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The surface modifications and liquid crystal (LC) alignment properties of polystyrene‐block‐poly(ethylene‐ran‐butylene)‐block‐polystyrene‐graft‐maleic anhydride (SEBS‐g‐MA) films induced by ion‐beam (IB) irradiation are reported herein. Changes to the surfaces of the SEBS‐g‐MA films from IB irradiation at various incidence angles and changes in the LC orientations upon LC cell fabrication were analyzed. The physical surface modifications due to IB irradiation were observed via atomic force microscopy. Additionally, changes in the molecular composition of the surface were observed through X‐ray photoelectron spectroscopy analysis. Polarized optical microscopy analysis shows that excellent LC alignment properties could be obtained after IB irradiation at angles exceeding 45°. Further, the anisotropy caused by IB irradiation was more responsible for uniform LC alignment than the corrugated pattern. [ABSTRACT FROM AUTHOR]

This paper introduces the vertically aligned twisted nematic in-plane switching (VPS) structure, and compares the electro-optical (EO) characteristics of VPS liquid crystal displays (LCDs) and in-plane switching (IPS) LCDs. Various VPS-LCD pretilt angles were induced, and ion beam (IB) irradiation was used to enhance the EO properties. An x-ray photoelectron spectroscopic analysis of the IB-irradiated polymer surface confirmed that the intensity of C=O bonding as a function of exposure time traced the pretilt angles. The pretilt angle effect on optical properties was first analyzed in the experimental results. While multidomain vertical alignment LCDs and IPS-LCDs only resolve one difficulty, the VPS-LCDs described here overcome several viewing angle and transmittance curve problems. [ABSTRACT FROM AUTHOR]

We investigated the effects of ion beam (IB) irradiation and rubbing on the directional behavior and alignment mechanism of liquid crystals (LCs) on polyimide (PI) surfaces. We found that the LC direction follows the IB irradiation alignment direction on the PI surface regardless of whether the irradiation occurs before or after rubbing. We assumed that the LC direction depends strongly on the C–O bonds created from C=O bonds on the PI surface broken by IB irradiation and conducted an investigation of the chemical bonding state of the PI surface by x-ray photoelectron spectroscopy. [ABSTRACT FROM AUTHOR]

The surface modification characteristics of liquid crystal (LC) alignment layers irradiated with various argon (Ar) ion beam (IB) energies were investigated as a substitute for rubbing technology. Various pretilt angles were created on the IB-irradiated polyimide (PI) surfaces after IB irradiation, but the Ar ions did not alter the morphology on the PI surface, indicating that the pretilt angle was not due to microgrooves. The chemical bonding states of the IB-irradiated PI surfaces were analyzed in detail by x-ray photoelectron spectroscopy to verify the compositional behavior for the LC alignment. Chemical structure analysis showed that the alignment ability of LCs was due to the preferential reorientation of the carbon network due to the breaking of C=O double bonds in the imide ring parallel to the incident IB direction. The potential of applying nonrubbing technology to display devices was further supported by the superior electro-optical characteristics compared to rubbed PI. [ABSTRACT FROM AUTHOR]

We investigated the induced uniform alignment of liquid crystals (LCs) on a polyurethane (PU) ion-beam (IB) irradiated at a certain incidence angle. Polarized optical microscopy (POM) and the crystal rotation method were used to evaluate the LC alignment state. On PU films IB-irradiated with incidence angles of 60° or less, the LC cells exhibit a clear and uniform alignment. At an incidence angle of 75°, light scattering was observed via POM, indicating the randomly aligned state of the LC cells. Moreover, the calculated pretilt angles for LC cells on IB-irradiated PU at incidence angles of 15°, 30°, 45°, and 60° were 0.05°, 0.05°, 0.20°, and 0.18°, respectively. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were used to confirm the effect of varying the IB irradiation incidence angle. The PU surface irradiated by IB was modified differently as the incidence angle changed. IB irradiation at low incidence angles broke C–C, C–O/C–N, and N–C(O)–O bonds and caused C=O bond formation by the dissociation of the N–C(O)–O bonds. The van der Waals interactions between the PU and LC matched the LC molecular interactions and the anisotropic characteristics could be maintained, thereby achieving a stable homogeneous LC alignment. [ABSTRACT FROM PUBLISHER]

In this paper, solution-derived gallium oxide (GaO) films are fabricated for the homogeneous alignment of liquid crystals (LCs) after an ion-beam (IB) irradiation process. GaO thin films are prepared under a variety of temperatures and different IB irradiation intensities, and the physicochemical performances of the fabricated GaO thin films are analysed using a UV-vis spectrometer, an atomic force microscope, and X-ray photoelectron spectroscopy. A higher transmittance of 85.40% from GaO thin film is obtained compared with that of polyimide (PI) film (83.52%), which indicates the feasibility for a GaO thin layer to substitute for a conventional PI layer as an alignment layer. LCs are found to align on the GaO thin film after pre-baking at 100°C and homogeneous and uniform low-IB intensity irradiation. We also determined the electro-optical (EO) characteristics of the twisted nematic (TN) cells fabricated with GaO thin layers and found them to be similar to those of cells fabricated with PI layers. Overall, GaO films achieved via the IB irradiation method are promising LC alignment layers due to the method’s low-temperature solution-derived process. [ABSTRACT FROM AUTHOR]

We demonstrate homogeneous and uniform liquid crystal (LC) alignment on poly(vinylidene fluoride-trifluoroethylene) [PVDF-TrFE] films using ion-beam (IB) irradiation and a performance improvement of twisted nematic (TN) cells using IB-irradiated PVDF-TrFE films. Spontaneous ferroelectricity of the PVDF-TrFE films was modified by IB irradiation, which affected the LC alignment properties. The variation in the pre-tilt angles of the LC molecules on the IB-irradiated PVDF films is attributed to surface reformation, including defluorination and oxidation because the pre-tilt angles of LC molecules can be controlled by adjusting the fluorine content. The results of contact angle measurements supported this phenomenon. A 58% reduction in the switching voltage was observed for TN cells, indicating that the IB-irradiated PVDF-TrFE films are a promising candidate for use as an alignment layer. [ABSTRACT FROM AUTHOR]

This report discusses homogeneously aligned liquid crystals (LCs) subjected to ion-beam (IB) irradiation of the amorphous(a)-Al2O3 alignment layer. We studied the relationship between LC alignment and IB alignment conditions acting on homogeneous surfaces. We attained homogeneous LC orientations on a- Al2O3 alignment layer by optimization between the van der Waals interactions caused by Al-O bonding breaking with x-ray photoelectron spectroscopy. The voltage-transmittance characteristics of the twisted nematic – liquid crystal displays (LCDs) on the a-Al2O3 film indicate potential for use as the LC alignment layer in various LCD display applications. [ABSTRACT FROM PUBLISHER]

This paper introduces the characteristics of the zirconium dioxide (ZrO2) inorganic film deposited by radio-frequency magnetron sputtering. The homogeneously aligned liquid crystal (LC) on ZrO2 layer via ion beam (IB) irradiation at various incident angles was embodied with LC alignment capability and performance. The x-ray photoelectron spectroscopic (XPS) data shows that O-Zr bonds on the ZrO2 surface are broken and induce the van der Waals force for the homogeneous alignment of LCs. That is the van der Waals force, affecting the alignment of the LCs, is verified by the contact angle of the liquid and by the XPS analysis on the ZrO2 thin film. In addition, the advantage of IB alignment method is verified by using atomic force microscope (AFM). [ABSTRACT FROM PUBLISHER]

We present the characteristics of titanium dioxide (TiO2) inorganic film deposited by RF magnetron sputtering for liquid crystal display applications in this paper. TiO2 films supported vertically aligned liquid crystal (LC) molecules based on ion-beam (IB) irradiation time dependence. Uniform alignment was obtained only when the incident time was two minutes with 1.8 keV of incident energy and an incident angle of 45°. Energy from uniform high-density plasma by IB irradiation affected the interaction between the TiO2 layer and LC molecules to produce vertical alignment of the LC molecules. [ABSTRACT FROM PUBLISHER]

The authors introduce variable liquid crystal (LC) properties via ion beam (IB) irradiation on the ZrO2 layers. A uniform LC alignment characteristic was achieved on the ZrO2 thin film, and the pretilt angle was about 1.2°. We have shown that the pretilt angle can be controlled by changing ion beam parameters, such as the ion beam energy, the angle of incidence, and the irradiation time. The low pretilt angle for the nematic liquid crystal (NLC) on the ZrO2 thin film treated by ion beam irradiation could be adopted in planer alignment LCD liquid crystal display (LCD) applications as in-plane switching and fringe-field switching modes. The thermal stability of the ZrO2 thin film was sustained until 210°C. We also have shown that a liquid crystal cell aligned homogeneously by the ion beam irradiation exhibits the voltage-transmittance curve similar to that of a rubbed polyimide cell. [ABSTRACT FROM PUBLISHER]

Liquid crystal alignment using ion beam (IB) irradiated a-C:H films on either plastic or glass substrates can be affected by the type of topographical structure. Strong IB irradiation induces greater roughness to the micro-groove on a plastic substrate, leading to a device with increased pretilt angle, fast response time and reduced threshold voltage. In contrast to the hysteresis in the transmittance-voltage curve of the rubbed polyimide film, which rapidly increases with increasing thermal and UV stress time, study of the residual DC voltage revealed no hysteresis on an a-C:H film due either to thermal or UV stress. [ABSTRACT FROM AUTHOR]

Nematic liquid crystal alignment capabilities and electro-optical performance characteristics have first been embodied in a ZrO2 layer using ion-beam irradiation. The study demonstrates that liquid crystal layers can be aligned homogeneously as a function of the incident angle of the ion beam device, which causes a uniform dense plasma. X-ray photoelectron spectroscopy indicated that full oxidation of the ZrO2 thin-film surfaces was produced by ion irradiation, shifting the Zr 3d spectra to lower binding energies. In addition, the electro-optical performance characteristics of twisted nematic cells on a ZrO2 thin-film layer after ion beam irradiation showed similar characteristics to those of a rubbed polyimide cell. [ABSTRACT FROM AUTHOR]

Ion-beam irradiation (IB) on HfO2 surface induced high-performance liquid crystal (LC) driving at a 1-V threshold with vertical alignment of liquid crystals (LC). The high-k materials Atomic layer deposition was used to obtain LC orientation on ultrathin and high-quality films of HfO2 layers. To analyze surface morphological transition of HfO2 which can act as physical alignment effect of LC, atomic force microscopy images are employed with various IB intensities. The contact angle was measured to elucidate the mechanism of vertical alignment of LC on HfO2 with IB irradiation. Contact angle measurements show the surface energy changes via IB intensity increasing. [ABSTRACT FROM AUTHOR]

In this study, we explored the effects of ion beam (IB) bombardment on the orientation of liquid crystal (LC) molecules on Ta2O5 surfaces. Increasing the lB exposure time resulted in improved LC alignment characteristics. Through X-ray photoelectron spectroscopy analysis, it was also confirmed that LB irradiation caused Ta 4f and 0 Is peak shifts in the positive direction. The breaking phenomenon of the 0 Is bonds may cause anisotropic dipole-dipole forces to stably align the vertical LC molecules. Finally, measuring the contact angles on the lB irradiated Ta2O5 surfaces, we concluded that increasing the LB irradiation time strengthened the anisotropic surface energy on the Ta2O5 surfaces, and stable vertical LC alignment was achieved via the transformed surface energies. [ABSTRACT FROM AUTHOR]

The nematic liquid crystal alignment capability and electro-optical (EO) performance characteristics of in-plane switching (IPS) cells were first demonstrated on organic hybrid overcoat layers via ion beam irradiation. Usually the organic hybrid overcoat is used as the material for making a plate alignment layer in a colour filter process. To characterise the organic hybrid overcoat layer, we analysed the surface composition of the organic hybrid overcoat by X-ray photoelectron spectroscopy. The results show that the intensity of C = O and C-O bonding undergoes a change corresponding to the changes in energy of the ion beam exposure. Moreover, EO performance characteristics of IPS cells on the organic hybrid overcoat layer via ion beam irradiation were observed to have similar characteristics to the polyimide. [ABSTRACT FROM AUTHOR]

Y2Sn2O7 nanoparticle layer fabricated by ion beam (IB) irradiation after annealing is reported here. Spherical particles were induced after IB irradiation as demonstrated by field emission scanning electron microscopy. When this layer was used as an alignment layer, homogeneous alignment of nematic liquid crystals (LCs) was observed with a small pretilt angle due to van der Waals interactions between LCs and the Y2Sn2O7 layer and interactions between benzene rings of the LCs and broken chemical bonds. The resulting electric-controlled twist nematic cell showed excellent electrical-optical properties, indicating that our approach holds great potential for creating commercial LC displays (LCDs). [ABSTRACT FROM AUTHOR]

This letter introduces the characteristics of the magnesium fluoride ( \MgF2) inorganic film deposited by an electron-beam evaporation system for liquid crystal display (LCD) applications. We first achieved homogeneous liquid crystal (LC) alignment by controlling the ion-beam (IB) irradiation energy intensity. We also showed that \MgF2 is more transparent than spin-coated polyimide (PI) in the visible wavelength. By chemical analysis, IB irradiation selectively broke the Mg–F bonding structure because of the IB energy intensity; thus, the \MgF2 surface was turned to an unstable \MgF2-x surface, resulting in homogeneous LC orientation. Moreover, the electrooptic characteristics of a homogeneously aligned twisted nematic (TN)-LCD on the \MgF2 layer showed good performance as the TN-LCD on the polyimide, showing a strong possibility of the \MgF2 material as an LC alignment layer. [ABSTRACT FROM AUTHOR]

The homogeneously aligned liquid crystal display on Ta2O5 via ion beam (IB) irradiation was first embodied with controllability of pretilt angle depending on incident angle of the IB. As a result of x-ray photoelectron spectroscopic analysis, the intensity of Ta–O and O–Ta bondings as a function of incident angle behaved reversely with the pretilt angle and the lowest amplitude was observed at 45°. It revealed that the creation of pretilt angle was attributed to the irradiation of the IB by breaking Ta–O and O–Ta bonding so orientational order was generated by directional IB. Comparable electro-optical characteristics to rubbed polyimide were also achieved. [ABSTRACT FROM AUTHOR]

We demonstrate self-aligned liquid crystals (LCs) using a wrinkled-wall polydimethylsiloxane (PDMS) wrinkle structure, which is a key factor to obtain a stable homogeneous alignment state with positive LCs. We constructed the wrinkled walls via localised surface exposure to IB radiation, which passed through a long length localised pattern mask. The creation of the wrinkled wall helped to align the LC molecules homogeneously because the wrinkled wall acted as a guide for the arrangement of positive LC molecules. In addition, we confirmed the stability of the alignment state as the width of the wrinkled wall was changed. Although this wrinkled-wall method is a non-contact method, LC alignment is achieved via an anisotropic topographical guide, which provides the LC molecules with stable homogeneous alignment. [ABSTRACT FROM AUTHOR]

Abstract The characteristics of a solution-derived indium-doped zinc oxide (In:ZnO) film exposed to ion-beam (IB) irradiation as a liquid crystal (LC) alignment layer were investigated. Solution processing was conducted to deposit a thin layer on a substrate and irradiation at various IB irradiation energies was used as an LC alignment method, all of which achieved uniform and homogeneous LC alignment. Atomic force microscopy using three-dimensional imaging and numerical analyses showed that the IB irradiation reduced the surface roughness. Through the X-ray photoelectron spectroscopy, it was revealed that the modification of the chemical composition due to the IB irradiation affected the state of the LC alignment. Increased polarizability of the surface and oxygen vacancies induced strong van der Waals forces between the In:ZnO film surface and the LC molecules, thereby subsequently achieving uniform and homogeneous LC alignment. The electro-optical (EO) characteristics of a twisted-nematic cell made with IB-irradiated In:ZnO film at an IB irradiation energy of 2200 eV, with which outstanding EO performance was observed. Therefore, using the solution-derived In:ZnO film with the IB irradiation as an alignment shows remarkable potential for use in LC device. Highlights • In:ZnO film layer was deposited by using solution-process. • IB irradiation was conducted as an LC alignment method. • Physical and chemical surface modification due to the IB irradiation. • Enhanced electro-optical characteristics using the In:ZnO film with the IB irradiation. [ABSTRACT FROM AUTHOR]

We present the characteristics of annealing temperature-dependent, zinc-tin-oxide (ZTO) films deposited by a solution process for application in liquid crystal displays (LCDs). ZTO surfaces supported homogeneously-aligned liquid crystal (LC) molecules based on an ion beam irradiation system. Uniform LC alignment and a precise pretilt angle were obtained at an annealing temperature greater than 300 °C. The oxidation of ZTO films was confirmed using field-emission-scanning electron microscopy and X-ray photoelectron spectroscopy. The electro-optical characteristics of electrically controlled birefringence (ECB) cells based on the ZTO films were superior to those based on polyimide. Especially, IB-irradiated ZTO films exhibited superior performance with respect to response time. This result indicates that this approach will allow for the fabrication of advanced LCDs with high performance. [ABSTRACT FROM AUTHOR]

We demonstrate high-performance liquid crystal (LC) devices using alignment layers formed of solution-processed HfYO films that were subjected to ion-beam (IB) irradiation. IB irradiation entails the increment of the surface roughness and chemical modification of the surface. Our X-ray photoelectron spectroscopy (XPS) analysis revealed that IB irradiation also breaks oxygen bonds, and thereby creates oxygen vacancies with lattice displacement of the metal atoms. This variation stabilizes the homogeneous LC alignment. The LC cells formed using the IB-irradiated HfYO films with an intensity of 2200 eV yielded a rapid response time of 6.579 ms. Therefore, our fast switching application based on IB-irradiated HfYO films has great potential for application of display devices. [ABSTRACT FROM AUTHOR]

Abstract: This study demonstrates liquid crystal (LC) alignment on Al2O3 films using the ion-beam (IB) method as well as the optimization of the IB irradiation condition. Uniform LC alignment was achieved at an IB incident energy of 1800eV with an IB incident angle of 45°, while inferior LC alignments were observed in other tested conditions. The pretilt angles and transmittances of the LC cell were also shown as part of the same trend for the LC alignment states. This result was subject to van der Waals forces which were caused by topographical changes during the IB process. [Copyright &y& Elsevier]

• Uniform alignment of liquid crystals on the PEVA surface was achieved by ion beam irradiation. • Physicochemical characteristics of PEVA surface was investigated by AFM and XPS analysis. • Ion beam induced significant chemical modification on the surface for uniform LC alignment. • IB irradiated PEVA film is a promising alternative for stable and remarkable LC alignment layers. The post-processing of a poly(ethylene-co-vinyl acetate) (PEVA) film by ion-beam (IB) irradiation is described herein for use as a liquid crystal (LC) alignment layer. Various film curing temperatures are investigated in order to achieve a stable film prior to IB irradiation, and a uniform and homogeneous LC alignment with superior optical transparency is obtained at a curing temperature of 130 °C. The chemical and morphological effects of IB irradiation are further examined by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Although the surface morphology exhibits a random pattern, the IB irradiation is found to modify the chemical characteristics of the PEVA surface by simultaneously inducing van der Waals forces and strong dipole-dipole interactions with the LCs, thus leading to unidirectional LC alignment. In addition, LC cells are fabricated from the IB-irradiated PEVA films, and the LC alignment state is confirmed by polarized optical microscopy and pre-tilt angle measurements. Further, the high transparency of the deposited PEVA film compared to that of ITO-coated glass is demonstrated via transmittance measurement. In view of this superior performance, the IB-irradiated PEVA film is a promising alternative for advanced LC displays. [ABSTRACT FROM AUTHOR]