Novel organic dyes for photovoltaic applications

Dye-sensitized solar cells (DSC) recently attracted much attention as promising devices for the conversion of sunlight in electric power.[1] Such cells employ dyes, which act as photosensitizers, together with a suitable inorganic semiconductor, such as TiO2. Historically, the first class of photosensitizers employed in DSC was represented by transition metal complexes, such as the Ru-bipyridyl complex N719.[2] More recently, purely organic sensitizers, not containing any metal atom, have emerged as a cheap and efficient alternative.[3] Such substances are often based on a "donor-?-acceptor" architecture, featuring electron-donating and electron-accepting groups separated by a conjugated spacer. Here, we will present some of the dyes recently prepared in our laboratories, whose general structure (1) is shown in the figure. The synthesis of these compounds will be described together with the results of preliminary experiments conducted on test cells containing the novel sensitizers. [1] Hagfeldt, A.; Boschloo, G.; Sun, L.; Kloo, L.; Pettersson, H. Chem. Rev. 2010, 110, 6595. [2] (a) O'Regan, B.; Grätzel, M. Nature 1991, 353, 737 [3] (a) Mishra, A.; Fisher, M. K. R.; Bäuerle, P. Angew. Chem. Int. Ed. 2009, 48, 2474. (b) Ooyama, Y.; Harima, Y. Eur. J. Org. Chem. 2009, 2903.