Sensitization of niobium pentoxide thin films by cis-dithiocyanate (2,2-bipyridyl-4,4 ' dicarboxylic acid) ruthenium(II) complex

The sensitization caused by the adsorption of a ruthenium complex in a niob ium thin film (d < 300 nm) was analysed by photoelectrochemical measurement s. The films were coated on a indium-tin-oxide (ITO) conductor glass by a d ip-coating technique. The non-sensitized him had only photoelectrochemical current in the UV region (i <less than or equal to> 40 nA). The sensitizati on of the film by cis-dithiocyanate (2,2-bipyridyl-4,4'dicarboxylic acid) r uthenium(II) complex altered the shape of the non-normalized action spectru m with the presence of photoelectrochemical current in the visible range (l ambda greater than or equal to 400 nm). This photoelectrochemical current ( i less than or equal to 70 nA) was associated with electron injection into the niobium pentoxide conduction band due to metal-to-ligand charge-transfe r (MLCT) of the ruthenium complex. The shape of the action spectrum in the UV range (lambda less than or equal to 400 nm) changed with the application of an electric potential to the film surface and the photoelectrochemical current associated with the ligand-to-metal charge transfer of niobia film decreased for higher ruthenium concentration.