Research On Photoelectric Properties Of α-Cyanostilbene Derivatives Molecules Doped With Cholesteric Liquid Crystal

Luminescent liquid crystal materials have attracted widespread attention recently. They can emit visible fluorescence and have a certain compatibility with liquid crystal. They can simplify the structure of device and increase the efficiency of luminescence brightness and contrast. The organic photoelectric materials with aggregation induced enhanced emission effect have potential applications in the field of chemical, biological and physical. Thus liquid-crystal molecule ((Z)-2-(4-aminophenyl)-3-(4-(dodecyloxy) phenyl)-acrylonitrile, CN-APHP) was designed and synthesized, the specific research content as follows:1) We have designed and synthesized the liquid-crystal molecule CN-APHP, which exhibits strong fluorescence in the aggregation state. Ultraviolet absorption spectrum, fluorescence emission spectrum were used to study the photo physical property of the CN-APHP. Differential scanning calorimetry (DSC) and polarizing optical microscope (POM) were used to study the liquid crystal property of compound CN-APHP. The results indicate that a smectic liquid crystal was observed between 59 to 85 (C. The ordered orientated film of CN-APHP shows obvious luminous anisotropy and the linear polarization is 0.3.2) According to above research on physical and chemical of CN-APHP, we have successfully fabricated two optical switch devices. A tristable and electrically switchable optical switch based on luminescent molecule and cholesteric liquid crystal (CLC) is demonstrated. The CLC can be switched among the planar state, focal conic state and fingerprint state using the electric field. The interaction between the luminescent molecules and indium tin oxide substrate can be modulated by controlling the orientation of the luminescent molecules, which determine the stability of the three states. The optical property and fluorescent intensity of these states depend on the arrangement of liquid crystal molecules and all the three states can exist for several hours at room temperature without any observable change. Such a multi-stable electrical switch is simple to be fabricated, easy to be operated, and has low power consuming. It, therefore, has the potential to be used in practical portable information systems.3) We found reversible photo/thermal isomerization of the a-cyanostilbenic derivative (Z)-2-(4-aminophenyl)-3-(4-(dodecyloxy)phenyl)-acrylonitrile, (Z)-CN-APHP, which is accompanied by a large decrease in compatibility when mixed with a nematic liquid crystal. A luminescent liquid crystal device based on the isomerization of CN-APHP which can be modulated by photo in two states is fabricated. Moreover, a novel optical switch using a CN-APHP doped liquid crystal that emits partially linearly polarized light is investigated. By controlling the trans-cis isomerization of CN-APHP, it is possibly to modulate not only photo-luminescence intensity but also its polarization. This could open possibilities to design improved optical Devices.