Light emitting devices from blended films of ruthenium(II)bis (2,2′-bipyridine)(4,7-dimethyl-1,10-phenanthroline) complex with poly(N-vinylcarbazole)

The light emitting devices using ruthenium(II)bis(2,2^′- bipyridine)(4,7-dimethyl-1,10-phenanthroline) [Ru(bpy)₂ DIM]²⁺ complex as emitter have been fabricated in two structures: Indium-tin-oxide glass (ITO)/poly( N-vinylcarbazole) (PVK):[Ru(bpy)₂DIM]²⁺/Al and ITO/PVK:[Ru(bpy)₂DIM]²⁺/2,9-dimethyl-4,7- diphenyl-1,10-phenanthroline (BCP)/tris-(8-hydroxyquinoline) aluminum (Alq₃)/Al. In ITO/PVK:[Ru(bpy)₂DIM] ²⁺/Al, the emitter concentration influences both the turn on voltage and the emission wavelength. At 6 wt% [Ru(bpy)₂ DIM]²⁺ concentration, the device has a turn on voltage of 16 V and the emission peak at 600 nm. At 36 wt% [Ru(bpy)₂DIM] ²⁺ concentration, the device turn on voltage can be reduced to 3 V, with the emission peak at 620 nm. ITO/PVK:[Ru(bpy)₂ DIM]²⁺ (36 wt%)/BCP/Alq₃)/Al obtains a quantum efficiency one order of magnitude higher than ITO/PVK:[Ru (bpy)₂DIM]²⁺ (36 wt%)/Al.