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 (λEL) of 399 nm, and CIE coordinates of (0.166, 0.030). Moreover, the device attained a record‐high maximum external quantum efficiency (EQEmax) of 18.6% among reported HLCT‐based UV OLEDs with CIEy < 0.05. These findings highlight the great potential of double BON‐PAHs as robust emitters for high‐performance UV OLEDs.