Application In Electrochromic Devices Research Articles

Multichromic conducting copolymer of 1-benzyl-2,5-di(thiophen-2-yl)-1 H-pyrrole with EDOT

Despite the significant progress made in the field of electrochromic polymers, the multichromic facility of current knowledge is restricted. Therefore, as previously proven, electrochemical copolymerization of 1-benzyl-2,5-di(thiophen-2-yl)-1 H-pyrrole (SNBS) and 3,4-ethylenedioxythiophene (EDOT) was used as a strategy to achieve desired multichromic properties, where the resultant copolymer displayed distinct color changes between claret red, yellow, green, and blue colors with short switching times and high optical contrast. As an application, absorption/transmission type electrochromic device with indium tin oxide (ITO)/copolymer/gel electrolyte PEDOT/ITO configuration was constructed, where copolymer and PEDOT functioned as the anodically and the cathodically coloring layers, respectively. Results implied the successive use of this copolymer in electrochromic device applications, since the device exhibited short switching times with a wide color variation upon applied potential.

Fine tuning of color via copolymerization and its electrochromic device application

In this study electrochemical copolymerization of 1-(perfluorophenyl)-2,5-di(thiophen-2-yl)-1H-pyrrole and 3,4-ethylenedioxythiophene was used to fulfill a strategy in achieving desired multichromic properties. The resultant polymer displayed distinct color changes between red–violet, amber, green and blue color with good switching times and optical contrast. A direct correlation between the color of the polymer in neutral state and the applied potential during synthesis was observed. Hence, it was possible to achieve colors from maroon, red–violet, and eggplant to indigo depending on the applied potential. A dual type electrochromic device of the copolymer and poly(3,4-ethylenedioxythiophene) was constructed to evaluate the possible use of such copolymer in device applications. The device displayed multichromism, with 1.1 s switching time and good electrochromic memory.

Electrochromic properties of poly (1-(phenyl)-2,5-di(2-thienyl)-1H-pyrrole-co-3,4-ethylenedioxy thiophene) and its application in electrochromic devices

Electrochemical copolymerization of 1-(phenyl)-2,5-di(2-thienyl)-1H-pyrrole (PTP) with 3,4-ethylenedioxy thiophene (EDOT) was carried out in acetonitrile (AN)/NaClO4/LiClO4 (0.1M) solvent–electrolyte couple via potentiodynamic electrolysis. Characterizations of the resulting copolymer were performed via cyclic voltammetry (CV), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and spectroelectrochemical analysis. Spectroelectrochemical analyses show that the copolymer of PTP with EDOT has an electronic band gap (due to π to π∗ transition) of 1.9eV at 480nm, with a claret red in the fully reduced form and a blue color in the fully oxidized form. Via kinetic studies, the optical contrast (ΔT %) was found to be 8% for P(PTP-co-EDOT). Results showed that the time required to reach 95% of the ultimate transmittance was 1.7s for the copolymer.The P(PTP-co-EDOT) film was used to construct a dual type polymer electrochromic device (ECDs) with poly(3,4-ethylenedioxy thiophene) (PEDOT). Spectroelectrochemistry, electrochromic switching and open circuit memory of the device were investigated.

Imidazolium-based ionic liquid derivatives for application in electrochromic devices

Novel proton-conducting electrolytes were prepared from the sol–gel precursor 1-[3-(trimethoxy-λ4-silyl)propyl]imidazole with the addition of either trifluoroacetic or acetic acid. The presence of trimethoxysilyl groups enabled the solvolysis and condensation reactions of silsesquioxane species. IR spectroscopy revealed that more cube-like species formed in the electrolyte prepared from trifluoroacetic acid, while cube- and ladder-like silsesquioxanes were present in the electrolyte with acetic acid. This assignation was independently confirmed by 29Si NMR analyses revealing the T3 signals of trisiloxane bonding. IR spectroscopy also pointed to the formation of hydrogen bonding in the latter electrolyte, since the frequencies of the observed bands at 1710, 1409, and 1272 cm−1 approached those of acetic acid. In contrast, the IR bands at 1662, 1204, and 1130 cm−1 confirmed the existence of trifluoroacetate anions in the case when the electrolyte was prepared from trifluoroacetic acid. The presence of free trifluoroacetate anions contributed to the moderately higher specific conductivity of this electrolyte (4.6×10−5 S/cm) compared to that of acetic acid (1.6×10−5 S/cm). The specific conductivity of the electrolytes could be further increased by the addition of a lithium salt. All electrolytes were employed in electrochromic devices with optically active WO3 and various inorganic counter-electrodes (CeVO4, V2O5, Ti/V-oxide). Photopic transmittance changes from 30% to 40% were achieved.

Solid hybrid polyelectrolyte with high performance in electrochromic devices: Electrochemical stability and optical study

This paper presents a high-stability, single-phase hybrid polyelectrolyte (SPHP) applied in a large EC device (5×10 cm 2) using WO 3 (electrochromic) and CeO 2–TiO 2 (counter-electrode–ion storage) electrodes, both produced by Leibniz—Institut of New Materials (Leibniz—INM, Germany). The electrochromic device exhibited excellent color and bleach reversibility, high coloration efficiency (>35 cm 2/C) from the first cycle up to more than 60,000 CA cycles, and a maximum constant rate of deintercalation/intercalation ( O out/ Q in=1). Its remarkable behavior and high stability render this material an excellent candidate for application in electrochromic devices.

Solid state electrochromic device applications of N-(2-(thiophen-3-yl)methylcarbonyloxyethyl) maleimide

Homopolymer and copolymer of N-(2-(thiophen-3-yl)methylcarbonyloxyethyl) maleimide (NMThi) with thiophene [P(NMThi- co-Th)] were synthesized electrochemically in acetonitrile/borontrifluoride ethylether solvent mixture (1:1, v/v). Spectroelectrochemical analysis of the resulting copolymer reflected electronic transitions at 488 and 718 nm revealing π to π ∗ transition and polaron formation, respectively. Switching ability was evaluated by a kinetic study via measuring the transmittance (% T) at the maximum contrast. Dual-type polymer electrochromic devices (ECDs) based on homopolymer (P(NMThi) and copolymer P(NMThi- co-Th) were constructed with poly(3,4-ethylenedioxythiophene) (PEDOT). Spectroelectrochemistry and switching ability of the devices were investigated by UV–vis spectroscopy and cyclic voltammetry.

Performance of a single-phase hybrid and nanocomposite polyelectrolyte in classical electrochromic devices

In this paper, we discuss the high stability of a single-phase hybrid polyelectrolyte (SPHP) and nanocomposite hybrid polyelectrolyte (NHP) in a large electrochromic (EC) device (5 cm × 10 cm) mounted with different electrodes. The electrochromic device (K-glass/FTO/WO 3/SPHP/CeO 2–TiO 2/FTO/K-glass—ECI, K-glass/FTO/WO 3/NHP/CeO 2–TiO 2/FTO/K-glass—ECII,) exhibited excellent color and bleach reversibility, high coloration efficiency (CE) (>35 cm 2/C) from the first cycle up to more than 60,000 CA cycles, and a maximum constant rate of deintercalation/intercalation ( O out/ Q in = 1). Also, the life time of the EC device with Nb 2O 5:Mo (K-glass/FTO/Nb 2O 5:O/SPHP/CeO 2–TiO 2/FTO/K-glass—ECIII) was prolonged to up to more than 10,000 cycles with a fairly stable coloration efficiency (around 19 cm 2/C) and O out/ Q in = 1. The SPHP and NHP were tested in a large EC device with different configurations to evaluate its successful performance. In conclusion, its remarkable behavior and high stability render this material an excellent candidate for application in EC devices.

A Solution‐Processable High‐Coloration‐Efficiency Low‐Switching‐Voltage Electrochromic Polymer Based on Polycyclopentadithiophene

AbstractA solution‐processable electrochromic (EC) polymer, poly(4,4‐dioctyl‐cyclopenta[2,1‐b:3,4‐b′]‐dithiophene) (PDOCPDT) is prepared by means of chemical oxidative polymerization of the corresponding monomer. The UV‐vis spectrum of the spin‐coated PDOCPDT film displays an absorption maximum of 580 nm. Although the polymer is deep blue in its neutral state, it turns to transparent bluish after being oxidized. PDOCPDT film (thickness 120 nm) exhibits high coloration efficiency (CE)—as high as 932 C cm–2 at 580 nm, low response time (0.75 s), high optical density (0.75 at 580 nm), and high‐level stability for long term switch (it switches repetitively 1000 times with less than 8 % contrast loss). The electrochemical stability and redox potentials of PDOCPDT films are independent of film thickness (50–180 nm) and active area (up to 2 cm × 2 cm). Nevertheless, optical contrast increases as the film thickness increases, although the CE and response time changes irregularly with the film thickness. The good EC properties combined with the easy film fabrication process make PDOCPDT a notable candidate for application in EC devices. (ECDs) A simple transmissive‐type ECD with good CE using PDOCPDT film as an active layer is also demonstrated.

Morphological and structural studies of WO x thin films deposited by laser ablation

Tungsten oxide is an interesting compound with many applications in gas sensors, electrochromic and photochromic devices. Thin films of tungsten oxide were obtained by pulsed laser deposition (PLD) and radio frequency assisted PLD (RF-PLD). A tungsten target was ablated in reactive oxygen atmosphere (0.01–0.05 mbar). The deposition parameters such as laser fluence, substrate temperature, radiofrequency power were varied, while different materials (Corning glass and silicon) have been used as substrates. The obtained films showed good adhesion to the substrate and uniform surface aspect, which are important properties for applications. X-ray diffraction, Auger electron, Raman spectroscopies and atomic force microscopy were used for characterization.

Electrosynthesis of polyfuran in acetonitrile–boron trifluoride–ethyl ether mixture and its device application

AbstractElectrochemical polymerization of furan was achieved in acetonitrile/boron trifluoride/ethyl ether (CH3CN/BF3/EE) mixture in the presence of tetrabutylammonium tetrafluoroborate via constant potential electrolysis at 1.4 V versus Ag/AgCl. Electrochemical behavior of furan was investigated in the same solvent mixture of varying ratios, utilizing cyclic voltammetry. Free‐standing polyfuran (PFu) films were obtained in CH3CN/BF3/EE mixture (2/4/4; v/v/v) and characterized using FTIR spectroscopic technique. Spectroelectrochemical behavior of the PFu film was investigated by recording the electronic absorption spectra, in situ, in monomer‐free solution. It is observed that PFu film can be reversibly cycled between –0.1 V (gray) and + 0.6 V versus Ag‐wire (gray color); however, this behavior diminishes in the presence of water. Electrochromic device application of PFu film with poly(ethylene dioxythiophene) was also studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 871–876, 2007

Freestanding Mesoporous Quasi-Single-Crystalline Co3O4 Nanowire Arrays

We report a facile template-free method for the large-area growth of freestanding hollow Co3O4 nanowire arrays on a variety of substrates including transparent conducting glass, Si wafer, and copper foil, et al. These nanowires have the interesting combined properties of mesoporosity and quasi-single-crystallinity. With their high surface area and crystallinity, and their direct growth on conductive substrate, these Co3O4 nanowire arrays will have promising applications in lithium-ion batteries, chemical sensing, and field-emission and electrochromic devices. Using the prepared nanowire arrays as electrode, an electrochemical sensor for hydrogen peroxide sensing has been demonstrated.

Electrochromic properties and electrochromic device application of copolymer of N‐(4‐(3‐thienyl methylene)‐oxycarbonylphenyl)maleimide with thiophene

AbstractA new copolymer of N‐(4‐(3‐thienyl methylene)‐oxycarbonylphenyl)maleimide (MBThi) with thiophene [P(MBThi‐co‐Th)] was synthesized electrochemically in the presence of tetrabutylammonium tetrafluoroborate as the supporting electrolyte, in acetonitrile/borontrifluoride ethylether solvent mixture (80 : 20, v/v). Spectroelectrochemical analysis of the resulting copolymer reflected electronic transitions at 440, 730, and ∼1000 nm, revealing π–π* transition, polaron, and bipolaron band formation, respectively. Switching ability was evaluated by a kinetic study via measuring the transmittance (%T) at the maximum contrast. Dual‐type polymer electrochromic devices (ECDs) based on P(MBThi‐co‐Th) and poly(ethylene dioxythiophene) (PEDOT) were constructed. Spectroelectrochemistry, switching ability, and stability of the devices were investigated by UV–vis spectroscopy and cyclic voltammetry. These devices exhibit low switching voltages (between 0.0 and +2.0 V) and short switching times with reasonable switching stability under atmospheric conditions. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 102: 4500–4505, 2006

A Low-Temperature Atmospheric Pressure CVD Process for Growing Thin Films of MoO3 and MoO3-WO3 for Electrochromic Device Applications

Thin films of MoO3 and mixed Mo/W oxides have been obtained by atmospheric pressure (AP)CVD, using pyrolytic decomposition of metal carbonyls. The correlation between film structure and optical properties is studied by applying techniques such as Raman spectroscopy (RS), Fourier transform infrared (FTIR) spectroscopy, and UV-vis spectrophotometry. The transmittance in the visible range of films deposited on glass substrates is about 80 %, but when deposited on conductive glass (e.g., SnO2:Sb/glass) the films have 60 % transmittance. After annealing, the optical transmittance of the single oxide films improves, while for the mixed oxide films it slightly decreases. The electrochromic (EC) properties of MoO3 and mixed Mo/W oxide films have been investigated by cyclic voltammetry. Deep-blue coloring of all the EC films appears only in the cathodic range, minimizing the visible-light transmittance. In the anodic regime, the EC film starts bleaching and becomes transparent. Devices fabricated with a solid polymeric-type electrolyte and a functioning layer of mixed oxide films exhibit good reversibility of the effect, and an optical modulation of about 30 % is obtained.

Preparation and characterization of electron beam evaporated WO 3 thin films

Thin film of tungsten oxide (WO 3) has been extensively studied as an electrochromic material and has numerous applications in electrochromic devices, smart windows, gas sensors and optical windows. In order to explore the possibility of using this in electrochromic devices, a preliminary and thorough study of the optical properties of the host material is an important step. Based on the above criterion, the effect of annealing temperature on the structural, surface morphological and optical properties of WO 3 films has been studied in the present work. The host material, WO 3 films, has been prepared by the physical vapor deposition method of electron beam evaporation (PVD:EBE) technique under a pressure of 1 × 10 −5 mbar. The single phase nature, monoclinic structure and textured nature of the films have been confirmed by the X-ray diffraction analysis. The needle-like crystallites have been observed from surface morphological studies. The evaluated crystallite size is in the nanometer range. The shift in absorption edge towards the higher wavelength region observed from optical studies may be due to the coloration effect on the films.

Tailor-made polymer electrolytes based upon ionic liquids and their application in all-plastic electrochromic devices

A new type of tailor-made polymer electrolyte based on ionic liquids (ILs) and polymeric ionic liquids (PILs) analogues has been prepared by mixing 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonimide) [bmim][Tf 2N], 1-butyl-3-methylimidazolium tetrafluoroborate [bmim][BF 4] and 1-butyl-3-methylimidazolium bromide [bmim][Br], with poly[1-vinyl-ethyl-imidazolium] bearing similar counter-anions [Tf 2N], [BF 4] and [Br]. The chemical affinity between PILs and ILs affords a completely compatible combination resulting in stable polymer electrolytes. The ionic conductivity of all these polymer electrolytes varies between 10 −2 and 10 −5 S cm −1 at room temperature, and shows high values of conductivity with increasing ionic liquid content. Finally, we have demonstrated that cycle life of electrochromic devices (ECDs) is significantly enhanced (up to 70,000 cycles) when this new type of tailor-made polymer electrolyte was used in PEDOT/electrolyte/PEDOT devices as compared to previously used poly(ethylene oxide) electrolytes.

Molecular Assembly Engineering of Self-Doped Polyaniline Film for Application in Electrochromic Devices

Self-doped polyaniline (SPANI) films were prepared by using a self-assembly process consisting of a self-doping monomer (-aminobenzenesulfonic acid, SAN) and aniline (AN). SAN-AN copolymerization and film formation were simultaneously performed in an aqueous solution. An immersing self-assembly method was developed to buildup a SPANI nanofilm on a indium-tin oxide (ITO) glass, providing an electrode material in an electrochromic device ITO ITO where poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) is PEDOT:PSS, and waterborne polyurethane is WPU. Short response time (ca. 10 s) was attained from coloring to bleaching processes. After 300 switchings, the coulombic efficiency and stability of optical contrast possess the values of 94 and 90%, respectively.

Influence of Intercalated Lithium on Structural and Electrical Properties of V2O5, Mixed V ∕ Ce Oxide, and Fe2O3

We have investigated thin films containing nanosized grains of , new oxides, and , , and , with Li by the thermally stimulated currents, impedance spectroscopy, Raman spectroscopy, and grazing-incidence small-angle X-ray scattering (GI-SAXS) at the Elettra Synchrotron (Italy, Trieste). Combining different experimental methods, the dependence of structural and electrical properties upon percentage of Li added into the matrix of these metal-oxide films was found. These changes are explained by the structural changes of grains (and grain boundaries) and with the impact of ions in the charge transfers. The average grain radius , obtained by GI-SAXS, increased in oxide at upon the intercalation of ions. This particular morphology is quite suitable for application in electrochromic devices in an advanced electrochemical cell concept and efficient new solar cells.

Electrochromic devices based on wide band-gap nanocrystalline semiconductors functionalized with mononuclear charge transfer compounds

A series of ruthenium and iron mononuclear complexes were prepared and their spectroeletrochemical behavior characterized on Optically Transparent Thin Layer Electrodes (OTTLE) and on Fluorine Doped SnO 2 (FTO) conductive glasses coated with Sb-doped nanocrystalline SnO 2. These systems display a reversible electrochemical response and offer potential application in electrochromic devices. On SnO 2 films distinct spectral changes are observed in a narrow potential range (−0.5/0.9 V vs SCE) with switching times of the order of 0.8 s.

Influence of aging and composition of the precursor sol on the properties of CeO 2–TiO 2 thin films for electrochromic applications

Sol–gel derived spin coated CeO 2–TiO 2 thin films with two different compositions have been prepared using precursor sols based on ceric ammonium nitrate and titanium isopropoxide in ethanol. The aging effect of the sol on different properties of the films has been investigated by subjecting the films to optical, electrochemical and structural analysis by employing characterization techniques such as UV–visible spectrophotometry, cyclic voltammetry, multiple step chronoamperometry, X-ray diffraction, FT-IR, electron microscopy, differential thermal analysis and energy dispersive X-ray analysis. The films are nanocrystalline as shown by the TEM study. The optically passive nature of the films shows their potential as passive counter electrodes. Good electrochemical reversibility under lithium ion insertion, studied for a large number of cycles confirms that the films are promising candidates as ion storage layer in electrochromic devices. The performance characteristics of the electrochromic devices have improved with the aging of the precursor sol employed for the deposition of the CeO 2–TiO 2 films. High diffusion coefficient and thereby faster kinetics of the insertion/extraction reactions in Ce/Ti (1:1) films shows the suitability of this composition in systems wherein dynamic response is important. However, higher ion storage capacity of Ce/Ti (1:2) films has led to their usefulness in applications wherein the transmission modulation of the overall device is the most significant. In the present study, the device comprising the CeO 2–TiO 2 (1:2) film has exhibited the highest transmission modulation, thereby this composition of the ion storage layer is considered to be the most promising from the viewpoint of its application in transmissive electrochromic devices.

Colours from electroactive polymers: Electrochromic, electroluminescent and laser devices based on organic materials

This paper focuses on the most relevant devices currently used in order to achieve electrically stimulated generations of colours from electroactive polymers, either as coloured light emissions from the material or as modifications of its intrinsic colour properties. For this purpose, most relevant materials, fundamental principles of operations, latest developments and current applications of organic-based electrochromic, electroluminescent and lasing devices are reviewed here. The very promising performances resulting from the analysis of state-of-the-art products, and in particular of those which are currently approaching commercial applications, suggest likely roles played by such devices for niche applications in the very near future.