Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B12/00—Arrangements for controlling delivery; Arrangements for controlling the spray area
  • B05B12/08—Arrangements for controlling delivery; Arrangements for controlling the spray area responsive to condition of liquid or other fluent material to be discharged, of ambient medium or of target ; responsive to condition of spray devices or of supply means, e.g. pipes, pumps or their drive means
  • B05B12/082—Arrangements for controlling delivery; Arrangements for controlling the spray area responsive to condition of liquid or other fluent material to be discharged, of ambient medium or of target ; responsive to condition of spray devices or of supply means, e.g. pipes, pumps or their drive means responsive to a condition of the discharged jet or spray, e.g. to jet shape, spray pattern or droplet size
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
  • B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
  • B05B5/035—Discharge apparatus, e.g. electrostatic spray guns characterised by gasless spraying, e.g. electrostatically assisted airless spraying
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B1/00—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means
  • B05B1/14—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means with multiple outlet openings; with strainers in or outside the outlet opening
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B12/00—Arrangements for controlling delivery; Arrangements for controlling the spray area
  • B05B12/16—Arrangements for controlling delivery; Arrangements for controlling the spray area for controlling the spray area
  • B05B12/20—Masking elements, i.e. elements defining uncoated areas on an object to be coated
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
  • B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
  • B05B5/0255—Discharge apparatus, e.g. electrostatic spray guns spraying and depositing by electrostatic forces only
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
  • B05B5/08—Plant for applying liquids or other fluent materials to objects
  • B05B5/10—Arrangements for supplying power, e.g. charging power
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
  • B05B5/16—Arrangements for supplying liquids or other fluent material
  • B05B5/1608—Arrangements for supplying liquids or other fluent material the liquid or other fluent material being electrically conductive
  • B05B5/1616—Arrangements for supplying liquids or other fluent material the liquid or other fluent material being electrically conductive and the arrangement comprising means for insulating a grounded material source from high voltage applied to the material
  • B05B5/165—Arrangements for supplying liquids or other fluent material the liquid or other fluent material being electrically conductive and the arrangement comprising means for insulating a grounded material source from high voltage applied to the material by dividing the material into discrete quantities, e.g. droplets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C5/00—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work
  • B05C5/02—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work the liquid or other fluent material being discharged through an outlet orifice by pressure, e.g. from an outlet device in contact or almost in contact, with the work
  • B05C5/0208—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work the liquid or other fluent material being discharged through an outlet orifice by pressure, e.g. from an outlet device in contact or almost in contact, with the work for applying liquid or other fluent material to separate articles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/007—Processes for applying liquids or other fluent materials using an electrostatic field
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
  • B05D1/04—Processes for applying liquids or other fluent materials performed by spraying involving the use of an electrostatic field
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
  • B05D1/04—Processes for applying liquids or other fluent materials performed by spraying involving the use of an electrostatic field
  • B05D1/045—Processes for applying liquids or other fluent materials performed by spraying involving the use of an electrostatic field on non-conductive substrates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/02—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to macromolecular substances, e.g. rubber
  • B05D7/04—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to macromolecular substances, e.g. rubber to surfaces of films or sheets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/24—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials for applying particular liquids or other fluent materials
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B32/00—Carbon; Compounds thereof
  • C01B32/15—Nano-sized carbon materials
  • C01B32/158—Carbon nanotubes
  • C01B32/159—Carbon nanotubes single-walled
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
  • C08J7/06—Coating with compositions not containing macromolecular substances
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L25/00—Compositions of, homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Compositions of derivatives of such polymers
  • C08L25/18—Homopolymers or copolymers of aromatic monomers containing elements other than carbon and hydrogen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
  • C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L27/12—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D30/00—Field-effect transistors [FET]
  • H10D30/60—Insulated-gate field-effect transistors [IGFET]
  • H10D30/67—Thin-film transistors [TFT]
  • H10D30/6757—Thin-film transistors [TFT] characterised by the structure of the channel, e.g. transverse or longitudinal shape or doping profile
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K10/00—Organic devices specially adapted for rectifying, amplifying, oscillating or switching; Organic capacitors or resistors having potential barriers
  • H10K10/40—Organic transistors
  • H10K10/46—Field-effect transistors, e.g. organic thin-film transistors [OTFT]
  • H10K10/462—Insulated gate field-effect transistors [IGFETs]
  • H10K10/468—Insulated gate field-effect transistors [IGFETs] characterised by the gate dielectrics
  • H10K10/471—Insulated gate field-effect transistors [IGFETs] characterised by the gate dielectrics the gate dielectric comprising only organic materials
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/20—Carbon compounds, e.g. carbon nanotubes or fullerenes
  • H10K85/221—Carbon nanotubes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D2601/00—Inorganic fillers
  • B05D2601/20—Inorganic fillers used for non-pigmentation effect
• • 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
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/50—Photovoltaic [PV] energy
  • Y02E10/549—Organic PV cells
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

• the invention is generally directed to printable electronics. More specifically, the invention is directed to an apparatus and method for aerosol deposition of nanoparticles on a substrate.
• printable electronics require depositing inks on a surface in a defined pattern.
• the inks used in printable electronics include functional electronic or optical materials, such as inks having carbon nanotubes, the material acting as a macroscopic transistor channel when printed to form a network.
• Carbon nanotubes have outstanding electrical properties with semiconducting single-walled carbon nanotubes (SWCNTs) performing as semiconducting channels in high mobility transistors in printable electronics applications. In such applications, thousands of carbon nanotubes are laid down on a surface and form a network of electrically connected wires. These networks form readily upon soaking a substrate in a carbon nanotube containing solution (or ink).
• an apparatus for aerosol deposition of nanoparticles on a substrate includes: an aerosol generator for generating an aerosol of micron-sized droplets, each droplet comprising a limited number of nanoparticles; and a deposition chamber for receiving the aerosol from the aerosol generator.
• the deposition chamber has an electrostatic field for attracting individual droplets in the aerosol to a substrate. The electrostatic field is substantially perpendicular to the substrate.
• the apparatus also includes an injector nozzle with one to several openings either parallel or perpendicular to the deposition substrate.
• the deposition chamber further includes a stencil mask positioned between the flow of the aerosol and the substrate.
• the electrostatic field is provided by interspaced charged plates and the substrate is positioned on the grounded plate.
• the charged plates are electrostatically charged insulators or voltage biased conductors.
• the charged plates are patterned to spatially modulate the electric field and promote nanoparticle deposition at specific locations on the substrate.
• the aerosol flows in a laminar fashion and is spatially engineered to afford nanoparticle deposition at specific locations on the substrate.
• the apparatus described above in the production of a thin film of nanoparticles.
• the apparatus is used in the production of a thin film transistor.
• the apparatus is used in the production of a conductive electrode, a diode, a photovoltaic cell, a physical sensor or chemical sensor.
• the conductive electrode may be either a transparent or non-transparent electrode.
• a method for depositing nanoparticles on a substrate comprising the steps of: generating an aerosol of micron-sized droplets, each droplet comprising a limited number of carbon nanoparticles; and subjecting the aerosol to an electrostatic field that causes the micron- sized droplets to be deposited on a substrate.
• the method further comprises a step of passing the micron- sized droplets through a mask prior to being deposited on the substrate.
• the method further comprises maskless patterning of the nanoparticle film on the substrate by patterned charging of the substrate.
• the electrostatic field may be provided by interspaced charged plates and the substrate positioned on the grounded charged plate.
• the charged plates may be electrostatically charged insulators or voltage biased conductors.
• the charged plates can be patterned to spatially modulate the electric field and promote carbon nanotube deposition at specific locations on the substrate.
• the aerosol flows in a laminar fashion and is spatially engineered to afford nanoparticle deposition at specific locations on the substrate.
• the substrate can have a conductive surface or a dielectric surface.
• a material that has a hydrophobic surface and at least one nanoparticle adhered on the surface.
• a plurality of nanoparticles is provided in a network.
• the nanoparticles can act as transistors.
• the surface has a water contact angle greater than 80° such as poly(vinylphenol) based dielectric or a polytetrafluoroethylene based dielectric, for example XeroxTM Dielectric xdi-d1 .2 or Teflon®-AF, or a fluoropolymer, such as the amorphous (non-crystalline) fluoropolymer CyTOP®.
• the material is provided as a semiconductor in a thin film transistor.
• the material can be a conductive electrode, a diode, a photovoltaic cell, a physical sensor or chemical sensor.
• the conductive electrode may be either a transparent or non-transparent electrode.
• the substrate is a conductive surface or a dielectric surface.
• the substrate has an at least partially conductive surface.
• the substrate has an at least partially dielectric surface.
• the surface may be a hydrophilic or hydrophobic surface, in some embodiments.
• a hydrophobic surface is used to eliminate the interference of humidity that can confound the sensing of an analyte, for example.
• the substrate/material is a device such as, for example, a physical or chemical sensor that is devoid of humidity fluctuations.
• the apparatus described herein is used in the production of such a substrate/material, which for example, could be a thin film transistor having said substrate/material as a dielectric or as a coating at the interface between a dielectric and a network of SWCNTs. This results in minimal hysteresis due to the elimination of interactions between the SWCNT network and atmospheric water. In such a device or sensor, the hysteresis that could result would be principally from interactions between the SWCNT network and desired analyte. This material can be particularly helpful in minimizing the impact of relative humidity changes on the use of a sensor.
• the substrate has a surface with water contact angle greater than 80°, for example between 85° and 120°, about 90° or between 1 17-120°.
• the surface may be a modified oxide surface, for example self-assembled monolayers on Si0 2 , Al 2 0 3 , Zr0 2 or Hf0 2 .
• the surface may be polymeric. Polymers may be homopolymers or copolymers, for example alternating copolymers, periodic copolymers statistical copolymers, block copolymers and the like.
• the polymer may be fluorinated.
• fluorinated polymers include, but are not limited to: fluorinated polyalkenes, fluorinated polyacrylates, fluorinated polymethacrylates, fluorinated polystyrenes, fluorinated polycarbonates, fluorinated silicones and fluorinated poly(p-xylylene) polymers (e.g. Parylene).
• Example surfaces, or polymers include, but are not limited to: polyvinylidene chloride, polyvinylidene fluoride; polyhexamethylene adipamide (Nylon 66); Nylon 7; poly(dodecano-12-lactam) (Nylon 12); polyamide; cellulose acetate; polysulfone; polymethyl methacrylate; polyvinyl acetate; polycarbonate; polystyrene; polypropylene; polyimide; epoxy; polyethylene terephthalate; silicones; olefins (alkenes); cellulose nitrate; ultra-high-molecular-weight polyethylene; polychloroprene; polyvinyl chloride; latex; butyl rubber; polytetrafluoroethylene; and poly(p-xylylene) polymers (e.g. Parylene).
• polyvinylidene chloride polyvinylidene fluoride
• polyhexamethylene adipamide Nylon 66
• the hydrophobic surface is a poly(vinylphenol) based dielectric or a polytetrafluoroethylene based dielectric. In some embodiments, the surface is polymethylsilsesquioxane.
• the surface is polytetrafluoroethene; perfluorovinylpropyl ether-tetrafluoroethylene copolymer; tetrafluoroethene-perfluoro(propylvinylether) copolymer; poly[tetrafluoroethylene-co-perfluoro (alkyl vinyl ether)]; tetrafluoroethylene/perfluoro(propylvinylether) copolymer; polytetrafluoroethylene- perfluoroalkyl vinyl ether copolymer; poly(tetrafluoroethylene-co-tetrafluoro-ethylene perfluoropropyl ether); 1 ,1 ,1 ,2,2,3,3-heptafluoro-3-[(trifluoroethenyl)oxy]-propan polymer with tetrafluoroethene; or 1 ,1 ,1 , 2,2,3, 3-heptafluor
• each micron-sized droplet can comprise less than 5 nanoparticles per droplet, for example one nanoparticle per droplet.
• the nanoparticle can be boron nitride, molybdenum disulfide, tungsten disulfide, a carbon- or phosphorus-based nanoparticle.
• the nanoparticle can be a combination of the above materials.
• the nanoparticle can take on various crystalline forms, such as single-walled or multi-walled nanotubes, nanorods, nanospheres, nanoflakes or nanoribbons.
• the nanoparticle is a single-walled carbon nanotube.
• the nanoparticle is a graphene nanoribbon.
• the apparatus described hereinabove can form part of a roll-to-roll printing system.
• a material comprising polymers having carbon nanotube networks deposited thereon by the apparatus described above for use as gate dielectrics in a bottom gate transistor or as an encapsulation layer.
• a material comprising polymers having carbon nanotube networks deposited thereon by the apparatus described above for use as gate dielectrics in an air exposed transistor without an encapsulation layer.
• the material has transfer characteristics without hysteresis from 0-1 MV/m applied gate field.
• FIG. 1 is a schematic of an apparatus according to an embodiment of the present invention
• FIG. 2 is a scanning electron microscopy image of a network of single-walled carbon nanotubes assembled using the apparatus of the present invention
• FIG. 3 is a schematic of the deposition chamber according to an embodiment of the present invention.
• FIG. 4 is an optical (top) and scanning electron microscopy (bottom) image showing patterned nanotube networks obtained combining a shadow mask with the apparatus of the present invention
• FIG. 5 is an optical image of a series of depositions performed under different electric field intensities, (a) and (b) being the same image taken under different illumination conditions;
• FIG. 6 is a graphical representation of carbon nanotube transistors on polymer dielectrics. Transfer characteristics are shown on linear and logarithmic scales for forward and reverse sweep directions, a) Xerox Dielectric xdi-d1 .2. Sweep rate is 0.22 V/s. b) Teflon-AF. Sweep rate 0.55 V/s;
• FIG. 7 is a graphical representation of a gate dielectric stress test, a) Transfer characteristics for Xerox Dielectric xdi-d1 .2 taken at different sweep ranges from ⁇ 10 V to ⁇ 60 V.
• the sweep frequency is 1 10 mHz.
• Inset shows extracted threshold voltages (V,) for forward (F) and reverse (R) sweep directions, b) Time evolution of the transistor conductance (red trace) for Xerox Dielectric xdi-d1 .2 under a sequence of gate voltages (blue trace), c) Transfer characteristics for Teflon-AF dielectric taken at different sweep ranges from ⁇ 15 V to ⁇ 75 V.
• the sweep frequency is 1 10 mHz.
• Inset shows extracted threshold voltages (V t ) for forward (F) and reverse (R) sweep directions, d) Time evolution of transistor conductance (red trace) for Teflon-AF dielectric under a sequence of gate voltages (blue trace); and
• FIG. 8 is a graphical representation of transfer characteristics of encapsulated, bottom gate SWCNT network transistor using Xerox Dielectric xdi-dl.2 both dielectric and encapsulation layers.
• FIG. 9 depicts maskless deposition of carbon nanotube films, (a) Deposition from a slit-shape nozzle, (b) Raman intensity profile across a stripe (grey circle) of carbon nanotube material. The light gray line is a lorentzian profile, (c) Deposition pattern obtained from a nozzle with multiple apertures. From left to right, the sample is immobile for two durations and then continuously translated for 3 mm, and then immobile again for two more steps, (d) Deposition of carbon nanotubes on a nylon film using a sample holder with a patterned ground.
• FIG. 10 is a schematic of nozzle designs to facilitate both aerosol injection and gas recovery.
• FIG. 10a illustrates a single coaxial nozzle design.
• FIG. 10b illustrates a multiple coaxial nozzle design.
• the apparatus (1 ) for deposition of carbon nanotubes on a substrate includes: an aerosol generator (2) for generating an aerosol of micron-sized droplets (3) and a deposition chamber (4) for receiving the droplets from the generator (2).
• the deposition chamber (4) has an electrostatic field (5) for attracting droplets (3) in the aerosol to a substrate.
• the electrostatic field (5) being substantially perpendicular to the substrate. In other words, the electrostatic field is more or less 90 degrees to the substrate.
• the apparatus (1 ) described herein can form part of a roll-to-roll printing system.
• the aerosol generator (2) is a separate unit within the apparatus (1 ). However, the aerosol generator (2) can be integrally connected to the deposition chamber (4). In either case, the aerosol generator (2) is responsible for generating an aerosol of micron-sized droplets (3).
• the aerosol generator (2) will typically include a mist generating chamber (20) and a nozzle (21 ). However, it is possible to generate an aerosol by linking a container containing a solution directly to an atomizer nozzle.
• each droplet (3) contains a limited number of nanoparticles, for example, five or less nanoparticles. Droplets containing a nanoparticle, such as a single-walled carbon nanotube, are particularly useful in forming electrical networks (FIG. 2).
• the aerosol of micron-sized droplets (3) is fed into a deposition chamber (4) through an inlet (5) connected to the nozzle (21 ) or through a conduit (6) connecting the nozzle (21 ) to the deposition chamber (4).
• the aerosol travels through the deposition chamber (4), and if not deposited on the substrate, exits the chamber (4) through an outlet (7).
• the droplets (3) are attracted or drawn to the substrate (8) by an electrostatic field created by a charged top plate (9) and grounded bottom plate (10), such as, but not limited to, electrostatically charged insulators or voltage biased conductors.
• the substrate (8) is positioned on the bottom plate (10) to receive the individual droplets (3) from the aerosol.
• one or more injector nozzles (1 1 ) are provided in conjunction with the charged top plate (9) to introduce the droplets (3) to the electrostatic field created between the charged top plate (9) and the grounded bottom plate (10).
• the droplets (3) are propelled through openings in the charged top plate and attracted or drawn to the substrate (8) through the electrostatic field.
• a stencil mask can be provided between the flow of the aerosol and the substrate (8). As shown in FIG. 4, use of a stencil mask allows for the deposition of droplets (3) to be patterned on the substrate (8) in a predefined manner.
• the charged top (9) and/or bottom plates (10) are patterned to spatially modulate the electrostatic field in order to promote carbon nanotube deposition at specific locations on the substrate (8).
• the aerosol can flow in a laminar fashion through the deposition chamber (4) and be spatially engineered to afford carbon nanotube deposition at specific locations on the substrate (8).
• the precipitation of carbon nanotube particles on the substrate (8) can also be controlled or patterned by adjusting the deposition parameters of the starting solution of the material being deposited or adhered onto the substrate; the aerosol flow rate; the electrostatic field; the nozzle temperature, the substrate temperature and atmospheric content of the deposition chamber; and/or the composition of the carrier gas that flows through the deposition chamber.
• the apparatus (1 ) described herein allows for nanoparticle films/networks, for example, to be patterned on the substrate to sub-millimetre feature sizes. Nanoparticles that either carry a net charge or are charge neutral but have strong electrical polarizability, are particularly useful in the apparatus (1 ). Charged/polarizable nanoparticles will interact with the electrostatic field in the deposition chamber (4), causing the nanoparticles to be adhered to the substrate (8).
• the intensity of the interaction with the electrostatic field can be adjusted in two ways: externally, using Corona discharge or UV exposure, for example, to change the charge on the nanoparticle; or intrinsically, by modifying the solution's chemical characteristics.
• deposition of material using an aerosol system of the present invention may be sensitive to details of the gas flow. Small disruption or asymmetry in the gas flow may reduce uniformity of deposited material. This may be important especially for scaling up deposition to accommodate larger samples, for example samples having an area of greater than about 10 cm 2 .
• further improvements to deposition uniformity may be achieved by altering nozzle design to combine both aerosol injection and gas recovery.
• FIG. 10 illustrates two nozzle designs to facilitate both aerosol injection and gas recovery.
• FIG. 10a illustrates a single coaxial nozzle design
• FIG. 10b illustrates a multiple coaxial nozzle design. Referring to FIG.
• a coaxial nozzle (30) comprises an aerosol feed conduit (31 ) axially aligned with an electrostatic field to permit injection of an aerosol (40) into a deposition chamber so that droplets (41 ), only one labeled, are propelled toward a substrate (42).
• the coaxial nozzle (30) further comprises a gas return conduit (32) housing the aerosol feed conduit (31 ).
• the aerosol feed conduit (31 ) preferably extends through and is preferably concentric with the gas return conduit (32).
• other arrangements in which an aerosol feed conduit is housed inside a gas return conduit are suitable.
• the diameter of the gas return conduit (32) is larger than the diameter of the aerosol feed conduit (31 ) by an amount sufficient to permit reentry gases (33), for example carrier gas and solvent gas, to re-enter the nozzle (30) in a space (34) outside the aerosol feed conduit (31 ) and inside the gas return conduit (32).
• reentry gases for example carrier gas and solvent gas
• Back pressure in the deposition chamber facilitates reentry of the gases (33) into the nozzle (30).
• An end (35) of the gas return conduit (32) may be sealed around the aerosol feed conduit (31 ) to force reentry gases (33) into an exhaust outlet (36) in fluid communication with and extending transversely from the gas return conduit (32), preferably proximate the end (35) of the gas return conduit (32).
• the reentry gases (33) are expelled through the exhaust outlet (36) as exhaust gases (33').
• the multiple coaxial nozzle design comprises a plurality (39) of single coaxial nozzles (30), only one labeled, as described in FIG. 10a.
• the plurality (39) of single coaxial nozzles (30) are fluidly interconnected through exhaust outlets (36), only a few labeled, of each nozzle (30) so that reentry gases (33) are collected and exhausted as exhaust gases (33') out of the plurality (39) of nozzles (30) through terminal exhaust outlets (36').
• FIG. 10b illustrates three rows of nozzles (30), each row separately exhausting exhaust gases (33') through three terminal exhaust outlets (36'), any suitable arrangement of nozzles (30) and connection of exhaust outlets (36) may be used.
• Nanoparticles that can be used in the apparatus (1 ) include, but are not limited to, boron nitride, molybdenum disulfide, tungsten disulfide, and phosphorus- or carbon-based nanoparticles.
• Nanoparticles may comprise other elements that alter electronic properties, for example carbon nanotubes may comprise boron, nitrogen or other elements to alter electronic properties of the carbon nanotubes.
• carbon-based nanoparticles could include carbon nanotubes, nanorods, nanospheres, nanoflakes and nanoribbons. Single-walled carbon nanotubes are particularly useful for high performance printed transistors.
• Graphene nanoribbons are also particularly useful as semiconductors in transistors.
• Further examples of nanoparticles can include polymers having a molecular weight between about 1 ,000 and 1 ,000,000 g/mol.
• Other examples of nanoparticles that can be used in the apparatus (1 ) can be a combination of the above materials.
• the substrate (8) used in the apparatus is chosen based on the product being manufactured. In most cases, the substrate will be an electrically insulating material, such as, a hydrophilic or hydrophobic dielectric surface, that when coated with a network of single-walled carbon nanotubes can function as a thin (or ultra thin) film transistor.
• a conductive substrate such as metal, having nanoparticles adhered thereto.
• the substrate will often be patterned with multiple materials typical of printed devices, for example dry/cured conductive, insulating and dielectric inks.
• the manufactured product can be a diode, a conductive electrode (transparent or non-transparent), a photovoltaic cell, a physical sensor, a chemical sensor or all possible combinations of such devices.
• the nanoparticles have a size that should not exceed the size of the droplet. For droplets having a diameter of about 1000 nm, a longest dimension of the nanoparticles may be in a range of about 100-1000 nm. For nanoflakes, diameters may be in a range of about 50-1000 nm.
• the nanoparticles may be 2-dimensional or 3-dimensional.
• solvents that can be aerosolized include, but are not limited to non-polar solvents (e.g. toluene, chlorobenzene, and the like) and polar solvents (e.g. alcohols, ketones, water, and the like).
• Non-polar solvents are generally preferred.
• Aerosol properties may be suitably adjusted to optimize performance.
• Diameter of solvent droplets in the aerosol is preferably in a range of about 0.5 to 5 ⁇ .
• Droplet concentration in the gas stream is preferably less than 10%, for example less than about 1 %.
• Droplet velocity is preferably less than about 10 cm/s.
• Deposition time is preferably in a range of a few seconds to several minutes, for example about 2 seconds to 5 minutes. In a continuous deposition process, where deposition rates are more appropriate measure, deposition rate is preferably in a range of about 1 to 100 nanotubes per second per micron squared.
• Nozzle design may be suitably adjusted to optimize performance.
• nozzle apertures have a minimum dimension greater than about 10x the diameter of the droplet, for example the minimum dimension may be about 10 micron or more.
• nozzle apertures have a minimum dimension determined by the distance to the substrate.
• apertures preferably do not exceed about 0.5-5 mm, respectively, in order to maintain deposition uniformity.
• Nozzle shape is not particularly limited.
• nozzle shape can be simple in "pixelated" deposition (single hole or slit opening), or complex if a pattern is achieved with a single nozzle (e.g. using a shadow mask as nozzle).
• Nozzles are preferably designed so that gas recovery does perturb flow pattern of the aerosol.
• Carrier gases for the aerosol are preferably inert to the solvent, nanoparticles and/or the atmosphere.
• Some non-limiting examples of carrier gases include N 2 , Ar, He and vapors of solvents to control droplet drying and film morphology.
• Electrostatic field intensity is preferably greater than about 100 kV/m, for example about 1 MV/m. Both charged and polarizable nanoparticles may be utilized, and especially with polarizable nanoparticles, it may be useful to also adjust field gradient to optimize deposition of the nanoparticles. Nanoparticles may be charged by the electrostatic field during deposition.
• the substrate is a surface or polymer with water contact angle greater than 80°.
• Such primarily hydrophobic surfaces typically have water contact angles between 85-120°, with particularly useful surfaces having contact angles around 90°+/-5° or between 1 17-120°.
• Such surfaces, or polymers include, but are not limited to: polyvinylidene chloride and polyvinylidene fluoride; polyhexamethylene adipamide (Nylon 66); Nylon 7; poly(dodecano-12-lactam) (Nylon 12); polyamide; cellulose acetate; polysulfone; polymethyl methacrylate; polyvinyl acetate; polycarbonate; polystyrene; polypropylene; polyimide; epoxy; polyethylene terephthalate; silicones; olefins (alkenes); cellulose nitrate; ultrahigh-molecular-weight polyethylene; polychloroprene; polyvinyl chloride; latex; butyl rubber; polytetrafluoroethylene; and poly(p-xylylene) polymers (e.g.
• the hydrophobic surface is a poly(vinylphenol) based dielectric or a polytetrafluoroethylene based dielectric.
• a poly(vinylphenol) based dielectric would be XeroxTM Dielectric xdi-d1 .2 (supplied by the Xerox Research Centre of Canada), whereas an example of polytetrafluoroethylene based dielectric includes: Teflon®-AF.
• the hydrophobic surface is a fluoropolymer, such as the amorphous (non-crystalline) fluoropolymer CyTOP®.
• Such polymers having carbon nanotube networks deposited thereon by the apparatus described above can be used as gate dielectrics in a bottom gate transistor or as an encapsulation layer.
• the transfer characteristics of the material indicate little to no hysteresis (i.e. from 0-1 MV/m, which corresponds to 0-1 V for a 500 nm dielectric with a dielectric constant of 2).
• Aerosol deposition appears to be much less sensitive to surface energy where poor carbon nanotube adherence is found using other deposition methods.
• Xerox Dielectric xdi-d1 .2 supplied by the Xerox Research Centre of Canada
• networks formed readily on polymer layers obtained from spin coating, without surface treatment.
• the Xerox Dielectric comprises a dielectric material and a low surface tension additive (see US Patent No. 8,821 ,962, the contents of which is herein incorporated by reference).
• the low surface tension additive enables the formation of a thin, smooth dielectric layer with fewer pinholes and enhanced device yield.
• the dielectric material comprises a high-k dielectric, Poly(4-vinylphenol) (PVP) and a low-k dielectric, Poly(methyl silsesquioxane) (pMSSQ). Direct comparisons were made with networks on Si0 2 and, except for the hysteresis being larger on Si0 2 , electrical data were similar in many respects (nominal mobility and current On/Off ratio).
• Teflon-AF a 15 minute UV-Ozone exposure (conditions were not optimized) was used to promote carbon nanotube adhesion. The treatment led to minimal change of the water contact angle from 120° to 1 17° (a direct measure of hydrophobicity).
• carbon nanotube adhesion was sufficiently strong for the rinsing steps required to remove excess dispersant in the nanotube ink formulation.
• Transistors fabricated with Xerox Dielectric xdi-d1 .2 and Teflon-AF dielectrics were found to have good performance metrics in terms of hole mobility, On-current and Off-current.
• Transistor transfer characteristics (source-drain conductance versus gate voltage) are shown in FIG.6 and Table 2 summarizes performance numbers obtained from data analysis. In striking contrast with devices on Si0 2 /Si surfaces under similar measurement conditions (and dielectric thicknesses), the magnitude of the hysteresis between forward and reverse gate sweeps are small for both dielectrics. In the case of Xerox Dielectric xdi-d1 .2 (Fig.
• the hysteresis is essentially absent (0.004 ⁇ 0.030 V) with forward and reverse sweeps tracking perfectly on both linear and logarithmic scales.
• the hysteresis is also very small with a value of 0.45 ⁇ 0.02 V.
• two sets of "stress test" measurements were performed. When transistor devices are stressed, large voltages are applied to the gate or source-drain electrode, and electrical data is acquired dynamically. Those results are shown in FIG. 7. In Fig. 7 a) and c), transfer curves are obtained at progressively greater gate voltage sweep ranges.
• V t threshold voltage
• FIG. 7 a) and c) displays V, for forward (F) and reverse (R) sweep direction.
• Teflon-AF is an amorphous fluoropolymer having highly electronegative fluorine atoms. This attribute results in efficient electron withdrawing from the carbon nanotube and easy electron trapping at the Teflon surface. For holes however, a deep HOMO level would prevent significant bias stress for negative gate voltages.
• the second "stress test” consisted of measuring the time evolution of conductance while the transistor is being subsequently switched between its "On" and "Off state.
• V G within the ⁇ 20 V range was looked at where the hysteresis remained quite small.
• the time evolution in FIG. 7b displays six consecutive switch- Offs where V G takes different values from 0 to 20 V, corresponding to various degrees of stress in the Off state.
• the effect of V G > 0 was studied since that's where the hysteresis growth is most pronounced (asymmetry in FIG. 4a and inset).
• SWCNT networks are assembled on top of hydrophobic polymer dielectrics: the absence of hysteresis and time stability, particularly in the device's On-state.
• the absence of hysteresis and the robustness to stress tests indicate first that the polymers, the major component of the formulation, perform well as dielectrics, with a low level of dynamic charge traps. This is expected considering they are formulated for use as dielectrics in electronics applications, but it should be noted that many publications using PVP as a dielectric do not provide the same performance attributes that were observed with the Xerox Dielectric xdi-d1 .2 formulation.
• crosslinking chemistry and the layering property of the polymer blend have a significant effect on device performance and is a good match with semiconducting-SWCNT as the semiconducting channel. These results should serve as a guide to obtain robust bottom gate devices using normal processing in air ambient and Xerox Dielectric xdi-d1 .2 represents a practical route to using established printing techniques and simple processes (conventional solvents).
• FIG. 8 shows a transfer characteristic with V, near 0 V. Although the On/Off ratio measured at 0 V is poor ( ⁇ 4) for un-encapsulated devices in air ambient, it improves to 10 2 after encapsulation.
• Aerosol processes of the present invention are compatible with shadow masking. Although mask fabrication can prove useful, it is technologically more desirable to have a process capable of producing patterns in a maskless fashion.
• FIG. 9 shows three examples of how this is possible by engineering both the gas flow and the electrostatic field.
• FIG. 9a demonstrates how tightly the electrostatic field can focus the material. Optically, it can be seen that the stripes deposited at the highest voltages appear very sharp with dimensions well under a millimeter.
• FIG. 9b presents a Raman intensity profile taken across a stripe and reveals a FWHM (Full-width at half-maximum) of 100 ⁇ . Even with the overspread of material beyond 200 ⁇ , transistors with channel width below 150 ⁇ can be fabricated using a simple slit-shape nozzle. Patterning in the transverse direction can also be achieved by using a nozzle comprising multiple holes. An example of such a deposition is shown in FIG. 4c. Individual islands of material as well as lines can be obtained with dimensions of order 500 ⁇ .
• FIG. 9d shows one example of carbon nanotube islands deposited on a thin nylon film.
• the mask is a TeflonTM slab with copper wire inclusions connected to ground.

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