No abstract

Solution-derived YZO films were investigated as liquid crystal (LC) alignment layers modified by ion beam (IB) irradiation. Solution processing was adopted in place of the sputtering method for the deposition of YZO films as LC alignment layers. Uniform and homogeneous LC alignment was achieved to produce a high performance LC system. X-ray photoelectron spectroscopy analysis showed that surface reformation of YZO films by annealing and IB irradiation affects the uniformity of the LC alignment. Superior electro-optical characteristics of twisted nematic LC cells constructed from IB-irradiated YZO films were observed, which indicates that the proposed solution-derived YZO films have strong potential for use in the production of advanced LC displays.

We present the alignment characteristics of liquid crystal (LC) molecules on solution-derived tin(IV) oxide (SnO 2 ) films. Solution processing was used in place of the sputtering method to deposit SnO 2 films as LC alignment layers. The LC molecules on the SnO 2 surfaces could be homogeneously and uniformly aligned by ion-beam (IB) irradiation. X-ray photoelectron spectroscopy (XPS) analysis indicated surface reformation of the SnO 2 films resulting from annealing and that IB irradiation affects the uniform LC orientation. Fast response times of twisted nematic cells constructed with IB-irradiated SnO 2 films were observed, which indicates that the proposed IB-irradiated solution-derived SnO 2 films have considerable potential for use in the production of advanced LC displays.

Generally, liquid crystal (LC) orientation on rubbed polystyrene (PS) surfaces runs in the direction orthogonal to the rubbing process. In this study, homogeneous LC orientations were produced in the direction parallel to the ion beam (IB) process on PS surfaces using various IB exposure energies. Through x-ray photoelectron spectroscopy it was shown that IB irradiation resulted in the reformation of O=C bonds resulting from surface oxidation or charge transfer, reversely tracing out the produced pretilt angles of the homogeneous LC. Moreover, thermal tests on IB-irradiated PS surfaces were carried out which showed that a relatively high IB exposure energy induced a thermally stable LC alignment property. Finally, we determined the mechanism by which homogeneous LCs are aligned on IB-irradiated PS surfaces with electro-optical properties of twisted-nematic LC cells.

We examined the properties of nematic liquid crystal (N-LC) systems with dispersed nickel oxide nanoparticles (NPs). Uniform LC alignments with regular pretilt angles were achieved on rubbed polymer surface regardless of NiO nanoparticles concentration. We confirmed the electro-optical characteristics of twisted nematic (TN) cells containing NiO nanoparticles on rubbed polymer surface, which exhibited lower threshold voltages and faster response times with less capacitance hysteresis than pure LC cells. It is clear that the response time of TN cells on rubbed polymer surfaces decreases with increasing the NiO nanoparticles concentration. These results demonstrate the relationship between NP doping concentration and trapping of impurity ions, and were confirmed by a software simulation of electric flux and field density. NiO nanoparticles in the LC cells focused the electric field flux and strengthened the electric field. Further, NiO nanoparticles in LC medium trapped charged ionic impurities and suppressed the screen effect, leading to a stronger electric field and the van der Waals interactions between LC molecules and the alignment layers.