We report here the synthesis, electrochemical and photophysical properties of a series of novel exTTF-based organic dyes (3 and 7a,b) as well as their application in dye-sensitized solar cells (DSSCs). In the three designed dyes, the electron-donor exTTF group is connected to the rhodanine-3-acetic acid electron-acceptor unit through vinyl or vinyl-thiophene spacers. The electrochemical studies showed that the energy gap between the LUMO level of the dyes and the TiO2 conduction band decreases with the length of the conjugated system. As a consequence, the power conversion efficiencies of organic DSSCs fabricated with these dyes scale inversely with their light-harvesting ability.