Utilization of natural carotenoids as photosensitizers for dye-sensitized solar cells

The dye-sensitized solar cells (DSCs) were assembled by using natural carotenoids, crocetin (8,8′-diapocarotenedioic acid) and crocin (crocetin-di-gentiobioside), as sensitizers and their photoelectrochemical properties were investigated taking a presence or absence of carboxylic group in the dye molecule into consideration. In these carotenoids, crocetin that has carboxylic groups in the molecule can attach effectively to the surface of TiO₂ film so that it performed the best photosensitized effect resulting in the short-circuit photocurrent with 2.84 mA under irradiation of 1.0 cm². On the other hand, crocin that has no carboxylic group in the molecule showed lower photoelectrochemical performance because of its lower affinity to the surface of TiO₂ film. These results indicate that it is possible to apply carotenoid as sensitizers for DSCs at the presence of effective function groups.