CN102592918B - Post-processing method for improving field electron emission performance of carbon nano tube cathode - Google Patents
Post-processing method for improving field electron emission performance of carbon nano tube cathode Download PDFInfo
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- CN102592918B CN102592918B CN201210041775.4A CN201210041775A CN102592918B CN 102592918 B CN102592918 B CN 102592918B CN 201210041775 A CN201210041775 A CN 201210041775A CN 102592918 B CN102592918 B CN 102592918B
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Abstract
The invention discloses a post-processing method for improving field electron emission performance of a carbon nano tube cathode. After the post-processing of a magnetic field, the magnetism of a carbon nano tube on the cathode surface is polarized to carry out orientation, so that the carbon nano tube on the cathode surface is vertical to the surface of a substrate, the field electron emission performance of the carbon nano tube cathode can be obviously improved, particularly, the current density of a carbon nano tube film can be improved by one time, the threshold value strength is reduced by more than 30 %, the electron emission point density can be improved by more than one order of magnitude, and the uniformity is obviously improved. The post-processing method is simple and effective, can completely improve the field electron emission performance of the carbon nano tube cathode and has obvious economic and social benefits.
Description
Technical field
The present invention relates to a kind of post-processing approach that improves cathode field-induced electron emission performance of carbon nanometer tube, belong to Field Emission Display field.
Background technology
Carbon nano-tube, since 1991 are found, has become a study hotspot in material with carbon element field, is one of research field of physics, chemistry and material science forefront.Carbon nano-tube has unique quasi-one dimensional nanostructure, show the character such as special mechanics, electricity and magnetics, be expected to obtain application widely in various fields such as nano electron device, energy storage, a transmitting and flat panel display, conduction and electromagnetic shielding and structural reinforcings.
Among the numerous characteristics that have in carbon nano-tube, field emission performance is especially attracted attention.Utilize this performance, can prepare field emission cold-cathode material, be applied to the fields such as field-emission plane display (Field Emission Display, FED), field emission electron gun and field emission luminescence unit.
In field emission demonstration field, the preparation of carbon nanotube cathod be by silk screen print method, drip be coated with, revolve (spray) be coated with, soak draw, one in the several different methods such as self assembly, electrophoretic deposition forms carbon nano-tube film on underlayer electrode.Still there are some problems in these methods, as carbon nano tube surface exists defect more or less, the conduction of carbon nano-tube is bad, and electron emission poor stability, the shortcoming such as contact resistance is large, the life-span is short, suppressed the superior function of carbon nano-tube as cathode material.Therefore, just must carry out reprocessing to carbon nano-tube.Existing reprocessing scheme mainly contains: mechanical treatment, plasma treatment, electron beam treatment, colloid processing, electric field treatment, heat treatment etc., the field emission performance of raising carbon nano-tube.
The invention provides a kind of new carbon nano-tube post-processing approach, utilize the character of carbon nano-tube easy magnetization, by high-intensity magnetic field, carbon nano-tube is carried out to reprocessing, make it vertical orientated, draw ratio, density distribution, the factors such as surface is clean can be significantly improved, and then a threshold voltage for transmitting is obviously reduced, and emission uniformity significantly improves, and emission lifetime extends greatly.
Summary of the invention
The object of the present invention is to provide a kind of post-processing approach that improves cathode field-induced electron emission performance of carbon nanometer tube, make the current density of carbon nano-tube film improve 1 times, threshold intensity reduces more than 30%, electron emission dot density can improve 1 order of magnitude above and uniformity obviously improves, method of the present invention is simply effective, the field emission performance that comprehensively improves carbon nanotube cathod, possesses significant economic and social benefit.
For achieving the above object, the present invention adopts following technical scheme:
A kind of post-processing approach that improves cathode field-induced electron emission performance of carbon nanometer tube is to adopt the carbon nano-tube on high-intensity magnetic field target surface magnetize and be orientated, and makes surperficial carbon nano-tube perpendicular to substrate surface.
Described magnetic field is even or non-uniform magnetic-field, and magnetic field intensity is 1-10 T; Cathode surface and magnetic direction are perpendicular; Treatment temperature is 50-500 DEG C, and the processing time is 5-300 min; Processing atmosphere is air, N
2or any one or multiple mist in Ar.
Described carbon nano-tube by spraying, silk screen printing, electrophoretic deposition, spin coating, ink jet printing, brush or soak Tu and deposit.
Remarkable advantage of the present invention is: thus preparation method of the present invention erects more carbon nano-tube by carbon nanotube cathode material being carried out to magnetic field reprocessing, reduce the threshold field of carbon nano-tube, emission and electron emission dot density are improved, luminous efficiency and the uniformity of the field emission device of manufacturing are significantly improved compared with conventional cathode device, and it is convenient to process, cost is low, after processing, there is no residue on base material.
Brief description of the drawings
Fig. 1 is magnetic field reprocessing carbon nano-tube schematic diagram.
Fig. 2 is that the carbon nano-tube SEM through magnetic field reprocessing does not scheme.
Fig. 3 is the carbon nano-tube SEM figure through magnetic field reprocessing.
Fig. 4 is the I-V curve chart before and after carbon nanotube cathode arrays reprocessing.
Embodiment
Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiment are only not used in and limit the scope of the invention for the present invention is described.In addition should be understood that those skilled in the art can make various changes or amendment to the present invention after having read the content of the present invention's instruction, these equivalent form of values fall within the application's appended claims limited range equally.
Embodiment 1
A kind of carbon nano-tube post-processing approach that improves field emission performance of the present invention, shifts carbon nano-tube as example taking electrophoretic deposition, comprising: the preliminary treatment to carbon nano-tube, the configuration of carbon nano-tube electrophoretic liquid, electrophoresis, sintering and reprocessing.
1)the preliminary treatment of carbon nano-tube
Carbon nano-tube is carried out to Ultrasonic Pulverization processing, reach the effect that shortization disperseed, after filtration, deionized water rinsing, add aqueous isopropanol and neopelex additive, carry out ultrasonic dispersion, filter again, dry.
2) configuration of carbon nano-tube electrophoretic liquid
The carbon nano-tube of oven dry is inserted in organic solvent, and organic solvent can be methyl alcohol, ethanol, isopropyl alcohol, acetone etc., adds carrier ion, as magnesium nitrate (Mg (NO
3)
2), aluminum nitrate (Al (NO
3)
3), indium nitrate (In (NO
3)
3), silver nitrate (AgNO
3) etc. salt electrolyte, taking magnesium nitrate as example, Mg
2+general 1.0 mmol/L of concentration, the electrophoresis configuring also, under ultrasonic machine, ultrasonic 4～5 hours, obtains the carbon nano-tube electrophoretic liquid fully disperseing.
3)the electrophoresis of carbon nano-tube
The electrophoresis of carbon nano-tube adopts straight flow electrophoresis, cathode-anode plate spacing 700 μ m, electrophoretic current 4mA, electrophoresis time 9min.Electrophoretic voltage scope is between 3 ~ 8V.
4)the dry processing of carbon nano-tube
First print good electrophoresis is dried to 0.5～1.5 hour in 80 DEG C of constant temperature ovens, the impurity components such as evaporative removal part organic solvent.
Also can adopt other technology generations for electrophoretic deposition, carbon nano-tube is transferred on electrode surface, for example spraying process, dip coating, silk screen printing, ink jet printing, spin coating, brushing or other can be transferred to carbon nano-tube the technology on base material.
5)the reprocessing of carbon nano-tube
The present invention carries out reprocessing by high-intensity magnetic field to carbon nano-tube material, principle is that carbon nano-tube has anisotropic magnetic susceptibility, and the carbon nano-tube minimum energy direction of metallicity and semiconductive will be parallel to the direction in additional magnetic field, so under the effect of high-intensity magnetic field, carbon nano tube surface is magnetized, thereby make more carbon nano-tube under the attracting each other of magnetic force, out exposed, keep the orientation of height, electronics just can be from these height-oriented carbon nano-tube electron emissions like this, so just improve field emission performance, and report according to pertinent literature, the more carbon nano-pipe array alignment of cathode surface, can increase substantially field emission performance.The aftertreatment technology of carbon nano-tube is: at N
2in atmosphere, magnetic field intensity 3 T, 300～400 DEG C of temperature, processing time 30～40min.As shown in Figure 1.
Embodiment 2
The carbon nano-tube emitting cathode that embodiment 2 is secondary structure.Get the carbon nano-tube of 0.03g, add the acetone solvent of 300ml, pulverize after four hours at ultrasonic disintegrating machine, filter, after deionized water rinsing, then add the isopropanol solvent of 300ml, and add on a small quantity neopelex additive, carry out ultrasonic dispersion, after ultrasonic 24 hours, filter again, clean and dry.
The carbon nano-tube of oven dry is inserted in the isopropanol solvent of 300ml, added a certain amount of aluminum nitrate (Al (NO
3)
3), make Al
3+general 1.0 mmol/L of concentration, the electrophoresis configuring also, under ultrasonic machine, ultrasonic 4～5 hours, obtains the carbon nano-tube electrophoretic liquid fully disperseing.
The electrophoresis of carbon nano-tube adopts straight flow electrophoresis, and print size is 10cm × 10cm, cathode-anode plate spacing 700 μ m, constant electrophoretic current 4mA, electrophoresis time 9min.Electrophoretic voltage scope is between 3 ~ 8V.
First by print good electrophoresis dry 30～90 min in 100 DEG C of constant temperature ovens, the impurity components such as evaporative removal organic solvent.
Dried print is inserted to airborne high-intensity magnetic field, print vertical magnetic field direction, magnetic field intensity 6 T, print temperature 60 C, processes after 4s, takes out print, places after 4s, then print is inserted in high-intensity magnetic field to repetitive operation 60 times.
Be 0.73 V/ μ m by the unlatching electric field of the carbon nanotube cathod of the inventive method processing, reduced 30%(1.05 V/ μ than the carbon nanotube cathod that does not pass through any processing under identical electric field strength m) many, electron emission current density and emission uniformity are all significantly improved.
Embodiment 3
The carbon nano-tube emitting cathode that second embodiment of the present invention is normal-gate structure, preliminary treatment, deposition condition and the last handling process of carbon nano-tube are identical with embodiment 2, difference is, the structure of minus plate is normal-gate, and carbon nano-tube electrophoretic is on negative electrode.
Embodiment 4
The 3rd embodiment of the present invention is the carbon nanotube field emission cathode of rear grid structure, preliminary treatment, deposition condition and the last handling process of carbon nano-tube are identical with embodiment 2, difference is, the structure of minus plate is normal-gate, and carbon nano-tube electrophoretic is on negative electrode.
The foregoing is only preferred embodiment of the present invention, all equalizations of doing according to the present patent application the scope of the claims change and modify, and all should belong to covering scope of the present invention.
Claims (2)
1. one kind is improved the post-processing approach of cathode field-induced electron emission performance of carbon nanometer tube, it is characterized in that: described post-processing approach is to adopt the carbon nano-tube on high-intensity magnetic field target surface magnetize and be orientated, and makes surperficial carbon nano-tube perpendicular to substrate surface;
Described magnetic field is even or non-uniform magnetic-field, and magnetic field intensity is 1-10 T; Cathode surface and magnetic direction are perpendicular; Treatment temperature is 50-500 DEG C, and the processing time is 5-300 min; Processing atmosphere is air, N
2or any one or multiple mist in Ar.
2. the post-processing approach of raising cathode field-induced electron emission performance of carbon nanometer tube according to claim 1, is characterized in that: described carbon nano-tube by spraying, silk screen printing, electrophoretic deposition, spin coating, ink jet printing, brush or soak Tu and deposit.
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6902658B2 (en) * | 2001-12-18 | 2005-06-07 | Motorola, Inc. | FED cathode structure using electrophoretic deposition and method of fabrication |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6902658B2 (en) * | 2001-12-18 | 2005-06-07 | Motorola, Inc. | FED cathode structure using electrophoretic deposition and method of fabrication |
Non-Patent Citations (2)
| Title |
|---|
| 涂敷法制备碳纳米管场发射阴极的研究;王琪琨;《第八届中国场致发射与真空微电子学学术会议论文集》;20031208;第114页28-31行、第115页10行 * |
| 王琪琨.涂敷法制备碳纳米管场发射阴极的研究.《第八届中国场致发射与真空微电子学学术会议论文集》.2003,第114页28-31行、第115页10行. |
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