Abstract: Asymmetric dyes of the D-?-A type have the Formula (1), including the valence tautomers thereof. The dyes of Formula (1) are suitable for use in dye-sensitized solar cells (DSSC), in photoelectrochemical devices or in photonic devices. A solar cell and a device for photoelectric conversion contain an asymmetric dye of Formula (1). The dyes of Formula (1) are also suitable for conjugating with optically active nanoparticles (NP).