Using the Voids. Evidence for an Antenna Effect in Dye-Sensitized Mesoporous TiO2 Thin Films

Composite structures of Ru(bpy)2(4,4′-(PO3H2)2bpy)2+ surface bound to nanocrystalline TiO2 with an overlayer of Ru(bpy)3 2+ ion exchanged into Nafion, FTO|nanoTiO2-[Ru(bpy)2(4,4′-(PO3H2)2bpy)]2+/Nafion,Ru(bpy)3 2+ (FTO = fluorine-doped tin oxide), have been prepared and characterized. Steady-state emission and time-resolved lifetime measurements demonstrate that energy transfer occurs from Nafion,Ru(bpy)3 2+* to adsorbed Ru(bpy)2(4,4′-(PO3H2)2bpy)2+ with an efficiency of ∼0.49. Energy transfer sensitizes photoinjection by the adsorbed metal-to-ligand charge transfer (MLCT) excited state by an “antenna effect.”