蓝相液晶对聚集诱导发光分子荧光性能的影响

Effect of blue-phase liquid crystals on the fluorescence properties of aggregation-induced emissive molecules

为了拓宽蓝相液晶的应用范围,构建多功能化蓝相体系平台,本文将具有聚集诱导发光(AIE)特性的液晶TPE-PPE引入蓝相液晶体系,围绕复合体系的荧光性能展开研究。一方面,系统研究并归纳了手性添加剂含量对蓝相液晶相转变行为和光子带隙位移情况的影响;另一方面,探究了蓝相液晶对AIE分子荧光性能的影响,提出了相关荧光增强效应的假说。实验结果表明,不同手性添加剂体系的蓝相Ⅱ的温域范围基本一致,且反射带隙随着温度的降低发生蓝移;而蓝相Ⅰ的温域与手性密切相关,体系中仅存在蓝相Ⅰ时,其反射带隙随温度的降低而红移。蓝相液晶体系对AIE分子有一定的荧光增强效应,并且在整个蓝相温域内,蓝相Ⅰ的反射带隙红移,体系的荧光强度明显增强。由此得出结论,TPE-PPE分子在一定程度上参与了蓝相液晶体系的自组装。由于TPE-PPE分子在双螺旋柱结构中的受限运动,导致其荧光强度增强。随着蓝相Ⅱ的消失和蓝相Ⅰ光子带隙的红移,更多TPE-PPE分子参与到双螺旋柱的自组装中,体系的荧光发射增强。

In order to broaden the application of bluephase liquid crystal(BPLC)and build a multifunctional BPLC system platform,this paper introduces TPE-PPE,a liquid crystal with aggregation-inducedemission(AIE)characteristics,into the BPLC system,and carries out a study on the fluorescence performance of the composite system.On the one hand,the effects of chiral dopant content on the phase transition behavior and photonic band gap(PBG)displacement of the BPLC are systematically investigated and summarized.On the other hand,the influence of BPLC on the fluorescence performance of AIE molecules is explored,and relevant fluorescence enhancement effects are proposed.The experimental results show that the temperature domain ranges of blue phaseⅡwith different chiral dopants systems are basically the same,and the PBG shows blue shift with decreasing temperature.The temperature range of blue phaseⅠis closely related to the chirality,and when only blue phaseⅠexists in the system,its PBG shows red shift with the decrease of temperature.The BPLC system has a certain fluorescence enhancement effect on AIE molecules,and the fluorescence intensity of the system is obviously enhanced with the red shift of the PBG of blue phaseⅠ.It is concluded that the TPE-PPE molecules are involved in the self-assembly of the BPLC system to a certain extent.The enhanced fluorescence intensity of the TPE-PPE molecules is due to the restricted movement of the TPE-PPE molecules in the double-twisted cylinders.With the disappearance of the blue phaseⅡand the red shift of the PBG of the blue phaseⅠ,more TPE-PPE molecules are involved in the self-assembly of the double-twisted cylinders,and the fluorescence emission of the system is enhanced.