Series of new D-A-π-A organic broadly absorbing sensitizers containing isoindigo unit for highly efficient dye-sensitized solar cells.

In this work, six new D-A-π-A sensitizers (ID1-ID6), with triarylamine as the electron donor; isoindigo as a auxiliary electron withdrawing unit; thiophene, furan, and benzene as the linker; and cyanoacrylic acid as the anchoring group, were synthesized through simple synthetic procedures and with low cost. Their absorption spectra were broad with long wavelength absorption maximum approximately at 589 nm and the absorption onset at 720 nm on the TiO(2) film. Electrochemical experiments indicate that the HOMO and LUMO energy levels can be conveniently tuned by alternating the donor moiety and the linker. All of these dyes performed as sensitizers for the DSSCs test under AM 1.5 similar experimental conditions, and a maximum overall conversion efficiency of 5.98% (J(sc) = 14.77 mA cm(-2), V(oc) = 644 mV, ff = 0.63) is obtained for ID6-based DSSCs when TiO(2) films were first immersed for 6 h in 20 mM CDCA ethanol solution followed by 12 h of dipping in the dye CH(2)Cl(2) solution. Electrochemical impedance measurement data implies that the electron lifetime can be increased by coadsorption of CDCA, which leads to a lower rate of charge recombination and thus improved V(oc).