JP2010129346A - Method of manufacturing organic electroluminescent device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of easily manufacturing an organic EL device while forming a light emitting layer having a uniform film thickness and a large area and improving the life characteristics of the device to be obtained, and to provide the organic EL device obtained by the method, a lighting apparatus using the organic EL device, and a planar light source. <P>SOLUTION: In the method of manufacturing the organic EL device which has a cathode, an anode, the emitting layer arranged between the cathode and the anode, and a metal doped molybdenum oxide layer arranged between the anode and the light emitting layer, the light emitting layer is formed by using a letterpress printer having a protruded portion which is shaped corresponding to a light emitting layer forming region where the light emitting layer is formed, and which has a plurality of recessed grooves formed in the surface, for supplying organic luminescent ink containing organic luminescent material to constitute the light emitting layer and a solvent to the light emitting layer forming region. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an organic electroluminescence element, a method for producing the organic electroluminescence element, an illumination device using the organic electroluminescence element, and a planar light source.

  An organic electroluminescence element (hereinafter sometimes referred to as an organic EL element) includes a pair of electrodes and a light emitting layer. When a voltage is applied to the organic EL element, holes and electrons are injected from each electrode, and light is emitted by recombination of the injected holes and electrons in the light emitting layer. Compared to inorganic electroluminescence elements, organic EL elements can be driven at a low voltage and have high luminance. For this reason, the use of organic EL elements in display devices and lighting devices has been studied.

  In a display device, a plurality of organic EL elements each functioning as a pixel are formed on a substrate (see, for example, Patent Document 1). Since the size of the organic EL element used as a pixel in the display device is determined according to the resolution, it is usually on the order of micrometers (see, for example, Patent Document 1). On the other hand, the organic EL element used for the lighting device or the like does not need to be extremely small like the organic EL element for a display device, and usually has a size of centimeter order, and is used for a display device. Compared to organic EL elements, it is very large. Specifically, the size of the organic EL element for the display device is, for example, about 100 μm × 100 μm, but the size of the organic EL element used for the lighting device or the like is, for example, 1 cm × 1 cm or more. The size of the element differs from that of the organic EL element for lighting devices by 10,000 times or more in terms of area.

  The light emitting layer can be formed by a plurality of methods such as a vapor deposition method and a coating method. Among them, it has been studied to form a light emitting layer using a coating method because of the simplicity of the process. For example, a method for forming a light emitting layer by a relief printing method using an organic light emitting ink containing an organic material constituting the light emitting layer has been proposed.

  In organic EL elements for display devices, since the size of the light emitting layer is extremely small, the ink can be uniformly applied in the pixels by appropriately adjusting the ink density, printing speed, etc. A relatively uniform light emitting layer can be formed. However, as described above, for example, in an organic EL element for a lighting device, it is necessary to apply ink over a wide area of 10,000 times or more in area to the organic EL element for a display device. The letterpress printing method that has been used in the past cannot be directly applied to the production of a large organic EL element. For example, if you apply the letterpress printing method that has been used in manufacturing ultra-small organic EL elements for display devices as it is and apply ink over a wide area, uneven coating occurs and a light-emitting layer with a uniform thickness is formed. There is a problem that you can not. The occurrence of such coating unevenness becomes significant when the size of the light emitting layer exceeds 1 cm × 1 cm.

  When unevenness occurs in the thickness of the light emitting layer, unevenness in light emission luminance also occurs. In some cases, a light emission failure may occur or the light emission efficiency of the organic EL element may decrease. The performance of this will be significantly reduced.

  The organic EL element can improve performance by providing a predetermined layer (such as an electron injection layer and a hole injection layer) different from the light emitting layer between the electrodes. Various studies have been made so far for improving the performance of organic EL elements. For example, the use of a layer made of a metal oxide for an electron injection layer or a hole injection layer has been studied. As a highly efficient electron injection layer, an inorganic material such as molybdenum oxide is provided between a light emitting layer and an electron injection electrode. There is an organic EL element provided with an oxide layer (see, for example, Patent Document 2).

  When the light emitting layer is formed by the above-described printing method after the molybdenum oxide layer is formed, the molybdenum oxide layer has low resistance to a wet process, so there is a risk of damaging the molybdenum oxide layer when forming the light emitting layer. In some cases, the molybdenum oxide layer may be dissolved in the organic light emitting ink. As a result, the technique disclosed in Patent Document 2 has a problem that an organic EL element having high light emission characteristics and long life characteristics cannot be obtained.

JP 2006-286243 A JP 2002-367784 A

  The present invention has been made in view of the above-described problems of the prior art, and the problem is to prevent coating unevenness when an organic light-emitting ink is applied to a formation region of a light-emitting layer having a large area by a relief printing method. A method for producing an organic EL device capable of forming a light-emitting layer having a uniform film thickness, being easy to produce and having good lifetime characteristics of the obtained device, and an organic material obtained by the production method An object is to provide an EL element, an illumination device using the organic EL element, and a planar light source.

  In order to solve the above-described problems, the present invention provides a method for manufacturing an organic EL element adopting the following configuration, an organic EL element obtained by the manufacturing method, a lighting device using the organic EL element, and a planar shape. Provide a light source.

[1] Manufacture of an organic electroluminescence device having a cathode, an anode, a light emitting layer disposed between the cathode and the anode, and a metal-doped molybdenum oxide layer disposed between the anode and the light emitting layer A method,
Preparing a substrate provided with an anode;
A metal-doped molybdenum oxide layer forming step;
A relief printing plate having a shape corresponding to a light emitting layer forming region in which the light emitting layer is formed after the metal doped molybdenum oxide layer forming step and having a convex portion having a plurality of concave grooves formed on the surface portion A step of forming a light emitting layer by supplying an organic light emitting ink containing an organic light emitting material and a solvent constituting the light emitting layer to the light emitting layer forming region,
The manufacturing method of the organic electroluminescent element which has a process of forming a cathode.

[2] The method for producing an organic electroluminescent element according to [1], wherein in the metal-doped molybdenum oxide layer forming step, the metal-doped molybdenum oxide layer is formed by simultaneously depositing molybdenum oxide and a dopant metal. .

[3] The organic material according to [1] or [2], wherein the dopant metal contained in the metal-doped molybdenum oxide layer is selected from the group consisting of transition metals, metals of Group 13 of the periodic table, and mixtures thereof. Manufacturing method of electroluminescent element.

[4] The method for producing an organic electroluminescent element according to the above [3], wherein the dopant metal is aluminum.

[5] The organic electroluminescence device according to any one of [1] to [4], wherein the ratio of the dopant metal contained in the metal-doped molybdenum oxide layer is 0.1 to 20.0 mol%. Manufacturing method.

[6] The organic material according to any one of [1] to [5], wherein at least one end in the longitudinal direction of the plurality of concave grooves is open to a side surface of the convex portion. Manufacturing method of electroluminescent element.

[7] The method for producing an organic electroluminescent element according to any one of [1] to [6], wherein the size of the light emitting layer forming region is 1 cm × 1 cm or more.

[8] An organic electroluminescence device obtained using the method for producing an organic electroluminescence device according to any one of [1] to [7].

[9] An illumination device comprising the organic electroluminescence element according to [8].

[10] A planar light source comprising the organic electroluminescence device according to [8].

According to the present invention, it is possible to provide an organic EL element that is easy to manufacture, has a long lifetime, and has excellent light emission characteristics without occurrence of light emission unevenness or light emission failure on the light emitting surface.
Therefore, the organic EL element of the present invention can be preferably used as a planar light source as a lighting device or a backlight.

  Hereinafter, the organic EL element of the present invention will be described in detail according to preferred embodiments thereof.

  The organic EL device manufacturing method according to the present invention includes a cathode, an anode, a light emitting layer disposed between the cathode and the anode, and a metal-doped molybdenum oxide layer disposed between the anode and the light emitting layer. A step of preparing a substrate provided with an anode, a metal doped molybdenum oxide layer forming step, and the light emitting layer after the metal doped molybdenum oxide layer forming step An organic light-emitting material and a solvent constituting the light-emitting layer, using a relief printing plate having a shape corresponding to the light-emitting layer forming region where the light-emitting layer is formed and having a convex portion in which a plurality of concave grooves are formed on the surface portion A light emitting layer forming step of forming a light emitting layer by supplying an organic light emitting ink containing a light emitting layer to the light emitting layer forming region, and a step of forming a cathode.

  Below, one Embodiment of the structure of the organic EL element which this invention method makes object is described, Then, one Embodiment of the manufacturing method of the organic EL element concerning this invention is described.

(substrate)
As the substrate, any substrate that does not change in the process of forming the organic EL element, that is, any substrate that does not change when the electrode is formed and the organic layer is formed may be a rigid substrate or a flexible substrate. A glass plate, a plastic plate, a polymer film and a silicon plate, and a laminated plate obtained by laminating these are preferably used. Further, a plastic, a polymer film or the like that has been subjected to a low water permeability treatment can also be used. A commercially available substrate can be used as the substrate. Moreover, the said board | substrate can also be manufactured by a well-known method.

  In this embodiment, the anode is provided on the substrate side, and the cathode is provided on the side away from the substrate. However, the bottom emission type organic EL element that takes out light from the light emitting layer from the substrate side is provided. In this case, a substrate having a high light transmittance in the visible light region is preferably used. . Further, in the case of a top emission type organic EL element that takes out light from the light emitting layer from the cathode side, the substrate may be transparent or opaque.

  In addition, as said commercially available board | substrate, there also exists a board | substrate with which the anode was formed on the support substrate. When such a commercially available substrate is used, the following anode forming step can be omitted in the manufacturing method of the present embodiment.

(anode)
The anode in the present embodiment is a transparent electrode that transmits light from the light emitting layer. However, as another form, an organic EL element in which the cathode is formed of a transparent electrode is also possible. As the anode, a metal oxide, metal sulfide or metal thin film having high electrical conductivity can be used, and a material having a high transmittance can be suitably used. The anode is appropriately selected according to the constituent material of the light emitting layer. be able to. Examples of the transparent anode material include indium oxide, zinc oxide, tin oxide, ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), gold, platinum, silver, copper, and the like. The thin film is used. Among these, ITO, IZO, and tin oxide are preferable.

  Further, as the constituent material of the anode, a transparent organic conductive film such as polyaniline or a derivative thereof, polythiophene or a derivative thereof may be used.

  Further, from the viewpoint of facilitating charge injection into the light emitting layer, a conductive polymer such as a phthalocyanine derivative and a polythiophene derivative, Mo oxide, amorphous carbon, carbon fluoride, polyamine is formed on the surface of the anode on the light emitting layer side. A 1 to 200 nm layer such as a compound, or a layer having an average film thickness of 10 nm or less made of a metal oxide, a metal fluoride, an organic insulating material, or the like may be provided.

  The film thickness of the anode can be appropriately selected in consideration of light transmittance and electrical conductivity, and is, for example, 5 nm to 10 μm, preferably 10 nm to 1 μm, and more preferably 20 nm to 500 nm.

  Further, the anode may be divided into a plurality of electrically separated cells. In such a case, the interval between adjacent cells is preferably 1 μm to 50 μm, more preferably 5 μm to 30 μm. is there. If the distance between adjacent cells is less than the lower limit, the light guided in the surface direction of the anode tends not to be sufficiently suppressed, whereas if the upper limit is exceeded, the actual light emitting area of the entire device is reduced. Since it becomes small, the light emission efficiency tends to decrease.

Examples of the method for forming the anode include vacuum deposition, sputtering, ion plating, and plating.
Examples of the method of partitioning the anode into a plurality of electrically separated cells include a method of forming a pattern by an etching method using a photoresist after forming the anode.

(Metal-doped molybdenum oxide layer)
In the present embodiment, a metal-doped molybdenum oxide layer is provided between the anode and the light emitting layer as an essential component. A predetermined layer may be further provided between the anode and the light emitting layer. Examples of the layer provided between the anode and the light emitting layer include a hole injection layer, a hole transport layer, and an electron block layer described later. That is, there are an element configuration in which only the metal-doped molybdenum oxide layer is provided between the anode and the light emitting layer, and an element configuration in which the metal-doped molybdenum oxide layer and other layers are provided.
Examples of the layer provided between the light emitting layer and the cathode include an electron injection layer, an electron transport layer, and a hole blocking layer.

  The metal-doped molybdenum oxide layer contains a molybdenum oxide and a dopant metal, and preferably consists essentially of a molybdenum oxide and a dopant metal. In this embodiment, a hole injection layer and a hole transport described later are included. It functions as one or more layers of the layer and the electron block layer. More specifically, the proportion of the total of the molybdenum oxide and the dopant metal in the total amount of the material constituting the metal-doped molybdenum oxide layer is preferably 98% by mass or more, more preferably 99% by mass or more, and still more preferably Is 99.9% by mass or more.

The metal-doped molybdenum oxide layer is preferably a hole injection layer or is provided in direct contact with the light emitting layer or the hole injection layer. More specific arrangements of the metal-doped molybdenum oxide layer are shown in the following (i) to (v).
(Ii) provided in contact with the anode and the hole transport layer (ii) provided in contact with the anode and the electron blocking layer (iii) provided in contact with the hole injection layer and the light emitting layer (iv) the hole injection layer and Provided in contact with the electron blocking layer (v) Provided in contact with the anode and the light emitting layer

  The visible light transmittance of the metal-doped molybdenum oxide layer is preferably 50% or more. By having a visible light transmittance of 50% or more, it can be suitably used for an organic EL device that emits light through the metal-doped molybdenum oxide layer.

The dopant metal contained in the metal-doped molybdenum oxide layer is preferably a transition metal, a Group 13 metal of the periodic table, or a mixture thereof, more preferably aluminum, nickel, copper, chromium, titanium, silver, gallium, zinc. , Neodymium, europium, holmium, cerium, and more preferably aluminum. On the other hand, it is preferable to employ MoO ₃ as the molybdenum oxide. When MoO ₃ is formed by an evaporation method such as vacuum evaporation, the stoichiometric composition ratio of Mo and O in the deposited film may deviate from MoO _3. It can be preferably used for an EL element.

  It is preferable that the ratio of the dopant metal contained in the metal doped molybdenum oxide layer is 0.1 to 20.0 mol%. When the content ratio of the dopant metal is within the above range, a metal-doped molybdenum oxide layer having good process resistance can be obtained.

  Although the thickness of the said metal dope molybdenum oxide layer is not specifically limited, It is preferable that it is 1-100 nm.

  A method for forming the metal-doped molybdenum oxide layer is not particularly limited, but one of the preferable methods is to simultaneously deposit molybdenum oxide and a dopant metal on the layer on which the metal-doped molybdenum oxide layer is stacked. It can be illustrated as. For example, deposition can be performed on the anode layer provided on the substrate to obtain a metal-doped molybdenum oxide layer in direct contact with the electrode.

  Deposition can be performed by vacuum evaporation, molecular beam evaporation, sputtering or ion plating, ion beam evaporation, or the like. By introducing plasma into the film formation chamber, a plasma assisted vacuum deposition method with improved reactivity and film formability can be used. Examples of the evaporation source of the vacuum deposition method include resistance heating, electron beam heating, high frequency induction heating, and laser beam heating. As a simpler method, resistance heating, electron beam heating, and high frequency induction heating are preferable. Examples of the sputtering method include a DC sputtering method, an RF sputtering method, an ECR sputtering method, a conventional sputtering method, a magnetron sputtering method, an ion beam sputtering method, and a counter target sputtering method, and any method can be used. In order not to damage the lower layer of the metal-doped molybdenum oxide layer, it is preferable to use a magnetron sputtering method, an ion beam sputtering method, or a counter target sputtering method.

Note that during film formation, vapor deposition can be performed by introducing a gas containing oxygen or an oxygen element into the atmosphere. In addition, as a material for depositing the metal-doped molybdenum oxide layer, MoO ₃ or a dopant metal alone is usually used, but molybdenum alone, an oxide of MoO ₂ or a dopant metal, an alloy of a dopant metal and molybdenum, or these A mixture of the above can be used.

The deposited metal-doped molybdenum oxide layer is subjected to other steps such as heating, UV-O ₃ treatment, atmospheric exposure, etc. as it is or optionally. Among these, heat treatment is preferably performed in order to improve the transmittance.

The heating can be performed at 50 to 350 ° C. for 1 to 120 minutes. The UV-O ₃ treatment can be performed by irradiating with ultraviolet rays at an intensity of 1 to 100 mW / cm ² for 5 seconds to 30 minutes and in an atmosphere having an ozone concentration of 0.001 to 99%. The exposure to the atmosphere can be performed by leaving it in the atmosphere at a humidity of 40 to 95% and a temperature of 20 to 50 ° C. for 1 to 20 days.

(Layer provided between the anode and the light emitting layer)
At least a metal-doped molybdenum oxide layer is provided between the anode and the light emitting layer. As described above, a hole injection layer, a hole transport layer, an electron blocking layer, and the like may be provided in addition to the metal-doped molybdenum oxide layer.

  The hole injection layer is a layer having a function of improving hole injection efficiency from the anode. The hole transport layer is a layer having a function of improving hole injection from the anode, the hole injection layer, or the hole transport layer closer to the anode. The electron blocking layer is a layer having a function of blocking electron transport. In the case where the hole injection layer and / or the hole transport layer has a function of blocking electron transport, these layers may also serve as an electron blocking layer. The fact that the electron blocking layer has a function of blocking electron transport makes it possible, for example, to produce an element that allows only electron current to flow and confirm the blocking effect by reducing the current value.

(Hole injection layer)
As described above, the hole injection layer can be provided between the anode and the hole transport layer or between the anode and the light emitting layer. As a material constituting the hole injection layer, a known material can be appropriately used, and there is no particular limitation. For example, phenylamine, starburst amine, phthalocyanine, hydrazone derivative, carbazole derivative, triazole derivative, imidazole derivative, oxadiazole derivative having amino group, vanadium oxide, tantalum oxide, tungsten oxide, molybdenum oxide, ruthenium oxide And oxides such as aluminum oxide, amorphous carbon, polyaniline, polythiophene derivatives, and the like.

  As a film formation method of the hole injection layer, for example, film formation from a solution containing a material (hole injection material) that becomes the hole injection layer can be mentioned. The solvent used for film formation from a solution is not particularly limited as long as it dissolves the hole injection material. Chlorine solvents such as chloroform, methylene chloride and dichloroethane, ether solvents such as tetrahydrofuran, toluene, Mention may be made of aromatic hydrocarbon solvents such as xylene, ketone solvents such as acetone and methyl ethyl ketone, ester solvents such as ethyl acetate, butyl acetate and ethyl cellosolve acetate, and water.

  As a film forming method from a solution, a spin coating method, a casting method, a micro gravure coating method, a gravure coating method, a bar coating method, a roll coating method, a wire bar coating method, a dip coating method, a spray coating method, a screen printing method, Examples of the application method include a flexographic printing method, an offset printing method, and an ink jet printing method.

  The thickness of the hole injection layer is preferably about 5 to 300 nm. If the thickness is less than 5 nm, the production tends to be difficult. On the other hand, if the thickness exceeds 300 nm, the driving voltage and the voltage applied to the hole injection layer tend to increase.

(Hole transport layer)
The material constituting the hole transport layer is not particularly limited. For example, N, N′-diphenyl-N, N′-di (3-methylphenyl) 4,4′-diaminobiphenyl (TPD), 4 , 4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPB) and other aromatic amine derivatives, polyvinylcarbazole or derivatives thereof, polysilane or derivatives thereof, aromatic amines in the side chain or main chain Polysiloxane derivative having pyrazole, pyrazoline derivative, arylamine derivative, stilbene derivative, triphenyldiamine derivative, polyaniline or derivative thereof, polythiophene or derivative thereof, polyarylamine or derivative thereof, polypyrrole or derivative thereof, poly (p-phenylene vinylene) Or its derivatives, or poly (2,5-thienylene vinylene) or a derivative thereof is exemplified.

  Among these, as the hole transport material used for the hole transport layer, polyvinyl carbazole or a derivative thereof, polysilane or a derivative thereof, a polysiloxane derivative having an aromatic amine compound group in a side chain or a main chain, polyaniline or a derivative thereof, Polymeric hole transport materials such as polythiophene or derivatives thereof, polyarylamine or derivatives thereof, poly (p-phenylene vinylene) or derivatives thereof, or poly (2,5-thienylene vinylene) or derivatives thereof are preferred, and more preferred Is polyvinyl carbazole or a derivative thereof, polysilane or a derivative thereof, and a polysiloxane derivative having an aromatic amine in the side chain or main chain. In the case of a low-molecular hole transport material, it is preferably used by being dispersed in a polymer binder.

  The method for forming the hole transport layer is not particularly limited, but in the case of a low molecular hole transport material, film formation from a mixed solution containing a polymer binder and a hole transport material can be exemplified. Examples of molecular hole transport materials include film formation from a solution containing a hole transport material.

The solvent used for film formation from a solution is not particularly limited as long as it dissolves the hole transport material, and is a chlorine-based solvent such as chloroform, methylene chloride, dichloroethane, an ether-based solvent such as tetrahydrofuran, toluene, Examples thereof include aromatic hydrocarbon solvents such as xylene, ketone solvents such as acetone and methyl ethyl ketone, and ester solvents such as ethyl acetate, butyl acetate, and ethyl cellosolve acetate.
Examples of the film forming method from a solution include the same coating method as the above-described film forming method of the hole injection layer.

  As the polymer binder to be mixed, those that do not extremely inhibit hole transport are preferable, and those that weakly absorb visible light are preferably used. For example, polycarbonate, polyacrylate, polymethyl acrylate, polymethyl methacrylate, polystyrene, Examples thereof include polyvinyl chloride and polysiloxane.

  The thickness of the hole transport layer is not particularly limited, but can be appropriately changed according to the intended design, and is preferably about 1 to 1000 nm. If the thickness is less than the lower limit value, production tends to be difficult or the effect of hole transport is not sufficiently obtained. On the other hand, if the thickness exceeds the upper limit value, the driving voltage and the hole transport layer are increased. There is a tendency that the voltage applied to is increased. Therefore, the thickness of the hole transport layer is preferably 1 to 1000 nm as described above, more preferably 2 nm to 500 nm, and still more preferably 5 nm to 200 nm.

(Light emitting layer)
The light emitting layer usually includes an organic substance that mainly emits fluorescence or phosphorescence. The light emitting layer contains a low molecular compound and / or a high molecular compound as an organic substance. Further, a dopant material may be included. Examples of the material for forming the light emitting layer that can be used in this embodiment include the following. In addition, a plurality of light emitting layers may be disposed between the anode and the cathode without being limited to a single light emitting layer.

(Dye material)
Examples of dye-based materials include cyclopentamine derivatives, tetraphenylbutadiene derivative compounds, triphenylamine derivatives, oxadiazole derivatives, quinacridone derivatives, coumarin derivatives, pyrazoloquinoline derivatives, distyrylbenzene derivatives, distyrylarylene derivatives, Examples include pyrrole derivatives, thiophene ring compounds, pyridine ring compounds, perinone derivatives, perylene derivatives, oligothiophene derivatives, oxadiazole dimers, and pyrazoline dimers.

(Metal complex materials)
Examples of metal complex materials include metal complexes that emit light from triplet excited states such as iridium complexes and platinum complexes, aluminum quinolinol complexes, benzoquinolinol beryllium complexes, benzoxazolyl zinc complexes, benzothiazole zinc complexes, azomethyls. Zinc complex, porphyrin zinc complex, europium complex, etc., which has Al, Zn, Be or the like as the central metal or rare earth metal such as Tb, Eu, or Dy, and the ligand is oxadiazole, thiadiazole, phenylpyridine, phenylbenzo Examples thereof include metal complexes having an imidazole or quinoline structure.

(Polymer material)
Polymeric materials include polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, and polymerized chromophores and metal complex light emitting materials. Etc.

Among the above light-emitting materials, examples of materials that emit blue light include distyrylarylene derivatives, oxadiazole derivatives, and polymers thereof, polyvinylcarbazole derivatives, polyparaphenylene derivatives, and polyfluorene derivatives. Of these, polymer materials such as polyvinyl carbazole derivatives, polyparaphenylene derivatives, and polyfluorene derivatives are preferred.
Examples of materials that emit green light include quinacridone derivatives, coumarin derivatives, and polymers thereof, polyparaphenylene vinylene derivatives, polyfluorene derivatives, and the like. Of these, polymer materials such as polyparaphenylene vinylene derivatives and polyfluorene derivatives are preferred.
Examples of materials that emit red light include coumarin derivatives, thiophene ring compounds, and polymers thereof, polyparaphenylene vinylene derivatives, polythiophene derivatives, and polyfluorene derivatives. Among these, polymer materials such as polyparaphenylene vinylene derivatives, polythiophene derivatives, and polyfluorene derivatives are preferable.

(Dopant material)
A dopant can be added to the light emitting layer for the purpose of improving the light emission efficiency and changing the light emission wavelength. Examples of such dopants include perylene derivatives, coumarin derivatives, rubrene derivatives, quinacridone derivatives, squalium derivatives, porphyrin derivatives, styryl dyes, tetracene derivatives, pyrazolone derivatives, decacyclene, phenoxazone, and the like. The thickness of the light emitting layer 7 is usually about 20 to 2000 mm.

(Layer provided between the cathode and the light emitting layer)
Layers such as an electron injection layer, an electron transport layer, and a hole blocking layer are laminated between the light emitting layer and the cathode as necessary.

When only one layer is provided between the cathode and the light emitting layer, the layer is referred to as an electron injection layer. When both the electron injection layer and the electron transport layer are provided between the cathode and the light emitting layer, a layer in contact with the cathode is referred to as an electron injection layer, and a layer excluding the electron injection layer is referred to as an electron transport layer.
The electron injection layer is a layer having a function of improving electron injection efficiency from the cathode. The electron transport layer is a layer having a function of improving electron injection from the cathode, the electron injection layer, or the electron transport layer closer to the cathode. The hole blocking layer is a layer having a function of blocking hole transport. In the case where the electron injection layer and / or the electron transport layer have a function of blocking hole transport, these layers may also serve as the hole blocking layer.
The fact that the hole blocking layer has a function of blocking hole transport makes it possible, for example, to produce an element that allows only a hole current to flow, and confirm the blocking effect by reducing the current value.

(Electron transport layer)
As the material for forming the electron transport layer, known materials can be used, such as oxadiazole derivatives, anthraquinodimethane or derivatives thereof, benzoquinone or derivatives thereof, naphthoquinone or derivatives thereof, anthraquinones or derivatives thereof, tetracyanoanthraquinodi. Examples include methane or its derivatives, fluorenone derivatives, diphenyldicyanoethylene or its derivatives, diphenoquinone derivatives, or metal complexes of 8-hydroxyquinoline or its derivatives, polyquinoline or its derivatives, polyquinoxaline or its derivatives, polyfluorene or its derivatives, etc. The

  Of these, oxadiazole derivatives, benzoquinone or derivatives thereof, anthraquinones or derivatives thereof, or metal complexes of 8-hydroxyquinoline or derivatives thereof, polyquinoline or derivatives thereof, polyquinoxaline or derivatives thereof, polyfluorene or derivatives thereof are preferred, 2- (4-biphenylyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole, benzoquinone, anthraquinone, tris (8-quinolinol) aluminum, and polyquinoline are more preferable.

(Electron injection layer)
The electron injection layer is provided between the electron transport layer and the cathode or between the light emitting layer and the cathode. Depending on the type of the light emitting layer, the electron injection layer may be an alkali metal or alkaline earth metal, an alloy containing one or more of the above metals, an oxide, halide and carbonate of the metal, or a mixture of the substances. Etc.

  Examples of the alkali metal or its oxide, halide, carbonate include lithium, sodium, potassium, rubidium, cesium, lithium oxide, lithium fluoride, sodium oxide, sodium fluoride, potassium oxide, potassium fluoride, oxide Examples include rubidium, rubidium fluoride, cesium oxide, cesium fluoride, and lithium carbonate.

  Examples of the alkaline earth metals or oxides, halides and carbonates thereof include magnesium, calcium, barium, strontium, magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride, calcium fluoride, barium oxide, fluorine. Barium fluoride, strontium oxide, strontium fluoride, magnesium carbonate and the like.

  Furthermore, a metal, a metal oxide, an organometallic compound doped with a metal salt, an organometallic complex compound, or a mixture thereof can also be used as a material for the electron injection layer.

This electron injection layer may have a stacked structure in which two or more layers are stacked. Specifically, Li / Ca etc. are mentioned. This electron injection layer is formed by vapor deposition, sputtering, printing, or the like.
The thickness of the electron injection layer is preferably about 1 nm to 1 μm.

  The electron injection layer and the hole injection layer may be collectively referred to as a charge injection layer, and the electron transport layer and the hole transport layer may be collectively referred to as a charge transport layer.

(cathode)
A material for the cathode is preferably a material having a small work function and easy electron injection into the light emitting layer. The cathode material is preferably a material having high electrical conductivity and high visible light reflectance. Specific examples of such cathode materials include metals, metal oxides, alloys, graphite or graphite intercalation compounds, and inorganic semiconductors such as zinc oxide (ZnO).

  As the metal, an alkali metal, an alkaline earth metal, a transition metal, a group 13 metal of the periodic table, or the like can be used. Specific examples of these metals include lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten, tin, and aluminum. , Scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, ytterbium, and the like.

  Examples of the alloy include an alloy containing at least one of the above metals. Specifically, a magnesium-silver alloy, a magnesium-indium alloy, a magnesium-aluminum alloy, an indium-silver alloy, a lithium-aluminum alloy, Examples thereof include a lithium-magnesium alloy, a lithium-indium alloy, and a calcium-aluminum alloy.

  The cathode is an electrode having optical transparency as required, for example, when light is taken out from the cathode side. Examples of such a light-transmitting cathode material include conductive oxides such as indium oxide, zinc oxide, tin oxide, ITO, and IZO; and conductive organic substances such as polyaniline or a derivative thereof, polythiophene or a derivative thereof. Can do.

  Note that the cathode may have a laminated structure of two or more layers. Moreover, an electron injection layer may be used as a cathode.

  The film thickness of the cathode can be appropriately selected in consideration of electric conductivity and durability, but is, for example, 10 nm to 10 μm, preferably 20 nm to 1 μm, and more preferably 50 nm to 500 nm.

  Examples of the method for forming the cathode include a vacuum deposition method, a sputtering method, and a laminating method in which a metal thin film is thermocompression bonded. Note that the cathode may have a laminated structure of two or more layers.

In the organic EL element of the present embodiment, examples of combinations of layer configurations from the anode to the cathode are shown below.
a) Anode / hole injection layer / light emitting layer / cathode b) Anode / hole injection layer / light emitting layer / electron injection layer / cathode c) Anode / hole injection layer / light emitting layer / electron transport layer / cathode d) Anode / Hole injection layer / light emitting layer / electron transport layer / electron injection layer / cathode e) anode / hole transport layer / light emitting layer / cathode f) anode / hole transport layer / light emitting layer / electron injection layer / cathode g) Anode / hole transport layer / light emitting layer / electron transport layer / cathode h) anode / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode i) anode / hole injection layer / hole transport layer / Emissive layer / cathode j) anode / hole injection layer / hole transport layer / emission layer / electron injection layer / cathode k) anode / hole injection layer / hole transport layer / emission layer / electron transport layer / cathode l) Anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode (here, the symbol “/” indicates that the layers sandwiching the symbol “/” are stacked adjacent to each other) Indicating that. Hereinafter the same.)
In a) to l), one of the layers provided between the anode and the light emitting layer is a metal-doped molybdenum oxide layer.

The organic EL device of the present embodiment may have two or more light-emitting layers, and as an organic EL device having two light-emitting layers, any one of the layer configurations a) to l) above. In this case, when the laminate sandwiched between the anode and the cathode is referred to as “repeating unit A”, the layer configuration shown in the following m) can be exemplified.
m) Anode / (Repeating unit A) / Charge generating layer / (Repeating unit A) / Cathode Further, as an organic EL device having three or more light emitting layers, “(Repeating unit A) / charge generating layer” As the “repeating unit B”, the layer constitution shown in the following n) can be mentioned.
n) Anode / (Repeating unit B) x / (Repeating unit A) / Cathode The symbol “x” represents an integer of 2 or more, and (Repeating unit B) x is a laminate in which the repeating unit B is laminated in x stages. Represents the body.
Here, the charge generation layer is a layer that generates holes and electrons by applying an electric field. Examples of the charge generation layer include a thin film made of vanadium oxide, indium tin oxide (abbreviated as ITO), molybdenum oxide, or the like.

  In the organic EL device of this embodiment, an insulating layer having a thickness of 2 nm or less may be provided adjacent to the electrode in order to further improve the adhesion with the electrode or improve the charge injection property from the electrode. In addition, a thin buffer layer may be inserted between each of the aforementioned layers in order to improve adhesion at the interface or prevent mixing.

(Protective layer)
After the cathode is formed as described above, the basic structure is (anode)-(layer between the anode and the light-emitting layer)-(light-emitting layer)-(between the light-emitting layer and the cathode provided as necessary. In order to protect the light emitting functional part having (layer)-(cathode), a protective layer (upper sealing film) for sealing the light emitting functional part is formed. This protective layer usually has at least one inorganic layer and at least one organic layer. The number of stacked layers is determined as necessary. Basically, inorganic layers and organic layers are alternately stacked.

  Note that a plastic substrate is higher in gas and liquid permeability than a glass substrate, and a light emitting material such as a light emitting layer is easily oxidized and easily deteriorated by contact with water. Therefore, a plastic substrate is used as the substrate. If the light emitting function part is encapsulated by the substrate and the protective layer, it is easy to change with time. Therefore, a lower sealing film having a high barrier property against gas and liquid is laminated on the plastic substrate, and then the lower part is formed. The light emitting functional unit is laminated on the sealing film. The lower sealing film is usually formed with the same configuration and the same material as the protective layer (upper sealing film).

The organic EL device of the above-described embodiment is a bottom emission type device that transmits light from the light emitting layer through the transparent anode and emits the light from the transparent substrate to the outside. However, the light from the light emitting layer is transparent. The present invention can be similarly applied to other forms of the top emission type in which the cathode is transmitted and emitted from the transparent protective layer to the outside.

  In the other embodiments, for example, a metal thin film exemplified as the cathode electrode can be used as the transparent cathode for the transparent cathode that transmits light from the light emitting layer. In addition, since the metal thin film used for the transparent cathode is formed into a thin film to such an extent that light can be transmitted, the sheet resistance is increased. Therefore, the transparent cathode is preferably constituted by a laminate in which transparent electrodes such as ITO thin films are laminated in a metal foil film shape. Moreover, it is preferable to provide a reflective film having a high reflectivity such as silver, for example, between the cathode and the substrate, and by providing such a reflective film, light directed toward the substrate side can be reflected to the transparent cathode side. And the light extraction efficiency can be improved.

[Method of manufacturing organic EL element]
Hereafter, the manufacturing method of the organic EL element concerning this invention is demonstrated in detail.

(Anode formation process)
A substrate made of any of the aforementioned substrate materials is prepared. When a plastic substrate having high gas and liquid permeability is used, a lower sealing film is formed on the substrate as necessary.

  Next, an anode is patterned on the prepared substrate using any of the anode materials described above. When this anode is used as a transparent electrode, as described above, a transparent electrode material such as ITO, IZO, tin oxide, zinc oxide, indium oxide, and zinc aluminum composite oxide is used. For example, in the case of using ITO, the electrode pattern is formed as a uniform deposited film on the substrate by a sputtering method, and then patterned into a line shape by photolithography.

(Formation process of light emitting layer formation region)
In some cases, an insulating film is formed over the substrate on which the anode is formed, and further patterned to form a partition wall that surrounds the light emitting layer forming region where the light emitting layer is formed when viewed from one side in the thickness direction of the substrate. The light emitting layer forming region corresponds to the light emitting region. When the organic EL element is used as a light source of an illumination device, the light emitting layer forming region (light emitting region) is usually formed so that the dimension thereof is an area of 0.5 cm × 0.5 cm or more.

  When the plurality of organic EL elements are formed on the substrate, the role of the partition formed from the insulating film is to ensure electrical insulation between the organic EL elements and to define a light emitting region. Therefore, the thickness dimension is usually set to 0.1 to 5 μm.

The partition wall is usually formed by photolithography using a photosensitive material (photoresist composition).
The photosensitive material (photoresist composition) can be applied by a coating method using a spin coater, bar coater, roll coater, die coater, gravure coater, slit coater or the like.

  The insulating photosensitive material forming the partition may be either a positive resist or a negative resist. Specifically, polyimide, acrylic resin, and novolac resin-based photosensitive compounds can be used as the photosensitive material exhibiting insulation properties. The photosensitive material may contain a material exhibiting light shielding properties.

  In order to impart ink repellency to the surface of the partition wall, an ink repellant substance may be added to the photosensitive material for forming the partition wall. Or after forming a partition, you may provide ink repellency to the surface of a partition by coat | covering the ink-repellent substance on the surface. The ink repellency is preferably liquid repellency with respect to the ink used when forming an organic layer such as a light emitting layer.

(Metal-doped molybdenum oxide layer forming process)
After the formation of the insulating partition, layers such as a hole injection layer, a hole transport layer, and an electron blocking layer are provided in a region (light emitting layer formation region) defined by the partition. As described in the description of the element structure, the layer provided between the anode and the light-emitting layer may be composed of only a metal-doped molybdenum layer or a laminate including a metal-doped molybdenum oxide layer. May be. The combination of the material of the metal-doped molybdenum oxide layer and the laminated body can be selected as described in the description of the element structure.

  A method for forming the metal-doped molybdenum oxide layer is not particularly limited, but a preferred method is a so-called co-evaporation method in which molybdenum oxide and a dopant metal are simultaneously deposited on a layer on which the metal-doped molybdenum oxide layer is laminated. It can be illustrated as one of these. For example, deposition can be performed on the anode layer provided on the substrate to obtain a metal-doped molybdenum oxide layer in direct contact with the electrode. Alternatively, after providing an electrode on the substrate, one or more other layers such as a light emitting layer, a hole injection layer, a hole transport layer, or an electron blocking layer are provided on the electrode, and deposition is further performed thereon. A metal-doped molybdenum oxide layer in direct contact with the layer can be obtained. Since the method for forming the metal-doped molybdenum oxide layer has been described in detail above, the description thereof is omitted.

  In the case where the layer provided between the anode and the light emitting layer is composed of a laminate including a metal-doped molybdenum oxide layer, there is no particular limitation on the method for forming other layers other than the metal-doped molybdenum oxide layer. In the case of a low molecular material, a method by film formation from a mixed solution with a polymer binder is exemplified. In the case of a polymer material, a method by film formation from a solution is exemplified, and the polymer material can be formed by the method described above.

  When the coating solution is applied to the entire surface of the substrate by the above-described coating method, the coating solution may be applied onto the partition wall. As a result, it falls into the areas separated by the partition walls, and is formed as a coating film in each area. Thereafter, the coating film in each region is formed by drying, and functions as a hole injection layer, a hole transport layer, or the like.

(Light emitting layer forming step)
In the light emitting layer forming step in the conventional method for manufacturing an organic EL element, as shown in FIG. 1, the tip surface 2a of the convex portion 2 of the relief printing plate 1 is formed in a shape and size corresponding to the region where the light emitting layer is formed. Then, the organic light emitting ink 3 was adhered on the tip surface 2a, and the organic light emitting ink 3 was transferred to the formation region of the light emitting layer. In addition, the front end surface of a convex part is a plane of the open end of a convex part.

  On the other hand, the feature of the light emitting layer forming step in the method for manufacturing an organic EL element of the present invention is that, as shown in FIG. 2, the convex portion 12 having a shape corresponding to the light emitting layer forming region where the light emitting layer is formed. Using the relief printing plate 11, a light emitting layer is formed by applying an organic light emitting ink containing an organic light emitting material constituting a light emitting layer and a solvent to the light emitting layer forming region, and the convex portion 12 is formed on the surface portion. It has a plurality of concave grooves 12b. In the surface portion of the convex portion 12, the plurality of concave grooves 12 b are preferably arranged in stripes with a predetermined interval in the lateral direction, and further, the predetermined interval is a constant interval. Preferably there is. Here, the short direction is a direction perpendicular to the depth direction of the groove and the direction (longitudinal direction) in which the groove extends. Hereinafter, the site | part between the ditch | groove 12b and the ditch | groove 12b arrange | positioned adjacently is called the protruding item | line 12a. Therefore, the width of the ridges 12a described later corresponds to the predetermined interval or the constant interval. When the plurality of concave grooves 12b are arranged in stripes at predetermined intervals in the lateral direction, the concave grooves 12b and the ridges 12a are alternately formed on the surface portion. The shape corresponding to the light emitting layer forming region is a shape in which the contour of the surface of the convex portion 12 substantially matches the contour of the light emitting layer forming region. By using the relief printing plate 11 having such concave grooves 12b formed in the convex portions 12, the organic light emitting ink 3 adhered to the convex portions 12 is transferred to the light emitting layer forming region, thereby applying a uniform film thickness. A film can be formed, and as a result, a light emitting layer with a uniform thickness can be formed.

  It is preferable that at least one end in the longitudinal direction of the plurality of concave grooves 12b is opened on the side surface of the convex portion 12. That is, it is preferable that at least one end in the longitudinal direction of the plurality of concave grooves 12 b reaches the side surface of the convex portion 12. Further, in the surface portion of the convex portion 12, the concave grooves 12 b are formed on both side surfaces of the convex portion 12. It is preferable that they are formed between. After the organic light emitting ink is adhered by pressing the convex portion 12 against the light emitting layer forming region, when the convex portion 12 is separated from the light emitting layer forming region, the organic interposed between the convex portion 12 and the light emitting layer forming region. Negative pressure is generated in the luminescent ink. However, since the convex portion 12 is formed in an irregular shape, air can easily flow into the concave groove 12b, and the negative pressure generated in the coating film during the transfer of the organic light-emitting ink can be relieved. As a result, the transferred organic It is presumed that the film thickness of the coating film of the luminescent ink becomes uniform. In particular, when at least one end in the longitudinal direction of the groove 12b is open, air easily flows from the open end of the groove 12b into the groove 12b. Is assumed to be more uniform.

  The preferred range of the short-side dimension of the ridge 12a and the dimension of the concave groove 12b, that is, the stripe line-and-space dimension is not particularly limited, but is appropriately set according to the ink concentration, viscosity, solvent evaporation rate, and the like. Is done. Referring to FIG. 3, the height dimension (depth of the groove 12b) h of the ridge 12a is preferably 5 μm to 50 μm, and the width dimension (line width dimension) of the ridge 12a is 10 μm. ˜100 μm is preferable, and the width dimension of the groove 12b (space width dimension, width of the groove in the short direction) is preferably 10 μm to 100 μm.

  The longitudinal direction of the concave groove 12b, that is, the stripe forming direction is not particularly limited, but is preferably parallel to the printing direction of relief printing.

  The organic light emitting ink is prepared by dissolving or stably dispersing an organic light emitting material in a solvent. Examples of the solvent for dissolving or dispersing the organic light emitting material include toluene, xylene, acetone, anisole, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and the like alone or a mixed solvent thereof. Among these, aromatic organic solvents such as toluene, xylene, and anisole are preferable because they have good solubility of the organic light emitting material.

  In addition, you may add surfactant, antioxidant, a viscosity modifier, a ultraviolet absorber, etc. to organic luminescent ink as needed.

  Note that the size of the light emitting layer forming region is preferably 1 cm × 1 cm or more. Even in such a large region, the organic light-emitting ink can be uniformly applied, so that an organic EL element having a wide light-emitting area can be easily produced by a coating method.

(Step of forming a layer between the light emitting layer and the cathode)
After the formation of the light emitting layer, layers such as an electron transport layer and an electron injection layer are formed as necessary.
The method for forming an electron transport layer or an electron injection layer is not particularly limited in the case of an electron transport layer, but in the case of a low molecular electron transport material, a vacuum deposition method from powder, or a film formation from a solution or a molten state. In the polymer electron transport material, a method by film formation from a solution or a molten state is exemplified. In film formation from a solution or a molten state, a polymer binder may be used in combination. As a method for forming an electron transport layer from a solution, a film formation method similar to the method for forming a hole transport layer from a solution described above can be used.
In the case of an electron injection layer, it is formed using a vapor deposition method, a sputtering method, a printing method, or the like.

(Cathode formation process)
The cathode is formed by using any of the materials described above by vacuum deposition, sputtering, CVD, ion plating, laser ablation, or laminating a metal thin film.

  After forming the cathode, an upper sealing film is formed in order to protect the light emitting functional part having the anode-light emitting layer-cathode as a basic structure. The upper sealing film is composed of at least one inorganic layer and at least one organic layer as necessary. The number of these layers is determined as necessary. Basically, the inorganic layers and the organic layers are alternately stacked.

  In the first embodiment described above, the metal-doped molybdenum oxide layer is provided after the partition is formed. However, as another embodiment, the metal-doped molybdenum oxide layer may be formed before the partition is provided. In this case, the metal doped molybdenum oxide layer is formed in common for the plurality of organic EL elements.

  In the case where the metal doped molybdenum oxide layer is formed in common for a plurality of organic EL elements, the metal doped molybdenum oxide layer is formed as compared with the case where the metal doped molybdenum oxide layer is selectively formed between the partition walls. In this case, high-precision positioning is not necessary, and the process can be simplified. Furthermore, since the metal-doped molybdenum oxide layer is highly resistant to the wet process, the metal-doped molybdenum oxide layer is damaged when the partition wall formed by the wet process is provided after the metal-doped molybdenum oxide layer is formed on one surface. In this case, a highly reliable organic EL element can be obtained. Furthermore, although the partition is provided in the first embodiment, an organic EL element having a form in which no partition is provided may be manufactured.

  In addition, although the above-mentioned embodiment was a form at the time of applying to the bottom emission type element which radiate | emits the light from a light emitting layer to the exterior from a transparent support substrate, as another embodiment, the light from a light emitting layer is used. May be a top emission type element that passes through a transparent cathode and exits from a transparent protective layer.

  A planar light source and an illumination device can be configured using the organic EL element of the present embodiment.

  When the organic EL element of the present embodiment is used as a planar light source, for example, a planar anode and a cathode may be arranged so as to overlap each other when viewed from one side in the stacking direction.

  The planar light source is a self-luminous thin type and can be suitably used as a backlight of a display device such as a liquid crystal display device. Moreover, if a flexible board | substrate is used, it can be used also as a curved surface light source and an illuminating device.

  Hereinafter, the present invention will be described more specifically based on production examples and comparative examples, but the present invention is not limited to the following production examples.

  In the following Production Examples 1 to 6 and Comparative Examples 1 and 2, in order to confirm the effect of providing the metal-doped molybdenum oxide layer between the anode and the light emitting layer, the metal doping was performed between the anode and the light emitting layer. An organic EL device provided with a molybdenum oxide layer was manufactured.

(Production Example 1)
(A: Deposition of Al-doped MoO ₃ on a glass substrate by a vacuum deposition method)
A plurality of glass substrates were prepared, one side of which was partially covered with a vapor deposition mask, and attached to the vapor deposition chamber using a substrate holder.

MoO ₃ powder (manufactured by Aldrich, purity 99.99%) was packed in a tungsten board for a box-type sublimation substance, covered with a cover with holes so that the material would not scatter, and set in a vapor deposition chamber. Al (manufactured by Koyo Chemical Co., Ltd., purity 99.999%) was put in a crucible and set in a vapor deposition chamber.

The degree of vacuum in the vapor deposition chamber is set to 3 × 10 ⁻⁵ Pa or less, MoO ₃ is gradually heated by a resistance heating method and sufficiently degassed, and Al is dissolved in the crucible by an electron beam and fully desorbed. After performing the gas, it was subjected to vapor deposition. The degree of vacuum during vapor deposition was 9 × 10 ⁻⁵ Pa or less. The film thickness and the deposition rate were constantly monitored with a crystal resonator. When the deposition rate of MoO ₃ was about 0.28 nm / second and the deposition rate of Al was about 0.01 nm / second, the main shutter was opened and film formation on the substrate was started. During deposition, the substrate was rotated so that the film thickness was uniform. Film formation was performed for about 36 seconds while controlling the vapor deposition rate to the above speed, and a substrate provided with a co-deposition film having a thickness of about 10 nm was obtained. The composition ratio of Al to the total of MoO ₃ and Al in the film was about 3.5 mol%.

(B: Durability test)
After film formation, the obtained substrate was taken out into the atmosphere and the film surface was observed with an optical microscope (500 times). As a result, no crystal structure was observed, and it was confirmed that the film was in an amorphous state.
When the obtained substrate was exposed to pure water for 1 minute and observed again with an optical microscope, there was no change and the surface was not melted. In either case, the substrate was further exposed to pure water for 3 minutes, or the film was wiped with a non-woven fabric (trade name “Bencot”, manufactured by Ozu Sangyo Co., Ltd.) containing pure water and then visually observed. The membrane remained unchanged.

  Moreover, when the board | substrate obtained different from the board | substrate exposed to the said pure water was exposed to acetone for 1 minute and observed with the optical microscope, there was no change and the surface did not melt | dissolve. The substrate was further exposed to acetone for 3 minutes, or the film was wiped with a non-woven fabric containing acetone and visually confirmed. In either case, the film remained unchanged.

(C: Measurement of transmittance)
Further, the transmittance of the deposited film after film formation was measured using a transmittance / reflectance measuring apparatus (trade name “FilmTek 3000” manufactured by Scientific Computing International). The results are shown in (Table 1) below. The transmission spectrum rose from a wavelength of about 300 nm. The transmittance at a wavelength of 320 nm was 21.6%, and the transmittance at 360 nm was 56.6%. Compared to Comparative Example 1 described later, the transmittance was 3.6 times at 320 nm and 1.6 times at 360 nm.

(Production Example 2)
A substrate provided with a co-deposited film was obtained in the same manner as in Production Example 1 (A) except that oxygen was introduced into the chamber during the deposition. The amount of oxygen was controlled to 15 sccm by a mass flow controller. The degree of vacuum during vapor deposition was about 2.3 × 10 ⁻³ Pa. The thickness of the obtained co-deposited film was about 10 nm, and the composition ratio of Al to the total of MoO ₃ and Al in the film was about 3.5 mol%.

  After film formation, the durability of the obtained substrate was evaluated in the same manner as in Production Example 1 (B). No change was observed when exposed to either pure water or acetone.

(Production Example 3)
The deposition rate, the same procedure as about 0.37 nm / sec, for the Al about 0.001 nm / sec except that the control in the Preparation Example. 1 (A) for MoO _3, substrate co-evaporation film is provided Got. The thickness of the obtained co-deposited film was about 10 nm, and the composition ratio of Al to the total of MoO ₃ and Al in the film was about 1.3 mol%.

  After film formation, the durability of the obtained substrate was evaluated in the same manner as in Production Example 1 (C). No change was observed when exposed to either pure water or acetone.

(Production Example 4)
The substrate obtained in (A) of Preparation Example 1 was placed in a clean oven in an air atmosphere and heat-treated at 250 ° C. for 60 minutes. After cooling, the transmittance of the deposited film was measured in the same manner as in Production Example 1 (C). The results are shown in (Table 1) below. The transmittance at a wavelength of 320 nm was 28.9%, and the transmittance at 360 nm was 76.2%. Compared to Comparative Example 1 below, the transmittance was 4.7 times at 320 nm and 2.2 times at 360 nm.

(Comparative Example 1)
Except that Al was not deposited and only MoO ₃ was deposited at about 0.28 nm / second, the same operation as in Production Example 1 was performed to obtain a substrate provided with a deposited film having a thickness of about 10 nm.
After the film formation, the obtained substrate was taken out into the atmosphere and the film surface was observed with an optical microscope (500 times). As a result, it was confirmed that the crystal structure was not observed and the film was in an amorphous state.

  When the obtained substrate was exposed to pure water for 1 minute and observed again with an optical microscope, it was observed that a bleeding pattern was observed and the surface was melted. The substrate was further exposed to pure water for 3 minutes, or the film was wiped with a non-woven fabric soaked with pure water and visually observed. In all cases, the film disappeared.

  Another obtained substrate was exposed to acetone for 1 minute and observed with an optical microscope. As a result, a bleeding pattern was observed and the surface was melted. The substrate was further exposed to acetone for 3 minutes, or the film was wiped with a non-woven fabric containing acetone and then visually confirmed. In all cases, the film was lost.

  Further, the transmittance of the deposited film after film formation was measured in the same manner as in Production Example 1 (C). The results are shown below (Table 1). The transmittance at a wavelength of 320 nm was 6.1%, the transmittance at 360 nm was 35.4%, and it was confirmed that the transmittance was low.

(Synthesis Example 1)
2,7-bis (1,3,2-dioxaborolan-2-yl) -9,9-dioctyl was added to a separable flask equipped with a stirring blade, baffle, length-adjustable nitrogen inlet tube, cooling tube, and thermometer. Fluorene 158. 29 parts by weight of bis- (4-bromophenyl) -4- (1-methylpropyl) -benzenamine 136. 11 parts by weight, tricaprylmethylammonium chloride (Aliquat 336 manufactured by Henkel Co., Ltd.) 27 parts by weight, toluene 1800 parts by weight were charged, and the temperature was raised to 90 ° C. with stirring while flowing nitrogen from the nitrogen introduction tube.

  Next, 0.066 parts by weight of palladium (II) acetate and 0.45 parts by weight of tri (o-toluyl) phosphine were added, and then a 17.5% aqueous sodium carbonate solution (573 parts by weight) was added dropwise over 1 hour. did. After completion of the dropwise addition, the nitrogen inlet tube was lifted from the liquid level and kept under reflux for 7 hours, then 3.6 parts by weight of phenylboric acid was added, kept under reflux for 14 hours, and cooled to room temperature.

  After removing the reaction solution aqueous layer, the reaction solution oil layer was diluted with toluene and washed with 3% acetic acid aqueous solution and ion-exchanged water. To the separated oil layer, 13 parts by weight of sodium N, N-diethyldithiocarbamate trihydrate was added and stirred for 4 hours. Thereafter, the mixture was passed through a mixed column of activated alumina and silica gel, and toluene was passed through to wash the column.

The filtrate and washings were mixed and then added dropwise to methanol to precipitate the polymer. The obtained polymer precipitate was separated by filtration, washed with methanol, and then dried with a vacuum dryer to obtain 192 parts by weight of polymer. The resulting polymer is referred to as polymer compound P1. When the polystyrene equivalent weight average molecular weight and number average molecular weight of this polymer compound P1 were determined by the following GPC analysis method, the polystyrene equivalent weight average molecular weight was 3.7 × 10 ⁵ , and the number average molecular weight was 8.9 ×. There were 10 ⁴ .

(GPC analysis method)
The polystyrene equivalent weight average molecular weight and number average molecular weight were determined by gel permeation chromatography (GPC). Standard polystyrene made by Polymer Laboratories was used to prepare a GPC calibration curve. The polymer to be measured was dissolved in tetrahydrofuran to a concentration of about 0.02% by weight, and 10 μL was injected into the GPC apparatus.

  The GPC apparatus used was LC-10ADvp manufactured by Shimadzu Corporation. Two columns manufactured by Polymer Laboratories (“PLg electroluminescence” 10 μm MIXED-B column (300 × 7.5 mm)) were connected in series, and tetrahydrofuran was used as a mobile phase at 25 ° C., 1.0 mL / Flowed at a flow rate of min. The detector used was a UV detector, and the absorbance at 228 nm was measured.

(Production Example 5)
(Production of organic EL element)
A glass substrate having an ITO thin film patterned on the surface was used as a substrate, and an Al-doped MoO ₃ layer having a thickness of 10 nm was deposited on the ITO thin film by a vacuum deposition method in the same procedure as in Production Example 1.

  After the film formation, the substrate was taken out into the atmosphere, and the polymer compound P1 obtained in Synthesis Example 1 was formed on the vapor-deposited film by spin coating to form an interlayer layer having a thickness of 20 nm. The interlayer layer formed on the extraction electrode portion and the sealing area was removed, and baking was carried out on a hot plate at 200 ° C. for 20 minutes.

  Thereafter, a polymer light-emitting organic material (manufactured by RP158 Summation Co., Ltd.) was formed on the interlayer layer by a spin coating method to form a light-emitting layer having a thickness of 90 nm. The light emitting layer formed on the extraction electrode portion and the sealing area was removed.

  The subsequent processes up to the sealing were performed in vacuum or nitrogen so that the elements in the process were not exposed to the atmosphere.

  The substrate was heated at a substrate temperature of about 100 ° C. for 60 minutes in a vacuum heating chamber. Thereafter, the substrate was transferred to a vapor deposition chamber, and a cathode mask was aligned on the surface of the light emitting layer so that a cathode was formed on the light emitting portion and the extraction electrode portion. Further, the cathode was deposited while rotating the mask and the substrate. As a cathode, metal Ba is heated by a resistance heating method and deposited at a deposition rate of about 0.2 nm / second and a film thickness of 5 nm, and Al is deposited thereon by using an electron beam deposition method at a deposition rate of about 0.2 nm / second. The film was deposited with a film thickness of 150 nm.

Thereafter, the substrate is bonded to a prepared sealing glass coated with UV curable resin around the substrate, kept in vacuum, then returned to atmospheric pressure, fixed by irradiation with UV, and light emitting region Produced a 2 × 2 mm organic EL device.
The obtained organic EL device had a layer structure of glass substrate / ITO film / Al-doped MoO ₃ layer / interlayer layer / light emitting layer / Ba layer / Al layer / sealing glass.

(Evaluation of organic EL elements)
The manufactured element was energized so that the luminance was 1000 cd / m ^2, and current-voltage characteristics were measured. In addition, the device was driven at a constant current at 10 mA, light emission was started at an initial luminance of about 2000 cd / m ² , the light emission was continued as it was, and the light emission lifetime was measured. The results are shown in the following (Table 2) and (Table 3). Compared to Comparative Example 2 described later, the maximum power efficiency is slightly higher, the driving voltage at the time of 1000 cd / m ² emission is reduced, and the life is extended by about 1.6 times.

(Production Example 6)
Except that the Al-doped MoO ₃ layer was formed in the same procedure as in Production Example 3, the same procedure as in Production Example 5 was followed to produce an organic EL device, and current-voltage characteristics and emission lifetime were measured. The emission lifetime was measured by driving at a constant current of 10 mA, starting emission at an initial luminance of about 2000 cd / m ² , and then continuing emission. The results are shown in the following (Table 2) and (Table 3). Compared with Comparative Example 2 below, the maximum power efficiency is slightly higher, the driving voltage at the time of light emission of 1000 cd / m ² is lowered, and the life is extended about 2.4 times.

(Comparative Example 2)
Instead of forming the Al-doped MoO ₃ layer, the same procedure as in Comparative Example 1 was followed, except that the MoO ₃ layer was formed in the same manner as in Production Example 5 to produce an organic EL device, and the current-voltage characteristics The emission lifetime was measured. The light emission lifetime was measured by driving at a constant current of 10 mA, starting light emission at an initial luminance of about 2000 cd / m ² , and continuing light emission as it was. The results are shown in the following (Table 2) and (Table 3).

  In Preparation Examples 7 and 8 shown below, using a relief printing plate having a shape corresponding to the light emitting layer forming region where the light emitting layer is formed and having a convex portion in which a plurality of concave grooves are formed on the surface portion, In order to confirm the effect of the method of forming a light emitting layer by supplying an organic light emitting ink containing an organic light emitting material and a solvent to the light emitting layer forming region, a simulated experimental example was performed.

(Production Example 7)
An organic luminescent ink was applied onto a glass substrate using a relief printing plate. A transparent glass plate of 200 mm (length) × 200 mm (width) × 0.7 mm (thickness) was used for the glass substrate.
Further, as the ink, an organic light emitting ink was prepared by dissolving a polymer light emitting material (product name “GP1300”, manufactured by Sumation Corporation) in a mixed solvent in which anisole and cyclohexylbenzene were mixed at a weight ratio of 1: 1. The concentration of the polymer light emitting material in the organic light emitting ink was 1% by weight.

The printing machine used for printing was “Angstroma SDR-0023 (trade name), plate drum diameter: 80 mm” manufactured by Nissha Printing Co., Ltd. The printing speed was 50 mm / second.
Printing was performed in a state in which the plate and the substrate were in contact with each other with a printing push amount of 0 μm, and the plate was pressed from that position by 50 μm (print push amount = 50 μm).

  A flexographic printing plate (letter printing plate) made of polyester resin was used as the printing plate. A plurality of concave grooves arranged at equal intervals are formed on the surface portion of the flexographic printing plate. The width (line) in the short direction of the ridge was 40 μm, and the width (space) in the short direction of the groove was 40 μm (line / space = 40 μm / 40 μm). The height of the ridge was 15 μm.

(Production Example 8)
Only the flexographic printing plate was changed, and the organic light emitting ink was applied on the glass substrate in the same manner as in Preparation Example 7.
A plurality of concave grooves arranged at equal intervals are formed on the surface portion of the used flexographic printing plate. The width (line) in the short direction of the ridge was 30 μm, and the width (space) in the short direction of the groove was 50 μm (line / space = 30 μm / 50 μm). The height of the ridge was 15 μm.

(Comparative Example 3)
Only the flexographic printing plate was changed, and the organic light emitting ink was applied on the glass substrate in the same manner as in Preparation Example 7. As the flexographic printing plate, a plate having a flat surface (solid plate) was used.

(Comparative Examples 4 to 8)
Only the flexographic printing plate was changed, and the organic light emitting ink was applied on the glass substrate in the same manner as in Preparation Example 7. In Comparative Examples 4, 5, 6, 7, and 8, halftone plates of 100 / inch, 200 / inch, 400 / inch, 600 / inch, and 900 / inch were used, respectively. The height of the halftone dot was 15 μm.

(Evaluation)
Ultraviolet rays were applied to the printed material, and the fluorescence (PL) intensity distribution from the coating film was observed with an optical microscope to evaluate the printed film thickness distribution (printing unevenness). The evaluation results are shown in Table 4.

なお、表１において、記号「○」は、印刷ムラがなかったことを表し、記号「×」は、印刷ムラがあったことを表す。

In Table 1, the symbol “◯” represents that there was no printing unevenness, and the symbol “x” represents that there was printing unevenness.

  From the above results, it was confirmed that the organic light-emitting ink can be applied with a uniform film thickness by forming a plurality of concave grooves on the convex surface of the relief printing plate.

It is a cross-sectional block diagram of this convex part which shows the surface structure of the convex part of the relief printing plate used in order to form a light emitting layer in manufacture of the conventional organic EL element. It is a cross-sectional block diagram of this convex part which shows the surface structure of the convex part of the relief printing plate used in order to form a light emitting layer in manufacture of the organic EL element of this invention. It is an expanded sectional block diagram of the convex part surface of the relief printing plate shown in FIG.

Explanation of symbols

3 Organic Luminous Ink 11 Letterpress Printing Plate 12 Projection 12a Projection 12b Projection Groove

Claims (10)

A method for producing an organic electroluminescent device comprising a cathode, an anode, a light emitting layer disposed between the cathode and the anode, and a metal-doped molybdenum oxide layer disposed between the anode and the light emitting layer. And
Preparing a substrate provided with an anode;
A metal-doped molybdenum oxide layer forming step;
A relief printing plate having a shape corresponding to a light emitting layer forming region in which the light emitting layer is formed after the metal doped molybdenum oxide layer forming step and having a convex portion having a plurality of concave grooves formed on the surface portion A step of forming a light emitting layer by supplying an organic light emitting ink containing an organic light emitting material and a solvent constituting the light emitting layer to the light emitting layer forming region,
The manufacturing method of the organic electroluminescent element which has a process of forming a cathode.   The method for producing an organic electroluminescence element according to claim 1, wherein in the metal-doped molybdenum oxide layer forming step, the metal-doped molybdenum oxide layer is formed by simultaneously depositing molybdenum oxide and a dopant metal.   The manufacturing method of the organic electroluminescent element of Claim 1 or 2 with which the dopant metal contained in the said metal dope molybdenum oxide layer is selected from the group which consists of a transition metal, a periodic table group 13 metal, and mixtures thereof.   The method for producing an organic electroluminescent element according to claim 3, wherein the dopant metal is aluminum.   The ratio of the dopant metal contained in the said metal dope molybdenum oxide layer is 0.1-20.0 mol%, The manufacturing method of the organic electroluminescent element of any one of Claims 1-4.   6. The method of manufacturing an organic electroluminescence element according to claim 1, wherein at least one end in the longitudinal direction of the plurality of concave grooves is open on a side surface of the convex portion.   The method for manufacturing an organic electroluminescence element according to claim 1, wherein the size of the light emitting layer forming region is 1 cm × 1 cm or more.   The organic electroluminescent element obtained using the manufacturing method of the organic electroluminescent element of any one of Claims 1-7.   An illuminating device comprising the organic electroluminescence element according to claim 8.   A planar light source comprising the organic electroluminescence element according to claim 8.

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