Tungsten oxide–cellulose nanocrystal composite films for electrochromic applications

Composite films of tungsten oxide and CNCs are prepared through a sol-gel method and their electro-chromic (EC) properties investigated. After mixing CNC gel into a tungsten oxide precursor solution, indium-tinoxide-coated glass substrates are dipped into the composite solution and subsequently annealed at 170 degrees C. The composite films consisted of CNCs dispersed in the tungsten oxide matrix. The resulting nanocomposite was found to be amorphous, exhibiting a high transmission modulation and very good cycling stability. After having tested a range of compositions, a film of WO3 with 10% CNC was found to be the most uniform and showed good EC performance. These results bode well for further work on CNC-EC composites for specific applications, especially when used on flexible substrates. c The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License.