PHOTOSENSITIZATION OF COMPOSITE METAL-OXIDE-SEMICONDUCTOR FILMS

New approach of surface modification consisting on mixing SnO2 and TiO 2 colloids and packing them as a composite film (SnO2-TiO2) on a condu cting glass surface has led to the increased sensitized photocurrent q uantum yields. The photoinjected electrons from the sensitizer into Ti O2 are quickly transferred into lower lying conduction band of SnO2 ca rriers thus promoting the charge separation. High internal photocurren t quantum yield for CdS film as sensitizer, approaching unity (Phi = 9 5%), has been obtained. In addition, composite SnO2-TiO2 nanocrystalli ne films improve the charge separation in adsorbed 2,2'-bipyridine)(2, 2'-bipyridine-4,4'-dicarboxylic acid) ruthenium complex (Ru(II)) too. Higher internal photocurrent quantum yield (Phi = 92%) has been obtain ed for Ru(II) by replacing SnO2 carriers against composite SnO2-TiO2 p articles in the film. On the other hand, the later composition does no t show any increase in the photovoltage.