Abstract：
A new methodological design is proposed for carbon dots (CDs)-based crystallization-induced phosphorescence (CIP) materials via one-step self-assembled packaging controlled by NH4 +. O-phenylenediamine (o-PD) as a nitrogen/carbon source and the ammonium salts as oxidants are used to obtain CDs supramolecular crystals with a well-defined staircase-like morphology, pink fluorescence and ultralong green room-temperature phosphorescence (RTP) (733.56 ms) that is the first highest value for CDs-based CIP materials using pure nitrogen/carbon source by one-step packaging. Wherein, NH4 + and o-PD-derived oxidative polymers are prerequisites for self-assembled crystallization so as to receive the ultralong RTP. Density functional theory calculation indicates that NH4 + tends to anchor to the dimer on the surface state of CDs and guides CDs to cross-arrange in an X-type stacking mode, leading to the spatially separated frontier orbitals and the through-space charge transfer (TSCT) excited state in turn. Such a self-assembled mode contributes to both the small singlet-triplet energy gap (ΔEST) and the fast inter-system crossing (ISC) process that is directly related to ultralong RTP. This work not only proposes a new strategy to prepare CDs-based CIP materials in one step but also reveals the potential for the self-assembled behavior controlled by NH4 +.
摘要：
通过由NH4控制的一步自组装包装，提出了一种新的方法设计，用于基于碳点（CD）的结晶诱导磷光（CIP）材料。邻苯二胺（o-PD）作为氮/碳源和铵盐作为氧化剂用于获得具有明确定义的阶梯状形态的CD超分子晶体，粉红色荧光和超长绿色室温磷光（RTP）（733.56ms），这是通过一步包装使用纯氮/碳源的基于CD的CIP材料的第一个最高值。其中,NH4+和o-PD-衍生的氧化聚合物是自组装结晶以便接收超长RTP的先决条件。密度泛函理论计算表明，NH4+倾向于锚定在CD表面状态的二聚体上，并引导CD以X型堆叠模式交叉排列，导致空间分离的前沿轨道和通过空间电荷传递（TSCT）激发态。这种自组装模式有助于小的单重态-三重态能隙（ΔEST）和与超长RTP直接相关的快速系统间交叉（ISC）过程。这项工作不仅提出了一步制备基于CD的CIP材料的新策略，而且还揭示了由NH4控制的自组装行为的潜力。
