-copper alloy by magnetron sputtering on “template” substrate and electrochemical dealloying one can create planar arrays of nanoporous gold nanowires with a tunable morphology. In term of application, the various nanoporous structures developed so far in this work are then used for the development of SERS-based sensors for the detection of small molecules. We obtain a detection limit at picomolar level (between 10-12 and 10-14 mol.L-1) with bipyridine as probe molecule using the nanoporous lamellar films. Moreover, we demonstrate a novel process based on applying dealloying using acidic vapors allowing fabricating highly flexible and transparent gold nanomesh electrodes suitable for flexible electronics. The obtained gold nanomesh electrodes may exhibit a resistivity as low as 44 Ω/□ and a transmittance of 79 % with a slight increase in resistance of less than 8 % after 10 000 bending cycles at 1 %.

Philosophiae Doctor - PhD / This project is aimed at fabricating a smart material. Zinc oxide and vanadium dioxide have received a great deal of attention in recent years because they are used in various applications. ZnO semiconductor in particular has a potential application in optoelectronic devices such as light emitting diodes (LED), sensors and in photovoltaic cell industry as a transparent electrode. VO2 also has found application in smart windows, solar technology and infrared smart devices. Hence the need to synthesis or fabricate a new smart material using VO2 and an active ZnO based nano-composites family in which ZnO matrix will be hosting thermally active VO2 nano-crystals is the basis of this study. Since VO2 behave as an MIT Mott’s type oxides and exhibits a thermally driven semiconductor-metal phase transition at about 68 oC and as a direct result ZnO:VO2 nano-composites would exhibit a reversible and modulated optical transmission in the infra-red (IR) while maintaining a constant optical transmission in the UV-Vis range. The synthesis is possible by pulsed laser deposition and ion implantation. Synthesis by pulsed laser deposition will involve thin films multilayer fabrication. ZnO buffer layer thin film will be deposited on the glass and ZnO single crystals and subsequent layer of VO2 and ZnO will be deposited on the substrate. X-ray diffraction (XRD) reveals that the series of ZnO thin films deposited by Pulsed Laser Deposition (PLD) on glass substrates has the hexagonal wurtzite structure with a c-axis preferential orientation. In addition the XRD results registered for VO2 samples indicate that all thin films exhibits a monoclinic VO2 (M) phase. UV-Vis NIR measurements of multilayered structures showed the optical tunability at the near-IR region and an enhanced transparency (>30 %) at the visible range.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第16865号 / 工博第3586号 / 新制||工||1542(附属図書館) / 29540 / 京都大学大学院工学研究科材料化学専攻 / (主査)教授 平尾 一之, 教授 三浦 清貴, 教授 田中 勝久 / 学位規則第4条第1項該当

Thesis advisor: Michael J. Naughton / In this dissertation, I first discuss many different kinds of transparent conductors in Chapter one. In Chapter two, I focus on transparent conductors based on crackle temples. I and my colleagues developed three (one sputter-free and two fully all-solution) methods to fabricate metallic networks as transparent conductors. The first kind of all-solution process is based on crackle photolithography and the resulting silver networks outperform all reported experimental values, including having sheet resistance more than an order of magnitude lower than ITO, yet with comparable transmittance. The second kind of all-solution proceed transparent conductor is obtained by integrating crackle photolithography-based microwires with nanowires and electroplate welding. This combination results in scalable film structures that are flexible, indium-free, vacuum-free, lithographic-facility-free, metallic-mask-free, with small domain size, high optical transmittance, and low sheet resistance (one order of magnitude smaller than conventional nanowire-based transparent conductors). / Thesis (PhD) — Boston College, 2019. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Physics.

Dans notre quotidien, le smartphone est devenu un outil indispensable pour effectuer nos tâches courantes. Accéder à des services en ligne depuis son téléphone mobile est devenu une action commune. Afin de s'authentifier à ces services parfois sensibles, la seule protection est généralement l'usage d'un mot de passe. Ces mots de passe pour être robustes doivent être de plus en plus longs. Ceci représente, sur les téléphones mobiles, une contrainte plus forte que pour les ordinateurs de bureau puisque les claviers tactiles disposent de moins de touches. D'autres méthodes d'authentification ont vu le jour sur téléphones mobiles comme la reconnaissance faciale sur les appareils android ou bien l'empreinte digitale qui gagne le marché des smartphones et même le domaine bancaire avec Apple Pay.Afin de simplifier l'authentification, la biométrie prend une part de plus en plus importante dans l'usage des téléphones mobiles. Au delà des capteurs dédiés à l'acquisition de données biométriques, il est aussi possible d'utiliser l'environnement du téléphone mobile pour authentifier les utilisateurs. Si les méthodes d'authentification tendent à se transformer pour devenir de plus en plus transparentes, cela amène deux questions :Comment utiliser ces nouvelles techniques d'authentification dans les processus actuels d'authentification ?Quels impacts ces nouvelles méthodes peuvent avoir sur la vie privée des utilisateurs ?L'objectif de cette thèse est de proposer des méthodes d'authentification transparentes qui soient respectueuses de la vie privée des utilisateurs tout en permettant leur intégration dans les systèmes actuels d'authentification.Dans le manuscrit de thèse, nous abordons ces deux questions en analysant tout d'abord les travaux existants sur la collecte des données permettant l'authentification sur téléphone mobile. Puis, une fois les données collectées, nous verrons les processus permettant la mise en place d'une authentification respectueuse de la vie privée. Enfin, nous évaluons concrètement ces méthodes d'authentification par la réalisation de prototypes à l'échelle industrielle. / In our daily life, the smartphone became an unavoidable tool to perform our common tasks.Accessing to online services from its mobile phone is an usual action.In order to authenticate to those services, that might be sensitive, the one and only protection is usually a password. Those passwords must be longer and longer to stay robust.This is a bigger constraint on mobile phones than on desktop computers.Other authentication solutions are dedicated to smartphones, like facial recognition on android and now Apple smartphones or the fingerprint that conquier new phones.To ease the authentication process, biometrics is more and more often used on mobile phones. In addition to the dedicated biometric sensors, it is also possible to use the phone environement to authenticate users.However, if authentication methods are becoming more and more transparent, it brings two questions:How to integrate those new methods within the actual authentication framework ?What is the impact of those new methods on users' privacy ?The main goal of the phD is to offers privacy compliant transparent authentication methods while integrating them in current authentication systems.In this document, we evaluates those two questions by first analyzing existing works on the data collection for transparent authentication on mobile phones. Then, once the data are collected, we will see wich process can enable the privacy protection. To conclude, we will evaluates concretly those solutions by building industrial prototypes.

As our understanding of ceramic processing methods for the purpose of fabricating polycrystalline optical materials has increased over the past few decades, the race is on to bring ceramic technology to markets where single crystalline materials have traditionally been used. One such market is scintillators. This Master’s thesis focuses specifically on a class of materials attractive for use as gamma-ray scintillators. These barium based halides can potentially be utilized in applications ranging from ionizing radiation detection in the field to high-energy physics experimentation. Barium bromide iodide and barium chloride single crystals have already showed high light yield, fast scintillation decay, and high energy resolution, all desirable properties for a scintillator. This work attempts to show the likelihood of moving towards polycrystalline scintillators to take advantage of the lower processing temperature, higher manufacturing output, and overall reduced cost. The experiments begin with identifying appropriate sintering conditions for hot pressed ceramics of BaBrI and BaCl2. Possible sources of optical loss in the first phase of hot pressed samples are investigated using a wide range of characterization tools. Preliminary luminescence and scintillation measurements are reported for a translucent sample of BaBrI. Recommendations are made to move toward highly transparent ceramics with scintillation properties approaching those measured in single crystal samples

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