Fluorene based organic dyes for dye sensitised solar cells: structure–property relationships

Dye sensitised solar cells (DSSCs) have received immense attention in recent years as they offer the possibility of low cost conversion technology of light energy to electrical energy. Organic dyes have been demonstrated as sensitisers in DSSCs with promising photoelectrical conversion efficiencies. Though several polyaromatic hydrocarbon based organic dyes have been developed for use in DSSC, dipolar compounds featuring a fluorene unit have shown promising potential as light harvesting component. In this review, we present a comprehensive survey of the organic dyes containing fluorene either in the donor part or as a π linker in the conjugation pathway in a conventional donor–π–acceptor molecular configuration. Structural features of the molecular materials were correlated with the functional properties, such as optical absorption and oxidation potential.