Improvement of TiO2/dye/electrolyte interface conditions by positional change of alkyl chains in modified panchromatic Ru complex dyes.

A series of panchromatic ruthenium sensitizers (MJ sensitizers) with attached thiophene and phenyl units bearing alkyl chains was synthesized. A new synthetic route was used to examine all possible positions for the alkyl chains. The absorption spectra showed the sum of a ruthenium complex and peripheral organic chromophore units. The hypochromic effect and blueshift of the metal-to-ligand charge-transfer band observed in the modified ruthenium sensitizers were suppressed by changing the positions of the alkyl chains on the attached thiophene ring. Changing only one alkyl chain also influenced the performance of dye-sensitized solar cells. Ruthenium sensitizer MJ-10 with bulky substituent harvests visible and near-infrared light, and solar cells sensitized by MJ-10 exhibit an efficiency of 9.1% under 1 sun irradiation.