Y‐Shaped Pyrene‐Based Aggregation‐Induced Emission Blue Emitters for High‐Performance OLED Devices
Jin Zeng, Nuoling Qiu, Jianyu Zhang, Xiaohui Wang, Carl Redshaw, Xing Feng, Jacky W. Y. Lam, Zujin Zhao, Ben Zhong Tang
Abstract
Abstract The proposed concept of aggregation‐induced emission (AIE) has offered an efficient strategy to design high‐performance luminescent materials. Herein, three blue emitters containing a pyrene core decorated with either triphenylamine or tetraphenylethylene units are presented. The designed compounds Py‐TPA and Py‐2TPE are AIE or active materials with blue emission from 464 to 478 nm in the solid state, whereas Py‐2TPA is not. Moreover, the enhanced thermal stability of compounds Py‐TPA and Py‐2TPE allows for their utilization as emitter layers for the fabrication of blue organic light‐emitting diode (OLED) devices. The devices exhibit excellent electroluminescence emission with maximum λ max em in the range 456–482 nm with a maximum external quantum efficiency of 7.27%, high exciton utilization efficiency (77.3%), and low turn‐on voltage (≤3.1 V), as well as low‐efficiency roll‐off. Theoretical calculations reveal that the high exciton utilization efficiency ( ƞ r ) originates from the triplet excitons at T 2 to the lowest single excited (S 1 ) state via a reverse intersystem crossing process following the principle of the “hot exciton” mechanism. This article not only provides powerful evidence revealing the advantages of pyrene‐based AIEgens for OLED applications, but also offers a new approach for designing pyrene‐based “hot exciton” materials for next‐generation OLEDs.