Tuning the properties of ruthenium bipyridine dyes for solar cells by substitution on the ligands -: characterisation of bis[4,4′-di(2-(3-methoxyphenyl)ethenyl)-2,2′-bipyridine][4,4′-dicarboxy-2,2′-bipyridine]ruthenium(II) dihexafluorophosphate

The new dye complex bis[4,4'-di(2-(3-methoxyphenyl) ethenyl)-2,2'-bipyridine][4,4'-dicarboxy-2,2'-bipyridine]ruthenium(II) dihexafluorophosphate (1) has been prepared, characterised by absorption spectroscopy and adsorbed onto nanocrystalline TiO2 electrodes. The resulting system was studied by absorption spectroscopy, electrochemistry and photoelectrochemistry and the results were compared to those for a reference system with bis[2,2'-bipyridine][ 4,4'-dicarboxy-2,2'-bipyridine] ruthenium(II) ( 2). The system with 1 displays a broader and red-shifted UV-vis absorption compared to that with 2. Moreover, the system with 1 is less sensitive towards the water content in the electrolyte, and an adsorbed monolayer of 1 remains on the electrode surface after days even in aqueous NaOH (0.1 M), while 2 desorbs immediately.