Electronic tuning effects via pi-linkers in tetrathiafulvalene-based dyes

Four new tetrathiafuIvalene (TTF)-based dyes featured with a donor-bridge-acceptor (D-pi-A) structure were synthesized and characterized. ALL of them undergo two reversible oxidations to form stable radical cation and dication species. The eIectronic interactions between the TTF donor and the cyanoacrylic acid acceptor through the different Tc-Iinkers have been demonstrated by the presence of a photoinduced intramolecular charge-transfer (ICT) absorption band in the visible region. A red shift of the ICT state can be finely tuned by the degree of aromaticity and extended conjugation of Tc-bridges. To some extent, the oxidation potentials of these dyes are affected by the nature of Tc-bridges. They have been applied in organic dye-sensitized solar cells, showing relatively Low power conversion efficiencies of up to 0.87% due to substantial charge recombination Losses.