JP3972107B2 - Manufacturing method of electron emission source using carbon nanotube and polymer - Google Patents

Description

The present invention relates to a method for producing an electron emission source using carbon nanotubes and polymers that emit electrons at a low voltage.

  Recently, field emission displays (FEDs) have been actively developed not only in Japan but also overseas including Korea. Field emission refers to a phenomenon in which, when a strong electric field is applied to a solid surface, electrons confined on the solid surface jump out into the vacuum. In order to emit electrons, it is necessary to apply a strong voltage to the solid, but if a solid with a fine point is used, only a small voltage needs to be applied. In the past, materials such as finely sharpened silicon and molybdenum have been used as field emission electron sources, but recently, nanoscale thinness, good electrical conductivity, high strength, and chemical stability Carbon Nanotubes (CNTs) that combine these properties are expected as a new field emission electron source.

  The FED is a display that forms an image by emitting light by applying electrons to phosphors arranged in units of pixels. In order to use CNT as a field emission electron source, it is necessary to arrange a large number of CNTs substantially perpendicular to the phosphor so that electrons can be emitted toward the phosphor on the back surface of the FED glass plate. is there. Normally, a large number of CNTs are erected in a conductive polymer film. In this step, it is important how vertically the CNTs are erected in the conductive polymer.

  As a method of standing CNTs in a conductive polymer, for example, a spin coating method is known (see, for example, Patent Document 1). The spin coating method is a method in which a mixture of a conductive polymer and an electrode material such as CNT is applied onto a disk, and the disk is rotated and spread and cured.

JP 2000-277004 A (Claims, Abstract, etc.)

  However, in the case of the spin coating method, only the conductive polymer and the CNT spread due to the centrifugal force generated by the rotation of the disk, so that there are not necessarily many CNTs standing vertically on the conductive polymer. If the vertical alignment of CNTs is low, the number of electrons effective for causing the phosphor to emit light is reduced even if a large number of electrons are emitted. Therefore, a voltage for causing the phosphor to emit light is not yet sufficiently low, and an FED that can emit electrons at a lower voltage is strongly desired.

The present invention has been made in view of such problems, and an object of the present invention is to provide a method for producing an electron emission source using a carbon nanotube and a polymer capable of further reducing the voltage required for electron emission. .

In order to achieve the above object, the present invention provides a method of manufacturing an electron emission source that emits electrons by field emission, comprising an anode connected to a power source in an organic solvent containing a conductive polymer and carbon nanotubes. Inserting the cathode, depositing the conductive polymer and the carbon nanotubes on the cathode, and depositing the conductive polymer and the carbon nanotubes, then pulling the cathode out of the solution, and the surfaces of the cathode and the deposit And a step of performing an electric field treatment in which a voltage in the range of 150 to 250 V is applied between the two and the electron emission source using a carbon nanotube and a polymer. By employing such a production method, a film in which carbon nanotubes are dispersed in a conductive polymer can be obtained. In the manufacturing process, the carbon nanotubes are easily deposited with the length direction facing the cathode. For this reason, it is possible to obtain a film in which the carbon nanotubes are erected vertically to the conductive polymer film. In particular, by performing such an electric field treatment, a good electron emission source having a lower threshold voltage can be obtained. Even if the voltage in the electric field treatment is less than 150V or higher than 250V, the effect of lowering the threshold voltage is low. In the case of a voltage in the range of 150 to 250 V, the threshold voltage decreases.

  In another aspect of the present invention, the conductive polymer is composed of one or more of polyvinyl carbazole, soluble polyparaphenylene vinylene, soluble polyaniline, poly (alkyl) fluorene, and poly (alkyl) thiophene. It is a polymer. These polymers are easily soluble in organic solvents, and are particularly excellent in conductivity among conductive polymers. Therefore, an electron emission source using carbon nanotubes and a polymer can be easily manufactured, and an electric field can be easily applied to the carbon nanotubes.

Another aspect of the present invention is a method for producing an electron emission source using a carbon nanotube and a polymer in which the weight ratio of the carbon nanotube to the conductive polymer contained in the organic solvent is 0.05 or more and 2 or less. When the weight ratio of the carbon nanotube to the conductive polymer is increased, theoretically, the voltage (threshold voltage) necessary for emitting electrons from the tip of the carbon nanotube is decreased. However, in reality, the probability of aggregation between the carbon nanotubes is also increased, so that the amount of carbon nanotubes is excessively increased and the threshold voltage is increased. When the weight ratio of the carbon nanotubes to the conductive polymer is 0.05 or more and 2 or less, it is possible to obtain an electron emission source having a low threshold voltage composed of carbon nanotubes with little aggregation between the carbon nanotubes and high dispersibility.

  In another aspect of the present invention, an electron emission source manufacturing method using carbon nanotubes and a polymer in which the above electric field treatment is performed at 200 V for 30 to 60 seconds is used. In particular, when the voltage in the electric field processing is set to 200 V and the electric field processing time is set in the range of 30 to 60 seconds, the threshold voltage is greatly reduced.

  According to the present invention, it is possible to provide an electron emission source using carbon nanotubes and a polymer, which requires a lower voltage for electron emission.

Embodiments of an electron emission source manufacturing method using carbon nanotubes and a polymer according to the present invention will be described below.

  FIG. 1 is a diagram showing a manufacturing process and an evaluation flow of an electron emission source (hereinafter simply referred to as “electron emission source”) using a carbon nanotube and a polymer according to an embodiment of the present invention.

  As shown in FIG. 1, a method for manufacturing an electron emission source includes adjusting a solution used for electrophoresis (hereinafter referred to as “electrophoretic solution”) (step S1), and forming a film in the electrophoretic solution (step 1). S2), consisting of a step of electric field processing (step S3) on the film after fabrication. Thereafter, evaluation (step S4) is performed. However, step S3 is not an essential step, and the evaluation can be performed after the film forming process.

  Next, each step described above will be described in detail.

(1) Preparation of electrophoresis solution (step S1)
Step S1 is a step of mixing the carbon nanotube and the conductive polymer in a solvent. In step S1, a method in which a solution in which carbon nanotubes are mixed with a predetermined liquid and a solution in which a conductive polymer is mixed with a predetermined liquid are prepared in advance, and both these solutions are mixed in a solvent. However, the carbon nanotube and the conductive polymer may be directly mixed in a solvent.

  Carbon Nano Tube (CNT) is a hollow tube in which a carbon hexagonal network called graphene is rolled into a cylinder with a nano-level diameter, and is a single-walled carbon nanotube (Single) Wall carbon nano tubes (SWCNT) and multi-wall carbon nanotubes (MWCNT) consisting of multiple graphenes with different diameters. As the CNTs used in a field emission display (FED), both SWCNTs and MWCNTs can be employed, but MWCNTs that emit many electrons at a low voltage are more advantageous. In the present invention, the CNTs are broadly interpreted as including ultra-fine CNTs having a diameter of 1 nanometer or less and medium-sized CNTs of several nanometers to several tens of nanometers. Further, the CNT can be produced by any method such as an arc discharge method, a laser ablation method, a plasma synthesis method, and a chemical vapor deposition (CVD) method. However, CNTs produced by a CVD method advantageous for mass production are preferred.

  The conductive polymer refers to a polymer that conducts electricity like a metal by a dopant. As the conductive polymer used in the practice of the present invention, any conductive polymer that is soluble in an organic solvent can be applied, and those belonging to a p-type semiconductor are particularly preferable. The introduced substituent is preferably a hydrocarbon group (such as an alkyl group). The alkyl group may be either a straight chain or a branched chain, but is preferably a hexyl group, a heptyl group, an octyl group, a nonyl group, or a decyl group. For example, polyvinylcarbazole, soluble polyparaphenylene vinylene (MEH-PPV (Poly [2-methoxy-5- (2'ethylhexyloxy) -1,4-phenylenevinylene]), soluble polyaniline, poly (alkyl) fluorene or poly (alkyl) In view of solubility and heat resistance, the length of the alkyl group is preferably in the range of 4 to 20 carbon atoms, especially poly (3-octylthiophene) in which the alkyl group has 8 carbons. Alternatively, it is preferable to employ poly (3-hexylthiophene) composed of 6 carbons, and a plurality of the above conductive polymers may be used.

  The weight ratio of CNT to the conductive polymer is preferably 0.05 or more and 2 or less. If the weight ratio is less than 0.05, an electron emission effect sufficient to cause the phosphor to emit light sufficiently cannot be expected. On the other hand, if the weight ratio is larger than 2, the volume ratio occupied by the CNTs is too large, and it becomes difficult to handle, and it becomes easy to aggregate and the dispersibility decreases. The solvent to be used is not particularly limited as long as it is a medium that can disperse CNT and a conductive polymer and deposit these conductive substances on the cathode, but an organic solvent such as acetonitrile or toluene is preferable.

(2) Film formation process (step S2)
Film formation is performed by electrophoresis. Two electrodes are inserted into the container containing the electrophoretic solution prepared in step S1, and each electrode is connected to the positive electrode side and the negative electrode side of the DC power supply. The electrode is made of a highly conductive material. As the electrode, for example, platinum, copper, indium tin oxide (ITO), gold, or aluminum can be used.

  The two electrodes connected to the DC power source are a positive electrode and a negative electrode. The CNT and the conductive polymer in the electrophoresis solution are attracted to the negative electrode and deposited on the surface thereof. The film formation conditions can be selected as appropriate, but it is preferable to use a DC power source of 100 to 300 V and perform the treatment with a film formation time of 2 minutes or less.

(3) Electric field processing (step S3)
The electric field treatment is a treatment performed after drawing the negative electrode from the electrophoretic solution and drying, and applying a voltage between the upper and lower sides of the film formed on the negative electrode. Since the film is deposited on the negative electrode, one of the power supplies is connected to the negative electrode. The other side of the power supply is connected near the surface of the membrane. The voltage is preferably in the range of 150 to 250V. The electric field treatment time is preferably 30 to 60 seconds.

(4) Evaluation of film (step S4)
The film obtained by the film formation process is used for evaluation of the threshold voltage. In this evaluation, the voltage applied between the negative electrode directly below the film and the electrode disposed in a non-contact manner above the film is increased, and electrons are emitted from the tip of the CNT protruding on the surface of the film. This is performed by examining the voltage (threshold voltage) when electricity flows between the electrodes arranged in a non-contact manner above. The lower the threshold voltage, the better the electrode.

  Next, examples of the present invention will be described.

(Electrophoretic deposition conditions and evaluation methods)
The electrophoresis solution was 30 ml of acetonitrile (Acetonitrile), 0.5 ml of a poly (3-octylthiophene) solution (hereinafter referred to as “P3OT solution”) and 0.25 ml of a carbon nanotube solution (hereinafter referred to as “CNT solution”). The mixture was used. P3OT / CNT (weight ratio) in the electrophoresis solution is 2.0 (CNT / P3OT (weight ratio) is 0.5). The P3OT solution was prepared in advance by mixing 20 ml of toluene (Toluene) and 20 mg of P3OT. Further, the CNT solution was prepared in advance by mixing 5 ml of toluene (Toluene) and 5 mg of CNT. The used CNTs are those having a diameter of 12 to 15 Å made by Aldrich.

  FIG. 2 is a diagram showing the electrophoresis apparatus used in this example.

In this apparatus, the above-described electrophoresis solution 2 is placed in a cylindrical container 1 and two glass substrates 3 and 4 are inserted therein. The two glass substrates 3 and 4 were arrange | positioned at intervals of 5 mm. However, the distance between the glass substrates 3 and 4 is not limited to 5 mm. One glass substrate 4 was pasted with an ITO film on a part 5 thereof. In addition, an ITO film was attached to the entire surface of the other glass substrate 3. The sheet resistance of the ITO film was about 20 Ω / cm ² . A part 5 of the glass substrate 4 and the surface of the glass substrate 3 were connected to the negative electrode and the positive electrode of the DC power source 7 by extending the wiring 6, respectively. Therefore, a part 5 of the glass substrate 4 becomes the negative electrode 5, and the surface of the glass substrate 3 becomes the positive electrode 3.

  Since the CNT 8 and the conductive polymer 9 are both positively charged in the electrophoresis solution, when a voltage is applied between the positive electrode 3 and the negative electrode 5, the CNT 8 and the conductive polymer 9 are attracted to the negative electrode 5, respectively. It is burned. As a result, a deposit in which the CNT 8 and the conductive polymer 9 are mixed is formed on the surface of the negative electrode 5. This film forming process was performed by changing the voltage of the DC power source to 100V, 200V, and 300V. In addition, the processing time was two types of time of 5 seconds and 60 seconds.

  FIG. 3 is a diagram for explaining the electric field processing method employed in this embodiment. FIG. 3A shows a situation where the glass substrate 4 removed from the electrophoresis apparatus is placed on the silicon plate 20, and FIG. 3B shows a situation where electric field processing is performed.

On the negative electrode 5 of the glass substrate 4, a film 10 (part shown in black in the drawing) composed of CNTs 8 and a conductive polymer 9 was formed. On the other hand, a silica (SiO ₂ ) film 21 having a thickness of about 620 nm was formed in advance on the surface of the silicon plate 20 (shaded area in FIG. 3). However, only one corner 20a of the silicon plate 20 does not form a Si0 ₂ film 21, and a state in which silicon is exposed. The glass substrate 4 was placed from above the SiO ₂ film 21 of the silicon plate 20 so that the portion of the film 10 was in contact with the SiO ₂ film 21. In this state, the corner 20 a and the negative electrode 5 were connected to the DC power source 23 via the wiring 22. The voltage applied between the corner 20a and the negative electrode 5 was changed to 100, 140, 150, 200, 250, 260, 300, and 400V. The electric field treatment time was changed to 20 seconds, 30 seconds, 60 seconds and 70 seconds.

  FIG. 4 is a diagram for explaining an evaluation method of the film 10. 4A is a perspective view showing the evaluation status of the film 10, and FIG. 4B is a cross-sectional view taken along the line XX (dashed line) in FIG. FIG. Note that FIG. 4B exaggerates the thicknesses of various thin films for easy viewing.

  Four films (made of PET, thickness of about 25 microns) 25 were arranged around the negative electrode 5 of the glass substrate 4 after the film formation process or the electric field process. On the other hand, another glass substrate 27 with the ITO film 26 attached in a line shape was prepared, and the glass substrate 27 was placed on the film 25 so that the ITO film 26 intersected the film 10. The negative electrode 5 and the ITO film 26 were each connected to a DC power source 29 by extending the wiring 28. Further, an ammeter 30 was connected in the middle of the wiring 28.

  As shown in FIG. 4B, the CNTs 8 standing on the film 10 and the ITO film 26 thereabove are in a non-contact state. When the voltage between the negative electrode 5 and the ITO film 26 is increased in this state, when a certain voltage is exceeded, electrons are emitted from the tip of the CNT 8 and reach the ITO film 26, and the circuit formed as described above is formed. Current flows. The voltage at this time was examined and the film 10 was evaluated. This evaluation was performed in a vacuum. Moreover, in order to investigate the influence of temperature, it evaluated under the temperature of the range of normal temperature (20 degreeC) to 100 degreeC.

(Deposition conditions and evaluation method by spin coating method)
On the other hand, in order to compare with the performance of the film 10 produced by electrophoresis, a film produced by spin coating was also evaluated. The film forming conditions by the spin coating method are as follows.

  Five types of solutions (P3OT solutions) prepared by mixing 50 mg of P3OT, 5 ml of chloroform, and CNT were prepared. Here, the amounts of CNTs in various P3OT solutions were 0 mg (equivalent to 0 wt% with respect to the weight of the P3OT solution), 0.25 mg (equivalent to 0.5 wt% with respect to the weight of the P3OT solution), 0.5 mg ( 1.0 wt% corresponding to the weight of the P3OT solution), 1.0 mg (corresponding to 2.0 wt% relative to the weight of the P3OT solution), and 2.5 mg (corresponding to 5.0 wt% relative to the weight of the P3OT solution) did.

  Next, after ultrasonically dispersing the above P3OT solution for about 20 seconds, 50 microliters of the solution was dropped onto a medium rotating at 1000 rpm for 25 seconds to perform film formation. The evaluation of the film was performed by the same method as the evaluation of the film 10 prepared by electrophoresis (the evaluation described above).

(Evaluation results)
FIG. 5 is a graph showing emission characteristics of an electron emission source formed by spin coating as a comparison. The horizontal axis represents a value expressed in units obtained by dividing the voltage (electric field strength) applied between the negative electrode 5 and the ITO film 26 by the distance (= 25 μm) between the negative electrode 5 and the ITO film 26. Further, the vertical axis indicates the density of current generated when electrons are emitted from the negative electrode 5 to the ITO film 26. The same applies to the drawings after FIG. The samples were five types of electron emission sources containing 0, 0.5, 1.0, 2.0 and 5.0 wt% of CNT.

  From the graph shown in FIG. 5, in the case of an electron emission source not containing CNT, no current flows even if the voltage is increased to 25 V / μm, but electron emission containing 0.5 to 5.0 wt% of CNT. In the case of the source, it was found that current flows when the voltage is in the range of 6 to 17 V / μm. Looking at the relationship between the voltage at which this current starts to flow (threshold voltage) and the CNT concentration (wt%), in the electron emission source having a CNT concentration of 0.5 and 2.0 wt%, the threshold voltage is about 10 V / μm. However, in other electron emission sources having a CNT concentration, the threshold voltage was about 15 V / μm or more. Thus, there was no correlation between the CNT concentration (wt%) and the threshold voltage. Based on the Fowler-Nordheim equation, it was examined whether or not the current shown in FIG. 5 is due to field emission. As a result of the FN plot, it was confirmed that the above phenomenon was caused by field emission. From this, it can be seen that the electron emission source formed by spin coating does not show electron emission by field emission unless the voltage is increased to about 10 V / μm.

  FIG. 6 is a graph showing emission characteristics of an electron emission source formed by the electrophoresis method (voltage 200 V, film formation time 5 seconds) of the present invention. FIG. 7 is a graph showing emission characteristics of the electron emission source formed by the electrophoresis method (voltage 100 V, film formation time 60 seconds) of the present invention. The horizontal and vertical axes of both graphs are the same as those in FIG. The sample was an electron emission source having a P3OT / CNT (weight ratio) of 2.0, and the evaluation was performed by changing the temperature under evaluation from room temperature (20 ° C.) to 100 ° C.

  As a result, it was found that both emission characteristics shown in FIGS. 6 and 7 do not depend on the evaluation temperature. In both emission characteristics, current began to flow from 4 to 5 V / μm or more, and no high dependence on each film forming condition was observed.

  Further, comparing FIGS. 6 and 7 with FIG. 5 shown above, the electron emission source formed by the electrophoresis method has a threshold voltage equal to that of the electron emission source formed by the spin coating method. It turned out to be an order of magnitude smaller. In the case of the spin coating method, since it spreads in a mixed state with the conductive polymer due to centrifugal force, there is no force for orienting CNTs in a certain direction. On the other hand, in the case of electrophoresis, since the CNT can freely move in the solvent, the CNT is easily aligned with its axial direction and drawn to the negative electrode, and as a result, an electron emission source with excellent orientation is formed. It is considered a thing.

  FIG. 8 is a graph showing a comparison between the emission characteristics of an electron emission source formed by electrophoresis and the emission characteristics of an electron emission source subjected to electric field treatment thereafter. The film forming conditions were voltage 100-film forming time 60 seconds and voltage 200 V-film forming time 5 seconds. When an electron emission source formed under the condition of voltage 100-deposition time 60 seconds is subjected to electric field treatment under the condition of voltage 200 V-electric field treatment time 30 seconds, the threshold voltage is about 5 V / μm to 2.5 V / μm. It turns out that it falls. Further, when an electron emission source formed under the condition of voltage 200−film formation time 5 seconds is subjected to electric field treatment under the condition of voltage 200V−electric field treatment time 60 seconds, the threshold voltage is about 3.5 V / μm to 2 V / It was found that the voltage dropped to a voltage lower than μm. From this result, it can be seen that the threshold voltage can be further reduced by performing the electric field treatment.

  FIG. 9 and FIG. 10 are graphs showing a comparison of emission characteristics of electron emission sources in which electric field treatment conditions applied after film formation by electrophoresis are changed. FIG. 9 shows a comparison between the condition of voltage 200 V—electric field treatment time 30 seconds and the condition of voltage 400 V—electric field treatment time 30 seconds. FIG. 10 shows a comparison between the condition of voltage 200 V—electric field treatment time 60 seconds and the condition of voltage 300 V—electric field treatment time 60 seconds.

  As is apparent from the graph shown in FIG. 9, the phenomenon that the threshold voltage decreases from about 5 V / μm to 2.5 V / μm by setting the voltage in the electric field treatment to 200 V is seen. It decreased only from about 5 V / μm to 3.2 V / μm. Further, as is apparent from the graph shown in FIG. 10, the phenomenon that the threshold voltage is lowered from about 4 V / μm to about 2.5 V / μm by setting the voltage in the electric field treatment to 200 V is seen. As a result, no increase in current density was observed even when the voltage was increased to 6.0 V / μm. From these results, it can be seen that if the voltage in the electric field treatment is increased too much, the improvement of the threshold voltage is lowered, and even the improvement of the threshold voltage cannot be seen depending on the conditions.

  When the emission characteristics were further investigated by changing the voltage in the electric field treatment, the threshold voltage was significantly improved by performing the electric field treatment applying a voltage in the range of 150 to 250V. In particular, it was found that the threshold voltage can be improved by setting the electric field treatment time to 30 to 60 seconds at a voltage of 200V.

  As mentioned above, although the Example of this invention was described, this invention is not limited to the said Example, It can implement with the form which gave various deformation | transformation.

  For example, the electrophoresis apparatus shown in FIG. 2 may have the form shown in FIG. In the apparatus shown in FIG. 11, an electrophoresis solution 32 similar to the previous electrophoresis solution 2 is placed in a cylindrical container 31, and a cylindrical electrode 33 and a rod-shaped electrode 34 are placed inside the cylindrical electrode 33. Inserted. The cylindrical electrode 33 and the rod-shaped electrode 34 are connected to the positive electrode and the negative electrode of the DC power source 36 by extending the wiring 35 from both sides.

  When a voltage is applied between the cylindrical electrode 33 and the rod-shaped electrode 34 in such a configuration, the CNT 37 and the conductive polymer 38 are attracted by the rod-shaped electrode 34 serving as a negative electrode, and the CNT 37 and the conductive polymer 38 are electrically As a result, a deposit mixed with the conductive polymer 38 is formed. Such a film forming process can be performed by changing the voltage of the DC power supply. Thus, by arranging the CNTs 37 around the rod-shaped electrode 34, a fluorescent tube capable of fluorescence at a low voltage with the rod-shaped electrode 34 provided therein can be produced.

  As the CNT 37, any of SWCNT and MWCNT can be adopted, and it is broadly interpreted as including ultra-fine CNTs having a diameter of 1 nanometer or less and CNTs of several nanometers to several tens of nanometers. Shall. Further, the CNT 37 can be manufactured by any method such as an arc discharge method, a laser ablation method, a plasma synthesis method, a chemical vapor deposition (CVD) method, or the like. However, CNTs produced by a CVD method advantageous for mass production are preferred.

  As the conductive polymer 38, any conductive polymer that is soluble in an organic solvent can be applied, but those belonging to a p-type semiconductor are particularly preferable. The introduced substituent is preferably a hydrocarbon group (such as an alkyl group). The alkyl group may be either a straight chain or a branched chain, but is preferably a hexyl group, a heptyl group, an octyl group, a nonyl group, or a decyl group. For example, polyvinylcarbazole, soluble polyparaphenylene vinylene (MEH-PPV (Poly [2-methoxy-5- (2'ethylhexyloxy) -1,4-phenylenevinylene]), soluble polyaniline, poly (alkyl) fluorene or poly (alkyl) In view of solubility and heat resistance, the length of the alkyl group is preferably in the range of 4 to 20 carbon atoms, particularly poly (3-octylthiophene) in which the alkyl group has 8 carbons. Alternatively, it is preferable to employ poly (3-hexylthiophene) composed of 6 carbons, and a plurality of the above conductive polymers may be used.

The present invention can be used for manufacturing an electron emission source such as an FED.

It is a figure which shows the manufacture process of an electron emission source using the carbon nanotube of this invention, and a polymer, and the flow of evaluation. It is a figure which shows the electrophoresis apparatus used in the present Example. It is a figure for demonstrating the method of the electric field process employ | adopted in the present Example. (A) is the figure which shows the condition which mounts the glass substrate removed from the electrophoresis apparatus on a silicon plate, (B) is a figure which respectively shows the condition which performs an electric field process. It is a figure for demonstrating the evaluation method of the film | membrane in this invention. (A) is a perspective view which shows the evaluation condition of a film | membrane, (B) is sectional drawing cut | disconnected by the XX line (dashed-dotted line) of (A), and was seen from the direction of arrow Y. It is a graph which shows the emission characteristic of the electron emission source formed into a film by the spin coat method as a comparison with the Example of this invention. In the Example of this invention, it is a graph which shows the emission characteristic of the electron emission source formed into a film by the electrophoresis method (voltage 200V, film-forming time 5 second). In the Example of this invention, it is a graph which shows the emission characteristic of the electron emission source formed into a film by the electrophoresis method (voltage 100V, film-forming time 60 seconds). In the Example of this invention, it is a graph which compares and shows the emission characteristic of the electron emission source formed into a film by the electrophoresis method, and the emission characteristic of the electron emission source which performed the electric field process after that. In the Example of this invention, it is a graph which compares and shows the emission characteristic of the electron emission source which changed the conditions of the electric field process performed after the film-forming by an electrophoresis method. FIG. 10 is a graph showing, in comparison with FIG. 9, emission characteristics of electron emission sources in which electric field treatment conditions applied after film formation by electrophoresis are changed in an example of the present invention. It is a figure which shows the electrophoresis apparatus used in another embodiment of this invention.

Claims (4)

A method of manufacturing an electron emission source that emits electrons by field emission,
Inserting an anode and a cathode connected to a power source into an organic solvent containing a conductive polymer and a carbon nanotube, and depositing the conductive polymer and the carbon nanotube on the cathode ;
After depositing the conductive polymer and the carbon nanotube, a step of performing an electric field treatment in which the cathode is pulled out of the solution and a voltage in the range of 150 to 250 V is applied between the cathode and the surface of the deposit. When,
A process for producing an electron emission source using carbon nanotubes and a polymer, characterized by comprising:   The conductive polymer is made of any one or more of polyvinyl carbazole, soluble polyparaphenylene vinylene, soluble polyaniline, poly (alkyl) fluorene, and poly (alkyl) thiophene. The manufacturing method of the electron emission source using the carbon nanotube and polymer which are described. The carbon nanotube and the polymer according to claim 1 or 2, wherein a weight ratio of the carbon nanotube to the conductive polymer contained in the organic solvent is 0.05 or more and 2 or less. The manufacturing method of the electron emission source. The method of manufacturing an electron emission source using carbon nanotubes and a polymer according to any one of claims 1 to 3, wherein the electric field treatment is performed at 200 V for 30 to 60 seconds.

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