Color Switchable Goggle Lens Based on Electrochromic Polymer Devices
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Color Switchable Goggle Lens Based on Electrochromic Polymer Devices Chao Ma and Chunye Xu1 1 Center of Intelligent Materials and Systems, University of Washington, Box 352600, Seattle, WA 98115, E-Mail:[email protected] ABSTRACT We have developed a set of new electrochromic devices (ECDs) for special application goggles, whose color can be switched between transparent and a specific color mode, i.e. blue (B). This paper will discuss the design, film deposition, device assembly and characterizations of the color switchable lens. The ECD is composed of a layer of thin film conducting polymer poly (3,4-(2,2-dimethylpropylenedioxy)thiophene) (PProDOT-Me2), a layer of thin film inorganic oxide V2O5-TiO2, and a layer of ionic conductive electrolyte. The thin films are electrochemically deposited on ITO coated flexible plastic substrate. The whole device is packaged with an UV cured flexible film sealant. The goggle lens exhibit tuneable shade in visible light wave length (380-800nm), with a maximum contrast ratio at 580nm. Meanwhile, other unique properties include fast switching speed, low driving voltage, memory function (no power needed after switching, bistable), great durability, high flexibility, light weight, and inexpensiveness. INTRODUCTION Today people have known more and more about the sun’s harmful effects on the eyes. Long exposure to sun light may cause diseases such as cataracts, macular degeneration, and photokeratitis [1, 2]. Mean while unexpected glare, flash and varied light conditions are always safety issues faced by people activating outdoors, including motorcycle riders, truck drivers, and even soldiers. A smart, color switchable eyewear is highly demanded here, which can exhibit different light transmittance instantly upon user’s command or changing environment. The requirement has been beyond the ability of traditional materials for sunglasses or goggles. They have only one fixed color state and the transparency is uncontrollable. Existing color switchable eyewear products on the market, manufactured by Uvex Inc. or Corning Inc., are based on liquid crystal devices (LCDs), or photochromic devices [3-6]. LCDs are capable of switching quickly and perform reasonable high light transmission range, but their disadvantages are also obvious: high operation voltage, complex manufacturing, lack of memory function, and limited color availability. Photochromic devices rely on specific chemical reaction and are activated by UV light. However, photochromic materials based eyewear only reacts to UV irradiation not to visible light. One awkward example is when you sit in a car. Because the wind shield blocks out most of the UV light, photochromic devices will not work inside the car. In addition, the color switching speed is too slow to satisfy fast pace activities. Electrochromic (EC) materials can change their optical properties reversibly for an applied potential due to electrochemical oxidation and reduction. Electrochromic devices (ECDs) which are able to actively control light transmit
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