TW201814933A - Organic EL device, display device and method for manufacturing organic EL device - Google Patents

Abstract

An object of the present invention is to provide an organic EL device with improved lifetime. An organic EL device of the present invention comprises a substrate, a bank provided on the substrate, an anode provided in a section defined by the bank on the substrate, a functional layer provided on the anode, a compound layer having an electron injecting property which is provided on the functional layer, a metal layer provided on the compound layer having an electron injecting property, and a cathode provided on the metal layer, wherein the functional layer has a light emitting layer, and the metal layer is a layer of an alloy containing a reducing metal or a metal mixture containing a reducing metal.

Description

   Organic electroluminescence device, display element and manufacturing method of organic electroluminescence device   

The invention relates to an organic electroluminescence (EL) device, a display element, and a method for manufacturing an organic electroluminescence device.

As an organic electroluminescence device, for example, Patent Document 1 discloses a device in which a plurality of pixels are defined by a bank (partition wall). In such an organic electroluminescence device, an organic light emitting layer is provided in each pixel so that each pixel emits light. It is known that an organic electroluminescence device that is partitioned by a bank as described above can be manufactured by an inkjet printing method.

    [Prior Art Literature]         [Patent Literature]    

Patent Document 1: International Publication No. 2008/149499

However, the organic electroluminescence device as described above has a problem that the life is easily shortened.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a long-lived organic electroluminescence device, a display element including the organic electroluminescence device, and a method for manufacturing the organic electroluminescence device.

The organic electroluminescence device of the present invention includes a substrate, a bank provided on the substrate, an anode provided in a zone defined by the bank on the substrate, a functional layer provided on the anode, and a functional layer provided on the functional layer. A compound layer having an electron injectability, a metal layer provided on the compound layer having an electron injection, and a cathode provided on the metal layer, wherein the functional layer has a light emitting layer, and the metal layer is an alloy containing a reducing metal or a metal A layer of a metal mixture of reducing metals.

The compound layer having the electron injection property is preferably a fluoride containing a Group 1 metal element of the periodic table other than Li.

It is preferable that the compound layer having the electron injection property contains NaF.

The reducing metal is preferably Mg, Ca, or Ba.

It is preferable that the compound layer having the electron injection property has a thickness of 10 nm or less.

The metal layer preferably has a thickness of 10 nm or less.

A display device of the present invention includes the organic electroluminescence device.

In the method for manufacturing an organic electroluminescent device according to the present invention, the functional layer is formed by an inkjet printing method.

According to the present invention, a long-life organic electroluminescence device, a display element including the organic electroluminescence device, and a method for manufacturing the organic electroluminescence device can be provided.

1‧‧‧Organic electroluminescence device

2‧‧‧ pixels

10‧‧‧ Substrate with bank

11‧‧‧ substrate

12‧‧‧Anode

13‧‧‧ Sediment

20‧‧‧Organic Electroluminescence Structure Department

21‧‧‧Functional layer

22‧‧‧ Compound layer with electron injection

23‧‧‧metal layer

30‧‧‧ cathode

FIG. 1 is a plan view when the organic electroluminescence device according to this embodiment is viewed from the substrate side with a bank.

Fig. 2 is a partially enlarged view of a cross section taken along a line II-II in Fig. 1.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same reference numerals are assigned to the same elements. Repeated description is omitted. The dimensional ratios of the drawings are not necessarily consistent with those described.

The organic electroluminescence (organic EL) device 1 shown in FIG. 1 is an organic electroluminescence display panel having a plurality of pixels 2. Each pixel 2 is an organic electroluminescence element portion, which is formed on a partition defined by a bank on a substrate 10 with a bank. The bank 10 with a bank is formed on the substrate 11. . That is, the organic electroluminescence device 1 has a structure in which a plurality of organic electroluminescence element portions are integrally connected. In this embodiment, the “pixel” refers to a minimum unit (or a minimum area) of light emitted, and the pixel 2 has color information by emitting light from the pixel 2. In FIG. 1, the pixel 2 is schematically shown by a dotted line.

Fig. 2 is a partially enlarged view of a cross section of the substrate 10 with a bank along the line II-II in Fig. 1. As shown in FIG. 2, the organic electroluminescence device according to this embodiment includes a substrate 11, a bank 13 provided on the substrate 11, a plurality of anodes 12 provided in a zone defined by the bank 13, and An organic electroluminescence structure portion 20 on the anode 12 and a cathode (second electrode) 30. The organic electroluminescence structure section 20 includes a functional layer 21 including a light-emitting layer, a compound layer 22 having an electron injection property provided directly on the functional layer 21, and a metal layer 23 provided on the compound layer 22 having an electron injection property. The metal layer 23 is an alloy containing at least one reducing metal or a layer of a metal mixture containing at least one reducing metal. The organic electroluminescence device 1 may be a top emission type device or a bottom emission type device. In the following, if not explained, a description will be given of a case of a bottom emission type, that is, a case where light is extracted from the substrate 10 side with a bank.

The substrate 11 may be a plate-shaped transparent member having light transparency to visible light (light having a wavelength of 400 nm to 800 nm). The substrate 11 is a support that supports the anode 12 and the bank 13. Examples of the thickness of the substrate 11 are 30 μm or more and 1100 μm or less. The substrate 11 may be a rigid substrate such as a glass substrate and a silicon substrate, or a flexible substrate such as a plastic substrate or a polymer film. By using a flexible substrate, the organic electroluminescence device 1 can have flexibility.

The substrate 11 may be previously formed with a circuit for driving each pixel 2. The substrate 11 may be formed in advance with, for example, a TFT (Thin Film Transistor), a capacitor, or the like.

A plurality of anodes 12 are provided on the surface of the substrate 11 on a region corresponding to each pixel 2. Examples of the shape of the anode 12 in a plan view (the shape viewed from the thickness direction of the substrate 11) include a quadrangle such as a rectangle and a square, and other polygons. The anode 12 may be circular or oval in plan view.

As the anode 12, a thin film containing metal oxide, metal sulfide, metal, or the like can be used. Specifically, indium oxide, zinc oxide, tin oxide, indium tin oxide (ITO), and indium zinc oxide can be used. (Indium Zinc Oxide: IZO for short), thin films of gold, platinum, silver and copper. As described mainly in this embodiment, when the organic electroluminescence device 1 emits light from the substrate-attached substrate 10 side, an anode 12 that exhibits light permeability is used.

The thickness of the anode 12 can be appropriately determined in consideration of light transmittance, electrical conductivity, and the like. The thickness of the anode 12 is, for example, 10 nm to 10 μm, preferably 20 nm to 1 μm, and more preferably 50 nm to 500 nm.

In one embodiment, a layer made of an insulating layer or the like may be provided between the anode 12 and the substrate 11. A layer such as an insulating layer may be regarded as a part of the substrate 11.

As shown in FIG. 2, the bank 13 is provided around each anode 12. The bank 13 may be provided across the adjacent anodes 12. A part of the bank 13 may cover the peripheral edge portion of the anode 12. The bank 13 is a partition wall of the partitioned pixel 2 or the pixel region 2a. In other words, the bank 13 is provided on the substrate 11 in a pattern having an opening that partitions the pixel region 2 a set in advance on the surface 11 a of the substrate 11. In this embodiment, as shown in FIG. 1, since the plurality of pixels 2 are arranged in a two-dimensional array, a grid-like bank 13 is provided on the substrate 11.

An example of the material of the bank 13 is a resin. The bank 13 is, for example, a cured product of a photosensitive resin composition containing a liquid repellent. Examples of the liquid repellent include a liquid repellent containing a fluororesin. A functional layer including a light-emitting layer is formed on a partition defined by the bank 13 by a coating method as described later. Therefore, when a functional layer is generally formed by a coating method on a partition defined by the bank 13, the bank 13 is formed so as to have characteristics (for example, wettability) suitable for forming the functional layer.

The shape and arrangement of the bank 13 can be appropriately set according to the specifications of the organic electroluminescence device 1 such as the number of pixels 2 and the resolution, the ease of manufacture, and the like. For example, in FIG. 2, the side surfaces serving as the partitions defined by the bank 13 are substantially perpendicular to the surface of the substrate 11. However, the side surface may be inclined at an acute angle with respect to the surface, or may be inclined at an obtuse angle. When the side surface and the surface of the substrate 11 are at an acute angle, the shape of the bank 13 is known to be a tapered shape, and when the side surface and the surface of the substrate 11 are at an obtuse angle, the shape of the bank 13 is known to be an inverted cone shape. An example of the thickness (height) of the bank 13 is about 0.3 μm to 5 μm.

The substrate 10 with a bank described above can be manufactured, for example, by forming an anode 12 on a plurality of regions set as regions in which pixels are formed in advance on the substrate 11 and then forming a bank 13.

The anode 12 can be formed by a vapor deposition method or a coating method. Examples of the vapor deposition method include a vacuum vapor deposition method, an ion beam vapor deposition method, a sputtering method, and an ion plating method. When formed by the sputtering method, a layer including a material of the anode 12 is formed on the substrate 11. Then, the layer may be patterned into a pattern of a plurality of anodes 12. When the anode 12 is formed by a coating method, a coating liquid containing a material of the anode 12 may be applied on a substrate in a pattern corresponding to the plurality of anodes 12 to form a coating film, and then the coating film may be dried to thereby form. Alternatively, a coating film containing a material of the anode 12 may be formed on the substrate 11 and dried, and then patterned into a pattern of a plurality of anodes 12.

When the coating method is used in the formation of the anode 12, as an example of the coating method, an inkjet printing method may be mentioned. In addition, a known coating method such as a slit coating method or a micro gravure may be used. Coating method, gravure coating method, bar coating method, roll coating method, wire rod coating method, spray coating method, screen printing method, flexographic printing method, offset printing method, nozzle printing method, and the like. The solvent of the coating liquid containing the material of the anode 12 may be any solvent that can dissolve the material of the anode 12.

The bank 13 is formed by, for example, a coating method. Specifically, the coating liquid containing the material of the bank 13 may be formed by applying a coating film to the substrate 11 on which the anode 12 is formed to form a coating film and drying, and then patterning the coating film into a predetermined pattern. Examples of the coating method include a spin coating method and a slit coating method. The solvent of the coating liquid containing the bank 13 may be any solvent that can dissolve the material of the bank 13.

As shown in FIG. 2, the plurality of organic electroluminescence structure portions 20 are provided in the recessed portion formed by the bank 13 and the anode 12 in the substrate 10 with the bank. The functional layer 21 may include a hole injection layer and a hole transport layer in addition to the light emitting layer. When a hole injection layer and a hole transport layer are provided, they are laminated in this order from the anode side.

The hole injection layer is a layer having a function of improving the hole injection efficiency from the anode 12 to the light emitting layer. As the material of the hole injection layer, a known hole injection material can be used. Examples of hole injection materials include oxides such as vanadium oxide, molybdenum oxide, ruthenium oxide, and aluminum oxide; phenylamine compounds, starburst-type amine compounds, phthalocyanine compounds, amorphous carbon, and polyaniline And polythiophene derivatives such as polyethylenedioxythiophene (PEDOT).

The thickness of the hole injection layer varies depending on the material used. The optimal value can be appropriately determined in consideration of required characteristics, ease of layer formation, and the like. The thickness of the hole injection layer is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, and still more preferably 5 nm to 200 nm.

The hole injection layer is provided with different materials or thicknesses according to the type of each pixel 2, that is, each of the red pixel, the green pixel, and the blue pixel. From the viewpoint of the simplicity of the formation process of the hole injection layer, all the hole injection layers can be formed with the same material and the same thickness.

The hole transport layer is a layer having a function of improving the injection of holes from the anode 12, the hole injection layer, or the hole transport layer closer to the anode 12, into the light emitting layer. As the material of the hole transport layer, a well-known hole transport material can be used. Examples of the material of the hole transport layer include polyvinyl carbazole or a derivative thereof, polysilane or a derivative thereof, and a polysiloxane having an aromatic amine in a side chain or a main chain. Or its derivative, pyrazoline or its derivative, arylamine or its derivative, stilbene or its derivative, triphenyldiamine or its derivative, polyaniline or its derivative, polythiophene or its derivative , Polyarylamine or a derivative thereof, polypyrrole or a derivative thereof, poly (p-phenylene vinylene) or a derivative thereof, or poly (2,5-thienyl vinylene) or a derivative thereof, and the like. In addition, hole-transporting materials disclosed in Japanese Patent Application Publication No. 2012-144722 can be cited.

The thickness of the hole transport layer varies depending on the material used. The optimum value can be appropriately set so that the driving voltage and the light emission efficiency reach appropriate values. The thickness of the hole transport layer is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, and still more preferably 5 nm to 200 nm.

The hole transmission layer is provided with different materials or thicknesses according to the type of each pixel 2, that is, each red pixel, green pixel, and blue pixel. From the viewpoint of simplicity of the formation process of the hole transport layer, all hole injection layers can be formed with the same material and the same thickness.

The light emitting layer may be disposed on the hole transport layer. The light emitting layer is a layer having a function of emitting light of a predetermined wavelength. The light-emitting layer is usually formed of an organic substance that mainly emits fluorescence and / or phosphorescence, or is formed of a light-emitting material such as the organic substance and a dopant that assists the organic substance. The dopant is added for the purpose of, for example, improving the light emission efficiency or changing the light emission wavelength. The organic substance contained in the light-emitting layer may be a low-molecular compound or a high-molecular compound. Examples of the light-emitting material constituting the light-emitting layer include materials that mainly emit fluorescent and / or phosphorescent organic materials such as pigment-based materials, metal complex-based materials, and polymer-based materials, and materials of dopants.

Examples of the pigment-based material include cyclopentamine benzoate or a derivative thereof, tetraphenylbutadiene or a derivative thereof, triphenylamine or a derivative thereof, and oxadiazole or a derivative thereof. , Pyrazoloquinoline or its derivative, distyrylbenzene or its derivative, distyrylarylene or its derivative, pyrrole or its derivative, thiophene ring compound, pyridine ring compound, fluorenone or its Derivatives, hydrazone or its derivatives, oligothiophenes or its derivatives, oxadiazole dimers or its derivatives, pyrazoline dimers or its derivatives, quinacridone or its derivatives, couma Or its derivatives.

Examples of the metal complex-based material include rare earth metals such as Tb, Eu, and Dy, or Al, Zn, Be, Pt, Ir, etc. as the central metal, and oxadiazole, thiadiazole, and phenyl. Metal complexes such as pyridine, phenylbenzimidazole, and quinoline structures as ligands. Examples of the metal complex include a metal complex having light emission from a triplet excited state such as an iridium complex, a platinum complex, a hydroxyquinoline aluminum complex, a benzohydroxyquinoline beryllium complex, Benzoxazole zinc complex, benzothiazole zinc complex, azomethyl zinc complex, zinc porphyrin complex, phenanthroline hydrazone complex, and the like.

Examples of the polymer material include polyparaphenylene vinylene or its derivative, polythiophene or its derivative, polyparaphenylene or its derivative, polysilane or its derivative, polyacetylene, or Derivatives thereof, polyfluorene or its derivatives, polyvinylcarbazole or its derivatives; materials obtained by polymerizing the pigment-based materials and metal complex-based materials, and the like.

Among the above-mentioned light-emitting materials, as a material that emits red light (hereinafter referred to as a "red light-emitting material"), coumarin or a derivative thereof, a thiophene ring compound, a polymer thereof, and polyparaphenylene phenylene Vinyl or its derivative, polythiophene or its derivative, polyfluorene or its derivative, and the like. Among them, polyparaphenylene vinylene or a derivative thereof, polythiophene or a derivative thereof, and polyfluorene or a derivative thereof are preferably polymer materials. Examples of the red light-emitting material include those disclosed in Japanese Patent Application Laid-Open No. 2011-105701.

Examples of green-emitting materials (hereinafter referred to as "green emitting materials") include quinacridone or a derivative thereof, coumarin or a derivative thereof, polymers thereof, and polyparaphenylene terephthalate. Vinyl or its derivative, polyfluorene or its derivative, and the like. Among them, polyparaphenylene vinylene or a derivative thereof, and polyfluorene or a derivative thereof are preferably polymer materials. Examples of the green light-emitting material include those disclosed in Japanese Patent Application Laid-Open No. 2012-036388.

Examples of the material that emits blue light (hereinafter referred to as "blue light-emitting material") include distyryl arylidene or a derivative thereof, oxadiazole or a derivative thereof, a polymer thereof, and polyethylene Carbazole or a derivative thereof, polyparaphenylene or a derivative thereof, polyfluorene or a derivative thereof, and the like. Among them, polyvinyl carbazole or a derivative thereof, polyparaphenylene or a derivative thereof, and polyfluorene or a derivative thereof are preferable as a polymer material. Examples of the blue light-emitting material include those disclosed in Japanese Patent Application Laid-Open No. 2012-144722.

Examples of the material of the dopant include osmium or a derivative thereof, coumarin or a derivative thereof, rubrene or a derivative thereof, quinacridone or a derivative thereof, squalium or Derivatives thereof, porphyrins or derivatives thereof, styryl pigments, fused tetrabenzenes or derivatives thereof, pyrazolones or derivatives thereof, decacyclene or derivatives thereof, phenoxazone or derivatives thereof Things.

On the functional layer 21, a compound layer 22 having an electron injection property is provided so as to be in direct contact with the functional layer 21. The compound layer 22 having an electron injection property is a layer containing a compound having an electron injection property, and has a function of improving the electron injection efficiency from the cathode 30. The compound having an electron injecting property can be appropriately selected depending on the type of the light emitting layer. Examples of the compound having electron-injecting properties include oxides, halides, carbonates of alkali metals or alkaline earth metals, or mixtures of these compounds. Examples of the oxides, halides, and carbonates of alkali metals include lithium oxide, lithium fluoride, sodium oxide, sodium fluoride, potassium oxide, potassium fluoride, rubidium oxide, rubidium fluoride, cesium oxide, and fluorine. Cesium, lithium carbonate, etc. Examples of oxides, halides, and carbonates of alkaline earth metals include magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride, barium oxide, barium fluoride, strontium oxide, strontium fluoride, and magnesium carbonate. Wait. At this time, the compound layer 22 having electron injection properties is in contact with the bank.

From the viewpoint of further extending the life of the organic electroluminescent device, the material constituting the compound layer 22 having an electron injecting property is preferably a fluoride containing a metal element of Group 1 of the periodic table other than Li, and more preferably Contains NaF. In addition, from the viewpoint of further extending the life of the organic electroluminescence device, the compound layer 22 having an electron injecting property preferably has a thickness of 10 nm or less, and more preferably has a thickness of 2 to 6 nm.

A metal layer 23 is provided on the compound layer 22 having electron injection properties, and the metal layer 23 is a layer containing an alloy of a reducing metal or a metal mixture containing a reducing metal (the metal mixture does not include an alloy). Here, an alloy containing a reducing metal or a metal mixture containing a reducing metal means one containing only two or more metals. The reducing metal-containing alloy or the reducing metal-containing metal mixture may include one or more metals other than the reducing metal and the reducing metal, or may include only two or more reducing metals. The reducing metal is a metal capable of reducing the compound injection layer 22 having electron injection properties. Examples of the reducing metal include Li, Na, K, Rb, Mg, Ca, Sr, Ba, and Al. Among them, Mg, Ca, or Ba is preferred, and Ba is more preferred. The metal other than the reducing metal contained in the alloy or the metal mixture is not particularly limited as long as it has conductivity, and examples thereof include Ag and the like. The content of the reducing metal in the metal layer 23 is preferably 1 at% or more and 100 at% or less with respect to 100 at% of the metal contained in the metal layer 23. When the content of the reducing metal falls within the above range, the life of the organic electroluminescence device can be extended. When the reducing metal includes at least one metal selected from the group consisting of Mg, Ca, and Ba, the content of the metal is preferably 0.5 at% relative to 100 at% of the metal contained in the metal layer 23. Above and below 40at%. When the content of the metal is within the above range, the life of the organic electroluminescence device can be extended. Here, the content of each metal included in the metal layer can be measured by dissolving a test piece obtained by making a metal layer on a raw glass in aqua regia and using an inductively coupled plasma emission analysis method. The metal layer 23 is preferably provided directly on the compound layer 22 having electron injection properties. However, when a layer composed of only one type of reducing metal is formed on a compound layer having electron injection properties, the reducing metal is easily deteriorated by water, oxygen, or the like. On the other hand, in the present embodiment, since the metal layer 23 is a layer containing an alloy of a reducing metal or a metal mixture containing a reducing metal, it contains two or more kinds of reducing metals or metals other than reducing metals. At this time, at least a part of the one reducing metal is easily covered with another metal (a reducing metal other than the one reducing metal, or a metal other than the reducing metal), and the one reducing property is easily suppressed. The metal is excessively exposed on the surface and deteriorates due to water, oxygen, and the like.

From the viewpoint of being able to further extend the life of the organic electroluminescence device, the thickness of the metal layer 23 is preferably 10 nm or less, and more preferably 1 to 6 nm.

A cathode 30 is provided on the metal layer 23. The material of the cathode 30 is preferably a material having a small work function, which is easy to inject electrons into the metal layer 23, and has a high electrical conductivity. In addition, as explained in this embodiment, when the organic electroluminescence device 1 extracts light from the anode 12 side, in order to reflect the light emitted from the light-emitting layer to the anode 12 side by the cathode 30, the material of the cathode 30 is preferably visible light. Highly reflective material. The cathode 30 can use a transition metal, a Group 13 metal of the periodic table, or the like. As the cathode 30, a transparent conductive cathode containing a conductive metal oxide, a conductive organic substance, or the like can be used.

The thickness of the cathode 30 can be appropriately set in consideration of electrical conductivity and durability. The thickness of the cathode 30 is, for example, 10 nm to 10 μm, preferably 20 nm to 1 μm, and more preferably 50 nm to 500 nm.

In this embodiment, the cathode 30 is formed on the entire surface of the display area where the plurality of pixels 2 are provided. That is, the cathode 30 is formed not only on the light emitting layer but also on the bank 13 as the cathode 30 shared by the plurality of pixels 2.

Although the illustration is omitted in FIGS. 1 and 2, a sealing substrate is usually provided on the cathode 30 of the organic electroluminescence device 1. In addition, the organic electroluminescence device 1 may have a known structure included in, for example, an organic electroluminescence panel display panel.

In the organic electroluminescence device 1 configured as described above, the structure in each pixel 2, that is, the portion of the pixel region in the anode 12, the organic electroluminescence structure portion 20, and the cathode 30 constitutes an organic electroluminescence element portion. Therefore, the organic electroluminescence device 1 has a plurality of organic electroluminescence element sections separated by a bank 13, and the organic electroluminescence element sections are integrally connected to each other so as to share the substrate 11 and the anode 12.

Next, a method for manufacturing the organic electroluminescence device 1 will be described. Here, a method for manufacturing the organic electroluminescence device 1 after preparing the substrate 10 with a bank will be described. A method of manufacturing the organic electroluminescence device 1 includes sequentially forming a functional layer 21 including a light-emitting layer in a zone defined by a bank of a substrate 10 with a bank, a compound layer 22 having an electron injection property, and a metal layer. 23 and cathode 30 steps. Hereinafter, a method for manufacturing an organic electroluminescence device 1 including a hole injection layer, a hole transport layer, and a light emitting layer as the functional layer 21 in this order will be described.

Specifically, when a hole injection layer is formed, a coating liquid containing a hole injection material is dropped on the anode 12 in a recessed portion surrounded by a bank and the anode to form a coating film, and then the coating film is dried. This forms a hole injection layer.

Examples of the coating method include an inkjet printing method. However, as long as it is a coating method capable of forming a layer in the recessed portion, other known coating methods such as a micro gravure coating method, a gravure coating method, a bar coating method, a roll coating method, and a wire rod coating method may be used. Method, spraying method, screen printing method, flexographic printing method, offset printing method, and nozzle printing method, and screen printing method, flexographic printing method, offset printing method, and nozzle printing method are preferably used.

The solvent used in the coating liquid is not limited as long as it can dissolve the hole injection material, and examples thereof include chloride solvents such as chloroform, methylene chloride, and dichloroethane; ether solvents such as tetrahydrofuran; and aromatic solvents such as toluene and xylene. Hydrocarbon solvents; ketone solvents such as acetone, methyl ethyl ketone; ester solvents such as ethyl acetate, butyl acetate, ethyl cellosolve acetate; cyclohexylbenzene, decylbenzene, dodecylbenzene, diethylbenzene, Amylbenzene, dipentylbenzene, tetrahydronaphthalene, cumene, cumene, decahydronaphthalene, diethylbenzene, trimethylbenzene, trimethylbenzene, tetramethylbenzene, butylbenzene, A solvent and the like having a benzene ring containing at least one or more substituents, such as 4-methylanisole. In addition, in order to dissolve the hole injection material well, a polar solvent may be contained. As the polar solvent, a conventional solvent is used without particular limitation, and examples thereof include alcohols, ketones, glycol esters, glycol ethers, N, N-dimethylformamide, and N, N-diamine. Methylacetamide, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidone and dimethylsulfinyl, N-cyclohexyl-2-pyrrolidone, and the like.

The method for drying the coating film is not limited as long as the coating film can be dried, and examples include vacuum drying and heat drying.

Next, when the hole transport layer is formed, a coating liquid containing a hole transport material is dropped onto the hole injection layer in the recess to form a coating film, and the coating film is dried to form a hole transport. Floor. Examples of the solvent and the drying method may be the same as in the case of the hole injection layer.

Next, a light emitting layer is formed on the hole transport layer. The light emitting layer is formed by a coating method. Specifically, a coating liquid containing a light-emitting material to be formed into a light-emitting layer is dropped into the recess to form a coating film, and then the coating film is dried to form a light-emitting layer.

As the coating method, an inkjet printing method may be exemplified, or other known coating methods exemplified in the case of a hole injection layer may be used. The solvent used in the coating liquid is not limited as long as it can dissolve the light-emitting material, and may be the same as the solvent exemplified when the hole injection layer is formed. The method for drying the coating film is the same as in the case of the hole injection layer, and is not limited as long as the coating film can be dried, and examples include vacuum drying and heat drying.

Next, a compound layer 22 having an electron injection property is formed on the light emitting layer. Examples of the method for forming the compound layer 22 having an electron injection property include an inkjet printing method and a vapor deposition method, and other known coating methods exemplified in the case of a hole injection layer may be used. Examples of the vapor deposition method include a vacuum vapor deposition method, an ion beam vapor deposition method, a sputtering method, and an ion plating method. In the case of the inkjet printing method, a coating liquid containing an electron-injecting material that should form the compound layer 22 having electron-injecting properties is dropped into the recessed portion to form a coating film, and then the coating film is dried. A compound layer 22 having electron injection properties is formed. The solvent used in the coating liquid is not limited as long as it can dissolve the electron injection material, and may be the same as the solvent exemplified when the hole injection layer is formed. The method for drying the coating film is the same as in the case of the hole injection layer, and is not limited as long as the coating film can be dried, and examples include vacuum drying and heat drying.

Next, a metal layer 23 is formed on the compound layer 22 having an electron injection property. The method for forming the metal layer 23 can be formed by a vapor deposition method or a coating method. Examples of the vapor deposition method include a vacuum vapor deposition method, an ion beam vapor deposition method, a sputtering method, and an ion plating method. The alloy of the reducing metal layer or the metal mixture of the reducing metal layer may be formed using a raw material containing two or more metals, or a plurality of raw materials containing one metal may be prepared and formed using a plurality of raw materials. When a plurality of raw materials are used to form a metal layer, a plurality of raw materials are co-evaporated by a vacuum evaporation method, whereby a metal layer can also be formed. At this time, for example, when Mg, Ca, or Ba is used and a metal other than Mg, Ca, or Ba is used as a raw material, the vapor deposition rate of Mg, Ca, or Ba is larger than the vapor deposition rate of a metal other than Mg, Ca, or Ba. More preferably, it is 0.04 to 1.0, more preferably 0.04 to 0.5, and even more preferably 0.05 to 0.5.

Next, a cathode is formed on the metal layer. The method for forming the cathode 30 can be formed by a vapor deposition method or a coating method. When forming by a vapor deposition method, a vacuum vapor deposition method, an ion beam vapor deposition method, a sputtering method, an ion plating method, etc. are mentioned.

The organic electroluminescence device 1 obtained as described above can be sealed by a sealing member. At this time, the sealing member is arranged so as to cover the organic electroluminescence device. The material of the sealing member is not particularly limited, and for example, glass, a metal selected from aluminum, copper, and iron, or an alloy containing at least one of these metals can be used.

The organic electroluminescence device of this embodiment can be applied to display elements such as organic electroluminescence displays and organic electroluminescence lighting.

As mentioned above, although various embodiment of this invention was described, it is not limited to the various embodiment illustrated, and it is intended that the scope of a patent application, and all the changes within the meaning and range equivalent to the scope of patent application are included.

For example, the configuration of the organic electroluminescence device is not limited to the configurations illustrated in FIGS. 1 and 2.

The organic electroluminescence device only needs to have a metal layer 23 between the compound layer 22 having an electron injection property and the cathode 30, and the metal layer 23 is an alloy containing at least one reducing metal or an alloy containing at least one reducing metal. Layer of metal mixture. An example of a layer configuration that can be taken by an organic electroluminescence element is exemplified. In addition, the following description may include the configuration of the first embodiment and the second embodiment.

a) Anode / hole injection layer / light emitting layer / compound layer with electron injection property / metal layer / cathode

b) Anode / hole injection layer / hole transport layer / light emitting layer / compound layer with electron injection property / metal layer / cathode

c) Anode / Light-emitting layer / Compound layer with electron injection property / Metal layer / Cathode

Furthermore, in a) and b), when the hole injection layer and / or the hole transport layer have a function of blocking electron transmission, these layers may be referred to as an electron blocking layer. The electron blocking layer has a function of blocking electron transmission. For example, the effect of blocking the electron transmission can be confirmed by making an organic electroluminescence element that only flows an electron current, and measuring a decrease in the current value. In addition, instead of being provided between the hole injection layer and / or the hole transport layer, an electron blocking layer may be provided between the anode and the light emitting layer.

Furthermore, the organic electroluminescence element may have a single light emitting layer, or may have two or more light emitting layers. In any of the above-mentioned layers a) to c), when the laminated body arranged between the anode and the cathode is referred to as "structural unit A", it is used as an The structure includes a layer structure shown in the following d). In addition, the two (structure unit A) layer structures may be the same or different from each other.

d) Anode / (structural unit A) / charge generation layer / (structural unit A) / cathode

Here, the charge generating layer refers to a layer that generates holes and electrons by applying an electric field. Examples of the charge generation layer include a thin film containing vanadium oxide, indium tin oxide (ITO), molybdenum oxide, and the like.

When “(structural unit A) / charge generating layer” is referred to as “structural unit B”, as a configuration of an organic electroluminescent device having three or more light emitting layers, a layer configuration shown in e) below can be cited.

e) anode / (structural unit B) x / (structural unit A) / cathode

The symbol "x" represents an integer of 2 or more, and "(structural unit B) x" represents a laminated body obtained by stacking (structural unit B) x segments. In addition, the layer structure having a plurality of (structural units B) may be the same or different.

The organic electroluminescence element may be formed by directly stacking a plurality of light emitting layers without providing a charge generating layer.

In the description so far, the example in which the anode is disposed on the substrate side has been described, but the cathode may be disposed on the substrate side. At this time, for example, when fabricating each of the organic electroluminescent elements a) to e) on the substrate, each layer may be sequentially laminated on the substrate from the cathode (the right side of each structure a) to e)).

    [Example]    

Hereinafter, the present invention will be described in more detail based on examples and comparative examples. However, the present invention is not limited to the following examples.

    [Example 1]    

As Example 1, as shown in FIG. 1, an anode, a hole injection layer, a hole transport layer, a light emitting layer, a compound layer having an electron injection property, and an alloy containing a reducing metal were sequentially laminated on a substrate. Or a metal layer including a layer of a metal mixture of a reducing metal (the metal mixture does not include an alloy), and an organic electroluminescence element of a cathode. The organic electroluminescence element of Example 1 is referred to as an organic electroluminescence element Al. Hereinafter, a method for producing the organic electroluminescent element Al will be specifically described.

    <Substrate and anode>    

A glass substrate was prepared as a substrate of the organic electroluminescence element Al. An ITO film is formed on the glass substrate in a predetermined pattern as an anode. The ITO thin film is formed by a sputtering method, and its film thickness is 45 nm.

On such a substrate, a grid-like bank is formed by a photolithography method using a photosensitive resin. The thickness of the bank is 1.0 μm, and the opening portion has a forward tapered shape (the angle formed by the side surface of the partition wall and the substrate is an acute angle). The shape of the opening is an approximately elliptical shape. As shown in FIG. 1, the width in the first axial direction X is 50 μm, and the width in the second axial direction Y is 200 μm.

    <Hole injection layer>    

The hole injection material was applied to the pixels partitioned by the banks on the ITO film by an inkjet printing method, thereby forming a coating film having a thickness of 65 nm. Hereinafter, the hole injection material used in Example 1 is referred to as a hole injection material α1. In a vacuum drying chamber to which a dry pump is connected, a substrate is placed on a temperature controller adjusted to 10 ° C, and the pressure is reduced to about 10 Pa to dry the coating liquid. Further, the temperature of the temperature control table was adjusted to 230 ° C., and firing was performed under atmospheric pressure for 15 minutes to form a hole injection layer.

    <Hole transport layer>    

The coating solution in which the hole transporting material α2 was dissolved was applied to the hole injection layer by an inkjet method, and the substrate was placed in a vacuum drying chamber connected to a dry pump in a temperature-controlled table adjusted to 10 ° C. The coating liquid was dried by pressing to about 5 Pa to obtain a coating film having a film thickness of 20 nm. The glass substrate provided with the coating film was heated at 190 ° C. for 60 minutes under a nitrogen environment (inert environment) to evaporate the solvent, and then naturally cooled to room temperature to obtain a hole transport layer.

    <Luminescent layer>    

A coating solution in which a polymer-based material (a material that mainly emits fluorescent and / or phosphorescent organic substances) α3 is dissolved is applied to a hole transport layer by an inkjet printing method, and a vacuum drying chamber connected to a dry pump The substrate was placed on a temperature control platform adjusted to 10 ° C., and the pressure was reduced to about 20 Pa to dry the coating solution to obtain a coating film having a thickness of 65 nm. The glass substrate provided with the coating film was heated at 180 ° C. for 10 minutes under a nitrogen environment (inert environment) to evaporate the solvent, and then naturally cooled to room temperature to obtain a light-emitting layer.

    <Compound layer having electron injection property>    

The glass substrate on which the light emitting layer is formed is transferred to a vapor deposition chamber, and a compound layer having an electron injecting property is formed on the light emitting layer. Specifically, the degree of vacuum exhausted into the evaporation chamber was 1.0 × 10 ^-5 Pa or less, and a sodium fluoride (NaF) layer having a thickness of 3 nm was formed on the light-emitting layer by a vacuum evaporation method.

    <Metal layer>    

After forming a compound layer having an electron injection property, a metal layer is formed on the compound layer having an electron injection property in the same vapor deposition chamber. Specifically, Ba and Al were co-evaporated on a compound layer having electron injection properties by a vacuum deposition method to form a metal layer having a film thickness of 1.7 nm and a mixture of Ba and Al. The evaporation rates of Ba and Al are: 0.3 Å / s for Ba and 0.7 Å / s for Al.

    <Cathode>    

After the metal layer is formed, a cathode is formed in the same evaporation chamber. Specifically, Al was deposited on the reducing metal layer by a vacuum deposition method to form a cathode having a film thickness of 100 nm.

    <Sealing member>    

After forming the cathode, the obtained organic electroluminescence element A1 was sealed with glass under a nitrogen environment (inert environment).

    [Example 2]    

The organic electroluminescence element of Example 2 is referred to as an organic electroluminescence element A2. An organic electroluminescence element A2 was manufactured in the same manner as in Example 1 except that the metal layer was formed in the following method.

    <Metal layer>    

After forming a compound layer having an electron injection property, a metal layer is formed on the compound layer having an electron injection property in the same vapor deposition chamber. Specifically, Ba and Al are co-deposited on a compound layer having electron injection properties by a vacuum evaporation method to form a metal layer having a film thickness of 1.7 nm and a mixture of Ba and Al. The evaporation rates of Ba and Al are: 0.1 Å / s for Ba and 0.9 Å / s for Al.

    [Example 3]    

The organic electroluminescence element of Example 3 is referred to as an organic electroluminescence element A3. An organic electroluminescence element A3 was manufactured in the same manner as in Example 1 except that the metal layer was formed in the following method.

    <Metal layer>    

After forming a compound layer having an electron injection property, a metal layer is formed on the compound layer having an electron injection property in the same vapor deposition chamber. Specifically, Ba and Al are co-deposited on a compound layer having electron injection properties by a vacuum evaporation method to form a metal layer having a film thickness of 1.7 nm and a mixture of Ba and Al. The evaporation rates of Ba and Al were: 0.04Å / s for Ba and 0.96Å / s for Al.

    [Example 4]    

The organic electroluminescence element of Example 4 is referred to as an organic electroluminescence element A4. An organic electroluminescence element A4 was manufactured in the same manner as in Example 1 except that a compound layer having electron injection properties was formed in the following method.

    <Compound layer having electron injection property>    

The glass substrate on which the light emitting layer is formed is transferred to a vapor deposition chamber, and a compound layer having an electron injecting property is formed on the light emitting layer. Specifically, the degree of vacuum exhausted into the evaporation chamber was 1.0 × 10 ^-5 Pa or less, and a 4 nm-thick sodium fluoride (NaF) layer was formed on the light-emitting layer by a vacuum evaporation method.

    [Example 5]    

The organic electroluminescence element of Example 5 is referred to as an organic electroluminescence element A5. An organic electroluminescent element A5 was manufactured in the same manner as in Example 1 except that the metal layer was formed in the following method.

    <Metal layer>    

After forming a compound layer having an electron injection property, a metal layer is formed on the compound layer having an electron injection property in the same vapor deposition chamber. Specifically, Ba and Ag are co-evaporated on a compound layer having electron injection properties by a vacuum evaporation method to form a metal layer having a film thickness of 1.7 nm and a mixture of Ba and Ag. The evaporation rates of Ba and Ag are: Ba is 0.29 Å / s, and Ag is 0.71 Å / s.

    [Example 6]    

The organic electroluminescence element of Example 6 is referred to as an organic electroluminescence element A6. An organic electroluminescent element A6 was manufactured in the same manner as in Example 1 except that the metal layer was formed in the following method.

    <Metal layer>    

After forming a compound layer having an electron injection property, a metal layer is formed on the compound layer having an electron injection property in the same vapor deposition chamber. Specifically, a metal layer having a film thickness of 3.9 nm and a mixture of Mg and Al was formed on the compound layer having electron injection properties by co-depositing Mg and Al by a vacuum evaporation method. The evaporation rates of Mg and Al are: Mg is 0.13 Å / s and Al is 0.87 Å / s.

    [Example 7]    

The organic electroluminescence element of Example 7 is referred to as an organic electroluminescence element A7. An organic electroluminescent element A7 was manufactured in the same manner as in Example 1 except that the cathode was formed in the following method.

    <Cathode>    

After the metal layer is formed, a cathode is formed in the same evaporation chamber. Specifically, Ag was deposited on the metal layer by a vacuum deposition method to form a cathode having a film thickness of 100 nm.

    [Example 8]    

The organic electroluminescence element of Example 8 is referred to as an organic electroluminescence element A8. An organic electroluminescent element A8 was manufactured in the same manner as in Example 1 except that the metal layer was formed in the following method.

    <Metal layer>    

After forming a compound layer having an electron injection property, a metal layer is formed on the compound layer having an electron injection property in the same vapor deposition chamber. Specifically, a metal layer having a film thickness of 3.9 nm and a mixture of Mg, Al, and Ag was formed on the compound layer having electron injection properties by co-depositing Mg, Al, and Ag by a vacuum deposition method. The evaporation rates of Mg, Al and Ag are: Mg is 0.13 Å / s, Al is 0.44 Å / s, and Ag is 0.43 Å / s.

    [Example 9]    

The organic electroluminescence element of Example 9 is referred to as an organic electroluminescence element A9. An organic electroluminescent element A9 was manufactured in the same manner as in Example 1 except that the metal layer was formed in the following method.

    <Metal layer>    

After forming a compound layer having an electron injection property, a metal layer is formed on the compound layer having an electron injection property in the same vapor deposition chamber. Specifically, Mg and Ag are co-evaporated on a compound layer having electron injection properties by a vacuum evaporation method to form a metal layer having a film thickness of 3.9 nm and a mixture of Mg and Ag. The evaporation rates of Mg and Ag are: Mg is 0.13 Å / s, and Ag is 0.87 Å / s.

    [Comparative Example 1]    

The organic electroluminescence element of Comparative Example 1 is referred to as an organic electroluminescence element B1. An organic electroluminescent element B1 was manufactured in the same manner as in Example 1 except that a metal layer was not formed.

    [Comparative Example 2]    

The organic electroluminescence element of Comparative Example 2 is referred to as an organic electroluminescence element B2. An organic electroluminescent element B2 was manufactured in the same manner as in Example 1 except that the metal layer was formed in the following method.

    <Metal layer>    

After forming a compound layer having an electron injection property, a metal layer is formed on the compound layer having an electron injection property in the same vapor deposition chamber. Specifically, Ba was vapor-deposited on a compound layer having an electron injection property by a vacuum deposition method to form a metal layer having a film thickness of 1 nm. The evaporation rate of Ba is 0.3 Å / s.

    [Comparative Example 3]    

The organic electroluminescence element of Comparative Example 3 is referred to as an organic electroluminescence element B3. An organic electroluminescence element B3 was manufactured in the same manner as in Example 1 except that the metal layer was formed in the following method.

    <Metal layer>    

After forming a compound layer having an electron injection property, a metal layer is formed on the compound layer having an electron injection property in the same vapor deposition chamber. Specifically, Ba was vapor-deposited on a compound layer having an electron injection property by a vacuum deposition method to form a metal layer having a film thickness of 2 nm. The evaporation rate of Ba is 0.3 Å / s.

    [Comparative Example 4]    

The organic electroluminescence element of Comparative Example 4 is referred to as an organic electroluminescence element B4. An organic electroluminescent element B4 was manufactured in the same manner as in Example 1 except that the metal layer was formed in the following method.

    <Metal layer>    

After forming a compound layer having an electron injection property, a metal layer is formed on the compound layer having an electron injection property in the same vapor deposition chamber. Specifically, Mg was vapor-deposited on a compound layer having an electron injection property by a vacuum vapor deposition method to form a metal layer having a film thickness of 1 nm. The deposition rate of Mg is 0.3 Å / s.

    [Comparative Example 5]    

The organic electroluminescence element of Comparative Example 5 is referred to as an organic electroluminescence element B5. An organic electroluminescent element B5 was manufactured in the same manner as in Example 1 except that the metal layer was formed in the following method.

    <Metal layer>    

After forming a compound layer having an electron injection property, a metal layer is formed on the compound layer having an electron injection property in the same vapor deposition chamber. Specifically, a metal layer having a film thickness of 3 nm was formed on a compound layer having an electron injecting property by depositing Mg by a vacuum vapor deposition method. The deposition rate of Mg is 0.3 Å / s.

    <Component life>    

Each of the organic electroluminescence devices manufactured in Examples 1 to 8 and Comparative Examples 1 to 5 was driven, and the device lifetime was measured. The results obtained are shown in Table 1.

In addition, when the luminance at the start of driving is 100, the element lifetime is evaluated by such an index as LT95, which is the time from the start of driving until the luminance decreases to 95. The element lifetime was measured by driving the organic electroluminescent element A1 at an initial brightness of 8000 cd / cm ² .

Claims (8)

    An organic electroluminescence device includes a substrate, a bank provided on the substrate, an anode provided in a zone defined by the bank on the substrate, a functional layer provided on the anode, and a The functional layer includes a compound layer having an electron injection property, a metal layer provided on the compound layer having an electron injection property, and a cathode provided on the metal layer, wherein the functional layer includes a light emitting layer and the metal layer. It is a layer containing an alloy of a reducing metal or a metal mixture containing a reducing metal.         The organic electroluminescence device according to item 1 of the scope of patent application, wherein the compound layer having an electron injecting property contains a fluoride of a Group 1 metal element of the periodic table other than Li.         The organic electroluminescence device according to claim 1 or 2, wherein the compound layer having electron injection properties includes NaF.         The organic electroluminescence device according to any one of claims 1 to 3, wherein the reducing metal is Mg, Ca, or Ba.         The organic electroluminescence device according to any one of claims 1 to 4, wherein the compound layer having electron injection properties has a thickness of 10 nm or less.         The organic electroluminescence device according to any one of claims 1 to 5, wherein the metal layer has a thickness of 10 nm or less.         A display element includes the organic electroluminescence device according to any one of claims 1 to 6.         A method for manufacturing an organic electroluminescence device, which is a method for manufacturing the organic electroluminescence device according to any one of claims 1 to 6, and forms the aforementioned functional layer by an inkjet printing method.