Thermally Activated Delayed Fluorescence Type Exciplex Host For Long Lifetime In Deep Blue Phosphorescent Organic Light-Emitting Diodes

High performance deep blue phosphorescent organic light-emitting diodes (PhOLEDs) were developed using a thermally activated delayed fluorescence type exciplex host. Three isomeric electron transport type host materials based on a triazine core, tetraphenylsilane and benzonitrile groups were synthesized for high triplet energy and good electron transport property in solid state. They formed thermally activated delayed fluorescence type exciplexes with a carbazole based hole transport type host. Among the three hosts, 3-(4,6-bis(3-(triphenylsilyl) phenyl)-1,3,5-triazin-2-yl)benzonitrile host achieved high external quantum efficiency of 21.0% and deep blue color coordinate of (0.14, 0.18). Moreover, the lifetime of the deep blue PhOLEDs was improved by more than 1.6 times using the new exciplex host compared with the state of the art mixed host.