Bifunctional ITO layer with a high resolution, surface nano-pattern for alignment and switching of LCs in device applications

Abstract

We describe a novel method for liquid crystal (LC) alignment using nano-patterns of electrically conductive indium-tin oxide (ITO) layers with high resolution (cao 20 nm) and high aspect ratio (ca 10), fabricated based on the secondary sputtering phenomenon. The ITO pattern developed in this manner not only provides high anchoring energy comparable to that of rubbed polyimides, but also maintains its low resistivity as an electrode. As a result, the patterned ITO can function as an electrode and alignment layer at the same time, which facilitates successful fabrication of bifunctional conductive alignment layer for LC devices. The LC cells fabricated using patterned ITO substrates show highly stable alignment of LCs over large area and good electro-optical responses. Moreover, systematic approach made by the precise control of pattern dimensions allows us to estimate a critical anchoring energy required for an effective LC alignment based on Berreman's theory.

Planar anchoring strength and pitch measurements in achiral and chiral chromonic liquid crystals using 90-degree twist cells

“…Planar alignment of the nematic phase of chromonic liquid crystals has been achieved by polarized photo-irradiation of an azo-polymer thin film [13,14], rubbing a polymer coating [7,15], evaporating a SiO X layer [15], and fabricating a surface of closely spaced ridges as in Refs. [16,17]. The effectiveness of these techniques varies considerably from one material to another, and some involve multiple, sophisticated fabrication steps.…”

Ultrastrong Anchoring on the Periodic Atomic Grooves of Black Phosphorus

“…The birefringence color of 5CBs at 40° was bright blue, gradually turning dark at 0° and becoming bright green at −40°. These observed birefringence colors indicate that 5CB molecules closely aligned along the slow axis of the λ retarder at a 40° rotation angle because red light became linearly polarized when crossed analyzers blocked the λ retarder, resulting in bluish light . The configuration of 5CB molecules in the corresponding POM images is represented by red rods.…”

“…In order to identify the aligning direction of 5CBs on BP as the sample was rotated from −40° to 40°, a λ retarder was inserted during the POM observation. The degree of retardation is modulated to the axis of the λ retarder by the molecular orientation . The birefringence color of 5CBs at 40° was bright blue, gradually turning dark at 0° and becoming bright green at −40°.…”

“…Because phosphorus atoms are saturated, in contrast to silicon with dangling bonds and graphene with in‐plane π electrons, chemical interaction between soft matter and BP is probably low. Thus, alignment of various soft materials can mainly explain the physical anchoring energy of BP, which can be estimated through Berreman's theory . The anchoring energy ( W ) of soft matter on the grooved surface is expressed as W = 2π 3 KA 2 /λ 3 .…”

Area-Selective Atomic Layer Deposition of In2O3:H Using a μ-Plasma Printer for Local Area Activation

“…6 Furthermore, more than six steps are typically required to fabricate patterned TCOs. 6−8,16 Hence, several applications that require millimeter and submillimeter patterned TCO films would benefit from the availability of alternative patterning methods. 9−12 …”