Electro-optical properties of new anthracene based organic dyes for dye-sensitized solar cells

Dipolar compounds containing anthracene-based triarylamine donor and cyanoacrylic acid acceptor were synthesized and characterized by electro-optical measurements. The optical spectra of the dyes are dominated by a charge transfer transition. This band is red-shifted and increased in intensity on elongation of conjugation by the introduction of bithiophene or dithienylbenzothiadiazole moiety. Similarly, the oxidation potentials of the dyes are shifted anodically on extension of the conjugation attributable to the reduction in the interaction between the triarylamine and acceptor segments. Theoretical calculations revealed the charge transfer to occur between anthracene and triarylamine moieties. However, in the benzothiadiazole containing dye the charge transfer is observed between the amine and the acceptor segment. Dye-sensitized solar cells fabricated using these dyes showed moderate efficiency which is highly dependent on the nature of the conjugation bridge.