激光倍频器件定向方法

用偏光显微镜解决了X射线技术确定倍频器件取向的困难。把这二种方法结合起来可以圆满地解决定向问题。     

聚合物分散液晶的电场诱导定向聚合实验研究

实验研究了聚合物分散正性和负性向列相液晶的电场诱导定向聚合,给出样品实物照片和偏光显微镜照片。实验结果表明,样品在施加电场和不施加电场的不同区域具有明显区别,在制备聚合物分散液晶样品时施加电场有诱导定向聚合作用。实验结果对于研究聚合物边界条件对液晶微滴构型的影响,对于设计新型液晶显示器件具有一定的启示意义。     

激光诱导向列相液晶分子重新取向的研究

用液晶分子运动的动力学方程,求出了激光诱导向列相液晶分子重新取向的取向角、折射率改变、阈值场强和上升时间的近似表达式。讨论了它们随液晶材料参数、激光强度和激光在液晶中传播方向的变化,进行了数值计算。给出了激光能诱导向列相液晶分子重新取向的必备条件,得到向列相液晶的各向异性是其分子重新的取向的根本原因。     

带有预倾角的液晶垂直定向的研究

文中介绍了用ＪＡＬＳ－２０４定向液获得向列型夜晶垂直定向的原理和方法。文中对涂膜，烘烤，磨擦等工艺因素作了描述，并给出了预倾角，对比度，响应速度的实测数据。     

向列相液晶定向过程中向错的研究

对向列相液晶定向过程中向错的产生原因进行了仔细的研究和分析，并提出了消除向错的一些办法，为向列相液晶制作工艺的研究和确定了理论和实验的参考。     

激光辅助生产液晶显示器

激光辅助生产液晶显示器激光已用在液晶显示器的生产上，新崛起的激光设备与工艺不久将对生产起到更重要的作用。最普遍的应用是激光消除短路（导线之间不应有的相连），修复开路（线路断开）的新方法也正被大家接受。对许多生产厂特别是主动列阵液晶显示器的制造厂来说，...     

激光辅助生产液晶显示器

激光辅助生产液晶显示器激光已用在液晶显示器的生产上，新崛起的激光设备与工艺不久则将对生产起到更重要的作用。最普遍的应用是激光消除短路（导线之间不应有的相连），而修复开路（线路断开）的新方法也正被大家所接受。对许多生产厂（特别是主动列阵液晶显示器的制造...     

波前场曲对激光诱导液晶远场衍射环的影响

为了明确入射激光参量对激光诱导衍射环的影响及其机理,利用菲涅耳-基尔霍夫衍射积分公式,数值模拟研究了高斯光束波前场曲对于高斯光束通过自散焦液晶介质后远场衍射图样的影响.结果表明,当波前场曲为无穷大时,随着光强的逐渐增大,远场衍射光斑中心明暗交替变化;当波前场曲为正时,随着波前场曲的减小,远场衍射光斑中心强度逐渐变暗并且...     

一种新型液晶垂直取向膜

采用离子沉积法在玻璃基板表面制备了十四烷基磺酸盐自组装膜,用带有该自组装膜的基板制成的液晶器件呈现出垂直取向效果。通过自组装反应过程分析,认为自组装膜表面的纵向沟纹引起了液晶的垂直排列。实验发现,当自组装膜烷烃碳链长度大于11个C原子就可获得垂直取向。这种取向膜制作过程简单、热稳定性好,非常有望应用于多畴垂直取向模式的液晶显示器。     

Controlled Planar Alignment of Discotic Liquid Crystals in Microchannels Made Using SU8 Photoresist

A range of triphenylene and phthalocyanine‐based discotic liquid crystals (DLCs) can be aligned within micrometer‐scale channels formed from SU8 patterned on silicon or glass surfaces. The channels can be filled with the DLC in its isotropic phase using capillary action. Alignment occurs spontaneously as the sample is slowly cooled into the Col_h phase. Whilst all of these DLCs align with the columns perpendicular to the surface when they are ‘sandwiched’ between glass slides, in these channels, the DLC aligns with the column director parallel to the surface. It is also constrained to lie across the channels. The same alignment occurs when these DLCs are confined between SU8‐topped interdigitated gold electrodes where it gives the optimum orientation for electrode‐to‐electrode conduction. The quality of the alignment depends on the particular liquid crystal used and on the width of the channel. For the Col_r phase of octaoctylphthalocyanine there is additional epitaxial control over the orientation of the lattice such that the a/c face of the lattice is parallel to the surface. This is an important prerequisite for creating a bistable display device that switches by virtue of changing the direction of the tilt of the discs.     

侧链含稠环的新型聚酰亚胺液晶垂直取向剂的制备及表征

以3,5-二硝基苯甲酰氯、雌二醇及溴代正辛烷为原料合成了含有稠环结构的新型功能性二胺(H8-c)。用1,2,3,4-环丁烷四甲酸二酐(CBDA)、对苯二胺(PDA)及H8-c共聚制备了一种聚酰亚胺(PI)液晶垂直取向剂。该PI膜作为取向层制得的液晶盒,在120℃下烘烤12h仍可垂直取向,拥有良好的垂直取向热稳定性。热重分析(TGA)测试表明其具有良好的热稳定性,在氮气中,这种PI的5%热失重温度(T5)和10%热失重温度(T10)分别高达400℃和480℃。紫外可见光谱(UV-vis)显示此PI膜在400nm以上具有高的透过率,可达95%以上。     

Alignment of Rod‐Shaped Single‐Photon Emitters Driven by Line Defects in Liquid Crystals

Arrays of liquid crystal defects—linear smectic dislocations—are used to trap semiconductor CdSe/CdS dot‐in‐rods which behave as single‐photon emitters. Measurements of the emission diagram are combined together with measurements of the emitted polarization of the single emitters. It is shown that the dot‐in‐rods are confined parallel to the linear defects to allow for a minimization of the disorder energy associated with the dislocation cores. It is demonstrated that the electric dipoles associated with the dot‐in‐rods, tilted with respect to the rods, remain oriented in the plane including the smectic linear defects and perpendicular to the substrate, most likely due to dipole/dipole interactions between the dipoles of the liquid crystal molecules and those of the dot‐in‐rods. Using smectic dislocations, nanorods can consequently be oriented along a unique direction for a given substrate, independently of the ligands' nature, without any induced aggregation, leading as well to a fixed azimuthal orientation for the dot‐in‐rods' dipoles. These results open the way for the fine control of nanoparticle anisotropic optical properties, in particular, fine control of single‐photon emission polarization.     

空间各向异性两体势与液晶定向排列

基于分子场理论，研究一种新的空间各向异性两体作用势。对于该两体势，分子质心固定在简单立方晶格的格点上，而势参数依赖于液晶的弹性常数。通过函数迭代方法解分子取向分布函数满足的自洽方程。在大块液晶内部，存在3组单轴解，它们的指向矢分别沿x，y和z轴方向并且具有相同自由能。通过表面作用势描写摩擦后基板对液晶分子的作用，对20个分子层构成的5CB液晶薄层进行了数值计算。仍存在三种指向矢不同的状态，指向矢沿着摩擦方向的状态具有最低自由能。另外，讨论了表面作用在界面分子层中诱导的双轴序。     

Photoswitching of Ferroelectric Liquid Crystals Using Unsymmetrical Chiral Thioindigo Dopants: Photoinduced Inversion of the Sign of Spontaneous Polarization

A new unsymmetrical chiral thioindigo dopant 6‐[(R,R)‐2,3‐difluorooct‐1‐yloxy]‐5′‐nitro‐6′‐[(R)‐2‐octyloxy]thioindigo ( 4 ) designed to photoinvert the sign of spontaneous polarization (P_S) in a ferroelectric chiral smectic C (SmC*) liquid crystal was prepared using a synthetic approach previously developed in our laboratory. In this new “ambidextrous” design, the (R)‐2‐octyloxy side‐chain is sterically coupled to the thioindigo core and induces a positive P_S, whereas the (R,R)‐2,3‐difluorooctyloxy side‐chain is decoupled from the core and induces a larger negative P_S. In the trans form, this dopant induces a negative polarization in the SmC host (+)‐4‐(4‐methylhexyloxy)phenyl 4‐decyloxybenzoate ( PhB ). Irradiation of a 1 mol‐% mixture of 4 in PhB at λ = 510 nm caused a sign inversion of P_S, from –0.88 to +0.42 nC cm^–2 at T – T_C = –5 °C, which is consistent with an increase in the polarization power of the coupled 2‐octyloxy/thioindigo unit over that of the 2,3‐difluorooctyloxy unit, due to the increase in transverse dipole moment of the thioindigo core upon trans–cis photoisomerization. The P_S sign inversion was confirmed by a surface‐stabilized ferroelectric liquid crystal photoswitching experiment. Spectroscopic measurements on films of the doped liquid crystal mixtures showed that trans–cis photoisomerization is gradually suppressed with increasing dopant mole fraction, possibly as a result of increased dopant aggregation.     

Patterning Smectic Liquid Crystals for OFETs at Low Temperature

The preparation of regular microstructures with liquid crystalline materials for organic field effect transistors (OFETs) is an attractive but challenging issue. However, it is usually limited by the difficulty of forming large‐area single crystals aligned in a desirable direction. Herein, several terthiophene (TTP) smectic liquid crystals such as 8‐TTP‐8 and 12‐TTP‐11OH are patterned into highly crystalline microstripes by a sandwich system through a dewetting method. Morphology and orientation of the microstripes strongly depend on preparation temperature. Microstripes prepared below crystalline temperature are uniform, well‐ordered, and show high field effect transistor (FET) mobility. Meanwhile, π–π stacking direction of the TTP backbone is perpendicular to the microstripe and the molecules stack in layer structure, standing up on the SiO₂/Si substrate, which would provide an effective pathway for p‐type charge transport. However, higher preparation temperatures at liquid crystalline or isotropic liquid range induce many defects in the crystal formation process and cause incline of the unit cell, thus leading to a sharp decrease in FET mobility. A possible mechanism of molecular stacking at different temperature range is proposed. This strategy promised to provide a new opportunity for the high cost‐efficiency fabrication of OFETs.     

液晶垂直定向的研究

本文介绍了用长链醇和胺的混和液在高温下对镀膜基片处理获得向列型液晶垂直定向的方法,讨论了反应时间、反应温度等因素对定向的影响,并给出了实测结果。     

铁电液晶SmC*相介电特性的研究

建立了铁电液晶ＳｍＣ＾＊相介电特性的分子理论,求出在外加交变电场上流晶系统的自由能密度,得到极化强度〈＾→Ｐ〉和复介电常数ε＾＊的近似表达式。结果表明ε＾＊是外加交变电场的角频率、幅值、温度以及液晶的分子结构参数的函数。