Quinoxaline-based host materials for organic light-emitting diodes

The host material plays a pivotal role in the performance of organic light-emitting diodes (OLEDs), driving efficient energy transfer to the guest material and thereby boosting overall device efficiency. Among the promising candidates for host materials, exciplexes stand out for their ability to fine-tune charge transport and facilitate superior energy transfer. In this study, we introduce diphenylquinoxaline (DPQ) as the core framework for the electron acceptor, leading to the creation of two innovative designs: DPQ-1 and DPQ-2. To complement this, carbazole and phenothiazine derivatives—renowned for their excellent hole-transport properties—were selected as electron donors. The interplay between these components fosters the formation of exciplexes, meticulously optimized through tailored molecular configurations. Incorporating tert-butyl groups further enhances solubility and mitigates quenching caused by molecular aggregation. By pairing the DPQ acceptor with various electron donors, we unraveled the mechanism behind exciplex formation. The DPQ molecules, along with donor-acceptor blends, were then employed as hosts in OLED emitting layers to evaluate their performance. Notably, red phosphorescent OLEDs using DPQ-2/TCTA achieved an impressive maximum external quantum efficiency (EQE) of 11.7 %, while the DPQ-2/mCP blend reached an even higher EQE of 12.6 %. These results underscore the significant potential of DPQ-based systems in advancing electroluminescent technologies. [Display omitted] •DPQ Framework: Introducing diphenylquinoxaline (DPQ) as a core acceptor, enabling high-performance DPQ-1 and DPQ-2 designs.•Enhanced Exciplex Efficiency: Optimized configurations and tert-butyl groups improve solubility, reduce quenching, and boost formation.•High PhOLED Efficiency: DPQ-2-based red PhOLEDs reached EQEs of 11.7% (TCTA) and 12.6% (mCP), showcasing strong advanced application potential.