X‑Aggregation Enhanced Room Temperature Phosphorescence from Terphenylamine

Organic room temperature phosphorescence (RTP) materials have drawn wide attention because of their unique photoluminescence performances. As is known, their molecular aggregation shows determined influences on their RTP performances. However, the regulation mechanism of the molecular aggregation is still unclear. Herein, the structure-aggregation dependence of organic RTP materials is studied in detail. When introducing methyl and constructing a constrained configuration, the resultant compounds show improved long-persistent luminescence performances. The terphenylamine (TPA) derivatives bearing methyl groups exhibit a prolonged RTP lifetime of about 68–410 ms. As the configurations are constrained stepwise, the RTP lifetimes of TPA, PhCz, and ICz also increase gradually. In contrast, methoxyl and tert-butyl result in a significant shortening of the RTP lifetime to about 110–312 ms and even quenching of RTP. It is found that the introduction of electron-donating groups and the construction of constrained configuration are beneficial for forming regular X-aggregation and rigid molecular packing, while unconstrained bulky groups would result in multiple conformations and disordered molecular arrangement. The X-aggregation could enhance both the intermolecular charge transfer and the restriction on molecular motion, which shows promoting effects on the intersystem crossing processes and suppressed nonradiative decay, resulting in long-lived RTP emission.有机室温磷光（RTP）材料凭借其独特的光致发光性能受到广泛关注。众所周知，分子聚集对其RTP性能具有决定性影响，但当前分子聚集的调控机制仍不明确。本文详细研究了有机RTP材料的结构-聚集依赖性规律。当引入甲基并构建受限构型时，所得化合物的长余辉发光性能得到改善，其中带有甲基的三苯胺（TPA）衍生物的RTP寿命延长至约68–410 ms。随着构型逐步受限，TPA、苯基咔唑（PhCz）和吲哚咔唑（ICz）的RTP寿命也逐渐延长。与之相反，甲氧基与叔丁基则会显著缩短RTP寿命至约110–312 ms，甚至引发RTP猝灭。研究发现，引入给电子基团并构建受限构型，有助于形成规则X型聚集与刚性分子堆积；而不受限的大位阻基团则会导致分子出现多种构象与无序排列。X型聚集可同时增强分子间电荷转移与分子运动受限效应，对系间窜越过程起到促进作用，并抑制非辐射衰减，最终实现长寿命的RTP发射。