Electrochromic Properties of Tungsten Oxide Nanoparticles Films Prepared by the Filtration and Transfer Method PDF Download
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Author: Youssef Mosaddeghian Golestani
Publisher:
ISBN:
Category :
Languages : en
Pages : 101
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Electrochromic tungsten oxide nanostructures were prepared from tungsten oxide nanoparticles for the first time by the filtration and transfer technique. This novel and facile method for film preparation presents many advantages that include the possibility to obtain nanoparticle films with various porosities and compositions. The films obtained in the present work exhibited indeed porous structures and were generally composed of a mixture of nanoparticles. When the amount of the nanoparticles in the suspensions increased, we observed thicker films with higher coverage densities. Films prepared at room temperature exhibited very good electrochromic properties. It was found that annealing at 500oC increases the film stability and life time. Using cyclic voltammetry, fast diffusion behaviour (D of the order of 10-6 cm2s-1) for proton insertion/extraction has been observed. Moreover, fast switching response time (less than a second) during the bleaching process due to the rapid decay of the anodic current during chronoamperometry was also noted. The coloration efficiency for such devices was about 20 cm2C-1. The coloration of the films is associated with the number of color centers and depends on the number of inserted charges. However, we have shown that good optical reversibility does not necessarily need fast electrochemical kinetics. Finally, the effect of high applied potentials on the films was investigated, followed by an analysis of the electronic properties of the films.
Author: Youssef Mosaddeghian Golestani
Publisher:
ISBN:
Category :
Languages : en
Pages : 101
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Book Description
Electrochromic tungsten oxide nanostructures were prepared from tungsten oxide nanoparticles for the first time by the filtration and transfer technique. This novel and facile method for film preparation presents many advantages that include the possibility to obtain nanoparticle films with various porosities and compositions. The films obtained in the present work exhibited indeed porous structures and were generally composed of a mixture of nanoparticles. When the amount of the nanoparticles in the suspensions increased, we observed thicker films with higher coverage densities. Films prepared at room temperature exhibited very good electrochromic properties. It was found that annealing at 500oC increases the film stability and life time. Using cyclic voltammetry, fast diffusion behaviour (D of the order of 10-6 cm2s-1) for proton insertion/extraction has been observed. Moreover, fast switching response time (less than a second) during the bleaching process due to the rapid decay of the anodic current during chronoamperometry was also noted. The coloration efficiency for such devices was about 20 cm2C-1. The coloration of the films is associated with the number of color centers and depends on the number of inserted charges. However, we have shown that good optical reversibility does not necessarily need fast electrochemical kinetics. Finally, the effect of high applied potentials on the films was investigated, followed by an analysis of the electronic properties of the films.
Author: 張哲揚
Publisher:
ISBN:
Category :
Languages : en
Pages : 99
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Author:
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ISBN:
Category :
Languages : en
Pages :
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Xiv, 114 leaves : ill. ; 30 cm.
Author: Afaf Almoabadi
Publisher:
ISBN:
Category :
Languages : en
Pages : 92
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ABSTRACT Electrochromic Properties of Vanadium Pentoxide Nanostructured Thin Films Afaf Almoabadi The focus of this work is the improvement of the electrochromic properties of vanadium pentoxide thin films in order to expand its use. Indeed, because of its rather poor electrochromic properties, until now, vanadium pentoxide has only been used as a storage material in an electrochromic device, in conjunction with tungsten oxide, molybdenum oxide etc. To this purpose, vanadium pentoxide thin films were prepared under different conditions and characterized by using optical and electrochemical methods. Films were deposited on indium tin oxide (ITO) substrates by dip-coating at both room- and sub-zero temperature (-100C) and porosity in the sol-gel prepared vanadium pentoxide film was created by using templating methods. The morphology, optical and electrochromic properties of the macro- and mesoporous films, prepared in the presence of structure-directing agents such as polystyrene microspheres and triblock copolymer, have been compared with those of dense films. By using various methods to remove the template material, it was shown that the morphology of the vanadium pentoxide film can be controlled and new nanostructures can be created. The transformation of the lamellar into a nanorod structure, observed when the film is heated at 425-500◦C for several hours, resulted in the development of an elegant method for the synthesis of vanadium oxide nanostructures. The electrochromic performance of the nanorods prepared through the thermal treatment was found to be superior to that of the vanadium pentoxide with the layered structure, especially in the near-infrared region, demonstrating their potential for electrochromic applications. The structure, morphology, optical and electrochromic properties of dense and porous vanadium oxide films, coated at low temperature were also determined and compared to those of the corresponding films, deposited under room-temperature conditions. The results indicated that in the films coated at -100C, a residual compressive stress exists that originates from a non-uniformity in depth of the film, most probably, due to the formation of micro voids during the deposition. The micro voids are preserved during the heat-treatment of the films. The "micro void" morphology was found to account for the considerably improved electrochromic properties of the sub-zero dip-coated films. Low-temperature coated films, heated at 4500C for several hours, undergo the transformation from a layered to a highly uniform nanorod structure with important potential optoelectronic applications. The overall aim of this work is thus to evaluate how the morphology of vanadium pentoxide thin films is instrumental in obtaining a material with a high lithium ion intercalation capacity. With an appropriate morphology, the performance of vanadium oxide as electrochromic material and as cathode in lithium ion batteries can be improved significantly. For this purpose, both layered (dense and porous) and nanorod films were prepared and characterized. Scanning electron microscopy, cyclic voltammetry and electrical impedance spectroscopy measurements were used for the characterization of the different V2O5 films.
Author: Y. Djaoued
Publisher:
ISBN:
Category :
Languages : en
Pages : 8
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Author: Shona Margaret Christie
Publisher:
ISBN:
Category :
Languages : en
Pages : 166
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Author: Diederik Depla
Publisher: Springer Science & Business Media
ISBN: 3540766642
Category : Technology & Engineering
Languages : en
Pages : 584
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Book Description
In this valuable work, all aspects of the reactive magnetron sputtering process, from the discharge up to the resulting thin film growth, are described in detail, allowing the reader to understand the complete process. Hence, this book gives necessary information for those who want to start with reactive magnetron sputtering, understand and investigate the technique, control their sputtering process and tune their existing process, obtaining the desired thin films.
Author: Alex Miller
Publisher:
ISBN:
Category : Electrochromic devices
Languages : en
Pages : 134
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The goal of this work was to fabricate electrochromic devices made with pulsed laser deposited tungsten oxide films and evaluate the effects of material properties on device performance. The oxide films were deposited in O2 atmospheres from 10-3 - 10-1 mbar on ITO/glass substrates between room temperature (RT) and 450 °C. A pulsed KrF laser operating at 248 nm was used to ablate the WO3 target. XRD analysis showed amorphous native films for RT depositions and orthorhombic poly-crystalline films deposited at 450 °C. UV-Vis spectroscopy showed transparent films deposited at 10-1 mbar and opaque films for lower chamber pressures. For depositions at RT, atomic force microscopy revealed ultra-smooth surfaces for films deposited at 10-2 mbar and disordered/porous surface morphology for films deposited at 10-1 mbar. With the substrate temperature at 450 °C, the topography had visible grain patterns. IV measurements were done on films grown at different chamber pressures. Preliminary devices were constructed by sandwiching a drop of 2.0-M HCl between the oxide/ITO/glass and a top ITO/glass electrode. Cyclic voltammetry was used to automate the bias potential, determine charge insertion, and investigate response time and the effects of repeated cycles. Devices constructed with opaque oxygen-deficient or poly-crystalline tungsten oxide films displayed poor electrochromism while devices constructed with transparent amorphous WO3 films (deposited at 10-1 mbar and RT) exhibited electrochromic properties including a large optical modulation (76.1 %T at 705 nm) and a coloration efficiency of 11 cm2/C.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 9
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Electrochromic windows offer the ability to dynamically change the transmittance of a glazing. With the appropriate sensor and controls, this smart window can be used for energy regulation and glare control for a variety of glazing applications. The most promising are building and automotive applications. This work covers the use of sol-gel deposition processes to make active films for these windows. The sol-gel process offers a low-capital investment for the deposition of these active films. Sol-gel serves as an alternative to more expensive vacuum deposition processes. The sol-gel process utilizes solution coating followed by a hydrolysis and condensation. In this investigation the authors report on tungsten oxide and nickel oxide films made by the sol-gel process for electrochromic windows. The properties of the sol-gel films compare favorably to those of films made by other techniques. A typical laminated electrochromic window consists of two glass sheets coated with transparent conductors, which are coated with the active films. The two sheets are laminated together with an ionically conductive polymer. The range of visible transmission modulation of the tungsten oxide was 60% and for the nickel oxide was 20%. The authors used the device configuration of glass/SnO2:F/W03/polymer/Li{sub Z}NiO(subscript x)H{sub y}/SnO2:F glass to test the films. The nickel oxide layer had a low level of lithiation and possibly contained a small amount of water. Lithiated oxymethylene-linked poly(ethylene oxide) was used as the laminating polymer. Commercially available SnO2:F/glass (LOF-Tec glass) was used as the transparent conducting glass. The authors found reasonable device switching characteristics which could be used for devices.
Author: Y. Djaoued
Publisher:
ISBN:
Category :
Languages : en
Pages : 10
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