Nano/microgroove zirconium‐doped lanthanum oxide film with self‐aligned molecules for liquid crystal device application

Abstract

Herein, we propose a brush‐coated zirconium‐doped lanthanum oxide (ZrLaO) film as a liquid crystal (LC) alignment layer. The film‐curing temperature was adjusted to 70, 150, and 230°C. Polarized optical microscopy and pre‐tilt angle analysis confirmed that there was uniform and homogeneous LC alignment on the 230°C cured ZrLaO film. Atomic force microscopy revealed that the surface had a nano/microgroove structure, which was caused by the shear stress generated by the brush‐coating process. This structure induced the uniform LC alignment. X‐ray photoelectron spectroscopy verified that the ZrLaO film was well‐formed on a glass substrate. The ZrLaO film displayed hydrophilic characteristics, and its surface energy increased as the film‐curing temperature increased. The ZrLaO alignment layer displayed suitable optical transmittance for LC device applications. The ZrLaO layer‐based twisted‐nematic LC cell exhibited more stable switching properties and better threshold voltage characteristics than conventional polyimide layers. Therefore, we expect that this brush‐coated ZrLaO layer will be a suitable LC alignment layer for LC device applications.