Research On Application Of Circularly Polarized Luminescent Materials From BINOL-based Chiral Nematic Liquid Crystals

Liquid crystal(LC)is widely used in the field of display(LCD)due to its ordered orientation,good fluidity,temperature,electromagnetic response and unique optical properties.Chiral nematic crystals(N*-LCs)with ordered supramolecular self-assembly helix structure can be induced by doping of chiral luminescent dopants into the nematic liquid crystals,which show circular dichroism,chiral amplification effect and gradually become an ideal circularly polarized luminescence material.With various modifications in structural,stable chiral configuration and chiral induction ability,the chiral 1,1'-binanol(BINOL)has been one of the best chiral sources for chiral luminescent materials.In this paper,the N*-LCs of CPL system containing chiral BINOL was constructed.The N*-LCs system can amplify the chiral luminescence emitter and induce the achiral luminescence system to produce CPL signal.In addition,the application of CPL light-emitting liquid crystal materials in LCD devices is preliminarily explored by using DC electric field control.The main works of this dissertation are as follows:1.A pair of enantioluminescence with AIE characteristics were synthesized and their optical properties in solution were characterized.The chiral AIE molecules can induce N-LCs to be a N*-LCs system with super helix structure by doping them into N-LCs in a certain concentration ratio.The N*-LCs shows a strong AI-CPL signal,and the maximum value of g_em is±0.4.Results show that the chiral nematic phase can be induced by low doping ratio of chiral AIE molecules into the nematic liquid crystal,which has significant chiral amplification ability and can emit strong CPL signal.2.A pair of enantiomer Guest 1 based on chiral BINOL and a series of Guest 2with typical AIE effect were designed and synthesized.The ternary N*-LCs self-assembly with highly ordered helical structure was constructed by using liquid crystal as a good self-assembly carrier.The results show that the self-assembly of AIE-N*-LCs emits the induced CPL signal of achiral AIE dyes.Among them,the achiral AIE dyes adjust the emission wavelength of N*-LCs,the CPL direction is determined by the N*-LCs system induced by Guest 1,and it has a significant chiral amplification effect with the g_em value 1.42.This method is universal and provides a simple strategy for the design of full band CPL materials.3.Two pairs of D-A(4-R/S-M1 and 4-R/S-M2)CPL emitters based on chiral BINOL were designed and synthesized,then doped into nematic liquid crystals to form chiral nematic phase(N*-LCs).The results show that the 4-R/S-M2 with relatively small dihedral angle of BINOL skeleton resulting from a more compact high helix structure emit a stronger CPL signal(g_em=-0.83/+0.86)in N*-LCs-2,compared with N*-LCs-1(g_em=-0.20/+0.26).In addition,the phase transition effect(EPT)of chiral nematic phase can be induced by the applied DC electric field,and the cyclic of CPL response behavior in N*-LCs can be observed.This kind of multi stable LCD used by DC electric field switch to adjust CPL signal lays the theoretical foundation of CPL device into practical application.