High and Balanced Bipolar‐Transporting Deep‐Blue HLCT Material for Efficient Monochrome and White OLEDs based on a Simple Phenanthroimidazole‐Dibenzothiophene Derivative

Abstract The irreconcilable contradiction between wide bandgap and charge carriers injection/transport in deep‐blue organic electroluminescence materials is one of the largest bottlenecks restricting the development of organic light‐emitting diodes (OLEDs). Here, a multifunctional deep‐blue hybridized local and charge‐transfer material containing a phenanthroimidazole‐dibenzothiophene derivative that can act as an emitter as well as a host for phosphorescent OLEDs is reported. Owing to its high and balanced bipolar‐transporting ability, remarkable fluorescence efficiency, and suitable triplet energy level, the deep‐blue device with it as a neat emitter provides an external quantum efficiency (EQE) of 6.68%, while yellow and red phosphorescent OLEDs offer the EQEs of 25.35% and 22.19%, respectively. All of them exhibit low‐efficiency roll‐off characteristics. What's more amazing is that the fluorescent/phosphorescent hybrid white OLEDs achieve high power efficiencies and EQEs over 95.9 lm W⁻¹ and 26.8%, and the values are still higher than 77.7 lm W⁻¹ and 25.6% at the high luminance of 1000 cd m⁻².