Liquid Crystal Orientation on the Surface of Obliquely-Evaporated Silicon Monoxide with Homeotropic Surface Treatment

Abstract

We have investigated the liquid crystal molecular orientation on a surface coated by oblique evaporation of SiO followed by treatment with homeotropic surface coupling agents. This is found to be a useful technique for obtaining the liquid crystal orientation with a small pretilt from homeotropic alignment. The orientation mechanism on surfaces with and without homeotropic treatment is also investigated. The results show that the relationships among evaporation conditions, surface topography and liquid crystal orientation can be explained well by using the columnar structure model of obliquely-evaporated films proposed by Goodman-van de Waterbeemd.

Controlling the Alignment of Polyimide for Liquid Crystal Devices

“…In order to obtain a demanded pretilt angle for different LCD applications, there are many methods have been developed in the last two decades for controlling the pretilt angle of LC with a wide range, such as: obliquely-evaporated silicon monoxide (Uchida et al, 1980;Janning, 1992), polymer-stabilized alignment (Chen & Chu, 2008), hybrid mixture of two materials (Yeung et al, 2006b;Vaughn et al, 2007;Wu et al, 2008;Ahn et al, 2009), nanostructured surfaces (Komitov, 2008), chemical synthesis (Nishikawa, 2000;Tsuda, 2011), and stacked PI alignment layers ). However, the reliability, the mass production capability and ease of material synthesis for those developed techniques are questionable.…”

Ultra high-resolution FLC display for PDA

“…And the unique defects called 'Zig-Zag defect' often appear because of the incompatibility of the direction of the layer angle [3]. So we used SiO inorganic films for the alignment layer to get good alignment without defects [4,5], because it is easy to get high pretilt angle above 208 by using SiO films. Fig.…”

Fabrication of pseudo-pi vertical alignment mode liquid crystal devices with ultra-violet polymerisation and investigations of their electro-optical characteristics

“…Therefore, the development of non-contact mode LC alignment technologies has been one of the most important issues and research thrusts over the past few years. Some of the techniques employed to achieve non-contact mode LC molecules alignment include ultraviolet (UV) irradiation [10,12,22,27,29,, oblique evaporation [54][55][56][57], ion beam irradiation [22,27,[58][59][60][61], Langmuir-Blodgett (LB) film [12,62,63], selfassembled monolayers (SAMs) [50,[64][65][66][67][68][69][70], photonic crystal [71,72], plasma treatment [73][74][75] and nanoimprinting [76][77][78][79][80][81].…”