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Ultraviolet (UV) organic emitters that can open up applications for future organic light-emitting diodes (OLEDs) are of great value but rarely developed. Here, we report a highquality UV emitter with hybridized local and charge-transfer (HLCT) excited state and its application in UV OLEDs. The UV emitter, 2BuCz-CNCz, shows the features of low-lying locally excited (LE) emissive state and high-lying reverse intersystem crossing (hRISC) process, which helps to balance the color purity and exciton utilization of UV OLED. Consequently, the OLED based on 2BuCz-CNCz exhibits not only a desired narrowband UV electroluminescent (EL) at 396 nm with satisfactory color purity (CIE x, y = 0.161, 0.031), but also a record-high maximum external quantum efficiency (EQE) of 10.79 % with small efficiency roll-off. The state-ofthe-art device performance can inspire the design of UV emitters, and pave a way for the further development of highperformance UV OLEDs.

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