TWI460759B - Method for manufacturing electron source of nanometer carbon tube - Google Patents

Description

Nano carbon tube field emission electron source manufacturing method

The present invention relates to a method for producing a carbon nanotube field emission source, and more particularly to a method for manufacturing a carbon nanotube emission source for producing a multi-directional electron emission path.

Since its discovery in the 1990s, carbon nanotubes have a special cylindrical structure composed of hexagonal carbon atom lattices due to their nanometer size and large surface area, as well as unique electrical, magnetic and optical properties. And the potential of the application, so it is particularly eye-catching. The carbon nanotubes have a very small tip radius of curvature, extremely small size, hollow shape, high chemical stability and high mechanical strength, and can provide a variety of applications, such as field emission sources, hydrogen storage vehicles, and crystals at room temperature. Etc., especially the high tube diameter ratio and high chemical stability, making it a more forward-looking field emission source, so the carbon nanotubes have excellent field emission characteristics, and the electric field generated at lower voltages can be It induces a large current density, making it the best material for a field emission cathode emitter.

At present, there are two main ways to fabricate the cathode structure of the carbon nanotubes. One is to directly grow the carbon nanotubes on the glass substrate by chemical vapor deposition (CVD), but the synthesis temperature exceeds the softening temperature of the substrate. The application of large-area displays is also limited; the other way is to use the screen printing method to directly print the carbon nanotube paste on the substrate. Compared with the CVD method, the screen printing method is not only low in cost, but also relatively simple to manufacture. And can be printed on a large area. However, after the carbon nanotube slurry is screen printed on the substrate, during the high-temperature sintering process, the carbon nanotubes react with the organic vehicle in the slurry to cause a large mass loss, and the emission of the carbon nanotubes. The stability is deteriorated. In addition, the structure manufactured by the screen printing method has no directionality, so further activation is required. The common method is that the flat carbon tube is pulled up to be perpendicular to the substrate, but this is The method will cause the chemical substances in the tape to remain in the cathode structure to cause secondary pollution, and the direct contact will also damage the structure and affect the field emission stability and life.

In view of the above, the present invention provides a method for manufacturing a carbon nanotube field emission source, Improve these shortcomings that existed in the prior art.

The main object of the present invention is to provide a method for manufacturing a carbon nanotube field emission source, which can omit the subsequent activation step to simplify the process of the carbon nanotube field emission source, thereby reducing the manufacturing cost.

Another object of the present invention is to provide a method for producing a carbon nanotube field emission source which can be reacted at a relatively low temperature without the need for an external hydrocarbon gas to reduce the manufacturing risk.

It is yet another object of the present invention to provide a method of application to a carbon nanotube field emission source on a field emission display or high performance light emitting device.

In order to achieve the above object, the present invention provides a method for fabricating a carbon nanotube field emission source, comprising: providing a substrate; disposing an electrode layer on the substrate; and providing a mixture mixed by a carbon nanotube slurry and carbon powder And coating the mixture on the electrode layer by screen printing and sintering to perform a thermal cracking reaction to form a carbon nanotube emitting layer of a thorn-shaped carbon nano-cluster structure.

In addition, the carbon nanotube field emission source manufactured by the invention can be applied to a field emission display or a high-performance light-emitting element. Taking a field emission display as an example, after obtaining the cathode plate according to the above steps, a field emission display can be assembled, and the method includes Providing a cathode plate having an electrode layer on an upper surface thereof, and a carbon nanotube emitting layer having a thorn-like carbon nano-cluster structure on the electrode layer; a space support on the cathode plate; and a space supporter An anode plate is disposed on the top edge, the space support is interposed between the cathode plate and the anode plate; and the cathode plate, the space supporter and the anode plate are placed in a vacuum chamber, and the cathode plate and the space are further supported The device and the anode plate are packaged; the field emission display can be completed according to the above steps.

In order to further understand the purpose, features and functions of the present invention, the drawings are described in detail as follows:

Please refer to the first figure for the steps of the method for manufacturing the carbon nanotube field emission source of the present invention. flow chart. Please refer to the second figure together for a cross-sectional view of the structure of the cathode plate of the present invention. In the first figure, the step of the carbon nanotube field emission source includes: Step S10: providing a substrate 211, and the substrate 211 is a glass substrate, a plastic substrate, a ceramic substrate or a germanium substrate.

Step S11: An electrode layer 212 is disposed on the substrate 211. The manufacturing process of the electrode layer 212 includes the following steps: applying a photosensitive conductive paste to a surface of the substrate 211, and using a photolithography process, The pattern is made, and after the sintering, the electrode layer 212 is completed. The lithography process includes pre-baking and defining the pattern with a photomask, and exposing and developing.

Step S12: providing a mixture of carbon nanotube slurry and carbon powder, wherein the mixture is uniformly mixed with carbon powder by using a three-roller device, and the carbon nanotube slurry is Including multi-walled carbon nanotubes (MWCNTs), organic vehicles, such as terpineol or ethyl cellulose (EC), binders, such as glass frits, conductive powders and dispersants, For example, a polyethanol phenol ether surfactant (Triton X-100). The carbon powder selected by the invention can be obtained from the recovered carbon powder gate, and the carbon powder comprises magnetic particles, a polymer and a carbon black element, and the carbon powder is cleaved into carbon atoms, iron and cobalt under the action of high temperature. The particles such as nickel react to form a carbon nanotube.

Step S13: The mixture is applied onto the electrode layer 212 by screen printing.

Step S14: sintering is performed to cause the mixture to undergo a thermal cracking reaction to form a carbon nanotube emitting layer 213 of a thorn-shaped carbon nanocluster structure.

Wherein, in step S14, the mixture is subjected to a thermal cracking reaction by a heating step of heating at a constant temperature in a plurality of stages, and then the temperature is lowered to room temperature, and the sintering step comprises: heating the mixture to raise the temperature to the first The heating temperature of the stage is maintained for a period of time, so that the polymer undergoes the first stage of removing hydrogen and removing unwanted volatile products. In the present invention, the heating temperature of the first stage is preferably between 300 and 350 ° C, and the heating rate from the room temperature to the first stage is preferably 2 to 5 ° C per minute. After the heating temperature of the first stage is completed, the temperature is further increased to the heating temperature of the second stage and the temperature is maintained for a period of time, so that the polymer undergoes the second stage thermal cracking reaction, at this time, the carbon powder and the carbon nanotube slurry The carbon cleavage of the polymer in the thermal cracking reaction is used as a carbon source, and the carbon nanotube emitting layer 213 of the thorn-like carbon nano-cluster structure can be grown, so that it is not required Add hydrocarbon gas to reduce the risk of carbon nanotube field emission sources made by conventional technology. In the present invention, the heating temperature of the second stage is preferably between 350 and 500 ° C, and the heating rate from the room temperature to the second stage is preferably 2 to 5 ° C per minute.

Due to the low cracking temperature of the carbon powder, when the carbon powder and the multi-walled carbon nanotubes in the carbon nanotube slurry are subjected to the cracking reaction, in addition to reducing the probability of oxidation of the multi-walled carbon nanotubes, it is also possible to synthesize A carbon cluster material which is advantageous for the field emission effect. The material is characterized in that the structure of the hedgehog-shaped carbon cluster can have one side facing the anode at all times, thereby reducing the subsequent surface treatment steps and solving the current preparation and activation of the cathode structure. The shortcomings of the complexity of the program, in other words, the field emission characteristics of high current density can be obtained, and the advantages of shortening the manufacturing process and the process time and reducing the cost can be achieved, and the emission plane can be effectively applied to the large-area process production site. On a display or high-performance light-emitting element.

In addition, in order to obtain a high-yield locust-shaped nanocarbon cluster, the mixture may be subjected to a thermal cracking reaction step, which comprises a step of introducing a gas into the first stage of the heating temperature prior to the thermal cracking reaction. Before the constant temperature, the air is introduced before the nitrogen gas is introduced, and after the temperature is raised to the heating temperature of the second stage, the nitrogen gas is replaced to replace the air in the reaction chamber, thereby, in accordance with the above manufacturing steps, during the sintering process. The gas, temperature and mixture can promote the formation of the carbon nanotubes, in addition to protecting the original carbon nanotubes from damage, and also growing the carbon nanotube emitting layer 213 of the hedgehog-like carbon cluster structure. After the sintering is completed, a cathode plate 21 can be completed.

Referring to the third and fourth figures, after the above-mentioned sintering to thermally decompose the mixture, the scanning electron microscope (SEM) can be used to observe the shape of the hedgehog produced by the manufacturing method indicated by the present invention. An image of the nanocarbon cluster structure. Since the carbon nanotubes emit electrons in all directions in a hedgehog shape, the structure of the thorn-shaped carbon nano-cluster structure produced by the present invention is a carbon nanotube emitting layer of a multi-directional electron emission path, so that it is not required to be activated. The high current density and low turn-on voltage characteristics can be achieved.

The nanocarbon tube field emission source manufactured by the invention can be applied to a field emission display or a high-performance light-emitting element, and is applied to a field emission display as an example, according to the manufacturing process steps of the nano carbon tube field emission source of the first figure. After obtaining the cathode plate 21, a field emission display can be assembled. As shown in FIG. 5, the field emission display 50 includes: a substrate 211 provided with an electrode layer as a cathode layer 212 on the upper surface and a cathode layer 211 on the cathode layer 211. a carbon nanotube emitting layer 213 of a hedgehog-like carbon cluster structure, followed by a plurality of space spacers 51 disposed on the cathode plate 21, and an anode plate 52 disposed on a top edge of the space supports 51, The space supporter 51 is interposed between the cathode plate 21 and the anode plate 52. The anode plate 52 is made of transparent conductive glass (ITO-glass). The lower surface of the anode plate 52 is provided with a transparent conductive layer as the anode layer 53 and the anode. The layer 53 corresponds to the cathode plate 21, and a phosphor 54 is printed on the anode layer 53. The phosphor 54 is responsive to the design of the circuit, and is of the following two types: the first type is Formed in red, green and blue (abbreviated as RGB) The primary color phosphor, and are provided independently, while the second is the RGB colors formed on a single phosphor 54.

Please refer to the fifth and sixth figures. The sixth figure is a schematic diagram of the test field emission display of the present invention. The cathode plate 21, the space supporter 51 and the anode plate 52 are placed in a vacuum chamber 61, wherein The field effect emission display 50 can be completed by pumping the pressure of the cavity to below 10 - 5 Torr and further encapsulating the cathode plate 21, the space support 52, and the anode plate 53. The present invention can utilize a voltage supply device 62 (e.g., up to 1100V) to provide a voltage between the cathode plate 21 and the anode plate 52 for accelerating the emission of the carbon nanotube emission layer 213 from the cathode plate 21 in multiple directions. Upon exiting the electrons and impinging on the phosphor 54 of the anode plate 52, the phosphor 54 will excite a source of visible light.

The embodiments described above are merely illustrative of the technical spirit and the features of the present invention, and the objects of the present invention can be understood by those skilled in the art, and the scope of the present invention cannot be limited thereto. That is, the equivalent variations or modifications made by the spirit of the present invention should still be included in the scope of the present invention.

twenty one. . . Cathode plate

211. . . Substrate

212. . . Cathode layer

213. . . Carbon nanotube emission layer

50. . . Field emission display

51. . . Space support

52. . . Anode plate

53. . . Anode layer

54. . . Phosphor

61. . . Vacuum chamber

62. . . Voltage supply device

The first figure is a flow chart of the steps of the method for manufacturing the carbon nanotube field emission source of the present invention.

The second figure is a cross-sectional view showing the structure of a cathode plate manufactured by the present invention.

The third figure is an image view of the structure of the hedgehog-like carbon clusters observed by a scanning electron microscope (SEM) of the present invention.

The fourth figure is an image view of the structure of the hedgehog-like carbon clusters observed by a scanning electron microscope (SEM) of the present invention.

Figure 5 is a cross-sectional view of the present invention applied to a field emission display.

The sixth figure is a schematic diagram of the test field emission display of the present invention.

Claims (12)

A method for manufacturing a carbon nanotube field emission source, which is applied to a field emission display or a high-performance light-emitting element, the method comprising: providing a substrate; disposing an electrode layer on the substrate; providing a mixture consisting of nano carbon The tube slurry and the carbon powder are mixed, and the carbon nanotube slurry comprises a multi-walled carbon nanotube, an organic carrier, a binder, a conductive powder and a dispersing agent, and the carbon powder comprises magnetic particles, a polymer and a carbon. The black element; and the mixture is applied to the electrode layer by screen printing, and sintered to perform a thermal cracking reaction to form a carbon nanotube emitting layer of a thorn-like carbon nano-cluster structure. The method for producing a carbon nanotube field emission source according to claim 1, wherein the mixture is subjected to the thermal cracking reaction by a heating step of a plurality of different heating and constant temperature, and then the temperature is lowered to room temperature. . The method for manufacturing a carbon nanotube field emission source according to claim 2, wherein the heating step of the plurality of stages includes at least a first stage heating temperature between 300 and 350 ° C and a first The two-stage heating constant temperature is in the heating phase between 350 and 500 °C. The method for producing a carbon nanotube field emission source according to claim 3, wherein the heating rate from the room temperature to the heating temperature of the first stage is 2 to 5 ° C per minute. The method for producing a carbon nanotube field emission source according to claim 3, wherein the heating rate from the room temperature to the heating temperature of the second stage is 2 to 5 ° C per minute. The method for producing a carbon nanotube field emission source according to claim 1, wherein the step of performing the thermal cracking reaction of the mixture further comprises a step of introducing a gas. The method for producing a carbon nanotube field emission source according to claim 6, wherein the gas system is nitrogen. A method for manufacturing a carbon nanotube field emission source as described in claim 7 of the patent application, wherein The step of introducing the gas is to introduce air before the temperature is raised to the heating temperature of the first stage, and the nitrogen is changed after the temperature is raised to the heating temperature of the second stage. The method for producing a carbon nanotube field emission source according to claim 1, wherein the substrate is a glass substrate, a plastic substrate, a ceramic substrate or a germanium substrate. The method for producing a carbon nanotube field emission source according to claim 1, wherein the mixture is obtained by uniformly mixing the carbon nanotube slurry with the carbon powder by using a three-roller device. The method for manufacturing a carbon nanotube field emission source according to claim 1, wherein the carbon in the thermal cracking reaction of the carbon powder and the carbon nanotube slurry is used as a carbon source. The hedgehog-like carbon cluster structure can be grown. The method for producing a carbon nanotube field emission source according to claim 1, wherein the thorn-shaped carbon nano-cluster structure is a carbon nanotube emission layer of a multi-directional electron emission path.