A High-Efficiency Ultraviolet Organic Light-Emitting Diode Employing a Double Boron-Oxygen-Nitrogen-Based Emitter

Designing high-efficiency ultraviolet organic light-emitting diodes (UV OLEDs) remains challenging due to the need for efficient utilization of triplet excitons while maintaining a wide bandgap. In this study, we designed double boron-oxygen-nitrogen-based polycyclic aromatic hydrocarbons (dBON-PAHs) with rigid planar structures and developed a novel UV emitter, BO-N, featuring hybridized local and charge-transfer (HLCT) properties. BO-N exhibited UV emission in toluene solution and 1,3-di(9H-carbazol-9-yl)benzene (mCP) film, with photoluminescence (PL) peaks of 391 and 400 nm and narrow full width at half-maximum (FWHM) values of 15 and 34 nm, respectively. The device doped with 5 wt% BO-N achieved a narrowband UV emission with an FWHM of 37 nm, an electroluminescence peak (λ_EL) of 399 nm, and CIE coordinates of (0.166, 0.030). Moreover, the device attained a record-high maximum external quantum efficiency (EQE_max) of 18.6% among reported HLCT-based UV OLEDs with CIE_y < 0.05. These findings highlight the great potential of double BON-PAHs as robust emitters for high-performance UV OLEDs.