JP2003168556A - Organic el element structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible type EL element structure in which occurrence of defects such as a dark spot is suppressed. <P>SOLUTION: A plurality of layers formed on a flexible substrate 1 comprise organic EL element layers interposed between the uppermost layer 9 and the flexible substrate 1 and inorganic moisture-proof layers 2, 8 clipping the organic EL element layers, and the inorganic moisture-proof layers 2, 8 are positioned nearly in the center in the thickness direction of the organic EL element structure. Thereby, distortion inside the inorganic moisture-proof layers 2, 8 is suppressed and occurrence of defects such as a dark spot is suppressed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an organic EL device structure.

[0002]

2. Description of the Related Art Organic EL (electroluminescence)
The device is expected as a next-generation flat display. If the pixel is divided into a plurality of pixels in the organic EL element, each pixel can selectively emit light.

The organic EL element utilizes light emission by injecting charges into an organic fluorescent substance. Early type organic EL
The device is described in JP-A-59-194393, and has a two-layer structure in which an organic fluorescent dye is used as a thin film light emitting layer, and this is laminated with an organic charge transporting compound used for an electrophotographic photoreceptor or the like. Have.

This organic EL element has a low driving voltage of around 5 V and is capable of emitting light in the three primary colors of RGB.
It is characterized by high response speed, and is expected to be applied to flat light emitters such as backlights for liquid crystal displays (LCDs) and sheet-like illumination light sources, and small displays to large displays such as TVs and monitors (J
pn. J. Appl. Phys. Volume 27, L
269 (1988), J. J. Appl. P
hys. Volume 65, page 3610 (1989).

In the organic EL element, improvement of display quality, reduction of luminance due to deterioration of the light emitting body, and prevention of generation of dark spots appearing on the light emitting surface during storage are the most important issues. The organic EL element layer is formed by sandwiching the organic layer between a cathode material and an anode material, and the organic EL element layer is covered with a moisture-proof material. However, the decrease in brightness and the growth of dark spots in the organic EL element layer are as follows. It is said to be caused by the cause.

The cathode material (active metals such as Mg and Al) is oxidized by moisture and oxygen that have entered the organic EL element layer through the sealing material and impurities in the constituent materials, and the interface with the organic layer is peeled off. The light emitting function is significantly reduced. Oxidation of the cathode material reduces the conductivity, resulting in a significant decrease in the light emitting function. As a result of the accelerated deterioration of the organic layer, the light emitting function is significantly reduced.

In view of these causes, the material used is purified, the element is formed in an inert atmosphere, and the element is sealed with a metal can or a glass substrate using a low melting point glass or a sealing material. Measures are being considered.

On the other hand, an organic EL element structure including such an organic EL element layer is expected to be flexible from the viewpoint of mechanical strength. It is also considered in part to fabricate the organic EL element layer on a flexible transparent resin substrate such as a plastic film in place of a substance that is extremely chemically and dimensionally stable such as glass or metal to form a flexible display. ing.

Generally, a resin material has higher permeability to moisture and oxygen than a metal or glass material. Therefore, when a resin material is used as a substrate for an organic EL element, it is necessary to impart a high moisture-proof function (gas barrier function) from the viewpoint of suppressing the generation of dark spots and the deterioration of the element as described above. Attempts have been made to provide a moisture-proof property by laminating a thin film (hereinafter, referred to as an inorganic moisture-proof layer) basically made of a gas-impermeable ceramic on a flexible substrate.

However, the inorganic material used as the inorganic moisture-proof layer is generally a brittle material and is characterized by being weak against mechanical tensile deformation.
Therefore, since minute defects in the inorganic moisture-proof layer induce macroscopic destruction, scratches and deposits on the surface of the underlying flexible substrate are eliminated in advance to prevent damage to the inorganic moisture-proof layer. It is said to be effective in preventing deterioration.

As a flexible substrate for an organic EL element, a method of forming an organic EL element on a substrate in which a large number of resin layers and thin glass substrates are laminated and sealing the element with the resin layer (Japanese Patent Laid-Open No. 11- 329715), a method of laminating an inorganic moisture-proof layer made of silicon oxide and silicon nitride, and sealing with a resin (Japanese Patent Laid-Open No. HEI 0-58100).
9-161967), a thickness of 20
A thin glass substrate having a thickness of 0 μm or less and a plurality of resin layers are laminated.

[0012]

However, in a flexible organic EL element structure in which an organic EL element formed on a flexible substrate is sealed with an inorganic moisture-proof layer, a resin substrate having a thickness of several hundred μm is used. On the other hand, it has a structure in which an inorganic moisture-proof layer having a thickness of 1 μm or less and a sealing resin layer having a thickness of several tens of μm are laminated. Occurs. As a result, the deterioration of the organic EL element layer is accelerated. The present invention has been made in view of such a problem, and an object of the present invention is to provide an organic EL element structure in which the generation of dark spots and the decrease in brightness are suppressed.

[0013]

In order to solve the above-mentioned problems, an organic EL element structure according to the present invention is formed by laminating a plurality of layers on a flexible substrate, and a bottom surface of the flexible substrate. An organic EL device structure defined by a thickness direction region between an outermost surface of a plurality of layers and an exposed surface, wherein the plurality of layers are interposed between the outermost surface layer and a flexible substrate. An organic EL element layer and an inorganic moisture-proof layer sandwiching the organic EL element layer are provided, and the inorganic moisture-proof layer is characterized by being located at a substantially central portion in the thickness direction of the organic EL element structure.

The "substrate" in the "flexible substrate" includes a "thin film" such as a resin film. Organic EL
The element structure has flexibility, but the inorganic moisture barrier layer is organic EL.
Since the element structure is located substantially in the center in the thickness direction, the forces for pulling the front surface and the back surface of the inorganic moisture-proof layer when the structure is curved become substantially equal, and the stress generated in the inorganic moisture-proof layer can be significantly reduced. As a result, the defect occurrence rate of the inorganic moisture-proof layer is lowered, and therefore, the organic E sandwiched between them is reduced.
Deterioration of the L element layer is suppressed, and as a result, generation of dark spots is suppressed, and a long life is achieved.

The term "substantially central portion" means that the thickness from the bottom surface of the flexible substrate to the exposed surface of the outermost surface layer is D, within ± 10% of the total thickness D from the center in the thickness direction. It means an area located at a distance.

Although it is a brittle material, a material having excellent moisture resistance (gas barrier property) can be used as the inorganic moisture-proof layer. Such an inorganic moisture-proof layer, silicon, aluminum,
The oxide, nitride, oxynitride, or fluoride of at least one element selected from the group consisting of magnesium, calcium, tin, and indium, or a mixture thereof.

Even if a minute defect occurs in the inorganic moisture-proof layer, the plurality of layers are provided with a transparent resin protective layer adhered onto the inorganic moisture-proof layer farther from the flexible substrate. In this case, the transparent resin protective layer suppresses the introduction of gas into the organic EL element layer from this defect.

The flexible substrate is preferably made of an amorphous transparent resin. Such an amorphous transparent resin comprises at least one resin selected from the group consisting of polyethylene terephthalate, polycarbonate, polyether sulfone and cycloolefin polymer.

If the inorganic moisture-proof layer is arranged in the substantially central portion, it is effective in suppressing the final generation of dark spots, but the materials and thicknesses of the other layers are set so as to reduce the strain in the inorganic moisture-proof layer. If so, the generation of defects in the inorganic moisture-proof layer is further suppressed, and the final generation of dark spots is suppressed.
The material and the thickness of each of the plurality of layers are set so that the strain generated in the inorganic moisture-proof layer is 1% or less when the radius of curvature having the radius in the thickness direction of the organic EL element layer is 20 mm. It is preferable.

The thickness Tf of the flexible substrate, the thickness Tc of the transparent resin protective layer, the elastic modulus E _c of the transparent resin protective layer and the elastic modulus E _f of the flexible substrate greatly contribute to the strain generation in the inorganic moisture-proof layer. If these parameters satisfy the following inequality: 0.8 ≦ (E _c × T _c ) / (E _f × T _f ) ≦ 1.2, the strain generation in the inorganic moisture-proof layer is significantly suppressed. can do.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The organic EL according to the embodiments will be described below.
The element structure will be described. The same elements will be denoted by the same reference symbols, without redundant description.

FIG. 1 is a vertical sectional view of an organic EL device structure according to an embodiment. First, the structure of the organic EK element structure will be described.

The organic EL element structure is formed by laminating a plurality of layers 2, 3, 4, 5, 6, 7, 8, 9 on the flexible substrate 1, and is formed on the bottom surface 1X of the flexible substrate 1. Multiple layers 2, 3, 4,
5, 6, 7, 8 and 9 are defined in the thickness direction region between the outermost surface layer 9 and the exposed surface 9X. It should be noted that these constituent elements are in close contact with each other.

This organic EL device structure comprises a flexible substrate 1
It comprises a lower inorganic moisture barrier layer 2, a transparent electrode (anode layer) 3, a hole transporting (injecting) layer 4, a phosphor layer 5, an electron transporting (injecting) layer 6 and a cathode layer 7, which are sequentially laminated on top. An upper inorganic moisture-proof layer 8 is formed on the cathode layer 7, and an organic EL element layer composed of layers 3 to 7 is sandwiched between the lower inorganic moisture-proof layer 2 and its side surface as well. A transparent resin protective layer (outermost surface layer) 9 is provided in close contact with the upper inorganic moisture-proof layer 8.

When a voltage is applied between the anode layer 3 and the cathode layer 7, the holes injected from the anode layer 3 reach the inside of the phosphor layer 5 through the hole transport layer 4 and the cathode layer 7 The injected electrons reach the inside of the phosphor layer 5 through the electron transport layer 6 and recombine inside the phosphor layer 5, whereby the phosphor layer 5 emits light. Light emitted from the phosphor layer 5 is emitted to the outside through the transparent flexible substrate 1.

The inorganic moisture-proof layers 2 and 8 are located substantially at the center of the organic EL element structure in the thickness direction. The substrate in the flexible substrate 1 is used to include a thin film such as a resin film. Although the organic EL element structure has flexibility, since the inorganic moistureproof layers 2 and 8 are located in the approximate center of the organic EL element structure in the thickness direction, the front surface and the back surface of the inorganic moistureproof layer are pulled when the structure is curved. The forces are almost equal, and the inorganic moisture barrier 2,
The stress generated in 8 can be significantly reduced. As a result, the defect occurrence rate of the inorganic moisture-proof layers 2 and 8 is lowered, and therefore, the organic EL element layers 3 to 7 sandwiched between them.
Deterioration is suppressed, and as a result, the generation of dark spots is suppressed and a long life is achieved.

The term "substantially the central portion" means that the thickness from the bottom surface 1X of the flexible substrate 1 to the exposed surface 9X of the transparent resin protective layer (outermost surface layer) 9 is D, from the center in the thickness direction. It means a region located within a distance of ± 10% of the total thickness D.

Even if a minute defect occurs in the inorganic moisture-proof layers 2 and 8, this structure has a transparent resin protective layer adhered to the inorganic moisture-proof layer 8 located far from the flexible substrate 1. 9 is provided, the transparent resin protective layer 9 suppresses the introduction of gas into the organic EL element layer from this defect.

Although arranging the inorganic moisture-proof layers 2 and 8 in the substantially central portion is effective in suppressing the final generation of dark spots, the material and thickness of the other layers reduce strain in the inorganic moisture-proof layer. If such a setting is made, it is possible to further suppress the occurrence of defects in the inorganic moisture-proof layers 2 and 8 and to suppress the final occurrence of dark spots.

Each of the plurality of layers 2 to 9 has a strain of 1% or less generated in the inorganic moistureproof layers 2 and 8 when the radius of curvature having the radius in the thickness direction of the organic EL element layer is 20 mm. , Each material and thickness are set.

The thickness Tf of the flexible substrate 1, the thickness Tc of the transparent resin protective layer, the elastic modulus E _c of the transparent resin protective layer and the elastic modulus E _f of the flexible substrate are strains in the inorganic moisture-proof layers 2 and 8. When these parameters satisfy the following inequalities, it is possible to remarkably suppress the strain generation in the inorganic moisture-proof layers 2 and 8. 0.8 ≦ (E _c × T _c ) / (E _f × T _f ) ≦ 1.2

Next, the flexible substrate 1, the lower inorganic moisture-proof layer 2,
Anode layer 3, hole transport layer 4, phosphor layer 5, electron transport layer 6,
Materials of the cathode layer 7, the upper inorganic moisture-proof layer 8 and the transparent resin protective layer 9 will be described.

First, the flexible substrate 1 will be described.

As a material for forming the flexible substrate 1, any resin that can be used for forming a vacuum thin film can be used without any problem.

As the material constituting the flexible substrate 1, polycarbonate, methyl methacrylate, polyethylene terephthalate, polyethylene-2,6-naphthalate,
In addition to polysulfone, polyethersulfone, polyetheretherketone, polyphenoxyether, polyarylate, fluororesin, polypropylene, ARTO
Cycloolefin polymers such as N (JSR Corporation), ZEONEX, ZEONOR (Nippon Zeon Corporation),
TAC (cellulose triacetate) or the like can be used.

The flexible substrate 1 is preferably made of an amorphous transparent resin. A particularly preferred amorphous transparent resin comprises at least one resin selected from the group consisting of polyethylene terephthalate, polycarbonate, polyether sulfone and cycloolefin polymer.

Examples of the material constituting the flexible substrate 1 include a material having a glass transition temperature (Tg) of 100 ° C. or higher and high transparency. From this viewpoint, the flexible substrate 1 As the material of No. 1, polycarbonate, polyethylene terephthalate, polyether sulfone or cycloolefin polymer can be used. You may use these resins in combination.

The protrusions and scratches present on at least the surface of the flexible substrate 1 forming the organic EL element layer are defects (pinholes or cracks) of the lower inorganic moisture-proof layer 2 formed on the flexible substrate 1. Not only is it a cause, but it also causes a protrusion to be generated on the electrode of the organic EL element layer. Such protrusions are a factor that shortens the element life such as short-circuiting of the electrodes of the organic EL element and acceleration of element deterioration due to concentration of an electric field, and should be eliminated as much as possible. As for smoothness, the surface roughness Ra is preferably 50 nm or less, more preferably 10 nm or less.

The thickness of the flexible substrate 1 is not particularly limited, but it is necessary that it does not impair the original flexibility of the substrate and has a certain degree of mechanical strength. 6 to 500 μm, especially 12 to 250
μm is preferred.

As a method for molding the flexible substrate 1, an extrusion method, a casting method and the like can be used, but a casting method which is particularly excellent in surface smoothness is preferable. Further, the film thus formed may be further subjected to heat treatment such as stretching or annealing and smoothing treatment.

Next, the lower inorganic moisture barrier layer 2 will be described.

The resin material has higher permeability to water and oxygen than the metal or glass material. In contrast, inorganic materials such as ceramics and metal layers are basically impermeable to gas.
The lower inorganic moisture-proof layer 2 is made of silicon oxide or aluminum oxide,
A transparent ceramic layer such as magnesium oxide, tin oxide, or indium oxide-tin oxide is used.

Although it is a brittle material, it can be used as the inorganic moisture-proof layer 2 if it is excellent in moisture-proof property (gas barrier property). Such an inorganic moisture barrier layer 2 is an oxide of at least one element selected from the group consisting of silicon, aluminum, magnesium, calcium, tin and indium,
It is made of nitride, oxynitride, fluoride, or a mixture thereof.

In particular, silicon oxynitride is a material having both the transparency of silicon oxide, the adhesion of silicon nitride and the strength characteristics.

The composition of silicon oxynitride is represented by the composition formula Si
When expressed as O _x N _y , 0.4 ≦ x ≦ 1.2y, 1.8
It is preferable that ≦ x + 1.5y. When x is larger than 1.2y, the strength and adhesion of the inorganic moisture barrier layer 2 are reduced. Further, when x is less than 0.4, the inorganic moisture-proof layer 2 becomes brownish and is not preferable as a constituent material of the light emitting device. Also, when x + 1.5y is less than 1.8, the inorganic moisture-proof layer similarly exhibits a brown color, which is not preferable as a constituent material of the light emitting device.

Next, the anode layer 3 will be described.

The conductive material used for the anode layer 3 is 4.
Those having a work function larger than 0 eV are preferable, and carbon, aluminum, silver, gold, platinum, palladium and the like and alloys thereof, ITO substrates, metal oxides such as tin oxide and indium oxide, and further polythiophene, polypyrrole and the like. Organic conductive resins are used, but not limited to these. The anode layer 3 can be formed with a layer structure of two or more layers if necessary. The anode layer 3 as a transparent electrode is formed by using the above-mentioned conductive material so as to ensure a predetermined translucency, but the visible light transmittance of the flexible substrate 1 and the anode layer 3 combined is It is desirable to be 50% or more.

Next, the hole transport layer 4 will be described.

As a constituent material of the hole transport layer 4, holes are efficiently injected from the anode layer 3 and have a capability of transporting holes, and the phosphor layer 5 or the organic light emitting material in the phosphor layer 5 is used. A compound having an excellent hole injection effect and capable of forming a thin film is preferable.

Specific examples of the constituent material of the hole transport layer 4 include phthalocyanine compounds, naphthalocyanine compounds, porphyrin compounds, stilbenes, benzidine type triphenylamines, styrylamine type triphenylamines, and diamine type triphenylamines. There are, but not limited to, phenylamine and the like, their derivatives, and polymeric materials such as polyvinylcarbazole, polysilane, and conductive polymers.

The layer thickness of the hole transport layer 4 needs to be at least such that pinholes are not generated, but if it is too thick, the resistance of the device increases and a high driving voltage is required, which is not preferable. Therefore, the thickness of the hole transport layer is preferably 1 nm to 1 μm, more preferably 2 nm to 500.
nm, particularly preferably 5 to 200 nm.

Next, the phosphor layer 5 will be described.

The phosphor layer 5 is composed of an organic light emitting material and a doping material added to the organic light emitting material as necessary.

The organic luminescent material is excellent in thin film forming ability, and in the thin film state, holes and electrons injected from the electrode or the hole transport layer or the electron transport layer are efficiently recombined in the phosphor layer 5, It is a material that can be excited by the energy generated at that time and has high emission intensity, which is energy emission when returning from the excited state to the ground state.

The doping material is a material added to the phosphor layer 5 when the brightness from the phosphor layer 5 is improved or the emission color is changed. The doping material is the phosphor layer 5
In principle, even if the thin film does not emit light in a single thin film state, the thin film forming ability may be poor, or the thin film may not exhibit light emission.

Specific examples of the organic light emitting material or doping material include anthracene, naphthalene, phenanthrene, pyrene, tetracene, coronene, coumarin, bisstyryl, quinoline metal complex, aminoquinoline metal complex, benzoquinoline metal complex, polymethine, There are polymer compounds such as merocyanine, imidazole chelated oxinoid compound, quinacridone, rubrene, and their derivatives and polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives,
It is not limited to these.

The thickness of the phosphor layer 5 is preferably 1 nm to
It is 1 μm, more preferably 2 nm to 500 nm. To increase the current density and luminous efficiency, 5 to 200n
A range of m is preferred.

Next, the electron transport layer 6 will be described.

As a constituent material of the electron transport layer 6, a compound having an ability to transport electrons, an excellent electron injection effect to the phosphor layer or the organic light emitting material, and an excellent thin film forming ability is used. Can be mentioned. For example, fluorenone, tetrazole, perylene tetracarboxylic acid, fluorenylidene methane, anthraquinodimethane, anthrone and their derivatives, bis (8-hydroxyquinolinate) zinc,
Tris (8-hydroxyquinolinate) aluminum,
Tris (2-methyl-8-hydroxyquinolinato) aluminum, tris (8-hydroxyquinolinato) gallium, bis (10-hydroxybenzo [h] quinolinato) beryllium, bis (10-hydroxybenzo [h] quinolinate) Metal complex compounds such as zinc, bis (2-methyl-8-quinolinato) (1-naphtholate) aluminum, bis (2-methyl-8-quinolinato) (2-naphthorate) gallium, oxazole, thiazole, oxadiazole, thiadiazole. Alternatively, there are nitrogen-containing five-membered derivatives such as triazole derivatives, but the present invention is not limited thereto.

In each of the hole transport layer 4, the phosphor layer 5, and the electron transport layer 6 in the organic EL device, a hole injection material is used so that holes or electrons are efficiently injected from the electrodes and are transported in the layers. It is also possible to mix and use two or more kinds of organic light emitting material, doping material or electron injecting material in the same layer. Further, the hole transport layer 4, the phosphor layer 5, and the electron transport layer 6 can each be formed with a layer structure of two or more layers.

In order to efficiently transport the holes injected from the anode layer 3 or the electrons injected from the cathode layer 7 to the organic light emitting material or the doping material, the phosphor layer 5 has a hole injecting material or an electron. An injection material may be added. Further, an electron accepting substance may be added to the hole transporting layer 4 and an electron donating substance may be added to the electron transporting layer 6 for sensitization.

The layer thickness of the electron transport layer 6 needs to be at least such that pinholes are not generated, but if it is too thick, the resistance of the device increases and a high driving voltage is required, which is not preferable. Therefore, the thickness of the electron transport layer is preferably 1 nm to 1 μm, more preferably 2 nm to 500.
nm, particularly preferably 5 to 200 nm.

Next, the cathode layer 7 will be described.

As the conductive material used for the cathode layer 7, one having a work function smaller than 4.0 eV is suitable, and cesium, rubidium, potassium, sodium,
Lithium, barium, strontium, calcium, magnesium, europium, ytterbium, samarium, cerium, erbium, gadolinium, yttrium, neodymium, lanthanum, scandium, etc. and these 4
An alloy with a metal element of eV or higher is used, but the alloy is not limited to these.

Next, the upper inorganic moisture-proof layer 8 will be described.

The upper inorganic moisture-proof layer 8 can be made of a material that can be used in the lower inorganic moisture-proof layer 8.

Next, the transparent resin protective layer 9 will be described.

The constituent material of the transparent resin protective layer 9 is not particularly limited, but in addition to curable resins such as urethane resin, epoxy resin, acrylic resin, and epoxy acrylate resin, polycarbonate, methyl methacrylate, polyethylene terephthalate, Polyethylene-2,6-naphthalate, polysulfone, polyethersulfone, polyetheretherketone, polyphenoxyether,
In addition to polyarylate, fluororesin, polypropylene,
ARTON (JSR Corporation), ZEONEX, ZEON
A cycloolefin polymer such as OR (Nippon Zeon Co., Ltd.) and a film such as TAC (cellulose triacetate) can be laminated and used.

As a method for laminating these transparent resin protective layers 9, a solution of the transparent resin layer is applied and dried to form a resin layer having a predetermined layer thickness, that is, a so-called casting method, or a predetermined layer thickness is prepared in advance. A laminating method of laminating and bonding the set films can be used.

For the purpose of interpolating the barrier property of the upper inorganic moisture-proof layer 8, as the transparent resin protective layer 9, a low moisture permeable resin such as a known fluorine resin or polyolefin resin, polyvinyl alcohol resin, or vinyl chloride resin is used. It is also effective to stack and use a resin having low oxygen permeability. By laminating these resins, the gas permeation amount can be suppressed even when minute defects are present in the inorganic moisture-proof layer 8.

For the purpose of interpolating the barrier property of the lower inorganic moisture-proof layer 2, the same material as that of the transparent resin protective layer 9 can be used.

As a constituent material of the transparent resin protective layer 9, a material having mechanically similar characteristics to the flexible substrate 1 can be used.

Next, a method for manufacturing the organic EL element structure shown in FIG. 1 will be described. First, the inorganic moisture barrier layer 2 is formed on the flexible substrate 1. As a layering device for the inorganic moisture barrier layer 2, a continuous winding type or a single-wafer type can be used.
As a method of forming the inorganic moisture-proof layer 2, a chemical vapor deposition method can be used in addition to a physical vapor deposition method such as DC sputtering or RF sputtering.

As the target raw material used in the sputtering method, a metal target of an inorganic moisture-proof layer to be formed, an oxide, a nitride, or a mixture target of these compounds can be used.

When a silicon compound is used as the inorganic moisture-proof layer 2, metallic silicon, a mixture of metallic silicon and silicon dioxide, a simple substance of silicon monoxide, a mixture of silicon, silicon dioxide and silicon monoxide, silicon nitride, silicon oxide and nitride. Examples thereof include a mixture of silicon, and the layer composition can be optimized by adjusting the flow rate ratio of the reactive gas such as oxygen and nitrogen in the presence of a dischargeable inert gas such as argon gas.

Next, the anode layer 3 is formed on the flexible substrate 1 on which the inorganic moisture barrier layer 2 is formed. The anode layer 3 has an electrode pattern such as a conductive metal oxide layer and a semitransparent metal thin film. The method for forming these electrode patterns is not particularly limited, and it can be produced by combining a vacuum layering method such as a general sputtering method and an etching method through a resist mask.

After that, the hole transport layer 4 is formed on the anode layer 3. The method for forming the hole transport layer 4 is not particularly limited, but it is a vacuum deposition method from a powder state, spin coating or dipping with a solution or a mixed solution / mixed melt with a polymer compound, bar coating, roll coating, etc. Can be used.

Next, the phosphor layer 5 is formed on the hole transport layer 4. As the organic light emitting material forming the phosphor layer 5, the above-mentioned low molecular weight light emitting material, polymer light emitting material or polymer light emitting material is used, and an appropriate charge transport material is contained therein.

Here, the method of forming the phosphor layer of the organic EL element will be described. In particular, when a low molecular weight light emitter is used, it is generally formed by vapor deposition, sputtering or the like. When it is necessary to form a pattern on the luminous body, it is possible to deposit the luminous body after covering the substrate with a sputter mask having an opening having a desired shape. When a polymer light emitting material is used, a wet layering method such as a spin coating method, a casting method, a dipping method, a bar coating method or a roll coating method is exemplified.

In the case of the wet layering method, the material forming each layer is dissolved or dispersed in an appropriate solvent such as chloroform, tetrahydrofuran or dioxane to form a thin film, and any solvent may be used. Further, in any of the thin films, in order to improve the layering property and prevent pinholes in the layer,
Appropriate resins and additives may be used. Examples of the additives include antioxidants, ultraviolet absorbers, plasticizers and the like.

Further, an electron transport layer 6 is formed on the phosphor layer 5 if necessary. The method for forming the electron transport layer 6 is not particularly limited, but a vacuum deposition method from a powder state,
A coating method such as spin coating, dipping, bar coating, or roll coating with a solution or a mixed solution or mixed melt with a polymer compound can be used.

The cathode layer 7 is provided on the phosphor layer 5 or the electron transport layer 6.
To form. Examples of the method for forming the cathode layer 7 include resistance heating vapor deposition, electron beam vapor deposition, DC sputtering, RF sputtering, and ion plating. The present invention is directed to improving the stability or other properties of the cathode,
Does not prevent making multi-component alloy. Further, the cathode may be composed of two or more layers of metal or alloy, if necessary,
The composition and the component ratio of the lower part and the upper part of the layer may continuously change.

Next, the upper inorganic moisture-proof layer 8 is formed on the cathode layer 7. The method for forming the upper inorganic moisture-proof layer 8 is the same as the method for forming the lower inorganic moisture-proof layer 8.

Further, a transparent resin protective layer 9 is formed on the upper inorganic moisture-proof layer 8. As the method for forming the transparent resin protective layer 9, the above-mentioned casting method or laminating method can be used.

The organic EL element structure has the inorganic moistureproof layers 2 and 8 on a flexible substrate, and further has an inorganic moistureproof layer different from these inorganic moistureproof layers 2 and 8. What is useful is that the reliability is further improved.

FIG. 2 is a vertical sectional view of such an organic EL element structure. The difference from the one shown in FIG. 1 is that the flexible substrate 1 has an inorganic moisture-proof layer 1a inside thereof, and the transparent resin protective layer 9 has an inorganic moisture-proof layer 9a inside thereof. . These inorganic moisture barrier layers 1a and 9a function as gas barriers to the organic EL element layer.

In this example, a new flexible substrate 1 is formed by forming the inorganic moisture-proof layer 1a and the transparent resin protective layer 1b on the bottom surface of the flexible substrate body made of resin. Further, a new transparent resin protective layer 9 is formed by forming the inorganic moisture-proof layer 9a and the transparent resin protective layer 9b on the surface of the transparent resin protective layer body. Therefore, the region in the thickness direction between the bottom surface 1X of the flexible substrate 1 and the exposed surface 9X of the transparent resin protective layer 9b is defined as the organic EL element structure.

The inorganic moisture-proof layer sandwiching the organic EL layer is the organic E layer from the viewpoint of completely blocking the organic EL layer from the outside.
It is preferable to completely cover the L layer.

Further, the inorganic moisture-proof layer sandwiching the organic EL layer is preferably a total of two inorganic moisture-proof layers, but it is not limited to a particular layer and may be a total of three or more layers.

[0090]

EXAMPLES Examples of the present invention will be described below.
The present invention is not limited to these.

Example 1 The organic EL device structure shown in FIG. 1 was manufactured. First, a polyether sulfone (PES) substrate (flexible substrate 1) having a thickness of 200 μm and 10 cm □
Was immersed in an ultrapure water tank, and ultrasonic cleaning was performed for 20 minutes. This substrate was taken out from the ultrapure water tank and dried, and then a silicon oxynitride layer (inorganic moisture barrier layer 2) was formed to a thickness of about 200 nm using an RF sputtering device (SPF-530H manufactured by Anelva).

The layer of the silicon oxynitride layer was formed by targeting high-purity silicon (B-doped) to a vacuum degree of 0.5 P.
a, argon 50 sccm, oxygen 1.3 sccm, nitrogen 2.6 sccm, applied power 0.48 W, inter-electrode distance 7
It was carried out for 30 minutes at 0% and the substrate rotation speed was 24 rpm. The transmittance of the formed silicon oxynitride layer is shown in FIG. Note that FIG. 3 is a graph showing the relationship between the wavelength (nm) of incident light and the transmittance (%).

11 is formed by mask sputtering on the inorganic moisture-proof layer 2 of the flexible substrate 1 on which the inorganic moisture-proof layer 2 is formed.
The ITO layer (anode layer 3) is formed with a thickness of 0 nm,
After depositing TPD on the layer to a thickness of 50 nm (hole transport layer 4),
As phosphor layer 5 / electron transport layer 6, tris (8-quinolinol) aluminum (Alq3) was vapor-deposited at 60 nm. Then, as a first metal layer of the cathode layer 7, lithium-
40n aluminum alloy (lithium concentration: 1wt%)
m was vapor-deposited.

Further, a 200 nm thick silicon oxynitride layer (inorganic moistureproof layer 8) is formed on the cathode layer 7 under the same conditions as the formation of the inorganic moistureproof layer 2 on the flexible substrate 1. At this time, the electrode pad (external contact portion) forming the end portion of the cathode layer 7 was covered with a sputter mask to prevent deposition of the insulating inorganic moisture-proof layer on the electrode pad.

After attaching an external terminal to this electrode, an acrylic photo-curing resin was applied to a thickness of 10 μm to give a thickness of 20 μm.
After stacking a 0 μm polyethersulfone (PES) substrate, the resin was cured by irradiation with light of about 1 J / cm ^{2 from} a mercury lamp to seal the resin, and a transparent resin protective layer 9 made of these was formed.

A radius of 20 is added to the manufactured organic EL device structure.
When a bending deformation of mm is applied, the strain generated in the vicinity of the inorganic moisture-proof layer is calculated to be 0.2%.

Comparative Example 1 A thickness of 200 μm on the cathode layer 7
An organic EL device structure was prepared in the same manner as in Example 1 except that the PES substrate of 1 was not adhered. Radius 2 for this structure
The strain generated in the vicinity of the inorganic moisture-proof layers 2 and 8 when a bending deformation of 0 mm is applied is calculated to be 1.0%.

(Evaluation and Results) When a DC voltage of 5 V was applied to the devices of Examples and Comparative Examples, stable EL emission was observed. The brightness was almost proportional to the current density. The organic EL element structure of the example is wound on a cylinder of 20 mmφ,
When the appearance of the device after the test was observed under a microscope, no particular change was observed in the inorganic moisture-proof layers 2 and 8.

The organic EL device structure of the comparative example was wound around a cylinder of 20 mmφ in the same manner as in the example. When the appearance after the test was observed with a microscope, many fine cracks were observed on the surfaces of the inorganic moisture-proof layers 2 and 8.

[0100]

According to the organic EL device structure of the present invention,
Deterioration of the organic EL element layer is significantly suppressed, dark spots are reduced, and a long life is achieved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an organic EL element structure according to an embodiment.

FIG. 2 is a vertical cross-sectional view of an organic EL device structure according to another embodiment.

FIG. 3 is a graph showing the relationship between the wavelength (nm) of incident light and the transmittance (%).

[Explanation of symbols]

1 ... Flexible substrate, 1X ... Bottom surface, 9a ... Inorganic moisture-proof layer, 1a
... inorganic moisture-proof layer, 1b ... transparent resin protective layer, 2 ... lower inorganic moisture-proof layer, 3 ... anode layer, 4 ... hole transport layer, 5 ... phosphor layer, 6
... electron transport layer, 7 ... cathode layer, 8 ... upper inorganic moisture-proof layer, 8
... Lower inorganic moisture-proof layer, 9 ... Outermost surface layer (transparent resin protective layer),
9b ... Transparent resin protective layer, 9X ... Exposed surface.

Continued front page    (72) Inventor Koichi Fujisawa             6 Kitahara, Tsukuba-shi, Ibaraki Sumitomo Chemical Co., Ltd.             Inside the company F term (reference) 3K007 AB11 AB15 BA07 BB02 BB05                       CA06 CB01 DB03 EA01 EB00                       FA01 FA02

Claims (7)

[Claims] 1. A plurality of layers are laminated on a flexible substrate and defined by a thickness direction region between a bottom surface of the flexible substrate and an exposed surface of an outermost surface layer of the plurality of layers. An organic EL element structure, wherein the plurality of layers comprises an organic EL element layer interposed between the outermost surface layer and the flexible substrate, and an inorganic moisture-proof layer sandwiching the organic EL element layer. The organic EL element structure is characterized in that the inorganic moisture barrier layer is located substantially in the center of the organic EL element structure in the thickness direction. 2. The inorganic moisture barrier layer is an oxide of at least one element selected from the group consisting of silicon, aluminum, magnesium, calcium, tin and indium.
The organic EL device according to claim 1, wherein the organic EL device comprises a nitride, an oxynitride, a fluoride, or a mixture thereof.
Device structure. 3. The organic E according to claim 1, wherein the plurality of layers include a transparent resin protective layer that is in close contact with the inorganic moisture barrier layer that is farther from the flexible substrate.
L element structure. 4. The organic EL device structure according to claim 1, wherein the flexible substrate is made of an amorphous transparent resin. 5. The amorphous transparent resin comprises at least one resin selected from the group consisting of polyethylene terephthalate, polycarbonate, polyether sulfone and cycloolefin polymer. Organic EL device structure. 6. Each of the plurality of layers comprises the organic E
The material and the thickness are set so that the strain generated in the inorganic moisture-proof layer is 1% or less when the radius of curvature of which the radius is the radius of the L element layer is 20 mm. The organic EL device structure according to item 1. 7. The thickness Tf of the flexible substrate, the thickness Tc of the transparent resin protective layer, the elastic modulus E _c of the transparent resin protective layer and the elastic modulus E _f of the flexible substrate have the following inequality: 0.8 ≦ The organic EL device structure according to claim 1, wherein (E _c × T _c ) / (E _f × T _f ) ≦ 1.2 is satisfied.