Single molecule white emission by intra- and inter- molecular charge transfer

A white-emitting small molecule designed to emit by intramolecular and intermolecular charge transfer (CT) emission mechanisms at the same time was developed. The small molecule was designed to have a donor-acceptor structure for blue emission by intramolecular CT and to possess an additional strong donor which can form exciplex with the acceptor in the same molecule for yellow emission. The donor-acceptor backbone structure and the strong donor were electronically isolated to realize the blue emission by intramolecular CT and yellow emission by intermolecular CT. The emission intensity of the blue and yellow emissions was easily controlled by managing the doping concentration of the white emitter in the host. High doping resulted in relatively strong yellow emission by intermolecular CT, while low doping offered strong blue emission by intramolecular CT. Therefore, the novel method of realizing white emission both by intramolecular CT and intermolecular CT can open a new way of developing single molecule based white organic light-emitting diodes.