Some Unusual Electro-optical and Photo-optical Properties of Doped Liquid Crystals

• 作 者: Xia Tong Guang Wang Yue Zhao
• 机 构: D(e)partementdechimie,Universit(e)deSherbrooke,Sherbrooke,Qu(e)bec,CanadaJ1K2R1
• 出 处: 第二届液晶光子学国际会议暨3D论坛
• 发表日期: 2013年4期

　　Our studies on doped liquid crystals (LCs) have led to the discovery of two interesting phenomena that may be exploited for photonic applications.On one hand,1,2 when a nematic LC is doped with a large amount of a LC azobenzene compound (>15 wt%),the trans-cis photoisomerization of azobenzene upon UV and visible light irradiation can give rise to multiple reversible and interconvertible photochemical processes in the LC host,such as disordering,phase transition and phase separation.Both normal and reverse mode of photocontrolled switching of transmittance through crossed polarizers can be realized using a same mixture of LC/azobenzene dopant.On the other hand,3,4 when a cholesteric LC contains a dispersion of fluorescent nanofibres or quantum dots (QDs),the reversible change in liquid crystal orientational state in response to an applied voltage changes the internal scattering of the excitation light and thus the excitation degree of the dispersed nanofibres or QDs.This leads to electrically controllable fluorescence emission of the mixture.By configuring the change in the LC orientational state,two modes of photoluminescence switching can be achieved,i.e.,high intensity at field-off and low intensity at field-on state,and vice versa.