Study of electroplex emission from a blend of two basic blue-emitting materials PVK and NPB

An organic light emitting diode was fabricated with the simple structure of ITO/PEDOT:PSS/PVK:NPB/LiF/Al, which used the blend of two blue-emitting materials poly(N-vinylcarbazole) (PVK) and N,N"0-bis-(1-naphthyl)-N,N"0-diphenyl-1,10-biphenyl-4,40-diamine (NPB) as the emitting layer. In EL spectra of the device, except for the emission of NPB, a new peak at 650nm was observed too, but was not in PL spectra. So the new emission was proposed to be electroplex that occurred between PVK and NPB molecules. White emission via electroplex formation can be obtained with Commission International d'Eclairage (CIE) coordinates (0.31, 0.3 0) at 28V. By use of electroplex formed between two blue-emitting materials, a new route to get white organic light-emitting diode (WOLED) may be obtained.