Influence of donor moiety in ruthenium sensitizers on the properties of dye-sensitized solar cells

Heteroleptic ruthenium complexes cis-Ru(H2dcbpy)(L)(NCS)2], where H2dcbpy is 4,4'-dicarboxylic acid-2,2'-bipyridine and L is 4-(4-(N,N-di-(p-hexyloxyphenyl)-amino)styryl)-4'-methyl-2,2'-bipyridine (Rut-A) or 4-(4'-(3,6-dihexyloxycarbazole-9-yl)-styryl)-4'-methyl-2,2'-bipyridine (Rut-B), have been synthesized and characterized by NMR, UV-Vis spectroscopy, and cyclic voltammogram. The effect of different electron donors on the properties of dye-sensitized solar cells has been studied. The power conversion efficiency of DSSC based on Rut-B is 6.1% while Rut-A delivered a lower efficiency of 4.52% under the same device fabrication and measuring conditions. The better photovoltaic performance of Rut-B is mainly associated with enhanced dye absorptivity and charge recombination suppression.