Browsing by Subject "Tungsten oxide"
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Item Open Access 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 VolkanUniform 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).Item Open Access Nonlinear laser lithography for indefinitely large-area nanostructuring with femtosecond pulses(Nature publishing group, 2013) Öktem, B.; Pavlov, I.; Ilday, S.; Kalaycıoǧlu, H.; Rybak, A.; Yavaş, S.; Erdoǧan, M.; Ilday F. Ö.Dynamical systems based on the interplay of nonlinear feedback mechanisms are ubiquitous in nature. Well-understood examples from photonics include mode locking and a broad class of fractal optics, including self-similarity. In addition to the fundamental interest in such systems, fascinating technical functionalities that are difficult or even impossible to achieve with linear systems can emerge naturally from them if the right control tools can be applied. Here, we demonstrate a method that exploits positive nonlocal feedback to initiate, and negative local feedback to regulate, the growth of ultrafast laser-induced metal-oxide nanostructures with unprecedented uniformity, at high speed, low cost and on non-planar or flexible surfaces. The nonlocal nature of the feedback allows us to stitch the nanostructures seamlessly, enabling coverage of indefinitely large areas with subnanometre uniformity in periodicity. We demonstrate our approach through the fabrication of titanium dioxide and tungsten oxide nanostructures, but it can also be extended to a large variety of other materials.