• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.12
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• pp.1023-1026
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• 2001

The control of high pretilt angle for nematic liquid crystal (NLC) with negative dielectric anisotropy on the rubbed blending polyimide (PI) of homeotropic and homogeneous alignment surface was studied. High LC pretilt angle on the rubbing blending polyimide of homeotropic PI and SE-7492 surface was measured and the LC pretilt angle increased wish blending ratio and rubbing strength. However, the low LC pretilt angle on the rubbed blending polyimide of homeotropic PI and SE-150 surface was measured. The high pretilt angle of NLC can be achieved by using the blending PI surface.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.450-452
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• 2005

The ion beam alignment technique is one of the potential and fascinating methods. However, there are merely a few reports about aligning nematic liquid crystals (NLCs) horizontally for in-plane switching mode (IPS) by means of low energy ion beam exposure on inorganic materials such as DLC. In this study, we have investigated the tilted vertical alignment of NLC by the ion beam technique on the thin films of various amorphous silicon compounds as new inorganic alignment materials. Appropriate pretilt angles of NLC with preferred orientation on these thin films were achieved. And the electro-optic property of vertically aligned single domain cells has been investigated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.11
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• pp.1019-1022
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• 2003

We studied the nematic liquid crystal (NLC) aligning capabilities using the new alignment material of a-C:H thin film as working gas at 30W rf bias condition. A high pretilt angle of about 5$^{\circ}$ by ion beam(IB) exposure on the a-C:H thin film surface was measured. A good LC alignment by the IB alignment method on the a-C:H thin film surface was observed at annealing temperature of 250$^{\circ}C$, and the alignment defect of the NLC was observed above annealing temperature of 300$^{\circ}C$. Consequently, the high LC pretilt angle and the good thermal stability of LC alignment by the IB alignment method on the a-C:H thin film surface as working gas at 30W rf bias condition can be achieved.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.648-650
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• 2009

We investigate nematic liquid crystal (NLC) alignment on ion-beam exposed ZnO films. ZnO is optically transparent material in the visible range. We optimized the deposition parameters such as deposition temperature and gas ratio for high transmittance and resistivity. Using ion-beam treated ZnO films, LC cells are fabricated and the conditions such as exposure energy and time for uniform alignment are found. The NLC molecules align parallel to the ion-beam exposure direction. The electro-optic and response characteristics show the possibility of application of this method in liquid crystal display.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.259-262
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• 1998

The liquid crystal (LC) alignment and pretilt angle generation using photo-alignment method were investigated in this study. We obtained that the monodomain alignment of nematic(N) LC increases with increasing irradiation time in a cell with linearly polarized ultraviolet (LPUV) light irradiation on polyimide (Pl) surfaces. We consider that the monodomain alignment is able to be anisotropic dispersion force due to photo-depolymerization of polymer with LPUV light irradiation on Pl surface. Also, we observed that the uniform alignment of NLC is obtained in a cell with normally LPUV light irradiated on Pl surface at 30 min. and then oblique LPUV is secondly irradiated on Pl surfaces rotated by 90$^{\circ}$. The pretilt angle of NLC is generated about 1.5$^{\circ}$ with oblique angle 60$^{\circ}$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.3
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• pp.214-218
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• 2003

We studied the nematic liquid crystal (NLC) aligning capabilities by the UV alignment method on a diamond like carbon (DLC) thin film surface A good LC alignment by UV exposure on the DLC thin film surface at 200${\AA}$ of layer thickness was achieved. Also, a good LC alignment by the UV alignment method on the DLC thin film surface was observed at annealing temperature of 180$^{\circ}C$. However, the alignment defect of the NLC was observed above annealing temperature of 200$^{\circ}C$. Consequently, the good thermal stability of LC alignment by the UV alignment method o the DLC thin film surface can be achieved.

• Transactions on Electrical and Electronic Materials
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• v.7 no.6
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• pp.301-304
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• 2006

We studied the nematic liquid crystal (NLC) aligning capabilities using the new alignment material of the SiC (Silicon Carbide) thin film. The SiC thin film exhibits good chemical and thermal stability. The good thermal and chemical stability make SiC an attractive candidate for electronic applications. A vertical alignment of nematic liquid crystal by atomic beam exposure on the SiC thin film surface was achieved. The about $87^{\circ}$ of stable pretilt angle was achieved at the range from $30^{\circ}\;to\;45^{\circ}$ of incident angle. Consequently, the vertical alignment effect of liquid crystal electro-optical characteristic by the atomic beam alignment method on the SiC thin film layer can be achieved.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.263-266
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• 1998

In this study, the effect of the crystallinity of polyimide (Pl) and the birefringence of the nematic liquid crystal (NLC) for pretilt angle generation on rubbed PI surface containing thiophenylene moieties has been demonstrated. The induced optical retardation produced in rubbed Pl surfaces decreases on increasing the imidization temperature. We suggest that the pretilt angle of 4-cyano-4'-n-pentybiphenyl (5CB) depends on the crystallinity of the rubbed Pl. The order of pretilt angle in NLCs is 5CB>PCH5$\geq$CCH5 at rubbing strength(RS)=150mm (medium rubbing) on rubbed PI surfaces. We suggest that on rubbed Pl surfaces the pretilt angle increases with increasing number of phenylrings in the NLC core.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.10
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• pp.871-875
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• 2000

Effects of liquid crystal (LC) alignment using a in-situ photoalignment method by polarized UV exposure on a polyimide (PI) surface with medium side chain were studied. The generated pretilt angle in nematic(N) LC using a in-situ photoalignment method was smaller than that of a conventional photoalignment method for short UV exposure time. Also, the pretilt angle of NLC using a in-situ photoalignment method increases with increasing UV exposure time on the PI surfaces. Finally, the pretilt angle of NLC can be improved by annealing treatment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.549-552
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• 1999

We have developed an novel vertical-alignment (VA) - $\pi$ cell mode that provides a wide viewing angle and fast response times for negative dielectric anisotropy nematic liquid crystal (NLC) on a homeotropic polyimide (PI) surfaces. We had the good voltage-transmittance curves and low driving voltages were achieved with the novel VA - $\pi$ cell mode without negative compensation film. Iso-viewing angle characteristics using the novel VA - $\pi$ cell mode without negative compensation film of NLC was also successfully observed. As well a fast response time of 31.7ms for the novel VA - $\pi$ cell mode was measured. Consequently, It is seen that by using the novel VA - $\pi$ cell mode the iso-viewing angle, fast response time, and low driving voltage characteristics can be achieved.