White light emission from blends of blue-emitting organic molecules: A general route to the white organic light-emitting diode?

We show that all possible binary combinations of molecules from four differ ent families of organics-a diamine derivative, N,N'-bis(3methylphenyl)-N,N' -diphenylbenzidine, an oxidiazole derivative, 2-(4-biphenylyl)-5-(4-tert-bu tylphenyl)-1,3,4-oxadiazole, a substituted thiophene dioxide, 2,5-bis(trime thylsilyl thiophene)-1,1-dioxide, and poly(9-vinylcarbazole)-produce white or near-white emission. We suggest that this is due to exciplex formation, and that this is likely to be a general phenomenon for blends of blue-emitt ing aromatic organics. This implies that films of spin-coated blends of blu e-emitting organics represent a general, simple, and cheap route to white-e mitting organic light-emitting diodes. (C) 2001 American Institute of Physi cs.