Julolidine--Based Organic Dyes with Neutral and Anion Anchoring Groups for Dye-Sensitized Solar Cells.

Two simple organic dyes (J1 and J2) containing julolidine as the electron donor were synthesized. The simple structure of julolidine attached to the cyanoacetic acid group formed two compounds (anion and neutral forms of E-CCVJ), which showed two different efficiencies when applied to dye-sensitized solar cells (DSSCs). Overall conversion efficiencies of 0.91% and 1.21% were obtained for DSSCs based on the cyanoacetic acid (J1) and cyanoacetate (J2) derived dyes, respectively. Compared to the cyanoacetic acid terminated dye, the current density, open circuit voltage and conversion efficiency of the solar cells based on cyanoacetate dye were increased by approximately 24%, 8% and 32%, respectively. The electrochemical impedance analysis showed that the better charge transfer of TiO2 (e-) and electron lifetime (τ(e)) for J2 dye as compared with J1. The power conversion efficiency was found to be quite sensitive to small structural changes to the anchoring moiety.