Exploration And Development Of Novel Viologen And Muti-functional Electrochromic Device

Electrochromic device (ECD) is a kind of device with functions of responsive discoloration and coloration through oxidation-reduction reactions by an appropriate driving voltage. ECD could adjust optical properties of the ultraviolet, visible or infrared region, and some can even show multi-level color through different voltages, which can be realized by selecting different electrochromic materials. Such devices can be used in building windows, the transport dimming devices or displays, in order to improve the working and living environment, to save energy. The small organic viologens were extensively researched, because of their good redox properties and stable color change process.This dissertation focused on how to improve properties of electrohromic devices based on viologens, and explore solid and liquid eletrochromic devices. Here, we designed and systhesised novel viologens, prepared matching electrodes, optimized structures of devices and measured the cycle life to prepare three kinds of electrochomic devices. And the contents include:Fast color changing ECD:We used electron-rich triphenylamine and phosphonate groups to modify viologen, thus the viologen molecule could be fixed on conductive glass substrate to form film electrodes through chemisorption between phosphonate groups and titanium dioxide. The as-prepared film electrode was applied to assemble a device with Prussian blue film. The device show fast color changing speed and good stability as a result of the modification and triphenylamine and phosphonate groups.Stable ECD:We used phosphonic acid to modify both asymmetric viologen triphenylamine materials, and prepared electrodes through chemisorption method. The similar morphology, molecule form and molecular concentration make that the electrodes can match with each other on color change, color change voltage and charge capacity. Using the above two electrodes an ECD was assembled, which exhibit the switching effect in the visible and infrared region, and high stable life.Liquid ECD:We searched for anion electrochromic materials as pairs with symmetric viologens dissolved in the solvent to assemble liquid ECD. The results showed that soluble electrochromic devices had vivid color changes. By comprehensive performance comparison, ferrocene was chosen as the counter material to assemble large area electrochromic device which showed good color change and uniformity color.In this paper, we designed and synthesized series of novel viologens, and prepared different electrodes through different methods for different structures, and assembled the solid and liquid viologen-based electrochromic devices with color changing speed less than1s or cycle life reach up to15,0000, thus to achieve its developments in multi-functions.