Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G61/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
  • C08G61/12—Macromolecular compounds containing atoms other than carbon in the main chain of the macromolecule
  • C08G61/122—Macromolecular compounds containing atoms other than carbon in the main chain of the macromolecule derived from five- or six-membered heterocyclic compounds, other than imides
  • C08G61/123—Macromolecular compounds containing atoms other than carbon in the main chain of the macromolecule derived from five- or six-membered heterocyclic compounds, other than imides derived from five-membered heterocyclic compounds
  • C08G61/126—Macromolecular compounds containing atoms other than carbon in the main chain of the macromolecule derived from five- or six-membered heterocyclic compounds, other than imides derived from five-membered heterocyclic compounds with a five-membered ring containing one sulfur atom in the ring
• • 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
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G2261/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
  • C08G2261/10—Definition of the polymer structure
  • C08G2261/14—Side-groups
  • C08G2261/141—Side-chains having aliphatic units
  • C08G2261/1412—Saturated aliphatic units
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G2261/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
  • C08G2261/30—Monomer units or repeat units incorporating structural elements in the main chain
  • C08G2261/32—Monomer units or repeat units incorporating structural elements in the main chain incorporating heteroaromatic structural elements in the main chain
  • C08G2261/322—Monomer units or repeat units incorporating structural elements in the main chain incorporating heteroaromatic structural elements in the main chain non-condensed
  • C08G2261/3223—Monomer units or repeat units incorporating structural elements in the main chain incorporating heteroaromatic structural elements in the main chain non-condensed containing one or more sulfur atoms as the only heteroatom, e.g. thiophene

Definitions

• the CRT is also unsuited to use in large area displays eg. in stadia and
• the liquid crystal display provides an alternative which is not subject
• row and column electrodes is typically provided, in addition to the anode, and in this
• Known FEDs typically utilise cathodes having on their surface an array of
• Electrons may be released from such a material by relatively small electric
• DLC diamond carbon
• Nitrogen acts as a donor fostering the formation of a high field depletion region.
• high field region promotes transfer of electrons from substrate to film.
• cathode should be capable - 4 - of manufacture in suitable form for use in a field emission display.
• field emission cathode comprising polymer material forming a field emission surface.
• Polymer materials can be manufactured giving high electron emission.
• the polymer is a conjugated polymer material.
• Conjugated polymers typically have high density of free electrons. Most polymer
• the substrate of the cathode can itself
• photocopiers, photodetectors and thin film transistors - do not require the material to
• the polymer material is a substituted - 5 - polythiophene, and polyalkylthiophenes are particularly suitable.
• octylthiophene is currently the preferred material.
• the polymer material may take the form of a layer on a substrate. It is
• the polymer layer is formed as a film with thickness of the
• the polymer material is preferably spun from a liquid source or is evaporated
• the polymer material should have a low barrier to
• the polymer material may be doped with an electron donor material
• electron donor may be nitrogen (known to reduce the barrier to electrons of the
• un-doped polymers have relatively low
• the polymer material may have energy levels which trap electrons serving
• the polymer material forms a film on a substrate comprising
• microcrystalline silicon The grain boundaries at the polysilicon surface trap large
• mould as used throughout this specification.
• moulding is to be correspondingly construed.
• emission surface can be shaped such as to promote field emission, eg. by forming tips
• emitted electrons may be insufficiently
• invention comprises a grid positioned with respect to the cathode such as to be
• the polymer material may be any of the polymer materials referred to above
• Fig. 1 is a graph of normalised or average field emission current density (on
• Fig. 2a is a graph of normalised field emission current density from a cathode
• Fig. 2b is a graph of normalised field emission current density from a cathode
• Fig. 3 is a graph of field emission current from a cathode according to the
• Fig. 4 shows band diagrams for a cathode according to the present invention
• Fig. 5 shows band diagrams for a cathode according to the present invention
• Fig. 6 is a band diagram representing a model for the field emission of
• Fig. 7 represents a simple model of field emission from a cathode according
• Fig. 8 schematically illustrates energy levels in the region of a void of the
• Fig. 9 is a graph of predicted field emission current (in a logarithmic scale as
• Fig. 10 illustrates a step in the process of moulding a polymer layer of a
• cathode according to the present invention, the cathode and mould being seen in cross section;
• Fig. 11 illustrates in cross section a structure of a display device constructed
• Fig. 12 illustrates in cross section a further structure of a display device
• cathode formed as a thick (5 ⁇ m), spin-cast, nominally undoped polymer
• P3OT can be synthesised in pellets by the technique reported in Chen, T-
• chloroform has been used as a solvent: dissolving 5mg of P3OT
• the optical Tauc bandgap was determined, at room temperature, to be - 1 J5eV by
• I-N current-voltage
• Regions la and lb represent the emission before
• conditioning and region 2 is after conditioning.
• Fig. 2a shows the J-F characteristics as a function of anode-cathode spacing.
• Fig. 2a versus gap separation is shown in Fig. 2a inset and indicates a nonlinear relationship.
• the surface morphology of the film was examined by scanning electron
• the polymer films show void-like features on the
• the inventors also examined the stability of the emission current over time.
• the emission characteristic recorded over a 16 hour period of continuous emission - 12 - is shown in Fig. 3.
• the initial current drops to 55% of its value in 2 hours, and
• n-Si barrier is a reasonably efficient injector - 13 - of electrons, that the effective lifetime of electrons in the polymer is, for minority
• FIG. 7 shows the proposed model in its simplest form.
• the electron density falls with distance from the silicon cathode, whilst the field
• ⁇ is the field intensification multiplier just outside the polymer surface.
• the lip will act as an effective intensifier of the field.
• the inventors have speculated that the voids in the polymer film may be
• the polymer film may be shaped against a mould.
• the polymer material may be cast or centrifugally spun and thereby
• a female mould seen at 100 in Fig. 10, is then pressed
• the substrate is seen at 104.
• Polymers can be well suited to moulding processes.
• the mould is shaped to form in the polymer a
• cathode is a flat film 2 of polymer material disposed on a conducting substrate 3
• An anode 4 is provided in front of the cathode,
• pixels 5 of a material which emits light when struck by energetic
• the anode may consist of a light emitting
• a grid 6 which can be
• the space 7 between the anode and the cathode is a
• FIG. 12 A more detailed illustration of a suitable device structure is given in Fig. 12.
• the cathode is formed by a shaped polymer layer 52 on a substrate 54 which
• Spacers 56 separate the cathode from a conducting grid 58,
• the anode 62 is maintained at - 17 - a higher voltage to accelerate the electrons sufficiently to cause the phosphor to

Landscapes

• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
• Devices For Indicating Variable Information By Combining Individual Elements (AREA)
• Electrodes For Cathode-Ray Tubes (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)

Priority Applications (6)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10828430

Family Applications (1)

Country Status (8)

Cited By (3)

Families Citing this family (4)

Citations (5)

Family Cites Families (3)

• 1998
  • 1998-03-13 GB GBGB9805271.5A patent/GB9805271D0/en not_active Ceased
• 1999
  • 1999-03-15 AT AT99910492T patent/ATE218750T1/de not_active IP Right Cessation
  • 1999-03-15 WO PCT/GB1999/000765 patent/WO1999048122A1/en not_active Ceased
  • 1999-03-15 US US09/646,032 patent/US6853127B1/en not_active Expired - Fee Related
  • 1999-03-15 JP JP2000537237A patent/JP2002507821A/ja active Pending
  • 1999-03-15 EP EP99910492A patent/EP1062676B1/en not_active Expired - Lifetime
  • 1999-03-15 AU AU29431/99A patent/AU2943199A/en not_active Abandoned
  • 1999-03-15 DE DE69901693T patent/DE69901693T2/de not_active Expired - Fee Related

Patent Citations (5)

Non-Patent Citations (4)

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