Photosensitization of nanocrystalline TiO2 thin films by a polyimide bearing pendent substituted-Ru(bpy)3+2 groups

Under visible illumination, a thin film of nanocrystalline TiO2, coated with an adsorbed substituted-Ru(bpy)(3)(+2)-labeled polyimide 1 produces a sensitized photocurrent when spin-coated on a conductive ITO support. The magnitude of the observed anodic photocurrent defines the efficiency of charge injection from the adsorbed dye to the nanoparticle and of interparticulate electron hopping to the conductive support. Power characteristics and photocatalytic activity of the sensitized him have been investigated. Laser flash photolysis at different applied potentials produces transient absorption spectra that have been analyzed as multicomponent charge injections. Lifetime measurements permit a characterization of the efficiency of electron migration across the semiconductor film. The polymeric dye is also shown to be an effective photosensitizer in inducing the catalytic oxidative decomposition of methylene blue. (C) 1998 Elsevier Science S.A. All rights reserved.