Ullazine Donor-π bridge-Acceptor Organic Dyes for Dye-Sensitized Solar Cells.

A series of four ullazine-donor based donor-π bridge-acceptor (D-π-A) dyes have been synthesized and compared to a prior ullazine donor-acceptor (D-A) dye as well as a triphenylamine donor with an identical π-bridge and acceptor. The D-π-A ullazine series demonstrates an unusually uniform-in-intensity panchromatic UV/Vis absorption spectrum throughout the visible region. This is in part due to the introduction of strong high-energy bands through incorporation of the ullazine building block as shown by computational analysis. The dyes were characterized on TiO2 films and in DSC devices. Performances of 5.6 % power conversion efficiency were obtained with IPCE onsets reaching 800 nm.