Boosting Exciton Utilization Rate in Organic Electroluminescence Devices with BN-Embedded Triangulenes and Triplet Fluorescence Emission

Organic diradicals with triplet ground states hold the potential to directly harness triplet excitons in electroluminescent devices, thus circumventing the slow reverse intersystem crossing process inherent in conventional organic fluorescent materials. Despite their significant promise, research into diradicals has remained relatively underexplored. [3]Triangulene, a polycyclic aromatic hydrocarbon, possesses a triplet ground state; however, it is nonfluorescent due to its alternating symmetry. This study introduces a novel strategy to break this symmetry by substituting carbon with boron or nitrogen, which may enable diradical fluorescence by facilitating triplet state transitions. Computational design of BN-integrated [3]triangulene derivatives reveals the presence of narrowband triplet fluorescence in the red and infrared regions, characterized by high quantum yields. By strategically positioning substituents at the periphery, we further achieve tunable luminescence colors and photoluminescence quantum yields that approach 100%. Our research highlights the promising potential of BN-embedded triangulenes in the advancement of high-performance organic light-emitting devices.