JP4914828B2 - Gate insulating film, organic transistor, organic EL display device manufacturing method, display - Google Patents

Description

  The present invention relates to a gate insulating film manufacturing method, an organic transistor manufacturing method, an organic EL display device manufacturing method, and a display.

  Organic thin film transistors (hereinafter also referred to as organic film transistors) are used for various applications. For example, organic TFTs have been studied as means for driving organic EL elements in organic EL display devices.

  An organic EL device includes an electrode and an organic solid layer having at least a light emitting layer between the electrodes, and injects electrons and holes from the electrodes on both sides into the light emitting layer in the organic solid layer. It is an element that causes light emission, and can emit light with high brightness. In addition, since it uses light emission of an organic compound, it has characteristics such as a wide selection range of emission colors, and is expected as a light source or an organic EL display device. In particular, an organic EL display device is generally expected as a flat panel display having a wide field of view, high contrast, high-speed response and visibility, thin and light, and low power consumption.

  The organic EL display device includes a pixel composed of an organic EL element including at least an anode, an organic light emitting layer, and a cathode, and an organic transistor that lights and controls the organic EL element. In an organic EL display device, a passive matrix system in which organic EL elements arranged in a matrix are driven from the outside by stripe-shaped scanning electrodes and data electrodes (signal electrodes) orthogonal to each other, and a switching element composed of an organic transistor for each pixel And an active matrix system in which an organic EL element is lit.

  In general, an active matrix method using an organic transistor is superior to an active matrix method in which an organic EL element is driven by a TFT as compared with a passive matrix method as the number of pixels increases. This is because in the passive matrix method, the organic EL element of each pixel is lit only during the period when the scanning electrode is selected, and as the number of pixels increases, the lighting period of the organic EL element becomes shorter and the average luminance tends to decrease. On the other hand, the active matrix system has a switching element and a memory element made up of TFTs for each pixel, so that the lighting state of the organic EL element is maintained, and operation with high brightness, high efficiency and long life is possible. This is because the display tends to be advantageous for high definition and large size.

  FIG. 1 shows an organic EL display device PA according to the background art. The organic EL display device PA includes a substrate 10, a barrier film 12 formed on the substrate 10, an organic EL element 100 and an organic TFT 50 formed on the barrier film 12, and a protection covering the organic EL element 100 and the organic TFT 50. A film (passivation film) 20.

  In the organic TFT 50, the source electrode 58 and the drain electrode 60 are provided separately from each other, the organic semiconductor layer 56 is interposed between the source electrode 58 and the drain electrode 60, and the source electrode 58 and the drain are interposed via the gate insulating film 54. In this structure, the electrode 60 and the gate electrode 52 are disposed so as to face the organic semiconductor layer 56.

  The performance of the organic TFT itself is often about the same as that of an amorphous silicon TFT. However, the performance of the organic TFT is low if it has a certain on / off ratio for use as a liquid crystal or electrophoretic drive element. Since current driving is possible, there are many cases where there is no problem of ensuring insulation in the gate insulating film.

On the other hand, in order to drive an organic EL element which is a self-luminous element by an active matrix system, a transistor capable of supplying a large current is required to emit light. Therefore, development of an organic TFT that uses a material having a high relative dielectric constant such as Ta ₂ O ₅ as a gate insulating film and can supply a large current due to many carriers that are attracted and generated is underway.

On the other hand, since there are various advantages, a method of forming a gate insulating film by a printing technique in which a coating liquid is applied to the surface of a material to be coated and solidified to form a gate insulating film has been studied. In order to form a gate insulating film having a high relative dielectric constant by a printing technique, selection of a coating film that becomes a gate insulating film after solidification becomes a problem. As the coating film, since the binder resin alone generally does not tend to have a high relative dielectric constant, a coating film containing a high relative dielectric constant material having a higher relative dielectric constant than the binder resin is employed. Patent Document 1 listed below includes a method in which metal oxide particles having a high relative dielectric constant are simply dispersed in a binder resin.
JP 2002-110999 A

  However, when the gate insulating film is formed with a coating solution in which metal oxide particles are simply dispersed in a binder resin as in Patent Document 1, a problem may occur due to the metal oxide particles contained therein. For example, the metal oxide particles protruding from the surface of the gate insulating film may cause the surface of the gate insulating film to become rough and cause the performance of the organic TFT to deteriorate.

  Therefore, it is conceivable to use a polymer having a high relative dielectric constant and having a cyanoethyl group alone or in a mixture with other polymers.

  However, when a polymer having a cyanoethyl group is used alone, there is a problem in solvent resistance when an etching solvent or a coating type organic semiconductor is used in a transistor manufacturing process such as photolithography or etching. There may be.

  In addition, when a polymer having a cyanoethyl group is mixed with another curable polymer, the solvent resistance is improved, but the compatibility is poor and phase separation may occur. As described above, a high-quality gate insulating film may not be provided.

  The present invention has been made in view of the above problems, and provides a manufacturing method of a higher quality gate insulating film, a manufacturing method of a higher performance organic transistor, a manufacturing method of an organic EL display device, and a display. Main purpose.

  The invention according to claim 1 is a method for producing a gate insulating film in an organic transistor, and includes a step of thermally curing a mixture containing a mixed polymer containing a cyanoethyl group and a hydroxyl group and a melamine derivative. It is characterized by.

  Invention of Claim 3 is a manufacturing method of the organic transistor containing a gate insulating film, Comprising: The said gate insulating film is an organic transistor manufactured by the manufacturing method of the gate insulating film of Claim 1 or 2 Manufacturing method.

  Invention of Claim 4 is a manufacturing method of the organic electroluminescent display apparatus containing the organic transistor which drives the organic electroluminescent element which drives the said organic electroluminescent element and an organic electroluminescent element provided with an anode, an organic light emitting layer, and a cathode, It is manufactured by the method for manufacturing an organic transistor according to claim 3.

  The invention described in claim 5 is a display including an organic transistor manufactured by the method for manufacturing an organic transistor according to claim 3.

It is typical sectional drawing of the organic electroluminescence display in a prior art. It is typical sectional drawing of the organic TFT in a prior art. It is typical sectional drawing of the organic electroluminescence display in this embodiment. It is a typical enlarged view near the organic EL element of the organic EL display device in the present embodiment. It is a typical enlarged view near organic TFT of the organic electroluminescence display in this embodiment. It is typical explanatory drawing of the manufacturing method of the gate insulating film in this embodiment. It is typical explanatory drawing of the manufacturing method of the gate insulating film in this embodiment. It is typical explanatory drawing of the manufacturing method of the gate insulating film in this embodiment.

Explanation of symbols

10 Substrate 16 Organic solid layer 18 Cathode 20 Protective film 50 Organic TFT
54 Gate insulating film 100 Organic EL element P1, PA Organic EL display device

"Improvement of gate insulating film manufacturing process"
This inventor examined the gate insulating film produced by mixing a polymer having a cyanoethyl group with another polymer. As described above, the cyanoethylated resin has poor compatibility with the solvent and may cause phase separation, which may lead to deterioration of the gate insulating film. In addition, the polymer having a cyanoethyl group has poor solvent resistance and may be affected by the solvent when etching solvent or a coating type organic semiconductor is used, leading to deterioration of the gate insulating film.
The present inventor has come to consider using a crosslinking reaction in order to improve the compatibility of the cyanoethylated resin. For example, resins such as polyvinyl alcohol (PVA: the following chemical formula (1)), polyvinylphenol (PVP: the following chemical formula (2)), and polyphenol resin are melamine derivatives (the following chemical formula (3): melamine-formaldehyde resin as an example thereof) Since the resin is cured by crosslinking reaction with heat, the compatibility with these resins is good. However, resins such as polyvinyl alcohol, polyphenol resin, and polyvinyl phenol are difficult to secure a sufficient dielectric constant, and it is conceivable to use a polymer having a cyanoethyl group instead.

However, as described above, a melamine derivative undergoes a crosslinking reaction with a resin such as a polyphenol resin or polyvinylphenol, whereas a cyanoethyl pullulan or polystyrene having a cyanoethyl group does not undergo a crosslinking reaction with a melamine derivative.

  This is considered that the present inventors consider as an example, that in the case of polyvinylphenol and polystyrene, the hydroxyl group is involved in the melamine derivative and the crosslinking reaction because the substituent is only the difference in the presence or absence of the hydroxyl group. In the case of cyanoethyl pullulan or polystyrene having a cyanoethyl group, it is considered that a crosslinking reaction with a melamine derivative does not occur because it does not have a hydroxyl group.

  In view of the above, as a result of intensive investigations, the present inventor has found that, for polymers having a hydroxyl group, a part of the hydroxyl group is partially converted to a cyanoethyl group, or for a polymer having a cyanoethyl group, a part of the cyanoethyl group is partially The present inventors have found that a mixed polymer in which a cyanoethyl group and a hydroxyl group are mixed (hereinafter, also simply referred to as a mixed polymer) is used to make use of the advantages of both a cyanoethyl group and a hydroxyl group.

  That is, the present inventors have attempted to increase the relative dielectric constant with a cyanoethyl group and find that the solvent resistance and compatibility are improved because the hydroxyl group promotes the crosslinking reaction with the melamine derivative while ensuring the high relative dielectric constant. Further, the gate insulating film having a relative dielectric constant of 7 to 40 is particularly preferable because the dielectric constant can be secured, hysteresis is prevented, and electrical properties are stabilized.

  As a result, it was possible to provide a higher quality gate insulating film, and to find a high-performance organic transistor including the gate insulating film and a method for manufacturing an organic EL display device including the organic transistor and a display.

"Organic EL display device"
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, about this embodiment, it is only one form for implementing this invention, and this invention is not limited by this embodiment.

  FIG. 3 is a schematic cross-sectional view of the organic EL display device P1 according to this embodiment. The organic EL display device P <b> 1 covers the film substrate 10, the barrier film 12 formed on the substrate 10, the organic EL element 100 and the organic TFT 50 formed on the barrier film 12, and the organic TFT 50. And a protective film 20 that protects the organic TFT 50 from erosion from the outside.

<Board>
The substrate 10 may be formed by appropriately selecting the constituent materials. For example, as the resin, thermoplastic resin, thermosetting resin, polycarbonate, polymethyl methacrylate, polyarylate, polyether sulfone, polysulfone, polyethylene terephthalate polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride, Polystyrene, polyamide, polyimide, polyvinylidene chloride, polyvinyl alcohol, saponified ethylene / vinyl acetate copolymer, fluororesin, chlorinated rubber, ionomer, ethylene / acrylic acid copolymer, ethylene / acrylic acid ester copolymer, etc. A simple substrate can be used. Further, instead of a substrate mainly composed of a resin, a glass substrate or a bonded substrate of glass and plastic may be used, and an alkali barrier film or a gas barrier film may be coated on the substrate surface. Further, in the case of a top emission type in which light is emitted from the opposite side to these transparent substrates, the substrate 10 does not necessarily have to be transparent.

<Barrier film>
The barrier film 12 is not necessarily formed, but is preferably formed because it can be protected from erosion due to moisture, oxygen, or the like from the substrate side. In the case of forming the barrier film 12, materials can be appropriately selected and used.

  The barrier film 12 may have a multilayer structure, a single layer structure, an inorganic film, or an organic film. When an inorganic film is included, the barrier film 12 is caused by moisture, oxygen, or the like. This is preferable because the barrier property against erosion is improved.

As the inorganic film, for example, a nitride film, an oxide film, a carbon film, a silicon film, or the like can be adopted. More specifically, a silicon nitride film, a silicon oxide film, a silicon oxynitride film, or diamond-like carbon (DLC) ) Film and amorphous carbon film. That is, nitrides such as SiN, AlN and GaN, oxides such as SiO, Al ₂ O ₃ , Ta ₂ O ₅ , ZnO and GeO, oxynitrides such as SiON, carbonitrides such as SiCN, metal fluorine compounds, Examples thereof include metal films.

Examples of the organic film include a furan film, a pyrrole film, a thiophene film, a polyparaxylene film, an epoxy resin, an acrylic resin, polyparaxylene, a fluorine-based polymer (perfluoroolefin, perfluoroether, tetrafluoroethylene, chlorotriethylene). Fluoroethylene, dichlorodifluoroethylene, etc.), metal alkoxides (CH ₃ OM, C ₂ H ₅ OM, etc.), polyimide precursors, polymer films such as perylene compounds, and the like.

The barrier film 12 is a laminated structure composed of two or more substances, an inorganic protective film, a silane coupling layer, a laminated structure composed of a resin sealing film, a barrier layer composed of an inorganic material, and a laminated structure composed of a cover layer composed of an organic material. , Si-CXHY, etc., a compound of a metal or semiconductor and an organic substance, a laminated structure made of an inorganic substance, a structure in which an inorganic film and an organic film are alternately laminated, a structure in which SiO ₂ or Si ₃ N ₄ is laminated on a Si layer, etc. The thing made into the laminated structure is mentioned.

<Organic EL device>
FIG. 4 shows an enlarged view of the vicinity of the organic EL element 100 of the organic EL display device P1. The organic EL element 100 is formed by laminating an anode 14 / an organic solid layer 16 / a cathode 18 from the barrier film 12 side.

  The anode 14 may be a layer having an energy level at which holes can be easily injected. A transparent electrode such as ITO (Indium tin oxide) can be used, but the organic EL display device is a top emission type. In this case, a general electrode may be used instead of the transparent electrode.

  A transparent conductive material such as ITO is formed to a thickness of, for example, 150 nm by sputtering or the like. Instead of ITO, a zinc oxide (ZnO) film, IZO (indium-zinc alloy) gold, copper iodide, or the like may be employed instead.

  The organic solid layer 16 includes a hole injection layer 162 / a hole transport layer 164 / a light emitting layer 166 / an electron transport layer 168 from the anode 14 side.

  The hole injection layer 162 is a layer that is provided between the anode 14 and the light emitting layer 166 and promotes injection of holes from the anode 14. With the hole injection layer 162, the driving voltage of the organic EL element 100 can be lowered. Also, it may play a role such as stabilizing hole injection and extending the life of the element, or covering an uneven surface such as a protrusion formed on the surface of the anode 14 to reduce element defects. is there.

  The material of the hole injection layer 162 may be appropriately selected so that the ionization energy is between the work function of the anode 14 and the ionization energy of the light emitting layer 166. For example, triphenylamine tetramer (TPTE), copper phthalocyanine, and the like can be used.

  The hole transport layer 164 is a layer that is provided between the hole injection layer 162 and the light emitting layer 166 and promotes the transport of holes, and has a function of appropriately transporting holes to the light emitting layer 166.

  The material of the hole transport layer 164 may be appropriately selected so that the ionization energy is between the hole injection layer 162 and the light emitting layer 166. For example, TPD (triphenylamine derivative) can be employed.

  The light emitting layer 166 is a layer that recombines the transported holes and the transported electrons, which will be described later, to emit fluorescence or phosphorescence. The material of the light-emitting layer 166 may be selected as appropriate so as to satisfy the properties corresponding to the above light-emitting modes. For example, tris (8-quinolinolato) aluminum complex (Alq), bis (benzoquinolinolato) beryllium complex (BeBq), tri (dibenzoylmethyl) phenanthroline europium complex (Eu (DBM) 3 (Phen)), ditoluyl Vinyl biphenyl (DTVBi), poly (p-phenylene vinylene), π-conjugated polymers such as polyalkylthiophene, and the like can be used. For example, an aluminum quinolinol complex (Alq3) can be used to emit green light.

  For example, in a phosphorescent device, when electrons and holes are injected from the cathode 18 and the anode 14 respectively into the phosphorescent layer 166 and recombined there, recombination energy is supplied to the dopant material through the host material. This dopant emits phosphorescence. Here, under conditions where the injection current density is low, this phosphorescent organic EL element can emit red light due to the dopant. In addition, under conditions where the injection current density is high, the host material according to the present invention having a light emitting function also emits light, and a colored light of the emission color of the host material and the emission color of the dopant material can be obtained. For example, when a compound that emits light blue is used, the dopant emits red light. Therefore, in this organic EL element, white light in which light blue and red are synthesized can be emitted to the outside.

  The electron transport layer 168 is provided between the cathode 18 and the light emitting layer 166 and has a function of promoting the injection of electrons from the cathode 18, and lowers the driving voltage of the organic EL element 100. In addition, there are cases where the electron injection is stabilized and the device has a long life, the adhesion between the cathode 18 and the light emitting layer 166 is enhanced, the uniformity of the light emitting surface is improved, and the device defects are reduced.

The material of the electron transport layer 168 may be appropriately selected so as to be between the work function of the cathode 18 and the electron affinity of the light emitting layer 166. For example, the electron transport layer 168 may be a thin film (for example, 0.5 nm) such as LiF or LiO ₂ (lithium dioxide).

  Each layer constituting the organic solid layer 16 is usually made of an organic material, and may be made of a high molecular weight organic material when it is made of a low molecular weight organic material. Organic functional layers composed of low molecular weight organic materials are generally processed by a dry process (vacuum process) such as vapor deposition. Organic functional layers composed of high molecular weight organic materials are generally processed by spin coating, blade coating, dipping, spraying, and printing. Each can be formed by a wet process.

  Examples of the organic material used for each layer constituting the organic solid layer 16 include polymer materials such as PEDOT, polyaniline, polyparaphenylene vinylene derivative, polythiophene derivative, polyparaphenylene derivative, polyalkylphenylene, and polyacetylene derivative.

  In the present embodiment, the organic solid layer 16 includes a hole injection layer 162, a hole transport layer 166, a light emitting layer 166, and an electron transport layer 168. However, the organic solid layer 16 is not limited to this configuration. The light-emitting layer 166 may be included at least.

  For example, depending on the characteristics of the organic material used, etc., in addition to a single layer structure of the light emitting layer, etc., a two-layer structure such as a hole transport layer / light emitting layer, light emitting layer / electron transport layer, etc., hole transport layer / light emitting layer / A three-layer structure of an electron transport layer, or a multilayer structure including a charge (hole, electron) injection layer and the like.

  Further, a hole blocking layer may be provided between the light emitting layer 166 and the electron transport layer 168 in the organic solid layer 16. The holes may pass through the light emitting layer 166 and reach the cathode 18. For example, when Alq3 or the like is used for the electron transport layer 168, the holes may flow into the electron transport layer so that the Alq3 emits light or the holes cannot be confined in the light emitting layer, resulting in a decrease in light emission efficiency. There is sex. Therefore, a hole blocking layer may be provided to prevent holes from flowing out from the light emitting layer 166 to the electron transporting layer 168.

  For the cathode 18, a material having a small work function or electron affinity may be selected in order to improve electron injection into the organic solid layer 16. For example, an alloy type (mixed metal) such as an Mg: Ag alloy or an Al: Li alloy can be suitably used. The cathode 18 can be formed by vacuum deposition or the like of a metal material such as Al or MgAg to a thickness of 150 nm, for example.

<Organic transistor (organic TFT)>
FIG. 5 shows an enlarged view of the vicinity of the organic TFT 50 of the organic EL display device P1. The organic TFT 50 includes a gate electrode 52 formed on the barrier film 12 from the barrier film 12 side, and a gate insulating film 54 formed so as to cover the surface of the gate electrode 52. On the gate insulating film 54, an organic semiconductor layer 56, a source electrode 58 on the left edge side, and a drain electrode 60 on the right edge side are formed. Here, the drain electrode 60 is electrically connected to the anode 14 of the organic EL element 100. That is, in the organic TFT 50, the source electrode 58 and the drain electrode 60 are provided separately from each other, the organic semiconductor layer 56 is interposed between the source electrode 58 and the drain electrode 60, and the source electrode 58 is interposed via the gate insulating film 54. , A drain electrode 60, and a gate electrode 52 disposed to face the organic semiconductor layer 56.

  The gate electrode 52 may be any metal that can be anodized as a gate electrode material, and a single substance such as Al, Mg, Ti, Nb, Zr, or an alloy thereof may be used, but is not limited thereto. The gate electrode only needs to have sufficient conductivity. For example, Pt, Au, W, Ru, Ir, Al, Sc, Ti, V, Mn, Fe, Co, Ni, Zn, Ga, Y, Zr, Nb, Mo, Tc, Rh, Pd, Ag, Cd, Ln, Sn, Ta, Re, Os, Tl, Pb, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, A single metal such as Er, Tm, Yb, or Lu, or a laminate or a compound thereof may be used. Alternatively, an organic conductive material containing a conjugated polymer compound such as metal oxide particles such as ITO and IZO, polyanilines, polythiophenes, and polypyrroles may be used.

  The manufacturing method of the gate electrode 52 may be a general method for forming the wiring pattern of the gate electrode 52 on the substrate 10. A sputtering method, a CVD method, and the like can be given, but there is no particular limitation, and an appropriate method may be used. For example, general thin film forming methods such as vacuum deposition, ion plating, sol-gel method, spin coating method, spray method, and CVD are also possible.

  For the gate insulating film 54, a part of the hydroxyl group is partially cyanoethyl group for a polymer having a hydroxyl group, or a part of the cyanoethyl group is partially hydroxyl group for a polymer having a cyanoethyl group. A mixed solution of a mixed polymer containing cyanoethyl groups and hydroxyl groups (hereinafter also simply referred to as a mixed polymer) and a melamine derivative is applied and thermally cured.

  The mixed polymer is not particularly limited as long as it has a partial cyanoethyl group and a partial hydroxyl group. Moreover, it does not prevent that mixed polymer contains groups other than a cyanoethyl group and a hydroxyl group.

  For example, as the polymer constituting the gate insulating film 54, polyvinyl phenol and polyvinyl alcohol, starch and derivatives thereof, cellulose derivatives such as ethyl cellulose, methoxy cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, pullulan, sorbitol, phenoxy resin And a polyphenol resin and the like, which are partially added with a cyanoethyl group.

  For example, the polyphenol resin can be obtained by reacting phenols and aldehydes in a proportion of 1 to 3 moles with respect to 1 mole of phenolic hydroxyl group under a basic catalyst or an acidic catalyst.

  Examples of phenols include phenol, cresol, xylenol, octylphenol, phenylphenol, bisphenol A, bisphenol S, and bisphenol F. Examples of aldehydes include formaldehyde, paraformaldehyde, glyoxal, and trioxal.

  In addition, those modified with a modifying agent that promotes plasticization such as paratoluene sulfonamide, tung oil, phosphoric esters, glycols, etc. can be applied as necessary, and basic catalysts include alkali metals such as sodium and potassium, And oxides and hydroxides of alkaline earth metals such as magnesium and calcium, amines such as triethylamine and triethanolamine, and ammonia. Examples of acidic catalysts include paratoluenesulfonic acid and hydrochloric acid.

  The melamine derivative only needs to have good compatibility with the polymer and can be dissolved in the same solvent as the partially cyanoethylated polymer. As the melamine derivative, a methylated polymelamine-formaldehyde copolymer is used, and as the melamine derivative, there are a methylolated, acrylated, butylated, isobutylated polymelamine-formaldehyde copolymer, and the like. For example, synthesis obtained by cocondensation of triazines and formaldehydes such as methylolated melamine resin, methylolated melamine-phenol cocondensation resin, methylolated melamine-urea cocondensation resin, methylolated melamine-epoxy cocondensation resin Resins can be used.

  Although the gate insulating film 54 is formed of the mixed polymer, it does not prevent mixing of other polymers such as thermoplastic resin and thermosetting resin and metal oxide particles. These can be appropriately selected and used in combination with the mixed polymer.

  Further, it is preferable that the other polymer mixed here has a high relative dielectric constant. For example, examples of the organic polymer or oligomer material having a high relative dielectric constant include cyanoethyl cellulose (relative dielectric constant 16), cyanoethyl hydroxyethyl cellulose (relative dielectric constant 18), cyanoethyl hydroxypropyl cellulose (relative dielectric constant 14), and cyanoethyl. Dihydroxypropyl cellulose (dielectric constant 23), cyanoethyl amylose (dielectric constant 17), cyanoethyl starch (dielectric constant 17), cyanoethyl dihydroxypropyl starch (dielectric constant 18), cyanoethyl pullulan (dielectric constant 18), cyanoethyl glycidol Pullulan (dielectric constant 20), cyanoethyl polyvinyl alcohol (dielectric constant 20), cyanoethyl polyhydroxymethylene (dielectric constant 10), cyanoethyl sucrose (dielectric constant 25), cyanoethyl Cyanoethyl group-containing polymer or oligomer such as sorbitol (relative dielectric constant 40), polyvinylidene fluoride (relative dielectric constant 11), vinylidene fluoride-trifluoroethylene copolymer (55/45: relative dielectric constant 18, 75/25 : Vinylidene polymers such as relative dielectric constant 10).

  Furthermore, it is preferable to mix a thermosetting resin. Examples of the thermosetting resin include polyurethane, phenol resin, melamine resin, urea resin, unsaturated polyester resin, diallyl phthalate resin, silicon resin, and epoxy resin. For example, as an example of epoxy resin, bisphenol-A type epoxy resin, bisphenol-F type epoxy resin, bisphenol-AD type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, cyclic aliphatic epoxy resin, glycidyl ester resin Glycidylamine epoxy resin, heterocyclic epoxy resin, urethane-modified epoxy resin, brominated bisphenol-A type epoxy resin, and the like.

The metal oxide particles can be appropriately selected and used. For example, the metal oxide contained in the metal oxide particles can be appropriately selected and used, and is not particularly limited. For example, Ta ₂ O ₅ , TiO ₂ , ZrO ₂ , BaTiO ₃ , PbTiO ₃ , CaTiO _3. MgTiO ₃ , BaZrO ₃ , PbZrO ₃ , SrZrO ₃ , CaZrO ₃ , LaTiO ₃ , LaZrO ₃ , BiTiO ₃ , LaPbTiO ₃ , Y ₂ O _3, etc., or a solid solution such as thorium, barium Strontium titanate, barium titanate, lead titanate, calcium titanate, magnesium titanate, barium zirconate titanate, lead zirconate titanate, lead zirconate, barium zirconate, strontium zirconate, calcium zirconate And the like. In addition, composite oxide particles such as lead lanthanum zirconate titanate, lead lanthanum titanate, bismuth titanate, lanthanum titanate, barium magnesium fluoride, titanium dioxide, tantalum pentoxide, yttrium trioxide, etc. A metal oxide particle is mentioned. Only one type of these metal oxide particles may be used, or a plurality of types may be used in combination.

  The source electrode 58 and the drain electrode 60 may be made of a simple substance such as Al, Mg, Ti, Nb, Zr, or an alloy thereof, but is not limited thereto. The gate electrode only needs to have sufficient conductivity. For example, Pt, Au, W, Ru, Ir, Al, Sc, Ti, V, Mn, Fe, Co, Ni, Zn, Ga, Y, Zr, Nb, Mo, Tc, Rh, Pd, Ag, Cd, Ln, Sn, Ta, Re, Os, Tl, Pb, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, A single metal such as Er, Tm, Yb, or Lu, or a laminate or a compound thereof may be used. Alternatively, an organic conductive material containing a conjugated polymer compound such as metal oxide particles such as ITO and IZO, polyanilines, polythiophenes, and polypyrroles may be used.

  The source electrode 58 and the drain electrode 60 may be manufactured by a general method. A sputtering method, a CVD method, and the like can be given, but there is no particular limitation, and an appropriate method may be used. For example, a general thin film forming method such as vacuum deposition, ion plating, sol-gel method, spray method, spin coating method, CVD, lift-off, or the like is also possible.

  The organic semiconductor 56 may be any organic material that exhibits semiconductor characteristics, such as pentacene, and is not particularly limited. For example, phthalocyanine derivatives, naphthalocyanine derivatives, azo compound derivatives, perylene derivatives, indigo derivatives, quinacridone compounds, and the like. Derivatives, polycyclic quinone derivatives such as anthraquinones, cyanine derivatives, fullerene derivatives, or nitrogen-containing compounds such as indole, carbazole, oxazole, inoxazole, thiazole, imidazole, pyrazole, oxadiazole, pyrazoline, thiathiazole, triazole Cyclic compound derivatives, hydrazine derivatives, triphenylamine derivatives, triphenylmethane derivatives, stilbenes, quinone compound derivatives such as anthraquinone diphenoquinone, anthracene, bilene, fluoro Polycyclic aromatic compound derivatives such as nanthrene and coronene whose structure is used in the main chain of polymer such as polyethylene chain, polysiloxane chain, polyether chain, polyester chain, polyamide chain, polyimide chain, etc. Attached in a pendant form as a chain, or an aromatic conjugated polymer such as polyparaphenylene, an aliphatic conjugated polymer such as polyacetylene, a heterocyclic conjugated polymer having a polypinol or polythiophene ratio, a polyaniline, Hetero-atom conjugated polymers such as polyphenylene sulfide, composite type having a structure in which structural units of conjugated polymers such as poly (phenylene vinylene), poly (annelen vinylene) and poly (chenylene vinylene) are alternately bonded Carbon-based conjugated polymers such as conjugated polymers are used. In addition, oligosilanes such as polysilanes, disilanylene arylene polymers, (disilanylene) ethenylene polymers, and disilanylene carbon-based polymer structures such as (disilanylene) ethynylene polymers alternate with carbon-based conjugated structures. Polymers linked to are used. In addition, polymer chains composed of inorganic elements such as phosphorus and nitrogen may be used, and polymers having aromatic chain ligands such as phthalocyanate polysiloxane coordinated, perylenetetracarboxylic Polymers in which perylenes such as acids are subjected to heat treatment and condensed, ladder-type polymers obtained by heat-treating polyethylene derivatives having a cyano group such as polyacrylonitrile, and organic compounds intercalated in perovskites The composite material may be used.

  Examples of the method for forming the organic semiconductor 56 include a sputtering method and a CVD method, but are not particularly limited, and an appropriate one may be used. For example, general thin film forming methods such as vacuum deposition, ion plating, sol-gel method, spray method, spin coating method, and CVD are also possible.

<Protective film>
The protective film 20 is not necessarily formed, but is preferably formed because it can be protected from erosion due to moisture or oxygen. The protective film 20 may have a multilayer structure, a single layer structure, an inorganic film, or an organic film. If an inorganic film is included, the protective film 20 is caused by moisture, oxygen, or the like. This is preferable because the barrier property against erosion is improved.

As the inorganic film, for example, a nitride film, an oxide film, a carbon film, a silicon film, or the like can be adopted. More specifically, a silicon nitride film, a silicon oxide film, a silicon oxynitride film, or diamond-like carbon (DLC) ) Film and amorphous carbon film. That is, nitrides such as SiN, AlN and GaN, oxides such as SiO, Al ₂ O ₃ , Ta ₂ O ₅ , ZnO and GeO, oxynitrides such as SiON, carbonitrides such as SiCN, metal fluorine compounds, Examples thereof include metal films.

Examples of the organic film include a furan film, a pyrrole film, a thiophene film, a polyparaxylene film, an epoxy resin, an acrylic resin, polyparaxylene, a fluorine-based polymer (perfluoroolefin, perfluoroether, tetrafluoroethylene, chlorotriethylene). Fluoroethylene, dichlorodifluoroethylene, etc.), metal alkoxides (CH ₃ OM, C ₂ H ₅ OM, etc.), polyimide precursors, polymer films such as perylene compounds, and the like.

The protective film 20 includes a laminated structure composed of two or more substances, an inorganic protective film, a silane coupling layer, a laminated structure composed of a resin sealing film, a barrier layer composed of an inorganic material, and a laminated structure composed of a cover layer composed of an organic material. , Si-CXHY, etc., a compound of a metal or semiconductor and an organic substance, a laminated structure made of an inorganic substance, a structure in which an inorganic film and an organic film are alternately laminated, a structure in which SiO ₂ or Si ₃ N ₄ is laminated on a Si layer, etc. The thing made into the laminated structure is mentioned.

  As for the barrier film 12 and the protective film 20, the organic film comprised fills up the pinhole and surface unevenness | corrugation formed in the inorganic film, and planarizes the surface. Also, it may play a role of relaxing the film stress of the inorganic film.

  The manufacturing method of the protective film 20 includes a sputtering method, a CVD method, and the like, but is not particularly limited, and an appropriate one may be used as appropriate. For example, general thin film forming methods such as vacuum deposition, ion plating, sol-gel method, spray method, spin coating method, and CVD are also possible.

<Light emission mode of organic EL display device>
The light emission mode of the organic EL display device P1 will be described.

  When a voltage is applied between the gate electrode 52 and the source electrode 58, holes are generated at the interface (region of about several nm) between the organic semiconductor 56 and the gate insulating film 54. When a voltage is applied between the source electrode 58 and the drain electrode 60 after the holes are generated, the holes can be transported. On the other hand, holes are not transported unless a voltage is applied between the gate electrode 52 and the source electrode 58. Thus, switching can be performed using the non-conducting state (the switch is off) and the conducting state (the switch is on).

  Holes (holes) are supplied from the source electrode 58 to the drain electrode 60 through the gate insulating film 54. Holes are transmitted to the anode 14 of the organic EL element 100 through the drain electrode 60.

  In the organic EL element 100, holes are transported from the anode 14 to the hole injection layer 162 in the organic solid layer 16. The transported holes are injected into the hole transport layer 164. The holes injected into the hole transport layer 164 are transported to the light emitting layer 166.

  In the organic EL element 100, electrons are transported from the cathode 18 to the electron transport layer 168 in the organic solid layer 16. The transported electrons are transported to the light emitting layer 166.

  The transported holes and electrons recombine in the light emitting layer 166. During recombination, light emitted by EL is generated by the energy generated. This light emission is led out to the outside through the hole transport layer 164, the hole injection layer 162, the anode 14, the barrier film 12, and the substrate 10 in order, and the light emission can be visually recognized.

  When Al is used for the cathode 18, the interface between the cathode layer 18 and the electron transport layer 168 becomes a reflection surface, and is reflected at this interface, proceeds to the anode 14 side, passes through the substrate 10, and goes to the outside. Is injected. Therefore, when the organic EL element having the above configuration is employed in a display or the like, the substrate 10 side becomes the display observation surface.

  For example, when a full-color display is to be realized with an organic EL panel, for example, a method of separately manufacturing organic EL elements that emit RGB colors (painting method), an organic EL element that emits white light with a single color, and a color A method combining a filter (color filter method), a method combining a single color organic EL element such as blue light emission or white light emission and a color conversion layer (color conversion method), a single color organic EL element, and organic light emission A method of realizing multiple light emission by irradiating the layer with electromagnetic waves (photo bleaching method) or the like can be mentioned, but it is not particularly limited.

  Since the organic EL element 100 is driven by the high-performance organic TFT including the high-quality gate insulating film 54, the organic EL display device P1 of the present embodiment can provide a higher-performance organic EL display device.

  A high-performance organic TFT can be manufactured using the gate insulating film of this embodiment. Therefore, an organic EL display device including a high-performance organic TFT can be provided. Here, it is more preferable to provide a gate insulating film, an organic TFT, and an organic EL display device from a polymer having a high solvent resistance to a process such as photolithography, etching, and heat treatment to a mixed polymer.

  In the said embodiment, although the organic electroluminescent display apparatus provided with an organic electroluminescent element and the organic TFT used for this were shown, even if it is an organic transistor which drives other than an organic electroluminescent element, this embodiment is not restricted to this. Applicable. That is, in the above embodiment, the organic EL element may be replaced with a driving element driven by another organic transistor, or the driving element such as the organic EL element may be omitted and the organic transistor alone may be used. Such an organic transistor can be applied to a display in general, for example, a liquid crystal display, an electrophoretic display, electronic paper, a toner display, and the like.

"Method for manufacturing organic EL display device"
A method for manufacturing the organic EL display device P1 shown in FIG. 2 will be described. The barrier film 12 is formed on the substrate 10, and the organic EL element 100 and the organic TFT 50 are produced on the barrier film 12. The drain electrode 60 of the organic TFT 50 and the anode 14 of the organic EL element 100 are made to contact each other so as to be electrically connected. Next, the protective film 20 is formed so as to cover the surfaces of the organic EL element 100 and the organic TFT 50, and the organic EL display device P1 is manufactured.

"Method of forming gate insulating film"
An example of a method for manufacturing the gate insulating film 54 of the organic TFT 50 will be described.

(Production of mixed polymer)
The mixed polymer may be a ready-made one, but may be produced. Although the manufacturing method of a mixed polymer is not specifically limited, For example, the polymer which has a hydroxyl group can be produced by the cyanoethylation reaction (Michael addition reaction etc.) by acrylonitrile. The amount of acrylonitrile added here is limited so that not all the hydroxyl groups of the polymer having a hydroxyl group are cyanoethylated.

  As an example, the mixed polymer is represented by the following chemical formulas (4) and (5). The mixed polymer represented by the chemical formula (4) is a mixed polymer in which the hydroxyl group of the polyvinyl alcohol represented by the chemical formula (1) is substituted with a cyanoethyl group. The mixed polymer represented by the chemical formula (5) is a mixed polymer in which the polyvinylphenol represented by the chemical formula (2) is substituted with a cyanoethyl group.

(Preparation of gate insulating film)
The mixed polymer represented by the above chemical formulas (4) and (5) and the melamine derivative represented by the above chemical formula (3) and the like are liquefied, mixed and stirred, and a coating liquid as a mixture containing them is prepared. Examples of the liquefaction method of the mixed polymer and melamine derivative include a method of liquefying the mixture itself of the mixed polymer and melamine derivative (solvent-free coating solution), and a method of using a solvent that dissolves the mixture separately from the mixture.

  The solvent is not particularly limited as long as it is appropriately selected and used. For example, acetone, DMF (N, N-dimethylformamide), acetonitrile and the like are used.

  As a solvent for the aqueous coating solution, a water-soluble organic solvent such as water or alcohol can be used. As the water, ordinary industrial water can be used. Further, as a water-soluble organic solvent composed of water and alcohol, it can be prepared using water, lower alcohols such as methanol, ethanol, isopropyl alcohol and N-propyl alcohol, glycols and esters thereof, and the like. . The lower alcohol, glycols and esters thereof are preferably contained in a proportion of about 5 to 20% by weight. These solvents such as lower alcohols, glycols and esters thereof are used for the purpose of improving the fluidity of the ink, improving the wetness of the substrate sheet as the printing medium, and adjusting the drying property. Yes, the type, amount used, etc. are determined according to the purpose.

  The solvent of the solvent-based coating solution is not particularly limited, but for example, water-insoluble such as toluene, xylene, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, etc. Organic solvents or mixed solvents thereof are used.

  As shown in FIG. 6, the coating solution 32 thus prepared is applied to the surface of the barrier film 12 on the gate electrode surface and the substrate 10 on which the gate electrode is formed.

  The coating method of the coating solution is not particularly limited as long as it is appropriately selected and used, but inkjet, gravure coating, gravure reverse coating, comma coating, die coating, lip coating, cast coating, roll coating, air knife coating , Mayer bar coat, extrusion coat, offset, UV curing offset, flexo, stencil, silk, curtain flow coat, wire bar coat, reverse coat, gravure coat, kiss coat, blade coat, smooth coat, spray coat, run-off coat, brush Various printing methods such as painting can be applied.

  Next, as shown in FIG. 7, a desired portion 34 where the gate insulating film 54 is formed is heated. By this heating, the cross-linking reaction between the mixed polymer and the melamine derivative proceeds. By this crosslinking reaction, a three-dimensional crosslinked structure of the mixed polymer and the melamine derivative is formed and cured. In this way, the desired portion 34 where the gate insulating film 54 is formed is thermally cured by heating.

  After thermosetting, as shown in FIG. 8, the desired portion 34 where the gate insulating film 54 is formed is thermally cured, and then removed by washing away the portion of the coating solution with a solvent by an etching process such as oxygen reactive ion etching, The portion 34 that has been solidified and not washed away becomes the gate insulating film 54, and the gate insulating film 54 is formed.

  An etching solvent may be appropriately selected and used. Aromatic organic solvents (anisole, toluene, etc.) that are good solvents for silicone ladder polymers, alcohol organic solvents (butanol, etc.), ester organic solvents (butyl acetate, etc.), ether organic solvents (tetrahydrofuran, etc.), And ketone organic solvents (such as methyl isobutyl ketone). Specific examples include aromatic organic solvents such as veratol, toluene, and phenetole. Other materials include diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, tetralin, and methyl isobutyl. Ketones, dimethylacetamide, N-methyl-2-pyrrolidone, dimethylformamide and the like are also included.

  After forming the gate insulating film 54, the organic semiconductor layer 56, the source electrode 58, and the drain electrode 60 are formed by photolithography or the like to form the organic TFT 50.

  In the gate insulating film in the present embodiment, for a polymer having a hydroxyl group, a part of the hydroxyl group is partially a cyanoethyl group, or for a polymer having a cyanoethyl group, a part of the cyanoethyl group is partially hydroxyl group, etc. Thus, since a mixture containing a mixed polymer containing cyanoethyl groups and hydroxyl groups and a melamine derivative is thermally cured and a crosslinked film is used, a gate insulating film having good compatibility and a high relative dielectric constant can be provided.

  A high-performance organic TFT can be manufactured using the gate insulating film of this embodiment. Therefore, an organic EL display device including a high-performance organic TFT can be provided. Here, it is more preferable to provide a gate insulating film, an organic TFT, an organic EL display device, and a display by changing a polymer having high solvent resistance to a mixed polymer with respect to processes such as photolithography, etching, and heat treatment.

Claims (5)

A method of manufacturing a gate insulating film in an organic transistor,
Mixture only contains a step of forming by thermally curing comprising a mixed polymer and melamine derivatives mixed with cyanoethyl group and a hydroxyl group,
A manufacturing method of a gate insulating film in which the mixed polymer is represented by the following chemical formula .
It is a manufacturing method of the gate insulating film according to claim 1,
The method for manufacturing a gate insulating film having a relative dielectric constant of 7 to 40. A method of manufacturing an organic transistor including a gate insulating film,
The said gate insulating film is a manufacturing method of the organic transistor manufactured by the manufacturing method of the gate insulating film of Claim 1 or 2. An organic EL display device comprising an organic EL element comprising at least an anode, an organic light emitting layer, and a cathode and an organic transistor for driving the organic EL element,
The said organic transistor is a manufacturing method of the organic electroluminescence display manufactured by the manufacturing method of the organic transistor of Claim 3.   The display containing the organic transistor manufactured with the manufacturing method of the organic transistor of Claim 3.