KR20060054545A - A composition for preparing an electron emitter, the electron emitter prepared using the composition, and an electron emission device comprising the electron emitter - Google Patents

Abstract

The present invention relates to a composition for forming an electron emission source, an electron emission source manufactured using the same, and an electron emission device including the electron emission source, and more specifically, to a carbon-based material, a vehicle, and a leveling enhancer. A composition for forming an electron emission source, an electron emission source manufactured using the same, and an electron emission device including the electron emission source. According to the present invention, by improving the surface roughness of the electron emission source generated after printing drying, it is possible to reduce the difference in the surface height of the electron emission source after the exposure and development process, and consequently by the final surface treatment The generated electron emission source can be vertically oriented with a uniform height difference. The uniformly vertically aligned electron emission source has a good light emission uniformity, and has an effect of improving lifetime by applying an electric field evenly.

Description

A composition for preparing an electron emitter, the electron emitter prepared using the composition, and an electron emission device comprising the electron emitter}

1 is a view schematically showing the surface roughness of the composition for forming an electron emission source according to the prior art and the surface alignment state of the electron emission source manufactured using such a composition.

2 is a view schematically showing the surface roughness of the composition for forming an electron emission source according to the present invention and the surface alignment state of the electron emission source manufactured using such a composition.

3 is a view showing an embodiment of an electron emitting device according to the present invention.

<Short description of drawing symbols>

200: electron emission element 201: top plate

202: lower plate 110: lower substrate

120: cathode electrode 130: insulator layer

140: gate electrode 160: electron emission source

41 ... cathode 42 ... anode

The present invention relates to a composition for forming an electron emission source, an electron emission source prepared using the same, and an electron emission device including the electron emission source, and more particularly, a leveling enhancer as a component of the composition for forming an electron emission source. By containing, the composition for forming an electron emission source that can make the finally produced electron emission source have a uniform vertical orientation, an electron emission source produced using the same, and an electron emission device comprising the electron emission source will be.

An electron emission device emits electrons from an electron emission source of a cathode electrode by applying a voltage between the anode electrode and the cathode electrode to form an electric field, and impinges the electrons on a fluorescent material on the anode electrode side to emit light. It is a display device.

Carbon-based materials including carbon nanotubes (CNTs), which have excellent electronic conductivity, have excellent conductivity and field concentration effects, low work function, and excellent field emission characteristics, so that low-voltage driving is possible and large area is possible. It is expected to be an ideal electron emission source for electron emission devices.

Compositions according to the prior art include carbon nanotube powders, vehicles comprising polymers and organic solvents, inorganic binders and other additives. For example, Korean Patent Publication No. 2003-0083790 discloses carbon nanotube powders and glasses. A carbon nanotube emitter paste composition for an electron emission display device comprising a frit, an acrylate resin, ethyl cellulose, a photoinitiator and an organic solvent is disclosed.

However, in the case of the composition for forming an electron emission source according to the prior art, carbon nanotube powder is formed into a photosensitive paste composition to form an electron emission source by undergoing a process such as printing, drying, exposure development, firing, and surface treatment. The difference in the surface height of the electron emission source generated in this process causes a difference in the number and height of carbon nanotubes vertically oriented according to the surface roughness in the surface activation step using a tape or the like. It will lower the uniformity of carbon nanotubes.

In order to solve this problem, Japanese Patent Laid-Open No. 12-141056 discloses that a portion of carbon nanotubes (for example, at least 50% by volume) is aligned in substantially the same direction in order to improve emission characteristics. A carbon nanotube electron emission source is disclosed. In order to align such carbon nanotubes, the above-mentioned document adopts a method of applying either an electric field or a magnetic field during the formation of a film of carbon nanotubes on a substrate.

However, in the above method of physically aligning the carbon nanotubes by application of an electric field or a magnetic field, it is difficult to obtain a homogenizing effect over the entire carbon nanotubes on the substrate, and the application of the electric or magnetic field has to be performed separately. This has the disadvantage of becoming complicated.

 Accordingly, the present invention is to solve the problems of the prior art as described above, by including a leveling enhancer as a component of the composition for forming an electron emission source, so that the electron emission source can be easily It is an object of the present invention to provide a composition for forming an electron emission source capable of obtaining a homogenization effect, an electron emission source manufactured using the same, and an electron emission element including the electron emission source.

In order to achieve the above object, the present invention in one embodiment,

A composition for forming an electron emission source including a carbonaceous material, a vehicle, and a leveling enhancer is provided.

In another embodiment,

It provides an electron emission source prepared using the composition for forming an electron emission source.

In another embodiment,

Board;

A cathode electrode formed on the substrate; And

Provided is an electron emission device having the electron emission source formed to be electrically connected to a cathode electrode formed on the substrate.

In another embodiment,

Providing a composition for forming an electron emission source comprising a carbonaceous material, a vehicle, and a leveling enhancer;

Printing the composition for forming an electron emission source on a substrate;

Baking the printed composition for forming an electron emission source; And

It provides a method for producing an electron emission source comprising the step of activating the fired product to obtain an electron emission source.

Hereinafter, the present invention will be described in more detail.

The composition for forming an electron emission source according to the present invention includes a carbonaceous material, a vehicle, and a leveling enhancer. The composition for forming an electron emission source according to the present invention includes a leveling enhancer as a component of the composition for forming an electron emission source, whereby the finally produced electron emission source can have a uniform vertical orientation.

In the composition according to the present invention, the carbon-based material is excellent in conductivity and electron emission characteristics, and serves to excite the phosphors by emitting electrons to the fluorescent film of the anode portion during operation of the electron emission device. Non-limiting examples of such carbon-based materials include carbon nanotubes, graphite, diamond and fullerenes. Among these, carbon nanotubes are preferable.

Carbon nanotubes are carbon allotrope in which a graphite sheet is rolled into a nano-sized diameter to form a tube, and both single wall nanotubes and multi wall nanotubes can be used. . The carbon nanotubes of the present invention are manufactured using CVD methods such as thermal chemical vapor deposition (hereinafter referred to as "CVD method"), DC plasma CVD method, RF plasma CVD method, microwave plasma CVD method. It may have been.

In the composition according to the present invention, the vehicle serves to control the viscosity and printability of the composition for forming an electron emission source, which includes a polymer component and an organic solvent component.

Non-limiting examples of polymer components included in the vehicle include cellulosic resins such as ethyl cellulose, nitro cellulose, and the like; Acrylic resins such as polyester acrylate, epoxy acrylate and urethane acrylate; And vinyl resins, and non-limiting examples of organic solvent components include butyl carbitol acetate (BCA), terpineol (TP), toluene, texanol and butyl carbitol (BC).

The content of the polymer component may be 100 to 500 parts by weight, more preferably 200 to 300 parts by weight based on 100 parts by weight of the carbon-based material. On the other hand, the content of the organic solvent component may be 500 to 1500 parts by weight, preferably 800 to 1200 parts by weight based on 100 parts by weight of the carbon-based material. When the content of the vehicle is outside the above range, there may be a problem that the printability and flowability of the composition for forming an electron emission source is lowered. In particular, when the content of the vehicle exceeds the above range there is a problem that the drying time may be too long

The composition according to the invention comprises a leveling enhancer in addition to the carbonaceous material and the vehicle.

The composition according to the present invention may be prepared by mixing a carbonaceous material, a vehicle, and a leveling enhancer together, wherein the leveling enhancer in the composition lowers the surface tension at the surface of the carbon nanotubes formed after printing, thereby reducing the It will improve the leveling characteristics. As such, the electron emission source having improved leveling characteristics has good light emission uniformity, and an electric field can be applied evenly, resulting in an improved lifetime.

The leveling enhancer is preferably included in an amount of 0.1 to 20% by weight based on the total weight of the composition, which is not preferable when the weighting of the leveling enhancer is less than 0.1% by weight because there is a slight problem in improving the rebalancing, 20% by weight If it exceeds, it remains as xanthan and is not preferable because of a problem in electron emission characteristics.

In addition, the leveling enhancer is preferably at least one leveling enhancer selected from the group consisting of polysiloxanes, fluorine compounds, acrylic copolymers and polymethylsiloxanes.

The composition according to the invention may further comprise one or more additives, preferably selected from the group consisting of an adhesive component, a filler, a photosensitive resin, a photoinitiator, a viscosity improving agent, a resolution improving agent, a dispersing agent, and an antifoaming agent. .

The adhesive component serves to improve adhesion between the carbon nanotubes and the substrate, and at least one selected from the group consisting of an inorganic adhesive component, an organic adhesive component, and a low melting point metal may be used. The content of the adhesive component in the composition for forming an electron emission source is 10 to 50 parts by weight, preferably 15 to 35 parts by weight based on 100 parts by weight of the carbon-based material. When the content of the adhesive component is less than 10 parts by weight based on 100 parts by weight of the carbon-based material, satisfactory adhesive strength may not be obtained, and when the content of the adhesive component exceeds 50 parts by weight, printability may deteriorate.

The filler serves to improve the conductivity of the carbon nanotubes not sufficiently adhered to the substrate. Specific examples of the filler include, but are not limited to, Ag, Al, Pd, and the like.

The photosensitive resin is a material used for patterning an electron emission source, and specific examples of the photosensitive resin include, but are not limited to, a thermally decomposable acrylate monomer, a benzophenone monomer, an acetphenone monomer, or a thiocylic acid. Ton monomers, and more specifically, epoxy acrylate, polyester acrylate, 2,4-diethyloxanthone, or 2,2-dimethoxy-2-phenylacetophenone can be used. Can be. The content of the photosensitive resin may be 300 to 1000 parts by weight, preferably 500 to 800 parts by weight based on 100 parts by weight of the carbon-based material. When the content of the photosensitive resin is less than 300 parts by weight based on 100 parts by weight of the carbon-based material, the exposure sensitivity is inferior, and when the content exceeds 1000 parts by weight based on 100 parts by weight of the carbon-based material, development is not preferable.

The photoinitiator serves to initiate crosslinking of the photosensitive resin when the photosensitive resin is exposed. Non-limiting examples of such photoinitiators include benzopinone and the like. The content of the photoinitiator may be 300 to 1000 parts by weight, preferably 500 to 800 parts by weight based on 100 parts by weight of the carbon-based material. When the content of the photoinitiator is less than 300 parts by weight based on 100 parts by weight of the carbon-based material, efficient exposure may not occur, which may cause a problem in pattern formation. This is undesirable because it can be.

In addition, the composition according to the present invention may further include a viscosity improver, a resolution improver, a dispersant, an antifoaming agent, and the like, which are commonly used as necessary.

The present invention also provides an electron emission source manufactured using the composition for forming an electron emission source.

The method for producing an electron emission source included in the electron emission device of the present invention using the composition for forming an electron emission source as described above provides a composition for electron emission source formation comprising a carbon-based material, a vehicle, and a leveling enhancer. Doing; Printing the composition for forming an electron emission source on a substrate; Baking the printed composition for forming an electron emission source; And activating the fired product to obtain an electron emission source.

First, a composition for forming an electron emission source is provided by mixing a carbonaceous material, a vehicle, and a leveling enhancer as described above. The viscosity of the composition for forming an electron emission source finally formed before printing may be 3,000 to 50,000 cps, preferably 5,000 to 30,000 cps.

Thereafter, the provided composition for forming an electron emission source is printed on a substrate. The "substrate" is a substrate on which an electron emission source is to be formed, which may be different depending on the electron emission element to be formed, which is easily recognized by those skilled in the art.

The printing method is different depending on the case where the composition for electron emission source formation contains the photosensitive resin and when the photosensitive resin is not included. When the composition for electron emission source formation contains photosensitive resin, a separate photoresist pattern is unnecessary. That is, a composition for forming an electron emission source containing a photosensitive resin is coated on a substrate by printing, and the film is exposed and developed according to a desired electron emission source forming region.

On the other hand, when the composition for electron emission source formation does not contain photosensitive resin, the photolithography process using a separate photoresist film pattern is required. That is, a photoresist film pattern is first formed using a photoresist film, and then the composition for forming an electron emission source is supplied by printing using the photoresist film pattern.

According to the method of the present invention, the difference between the maximum height and the minimum height on the surface of the composition after the printing step may be 0.1 μm or less. According to the prior art, the difference between the maximum height and the minimum height on the surface of the composition after the printing step is on the order of 2 to 1 μm, which is significantly higher than the 0.5 μm of the present invention. It is judged to be the result caused because it further comprises a leveling additive.

As described above, the composition for forming an electron emission source may have improved adhesion between the carbon-based material and the substrate through a sintering step, and durability may be improved by melting and solidifying at least one adhesive component, and outgassing. Outgasing can also be minimized. The firing temperature should be determined in consideration of the volatilization of the vehicle and the sinterable temperature and time of the adhesive component included in the composition for electron emission source formation. Typical firing temperatures are 400 to 500 ° C, preferably 450 ° C. If the firing temperature is less than 400 ℃ may cause a problem that the volatilization such as a vehicle is not sufficiently made, if the firing temperature exceeds 500 ℃ may cause a problem that the carbon-based material may be damaged.

According to the method of the present invention, the difference between the maximum height and the minimum height on the surface of the composition after the firing step may be 1 μm or less. The reason why the surface after the firing step is somewhat rougher than the surface after the printing step is that the polymer organic material is calcined and blown away, and solids are mainly left. According to the prior art, the difference between the maximum height and the minimum height on the surface of the composition after the calcination step is on the order of 5 to 3 μm, which is significantly higher than the 1 μm of the present invention, and this difference indicates that the composition according to the present invention has a surface uniformity. It is judged to be the result caused because it further comprises a leveling additive.

The carbon-based material on the surface of the fired product thus fired is subjected to an activation step. According to one embodiment of the activation step, after applying a solution that can be cured in the form of a film through a heat treatment process, for example, an electron emission source surface treatment agent containing a polyimide-based polymer on the firing result, and then heat treatment Then, the film formed by the heat treatment is peeled off. According to another embodiment of the activation step, the activation process may be performed by forming an adhesive part having an adhesive force on the surface of the roller driven by a predetermined driving source and pressing the surface of the firing product at a predetermined pressure. Through this activation step, the carbon-based material may be exposed to the electron emission surface or the vertical alignment may be controlled.

According to the method of the present invention, the difference between the maximum height and the minimum height on the surface of the composition after the activation step may be 1.5 μm or less. The reason why the surface after the activation step is somewhat rougher than the surface after the firing step is that the carbon nanotubes are vertically oriented as the surface of the carbon nanotube film is further peeled off, whereby uneven activation occurs. According to the prior art, the difference between the maximum height and the minimum height on the surface of the composition after the activation step is on the order of 6 to 3 μm, which is significantly higher than the 1.5 μm of the present invention. It is judged to be the result caused because it further comprises a leveling additive.

1 and 2, the surface roughness of the composition for forming an electron emission source according to the prior art and the surface orientation state of the electron emission source prepared using such a composition (Fig. 1), and the composition for forming an electron emission source according to the present invention. The surface roughness of and the surface orientation state (FIG. 2) of the electron emission source produced using this composition are schematically illustrated.

1 and 2, in the case of the composition according to the prior art has a rougher surface than the composition according to the invention from the surface treatment step, and consequently the final carbon nanotubes when the surface treatment step The arrangement of also becomes nonuniform and irregular, but in the case of the composition according to the present invention, since the surface roughness of the composition after print drying before the surface treatment step is low, carbon having a more uniform site density even after the final surface treatment It is possible to provide an array of nanotubes.

In another embodiment, the present invention, a substrate; A cathode electrode formed on the substrate; And the electron emission source formed to be electrically connected to the cathode electrode formed on the substrate.

3 is a partial cross-sectional view of an electron emission device according to the present invention, and typically shows an electron emission device having a triode structure.

As shown, the electron emission device 200 includes an upper plate 201 and a lower plate 202, and the upper plate is an upper electrode 190 and an anode electrode 180 disposed on the lower surface 190a of the upper substrate. And a phosphor layer 170 disposed on the bottom surface 180a of the anode electrode.

The lower plate 202 has a lower surface substrate 110 disposed in parallel with the upper substrate 190 at predetermined intervals to have an inner space, and a cathode electrode disposed in a stripe shape on the lower substrate 110 ( 120, a gate electrode 140 arranged in a stripe shape to intersect the cathode electrode 120, an insulator layer 130 disposed between the gate electrode 140 and the cathode electrode 120, and the insulator layer ( 130 and an electron emission source hole 169 formed in a portion of the gate electrode 140 and the electron emission source hole 169 are disposed in the electrical source to the cathode electrode 120 and lower than the gate electrode 140 It is provided with an electron emission source 160 disposed.

The upper plate 201 and the lower plate 202 are maintained in a vacuum at a pressure lower than atmospheric pressure, and the spacer 192 supports the pressure between the upper plate and the lower plate generated by the vacuum and partitions the light emitting space 210. It is disposed between the upper plate and the lower plate.

The anode electrode 180 applies a high voltage necessary for accelerating the electrons emitted from the electron emission source 160 to allow the electrons to collide with the phosphor layer 170 at high speed. The phosphor layer is excited by the electrons and emits visible light while falling from a high energy level to a low energy level. In the case of the color electron emission device, phosphor layers of red light emission, green light emission, and blue light emission are disposed on the lower surface 180a of the anode in each of the light emitting spaces 210 constituting the unit pixel.

The gate electrode 140 serves to facilitate the emission of electrons from the electron emission source 160, and the insulator layer 130 partitions the electron emission source hole 169 and the electrons. It serves to insulate the emission source 160 and the gate electrode 140.

Hereinafter, preferred examples and comparative examples of the present invention are described. The following examples are only described for the purpose of more clearly expressing the present invention, but the contents of the present invention are not limited to the following examples.

Example

To 10 g of terpineol, 1 g of carbon nanotube powder (ILJIN Nanotech Co., Ltd.), frit (Emerging Co., Ltd.), 0.2 g of acrylic resin (Elvacite), 5 g of polyester acrylate, and 5 g of benzopinone were added and stirred, followed by stirring as a leveling enhancer. 1 g of Polyisocyanate (EFKA) was further added and mixed to prepare a composition for an electron emission source having a viscosity of 30,000 cps. The composition for forming an electron emission source is printed on an electron emission source formation region on a substrate provided with a Cr gate electrode, an insulating film, and an ITO electrode, and then using a parallel mask with an exposure energy of 2000 mJ / cm ² using a pattern mask. Was investigated. After exposure, the solution was developed by spraying and firing at a temperature of 450 ° C. to form an electron emission source. The final electron emission source was completed by placing the roller surface having the adhesive portion on the formed electron emission source, pressing and peeling off, and performing an activation process. Thereafter, the substrate employing the ITO as the fluorescent film and the anode electrode is arranged so as to be oriented with the substrate on which the electron emission source is formed, and a spacer for maintaining the cell gap between the substrates is formed between both substrates, thereby providing the electron emission device according to the present invention. Was prepared.

Comparative example

An electron-emitting device was manufactured according to the ingredients and contents described in the preparation method of Example 1, except that no leveling enhancer was used.

Evaluation example

The difference between the maximum height and the minimum height of the surface of the composition was measured using an alpha step for each manufacturing step of the electron emission device according to the Examples and Comparative Examples, and the results are shown in Table 1 below.

Example Comparative example Height difference after printing 0.5 3 Height difference after firing One 5 Height difference after activation 1.5 6

(Unit: μm)

As can be seen from the results of Table 1, the composition according to the present invention has a difference between the maximum surface height and the minimum height of the surface at each stage of printing, firing, and activation, which is significantly smaller than the prior art, and consequently the surface uniformity. The performance is markedly improved over the prior art.

According to the present invention, by improving the surface roughness of the electron emission source generated after printing drying, it is possible to reduce the difference in the surface height of the electron emission source after the exposure and development process, and consequently by the final surface treatment The generated electron emission source can be vertically oriented with a uniform height difference. The uniformly vertically aligned electron emission source has a good light emission uniformity, and has an effect of improving lifetime by applying an electric field evenly.

Claims (12)

A composition for forming an electron emission source comprising a carbonaceous material, a vehicle, and a leveling enhancer. The composition of claim 1, wherein the leveling enhancer is included in an amount of 0.1 to 20 wt% based on the total weight of the composition. The composition of claim 1, wherein the leveling enhancer is at least one leveling enhancer selected from the group consisting of polysiloxanes, fluorine compounds, acrylic copolymers, and polymethylsiloxanes. The method of claim 1, wherein the composition further comprises at least one additive selected from the group consisting of an adhesive component, a filler, a photosensitive resin, a photoinitiator, a viscosity improving agent, a resolution improving agent, a dispersing agent, and an antifoaming agent. Composition for forming an electron emission source. An electron emission source manufactured using the composition for electron emission source formation according to any one of claims 1 to 4. Board; A cathode electrode formed on the substrate; And An electron emission device, comprising an electron emission source according to claim 5, formed to be electrically connected to a cathode electrode formed on the substrate. Providing a composition for forming an electron emission source comprising a carbonaceous material, a vehicle, and a leveling enhancer; Printing the composition for forming an electron emission source on a substrate; Baking the printed composition for forming an electron emission source; And Activating the fired product to obtain an electron emission source. The method of claim 7, wherein the leveling enhancer is included in an amount of 0.1 to 20 wt% based on the total weight of the composition. 8. The method of claim 7, wherein the leveling enhancer is at least one leveling enhancer selected from the group consisting of polysiloxanes, fluorine compounds, acrylic copolymers, and polymethylsiloxanes. The method of claim 7, wherein a difference between the maximum height and the minimum height on the surface of the composition after the printing step is 0.5 μm or less. 8. The method of claim 7, wherein a difference between the maximum height and the minimum height on the surface of the composition after the firing step is 1 µm or less. 8. The method of claim 7, wherein the difference between the maximum height and the minimum height on the surface of the composition after the activation step is 1.5 μm or less.

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