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

Abstract 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(9 H ‐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.