PYRIDINE CARBOXYLATE DERIVATIVES AS ACCEPTOR GROUPS IN SENSITIZERS FOR DSSCs

In recent years, metal-free organic sensitizers for dye-sensitized solar cells (DSSC) have been shown to have reached an interesting level of efficiency, while not having all the problems associated with the presence of a metal. Often these sensitizers have a "donor-?-acceptor" (D-?-A) architecture, where the acceptor groups is also involved in the interaction with titanium oxide[1]. In many cases, the acceptor/anchor group is a cyanoacrylate moiety but recently acceptors with different structural features, such as pyridine carboxylate, have been reported[2,3]. In this work, different dyes with a pyridine portion as acceptor group were synthesized and characterized, varying the position of the carboxyl group and the D-? group in the pyridine moiety. The isomers prepared showed significant differences both in absorption/emission spectra and in TiO2 up taking. Significantly insertion of appropriate substituents on the pyridine ring might be possible allowing to tune the optical properties of the dyes. Acknowledgements: We thank Regione Toscana for financial support of the FOTOSENSORG project, Prof. M. Bruzzi, Dr. R. Mori and Dr. A. Baldi, Dipartimento di Ingegneria Industriale, Università di Firenze, for cells efficiency measurements. [1] Hagfeldt, A.; Boschloo, G.; Sun, L.; Kloo, L.; Pettersson, H. Chem. Rev. 2010, 110, 6595. [2] Delcamp, J. H.; Yella, A.; Nazeeruddin, M.K.; Graetzel, M. Chem. Comm. 2012, 48, 2295 [3] Cheng, M.; Yang, X.; Li, J.; Chen. C.; Zhao, J.; Wang, Y.; Sun, L. Chemistry- A Eur. J. 2012, 18, 16196