Abstract
A tungsten trioxide (WO~3~)/tris(2,2′‐bipyridine)ruthenium(II) ([Ru(bpy)~3~]^2+^; bp__y__=2,2′‐bipyridine)/poly(sodium 4‐styrenesulfonate) (PSS) hybrid film was prepared by electrodeposition from a colloidal triad solution containing peroxotungstic acid (PTA), [Ru(bpy)~3~]^2+^, and PSS. A binary solution of [Ru(bpy)~3~]^2+^ and PTA (30 vol % ethanol in water) gradually gave an orange precipitate, possibly caused by the electrostatic interaction between the cationic [Ru(bpy)~3~]^2+^ and the anionic PTA. The addition of PSS to the binary PTA/[Ru(bpy)~3~]^2+^ solution remarkably suppressed this precipitation and caused a stable, colloidal triad solution to form. The spectrophotometric measurements and lifetime analyses of the photoluminescence from the excited [Ru(bpy)~3~]^2+^ ion in the colloidal triad solution suggested that the [Ru(bpy)~3~]^2+^ ion is partially shielded from electrostatic interaction with anionic PTA by the anionic PSS polymer chain. The formation of the colloidal triad made the ternary [Ru(bpy)~3~]^2+^/PTA/PSS solution much more redox active. Consequently, the rate of electrodeposition of WO~3~ from PTA increased appreciably by the formation of the colloidal triad, and fast electrodeposition is required for the unique preparation of this hybrid film. The absorption spectrum of the [Ru(bpy)~3~]^2+^ ion in the film was close to its spectrum in water, but the photoexcited state of the [Ru(bpy)~3~]^2+^ ion was found to be quenched completely by the presence of WO~3~ in the hybrid film. The cyclic voltammogram (CV) of the hybrid film suggested that the [Ru(bpy)~3~]^2+^ ion performs as it is adsorbed onto WO~3~ during the electrochemical oxidation. An ohmic contact between the [Ru(bpy)~3~]^2+^ ion and the WO~3~ surface could allow the electrochemical reaction of adsorbed [Ru(bpy)~3~]^2+^. The composition of the hybrid film, analyzed by electron probe microanalysis (EPMA), suggested that the positive charge of the [Ru(bpy)~3~]^2+^ ion could be neutralized by partially reduced WO~3~^−^ ions, in addition to Cl^−^ and PSS units, based on the charge balance in the film. The electrostatic interaction between the WO~3~^−^ ion and the [Ru(bpy)~3~]^2+^ ion might be responsible for forming the electron transfer channel that causes the complete quenching of the photoexcited [Ru(bpy)~3~]^2+^ ion, as well as the formation of the ohmic contact between the [Ru(bpy)~3~]^2+^ ion and WO~3~. A multicolor electrochromic performance of the WO~3~/[Ru(bpy)~3~]^2+^/PSS hybrid film was observed, in which transmittances at 459 and 800 nm could be changed, either individually or at once, by the selection of a potential switch. Fast responses, of within a few seconds, to these potential switches were exhibited by the electrochromic hybrid film.