High-Performance Ultraviolet Organic Light-Emitting Diode Enabled by High-Lying Reverse Intersystem Crossing

作者：Zhang, Han; Li, Ganggang; Guo, Xiaomin; Zhang, Kai; Zhang, Bing; Guo, Xuecheng; Li, Yuxuan; Fan, Jianzhong; Wang, Zhiming^*; Ma, Dongge; Tang, Ben Zhong^*

来源：Angewandte Chemie - International Edition, 2021, 60(41): 22241-22247.

DOI：10.1002/anie.202108540

• hybridized local and charge-transfer state
• OLEDs
• record-high EQE
• reverse intersystem crossing
• UV emission

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 high-quality 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 (CIEx, 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-of-the-art device performance can inspire the design of UV emitters, and pave a way for the further development of high-performance UV OLEDs.