Interfacial triplet confinement for achieving efficient solution-processed deep-blue and white electrophosphorescent devices with underestimated poly(N-vinylcarbazole) as the host

Highly efficient deep-blue and white PhOLEDs with FIr6 as a blue emitter and PVK as a host are developed by using a high triplet level interfacial layer to confine triplet excitons within the emissive layer. Incorporation of an interfacial layer with a higher triplet level such as TPCz can effectively cut off the potential loss pathways of the triplet excitons within the PVK:FIr6 emissive layer. The resultant PVK:FIr6-based deep-blue and white solution-processed PhOLEDs exhibit an unprecedented forward-viewing EQE of 16.1% and a total EQE of 28.0% (38.4 lm W-1) at a practical luminance of 1000 cd m-2, respectively.