KR20070078915A - An electron emission source comprising carbon-based material and metal carbonate particle, a method for preparing the same and an electron emission device comprising the electron emission source - Google Patents

Abstract

An electron emission source including a carbon-based material and a metal carbonate, a method for manufacturing the same, and an electron emission device including the same are provided to reduce a manufacturing cost by using metal carbonate particles. An electron emission source includes a first substrate(110), a cathode electrode(120), an electron emission source(150), a gate electrode(140), and an insulator layer(130). The cathode electrode and the electron emission source are arranged on the first substrate. The gate electrode is electrically isolated from the cathode electrode. The insulator layer is arranged between the cathode electrode and the gate electrode in order to isolate electrically the cathode electrode and the gate electrode from each other. The electron emission source includes a carbon-based material and a metal carbonate.

Description

An electron emission source comprising carbon-based material and metal carbonate particles, a method for preparing an electron emission source comprising a carbon-based material and a metal carbonate, a method for producing the electron emission source and the electron emission source the same and an electron emission device comprising the electron emission source}

1 is a perspective view schematically showing the configuration of an electron emission device and an electron emission display device according to the present invention;

2 is a cross-sectional view taken along the line II-II of FIG. 1,

3 is an SEM photograph of the electron emission source according to the present invention.

<Short description of drawing symbols>

60: spacer 70: phosphor layer

80: anode electrode 90: second substrate

100: electron emission display device

101: electron emission device

102: front panel 103: light emitting space

110: first substrate 120: cathode electrode

130: first insulator layer 131: electron emission source hole

140: gate electrode 150: electron emission source

The present invention relates to an electron emission source, a method for producing the electron emission source, and an electron emission device having the electron emission source, and more particularly, an electron emission source including a carbon-based material and metal carbonate particles, and the electron emission source. The present invention relates to a method for producing an electron emission device having the electron emission source. The electron emission source may have a precise pattern and adhesion to the substrate may be improved.

In general, an electron emission device includes a method using a hot cathode and a cold cathode as an electron emission source. Examples of electron-emitting devices using a cold cathode include field emitter array (FEA), surface conduction emitter (SCE) type, metal insulator metal (MIM) type, metal insulator semiconductor (MIS) type, and ballistic electron surface emitting (BSE) type. ) And the like are known.

The FEA type uses a principle that electrons are easily released due to electric field difference in vacuum when a material having a low work function or a high β function is used as an electron emission source. Molybdenum (Mo) and silicon A tip structure with a major material such as (Si), a carbon-based material such as graphite, DLC (Diamond Like Carbon), and a recent nano tube or nano wire, etc. Devices have been developed that use nanomaterials as electron emission sources.

The SCE type is a device in which an electron emission source is formed by providing a conductive thin film between a first electrode and a second electrode disposed to face each other on a first substrate and providing a micro crack in the conductive thin film. The device uses a principle that electrons are emitted from an electron emission source that is a micro crack by applying a voltage to the electrodes to flow a current to the surface of the conductive thin film.

The MIM type and the MIS type electron emission devices each form an electron emission source having a metal-dielectric layer-metal (MIM) and metal-dielectric layer-semiconductor (MIS) structure, and are disposed between two metals or metals with a dielectric layer interposed therebetween. When a voltage is applied between semiconductors, a device using the principle of emitting electrons is moved and accelerated from a metal or semiconductor having a high electron potential toward a metal having a low electron potential.

The BSE type uses the principle that electrons travel without scattering when the size of the semiconductor is reduced to a dimension area smaller than the average free stroke of the electrons in the semiconductor, thereby forming an electron supply layer made of a metal or a semiconductor on an ohmic electrode. And an insulator layer and a metal thin film formed on the electron supply layer to emit electrons by applying power to the ohmic electrode and the metal thin film.

Among these, the FEA type electron emission device can be classified into a top gate type and an under gate type according to the arrangement of the cathode electrode and the gate electrode. It can be divided into a pole tube, a triode or a quadrupole.

Among the electron emission devices as described above, as the electron emission material in the electron emission source, a carbon-based material, for example, carbon nanotubes may be used. The carbon nanotubes are expected to be an ideal electron emission source of an electron emission device because they have excellent conductivity and electric field concentration effect, low work function, excellent field emission characteristics, low voltage driving, and large area.

The method for producing an electron emission source containing carbon nanotubes includes, for example, a carbon nanotube growth method using a CVD method or the like, a paste method using an electron emission source formation composition containing carbon nanotubes and a vehicle. By using the above paste method, the manufacturing cost is low and the electron emission source can be formed in a large area. Compositions for forming electron emission sources, including carbon nanotubes, are described, for example, in US Pat. No. 6,436,221.

However, when the electron emission source is manufactured by the conventional paste method, satisfactory level of pattern precision and / or adhesion with the substrate cannot be obtained, and thus an improvement thereof is required.

The present invention solves the problems of the prior art as described above, in order to obtain a more precise pattern and improved adhesion to the substrate, an electron emission source containing a carbon-based material and metal carbonate particles, a method for producing the electron emission source and An object of the present invention is to provide an electron emitting device having the electron emission source.

In order to achieve the above object of the present invention, the first aspect of the present invention provides an electron emission source comprising a carbon-based material and metal carbonate particles.

In order to achieve the above object of the present invention, the second aspect of the present invention provides a composition for forming an electron emission source comprising a carbon-based material, metal carbonate particles and a vehicle, and the composition for forming an electron emission source It provides a method for producing an electron emission source comprising the step of printing on a substrate, and firing the printed composition for forming an electron emission source.

In order to achieve another object of the present invention, a third aspect of the present invention, the first substrate, the cathode electrode and the electron emission source disposed on the first substrate, and is arranged to be electrically insulated from the cathode electrode An insulator layer disposed between the gate electrode and the cathode electrode and the gate electrode, the insulator layer insulating the cathode electrode and the gate electrode, wherein the electron emission source includes an electron-emitting material and a metal carbonate particle; Provided is an element.

The electron emission source according to the present invention includes a carbon-based material and a metal carbonate, so that the patternability and adhesion to the substrate may be improved. In addition, the composition for forming an electron emission source provided to manufacture the electron emission source may include a metal carbonate, and thus may have excellent storage stability because no phase separation occurs even after being left for a predetermined time. In addition, the metal carbonate is low cost, easy to obtain, the productivity of the electron-emitting device employing it can be improved.

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

Electron emitters according to the present invention include carbonaceous materials and metal carbonate particles.

The carbon-based material has excellent conductivity and electron emission characteristics, thereby releasing electrons to the phosphor layer when the electron emission device is operated to excite the phosphor. Non-limiting examples of such carbon-based materials include carbon nanotubes, graphite, diamond, fullerenes, silicon carbide (SiC), and the like. Among these, carbon nanotubes are preferable.

Carbon nanotubes are carbon allotropes in which graphite sheets are rounded to a nano-sized diameter to form tubes. have. The carbon nanotubes of the present invention are manufactured using a CVD method 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.

On the other hand, the electron emission source according to the present invention includes metal carbonate particles. By including the metal carbonate particles, the electron emission source according to the present invention can be enhanced with adhesion to a substrate, for example, an ITO cathode electrode. In addition, when the electron emission source is formed by using the composition for forming an electron emission source including a metal carbonate, the patternability and resolution of the electron emission source may be improved. Thus, the electron emission source may have a precise pattern.

The metal carbonate particles preferably have a particle diameter of 10 nm to 500 nm, preferably 100 nm to 200 nm. When the particle size of the metal carbonate particles is less than 10nm, there may be a problem in manufacturing difficulties and cost, and when the particle size of the metal carbonate particles exceeds 500nm, the problem of poor patterning and resolution of the electron emission source Because there may be.

The metal carbonate particles may be variously used both crystalline particles and amorphous particles.

The metal carbonate particles may be one or more selected from the group consisting of calcium carbonate, sodium carbonate and potassium carbonate, but are not limited thereto.

The content of the metal carbonate particles may be 500 parts by weight to 4000 parts by weight, preferably 1000 parts by weight to 2000 parts by weight, per 100 parts by weight of the carbon-based material. When the content of the metal carbonate particles is less than 500 parts by weight per 100 parts by weight of the carbon-based material, the adhesion to the substrate may not be improved to a satisfactory level, and the content of the metal carbonate particles is 4000 per 100 parts by weight of the carbon-based material. If the weight part is exceeded, the content of the carbon-based material is relatively decreased, so that the field emission performance of the electron emission source can be reduced, and it is difficult to produce an electron emission source having a uniform shape.

In addition to the carbon-based material and the metal carbonate particles, the electron emission source may have a small amount of various organic substances that existed in the composition for forming an electron emission source, for example, xanthan such as a vehicle. This is readily recognizable to those skilled in the art who have understood the method for producing an electron emission source according to the present invention.

Such a method for producing an electron emission source of the present invention, for example, providing a composition for forming an electron emission source comprising a carbon-based material, metal carbonate particles and a vehicle; Printing the composition for forming an electron emission source; And firing the printed composition for forming an electron emission source.

First, a composition for forming an electron emission source including a carbonaceous material, metal carbonate particles, and a vehicle is prepared. Of these, the carbon-based material and the detailed description of the metal carbonate particles refer to the foregoing.

The composition for forming an electron emission source according to the present invention includes metal carbonate particles in addition to the carbon-based material and the vehicle, and thus does not cause phase separation even when left for a predetermined time. Therefore, the composition for forming an electron emission source including the metal carbonate particles is excellent in storage stability, thereby improving productivity of the electron emission source according to the present invention.

On the other hand, the vehicle contained in the electron emission source composition controls the printability and viscosity of the composition for forming an electron emission source, and serves to transport carbon-based materials and metal carbonate particles. The vehicle may include a resin component and a solvent component.

The resin component may be, for example, a cellulose resin such as ethyl cellulose, nitro cellulose or the like; Acrylic resins such as polyester acrylate, epoxy acrylate, urethane acrylate and the like; At least one of a vinyl-based resin such as polyvinyl acetate, polyvinyl butyral, polyvinyl ether, and the like may be included, but is not limited thereto. At least some of the resin components may also serve as photosensitive resins described below.

The solvent component is, for example, at least one of terpineol, butyl carbitol (BC), butyl carbitol acetate (BCA), toluene and texanol It may include. Among these, it is preferable to contain terpineol.

The content of the resin 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 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 consisting of the resin component and the solvent component is outside the above range may cause 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.

In addition, the composition for forming an electron emission source of the present invention may further include a photosensitive resin, a photoinitiator, an adhesive component, and the like, as necessary.

The photosensitive resin is a material used for patterning when forming an electron emission source. For example, an acrylate monomer, a benzophenone monomer, an acetophenone monomer, or a thioxanthone monomer may be used. More specifically, epoxy acrylate, polyester acrylate, 2,4-diethyloxanthone, or 2,2-dimethoxy-2-phenylacetophenone may be used.

The content of the photosensitive material 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 composition for forming an electron emission source according to the present invention may further include a photoinitiator. The photoinitiator serves to initiate crosslinking of the photosensitive material when the photosensitive material is exposed, and may be selected from known materials. For example, benzophenone or the like can be used.

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 crosslinking may not occur, which may cause a problem in pattern formation. This may cause a rise.

The adhesive component serves to attach the electron emission source to the substrate, and may be, for example, an inorganic binder. Non-limiting examples of such inorganic binders include frit, silane, water glass, and the like, and two or more of these may be mixed and used. The frit may be made of, for example, lead oxide-zinc oxide-boron oxide (PbO-ZnO-B ₂ O ₃ ). Among the inorganic binders, frit is preferable.

The content of the inorganic binder in the composition for forming an electron emission source may be 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 inorganic binder 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 inorganic binder exceeds 50 parts by weight, printability may decrease.

The composition for forming an electron emission source of the present invention comprising a material as described above may have a viscosity of 3,000 to 50,000 cps, preferably 5,000 to 30,000 cps. If it is out of the viscosity range, a problem may arise that the workability is poor.

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. For example, the "substrate" may be a cathode when manufacturing an electron emission device having a gate electrode provided between a cathode electrode and an anode electrode.

The printing of the composition for forming an electron emission source may use, for example, a photolithography process using a separate photoresist pattern. First, the photoresist film may be formed on the substrate, and then the composition for forming the electron emission source may be printed on the electron emission source forming region through printing, exposure, and development of the composition for forming the electron emission source, but is not limited thereto.

As described above, the composition for forming an electron emission source is subjected to a firing step. Carbon-based materials and metal carbonate particles in the composition for forming an electron emission source may improve adhesion to the substrate, at least some of the vehicles are volatilized, and other inorganic binders are melted and solidified through the sintering step, so that durability of the electron emission source may be improved. It can contribute to improvement. The firing temperature should be determined in consideration of the volatilization temperature and time of the vehicle included in the composition for electron emission source formation. Typical firing temperatures are 400 ° C 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 manufacturing cost rises, the substrate may be damaged.

The firing step may be performed in the presence of an inert gas to prevent deterioration of the carbonaceous material. The inert gas may be, for example, nitrogen gas, argon gas, neon gas, xenon gas, and a mixed gas of two or more thereof.

The calcined resultant surface is optionally subjected to an activation step for vertical alignment, surface exposure, etc. of the carbon-based material. 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 carbonaceous material may be controlled to be exposed to the electron emission surface or vertically aligned.

The electron emitter according to the present invention may be an electron emitter prepared according to the method for producing an electron emitter according to the present invention as described above.

An electron emission device according to the present invention includes a first substrate, a cathode electrode and an electron emission source disposed on the first substrate, a gate electrode arranged to be electrically insulated from the cathode electrode, the cathode electrode and the gate. The insulating layer may be disposed between the electrodes to insulate the cathode electrode from the gate electrode. In this case, the electron emission source includes a carbonaceous material and metal carbonate particles as described above. On the other hand, the electron emission source may be an electron emission source prepared according to the electron emission source manufacturing method according to the present invention as described above.

The electron emission device may further include a second insulator layer covering an upper side of the gate electrode. In addition, various modifications are possible, such that the second insulator layer may further include a focusing electrode insulated from the gate electrode and arranged in parallel with the gate electrode.

The electron emission device may be used in various electronic devices, for example, a backlight unit such as an LCD (Liquid Crystal Display), or may be used in an electron emission display device.

Among these, an electron emission display device according to the present invention includes a first substrate, a plurality of cathode electrodes disposed on the first substrate, a plurality of gate electrodes disposed to intersect the cathode electrodes, and the cathode electrode. An insulator layer disposed between the gate electrode and the gate electrode to insulate the cathode electrodes from the gate electrodes, an electron emission hole formed at an intersection point of the cathode electrode and the gate electrode, and in the electron emission source hole. And an electron emission source disposed thereon, and a second disposed substantially parallel to the first substrate. In this case, the electron emission source includes a carbon-based material substrate as described above, an anode electrode disposed on the second substrate, a phosphor layer and metal carbonate particles disposed on the anode electrode. On the other hand, the electron emission source may be an electron emission source prepared according to the electron emission source manufacturing method according to the present invention as described above. As a result, it is possible to emit additional electrons by the optoelectronic device, and thus have excellent luminance.

FIG. 1 is a partial perspective view showing a schematic configuration of a top gate type electron emission display device of the electron emission display device according to the present invention, and FIG. 2 is a cross-sectional view taken along the line II-II of FIG. have.

As shown in FIGS. 1 and 2, the electron emission display apparatus 100 is disposed side by side to form an electron emission element 101 and a front panel 102 which form a vacuum emitting space 103. A spacer 60 is provided to maintain a gap between the device 101 and the front panel 102.

The electron emission device 101 may include a first substrate 110, gate electrodes 140, cathode electrodes 120, and the gate electrodes 140 arranged to intersect on the first substrate 110. The insulating layer 130 is disposed between the cathode electrode 120 and electrically insulates the gate electrode 140 from the cathode electrode 120.

Electron emission holes 131 are formed in regions where the gate electrodes 140 and the cathode electrode 120 cross each other, and an electron emission source 150 is disposed therein.

The front panel 102 includes a second substrate 90, an anode electrode 80 disposed on a bottom surface of the second substrate 90, and a phosphor layer 70 disposed on a bottom surface of the anode electrode 80. Equipped.

Although the electron emission display device according to the present invention has been described with reference to FIGS. 1 and 2, various modifications such as an electron emission display device further including a second insulator layer and / or a focusing electrode are possible.

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, and the content of the present invention is not limited to the following examples.

EXAMPLE

Production Example

First, 10 g of terpineol, 1 g of carbon nanotube powder (manufactured by CNI), 0.2 g of glass frit (8000L, manufactured by Emerging Industries), 5 g of polyester acrylate, 5 g of benzophenone, and calcium carbonate particles (average particle size of 100 nm on average) 10g) was added and stirred to prepare a composition for forming an electron emission source having a viscosity of 30,000 cps. This is called composition 1.

compare Production Example

Among the preparation examples, except that the SiO ₂ particles were used instead of the calcium carbonate particles, a composition for forming an electron emission source was prepared in the same manner as in the preparation example. This is called Composition A.

Evaluation example  - Electronic Emission source  Evaluation of Storage Stability of Forming Composition

Immediately after preparation of Composition 1 and Composition A, these were allowed to stand for 36 hours and then observed for phase separation in the composition. As a result, composition 1 had all solids dispersed evenly on the liquid component without phase separation, but composition A had a phase separation, but composition 1 according to the present invention had no phase separation. As a result, it can be seen that the composition for forming an electron emission source according to the present invention has excellent storage stability.

Example

Composition 1 obtained from the above Production Example was applied onto a substrate prepared with a Cr gate electrode, an insulator layer and an ITO electrode, and then irradiated with a parallel exposure machine at an exposure energy of 2000 mJ / cm ² . Then, it developed using acetone and printed the composition for electron emission source formation in the electron emission source formation area. Thereafter, the mixture was calcined in the presence of a temperature of 450 ° C. and nitrogen gas to form an electron emission source. This is called sample 1.

Evaluation example  2-electronic Emission source  observe

In the sample 1, the electron emission source was observed using a SEM, and the results are shown in FIG. 3. As a result, it can be seen that the electron emission source according to the present invention has a precise pattern without being peeled off from the lower cathode electrode.

Since the electron emission source of the present invention includes metal carbonate particles in addition to the carbon-based material, adhesion to the substrate may be improved and may have a precise pattern. In addition, the electron emission source may be prepared from a composition for forming an electron emission source including a carbon-based material, a metal carbonate, and a vehicle. The composition for forming an electron emission source contains metal carbonate particles and is left for a predetermined time or more. Since phase separation does not occur even if it can have excellent storage stability, it is possible to improve the productivity of the electron emission source. In addition, the metal carbonate particles are inexpensive and easy to obtain, which can greatly reduce the production cost of the electron emission source according to the present invention.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I can understand that you can.

Claims (9)

An electron emission source comprising a carbonaceous material and metal carbonate particles. The method of claim 1, An electron emission source, characterized in that the particle diameter of the metal carbonate particles is 10nm to 500nm. The method of claim 1, And the metal carbonate particles are crystalline or amorphous. The method of claim 1, And the metal carbonate particles are at least one selected from the group consisting of calcium carbonate, sodium carbonate and potassium carbonate. The method of claim 1, The content of the metal carbonate particles is an electron emission source, characterized in that from 500 parts by weight to 4000 parts by weight per 100 parts by weight of the carbon-based material. Providing a composition for forming an electron emission source comprising a carbonaceous material, metal carbonate particles, and a vehicle; Printing the composition for forming an electron emission source on a substrate; And Baking the printed composition for forming an electron emission source; Electron emitter manufacturing method comprising a. The electron emission source according to claim 6, wherein the printing of the electron emission source forming composition is performed by applying the electron emission source forming composition to a substrate and then exposing and developing the electron emission source forming region. Manufacturing method. A first substrate; A cathode electrode and an electron emission source disposed on the first substrate; A gate electrode disposed to be electrically insulated from the cathode electrode; And An insulator layer disposed between the cathode electrode and the gate electrode to insulate the cathode electrode and the gate electrode; Wherein the electron emission source comprises a carbonaceous material and metal carbonate particles. 10. The method of claim 8, further comprising a second insulator layer covering an upper side of the gate electrode, and a focusing electrode insulated from the gate electrode by the second insulator layer and arranged in a direction parallel to the gate electrode. An electron emission element made into.

Images