Showing papers on "Electrochromism published in 2013"
TL;DR: In this paper, a polyaniline (PANI)/graphite oxide (GO) nanocomposite films were fabricated by electropolymerization of aniline monomers onto GO coated indium tin oxide (ITO) glass slides, which were prepared by spin coating technique.
273 citations
TL;DR: This work describes the solvothermal deposition and electrochemical properties of porous, micron-thick Zn-pyrazolate MOF films containing redox-active naphthalene diimide (NDI) linkers and shows that processing them as homogeneously dispersed thin films enables their use as multicolored electrochromic devices.
Abstract: The construction of well-defined organic architectures on solid surfaces is a key step toward the development of more efficient and robust electronic devices. Indeed, a number of self-assembly strategies have been applied to building supramolecular structures for use in devices such as organic lightemitting diodes (OLEDs), organic transistors, and solar cells. Recently, self-assembled coordination polymers, namely crystalline, microporous metal-organic frameworks (MOFs), have received considerable attention for their potential in a number of applications, including electronic devices. The solvothermal methods used to synthesize MOF materials generally afford bulk single crystals or microcrystalline powders and, as a result, a number of methods have been developed to process MOFs as thin films, which are generally more desirable for use in devices. However, MOFs still face a number of challenges in this area, particularly with regard to their insulating nature. The incorporation of redox-active organic linkers represents one strategy toward improving the charge transport properties of MOF materials as well as imparting a response to electrochemical stimuli. In the latter case, the use of colorswitching, redox-active organic linkers might be considered for the design of new, color-tunable electrochromic materials. Inorganic materials such as metal oxides and Prussian blue analogs have been extensively studied for electrochromic applications. More recently, conducting organic polymers such as polythiophenes have received considerable attention owing to their greater color tunability and efficiency, and faster switching times. Despite significant advances, the need still exists for more easily synthesized and processable electrochromic materials with the same or greater degree of tunability. In this sense, the well-defined structures, selfassembly synthesis, and guest-accessible microporosity of MOFs might prove useful for their application in this field. Herein, we describe the solvothermal deposition and electrochemical properties of porous, micron-thick Zn-pyrazolate MOF films containing redox-active naphthalene diimide (NDI) linkers. NDIs have been extensively studied for their electron accepting properties which make them attractive as n-type semiconductors. Furthermore, core substitution of NDIs with electron donor groups results in the appearance of charge-transfer transitions in the visible spectrum, affording color-tunable and sometimes fluorescent dyes with applications in optoelectronics and sensing. A handful of MOFs containing NDI-based linkers have been reported and studied as gas sorption, photochromic, and fluorescent sensor materials. However, studies of their electrochemical properties remain scarce. Here, we show that processing them as homogeneously dispersed thin films enables their use as multicolored electrochromic devices. Our group has been concerned with developing modular syntheses for water-stable pyrazolate-based MOFs, and recently we described a series of core-substituted NDIbased materials. These MOFs (Zn(NDI-X), Figure 1) were obtained as microcrystalline powders by heating 1.1:1
243 citations
TL;DR: The WO3·2H2O ultrathin nanosheets are successfully assembled into the electrode of flexible electrochromic device, which exhibits wide optical modulation, fast color-switching speed, high coloration efficiency, good cyclic stability and excellent flexibility.
Abstract: Ultrathin nanosheets are considered as one kind of the most promising candidates for the fabrication of flexible electrochromic devices (ECDs) due to their permeable channels, high specific surface areas, and good contact with the substrate. Herein, we first report the synthesis of large-area nanosheets of tungsten oxide dihydrate (WO3·2H2O) with a thickness of only about 1.4 nm, showing much higher Li(+) diffusion coefficients than those of the bulk counterpart. The WO3·2H2O ultrathin nanosheets are successfully assembled into the electrode of flexible electrochromic device, which exhibits wide optical modulation, fast color-switching speed, high coloration efficiency, good cyclic stability and excellent flexibility. Moreover, the electrochromic mechanism of WO3·2H2O is further investigated by first-principle density functional theory (DFT) calculations, in which the relationship between structural features of ultrathin nanosheets and coloration/bleaching response speed is revealed.
233 citations
TL;DR: In this paper, a uniform and crack-free metalorganic framework (MOF) thin film composed of free-standing acicular nanorods was grown on a transparent conducting glass substrate, which exhibits electrochromic switching between yellow and deep blue by means of a one-electron redox reaction at its pyrene-based linkers.
Abstract: A uniform and crack-free metalorganic framework (MOF) thin film composed of free-standing acicular nanorods was grown on a transparent conducting glass substrate. The MOF thin film exhibits electrochromic switching between yellow and deep blue by means of a one-electron redox reaction at its pyrene-based linkers. The rigid MOF stabilizes the radical cations of the pyrene linkers at positive applied potential, resulting in the reversible color change of the MOF film. The regular and uniform channels of the MOF allow ions to migrate through the entire film. The MOF thin film thus exhibits a remarkable color change and rapid switching rate.
217 citations
TL;DR: "Solvophobic" and "electrostatic" interactions are proposed to account for the preferential growth of CP along metal oxides to form core/shell heterostructures to pave the way for developing new functional materials with enhanced properties or new applications.
Abstract: High-quality metal oxide/conducting polymer (CP) heterostructured nanoarrays are fabricated by controllable electrochemical polymerization of CP shells on preformed metal oxides nanostructures for both electrochromic and electrochemical energy storage applications. Coaxial and branched CP shells can be obtained on different backbones (nanowire, nanorod, and nanoflake) simply by controlling the electrodeposition time. “Solvophobic” and “electrostatic” interactions are proposed to account for the preferential growth of CP along metal oxides to form core/shell heterostructures. The coaxial TiO2/polyaniline core/shell nanorod arrays exhibit remarkable electrochromic performance with rich color changes, fast optical modulation, and superior cycling stability. In addition, the Co3O4/polyaniline core/shell nanowire arrays are evaluated as an anode material of Li ion battery and exhibit enhanced electrochemical property with higher and more stable capacity than the bare Co3O4 nanowires electrode. These unique org...
190 citations
TL;DR: The W18O49 nanowire devices display excellent stability when color switching continues, which may provide a versatile and promising platform for electrochromism device, smart windows, and other applications.
Abstract: Ordered W18O49 nanowire thin films were fabricated by Langmuir–Blodgett (LB) technique in the presence of poly(vinyl pyrrolidone) coating. The well-organized monolayer of W18O49 nanowires with periodic structures can be readily used as electrochromic sensors, showing reversibly switched electrochromic properties between the negative and positive voltage. Moreover, the electrochromism properties of the W18O49 nanowire films exhibit significant relationship with their thickness. The coloration/bleaching time was around 2 s for the W18O49 nanowire monolayer, which is much faster than the traditional tungsten oxide nanostructures. Moreover, the nanowire devices display excellent stability when color switching continues, which may provide a versatile and promising platform for electrochromism device, smart windows, and other applications.
187 citations
TL;DR: In this article, flexible multi-colored electrochromic and volatile memory devices are fabricated from a solution-processable electroactive aromatic polyimide with starburst triarylamine unit.
Abstract: Flexible multi-colored electrochromic and volatile memory devices are fabricated from a solution-processable electroactive aromatic polyimide with starburst triarylamine unit. The polyimide prepared by the chemical imidization was highly soluble in many organic solvents and showed useful levels of thermal stability associated with high glass-transition temperatures. The polyimide with strong electron-donating capability possesses static random access memory behavior and longer retention time than other 6FDA-based polyimides. The differences of the highest-occupied and lowest unoccupied molecular orbital levels among these polyimides with different electrondonating moieties are investigated and the effect on the memory behavior is demonstrated. The polymer fi lm shows reversible electrochemical oxidation and electrochromism with high contrast ratio both in the visible range and near-infrared region, which also exhibits high coloration effi ciency, low switching time, and the outstanding stability for long-term electrochromic operation. The highly stable electrochromism and interesting volatile memory performance are promising properties for the practical fl exible electronics applications in the future.
176 citations
TL;DR: In this paper, a comparison of solar radiation glazing factors for different glass fabrications enables one to evaluate and thus select the most appropriate glass material or system for the specific buildings and applications.
153 citations
TL;DR: The TiO2@PANI core/shell nanorod array is prepared by the combination of hydrothermal and electro-polymerization methods, which can reduce the oxidation potential, make the ion diffusion easier and provide larger surface area for charge-transfer reactions as mentioned in this paper.
Abstract: The TiO2@PANI core/shell nanorod array is prepared by the combination of hydrothermal and electro-polymerization methods. A significant optical modulation (57.6% at 700 nm), high coloration efficiency (37.1 cm2 C–1), and good cycling performance (62.1% after 1000 cycles) are achieved for the TiO2@PANI core/shell nanorod array. The improved electrochromic properties are mainly attributed to the core/shell structure, formation of the donor–acceptor system, and the porous space among the nanorods, which can reduce the oxidation potential, make the ion diffusion easier and provide larger surface area for charge-transfer reactions. The data indicate great promise for the TiO2@PANI core/shell nanorod array as a potential multicolor electrochromic material.
143 citations
TL;DR: In this paper, vertically aligned WO3 nanostructure films can be fabricated on FTO-coated glass substrates using a template-free hydrothermal technique, where the urea content and solvent composition played important roles in controlling the shape and size of the nanostructures, respectively.
Abstract: We have demonstrated that vertically aligned WO3 nanostructure films can be fabricated on FTO-coated glass substrates using a template-free hydrothermal technique. Detailed mechanistic studies revealed that a variety of WO3 nanostructures—including nano-bricks, 1D nanorods and nanowires, and 3D nanorod-flowers—could be obtained by tuning the composition of the precursor solution, where the urea content and solvent composition played important roles in controlling the shape and size of the WO3 nanostructures, respectively. These nanostructured films exhibited enhanced electrochromic performance, and we drew a map for the correlation between the morphology and the electrochromic performance of the as-synthesized WO3 films. Due to the large tunnels in the hexagonally structured WO3, and the large active surface area available for electrochemical reactions, a large optical modulation of 66% at 632.8 nm and a potential of −2.0 V, fast switching speeds of 6.7 s and 3.4 s for coloration and bleaching, respectively, and a high coloration efficiency of 106.8 cm2 C−1 are achieved for the cylindrical nanorod array film.
143 citations
TL;DR: The first localized surface plasmon resonance (LSPR)-based multicolor electrochromic device with five reversible optical states with electrochemically size-controlled silver nanoparticles enables a reversible multiple-color change by a shift of the LSPR band.
Abstract: The first localized surface plasmon resonance (LSPR)-based multicolor electrochromic device with five reversible optical states is demonstrated. In this device, the size of deposited silver nanoparticles is electrochemically controlled by using a voltage-step method in which two different voltages are applied successively. The electrochemically size-controlled silver nanoparticles enable a reversible multiple-color change by a shift of the LSPR band.
TL;DR: In this paper, the suitability of electrodeposited nanoparticulate-WO3 electrodes for transmissive electrochromic devices (ECDs) was highlighted, which resulted in highest photopic transmittance modulation (88.51%), better Li-ion diffusion coefficient (∼3.16 × 10−9 cm2 s−1), and excellent coloration efficiency.
Abstract: This report highlights the suitability of electrodeposited nanoparticulate-WO3 (NP-WO3) electrodes for transmissive electrochromic devices (ECDs). The WO3 electrodes in the form of thin films are composed of 10–20 nm nanoparticles. An electrochromic (EC) device of dimensions 5 × 4 cm2 fabricated using NP-WO3 showed an Li insertion coefficient (x) of 0.43, which resulted in highest photopic transmittance modulation (88.51%), better Li-ion diffusion coefficient (∼3.16 × 10−9 cm2 s−1), fast electrochromic response time (5.2 s for coloration and 3.7 for bleaching) and excellent coloration efficiency (∼137 cm2 C−1). On reduction of WO3, the CIELAB 1931 2° color space coordinates show the transition from colorless to the deep blue state (Y = 97, a* = −1.93, b* = 0.46 and Y = 10, a* = 1.57, b* = −41.01) with steady decrease in relative luminance.
TL;DR: Efficient visible to near-infrared absorption, photon to heat, and heat to electric conversion has been realized in one film that could benefit in exploiting multifunctional film displays, invisible NIR sensors, photodynamic theragnosis, and thermoelectric devices.
Abstract: Electrochromism, photothermal effect, and thermoelectric properties of hexyl-derivatized poly(3,4-ethylenedioxyselenophene) are investigated by precisely controlling the morphology. These properties are clearly demonstrated by controlling the applied electrical potential of the polymer films. Especially, the doped polymer film at -0.1 V reveals the highest photothermal conversion efficiency and a power factor of 42.5% and 354.7 μW m(-1) K(-2) , respectively. Efficient visible to near-infrared absorption, photon to heat, and heat to electric conversion has been realized in one film that could benefit in exploiting multifunctional film displays, invisible NIR sensors, photodynamic theragnosis, and thermoelectric devices.
TL;DR: In this article, thin films of WO3 were prepared by surfactant assisted spray pyrolysis on F-doped SnO2 (FTO) conductive glass by using hexadecyltrimethylammonium bromide (HTAB) and polyethylene glycol (PEG400) as growth controlling agents.
TL;DR: In this paper, a TiO2@WO3 core/shell nanorod arrays are prepared by the combination of hydrothermal and electrodeposition method, and the array films show remarkable enhancement of the electrochromic properties.
TL;DR: The transformation of nickel patterned in a three-dimensional, highly interconnected, periodic nanomorphology into a self-supporting nickel oxide array with hollow struts is demonstrated, showing substantially enhanced electrochromic performance, combining fast switching speeds with high coloration contrast.
Abstract: Ion intercalation processes into metal oxide porous materials benefit from a high surface-to-volume ratio, while electronic charge transport requires a continuous network morphology. Detailed control over structure formation on the 10 nm length scale is therefore an effective strategy to enhance performance in electrochromic devices, supercapacitors, and batteries. Here we demonstrate the transformation of nickel patterned in a three-dimensional, highly interconnected, periodic nanomorphology into a self-supporting nickel oxide array with hollow struts. The oxidation of nickel gives rise to the nanoscale Kirkendall effect, which substantially increases the surface area of the NiO gyroid framework, without sacrificing its connectivity. Applicable to a vast range of electroplatable metals, this is a versatile route to high surface area metal oxides/chalcogenides which is especially suitable for various thin film applications. Nanostructured NiO electrodes showed substantially enhanced electrochromic performance, combining fast switching speeds with high coloration contrast.
TL;DR: Using the CIE (Commission Internationale de l'Eclairage) system of colorimetry the color stimuli of the electrochromic NiO films and the changes that take place on reversibly oxidatively switching to the NiOOH form were calculated from in situ visible spectra recorded under electrochemical control.
Abstract: Aerosol-assisted chemical vapor deposition (AACVD) was used for the first time in the preparation of thin-film electrochromic nickel(II) oxide (NiO) The as-deposited films were cubic NiO, with an octahedral-like grain structure, and an optical band gap that decreased from 361 to 348 eV on increase in film thickness (in the range 500–1000 nm) On oxidative voltammetric cycling in aqueous KOH (01 mol dm–3) electrolyte, the morphology gradually changed to an open porous NiO structure The electrochromic properties of the films were investigated as a function of film thickness, following 50, 100, and 500 conditioning oxidative voltammetric cycles in aqueous KOH (01 mol dm–3) Light modulation of the films increased with the number of conditioning cycles The maximum coloration efficiency (CE) for the NiO (transmissive light green, the “bleached” state) to NiOOH (deep brown, the colored state) electrochromic process was found to be 563 cm2 C–1 (at 450 nm) for films prepared by AACVD for 15 min followed b
TL;DR: In this article, the influence of Ti doping on the electrochromic properties of WO3 thin films is investigated in the visible-infrared region, and it is attributed to their low crystallization, a starlike structure which has low charge transfer and ion diffusion resistance, leading to superior electrical conductivity and reaction kinetics.
Abstract: Hierarchical structure Ti-doped WO3 thin films are prepared by a template-free hydrothermal method. The influence of Ti doping on the electrochromic properties of WO3 thin films is investigated in the visible-infrared region. Ti doping can lead to significant surface morphology change and lower the crystallization, which plays an important role in the electrochromic properties of WO3 films. The large transmittance modulation (49.1% at 750 nm, 64.6% at 2000 nm and 59.3% at 10 μm), fast switching speed (1.7 s and 1.6 s) and high coloration efficiency (68 cm2 C−1 at 750 nm) are achieved for the low Ti-doped WO3 film. The enhancement in the electrochromic performance of the low Ti-doped WO3 films is attributed to their low crystallization, a star-like structure which has low charge transfer and ion diffusion resistance, leading to superior electrical conductivity and reaction kinetics.
TL;DR: In this article, a post-processing ozone technique was used to improve the electrochromic performance of an aluminum-containing nickel oxide material in lithium-ion electrolytes, and the resulting materials were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), ultraviolet-visible-near-infrared (UV-vis-NIR) spectrograms, and Xray absorption spectrogram (XAS).
Abstract: Electrochromic materials exhibit switchable optical properties that can find applications in various fields, including smart windows, nonemissive displays, and semiconductors. High-performing nickel oxide electrochromic materials have been realized by controlling the material composition and tuning the nanostructural morphology. Post-treatment techniques could represent efficient and cost-effective approaches for performance enhancement. Herein, we report on a post-processing ozone technique that improves the electrochromic performance of an aluminum-containing nickel oxide material in lithium-ion electrolytes. The resulting materials were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible–near-infrared (UV-vis-NIR) spectroscopy, and X-ray absorption spectroscopy (XAS). It was observed that ozone exposure increased the Ni oxidation state by introducing hole states in the NiO6 octahedral unit. In addition, ozone exposure gi...
TL;DR: Glass has been prepared that selectively absorbs visible and near-infrared light when an electrochemical voltage is applied, which opens the way to 'smart' windows that block heat on demand, with or without optical transparency.
Abstract: Glass has been prepared that selectively absorbs visible and near-infrared light when an electrochemical voltage is applied. This opens the way to 'smart' windows that block heat on demand, with or without optical transparency. See Letter p.323
Glass windows let in light and keep out extreme heat and cold, but with the advance of the field of electrochromism — the reversible change of optical transmittance in response to electrochemical charge and discharge — they could do much more. Delia Milliron and co-workers have made a step towards producing windows that can greatly reduce lighting and heating costs with the demonstration of a composite film composed of tin-doped indium oxide nanocrystals embedded in a niobium oxide glass matrix. By varying an applied voltage over a 2.5-volt range, the charged nanocrystals selectively block near-infrared light, while the glass strongly modulates visible light owing to its reconstructed bonding near the nanocrystal–glass interface. Practical 'smart windows' and other devices are still some way off, but this solution-processed nanocrystal-in-glass approach is modular and permits extensive tuning of structure and composition, and so provides a solid platform for further refinement.
TL;DR: The preparation and characterisation of the electrochromic polyaniline–nonwoven composite and the electro chromic display prototype in which it is applied are outlined and the benefits and drawbacks of the technology are discussed.
TL;DR: The composite WO3/TiO2 nanostructures showed higher ion storage capacity, better stability, enhanced EC contrast, and longer memory time compared with the pure WO2 and TiO2 materials.
Abstract: A composite material consisting of TiO2 nanotubes (NT) with WO3 electrodeposited on its surface has been fabricated, detached from its Ti substrate, and attached to a fluorine-doped tin oxide (FTO) film on glass for application to electrochromic (EC) reactions. Several adhesion layers were tested, finding that a paste of TiO2 made from commercially available TiO2 nanoparticles creates an interface for the TiO2 NT film to attach to the FTO glass, which is conductive and does not cause solution-phase ions in an electrolyte to bind irreversibly with the material. The effect of NT length and WO3 concentration on the EC performance were studied. The composite WO3/TiO2 nanostructures showed higher ion storage capacity, better stability, enhanced EC contrast, and longer memory time compared with the pure WO3 and TiO2 materials.
TL;DR: In this paper, a review of various synthetic approaches to polypyridine ligands is presented, based on the polymerization efficiency of vinyl-substituted complexes and the stability of the resulting polymeric films.
TL;DR: It is demonstrated that thin films of hierarchical NiO microflakes assembled from nanoleaves can be grown directly on FTO-coated glass substrates using a facile and template-free hydrothermal technique and exhibit highly enhanced electrochromic performances and cyclic stability.
Abstract: We have demonstrated that thin films of hierarchical NiO microflakes assembled from nanoleaves can be grown directly on FTO-coated glass substrates using a facile and template-free hydrothermal technique This hierarchical structure holds the advantages of both nanometre-sized building blocks and microsized assemblies Thus, the films exhibit highly enhanced electrochromic performances and cyclic stability due to their high surface area and good electrochemical stability Moreover, a complementary electrochromic device combining the hierarchical NiO microflake film with a self-weaving WO3 nanoflake film is fabricated to further improve the electrochromic performance As a result, the complementary electrochromic device shows a high optical modulation (732% at 550 nm), large coloration efficiency (1469 cm2 C−1 at 550 nm by applying a low coloration voltage of −10 V) and fast switching responses with a coloring time of 18 s and a bleaching time of 32 s It is also observed that there is no significant degradation of the electrochromic properties after 2000 continuous coloration/bleaching cycles, making it attractive for practical applications
TL;DR: In this article, a series of Fe/Ru-based bimetallo-supramolecular polymers were synthesized by a stepwise coordination of Fe(II and Ru(II) ions to bis(terpyridyl)benzene (L1), which exhibited multi-colour electrochromic behavior based on the redox potential of the metal ion.
Abstract: A series of Fe/Ru-based bimetallo-supramolecular polymers were synthesized by a stepwise coordination of Fe(II) and Ru(II) ions to bis(terpyridyl)benzene (L1). The polymers exhibited multi-colour electrochromic behaviour based on the redox potential of the metal ion. Electrochemical and electrochromic properties of the polymer films were analyzed in acetonitrile with 0.1 M lithium perchlorate as an electrolyte. The polymer films showed high optical contrast and very fast response times, demonstrated by transmittance changes (ΔT) at 508 and 585 nm that were 68% and 37%, respectively, within a few seconds. Coloration efficiencies (η) were established for the first time in a metallo-supramolecular electrochromic system, with values of 242.1 and 188.2 (cm2 C−1) at different wavelengths.
TL;DR: In this paper, the electrochromic properties of transparent one-dimensional nickel oxide (NiO) nanorods were reported, including stable and reversible coloration-bleaching cycles, as well as good coloration efficiency.
TL;DR: In this article, the coloration mechanism of NiO was studied using the near-grazing incidence angle Fourier transform infrared spectroscopy (NGIA FTIR) and endurance potential cycling.
TL;DR: In this article, a flexible display is used as a visual interface for applications such as in electronic papers and paper electronics, where passive or active matrix-addressing of individual components is employed.
TL;DR: In this article, a mesoporous hexagonal-phase Na0.17WO3.085·0.29H2O nanosheet/microflower hierarchical structure has been synthesized employing a one-pot hydrothermal process with the assistance of Na2SO4.
Abstract: For the first time, a mesoporous hexagonal-phase Na0.17WO3.085·0.29H2O nanosheet/microflower hierarchical structure has been synthesized employing a one-pot hydrothermal process with the assistance of Na2SO4. It is shown that Na2SO4 not only acts as a stabilizer to facilitate the generation of a metastable hexagonal phase, but also function as a structure directing agent to assist the construction of nanosheet assemblies. The formation mechanisms have been rationalized. The materials have been thoroughly characterized by XRD/BET/FESEM/EDX/TEM/TGA. This hexagonal-phase Na0.17WO3.085·0.29H2O nanosheet/microflower hierarchical structure exhibits applicable electrochromic and adsorptive properties due to its unique crystallographic configuration and microstructures, promising its application in energy-saving smart windows and wastewater treatment.