EFFECT OF BRIDGE LENGTH ON INJECTION RATES IN Ru(II)OLYPYRIDYL COMPLEXES ANCHORED TO NANOCRYSTALLINE TiO_2 THROUGH RIGID-ROD LINKERS

摘要

Rigid-rod linkers were used to anchor Ru(II) polypyridyl complexes to the surface of TiO_2 (anatase) thin films and study the effect of bridge length on the injection rates. The linkers were made of p-phenyleneethynylene (Ph-E)n bridges carrying two COOR anchoring groups on one end, and were capped with Ru(Il) polypyridyl complexes as the sensitizing chromophores. The rigid-rod sensitizers were bound to TiO_2 anatase mesoporous thin films. The fully conjugated bridge influences the spectral properties of the Ru complexes. The metal-to-ligand charge-transfer MLCT excited states were long-lived (~ 2 ps) and there is evidence for delocalization onto the rigid-rod linker. The injection rates on TiO_2 were found to be dependent on the bridge length. Biexponential injection rates, weak distance dependence and small attenuation factor were observed.