Papers by Keyword: Electrochromic

Abstract: A two-stage hydrothermal method was used to prepare rapid-switching electrochromic WO₃/ZnO composite electrodes. The morphology of the nanorods was altered by changing the precursor concentration. A higher precursor concentration inhibited the growth of crystals and declined the crystallinity of nanorods. Nanorods with a diameter of 48 nm, height of 92.5 nm, and transmittance greater than 80% were grown when the precursor concentration in the second step was 1.5 times that in the first step. The electrochromic electrode demonstrated rapid coloring and bleaching speeds (5 and 0.8 s, respectively), which were faster than those of the electrode prepared using the one-stage process.

Abstract: Cobalt oxide thin film (Co₃O₄) has been prepared from cobalt chloride with distilled water on conducting glass substrates Fluorine doped Tin Oxide (FTO) at (400^ºC) by depositing chemical spray pyrolysis, with thickness (200 nm). The structural properties are studied by XRD. Also, optical properties and electrical properties of Co₃O₄ thin film are studied by UV spectroscopy and Cyclic voltammetry (CV) respectively. The effects of gamma irradiation on optical properties are also examined. XRD results showed that the film was polycrystalline with cubic structure having preferred orientation (111). The as-prepared Co₃O₄ film exhibits a noticeable EC behaviour with reversible colour which changes from dark grey to pale yellow with bleaching time (55 s) and colouring time (40 s). After irradiation, the optical properties showed that as the transmittance decrease leads to decrease the direct optical band gap from (3.68eV) to (3.55eV)

Abstract: Tungsten oxide (WO₃) is a transition metal oxide with a wide range of applications such as displays, rear-view mirrors, electrochromic (EC) smart windows and gas sensors. Many techniques were adopted for the fabrication of WO₃, namely magnetron sputtering, spray pyrolysis and sol-gel synthesis techniques. In this work, WO₃ films were deposited on indium tin oxide (ITO) coated glasses by sol-gel spin-coating method. The film thickness was varied by depositing different number of layers. The WO₃ film thickness and optical transmittance were determined using step profilometer and ultraviolet-visible (UV-Vis) spectrophotometer, respectively. WO₃ film thicknesses increased from 38 nm to 606 nmwith increasing number of deposited layers.The optical transmittance of the WO₃ films in visible range decreased with increasing film thickness. The optical transmittance were at least 70 % up to 10 deposited layers.WO₃is a promising EC material in the application ofEC devices (ECDs).The application of WO₃ in the EC devices will be discussed.

Abstract: The effect of annealing temperature on the electrochromic properties of the tantalum oxide (TaO) thin films deposited on silicon wafer (100) and indium tin oxide (ITO) substrates by dc reactive magnetron sputtering was investigated. The films were annealed at 300, 400 and 500 °C in vacuum for 2 hour. The crystalline structure, morphology, optical properties and electrochromic properties of as-deposited and annealed film were deduced by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), spectroscopic ellipsometry and ultraviolet–visible (UV–vis) spectrophotometery, respectively. The reflective index of TaO thin films increased with increasing annealing temperature. The result indicated that the annealed TaO thin film showed better performance than the as-deposited film.

Abstract: Tungsten oxide (WO₃) nanorods were successfully grown at low temperature of 90 °C by seeded growth hydrothermal reaction. The effect of sodium chloride (NaCl) addition on nanorod aggregation was studied. The hydrothermal reaction was conducted at various reaction periods (16-24 h). Monoclinic WO₃ nanorods started to grow from the seeds after 18 h of hydrothermal reaction and more vertical nanarods were formed after 20 h of treatment. The addition of NaCl successfully reduced the aggregation of nanorods. Cyclic voltammetry (CV) was performed to measure the electrochromic properties of the WO₃ nanorods. WO₃ nanorods grown with NaCl showed faster intercalation and de-intercalation processes due to less nanorods aggregation.

Abstract: Electrochromic composite film consisting of TiO₂, chitosan (CS) and carbon nanotubes (CNTs) were fabricated on quartz and FTO substrates by the layer-by-layer self-assembly method (LbL). The multilayer film was characterized by UV-vis spectrum, scanning electron microscopy (SEM), cyclic voltammetry (CV) and chronoamperometric (CA) and in situ spectral electrochemicalmeasurements. The composite material shows high electrochromic performance, with the optical contrast of 11.5% and coloration efficiency of 21.7 cm²/C at 800 nm. The results indicate great promise for the TiO₂-based film as a potential material in electrochromic devices.

Abstract: Nickel oxide thin films were electrodeposited onto ITO glass substrates by a two-step method: i) electrodeposition of nickel and ii) further thermal oxidation at 300 °C. The surface morphology of the NiO thin films was characterized by atomic force microscopy (AFM) and the transmittance in the coloured and bleached states were analysed using UV-Visible (UV-Vis) spectroscopy. The electrochemical properties of NiO films were measured in 1 M KOH electrolyte by cyclic voltammetry (CV). A good optical quality and highly improved electrochromic performances NiO film was successfully synthesized.

Abstract: Co₃O₄/NiO nanocomposite films were electrochemically synthesized on a ITO surface. The Co₃O₄/NiO nanocomposite films were characterized by energy-dispersive X-ray analysis (EDS) and scanning electron microscopy (SEM). The electrochromic properties of Co₃O₄/NiO nanocomposite films are investigated in an aqueous alkaline electrolyte (0.1M KOH) by means of transmittance, cyclic voltammetry (CV) and chronoamperometry (CA) measurements. The Co₃O₄/NiO nanocomposite films exhibit a noticeable electrochromism with reversible color changes, and fast switching speed (4.1 s and 3.6 s).

Abstract: As a kind of transition metal oxides, WO₃ has been widely used due to its excellent performance in Electrochromism. This article introduces properties and mechanism of Electrochromism of WO₃ films according to the literature of recent years, and offers a summary introduction of preparation of WO₃ films. Additionally, the problems on application and improvement in future of WO₃ films are discussed.

Abstract: Electrochemical synthesis in a room temperature ionic liquid, 1-butyl-3-methyl-imidazolium tetrafluoroborate ([BMIBF₄), has been used to prepare electrochromic poly (3-bromothiophene) (PBrT). The PBrT films were characterized by fourier-transform infrared spectroscopies (FTIR) and scanning electron microscopy (SEM). Electrochemistry properties of the prepared film was characterized by cyclic voltammetry. Spectroelectrochemistry and electrochromic properties of the PBrT films were characterized using various experiment techniques in [BMIBF₄. The thin films were red at its neutral state. After oxidization of the PBrT films, the films underwent reversible change to the blue.