共查询到20条相似文献,搜索用时 31 毫秒
1.
There is a considerable interest in the research and development of materials and devices, that can be used for optical switching of large-scale glazings. Several potential switching technologies are available for glazings, including those based on electrochromic, thermochromic and photochromic phenomena. One of the most promising technologies for optical switching devices is electrochromism (EC). In order to improve the electrochromic properties of tungsten oxide, we have investigated the effect of phosphorous insertion on the electrochromic behavior of oxide films prepared by the sol–gel process.The kinetics and thermodynamics of electrochemical intercalation of lithium into LixWO3 and LixWO3:P films prepared by the sol–gel process were investigated. The standard Gibbs energy for lithium intercalation was calculated. The chemical diffusion coefficients, D, of lithium intercalation into oxide, were measured by galvanostatic intermittent titration technique (GITT), as functions of the depth of lithium intercalation. 相似文献
2.
Danilo Dini Stefano Passerini Bruno Scrosati Franco Decker 《Solar Energy Materials & Solar Cells》1999,56(3-4)
The mechanical effects of the intercalation processes in electrochromic WO3 thin films are reported here and discussed. In particular the electrochemical insertion of H, Li and Na ions in WO3 was studied by means of laser beam deflection method (LBDM). Linear changes of WO3 stress were observed for small amounts of the inserted charge and linearity was always associated with a reversible mechanical behavior of thin films. An explanation in terms of homogeneity of the insertion is given. An analogous trend was also verified in the absorbance vs. charge curves. As a consequence the constancy of the electrochromic efficiency values for the three different ions was found. In this way it was possible to determine a full reversible behavior for MxWO3 in the composition range 0x0.2. The onset of new phases formation when x exceeded previous upper limit, was observed during Li and Na intercalation. Such transitions brought about the loss of optical and mechanical reversibility. During prolonged hydrogen insertion a reversible slope inversion occurred in stress curve so that it was necessary to take into account different possible mechanisms of the WO3 electrochromic reaction. 相似文献
3.
Chia-Ching Liao Fu-Rong Chen Ji-Jung Kai 《Solar Energy Materials & Solar Cells》2007,91(14):1282-1288
A new nanocomposite WO3 (NWO) film-based electrochromic layer was fabricated by a spray and electroplating technique in sequence. An indium–tin oxide (ITO) nanoparticle layer was employed as a permanent template to generate the particular nanostructure. The structure and morphology of the NWO film were characterized. The optical and electrochromic properties of the NWO films under lithium intercalation are described and compared to the regular WO3 film. The NWO films showed an improved cycling life and an improved contrast with compatible bleach-coloration transition time, owing to the larger reactive surface area. The nanocomposite WO3 film-based electrochromic device (NWO-ECD) was also successfully fabricated. Most importantly, the NWO film can be prepared on a large scale directly onto a transparent conductive substrate, which demonstrates its potential for many electrochromic applications, especially, smart windows, sunroof and displays. 相似文献
4.
We have prepared and tested integrated low-emittance–electrochromic devices using ZnS/Ag/ZnS coatings as transparent electrodes and WO3 films as electrochromic layers. These devices exhibit adequate coloration and can withstand more than 1000 bleaching-coloration cycles, provided that the metal layer is protected from the liquid electrolyte by a combination of thick dielectric films (ZnS/WO3). We have also predicted the optimum configuration of the WO3/ZnS/Ag/ZnS/Glass stack that maximizes transmission in the visible. Integration of low emittance and electrochromic films into one device could improve the performance and reduce the cost of electrochromic windows. 相似文献
5.
The characterization of electrochemical behavior of electrochromic intercalation device based on cobalt oxide thin film was carried out using the step potential excitation method. A method based on generating plots of current density as a function of passed charge has been applied for characterization of electrochromic cobalt oxide thin films using an aqueous KOH electrolyte. The device resistance and the intercalation capacity of the material are calculated. Dynamic built-in potential estimated from step potential experiment and plots of the built-in potential as function of the passed charge, Vbi(ΔQ), are generated for intercalation process. The intercalation efficiency curve is obtained to confirm the nature of energy distribution of intercalation sites in electrochromic cobalt oxide. 相似文献
6.
Chia-Ching Liao Fu-Rong Chen Ji-Jung Kai 《Solar Energy Materials & Solar Cells》2006,90(7-8):1147-1155
A simple method was developed to fabricate tungsten oxide (WO3−x) nanowires based electrochromic devices. The WO3−x nanowires are grown directly from tungsten oxide powders in a tube furnace. The WO3−x nanowires have diameters ranging from 30 to 70 nm and lengths up to several micrometers. The WO3−x nanowires based device has short bleach-coloration transition time and can be grown on a large scale directly onto an ITO-coated glass that makes it potential in many electrochromic applications. The structure, morphology, and composition of the WO3−x nanowires were characterized using the scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and energy-dispersive spectrometer. The optical and electrochromic performance of the nanowires layer under lithium intercalation was studied in detail by UV–VIS–NIR spectroscope and cyclic voltameter. 相似文献
7.
Tungsten oxide (WO3), vanadium and nickel-hydroxide (VOxHy and NiOxHy)-films were evaporated on glass and polymeric substrates covered with indium-tin oxide (ITO). Films of nickel-oxide (NiOx) were reactively sputtered from a nickel target. In order to obtain electrochromic devices the WO3 film was used as one electrode and with a polymeric solid state electrolyte (PSSE) glued to each of the other films which served as different counter electrodes. The films for themselves and the complete devices were investigated by optoelectrochemical and other methods. The most stable device was the WO3–VOxHy system which even improved the electrochromic properties after 3×104 cycles. 相似文献
8.
M. S. Burdis J. R. Siddle R. A. Batchelor J. M. Gallego 《Solar Energy Materials & Solar Cells》1998,54(1-4)
Thin films of V0.50Ti0.50Ox have been deposited by RF sputtering from metallic targets. Their use as potential counterelectrodes in electrochromic devices has been investigated. It is found that although they are slightly yellow looking in transmission, the films can reversibly store relatively large amounts of charge, whilst showing a reasonably low electrochromic colouration efficiency. The electrochemistry of V0.50Ti0.50Ox is found to be simple, in fact rather similar to that of WO3, making it an almost ideal material to use in such a variable transmission device. 相似文献
9.
Solid hybrid polyelectrolyte with high performance in electrochromic devices: Electrochemical stability and optical study 总被引:1,自引:1,他引:0
Flavio L. Souza Michel A. Aegerter Edson R. Leite 《Solar Energy Materials & Solar Cells》2007,91(19):1825-1830
This paper presents a high-stability, single-phase hybrid polyelectrolyte (SPHP) applied in a large EC device (5×10 cm2) using WO3 (electrochromic) and CeO2–TiO2 (counter-electrode–ion storage) electrodes, both produced by Leibniz—Institut of New Materials (Leibniz—INM, Germany). The electrochromic device exhibited excellent color and bleach reversibility, high coloration efficiency (>35 cm2/C) from the first cycle up to more than 60,000 CA cycles, and a maximum constant rate of deintercalation/intercalation (Oout/Qin=1). Its remarkable behavior and high stability render this material an excellent candidate for application in electrochromic devices. 相似文献
10.
Electrochromic devices have increasing application in large-area display devices, switchable mirrors and smart windows. A variety of vacuum deposition technologies have been used to make electrochromic devices. The sol–gel process offers an alternative approach to the synthesis of low-cost, high-quality electrochromic device layers. This paper discusses the developments in sol–gel-deposited electrochromic films and a prototype all sol–gel device with switching from 80% to 50% (550 nm). The sol–gel process involves the formation of oxide networks upon hydrolysis–condensation of alkoxide precursors. In this study, we cover sol–gel-deposited oxides of WO3, TiO2, Nb2O5, V2O5, Ni(OH)2, Co(OH)2 and CuOx. The coloration reaction voltammetry and spectral optical properties are presented for selected films. 相似文献
11.
This paper reports enhanced electrochromic properties in the infrared region, so-called IR, and in particular, in the middle wavelength (MW: 3–5 μm) and long wavelength (LW: 8–12 μm), of radio frequency sputtered (RFS) WO3 thin films, thanks to a careful optimization of the deposition conditions, namely the duration of deposition (<240 min), the substrate nature (FTO or Au), and the chamber pressure (15 and 45 mT). Significant modulations in reflectance (as high as 73% in the MW) and in the apparent temperature (up to 35 °C) between the inserted state and the deinserted one, for WO3 thin films cycled in H3PO4 liquid electrolyte, are reported. Such performances correspond to a variation in emissivity of at least 40% as required for military applications. Finally, coupling both modelling and experimental approaches, first trends on the incorporation of the WO3 single layer in full electrochromic devices (ECDs) are discussed considering mainly an all-solid-state device configuration. 相似文献
12.
Smart windows offer an opportunity to reduce energy consumption. However, the use of multiple optical elements, such as low emittance coatings and electrochromic devices, is detrimental to the luminous transmittance of these high performance windows. Although the addition of antireflective coatings has helped to reduce this problem, some elements, such as high index of refraction materials still give rise to loss of light. We show that replacing the single WO3 active coating, the main component of an electrochromic device, by an appropriately designed electrochromic interference filter can significantly increase the transmittance. This active filter is based on a stack of dense and porous WO3 layers. We first study the effect of porosity on the physical and electrochromic properties of WO3 prepared by radio frequency magnetron sputtering. We demonstrate that the overlying dense coating does not inhibit the coloration of the underlying porous coating. The best performing films are combined into a 27 layer quarter-wave interference filter which is shown to cycle between bleached and colored states, while providing attractive transmission. Finally, we discuss various filter designs which can increase the transmission of an electrochromic device in its bleached state, as well as the potential use of active filters for optical security devices possessing two levels of authentication. 相似文献
13.
E. Masetti M. L. Grilli G. Dautzenberg G. Macrelli M. Adamik 《Solar Energy Materials & Solar Cells》1999,56(3-4)
Tungsten trioxide is the most accepted material for electrochromic devices. In the work thin films of WO3 were deposited by reactive r.f. sputtering of both metallic (W) and ceramic (WO3) targets to study the correlation between the electrochromic properties and the structures of the films. Samples were grown at different pressures of Ar+O2 in order that the energy regimes of the sputtered particles on the condensing surface could be set either below or above the thermalisation diffusion limit. Lithium ions were intercalated in the films in an aprotic electrolyte and the colouring/bleaching behaviour as a function of the intercalated amount of lithium was detected in the 1st and 10th cycle. From these measurements, the electrochromic properties of the films were worked out. The optical and morphological characteristics were analysed respectively, by spectrophotometric and X-TEM measurements. The amount of water present in the films, detected by IR spectroscopy, turned out to be well correlated to the film morphology and also to the porosity. 相似文献
14.
Ye Yonghong Zhang Jiayu Gu Peifu Tang Jinfa 《Solar Energy Materials & Solar Cells》1997,46(4):349-355
In this report, a simple WO3 dry lithiation is proposed for fabrication of all-solid-state electrochromic devices and characterized completely by X-ray photoelectron spectroscopy and electrochemical method. Lithiation is carried out by electron-beam evaporation of metal lithium, and the lithiated films have different components and electrochromic properties with different lithiation degrees. It is found that if Li/W ratio is less than 0.25, tungsten bronze LixW03 is formed and the lithiated by wet method. Finally, a lithium-based all-solid-state electrochromic device with proper lithiation degree is fabricated using this dry method. 相似文献
15.
R. Sivakumar P. Manisankar M. Jayachandran C. Sanjeeviraja 《Solar Energy Materials & Solar Cells》2006,90(15):2438-2448
Now-a-days a large number of extensive research has been focused on electrochromic oxide thin films, owing to their potential applications in smart windows, low cost materials in filters, low cost electrochemical devices and also in solar cell windows. Among the varieties of electrochromic transition metal oxides, the molybdenum oxide (MoO3) and tungsten oxide (WO3), form a group of predominant ionic solids that exhibit electrochromic effect. The electrochromic response of these materials are aesthetically superior to many other electrochromic materials, because WO3 and MoO3 absorb light more intensely and uniformly. In the present case, we have discussed about the electrochromic behaviour of electron beam evaporated MoO3 films. Moreover, the MoO3 film can also be used as a potential electro-active material for high energy density secondary lithium ion batteries; because it exhibits two-dimensional van der Waals bonded layered structure in orthorhombic phase. The films were prepared by evaporating the palletized MoO3 powder under the vacuum of the order of 1 × 10−5 mbar. The electrochemical behaviour of the films was studied by intercalating/deintercalating the K+ ions from KCl electrolyte solutions using three electrode electrochemical cell by the cyclic-voltammetry technique. The studies were carried out for different scanning rates. The films have changed their colour as dark blue in the colouration process and returns to the original colour while the bleaching process. The diffusion coefficient values (D) of the intercalated/deintercalated films were calculated by Randle's Servcik equation. The optical transparency of the coloured and bleached films was studied by the UV–Vis–NIR spectrophotometer. The change in bonding assignment of the intercalated MoO3 films was studied by FTIR spectroscopic analysis. A feasible study on the effect of substrate temperatures and annealing temperatures on optical density (OD) and colouration efficiency of the films were discussed and explored their performance for the low cost electrochemical devices. 相似文献
16.
With in situ micro-Raman measurements during the electrochemical reduction of WO3 thin films, the influence of the intercalated cation (H+/Li+) and an addition of water to the aprotic lithium electrolyte was investigated. The Raman spectra of lithium bronzes LixWO3 show two main results: (i) the intercalation of hydrogen can be clearly distinguished in situ from the intercalation of lithium with this technique and (ii) even with an addition of 500 ppm of water to the lithium electrolyte no hydrogen intercalation was observed. 相似文献
17.
An all-solid-state electrochromic (EC) device based on NiO/WO3 complementary structure and solid polyelectrolyte was manufactured for modulating the optical transmittance. The device consists of WO3 film as the main electrochromic layer, single-phase hybrid polyelectrolyte as the Li+ ion conductor layer, and NiO film as the counter electrochromic layer. Indium tin oxide- (ITO) coated glass was used as substrate and ITO films act as the transparent conductive electrodes. The effective area of the device is 5×5 cm2. The device showed an optical modulation of 55% at 550 nm and achieved a coloration efficiency of 87 cm2 C−1. The response time of the device is found to be about 10 s for coloring step and 20 s for bleaching step. The electrochromic mechanism in the NiO/WO3 complementary structure with Li+ ion insertion and extraction was investigated by means of cyclic voltammograms (CV) and X-ray photoelectron spectroscopy (XPS). 相似文献
18.
S.N. Alamri 《Solar Energy Materials & Solar Cells》2009,93(9):1657-1662
The purpose of this paper was to investigate the variation in temperature of electrochromic devices under direct solar radiation and to compare the results with double-glazed glass. The devices consisted of a V2O5 layer as an ion storage film and a WO3 layer as an electrochromic layer. The V2O5 and WO3 films were prepared by thermal and electron beam evaporation, respectively. The optical properties and structures of these films were investigated. Both the ion storage film and the electrochromic layer were amorphous. The optical absorption was caused by a direct-forbidden transition in V2O5 and by an indirect-allowed transition in WO3. The maximum temperatures under solar radiation were measured for colored and bleached devices, double glass and air, they were found to be approximately 63, 63, 53 and 36 °C, respectively. The rates of increasing temperature to the incident power density for colored, bleached devices and double glass were 0.051, 0.049 and 0.041 °C/(W/m2), respectively. 相似文献
19.
《Solar Energy Materials & Solar Cells》1999,56(3-4)
Laminated electrochromic (EC) devices are becoming increasingly important for making “smart” windows and switchable displays. Mostly, polymeric Li+ ionic conductors in combination with vacuum deposited active electrochromic and counter-electrode films are used. In this paper we report on the development of all sol–gel EC devices, that is, those where all three internal layers are prepared via the sol–gel route, including the ionically conductive inorganic–organic hybrid (ormolyte). The electrochemical and optical properties of EC devices are presented and the cycling stability and reversibility of their optical modulation assessed. The results show that WO3/ormolyte/SnO2 : Mo, WO3/ormolyte/SnO2 : Sb, WO3/ormolyte/SnO2 : Sb : Mo, Nb2O5/ormolyte/SnO2 : Sb : Mo and WO3/ormolyte/LiCo-oxide exhibit a transmission modulation dependent on the thickness of the active electrochromic and counter-electrode films and the thickness of the ormolyte layer. Electrochemical and optical properties of individual films are described and correlated with the stability of the all sol–gel EC devices. 相似文献
20.
Jesús M. Ortega Arturo I. Martínez Dwight R. Acosta Carlos R. Magaa 《Solar Energy Materials & Solar Cells》2006,90(15):2471-2479
Transparent conductive and WO3 electrochromic thin films were deposited by spray pyrolysis technique. The films were deposited using solutions of WCl6 in dimethylformamide on SnO2:F (FTO) substrates with different sheet resistances. Noticeable effects of substrate on structural, morphological and optical properties of the WO3 films and on its electrochromic behavior are presented and discussed. Hexagonal and monoclinic WO3 structures were obtained on amorphous glass substrates; also the monoclinic structure on polycrystalline FTO substrates was obtained. Cyclic structural changes during the colored and blanched states were found from XRD and electron diffraction result analysis: The hydrogen tungsten bronze in the tetragonal phase after the hydrogen extraction change to the original WO3 monoclinic phase. 相似文献