Photophysical properties of new cyclometalated ruthenium complexes and their use in dye sensitized solar cells

Abstract

A new class of cyclometalated ruthenium complexes, Ru(C^N^N′)(N^N′^N′′)·Cl where N^N′^N′′ = 4,4′,4′′-tricarboxy-2,2′:6′,2′′-terpyridine and C^N^N′ = substituted 6-phenyl-2,2′-bipyridine, for Dye Sensitized Solar Cells (DSSCs) is proposed. We have investigated the effect of different substituents (R = COOH, thiophen-2-yl, F and OCH₃) on the ancillary C^N^N′ ligand on the photophysical properties and performance of the six different cyclometalated ruthenium complexes in DSSCs. Using an ionic liquid based electrolyte, efficiencies up to η = 3.06% have been attained under 1 sun irradiation. Moreover, the T66 based DSSC exhibited a good stability under 1000 W m² light soaking at 60 °C for 24 days, retaining 92.8% of its initial efficiency.