Purification-free synthesis of a highly efficient ruthenium dye complex for dye-sensitised solar cells (DSSCs)

Abstract

A novel Ru(II) sensitiser A597 containing the 4,4′-dioctylamido-2,2′-bipyridine ancillary ligand is synthesised without the need for purification steps. It shows an irreversible oxidation at 0.92 V in the cyclic voltammogram and an absorbtion at 539 nm in the UV-vis spectrum corresponding to an ¹MLCT transition. Preliminary DFT calculations reveal that the HOMO is localised on the ruthenium metal centre and the thiocyanate ligands, whereas the LUMO is predominantly on the 4,4′-carboxy-2,2′-bipyridine ligand. The ruthenium complex exhibits a maximum power conversion efficiency (7.25%) compared with the known Z907 (8.32%) in dye-sensitised solar cells.