Study On Preparation And Properties Of The Organic-Inorganic Doped Nano-sized Composite Electrochromic Thin Films

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. The electrochromic materials can be classified as anodically colored and cathodically colored materials by electrochemical reaction modes. Electrochromic(EC) materials are one of functional materials, which have very good application future. It can be used widely in large-area display, light switch, unglaring viewfinder, deposited devices, building glass and smart windows. The application of electrochromic materials as the electronic link was also been reported in recently.At present, the investigation about this aspect is focused on the pure inorganic cathodal electrochromic materials as WO₃ and organic electrochromic materials as and Polyaniline and viologens. But for the organic-inorganic doped electrochromic materials, the research is very lack.Aim to the application purpose of all-solid state electrochromic device and electronic link materials, which are prepared on flexible substrate. The tungstenic acid sols doped with PEO, MoO₃ and the PEO6000 nano-sized composite Ni(OH)₂ sols were prepared by ionic- changing and alcohol salt hydrolyzing technology of sol-gel method. The films were deposited on ITO/glass and ITO/PET by spin-coating method. The organic-inorganic doped nano-composite electrochromic thin films were gained through annealing at different temperatures. The influence of the components of sols on formation and stability of films was investigated. The optimum examination condition was gained in our lab. XRD, FT-IR, TG-DSC and SEM investigated the structure evolution and surface pattern of the doped electrochromic films during annealing. The optimum annealing temperatures of thin films on different substrate were gained. The performance of electrochemistry, responding time, circular stability, optical transmittance and open circuit memory time were tested by cyclic voltammetry, constant voltage and UV-VIS spectrometer.From the experiment, it is found that the optimum sol is very stable which can be stored more than one month at temperature. Doping of MoO₃, PEO also improves the stability of sols, the optical and electrochromic performance of the materials. The thin films which were annealed at 200℃2h on ITO/glass and 160℃2h on ITO/PET showed excellent photoelectric performances and colored efficiency. Doping of PEO also improves the stability of Ni(OH)₂ sols and electrochromic performance, controls the size of crystal. The thin films annealing at 350℃1.5h on ITO/glass showed excellent electrochromic performance.