Abstract
A simple, fast, and cost-effective technique to obtain highly oriented thermotropic and lyotropic liquid crystal (LC) phases using a simple nanoscratching method is presented. Highly aligned linear nanogrooves are fabricated by scratching substrates such as normal, indium tin oxide (ITO), curved glasses, and ITO-coated polyethylene terephthalate (PET) film using diamond lapping films. To demonstrate the feasibility of the platform, typical thermotropic and lyotropic LC materials in the nematic phase are used to demonstrate the well-aligned domains along with the resulting scratched nanogrooves. The polarised optical microscopy (POM) images show excellent dark and bright states depending on the sample rotation, proving that the LC molecules are well aligned. The electro-optical performance of the twisted nematic (TN) mode LC display fabricated using the nanogrooves is also measured and indicates reliable results compared with that of the conventional device. Indeed, scratch-induced nanogrooves are well generated on the curved substrate and ITO-coated PET film to show versatility of our technique. Our platform can suggest a new nanofabrication way to make various electro-optical devices as well as other patterning applications.
Highlights
Nanofabrication techniques have been important for the current electronics
The size of the diamond particles embedded on the films is varied from 0.1 to 15 μm in diameter to determine the appropriate size for obtaining transparency and homogeneous alignment of liquid crystal (LC) (Fig. 1a)
The thermotropic and lyotropic LC materials are injected into the sandwich cell by a capillary process at the isotropic state and the nematic LC phase, respectively
Summary
Nanofabrication techniques have been important for the current electronics. Among various kinds of fabrication tools, photolithography combined with etching process has been most widely used, though this is expensive and needs many additional processes. The cheap way to make nanopatterns is demanded, and bottom approaches using block copolymer, colloidal particles, and liquid crystals (LCs) have been developed to substitute photolithography though still there are some obstacles like prerequisites to use in the practical applications[7,8,9,10,11,12,13,14,15,16,17] To solve this problem, a scratching method was proposed to make nanopatterns using an atomic force microscope (AFM) tip for scratching the given substrate, which forms various kinds of nanogrooves by controlling the load force between a contacted substrate and the AFM tip[18,19]. Our simple method suggests a new means of aligning thermotropic and lyotropic LC structures within ~5 min, which is very cost effective
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