Variable liquid crystal pretilt angles on various compositions of alignment layers

Abstract

The authors introduce variable liquid crystal (LC) pretilt angles via ion beam (IB) irradiation of silicon carbide (SiC) layers of various compositions. To control the composition of the SiC layer, the authors altered the rf power ratio between the graphite target and silicon target. The pretilt angle of the silicon-rich SiC layer was constant regardless of IB irradiation angle; however, the carbon-rich SiC layer showed variable pretilt angles, depending on IB irradiation angle. The authors attribute variable pretilt angle to the competition between van der Waals interactions, favoring the vertical alignment, and pi-pi interactions, favoring the LC alignment parallel to IB direction.

2-Face Viewable Liquid Crystal Display by In-Plane Switching

“…To generate a mid-pretilt angle, several techniques can be employed, for example, the ion-beam exposure [4], mixing of planar and vertical polyimides [10], or stacked alignment layers [11]. Specifically, a special care should be paid to the selection of LC's pretilt angle h pretilt , since it ultimately determines the optimal observation direction h optimal for each viewing cone.…”

“…Motivated from the above issues, we propose a method for easily obtaining a 2-face viewable liquid crystal display (LCD) that is able to show different images on the same screen depending on the viewing perspectives. It can be seen that a unit LC region is divided into two subpixels by means of a 2-domain alignment technique, such as ion-beam exposure [4] and ultra-violet irradiation [5]. When no voltage is applied, i.e., the turn-off state, LC directors are initially mid-tilted at a certain angle and oriented towards opposite ways.…”

The Directional Peeling Effect of Nanostructured Rigiflex Molds on Liquid‐Crystal Devices: Liquid‐Crystal Alignment and Optical Properties

“…[28][29][30] They include patterning techniques, such as polymer transfer printing, nanoimprinting with a rigiflex mold, and soft molding, and LC alignment mechanisms on an inorganic layer, for example, silicon carbide and diamond-like carbon. Among them, nanoimprinting with a rigiflex mold makes it possible to peel the mold off with directionality (directional peeling), which can induce orientation of the free end chain of the alignment layer because the directional peeling of the flat film affects the orientation of the free end chain of the polymer.…”

Control of the molecular pretilt angle in liquid crystal devices by using a low-density localized polymer network

“…Continuous control of a from 5°to 89°was achieved in [6] by depositing vertical-alignment PI layers of various thickness on a planar PI. Wide-range control of a was also achieved in [7] by using island metallic films, ion-beam treated a-C:F films [8] and SiC films [9] for LC alignment.…”