Synthesize And Electrochromic Research Of The Hexagonal Tungsten Bronze Nanomaterials Layer-by-Layer Self-Assembly Films

Electrochromic is a part of color changing family, it relate to the absorption of visible light. Being activated by electronic signal, the electrochromic materials could change their macroscopical color. For a long time, people want to utilize the chemically electrochromic materials into commercial display devices, but some limitations of these materials prevent their applications. These limitation including: low switch speed, limitation in color range, stability, et. al.In recent year, the development of the nanotechnology provides some solution to solve these limitations. In this paper, we focus on the preparation of the hexagonal tungsten bronze nanomaterials film and it's Electrochromic property. First, we synthesize Hexagonal Tungsten Bronze nanomaterials by low temperature hydrathermal method. The result nanomaterials are mostly nanorods, length is at 150-250nm and diameter si about 20-40nm. For film assembling, we disperse the hexagonal tungsten bronze nanomaterials in collide solution. The nanomaterials absorb the charged ion in the solution, and could be assembled by layer-by-layer self assembly method in to multilayer thin film under electrostatic interaction. Though this route line, we synthesized Mo, Fe, Cu doped hexagonal tungsten bronze nanomaterials film with PEI as polyelectrolytes. Finally, we built up hexagonal tungsten bronze and TiO₂ all nanomaterial films by assembly these materials which were absorbed opposite charged ion on the hexagonal tungsten bronze nanorod and TiO₂ nanoparticle, respectively.After the detail research on these films, we found that all these films were well assembled, and still maintain their physical and chemical property. [Moo.o5-HTB/PEI]4 films display good electrochromic activity. On the oxidation status, the films were bleach. By adding negative potential, the films turn to light blue, and finally dark blue. The color contrast and electrochromic efficiency are very high, and the switching speed are faster than most of the electrochromic films which were reported. Further more, the films are very stable, can go through many times of reaction without contrast and efficiency lose. As the second step of the research, the Fe and Cu doped HTB films expand the color range from bleach-blue to orange-light blue-dark blue and yellowgreen-blue without obvious depression of color contrast, electrochromic efficiency, switching speed, and stability. The research on the [HTB/TiO₂]₄ all nanomaterials films shows ignificant development on every important property. The switching speed are increase about 30%, the contrast increase 14%, the efficiency increase about 12%. The films stability are increased largely. Not only corrosive environment and thousands times switch reaction but also high temperature treatment can not decrease the films' electrochromic property obviously. Further more, the layer thickness produce antireflection effect, which was very useful for electrochromic devices working under high lightness environment.