Preparation And Characterization Of Electrochromic Nanocomposites

Electrochromic composites have attracted more and more attention from researchers because of their larger specific surface area,smaller band gap and direct electron transport path.Loading with organic or inorganic materials is the basic method of improving properties of pure electrochromic materials.In this thesis,viologen-ZnO,ZnO@NiO,viologen-TiO₂,NiO-Ag etc.were prepared by using,among others,the hydrothermal,chemical deposition,and water deposition methods.The corresponding characteristics and device properties were then tested.Details are as follows:?1?ZnO nanotubes?nanorods?array were prepared by the hydrothermal method,and then were modified by small organic molecules?methyl-viologen?to obtain two kinds of electrochromic composites.The experimental results demonstrate that the ZnO nanotube arrays have larger specific surface area than that of ZnO nanorod arrays.Zn O nanotube arrays can therefore adsorb more organic small molecules,and more electrochromic materials are engaged in the reversible reduction-oxidation process,improving the electrochromic properties.?2?ZnO@NiO core-shell structure composites were prepared by the hydrothermal and chemical deposition methods,which show better electrochromic properties compared with pure NiO electrochromic film.ZnO@NiO core-shell composites have a relatively smaller band gap,which is more favorable for ion/electron injection and extraction in electrochromic layer.Thus,the electrochromic optical modulation range,response speed and coloration efficiency are enhanced.?3?Different thickness of TiO₂ nanorod array films were prepared by the hydrothermal method on FTO glasses,and then the viologen-TiO₂ EC devices were assembled.In this part,the influences of the thickness of the TiO₂ nanorod array film and the operating voltage of the electrochromic devices are investigated.?4?NiO-Ag electrochromic composites were prepared by the chemical deposition and photo deposition methods.Ag nanoparticles can improve the electrochromic properties of NiO-Ag electrochromic devices.The excellent conductivity of Ag nanoparticles promotes the transmission of electrons in the working electrode,which improves the response speed of the electrochromic devices.In addition,the flexible all solid state NiO-Ag electrochromic devices are also explored.