Preparation of chiral luminescent liquid crystals and manipulation effect of phase structures on the circularly polarized luminescence property
Preparation of chiral luminescent liquid crystals and manipulation effect of phase structures on the circularly polarized luminescence property
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手性发光液晶的制备及相结构对圆偏振发光性能的调控
DOI：
10.1039/d0tc04832a
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发表时间：
2021-02
影响因子：
6.4
通讯作者：
Youde Chen;Peng Lu;Qin Gui;Zhiyan Li;Yongjie Yuan;Hailiang Zhang
中科院分区：
文献类型：
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作者：
Youde Chen;Peng Lu;Qin Gui;Zhiyan Li;Yongjie Yuan;Hailiang Zhang
实现更大的发光不对称因子（glum）和更高的固态发光量子产率对于推动圆偏振发光（CPL）材料的应用至关重要，然而实现它们具有挑战性。本研究利用手性液晶的手性放大效应和聚集诱导发光增强（AIEE）荧光团的强固态发光特性，合成了一种高效的CPL活性手性发光液晶（NO2-CS-C6-Chol）。在退火过程中，依次观察到手性近晶C（SmC*）相、手性近晶C（SmC*）相和手性结晶相。为了抑制强的热激活无辐射衰减，我们用液氮冷冻了SmC * 相和SmC* 相的组装结构。结果，获得在室温下稳定的SmC * 膜（状态C）、SmC* 膜（状态B）和结晶膜（状态A）。结果表明，NO2-CS-C6-Chol在C态和B态具有较大的荧光值和较高的荧光效率，而在A态没有检测到CPL信号。基于NO_2-CS-C_6-Chol体系的热驱动相变特性，CPL可以任意从一种状态转变到另外两种状态，表明相结构对CPL的性质具有显著的调控作用。这一工作有助于深入理解手性的产生和放大机制。
Realizing a larger luminescence asymmetry factor (glum) and a higher solid-state luminescence quantum yield are vital for promoting the application of circularly polarized luminescence (CPL) materials; however, they are challenging to achieve. This study utilizes the chirality amplification effect from chiral liquid crystals and the intense solid-state emission feature from aggregation-induced emission enhancement (AIEE) fluorophores to generate a high efficiency CPL-active chiral luminescent liquid crystal (NO2-CS-C6-Chol). During annealing, cholesteric phase, chiral smectic C (SmC*) phase and crystalline phase were observed successively. To suppress the strong thermo-activated nonradiative decay, we froze the assembly structure of the cholesteric phase and SmC* phase with liquid nitrogen. As a result, the cholesteric film (State C), SmC* film (State B) and crystalline film (State A) stable at room temperature were obtained. The study focuses on the photophysical properties in different phase state films, particularly the impact of phase structures on the properties of CPL. The results show that NO2-CS-C6-Chol presented a large glum value and excellent fluorescence efficiencies in State C and B, while no CPL signal was detected in State A. Based on the thermo-driven phase transition feature of NO2-CS-C6-Chol, CPL can switch from one state to the other two states at our will, indicating the significant manipulation effect of phase structures on the CPL properties. This work is conducive to deeply understand the generation and amplification mechanisms of chirality.