Hybrid Local and Charge Transfer Emitters Using Pyrene as π-Bridge Towards Negligible Efficiency Roll-Off Non-doped OLED

Abstract

The development of organic light-emitting diodes (OLED) with low efficiency roll-off at high brightness remains a significant challenge. The hot-exciton mechanism may provide the possibility to address this problem owing to its unique high-lying reverse intersystem crossing (hRISC). In this study, two pyrene-based molecules were successfully designed using triphenylamine (TPA) as donor and benzonitrile as acceptor, namely TPAPyCP and 2mTPAPyCP. The planar pyrene provided a multiple fast hRISC channel, which effectively improve the photoluminescence quantum yield (PLQY) values of 73.2% and 65.8% in neat films. The non-doped device based on TPAPyCP demonstrated a maximum external quantum efficiency (EQE) of 9.41%, and still maintained 8.95% at high luminance of 10 000 cd/m2, highlighting the negligible efficiency roll-off of 4.97%.