CN101009187A - Method for making carbon nanotube electron emission source by dot matrix sequential electrophoretic deposition - Google Patents

Abstract

A method for manufacturing a carbon nanotube electron emission source by dot matrix sequential electrophoretic deposition provides an interlaced electrophoretic deposition technology, so that only a single pixel electric field is formed in the electrophoretic deposition process, and only the electrophoretic region has an electrophoretic deposition effect; the multiple cathode electrodes of the cathode plate are arranged longitudinally, the electrode is provided with multiple positions to be deposited with electron emission sources, the multiple anode electrodes of the anode plate used for electrophoresis are vertically arranged corresponding to the cathode electrodes, potential differences are respectively provided between the cathode electrodes and the anode electrodes according to sequential change, when electrophoresis is carried out, only one staggered pixel between the cathode plate and the anode plate has electric field formation in unit time, so that the deposition effect is generated only in the area to manufacture the carbon nano tube electron emission sources, and the electrophoretic deposition of all pixels of the cathode plate is realized by utilizing the sequential voltage change of each cathode electrode or each anode electrode.

Description

Method for making carbon nanotube electron emission source by dot matrix sequential electrophoretic deposition

technical field

The invention relates to a field emission display, in particular to an electrophoretic deposition technology for manufacturing electron emission sources of each pixel by sequentially electrophoretic carbon nanotubes in a dot matrix.

Background technique

The field emission display of the present invention is a kind of use electric field to make cathode electron emitter (Cathode electron emitter) generate electrons, excite the fluorescent powder body of anode plate by described electron, make fluorescent powder body produce photon to emit light, the characteristic of this display It is light, thin, and the size of the effective display area can be produced according to the manufacturing process and product requirements. In addition, it does not have the viewing angle problem that flat liquid crystal displays have.

A traditional three-pole field emission display, its structure mainly includes an anode plate and a cathode plate, a supporter (spacer) is arranged between the anode plate and the cathode plate, as the interval of the vacuum area between the anode plate and the cathode plate, and as The support between the anode plate and the cathode plate, the anode plate includes an anode substrate, an anode conductive layer and a phosphor layer (phosphors layer); the cathode plate includes a cathode substrate, a cathode conductive layer, an electron emission source layer, a dielectric layer and A grid layer; wherein a potential difference is provided on the grid layer so that the electron emission source layer emits electrons, and the electron beam is accelerated by the high voltage provided by the anode conductive layer, so that the electrons have sufficient kinetic energy to impinge on the anode The phosphor layer on the board is excited to emit light. Therefore, in order to move electrons in a field emission display, it is necessary to use a vacuum device to keep the vacuum of the display below at least 10 ^-5 Torr (torr), so that the electrons have a sufficient mean free path (mean free path), and at the same time avoid Pollution and poisoning of electron emission sources and phosphor areas. In addition, in order for the electrons to have enough energy to hit the phosphor, there needs to be a proper gap between the two plates, so that the electrons have enough acceleration space to hit the phosphor, so that the phosphor can fully produce the luminous effect.

Among them, the so-called electron emission source layer is mainly composed of carbon nanotubes (Carbon nanotubes). Since carbon nanotubes were proposed by Iijima in 1991 (Nature354, 56 (1991)) with extremely high electronic properties, they have been used by various electronic materials. used by the component. Carbon nanotubes can have a high aspect ratio (aspect ratio), its aspect ratio is greater than 500, and it has high rigidity, and its Young's modulus is mostly above 1000GPn, while the tip or defect of carbon nanotubes are both Atomic scale exposure, because of its above characteristics, is considered to be an ideal field electron emission source (electron field emitter) material, such as an electron emission source used in a cathode plate of a field emission display. Due to the above-mentioned physical properties of carbon nanotubes, they can also be designed to be used in various manufacturing processes, such as screen printing or thin film manufacturing processes, for patterning electronic components.

The so-called cathode plate manufacturing technology is to use carbon nanotubes as an electron source material on the cathode conductive layer. The manufacturing method includes chemical vapor deposition (CVD) of directly growing carbon nanotubes on the cathode electrode layer in each cathode pixel. method, or a method of totemizing the photosensitive carbon nanotube solution on the cathode conductive layer in each pixel, or a method of spraying the carbon nanotube solution with a mesh cover, but according to the above-mentioned tripolar field The electron emission source structure of the emissive display requires carbon nanotubes to be fabricated on the cathode electrode structure in each pixel. The above-mentioned fabrication methods are all limited by the production cost and the hindrance of the three-dimensional structure, especially for large-scale electron emission sources. , its uniformity will be more difficult to achieve.

Recently, a so-called electrophoretic deposition EPD (Electrophoresis Deposition) technology has been successively proposed, such as the publication of the US patent application No. US2003/0102222. Aluminum plasma salts are used as an auxiliary salt (Charger) to make an electrophoretic solution. The cathode electrode substrate to be deposited is connected to the electrode and placed in the electrophoretic solution. An electric field is formed in the solution by providing a DC or AC voltage. The auxiliary salt The ions ionized in the solution are attached to the carbon nanotube powder, which forms an electrophoretic force through an electric field to assist the carbon nanotubes to be deposited on a specific electrode, so that the carbon nanotubes can be patterned and deposited on the electrode, using the above electrophoresis Deposition technology can simply deposit carbon nanotubes on the electrode layer and avoid the structural limitations of the cathode structure of the triode field emission display. Therefore, this technology has been widely used in the manufacture of cathode plate structures.

However, in the traditional electrophoretic deposition method, in order to enable the carbon nanotubes to be deposited only on the cathode electrode without depositing on the grid and causing conduction between the grid and the cathode electrode, more than the grid and the dielectric layer forming a sacrificial layer or protective layer exposed only in the area of the cathode electrode layer to be patterned, performing electrophoretic deposition, and then removing the protective layer to prevent carbon nanotubes from remaining in unnecessary areas or causing conduction, Or, another traditional technology, Japanese Patent Publication No. 2001020093, is to form a protrusion in a specific area of the anode electrode of electrophoresis corresponding to the cathode. Since the protrusion is provided, the corresponding cathode electrode forms a specific electric field, which is It is beneficial for the carbon nanotubes in the solution to be deposited in this specific area, and the deposited carbon nanotubes are easy to condense and concentrate on a specific electrode layer area, or a simple fabrication mentioned in the applicant's previous application The totem electrophoretic anode structure, which provides an anode plate device that effectively concentrates the electrophoretic deposition area.

Although the current electrophoretic deposition method limits the electrophoretic deposition area, the traditional method also needs to provide voltages on the cathode and anode plates at the same time to form an electric field, so careful calculation and design are required so that the formed electric field can achieve an effective regionalization effect , and its practicability is likely to be limited, especially for high-resolution panels, the unit electrophoretic area that can be formed will be smaller, and the formed point-to-point electric field is more likely to be limited by the adjacent electric field distribution, so it is difficult to achieve the desired effect, that is, although it It is a point-to-point electrophoretic deposition technology, but because the electric field is generated at the same time, the electric fields of adjacent pixels are prone to interact, thus easily losing the matrix point-to-point electrophoretic deposition effect.

Contents of the invention

The main purpose of the present invention is to improve the effect of regionalized electrophoretic deposition in a dot matrix structure. The present invention proposes a staggered electrophoretic deposition technology, which allows electrophoretic deposition to occur on only one pixel within the electrophoresis time, thereby making electrophoretic deposition regionalized Concentration, while the design of the anode plate and the electric field generated by electrophoresis are more simplified, and the current density that can be applied during electrophoresis is increased. In the production of large-area panels, the design cost and power consumption of the equipment used are reduced, and the safety of operation is improved. .

In order to achieve the above object, the point matrix type sequential electrophoretic deposition of the present invention makes the method for carbon nanotube electron emission source, comprising:

Connect the anode end of the power supply device to a plurality of anode electrodes of the anode plate, connect the cathode end to the signal amplification unit, connect the output end of the signal amplification unit to the plurality of cathode electrodes of the cathode plate, and connect the plurality of cathode electrodes to the plurality of cathode electrodes. The anode electrodes are vertically corresponding, and then the signal generating unit is connected to the input ends of the plurality of signal amplifying units; the cathode plate and the anode plate are placed in the electrophoresis tank in parallel correspondence;

Then, the anode terminal of the power supply device outputs voltage to a plurality of anode electrodes of the anode plate, and the signal generating unit inputs the pulse signal generated sequentially into one of the signal amplifying units, and is amplified by the signal amplifying unit Finally, make one of the cathode electrodes in the cathode plate be in an energized state, while the rest of the cathode electrodes are not energized, so that only a single pixel between the cathode electrode and the anode electrode forms a potential difference to generate an electric field, thereby preparing to deposit electrons on the cathode electrode. Formation of carbon nanotubes at the position of the emission source;

After the above steps, the next cathode electrode is energized and the remaining cathode electrodes are not energized, so as to complete the fabrication of dot matrix sequential electrophoretic deposition carbon nanotube electron emission sources for multiple cathode electrodes.

Description of drawings

Fig. 1 is negative, anode plate schematic diagram of the present invention;

Figure 2 is a schematic diagram of the connection between the cathode and anode plates of the present invention and the electrophoresis equipment;

Fig. 3 is the schematic diagram of electrophoresis manufacturing process of cathode and anode plates of the present invention;

Fig. 4 is a simple schematic diagram of the connection between the cathode and anode plates of the present invention and the electrophoresis equipment;

Fig. 5 is a schematic diagram of another cathode and anode plate electrophoresis manufacturing process of the present invention.

In the accompanying drawings, the list of parts represented by each label is as follows:

Cathode plate 1, 1a Cathode electrode 11, 11a

Anode plate 2, 2a Anode electrode 21, 21a

Scanning power supply unit 3, 3a Signal amplifying unit 4, 4a

Signal generating unit 5, 5a Electrophoresis tank 6, 6a

Detailed ways

Relevant technical contents and detailed description of the present invention are as follows in conjunction with accompanying drawing now:

Fig. 1 and Fig. 2 are schematic diagrams of connection of cathode and anode plates and cathode and pole plates to electrophoresis equipment of the present invention. As shown in the figure, the dot-matrix sequential electrophoretic deposition method of the present invention for manufacturing carbon nanotube electron emission sources mainly uses the interlaced scanning electrophoretic deposition technology to stagger the current distribution to the pixels of the cathode electrode in different sections to make the cathode The carbon nanotube electron emission source on the board, this scanning method can effectively reduce the peak (peak) current, and this method can apply the pulse signal to the large-area panel production.

When the above-mentioned method is produced, the cathode plate 1 is firstly taken, and the cathode plate 1 has any one of a strip or 32 cathode electrodes 11 in a longitudinal layout, and the plurality of cathode electrodes 11 are all completed grids and sacrificial layers. Semi-finished structure, the sacrificial layer is used to protect areas that do not need electrophoretic deposition (such as gates, dielectric layers, etc.) Further, a×b or 32×32 pixels can be provided on the semi-finished substrate of the cathode plate 1;

Then take the anode plate 2, the anode plate 2 is to make a plurality of horizontally arranged anode electrodes 21 on the insulating plate, which are vertically corresponding to a plurality of cathode electrodes 11, and can provide b or 32 anode electrodes in cooperation with the pixels of the cathode plate 2 21, wherein the insulating plate can be a glass substrate, and a plurality of anode electrodes 21 are fabricated on the glass substrate by screen printing or photolithography;

Connect a plurality of anode terminals 31 of the scanning power supply device 3 to a plurality of anode electrodes 21 of the anode plate 2 to sequentially provide pulse voltages for each anode electrode 21, while the cathode terminal 32 is connected to the input of each signal amplifying unit 4 terminal, and the output terminal of the signal amplifying unit 4 is connected to each cathode electrode 11 of the cathode plate 1; in addition, the other input terminal of the signal amplifying unit 4 is connected to the signal generating unit 5 to complete the electrophoretic deposition production connection, wherein the scanning power supply device 3 is used to provide sequential delay (lag) pulse voltages for each anode electrode 21, and the signal generating unit 5 provides sequential signals for each cathode electrode 11, and through the plurality of signal amplifying units 4 and the cathode The electrodes 11 are connected, and the signal amplifying unit 4 is used to provide an amplified signal after voltage amplification.

Figure 3 and Figure 4 are simple schematic diagrams of the electrophoresis manufacturing process of the cathode and anode plates and the connection between the cathode and anode plates and the electrophoresis equipment of the present invention. As shown in the figure, after the cathode plate 1, the anode plate 2, the scanning power supply unit 3, the signal amplification unit 4 and the signal generation unit 5 are connected, the electrophoresis solution inside the electrophoresis tank 6 will be prepared: using ethanol as a solvent, electrophoresis The electron emission source material powder is a carbon nanotube produced by arc discharge, the average carbon tube length is less than 5μm, and the average carbon tube diameter is less than 100nm. It is a carbon nanotube structure with multiple walls. Concentration by weight is 0.1%～0.005% (preferably 0.02%), the metal oxide salt that can have conductivity after electrophoresis is selected for use as auxiliary salt, as indium chloride, and indium nitrate, or other similar salts, the present invention selects weight Indium chloride salt with a concentration of 0.1% to 0.005% (preferably 0.01%), and glass powder for increasing adhesion with a weight concentration of at least 5%;

Place the cathode plate 1 and the anode plate 2 in the electrophoresis tank 6 correspondingly, and keep a distance of 3-5 cm between them. Among them, the voltage supply method of the scanning power supply device 3 is to complete a full-area electrophoresis in one cycle time. Taking one second to complete a full-scale electrophoresis as an example, the scanning power supply device 3 sequentially supplies the plurality of anode electrodes in a delayed and sequential manner. 21 provides a voltage signal with a frequency of b or 32, and each anode terminal provides a pulsed voltage with a positive voltage of 120V and a duty ratio (Duty)=1/b or 1/32 to a plurality of anode electrodes of the anode plate 2 21a, and the continuous square wave signal generated by the signal generating unit 5 is output to the first signal amplifying unit 4, and after the first signal amplifying unit 4 amplifies the signal, it is immediately provided to the first cathode electrode of the cathode plate 1 11 to form a energized state, and at this time, the rest of the cathode electrodes 11 form a non-energized state, so only the first cathode electrode 11 and the first anode electrode 21 form a potential difference in a single pixel during the electrophoresis time to generate an electric field, Carbon nanotubes are formed on the cathode electrode 11 where the electron emission source is to be deposited. Then, the next cathode electrode 11 is turned on and the rest are not turned on sequentially, so as to form carbon nanotubes at corresponding positions of the next pixel. The fabrication of the electron emission source of the cathode electrode 11 is completed by this sequential electrophoretic deposition fabrication method. Accordingly, the above-mentioned cathode electrodes 11 are sequentially changed in duty ratio=1/32 or 1/a (or higher in frequency multiplication), and the frequency of delay sequential scanning of each cathode electrode 11 is a or 32, and each pixel Electrophoretic deposition is carried out at the frequency of a×b or 32×32 or its frequency multiplier, and the electrophoresis action time is 15 minutes. One electrophoresis can form an electron emission source structure with a uniform thickness of about 5-10um.

Fig. 5 is a schematic diagram of another cathode and anode plate electrophoresis manufacturing process of the present invention. In this embodiment, there are mainly a plurality of cathode electrodes 11a on the cathode plate 1a, and a plurality of anode electrodes 21a on the anode plate 2a, and the anode end 31a of the scanning power supply device 3a is connected to the plurality of anode electrodes 21a of the anode plate 2a. Above, the pulse voltage is provided sequentially for each anode electrode 21a, and the cathode terminal 32a is connected to the input terminal of the signal amplifying unit 4a, and the output terminal of the signal amplifying unit 4a is connected to a plurality of cathode electrodes 11a of the cathode plate 1a, and then the signal The generating unit 5a is connected to the input end of the signal amplifying unit 4a, and then the plurality of cathode electrodes 11a and anode electrodes 21a are vertically corresponding and placed in the electrophoresis tank 6a with a distance of 3-5 cm. The scanning power supply device 3a delays The voltage signal is sequentially provided to each anode electrode 21a sequentially, and the delay is sequentially scanned to each anode electrode 21a, and the scanning power supply device 3a provides a pulsed voltage with a positive voltage of 120V. At this time, the signal generating unit 5a generates signals output to a plurality of signal amplifying units 4a, wherein the first signal amplifying unit 4a does not perform signal amplifying processing, so that the first cathode electrode 11a of the cathode plate 1a is formed into a low potential state. The remaining cathode electrodes 11a form a high potential state (that is, the potentials of the cathode electrode and the anode electrode are equal, and there is no potential difference), so only a single pixel between the first cathode electrode 11a and the first anode electrode 21a forms a potential during electrophoresis. difference to generate an electric field, so that the cathode electrode 11a is prepared to form carbon nanotubes at the position where the electron emission source is to be deposited, and then sequentially scan to the pixel of the next cathode electrode 11a.

After the above description, it can be seen that the point matrix type sequential electrophoretic deposition of the present invention makes the advantages of the carbon nanotube electron emission source method as follows:

1. The electrode wires on the cathode and anode plates of the electrophoresis are staggered and correspondingly arranged, so that the electrophoretic deposition is concentrated on only one pixel during the electrophoresis time, so as to realize the regionalization and concentration of the electrophoretic deposition.

2. The invention provides a simpler electrophoresis anode plate design, which avoids the interaction of complex electric fields in the traditional electrophoresis process and simplifies the electric field generated by electrophoresis.

3. Since the unit electrophoresis can be regionalized, the applicable current density during electrophoresis can be increased.

4. Large-area electrophoresis has a large amount of current, and the design cost of equipment and power consumption is reduced, and the safety of operation is improved.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the implementation scope of the present invention. All equivalent changes and modifications made within the patent scope of the present invention are included in the patent scope of the present invention.

Claims (17)

1. A method for making carbon nanotube electron emission source by sequential electrophoretic deposition of dot matrix, comprising: a), connect the anode end of the power supply device to a plurality of anode electrodes of the anode plate, connect the cathode end of the power supply device to the input end of the signal amplifying unit, and the output end of the signal amplifying unit is connected to a plurality of cathodes of the cathode plate On the electrodes, the plurality of cathode electrodes are vertically corresponding to the plurality of anode electrodes, and then the signal generating unit is connected to the input end of the plurality of signal amplification units; b), preparing the electrophoresis solution inside the electrophoresis tank, and placing the cathode plate in the electrophoresis tank in parallel with the anode plate; c) The anode terminal of the power supply device outputs voltage to a plurality of anode electrodes of the anode plate, and the signal generating unit inputs the pulse signal generated sequentially into one of the signal amplifying units, through the After the signal amplifying unit is amplified, one of the cathode electrodes in the cathode plate is energized, while the rest of the cathode electrodes are not energized, so that only a single pixel forms a potential difference between the cathode electrode and the anode electrode during the electrophoresis time To generate an electric field, thereby forming carbon nanotubes at the position where the cathode electrode is prepared to deposit an electron emission source; d), after the above (c) step is completed, then enter the state of the next cathode electrode being energized and the rest of the cathode electrodes not being energized, so as to complete the dot matrix sequential electrophoretic deposition type carbon nanotube electron emission source of multiple cathode electrodes make. 2. the method for making carbon nanotube electron emission source by dot matrix type sequential electrophoretic deposition as claimed in claim 1, wherein, described power supply device is scanning type power supply device, and the voltage mode that provides is to complete a full cycle time For area electrophoresis, the one cycle time is preferably one second, and the anode terminal of the power supply device provides a pulsed voltage with a positive voltage of 120V. 3. The method for fabricating carbon nanotube electron emission sources by dot-matrix sequential electrophoretic deposition as claimed in claim 1, wherein the anode plate is made on an insulating plate to do a plurality of anode electrodes arranged laterally. 4. point matrix type sequential electrophoretic deposition as claimed in claim 3 makes the method for carbon nanotube electron emission source, wherein, described insulating plate can be glass substrate, by screen printing or lithography etc. Make the anode electrode. 5. The method for fabricating carbon nanotube electron emission sources by dot-matrix sequential electrophoretic deposition as claimed in claim 1, wherein the cathode plate has a plurality of vertically arranged cathode electrodes. 6. The method for fabricating carbon nanotube electron emission sources by dot-matrix sequential electrophoretic deposition as claimed in claim 1, wherein the cathode electrode is a semi-finished structure that has completed grid and sacrificial layer fabrication. 7. The method for fabricating carbon nanotube electron emission sources by dot-matrix sequential electrophoretic deposition as claimed in claim 6, wherein the sacrificial layer is used to protect areas that do not need electrophoretic deposition from generating deposit residues. 8. The method for fabricating carbon nanotube electron emission sources by dot-matrix sequential electrophoretic deposition as claimed in claim 6, wherein the sacrificial layer is removed after the electrophoretic deposition is completed. 9. The method for fabricating carbon nanotube electron emission sources by dot-matrix sequential electrophoretic deposition as claimed in claim 1, wherein the cathode plate and the anode plate are placed in the electrophoresis tank in parallel with a distance of 3-5 cm. 10. The method for making carbon nanotube electron emission source by dot matrix type sequential electrophoretic deposition as claimed in claim 1, wherein, described solution is solvent with ethanol, and the electron emission source material powder of electrophoresis adopts a kind of by arc discharge to make The carbon nanotubes have an average carbon tube length of less than 5 μm and an average carbon tube diameter of less than 100 nm, which is a multi-walled carbon nanotube structure, and the added weight concentration is 0.1% to 0.005%. 11. The method for fabricating carbon nanotube electron emission sources by dot-matrix sequential electrophoretic deposition as claimed in claim 10, wherein the added weight concentration is preferably 0.02%. 12. The method for making carbon nanotube electron emission sources by dot-matrix sequential electrophoretic deposition as claimed in claim 1, wherein, the solution also includes auxiliary salts, and the auxiliary salts can have conductivity after electrophoresis. metal oxide salts. 13. The method for fabricating carbon nanotube electron emission sources by dot-matrix sequential electrophoretic deposition as claimed in claim 12, wherein the metal oxide salts are indium chloride and indium nitrate. 14. The method for making carbon nanotube electron emission sources by dot-matrix sequential electrophoretic deposition as claimed in claim 12, wherein the auxiliary salts are indium chloride salts with a weight concentration of 0.1% to 0.005%, and adding weight Concentration above 5% glass frit for increasing adhesion. 15. The method for fabricating carbon nanotube electron emission sources by dot-matrix sequential electrophoretic deposition as claimed in claim 14, wherein the weight concentration of the auxiliary salts is preferably 0.01%. 16. The method for manufacturing carbon nanotube electron emission sources by dot-matrix sequential electrophoretic deposition as claimed in claim 1, wherein the signal generation unit generates a continuous square wave output. 17. A method for manufacturing carbon nanotube electron emission sources by dot matrix sequential electrophoretic deposition, comprising: a), connect the anode end of the power supply device to a plurality of anode electrodes of the anode plate, connect the cathode end of the power supply device to the input end of the signal amplifying unit, and the output end of the signal amplifying unit is connected to a plurality of cathodes of the cathode plate On the electrodes, the plurality of cathode electrodes are vertically corresponding to the plurality of anode electrodes, and then the signal generating unit is connected to the input end of the plurality of signal amplification units; b), preparing the electrophoresis solution inside the electrophoresis tank, and placing the cathode plate in the electrophoresis tank in parallel with the anode plate; c) The anode terminal of the power supply device outputs voltage to a plurality of anode electrodes of the anode plate, and the signal generating unit inputs the generated pulse signal into the plurality of signal amplifying units to sequentially make the A signal amplifying unit does not amplify the pulse signal, so that one cathode electrode in the cathode plate is in a low potential state, while the remaining cathode electrodes are in a high potential state, that is, the potentials of the remaining cathode electrodes and the anode electrodes are equal, There is no voltage difference, so that only a single pixel forms a potential difference between the cathode electrode with a low potential and the anode electrode with a high potential to generate an electric field, thereby forming carbon nanotubes at the position where the cathode electrode is prepared to deposit an electron emission source; d) After the above step (c) is completed, enter the state where the next cathode electrode is at a low potential and the rest of the cathode electrodes are at a high potential, so as to complete the dot matrix sequential electrophoretic deposition of carbon nanotube electrons on multiple cathode electrodes. Emitter production.

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