Multiresonance-donor-multiresonance emitter for efficient narrowband blue OLEDs

Solution processing has emerged as an up-and-coming technique for the scalable manufacture of organic light-emitting diodes (OLEDs) owing to the material savings and compatibility with large-area manufacturing. Nonetheless, the development of solution-processable pure-blue emitters that exhibit optimal color purity and electroluminescent efficiency presents a significant challenge in pursuing high-performance solution-processed devices. Here, we demonstrate a molecular configuration strategy to create solution-processable multiresonance thermally activated delayed fluorescence (MR-TADF) emitters. The methodology encompasses the construction of a “multiresonance-donor-multiresonance (MR-D-MR)” framework that features hybrid short/long-range charge transfer excitation characteristics. The proof-of-concept emitter demonstrates considerable rigidity and reduced vibronic progression, resulting in pure-blue narrowband emission at 474 nm. Furthermore, it possesses a large oscillator strength and significant spin-orbit couplings, facilitating rapid exciton dynamics. These advantageous properties enable the emitter to achieve a record-high electroluminescent efficiency of 35.1% for sensitizer-free solution-processed OLEDs. The outstanding electroluminescent outcomes underscore the efficacy of our molecular construction strategy.