Characterisation and application of new carboxylic acid-functionalised ruthenium complexes as dye-sensitisers for solar cells

A series of ruthenium complexes with and without TiO₂ anchoring carboxylic acid groups have been synthesised and characterised using nuclear magnetic resonance (NMR), UV–vis and luminescence. These complexes were adsorbed on thin films of the wide band-gap semiconductor anatase and were tested as photosensitisers under standard conditions. I/V characteristics of such devices revealed superior performance of the non-symmetric complexes 4′-(4-bromophenyl)-2,2′; 6′,2″] terpyridine]Ru(II) 4′-(4-bromophenyl)-2,2′; 6′,2″] terpyridine-4,4″-dicarboxylic acid] and 2,2′; 6′,2″] terpyridine Ru(II) 2,2′; 6′,2″] terpyridine-4′-carboxylic acid with a maximum output power 0.016 mW cm⁻² under illumination at 100 mW cm⁻² AM1.5 and efficiencies 3 times higher than the symmetric complexes.