JP2010147180A - Method of manufacturing organic electroluminescence element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an organic EL element in which a light emitting layer can be formed without causing film absence, the manufacture is easy, and excellent lifetime characteristics of the obtained element are made excellent, the organic EL element, a lighting device, a surface type light source, and a display device. <P>SOLUTION: The method of manufacturing the organic EL element which has, on a substrate, a cathode, an anode, and the light emitting layer disposed between the cathode and anode, and a metal-doped molybdenum oxide layer disposed between the anode and light emitting layer, includes: a barrier forming process of forming a barrier enclosing a pixel region where the light emitting layer is provided when viewed from one thickness-directional side of the substrate; a surface processing process of processing a surface with an organic solvent from the side where the barrier is installed on the substrate; and a light emitting layer forming process of forming the light emitting layer by supplying ink containing an organic light emitting material to the pixel region enclosed with the barrier after the surface processing process. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an organic electroluminescence element (hereinafter sometimes referred to as an organic EL element), a method for producing the organic EL element, an illumination device using the organic EL element, a planar light source, and a display device.

  The 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.

  A display device using organic EL elements uses a display panel in which a large number of organic EL elements each functioning as one pixel are arranged in a matrix. In such a display panel, in order to secure a large number of pixels, the first electrode is formed in a fine pattern, and a large number of pixel regions are formed on the patterned first electrode (anode or cathode). Therefore, a grid-like partition is formed. The partition walls are formed by forming a photoresist film on the first electrode pattern and patterning the photoresist film using a photolithography technique. The first electrode is exposed in a pixel region surrounded by a large number of partition walls.

  The partition wall is formed by adding an ink repellency (water repellency) substance to the photoresist, or by selectively coating the surface with an ink repellant substance after the partition wall is formed, Sex is imparted. Next, a light emitting layer is formed in these pixel regions, but before that, one layer or two or more organic material layers may be formed.

  As a method of forming a light emitting layer with a film thickness on the order of 100 nm in each pixel region, there is also a method using a vacuum vapor deposition method. However, usually, highly accurate and efficient layer formation (film formation) is possible. A coating method is used. This coating method is a method in which an organic light emitting material is dissolved in a solvent to form a coating solution, and this coating solution is selectively applied to the pixel region. For example, a relief printing method, an inkjet printing method, or the like is used.

  Conventionally, for example, a method disclosed in Patent Document 1 is known as a method for forming a light emitting layer using the relief printing method. The feature of the method disclosed in Patent Document 1 is that a partition wall is formed by using a partition material in which an ink repellent substance is mixed in a photoresist, thereby providing ink repellency to the surface of the partition wall, and ink repellency. The light emitting layer is formed by selectively supplying the coating liquid to the pixel region defined by the partition walls by letterpress printing.

  Since the ink repellency is imparted to the surface of the partition wall, when the organic luminescent ink for forming the luminescent layer is supplied to the pixel area by letterpress printing, the ink repellency is not affected even if the organic luminescent ink may adhere to the partition wall. Therefore, color mixing of the organic light emitting material between adjacent pixel regions can be prevented.

  As described in Patent Document 1, a method of forming a light emitting layer by supplying an organic light emitting ink to a pixel region whose surface is defined by an ink repellent partition using a relief printing method is effective for an organic EL element. However, according to the study by the present inventors, it has been found that there are the following problems to be solved.

  That is, for example, when organic light emitting ink is selectively supplied into each pixel area by letterpress printing, the organic light emitting ink may be repelled not only in the periphery of the pixel area but also in the pixel area. It may not be possible to apply to the entire region, and the area of the pixel region that actually emits light may be less than the design value. The amount of light emitted from a pixel having such a coating defect is equal to or less than the design value, and in some cases, light emission is not possible. As a result, unevenness in light emission occurs, and the light emission quality is significantly lowered.

  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 oxide such as molybdenum oxide is formed between a light emitting layer and an electron injection electrode. There is an organic EL element provided with a physical layer (see, for example, Patent Document 2).

  However, since the inorganic oxide layer has low resistance to a wet process, the wet process in forming the partition wall or the light-emitting layer may damage the molybdenum oxide layer. As a result, the molybdenum layer may be eluted, and as a result, there is a problem that an organic EL element having high 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 that a light-emitting layer can be formed without causing film defects, the manufacturing is easy, and the lifetime characteristics of the obtained element. It is to provide a method for manufacturing an organic EL element capable of improving the quality, an organic EL element obtained by the manufacturing method, a lighting device using the organic EL element, a planar light source, and a display device. .

  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, an illumination device using the organic EL element, and a planar light source A display device is provided.

[1] A method for producing an organic electroluminescence device, which is provided on a substrate and is configured by arranging an anode, a metal-doped molybdenum oxide layer, a light emitting layer, and a cathode in this order from the substrate side, wherein the anode is formed A step of preparing a substrate, a step of forming a metal-doped molybdenum oxide layer, and a partition formation step of forming a partition so as to surround a pixel region where the light emitting layer is provided when viewed from one of the thickness directions of the substrate And a surface treatment step of treating the surface of the element precursor having the partition wall formed on the substrate with an organic solvent, and after the surface treatment step, supplying an ink containing an organic light emitting material to the pixel region surrounded by the partition wall. A method for producing an organic electroluminescent element, comprising: a light emitting layer forming step of forming the light emitting layer; and a step of forming a cathode.

[2] The organic electroluminescence device according to [1], wherein in the step of forming the metal-doped molybdenum oxide layer, the metal-doped molybdenum oxide layer is formed by simultaneously depositing molybdenum oxide and a dopant metal. Manufacturing method.

[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. Electroluminescence element.

[4] The organic electroluminescence device according to [3], wherein the dopant metal is aluminum.

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

[6] The organic electroluminescence device according to any one of [1] to [5], wherein the surface treatment step is a step of bringing an organic solvent into contact with the surface of the device precursor. Manufacturing method.

[7] The method for producing an organic electroluminescent element according to the above [6], wherein in the surface treatment step, an organic solvent is brought into contact with the surface of the element precursor by a spin coating method.

[8] The method for producing an organic electroluminescent element according to the above [6] or [7], wherein in the surface treatment step, an organic solvent is brought into contact with the surface and then the organic solvent is dried.

[9] The method for producing an organic electroluminescent element as described in any one of [1] to [8] above, wherein the organic solvent is one or more of ink solvents.

[10] The production of an organic electroluminescence device according to any one of [1] to [9], wherein the organic solvent is one or more of the solvents for the organic light-emitting material. Method.

[11] The method for producing an organic electroluminescent element as described in [9] or [10] above, wherein the organic solvent is anisole.

[12] In any one of the above [1] to [11], in the light emitting layer forming step, ink containing an organic light emitting material is supplied to a pixel region surrounded by the partition by a printing method. The manufacturing method of the organic electroluminescent element of description.

[13] An organic electroluminescence device obtained by using the method for producing an organic electroluminescence device according to any one of [1] to [12].

[14] An illumination device comprising the organic electroluminescence element according to [13].

[15] A planar light source comprising the organic electroluminescence device according to [13].

[16] A display device comprising the organic electroluminescence element according to [13].

According to the present invention, it is possible to provide an organic EL element that is easy to manufacture and has good light emission characteristics and lifetime characteristics. In addition, the method for producing an organic EL element according to the present invention includes the step of applying an organic light emitting ink before applying an ink containing an organic light emitting material (hereinafter sometimes referred to as organic light emitting ink) to a pixel region surrounded by a partition wall. Since the ink repellency is eased by treating the surface to be coated with an organic solvent, the coating property when the organic light-emitting ink is applied to the pixel area is improved, and the coating failure of the organic light-emitting ink is greatly improved. There is an effect that can be. Therefore, according to the present invention, it is possible to provide an organic EL element having excellent light emission characteristics with reduced light emission unevenness on the light emitting surface.
Therefore, the organic EL element of the present invention can be preferably used as a display device such as a lighting device, a planar light source as a backlight, and a flat panel display.

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

  The organic EL device according to the present invention is a method for producing an organic electroluminescence device that is provided on a substrate and is configured by arranging an anode, a metal-doped molybdenum oxide layer, a light emitting layer, and a cathode in this order from the substrate side. A partition for enclosing a pixel region in which the light emitting layer is provided when viewed from one side in the thickness direction of the substrate, and a step of preparing a substrate on which an anode is formed, a step of forming a metal-doped molybdenum oxide layer A partition formation step for forming the surface, a surface treatment step for treating the surface of the element precursor having the partition wall formed on the substrate with an organic solvent, and an organic light emitting material in the pixel region surrounded by the partition after the surface treatment step. A light emitting layer forming step of forming the light emitting layer by supplying an ink containing a cathode, 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 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 the bottom emission type organic EL element that takes out light from the light emitting layer from the substrate side, a substrate having a high light transmittance in the visible light region is preferably used.
Note that in the top emission type organic EL element that extracts light from the light emitting layer from the cathode side, the substrate may be transparent or opaque.

(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.

Examples of the method for forming the anode include a vacuum deposition method, a sputtering method, an ion plating method, and a plating method.
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 this embodiment, a metal-doped molybdenum oxide layer is provided between the anode and the light emitting layer as an essential component. That is, the layer provided between the anode and the light emitting layer is composed of only a metal-doped molybdenum oxide layer, or is composed of a laminate including the metal-doped molybdenum oxide layer. Examples of the layer provided between the anode and the light emitting layer include a hole injection layer, a hole transport layer, an electron blocking layer, and the like, and the metal-doped molybdenum oxide layer functions as at least one of these layers.

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 an anode, a hole injection layer, or a 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.

  The metal-doped molybdenum oxide layer contains molybdenum oxide and a dopant metal, and preferably consists essentially of molybdenum oxide and dopant metal. More specifically, when the metal-doped molybdenum oxide layer is formed as a single layer, the proportion of the total of the molybdenum oxide and the dopant metal in the total amount of the substances constituting the layer is preferably 98% by mass or more, More preferably, it is 99 mass% or more, More preferably, it is 99.9 mass% or more.

The metal doped molybdenum oxide layer is 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.

(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. When the hole injection layer is constituted by a member different from the metal-doped molybdenum oxide, a known material can be appropriately used as the material constituting the hole injection layer, 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, dichloroethane, ether solvents such as tetrahydrofuran, toluene, xylene And aromatic hydrocarbon solvents such as acetone, 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)
When the hole transport layer is composed of a member different from the metal-doped molybdenum oxide, the material constituting the hole transport layer is not particularly limited. For example, N, N′-diphenyl-N, N′— Aromatic amine derivatives such as di (3-methylphenyl) 4,4′-diaminobiphenyl (TPD), 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPB), polyvinyl Carbazole or derivative thereof, polysilane or derivative thereof, polysiloxane derivative having aromatic amine in the side chain or main chain, pyrazoline derivative, arylamine derivative, stilbene derivative, triphenyldiamine derivative, polyaniline or derivative thereof, polythiophene or derivative thereof, Polyarylamine or a derivative thereof, polypyrrole or a derivative thereof Examples include derivatives, poly (p-phenylene vinylene) or derivatives thereof, or poly (2,5-thienylene vinylene) or derivatives thereof.

  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 can dissolve a hole transport material. Chlorine solvents such as chloroform, methylene chloride, dichloroethane, ether solvents such as tetrahydrofuran, toluene, xylene And aromatic hydrocarbon solvents such as acetone, 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 charge transport are preferable, and those that weakly absorb visible light are preferably used. For example, polycarbonate, polyacrylate, polymethyl acrylate, polymethyl methacrylate, polystyrene, poly Examples thereof include vinyl 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, and preferably contains a high molecular compound having a polystyrene-equivalent number average molecular weight of 10 ³ to 10 ⁸ . 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, trifumanylamine 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 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.

(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.

  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, a combination example of layer configurations from the anode to the cathode is 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 the above layer configuration, the hole injection layer or the hole transport layer provided between the anode and the light emitting layer corresponds to the metal-doped molybdenum oxide layer.

Further, the organic EL element of the present embodiment may have two or more light emitting layers, and examples of the organic EL element having two light emitting layers include the layer configuration shown in the following m). Can do.
m) Anode / charge injection layer / hole transport layer / light emitting layer / electron transport layer / charge injection layer / charge generation layer / charge injection layer / hole transport layer / light emitting layer / electron transport layer / charge injection layer / cathode Specifically, as an organic EL device having three or more light-emitting layers, (charge generation layer / charge injection layer / hole transport layer / light-emitting layer / electron transport layer / charge injection layer) is one repeating unit. Examples of the layer structure include two or more repeating units shown in n) below.
n) Anode / charge injection layer / hole transport layer / light-emitting layer / electron transport layer / charge injection layer / (the repeating unit) / (the repeating unit) /... / cathode In the above layer configurations m) and n) The layers other than the anode, the electrode, the cathode, and the light emitting layer can be deleted as necessary.
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 an organic EL element, an anode is usually disposed on the substrate side, but a cathode may be disposed on the substrate side.

  In the organic EL element of the present 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 to the electrode and 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. The present invention can be similarly applied to other forms of the top emission type that transmit light 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.

(Partition forming process)
After forming the line-shaped anode, a photosensitive material is applied onto the substrate on which the anode is formed, and a photoresist film is laminated. Next, this photoresist film is patterned into a lattice shape by photolithography to form an insulating partition. A rectangular region covered with the lattice-shaped partition walls becomes a pixel region, and the patterned anode is exposed in this pixel region.

  The insulating photosensitive material forming the insulating partition may be either a positive resist or a negative resist. It is important that the partition walls have insulating properties. If they do not have insulating properties, current may flow between different pixels, and display defects may occur.

  Specifically, polyimide, acrylic resin, and novolak resin photosensitive compounds can be used as the photosensitive material constituting the partition. This photosensitive material may contain a light-shielding material for the purpose of improving the display quality of the organic EL element.

  In order to impart ink repellency to the surface of the insulating partition, an ink repellant may be added to the photosensitive material for forming the partition. Alternatively, after the insulating partition is formed, the surface of the partition may be coated with an ink repellent material to impart ink repellency to the partition surface. This ink repellency is preferably repellant both for the ink of layers other than the light emitting layer described later and for the ink for the light emitting layer.

  As the ink repellent compound used when an ink repellent substance is added to the photosensitive material, a silicone compound or a fluorine-containing compound is used. These ink repellent compounds have ink repellency for both the organic light emitting ink (coating liquid) used for forming the light emitting layer described later and the organic material ink (coating liquid) for layers other than the light emitting layer such as the hole transport layer. In order to show, it can use suitably.

As a method of forming an ink-repellent film on the surface of the partition after forming the partition, a method of applying a coating liquid containing an ink-repellent component to the surface of the partition, or replacing a functional group of the organic material on the partition surface with fluorine Examples thereof include a method for modifying the surface by vaporizing, a method for vaporizing an ink repellency component, and depositing it on the partition wall surface. Specific examples of the latter vapor deposition method include plasma treatment using CF ₄ gas as an introduction gas. Compared to a substrate and an electrode, the organic partition walls are easily fluorinated by CF ₄ gas, and the surface of the partition walls can be selectively made ink-repellent by performing plasma treatment.

  The photosensitive material (photoresist composition) for forming the insulating partition can be applied by a coating method using a spin coater, bar coater, roll coater, die coater, gravure coater, slit coater or the like. After curing, the coating film is patterned into a lattice shape having a desired dimension using conventional photolithography.

(Metal-doped molybdenum oxide layer forming process)
After the insulating partition is formed, before the subsequent surface treatment step, layers such as a hole injection layer, a hole transport layer, and an electron blocking layer are provided in the pixel region. 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 lamination 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 carried out on an anode or cathode layer provided on a substrate to obtain a metal-doped molybdenum oxide layer in direct contact with the electrode. Alternatively, after an electrode is provided on the substrate, one or more other layers such as a light emitting layer, a charge injection layer, a charge transport layer, or a charge blocking layer are provided on the electrode, and deposition is further performed thereon. A metal-doped molybdenum oxide layer in direct contact can be obtained.

  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. There are 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, a counter target sputtering method, and the like, and any of these methods 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, MoO ₃ or a single metal is usually used as the molybdenum oxide and the dopant metal material, but an oxide of MoO ₂ or a dopant metal, an alloy of a dopant metal and Mo, a mixture thereof, or the like can be used.

The deposited metal-doped molybdenum oxide layer is subjected to other processes such as heating, UV-O ₃ treatment, atmospheric exposure, etc. as it is or optionally.

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.

  As is apparent from the above-described formation process, the formed metal-doped molybdenum layer has a characteristic that the liquid resistance is very high. Therefore, a layer formed on the metal-doped molybdenum layer such as a light emitting layer can be formed by a wet process which is an easy and easy process during film formation.

  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.

  Solvents used for film formation from solution include chlorine solvents such as chloroform, methylene chloride, dichloroethane, ether solvents such as tetrahydrofuran, aromatic hydrocarbon solvents such as toluene and xylene, and ketone solvents such as acetone and methyl ethyl ketone. And ester solvents such as ethyl acetate, butyl acetate, and ethyl cellosolve acetate.

  As a film forming method from the above solution, a spin coating method from a solution, 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 slit coating method, Coating methods such as a capillary coating method, a spray coating method, a nozzle coating method, etc., a gravure printing method, a screen printing method, a flexographic printing method, an offset printing method, a reverse printing method, a printing method such as an inkjet printing method, etc. may be used. it can. A printing method such as a gravure printing method, a screen printing method, a flexographic printing method, an offset printing method, a reverse printing method, and an ink jet printing method is preferable in that the pattern formation is easy.

  As the polymer binder to be mixed, those not extremely disturbing charge transport are preferable, and those not strongly absorbing visible light are suitably used. Examples of such a polymer binder include polycarbonate, polyacrylate, polymethyl acrylate, polymethyl methacrylate, polystyrene, polyvinyl chloride, polysiloxane and the like.

  When the coating solution is applied to the entire surface of the substrate by the above coating method, the coating solution may be applied onto the partition wall. In this case, the coating solution on the partition wall is repelled by the surface of the partition wall showing ink repellency. Thus, it falls into the pixel area divided by the partition walls, and is formed as a coating film in each pixel area. The coating film in each pixel region is then dried to form a predetermined layer, which exhibits its function.

(Surface treatment process)
In the conventional method for manufacturing an organic EL element, as described above, a light emitting layer is formed after forming a layer provided as necessary. In the present invention, before the light emitting layer is formed, a partition wall is provided on the substrate. From the formed side, the surface (the surface of the element precursor having the partition formed on the substrate) is treated with an organic solvent.

  This surface treatment process is realized by bringing the organic solvent into contact with the surface from the side where the partition walls are installed with respect to the substrate. The contact with the organic solvent needs to be performed on at least the surface of the partition wall and may not be performed on the entire surface of the substrate, but is preferably performed on the entire surface of the element precursor.

  Examples of the method of contacting the organic solvent with the substrate surface include a spin coating method in which the organic solvent is dropped onto the rotating substrate and the organic solvent is brought into contact with the entire surface of the substrate, a method of applying or spraying the organic solvent on the inclined substrate, A method of lifting the substrate after the substrate is immersed in an organic solvent is used. After bringing the organic solvent into contact with the entire surface of the substrate or the partition walls and the pixel region surface by any method, it is preferable to dry the organic solvent with the surface in contact so that no droplets of the organic solvent remain. Drying methods include heat drying, natural drying, and air blowing.

  As an organic solvent to be used, it is preferable that it is 1 type, or 2 or more types of the solvent for inks, and it is further more preferable that it is 1 type or 2 or more types of the solvent for organic luminescent materials mentioned later among the solvents for inks. Specific examples of the solvent for the organic light emitting material include toluene, xylene, acetone, anisole, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and a mixed solvent thereof, and anisole is preferable.

  The surface treatment with the organic solvent slightly reduces the ink repellency on the partition wall surface, but does not impair the ink repellency. That is, even when the organic light emitting ink is applied on the partition after the surface treatment of the partition with the organic solvent, the performance of repelling the organic light emitting ink on the partition is not impaired, and it is necessary. The ink repellency that remains is still alive.

(Light emitting layer forming step)
After the above-described surface treatment process is completed, a light emitting layer forming process is performed.
As the organic light emitting material used for the light emitting layer, the above-described high molecular organic light emitting material and / or low molecular organic light emitting material are used.

  In the case of using a polymer light emitting material, the polymer material is dissolved or stably dispersed in a solvent to prepare an organic light emitting material coating liquid (organic light emitting ink). 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, 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. Moreover, you may add surfactant, antioxidant, a viscosity modifier, a ultraviolet absorber, etc. to the ink of organic luminescent material as needed.

  As a method of supplying a coating liquid (organic light-emitting ink) containing an organic light-emitting material to the pixel region surrounded by the partition wall, in the case where the organic EL element emits monochromatic light used in a lighting device, selective coating is considered. Because there is no need, spin coating method, casting method, micro gravure coating method, gravure coating method, bar coating method, coal coating method, wire bar coating method, dip coating method, slit coating method, capillary coating method, spray coating method, A coating method such as a nozzle coating method may be used. When the organic EL element emits multicolor light for use in a color display device, it is necessary to selectively apply a predetermined organic light emitting ink to each pixel region to avoid color mixing. For such selective coating, printing methods such as gravure printing, screen printing, flexographic printing, offset printing, reverse printing, and inkjet printing can be used. Among these, the inkjet printing method and the flexographic printing method are preferable, and the flexographic printing method is particularly preferable in order to more accurately apply the organic light-emitting ink to the pixel region surrounded by the partition walls.

  When the organic light emitting ink is applied to the pixel region surrounded by the partition wall by any of the above methods, the coating liquid is applied on the side surface of the ink-repellent partition wall and the surface of the anode or the layer provided as necessary in the conventional method. In this embodiment, the surface treatment process using an organic solvent is performed before the light-emitting layer forming process, so that the ink repellency is moderately moderated. As a result, coating unevenness is prevented, and the organic light emitting ink is applied so as to spread over the entire pixel area as designed, and a coating film is formed over the entire pixel area. Thus, the organic light emitting coating film formed in each pixel region without causing uneven coating becomes a light emitting layer through a drying process as necessary, and exhibits its function.

(Step of forming a layer between the light emitting layer and the cathode)
After the formation of the light emitting layer, layers such as a hole transport layer and a hole injection layer are formed as necessary.
The method of forming a layer such as a hole transport layer or a hole 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 from a solution or a molten state. A method by film formation is exemplified, and for polymer electron transport materials, 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.

  Note that the metal-doped molybdenum oxide layer may be formed before the partition is formed. When the metal-doped molybdenum oxide layer is formed after the partition wall is formed, it is necessary to selectively form the metal-doped molybdenum oxide in each pixel region, but before the partition wall is formed, the metal-doped molybdenum oxide layer For example, a metal-doped molybdenum oxide layer may be formed over the entire surface of the substrate across a plurality of pixel regions, and the process can be simplified. In particular, since the metal-doped molybdenum oxide layer has high resistance to a wet process, damage to the metal-doped molybdenum oxide layer is small even in the formation of a partition that requires a wet process. Therefore, by forming the metal-doped molybdenum oxide layer before forming the partition wall in this way, a high-performance organic EL element can be formed by a simple process.

  The organic EL element of the embodiment of the present invention as described above can be suitably used for a curved or flat illumination device, for example, a planar light source used as a light source of a scanner, and a display device.

  Examples of the display device including an organic EL element include a segment display device and a dot matrix display device. The dot matrix display device includes an active matrix display device and a passive matrix display device. An organic EL element is used as a light emitting element constituting each pixel in an active matrix display device and a passive matrix display device. In addition, the organic EL element is used as a light emitting element constituting each segment in the segment display device, and is used as a backlight in the liquid crystal display 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 substrate was supplied to the substrate before supplying the organic light emitting ink. Thus, an organic EL device in which a metal-doped molybdenum oxide layer was provided between the anode and the light-emitting layer was manufactured without performing the surface treatment step of treating with an organic solvent from the side where the partition walls were installed.

(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 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, 27 parts by weight of tricaprylmethylammonium chloride (Aliquat 336 manufactured by Henkel) and 1800 parts by weight of toluene 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 ×. 10 was ^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. As the column, two columns manufactured by Polymer Laboratories (“PLgel” 10 μm MIXED-B column (300 × 7.5 mm)) were connected in series, and tetrahydrofuran was used as a mobile phase at 25 ° C. and 1.0 mL / min. Flowed at a flow rate. 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 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 performed at 200 ° C. for 20 minutes on a hot plate.

  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).

(Production Example 7)
In Production Example 7 shown below, a hole injection layer was provided as a layer between the anode and the light-emitting layer, but a metal-doped molybdenum oxide layer was not provided, and a layer between the light-emitting layer and the cathode was not provided. A laminated organic EL element was produced. Since the feature of the present invention is that it has a surface treatment step with an organic solvent on the surface of the element precursor, it is for all types of organic EL elements other than the laminated structure shown in the following fabrication examples. Similarly, the present invention can be applied, and the same effects can be obtained.

(Preparation of substrate and formation of anode)
First, an ITO thin film was formed on a transparent glass plate of 200 mm (vertical) × 200 mm (horizontal) × 0.7 mm (thickness), and further patterned to form a striped anode. The repetition interval (pitch) of the anode was 80 μm, and the interval (space) between the anodes was 10 μm with respect to the width of the anode (line) of 70 μm (line / space = 70 μm / 10 μm). A pixel region in which pixels are formed when viewed from one side in the thickness direction of the substrate is set in an island shape at a predetermined interval in the one direction on an ITO thin film extending in one direction.

(Formation of partition walls)
Next, a positive photoresist (trade name “OFPR-800”, manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied to the entire surface of the substrate by a spin coating method, and this coating film is dried to obtain a film thickness of 1 μm. A photoresist layer was formed.
Next, a photomask designed to shield the region excluding the pixel region where the pixel is formed from one side in the thickness direction of the substrate from ultraviolet rays is disposed on the photoresist layer, and an alignment exposure machine ( The photoresist layer was irradiated with ultraviolet rays through the photomask from Dainippon Screen Mfg. Co., Ltd. (trade name “MA1300”) (exposure process).
Following the exposure step, the exposed portion of the photoresist layer was removed using a resist developer (trade name “NMD-3”, manufactured by Tokyo Ohka Kogyo Co., Ltd.) (development step).
Subsequently, the glass substrate was heat-treated at 230 ° C. for 1 hour on a hot plate to completely heat and cure the developed photoresist layer (thermosetting step).

  Through the series of photolithography processes, a partition wall (organic insulating layer) surrounding the pixel region is formed, and the anode is exposed in the pixel region surrounded by the partition wall. The width dimension of the obtained partition line was 20 μm, and the height dimension was 2 μm. Each pixel region was a rectangle of 60 μm × 180 μm.

Next, the partition walls were subjected to ink repellency using a vacuum plasma apparatus (trade name “RIE-200L”, manufactured by Samco International Laboratories) using CF ₄ gas.

(Formation of hole injection layer)
Next, a suspension of poly (3,4-ethylenedioxythiophene) / polystyrene sulfonic acid (manufactured by Bayer, trade name “BaytronP AI4083”) was filtered through a 0.2 μm membrane filter. This filtrate was applied to the pixel region by a nozzle coating method. Subsequently, this coating layer was heat-treated at 200 ° C. for 20 minutes to form a 60 nm-thick hole injection layer.

(Treatment of the partition wall substrate surface with a solvent)
Next, a total amount of 30 mL of anisole was continuously dropped on the substrate, and the anisole was contacted (coated) on the entire surface of the substrate by a spin coating method. Then, the board | substrate was dried by performing an air blow process for about 30 minutes.

(Formation of light emitting layer)
Organic light-emitting ink (concentration of polymer light-emitting material) in which a polymer light-emitting material (trade name “RP158”, manufactured by Sumation Corporation) is dissolved as an organic light-emitting material in a mixed solvent in which anisole and cyclohexylbenzene are mixed at a weight ratio of 1: 1. : 1% by weight). This organic luminescent ink (viscosity: 28 cp) was applied to a pixel region surrounded by an insulating partition after the surface treatment with the anisole by using a flexographic printing method. This coating film was dried to form a light emitting layer having a thickness of 60 nm in the pixel region. The time from the completion of the surface treatment with the anisole to the start of printing of the organic light emitting ink was about 30 minutes.

  Here, the state of the light emitting layer formed in each pixel region was observed with an optical microscope (manufactured by Nikon Corporation, trade name “Optiphoto 88”, objective lens magnification: 50 ×). There was no trace of the organic light emitting ink repelled from the layer, and it was confirmed that the light emitting layer was formed over the entire pixel area.

(Formation of cathode)
Next, calcium was vapor-deposited with a thickness of 100 mm as a cathode on the light emitting layer, and aluminum was vapor-deposited with a thickness of 2000 mm as an oxidation protective layer. Thus, an organic EL element having a bottom emission structure was produced.

  When the organic EL device obtained as described above was caused to emit light, the emission intensity was uniform over the entire light emitting surface.

(Comparative Example 3)
An organic EL device was produced in the same manner as in Production Example 7 except that the process before the formation of the light emitting layer in the Production Example 7 was not performed (treatment with the solvent on the substrate surface on the partition wall side).

  Immediately after forming the light emitting layer, when the state of the light emitting layer formed in each pixel region was observed with an optical microscope (manufactured by Nikon Corporation, trade name “Optiphoto 88”, objective lens magnification: 50 ×), The organic light emitting ink is repelled on the surface of the partition walls and the hole injection layer, so that in the pixel region surrounded by the partition wall when viewed from one side in the thickness direction of the substrate, there are scattered defective portions where the light emitting layer is not formed. I confirmed that

  When the organic EL device obtained in this manner was allowed to emit light, uneven light emission occurred on the light emitting surface.

Claims (16)

A method for producing an organic electroluminescence device, which is provided on a substrate and configured by arranging an anode, a metal-doped molybdenum oxide layer, a light emitting layer, and a cathode in this order from the substrate side,
Preparing a substrate on which an anode is formed;
Forming a metal-doped molybdenum oxide layer;
A partition formation step of forming a partition so as to surround a pixel region in which the light emitting layer is provided when viewed from one of the thickness directions of the substrate;
A surface treatment step of treating the surface of the element precursor having the partition formed on the substrate with an organic solvent;
After the surface treatment step, a light emitting layer forming step of forming the light emitting layer by supplying ink containing an organic light emitting material to the pixel region surrounded by the partition;
Forming a cathode;
The manufacturing method of the organic electroluminescent element containing this.   The method for producing an organic electroluminescent element according to claim 1, wherein in the step of forming the metal-doped molybdenum oxide layer, the metal-doped molybdenum oxide layer is formed by simultaneously depositing molybdenum oxide and a dopant metal.   The organic electroluminescent device according to claim 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.   The organic electroluminescent device according to claim 3, wherein the dopant metal is aluminum.   The organic electroluminescent element according to any one of claims 1 to 4, wherein a ratio of a dopant metal contained in the metal-doped molybdenum oxide layer is 0.1 to 20.0 mol%.   The method for manufacturing an organic electroluminescent element according to claim 1, wherein the surface treatment step is a step of bringing an organic solvent into contact with the surface of the element precursor.   7. The method of manufacturing an organic electroluminescent element according to claim 6, wherein in the surface treatment step, an organic solvent is brought into contact with the surface of the element precursor by a spin coating method.   In the said surface treatment process, after making an organic solvent contact the surface, this organic solvent is dried, The manufacturing method of the organic electroluminescent element of Claim 6 or 7 characterized by the above-mentioned.   The method for producing an organic electroluminescence element according to claim 1, wherein the organic solvent is one or more of ink solvents.   The method for producing an organic electroluminescent element according to claim 1, wherein the organic solvent is one or more of the solvents for the organic light emitting material.   The method for producing an organic electroluminescent element according to claim 9, wherein the organic solvent is anisole.   The organic electroluminescent element according to claim 1, wherein in the light emitting layer forming step, ink containing an organic light emitting material is supplied to a pixel region surrounded by the partition wall by a printing method. Manufacturing method.   The organic electroluminescent element obtained using the manufacturing method of the organic electroluminescent element of any one of Claims 1-12.   An illuminating device comprising the organic electroluminescence element according to claim 13.   A planar light source comprising the organic electroluminescence element according to claim 13.   A display device comprising the organic electroluminescence element according to claim 13.