Ion-Beam Induced Liquid Crystal Alignment on Diamond-like Carbon and Fluorinated Diamond-like Carbon Thin Films

Abstract

Homogeneous and homeotropic orientations of nematic liquid crystal (NLC) are investigated on various inorganic thin films which are exposed to Ar ion-beam. It is the novel investigations which results in a completely dry processing technique for both the thin film deposition and alignment steps. In the case of homogenous alignment on diamond-like carbon (DLC) layer, optical band gap and the polar surface energy are investigated in order to elucidate the alignment mechanism by ion beam (IB) irradiation. We elucidate the role of surface polarity in DLC films with respect to the LC orientation. On the other hand, FDLC thin films are selected by homeotropic alignment layer with regard to the relationship between surface tension and LC orientation. Selected pretilt angles in the range of 71.1–89.8° can be easily obtained with ion beam irradiation. It is sensitively changed by thin films composition and the angle of ion beam irradiation.

The effect of phenoxymethyl side groups on the liquid crystal alignment behavior of polystyrene derivatives

“…It has been known that the high pretilt angles of LC molecules required to produce homeotropic alignment are related to the low surface energy values of the alignment layer and/ or the steric repulsions between the LC molecules and the alignment layers. 36,[49][50][51][52][53][54][55][56] Therefore, polyimides having long alkyl side groups have been widely used to align LCs perpendicular to the surface of the alignment layer, because the long alkyl groups can produce low surface energy layers due to their steric effect. 51,56 We also found that the LC alignment behavior on the polystyrene derivatives in this study could be ascribed to the surface energy values.…”

VAN LCOS Microdisplays: A Decade of Technological Evolution

“…Homogeneous alignment with a controllable pretilt angle of 0 to 10 (from horizontal) and strong anchoring is achieved. Homeotropic alignment was reported a few years later [52], using fluorinated diamond-like-carbon. Again, controllable pretilt angles from 71 to 89.8 could be produced.…”

“…The planes of the remaining rings are predominantly parallel to the direction of the ion beam and will thus induce alignment of the liquid crystal molecules [53]. For the homeotropic alignment the mechanism is less clear, although the fluorohydrocarbons are believed to contribute to the vertical alignment by means of their extremely low surface tension [52].…”

Fabrication of a dual‐gap substrate using the replica‐molding technique for transflective liquid crystal displays

“…Since the polydimethylsiloxane (PDMS) surface provides a low surface energy and hydrophobicity [7], the LC alignment induced by the PDMS surface was first examined. It is known that a surface with low hydrophobicity aligns the LC vertically [8,9]. An LC cell with two PDMS substrates was prepared as shown in the left diagram in Fig.…”