High luminance and efficient non-doped blue OLED with negligible efficiency roll-off

Efficient non-doped blue organic light-emitting diodes (OLEDs) exhibit admirable merits of simple device structure and low power consumption. However, efficient and stable blue devices are still rare. Herein, a novel blue molecule (PPyIAC) was designed by adding 9,10-diphenyl-9H-pyreno[4,5-d]imidazole (PPyI) to benzonitrile substituted anthracene. Single-crystal analysis displayed that it had formed highly ordered arrangement and abundant intra/intermolecular forces as well as weak π-π stacking in solid state, which not only accelerated and balanced the carrier transport, but also reduced excitons quenching caused by serious molecular aggregation, improving the stability of non-doped device. Furthermore, theoretical investigations have shown that the high-energy “hot exciton” channels avoided the accumulation of T₁ excitons and reduced efficiency roll-off. Consequently, the non-doped device of PPyIAC exhibits a high luminance of 46778 cd m⁻², and achieved a maximum external quantum efficiency (EQE_max) up to 9.2 % with a negligible efficiency roll-off (2 %) @ 10 000 cd m⁻², resulting in superior performance in organic light-emitting diodes.