Abstract: A prototype of the all solid state WO₃/NiO complementary electrochromic device was designed and manufactured on the basis of the inverstigation on the ionic conductivity of polyethylene glycol gel eletrolyte doped with lithium erchlorate
and propylene carbonate, and the Li⁺ ion intercalation performance of sputtered nickel oxide and tungsten oxide thin films.
The electrochromic performances of the devices were studied by cyclic voltammetry and spectrophotometry. The results ndicated that the laminated WO₃/PEG-LiClO₄-PC/NiO complementary electrochromic devices have excellent electrochromic characters in
vis-nir region with the transmittance 0.70 in the bleached state at 600nm and 0.20 in the colored state.

Key words: all-solid-state electrochromic device, tungsten oxide thin films, nickel oxide thin films, smart window