聚集诱导发光现象的理论研究

本文系统介绍了本课题组发展的分子辐射跃迁和无辐射跃迁速率常数的热振动关联函数理论方法的最新进展及其在聚集诱导发光领域的典型应用. 基于第一性原理计算, 定量考察了位阻、温度、聚集等因素对分子体系发光性质的影响. 从微观角度给出了分子聚集诱导发光机理： 分子激发态的无辐射能量衰减通道主要是对应于低频模式的芳香环扭转和高频模式的碳碳伸缩振动. 当位阻增加、温度降低或者分子聚集时, 芳香环的转动受限, 无辐射能量衰减通道被抑制, 导致无辐射跃迁速率常数降低, 而其对辐射跃迁速率常数影响不大, 从而提高分子的荧光量子产率, 荧光增强.

Theoretical study on the aggregation induced emission

In this paper, we present the newly developed thermal vibration correlation formalism to calculate the radiative and nonradiative decay rates for molecular, and the typical applications in the field of aggregation induced emission （AIE） molecules. Based on the first principles, we quantitatively investigated the effect of steric hindrance, temperature and aggregation for the molecular luminescence properties. It is found that （i） the low frequency normal modes associated with the phenyl ring rotational motions and the high frequency normal modes belonging to C-C stretching vibration are the main channels to dissipate excited-state energy nonradiatively; （ii） the aggregate restricted rotation of the phenyl rings is the main factor for blocking the nonradiative decay process and thus enhancing the fluorescence quantum efficiency.