The Synthesis Of Viologen Derivates And Solid Electrochromic Devices

Electrochromism can be defined as the phenomenon of the electrochromic material to undergo color reversible change upon oxidation or reduction, which was ensued from changing the potential applied. The reversible changes of the performances of the transmission, reflection and color of the electrochromic materials can be showed in appearance. Electrochromic(EC) materials are one of functional materials, which have very bright application future. It can be used widely in large-area display, light switch, unglaring viewfinder, deposited devices, building glass, smart windows and so on. Recently, electrochromic display combined with nano-technique is the most likely to be commercialized low cost electronic ink.The earliest reported electrochromic material is inorganic and it has been studied by domestic scholars for many years. The organic EC materials were rising abroad in recent years and the research of viologen for EC material seldom reported domestically. We have synthesized the viologen derivatives monomer by reaction between halogenated hydrocarbon and 4,4'-bipyridine: 1-ethyl-1'-(4-vinylbenzyl) -4,4'-bipyridinium chloride and iodide (EVBCI), 1-allyl-1'-ethyl-4, 4'-bipyridinium bromide and iodide (AEBBI), 1, 1-diallyl-4, 4'-bipyridinium dibromide (DBDB). And their corresponding polymers were also synthesized by copolymerization: copolymerization between styrene, acrylic acid, butyl acrylate and 1 -ethyl- 1'-(4-vmylbenzyl)-4,4'-bipyridinium chloride and iodide (CPSABE), trunk polymerisation between 2-chloroethyl chloroacetate and 4, 4'-bipyridine (TPCCB). The structure and properties of these compounds were tested by NMR, IR, UV, CV and so on. With polyelectrolyte as ionic conduction layer, the transparent solid EC device (TSECD), reflecting solid EC device (RSECD) and flexible solid EC device (FSECD) based on these compounds were assembled with structure: ITO glass (or ITO-PET) | EC or EC+ carrier | polyelectrolyte (PE) | ITO glass (or ITO-PET). The thickness of TSECD and RSECD was about 2.3 mm, and the thickness of FSECD was about 0.5 mm. The technique of solidification device is much easier and true of producing on a large scale. When charged voltage in 1.1 V to 3 V, they showed blue or violet. After optimization, their response time was less than 100 ms, the number of red-ox circulation was over million times and the color of colorization could be kept for 3 days. The main indexes of this kind of device can meet the demand of electronic ink. The RSECD with high contrast can make use of printing technique. Comparing with luminiferous displays' high energy cost and strong radiation, the electrochromic electronic paper displays cost less energy and have no radiation. For the purpose of multicolor, the other electrochromic materials have also been studied, such as anthraquinone, p-phenylene diamine.