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Ainsworth, Catherine. "Structure-property relationships in conductive nanowire networks." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/structureproperty-relationships-in-conductive-nanowire-networks(0a8901bc-54be-4882-b49d-3e5515fac0df).html.
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This thesis studies networks of silver nanowires as a transparent conducting electrode material and presents an investigation into the relationship between electrical and optical properties in the networks. The work focusses on two main aspects: the production of networks via different deposition methods; and the development of a predictive model based on theory that relates the sheet resistance to the optical transmittance. The deposition methods of drop-casting, bar-coating and spray-coating are used to create networks and the randomness of these networks is compared using image analysis in ImageJ, a public domain image processing program, and Wolfram Mathematica, a computer algebra program. It is determined that spray-coating results in the most random networks, therefore all subsequent experiments are carried out using this as the deposition method. Annealing condition tests are carried out on the nanowire networks to determine the optimal annealing conditions required to burn off poly(vinyl pyrrolidone) (PVP) remaining from the nanowire synthesis process and sinter the nanowire junctions to improve network conductivity. The sheet resistances and optical transmittances of the networks are measured and compared to networks created by other research groups. It is found that the networks created in this study exhibited similar optical and electrical properties to those in the literature, obtaining Rs = 100 Ω/sq for T = 81%.The developed model is based on theory and relates the sheet resistance to the optical transmittance using only the length and width of the nanowires used in the network and the mean network coverage as variables. The model can be used to predict the properties of a network if these factors are known. The model is compared with experimental data both from this study and from the literature, along with simulated data from the literature that was obtained by Monte Carlo methods. It is shown that there is an excellent fit between the model and all data that it is compared with. It is demonstrated that < 1% of the network coverage is greater than 2 for typical nanowire networks, proving that the networks are two-dimensional and therefore do not require a bulk regime to describe the relationship, as has been suggested in prior work.
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Zhu, Zhaozhao, and Zhaozhao Zhu. "Emerging Materials for Transparent Conductive Electrodes and Their Applications in Photovoltaics." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/623062.
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Clean and affordable energy, especially solar energy, is becoming more and more important as our annual total energy consumption keeps rising. However, to make solar energy more affordable and accessible, the cost for fabrication, transportation and assembly of all components need to be reduced. As a crucial component for solar cells, transparent conductive electrode (TCE) can determine the cost and performance. A light weight, easy-to-fabricate and cost-effective new generation TCE is thus needed. While indium-doped tin oxide (ITO) has been the most widely used material for commercial applications as TCEs, its cost has gone up due to the limited global supply of indium. This is not only due to the scarcity of the element itself, but also the massive production of various opto-electronic devices such as TVs, smartphones and tablets. In order to reduce the cost for fabricating large area solar cells, substitute materials for ITO should be developed. These materials should have similar optical transmittance in the visible wavelength range, as well as similar electrical conductivity (sheet resistance) to ITO. This work starts with synthesizing ITO-replacing nano-materials, such as copper nanowires (CuNWs), derivative zinc oxide (ZnO) thin films, reduced graphene oxide (rGO) and so on. Further, we applied various deposition techniques, including spin-coating, spray-coating, Mayer-rod coating, filtration and transferring, to coat transparent substrates with these materials in order to fabricate TCEs. We characterize these materials and analyze their electrical/optical properties as TCEs. Additionally, these fabricated single-material-based TCEs were tested in various lab conditions, and their shortcomings (instability, rigidity, etc.) were highlighted. In order to address these issues, we hybridized the different materials to combine their strengths and compared the properties to single-material based TCEs. The multiple hybridized TCEs have comparable optical/electrical metrics to ITO. The doped-ZnO TCEs exhibit high optical transmittance over 90% in the visible range and low sheet resistance under 200Ω/sq. For CuNW-based composite electrodes, ~ 85% optical transmittance and ~ 25Ω/sq were observed. Meanwhile, the hybridization of materials adds additional features such as flexibility or resistance to corrosion. Finally, as a proof of concept, the CuNW-based composite TCEs were tested in dye-sensitized solar cells (DSSCs), showing similar performance to ITO based samples.
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Gaone, Joseph Michael II. "A Mathematical Model of a Microbial Fuel Cell." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1376400246.
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Selzer, Franz, Nelli Weiß, David Kneppe, Ludwig Bormann, Christoph Sachse, Nikolai Gaponik, Alexander Eychmüller, Karl Leo, and Lars Müller-Meskamp. "A spray-coating process for highly conductive silver nanowire networks as the transparent top-electrode for small molecule organic photovoltaics." Royal Society of Chemistry, 2015. https://tud.qucosa.de/id/qucosa%3A36329.
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We present a novel top-electrode spray-coating process for the solution-based deposition of silver nanowires (AgNWs) onto vacuum-processed small molecule organic electronic solar cells. The process is compatible with organic light emitting diodes (OLEDs) and organic light emitting thin film transistors (OLETs) as well. By modifying commonly synthesized AgNWs with a perfluorinated methacrylate, we are able to disperse these wires in a highly fluorinated solvent. This solvent does not dissolve most organic materials, enabling a top spray-coating process for sensitive small molecule and polymer-based devices. The optimized preparation of the novel AgNW dispersion and spray-coating at only 30 °C leads to high performance electrodes directly after the deposition, exhibiting a sheet resistance of 10.0 Ω □−1 at 87.4% transparency (80.0% with substrate). By spraying our novel AgNW dispersion in air onto the vacuum-processed organic p-i-n type solar cells, we obtain working solar cells with a power conversion efficiency (PCE) of 1.23%, compared to the air exposed reference devices employing thermally evaporated thin metal layers as the top-electrode.
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Lagrange, Mélanie. "Physical analysis of percolating silver nanowire networks used as transparent electrodes for flexible applications." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAI075/document.
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Les électrodes transparentes (ET) sont présentes dans de nombreux dispositifs optoélectroniques. Par exemple, on peut les trouver au sein de cellules solaires, d'écrans tactiles, d'OLEDs ou encore de films chauffants transparents. Les propriétés physiques de ces électrodes influencent l'efficacité de ces dispositifs. Les ET sont fabriquées à partir de matériaux transparents conducteurs (TCM) dont le développement a débuté dans les années 1950 notamment avec les oxydes métalliques. Parmi ces oxydes transparents conducteurs (TCO), l'oxyde d'étain-indium (ITO) est celui le plus communément utilisé dans les cellules solaires et les écrans de télévision ou de smartphones. Cependant, de nouvelles exigences telles qu'une réduction des coûts, la flexibilité et la fabrication à faible température et/ou faible coût, ont orienté les recherches vers de nouveaux TCM, notamment à base de nanostructures. Parmi ces matériaux émergents, les réseaux de nanofils métalliques, en particulier de nanofils d'argent, présentent déjà des propriétés optiques et électriques approchant celles de l'ITO, c'est-à-dire une conductivité électrique et une transparence élevées. Ces deux propriétés sont cependant intrinsèquement liées à la densité de nanofils constituant le réseau, et lorsque la conductivité augmente, la transparence diminue. Des traitements post-dépôt existent et permettent d'augmenter la conductivité électrique des ET sans changer la densité du réseau. Plusieurs de ces méthodes d'optimisation ont été étudiées pendant ce travail de thèse, en particulier le recuit thermique, analysé minutieusement afin de comprendre les différents mécanismes de réduction de la conductivité électrique induits par la température. L'examen des effets thermiques a soulevé la question de l'instabilité des nanofils en température, qui est aussi abordée et discutée dans ce document. Le paramètre clé de la densité de nanofils optimale menant au meilleur compromis entre transparence et conductivité a été recherché pour des nanofils de différentes dimensions. La taille des nanofils a en effet un fort impact sur les propriétés du réseau. Ainsi, les propriétés électriques, dans le cadre de la théorie de la percolation, les propriétés optiques comme la transmittance et le facteur de haze, et même l'instabilité thermique ont été reliées aux dimensions des nanofils ainsi qu'à la densité du réseau en utilisant des modèles physiques simples. En ce qui concerne les applications de ces ET émergentes, des études ont été menées sur l'application des réseaux de nanofils d'argent comme film chauffant transparent, et les résultats sont rapportés à la fin de ce document. Les limitations soulevées par cette application, comme les limites de stabilités électrique et thermique ont aussi été abordées. Pour finir, des études préliminaires menées sur de nouvelles applications comme des antennes transparentes ou le blindage électromagnétique transparent utilisant les nanofils d'argent sont présentéesTransparent electrodes (TE) are used in a variety of optoelectrical devices. Among them, solar cells, flat panel displays, touch screens, OLEDs and transparent heaters can be cited. The physical properties of the TE influence the efficiency of the device as a whole. Such electrodes are fabricated from transparent conducting materials (TCM) that have been undergoing development since the 1950s, initially from metallic oxides. Among these transparent conducting oxides (TCO), indium tin oxide (ITO) is the most commonly used in solar cells, and television or smartphone screens. However requirements such as cost reduction, flexibility and low cost/temperature fabrication techniques have oriented the researches toward emerging TCM, mostly using nanostructures. Among them, metallic nanowire networks, and in particular silver nanowires (AgNW), already present optical and electrical properties approaching those of ITO, i.e. a high electrical conductivity and a high transparency. These two properties are intrinsically linked to the network density, therefore a tradeoff has to be considered knowing that when conductivity increases, transparency decreases. Some post-deposition treatments do exist, allowing an increase of the TE electrical conductivity without changing the network density. Several of these optimization methods have been thoroughly studied during this thesis work, especially thermal annealing. This method have been investigated in details to understand the different thermally-induced mechanisms of conductivity improvement. In addition, the investigation of thermal effects raised the question of thermal instability of the nanowires, which is also addressed and discussed in this document. The key issue of density optimization, allowing the best tradeoff between transparency and conductivity, has been investigated for nanowires with different dimensions. Nanowire size has a strong impact on the network properties. Thus, electrical properties, within the framework of percolation theory, optical properties such as transmittance or haziness, and even thermal instability have been linked to the nanowires' dimensions and the network density by using simple physical models. Regarding the application of these emerging TE, studies were conducted on the application of AgNWs as transparent heaters, and the results are reported at the end of the document. Limitations arising from this application, like thermal and electrical stabilities, have also been addressed. To finish, preliminary studies conducted on new applications such as transparent antennas and transparent electromagnetic shielding using AgNW are presented
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Bocharova, Vera. "Electrically Conductive Low Dimensional Nanostructures: Synthesis, Characterisation and Application." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1231161926227-23379.
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Miniaturization has become a driving force in different areas of technology including microelectronics, sensoric- and bio-technologies and in fundamental science. Because of the well-known limitations of conventional lithographic methods, newly emerging bottom-up approach, utilizing self-assembly of various nanoobjects including single polymer molecules and carbon nanotubes constitutes a very promising alternative for fabrication of ultimately small devices. Carbon nanotubes are attractive materials for nanotechnology and hold much promise to revolutionize fundamental science in a investigation of phenomena, associated with the nanometer–sized objects.It was found in this work that grafted chains of poly(2-vinylpyridine) form a shell covering the carbon nanotubes that makes them dispersible in organic solvents and in acidic water (CNTs-g-P2VP).The positively charged poly(2-vinylpyridine) shell is responsible for the selective deposition of carbon nanotubes onto oppositely charged surfaces. It was established that the deposition CNTs-g-P2VP from aqueous dispersions at low pH is an effective method to prepare ultra-thin films with a tunable density of carbon nanotubes.It was shown that poly(2-vinylpyridine) grafted to carbon nanotubes is a universal support for the immobilization of various nanoclusters at the carbon nanotube's surface. Prussian Blue nanoparticles were selectively attached to the surface of CNTs-g-P2VP.Conducting polymer nanowires are another very promising kind of nanomaterials that could be also suitable for applications in nanodevices and nanosensors. In this work was developed a simple method to control the conformation and orientation of single adsorbed polyelectrolyte molecules by co-deposition with octylamine. A simple chemical route to conductive polypyrrole nanowires by the grafting of polypyrrole from molecules of polystyrensulfonic acid was developed. The dc conductivity of individual polypyrrole nanowires approaches the conductivity of polypyrole in bulk.The conductivity can be described using variable-range hopping model.
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Bocharova, Vera. "Electrically Conductive Low Dimensional Nanostructures: Synthesis, Characterisation and Application." Doctoral thesis, Technische Universität Dresden, 2008. https://tud.qucosa.de/id/qucosa%3A23607.
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Miniaturization has become a driving force in different areas of technology including microelectronics, sensoric- and bio-technologies and in fundamental science. Because of the well-known limitations of conventional lithographic methods, newly emerging bottom-up approach, utilizing self-assembly of various nanoobjects including single polymer molecules and carbon nanotubes constitutes a very promising alternative for fabrication of ultimately small devices. Carbon nanotubes are attractive materials for nanotechnology and hold much promise to revolutionize fundamental science in a investigation of phenomena, associated with the nanometer–sized objects.It was found in this work that grafted chains of poly(2-vinylpyridine) form a shell covering the carbon nanotubes that makes them dispersible in organic solvents and in acidic water (CNTs-g-P2VP).The positively charged poly(2-vinylpyridine) shell is responsible for the selective deposition of carbon nanotubes onto oppositely charged surfaces. It was established that the deposition CNTs-g-P2VP from aqueous dispersions at low pH is an effective method to prepare ultra-thin films with a tunable density of carbon nanotubes.It was shown that poly(2-vinylpyridine) grafted to carbon nanotubes is a universal support for the immobilization of various nanoclusters at the carbon nanotube's surface. Prussian Blue nanoparticles were selectively attached to the surface of CNTs-g-P2VP.Conducting polymer nanowires are another very promising kind of nanomaterials that could be also suitable for applications in nanodevices and nanosensors. In this work was developed a simple method to control the conformation and orientation of single adsorbed polyelectrolyte molecules by co-deposition with octylamine. A simple chemical route to conductive polypyrrole nanowires by the grafting of polypyrrole from molecules of polystyrensulfonic acid was developed. The dc conductivity of individual polypyrrole nanowires approaches the conductivity of polypyrole in bulk.The conductivity can be described using variable-range hopping model.
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Demidenok, Konstantin. "Polyelectrolyte nanostructures formed in the moving contact line: fabrication, characterization and application." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-27327.
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Having conducted the research described in this thesis I found that there exists a possibility to produce polyelectrolyte nanostructures on hydrophobic surfaces by application of the moving contact line approach. It was demonstrated that the morphology of nanostructures displays a range of structure variations from root-like to a single wire structure with a high anisotropy and aspect ratio (providing diameters of several nanometers and the length limited by the sample surface dimensions). Such nanostructures can be produced exactly on the spot of interest or can be transferred from the surface where they were produced to any other surfaces by the contact printing technique.
A model describing the polymer deposition during the moving contact line processes on hydrophobic surfaces has been proposed. The application of this model provides the ground for an explanation of all the obtained experimental data.
Utilizing moving contact line approach aligned one-dimensional polycation structures were fabricated and these structures were used as templates for assembling amphiphile molecules.
Quasiperiodic aligned and oriented nanostructures of polyelectrolyte molecules formed in moving droplets were utilized for fabrication of electrically conductive one-dimensional nanowires.
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Demidenok, Konstantin. "Polyelectrolyte nanostructures formed in the moving contact line: fabrication, characterization and application: Polyelectrolyte nanostructures formed in the moving contact line: fabrication, characterization and application." Doctoral thesis, Technische Universität Dresden, 2009. https://tud.qucosa.de/id/qucosa%3A25246.
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Having conducted the research described in this thesis I found that there exists a possibility to produce polyelectrolyte nanostructures on hydrophobic surfaces by application of the moving contact line approach. It was demonstrated that the morphology of nanostructures displays a range of structure variations from root-like to a single wire structure with a high anisotropy and aspect ratio (providing diameters of several nanometers and the length limited by the sample surface dimensions). Such nanostructures can be produced exactly on the spot of interest or can be transferred from the surface where they were produced to any other surfaces by the contact printing technique.
A model describing the polymer deposition during the moving contact line processes on hydrophobic surfaces has been proposed. The application of this model provides the ground for an explanation of all the obtained experimental data.
Utilizing moving contact line approach aligned one-dimensional polycation structures were fabricated and these structures were used as templates for assembling amphiphile molecules.
Quasiperiodic aligned and oriented nanostructures of polyelectrolyte molecules formed in moving droplets were utilized for fabrication of electrically conductive one-dimensional nanowires.
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Yang, Chaobin. "All-Solution-Processed Transparent Conductive Electrodes with Crackle Templates:." Thesis, Boston College, 2019. http://hdl.handle.net/2345/bc-ir:108648.
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Thesis advisor: Michael J. NaughtonIn 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
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Al-Ghamdi, Said. "Synthesis and characterization of conductive nanowires using DNA as a template." Thesis, University of Newcastle Upon Tyne, 2011. http://hdl.handle.net/10443/1137.
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The preparation and characterisation of conductive nanowires and nanoropes on DNA templates is the focus of this work. This work is motivated by the search for alternative bottom-up approaches to nanoscale electronics. The structures and composition of prepared nanowires were determined by Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-Vis) absorption spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron (XPS) spectroscopy. The morphology and physical properties were examined by atomic force microscopy (AFM), electrostatic force microscopy (EFM), conductive atomic force microscopy (C-AFM) and two-terminal current-voltage (I-V) measurements using microelectrodes fabricated by photolithography techniques. Polypyrrole (PPy) nanoropes were formed by chemical polymerization of pyrrole on a DNA template. The diameter of these 'nanoropes' was between 5–30 nm. At room temperature, the conductivity of a PPy-DNA nanorope is confirmed by C-AFM, while the temperature dependence of the conductivity was observed to follow a simple Arrhenius behaviour with a characteristic temperature of T0 = 4000K. Silver (Ag) nanoparticle chains were grown along λ-DNA templates using Tollens' reagent under mild conditions (50 ºC, 10 min). UV–Vis spectroscopy of these nanowires exhibited an absorption band at 400-440 nm due to the Ag plasmon. The DNA-templated Ag wires were found to be coated with an oxidized shell. Unlike DNA-templated polypyrrole, these nanowires were often rough. Using metal-binding functionality (alkynyl) introduced into DNA-templated polymer nanowires by chemical modification of the monomer, the morphology of the wire was improved on this hybrid template. Finally, DNA was used as a template for the growth of cuprous oxide (Cu2O) nanowires using Benedict's reagent and ascorbic acid as reducing agent at room temperature. AFM showed that these nanowires are uniform and continuous (diameters of 5-30 nm and lengths of 5-16 μm). C-AFM revealed that the average resistance of Cu2O–DNA nanowires was in the range from 0.13-0.18 MΩ depending on deflection setpoints, which suggests the material is doped. In summary, a range of inorganic and organic materials can be templated on DNA in the form of nanowires and various methods for measuring the conductivity of these nanowires have been established.
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Tachibana, Masamitsu. "Theoretical studies on vibronic interactions and conducting nanowires." 京都大学 (Kyoto University), 2003. http://hdl.handle.net/2433/148836.
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Hedley, Joseph Henry. "DNA-based conducting polymer nanowires for biosensor applications." Thesis, University of Newcastle upon Tyne, 2014. http://hdl.handle.net/10443/2566.
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Novel DNA-based conductive polymer nanowires formed from thienyl-pyrrole derivatives have been synthesized and characterised by high-resolution ES-MS, ¹H and ¹³C NMR spectroscopy. Bulk DNA-templating of these materials is demonstrated by FTIR, while relative control over nanowire dimensions and deposition is shown by AFM. The electronic properties of these materials were investigated by Scanned Conductance Microscopy (SCM) and two-point I-V measurements. The resistance of the DNA/polymer nanowires, determined from variable temperature I-V measurements, was found to be in the range of 10¹²-10¹⁴Ω. Nanowire conductivity values were calculated to be in the range of 1.9x10-⁷-3.75x10-⁴S cm-¹ at 303K. FTIR data demonstrates the availability of the alkyne group in bulk DNAtemplated materials for subsequent nanowire functionalisation using ‘click’ chemistry. Efforts to couple 3-azido propanol and ssDNA probe DNA is also presented.
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Elias, Watheq Zako. "Calculation of the electrical conduction of molecules and nanowires." Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/60045/.
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As electronics become more and more miniaturised, there is much interest in increasing knowledge about the electronic and transport properties of nano-systems. In particular, there has been some focus on understanding the physics of nanowires with prescribed properties. Two different groups of systems have been considered that of 1D organic molecular nanowires and 2D interconnects based on graphene. In order to develop a deeper insight of the factors that determine the electronic structure and consequently the electrical transport properties, it is desirable to carry out computer simulation studies of these systems. The work reported in this thesis has focused on studying the porphyrin and DNA molecules as well as investigating the consequences of engineered 2D graphene interconnect. The latter class of systems has included graphene nanoribbons (GNRs), graphene sheets with grain boundaries (GGBs) and graphene nanomeshes (GNMs). The methodology was to use self-consistent extended Hückel theory (SC-EHT) and density functional theory (DFT) in combination with non-equilibrium Green functions (NEGFs) formalism to investigate the electronic and transport properties of these systems. The SC-EHT calculations were performed using an in-house developed C++ code named EHTransport. While the SIESTA package was employed for the DFT. It was found that the SC-EHT approach produced comparable results with that obtained by DFT. This supports the idea that the semi-empirical methods can be as valid as ab-initio approaches. The findings demonstrated that porphyrin, DNA, and graphene based systems are very promising candidates to incorporate in future electronics.
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Hoeng, Fanny. "Potential of nanocellulose for conductive ink preparation." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI078.
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Ce projet vise à développer de nouvelles encres à base de nanofils d’argent et de nanocellulose pour des applications conductrices et transparentes. Les nanocelluloses, nanoparticules issues de la cellulose, sont de deux types : les nanocristaux de cellulose (NCC) et les nanofibrilles de cellulose (NFC) et possèdent des propriétés bien spécifiques. Ce travail a consisté d’une part (i) à utiliser la forme tubulaire et rigide des NCC pour produire des nanotubes d’argents par synthèse chimique, avant leur formulation en encre et d’autre part (ii) à utiliser les propriétés d’enchevêtrement des NFC flexibles pour stabiliser des nanofils d’argent commerciaux, habituellement instables en suspension. Les divers résultats de ce projet ont permis d’aboutir à la formulation brevetée et à la commercialisation d’une encre conductrice à base d’une faible quantité d’argent et de NCC et de deux encres conductrices et transparentes à base de NFC et de nanofils d’argent. Les interactions physico-chimiques et la stabilité colloïdale de ces suspensions hybrides ont été étudiée de manière fondamentale, tout en développant des formulations adaptées à divers procédés d’impression, que ce soit à échelle laboratoire mais aussi industrielleThis project aims at developing new conductive inks based on nanocellulose and silver nanowires for transparent and conductive applications. Nanocellulose are nanoparticles extracted from the cellulose and two kinds currently exist: the cellulose nanocrystals (CNC) and the cellulose nanofibrils (CNF). This project have evaluated on one hand the ability of using tubular rigid CNC as template for producing silver nanorods, prior their formulation into conductive inks. On the other hand, the ability of using flexible and entangled CNF to stabilize commercial silver nanowires, usually unstable in suspension, was investigated. The results of this project lead to the patented formulation and commercialization of one low silver content conductive ink based on silver and CNC and two conductive transparent ink based on CNF and silver nanowires. Physico-chemical interactions and colloidal stability of such hybrid suspension have been scientifically studied meanwhile printing process adapted formulation have been successfully designed and tested at laboratory scale but also industrial scale
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Mankowski, Trent, and Trent Mankowski. "Integrating Copper Nanowire Electrodes for Low Temperature Perovskite Photovoltaic Cells." Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/624135.
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Recent advances in third generation photovoltaics, particularly the rapid increase in perovskite power conversion efficiencies, may provide a cheap alternative to silicon solar cells in the near future. A key component to these devices is the transparent front electrode, and in the case of Dye Sensitized Solar Cells, it is the most expensive part. A lightweight, cost-effective, robust, and easy-to-fabricate new generation TCE is required to enable competition with silicon.
Indium Tin Oxide, commonly used in touchscreen devices, Organic Light Emitting Diodes (OLEDs), and thin film photovoltaics, is widely used and commonly referred to as the industry standard. As the global supply of indium decreases and the demand for this TCE increases, a similar alternative TCE is required to accompany the next generation solar cells that promise energy with lighter and significantly cheaper modules. This alternative TCE needs to provide similar sheet resistance and optical transmittance to ITO, while also being mechanically and chemically robust.
The work in this thesis begins with an exploration of several synthesized ITO replacement materials, such as copper nanowires, conductive polymer PEDOT:PSS, zinc oxide thin films, reduced graphene oxide and combinations of the above. A guiding philosophy to this work was prioritizing cheap, easy deposition methods and overall scalability. Shortcomings of these TCEs were investigated and different materials were hybridized to take advantage of each layers strengths for development of an ideal ITO replacement. For CuNW-based composite electrodes, ~85% optical transmittance and ~25 Ω/sq were observed and characterized to understand the underlying mechanisms for optimization.
The second half of this work is an examination of many different perovskite synthesis methods first to achieve highest performance, and then to integrate compatible methods with our CuNW TCEs. Several literature methods investigated were irreproducible, and those that were successful posed difficulties integrating with CuNW-based TCEs. Those shortcomings are discussed, and how future work might skirt the issues revealed here to produce a very low cost, high performance perovskite solar cell.
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Tabookht, Zahra. "Theoretical study of magnetic and conducting properties of transition metal nanowires." Doctoral thesis, Universitat Rovira i Virgili, 2011. http://hdl.handle.net/10803/52798.
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En la presente tesis doctoral se ha realizado un estudio computacional de las propiedades electrónicas de sistemas basados en cadenas metálicas monodimensionales de la familia de los llamados nanowires, concretamente su magnetismo y conductividad. Estas cadenas lineales se sustentan gracias a los ligandos orgánicos que se organizan a su alrededor, cuyo número de sitios de unión determina la nuclearidad de la cadena. Para estas moléculas, llamadas cadenas metálicas extendidas, se han calculado los parámetros de acoplamiento magnético con el método CASPT2. El uso del Hamiltoniano de Heisenberg estándar para los sistemas M3(dpa)4Cl2 cuando hay dos electrones no desapareados en cada centro, ha sido examinado mediante el cálculo del valor de λ mediante cálculos DFT. Las diferentes conductividades eléctricas observadas en las cadenas MMX [Ni2(dta)4I]∞ y [Pt2(dta)4I]∞ (dta = CH3CS2) y sus estados de ordenación de carga han sido analizados con parámetros de estructura electrónica extraídos a partir de cálculos DFT periódicos y de correlación combinados con la teoría del Hamiltoniano efectivo.In the present thesis, magnetic and conducting properties of systems, one-dimensional chains of the family of so-called nanowires, have been studied computationally. These linear chains are supported by organic ligands surrounding the metal backbone where the number of binding sites determines the nuclearity of the chain. For these molecules, also called extended metal atom chains, magnetic coupling parameters have been calculated with the CASPT2 method. The use of standard Heisenberg Hamiltonian for systems M3(dpa)4Cl2 when two unpaired electrons are localized on each magnetic center has been examined by calculating the value of λ from DFT calculations. The different electrical conductivities observed in MMX chains [Ni2(dta)4I]∞ and [Pt2(dta)4I]∞ (dta = CH3CS2) and the charge ordering state have been analyzed with DFT periodic calculations and also through the comparison of extracted electronic structure parameters from ab initio calculations combined with the effective Hamiltonian theory.
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Zhu, Zhaozhao, Trent Mankowski, Ali Sehpar Shikoh, Farid Touati, Mohieddine A. Benammar, Masud Mansuripur, and Charles M. Falco. "Ultra-high aspect ratio copper nanowires as transparent conductive electrodes for dye sensitized solar cells." SPIE-INT SOC OPTICAL ENGINEERING, 2016. http://hdl.handle.net/10150/622550.
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We report the synthesis of ultra-high aspect ratio copper nanowires (CuNW) and fabrication of CuNW-based transparent conductive electrodes (TCE) with high optical transmittance (> 80%) and excellent sheet resistance (R-s < 30 Omega/sq). These CuNW TCEs are subsequently hybridized with aluminum-doped zinc oxide (AZO) thin-film coatings, or platinum thinfilm coatings, or nickel thin-film coatings. Our hybrid transparent electrodes can replace indium tin oxide (ITO) films in dye-sensitized solar cells (DSSCs) as either anodes or cathodes. We highlight the challenges of integrating bare CuNWs into DSSCs, and demonstrate that hybridization renders the solar cell integrations feasible. The CuNW/AZO-based DSSCs have reasonably good open-circuit voltage (V-oc = 720 mV) and short-circuit current-density (J(sc) = 0.96 mA/cm(2)), which are comparable to what is obtained with an ITO-based DSSC fabricated with a similar process. Our CuNW-Ni based DSSCs exhibit a good open-circuit voltage (V-oc = 782 mV) and a decent short-circuit current (J(sc) = 3.96 mA/cm2), with roughly 1.5% optical-to-electrical conversion efficiency.
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Rodichkina, Sofia. "Electrical and thermal properties of silicon nanowire arrays." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI129.
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Les nanofils de silicium (SiNWs) attirent l’attention particulière en raison de leurs applications thermoélectriques prometteuses. La faible conductivité thermique et les propriétés électriques proches du Si massif en font un nanomatériau thermoélectrique idéal dans le concept de "verre à phonons - cristal à électrons". Théoriquement, les valeurs du facteur de mérite thermoélectrique (ZT) pour SiNW peuvent atteindre 3 à la température ambiante. ZT = 0,7 a été déjà obtenu expérimentalement pour des SiNW individuels, ce qui est proche de ZT pour les chalcogénures de bismuth (ZT = 0,8 -1,0) qui sont couramment utilisés. De point de vue pratique, il faut savoir fabriquer des réseaux de SiNWs à faible coût. Dans cette thèse, nous avons cherché: (i) à adapter des technologies existantes pour la fabrication des SiNWs fortement dopés, (ii) à développer des méthodes de caractérisation sans contact et non destructive des propriétés électriques et thermiques de réseaux de SiNWs, (iii) à fabriquer et caractériser des réseaux de SiNWs à haute conductivité électrique et faible conductivité thermique. Les réseaux des SiNW ayant la morphologie et le niveau de dopage nécessaires pour obtenir un ZT maximal ont été fabriquées par gravure chimique assistée par métaux de substrats de silicium. Une procédure de dopage post-fabrication a été développée en utilisant la diffusion thermique d’atomes de dopant à partir de solutions de dopage (via un dépôt spin-on). En particulier, les réseaux de nanofils de silicium ayant un diamètre typique de 100 nm, une longueur de 10 mm, une morphologie de type "cœur cristallin/ surface rugueuse" et un niveau de dopage de 10 20 cmSilicon nanowires (SiNWs) attract growing attention in view of their promising thermoelectric applications. Low thermal conductivity and bulk-like electrical properties make them a perfect candidate as a thermoelectric material in framework of the concept “phonon-glass/ electroncrystal”. Theoretically, the values of figure of merit (ZT) for SiNWs as high as three can be achieved at room temperature, and experimentally ZT = 0.7 were already observed for individual SiNWs, which is close to ZT for commonly used bismuth chalcogenides (ZT = 0.8-1.0). For practical application of SiNWs, the low-cost fabrication methods for SiNWs arrays with high ZT should be achieved. In this thesis we aimed: (i) to adapt available semiconductor technology for fabrication of highly-doped SiNWs arrays, (ii) to develop contactless methods for non-destructive characterization of electrical and thermal properties of the SiNWs arrays, (iii) to fabricate and characterize SiNWs arrays with high electrical and low thermal conductivities. The arrays of SiNWs with the morphology and doping level necessary for maximum ZT were fabricated using metal-assisted chemical etching of silicon wafers and post-fabrication doping procedure, which consisted of the thermal diffusion of dopant atoms from spin-on dopant solutions. In particular, the arrays of silicon nanowires with a typical diameter of 100 nm, length of 10 mm, bulk core/rough surface morphology and doping level of 1020 cm
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Hangarter, Carlos Maldonado. "Electrochemical synthesis of one-dimensional nanostructures for sensor and spintronic applications." Diss., [Riverside, Calif.] : University of California, Riverside, 2009. http://proquest.umi.com/pqdweb?index=0&did=1957308741&SrchMode=2&sid=1&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1269278715&clientId=48051.
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Thesis (Ph. D.)--University of California, Riverside, 2009.Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 12, 2010). Includes bibliographical references. Also issued in print.
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Bajpai, Vardhan. "SYNTHESES, CHARACTERIZATION AND APPLICATIONS OF MICRO-/NANO-STRUCTURED CONDUCTING POLYMERS AND CARBON NANOTUBES." University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1131983430.
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Jaber, Wassim. "Phonon heat conduction probed by means of an electro-thermal method involving deposited micro and nanowires." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI109/document.
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The context of this PhD is the reduction of sizes involved in material development and the confinement of heat in modern devices, which are known to lead to the apparition of hot spots. The goal is to investigate heat conduction from micro- to nanoscale wide Joule-heated wires standing on flat layered materials. A particular focus is given to the analysis of phonon heat dissipation when departing from the well-known Fourier diffusive conduction and entering the ballistic regime. The manuscript starts with a summary of the main observed effects on the effective thermal conductivity in nanoscale materials, especially in light of the values of thermallyaveraged phonon mean free paths and the associated Knudsen number. Then the advantages and drawbacks of various measurement techniques are discussed. The analysis of the experimental configuration requires 2D analytical and 3D finite-element method based numerical studies of diffusive heat conduction from a finite source into a medium. Limitations of the 3! method due to wire length, substrate geometry and thin oxide layers are highlighted. The electro-thermal setup developed and the procedure used to deposit the devices on top of the samples are then detailed. A set of well-known materials with mean free path ranging from few nanometers to hundreds of nanometers is characterized with microwires. The thermal conduction properties of multilayer materials are investigated. Heat dissipation from finite sources on top of silicon substrates is then measured as a function of temperature. The mean free path is known to become large when temperature decreases. As a result, this configuration provides clues for understanding heat conduction from ballistic sources. The observed behavior is very different from the one predicted by Fourier’s law and shows a strong reduction of the dissipation. It is found that the results are comparable to earlier measurements involving ridges. They are analyzed with various levels of approximations of predictions using the Boltzmann transport equation. The results obtained may be useful in many fields, in particular for electronics and thermoelectric designsLe contexte de ce doctorat est la réduction des tailles impliquées dans le développement des matériaux et le confinement de la chaleur dans les dispositifs modernes, qui sont connus pour conduire à l'apparition de points chauds. L'objectif est d'étudier la conduction de la chaleur à partir de fils chauffés par Joule à l'échelle nanométrique et à l'échelle nanométrique, reposant sur des matériaux à couches planes. Une attention particulière est accordée à l'analyse de la dissipation thermique des phonons en partant de la conduction de Fourier bien connue et en entrant dans le régime balistique. Le manuscrit commence par un résumé des principaux effets observés sur la conductivité thermique effective dans les matériaux à l'échelle nanométrique, en particulier à la lumière des valeurs des voies libres moyennes des phonons et du nombre de Knudsen associé. Ensuite, les avantages et les inconvénients des différentes techniques de mesure sont discutés. L'analyse de la configuration expérimentale nécessite des études numériques 2D basées sur la méthode des éléments finis et des éléments finis de la conduction de chaleur par diffusion à partir d'une source finie dans un milieu. Limitations du 3! méthode en raison de la longueur du fil, de la géométrie du substrat et des couches minces d'oxyde sont mises en évidence. La configuration électro-thermique développée et la procédure utilisée pour déposer les dispositifs sur les échantillons sont ensuite détaillées. Un ensemble de matériaux bien connus avec un chemin libre moyen allant de quelques nanomètres à des centaines de nanomètres est caractérisé par des microfils. Les propriétés de conduction thermique des matériaux multicouches sont étudiées. La dissipation thermique des sources finies sur les substrats de silicium est ensuite mesurée en fonction de la température. Le libre parcours moyen est connu pour devenir important lorsque la température diminue. En conséquence, cette configuration fournit des indices pour comprendre la conduction de la chaleur à partir de sources balistiques. Le comportement observé est très différent de celui prédit par la loi de Fourier et montre une forte réduction de la dissipation. On trouve que les résultats sont comparables à des mesures antérieures impliquant des crêtes. Ils sont analysés avec différents niveaux d'approximations de prédictions en utilisant l'équation de transport de Boltzmann. Les résultats obtenus peuvent être utiles dans de nombreux domaines, en particulier pour les conceptions électroniques et thermoélectriques
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Kosmala, A. "Development of high loading Ag nanoparticle inks for inkjet printing and Ag nanowire dispersions for conducting and transparent coatings." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7754.
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The work presented in this thesis focuses on the synthesis of nanomaterials, formulation and printing of Ag nanoparticle and nanowire inks for two distinct applications: a) inkjet printing of Ag nanoparticle films on ceramic substrates with the aim of providing a smaller size of printed feature at lower cost than that can be obtained with the conventionally used screen printing, and b) Ag nanowires films prompted by the wide quest of electronics industry for materials with increased flexibility, lower cost and higher transmittance to replace indium tin oxide. Ag nanoparticles with a size of 50 nm were successfully synthesized and dispersed in aqueous medium. Two preparation routes were compared in order to distinguish the effects of solvents treatment of particles and their influence on the suspension characteristics including Ag loading, rheology, surface tension and later the electrical film properties. The co-polymer Pluronic F127 was found to be an effective as a stabiliser leading to the formulation of high silver loading in inks. The processing and characterization of silver films was performed. The aim was to reduce the number of layers in the silver nanoparticles film by increasing the thickness of a single layer with the goal of obtaining a dense and conductive film. An increase in the Ag loading, from 5 wt % to 45 wt % favoured the achievement of denser and thicker film with one layer printing. Addition of SiO2 to the ink formula resulted in denser structure and better adhesion of the printed track then the one without SiO2. A new method for improving the morphology of inkjet printed tracks has been proposed by printing the ink into the structured channels with predefined topography. Silver nanowires were synthesised and dispersed in methanol with help of copolymer F127. They were subsequently deposited on plastic and glass substrates forming conductive and transparent films.
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Ge, Chenhao. "Development of Self-Assembled Conducting Polymer Ultrathin Films and Poly(aniline) Nanowires/Sol-Gel Composite Materials as Substrates for Planar Supported Biomimetic Artificial Photosynthetic Systems." Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/195858.
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This research focuses on the development of a biomimetic photosynthetic energy transduction system which can convert the light energy into a transmembrane potential gradient. This potential gradient provides energy for transmembrane proton pumping, which can be detected potentiometrically and/or spectroscopically through the changes in the optical and electrochemical properties of conductive polymers that supports a lipid bilayer. To achieve this goal, there were two major objectives: 1) Development of a pH sensitive, conducting polymer-based thin film platform as a suitable interface to couple a planar lipid membrane to an ITO electrode and as a pH transducer to detect transmembrane proton motive force (pmf). 2) Construction of an ionophore-aided, transmembrane proton transport model system in a planar supported lipid membrane.Toward the first objective, two different approaches have been used: a) to create a conducting polymer thin film, composed of alternating layers of poly(aniline) PANI and poly(acrylic acid) PAA on an ITO-coated, planar glass substrate. The electroactivity in a neutral environment and the pH dependence of the self-assembled (SA) PANI/PAA multilayer thin films were demonstrated both electrochemically and spectroscopically. Additionally, (PANI/PAA)2 films were shown to be compatible with PSLB. The polymer cushion supported lipid bilayer was found to be highly impermeable to protons, as demonstrated by the blockage of the pH response of the PANI film underneath the lipid membrane. b) to create a PANI nanowire/sol-gel hybrid thin film on an ITO-coated, planar glass substrate. Electrochemical growth of PANI nanowires through a porous sol-gel matrix was demonstrated. The PANI nanowire/sol-gel hybrid thin film with a sol-gel capping layer was found to respond to pH both potentiometrically and spectroscopically and a uniform lipid membrane was formed on the capping layer.To achieve the second objective, a ΔpH-driven transmembrane proton transport model system supported by a PANI nanowire doped sol-gel/ITO substrate with a sol-gel capping layer was developed. Ionophore valinomycin and CCCP were incorporated into the planar supported lipid bilayer (PSLB). Driven by a transmembrane pH gradient, an enhanced rate of proton transport with a proton permeability ca. 3 orders of magnitude higher than that of the lipid membrane without ionophores was demonstrated.
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Liang, Zhiming. "MORPHOLOGICAL AND ENERGETIC EFFECTS ON CHARGE TRANSPORT IN CONJUGATED POLYMERS AND POLYMER-NANOWIRE COMPOSITES." UKnowledge, 2018. https://uknowledge.uky.edu/chemistry_etds/99.
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Organic semiconductors have wide applications in organic-based light-emitting diodes, field-effect transistors, and thermoelectrics due to the easily modified electrical and optical properties, excellent mechanical flexibility, and solution processability. To fabricate high performance devices, it is important to understand charge transport mechanisms, which are mainly affected by material energetics and material morphology. Currently it is difficult to control the charge transport properties of new organic semiconductors and organic-inorganic nanocomposites due to our incomplete understanding of the large number of influential variables. Molecular doping of π-conjugated polymers and surface modification of nanowires are two means through which charge transport can be manipulated. In molecular doping, both the energetics and microstructures of polymer films can be changed by controlling the degree of oxidation of the conjugated polymer backbone. For surface modification of inorganic nanowires, the energetics and morphology can be influenced by the properties of the surface modifiers. Meanwhile, the energy band alignment, which can be controlled by surface modification and molecular doping, may also alter the charge transport due to the variation in energetic barriers between the transport states in the organic and inorganic components.
To reveal the effects of morphology and energetics on charge transport in conjugated polymers and organic-inorganic nanocomposites, the influence of surface modifier on the electrical and morphological properties of nanocomposites was first probed. Silver nanowires modified with different thiols were blended with poly (3,4-ethylenedioxythiophene)-poly(styrenesulfonate)(PEDOT:PSS) to fabricate thin films. The modified nanowires provided a means of controllably altering the nanowire dispersability and compatibility with solvents and polymers. The results also demonstrated that charge transport between the nanowires was facilitated due to low wire-to-wire junction resistance. To further figure out the charge transport mechanism in organic-inorganic nanocomposites and the potential applications, tellurium nanowires and ferric chloride doped poly (3-hexylthiophene-2,5-diyl)(P3HT) were used to characterize energy band alignment effects on charge transport, electrical conductivity, and thermoelectric properties. The results showed that charge transfer between nanowires can be mediated by the polymer and may potentially increase the electrical conductivity as compared to the pure polymer or pure nanowires; while the observed enhancement of power factor (equal to electrical conductivity times the square of Seebeck coefficient) may not be affected by the energy band alignment. It is important to investigate the change of polymer morphology caused by molecular doping and processing method to determine how the morphology will influence the electrical and thermoelectric properties. Various p-type dopants, including ferric chloride and molybdenum tris(1,2-bis(trifluoromethyl)ethane-1,2-dithiolene) (Motfd3), were examined for us in P3HT and other polymers. The results showed that: i) At light doping levels, the electrical conductivity and power factor of polymers doped with the large electron affinity (EA) dopants were larger than small EA dopants; ii) At heavy doping levels, the large size dopants cannot effectively dope polymers even for the dopants with large EAs; iii) For the same dopant, as the IE of the polymer increased, the doping efficiency gradually decreased.
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Klein, Naiara Yohanna. "Nanofils magnétiques et semiconducteurs : adressage, caractérisation électriques et magnétiques et applications." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30313/document.
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La nanotechnologie a pris un rôle clé dans le développement technologique actuel de façon extrêmement grande et interdisciplinaire. L'utilisation de nanofils dans la construction de structures/dispositifs plus complexe peut être entrevue en raison de sa polyvalence. Comprendre la fabrication de nanofils et être capable de les caractériser est extrêmement important pour ce développement. Des dispositifs à base de nanofils semi-conducteurs et ferromagnétiques ont été étudiés dans cette thèse, abordant les techniques de croissance et d'adressage pour des caractérisations électroniques et structurelles, et pour des développements à grande échelle pour des applications industrielles. Les nanofils de cobalt ont été électro déposés à différents pH permettant d'associer le pH de la solution à la caractérisation de la structure cristalline. Les nanofils de semiconducteurs ont été crus par CVD. L'adressage et l'alignement des nanofils ont été faits par diélectrophorèse couplé avec l'assemblage capillaire. Pour caractériser les nanofils, des techniques de lithographie optique et électronique ont été utilisés pour la fabrication des contacts. Une étude d'interface matériaux semiconducteurs/siliciure a été réalisée démontrant que les valeurs de barrière Schottky sont différentes entre des nanofils de silicium et des matériaux massifs. Dans le cas de nanofils InAs la barrière est imperceptible et il a été constaté que le fil de ZnO était de type p. Les applications ont démontrées différents dispositifs, tels que les transistors, les vannes de spin, capteurs de gaz, de l'humidité et de la lumière. Dans le cadre de vannes de spin, la caractérisation de l'interface semiconducteur/ferromagnétique a permis d'associer la valeur de la hauteur de barrière de Schottky à l'épaisseur de SiO2, qui agit comme une barrière à effet tunnel. Grâce aux mesures de transistors à effet de champ (FET) , nous avons pu identifier le type de porteurs de charge pour chaque matériau, extraire leur mobilité, la tension de seuil... Les capteurs ont été fabriqués à base de nanofils en Si, InAs, et ZnO, afin d'être utilisés comme capteurs de lumière, l'humidité et les gaz. Cette thèse propose une amélioration des technologiques actuelles d'adressage de nanostructures et l'utilisation des propriétés à l'échelle nanométrique pour des dispositifs plus efficaces et une large applicabilité, fournissant la base pour de futures études et les réalisations pratiques des nanosciences et des nanotechnologiesNanotechnology is at the center of nowadays technologies in an increasing and very interdisciplinary manner. Sticking together the manufacturing and characterization of the nano-devices and their constituent nanostructures are keys for the development of the field. This thesis covered studies of ferromagnetic (Co) and semiconductors nanowires (Si, InAs and ZnO) based nanodevices. Nanowires growing and correct addressing techniques were studied for measurements and characterizations set ups and for large-scale industrial applications possibilities. The growing techniques were electrodeposition and CVD. Different pHs were used for the solutions in the case of the Co nanowires growing that were, than, connected by means of electronic lithography. The resulting measurements enabled us to associate the pH to the crystalline structure characterization. The nanowires addressing was made using the dieletrophoresis technique coupled to capillary assembly and also by contacting the isolated nanowire by means of electronic lithography. The contact made in the nanowire was favored by the silicidation technique. For this two different materials, Pt and Ni, compatible with the CMOS technology. A deep study of the interface semiconductor/silicidation was performed and the Schottky Barrier of Si nanowires was verified to be smaller than the barrier in the bulk form of Si. In the InAs nanowires case an imperceptible barrier was found. The ZnO nanowires were found to be of p-type. The following devices were manufactured: top/back-gate transistors, lateral spin valves (local and non-local valves) and multilayer-nanowires based spin valves (local valves). The semiconductor nanowires sensors (gas, humidity and luminosity) were also manufactured and tested. In the spin valves context the interface semiconductor/ferromagnetic material was studied in order to associate the Schottky Barrier height to the SiO2 width that acts as a tunnel barrier. From the semiconductors nanowires based field effect transistors (FETs) measurements it was possible to verify the charge carriers type for each different material, to extract its mobility, threshold voltage and others. The manufactured sensors were made of Si, InAs and ZnO nanowires and the main aim was to use them as gas, humidity and luminosity sensors. The ZnO nanowires have been seen to be light sensitive whereas the Si and InAs nanowires responded to the presence of humidity and of pollutant gases, e.g. the NO2
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Serre, Pauline. "Etude des propriétés structurales et électriques de réseaux aléatoires de nanofils de silicium. Application à la détection d'ADN." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENT110/document.
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Un « Nanonet », acronyme pour « NANOstructured NETwork », est défini comme un réseau de nanostructures unidimensionnelles à fort facteur de forme et aléatoirement orientées sur un substrat. Dans ce travail de thèse, une étude approfondie de nanonets à base de nanofils de silicium est présentée en vue d'une intégration dans des capteurs d'ADN. Une méthode de fabrication simple de ces réseaux a tout été d'abord développée afin d'obtenir des nanonets homogènes et reproductibles. La surface des nanofils a ensuite été fonctionnalisée afin de permettre la détection de l'hybridation de l'ADN par fluorescence. Les capteurs ainsi réalisés présentent une excellente sélectivité et une meilleure limite de sensibilité que des substrats plans. Les propriétés électriques des nanonets de silicium ont également été étudiées ce qui a mené à la description des mécanismes de conduction de ces réseaux. Ainsi, il a été démontré que le comportement électrique de ces structures est dominé par les nombreuses jonctions nanofil-nanofil et suit la théorie de la percolation électrique. De plus, une procédure d'optimisation de ces jonctions a finalement permis de stabiliser les propriétés électriques des nanonets de silicium.Ces réseaux possèdent donc des propriétés remarquables provenant des constituants individuels, les nanofils, qui présentent une surface spécifique élevée, mais également de leur structure en réseaux aléatoires offrant la possibilité de les manipuler simplement et à bas coût à l'échelle macroscopique. Ces travaux ouvrent la voie à l'intégration des nanonets de silicium dans des capteurs d'ADN reposant sur la détection électriqueA "nanonet", acronym for "NANOstructured NETwork", is defined as a network of one-dimensional nanostructures with high aspect ratio and randomly oriented on a substrate. In this work, a comprehensive study of nanonets based on silicon nanowires is presented for integration into DNA sensors. First, a simple method for the network fabrication has been developed in order to obtain homogeneous and reproducible nanonets. Then, the nanowire surface has been functionalized, so that the DNA hybridization detection is possible by fluorescence. The elaborated sensors exhibit excellent selectivity and a better sensitivity limit than planar substrates. The electrical properties of the silicon nanonets have also been investigated which resulted in the description of the conduction mechanisms of these networks. It has been shown that the electrical behaviour of such structures is ruled by the numerous nanowire-nanowire junctions and follows the electrical percolation theory. Moreover, an optimization procedure of these junctions has allowed stabilizing the electrical properties of silicon nanonets.Therefore, these networks have attractive characteristics which arise from the individual components, the nanowires with a high specific surface, but also from the structural properties of the network itself which can be simply manipulated, at a low cost, on macroscopic scales. This work paves the way for the integration of silicon nanonets into DNA sensors based on electrical detection
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Lemaire, Vincent. "Dépôts alignés de nanofils d'argent au sein de films multicouches pour des propriétés conductrices et optiques." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAE038/document.
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Cette thèse est consacrée à l’élaboration de films de nanofils d’argent orientés à l’aide de la technique de pulvérisation à incidence rasante. Couplée à la technique de dépôt couche-par-couche, il est possible de réaliser des films composés de plusieurs couches de nanofils d’argent orientées dans des directions différentes. Les films ainsi formés sont étudiés pour réaliser d’une part des supports conducteurs et transparents ordonnés et d’autre part pour réaliser des structures chirales aux propriétés optiques particulières. Une première étude est menée sur l’influence des différents paramètres de pulvérisation. Ils seront optimisés pour réaliser, dans un premier temps les échantillons transparents et conducteurs, puis dans un second, des structures chirales. Une seconde partie consiste à l’étude de structures hélicoïdales composées de plusieurs couches orientées de nanofils d’argent. Le dichroïsme circulaire de ces échantillons est étudié en fonction de différents paramètres de structure. Enfin une étude consistera à comparer les performances en tant que surface transparente et conductrice, de films orientés et d’argent sans ordre de nanofilsThis study consist in the elaboration of aligned films of silver nanowires by the Grazing Incidence Spraying (GIS) technique. Combined with the Layer-by-Layer (LbL) technique, it is possible to generate films composed of several aligned layers of silver nanowires with different directions of orientation. Optical and conductive properties of these films will be investigated to highlight the impact of these 3D ordered structures. The influence of different parameters of the GIS will be studied. These parameters will be optimized in ordrer to design samples for conductive and transparent films and to elaborate chiral structures. Chiral structures will be realized and their circular dichroism will be investigated in function of structural parameters. A last study will be realized about the influence of order for transparent and conductive electrodes by measuring performances of films with aligned and randomly deposed silver nanowires
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Agha, Hakam. "Interaction de grains colloïdale avec une ligne de disclinaison dans un cristal liquide nématique et d'auto-assemblage d'un nanofil conducteur en 3D." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAE002.
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Dans cette thèse, l'interaction entre les grains colloïdaux avec une ligne de disclinaison dans un cristal liquide nématique est explorée. Deux types de colloïdes ont été utilisés; sphérique (billes de silice) et allongé (nanotubes de carbone). En plus, différents types d'ancrage sur leur surface sont obtenus; planaire, homéotrope, et Janus (moitié planaire - moitié homéotrope). Ces paramètres ont été modifiés dans le but d'examiner et d'évaluer la force nématique agissant entre les grains colloïdaux et la ligne de disclinaison, qui est le résultat de l'interaction élastique entre les deux. Cette force est de l'ordre du pico-Newton et capable d'attirer et de fixer les colloïdes dispersés dans le cristal liquide nématique sur la ligne de disclinaison. Une fois que les colloïdes sont fixés sur la ligne de disclinaison, ils peuvent être collés ensemble par électropolymérisation de pyrrole. Ce qui donne lieu à un nanofil conducteur en 3 dimensions, qui est auto-assemblé et auto-connecté à des électrodes prédéfinies à l'intérieur du cristal liquide nématiqueThroughout this thesis, the interaction between the colloidal grains with a disclination line in a nematic liquid crystal is explored. Two types of colloids were used; spherical (silica beads) and elongated (carbon nanotubes). In addition different types of anchoring conditions on their surface is obtained; planar, homeotropic, and Janus (half planar – half homeotropic). These parameters were varied in the aim to examine and evaluate the nematic force acting between the colloidal grains and the disclination line, which is a result of the elastic interaction between the two respectively. This force is in the order of pico-newton, and capable of attracting and fixing the dispersed colloids, in the nematic liquid crystal, on the disclination line. Once the colloids are fixed on the disclination line, they can be glued together by means of electropolymerization of pyrrole. This gives rise to a 3 dimensional conductive nanowires, which are auto-assembled, and auto-connected to predesigned electrodes inside the nematic liquid crystal
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Rey, Germain. "Etude d'oxydes métalliques nanostructurés (ZnO,SnO2) pour applications photovoltaïques, notamment oxydes transparents conducteurs et cellules solaires à colorant." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENI017.
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Les nanostructures d'oxydes métalliques jouent un rôle essentiel dans les cellules photovoltaïques à colorants, puisque ces matériaux permettent la réalisation du contact électrique transparent en face avant et de la photoanode. L'oxyde stannique (SnO2) et l'oxyde de zinc (ZnO) ont été employés respectivement, car leurs propriétés optiques, électroniques et structurales sont particulièrement bien adaptées aux cellules solaires à colorant. Le contact électrique transparent, obtenu par pyrolyse d'aérosol, se présente sous forme d'une couche mince de SnO2 dopé par du fluor composée de grains nanométriques. Les propriétés électriques et optiques de ce composant ont été optimisées en vue de son intégration dans des cellules à colorants. Une étude approfondie du transport électronique au sein de la couche a permis de quantifier l'influence des différents mécanismes de diffusion suivant les cas considérés. La photoanode a été réalisée, directement à la surface de la couche mince de SnO2, par dépôt chimique de nanofils de ZnO à partir de précurseurs en phase vapeur. Le diamètre et la densité surfacique des nanofils sont contrôlés respectivement par les conditions de croissance et le degré d'oxydation du substrat. Les photoanodes à base de nanofils ont été intégrées dans des cellules à colorant. La limitation des performances de ces cellules est due à la faible surface développée par le ZnO qui conduit à la fixation d'une trop faible quantité de colorant à la surface de ce dernier. Afin de remédier à ce problème, des nanoparticules de ZnO ont été élaborées par bain chimique à la surface des nanofils. Les cellules solaires à base de structures composites présentent des performances supérieures à celles réalisées à partir de nanofils ou de nanoparticules. Les photoanodes composites permettent d'obtenir à la fois un transport efficace des électrons et de développer une surface importante et de ce fait, elles présentent des performances prometteusesMetallic oxide nanostructures play a critical role in dye-sensitized solar cells as front transparent electrodes and photoanodes. The use of stannic oxide (SnO2) and zinc oxide (ZnO) have been motivated by their particularly suitable structural, electrical and optical properties for dye-sensitized solar cells. Fluorine doped-SnO2 transparent electrodes have been deposited by spray pyrolysis in the form of thin films and consist of nanoscale grains. Their optical and electrical properties have been optimized in order to integrate them into dye-sensitized solar cells. The electron transport has been investigated in details and the influence of each scattering mechanism has quantitatively been assessed. ZnO photoanodes have directly been grown on the SnO2 surface by chemical vapor deposition in the form of nanowires. The nanowire diameter and surface density have been controlled by the growth conditions and the substrate surface oxidation, respectively. The nanowire-based photoanodes have subsequently been integrated into dye-sensitized solar cells. The relatively low efficiency of these cells has been found to be due to the small ZnO surface area, which limits the amount of dye anchored to its surface. In order to circumvent this limitation, ZnO nanoparticles have been deposited on the nanowire surface by chemical bath deposition. The nanocomposite photoanodes lead to the fabrication of dye-sensitized solar cells with promising efficiency by combining both efficient electron transport and high developed surface area
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Audoit, Jérémie. "Optimisation de la conductivité électrique transverse de composites structuraux PAEK-fils submicroniques d'argent/fibres de carbone continues avec ensimage conducteur." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30001/document.
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Ce travail propose une optimisation de la conductivité électrique transverse des composites structuraux matrice/fibres de carbone. L'influence de la fonctionnalisation électrique de l'ensimage sur la conductivité des composites est particulièrement étudiée. Des feuillets submicroniques d'argent (AgNpts) ont été élaborés en présence de citrate de sodium (TSC). Leur morphologie plane est particulièrement adaptée à une dispersion dans un ensimage. Les feuillets ont été dispersés dans une matrice modèle. Le seuil de percolation électrique des feuillets est déterminé à 5,9 %. Cette valeur est cohérente avec un facteur de forme modéré, compris entre 12 et 28. L'ensimage fonctionnalisé a ensuite été déposé sur une mèche de fibres de carbone, elle-même imprégnée par une matrice PAEK hautes performances. Avant imprégnation des fibres de carbone, des fils submicroniques d'argent ont été introduits dans la matrice PAEK. Des composites matrice-fils submicroniques d'argent/fibres de carbone avec ensimage conducteur ont été mis en œuvre. Leur conductivité électrique est élevée (7 S.m-1), alors que la fraction volumique en particules d'argent (fils et feuillets) est inférieure à 1 % en volumeThis PhD thesis deals with the optimization of transverse electrical conductivity of Thermoplastic Carbon Fiber Reinforced Polymer. The influence of an electrically conductive sizing has been investigated. Silver nanoplates (AgNpts) have been successfully synthesized by a soft chemical reduction, with trisodiumcitrate (TSC) as surfactant. Silver nanoplates have been dispersed into a model matrix, percolation threshold has been determined near 5.9 % in volume fraction. This value is consistent with their moderate aspect ratio (between 12 and 28). Size and morphology of silver nanoplates are suitable for their dispersion in the sizing. Carbon fiber has been coated with conductive sizing. Carbon fiber will be further impregnated by a PAEK thermoplastic matrix. A higher conductivity level has been achieved by introducing silver nanowires in the PAEK matrix. Structural composites consisting of matrix-silver nanowires / continuous carbon fiber sized with conductive sizing have been elaborated. Their electrical conductivity reached 7 S.m-1 for a total silver volume fraction of 1 %.vol
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Firmino, Sandro Fernandes. "Desenvolvimento de filmes finos condutores transparentes de nanofios de prata depositados sobre substratos r?gidos." Pontif?cia Universidade Cat?lica do Rio Grande do Sul, 2018. http://tede2.pucrs.br/tede2/handle/tede/8257.
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Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES
This work proposes the development of a low cost protocol for the production of TCNTs based on silver nanowires (AgNWs) on rigid substrates, and the improvement of the deposition technique to obtain a higher layer homogeneous, aiming at the optimization of its optical and electrical properties. For this, silver nanowires with length and diameter control were produced, aiming to evaluate the influence of these parameters on the optical and electrical properties of TCTFs. The effects of thermal annealing on the morphology of AgNWs networks and on the electrical and optical properties of TCTFs were also investigated. Studies were carried out to improve the deposition technique to obtain more homogeneous films and, as a result of this study, a new deposition technique (VMCV - Vertical Controlled Mechanical Vibration) was developed with INPI (National Institute of Intellectual Property). Silver nanowires were synthesized through the polyol process, which uses a polymer (N-vinylpyrrolidone) (PVP) as the coating agent. The prepared solutions of AgNWs were deposited on rigid substrates (glass / silicon) for analysis of topological and chemical surfaces, resulting in a random network of nanowires. The networks of AgNWs were characterized by MEV-FEG, UV-Vis, XPS and DSC-TGA techniques. The effect of thermal annealing on the AgNWs networks was investigated by means of in situ measurements of the evolution of the electrical resistances, through the technique of two tips, on a hot plate with temperature control system. Our best results exhibit an optical transparency (~ 83% at 550 nm) equivalent to commercial metal oxide thin films (indium oxide-oxide, ITO or fluoride oxide and tin oxide, FTO) and sheet resistance of ~ 23 ? / ?.
Este trabalho tem como proposta o desenvolvimento de um protocolo de baixo custo para produ??o de TCTFs (Filmes Finos Condutores Transparentes) ? base de nanofios de prata (AgNWs) sobre substratos r?gidos, e o aperfei?oamento da t?cnica de deposi??o para a obten??o de uma camada homog?nea, visando ? otimiza??o de suas propriedades ?pticas e el?tricas. Para isto, foram produzidos nanofios de prata com controle de comprimento e di?metro, visando avaliar a influ?ncia destes par?metros sobre as propriedades ?pticas e el?tricas dos TCTFs. Tamb?m foram investigados os efeitos do recozimento t?rmico na morfologia das redes de AgNWs e sobre as propriedades el?tricas e ?pticas dos TCTFs. Foram realizados estudos para o aperfei?oamento da t?cnica de deposi??o para a obten??o de filmes homog?neos e, como resultado deste estudo, desenvolveu-se uma nova t?cnica de deposi??o (VMCV- Vibra??o Mec?nica Controlada Vertical) registrada junto ao INPI (Instituto Nacional de Propriedade Intelectual). Os nanofios de prata foram sintetizados atrav?s do processo poliol, que utiliza um pol?mero (N-vinilpirrolidona) (PVP) como o agente de cobertura. As solu??es preparadas de AgNWs foram depositadas sobre substratos r?gidos (vidro/sil?cio) para an?lises de superf?cies topol?gicas e qu?micas, resultando em uma rede aleat?ria de nanofios. As redes de AgNWs foram caracterizadas pelas t?cnicas MEV-FEG, UV-Vis, XPS e DSC-TGA. O efeito do recozimento t?rmico sobre as redes de AgNWs foi investigado por meio de medi??es in situ da evolu??o das resist?ncias el?tricas, atrav?s da t?cnica de duas pontas, sobre uma chapa quente com sistema de controle de temperatura. Nossos melhores resultados exibem uma transpar?ncia ?ptica (~ 83% a 550 nm) equivalente a das pel?culas finas de ?xido de metal comercial (?xido de ?ndio-?xido, ITO ou ?xido de fl?or e ?xido de estanho, FTO) e resist?ncia de folha de ~ 23 ?/?.
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Cabos, Anthony. "Nouveaux nanomatériaux pour la fabrication d'électrodes flexibles transparentes." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI116/document.
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Les électrodes transparentes sont des éléments essentiels pour de nombreux dispositifs tels que les cellules solaires, les OLEDs, les écrans tactiles ou les films chauffants transparents. Au regard de la croissance forte du marché des dispositifs flexibles, le remplacement de l’ITO, matériau de référence dans l’industrie, s’avère nécessaire. Les réseaux percolants à base de nanofils(NF) métalliques sont une alternative de choix pour ce qui est des performances optoélectroniques, du coût et de la flexibilité. En particulier, les NF d’argent, fortement étudiés ces dernières années, offrent probablement le meilleur potentiel. L’objectif de cette thèse est de développer de nouvelles électrodes transparentes à NF avec un métal de substitution. Le cuivre est un candidat intéressant car à conductivité électrique équivalente, son prix est environ cent fois moins élevé que celui de l’argent. Dans ce manuscrit, différentes voies de synthèse des nanofils de cuivre (CuNF) sont abordées. Des électrodes sont fabriquées à partir de ces nanofils, notamment par impression, et des études sont rapportées sur l’évaluation de leurs performances. L’étude de la stabilité des électrodes à CuNF sous différents stress environnementaux (air sec, soleil, humidité) a été effectuée et met en évidence la stabilité moindre des NF de cuivre par rapport aux NF d’argent. Pour pallier cela, deux stratégies de protection des réseaux de nanofils ont été mises en place à base, soit d’une couche encapsulante sur le réseau, soit d’un système coeur-coquille à l’échelle du NF. La stabilité de ces systèmes a été mesurée lors du fonctionnement de ces électrodes lorsqu’elles sont utilisées pour la fabrication de films chauffants transparentsTransparent electrodes are implanted in a lot of devices such as solar cell, OLED, touch screen or transparent film heater. Market trends toward flexible devices lead replacement of the well known brittle ITO. Metallic nanowire (NW) based percolative networks are a promising alternative in terms of performances, cost and flexibility. Indeed, the widely reported silver NWs exhibited really high optoelectrical performances. The objective of this thesis is to develop new NW based transparent electrodes with other metal. Among metals, copper is the most promising because of its high conductivity and its price one hundred times cheaper. In that manuscript, we detail different synthesis of copper nanowire (CuNW), their printing to get the related performances. Then ageing under environmental stresses (dry air, sun and humidity) will be studied. Stability of CuNW into networks is very low compared to silver, to improve stability of CuNW two strategies based on capping layer on top of CunW and on core-shell nanostructure will be presented. Operating stability into transparent film heater will also be reported
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Zhang, Kelvin Hongliang. "Structural and electronic investigations of In₂O₃ nanostructures and thin films grown by molecular beam epitaxy." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:de125918-b36f-47cc-b72d-2f3a27a96488.
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Transparent conducting oxides (TCOs) combine optical transparency in the visible region with a high electrical conductivity. In2O3 doped with Sn (widely, but somewhat misleadingly, known as indium tin oxide or ITO) is at present the most important TCO, with applications in liquid crystal displays, touch screen displays, organic photovoltaics and other optoelectronic devices. Surprisingly, many of its fundamental properties have been the subject of controversy or have until recently remained unknown, including even the nature and magnitude of the bandgap. The technological importance of the material and the renewed interest in its basic physics prompted the research described in this thesis. This thesis aims (i) to establish conditions for the growth of high-quality In2O3 nanostructures and thin films by oxygen plasma assisted molecular beam epitaxy and (ii) to conduct comprehensive investigations on both the surface physics of this material and its structural and electronic properties. It was demonstrated that highly ordered In2O3 nanoislands, nanorods and thin films can be grown epitaxially on (100), (110) and (111) oriented Y-stabilized ZrO2 substrates respectively. The mismatch with this substrate is -1.7%, with the epilayer under tensile strain. On the basis of ab initio density functional theory calculations, it was concluded that the striking influence of substrate orientation on the distinctive growth modes was linked to the fact that the surface energy for the (111) surface is much lower than for either polar (100) or non-polar (110) surfaces. The growth of In2O3(111) thin films was further explored on Y-ZrO2(111) substrates by optimizing the growth temperature and film thickness. Very thin In2O3 epilayers (35 nm) grew pseudomorphically under high tensile strain, caused by the 1.7% lattice mismatch with the substrate. The strain was gradually relaxed with increasing film thickness. High-quality films with a low carrier concentration (5.0 1017 cm-3) and high mobility (73 cm2V-1s-1) were obtained in the thickest films (420 nm) after strain relaxation. The bandgap of the thinnest In2O3 films was around 0.1 eV smaller than that of the bulk material, due to reduction of bonding-antibonding interactions associated with lattice expansion. The high-quality surfaces of the (111) films allowed us to investigate various aspects of the surface structural and electronic properties. The atomic structure of In2O3 (111) surface was determined using a combination of scanning tunnelling microscopy, analysis of intensity/voltage curves in low energy electron diffraction and first-principles ab initio calculations. The (111) termination has an essentially bulk terminated (1 × 1) surface structure, with minor relaxations normal to the surface. Good agreement was found between the experimental surface structure and that derived from ab initio density functional theory calculations. This work emphasises the benefits of a multi-technique approach to determination of surface structure. The electronic properties of In2O3(111) surfaces were probed by synchrotron-based photoemission spectroscopy using photons with energies ranging from the ultraviolet (6 eV) to the hard X-ray regime (6000 eV) to excite the spectra. It has been shown that In2O3 is a highly covalent material, with significant hybridization between O and In orbitals in both the valence and the conduction bands. A pronounced electron accumulation layer presents itself at the surfaces of undoped In2O3 films with very low carrier concentrations, which results from the fact the charge neutrality level of In2O3 lies well above the conduction band minimum. The pronounced electron accumulation associated with a downward band bending in the near surface region creates a confining potential well, which causes the electrons in the conduction band become quantized into two subband states, as observed by angle resolved photoemission spectra (ARPES) Fermi surface mapping. The accumulation of high density of electrons near to the surface region was found to shrink the surface band gap through many body interactions. Finally epitaxial growth of In2O3 thin films on α-Al2O3(0001) substrates was investigated. Both the stable body centred cubic phase and the metastable hexagonal corundum In2O3 phase can be stabilized as epitaxial thin films, despite large mismatches with the substrate. The growth mode involves matching small but different integral multiples of lattice planes of the In2O3 and the substrate in a domain matching epitaxial growth mode.
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Choueib, May. "Étude des propriétés physiques de nanofils individuels de carbure de silicium par émission de champ." Phd thesis, Université Claude Bernard - Lyon I, 2009. http://tel.archives-ouvertes.fr/tel-00656991.
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Ce travail s'inscrit dans le cadre de la caractérisation physique de nanofils (NF) semiconducteurs (SC) qui est un domaine en plein essor ces dernières années. Plus précisément, nous explorons l'émission de champ (EC) de NFs individuels de Carbure de Silicium (SiC) pour leur potentialité comme source d'électrons, mais surtout pour étudier leurs propriétés de transport électrique, optiques et mécaniques.Le rôle important joué par la surface dans ces NFs a été prouvé par des traitements in situ qui ont eu des conséquences radicales sur l'EC dévoilant ainsi des propriétés d'émission propres aux SCs. En particulier, un régime de saturation, en accord avec la théorie d'EC des SCs, associé à une forte dépendance de l'émission à la température et à l'illumination laser a été révélé pour la première fois pour un NF. Ces mesures ouvrent des perspectives importantes tant pour la recherche fondamentale que pour les applications telles que la réalisation de photocathodes et de sources d'électrons pilotées optiquement ou par la température. Les caractéristiques courant-tension-température associées à l'analyse en énergie des électrons émis nous ont permis de déterminer le mécanisme de transport dans ces NFs, qui est limité par le nombre de porteurs dans le volume et contrôlé par les pièges présents dans la bande interdite par l'effet Poole-Frenkel. Finalement, la caractérisation mécanique a révélé des valeurs du facteur de qualité élevé (160000) et du module de Young allant jusqu'à 700GPa. Ces valeurs sont très prometteuses pour l'utilisation de ces NFs dans les systèmes nano-électro-mécaniques et dans les composites.
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Ramachandran, Laavanya. "Comportement électrique large bande des composites polymère - fils submicroniques d'or : corrélation avec la structure et les propriétés mécaniques." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30072/document.
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L'objectif principal de ce travail est d'étudier les propriétés d'un composite polymère-métal d'un point de vue physique, thermique, mécanique et électrique large bande. Pour cela, des fils d'or à haut facteur de forme (190) ont été élaborés par un procédé d'électrodéposition dans un template. Les fils submicroniques d'or ont été dispersés dans une matrice polymère PVDF pour l'élaboration des composites conducteurs faiblement chargés. Le comportement électrique des composites met en évidence le phénomène de la percolation électrique, avec un seuil de 1,33 %vol. La dispersion des fils submicroniques d'or au sein de la matrice PVDF est homogène, avec une légère orientation. L'analyse mécanique permet de mettre en évidence le rôle de renfort des fils d'or dans la matrice PVDF et l'influence des fils sur la structure physique du PVDF. Cela se traduit par une rigidification de la matrice PVDF et plus particulièrement l'effet sur la relaxation ac , associée à l'interface cristallite-phase amorphe du PVDF. L'étude de la conductivité statique et dynamique en basse (10-2 à 106 Hz) et haute (106 à 109 Hz) fréquence montre un changement de régime de transport de charge avec une activation thermique. La conduction par tunneling est prédominante à basse température, tandis que la conductivité au-delà est expliquée par les modèles d'Efros et Shklovskii et le modèle de saut de barrières corrélés (CBH), respectivement pour la partie statique et dynamique. Les paramètres déterminés avec les modèles présentent une bonne corrélation avec les propriétés mécaniques, ce qui permet d'améliorer la compréhension des phénomènes de transport de charge dans des systèmes hétérogènes tels les composites polymère-métal faiblement chargésThe aim of this work is to study the properties of a polymer-metal composite, with regards to physical, thermal, mechanical and broad band electrical analyses. High aspect ratio gold nanowires (Au NW) were prepared using a template electrodeposition method (aspect ratio of 190 determined by image analysis). The gold nanowires were dispersed in a PVDF polymer matrix to form low-filled conducting composites. The electrical conductivity of the composites exhibit electrical percolation behaviour with a critical volume fraction of 1.33%. SEM images show a slightly oriented but homogenous dispersion of AU NWs within the PVDF matrix. Mechanical analysis confirms that the homogenous dispersion Au NWs reinforces the PVDF matrix and highlights the influence of Au NWs on the physical structure of the PVDF matrix. This is confirmed by an increase in G' values and more specifically the ac relaxation process (associated with the crystallite-amorphous phase interface). Analysis of static and dynamic conductivity for low (10-2 to 106 Hz) and high frequency (106 to 109 Hz) regions reveals a thermally-activated charge transport process: tunneling being the predominant mechanism at low temperatures, the Efros and Shklovskii (ES) and Correlated Barrier Hopping (CBH) models being responsible for static and dynamic conductivity, respectively. The models were found to be coherent with the structure and mechanical properties of the composites, leading to a better understanding of charge transport mechanisms in low-filled polymer-metal composites
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Idier, Jonathan. "Utilisation de nanomatériaux anisotropes pour l'élaboration d'électrodes transparentes conductrices." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0314/document.
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Ce travail de thèse est principalement dédié à la mise en forme et à l’utilisation de nano-objets unidimensionnels comme matériaux d’électrodes transparentes. Les nanofils d’argent font partie des candidats les plus prometteurs pour le remplacement de l’oxyde d’indium-étain, actuellement le plus répandu dans les dispositifs commerciaux. La forte instabilité des nanofils d’argent à l’oxydation est néanmoins un problème critique puisque les électrodes deviennent moins performantes en peu de temps. En premier lieu, la triphénylphosphine a été utilisée comme agent inhibant l’oxydation. Contrairement aux électrodes non modifiées, celles-ci sont stables pendant plus de trois mois. Une deuxième partie est consacrée à l’utilisation de l’électrofilage pour élaborer des électrodes transparentes à base de nanofibres de matériaux conducteurs (nanofibres de cuivre, nanotubes de carbone, oxyde de graphène réduit). Enfin, une dernière partie concerne l’étude des propriétés mécaniques de nanofibres d’alcool polyvinylique par l’écoulement d’un fluide porteur dans une constriction réalisée en impression 3D. Cette méthode permet une analyse et une évaluation simple et rapide de la contrainte à la rupture des nanofibres, propriété difficilement accessible par des mesures mécaniques traditionnellesThis PhD work deals mainly with the high scale organization and use of unidimensional nano-objects for making transparent electrodes. Among the candidates of choice for the replacement of indium tinoxide, the main material used in commercial devices, silver nanowires (Ag NW) are among the most promising. However, the tendency of silver nanowires to be quickly oxidized can severely affect their performances. Firstly, this drawback is circumvented through the use of triphenylphosphine (PPh3)as a protective agent. Unlike bare Ag NW electrodes, the PPh3 modified Ag NW electrodes are stable over three months. A second part is dedicated to the production of transparent electrodes via the electrospinning technique. Materials such as copper nanofibers, carbon nanotubes and reduced graphene oxide are investigated. The last part of the manuscript deals with the measurement of the mechanical properties of poly(vinyl alcohol) (PVA) nanofibers. To do so, the flowing of a fluid in a3D-printed constriction is used. Usually determined with difficulty, the fracture strength of the nanofibers can be evaluated quickly at ease
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Huang, Shao-xian, and 黃韶嫻. "Preparation and characterization of silver nanowire transparent conductive films." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/40244887350049870336.
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碩士國立雲林科技大學
化學工程與材料工程系碩士班
101
This study was divided into two major parts: In the first part,we used the cheaper sodium chloride (NaCl) as the seeds and the ethylene glycol as the reducing agent to synthesize silver nanowires in high temperature 160 ℃through the polyol synthesis method.First,AgNO3was reduced to form silver nanoparticles.Then,the silver particles glowed and transformed to silver nanowires in the presence of PVP.We successfully prepared silver nanowires with a diameter of about 50-100 nm and a length of about 10-20 μm.The transparent conductive films prepared using the silver nanowires can have a transparency of 82 % and a sheet resistance of 52 Ω/sq.The conductivity of the conductive films can be improved by suitable gas and heat treatment. We used the polyethoxysiloxane(PES) to fill the voids among the silver nanowires and connect the silver nanowires closely to the substrate.The method can improve the anti-scratch and conductivity,anti-oxidation,flexibility properties of the thin films,which may be capably applied as optoelectronic materials in the future. In the second part,we used the two-step synthesis method to fabricate the AgNW@Ni core-shell nanowire. The core-shell structure of nanowires was identified by the transmission electron microscopy.Finally,We successfully aligned the AgNW@Ni nanowires in sequence by the magnetic field and investigated the conductive property of the AgNW@Ni films.
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Su, Ching-Kuei, and 蘇清貴. "Polypyrrole Conductive Polymer Modified Silicon Nanowire Arrays For Biosensor Applications." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/14779817729347426410.
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碩士國立交通大學
機械工程學系
100
A simple and low in cost approach to generate silicon nanowires (SiNWs) of single-crystalline, well-aligned, and large area has been synthesized via a silver assisted electroless metal method. The aims of this study are divided into two sections, (1) effect of the different size silver catalyst in the fabrication of silicon nanowires (SiNWs) array via EMD method and (2) polypyrrole conductive polymer was used to modify SiNW arrays, and immobilized BSA with glutaraldehyde cross-linking. The results show that the best of silver catalyst size in the fabrication of SiNW arrays was 3min.When the pre-deposition times of silver catalyst are too short or too long, SiNW arrays could not be formed in this study. When pre-deposition time is too short, the silver particles were more dense lead to SiNW arrays has been not synthesized. When pre-deposition time is too long, too much silver dendrite was fabricated lead to larger spacing. Large-area ordered single crystal SiNW arrays on p-type (100) silicon wafer without the use of a template were prepared in a hydrofluoric acid and (HF / H2O2) solution at 50oC by silver assisted electroless etching (pre-deposition silver catalyst for etching 3min). The result showed that highly dominant peak at 69° is belong to (400) silicon plane which can be explained equally by preferential etching along [100] directions. The linear relationship of SiNW arrays could be adjusted by controlling the immersion time. On the other hand, polypyrrole conductive polymer treatment was confirmed to be an effective precursor to the introduction of amine functionalities onto the SiNW arrays surface, to enhance their biocompatibility. The results show that the best immersion time of PPy modifying SiNW arrays was 48hr. The amine (NH2) functional groups were incorporated on the SiNW arrays surface by FTIR analysis. The glutaraldehyde (GA) was used to cross-link the amino (NH-) functional groups with bovine serum albumin (BSA) onto the PPy-SiNW arrays surface. In addition, the bovine serum albumin (BSA) detection Zn signal was investigated by FTIR, energy dispersive spectrometer (EDS) and X-ray diffraction (XRD) measurements. The results demonstrate Zn signal could be detected. The lower concentration of ZnSO4 at 0.1 mM also could be detected. Therefore, these results demonstrate that the induction of amino groups onto SiNW arrays surface, using polypyrrole conductive polymer treatment, is an novelty, effective and reliable method which could be expected to have favourable applications in biosensor.
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TSAI, YI-HAN, and 蔡宜涵. "Preparation and Characterization of Silver Nanowire-based Transparent Conductive Thin Film." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/68793220579484001756.
Full textAbstract:
碩士逢甲大學
化學工程學系
105
The aim of the thesis is to study the synthesis of silver nanowires by applying it to a transparent conductive film. Based on the data from published papers and results the of experiments the preparation and characterisation of the silver nanowire-based transparent conductive thin film has been analysed and presented. The experiments shows that the sliver nanowires has great electrical properties and extensibility in transparent conductive film. Therefore, the increase demand of various products applying sliver nanowires, has turned such material in to potential components in nowadays technology industry. The thesis then identifies the variables that included in the experiment of the analysation of silver nanowire-based transparent conductive thin film regarding three different aspects: the quantity of solid constant, the coating frequency and the holding time. The detail procedure of the experiment and practical tips for future development has also been provided in the thesis. By implementing the polyal method, the experiment began on deoxygenating the sliver nitrate （AgNO3） into 1,2 - propanediol (Propylene Glycol, PG). Then, adding the sliver nitrate （AgNO3） in Propylene Glycol for the purpose of deoxygenize the sliver nitrate and transferred it into Sliver Nanoparticle. Followed by adding both the 1-Buty1-3-methylimidazolium chloride to help accelerates the process and the Polyvinylpyrrolidone （PVP） to limit the transferring direction. Finally, analysing the characteristic of Sliver Nanoparticle that applied on the transparent conductive film. Last but not least, the experiment has successfully produced silver nanowires and applied it onto the transparent conductive film. For going forward, it is suggested that coating silver nanowires onto different material substrates is essential for full-development of its extensibility. Additionally, adding other solvents to increase the firmness are also recommended. The thesis also provides the informations and recommendations for the implementation of the silver nanowires such as producing a extensible mobile phone.
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Wang, Tzu-Chi, and 王孜齊. "Synthesis and Characterization of Conductive Oligoanilines–Graphene / Ag nanowire -Polyurethane Composite Materials." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/3b8m25.
Full textAbstract:
碩士國立臺北科技大學
有機高分子研究所
102
The study is based on tetraaniline synthesized by using aniline dimer as monomer and FeCl3 as oxidant. However, tetraaniline are commonly classified as rigid, brittle, and difficult to process. And the experiment uses the polyurethane to improve its disadvantages. The prepolymer with -NCO group was obtained by the reaction of Poly-(caprolactone)-diol (PCL) as soft segments and 4,4-diphenylmethane diisocyanate (MDI) as hard segments which were with the molecular weight 2000 and 250 respectively. Then the tetraaniline could connect end to end in two shorts of the prepolymer with -NCO group to form copolymer. The copolymer could be blended with Ag nanowire or graphene as addition agent while dissolve in DMF. The structures of nanocomposites were investigated by FTIR spectra and MS. The analysis of microstructure was by SEM. The physical properties of nanocomposites were investigated by DMA, Four-point probe, and XRD. The experimental results of Ag nanowire content 3% in the copolymer, and the best conductivity is 4.60*10-2S/cm. However, the stretched molecular chains in nanocomposites are orientation as the increase in conductivity.
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Cho, Wei-Min, and 卓偉民. "Effects of Si-nanowire surface passivation on the device performance of conductive polymer/Si-nanowire arrays/n-type Si diodes." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/49057012482899157806.
Full textAbstract:
碩士國立彰化師範大學
光電科技研究所
101
The effect of Si-nanowire (SiNW) surface passivation on electronic transport of heterojunction diodes based on the poly(3,4-ethylenedioxythiophe- ne) doped with poly(4-styrenesulfonate) (PEDOT:PSS) and n-type Si with SiNW arrays was investigated in this study. The PEDOT:PSS/SiNWs/n-type Si diode without SiNW surface passivation shows a poor rectifying behavior with an ideality factor (η) of 7.8 and high leakage. However, the PEDOT:PSS/SiNWs /n-type Si diode with SiNW surface passivation shows a good rectifying behavior with η of 1.7 and low leakage. Such an improvement indicates that a good passivation is formed at the interface as a result of a combined effect of the formation of Si-O bonds and the removal of the short-lifetime charge traps. Note, SiNW surface passivation plays a significant role in the photoconduction by providing the contribution of long-lifetime charge trapping to the decay process.
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薛羽利. "The study on synthesis of silver nanowire by polyol method for transparent conductive film." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/fb5g5q.
Full textAbstract:
碩士國立彰化師範大學
機電工程學系
100
In the study, we used the polyol method to synthesize silver nanowire, and the use of silver nitrate (AgNO3) as the precursor for seeds. Unlike other studies,we not use the metal salts (PtCl2, NaCl) as the seed precursors before the synthesis of silver nanowires. The experimental results show that the different synthesis temperature, Poly(N-vinylpyrrolidone) (PVP) molecular weight, the concentration of reactants and the addition rate of silver nitrate will affect the growth characteristics of silver nanowires. SEM, UV-Vis spectra and XRD have been employed to characterize the silver nanowires. When the synthesis temperature is higher than 180 oC, the nucleation rate is too fast. Therefore, the particles are homogeneous nucleation and the formation of silver particles. When increasing the concentration of PVP, the diameter of the silver nanowires will be widened to cause a smaller aspect ratio. This study successfully prepared silver nanowires with a diameter of 170 nm and a length of 21 μm. Finally, the transmittance and sheet resistance were measured by UV-VIS-NIR spectrophotometer and four-point probe I-V test, respectively.The solution-type silver nanowire thin film shows high transmittance, low sheet resistance and can be used for transparent conductive film application.
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HO, YING-RONG, and 何映融. "The Study of AZO / Silver Nanowire Composite Transparent Conductive Films by RF Magnetron Sputtering." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/86ts3y.
Full textAbstract:
碩士亞洲大學
資訊工程學系
105
In this study, a transparent conductive film was deposited on a glass substrate and a PET substrate by magnetron sputtering. The effects of substrate temperature and working pressure on the structure and properties of AZO thin films investigated by using a zinc oxide doped aluminum (AZO) ceramic target. On the other hand, the effect of AgNWs on the flexibility of AZO films investigated. For AZO film, the experimental results indicate that the films show the best direction of (002) under different sputtering conditions. At the power of 50W, the working pressure of 5mtorr, the argon flow rate of 15 sccm and the substrate of heated to 200℃, the grain size of AZO film decreases with the temperature and becomes dense because Al atoms easily activated into the zine oxide structure by high substrate temperature. The penetration rate of 85.23% and the resistivity of 4.72 × 10-4 Ω‧cm. The particle size decreases with the decreased of pressure, and becomes small and compact because of the freedom of particles. When the working pressure is 1 mtorr, the grain size decreases with the decreased pressure. The reason is form the improved partical free path. A penetration rate of 85.42% and a resistivity of 1.14× 10-4 Ω‧cm. For AZO/AgNws film, the resistivity and AFM average roughness respectively of 1.14 × 10-4 Ω‧cm and 9.85 nm. The resistivity after the flexible test of 1000 times is degraded to 1.73×10-3 Ω‧cm.
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Chen, Pei-Wen, and 陳姵雯. "Fabrication of Silver Suspension and Transparent Conductive Thin Film Based on Silver Nanowire/Nanoparticle." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/p37s46.
Full textAbstract:
碩士國立臺灣大學
化學工程學研究所
105
Silver nanowires and silver nanoparticles have received considerable attention due to their electrical, optimal and thermal properties used in various applications such as conductive thin film since bulk silver (Ag) has the highest thermal and electrical conductivity among all metals. Two methods were developed in this research to fabricate transparent conductive thin films from stable silver-nanowire or silver-nanoparticle suspensions. Chemical method was applied to synthesize silver nanowires; whereas electrospinning method was used to prepare silver nanoparticles. Three divided sections were contained in this thesis. In the first section, we demonstrated a parametric study on self-seeding polyol synthesis of optimal Ag nanowires. The effects of synthesizing temperature, molar ratio of poly(vinylpyrrolidone) (PVP) to silver nitrate, injecting rate of silver nitrate, concentrations of sodium chloride and potassium bromide, and stirring rate on the morphology of Ag nanostructures were examined. The morphologies of nanostructures and aspect ratio on synthesis parameters were shown via scanning electron microscopy (SEM) images. Ag nanowires were optimally synthesized by polyol process with a high aspect ratio of over than 300, where the average diameter and length were 40 nm and 12-15 μm, respectively. In terms of silver nanoparticle, single-jet electrospinning nethod was used to fabricate silver electrospun fibers, and the fibers were pre-annealed, and these fibers were re-disperded in water to form the stable silver nanoparticle suspension with the assistance of PVP from fibers. Traditionally, Ag nanowires were hardly suspended in polar or nonpolar solvents owing to their high density. In the second section, some innovative and facile formulas were proposed to prepare the water-based stable Ag nanowire suspensions with the addition of dispersive agent such as polyethylenimine (PEI), poly(vinylpyrrolidone) (PVP) and BYK-410 as suspending agent. When adding a little amount of polymers, polymer served as dispersion that associated with Ag nanowire, thus changing the interaction between Ag nanowires. We also examined the effect of pH values and zeta potential on the suspended behaviors of the polymer-bound Ag nanowire in aqueous solutions. The last section, a practical and general approach is described to fabricate the conductive thin films. Ag nanowires were dispersed stably in aqueous phase by the addition of dispersive agent under homogenization and Ag nanoparticles were dispersed in water phase then followed by three distinct processes including drop casting, spray coating and spin coating. Through the above-mentioned methods, good electrical and optical properties of prepared polymer-bound Ag nanowires/nanoparticles conductive thin films were performed. The proposed method provided a simple and practical approach for the fabrication of the conductive thin films with excellent transparency and showed the significant potential to apply in electronic fields generally.
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Huang, Chi-Ying, and 黃麒穎. "A studying for preparation and characterization of Graphene oxide/silver nanowire conductive composite film." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/47716341047234340299.
Full textAbstract:
碩士國立勤益科技大學
化工與材料工程系
103
The study use graphene oxide(GO) and silver nanowire(AgNW) prepared Transparent conductive films(TCFS). research GO dispersion in solution and preparation condition. Silver nanowire synthesis temperature and PVP protection agent effect. Select the best conductivity formula analysis the film transmittance and conductivity. different graphene and nano silver wire content with PMMA oligomer to prepared transparent conductive film. using SEM observation GO dispersed in PMMA. results show graphene content increase conductivity rise and transmittance decreased. results show graphene content increase conductivity rise and transmittance decreased. put in silver nanowire to increase film conductivity and maintain the transmittance to achieve high transmittance and high conductivity targets. coating on PET Improve the traditional ITO bent resulting increase in resistance.
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Hsieh, Ang-Chun, and 謝昂君. "The Effect of Dispersing Agent on Physical Properties of Silver Nanowire Transparent Conductive Films." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/08828547397226814070.
Full textAbstract:
碩士逢甲大學
纖維與複合材料學系
103
The purpose of this research is to prepare conductive nano film based on silver nanowire as the conductive material by spin coating method. In this study, we focused on improving the dispersion of silver nanowire thereby enhancing performance of transparent conductive film made of silver nanowire. In order to solve the adhesion problem of silver nanowire film, PEDOT: PSS was adopted to coat on silver nanowire as a protective overcoating layer. The performance properties of silver nanowire /PEDOT:PSS films were evaluated for reaching the therehold standard of conductivity below 100 Ω/sq and transmittance more than 80 %. The experimental results showed that silver nanowire was dispersed well and showed a good formation of conductive network when 5 wt% diethylene glycol butyl ether (DGBE) was added. The best conductivity and transmittance value was 41.76 Ω/sq and 78.03 %, respectivily. The results indicate that PEDOT:PSS coating reduce the roughness of the film and effectively prevent the silver nanowire peeling by external force. Consequentially, the optimal parameters for transparent film of silver nanowire are as follows: the concentration of DGBE is 5 wt%, the speed of spin coating is at 3000 rpm with PEDOT:PSS coationg, which result in a film conductivity value of 47.53 Ω/sq and transmittance value of 69.84 %, both value reaches the threhold standard.
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Chang, Yen-Cheng, and 張晏誠. "The Synthesis of Copper Nanowire in Solution Phase and their Application in Transparent Conductive Electrode." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/49188598939688481955.
Full textAbstract:
碩士國立清華大學
化學工程學系
100
In this study, thin, long, and well-dispersed copper nanowires were obtained via the seed-mediated growth in an organic solvent-based synthesis. The mean length and diameter of nanowire are about 37.7 μm and 46 nm with a high aspect ratio of 820. These wires were used for nanowire conducting films since their relatively long length is advantage in lowering the sheet resistance. Transparent conducting copper nanowire electrodes were prepared by a simple, facile and low cost spray coating method and their properties were characterized. Transparent electrode with optical transmittance and sheet resistance of 90% and 50Ω/sq was obtained. A relatively high value of 300 for the optoeletricial property, σDC/σOp, was obtained, only inferior to silver nanowire-based conducting glass. Moreover, the copper nanowire films maintained their electrical stabilities upon exposed to the ambient over more than one month.
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SHEN, LIEN CHIEN, and 練建伸. "Investigation of Coating of TAPU/Ag nanowire on a Nylon 6 fabric Conductive Composite Materials." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/4tfqqb.
Full textAbstract:
碩士國立臺北科技大學
有機高分子研究所
103
The study is based on aniline tetramer as the substrate. In this article added different proportions of nanomaterials, such as nano-silver wire, grapheme and then coated on a Nylon fiber. In different proportions, it had different conductivity properties. The tetraani-line synthesized by using dianlien as monomer and FeCl3 as a oxidant. However, tertaaniline are commonly classified as rigid ,brittle ,and difficult to process. And experiment method is to flexible macromolecules such as PU into conjugated polymer to make polymer composites.The prepolymer was reacted by ether type poly(tetramethyleneglycol) (PTMO) as soft segments and 4,4-diphenylemthane diisocyanate (MDI)as hard segments with molecular weight 2900 and 250 resp-ectively. The application of aniline tetramer have limited because it&;#39;s fragile and difficult process. Therefore, this article will use of flexible and soft polyurethane to improve. Then the tetraaniline could connected end to end in two short of the prepolymer to form copolymers. The copolymer could be as some Nano sliverwire or grapheme as addition agent while the copolymer dissolve in DMF. Then, aniline tetramer added some metallic or non-metallic conductive material, nano: silver nanowire &; grapheme and grapheme fixed content, this article changed the proportion silver nanowire. Because of their unique structure that can keep maintaining the characteristics of the elastomer and also increasing the conductivity of the composite material thereof. The structures of nano-composites chemical were investigated by FTIR spectra. The analyze the microstructure were by SEM and the conductivity, measurement were by high impedance meter or Four-Point Probe.
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Lin, Ya-Ting, and 林雅婷. "Fabrication of flexible transparent conductive film with high electrical stability using reduced graphene oxide/copper nanowire composites." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/05816578753658633718.
Full textAbstract:
碩士國立清華大學
材料科學工程學系
104
Among the materials for preparing transparent conductive films (TCFs), metal nanowire is gaining a great deal of interest owing to advantages of low sheet resistance (Rsh), high transparency and high flexibility, and copper nanowires (CuNWs) is one of the metal nanowires been investigated. However, CuNWs face the serious problem of oxidation, which results in the deterioration on electrical conductivity. In this work, we developed a highly stable electrical approach based on reduced graphene oxide (rGO)/ CuNW for TCFs. The presence of the rGO playing a role a gas barrier layer can effectively overcome the problem of CuNW oxidation. The electrical stability of the rGO/CuNW films prepared by varied syntheses were investigated systematically. The CuNWs with an average diameter of 58 ± 9 nm and a length longer than 10 μm were synthesized through a solution-based method. The best optoelectrical property of the CuNW film is 89.2% @ 550 nm and 22.0 ± 0.6 Ω/sq. After exposure to ambient atmosphere for 15 days, the Rsh of CuNW film substantially raised to 256.7 ± 2.1 Ω/sq., and became an insulator after 26 days. To solve the oxidation problem, two rGO fabrication processes were developed, one was chemically reduced graphene oxide (c-rGO), and the other was treating the graphene oxide by thermal reduction under hydrogen to form h-rGO. Similar trend of variety in Rsh between c-rGO/CuNW film and CuNW film was detected. On the contrast, after exposure to ambient atmosphere for 30 days, the Rsh of h-rGO/CuNW film was slightly increased from 25.1 ± 0.1 /sq. to 42.2 ± 0.1 /sq. accompanied a transmittance of 85.9% @ 550 nm. Such high electrical stability is due to the complete coverage of h-rGO on CuNW caused by the hydrophilicity of GO in nature. The high flexibilityof h-rGO/CuNW film was also demonstrated. Based upon the obtained results, the synthesized h-rGO/CuNW film possesses high electrical stability and flexibility, which is a potential material in TCFs.