Emission Mechanism-Tunned Fused Indolo[3,2,1-jk]carbazole-based Multiple Resonance Emitters for Long Device Operational Lifetime

In blue organic light-emitting diodes (OLEDs), the importance of terminal emitters, which determine device operational characteristics, has been grown. Although multiple resonance (MR) type emitters can provide high color purity and high device efficiency, the high triplet energy (ET) of emitters often cause issues on long-term device operation. In this work, as a solution to implementing stable operation of blue OLEDs, novel emission-mechanism-tuned MR type emitters were developed based on fused indolo[3,2,1-jk]carbazole framework. The molecular structural changes effectively stabilized the ET while maintaining the narrow emission bandwidth. The fabricated blue fluorescent OLED recorded a highquantum efficiency in deep-blue region of CIE_y of 0.075 and device lifetime twice longer than a typical boron type dopant based device. This research establishes the emitter design strategy for extended blue OLEDs.