CN101410927B - Field emission devices made with laser and/or plasma treated carbon nanotube mats, films or inks - Google Patents
Field emission devices made with laser and/or plasma treated carbon nanotube mats, films or inks Download PDFInfo
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- CN101410927B CN101410927B CN2004800253870A CN200480025387A CN101410927B CN 101410927 B CN101410927 B CN 101410927B CN 2004800253870 A CN2004800253870 A CN 2004800253870A CN 200480025387 A CN200480025387 A CN 200480025387A CN 101410927 B CN101410927 B CN 101410927B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
- B01J19/12—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electromagnetic waves
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y10/00—Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/04—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of carbon-silicon compounds, carbon or silicon
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
- H01J1/02—Main electrodes
- H01J1/30—Cold cathodes, e.g. field-emissive cathode
- H01J1/304—Field-emissive cathodes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
- H01J9/02—Manufacture of electrodes or electrode systems
- H01J9/022—Manufacture of electrodes or electrode systems of cold cathodes
- H01J9/025—Manufacture of electrodes or electrode systems of cold cathodes of field emission cathodes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2201/00—Electrodes common to discharge tubes
- H01J2201/30—Cold cathodes
- H01J2201/304—Field emission cathodes
- H01J2201/30446—Field emission cathodes characterised by the emitter material
- H01J2201/30453—Carbon types
- H01J2201/30469—Carbon nanotubes (CNTs)
Abstract
Field emission devices comprising carbon nanotube mats which have been treated with laser or plasma are provided. Mats are formed from carbon nanotubes, also known as carbon fibrils, which are vermicular carbon deposits having diameters of less than about one micron. The carbon nanotube mats are then subjected to laser or plasma treatment. The treated carbon nanotube mat results in improved field emission performance as either a field emission cathode or as part of a field emission device.
Description
Related application
The application requires the U.S. Provisional Patent Application No.60/485 of submission on July 9th, 2003,918 rights and interests.The application also is the part continuation application of the PCT/US03/19068 of submission on June 16th, 2003, and this application requires the U.S. Provisional Patent Application No.60/388 of submission on June 14th, 2002,616 rights and interests.The application also is the U.S.S.N.10/171 that submitted on June 14th, 2002,760 part continuation application, and this application requires the U.S. Provisional Patent Application No.60/298 of submission on June 14 calendar year 2001,193 rights and interests.The application also is the U.S.S.N.10/171 that submitted on June 14th, 2002,773 part continuation application, and this application requires the U.S. Provisional Patent Application No.60/298 of submission on June 14 calendar year 2001,228 rights and interests.
Technical field
The present invention relates to by or the field emission apparatus or the field-transmitting cathode that utilize laser or plasma treated carbon nanotube mats, film or printing ink to make.
Background technology
Field emission apparatus
Field emission apparatus is the device that electron motion is used.Typical field emission apparatus comprise at least negative electrode, emitter tip and with negative electrode anode separately.Thereby applying voltage between negative electrode and anode makes electronics launch from emitter tip.Electronics moves along the direction from the negative electrode to the anode.These devices can be used in the multiple application, and this includes but not limited to microwave vacuum pipe unit, power amplifier, ion gun, high energy acclerator, free electron laser and electron microscope, and flat-panel monitor particularly.Flat-panel monitor can be used as substituting of conventional cathode ray tube.Therefore, they can be used in television set and the computer monitor.
Traditional emitter tip utilize metal for example molybdenum or semiconductor for example silicon make.It is higher that the problem at metallic radiator tip is to be used to launch required control voltage, for example about 100V.And these emitter tips lack uniformity, thereby cause the current density between the pixel inhomogeneous.
Recently, material with carbon element has been used as emitter tip.Diamond has negative or low electron affinity on its hydrogen end face.But diamond tip has graphited trend under the emission current that strengthens, particularly at about 30 mA/cm
2Electric current under.Carbon nano-tube is also referred to as the carbon microfilament and is the latest developments in the emitter tip technology.Though in the lift-off technology on the scene with carbon nano-tube as having made a lot of work in the field of emitter tip, in three fields, still need remarkable improvement at least.They are to reduce operating voltage (specific to concrete application), reduce " unlatching " voltage, raising emission, and the number at increase emission position.Reduce " unlatchings " voltage (and operating voltage) help to improve the electronics emission between easy life-span of property and raising emitter tip.The number that improves emission current and emission position simultaneously can highlight.The emission position that number increases may cause forming emission more uniformly by given area or volume.
Carbon nano-tube
Carbon nano-tube (CNT) is to have the vermiform carbon deposits that is lower than about 1 micron diameter.They exist in a variety of forms, and utilize wherein solid carbon is utilized simultaneously and graphite rod and transition metal are carried out laser vaporization prepared by various carbonaceous gass are carried out catalytic decomposition on the metal surface as the high temperature carbon arc process of carbon base feed.The U.S. Patent No. 4,663,230 of authorizing Tennent successfully grows the nanotube of minor diameter, this nanotube have the graphite core of cylindrical arrangement and be not subjected to being arranged in of pyrolysis carbon contamination " as grow " graphite surface.Tennent has described and has not contained continuous hot carbon coating and have the outer field carbon nano-tube of a plurality of graphite that is basically parallel to the microfilament axis.Therefore, their feature can be described to, and makes its c axle perpendicular to graphite lth layer tangent line be basically perpendicular to their cylinder axis.They have diameter that is not more than 0.1 micron and the length diameter ratio that is at least five usually.U.S. Patent No. 5 people such as people's such as Tennent U.S. Patent No. 5,165,909 and Tennent, 171, in 560, described and had graphite linings and this nanotube of diameter between 3.5 to 75 nanometers that is basically parallel to the microfilament axis, by reference they all have been combined in here.
Graphite plane also can be angled with the microfilament axis orientation.Because the two-dimentional projection outward appearance on this plane, this structure is commonly referred to " fish-bone " microfilament or nanotube.In the U.S. Patent No. 4,855,091 of authorizing Geus, disclose and be used to make their method and such form, by reference this patent has been combined in here.Half is 10 to 500nm for the diameter of fishbone microfilament, preferably from 50 to 200nm and have a aspect ratio 10 and 1000.
In people's such as Tennent U.S. Patent No. 5,691,054, described macroscopical aggregation and the composite material that constitutes by many walls nanotube, by reference this patent has been combined in here.The carbon microfilament of the random orientation of physical characteristic constitutes by having evenly at least two dimensions for this aggregation and composite material.This macroscopical aggregation and " as manufacturing " polymeric difference are they are formed the ability of any ideal dimensions.Preferably, this condensate has at least one greater than 1mm and be preferably greater than the dimension of 1cm.This aggregation can present the form of the pad or the felt of two-dimentional constant entropy.
In U.S. Patent No. 4,663,230,5,165,909 and 5, in 171,560 disclosed carbon nano-tube can have scope from about 3.5nm to 70nm diameter and greater than 100 times length of diameter, and the perimeter and the significant internal core zone of arranging a plurality of basic pantostrats of carbon atom.And these multi-walled carbon nano-tubes do not contain the carbon of pyrolytic deposition substantially.All these are with reference to all being combined in here by reference.
As in U.S. Patent No. 5,110,693 and citing document wherein (by reference they all being combined in here) in disclosed, two or more independent carbon microfilaments can form the microcosmic condensate of entanglement microfilament.Only be the purpose of signal, the axle or the bar of the similar entanglement microfilament of one type microcosmic condensate (" cotton candy or CC "), its diameter can change from 5nm to 20nm, and length can change to 1000 μ m from 0.1 μ m.Be the purpose of signal once more, the microcosmic microfilament condensate of another kind of type (" Bird's Nest or BN ") is roughly spherical, and its diameter can change to 1000 μ m from 0.1 μ m.Can form the bigger condensate of every type (CC and/or BN) or every type mixture.
Produced carbon nano-tube with the single wall that constitutes single graphite flake.U.S. Patent No. 5,424,054 people such as Bethune; People's such as Guo Chem.Physics Lett., 243:1-12 (1995); People's such as Thess Science, 273:483-487 (1996); People's such as Journet Nature 388 (1997) 756; Among people's such as Vigolo the Science 290 (2000) 1331 these Single Walled Carbon Nanotube have been described.Be called the U.S. Patent application No.08/687 of " Ropes ofSingle-Walled Carbon Nanotubes (Single Walled Carbon Nanotube rope) " in the name that is combined in by reference here, also they be described in 665.Single-walled nanotube can prepare by various procedures.They can use the solid-state carbon source of utilizing electric arc or laser vaporization.Optional and preferably, single-walled nanotube is utilized gas-phase carbon precursor catalysis manufacturing.This catalysis is synthetic to have two kinds of main method: so-called aerosol or suspension catalytic process, this process is used and be decomposed into the gas phase catalyst precursor of catalytic specie in reaction zone, and uses traditional catalyst-loaded process.The aerosol process can advantageously be used the high pressure up to 100atm.Catalyst-loaded process is carried out under atmospheric pressure and even can be carried out in a vacuum.Preferred gas phase carbon source is CO, CH4, ethanol and benzene.Preferred temperature is between 500 and 1000 ℃.
Apply for that at the PCT that is combined in by reference here No.PCT/US99/25702 and PCT apply for having described among the No.PCT/US98/16071 method of other production single-walled nanotube.Single-walled nanotube can be used in the multiple application.Tubular structure has been given good intensity, low weight, stability, flexible, heat conductivity, big surface area and a variety of characteristic electron.They can be used as reinforcing material in fibre-reinforced composite structure or hybrid composite structure promptly also contain the composite material of reinforcing material such as continuous fiber for example except single-walled nanotube.Carbon nano-tube can they as made form in handle or can in suitable substrate, be deposited as film and handle then.All these are with reference to all being combined in here by reference.
Nanotube deposition technology-(receive at Electrophoretic Deposition of Nanotubes The electrophoretic deposition of mitron) open in(, by reference this patent application being combined in here) from U.S. Patent application Pub.2003/0090190
Electrophoresis tank
Can in electrophoresis tank, carry out the electrophoretic deposition of carbon nano-tube.This groove comprises and is used to hold the chamber of carbon nano-tube solution and is used for separately the parts of two comparative electrodes at a certain distance of the carbon nano-tube submergence between the comparative electrode.Use applies voltage between the DC of electrophoresis tank outside power supply is being immersed in two electrodes in the electrophoresis tank.Cathode leg is connected to the aluminium matter substrate of patterning, and anode tap is connected to another electrode.Tantalum is used for second metal.The voltage that is applied to two electrodes can be adjusted to suitable level, perhaps can regulate this voltage to obtain suitable electric current between two electrodes.Can utilize binding agent to strengthen the connection of carbon nano-tube to aluminium.This binding agent can be the mixture of Ag cream, carbon nano-tube and ethanol.Perhaps but this binding agent can be conduction carbon paste, conductive metal paste or a carbonized polymers.
Electrophoresis deposition of carbon nanotubes in substrate
The field emission device substrate is added in the electrophoresis tank.A plurality of negative electrodes are set on substrate of glass, and on negative electrode, form dielectric film with hole.Formation is positioned at the metal gate with opening on the hole of dielectric film so that expose the surface of negative electrode.Then, at room temperature utilize electrophoretic deposition on the cathode surface that exposes by these holes with even carbon nanotube deposit in the substrate that is obtained.
Heat treatment after deposition
After the particle that utilizes the electrophoretic deposition carbon nano-tube, carry out low-temperature heat so that keep the deposition of carbon nano-tube on negative electrode, and guarantee easily to remove the impurity that mixes in the field emission device depositing therebetween.
In the substrate of aluminium matter, prepare nanotube films (among the U.S. Patent application Pub.2003/0090190
An example, this patent application is combined in here by reference)
With reference to Figure 17, form the solution of the acid-washed carbon nanotube of the isopropyl alcohol (IPA) contain 150ml and 0.44g.This solution is placed electrophoresis tank 5000.
The aluminized coating substrate of glass 5002 of patterning is as an electrode in the electrophoresis tank 5000.This pattern forms Pixel Dimensions.Minimum characteristic size can be about 1 micron.The size of aluminized coating substrate of glass 5002 is approximately 55mm. * 45mm. * 1mm.The size of aluminium matter pattern is approximately 9mm * 9mm.Another electrode is that tantalum (Ta) electrode 5004 also inserts in the electrophoresis tank 5000.Distance piece 5006 is spaced apart from tantalum electrode 5004 with aluminized coating substrate of glass 5002.For example apply between 40 to 120V for example dc voltage of 100V to electrode.Observing between 1.0 to 5mA for example electric current of 3.8mA between the electrode.The length of preparation time can be at about 30 between about 90 minutes for example 60 minutes.
Figure 18 has illustrated according to the optional electrophoresis method of disclosed method produced film in the UK Patent Application 2,353,138 that is described below.At first, generate carbon nano tube suspension.Carbon nanotube particulate can have from about 0.1 to about 1000 microns length.This suspension also can contain surfactant for example anion, ion, both sexes or nonionic or other activating agent well known in the art.The example of suitable activating agent comprises hot benzene glycan, succinate sodium 2-ethylhexyl and Mg (OH)
2, Al (OH)
3And La (OH)
3Nitrate.
Apply electric field for suspension then so that be the carbon nanotube particulate charging.Electric field strength and the time that applies electric field have been determined the thickness of carbon nanotube layer.Bigger intensity and longer time will produce thicker layer.
With reference to Figure 18, field emission device substrate 6030 is inserted in the electrophoresis tank 6000 that contains carbon nano tube suspension 6010.Also battery lead plate 6020 is installed in the electrophoresis tank 6000, makes itself and field emission device substrate 6030 separately.The negative electrode of the DC power supply of installing in the outside of electrophoresis tank 6,000 6040 is connected to other negative electrode of field emission device substrate 6030, and the anode of DC power supply 6040 is connected to battery lead plate 6020.Then, between the negative electrode of battery lead plate 6020 and field emission device substrate 6030, apply about bias voltage of 1 to about 1000V from DC power supply 6040.
When the positive voltage of DC power supply 6040 imposes on battery lead plate 6020, carbon nanotube particulate by the charging of the cation in the carbon nano tube suspension 6010 is moved to and is depended on the exposure negative electrode of field emission device substrate 6030, and this causes forming carbon nano-tube film on the negative electrode pattern that exposes.
The height of the carbon nano-tube film (being also referred to as printing ink, coating or cream) of printing may be less than 10 microns, and carbon nanotube cathod is approximately 125 microns from the isolated space of the indium-tin oxide anode with tin indium oxide and phosphor.
This electrophoresis process can be applied to diode and triode.For the application in diode, apply the electric field of its electric charge and the lip-deep opposite charge of carbon nanotube particulate to the exposed electrode surface of field emission device substrate, so that deposition of carbon nanotubes particle optionally thereon.For the application in having the triode of grid, apply weak positive electric field to grid, the electrode to the field emission device substrate applies positive electric field simultaneously, and this can be avoided deposition of carbon nanotubes particle on grid.Particularly, the battery lead plate negative electrode that is connected to the anode of DC power supply and field emission device substrate is connected to the negative electrode of DC power supply.When grid applies positive potential, this grid repels the cation in the carbon nano tube suspension in the surface, and the exposure negative electrode that is connected to the field emission device substrate of DC power cathode will attract the cation of suspension to pass aperture.As a result, carbon nano-tube only is deposited on the whole exposed surface of negative electrode, and can not deposit on the grid of field emission device substrate.At this moment, that carbon nanotube particulate attracted to field emission device substrate and basic horizontal or be basically parallel to substrate and carry out orientation, this makes carbon nanotube particulate move to negative electrode by aperture smoothly, and therefore can deposition of carbon nanotubes.
Also can be similar at European patent application EP 1 020 888 A1-Carbon ink, electron-emitting element, the disclosed carbon ink of method for manufacturing and electron-emitting element and image display device (Al-carbon printing ink, electronic emission element, be used for making the method for electronic emission element and image display device) prepares film like that.
Summary of the invention
According to an embodiment, provide a kind of field emission apparatus.This device has negative electrode and anode.This negative electrode comprises carbon nanotube mats, and wherein this carbon nanotube mats utilizes filter cake production, by forming this filter cake from a plurality of nanotubes of the suspension filtered of liquid.This pad can have top surface and relative basal surface.During pad formed, this basal surface was corresponding to the filter cake surface that is provided with near filter.This top surface can be used as the emitting surface of negative electrode.
These a plurality of nanotubes can have less than about 1 micron diameter.
These a plurality of nanotubes can have the form of similar fish-bone.These a plurality of nanotubes can be walls single wall or many.This nanotube can be oxidized; They can be crosslinked.This filter cake can form when having binding agent.This binding agent can be can be by the fluoropolymer of dissolution with solvents in one embodiment.It can be PVDF.
The field-transmitting cathode that comprises carbon nanotube mats is provided, and this pad utilizes filter cake production, by forming this filter cake from a plurality of nanotubes of the suspension filtered of liquid.
Also provide field-transmitting cathode that a kind of processing comprises nanotube to improve the method for cut-in voltage.This method comprises radiation target irradiation adequate time and the intensity of utilizing suitable wavelength.This radiation can be in the ultraviolet range.When irradiation, this negative electrode can be exposed to laser continuous or pulse.This radiation can have the wavelength that is lower than about 349nm.This radiation can have and is higher than about 10.3mJ/cm
2Energy density.Can in air or in the oxygen partial pressure of at least 1 holder, shine.Negative electrode can be made of carbon nanotube mats.The field-transmitting cathode of irradiation by this way also is provided.
As further embodiment, provide field-transmitting cathode that a kind of processing comprises nanotube to improve the method for cathode emission current density.The method that the field-transmitting cathode that comprises nanotube is launched the number at position with increase and passed through the emission uniformity of negative electrode of handling also is provided.These methods comprise the UV irradiation and are exposed to low temperature plasma.
Provide a kind of and in structure nanotube is carried out directed method, this method comprises this structured illumination adequate time and intensity.Provide a kind of and in structure nanotube is carried out directed method, this method comprises under suitable condition this structure is exposed to low temperature plasma.
In another embodiment, a kind of field emission apparatus is provided, it has a plurality of basic columniform nanotubes that are, these nanotubes have one or more graphite linings concentric with their cylinder axis, these nanotubes do not contain the carbon coating of pyrolytic deposition substantially, have between 0.4nm and the 100nm basic diameter uniformly and greater than 5 length diameter ratio.
Description of drawings
Fig. 1 is to have illustrated the carbon nano-tube of electrophoretic deposition, the carbon nano-tube of silk screen printing and the electronics emission behavior of carbon nanotube mats as the form of the curve chart of the current density of electric field function.
Fig. 2 is the serial-gram of the electronics emission pattern of the carbon nano-tube of carbon nano-tube, silk screen printing of electrophoretic deposition and carbon nanotube mats.
Fig. 3 is according to the carrying out of an embodiment and does not carry out the comparative graph of the emission of the silk screen printing carbon nanotube cathod that argon plasma handles to electric field (I-V characteristic).
Fig. 4 illustrates the contrast of emission pattern, shows according to an embodiment to have realized the number at emission position and the increase of this two aspect of emission by the argon plasma processing.
Fig. 5 is according to another embodiment contrast between the SEM microphoto of carbon nano-tube form before plasma treatment causes change in orientation and afterwards.
Fig. 6 is the comparative graph of the emission of the top of the CNT pad negative electrode made according to the various binding agents of utilizing of an embodiment and lower surface to electric field (I-V characteristic).
Fig. 7 be according to the top that utilizes the CNT pad negative electrode that binding agent makes of another embodiment and lower surface before shining and emission afterwards to the comparative graph of electric field (I-V characteristic).
Fig. 8 has illustrated the contrast of emission pattern, shows according to another embodiment to have realized launching this increase aspect two of the number at position and emission the UV laser radiation after in the CNT pad.
Fig. 9 be silk screen printing CNT negative electrode according to another embodiment before being exposed to different illumination levels and emission afterwards to the comparative graph of electric field (I-V characteristic).
Figure 10 has illustrated the contrast of emission pattern, shows according to another embodiment to have realized launching this increase aspect two of the number at position and emission the UV laser radiation after in CNT silk screen printing negative electrode.
Figure 11 be according to another embodiment laser radiation handle cause change in orientation before and the contrast between the SEM microphoto of carbon nano-tube form afterwards.
Figure 12 is the contrast according to embodiment emission of acquisition after utilizing the different wave length irradiation.
Figure 13 is the contrast that utilizes the emission that obtains after the different wave length irradiation according to an embodiment in different irradiation environment (air and vacuum).
Figure 14 illustrates according to another embodiment before irradiation and the contrast of the emission of the silk screen printing top of the pad CNT negative electrode that obtains afterwards and lower surface.
Figure 15 is according to the contrast between the SEM microphoto of the top of another embodiment CNT pad after the laser radiation processing causes change in orientation and the carbon nano-tube form on the lower surface.
Figure 16 has illustrated the contrast of emission pattern, shows according to another embodiment to have realized launching this increase aspect two of the number at position and emission the UV laser radiation after in CNT pad negative electrode.
Figure 17 has illustrated to be used to make the electrophoresis tank of carbon nano-tube film (electrode).
Figure 18 has illustrated to be used to make the another kind of electrophoresis tank of carbon nano-tube film (electrode).
Embodiment
The patent of all references, patent application and public publication in specification comprise institute
Attached list of references all is combined in here by quoting here.
Definition
" condensate " refers to the microcosmic particle structure of nanotube.
" aggregation " refers to along the axis of at least one dimension to have relatively or basic physical characteristic uniformly, and has relative or basic physical characteristic uniformly ideally in the one or more planes in aggregation, the nano tube structure that promptly in this plane, has the isotropism physical property.Aggregation can comprise each interconnective nanotube or a lot of nanotube condensate that links to each other of uniformly dispersing.In other embodiments, whole aggregation is relative or isotropic substantially about the one or more of its physical characteristic.
" carbon microfilament base oil China ink " refers to the conducting liquid composite material, and conductive filler wherein is the carbon microfilament.
" two-dimentional carbon atom sheet (graphenic) " carbon is a kind of form of carbon, and its each carbon atom all is connected to three other carbon atoms in forming the basic layer for planar shaped of hexagon coupling collar.These layers are the small pieces that only have seldom several rings in their diameter, perhaps have a lot of rings still only have seldom several rings in their width band in their length.
" two-dimentional carbon atom sheet analog " refers to the structure that is combined in the two-dimentional carbon atom sheet surface.
" graphite " carbon is made of the layer that mutual substantially parallel and spacing is no more than 3.6 dusts.
" low temperature plasma " but refer to abundant ionization so that can conduct electricity still and to be electroneutral gas system, wherein electronics is in than under the higher temperature of molecule.See Baddour, R.F.andTimmins, R.S.eds,
The Application of Plasmas to Chemical Processing (plasma is to chemically treated application)MIT publishes, Cambridge MA 1967.
The use " nanotube ", " nanofiber " and " microfilament " and " CNT " that exchange.Each all refers to a kind of elongated hollow carbon structure, and this structure has the diameter less than 1 micron.Term " nanotube " also comprises " Baji-tube " and gnf, and wherein two-dimentional carbon atom plate plane is with catfish bone or fish-bone pattern orientation.
Term " emitter tip " and " reflector " can exchange.Use word " tip " and do not mean that the tip that the electronics emission only is confined to carbon nano-tube.Electronics can be from any part emission of carbon nano-tube.
Manufacture method
Except electrophoresis method (describing in the superincumbent background technology part), other method for example silk screen printing also can be used for forming the pattern of making the field emission apparatus use.Screen printing technique is in U.S. Patent No. 6,239, and is open in 547.Except silk screen printing, can carbon nano-tube be applied to substrate by ink jet printing.Utilization is finished ink jet printing based on the liquid medium or the printing ink of carbon nano-tube, and wherein microfilament is almost by individual.Printing ink generally contains carrier fluid, carbon nano-tube, and also contains polymeric binder usually.Useful binding agent comprises VAGH, VAGF, cellulose acetate-butyrate, ethyl cellulose, crosslinkable polymer and acrylate polymer.They can exist with 1 to 7wt% scope of printing ink.This liquid support can be a polar organic solvent, preferably boils between 150 ℃ and 200 ℃.
Printing ink can be dried (promptly evaporating carrier fluid) to form patterned coating.In the PCT/US03/19068 that is combined in by reference here, more fully printing ink is described.According to designed printing process, printing ink can have 1 and 50, the viscosity between the 000cps.Available carbon nano-tube addition from 0.5 to 2.5wt%.
The CNT pad
The form deposition that carbon nano-tube can also be filled up.This have 0.10 and 0.40gm/cc between density and can be greater than the porous pad of the surface area of 100sq.m/gm easily by nanotube suspension is filtered formation.In U.S. Patent No. 6,099, this method is more fully disclosed in 965 and 6,031,711, this patent all is combined in here by reference.If supply with nanotube, before making pad, need not fully that nanotube is individual with polymeric form.As a simple example, use Waring blender to prepare nanotube suspension, this suspension contains about 0.5% nanotube in water.Be diluted to after 0.1% subsequently, using probe-type sound wave processor dispersing nanometer pipe further.Then this dispersion is carried out vacuum filtration and fill up, and dry then to form.This causes forming the filter cake with top and lower surface.When successfully making pad, the filtering material that originally adheres on the lower surface is stripped from.The nanotube of oxidation especially is easy to be scattered in the aqueous medium and from it filter.
Can as described in aforementioned patent, apply rigidization or cross-linking step to these pads.Can in air, under up to 300 ℃ temperature, utilize the microfilament pad rigidization of heat treatment with oxidation.Optionally, can in oxygen-free atmosphere, under up to 600 ℃ temperature, utilize heat treatment will fill up rigidization.CNT pad negative electrode has uniform emission position under the lower electric field that is applied, and can obtain to be higher than 10mA/cm
2Current density.In Fig. 1, shown the contrast of the electronics emission behavior of the carbon nano-tube of carbon nano-tube, silk screen printing of electrophoretic deposition and carbon nanotube mats with form as the curve chart of the current density of electric field function.Fig. 2 has shown the further contrast of the electronics emission pattern of the carbon nano-tube of carbon nano-tube to electrophoretic deposition, silk screen printing and carbon nanotube mats.
Also can use various types of binding agents to produce CNT pad negative electrode.Useful binding agent comprises that cellulose, carbohydrate, polyethylene, polystyrene, nylon, polyurethane, polyester, polyamide, phenolic resins and any other produce the binding agent of carbon when pyrolysis.High-temperature decomposition temperature depends on employed binding agent, but can be in air up to 300 ℃ or in oxygen-free environment up to 900 ℃.But must not carry out pyrolysis to binding agent.Can in the solvent that contains microfilament suspension, dissolve, and be used for polymeric binder that the non-solvent of this polymer separates out by interpolation then and can be used for filtration by subsequently to form pad.PVDF is an example of this polymer.
Plasma treatment
In a preferred embodiment, carbon nano-tube or carbon nanotube mats are implemented plasma treatment.In a further advantageous embodiment, the screen printing ink that contains carbon nano-tube is implemented plasma treatment.Optionally, field-transmitting cathode or field emission apparatus itself are implemented plasma treatment.Plasma treatment forms improved field emission performance for carbon nanotube mats or printing ink, and causes forming better field-transmitting cathode or field emission apparatus thus.
Implement plasma treatment and be in order to change the surface characteristic of carbon microfilament, microfilament structure and/or matrix, they contact with plasma during handling; Utilize the handled microfilament composite material of this method can be functionalized or as desired the change.In case possess the instruction here, those of ordinary skills can adapt to and utilize well-known plasma treatment technology so that this composite material is handled.Therefore, can in suitable reaction vessel, under suitable pressure and other condition and in the suitable duration, implement this processing, so that the modification that produces plasma, makes it contact composite material and realize desired type and degree.For example can utilize those based on the plasma of oxygen, hydrogen, ammonia, helium or other chemically reactive gas or inert gas.
The example that is used to produce other gas of plasma comprises argon gas, water, nitrogen, ethene, carbon tetrafluoride, sulphur hexafluoride, perfluoroethylene, fluoroform, dichlorodifluoromethane, bromotrifluoro-methane, trifluorochloromethane etc.Can produce plasma from the mixture of pure gas or two or more gases.Advantageously, composite material is exposed to more than one type plasma.Also advantageously, continuous several times composite material is exposed to plasma; The duration that is used to produce between the condition of plasma, this processed continuously duration and this continuous processing also can be changed, to realize specific variation in material.Can also between handling continuously, handle, for example utilize a kind of material to apply this material, wash the surface of this material etc. composite material.
The plasma treatment of composite material can cause some variations.For example, comprise that polymer and the composite material that intersperses among a plurality of carbon microfilaments wherein can be exposed to plasma.Being exposed to plasma can this polymer of etching and on the surface of composite material the carbon microfilament is come out, and increases the surface area of the carbon microfilament that exposes thus, for example makes the surface area of the microfilament that exposes greater than the geometric jacquard patterning unit surface area of composite material.Also can discharge the end or the segment of the nanotube that has been aggregated thing and is fettered to the etching of polymer, make them move or be redirected.Be exposed to plasma and can on microfilament or polymer, introduce chemical functional group.Can be on each microfilament and on microfilament structure example such as condensate, pad, hard porous microfilament structure and even can on microfilament that is functionalized previously or microfilament structure, implement to handle.The surface modification of microfilament can utilize a variety of plasmas to realize, comprises that those are based on F
2, O
2, NH
3, He, N
2And H
2, other combination of other chemically reactive gas or inert gas, one or more reacting gass and one or more inert gases or the gas that can carry out the plasma induced polymerization reaction plasma of methane, ethane or acetylene for example.And, to compare with traditional " moistening " chemical technology that relates to solution, flushing, evaporation etc., plasma treatment realizes this surface modification with " drying " process.For example, can carry out plasma treatment on the microfilament in interspersing among gaseous environment.
In case possess the instruction here, those of ordinary skills can utilize well-known plasma technique to implement the present invention.The time span that employed plasma type and plasma contact with microfilament will change according to required result.For example, if desired oxidation is carried out on the microfilament surface, then can be used O
2Plasma, ammonia plasmas then are used to nitrogenous functional group is introduced the microfilament surface.In case know the instruction here, those of ordinary skills can select the processing time so that realize desired change/functionalization degree.
More specifically, by microfilament being placed in the reaction vessel that can hold plasma, microfilament or microfilament structure are carried out plasma treatment.For example can so produce plasma: (1) pressure in container is reduced to for example 100-500 millitorr with selected gas or gaseous mixture, and (2) are exposed to low-pressure gas the radio frequency that can make that plasma forms.When producing plasma, allow this plasma to keep contacting of the scheduled time with microfilament or microfilament structure, this time-dependent is in for example specimen size, reactor geometries, reactor power and/or plasma type, general in about about 10 minutes scope, thus microfilament functionalization or surface modification or microfilament structure formed.Surface modification can comprise the functionalization of preparing to carry out subsequently.
Processing to carbon microfilament or carbon microfilament structure as noted above produces to have modified surface and product that therefore have the surface characteristic of very favorable change.
Laser treatment
In a preferred embodiment, carbon nano-tube or carbon nanotube mats are implemented laser treatment.In another preferred embodiment, the screen printing ink that contains carbon nano-tube is implemented laser treatment.Laser treatment forms improved field emission performance for carbon nanotube mats or printing ink, and causes forming better field-transmitting cathode or field emission apparatus thus.
By laser treatment, utilize laser (being UV, IR etc.) to carbon nano-tube, carbon nanotube mats or carbon nanotube ink irradiation regular hour.Optionally, also can carry out laser radiation to field-transmitting cathode or field emission apparatus.
Example
Below example illustrated each embodiment of the present invention.
Example 1
Utilize the pad of PVDF binding agent
Obtained good field emission characteristic for the CNT pad that utilizes the PVDF binding agent.In order to prepare this pad, the PVDF (Kynar 741) of 0.04 gram is dissolved in 150 milliliters the acetone.In Waring blender, the CC type carbon nano-tube of 0.16 gram is mixed in the PVDF/ acetone soln.When suspension becomes even, add DI water, so that PVDF separates out.This CC type carbon nano-tube is collected among the PVDF that separates out.Water washes separating out material, and it is filled on the nylon membrane so that form thin pad.This pad is carried out mark so that top (air surface) and bottom (nylon membrane surface) can be identified.In low temperature oven (80 ℃), will fill up oven dry and it will be denoted as 296-29-3.
The part of CNT pad 296-29-3 is cut and use silver paste to paste on the surface of aluminium film/substrate of glass.Measure the I-V characteristic of CNT pad (top and lower surface).And, in air, carry out the UV laser radiation to improve emission characteristics (discussion of handling in the face of the UV laser radiation as follows).The wavelength of this UV Laser emission 266nm has pulsewidth, the 20.3mJ/cm of 5ns
2Radiant energy density and the repetition rate of 10Hz.Laser facula is mobile in cathode zone with 25% Duplication after each irradiation time.Each hot spot for the lip-deep irradiation array of CNT pad carries out 60 seconds irradiation.
Example 2
Utilize the pad of surfactant binding agent
Utilize the stabilising dispersions that can form the hydrophobic carbon nano-tube as the surfactant additive of surfactant and dispersing aid.Utilize this dispersion manufacturing pad then.The Surfynol CT324 (Air Products) of 0.55 gram is dissolved in the DI water of 200ml.Add the CC type carbon nano-tube of 0.15 gram and utilize probe-type sound wave processor (Branson) to disperse.It is last and air-dry that the material of this dispersion is filtered to nylon membrane (0.45 micron pore size size).When drying, pad will separate from nylon membrane.This pad is carried out mark so that top (air side) and bottom (nylon membrane side) can be identified.This pad is denoted as 296-29-1.
Optionally, this pad can be rinsed so that remove any loose Surfynol that adheres to.The Surfynol CT324 (Air Products) of 0.60 gram is dissolved in the DI water of 200ml.Add the CC type carbon nano-tube of 0.15 gram and utilize probe-type sound wave processor (Branson) to disperse.The material of this dispersion is filtered on the nylon membrane (0.45 micron pore size size), and utilizes methyl alcohol to wash by using vacuum equipment so that attract methyl alcohol to pass this pad.Pad after will washing then is air-dry.When drying, pad will separate from nylon membrane.This pad is carried out mark so that top (air side) and bottom (nylon membrane side) can be identified.This pad is denoted as 296-29-2.
The field emission measurement that the sample of describing in the example 1 and 2 that does not carry out laser radiation is carried out the results are shown among Fig. 6.Sample 296-29-2 shown in Figure 7 before irradiation and the contrast of afterwards field emission results and top and lower surface contrast.Fig. 8 was sample 296-29-2 before irradiation and a series of contrast photos of the emission of electronics afterwards pattern.Fig. 6 has disclosed when comparing with the top surface of 296-29-2, and the cut-in voltage of the top surface of sample 296-29-1 and 296-29-3 sharply reduces.The result of Fig. 6 shows that also with respect to lower surface, when using pad surface, top as negative electrode, the I-V characteristic has remarkable improvement.Fig. 7 illustrates that 296-29-2 its emission characteristics after irradiation is obviously improved to the level that almost reaches other two samples.These curves are drawn based on logarithmic scale.The top surface of contrast 296-29-2 is illustrating with microphoto (Fig. 8) afterwards how sample is presenting certain amplitude difference aspect the overall electric current density under identical operating voltage before the laser radiation.
The modification of carbon nano-tube film
Can pass through chemistry or mechanical treatment to carbon nano-tube or film modification.Its surface can be processed to introduce functional group.Operable technology comprises carbon nano-tube is exposed to electromagnetic radiation, ionising radiation, plasma or chemical reagent for example oxidant, electrophilic reagent, nucleopilic reagent, reducing agent, strong acid and highly basic and/or its combination.What cherish a special interest is UV laser radiation processing and plasma treatment.
The UV laser radiation of nanotube films is handled
Carry out treatment with irradiation so that change carbon microfilament, microfilament structure and/or wherein contain the surface characteristic of the matrix of nanotube.Utilized the UV irradiation to carry out testing many times to strengthen cathode characteristic.On silk screen printing CNT negative electrode, carried out preliminary research; Nearest result obtains on the CNT pad.
Silk screen printing
Use traditional organic binder bond to be screen-printed to from the CNT that gaseous hydrocarbon catalysis is turned out on ITO (tin indium oxide)/substrate of glass, and in air, under 350-450 ℃ temperature, cured 30 minutes.The CNT cathode area is 8 * 8mm
2Use has the diode structure of the distance piece of 150 μ m and measures emission current.Observe electronics emission pattern by the phosphor screen on the ITO/ substrate of glass, it is used as anode (annode area: 5 * 5mm in diode structure
2).Distance piece between anode and the negative electrode is so thin so that electron emission region has the size identical with anode dimension.Electric field shown in the data is defined as poor divided by distance piece thickness and phosphor/CNT thickness of the anodic bias that applied, and emission is calculated as emission current divided by annode area.Be used to from the tunable Nd:YAG of Q switching (neodymium: Yttrium-Aluminium-Garnet) 349 of laser and the wavelength of 266nm carry out the UV irradiation so that the CNT negative electrode is shone.The repetition rate of this is tunable UV laser is 10Hz, and the burst length is 5ns.By under the average laser energy of 1mJ with 4.9,9.8 and 44.4mm
2Change adjustment 20.3,10.2 of laser facula area and 2.25mJ/cm
2Laser energy density.Irradiation time changes from 10s to 60s.Laser facula is mobile in cathode zone with 25% Duplication after each irradiation time.At 20.3mJ/cm
2Energy density under air neutralization shine 60s in a vacuum in case the research atmosphere for the influence of laser radiation.Also use the ion beam irradiation CNT negative electrode of 30keV Ga or be exposed to the Ar plasma under various conditions with the contrast high power treatment.
Fig. 9 illustrates before the CNT reflector carries out 266nm in air the laser radiation and I-V characteristic afterwards.At 20.3mJ/cm
2Laser energy density under, after laser radiation, be increased to 14.45mA/cm in the emission that applies under the electric field of 5.7V/ μ m from 0.0027
2(Figure 10 illustrates before the irradiation and the remarkable contrast of launching pattern afterwards, and all there is increase number and this two aspect of emission that the emission position is shown), and at 10.2mJ/cm
2Laser energy density under be increased to 0.400mA/cm from 0.0014
2Open electric field at 20.3mJ/cm
2The time be reduced to 1.2V/ μ m from 3.7, and at 10.2mJ/cm
2The time be reduced to 1.5V/ μ m from 2.8.On the other hand, with 2.25mJ/cm
2Do not find any improvement in the sample of irradiation.Under the operating voltage of 6.2V/ μ m, observe 20.15mA/cm
2Maximum current density.If the phosphor anode can stand stronger electron bombard in higher electric field then current density will become much higher.
Figure 11 is illustrated in and utilizes energy density to be 20.3mJ/cm
2The laser radiation of 266nm wavelength before and CNT form afterwards.CNT restraints mat immediately in silk screen printing and after curing, and these CNT are tending towards with the open end himself orientation after the laser radiation.Figure 12 illustrates for the laser radiation of specific 266 and the 349nm emission as the function of laser energy density.The scope of emission before laser radiation represented with vertical bar in the drawings.Current density increases (from laser radiation about 1 μ A/cm before with 4 orders of magnitude
2To laser radiation 14.45mA/cm afterwards
2).Compare with irradiation, observe many that improvement will be good for the irradiation of 266nm for 349nm.Though be not subjected to concrete theoretical the restriction, the improvement degree difference explanation induced with laser reaction that causes owing to different wave length is not a simple thermal process, and the much higher laser photon of energy is necessary so that with the direct scission of link of C=C key (6.3eV).The effect of being brought out by the UV laser radiation shows mainly be owing to photoexcitation effect (for example photodissociation effect) and non-thermal effect.As if for the CNT negative electrode of the laser radiation that utilizes 266nm, emission is saturated after 100 Laser emission.On the other hand, along with the increase of time, in the situation of 349nm laser radiation, emission also will increase.This shows that in the situation of 266nm laser radiation, nearly all C-H, H-O chemical bond that is retained in the CNT negative electrode of organic binder bond ruptured by photon and/or be oxidized after curing, and utilizes irradiation time still less that organic binder bond is decomposed.On the other hand, so that decompose lip-deep remaining organic binder bond, this is because the energy of photon is lower for the obvious more Laser emission of the laser radiation needs of 349nm.The improvement of emission characteristics will be by photoexcitation and destructive effect and non-thermal effect causes because under these wavelength because the temperature that laser photon causes raises is the same level that almost is in.
Shown in Figure 13 at 20.3mJ/cm
2Laser energy density down during irradiation 60 seconds (600 emissions), irradiation atmosphere (air is to vacuum) is for the influence of emission.When utilizing the laser radiation sample of 266nm in air, emission increases with about 3 orders of magnitude, and for the irradiation of carrying out in a vacuum, the raising that observes emission that only can be slight.This has shown that the contribution of oxygen between the light period is oxidation.Therefore, equally in this case, utilize the improvement Billy of 266nm laser radiation more remarkable with the improvement of 349nm laser radiation.Require further study the correlation of laser radiation, so that illustrate the effect of laser radiation about oxygen pressure.
The CNT pad
Use silver paste that the CNT pad is pasted on the surface of aluminium film/substrate of glass.Utilize organic binder bond that the CNT sample is screen-printed on ITO (tin indium oxide)/substrate of glass before this.The I-V characteristic of test CNT pad (top and lower surface) and silk screen printing CNT reflector.And, in air, carry out the UV laser radiation to improve emission characteristics [3,4].The UV laser of this 266nm has pulsewidth, the 20.3mJ/cm of 5ns
2Radiant energy density, and the repetition rate of 10Hz.For each hot spot of the irradiation array on the CNT emitter surface, irradiation continues 60 seconds time.
Figure 14 illustrates and carries out before the UV laser radiation in air and afterwards as the emission of electric field function for CNT pad and silk screen printing CNT reflector.For the electric field that applies of 3.47V/ μ m, the top of CNT pad and the emission of lower surface are 1.99 and 0.03mA/cm
2, and utilize identical electric field not observe any emission for silk screen printing CNT reflector.After the UV laser radiation, for the top and the lower surface of CNT pad, emission is changed to 1.52 and 6.76mA/cm
2, and the emission of silk screen printing CNT reflector is increased to 0.33mA/cm
2As shown in the SEM microphoto of CNT pad in Figure 15, the form on two surfaces is very different.Figure 16 demonstrates emission uniformity and also is modified after the UV laser radiation.For this data conversion is become perspective view, should notice that the electron emission characteristic that does not carry out any surface-treated CNT pad is similar to the electron emission characteristic of silk screen printing CNT negative electrode after laser radiation.
Example 3-CNT negative electrode
Shown in Fig. 3,4 and 5, at ultra high vacuum chamber (5.3 * 10
-8Pa) after the timeliness, measure emission characteristics in by carbon nano-tube (CNT) negative electrode that on substrate of glass, carries out the silk screen printing manufacturing.CNT negative electrode on substrate of glass is exposed to argon (Ar) plasma of the vacuum degree of discharge voltage with 250V and 40Pa.The plasma exposure time changes (30s, 1min, 2min, 3min, 4min and 5min) with the following time.In the ultra high vacuum chamber, measure the emission characteristics of CNT negative electrode.Fig. 3 is illustrated in and utilizes before the plasma treatment 3min and the I-V characteristic of CNT negative electrode afterwards.After utilizing Ar plasma treatment 3min, emission current is from 9.0 * 10 under the electric field of 4V/ μ m
-5To 0.3mA/cm
2Increase with three orders of magnitude, and cut-in voltage is reduced to 1.7V/ μ m from 3.3V/ μ m.Electronics emission pattern when Fig. 4 is illustrated in 4.6V/ μ m; (a) before the plasma treatment; (b) utilize after the plasma treatment 3min.This clearly illustrates that the number and the intensity of launching the position after plasma treatment all have increase.These presentation of results have significantly improved emission characteristics by plasma treatment.Fig. 5 is illustrated in before the plasma treatment and the CNT image that uses scanning electron microscopy (SEM) to obtain afterwards.The CNT bundle that is entangled to after silk screen printing is together taken apart a little, thus after the Ar plasma treatment is carried out on the surface, cause to a certain degree carry out orientation perpendicular to negative electrode.Be not subjected to concrete theoretical the restriction, think after plasma treatment, can help after plasma treatment, to strengthen the electronics emission from observed this directionality effect of CNT.
Also do not carry out any test so far with the effect of research plasma treatment for nanometer pipe pad negative electrode.Look back shown in figure 2 the emission results that the screen printing electrode of handling and the pad electrode of handling are compared, can expect to pass through the pad electrode of plasma treatment the negative electrode that is improved.
Example 4-carbon nanotube ink
Be prepared as follows the printing ink (sample 296-47-02) that contains carbon nano-tube.At first VAGH (ethylene copolymer of DOW hydroxyl modification) and 100 gamma butyrolactones that restrain by utilizing stirring rod to mix 9.5 grams on hot plate at 60 ℃ prepare polymeric binder and liquid support, dissolve fully until binding agent.After the VAGH dissolving, obtain limpid yellow solution.In solution, add Triton (the TritonX)-X surfactant of 1 gram, and stir so that its dissolving.Add the dry carbon microfilament of 2.0 grams, and utilize probe-type Branson sound wave processor mixture to be carried out sonicated at 450W.Proceed sonicated until obtaining the gel slurries.Use then three-high mill with this printing ink be milled into uniformly, the printing ink of viscosity.Pass through this three-high mill by four times printing ink is handled, and at last the stainless steel screen pack by 500 sieve meshes filters printing ink.
Example 5-carries out the carbon nanotube ink of plasma treatment
At ultra high vacuum chamber (5.3 * 10
-8Pa) after the timeliness, measure in by on substrate of glass, carbon nanotube ink being carried out the emission characteristics of carbon nano-tube (CNT) negative electrode of silk screen printing manufacturing.CNT negative electrode on substrate of glass is exposed to argon (Ar) plasma of the vacuum degree of discharge voltage with 250V and 40Pa.The plasma exposure time changes (30s, 1min, 2min, 3min, 4min and 5min) with the following time.In the ultra high vacuum chamber, measure the emission characteristics of CNT negative electrode.After utilizing Ar plasma treatment 3min, emission current is from 9.0 * 10 under the electric field of 4V/ μ m
-5To 0.3mA/cm
2Increase with three orders of magnitude, and cut-in voltage is reduced to 1.7V/ μ m from 3.3V/ μ m.Clearly illustrate that with the pattern of the emission of the electronics when 4.6V/ μ m afterwards the number and the intensity of launching the position after plasma treatment all have increase before utilizing plasma treatment 3min.Before the record plasma treatment and the scanning electron microscopy of cathode surface (SEM) image afterwards.These images demonstrate the CNT bundle that is entangled to together and are taken apart a little after silk screen printing, thus after the Ar plasma treatment is carried out on the surface, cause to a certain degree carry out orientation perpendicular to negative electrode.Be not subjected to concrete theoretical the restriction, think after plasma treatment, can help after plasma treatment, to strengthen the electronics emission from observed this directionality effect of CNT.These presentation of results have significantly improved emission characteristics by plasma treatment.
The negative electrode that example 6-prepares from the carbon nanotube ink that utilizes the laser radiation processing
Utilize UV laser handle before and measure afterwards by on substrate of glass, carbon nanotube ink being carried out the emission characteristics of carbon nano-tube (CNT) negative electrode that silk screen printing makes.In air and at vacuum chamber (pressure: 1 * 10
-5A) in corresponding to 4.9,9.8 and 44.4mm
2The oval beam spot size, respectively 20.3,10.2 and 2.25mJ/cm
2Mean energy density under, use from the wavelength of tunable laser to the UV laser of 349nm and 266nm CNT sample irradiation 1 minute.The repetition rate of this laser is 10Hz, and the pulse duration is 5ns.Use has the diode structure (annode area: 5 * 5mm of the distance piece of 125mm
2) the measurement emission current.Observe electronics emission pattern by the phosphor screen on the ito anode.In air, utilize and have 20.3 and 10.2mJ/cm
2The 349nm of average irradiation energy density and the emission characteristics of the CNT sample of the UV laser radiation of 266nm, all after laser radiation, be significantly improved.For example, emission is increased to 259.4mA/cm from 8.9
2, and the unlatching electric field is reduced to the 2.9V/ micron from 3.6.
Based on the foregoing description, it will be appreciated by those skilled in the art that further aspect of the present invention and advantage.Accordingly, except as appended claim is pointed subsequently, the present invention be not limited to be specifically illustrated with the content of describing.
All following references all are bonded to here by reference.
List of references
Carbon nano-tube is used for light source in field-transmitting cathode
PCT application PCT/SE00/015221--A Light Source, and a Field EmissionCathode (light source and field-transmitting cathode)
Other use
PCT application PCT/US99/13648--Free-Standing and Aligned CarbonNanotubes and Synthesis Thereof (scanning electron microscope, alkalimetal batteries, electromagnetic interference shield, and microelectrodes) (independently and the carbon nano-tube of aiming at and synthetic (scanning electron microscopy, alkali metal battery, electromagnetic interference shield, and microelectrode) thereof)
Further describe
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Claims (12)
1. field emission apparatus comprises:
Anode; With
The negative electrode that comprises carbon nanotube mats;
Wherein utilize by the filter cake that forms from a plurality of nanotubes of the suspension filtered of liquid and produce described carbon nanotube mats;
Wherein said a plurality of nanotube is basic for columniform, and has one or more graphite linings concentric with their cylinder axis, and described nanotube does not contain the carbon coating of pyrolytic deposition substantially, has the basic diameter uniformly between 0.4nm and the 100nm.
2. device according to claim 1, described spacer have top surface and relative lower surface, and described lower surface is corresponding to the filter cake surface of placing near filter during forming at filter cake; Thereby described top surface is as the emitting surface of described negative electrode.
3. device according to claim 1, wherein said a plurality of nanotubes have the form of similar fish-bone.
4. device according to claim 1, wherein said a plurality of nanotubes have single wall.
5. device according to claim 1, wherein said a plurality of nanotubes are oxidized.
6. device according to claim 5, wherein said nanotube is crosslinked.
7. according to any described device in the claim 1,3,4,5 and 6, wherein when having binding agent, form described filter cake.
8. device according to claim 7, wherein said binding agent are can be by the fluoropolymer of dissolution with solvents.
9. device according to claim 8, wherein said binding agent is PVDF.
10. device according to claim 1, wherein said nanotube has the length diameter ratio greater than 5.
11. a field-transmitting cathode comprises:
Carbon nanotube mats;
Wherein utilize by the filter cake that forms from a plurality of nanotubes of the suspension filtered of liquid and produce described carbon nanotube mats;
Wherein said a plurality of nanotube is basic for columniform, and has one or more graphite linings concentric with their cylinder axis, and described nanotube does not contain the carbon coating of pyrolytic deposition substantially, has the basic diameter uniformly between 0.4nm and the 100nm.
12. negative electrode according to claim 11, described spacer have top surface and relative lower surface, described lower surface is corresponding to the filter cake surface of placing near filter during forming at filter cake; Thereby described top surface is as the emitting surface of described negative electrode.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US48591803P | 2003-07-09 | 2003-07-09 | |
| US60/485,918 | 2003-07-09 | ||
| PCT/US2004/021878 WO2005012162A2 (en) | 2003-07-09 | 2004-07-09 | Field emission devices made with laser and/or plasma treated carbon nanotube mats, films or inks |
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| Publication Number | Publication Date |
|---|---|
| CN101410927A CN101410927A (en) | 2009-04-15 |
| CN101410927B true CN101410927B (en) | 2011-09-14 |
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| CN2004800253870A Expired - Fee Related CN101410927B (en) | 2003-07-09 | 2004-07-09 | Field emission devices made with laser and/or plasma treated carbon nanotube mats, films or inks |
Country Status (8)
| Country | Link |
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| EP (1) | EP1663857A4 (en) |
| JP (2) | JP2007531201A (en) |
| KR (3) | KR20060064604A (en) |
| CN (1) | CN101410927B (en) |
| AU (1) | AU2004261558B2 (en) |
| CA (1) | CA2531628A1 (en) |
| MX (1) | MXPA06000248A (en) |
| WO (1) | WO2005012162A2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI548448B (en) * | 2015-01-05 | 2016-09-11 | 國立交通大學 | Method for preparing two-dimensional material |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100922399B1 (en) | 2008-02-29 | 2009-10-19 | 고려대학교 산학협력단 | Electron emission source, device adopting the source and fabrication method the source |
| JP5170666B2 (en) * | 2008-05-30 | 2013-03-27 | 独立行政法人国立高等専門学校機構 | Method of manufacturing electron source electrode for field emission |
| KR101075481B1 (en) * | 2009-09-29 | 2011-10-21 | 경희대학교 산학협력단 | Fabrication method of flexible board |
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- 2004-07-09 WO PCT/US2004/021878 patent/WO2005012162A2/en active Search and Examination
- 2004-07-09 KR KR1020097014365A patent/KR20090082295A/en not_active Application Discontinuation
- 2004-07-09 JP JP2006518900A patent/JP2007531201A/en active Pending
- 2004-07-09 AU AU2004261558A patent/AU2004261558B2/en not_active Ceased
- 2004-07-09 CA CA002531628A patent/CA2531628A1/en not_active Abandoned
- 2004-07-09 EP EP04777763A patent/EP1663857A4/en not_active Withdrawn
- 2004-07-09 MX MXPA06000248A patent/MXPA06000248A/en active IP Right Grant
- 2004-07-09 KR KR1020097014364A patent/KR20090082294A/en not_active Application Discontinuation
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Also Published As
| Publication number | Publication date |
|---|---|
| JP2010177214A (en) | 2010-08-12 |
| WO2005012162A3 (en) | 2008-10-16 |
| MXPA06000248A (en) | 2006-08-31 |
| AU2004261558B2 (en) | 2010-04-22 |
| CN101410927A (en) | 2009-04-15 |
| WO2005012162A2 (en) | 2005-02-10 |
| KR20060064604A (en) | 2006-06-13 |
| AU2004261558A1 (en) | 2005-02-10 |
| JP2007531201A (en) | 2007-11-01 |
| EP1663857A4 (en) | 2011-05-25 |
| CA2531628A1 (en) | 2005-02-10 |
| EP1663857A2 (en) | 2006-06-07 |
| KR20090082295A (en) | 2009-07-29 |
| KR20090082294A (en) | 2009-07-29 |
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