Photocurrent enhancement by employing 2,6-bis[1-(2,4,6-trimethyl-phenylimino)ethyl]pyridine as a co-sensitizer with ruthenium in dye sensitized solar cell

2,6-bis[1-(2,4,6-trimethyl-phenylimino)ethyl]pyridine (M3) is prepared and employed as a co-sensitizer in dye-sensitized solar cells (DSSCs) based on nanostructured TiO₂ electrodes. The prepared co-sensitizer could alleviate the aggregation of ruthenium dye N719 on the nanostructured TiO₂ film, enhance the spectral responses of the co-sensitized TiO₂ film in region from 400 to 750 nm, suppress the electron recombination, prolong the electron lifetime and decrease the total resistance of DSSCs. The optimized cell device co-sensitized by M3/N719 dye gives a short circuit current density of 17.31 mA cm^-2, an open circuit voltage of 0.70 V and a fill factor of 0.61 corresponding to an overall conversion efficiency of 7.30% under standard global AM 1.5 solar irradiation, which is 34% higher than that of device solely sensitized by N719 (5.43%) under the same conditions. The improved overall conversion efficiency is ascribed to the enhancement of photocurrent.