We demonstrate the benefit of home-made nanopowder precursors on the electrochromism of V 2 O 5 films deposited by the "Doctor Blade" method. Using the polyol process, nano-structured V 2 O 5 powder were synthesized. Orthorhombic V 2 O 5 thin films deposited from as-synthesized powder exhibit good cycling stability associated with significant reflectance modulation in both lithium and sodium based electrolytes. The orange to green reversible color change appears well suitable for display application. To conclude, the electrochromic performances of complete devices using WO 3 as complementary electrode and 0.3 M Lithium Bis(Trifluoromethanesulfonyl)Imide LiTFSI in BMITFSI plastified with polymethylmetacrylate (PMMA) membrane electrolyte are reported.

Novel design of electrochromic devices (ECDs) known for their ability to modify optical properties under an applied voltage, based on a minimization of the number of layers is reported. The use of a metallic electrode, playing the role of both the conductive layer and the counter electrode, allows us to simplify the assembly of a commonly five-layer battery-type device to four-layer ECD. Further minimization of the number of layers is achieved using a conductive and electrochromic material. The novelty of the device configuration is illustrated using poly­(3,4-ethylenedioxythiophene) (PEDOT)-based materials as EC layer, lithium-based ionic liquid as electrolyte, and Ag as counter electrode. Such a four- or three-layer ECD deposited on paper substrate switches from light to deep blue in a narrow 0.7 V voltage window. Preliminary investigations of the mechanism indicate traces of Ag on the PEDOT layer upon cycling. Finally, the printed ECD is successfully activated using a mobile phone.