Because of low cost, fast response time, and high light transmittance, thin-film-transistor （TFT） driven twisted nematic （TN） liquid-crystal displays （LCDs） have been widely used in calculators, computer screens...Because of low cost, fast response time, and high light transmittance, thin-film-transistor （TFT） driven twisted nematic （TN） liquid-crystal displays （LCDs） have been widely used in calculators, computer screens, and cell phones. The pretilt angle of the TN medium within the TFT-TN panel affects not only its response times and view- ing angles but also the light-leakage positions of fringed- field-induced disclination lines within pixels of theTFT-TN panel.展开更多
On the basis of two-parameter formula of weak surface coupling anchoring energy of nematic liquid crystals proposed by Zhao et al recently, the general torque equilibrium equation and boundary conditions of the direct...On the basis of two-parameter formula of weak surface coupling anchoring energy of nematic liquid crystals proposed by Zhao et al recently, the general torque equilibrium equation and boundary conditions of the director have been obtained and the threshold field as well as the saturation field of the field-induced twist cell have been analysed for three kinds of configurations, i.e. homogeneous, splay and Pi ceils formed by different rubbing conditions and pretilt angles. The results indicated that the polar anchoring has no effect on the threshold field. It is determined only by the twist anchoring and pretilt angle. But, the polar anchoring and twist anchoring are coupling with each other and have a great influence on the saturation field. The formulae for calculating the threshold field and saturation field are given. These results will be very useful in understanding surface physics and the design of liquid crystal cells.展开更多
Surface enhanced Raman scattering (SERS) spectroscopy was first utilized to study the photo-orientation behaviour of the photoreactive groups on a novel photo-alignment film surface and elucidate the generation mechan...Surface enhanced Raman scattering (SERS) spectroscopy was first utilized to study the photo-orientation behaviour of the photoreactive groups on a novel photo-alignment film surface and elucidate the generation mechanism of pretilt angle. The novel photo-alignment film was prepared by spin-coating a solution of ladderlike polysiloxane (LPS) bearing dual photoreactive group on an ITO surface and by irradiation with linear-polarized ultraviolet (LPUV) light A Si—H terminal compound (M) containing an identical photosensitive part has been used to fabricate a model film for SERS investigation.展开更多
Liquid crystal-nanoparticle composite systems have attracted particular attention for both academic interests and applications in inducing macroscopic alignment,altering electro-optic response of the liquid crystal ho...Liquid crystal-nanoparticle composite systems have attracted particular attention for both academic interests and applications in inducing macroscopic alignment,altering electro-optic response of the liquid crystal hosts,and generating ordered,tunable soft metamaterials.Herein,the synthesis of two shapes of CuInS_(2)nanoparticles,tremelliform-like CuInS_(2)and frame-like CuInS_(2),and their utilization in producing uniform homeotropic alignment of liquid crystals are reported.Through exploring the mechanism in detail,the crystal structures of CuInS_(2)nanoparticles were found to rely heavily on the reaction solvents during the growth process,which in turn play a significant role on the anchor of liquid crystal molecules.The achieved homeotropic alignment shows high thermal stability,owing to the outstanding stability of the CuInS_(2)nanoparticles.In addition,combining this feasible method with parallel-aligning technique,variable pretilt angles in a range of~0.9°to~7.2°could be continuously achieved.展开更多
The generation of pretilt angles for nematic liquid crystal aligned on the rubbed polyimide surface containing trifluoromethyl moieties has been investigated. The characters of the rubbed polyimide films were studied ...The generation of pretilt angles for nematic liquid crystal aligned on the rubbed polyimide surface containing trifluoromethyl moieties has been investigated. The characters of the rubbed polyimide films were studied by using X ray photoelectron spectroscopy(XPS) and atomic force microscopy(AFM). The uneven distribution extent of fluorine content along the depth of the polyimide films could be reduced by rubbing, thus the interaction between liquid crystal molecules and polyimide molecules decreased. It is also showed that the aggregation state of polyimide molecules was changed and polyimide chains aligned along the rubbing direction, so the orientation direction of the liquid crystal molecules was the same as the rubbing direction. The orientation effect of the liquid crystal molecules on the rubbed polyimide surface can be attributed to the combined effects of the Van der Waals dispersion interaction between polyimide and liquid crystal molecules, and the alignment of the orientation direction of polyimide chains with the rubbing direction.展开更多
文摘Because of low cost, fast response time, and high light transmittance, thin-film-transistor （TFT） driven twisted nematic （TN） liquid-crystal displays （LCDs） have been widely used in calculators, computer screens, and cell phones. The pretilt angle of the TN medium within the TFT-TN panel affects not only its response times and view- ing angles but also the light-leakage positions of fringed- field-induced disclination lines within pixels of theTFT-TN panel.
基金Project supported by the Theoretical Physics Special Foundation of the National Natural Science of China （Grant No 10447107）, the Natural Science Foundation of Hebei Province, China （Grant No A2006000675）, the Doctoral Foundation of Hebei Province, China （Grant No 05547001D-3）, the Key Project Foundation of North China Electric Power University, China （Grant No 200513002） and the Key Construction Project of Hebei Provincial University, China.
文摘On the basis of two-parameter formula of weak surface coupling anchoring energy of nematic liquid crystals proposed by Zhao et al recently, the general torque equilibrium equation and boundary conditions of the director have been obtained and the threshold field as well as the saturation field of the field-induced twist cell have been analysed for three kinds of configurations, i.e. homogeneous, splay and Pi ceils formed by different rubbing conditions and pretilt angles. The results indicated that the polar anchoring has no effect on the threshold field. It is determined only by the twist anchoring and pretilt angle. But, the polar anchoring and twist anchoring are coupling with each other and have a great influence on the saturation field. The formulae for calculating the threshold field and saturation field are given. These results will be very useful in understanding surface physics and the design of liquid crystal cells.
基金This work was supported by the National Natural Science Foundation of China (No. 50073028, 29974036, 20174047).
文摘Surface enhanced Raman scattering (SERS) spectroscopy was first utilized to study the photo-orientation behaviour of the photoreactive groups on a novel photo-alignment film surface and elucidate the generation mechanism of pretilt angle. The novel photo-alignment film was prepared by spin-coating a solution of ladderlike polysiloxane (LPS) bearing dual photoreactive group on an ITO surface and by irradiation with linear-polarized ultraviolet (LPUV) light A Si—H terminal compound (M) containing an identical photosensitive part has been used to fabricate a model film for SERS investigation.
基金the National Natural Science Foundation of China(Nos.51973007 and 51673008)the Beijing Natural Science Foundation of China(No.2192030)the National Key R&D Program of China(No.2018YFB0703703).
文摘Liquid crystal-nanoparticle composite systems have attracted particular attention for both academic interests and applications in inducing macroscopic alignment,altering electro-optic response of the liquid crystal hosts,and generating ordered,tunable soft metamaterials.Herein,the synthesis of two shapes of CuInS_(2)nanoparticles,tremelliform-like CuInS_(2)and frame-like CuInS_(2),and their utilization in producing uniform homeotropic alignment of liquid crystals are reported.Through exploring the mechanism in detail,the crystal structures of CuInS_(2)nanoparticles were found to rely heavily on the reaction solvents during the growth process,which in turn play a significant role on the anchor of liquid crystal molecules.The achieved homeotropic alignment shows high thermal stability,owing to the outstanding stability of the CuInS_(2)nanoparticles.In addition,combining this feasible method with parallel-aligning technique,variable pretilt angles in a range of~0.9°to~7.2°could be continuously achieved.
文摘The generation of pretilt angles for nematic liquid crystal aligned on the rubbed polyimide surface containing trifluoromethyl moieties has been investigated. The characters of the rubbed polyimide films were studied by using X ray photoelectron spectroscopy(XPS) and atomic force microscopy(AFM). The uneven distribution extent of fluorine content along the depth of the polyimide films could be reduced by rubbing, thus the interaction between liquid crystal molecules and polyimide molecules decreased. It is also showed that the aggregation state of polyimide molecules was changed and polyimide chains aligned along the rubbing direction, so the orientation direction of the liquid crystal molecules was the same as the rubbing direction. The orientation effect of the liquid crystal molecules on the rubbed polyimide surface can be attributed to the combined effects of the Van der Waals dispersion interaction between polyimide and liquid crystal molecules, and the alignment of the orientation direction of polyimide chains with the rubbing direction.
