Browsing by Author "Jiao, Z."

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    A complementary electrochromic device with highly improved performance based on brick-like hydrated tungsten trioxide film
    (American Scientific Publishers, 2012) Jiao, Z.; Wang, J.; Ke, L.; Sun, X. W.; Demir, Hilmi Volkan
    Uniform and well adhesive nanostructured hydrated tungsten trioxide (3WO 3•H 2O) films were grown on fluorine doped tin oxide (FTO) substrate via a facile and template-free crystal-seed-assisted hydrothermal method by addition of ammonium sulfate ((NH 4) 2SO 4) and hydrogen peroxide (H 2O 2). X-ray diffraction (XRD) studies indicated that the films are of orthorhombic structure. Scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) analysis showed that the film was composed of brick-like nanostructures with a preferred growing direction along (002). The influence of seed layer, (NH 4) 2SO 4 and H 2O 2 on the products were also studied. The film showed good cyclic stability, comparable switching speed and coloration efficiency (30.1 cm 2 C -1). A complementary electrochromic device based on the film and Prussian blue depicted highly improved color contrast, coloration/bleaching response (1.8 and 3.7 s respectively) and coloration efficiency (164.6 cm 2 C -1).
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    ItemOpen Access
    Efficient synthesis of plate-like crystalline hydrated tungsten trioxide thin films with highly improved electrochromic performance
    (Royal Society of Chemistry, 2011) Jiao, Z.; Wang, X.; Wang, J.; Ke, L.; Demir, Hilmi Volkan; Koh, T. W.; Sun, X. W.
    Plate-like hydrated tungsten trioxide (3WO(3)center dot H(2)O) films were grown on a fluorine doped tin oxide (FTO) coated transparent conductive substrate via an efficient, facile and template-free hydrothermal method. The film exhibited a fast coloration/bleaching response (t(c90%) = 4.3 s and t(b90%) = 1.4 s) and a high coloration efficiency (112.7 cm(2) C(-1)), which were probably due to a large surface area.
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    Electrochromic properties of nanostructured tungsten trioxide (hydrate) films and their applications in a complementary electrochromic device
    (Elsevier, 2011-12-26) Jiao, Z.; Wang, J.; Ke, L.; Liu, X.; Demir, Hilmi Volkan; Yang, M. F.; Sun, X. W.
    Orthorhombic hydrated tungsten trioxide (3WO(3)center dot H2O) films consisted of nanosticks and nanoparticles were prepared on fluorine doped tin oxide (FTO)-coated substrate by a facile and template-free hydrothermal method using ammonium acetate (CH3COONH4) as the capping agent. Irregular nanobrick films were obtained without capping agent. Due to the highly rough surface, the nanostick/nanoparticle film depicts faster ion intercalation/deintercalation kinetics and a greater coloration efficiency (45.5 cm(2)/C) than the nanobrick film. A complementary electrochromic device based on the nanostick/nanoparticle 3WO(3)-H2O film and Prussian blue (PB) was assembled. As a result, the complementary device shows a higher optical modulation (54% at 754 nm), a larger coloration efficiency (151.9 cm(2)/C) and faster switching responses with a bleaching time of 5.7 s and a coloring time of 1.3 s than a single 3WO(3).H2O layer device, making it attractive for a practical application.
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    A fast-switching light-writable and electric-erasable negative photoelectrochromic cell based on Prussian blue films
    (Elsevier, 2011) Jiao, Z.; Song, J. L.; Sun, X. W.; Liu, X. W.; Wang, J. M.; Ke, L.; Demir, Hilmi Volkan
    We report a fast-switching negative photoelectrochromic cell composed of a dye-sensitized nanocrystalline TiO2 electrode and Prussian blue counter electrode sandwiching a LiI electrolyte. The cell can be bleached under illumination with shorted TiO2 and Prussian blue electrodes, and re-colored by applying an appropriate external voltage. The photo-bleaching and electric-coloring processes are fast and reversible. A maximum absorbance modulation of 0.44 recorded at 700 nm is obtained between bleached and colored states for the cell when the PB film's thickness is 452 nm. Illuminated under different levels of light intensity or durations of time, the shorted cell shows adjustable optical absorption from 470 to 840 nm. The in-situ transmittance response depicts that the photo-bleaching response is 6.2 s for 70% transmittance change under 100 mW/cm(2) illumination in short circuit configuration, and the re-coloration time is about 600 ms under 2 V bias recorded at 780 nm, with an electrochromic coloration efficiency of 103.4 cm(2)/C. The cell shows a good reversible stability and can be potentially applied in erasable displays.
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    Tailoring insoluble nanobelts into soluble anti-UV nanopotpourris
    (Royal Society of Chemistry, 2011) Wang, J.; Sun, X. W.; Jiao, Z.; Khoo, E.; Lee, P. S.; Ma, J.; Demir, Hilmi Volkan
    Soluble, transparent and anti-UV nanopotpourris have been prepared by tailoring long nanobelts. The strains and layered structures facilitate the breaking of the as-synthesized nanobelts under an applied mechanical action. The developed tailoring process of nanobelts is a general top-down secondary processing of layered nanostructures at the nanoscale level, which can be expended to the modifications of layered nanowires, nanotubes and hierarchical nanostructures. By tailoring, the size, morphology and solubility are modified, which may open up an area of advanced processing of nanomaterials and hint at some potential applications. Because of the excellent solubility of the tailored nanopotpourris, they are easily dispersed in cosmetics or polymer films, which are quite useful for some anti-UV protection applications, such as anti-UV sunscreen creams and anti-UV window films for vehicles and buildings.