Phase field method in capacitance characteristics of nematic liquid crystals with different initial alignments

Shu-kai WANG; Zhi-dong ZHOU

doi:10.3788/YJYXS20193404.0327

您当前的位置：

首页 >

文章列表页 >

Phase field method in capacitance characteristics of nematic liquid crystals with different initial alignments

Materials and Devices | 更新时间：2020-07-05

- Phase field method in capacitance characteristics of nematic liquid crystals with different initial alignments
- Chinese Journal of Liquid Crystals and Displays Vol. 34, Issue 4, Pages: 327-334(2019)
- 作者机构：
  
  厦门大学材料学院, 福建省特种先进材料重点实验室, 福建厦门 361000
- 作者简介：
- 基金信息：
- DOI：10.3788/YJYXS20193404.0327
  CLC： O753+.2;TM532.5
- Received：31 October 2018，
  
  Accepted：20 January 2019，
  
  Published：2019-04
- 稿件说明：
移动端阅览
Shu-kai WANG, Zhi-dong ZHOU. Phase field method in capacitance characteristics of nematic liquid crystals with different initial alignments[J]. Chinese journal of liquid crystals and displays, 2019, 34(4): 327-334.
DOI：

Shu-kai WANG, Zhi-dong ZHOU. Phase field method in capacitance characteristics of nematic liquid crystals with different initial alignments[J]. Chinese journal of liquid crystals and displays, 2019, 34(4): 327-334. DOI： 10.3788/YJYXS20193404.0327.

摘要

液晶盒内的液晶分子在不同的外加电场作用下重新排布，其极化指向发生改变，从而影响液晶盒整体的电学特性。本文考虑液晶材料的挠曲电效应，分析液晶盒的整体自由能表达式，包含弹性形变自由能密度、介电自由能密度和挠曲电自由能密度。基于液晶弹性理论和相场方法，构建描述液晶核指向矢分布及演化的相场方程，并运用离散方法推导出液晶盒约化电容的表达式。讨论边界强锚定的混合液晶盒（HAN）和平行液晶盒（PAN）表面电荷密度对液晶核指向矢偏转角的影响。进一步分析了挠曲电系数、表面电荷密度以及液晶盒厚度对两种不同初始指向分布液晶盒电容性能的影响。数值分析结果表明，表面电荷密度越大、挠曲电系数越小，液晶核指向矢偏角越大。在混合液晶盒中，约化电容随着表面电荷或液晶厚度的增加而增加，最终趋于饱和；而在平行液晶盒中，当表面电荷密度或液晶盒厚度达到某个临界值时，液晶核的指向矢才发生改变，液晶的约化电容才有明显的变化。随着表面电荷密度增加，液晶核指向矢发生偏转的临界厚度减小。

Abstract

Subjected to different electric fields

liquid crystal molecules would rearrange and the polarization directors would change

which could affect the capacitance characteristics of liquid crystal cells. Based on the free energy of liquid crystals due to the flexoelectric effect

the expressions of the elastic

dielectric and flexoelectric free energy density are obtained. Applying the elastic theory and the phase filed methods of liquid crystals

the phase field equations describing the distribution and switching of liquid crystal director are obtained

and the expression of the capacitance of the liquid crystal cell is derived by discrete methods. The influences of the surface charge density on the liquid crystal directors are discussed in the strong anchoring hybrid alignment nematic (HAN) and the parallel alignment nematic (PAN) liquid crystal cells. Furthermore

the effects of flexoelectricity

surface charge density and the thickness of the liquid crystal cell on the capacitance performance of two different initial alignments are analyzed in detail. The results of numerical analysis show that the larger surface charge density and the smaller flexoelectric coefficients would induce the larger angle of the director. In the HAN liquid crystal cell

the capacitance increases with increasing surface charge or liquid crystal thickness

and finally becomes saturated. In the PAN liquid crystal cell

the liquid crystal directors switch only upon the surface charge density or the thickness of the liquid crystal cell reaching a certain critical value

and the capacitance of the liquid crystal changes significantly. With increasing surface charge density

the critical thickness of the liquid crystal cell decreases.

关键词

Keywords

references

谢毓章.液晶物理学[M].北京:科学出版社, 1998:61-66.

XIE Y Z. The Physics of Liquid Crystals [M]. BeiJing:Science Press, 1998:61-66.

YANG D K, Wu S T. Fundamentals of liquid crystal devices [M]. John Wiley & Sons Ltd, 2006:274

MORRIS S W. Measurements of the elastic constants of a liquidcrystal[D]. Vancouver: University of British Columbia, 1985.

WELFORD K R, MINERS F, SAMBLES J R. A new technique for determining the dielectric constants of a nematic liquid crystal[J]. Journal of Physics D, Applied Physics, 1988, 21(9):1320.

温庆祥, 黄锡珉, 何林, 等. C-V法液晶弹性常数的测定[J].液晶通讯, 1993(1):73-78.

WENG Q X, HUANG X M, He L, et al . Measurement of liquid crystal elastic constants by C-V method[J]. Chinese Letter of Liquid Crystal, 1993(1):73-78.

孔祥建, 荆海, 黄霞, 等.一种改进的C-V方法对向列相液晶弹性常数k 11 、k 33 测量的理论研究[J].液晶与显示, 2007, 22(5):587-590.

KONG X J, JIN H, HUANG X, et al . Theoretical research of improved C-V method to measure k 11 and k 33 of nematic liquid crystals[J]. Chinese Journal of Liquid Crystals and Displays, 2007, 22(5):587-590.

崔文静, 邢红玉, 张艳君, 等.挠曲电效应对向列相液晶盒电容的影响[J].数值计算与计算机应用, 2012, 33(2):129-137.

CUI W J, XIN H Y, ZHANG Y J, et al . Influence of the flexoelectric effect on the capacitance of nematic liquid crystal cell[J]. Journal on Numerical Methods and Computer Applications, 2012, 33(2):129-137.

崔文静, 邢红玉, 张艳君, 等.混合排列向列相液晶盒电容特性研究[J].液晶与显示, 2012, 27(5):608-612.

CUI W J, XIN H Y, ZHANG Y J, et al . Capacitance characteristics of hybrid aligned nematic liquid crystal cell[J]. Chinese Journal of Liquid Crystals and Displays, 2012, 27(5):608-612.

YE W J, XING H Y, CUI W J, et al . Determining the sum offlexoelectric coefficients in nematic liquid crystals by the capacitance method[J]. Chinese Physics B, 2014, 23(11):414-421.

MURAUSKI A, CHIGRINOV V, MURAVSKY A, et al . Determination of liquid-crystal polar anchoring energy by electrical measurements[J]. Physical Review E, 2005, 71(1):061707.

顾利忠, 苏菲, 赵颉, 等.用瞬态激振法测量微机械材料的弹性模量[J].清华大学学报(自然科学版), 2001, 41(9):126-128.

GU L Z, SU F, ZHAO J, et al . Measurement of Young's modulus for micro-machined materials using transient excitation[J]. Journal of Tsinghua University, 2001, 41(9):126-128.

Meyer R B. Piezoelectric effects in liquid crystals[J]. Physical Review Letters, 1969, 22(18):918-921.

Gennes P G D. Polymeric liquid crystals:Frank elasticity and light scattering[J]. Molecular Crystals, 1976, 34(8):177-182.

崔文静, 邢红玉, 叶文江, 等.液晶可调电容器的研究[J].液晶与显示, 2013, 28(2):173-178.

CUI W J, XIN H Y, YE W J, et al . Liquid crystal tunable capacitor[J]. Chinese Journal of Liquid Crystals and Displays, 2013, 28(2):173-178.

KAUR S, PANOV V P, GRECO C, et al . Flexoelectricity in an oxadiazole bent-core nematic liquid crystal[J] . Applied Physics Letters, 2014, 105(22):022505.

RESHETNYAK V Y, PINKEVYCH I P, COOK G, et al . Two-beam energy exchange in a hybrid photorefractive-flexoelectric liquid-crystal cell[J]. Physical Review E, 2010, 81:031705.

VITORIANO C, SáTIRO C. Consequences of director-density coupling theory for flexoelectricity in nematic liquid crystals[J]. Physical Review E, 2016, 93(2):022702.

OATES W S, WANG H. A new approach to modeling liquid crystal elastomers using phase field methods[J]. Modelling and Simulation in Materials Science and Engineering, 2009, 17(6):064004.

KISCHKA C, PARRY-JONES L A, ELSTON S J, et al . Measurement of the flexoelectric coefficients e 1 and e 3 in nematic liquid crystals[J]. Molecular Crystals and Liquid Crystals, 2008, 480(1):103-110.

VITORIANO C. Generalization of the Ericksen-Leslie theory[J]. European Physical Journal E, 2017, 40(4):48.

ZHOU Z D, WU D Y. Domain structures of ferroelectric films under different electrical boundary conditions[J]. AIP Advances, 2015, 5(10):107206.

Views

下载量

CSCD

Alert me when the article has been cited

提交

Tools

Publicity Resources

Dielectric and flexoelectric properties of nematic liquid crystal with chiral dopants in a concentric cylindrical cell

Effect of capacitance on common voltage in TFT-LCD

Research and improvement of dark corner Mura in TFT-LCD

Low coherence carrier frequency interference method for measurement of the liquid crystal cell surface

Dielectric properties of fluorine-containing tricyclic NCS liquid crystal materials

Related Author

LI Zhi-guang

ZHANG Yan-jun

ZHENG Gui-li

ZHANG Hui

HAN Yue

GAI Wen-ya

MA Zi-han

SUN Gui-jiao

Related Institution

School of Science， Hebei University of Technology

Fuzhou BOE Optoelectronics Technology Co., Ltd.

HeFei XinSheng Optoelectronics Technology Co., Ltd.

School of Electronic and Optical Engineering, Nanjing University of Science and Technology

Advanced Launching Co-innovation Center, Nanjing University of Science and Technology

AI问答

Address：No.3888 Dong Nanhu Road, Changchun, Jilin, China 130033 Postal code：130033
Tel：0431-86176059 Email：yjxs@ciomp.ac.cn
Technical support is provided by Beijing Founder electronics co., LTD 吉ICP备11002662号-17 京公网安备11010802024621
It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.

⁰