To achieve efficient room-temperature phosphorescence of organic materials with ultralong lifetime, it is imperative to resolve the dilemma that the introduction of heavy atoms simultaneously improves emission efficiencies and shortens the emission lifetimes. Herein, we report a new molecular design approach for halogenated luminogens with a methylene bridge to avoid the lifetime shortening induced by heavy halogens and propose a general molecular engineering strategy to realize efficient and ultralong room-temperature phosphorescence via halogen-mediated molecular clustering. The halogenated N-benzylcarbazole derivatives show distinct photophysical behaviors depending on different physical states, including single-molecule state and cluster state. Their crystals demonstrate the halogen-dependent emission duration of room-temperature phosphorescence upon excitation. Experimental data and theoretical analysis indicate that halogen-regulated molecular clustering in the crystal is responsible for the generation of efficient ultralong room-temperature phosphorescence, and halogen-dominated molecular engineering favors the promotion of the intersystem crossing process and the following triplet emissions.

中文翻译：

---

通过卤素介导的分子组装，簇状触发的超长室温有机晶体的磷光。

为了实现具有超长寿命的有机材料的有效室温磷光，必须解决引入重原子同时提高发射效率和缩短发射寿命的难题。在这里，我们报告了一种新的针对带有亚甲基桥的卤化发光剂的分子设计方法，以避免重卤素引起的寿命缩短，并提出了一种通用的分子工程策略，以通过卤素介导的分子簇来实现高效且超长的室温磷光。卤代的N-苄基咔唑衍生物根据不同的物理状态（包括单分子状态和簇状态）显示出不同的光物理行为。他们的晶体证明了激发后室温磷光的卤素依赖性发射时间。实验数据和理论分析表明，晶体中受卤素调节的分子簇是产生有效的超长室温磷光的原因，而卤素主导的分子工程有利于促进系统间交叉过程和随后的三重态发射。