• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.506-508
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• 2007

We studied the nematic liquid crystal (NLC) alignment capability with a new alignment method utilizing an inkjet printed polyimide (PI) layer. A good, uniform LC alignment was achieved by the good PI printing using a new alignment method. The pretilt angle generated on the printed PI layer using the alignment method was almost the same as that on printed PI layer using rubbing alignment method. In addition, the good electro-optical performances of the new aligned twisted nematic (TN) cell with printed PI surface was obtained

• Journal of Electrical Engineering and Technology
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• v.12 no.1
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• pp.284-287
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• 2017

This paper introduces liquid crystal (LC) alignment and its electro-optical properties in the LC cells with silver nanowire (AgNW) networks. The AgNW network was used as an electrode of LC cell as a substitute for an indium-tin-oxide (ITO) film. LC alignment characteristics in the LC cell using AgNW networks, which have two different sheet resistances of $60{\Omega}/m^2$ and $80{\Omega}/m^2$, were observed. The LC alignment characteristics including pretilt angle, LC alignment state, and thermal stability are similar irrespective of sheet resistance of AgNW network. However, twisted-nematic (TN)-LC cell normally operated when using AgNW network with sheet resistance of $80{\Omega}/m^2$. Electrooptical properties of TN-LC cell exhibited competitive performance compared to those of TN-LC cell based on conventional ITO electrode, which allow new approaches to replace conventional ITO electrode in display technology.

• Elastomers and Composites
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• v.58 no.1
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• pp.1-10
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• 2023

In this study, we investigate the liquid crystal (LC) alignment of LC cells created from plant-based polysaccharide derivatives, such as guar gum. Guar gum films exhibit satisfactorily high optical transparency in the visible light region (400-750 nm). For example, the transmittance of polyimide films, which are the most typically used LC alignment layers, is 87%, whereas that of guar gum films deposited onto a glass substrate at a wavelength of 550 nm is approximately 99%. The observed LC alignment depends on the rubbing depth. For example, an LC cell comprising a guar gum film fabricated via rubbing at rubbing depths of 0.1, 0.2, 0.3, and 0.4 mm exhibits a planar LC alignment, whereas it exhibits a vertical LC alignment at a rubbing depth of 0.5 mm. Additionally, the LC alignment is shown to be correlated with the total surface energy of the guar gum films. When the total surface energy of a rubbed guar gum film exceeds 58.10 mJ/m², an LC cell comprising the guar gum film exhibits a stable and vertical LC alignment. Therefore, guar gum can be used to realize the vertical alignment system of LC via a simple adjustment of the rubbing depth.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.534-537
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• 2007

To promote liquid crystal application of nanoimprint lithography, a polymer with new concept is proposed. The material consists of a polyamic acid for good LC alignment and an epoxy resin for good imprinting. The result of sum-frequency generation (SFG) vibrational spectroscopy proves that this material is a functionally gradient material. This material shows excellent capability as a nanoimprinting material as well as an LC alignment layer.

• Macromolecular Research
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• v.17 no.7
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• pp.506-515
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• 2009

We synthesized a series of polystyrene derivatives containing various side chain terminal moieties, such as phenoxymethyl, 4-methoxyphenoxymethyl, 4-fluorophenoxymethyl, 4-methylphenoxymethyl, and 4-trifluoromethoxyphenoxymethyl groups, using polymer analogous reactions, in order to investigate the effect of the side group on their liquid crystal (LC) alignment behaviors. The polymers containing 4-fluorophenoxymethyl, 4-methylphenoxymethyl, or 4-trifluoromethoxyphenoxymethyl side groups had lower surface energy values and the LC cells fabricated using the unrubbed films of these polymers showed homeotropic LC alignment behavior. The LC cells fabricated using the rubbed films of the polymers containing phenoxymethyl or 4-fluorophenoxymethyl groups showed homogeneous planar LC alignment behavior in which the LCs were aligned perpendicular to the rubbing direction. This homogeneous planar and perpendicular alignment behavior was ascribed to the favorable anisotropic interactions between the LC molecules and the side groups preferentially oriented perpendicular to the rubbing direction.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.9
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• pp.677-681
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• 2013

Apart from the deposition of alignment layer, alignment process needs to be involved for alignment of liquid crystal (LC) molecules. To simplify manufacturing process, several method were used such as rubbing, ion-beam irradiation, UV irradiation, and lithography. But, eventually it needs another treatment for LC alignment. Here, we suggested Si induced polyimide (PI) alignment layer at low temperature. Using this method, we are able to eliminate the alignment process and found that the alignment and electro-optic performance are much better than that of the rubbed PI LC cells. Compared to the rubbed PI cells, the response time was decreased by 70% and C-V characteristics have hysteresis-free.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.5
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• pp.382-386
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• 2019

The alignment characteristics of liquid crystal (LC) molecules on a solution-derived lanthanum zinc oxide (LZO) film under ion-beam irradiation were demonstrated. Using the solution process, an LZO film was fabricated on the glass substrate and cured at $100^{\circ}C$. Afterwards, ion-beam irradiation was performed following the LC alignment method. Using this film, an LC cell was fabricated and the characteristics of the LC alignment were verified. Cross polarizing microscopy and the crystal rotation method were used to investigate the alignment state of the LC molecules on the LZO films. Furthermore, field emission scanning electron microscopy and X-ray photoelectron spectroscopy were used to explore the effect of the ion-beam irradiation on the LZO film. Through these, it was confirmed that the ion-beam irradiation induced surface modification, which demonstrated anisotropic physical and chemical surface characteristics. Due to this, uniform LC alignment was achieved. Finally, the residual DC and anchoring energy of the LC cell based on the LZO films were measured using a capacitance-voltage curve.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.755-758
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• 2005

The mechanism responsible for liquid crystal (LC) alignment on solid substrates treated with mechanical rubbing or polarized UV is not understood. The results of x-ray reflectivity study of LC alignment on a large number of different alignment layers show that the anisotropy in the surface roughness of the substrate completely determines the LC alignment. The anchoring energy depends on the degree of roughness anisotropy and chemical interactions between the substrate and LC molecules.

• Transactions on Electrical and Electronic Materials
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• v.7 no.6
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• pp.305-308
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• 2006

We have studied liquid crystal (LC) aligning capabilities for homeotropic alignment and the control of tilt angles on the $SiO_{x}$ thin film by electron beam evaporation method. A high tilt angle of about $86.5^{\circ}$ was obtained, and also the suitable tilt angle of the NLC on the $SiO_{x}$ thin film at $20{\sim}50\;nm$ thickness with e-beam evaporation can be achieved. The uniform LC alignment on the $SiO_{x}$ thin film surfaces with electron beam evaporation can be achieved. It is considerated that the LC alignment on the $SiO_{x}$ thin film by electron beam evaporation is attributed to elastic interaction between LC molecules and micro-grooves at the $SiO_{x}$ thin film surface created by evaporation.

• 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.