Management of Locally Excited States for Purine-based TADF Emitters: A Method to Reduce Device Efficiency Roll-Off.

The programmed arylation of purine has been developed to construct a series of efficient thermally activated delayed fluorescent (TADF) materials. The corresponding organic light-emitting diodes (OLEDs) exhibit external quantum efficiency as high as 16.0% alongside small efficiency roll-off. Intriguingly, this work proves that the good management of localized states is an efficient way to reduce device efficiency roll-off and is crucial for the future design of high-performance OLEDs.