Дисертації з теми "Nanostructured architectures"
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Jean, Joel Ph D. Massachusetts Institute of Technology. "Nanostructured architectures for colloidal quantum dot solar cells." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82187.
Повний текст джерелаThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 73-79).
This thesis introduces a novel ordered bulk heterojunction architecture for colloidal quantum dot (QD) solar cells. Quantum dots are solution-processed nanocrystals whose tunable bandgap energies make them a promising active-layer candidate for next-generation optoelectronic devices, including solar cells and light-emitting diodes. Despite rapid advances in performance, however, modern QD solar cells remain limited by a fundamental trade-o between light absorption and photocarrier collection due to poor electronic transport. Vertically aligned arrays of ZnO nanowires can decouple absorption and collection: The nanowires penetrate into the QD film and serve as highly-conductive channels for extracting photogenerated electrons from deep within the film. After optimizing the nanowire growth and device fabrication processes, we nd that incorporating nanowires boosts the photocurrent and the eciency of planar QD photovoltaic devices by 50% and 35%, respectively. The demonstrated AM1.5G power conversion eciency of 4.9% is among the highest ever reported for a ZnO-based QD solar cell. We further show that graphene can serve as a viable alternative to tin-doped indium oxide (ITO) as a transparent conductive electrode for thin-film optoelectronics. We grow ZnO nanowires on graphene and fabricate prototype graphene-based ordered bulk heterojunction QD devices with photovoltaic performance approaching that of ITO-based solar cells. Our work shows that nanostructured architectures can substantially improve QD solar cell performance, and that a simple, low-temperature, bottom-up solution growth process can produce nanowire alignment and device performance matching that of top-down synthetic processes, with the added advantage of compatibility with a variety of rigid and flexible substrates. The 1-D nanostructure design principles we propose and apply here can be generalized to a broad range of optoelectronic device applications. This study of scalable bottom-up processing of ZnO nanowire-based QD solar cells suggests that 1-D nanostructures may be the key to enhancing the eciency and hence the economic viability of quantum dot photovoltaics.
by Joel Jean.
S.M.
Bayle, Maxime. "Architectures plasmoniques enterrées : élaboration, propriétés optiques et applications." Toulouse 3, 2014. http://thesesups.ups-tlse.fr/2664/.
Повний текст джерелаIn our work, we present the study of plasmonic architectures made of a plane of nanoparticules (NPs) embedded at the vicinity of a dielectric matrix free surface, by low energy ion beam synthesis. Materials structural analysis, especially by transmission electron microscopy, have been carried out to determine the impact of the elaboration process parameters on the three dimensional organization of the NPs, in silicon dioxide or nitride layers grown on silicon substrates. To systematically check these parameters, we studied the elastic and inelastic optical responses of the heterostructures. The elastic response has been obtained by measuring the reflectance of the samples, and confronted to numerical modelling we developed, to determine the mean size of the NPs and the implanted silver amount. The study of the electric field topography allowed us to take benefit from both plasmonic resonance and optical amplification in antireflective layers. The inelastic response has been studied using Raman spectroscopy over a wide frequency range: vibrational collective modes (Lamb modes) of the NPs have been studied at low frequency, while at higher frequency, we have extracted the vibrational density of states (VDOS). Combined with atomistic simulations, the VDOS gave us original information on the vibrational dynamics and the thermodynamic properties of buried silver NPs (and deposited gold NPs). Finally, we present some applications of the assemblies of NPs in hybrid devices, such as the use of coupling between these NPs and deposited substances (e. G. Graphene) on our substrates. In particular, it can be used for surface enhanced Raman spectroscopy (SERS). Then using techniques from microelectronics, we designed plasmo-electronic devices exploiting photoconductance properties of these buried or deposited NPs assemblies
Schulze, Carsten [Verfasser], Manfred [Akademischer Betreuer] Albrecht, Manfred [Gutachter] Albrecht, and Sibylle [Gutachter] Gemming. "Magnetization Reversal in Film-Nanostructure Architectures : Magnetization Reversal in Film-Nanostructure Architectures / Carsten Schulze ; Gutachter: Manfred Albrecht, Sibylle Gemming ; Betreuer: Manfred Albrecht." Chemnitz : Universitätsbibliothek Chemnitz, 2014. http://d-nb.info/1214302173/34.
Повний текст джерелаSchulze, Carsten. "Magnetization Reversal in Film-Nanostructure Architectures ." Doctoral thesis, Universitätsbibliothek Chemnitz, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-142720.
Повний текст джерелаNguyen, Van Tang. "Nanostructured soft-hard magnetic materials with controlled architecture." Thesis, Le Mans, 2018. http://www.theses.fr/2018LEMA1007.
Повний текст джерелаAmong currently investigated rare-earth-free magnets, ferromagnetic τ-MnAl is a highly potential candidate as having promising intrinsic magnetic properties. In my thesis, Mn(Fe)AlC was synthesized by mechanical alloying method. Effects of carbon on microstructure and magnetic properties were systematically investigated. It was found that high purity of τ-MnAl(C) could be obtained at 2 at.% C doping, showing clearly stabilizing effect of carbon. Mn54.2Al43.8C2 has the best magnetic properties: magnetization at 2T M2T = 414 kAm-1, remanent magnetization Mr = 237 kAm-1, coercivity HC = 229 kAm-1, and |BH|max = 11.2 kJm-3. HC increased inversely with the crystallite size of τ phase and proportionally with C content. Moreover, first principle calculation showed both stabilizing effect and preferable interstitial positions of carbon in tetragonal τ-MnAl. Mn51-xFexAl47C2 (x= 0.25, 0.5, 1, 2, 4, 6) alloys were also synthesized by mechanical alloying method, showing high purity of τ phase up to 2 at.% Fe doping. Adding of Fe on MnAl(C) reduced both magnetization and TC but likely increased slightly HC. 57Fe Mössbauer spectrometry at 300K was used to probe local enviroment in ε-, τ-, β-, and γ2-MnFeAl(C). In which, γ2-, ε-, and β-MnFeAl(C) exhibited a quadrupolar structure while τ -Mn50.5Fe0.5Al47C2 spectrum showed a rather complex magnetic hyperfine splitting. The interaction between Fe and Mn examined by in-field Mössbauer measurement at 10 K and 8 T showed a non-collinear magnetic structure between Fe and Mn with different canting angles at different sites. Hyperfine field of MnFeAl alloy calculated by Win2k supported both magetic properties and Mossbauer results
Yip, Chi Kin. "A catalytic architecture composed of titanium silicalite-1 and nanostructured support for oxime synthesis /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?CBME%202009%20YIP.
Повний текст джерелаDeSantis, Christopher John. "Manipulating the architecture of bimetallic nanostructures and their plasmonic properties." Thesis, Indiana University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3665584.
Повний текст джерелаThere has been much interest in colloidal noble metal nanoparticles due to their fascinating plasmonic and catalytic properties. These properties make noble metal nanoparticles potentially useful for applications such as targeted drug delivery agents and hydrogen storage devices. Historically, shape-controlled noble metal nanoparticles have been predominantly monometallic. Recent synthetic advances provide access to bimetallic noble metal nanoparticles wherein their inherent multifunctionality and ability to fine tune or expand their surface chemistry and light scattering properties of metal nanoparticles make them popular candidates for many applications. Even so, there are currently few synthetic strategies to rationally design shape-controlled bimetallic nanocrystals; for this reason, few architectures are accessible. For example, the "seed-mediated method" is a popular means of achieving monodisperse shape-controlled bimetallic nanocrystals. In this process, small metal seeds are used as platforms for additional metal addition, allowing for conformal core@shell nanostructures. However, this method has only been applied to single metal core/single metal shell structures; therefore, the surface compositions and architectures achievable are limited. This thesis expands upon the seed-mediated method by coupling it with co-reduction. In short, two metal precursors are simultaneously reduced to deposit metal onto pre-formed seeds in hopes that the interplay between two metal species facilitates bimetallic shell nanocrystals. Au/Pd was used as a test system due to favorable reduction potentials of metal precursors and good lattice match between Au and Pd. Alloyed shelled Au@Au/Pd nanocrystals were achieved using this "seed-mediated co-reduction" approach. Symmetric eight-branched Au/Pd nanocrystals (octopods) are also prepared using this method. This thesis investigates many synthetic parameters that determine the shape outcome in Au/Pd nanocrystals during seed-mediated co-reduction. Plasmonic, catalytic, and assembly properties are also investigated in relation to nanocrystal shape and architecture. This work provides a foundation for the rational design of architecturally defined bimetallic nanostructures.
Wei, Diming. "The beauty of DNA architecture : the design and applications in DNA nanotechnology /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?CBME%202009%20WEI.
Повний текст джерелаBelchi, Raphaëlle. "Architectures à base de nanostructures de carbone et TiO₂pour le photovoltaïque." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS329/document.
Повний текст джерелаPhotovoltaic is a promising renewable energy to tackle global warming and the depletion of fossil resources. The emerging field of perovskite solar cells (3rd generation photovoltaic) is very attractive because it uses abundant and easy-processing materials (low-cost technology) and provides competitive efficiencies.Still, efforts remain to be performed to develop this technology, especially concerning the improvement of efficient and reliable charge transporting electrodes. Titanium dioxide layer, commonly used for electron extraction, presents defects that limit the performance and lifetime of the perovskite solar cells.This work proposes the use of materials based on TiO₂ and carbon nanostructures to improve the electron transport and collection within the solar cells, in order to enhance the power conversion efficiency. The singular technique of laser pyrolysis, which is a continuous process of nanoparticles synthesis, was adapted to produce TiO₂/graphene nanocomposites with well-controlled properties. These materials have been characterized and integrated into perovskite solar cells that demonstrate an improved efficiency in presence of graphene.Besides, this work presents an innovating architecture based on vertically aligned carbon nanotubes for the electron collection of a perovskite solar cell. We show then the strong potential of carbon materials for optoelectronic, especially 3rd generation photovoltaic
Kong, David Sun 1979. "Nanostructure fabrication by electron and ion beam patterning of nanoparticles." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28346.
Повний текст джерелаIncludes bibliographical references (leaves 82-83).
Two modes of energetic beam-mediated fabrication have been investigated, namely focused ion beam (FIB) direct-writing of nanoparticles, and a technique for electrostatically patterning ionized inorganic nanoparticles, termed nanoxerography. A FIB has been used to directly pattern thin films of organometallic Ag-precursors down to a resolution of 100 nm. The sensitivity of the resist to 30 keV Ga+ ions was measured to be approximately 5 C/cm2. Using this technique arbitrary structures were fabricated in two and three dimensions with resistivity on the order of 1x10 4 Q-cm and 1x1 0-5 Q-cm for single- and multi-layer structures, respectively. A new unit of merit for characterizing direct-write processes, termed resistivity-dose (Q-jC/cm), has been introduced. A Nanocluster Source capable of generating a beam of charged, inorganic nanoparticles has been characterized. The relationship between power supplied to the magnetron of the source and the size of deposited clusters has been plotted. Techniques for utilizing such clusters to develop latent electrified images patterned by an electron beam (EB) have been proposed. The charge-storing characteristics of a variety of substrates such as mylar and polyimide were studied by developing EB-patterned charge images with toner particles.
David Sun Kong.
S.M.
Yuen, Mai-yan, and 袁美恩. "Semiconducting and electroluminescent cyclometalated platinum (II) complexes: from molecular functionalmaterials to supramolecular architecture and self-assemblednanomaterials." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B44758121.
Повний текст джерелаLiang, Qizhen. "Preparation and properties of thermally/electrically conductive material architecture based on graphene and other nanomaterials." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/44846.
Повний текст джерелаZhao, Teng. "Development of new cathodic interlayers with nano-architectures for lithium-sulfur batteries." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/275684.
Повний текст джерелаLudlow, James M. III. "Design and Synthesis of Terpyridine based Metallo-Supramolecular Architectures." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1444989836.
Повний текст джерелаBenamira, Messaoud. "Conducteurs mixtes nanostructurés pour les piles à combustible à oxyde solide (SOFC) : élaboration et performances de nouvelles architectures." Phd thesis, Paris 6, 2008. http://pastel.archives-ouvertes.fr/pastel-00004896.
Повний текст джерелаGu, Tang. "Modélisation multi-échelles du comportement électrique et élasto-plastique de fils composites Cu-Nb nanostructurés et architecturés." Thesis, Paris, ENSAM, 2017. http://www.theses.fr/2017ENAM0017/document.
Повний текст джерелаNanostructured and architectured copper niobium composite wires are excellent candidates for the generation of intense pulsed magnetic fields (>90T) as they combine both high strength and high electrical conductivity. Multi-scaled Cu-Nb wires are fabricated by accumulative drawing and bundling (a severe plastic deformation technique), leading to a multiscale, architectured and nanostructured microstructure exhibiting a strong fiber crystallographic texture and elongated grain shapes along the wire axis. This thesis presents a comprehensive study of the effective electrical and elasto-plastic behavior of this composite material. It is divided into three parts: electrical, elastic and elasto-plastic multiscale modeling. In order to investigate the link between the effective material behavior and the wire microstructure, several homogenization methods are applied which can be separated into two main types: mean-field and full-field theories. As the specimens exhibit many characteristic scales, several scale transition steps are carried out iteratively from the grain scale to the macro-scale. The general agreement among the model responses allows suggesting the best strategy to estimate reliably the effective electrical and elasto-plastic behavior of Cu-Nb wires and save computational time. The electrical models are demonstrated to predict accurately the anisotropic experimental data. Moreover, the mechanical models are also validated by the available ex-situ and in-situ X-ray/neutron diffraction experimental data with a good agreement
Niu, Jianbing. "Growth Mechanisms, and Mechanical and Thermal Properties of Junctions in 3D Carbon Nanotube-Graphene Nano-Architectures." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc700065/.
Повний текст джерелаMontana, garcia Juan. "Architecture multi-échelle de matériaux polymères : de l’auto-assemblage à l’assemblage forcé." Thesis, Paris, ENSAM, 2017. http://www.theses.fr/2017ENAM0060/document.
Повний текст джерелаBlock copolymers (BCP) have proven to be of great interest, especially for their ability to spontaneously self-assemble in ordered and well-defined nanostructures. Some of their macroscopic properties can be altered by physical effects such as confinement (constraining domains at molecular scale) or shear (predominant orientation of domains with anisotropic mechanical response). Here, the study of these effects over the BCP structuration is achieved by using an industrially scalable technique, nanolayer coextrusion, which allows fabrication of macroscopic films made of thousands of alternating layers with individual thickness tuned down to a few tens of nanometers. Films are then coextruded using the triblock : poly(methyl methacrylate-b-butyl acrylate-b-methyl methacrylate) and the polymers : polymethyl methacrylate, polystyrene and polycarbonate (having different interfaces) by varying weight proportions and process parameters to target different layer thicknesses. A multi-scale characterization by coupling different technics as AFM, TEM (after samples staining) and SAXS allowed the local identification of nano-domains and the better understanding of process-structures-properties relation as a result of tensile tests showing improved mechanical behavior for these films. A low thermic stability for comparable process times showed a clear influence over structuration of this kind of BCP. We have observed a change in the triblock morphology from lamellar structures, when it is a close to thermodynamic equilibrium state, to cylindrical structures within the multilayer system which is maintained over long distances indistinct of layer thickness. The well understanding of the forming process parameters to create polymer-based materials at micro- or nanoscale scale is therefore an important factor in order to control nano-structures during a large-scale production of hierarchized materials consisting of BCP, which could strongly influence their macroscopic properties
Schmitt, Thomas. "Mécanismes de dégradation de revêtements base CrN élaborés par arc-PVD : Intérêt d'une nano-architecture." Phd thesis, Ecole Centrale de Lyon, 2010. http://tel.archives-ouvertes.fr/tel-00633784.
Повний текст джерелаArndt, Grégory. "Architecture système et conception électronique de réseaux de capteurs de masse à partir de micro et nanorésonateurs." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00658843.
Повний текст джерелаCharles, Cédric. "Etude théorique et expérimentale des relations architecture - propriétés optiques de films minces d'oxyde de tungstène pulvérisés par GAD." Phd thesis, Université de Franche-Comté, 2013. http://tel.archives-ouvertes.fr/tel-01063023.
Повний текст джерелаOvalle, Robles Raquel. "Physical process in OLED architectures with transparent carbon nanotube sheets as electrodes /." 2008. http://proquest.umi.com/pqdweb?did=1663060241&sid=8&Fmt=2&clientId=10361&RQT=309&VName=PQD.
Повний текст джерелаRreza, Iva. "Designing Quantum Dot Architectures and Surfaces for Light Emitting Diodes." Thesis, 2019. https://doi.org/10.7916/d8-hd0j-as89.
Повний текст джерелаSampaio, Maria José Fernandes. "Nanostructured Architectures Based on Metal Oxides With Direct Wide Band-Gap for the Engineering of Photocatalytic Reactions." Doctoral thesis, 2016. https://hdl.handle.net/10216/100177.
Повний текст джерелаSampaio, Maria José Fernandes. "Nanostructured Architectures Based on Metal Oxides With Direct Wide Band-Gap for the Engineering of Photocatalytic Reactions." Tese, 2016. https://hdl.handle.net/10216/100177.
Повний текст джерелаSchulze, Carsten. "Magnetization Reversal in Film-Nanostructure Architectures : Magnetization Reversal in Film-Nanostructure Architectures." Doctoral thesis, 2013. https://monarch.qucosa.de/id/qucosa%3A20055.
Повний текст джерелаLu, Po Wei, and 呂柏緯. "Effect of nanostructured architecture on the enhanced optical absorption in silicon thin-film solar cells." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/59964676233803441611.
Повний текст джерела國立臺灣師範大學
光電科技研究所
100
We apply the finite difference time domain method to numerically calculate the enhanced optical absorption of three nanostructures (i.e., nanorod, nanocone, and nanolens arrays) that were decorated on the surface of 2 µm thick crystal silicon thin films. Compared with the nanorod and nanocone arrays, the nanolens array exhibits the highest power conversion efficiency. This result is mainly attributed to the natural capability of the nanolens array to optically couple incident light into in-plane guided modes, which increases the optical path of the incident photons in the long-wavelength regime. The power conversion efficiencies of the optimized nanorod, nanocone, and nanolens arrays are =17.4%, 18.8%, and 22.0%, respectively. These efficiencies correspond to enhancements of 26.1%, 36.2%, and 59.4% for the nanorod, nanocone, and nanolens arrays, respectively, compared with a planar Si thin-film with a standard quarter-wavelength antireflection layer. These findings show promises for the nanostructured design of silicon thin-film solar cells that exhibit enhanced optical absorption.