Papers by Keyword: Electrochromism

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Authors: Claes Goran Granqvist, E. Avendaño, A. Azens
Authors: Yi Jie Tao, Zhao Yang Zhang, Hai Feng Cheng, Wen Wei Zheng
Abstract: An electrochromic copolymer based on pyrrole and 3,4-ethylenedioxythiophene (EDOT) are electrodeposited on ITO electrode in aqueous micellar solution. The copolymer show blue grey in neutral state (-0.8V) and light blue in oxidized state(0.8V). The λmax of the copolymer in neutral state is 530nm and the onset energy for π-π* transition (Eg) is calculated to be 1.68eV by the onset wavelength. And successive cycle voltammagrams indicate that the incorporation of EDOT units into the Ppy improves the electrochemical stability of the copolymer films, which retains 89% of electroactivity after 500 cycles, the copolymer could be as a promising candidate material for electrochromic devices.
Authors: Sangeeta Adhikari, Debasish Sarkar
Abstract: Nanoscale material world attracted researchers because of their outstanding properties and prospective novel applications. Tungsten trioxide semiconductor is one of the fundamental functional materials due to its versatile application as gas sensors, solar cells, and smart windows. Confined growth of the metal oxide nanostructures can tune the electrical and optical properties for modern device application. The management of morphology is a challenge to investigate the ultimate performance. In this paper, self-assembled growth of four different tungsten trioxide nanostructures were carried using a different structure directing agents through either co-precipitation or hydrothermal techniques. The monoclinic spherical and rod-like WO3 nanostructures were obtained by acid precipitation method. WO3 nanocuboids and nanofibers were synthesized hydrothermally using HBF4 and NaCl as structure directing reagents to attain monoclinic and hexagonal crystal phases, respectively. Analytical techniques like XRD, TEM, and FESEM imaging methods were used to confirm the phase and morphology. All the nanopowders were calculated to have similar band gap energy at visible wavelength. A simple dip coated WO3/ITO fabricated electrode was used as a reference electrode to carry out the electrochemical measurements for all nanopowders. The evaluated properties suggested the plausible use of WO3 nanofibers for high efficient electrochromic device.
Authors: Xiao Qian Xu, Wen Wei Zheng, Yi Jie Tao
Abstract: A novel copolymer based on bromobenzene and 3,4-ethylenedioxythiophene (EDOT) was electrochemically prepared in boron trifluoride diethyl etherate (BFEE) via direct anodic oxidation of the monomer mixtures on indium-tin oxide working electrodes. The corresponding polymer was characterized by cyclic voltammetry and UV-vis spectroscopy. The copolymer had a very well-defined and reversible redox process. The band gap of the copolymer was calculated as 1.42 eV, respectively from the onset of π-π* transition of conjugated backbone. Furthermore, the copolymer exhibited multicolor electrochromism, high redox stability and reasonable response time.
Authors: F. Pınar Gokdemir, Ece Yuzbasioglu, A. Evrim Saatci, Orhan Ozdemir, Kubilay Kutlu
Abstract: Comparative work of erbium doped vanadium pentoxide and titanium dioxide thin films were carried out via sol gel technique by dissolving erbium (III) nitrate pentahydrate in vanadium (V) oxoisopropoxide and titanium (IV) isopropoxide. Fourier Transform IR and thermogravimetric/differential thermal measurements were performed to find out erbium substitution. UV-Vis. spectroscopy indicated a blue shift upon Er doping in V2O5 film due to the softening of V=O bond. The similar behavior was expected in TiO2 film and the prediction shall be shown only if annealing of the film above 600°C, resulting oxygen deficiency in anatase TiO2 while Ti deficiency in rutile TiO2 film. Due to such impact of erbium on structure, granule size of the films, determined by AFM, increased yielding more space for intercalation of ion in host materials and monitored through cyclic voltammetry measurements.
Authors: Gyun Tak Kim, Hoh Yeong Kim, Tae Jin Hwang, Heung Yeol Lee
Abstract: The adhesion enhancement effect of tetraethoxysilane (TEOS) addition to a silica-polyaniline composite film on ITO glass substrate was studied. The composite film was prepared with the silica-polyaniline core-shell composite nanoparticles which were synthesized by a chemical polymerization of polyaniline in a colloidal solution of silica. A small amount of TEOS and acidic water was added to the dispersion solution of composite nanoparticles. The addition of TEOS was intended to increase the adhesion of electrochromic film to substrate without a deterioration of the electrochromic properties such as response time and cycle life. The adhesion of the films was tested by a tape test, and the composite film with TEOS showed a dramatic increase in adhesion to the ITO glass substrate when compared with the film deposited without TEOS. The electrochromic properties of the films were also characterized using the cyclic voltammetry and the optical response measurement.
Authors: Ai Ping Jin, Quan Yao Zhu, Wen Chen, Victor L. Volkov, Galina S. Zakharova, Han Xing Liu, Jian Zhou, Qing Xu
Abstract: Vanadium pentoxide xerogel films intercalated by poly (ethylene oxide), PEO, were prepared using direct intercalation method via a sol-gel route. The electrical and electrochromic characterization of the films were conducted. The electrical properties along and across V-O layers have been evaluated. The results indicate that the proper amount of PEO can increase the electrical conductivity and charge density of the films. The electrochromism of the films upon lithium intercalation was investigated by ex-situ transmittance measurement. The films display a reversible multichromism (orange green blue) upon Li+ ion insertion/extraction.
Authors: Ai Ping Jin, Wen Chen, Quan Yao Zhu
Abstract: The hybrid guest-host nanocomposite films based on poly (ethylene oxide) (PEO) and molybdenum doped vanadium pentoxide (V0.975Mo0.025)2O5nH2O were prepared by sol-gel and hydrothermal reaction via a two-part process. The electrical properties along and across V-O layers have been evaluated. The results indicate that the proper amount of PEO can increase the electrical conductivity of the films. The electrochromism of the films were investigated by cyclic voltammetry, the ex-situ transmission spectra and photographs. The films display a reversible multichromism (orangegreenbluebrown) upon Li+ ion insertion/extraction.
Authors: Arturo Mendoza-Galván, M.A. Vidales-Hurtado
Abstract: Nickel oxide-based thin films were deposited onto indium-tin oxide (ITO) coated glass substrates by the chemical bath method. The synthesis, based on the decomposition of urea in an aqueous nickel nitrate solution, promotes the deposition of the turbostratic -Ni(OH)2 phase. The electrochromic behavior of films obtained from low and high urea concentrations was tested after air annealing at temperatures of 250 and 300 °C. Using cyclic voltammetry, chronoamperometry and in-situ single wavelength transmittance it is shown that the films exhibit good reversibility and coloration efficiency. Transmittance spectra in the visible range show the high optical contrast of the films. It was found that in films annealed at 250 °C the bleached-colored switching is between the Ni(OH)2 and -NiOOH phases. Films annealed at 300 °C are comprised by a Ni(OH)2-NiO mixture and Ni2O3 units or the -NiOOH phase are responsible for coloring depending on urea concentration in solution. The -NiOOH phase was clearly identified in over-colored films. X-ray diffraction, Raman scattering, and infrared reflectance were used for phase identification.
Authors: P.J.S. Foot, V. Montgomery, P. Spearman
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