JP2008251292A - Organic EL light emitting device - Google Patents

Abstract

An organic EL light emitting device capable of effectively preventing peeling between an organic EL layer and an electrode without limiting the material constituting the organic EL layer.
SOLUTION: A substrate 12, an organic EL element 20 in which a first electrode 14, an organic EL layer 16, and a second electrode 18 are sequentially stacked on the substrate, and sealing for sealing the organic EL element. An organic EL light emitting device including a member 28, wherein a low adhesion layer 22 is provided between the second electrode and the sealing member, and at least on one surface of the low adhesion layer, the low adhesion layer 22 is provided. An organic EL light emitting device according to claim 10, wherein the adhesion between the adhesion layer and the layer in contact with the adhesion layer is smaller than the adhesion between the organic EL layer and the first electrode and the second electrode.
[Selection] Figure 2

Description

  The present invention relates to an organic EL light emitting device including an organic electroluminescence (organic EL) element.

  In recent years, light-emitting devices using organic EL elements have been developed. FIG. 7 schematically shows the configuration of the organic EL element 1. An anode 3, an organic EL layer 8 (a hole transport layer 4, a light emitting layer 5, and an electron transport layer 6), a cathode 7, and the like are formed on a substrate 2 such as glass or plastic. In addition, since the organic EL element 1 is easily deteriorated by moisture or oxygen, it is sealed with a sealing member (not shown). As the sealing member, in addition to a sealing can (sealing cap) formed of glass, metal, or the like, a sealing film made of an inorganic film or a plastic sealing film having a barrier layer is used (Patent Literature). 1).

  The organic EL element 1 having such a configuration is connected to an external wiring via a lead wiring (terminal) 9 and an electric field is applied to both the electrodes 3 and 7, so that the region sandwiched between the electrodes 3 and 7 is The light emitting layer 5 is excited to emit light. However, for example, when peeling occurs between the electrodes 3 and 7 and the organic EL layer 8, light cannot be emitted.

  In order to prevent peeling between the electrode and the organic EL layer, it has been proposed to provide an organic layer of a low molecular material between an organic layer formed of a polymer material and a cathode (see Patent Document 2). When an organic EL layer is formed using a polymer material, peeling between the organic EL layer and the cathode is likely to occur, but the adhesion of the cathode can be improved by interposing the organic layer formed of a low molecular material as described above. It is taught to improve.

JP 2005-339863 A JP 2002-33195 A

  As described above, when a low molecular weight organic layer is formed between the high molecular weight organic layer and the cathode, there is a problem that the material constituting the organic EL layer is limited. Further, even if the material of the organic EL layer is limited to improve the adhesion between the cathode and the organic EL layer, especially when a flexible substrate such as a plastic film is used, it is greatly bent or repeatedly bent. Again, peeling is likely to occur between the organic EL layer and the electrode.

  An object of this invention is to provide the organic electroluminescent light-emitting device which can prevent effectively peeling between an organic electroluminescent layer and an electrode, without limiting the material which comprises an organic electroluminescent layer.

  In order to achieve the above object, the present invention provides the following organic EL light emitting device.

<1> a substrate;
An organic EL element in which at least a first electrode, an organic EL layer, and a second electrode are sequentially laminated on the substrate;
An organic EL light emitting device including a sealing member for sealing the organic EL element,
A low adhesion layer is provided between the second electrode and the sealing member, and at least one surface of the low adhesion layer has an adhesion force between the layer in contact with the low adhesion layer and the organic An organic EL light emitting device characterized by being smaller than the adhesion between the EL layer and the first electrode and the second electrode.

<2> The organic EL light-emitting device according to <1>, wherein the substrate is flexible.

<3> The organic EL light-emitting device according to <1> or <2>, wherein an inorganic sealing film is provided as a layer in contact with the low adhesion layer.

<4> The organic EL light-emitting device according to <3>, wherein the inorganic sealing film is formed so as to cover the low adhesion layer and the organic EL layer.

<5> The organic EL light-emitting device according to any one of <1> to <4>, wherein the low adhesion layer is formed by vapor deposition.

<6> The organic EL light-emitting device according to any one of <1> to <4>, wherein the low adhesion layer is formed by coating.

  In the organic EL light emitting device according to the present invention, a low adhesion layer that is preferentially peeled is provided between the second electrode on the organic EL layer and the sealing member, and the material constituting the organic EL layer is limited. Therefore, peeling between the organic EL layer and the electrode can be effectively prevented.

  Hereinafter, an organic EL light emitting device according to the present invention will be described with reference to the accompanying drawings.

  The inventor conducted intensive research on means for preventing electrode peeling in an organic EL light emitting device. As shown in FIG. 6, in particular, a flexible substrate such as a plastic film is used. On the substrate 12, a first electrode (anode) 14, an insulating layer 15, an organic EL layer 16, and a second electrode (cathode) 18 are used. When an organic EL light emitting device is manufactured by forming the above, peeling between the cathode 18 and the organic EL layer 16 tends to occur when stress is generated by bending. In particular, when the cathode 18 is formed of Al, the adhesion at the interface with the organic EL layer 16 is deteriorated. The method of forming the organic EL layer with a material that enhances the adhesion between the cathode 18 and the organic EL layer 16 is limited.

  Therefore, for example, as shown in FIG. 5, the inventor preferentially has a relatively small adhesion force between the second electrode 18 and the sealing member 28 and before the second electrode 18 is peeled off. It has been found that the peeling of the electrode can be suppressed by providing the low adhesion layer 22 that peels, and the present invention has been completed.

FIG. 1 is a plan view schematically showing an example of an organic EL light emitting device according to the present invention, and FIG. 2 schematically shows a part of a cross section along the line AA ′ in FIG. Yes.
The organic EL light emitting device 10 includes a transparent substrate (support substrate) 12, an organic EL element 20, a sealing member 28, and the like.

  The organic EL element 20 is configured by sequentially laminating an anode (first electrode) 14, an organic EL layer 16, and a cathode (second electrode) 18 on a substrate 12. A low adhesion layer 22 and a sealing film 24 are sequentially stacked on the cathode 18, and a sealing substrate 28 is provided on the sealing film 24 with an adhesive layer 26 interposed therebetween. In addition, a part of each electrode 14 and 18, a partition, an insulating layer, etc. are abbreviate | omitted.

In the organic EL light emitting device 10 having such a configuration, the low adhesion layer 22 is attached in contact with the cathode 18 and the organic EL layer 16 exposed between the cathodes 18, but the low adhesion layer 22, the cathode 18, and the organic EL. Each adhesion force between the layer 16 is smaller than each adhesion force between the organic EL layer 16 and the first electrode 14 and the second electrode 18.
Hereinafter, each component will be specifically described.

<Board>
The substrate 12 is not particularly limited as long as it has strength capable of supporting the organic EL element 20 and the like, light transmittance, and the like, and a known substrate can be used. For example, inorganic materials such as zirconia stabilized yttrium (YSZ), glass, polyesters such as polyethylene terephthalate (PET), polybutylene phthalate, polyethylene naphthalate (PEN), polystyrene, polycarbonate, polyethersulfone (PES), polyarylate, Examples include organic materials such as polyimide, polycycloolefin, norbornene resin, and poly (chlorotrifluoroethylene).

  For example, when glass is used as the substrate 12, it is preferable to use alkali-free glass in order to reduce ions eluted from the glass. When soda lime glass is used, it is preferable to use a glass with a barrier coat such as silica.

When a substrate made of an organic material is used, it is preferable that the substrate is excellent in heat resistance, dimensional stability, solvent resistance, electrical insulation, and workability. In particular, when a plastic substrate is used, it is preferable to provide a moisture permeation preventive layer or a gas barrier layer on one or both sides of the substrate in order to suppress moisture and oxygen permeation. As a material for the moisture permeation preventing layer or the gas barrier layer, an inorganic material such as silicon nitride or silicon oxide can be suitably used. The moisture permeation preventing layer or the gas barrier layer can be formed by, for example, a high frequency sputtering method.
When the thermoplastic substrate 12 is used, a hard coat layer, an undercoat layer, or the like may be further provided as necessary.

  There is no restriction | limiting in particular about the shape of a board | substrate 12, a structure, a magnitude | size, etc., It can select suitably according to the use, purpose, etc. of the organic electroluminescent light-emitting device 10, As a shape of a board | substrate 12, handling property, an organic EL element From the viewpoint of the ease of formation of 20 and the like, a plate shape is preferable. Further, the structure of the substrate 12 may be a single layer structure or a laminated structure. Moreover, the board | substrate 12 may be comprised by the single member and may be comprised by two or more members.

  The substrate 12 may be colorless and transparent or colored and transparent. However, the substrate 12 is preferably colorless and transparent from the viewpoint that scattering, attenuation, and the like of light emitted from the organic EL element 20 can be prevented.

  In the case of a so-called top emission type light emitting device in which light from the organic EL element 20 is extracted not from the support substrate 12 side but from the sealing substrate 28 side, a metal substrate 12 such as stainless steel may be used. it can.

  In the present invention, a flexible substrate 12 such as a film substrate made of an organic material or a metal substrate such as stainless steel can be suitably used. In the case of manufacturing an organic EL light emitting device using a flexible substrate, there is an advantage that it can be largely bent, but on the other hand, between the electrode in the organic EL element 20 formed on the substrate 12 and the organic EL layer 16. Peeling easily occurs. However, in the organic EL light emitting device 10 according to the present invention, since the low adhesion layer 22 that is easier to peel off than the electrodes 14 and 18 is formed between the second electrode 18 and the sealing member 28, the electrode 18 Since peeling occurs through the low adhesion layer 22 before peeling, peeling of the electrode 18 can be effectively prevented.

<Organic EL device>
An organic EL element 20 is formed on the substrate 12 as a light emitting element. As long as the organic EL element 20 has the organic EL layer 16 between a pair of electrodes composed of an anode 14 and a cathode 18 laminated in the thickness direction of the substrate 12, the layer structure is not particularly limited. For example, the following layer structure can be adopted. However, the layer structure of the element 20 is not limited to these, and may be determined as appropriate according to the purpose.

Anode / light-emitting layer / cathode Anode / hole transport layer / light-emitting layer / electron transport layer / cathode Anode / hole transport layer / light-emitting layer / block layer / electron transport layer / cathode Anode / hole transport layer / Light emitting layer / block layer / electron transport layer / electron injection layer / cathode ・ Anode / hole injection layer / hole transport layer / light emission layer / block layer / electron transport layer / cathode ・ Anode / hole injection layer / hole transport Layer / light emitting layer / block layer / electron transport layer / electron injection layer / cathode

<Anode and lead wiring>
On the substrate 12, for example, anodes 14 are formed as a first electrode in a stripe shape, and an extraction wiring is formed at one end.
As long as the anode 14 has a function as an electrode for supplying holes to the organic EL layer 16, the shape, structure, size, and the like are not particularly limited, and the use, purpose, and the like of the organic EL light-emitting device 10 are not limited. The electrode material can be appropriately selected from known electrode materials. However, in view of the properties of the organic EL element 20, at least one of the anode 14 and the cathode 18 is preferably transparent, and usually the transparent anode 14 is formed.

  Suitable materials for the anode 14 include, for example, metals, alloys, metal oxides, conductive compounds, or mixtures thereof. Specific examples include tin oxide (ATO, FTO) doped with antimony or fluorine, conductive metal oxides such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and zinc indium oxide (IZO), gold Metals such as silver, chromium and nickel, and mixtures or laminates of these metals and conductive metal oxides, inorganic conductive materials such as copper iodide and copper sulfide, and organic conductive materials such as polyaniline, polythiophene and polypyrrole Examples thereof include materials and laminates of these and ITO. Among these, a conductive metal oxide is preferable, and ITO is particularly preferable from the viewpoints of productivity, high conductivity, transparency, and the like.

Examples of the method for forming the anode 14 include a wet method such as a printing method and a coating method, a physical method such as a vacuum deposition method, a sputtering method, and an ion plating method, and a chemical method such as a CVD method and a plasma CVD method. It is done. The anode 14 can be formed on the substrate 12 according to a method appropriately selected in consideration of suitability with the material constituting the anode 14 and the like. For example, when ITO is selected as the anode material, the anode 14 can be formed according to a direct current or high frequency sputtering method, a vacuum deposition method, an ion plating method, or the like.
The position at which the anode 14 is formed is not particularly limited and can be appropriately selected according to the use, purpose, etc. of the organic EL light emitting device 10, and may be formed on the entire surface of one of the substrates 12, It may be formed in a part.

  Patterning when forming the anode 14 may be performed by chemical etching such as photolithography, or may be performed by physical etching using a laser or the like. Further, the mask may be overlapped, and vacuum deposition, sputtering, or the like may be performed, or may be performed by a lift-off method or a printing method.

  The lead-out wiring for the anode can also be formed by the same method using the same material as the anode 14. When forming the anode 14, a lead wiring connected to the anode 14 may be formed at the same time. At this time, a lead-out wiring for the cathode can be formed at the same time.

The thickness of the anode 14 and the lead-out wiring can be appropriately selected according to the material constituting the anode 14 and cannot be generally specified, but is usually about 10 nm to 50 μm, and preferably 50 nm to 20 μm.
Further, the resistance value of the anode 14 and the lead-out wiring is preferably 10 ³ Ω / □ or less, and more preferably 10 ² Ω / □ or less in order to reliably supply holes to the organic EL layer 16.

  When the transparent anode 14 is used, it may be colorless and transparent or colored and transparent. However, in order to extract emitted light from the transparent anode side, the light transmittance is preferably 60% or more, more preferably 70% or more. preferable. The transparent anode 14 is described in detail in “New Development of Transparent Electrode Film”, published by CMC (1999), supervised by Yutaka Sawada, and the matters described here can also be applied to the present invention. For example, when a plastic substrate with low heat resistance is used, a transparent anode formed using ITO or IZO at a low temperature of 150 ° C. or lower is preferable.

<Organic EL layer>
The organic EL element 20 has an organic EL layer 16 including at least a light emitting layer between the anode 14 and the cathode 18. Examples of the layers other than the light emitting layer constituting the organic EL layer 16 include layers such as a hole transport layer, an electron transport layer, a charge block layer, a hole injection layer, and an electron injection layer as described above. A preferable layer configuration includes an aspect in which a positive hole transport layer, a light emitting layer, and an electron transport layer are laminated in this order from the anode side, and further, for example, between the hole transport layer and the light emitting layer, or A charge blocking layer or the like may be provided between the electron transporting layer and the like. A hole injection layer may be provided between the anode 14 and the hole transport layer, and an electron injection layer may be provided between the cathode 18 and the electron transport layer. Each layer may be divided into a plurality of secondary layers.
Each layer constituting the organic EL layer 16 can be suitably formed by any of a dry film forming method such as a vapor deposition method and a sputtering method, a transfer method, and a printing method.

-Light emitting layer-
The light emitting layer receives holes from the anode 14, the hole injection layer, or the hole transport layer when an electric field is applied, receives electrons from the cathode 18, the electron injection layer, or the electron transport layer, and recombines holes and electrons. It is a layer having a function of providing light and emitting light.
The light emitting layer may be composed of only a light emitting material, or may be a mixed layer of a host material and a light emitting material. Further, the light emitting layer may include a material that does not have charge transporting properties and does not emit light. Further, the light emitting layer may be a single layer or two or more layers, and each layer may emit light in different emission colors.

The light emitting material may be a fluorescent light emitting material or a phosphorescent light emitting material, and the dopant may be one type or two or more types.
Examples of fluorescent light emitting materials include, for example, benzoxazole derivatives, benzimidazole derivatives, benzothiazole derivatives, styrylbenzene derivatives, polyphenyl derivatives, diphenylbutadiene derivatives, tetraphenylbutadiene derivatives, naphthalimide derivatives, coumarin derivatives, condensed aromatic compounds. , Perinone derivatives, oxadiazole derivatives, oxazine derivatives, aldazine derivatives, pyridine derivatives, cyclopentadiene derivatives, bisstyrylanthracene derivatives, quinacridone derivatives, pyrrolopyridine derivatives, thiadiazolopyridine derivatives, cyclopentadiene derivatives, styrylamine derivatives, diketo Typical examples include pyrrolopyrrole derivatives, aromatic dimethylidin compounds, metal complexes of 8-quinolinol derivatives and metal complexes of pyrroletene derivatives. Seed metal complexes, polythiophene, polyphenylene, polyphenylene vinylene polymer compounds include compounds such as organic silane derivatives.

Examples of the phosphorescent material include a complex containing a transition metal atom or a lanthanoid atom.
Although it does not specifically limit as a transition metal atom, Preferably, ruthenium, rhodium, palladium, tungsten, rhenium, osmium, iridium, and platinum are mentioned, More preferably, they are rhenium, iridium, and platinum.
Examples of lanthanoid atoms include lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Among these lanthanoid atoms, neodymium, europium, and gadolinium are preferable.

Examples of the ligand of the complex include G. Wilkinson et al., Comprehensive Coordination Chemistry, Pergamon Press, 1987, H. Yersin, “Photochemistry and Photophysics of Coordination Compounds”, Springer-Verlag, 1987, Akio Yamamoto Examples of the ligand include those described in “Organic Metal Chemistry-Fundamentals and Applications-” published in 1982.
Specific ligands are preferably halogen ligands (preferably chlorine ligands), nitrogen-containing heterocyclic ligands (eg, phenylpyridine, benzoquinoline, quinolinol, bipyridyl, phenanthroline, etc.), diketones Ligand (for example, acetylacetone), carboxylic acid ligand (for example, acetic acid ligand), carbon monoxide ligand, isonitrile ligand, cyano ligand, more preferably nitrogen-containing Heterocyclic ligand. The complex may have one transition metal atom in the compound, or may be a so-called binuclear complex having two or more. Different metal atoms may be contained at the same time.

  The phosphorescent material is preferably contained in the light emitting layer in an amount of 0.1 to 40% by mass, and more preferably 0.5 to 20% by mass.

The host material contained in the light emitting layer is preferably a charge transport material. The host material may be one type or two or more types, and examples thereof include a configuration in which an electron transporting host material and a hole transporting host material are mixed.
Specific examples of the host material include those having a carbazole skeleton, those having a diarylamine skeleton, those having a pyridine skeleton, those having a pyrazine skeleton, those having a triazine skeleton, those having an arylsilane skeleton, The materials exemplified in the sections of the hole injection layer, the hole transport layer, the electron injection layer, and the electron transport layer are given.

  Although the thickness of a light emitting layer is not specifically limited, Usually, it is preferable that they are 1 nm-500 nm, it is more preferable that they are 5 nm-200 nm, and it is still more preferable that they are 10 nm-100 nm.

-Hole injection layer, hole transport layer-
The hole injection layer and the hole transport layer are layers having a function of receiving holes from the anode 14 or the anode side and transporting them to the cathode 18 side. Specifically, the hole injection layer and the hole transport layer are carbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamines. Derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidin compounds, porphyrin compounds, organosilane derivatives, carbon In addition, a layer containing various metal complexes represented by an Ir complex having phenylazole or phenylazine as a ligand is preferable.

The thicknesses of the hole injection layer and the hole transport layer are each preferably 500 nm or less from the viewpoint of lowering the driving voltage.
The thickness of the hole transport layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 200 nm. The thickness of the hole injection layer is preferably 0.1 nm to 200 nm, more preferably 0.5 nm to 200 nm, and still more preferably 1 nm to 200 nm.
The hole injection layer and the hole transport layer may have a single-layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions. .

-Electron injection layer, electron transport layer-
The electron injection layer and the electron transport layer are layers having a function of receiving electrons from the cathode 18 or the cathode side and transporting them to the anode side. Specifically, the electron injection layer and the electron transport layer are triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, fluorenone derivatives, anthraquinodimethane derivatives, anthrone derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, Carbodiimide derivatives, fluorenylidenemethane derivatives, distyrylpyrazine derivatives, aromatic tetracarboxylic anhydrides such as naphthalene and perylene, phthalocyanine derivatives, metal complexes of 8-quinolinol derivatives, metal phthalocyanines, benzoxazoles and benzothiazoles as ligands It is preferably a layer containing various metal complexes typified by metal complexes, organosilane derivatives, and the like.

The thicknesses of the electron injection layer and the electron transport layer are each preferably 500 nm or less from the viewpoint of lowering the driving voltage.
The thickness of the electron transport layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 100 nm. In addition, the thickness of the electron injection layer is preferably 0.1 nm to 200 nm, more preferably 0.2 nm to 100 nm, and still more preferably 0.5 nm to 50 nm.
The electron injection layer and the electron transport layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

-Hole blocking layer-
The hole blocking layer is a layer having a function of preventing holes transported from the anode side to the light emitting layer from passing through to the cathode side. A hole blocking layer adjacent to the light emitting layer on the cathode side can be provided.
Examples of the organic compound constituting the hole blocking layer include aluminum complexes such as BAlq, triazole derivatives, phenanthroline derivatives such as BCP, and the like.
The thickness of the hole blocking layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 100 nm.
The hole blocking layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

<Cathode and lead wiring>
On the organic EL layer 16, as the second electrode, for example, cathodes 18 are formed in a stripe shape so as to intersect the anode 14.
The cathode 18 usually has a function as an electrode for injecting electrons into the organic EL layer 16, and there is no particular limitation on the shape, structure, size, etc., depending on the use, purpose, etc. of the organic EL light-emitting device 10. Thus, it can be appropriately selected from known electrode materials. Examples of the material constituting the cathode 18 include metals, alloys, metal oxides, electrically conductive compounds, and mixtures thereof. Specific examples include alkali metals (eg, Li, Na, K, Cs, etc.), alkaline earth metals (eg, Mg, Ca, etc.), gold, silver, lead, aluminum, sodium-potassium alloy, lithium-aluminum alloy, magnesium- Examples thereof include silver alloys, rare earth metals such as indium and ytterbium. These may be used singly or in combination of two or more from the viewpoint of achieving both stability and electron injection.

Among these, the material constituting the cathode 18 is preferably a metal such as an alkali metal, an alkaline earth metal, or silver from the viewpoint of electron injection, and a material mainly composed of aluminum from the viewpoint of excellent storage stability. More preferred. The material mainly composed of aluminum is aluminum alone, an alloy of aluminum and 0.01 to 10% by mass of alkali metal or alkaline earth metal, or a mixture thereof (for example, lithium-aluminum alloy, magnesium-aluminum alloy, etc.) Say.
The material of the cathode 18 is described in detail in, for example, Japanese Patent Laid-Open Nos. 2-15595 and 5-121172, and the materials described in these publications can also be applied to the present invention. .

  There is no restriction | limiting in particular about the formation method of the cathode 18, It can form according to a well-known method. For example, the cathode 18 is configured from a wet method such as a printing method or a coating method, a physical method such as a vacuum deposition method, a sputtering method, or an ion plating method, or a chemical method such as a CVD method or a plasma CVD method. It can be formed according to a method appropriately selected in consideration of suitability with the material. For example, when a metal or the like is selected as the material of the cathode 18, the cathode 18 can be formed according to a sputtering method or the like, one or more of them simultaneously or sequentially.

  The patterning for forming the cathode 18 may be performed by chemical etching such as photolithography, may be performed by physical etching using a laser or the like, or may be performed by vacuum deposition or sputtering with a mask overlapped. However, it may be performed by a lift-off method or a printing method.

  The lead-out wiring for the cathode can be formed by the same method using the same material as the cathode 18 and can be formed at the same time when the cathode 18 is formed.

  The formation position of the cathode 18 is not particularly limited, and may be formed on the entire organic EL layer 16 or a part thereof.

  In addition, a dielectric layer made of an alkali metal or alkaline earth metal fluoride or oxide may be formed between the cathode 18 and the organic EL layer 16 in a thickness of 0.1 to 5 nm. This dielectric layer can also be understood as a kind of electron injection layer. The dielectric layer can be formed by, for example, a vacuum deposition method, a sputtering method, an ion plating method, or the like.

The thickness of the cathode 18 can be appropriately selected depending on the material constituting the cathode 18 and cannot be generally defined, but is usually about 10 nm to 5 μm, and preferably 50 nm to 1 μm.
The cathode 18 may be transparent or opaque. In addition, when setting it as the transparent cathode 18, it can form by forming the material of the cathode 18 thinly in the thickness of 1-10 nm, and laminating | stacking transparent conductive materials, such as ITO and IZO especially.

<Low adhesion layer>
A low adhesion layer 22 is provided on the cathode (second electrode) 18. In the low adhesion layer 22 of the present invention, at least on one surface of the low adhesion layer 22, the adhesion between the low adhesion layer 22 and the layer in contact with the low adhesion layer 22 is such that the organic EL layer 16, the first electrode, and the second electrode 18 The layers are smaller than the respective adhesive strengths between the layers. For example, the low adhesion layer 22 is formed such that the adhesion of the low adhesion layer 22 to the second electrode 18 and the organic EL layer 16 is smaller than the adhesion between the second electrode 18 and the organic EL layer 16.

  The low adhesion layer 22 is formed on the second electrode 18 at least in the light emitting region 30. For example, as shown in FIGS. 1 and 2, the low adhesion layer 22 can be formed over the entire region 32 that is wider than the light emitting region 30 and exposes the lead wires of the electrodes 14 and 18. Thereby, the low adhesion layer 22 is formed on the exposed portion of the second electrode 18 and the organic EL layer 16 in the light emitting region 30.

  The method for forming the low adhesion layer 22 may be appropriately selected depending on the material, but it is particularly preferable to use an organic compound capable of forming a layer by vapor deposition or coating. If the low adhesion layer 22 is formed of an organic compound, the second electrode 18 is sandwiched between the organic EL layer 16 and the low adhesion layer 22 made of an organic compound. As a result, the adhesion at the laminated portion of the organic compounds is increased, and the second electrode 18 is not peeled off at the interface between the low adhesion layer 22 and the sealing film 24 due to the stress generated when bent. The effect which becomes difficult to peel from can be acquired.

  As a material that can be deposited for forming the low adhesion layer 22, for example, Alq3, BAlq, or the like can be selected. When the low adhesion layer 22 is formed by coating, for example, a fluorine-based compound such as OPTOOL (registered trademark, manufactured by Daikin Industries, Ltd.) is applied on the organic EL element 20 by spin coating, and then dried. Thus, the low adhesion layer 22 can be formed. The fluorine-based compound has a high contact angle with water, and can exhibit the effect as the low adhesion layer 22.

  The thickness of the low adhesion layer 22 is set to a thickness that can reliably cover the second electrode 18, but if formed thicker than necessary, the thickness of the entire light emitting device may increase or the manufacturing cost may increase. Is about 1 nm to 1 μm, preferably 10 nm to 500 nm, and more preferably 10 nm to 100 nm.

  Note that if the adhesion of the low adhesion layer 22 is too small, the effect of preventing electrode peeling may not be sufficiently exhibited. In order to reliably and sufficiently exert the effect of suppressing electrode peeling, the adhesion of the low adhesion layer 22 is, for example, 10% to 80% of the adhesion between the cathode 18 and the organic EL layer 16, preferably It is 10% to 50%, more preferably 10% to 30%.

  In the embodiment illustrated in FIG. 2, the low adhesion layer 22 is formed so as to cover the entire light emitting region 30, but the low adhesion layer 22 may be formed at least on the cathode (second electrode) 18. For example, as shown in FIGS. 3 and 4, a region along each cathode 18 formed in a stripe shape is defined as a low adhesion layer region 33, and the low adhesion layer 22 is striped so as to cover each cathode 18. The organic EL layer 16 may be exposed between the cathodes 18.

<Sealing film>
A sealing film 24 is formed on the low adhesion layer 22. The sealing film 24 is made of a material having a barrier property against oxygen and moisture in the atmosphere. For example, a silicon nitride (SiNx) film, a silicon oxide (SiOx) film, a silicon oxynitride (SiOxNy) film, or Al _{2 is used.} An inorganic thin film such as O ₃ is suitable.

  As a method for forming the sealing film 24, for example, a chemical method printing method such as CVD or plasma CVD method, a physical method such as vacuum deposition method, sputtering method or ion plating method, or a wet method such as coating method is used. And may be appropriately selected depending on the material to be used.

  The sealing film 24 is formed so as to cover the low adhesion layer 22 and the organic EL layer 16. Thereby, the barrier property with respect to oxygen and a water | moisture content can be acquired reliably.

  The thickness of the sealing film 24 can be appropriately selected according to the material constituting the sealing film 24 and cannot be generally defined, but is usually about 50 nm to 10 μm, and preferably 100 nm to 5 μm.

<Sealing member>
On the sealing film 24, a sealing substrate 28 is further provided as a sealing member via an adhesive layer 26.
As the adhesive layer 26, a photocurable adhesive such as an epoxy resin or a thermosetting adhesive can be used. For example, a thermosetting adhesive sheet can also be used.

As the sealing substrate 28, a substrate having a high barrier property against oxygen or moisture is used, and a substrate made of a known sealing material such as glass, metal, or a resin film provided with a barrier layer can be used. In addition, when manufacturing the organic EL light-emitting device which has flexibility, it is preferable to use the sealing substrate made from the resin film which provided the barrier layer. As the resin film sealing substrate 28, the same material as that of the support substrate 12 such as PET, PEN, PES, or the like can be used.
The thickness of the barrier layer may be determined according to the material and required barrier properties, but is usually 100 nm to 5 μm, more preferably 1 μm to 5 μm.

  An adhesive is applied on the sealing film 24 or on one surface of the sealing substrate 28, or the sealing substrate 28 is attached with an adhesive sheet interposed between the sealing film 24 and the sealing substrate 28. The sealing substrate 28 is wider than the region 32 where the organic EL layer 16 and the low adhesion layer 22 are formed so that the organic EL element 20 can be reliably sealed, and each of the electrodes 14, 18. It is preferable that the entire surface is bonded to the region 34 where a part of the lead wiring is exposed. Thereby, as shown in FIG. 2, the organic EL element 20 is sealed by the sealing film 24 and the sealing substrate 28, and higher barrier properties can be imparted to oxygen and moisture.

  After sealing, the organic EL layer 16 between the electrodes can emit light by connecting an external wiring to the lead-out wiring of each of the electrodes 14 and 18 and applying an electric field between the electrodes. In addition, about the drive method of the organic EL element 20, each of Unexamined-Japanese-Patent No. 2-148687, 6-301355, 5-29080, 7-134558, 8-234585, 8-240147 The driving methods described in the publications, Japanese Patent No. 2784615, US Pat. Nos. 5,828,429 and 6023308, and the like can be applied.

  As described above, the organic EL light emitting device 10 according to the present invention can be manufactured. In the organic EL light emitting device 10, the low adhesion layer 22 is provided between the second electrode 18 and the sealing member 28. Then, due to the stress generated when it is bent, for example, as shown in FIG. 5, separation occurs preferentially at the interface between the low adhesion layer 22, the second electrode 18 and the organic EL layer 16. It can suppress that it peels from 16. Thus, even if peeling occurs in the portion of the low adhesion layer 22, the organic EL element 20 can maintain the light emitting function as long as no peeling occurs between the electrode and the organic EL layer 16. Therefore, it is not necessary to limit the materials of the second electrode 18 and the organic EL layer 16, and the life of the organic EL light emitting device can be extended.

Example 1
<Formation of organic EL element>
A SiON film was formed as a barrier layer on a transparent polyethylene naphthalate (PEN) film having a thickness of 100 μm so as to have a thickness of 1 μm by the CVD method. Further, a first electrode (anode) 14 made of ITO, an organic EL layer 16, and a second electrode (cathode) 18 made of Al were sequentially formed. In addition, the 1st electrode 14 and the 2nd electrode 18 were each made into stripe form, and it formed so that it might mutually orthogonally cross. The organic EL layer 16 has a structure in which 2-TNATA is 100 nm as a hole injection layer, αNPD is 20 nm as a hole transport layer, Alq3 is 30 nm as a light emitting layer, LiF is 0.5 nm as an electron injection layer, and vacuum deposition is used. Formed by.

<Formation of a low adhesion layer>
After forming the second electrode 18, a low adhesion layer 22 having a thickness of 30 nm was formed by vacuum deposition using Alq3.

<Formation of sealing layer>
Next, a sealing layer was formed so as to cover the low adhesion layer 22. As the sealing layer, a SiN film having a thickness of 1 μm was formed by a CVD method.

<Preparation of adhesive sheet>
A composition prepared by the following components on a transparent polyethylene terephthalate film having a thickness of 100 μm was applied and dried by a wire bar coating method so that the thickness after drying was 20 μm to prepare an adhesive sheet.

-Polyvinyl butyral resin (S-REC BLS: manufactured by Sekisui Chemical Co., Ltd.): 12g
・ Acrylic resin (Dianar BR-87: trade name, manufactured by Mitsubishi Rayon Co., Ltd.): 48g
・ Urethane acrylate (U-6HA: trade name of Shin-Nakamura Chemical Co., Ltd.): 16g
・ Pentaerythritol diacrylate: 24g
・ Azoisobutyl nitrile (thermal polymerization initiator): 0.3 g
・ Methyl ethyl ketone: 400ml

<Preparation of sealing film>
As a sealing film, a SiON film as a barrier layer was formed on a transparent polyethylene naphthalate (PEN) film having a thickness of 100 μm by a CVD method so as to have a thickness of 1 μm.

<Sealing>
Next, the adhesive sheet (sheet-like thermosetting resin) is peeled off from the transparent polyethylene terephthalate film, and the surface of the sealing layer on the flexible support substrate 12 faces the surface of the barrier layer of the sealing film. In this way, the adhesive sheets were sandwiched and formed by hot pressing. The conditions for hot pressing were a temperature of 100 ° C., a pressing pressure of 0.2 MPa, and a pressing time of 1 hour.
External wiring was connected to each electrode, and the organic EL light-emitting device 10 was manufactured.

Comparative Example 1
An organic EL light emitting device was manufactured in the same manner as in Example 1 except that the low adhesion layer 22 was not formed.

<Evaluation>
In order to investigate the presence or absence of peeling of the cathode, a bending test and an environmental test were performed.
The bending test was performed with a radius of curvature of 20 mm. The environmental test was conducted at a temperature of 60 ° C. and a humidity of 90% for 500 hours.

In the organic EL light emitting device of Example 1, dark spots were not observed in all tests.
On the other hand, in the organic EL light emitting device of Comparative Example 1, dark spots were observed in all tests.

Although the present invention has been described above, the present invention is not limited to the above embodiment.
For example, the low adhesion layer 22 only needs to be formed between the second electrode 18 and the sealing substrate 28. For example, after forming the sealing film 24 on the second electrode 18, Alternatively, the low adhesion layer 22 may be formed. Further, after forming the low adhesion layer 22 on the second electrode 18, the sealing substrate 28 can be attached without forming the sealing film.

  Further, the sealing member is not a type in which the flat sealing substrate 28 as shown in FIG. 2 is bonded to the entire surface, but, for example, only the outside of the light emitting region is bonded and a space is provided between the organic EL element 20 A sealing member to be used may be used. Even when such a sealing member is used, if the low adhesion layer 22 is provided between the second electrode 18 and the sealing film 24, the low adhesion layer 22 and a layer adjacent thereto are preferentially used. It is possible to obtain an effect of suppressing peeling and peeling of the second electrode 18 from the organic EL layer 16.

Further, the organic EL light emitting device according to the present invention may be a passive matrix type or an active matrix type.
In addition, the use of the organic EL light emitting device according to the present invention is not particularly limited. For example, in addition to a lighting device, a display device such as a television, a personal computer, a mobile phone, and electronic paper can be used.

It is a schematic plan view which shows an example of the organic electroluminescent light-emitting device concerning this invention. It is a figure which shows schematically a part of cross section along the AA 'line in FIG. It is a schematic sectional drawing which shows the other aspect of a low adhesion layer. It is a schematic plan view which shows the formation area of a low adhesion layer. It is a schematic sectional drawing which shows the state peeled through the low adhesion layer. It is a schematic sectional drawing which shows the state which the 2nd electrode peeled from the organic electroluminescent layer. It is the schematic which shows an example of a structure of an organic EL element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Organic EL light-emitting device 12 Substrate 14 Anode 16 Organic EL layer 18 Cathode 20 Organic EL element 22 Low adhesion layer 24 Sealing film 26 Adhesive layer 28 Sealing member

Claims (6)

A substrate,
An organic EL element in which at least a first electrode, an organic EL layer, and a second electrode are sequentially laminated on the substrate;
An organic EL light emitting device including a sealing member for sealing the organic EL element,
A low adhesion layer is provided between the second electrode and the sealing member, and at least one surface of the low adhesion layer has an adhesion force between the layer in contact with the low adhesion layer and the organic An organic EL light emitting device characterized by being smaller than the adhesion between the EL layer and the first electrode and the second electrode.   The organic EL light-emitting device according to claim 1, wherein the substrate is flexible.   The organic EL light-emitting device according to claim 1, wherein an inorganic sealing film is provided as a layer in contact with the low adhesion layer.   The organic EL light-emitting device according to claim 3, wherein the inorganic sealing film is formed so as to cover the low adhesion layer and the organic EL layer.   The organic EL light-emitting device according to any one of claims 1 to 4, wherein the low adhesion layer is formed by vapor deposition.   The organic EL light-emitting device according to any one of claims 1 to 4, wherein the low adhesion layer is formed by coating.

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