Luminogens featuring aggregation‐induced emission characteristics (AIEgens) have been widely applied in high‐performance non‐doped blue organic light‐emitting diodes (OLEDs). However, AIEgens with high exciton utilization are rare. Herein, a tetraphenylbenzene (TPB)‐based AIEgen of PXZ‐TPB‐CN, in which phenoxazine (PXZ) and cyano (CN) serve as strong electron‐donating and withdrawing group, respectively, was rationally designed and facilely synthesized. PXZ‐TPB‐CN exhibits a unique mechanochromic luminescence. The lifetime of its ground powders and films exhibits a new decay component compared with the pristine powders, which attributes to the reverse intersystem crossing from the high‐lying triplet state process according to the theoretical calculation. To further verify this process, a non‐doped OLED using PXZ‐TPB‐CN as emitting layer was fabricated, and a much higher maximum external quantum efficiency (EQE) of the device than that of theoretical one was obtained, suggesting that triplet excitons are involved in a radiative process. In addition, the high horizontally oriented dipoles also contribute to this high EQE. This work provides a new strategy to realize blue AIEgen‐based OLEDs with high exciton utilization by attaching strong donors and acceptors on twisted AIE cores.

中文翻译：

---

具有给体-受体结构的基于四苯苯的AIE发光剂：独特的变色发射和高激子利用率

具有聚集诱导发射特性的发光剂（AIEgens）已广泛应用于高性能非掺杂蓝色有机发光二极管（OLED）。但是，激子利用率高的AIEgens很少。本文中，合理设计并轻松合成了PXZ-TPB-CN中基于四苯苯（TPB）的AIEgen，其中苯恶嗪（PXZ）和氰基（CN）分别作为强电子给体和吸电子基团。PXZ‐TPB‐CN具有独特的机械变色发光。与原始粉末相比，其研磨粉末和薄膜的寿命表现出新的衰减成分，这归因于根据理论计算，从高层三重态过程逆向体系间交叉。为了进一步验证此过程，制备了一种使用PXZ-TPB-CN作为发射层的非掺杂OLED，并且该器件的最大外部量子效率（EQE）比理论值高得多，这表明三重态激子参与了辐射过程。另外，高水平定向偶极子也有助于这种高EQE。这项工作提供了一种新的策略，即通过在扭曲的AIE核心上附加强大的供体和受体来实现具有高激子利用率的蓝色AIEgen基OLED。