KR100701093B1 - Apparatus for orientating carbon nanotube, method of orientating carbon nanotube and method of fabricating field emission display - Google Patents

Abstract

The present invention relates to an orientation method of carbon nanotubes and a method of manufacturing a field emission display device including the same. Also disclosed is an orientation device for carbon nanotubes. The alignment device for carbon nanotubes according to the present invention includes at least two electrodes having opposite polarities formed on an insulating substrate and an insulating layer covering the electrodes. The carbon nanotubes disposed adjacent to the electrodes are oriented by the electric field formed by the electrodes. According to the present invention, the carbon nanotubes can be oriented in a predetermined direction, which can cause high luminance and uniform light emission, and can be used for a long time.

Carbon Nanotubes, Field Emission Display, Orientation Device

Description

Carbon nanotube alignment device, carbon nanotube orientation method, and field emission display device manufacturing method {APPARATUS FOR ORIENTATING CARBON NANOTUBE

1 schematically shows an orientation device for carbon nanotubes,

2 is a view for explaining the alignment method of carbon nanotubes,

3A and 3B are cross-sectional views illustrating a method of manufacturing a field emission display device.

♧ explanation of the reference numerals for the main parts of the drawing.

10: alignment device 12: insulating substrate of the alignment device

15a: anode electrode of alignment device 15c: cathode electrode of alignment device

18: insulation layer

20: substrate of the field emission display device

25c: cathode of field emission display device

25g: gate electrode of field emission display

30 emitter 30p

EF: electric field

The present invention relates to a display device, and more particularly, to a method of manufacturing a field emission display device.

Typical applications of the display device, which is an important part of the conventional information transmission medium, include a personal computer monitor and a television receiver. Such display devices include cathode ray tubes (CRTs) using high-speed hot electron emission, liquid crystal displays (LCDs), plasma display panels (PDPs), and electric fields that are rapidly developing in recent years. The display panel may be broadly classified into a flat panel display such as a field emission display (FED).

Among them, the field emission display device is attracting attention as a next-generation flat panel display device for overcoming the disadvantages of other flat panel display devices. The field emission display device has a simple electrode structure, high-speed operation on the same principle as a CRT, and is excellent in terms of power consumption, efficiency, brightness, and the like.

The field emission display device emits electrons from the emitter by applying a strong electric field to the emitters arranged at regular intervals on the cathode electrode, and impinges the electrons on the phosphor coated on the surface of the anode to emit light. In other words, when a strong electric field is applied to the emitter in the vacuum, electrons are taken out of the vacuum from the emitter using quantum mechanical tunneling. In this case, the field emission display device exhibits current-voltage characteristics according to a Fowler-Nordheim law.

Early emitters of field emission displays were mainly made of molybdenum (Mo) as a spint type metal tip (or micro tip). However, in the field emission display device having an emitter in the form of a metal tip, an extremely fine hole for disposing an emitter should be formed, and a uniform metal micro tip should be formed in the entire area of the screen by depositing molybdenum. The process is complex and requires advanced technology. In addition, there is a problem in that the manufacturing cost of the product rises because expensive equipment must be used. Therefore, it is pointed out that the field emission display device having the emitter in the shape of a metal tip has a limitation in large screen. As a result, high-quality electron emission can be obtained even under low voltage driving conditions, and a technology for simplifying the manufacturing process by forming the emitter in a flat shape has been researched and developed. In recent years, carbon nanotubes are mechanically strong and chemically stable, and have excellent electron emission characteristics at relatively low vacuums. Therefore, the importance of field emission displays using the same has been recognized.

Carbon nanotube emitters can be prepared by printing pastes consisting of metals, organic polymers and nanotubes, and then protruding nanotubes through etching, and dispersing nanotubes in organic solvents on organic plates. And a method of forming an emitter by electrophoresis by dispersing the nanotube film to form a nanotube film, and dispersing the nanotube in a solvent together with the charged material. However, nanotube emitters prepared in this way are not uniform in the distribution of nanotubes effective for electron emission, and in particular, since the nanotubes on the electrode substrate are not vertically arranged to easily cause electron emission, uniformity of high brightness is achieved. It can't cause a glow. In addition, there is a disadvantage that can not be used for a long time.

SUMMARY OF THE INVENTION The present invention has been proposed in consideration of the above-mentioned situation, and a technical problem to be achieved by the present invention is a method of orienting carbon nanotubes to cause uniform luminance of high brightness and a method of manufacturing a field emission display device including the same. To provide.

Another object of the present invention is to provide an alignment device for carbon nanotubes capable of orientating carbon nanotubes in a predetermined direction.

According to one aspect of the present invention, an alignment device for carbon nanotubes includes at least two electrodes having opposite polarities formed on an insulating substrate, and an insulating layer covering the electrodes. The carbon nanotubes disposed adjacent to the electrodes are oriented by the electric field formed by the electrodes.

The pair of electrodes may be stripe-like in size.

According to another aspect of the present invention for achieving the above technical problem, the alignment method of the carbon nanotubes uses the alignment device of the carbon nanotubes. The method includes placing the substrate on which the carbon nanotubes are disposed in proximity to the alignment device and applying an electric voltage to an electrode of the alignment device to form an electric field.

The current used to apply the voltage may be alternating current or pulsed direct current.

The strength of the electric field may be 0.1 ~ 10V / ㎛.

According to another aspect of the present invention, there is provided a method of manufacturing a field emission display device, wherein carbon nanotubes are disposed on an insulating substrate on which a cathode electrode and a gate electrode are formed, and the carbon nanotubes are exposed to an electric field. To orientate the carbon nanotubes.

Placing the carbon nanotubes is performed by screen printing a paste comprising the carbon nanotubes on the cathode electrode and the gate electrode, or by printing a paste comprising the carbon nanotubes on the substrate and then patterning the paste. It can be done by doing.

The electric field may be formed by the electric field applying apparatus of claim 1.

The strength of the electric field may be 0.1 ~ 10V / ㎛.

According to the present invention, the carbon nanotubes can be oriented in a predetermined direction, thereby generating uniform luminance of high brightness.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed subject matter is thorough and complete, and that the spirit of the present invention to those skilled in the art will fully convey.

In the drawings, the thickness of a layer (film) or regions may be exaggerated for clarity. Also, if it is mentioned that a layer (film) is on or above another layer (film) or it can be formed directly on another layer (film) or substrate or between them a third layer (film) ) May be intervened.

The same reference numerals throughout the specification represent the same components.

1 is a view schematically showing an alignment device of carbon nanotubes.

Referring to FIG. 1, the alignment device 10 of carbon nanotubes includes an insulating substrate 12, electrodes 15a and 15c for forming an electric field, and an insulating layer 18. Electrodes 15a and 15c with opposite polarities are positioned on the insulating substrate 12. Although not shown, the electrodes 15a and 15c may be striped. The electrodes 15a and 15c having opposite polarities are composed of an anode electrode 15a and a cathode electrode 15c, and the anode electrodes 15a and the cathode electrodes 15c are alternately arranged one by one at a predetermined interval. The anode electrode 15a and the cathode electrode 15c may have the same thickness and width. In addition, the anode electrode 15a and the cathode electrode 15c in the alignment device of the carbon nanotubes should be distinguished from the anode electrode and the cathode electrode in the field emission display device described later.

An insulating layer 18 may be disposed on the substrate 12 to cover the electrodes 15a and 15c. If voltage is applied to the anode electrode 15a without the insulating layer 18, the electric field EF is formed at the shortest distance between the anode electrode 15a and the cathode electrode 15c, but if the insulating layer 18 is applied, the electric field ( EF is formed by drawing a parabola between the anode electrode 15a and the cathode electrode 15c.

2 is a view for explaining the alignment method of carbon nanotubes.

Referring to FIG. 2, when the paste 30p including the carbon nanotubes is placed close to the electric field EF formed by the alignment device of FIG. 1, the carbon nanotubes in the paste 30p move in the direction of the electric field EF. Oriented. At this time, if the arrangement of the electrodes 15a and 15c of the alignment device 10 and the applied voltage and the position of the emitter substrate 20 of the field emission display device are appropriately adjusted, not only in the vertical direction but also in any desired direction Carbon nanotubes can also be oriented.

The power source used for voltage application may be any of AC, DC, and pulsed DC, but AC or pulsed DC is preferable from the viewpoint of impact effect when the carbon nanotubes are aligned. The strength of the electric field (EF) required for the orientation of the carbon nanotubes is suitably 0.1 to 10 V / µm.

In one embodiment of the present invention, the paste 30p including carbon nanotubes is formed on both the gate electrode 25g and the cathode electrode 25c of the emitter substrate 20, but may be in any form. The paste 30p may be formed only on the cathode electrode 25c. In addition to the lateral gate method in which the gate electrode 25g is located on the side of the cathode electrode 25c, the under gate method or the gate electrode 25g in which the gate electrode 25g is positioned below the cathode electrode 25c. The orientation method according to the present invention can also be applied to a grid-type gate method or the like, which is formed in a hole formed between the cathode electrode 25c and the anode electrode (not shown).

3A and 3C illustrate a method of manufacturing a field emission display device.

Referring to FIG. 3A, a cathode electrode 25c and a gate electrode 25g are formed on the emitter substrate 20. In the lateral gate type field emission display device in which the gate electrode 25g is positioned on the side of the cathode electrode 25c as in an exemplary embodiment of the present invention, the cathode electrode 25c and the gate electrode 25g are photographed and etched once. Are formed simultaneously. The cathode electrode 25c and the gate electrode 25g are stripe-shaped with the same size and are formed so as to be alternated one by one. However, in the present invention, the field emission display device may not be a lateral gate method.

 The emitter substrate 20 may be glass, alumina, quartz, silicon, or the like. However, in consideration of the process and the large area of the field emission display device, it is preferable to use a glass substrate. The cathode electrode 25c and the gate electrode 25g may be made of any one selected from the group consisting of Ag, Cr, Al, Ni, Co, Pt, Au, Ti, W, Zn, ITO, and alloys thereof.

Referring to FIG. 3B, a paste 30p including carbon natotubes is screen printed on the cathode electrode 25c and the gate electrode 25g. At this time, the paste 30p is formed in a stripe like the cathode electrode 25c and the gate electrode 25g. Of course, it may be formed in a shape other than stripe. In addition, the present invention is not limited to the formation method and the formation position of the carbon natotube paste 30p.

The paste 30p is oxidized carbon nanotubes in an acid solution mixed with nitric acid and sulfuric acid for at least 8 hours, and the diameter (d) is 1-30 nm, the length (L) is 1-10 μm, and the ratio of length and diameter (L / d ) 500 to 10000, and then prepared by mixing with 10% by weight solution of ethyl cellulose (ethylcellulose) in terpineol (terpineol).

Referring again to FIGS. 3B and 2, the emitter substrate 20 on which the carbon nanotube paste 30p is formed is disposed in proximity to the alignment device 10. The carbon nanotubes in the paste 30p are oriented in the vertical direction by the electric field EF formed by the electrodes 15a and 15c of the alignment device. As described above, it may be oriented in a direction other than the vertical direction.

Referring to FIG. 3C, when the paste 30p is dried, the emitter 30 is formed by oriented carbon nanotubes. An anode substrate 40 is disposed on the emitter substrate 20. An anode electrode 45 having the phosphor 50 coated thereon is positioned on the anode substrate 40.

Hereinafter, the results of experimenting with the emission characteristics of the emitter prepared according to the present invention are described. Referring again to FIG. 3C, the emitter 30 has a line width of 100 μm, a thickness of 10 μm, and is vertically oriented for about 3 minutes by an electric field having a size of 2 V / μm. After the anode substrate 40 is disposed on the emitter substrate 20 at a distance of 5 mm, a 250 V bidirectional pulse DC voltage is applied to the gate electrode 25 g, and a 6 kV DC voltage is applied to the anode electrode 45. As a result, electron emission characteristics such as brightness of 12000 cd / m 2 and color temperature of 11500K were shown to be improved by the electric field treatment.

On the other hand, in the detailed description of the present invention has been described with respect to specific embodiments, various modifications are of course possible without departing from the scope of the invention.

Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be defined not only by the claims below but also by the equivalents of the claims of the present invention.

According to the present invention described above, the carbon nanotubes can be oriented in a predetermined direction to cause uniform luminance of high brightness, and can be used for a long time.

Claims (10)

At least two electrodes with opposite polarities formed on the insulating substrate; And Including an insulating layer covering the electrodes, Orienting the carbon nanotubes disposed adjacent to the electrodes by an electric field formed by the electrodes. The method of claim 1, And the electrodes are stripe-shaped carbon nanotube alignment devices of the same size. In the method of orienting carbon nanotubes using the alignment device of claim 1, Placing the substrate on which the carbon nanotubes are placed in proximity to the alignment device, Forming an electric field by applying a voltage to an electrode of the alignment device to form an electric field. The method of claim 3, wherein And the current used to apply the voltage is alternating current or pulsed direct current. The method of claim 3, wherein The strength of the electric field is 0.1 ~ 10V / ㎛ method of orientation of carbon nanotubes. Forming a cathode electrode and a gate electrode on the insulating substrate, Disposing a carbon nanotube on at least one of the cathode electrode and the gate electrode; By using the carbon nanotube alignment device of claim 1 to form an electric field, And aligning the carbon nanotubes by bringing the carbon nanotubes and the electric field closer to each other. The method of claim 6, Disposing the carbon nanotubes by screen printing a paste including the carbon nanotubes on the cathode electrode and the gate electrode. The method of claim 6, And disposing the carbon nanotubes by printing a paste including the carbon nanotubes on the substrate and then patterning the paste. delete The method of claim 6, The intensity of the electric field is 0.1 ~ 10V / ㎛ manufacturing method of the field emission display device.

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