An electrochromic display based on titanium dioxide

An electrochromic display (ECD) based on anatase titanium dioxide was investigated. When negative and positive voltage bias were applied to TiO₂/In₂O₃-coated glass electrode, the coloration and bleaching phenomena were alternately observed by the electrochemically reversible reaction of

Reversibility, contrast during “Write”, frequency response and cycle tests, which were required for an information display device, were examined and shown to have a possibility to apply an electrochromic display device.     

Strength of display glass

The strength of dual-display glass surfaces 0.64 mm (Corning 1737 glass) and 0.70 mm (Eagle²⁰⁰⁰ glass) thick is measured in the initial state and after annealing. Large dispersion of the strength of the glass before and after annealing is found. It is suggested that the low values of the strength are caused by the adverse conditions of storing and handling glass samples.     

Organic multiviologen electrochromic cells for a color electronic display application

The electrochromic (EC) and optical properties of three new viologen compounds containing 1,1′‐di‐n‐heptyl‐4,4′‐bipyridinum dibromide (DHBPDB; C₂₄H₃₈Br₂N₂), 1‐heptyl‐4‐(4‐pyridyl)pyridinium bromide (HPPB; C₁₇H₂₃BrN₂), and 1,1′‐dis(p‐cyanophenyl)‐4,4′‐bipyridinium chloride (DCBPC; C₁₂H₈N₂OBr₂) for potential use in electrochromism applications were investigated. The repetitive stability of all of the EC cells could be improved through the addition of ferrocene as an electron donor (a counter redox material) to the electrolyte solution under several redox cycles. The experimental results demonstrate that the EC cell showed a reversible color change from clear (tintless) to three different colors with the application of electrochemical stimuli at specific potentials. The color of the EC cells turned red, green, or blue upon electrochemical reduction for DHBPDB, HPPB, and DCBPC in indium tin oxide sandwich‐type cells. Because of the different viologen molecules competing to capture electrons and affecting the EC efficiency and life of the multiviologen cells, they could be improved by the optimization of the working voltage in the multiviologen cells from the modification of an operative potential based on the cyclic voltammetry measurements. In this article, we propose a prototype device of multicolor electrochromic display, which provides potential application for multicolor electronic displays or EC paper. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40485.     

Effect of Ar/O2 ratio on double-sided electrochromic glass performance

This paper reports the qualities of WO₃ film and NiO film added to a counter electrode and their use in a double-sided electrochromic glass device. A mixture of argon and oxygen gasses with ratios of Ar/O₂ of 1.5, 2, 3, and 5 were used for the deposition of the working electrode of WO₃ film for EC glass. The structure of double-side EC glass consists of glass/ITO/NiO/electrolyte/WO₃/ITO/glass/ITO/WO₃/electrolyte/NiO/ITO/glass layers. The working electrode of WO₃ film controls the color presented, the applied voltage controls the color depth, and the counter electrode controls the transparency in the bleached state. The double-sided EC glass with double WO₃ films and double NiO films have faster coloration/bleaching rates than do single-sided EC glass. A mixture of Ar/O₂ ratio of 3.0 has the best coloration/bleaching property of the ratios tested. Compared to the single-sided EC glass, the double-sided EC glass has lower transmittance of about 72% and 6% than the 78% and 12% during coloration and bleaching states in the visible light region with +1.5 V and ?3.5 V applied.     

Preparation of a multicolored reflective electrochromic display based on monodisperse polymeric microspheres with N‐substituted viologen pendants

This article describes the preparation of multicolored reflective electrochromic displays (R‐ECDs) through the control of the substituents on viologen molecules. Cyanophenyl, salicylic, and alkyl groups were introduced onto 4,4′‐bipyridine. The synthesized viologen moieties were reacted with methyl chloride functional groups on polymeric microspheres, which were prepared by seeded polymerization. Then, R‐ECD cells were fabricated by the placement of a mixture of the viologen‐modified polymeric microspheres and an electrolyte between sandwiched indium tin oxide glasses. The R‐ECDs showed an inherent white background without potential because the micrometer‐range particles scattered the light, and the viologen was in a bleached state. From spectrophotometric results and visual appearances, it was confirmed that the devices showed red, green, and blue colors with respect to cyanophenyl‐, salicylic‐, and alkyl‐substituted viologen pendants when 2.7 V was applied to the device. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Neutral state colorless electrochromic polymer networks: Spacer effect on electrochromic performance

A series of carbazole-based monomers and their corresponding polymers with various spacer units were synthesized and coated onto ITO-glass surface via an electrochemical cross-linking process. All carbazole-based polymers exhibited multi-electrochromic behavior thanks to two separate oxidation processes. All materials were characterized by FT-IR, ¹H NMR, GPC, DSC, UV–vis, Florescence and CV. In addition, electrochromic properties of the cross-linked polymer films were investigated via spectro-electrochemical measurements. The colorless films were converted to yellowish green and greenish blue colors at the anodic regime. The results indicate that the spacer unit between the carbazole unit and the polymer backbone has a great impact on the optical and electrochemical properties and also on the electrochromic performance of these polymers. PVBEC with benzyloxy based spacer exhibits a high contrast ratio (ΔT% = 55 at 690 nm), a faster response time of about 2.1 s, a higher coloration efficiency (331 cm² C⁻¹) and a better stability (retains its performance by 94.3% even after 1000 cycles).     

Glass-ceramics produced from thin-film transistor liquid-crystal display waste glass and blast oxygen furnace slag

This study employed waste glass from thin-film transistor liquid-crystal displays (TFT-LCD) and slag from a basic oxygen furnace (BOF) to produce CaO–MgO–Al₂O₃–SiO₂ (CMAS) glass-ceramics through vitrification and further heat treatment of compacts of the obtained glass powders for densification and crystallization. CMAS glass-ceramics are known for their excellent mechanical and dielectric properties. MgO and Al₂O₃ were selected as modifying agents to ensure that the composition of the wastes featured these important characteristics.     

防指纹玻璃显示设备用有机硅压敏胶的粘接性能研究

系统地研究了交联剂用量、有机硅胶粘剂的厚度控制和铂金催化剂用量对不锈钢板和防指纹玻璃粘接性能的影响.研究结果表明:对于100份的防指纹玻璃显示设备用有机硅胶粘剂,添加0.6～1.49份交联剂能够优化防指纹玻璃显示设备用有机硅胶粘剂与不锈钢板和防指纹玻璃的粘接性能;当有机硅胶粘剂的厚度被控制在20～45 pm时,有机硅胶...     

Influence of metasurface pit structure on the anti-glare performance of display glass via high-throughput calculation

Recently more and more attentions have been drawn on the anti-glare property of display glass, which is directly related to visual health. However, it is still a big challenge to study the influence of the micron-size metasurface structure on the anti-glare property of glass by way of experiment. In this work, an ideal micron-size metasurface filled with uniform pits was firstly established on the display glass via the theoretical simulation. By using FDTD solutions software, the influences of the diameter (D) and depth (L) of the pits on anti-glare properties, such as reflectance and transmittance, electric field intensity distribution, energy flow density distribution, maximum reflection angle and maximum refraction angle, were investigated detailedly. Results show that a small size (less than 6 μm) of pits can promote the anti-reflectance, transmittance and anti-glare property of display glass. Meanwhile, when the diameter of pits matched well with the depth, namely D = 1/L = 0.3–0.4 μm, or D = 3/L = 0.6–1.1 μm, the color brightness and contrast of display glass were improved largely. The equivalent reflectance and equivalent transmittance can also be calculated at the wavelength of 200–1200 nm by using contour cloud map to find the optimal diameter and depth with good anti-glare performance. The distribution of electric field intensity and energy flow density at the specific wavelength which is equal or close to the size of the pits also help to illustrate the flash point position, and the short-range anti-reflection effect and long-range diffuse reflectance effect of metasurface pit structure. Specially, when the diameter is 3 μm and the depth is 0.6 μm, the maximum reflection angle is 113.8°, the maximum refraction angle is 138.6°, the equivalent reflectance is 3.58%, and the glass shows excellent anti-reflection and anti-glare properties, which make the display glass more comfortable and colorful.     

Recent advances in electrochromic polymers

Electrochromic polymers are attractive materials with enormous potential in the rapidly developing area of plastic electronics due to their flexibility, low-power consumption, ease of processing and low processing cost. Electrochromic devices created with electrochromic polymers are likely to be alternatives or supplements to the conventional inorganic electrochromic devices, which face challenges of durability and electrochromic properties. Several novel electrochromic polyimides, polyamides, and polynorbornenes prepared via polycondensation, ring-opening metathesis polymerisation (ROMP), etc., are introduced in this article. These various polymer species exhibit high thermal stability and mechanical strength.     

A new low-voltage-driven polymeric electrochromic

Design, synthesis, and properties of a novel donor-acceptor-donor type low-voltage-driven green polymeric electrochrome, P1, which is based on 8-(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-11-(2,3-dihydrothieno[3,4-b][1,4]dioxin-7-yl)acenaphtho[1,2-b]quinoxaline (1) are highlighted. It is noted that P1 has an ambipolar (n- and p-doping processes) character in 0.1 M tetrabutylammonium hexafluorophosphate/dichloromethane solution and switches to a transmissive blue state upon oxidation. Furthermore, this new polymeric electrochromic candidate exhibits high redox stability, high coloration efficiency and/or contrast ratio, high percent transmittance (%T) and low response time (1.0 s) with a band gap of 1.10 eV-1.25 eV.     

Ionic liquids in electrochromic devices

The ionic liquid (PYR₁₄TFSI) has proved to be the key material to make a Li-ion conducting element of a complete electrochromic device, when interposed between transparent film electrodes like WO₃ and Li-charged V₂O₅. The key features of this ionic liquid and its mixtures with LiTFSI are the excellent transparency in the visible and NIR optical regions, the good ionic conductivity and the electrochemical compatibility with inorganic Li-intercalation oxide thin film electrodes used in electrochromic devices. The higher optical contrast found during WO₃ colouration with PYR₁₄TFSI-LiTFSI, compared to that in a conventional non-aqueous electrolyte like PC-LiTFSI, was attributed to the larger inertness of the former one (no decomposition reaction at the lowest electrode potential). This highly conductive ionic liquid has been incorporated into a polymer matrix (P(EO)₁₀LiTFSI), in order to obtain a transparent solid electrolyte with high Li ion conductivity and good mechanical stability. Finally this solid PYR₁₄TFSI-P(EO)₁₀LiTFSI transparent ion conductor was interposed between the same electrodes as above in order to yield a fully solid-state, Li-ion electrochromic device. This new solid electrolyte was able to transfer reversibly a Li ionic charge between 5 mC cm⁻² and 10 mC cm⁻² from the lithium storage electrode Li_xV₂O₅ to the WO₃ electrochromic electrode in less than 100 s at room T, darkening the device from an initial 80% to a final 30% transmittance (at 650 nm). Such a device has been tested first under various constant current conditions, and later under potentiostatic control using ±2 V steps. The latter method allows not only for a faster response of the electrochromic system, but provides also an easier life stability test of the device, which withstood 2000 cycles with little changes in its optical contrast.     

Effects of ethylene-acrylic acid ionomer on thermomechanical and electrochromic properties of electrochromic devices using gelatin-based electrolytes

Transparent adhesive polymer electrolytes, to be used for fabrication of electrochromic glass via a lamination process, were developed from gelatin blended with ethylene-acrylic acid (EAA) copolymer ionomer resin. The gelatin-based electrolyte films were prepared by mixing the polymer with glycerol, LiClO₄, formaldehyde, and EAA in a microcompounder. The concentration effect of EAA (i.e., 2.5, 5, 10, and 20 wt% with respect to the gelatin) on thermomechanical, optical, and electrochemical properties of the prepared films were then studied. Results from atomic force micrographs revealed that surface roughness of the neat gelatin film significantly decreased after blending with 20 wt% EAA. This corresponds to the highest ionic conductivity value (4.46 × 10⁻⁶ S/cm) of gelatin-based electrolyte in this study. Percentage light transmittance was also maintained above 80%, provided that the concentration of ionomer was kept below 20%. Finally, performance of the electrochromic device with a configuration of ITO/WO₃/gelatin/NiO/ITO was demonstrated. Coloration efficiency and response time of 60.38 cm²/C and 10 s/50 s (coloring/bleaching) were achieved, respectively.     

Smart sunglasses based on electrochromic polymers

Smart sunglasses based on electrochromic polymers are proposed and developed in this study. This article discusses the design, processing, and the optical and electrical performance of a prototype smart sunglasses based on cathodic electrochromic (EC) polymers, which show several merits compared with traditional materials for sunglasses lens as well as other smart window materials. It is a multilayer design of device. The conjugated polymer, poly[3,3‐dimethyl‐3,4‐dihydro‐2H‐thieno [3,4‐b] [1,4]dioxepine] (PProDOT‐Me₂), is utilized as the electrochromic working layer. The counter layer of the device is vanadium oxide (V₂O₅) film, which serves as an ion storage layer. There is also a polymer gel electrolyte acting as the ionic transport layer, sandwiched between the working and counter layers. The characteristics of the prototype device are reported, including transmittance (%T), driving power, response time, open circuit memory, and lifetime. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

A simplified all-polymer flexible electrochromic device

New all-polymeric simplified electrochromic devices have been prepared based in an intrinsically conductive polymer, poly(ethylene dioxythiophene) (PEDOT). In these devices PEDOT acts simultaneously as electrochromic layer and current collector layer simplifying the construction of the classic devices from seven to five layers. The device presents a chromatic contrast in all the visible range with a maximum at 650 nm (ΔT=0.15) between 0 and 3 V. Representative bleaching and coloring times are 20 and 16 s, respectively, for  cm devices. The originality of this work is that advanced electrochromic devices can be constructed using commercially available materials and using simple experimental methods.     

Fast electrochromic response of ultraporous polyaniline nanofibers

Polyaniline (PAni) nanofibers were prepared by a one-step electrosynthetic method. A gold sputtered electrode was used as the substrate for the nanofiber growth at a constant current density value of 100 μA cm⁻². Substrate morphology induces fiber growing and allows having a remarkable quantity of fibers in a short period of time. Tandem chronoabsorptometric and chronocoulometric data of the electro-synthesis process were collected and analyzed. Several electrochromic parameters were characterized and a short response time (T₉₀) of 20 ms was obtained for a contrast (ΔT %) of 10%. The main reason for this fast response is the ultraporous nature of the prepared nanofibers. This approach represents a straightforward, easy and low cost method to obtain a fast color switching film with potential application in the deployment of an electrochromic device.     

Testing of electrochromic materials using symmetrical devices

“Symmetric materials” devices, where both electrodes are made of the same electrochromic materials, allow the in situ study of side reactions. Each transferred charge that is not used for the expected electrochromic reaction will cause a colour change in the whole symmetric device. Two electrochromic materials, WO₃ and IrO₂, are successively used to show how to obtain information about side reactions such as faradaic efficiency, reversibility and potential limits from the symmetric experiment. This in situ approach with a polymer electrolyte shows significant differences compared to results obtained with studies in aqueous electrolytes.     

A review of organic electrochromic fabric devices

Electrochromic fabric devices represent a further extension to the plethora of available literature on conductive fabrics. This article contains a brief overview of electrochromic devices, electrochromic polymers, conductive materials, conductive fabrics, and electrochromic fabric devices. A tabulated list of the perceived colour of a number of electrochromic polymers that is contained herein is designed to serve as an aide to colour mixing studies. The challenges of optimisation and commercialisatiion of electrochromic fabric devices and their mitigating factors are conjectured, along with some future potential applications for electrochromic fabric device technologies.     

Orange to green switching anthraquinone-based electrochromic material

An easily accessible anthraquinone-benzodithiophene-based high bandgap polymer (PTAq) was synthesized by Stille coupling reactions in remarkably high yield (96.5%). The highest occupied molecular orbital energy level of the polymer was estimated from the onset of oxidation in a cyclic voltammetry study to be −5.7 eV. PTAq showed an orange-to-green color switching with the application of a 1.0-V external potential to the polymer film, which was visible to the naked eye. The optical behavior change was also monitored using ultraviolet–visible absorption spectroscopy and revealed a respectable 75% transmittance change when the polymer film was subjected to a 1.0-V external potential. The high color contrast observed makes PTAq one of the most promising materials for electrochromic device applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47729.     

Polyaniline electrochromic devices with transparent graphene electrodes

Transparent, conductive and uniform graphene films have been prepared and used as electrodes of the electrochromic devices of polyaniline. Polyaniline films on both graphene and the widely used indium tin oxide (ITO) electrodes showed similar electrochemical and spectroelectrochemical properties. However, graphene electrodes exhibited much higher electrochemical stability than ITO in aqueous acidic electrolytes. The performances of the electrochromic devices with graphene electrodes exhibited slight decrease upon voltage switching while those of the devices with ITO electrodes decreased dramatically. After 300 cycles, the electrochromic devices with graphene electrodes showed much larger optical contrast and shorter switching time than those of the devices with ITO electrodes.