Photoelectrochemical studies of nanocrystalline TiO2 co-sensitized by novel cyanine dyes

Abstract Pentamethylcyanine derivative (A), trimethylcyanine derivative (B) and their mixtures (AB) were used as sensitizers in nanocrystalline TiO 2 solar cells to improve photoelectric conversion efficiency. It was found that the aggregates of the cyanine dyes were efficient in light harvesting and that the mixture of A and B could be employed to sensitize the solar cell over the entire visible spectrum. The sensitizing properties of three mixed dyes with different A-to-B ratio were systematically studied, and it was found that A1B3 (A:B=1:3 V/V)-sensitized solar cell generated the highest photoelectric conversion yield of 3.4%. The effect of co-adsorption of A and B on their aggregation behavior and photosensitization was also investigated. Co-sensitization was found to suppress the aggregation and affect the sensitization performance profoundly.