KR101251541B1 - Nanostructure patterned transparent electrode and vertically alignment liquid crystal deivce using the same - Google Patents

Abstract

PURPOSE: A transparent electrode including a nano structure pattern and a vertical-orientation type liquid crystal display device thereof are provided to supply a transparent electrode having high uniformity and various aspect ratios at a low cost and with a simple process by applying an ion bombardment. CONSTITUTION: A transparent electrode layer is formed by depositing a transparent formation substance on a substrate. A polymer layer is formed by applying a polymer substance onto the transparent electrode layer. A patterned polymer structure is formed by performing a lithographic process to the polymer layer. A polymer complex structure with the transparent formation substance is formed by etching the transparent electrode layer. The transparent electrode layer with a nano electrode pattern is formed by removing the polymer substance. A transparent electrode with a repeatedly formed nano structure is manufactured. [Reference numerals] (AA) Liquid crystal molecule; (BB) Mold(PDMS); (CC) Transparent electrode forming material(ITO); (DD) Polymer(PS); (EE) Substrate(glass);

Description

Nanostructured patterned transparent electrode and vertically aligned liquid crystal display using the same

The present invention relates to a transparent electrode having a nanostructure pattern and a vertically aligned liquid crystal display device using the same, and more particularly, to a transparent electrode using an ion bombardment phenomenon through a repeating process of secondary sputtering lithography. By forming a nanostructure pattern having high resolution and high aspcet ratio, a transparent electrode having a nanostructure pattern for uniformly vertically aligning liquid crystals without forming an alignment layer and a vertical alignment liquid crystal display device using the same It is about.

In general, liquid crystals can be classified into rod-type liquid crystals and coin-shaped discotic liquid crystals, which are classified according to their shape, and at least among three-dimensional refractive indexes of materials, nx, ny, and nz. The two or more different materials are called birefringent materials, and the direction in which the phase difference of linearly polarized light does not occur in the incident direction is defined as the optical axis. In discotic liquid crystals, the minor axis direction of the molecules becomes the optical axis.

Among these, the alignment states of the rod-shaped liquid crystals can be broadly divided into five types. First, planar alignment refers to an orientation in which the optical axis is parallel to the film plane, and second, a homeotropic orientation refers to the film in the optical axis. When perpendicular to the plane, ie, parallel to the film normal, it refers to the orientation, and third, tilted orientation refers to the orientation in which the optical axis is inclined at a certain angle between 0 ° and 90 ° with respect to the film plane. And, fourthly, the splay orientation refers to an orientation in which the optical axis continuously changes from an inclination angle of 0 ° to 90 °, or from a minimum value to a maximum value within a range of 0 ° to 90 °, and fifth, a cholesteric orientation The parallel of the optical axis to the film plane is similar to the planar orientation, but refers to an orientation in which the optical axis rotates by a constant angle clockwise or counterclockwise when viewed in the vertical direction with respect to the thickness direction.

The second vertical alignment layer may be used alone or in combination with another film, such as TN (Twist Nematic) mode, STN (Super Twist Nematic) mode, IPS (In Plane Switching) mode, VA (Vertical Alignment) mode, and OCB (Optically Compensated). It can be used as an optical film such as a retardation film, a viewing angle compensation film in a liquid crystal display (LCD) device such as a beirefringence mode, and is usually manufactured by coating a liquid crystal after coating an alignment agent to form a thin alignment film.

The alignment layer forming process is a glass substrate cleaning, alignment film printing, drying and baking process must be performed continuously, the electro-optical properties of the liquid crystal cell (cell) is largely dependent on the formation of the alignment film, In the alignment film printing process, formation of an alignment film having a constant thickness over the entire substrate is an important issue. That is, the required properties of the alignment film formed to arrange the liquid crystal molecules in a certain direction are generally capable of forming a uniform thin film of 1000 kPa or less at 200 ° C. or lower, and have excellent adhesive properties with the surface of the substrate, It should be high, there should be no reaction with the liquid crystal, the electrical characteristics should be no charge trap, and the resistivity should be high enough so that the operation of the liquid crystal cell is not affected.

If the liquid crystal having vertical alignment can be obtained by directly coating the liquid crystal layer without coating the alignment layer on the substrate, the various difficult characteristics required for the alignment layer as well as the many constraints in the manufacturing process are not considered at all. There may be a need for benefits such as simplification of the process, shortening of the process time and increased yield.

The vertically aligned liquid crystal layer to which the non-oriented film is applied is described in Korean Patent Laid-Open Publication No. 2002-0045547, wherein the liquid crystal used herein contains a monomer unit containing a liquid crystalline fragment side chain and a non-liquid crystalline fragment side chain. It is a liquid crystal polymer which has a monomeric unit. The liquid crystal polymer has a higher glass transition temperature (Tg) having a liquid crystal phase compared to the reactive liquid crystal monomer (monomer), and after drying the solvent after coating in a solution state, an additional high temperature heat treatment process in the range of 70 to 200 ℃ is necessary. The time is also in the range of 20 seconds to 30 minutes, there is a disadvantage that can be problematic to apply to a high speed continuous process.

Accordingly, the present inventors have diligently attempted to solve the problems of the prior art, forming a patterned polymer structure on a substrate on which a transparent electrode forming material is deposited, and performing a physical ion etching process on an outer circumferential surface of the patterned polymer structure. After applying the ion bombardment phenomenon to form a polymer composite to which the transparent electrode forming material is attached, the polymer is removed from the polymer composite to which the transparent electrode forming material is attached to form a transparent electrode having a nanostructure pattern formed on the substrate. When obtained, and repeatedly performing the above process, it was confirmed that the liquid crystal can be uniformly vertically aligned without forming the alignment layer, and the present invention was completed.

The main object of the present invention is to provide a transparent electrode having a nanostructure pattern capable of uniformly vertically aligning a liquid crystal without forming an alignment layer and a vertically aligned liquid crystal display device using the same.

In order to achieve the above object, the present invention comprises the steps of (a) depositing a transparent electrode forming material on the substrate to form a transparent electrode layer; (b) applying a polymer material on the transparent electrode layer to form a polymer layer; (c) performing a lithography process on the polymer layer to form a patterned polymer structure; (d) ion-etching the transparent electrode layer to form a polymer composite structure having an ion-etched transparent electrode forming material attached to an outer circumferential surface of the polymer structure; (e) removing the polymer material of the polymer composite structure to obtain a transparent electrode having a nanostructure pattern formed thereon; And (f) repeating steps (b) to (e) at least one or more times to produce a transparent electrode on which nanostructure patterns are repeatedly formed. Provided is a transparent electrode, wherein a nanostructure pattern having a thickness of 10 nm to 20 nm, a height of 20 nm to 200 nm, and an aspect ratio of 20 or less is repeatedly formed on a surface thereof.

The invention also provides an upper substrate and a lower substrate facing each other; Transparent electrodes formed on the upper substrate and the lower substrate, respectively; And a liquid crystal layer formed between the transparent electrodes, wherein the transparent electrode has a transparent electrode formed on at least one upper substrate and a lower substrate according to the present invention. .

According to the present invention, by applying the ion bombardment phenomenon through the physical ion etching can be produced a transparent electrode formed with a pre-tilt of the liquid crystal having a high aspect ratio and uniformity in a simple process and low cost, a separate process Since the process for forming the alignment layer can be omitted, cost reduction and process time shortening and product defects are reduced. In addition, by directly aligning the liquid crystal directly to the transparent electrode without the alignment layer, not only the light transmittance is high, but also the resistance value is low, thereby improving liquid crystal alignment characteristics and stability, thereby improving product performance.

1 is a schematic diagram of a method of manufacturing a transparent electrode having a nanostructure pattern according to the present invention and a liquid crystal vertical alignment mode using the same.
2 is an image of a transparent electrode having a lattice nanostructure pattern according to the present invention (a: scanning electron microscope image at 50,000 magnification, b: atomic force microscope measurement image, c: energy dispersive X-ray analyzer measurement graph, d: AFM Measurement graph).
3 is an image of a transparent electrode having a superimposed nanostructure pattern according to the present invention (a: predicted concentric nanostructure pattern, b: predicted overlapped patterned concentric nanostructure pattern, c: 10,000 times concentric nanostructure Scanning electron microscope image of pattern, scanning electron microscope image of superimposed concentric nanostructured pattern at d: 10,000 magnification, enlarged view of FIG. 6c at 80,000 magnification, enlarged view of FIG. 6d at f: 45,000 magnification.
4 is a comparison graph of electrical conductivity measurements of a transparent electrode and a general transparent electrode having a lattice nanostructure pattern according to the present invention.
5 is a light transmittance measurement comparison graph of a transparent electrode and a general transparent electrode having a lattice nanostructure pattern according to the present invention.
6 is a polarization microscope image of a vertically aligned liquid crystal cell according to the present invention (a: an image when the cell rotation angle is 0 °, a ': a conoscopy pattern image when observed using a bertrand lens when the cell rotation angle is 0 °, b: image when the cell rotation angle is 45 °, b ': conoscopy pattern image when the cell rotation angle is 45 °).

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is well known and commonly used in the art.

Throughout this specification, when a layer or member is located "on" with another layer or member, it is not only when a layer or member is in contact with another layer or member, but also between two layers or another member between the two members. Or when another member is present. Also, when an element is referred to as "comprising ", it means that it can include other elements as well, without departing from the other elements unless specifically stated otherwise.

As used herein, the terms "about", "substantially", and the like, are used at, or in close proximity to, numerical values when manufacturing and material tolerances inherent in the meanings indicated are intended to aid the understanding of the invention. It is used to help prevent unscrupulous infringers from unscrupulous disclosures where accurate or absolute figures are mentioned to help.

In one aspect, the present invention provides a method for manufacturing a transparent electrode layer, the method comprising: (a) depositing a transparent electrode forming material on a substrate to form a transparent electrode layer; (b) applying a polymer material on the transparent electrode layer to form a polymer layer; (c) performing a lithography process on the polymer layer to form a patterned polymer structure; (d) ion-etching the transparent electrode layer to form a polymer composite structure having an ion-etched transparent electrode forming material attached to an outer circumferential surface of the polymer structure; (e) removing the polymer material of the polymer composite structure to obtain a transparent electrode having a nanostructure pattern formed thereon; And (f) repeating steps (b) to (e) at least one or more times to produce a transparent electrode having a plurality of nanostructure patterns formed thereon. .

The core idea of the present invention is to form a polymer composite structure by attaching the transparent electrode forming materials of the transparent electrode layer physically shocked to the patterned polymer structure by using a secondary sputtering lithography process, and forming only the polymer in the formed polymer composite structure. After removing the transparent electrode to form a nanostructure pattern having a large aspect ratio and uniformity in large area, and then repeat this process to produce a transparent electrode with a plurality of nanostructure pattern formed.

More specifically, as shown in FIG. 1, the transparent electrode having the nanostructure pattern according to the present invention sequentially forms the transparent electrode forming material and the polymer material on the substrate to form the transparent electrode layer and the polymer layer on the substrate. (FIG. 1A). In this case, the substrate may be used as long as the material does not cause physical deformation due to the temperature and pressure of the lithography process, preferably a polymer such as silicon, metal such as gold, silver, metal such as aluminum oxide, iron oxide, or the like. Non-metal oxides such as oxides, indium tin oxides, tin oxides, and the like, quartz, glass and mixtures thereof.

The transparent electrode forming material may be used as long as it is an oxide-based material capable of forming a transparent electrode, preferably indium tin oxide (ITO), fluorinated tin oxides (FTO), or aluminum zinc It is selected from the group consisting of oxides (aluminum zinc oxides (AZO), tin oxide (SnO), zinc oxide (ZnO) and mixtures thereof, more preferably indium tin oxide (ITO) can be used.

The polymer material may be used as long as it is a polymer material that can be used for lithography, and is preferably selected from the group consisting of polystyrene, chitosan, polyvinylalcohol, polymethylmethacrylate (PMMA), and mixtures thereof.

In the present invention, a method of forming the transparent electrode layer and the polymer layer on the substrate can be used without limitation as long as it is a method capable of forming the transparent electrode layer and the polymer layer. For example, a method of forming a transparent electrode layer may include conventional chemical vapor deposition (CVD), atomic layer deposition, sputtering, laser ablation, and arc discharge. -discharge), plasma deposition, thermochemical vapor deposition, and electron beam vapor deposition, and the method of forming a polymer layer is formed by spin coating or spray coating.

As described above, the polymer layer formed on the transparent electrode layer forms a patterned polymer structure using a lithography process such as a mold for nanoimprint (FIG. 1B). In this case, since the shape of the polymer structure determines the shape of the nanostructure pattern of the transparent electrode layer, the nanostructure pattern of the various transparent electrode layers may be easily formed by controlling the shape of the polymer structure by various lithography processes.

The lithography process may be a conventional lithography process, preferably carried out by at least one method selected from the group consisting of nanoimprint, soft lithography, block copolymer lithography, optical lithography and capillary lithography.

The polymer structure patterned by the lithography process attaches the transparent electrode forming material separated from the transparent electrode layer to the outer circumferential surface by using ion bombardment through physical ion etching of the transparent electrode layer, thereby forming the transparent electrode forming material. By manufacturing the attached polymer composite structure (FIG. 1C), the transparent electrode layer, in which the polymer structure is not patterned, is accelerated to particles such as argon gas and bounced off from the transparent electrode layer through physical etching with low energy, thereby leaving transparent. A polymer composite structure to which a transparent electrode forming material is attached is prepared by using secondary sputtering lithography (SSL), in which an electrode forming material is adsorbed on a side of the polymer structure.

The ion bombardment accelerates ions such as argon ions with a voltage difference and physically impacts the transparent electrode layer, so that the impacted particles of the transparent electrode forming material are torn in the crystal direction due to the high energy impact. Refers to the phenomenon of exiting.

In the present invention, secondary sputtering lithography (SSL) for generating an ion bombardment phenomenon is performed by ion milling. The ion milling applies high energy to the light ions, and when the ion bombardment phenomenon is performed, it reduces the wide angular distribution in the crystal direction, so that the angle of escape and fall out is small so that the transparent electrode forming material particles are formed on the outer circumferential surface of the patterned polymer structure. Since it is difficult to attach, preferably, plasma is formed using a gas such as argon gas at a process pressure of 10 ⁻² mTorr to 10 ⁻⁵ mTorr, and then the plasma is accelerated to 100 eV to 5000 eV to obtain a physical ion milling process. Do this.

In the case of physical ion milling, when ion milling is accelerated to a plasma exceeding 5000 eV, the angle at which the transparent electrode forming material is separated and bounced off from the transparent electrode layer is bounced perpendicularly to the direction in which the ions are incident. When the amount of adhesion to the outer circumferential surface is small and ion milling is performed by accelerating the plasma with less than 100 eV, the etching speed of the transparent electrode layer is slow, resulting in a problem in that work efficiency is lowered.

In the present invention, the gas used for ion milling is selected from the group consisting of argon, helium, nitrogen, hydrogen, oxygen, and mixtures thereof, preferably argon. The polymer composite structure having the transparent electrode forming material attached as described above is removed only the polymer through dry or wet etching to obtain a transparent electrode layer having a nanostructure pattern (FIG. 1D). The dry or wet etching is performed by a conventional etching method capable of removing only the polymer.

The transparent electrode layer having the nanostructure pattern obtained as described above is repeatedly formed as described above to form a polymer layer on the top (FIG. 1E), and then patterned through the lithography process such as a mold for nanoimprint. Is formed (FIG. 1F). At this time, the number of repetitions of the above-described process varies depending on the shape of the nanostructure pattern, but may preferably be repeated once to 10 times.

In addition, the method of forming the polymer layer may be formed through spin coating, spray coating, or the like as described above. In addition, when using a soft lithography technique such as a mold for nanoimprint, the polymer layer is formed to sufficiently cover the nanostructure pattern so that the nanostructure pattern previously formed on the transparent electrode layer is not damaged.

 The transparent electrode layer having the nanostructure pattern having the polymer structure formed thereon is a polymer having the transparent electrode forming material attached to the outer circumferential surface of the polymer structure by using ion bombardment through the above-described secondary sputtering lithography (SSL). After forming a composite structure (FIG. 1g), only the polymer of the polymer composite structure is removed to prepare a transparent electrode in which nanostructure patterns having a high resolution / high aspect ratio are repeatedly formed (FIG. 1H). In this case, the nanostructure pattern repeatedly formed on the surface of the transparent electrode is selected from the group consisting of lattice nanostructure patterns, overlapping nanostructure patterns, continuous nanostructure patterns, and mixed nanostructure patterns thereof. The lattice nanostructure pattern is a pattern form formed by alternating nanostructure patterns, the overlapping nanostructure pattern is a pattern form that each nanostructure pattern is overlapped, the continuous nanostructure pattern is a form in which each nanostructure pattern is continuously connected It means pattern.

The method for manufacturing a transparent electrode having a nanostructure pattern repeatedly formed according to the present invention has a large aspect ratio and uniformity with a large process in a simple process and low cost by directly patterning an electrode using an ion bombardment phenomenon through physical ion etching. It is possible to manufacture a transparent electrode having a repeatedly formed nanostructure pattern, and by controlling the pattern of the polymer structure, it is easy to manufacture a variety of nanostructure patterns and at the same time a large nanoscale pattern having a pattern thickness of 15 nm or less transparent electrode It can form on a phase.

In another aspect, the present invention is characterized in that the nanostructure pattern manufactured by the above method, the thickness is 10nm-20nm, the height is 20nm-200nm, the aspect ratio 1-20 is repeatedly formed on the surface It relates to a transparent electrode. In this case, the nanostructure pattern repeatedly formed on the surface of the transparent electrode is selected from the group consisting of lattice nanostructure patterns, overlapping nanostructure patterns, continuous nanostructure patterns, and mixed nanostructure patterns thereof.

The transparent electrode repeatedly formed with the nanostructure pattern according to the present invention ion-etched a transparent electrode layer having a small thickness in the range of 15 nm to 30 nm, and has a pattern thickness of 10 nm to 20 nm, a height of 20 nm to 200 nm, and an aspect ratio of 1 Nano-structured pattern of ~ 20 can be uniformly formed on transparent electrode, not only can vertically align liquid crystal molecules without change of conductivity and transparency, but also can control the direction and shape of the pattern, which is required for future display Can actively cope with the mode.

The present invention in another aspect, the upper substrate and the lower substrate facing each other; Transparent electrodes formed on the upper substrate and the lower substrate, respectively; And a liquid crystal layer formed between the transparent electrodes, wherein the transparent electrode relates to a vertical alignment liquid crystal display device, wherein the transparent electrode according to the present invention is formed on at least one upper substrate and a lower substrate. .

In the vertical alignment liquid crystal display device according to the present invention, the upper and lower substrates provided with the transparent electrode on which the nanostructure pattern is formed are bonded in a conventional manner (FIG. 1i), and then liquid crystal is injected into a space formed of a seal material. A liquid crystal layer is formed (FIG. 1J), and a polarizing film is attached to the upper and lower substrates to manufacture a liquid crystal display device. At this time, the gap between the upper and lower substrates can be maintained as a conventional spacer. In this case, the injected liquid crystal may be used without limitation as long as the material has liquid crystallinity.

In addition, the nanostructure pattern repeatedly formed on the surface of the transparent electrode is selected from the group consisting of lattice nanostructure pattern, superimposed nanostructure pattern, continuous nanostructure pattern and mixed nanostructure pattern thereof, preferably lattice nanostructure pattern to be.

In the vertically aligned liquid crystal display irradiation of the liquid crystal, high resolution is not only directly connected to the light transmittance of the device, but also minimizes the behavior of the liquid crystal to be horizontally aligned with respect to the pattern plane by minimizing the area in contact with the liquid crystals. In addition, the high aspect ratio is a factor directly related to the binding energy for the pattern of the liquid crystals, and the higher the aspect ratio, the higher the binding energy. On the basis of this binding energy, the liquid crystals are arranged in parallel with the line pattern direction, because the minimization of elastic free energy is satisfied when parallel. Thus, in the case of the vertically alternating lattice structure, the liquid crystals have a great elastic distortion between the line structures intersected at 90 ° to each other. The method of minimizing the elastic strain energy is not arranged in parallel with the patterned line structure but in the vertical direction, so the lattice pattern alternated vertically with high resolution / high aspect ratio lines is the most ideal liquid crystal vertical. Pattern for orientation.

In the vertical alignment liquid crystal display device manufactured as described above, when an electric field is applied to the transparent electrode of the liquid crystal display device, liquid crystal molecules having a negative dielectric constant in the electric direction are vertically arranged to pass light in opposition to the application of the electric field. It operates as a liquid crystal display device in which the passage of light is switched by an electric field.

Since the liquid crystal display device according to the present invention does not have a polymer alignment film, the cell transparency is high, the response speed is high due to low driving power, and the alignment is due to physical interaction. In addition to solving the problem of falling, a pattern having a high resolution and a high aspect ratio, unlike the existing electrode pattern is formed to improve the liquid crystal alignment quality. In addition, the direction of the liquid crystal can be precisely controlled by adjusting the direction and shape of the pattern, and the conductivity is similar to that of the transparent electrode without the pattern, and thus it can be applied to a complicated mode required by the next generation display industry.

Having described specific portions of the invention in detail, those skilled in the art will appreciate that these specific embodiments are merely preferred embodiments and that the scope of the invention is not limited thereby will be. It is therefore intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Example  1: manufacturing method of transparent electrode with lattice nanostructure pattern

1-1: Manufacturing a transparent electrode with a nanostructure pattern

Indium tin oxide has a thickness of 180 nm, a sheet resistance of 10 Ω, and a substrate (Dasom RMS Inc.) having a transmittance of 96% at a wavelength of 550 nm is ultrasonically washed with IPA (isopropyl alcohol) and then dried with nitrogen gas. Impurities were removed. As such, the polystyrene (6 wt%) / toluene mixture was spin coated onto the indium tin oxide substrate from which impurities were removed, and then the toluene was evaporated to form a polystyrene layer having a thickness of 180 nm.

The formed polystyrene layer has a width and a gap of 500 nm, a linear PDMS (polydimethylsiloxane) nanoimprint mold having a 5 mm × 5 mm area, having a 500 nm line width and a 250 nm thickness, and a nano structure having a 500 nm gap. The nanostructure pattern of was formed. The polystyrene layer other than the polystyrene structure thus formed is removed through reactive ion etching injected at 40:60 with oxygen and tetrafluoromethane under a process pressure of 10 ^-2 mTorr, thereby reducing the 500 nm line width on the indium tin oxide substrate. And a polystyrene structure having a line pattern having a thickness of 150 nm and a gap of 500 nm.

The polystyrene was ion-etched by plasma 500 eV using argon gas under 10 ^-2 mTorr pressure using an ion milling system (VTS, Korea) on the indium tin oxide substrate on which the patterned polystyrene structure was formed. An indium tin oxide-polystyrene composite structure having indium tin oxide particles attached to the outer circumferential surface of the structure was formed. The indium tin oxide-polystyrene composite structure was reacted with reactive ion etching under oxygen atmosphere of 100 sccm, then placed in a dichloromethane solution and sonicated to remove polystyrene from the structure to form a first nanostructure pattern. Tin oxide substrates were prepared.

1-2: manufacturing a transparent electrode with a lattice nanostructure pattern

After the polystyrene (6 wt%) / toluene mixture was spin coated on the indium tin oxide substrate having the first nanostructure pattern of Example 1-1, toluene was evaporated to form a polystyrene layer having a thickness of 180 nm. The formed polystyrene layer has a width and an interval of 500 nm, and has a 90 ° direction with the first nanostructure pattern of Example 1-1 by using a mold for linear PDMS (polydimethylsiloxane) imprint having a 5 mm × 5 mm area. Linear polystyrene structures were formed on the substrate. The polystyrene layer other than the polystyrene layer formed above was removed by reactive ion etching injected at 40:60 with oxygen and tetrafluoromethane under a process pressure of 10 ⁻² mTorr, and then on the indium tin oxide substrate. A polystyrene structure having a 500 nm line width and a 150 nm thickness and having a 500 nm spacing was formed.

The polysylene structure was ion-etched by plasma 500 eV using argon gas under an pressure of 10 ^-2 mTorr using an ion milling system (VTS, Korea) on the indium tin oxide substrate on which the patterned polystyrene structure was formed. An indium tin oxide-polystyrene composite structure having indium tin oxide particles attached to an outer circumferential surface thereof was formed. Reactive ion etching of the indium tin oxide-polystyrene composite structure under an oxygen atmosphere of 100 sccm, followed by sonication in dichloromethane solution to remove polystyrene from the structure, resulted in 500 nm intervals, 170 nm height and 20 nm thickness. Lines having widths were fabricated on the substrate to form intersected lattice nanostructure patterns.

As a result of measuring the lattice nanostructure pattern of the prepared indium tin oxide through a scanning electron microscope, it was confirmed that the regular lattice nanostructure pattern of indium tin oxide was prepared in a large area as shown in FIG. In addition, as shown in FIG. 2C, the intervals of the orthogonal lines constituting the lattice pattern were 500 nm, which is consistent with the PDMS mold gap, and the thickness of the lattice nanostructure pattern of indium tin oxide was less than 20 nm and the height was 175 nm. It was confirmed that the lattice nanostructure pattern having the ultra high resolution and the high aspect ratio was formed on the indium tin oxide substrate.

In addition, there is a difference of about 16 nm in thickness between the portion where the polystyrene structure pattern is formed and the portion where the polystyrene structure pattern is not formed at the time of forming the indium tin oxide. It was found that there is a difference in thickness of about 16nm because it is not attached (Fig. 2b).

Meanwhile, as a result of analyzing the components of the nanostructure pattern of indium tin oxide through an energy dispersive X-ray analyzer (EDX, FEI, Sirion), indium, tin, and oxygen are included in the nanostructure pattern of indium tin oxide. It appears that no material other than the present, the nano-structure pattern is formed only by the transparent electrode forming material (Fig. 2a).

Example  2: method of manufacturing a transparent electrode having a superimposed nanopattern

Prepared in the same manner as in Example 1, using a nanoimprint mold formed in a concentric concave shape to form a patterned concentric polystyrene structure, the bottom of the patterned first polystyrene structure 10 ^-2 Under the low vacuum of mTorr, the indium tin oxide layer was exposed by over-etching with reactive ion etching injected with oxygen and tetrafluoromethane at 40:60. Ion etching was performed on the indium tin oxide layer in the same manner as in Example 1 to form a polystyrene composite structure having indium tin oxide particles attached to an outer circumferential surface thereof, and then the polystyrene was removed in the same manner as in Example 1 to have a thickness of 15 nm. A transparent electrode having a concentric nanostructure pattern having an outer ring diameter of 2 µm, an inner ring diameter of 1.4 µm, and a height of 300 nm, respectively, was obtained.

After the concentric circular nano-styled pattern was formed on the transparent electrode having the concentric nanostructure pattern thus obtained, a concentric polystyrene structure having a 45 ° direction with respect to the concentric nanostructure pattern was formed. Ion etching was performed in the same manner as to prepare a transparent electrode having a superimposed nanostructure pattern in the form of a concentric nanostructure pattern (FIG. 3).

Example  3: Cell Preparation with Transparent Electrode with Nano-structured Pattern Formed

Two transparent electrode substrates on which the nanostructure patterns formed in Example 1 or 2 were formed were prepared in VA (Vertical Alignment) mode using the upper and lower substrates, respectively. NOA63, Norland Optical Adhesive 63) was maintained using a microbead having a diameter of 2㎛ dispersed in, and then cured by exposure to ultraviolet 530nm at room temperature and atmospheric pressure. A liquid crystal (5CB; 4-cyano-4'-pentylbiphenyl) was injected into the cell thus prepared using an osmotic phenomenon to prepare a transparent electrode having a nanostructure pattern.

Comparative example  1: General transparent electrode manufacturing

The general transparent electrode has a sheet resistance of 10 Ω, and was prepared such that indium tin oxide was formed to have a thickness of 180 nm on a substrate having a transmittance of 96% at a wavelength of 550 nm.

Experimental Example  1: Conductivity Measurement of Transparent Electrode

In order to compare the conductivity between the transparent electrode substrate on which the nanostructure pattern is formed and the transparent electrode substrate on which the nanostructure pattern is not formed, the transparent electrode substrate having the lattice nanostructure pattern formed in Example 1 and the nanostructure pattern of Comparative Example 1 Gold electrodes were deposited on each of both ends of the unformed transparent electrode substrate, and the conductivity at both electrodes was measured through the probe station 4420-SCS Keithiley.

As a result, as shown in Figure 4, it can be seen that the current value for the voltage of the transparent electrode substrate (ITO pattern) of Example 1 is almost similar to the transparent electrode substrate (ITO) of Comparative Example 1, but is almost similar. . In addition, in order to measure the electrical conductivity more accurately, the electrical conductivity of the five comparative example 1 (ITO) and the transparent electrode substrate (ITO pattern) of Example 1 was measured and the electrical conductivity was calculated by the following Equation 1. The average electrical conductivity of the transparent electrode substrate of Example 1 was 91,210s / m, and the average electrical conductivity of the transparent electrode substrate (ITO pattern) of Example 1 was 87,410s / m. appear.

In addition, the sheet resistance measurement result of the transparent electrode substrate of Comparative Example 1 was measured at 8.23ohm / sq, and the transparent electrode substrate (ITO pattern) of Example 1 was measured at 9.06ohm / sq and Example 1 even after the formation of 135nm nanostructure pattern The transparent electrode substrate (ITO pattern) of only 10% showed a decrease in conductivity, it can be seen that it is possible to pattern a large-scale high-quality transparent electrode substrate without electrical damage.

Where G is the slope of the voltage-current curve, l is the distance between the two electrodes, t is the thickness, and W is the width of the electrode.

Experimental Example  2: transparent electrode Light transmittance  Measure

The transparent electrode substrate having the lattice nanostructure pattern and the transparent electrode substrate having no nanostructure pattern formed thereon and the transparent electrode substrate having the lattice nanostructure pattern formed in Example 1 to compare and measure the transparency of the transparent structure of Comparative Example 1 The light transmittance of the electrode substrate was measured using a UV / Vis / NIR spectrum (Jasco, V-570).

As a result, as shown in Figure 5, the transparent electrode substrate (ITO pattern) of Example 1 is shown to show a light transmittance of 96% in the wavelength range of 550nm the same as the transparent electrode substrate of Comparative Example 1 according to the present invention It was found that the manufacturing method can pattern a large-scale transparent electrode substrate of high quality, which is also optically intact.

Experimental Example  3: liquid crystal Orientation  Measure

The liquid crystal alignment property of the cell prepared using the transparent electrode of Example 1 was measured through a polarizing microscope (POM; Nikon, LV-100POL) equipped with a rotatable stage.

As a result, as shown in FIG. 6, the texture of the liquid crystal appeared black in the patterned region (indicated by a yellow dotted line) (FIG. 6A), and the cell was rotated in a 45 ° direction between vertically cross polarizers. Even black texture was shown to be maintained (Fig. 6b). This means that the optical axes of the liquid crystals in the patterned area coincide with the direction of light travel, ie perpendicular to the substrate, and the birefringent values are zero because the aligned liquid crystals have no retardation. As a result, the light is naturally blocked, and this state is a very high black state close to the polarizer performance itself.

In addition, the liquid crystal cell was observed through a polarizing microscope equipped with a Bertrand lens to confirm the vertical alignment mode. As a result, a black cross-shaped cross was formed from the center, and a conoscopic interference pattern composed of an interference-colored circular band appeared around the center (FIG. 6A '). This interference pattern is a pattern that appears because optical axes of light passing through the vertically aligned liquid crystals are collected by conoscopy, which means a typical interference pattern of vertically aligned liquid crystals. As a result, even when the cell was rotated at 45 ° between the vertically cross polarizers, the shape and color of the interference pattern did not change, indicating that the cell was a vertically aligned cell (FIG. 6B ′).

Meanwhile, as shown in FIG. 6, the liquid crystals were also vertically aligned even in the unstructured portion of the nanostructure (area outside the yellow dotted line). The vertical alignment even in a region without a pattern is due to the collective behavior of the liquid crystals, that is, the orientation of the liquid crystals in the patterned region can be minimized, thereby minimizing strain energy of the entire cell. These measurement results showed that the transparent electrode having the lattice nanostructure pattern according to the present invention has a strong vertical alignment induction.

Having described specific portions of the invention in detail, those skilled in the art will appreciate that these specific embodiments are merely preferred embodiments and that the scope of the invention is not limited thereby will be. It is therefore intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims (12)

A method for manufacturing a transparent electrode having a nanostructured pattern comprising the following steps:
(a) depositing a transparent electrode forming material on the substrate to form a transparent electrode layer;
(b) forming a polymer layer by applying a polymer material on the transparent electrode layer;
(c) performing a lithography process on the polymer layer to form a patterned polymer structure;
(d) ion-etching the transparent electrode layer to form a polymer composite structure having an ion-etched transparent electrode forming material attached to an outer circumferential surface of the polymer structure;
(e) removing the polymer material of the polymer composite structure to obtain a transparent electrode layer having a nanostructure pattern formed thereon; And
(f) repeating steps (b) to (e) at least once to manufacture a transparent electrode on which a nanostructure pattern is repeatedly formed.
The method of claim 1, wherein the transparent electrode forming material is indium tin oxide (ITO), fluorinated tin oxides (FTO), aluminum zinc oxides (AZO), tin oxides (SnO) ), Zinc oxide (ZnO) and a method for manufacturing a transparent electrode, characterized in that selected from the group consisting of a mixture thereof.
The method of claim 1, wherein the substrate is selected from the group consisting of quartz, glass, polymer, metal, metal oxide, nonmetal oxide, and mixtures thereof.
The method of claim 1, wherein the polymer material is selected from the group consisting of polystyrene, chitosan, polymethylmethacrylate, polyvinyl alcohol, and mixtures thereof.
The method of claim 1, wherein the lithographic process of step (c) is performed by at least one method selected from the group consisting of nanoimprint, soft lithography, photolithography, block copolymer lithography and capillary lithography. Method of manufacturing a transparent electrode.
The method of claim 1, wherein the ion etching of step (d) is performed by ion milling.
The method of claim 6, wherein the ion milling is 10 ^-2 mTorr ~ 10 ^-5 mTorr is formed by using a gas under a process pressure to form a plasma, and then the plasma is accelerated to 100eV ~ 5,000eV characterized in that the transparent Method for producing an electrode.
The method of claim 7, wherein the gas is selected from the group consisting of argon, helium, nitrogen, oxygen, and a mixed gas thereof.
The method of claim 1, wherein the removing of the polymer material in the step (e) is performed by dry etching or wet etching.
The method of claim 1, wherein the nanostructure pattern of the transparent electrode has a thickness of 10 nm to 20 nm, a height of 20 nm to 200 nm, and an aspect ratio of 1 to 20.
A nanostructure pattern manufactured by the method of any one of claims 1 to 9, having a thickness of 10 nm to 20 nm, a height of 20 nm to 200 nm, and an aspect ratio of 1 to 20 repeatedly formed on the surface thereof. Transparent electrode characterized in that.
An upper substrate and a lower substrate facing each other; Transparent electrodes formed on the upper substrate and the lower substrate, respectively; And a liquid crystal layer formed between the transparent electrodes, wherein the transparent electrode includes a transparent electrode on which the nanostructure pattern of claim 11 is repeatedly formed on at least one upper substrate and a lower substrate. Liquid crystal display device.

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