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) was prepd., characterized by absorption spectroscopy and adsorbed onto nanocryst. TiO2 electrodes. The resulting system was studied by absorption spectroscopy, electrochem. and photoelectrochem. and the results were compared to those for a ref. 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-visible absorption compared to that with 2. Also, 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 aq. NaOH (0.1M), while 2 desorbs immediately.