Abstract
The development of organic light-emitting diodes (OLED) with low efficiency roll-off at high brightness still remains a significant challenge. The hot-exciton mechanism provides a potential solution owing to its unique high-lying reverse intersystem crossing (hRISC) with a sufficiently large rate constant. Herein, two pyrene-based hot-exciton molecules, namely TPAPyCP and 2mTPAPyCP, were successfully designed using triphenylamine (TPA) as donor and benzonitrile as acceptor. The planar pyrene provided multiple fast hRISC channels, which effectively improved the photoluminescence quantum yield (PLQY) values to 73.2% and 65.8% in neat films. A non-doped device based on TPAPyCP demonstrated a maximum external quantum efficiency (EQE) of 9.41% and still maintained 8.95% at a high luminance of 10 000 cd m(-2), highlighting a negligible efficiency roll-off of 4.97%.