Lifetime enhancement of exciplex based organic light-emitting diodes by triplet exciton engineering

A device approach to improve the device lifetime of exciplex organic light-emitting diodes was studied by managing the intermolecular interaction and concentration quenching of exciplexes. The exciplexes were made up of a p-type material and a bipolar n-type material, in which the ratio of the p-type material was less than 50% for dispersion in the n-type material to copy the conventional host-dopant type emitting layer. The exciplexes generated between the p-type material and n-type material were dispersed in the n-type material. The device lifetime of the exciplex organic light-emitting diodes was extended by almost four times through control of the p-type material content by mimicking the host-dopant system. The analysis of the lifetime improvement mechanism revealed that suppression of triplet exciton loss by strong intermolecular interaction and concentration quenching was the major pathway to stabilize the exciplex devices by dispersion. Additionally, the device lifetime of the fluorescence emitter doped exciplex devices was extended by more than three times. Therefore, the exciplexes with a p-type material dispersed in the bipolar n-type material were effective to elongate the device lifetime of the exciplex based organic light-emitting diodes.