Preparation And Research On Properties Of The Highly Polarized Luminescent Thin-flim

Polarized luminescence is important because it is useful for many optoelectronic applications,such as optical information storage devices,stereoscopic displays,and liquid crystal displays.Liquid crystals(LCs)have long-range orientation ordering with relatively free movement of anisotropic molecules.LCs form supramolecular assemblies with unidirectional orientations of the molecular axis in nature to produce optical anisotropy.Luminescent liquid crystals(LLCs)are rapidly emerging as an important optical class of materials,which possess the properties of intrinsic light emission and unique supramolecular organization.The aggregation-induced enhanced emission(AIEE)effect endows LLCs with great potential in many practical applications,which is an ideal material to explore the polarized luminescence.The dichroism of dyes is a characteristic of the anisotropy of the molecular transition moment in either absorption or emission,which is also an ideal material to research the polarized luminescence.Thus,an AIEE-active luminescent LC molecule,a highly ordered LC molecule and a class of dichroic luminescent dyes was designed and synthesized,the specific research content as follows:1)In this study,a novel AIEE-active LLC molecule,2-(4-(nonanealkoxy)phenyl)-3-(4-formamidephenyl)-acrylonitrile(CN-NPFA),was designed and synthesized,which shows a high fluorescent quantum yield in the solid state((?)f=0.44).1H NMR spectra,13C NMR spectra,infrared spectra and mass spectra were used to characterize the molecular structure.Ultraviolet absorption spectrum and luminescence emission spectrum were used to study the photo physical properties of the CN-NPFA.Differential scanning calorimetry(DSC)and polarizing optical microscope(POM)were used to study the mesomorphic properties of the CN-NPFA.The results indicate that three liquid crystal phase were observed between 116 ? to 182 ?.2)A well-aligned liquid crystalline film using AIEE-active molecules,is obtained using an in-plane electric field with an alignment layer.It exhibits highly polarized luminescence(?= 0.74)with a high luminescence quantum yield.The in-plane electric field induce the uniaxial orientation of the CN-NPFA molecules,in which the polarization direction of the CN-NPFA molecules follows the electric field direction and the long molecular axis of the CN-NPFA molecules follows the rubbing direction.Upon excitation,the oriented LLC film emits linearly polarized light with high degree of polarization.The device is both cheap and easy to fabricate,and has the potential to be used in practical electro-optic applications.3)On the research on such an orientation experiment,it is expected that polarized degree can be further improved.A LC monomer 4-(4-(6-(acryloyloxy)hexyloxy)phenethyl)phenyl-4-(6-(Acryloyloxy)hexyloxy)benzoate(AHPPAHB)and a major class of luminescent dichroic dyes 4,7-Bis(4-hexyloxy acrylate)phenyl)benzo-2,1,3-thiadizole(BHAPBT),4,7-Bis(4-nonyloxy acrylate)phenyl)benzo-2,1,3-thiadizole(BNAPBT),4,7-Bis(4-undecyloxy acrylate)phenyl)benzo-2,1,3-thiadizole(BUAPBT)and 4,7-Bis(4-nonylalkoxy)phenyl)benzo-2,1,3-thiadizole(BNPBT),was designed and synthesized.1H NMR spectra,13C NMR spectra,infrared spectra and mass spectra were used to characterize the molecular structure.DSC and POM were used to study the mesomorphic properties of the AHPPAHB.Ultraviolet absorption spectrum and luminescence emission spectrum were used to study the photo physical properties of the BHAPBT,BNAPBT,BUAPBT and BNPBT.The results indicate that AHPPAHB molecule possess three liquid crystal phase,especially possess a highly ordered smectic B(SB)phase.The luminescent dichroic dyes shows highly dichroic ratio and luminescence quantum yield.4)Highly polarized absorption and emission luminescent thin-film,is obtained using reactive liquid crystalline monomers(AHPPAHB)and highly dichroic luminescent dyes which both have polymerizable end groups.In situ photopolymerization of the liquid crystalline mixtures in the highly ordered SB phase resulted in the formation of cross-linked polymeric networks in which the anisotropic absorption and emission of the film was fixed.It exhibits highly dichroic ratio values(DR=30)with a high fluorescence quantum yield((?)F=0.77).The effect of the polymerizable acrylate groups and the length of the guest dye molecules on the alignment was compared and analyzed.The thermal stability of the anisotropic films obtained was also investigated.