Bistable Characteristics of Liquid Crystal Devices with Patterned Alignment Films

Abstract

The photoalignment technology for the alignment of liquid crystal molecules has lately gathered much attention because its advantages over the conventional rubbing of polyimide coating and several different approaches for the realization of photoalignment have been presented. Due to its non-contact nature, a photoalignment eliminates generation of dust and electrostatic charges as well as mechanical damage to the surface. Up to now, the study of the photoalignment effect has been focused mostly on uniform substrates through linearly polarized light. With the aim to achieve such a bistable liquid crystal device by means of unpolarized UV light, we have proposed a single-step laser patterning on a photoalignment layer using a photomask to achieve an equilibrium configuration of LC molecules in contact with a periodically patterned substrate. The patterns were formed by stripes of alternating random planar and homeotropic anchoring in a sub-micron scale on the order of 0.5 micron. We proposed two possible configurations of bistable LC cells that can be obtained by combination of micro-patterned surface formed with alternating random planar alignment with either planar alignment or homeotropic alignment surfaces. In this study, we have investigated the alignment properties and switching behaviours of both proposed models.