A new multilayer electrochromic device has been constructed according to the following pattern: glass1/ITO/WO3/gel electrolyte/BP/ITO/glass2, where ITO is a transparent conducting indium tin oxide film having the surface resistance equal to 8-10 Ω. Tungsten oxide (WO3) films were two-stage electrodeposited from the solution of sodium tungstate. To obtain a double layer, WO3 film was first crystallized by annealing in the air at a temperature of 450°C for 1 hour, and subsequently, another WO3 film was electrodeposited on it and annealing in the air at a temperature of 300°C for 1 hour. Obtained films had double layer structure: crystalline and amorphous/crystalline. Electrodeposited thin layer of prussian blue (PB) was a storage electrode of the device. A new gel electrolyte guaranteed high conductivity (σ = 4.8 mS•cm-1). It consisted of 38% EC, 38% PC, 8% LiCF3SO3, 10% PMMA, 6% PEO, THF, where PMMA - polimethylmetacrylate, and poly(ethylene oxide)PEO - based polymers electrolytes, containing lithium triftalate - LiCF3SO3 and using mixed solvent of propylene carbonate (PC) + γ-butyrolacton (γ-BL).
The electrochromic devices obtained in the research are characterized by considerable transmittance variation between coloration and bleaching state (25-40% at applied voltage of 1.5 to 3 V), and also high coloration efficiency (above 100 cm2C).