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

Abstract

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.