Room Temperature UV treated WO3 thin films for electrochromic devices on paper substrate

•Room Temperature Deposition of WO3 thin films on paper substrate.•UV irradiation of WO3 nano particles.•Electrochromic Performances in ionic liquid electrolyte.

Successful preparation of tungsten oxide thin films on paper substrate, using a novel room temperature deposition method involving the connection of tungsten oxide nanoparticles by UV-irradiation, is reported. WO3 thin films, prepared from synthesized monoclinic WO3 powder as compared to commercial ones, show higher electrochemical activity and good cycling stability in 0.3 M trifluoromethanesulfonimide (HTFSI) in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMITFSI) ionic liquid electrolyte versus Pt as counter electrode. Electrochromic performances of complete devices using Prussian Blue (PB) as complementary counter electrode and 0.3 M Lithium Bis(Trifluoromethanesulfonyl)Imide LiTFSI in BMITFSI plastified with polymethylmetacrylate (PMMA) membrane electrolyte are associated with a contrast in reflectance of 13%, from a yellow to a blue color.