A fluorene-bridged double carbonyl/amine multiresonant thermally activated delayed fluorescence emitter for efficient green OLEDs

Herein, we report a fluorene-bridged double carbonyl/amine-based MR TADF emitter DDiKTa-F, formed by locking the conformation of the previously reported compound DDiKTa. Using this strategy, DDiKTa-F exhibited narrower, brighter, and red-shifted emission. The OLEDs with DDiKTa-F emitted at 493 nm and showed an EQEmax of 15.3% with an efficiency roll-off of 35% at 100 cd m-2. We report a fluorene-bridged double carbonyl/amine-based MR TADF emitter DDiKTa-F. The OLEDs exhibited narrower, red-shifted emission and reduced efficiency roll-off compared to the device with the previously reported, conformationally flexible DDiKTa.