Search

• Flexible multicolor electrochromic tape based on steel foil electrodes and "inverted sandwich" geometry. • Good response time, with a sharp contrast between bleached and tinted states. • Ability to present single or mixed color response. • Ability to withstand compression higher than 30 MPa. Electrochromic devices (ECDs) have the ability to selectively change color under the influence of electric current or potential and can keep the selected color after disconnection. They are used as smart windows, e-ink displays and even as flexible tapes. Most multicolor ECDs incorporate traditional "sandwich" architecture, which requires at least one electrode to be made of a transparent conductive polymer or thin film ceramics, and can be quite fragile and sensitive. In this paper, a flexible and durable multicolor ECD tape is reported, which uses advanced architecture, steel foil electrodes, and multiple coloration systems, for example intercalation used in tungsten and vanadium oxide based electrochromic systems, as well as a redox dye, for example methyl orange. The presented ECD tapes can utilize different metal oxides and color mechanisms with coloration efficiency around 10 cm2 C−1 for V 2 O 5 and WO 3 in both visible and IR range, and more than 30 cm2 C−1 for ZnO with added methyl orange dye. Due to the use of stainless-steel foil as a substrate, the assembled ECD tape has excellent durability properties, withstanding more than 39 MPa of pressure, and could therefore be used even in the most adverse conditions, for applications such as adaptive camouflage, color changing clothes, or other applications [ABSTRACT FROM AUTHOR]

A new type of electrochromic device that uses electrodeposition of lead(II) oxide in combination with hydrogel-stabilized water-based electrolyte has been investigated. Operation of selected devices was examined using a series of electrochemical techniques (cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy), along with UV–Vis transmittance spectroscopy. Presented devices with use of electrodeposited PbO from aqueous solution exhibited very short response time of 15 s. Data obtained from experiments showed high difference between bleached and tinted state while low potential required for color change (+1.7 V). All tested devices were unsealed and performed electrochromic effect for several cycles with unchanged repeatable cycling ability. Best characteristics, achieving good repeatability, high transmittance in bleached state and good coloration in tinted state, along with good stability, were obtained with device using a cross-linked random copolymer hydrogel N,N -dimethylacrylamide (DMAM) and N -isopropylacrylamide (NIPAM) with a 85:15 unit molar ratio (DMAM/NIPAM), in combination with water-based Pb 2+ /Ni 2+ electrolyte and PbO as working electrode and NiO as counter electrode. Constructed devices showed stable color in tinted state and ability to self-bleach when short-circuited. This type of electrochromic cells could be used as a more time-stable and lower cost alternative for existing intercalation-type electrochromic devices. [ABSTRACT FROM AUTHOR]

A novel method of preparation of electrochromic cells with a cobalt(II) or iron(II)-tris-2,2′-bipyridine hexafluorophosphate dye adsorbed on a titanium dioxide coated electrode and platinum or nickel oxide thin coated counter-electrode in conjunction with quasi-solid state LiClO 4 based electrolyte is presented. The operation of the cells was analyzed using cyclic voltammetry as well as by UV–vis reflectance and transmittance spectroscopy. The transition times between the tinted and bleached states are of the order of one second, while the difference between both states is clearly visible. Best characteristics were obtained with the cobalt bipyridine hexafluorophosphate complex dye adsorbed on a mesoporous TiO 2 electrode in combination with NiO counter-electrode. Devices created according to the described method could potentially be used to recycle and re-use exhausted dye-sensitized solar cells for transparent smart windows, or as a new type of displays. [ABSTRACT FROM AUTHOR]

• Flexible electrochromic tape based on aluminum foil electrodes and "inverted sandwich" geometry. • Good response time (5 s for tinting) with sharp contrast between bleached and tinted state. • Ability to operate at high compression of 200 kg/cm2 (19.6 MPa). • 2 mm wide tape with 10 µm thick Al electrodes was able to endure force of up to 5.5 N and still operate normally. • The device is constructed from "kitchen grade" aluminum, greatly reducing cost compared to traditional "sandwich geometry" devices that use conductive polymer or ceramics. Electrochromic devices (ECDs) have the ability to selectively change their color state. They come in many forms, such as smart windows, e-ink displays and recently even as flexible tapes. Since most of ECDs incorporate traditional "sandwich" architecture, which requires at least one electrode to be made of a transparent conductive polymer or thin film ceramics, they are considered too expensive and fragile compared to devices made from metal or alloy foils. For the first time, we present a true low-cost, flexible and durable ECD tape that uses a common "kitchen-grade" aluminum foil for electrodes, while employing a Li-WO 3 intercalation based electrochromic system. The presented ECD tape is capable of showing two color states. The tested tapes were up to 20 cm long but could be easily made longer due to their "inverted sandwich" architecture. Due to the absence of transparent counter electrode, the assembled ECD tape has excellent durability properties and could be used in color changing clothes, adaptive camouflage or other applications. [ABSTRACT FROM AUTHOR]

Intercalation of lithium ions into the crystal lattice of tungsten trioxide is one of the most researched electrochromic mechanisms. Conventional electrochromic devices (ECDs) utilize electrodes made of thin layer coatings of WO 3 on optically transparent conductive polymer or metal oxide substrates. A majority of Li + - WO 3 based ECDs is built in the so-called "sandwich" configuration, where the optically transparent electrode (OTE) is placed directly on top of the Li + -based electrolyte which separates it from the counter electrode. It is shown here that stainless steel foils can replace conventional electrode substrates with the advantage of higher electrical conductivity and mechanical flexibility. In addition, the so-called "inverted sandwich" ECD architecture is introduced which allows for fabrication of devices without the use of at least one OTE. Electrochromic tape with two stainless steel based electrodes, coated with WO 3 and pencil lead carbon, is presented and characterized both electrochemically and optically. [ABSTRACT FROM AUTHOR]