JPH11307259A - Organic el element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element having heat resistance, weather resistance, stable physical property and high productivity in mass production at a low cost. SOLUTION: This organic EL element has a hole injection electrode 22, an electron injection electrode 26 and one or more kinds of organic layer relating to a light emitting function between these electrodes, and has a hole injection layer 23 between the organic layer and the hole injection electrode 22. This hole injection layer 23 having carbon as a main ingredient is doped by one or more kinds of element selected from B, Al, Ga, In, Tl and As and/or one or more kinds of compound selected from nickel oxide, chromium oxide, ferrous oxide, ferric oxide and molybdenum oxide, in order to make this EL element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescence (EL) device, and more particularly, to a device that emits light by applying an electric field to a thin film made of an organic compound.

[0002]

2. Description of the Related Art An organic EL device has a structure in which a thin film containing a fluorescent organic compound is sandwiched between an electron injection electrode and a hole injection electrode, and electrons and holes are injected into the thin film and recombined. Generate excitons,
Light emission when this exciton is deactivated (fluorescence / phosphorescence)
This is an element that emits light by utilizing.

[0003] The characteristics of the organic EL element are that it can emit a very high luminance of several hundreds to several tens of thousands cd / m ² at a voltage of about 10 V, and can change the color from blue to red by selecting the type of fluorescent substance. Light emission is possible.

Meanwhile, an organic EL device having a structure using a tin-doped indium oxide (ITO) transparent electrode as a hole injection electrode and a tetraarylenediamine derivative as a hole injection / transport compound for a hole injection / transport layer or the like is known. It is known (JP-A-63-29569, etc.).

However, for example, N, N, N ', N'-tetrakis (-m-biphenyl) is directly formed on the ITO transparent electrode.
When a layer of a tetraarylenediamine derivative such as -1,1'-biphenyl-4,4'-diamine is formed, there is a problem that the luminescence lifetime is not sufficient due to crystallization of the tetraarylenediamine derivative or separation of the layer.

In order to deal with such a problem, ITO
4, which is also a hole injecting and transporting compound, between the transparent electrode and the layer containing the tetraarylenediamine derivative.
4 ', 4 "-tris (-N-(-3-methylphenyl)
-N-phenylamino) triphenylamine (MTDA
It has been practiced to provide a layer containing TA) to obtain a hole injection effect and to improve the adhesion between the two layers (Japanese Patent Laid-Open No. 4-308688, etc.).

However, for example, 4,4 ', 4 "-tris (-N-(-3-methylphenyl) -N-phenylamino) triphenylamine has a glass transition temperature of 80.degree.
And heat resistance is insufficient. Organic EL elements
Practically, it is used under a high electric field strength and cannot escape heat generation.
4 "-tris (-N-(-3-methylphenyl) -N-
The heat resistance of organic materials such as phenylamino) triphenylamine is serious, and as a result, there is a problem that the light emission lifetime is not sufficient.

Further, when these organic materials are deteriorated or physical properties at the interface are deteriorated, an erroneous light emission phenomenon occurs due to a leak current, and a non-light emitting region called a dark spot is generated and expanded. This significantly impairs the display quality.

Further, the organic materials used for the hole injection layer, the electron injection layer and the like are relatively expensive. For this reason, cost reduction is an important issue when considering application to large displays and mass-produced products.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide heat resistance and weather resistance, which can suppress the occurrence of leak current and dark spots, have stable physical properties, and have high mass productivity and low cost. An object of the present invention is to provide an organic EL device that can be manufactured.

[0011]

The above object is achieved by the following constitution. (1) A hole injection electrode, an electron injection electrode, and at least one or more organic layers involved in at least a light emitting function between these electrodes, and an inorganic hole is provided between the organic layer and the hole injection electrode. The inorganic hole injection layer includes carbon as a main component, and further contains B, Al, Ga, In,
Mixing or doping one or more of the elements selected from Tl and As and / or one or more of the compounds selected from nickel oxide, chromium oxide, ferrous oxide, and molybdenum oxide An organic EL device. (2) The organic EL device according to (1), wherein the inorganic hole injection layer has a thickness of 1 to 50 nm.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The organic EL device of the present invention has a hole injection electrode, an electron injection electrode, and one or more organic layers at least related to a light emitting function between these electrodes. An inorganic hole injecting layer is provided between the organic layer and the hole injecting electrode. The hole injecting layer contains carbon as a main component, and contains one of B, Al, Ga, In, Tl and As.
One or more kinds of compounds selected from nickel oxide, chromium oxide, ferrous oxide, and molybdenum oxide are mixed or doped.

The inorganic hole injection layer has a function of facilitating the injection of holes from the hole injection electrode, a function of stably transporting holes, and a function of preventing electrons.
This layer increases and confines the holes injected into the light emitting layer, optimizes the recombination region, and improves luminous efficiency.
The hole transport layer (or, in addition to the inorganic hole injection layer)
Hole injection transport layer) may be provided between the light emitting layer and
The light emitting layer may be a hole transporting light emitting layer.

By making the hole injection layer a layer using an inorganic material, the heat resistance can be improved, and the life and weather resistance of the element can be improved. Further, unlike an organic material that is relatively expensive, an inorganic material that is inexpensive and easily available is used, so that the production becomes easy and the production cost can be reduced. Further, by using an inorganic material for the hole injection layer, the connectivity and adhesion to a hole injection electrode such as ITO can be improved. In addition, the thermal diffusivity becomes good, and the durability and life of the element are improved.

The thickness of the inorganic hole injection layer is not particularly limited as long as holes can be injected efficiently. Specifically, although it differs depending on the forming material, usually, 1
~ 50 nm is preferred. When the inorganic hole injection layer is on the light extraction side, the emission wavelength band, usually 400 to 700 nm,
In particular, the light transmittance for each emitted light is preferably 50% or more, preferably 70% or more, and particularly preferably 80% or more.
When the transmittance is low, the light emission from the light emitting layer itself is attenuated, and the luminance required for the light emitting element tends not to be obtained.

As a material constituting the inorganic hole injection layer, carbon is a main component, and B, Al, Ga, In,
One or more elements selected from Tl and As and / or one or more compounds selected from nickel oxide, chromium oxide, ferrous oxide and molybdenum oxide are mixed or doped. Things.

The above B, Al, Ga, In, Tl and A
The content of the element selected from s is 0.5 to 5 at.
%, Preferably nickel oxide, chromium oxide, primary oxide
Iron and molybdenum oxide are each 5
It is preferable to mix or dope about 50 at%.

When a sputtering method is used as a method for mixing or doping these materials, a material obtained by doping these materials on a target may be used, or a chip of these materials may be placed on the target, Reactive sputtering or binary sputtering may be used. After the carbon film is formed, these materials may be doped by ion implantation or the like.

The formed film mainly composed of carbon is usually in a non-single-crystal state. Such a film structure and a film composition can be confirmed by XRD (X-ray diffraction), EPMA (Electron Probe Micro-Analysis), or the like.

The above-mentioned inorganic hole injection layer can be formed by a sputtering method, a plasma CVD, or the like.
Sputtering is preferred.

When the inorganic hole injection layer is formed by the sputtering method, the pressure of the sputtering gas during the sputtering is 0.1 to 1
The range of Pa is preferable. As the sputtering gas, an inert gas such as Ar, Kr, or Xe used in a normal sputtering apparatus can be used. The power of the sputtering apparatus is preferably 1
The range is from 0 to 100 W / cm ² . Further, the film formation rate is preferably in the range of 5 to 100 nm / min, particularly 10 to 50 nm / min.

In the organic EL device of the present invention, when a hole injection layer formed of the above-mentioned insulating inorganic material is used, a hole injection layer made of an organic substance (or a layer having a hole injection / transport substance except a light emitting layer) ) Is preferably not used.

A configuration example of the organic EL device of the present invention will be described. FIG. 1 is a schematic sectional view showing one configuration example of the organic EL element. In the figure, the organic EL device of the present invention comprises a substrate 21, a hole injection electrode 22, such as ITO, formed thereon, an inorganic hole injection layer 23, a light emitting layer 24, an electron injection layer 25, and an electron injection layer. And an electrode 26 sequentially. The organic EL device of the present invention is not limited to the configuration of the illustrated example, and various modifications and applications are possible.

For a color display, for example,
A first hole injection electrode such as ITO on a substrate, a first hole injection layer, a first light emitting layer, a first electron injection layer,
A first electron injection electrode is sequentially stacked, and a second electron injection layer, a second light emitting layer, a second hole injection layer,
A second hole injection electrode is sequentially stacked, and a third hole injection layer, a third light emitting layer, a third electron injection layer, and a second electron injection electrode are sequentially stacked thereon. What is necessary is just to set it as the structure.

Alternatively, for example, a first electron injection electrode, a first electron injection layer, a first light emitting layer,
A hole injection layer and a first hole injection electrode are sequentially laminated, and a second hole injection layer, a second light emitting layer, a second electron injection layer, and a second electron injection layer are stacked thereon. Electrodes may be sequentially stacked, and a third electron injection layer, a third light emitting layer, a third hole injection layer, and a second hole injection electrode may be sequentially stacked thereon. In this case, the thickness of the electron injection electrode or the like is preferably 100 nm or less in order to secure light transmittance. In addition, one or more of the hole injection layers may be the inorganic hole injection layer of the present invention.

If necessary, a hole injection transport layer or a hole transport layer may be provided between each hole injection electrode and the hole injection layer, or an electron injection layer may be provided between each electron injection electrode and the electron injection layer. A transport layer or an electron transport layer may be provided. Further, in the laminate, the hole transport layer and / or the electron transport layer of the present invention need not necessarily be all layers, but may be one or more. In the case of such a structure in which a plurality of laminates are laminated, heat resistance is improved by providing the hole transport layer and / or the electron transport layer of the present invention, and the organic layer is sandwiched by an oxide film or the like. The performance is improved.

In these examples, a three-layered laminate serving as one light-emitting unit is laminated, and a full-color display using three primary colors or three primary colors are simultaneously emitted to function as a broad white light source. Has become.

Since the hole injection electrode is generally configured to extract light emitted from the substrate side, a transparent or translucent electrode is preferable. As the transparent electrode, similarly to the above-mentioned electron injection electrode, ITO (tin-doped indium oxide), IZO (zinc-doped indium oxide), ZnO, SnO ₂ , In ₂
O _{3 and the} like are exemplified, and ITO (tin-doped indium oxide) and IZO (zinc-doped indium oxide) are preferable.

When the hole injection electrode is an electrode on the side from which light is extracted, the light transmittance is 80% or more, especially 90%, for the emission wavelength band, usually 400 to 700 nm, especially for each emitted light.
It is preferable that it is above. When the transmittance is low, the light emission from the light emitting layer itself is attenuated, and the luminance required for the light emitting element tends not to be obtained.

The thickness of the hole injecting electrode may be a certain thickness or more that can sufficiently inject holes, and is preferably 5 or more.
The range is preferably from 0 to 500 nm, more preferably from 50 to 300 nm. The upper limit is not particularly limited, but if the thickness is too large, there is a fear of peeling or the like. If the thickness is too small, there is a problem in the film strength at the time of manufacturing, the hole transport ability, and the resistance value.

The hole injecting electrode layer can be formed by a vapor deposition method or the like, but is preferably formed by a sputtering method, particularly, a DC sputtering method or a pulse sputtering method.

The organic layer can have the following structure. The light emitting layer has a function of transporting holes (holes) and electrons, and a function of generating excitons by recombination of holes and electrons. It is preferable to use a relatively electronically neutral compound for the light emitting layer.

The electron injecting and transporting layer has a function of facilitating electron injection from the electron injecting electrode, a function of stably transporting electrons, and a function of preventing holes.
This layer increases and confines the electrons injected into the light emitting layer, optimizes the recombination region, and improves luminous efficiency.

The thickness of the light emitting layer and the thickness of the electron injection transport layer are as follows:
There is no particular limitation, and although it depends on the forming method, it is usually preferably about 5 to 500 nm, particularly preferably 10 to 300 nm.

The thickness of the electron injecting / transporting layer depends on the design of the recombination / light emitting region.
It may be about 0 to 10 times. When the electron injection layer and the transport layer are separated, the injection layer is 1 nm or more, and the transport layer is 1 nm or more.
It is preferably at least nm. At this time, the upper limit of the thickness of the injection layer and the transport layer is usually about 500 nm for the injection layer and about 500 nm for the transport layer. Such a film thickness is the same when two injection / transport layers are provided.

The light emitting layer of the organic EL element contains a fluorescent substance which is a compound having a light emitting function. Examples of such a fluorescent substance include, for example, JP-A-63-26469.
No. 2 discloses at least one compound selected from compounds such as quinacridone, rubrene, and styryl dyes. Also, Tris (8
-Quinolinolato) quinoline derivatives such as metal complex dyes having 8-quinolinol or a derivative thereof as a ligand such as aluminum, tetraphenylbutadiene, anthracene, perylene, coronene, and 12-phthaloperinone derivatives. Further, phenylanthracene derivatives disclosed in Japanese Patent Application No. 6-110569, and Japanese Patent Application No. 6-11445.
No. 6 tetraarylethene derivative or the like can be used.

Further, it is preferable to use in combination with a host substance capable of emitting light by itself, and it is preferable to use it as a dopant. In such a case, the content of the compound in the light emitting layer is 0.01 to 20% by weight, and more preferably 0.1 to 20% by weight.
It is preferably 1 to 15% by weight. When used in combination with a host substance, the emission wavelength characteristics of the host substance can be changed, light emission shifted to a longer wavelength becomes possible, and the luminous efficiency and stability of the device are improved.

As the host substance, a quinolinolato complex is preferable, and an aluminum complex having 8-quinolinol or a derivative thereof as a ligand is preferable. Such an aluminum complex is disclosed in JP-A-63-26469.
No. 2, JP-A-3-255190, JP-A-5-7073
3, JP-A-5-258859, JP-A-6-2158
No. 74 and the like.

Specifically, first, tris (8-quinolinolato) aluminum, bis (8-quinolinolato) magnesium, bis (benzo {f} -8-quinolinolato) zinc, bis (2-methyl-8-quinolinolato) aluminum Oxide, tris (8-quinolinolato) indium,
Tris (5-methyl-8-quinolinolato) aluminum, 8-quinolinolatolithium, tris (5-chloro-
8-quinolinolato) gallium, bis (5-chloro-8-
Quinolinolato) calcium, 5,7-dichloro-8-quinolinolatoaluminum, tris (5,7-dibromo-
8-hydroxyquinolinolato) aluminum and poly [zinc (II) -bis (8-hydroxy-5-quinolinyl) methane].

In addition to 8-quinolinol or its derivative, an aluminum complex having another ligand may be used, such as bis (2-methyl-
8-quinolinolato) (phenolato) aluminum (III)
, Bis (2-methyl-8-quinolinolato) (ortho-
Cresolato) aluminum (III), bis (2-methyl-
8-quinolinolato) (meth-cresolate) aluminum
(III), bis (2-methyl-8-quinolinolato) (para-cresolato) aluminum (III), bis (2-methyl-8-quinolinolato) (ortho-phenylphenolate)
Aluminum (III), bis (2-methyl-8-quinolinolato) (meth-phenylphenolato) aluminum (II
I), bis (2-methyl-8-quinolinolato) (para-
Phenylphenolato) aluminum (III), bis (2-
Methyl-8-quinolinolato) (2,3-dimethylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (2,6-dimethylphenolato) aluminum (III), bis (2-methyl- 8-quinolinolato)
(3,4-dimethylphenolato) aluminum (III),
Bis (2-methyl-8-quinolinolato) (3,5-dimethylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (3,5-di-tert-butylphenolato) aluminum (III) ), Bis (2-methyl-8)
-Quinolinolato) (2,6-diphenylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (2,4,6-triphenylphenolato) aluminum (III), bis (2-methyl- 8-quinolinolato)
(2,3,6-trimethylphenolato) aluminum (I
II), bis (2-methyl-8-quinolinolato) (2,
3,5,6-tetramethylphenolato) aluminum (I
II), bis (2-methyl-8-quinolinolato) (1-naphthrat) aluminum (III), bis (2-methyl-8
-Quinolinolato) (2-naphthrat) aluminum (II
I), bis (2,4-dimethyl-8-quinolinolato)
(Ortho-phenylphenolato) aluminum (III),
Bis (2,4-dimethyl-8-quinolinolato) (para-
Phenylphenolato) aluminum (III), bis (2,
4-dimethyl-8-quinolinolato) (meta-phenylphenolato) aluminum (III), bis (2,4-dimethyl-8-quinolinolato) (3,5-dimethylphenolato) aluminum (III), bis (2 4-dimethyl-8
-Quinolinolato) (3,5-di-tert-butylphenolato) aluminum (III), bis (2-methyl-4-ethyl-8-quinolinolato) (para-cresolato) aluminum (III), bis (2-methyl) -4-methoxy-8-quinolinolato) (para-phenylphenolato) aluminum (III), bis (2-methyl-5-cyano-8-quinolinolato) (ortho-cresolato) aluminum (III),
Bis (2-methyl-6-trifluoromethyl-8-quinolinolato) (2-naphthrat) aluminum (III);

In addition, bis (2-methyl-8-quinolinolato) aluminum (III) -μ-oxo-bis (2-
Methyl-8-quinolinolato) aluminum (III), bis (2,4-dimethyl-8-quinolinolato) aluminum
(III) -μ-oxo-bis (2,4-dimethyl-8-quinolinolato) aluminum (III), bis (4-ethyl-
2-methyl-8-quinolinolato) aluminum (III)-
μ-oxo-bis (4-ethyl-2-methyl-8-quinolinolato) aluminum (III), bis (2-methyl-4
-Methoxyquinolinolato) aluminum (III) -μ-oxo-bis (2-methyl-4-methoxyquinolinolato)
Aluminum (III), bis (5-cyano-2-methyl-
8-quinolinolato) aluminum (III) -μ-oxo-
Bis (5-cyano-2-methyl-8-quinolinolato) aluminum (III), bis (2-methyl-5-trifluoromethyl-8-quinolinolato) aluminum (III) -μ
-Oxo-bis (2-methyl-5-trifluoromethyl-8-quinolinolato) aluminum (III) and the like.

Other host materials include Japanese Patent Application No.
Also preferred are phenylanthracene derivatives described in -110569 and tetraarylethene derivatives described in Japanese Patent Application No. 6-114456.

The light emitting layer may also serve as an electron transporting layer. In such a case, tris (8-quinolinolato)
It is preferable to use aluminum or the like. These fluorescent substances may be deposited.

The light emitting layer is preferably a mixed layer of at least one kind of hole injecting and transporting compound and at least one kind of electron injecting and transporting compound, if necessary.
Further, it is preferable that a dopant is contained in the mixed layer. The content of the compound in such a mixed layer is preferably 0.01 to 20% by weight, more preferably 0.1 to 15% by weight.

In the mixed layer, a hopping conduction path of carriers is formed, so that each carrier moves in a substance having a favorable polarity and injection of a carrier having the opposite polarity is less likely to occur, so that the organic compound is less likely to be damaged. This has the advantage that the element life is extended. Further, by including the above-described dopant in such a mixed layer, the emission wavelength characteristics of the mixed layer itself can be changed, the emission wavelength can be shifted to a longer wavelength, and the emission intensity is increased, The stability of the device can be improved.

The hole transporting compound and the electron transporting compound used in the mixed layer may be selected from the compounds for the hole transporting layer and the compounds for the electron transporting layer described later. Among them, compounds for the hole transport layer include:
It is preferable to use an amine derivative having strong fluorescence, for example, a triphenyldiamine derivative which is a hole transport material, a styrylamine derivative, or an amine derivative having an aromatic condensed ring.

As the electron transporting compound, quinoline derivatives, furthermore, metal complexes having 8-quinolinol or a derivative thereof as a ligand, particularly tris (8-quinolinolato)
It is preferable to use aluminum (Alq3). It is also preferable to use the above-mentioned phenylanthracene derivatives and tetraarylethene derivatives.

As the compound for the hole transport layer, an amine derivative having strong fluorescence, for example, a triphenyldiamine derivative which is the above-described hole transport material, a styrylamine derivative, or an amine derivative having an aromatic condensed ring is used. Is preferred.

The mixing ratio in this case depends on the respective carrier mobility and carrier concentration. In general, the weight ratio of the compound of the hole transporting compound / the compound having the electron transporting function is 1/99 to 99/99. 1, more preferably 10 /
90-90 / 10, particularly preferably 20 / 80-80 /
It is preferable to set it to about 20.

The thickness of the mixed layer is preferably not less than the thickness corresponding to one molecular layer and less than the thickness of the organic compound layer. Specifically, the thickness is preferably 1 to 85 nm, more preferably 5 to 60 nm, particularly preferably 5 to 50 nm.

As a method of forming a mixed layer, co-evaporation in which evaporation is performed from different evaporation sources is preferable. However, when the vapor pressures (evaporation temperatures) are approximately the same or very close, they are mixed in advance in the same evaporation board. Alternatively, it can be deposited. In the mixed layer, it is preferable that the compounds are uniformly mixed, but in some cases, the compounds may exist in an island shape. The light-emitting layer is generally formed to a predetermined thickness by vapor-depositing an organic fluorescent substance or by dispersing and coating the resin in a resin binder.

Particularly preferred as the light emitting layer is a mixed layer in which 8-quinolinol or a derivative thereof as a ligand is doped with an aluminum complex, and a tetraarylbendicine compound is doped with a fluorescent substance such as rubrene or coumarin. The mixing ratio is such that a doping fluorescent substance such as rubrene is added to a mixed layer in which an aluminum complex: tetraarylbendicine compound is mixed at a ratio of about 1: 1 to 0.01 to 20.
Preferable is one doped with mol%.

In addition to the inorganic hole injection layer of the present invention,
When an organic hole injecting and transporting layer is formed, the hole injecting and transporting layer may include, for example, JP-A-63-295695, JP-A-2-191694, and JP-A-3-792.
JP, JP-A-5-234681, JP-A-5-25-2
39455, JP-A-5-299174, JP-A-7-126225, JP-A-7-126226
JP, JP-A-8-100172, EP0650
Various organic compounds described in 955A1 and the like can be used. For example, a tetraarylbendicine compound (triaryldiamine or triphenyldiamine: TPD), an aromatic tertiary amine, a hydrazone derivative,
Carbazole derivatives, triazole derivatives, imidazole derivatives, oxadiazole derivatives having an amino group,
And polythiophene. These compounds may be used alone or in combination of two or more. When two or more kinds are used in combination, they may be stacked as separate layers or mixed.

A quinoline derivative such as an organometallic complex having 8-quinolinol such as tris (8-quinolinolato) aluminum (Alq ³ ) or a derivative thereof as a ligand is provided in the electron injection transport layer provided as needed. Oxadiazole derivatives, perylene derivatives, pyridine derivatives, pyrimidine derivatives, quinoxaline derivatives, diphenylquinone derivatives, nitro-substituted fluorene derivatives, and the like. The electron injection / transport layer may also serve as the light emitting layer. In such a case, it is preferable to use tris (8-quinolinolato) aluminum or the like. The electron injecting and transporting layer may be formed by vapor deposition or the like, similarly to the light emitting layer.

When the electron injecting / transporting layer is divided into an electron injecting layer and an electron transporting layer, a preferable combination is selected from the compounds for the electron injecting / transporting layer and used. Can be used in combination. At this time, it is preferable to stack the compounds in descending order of the electron affinity value from the electron injection electrode side. Such a stacking order is the same when two or more electron injection / transport layers are provided.

After forming each layer of the organic EL structure, the Si
Inorganic materials O _X such as Teflon, a protective film may be formed using an organic material such as fluorocarbon polymers containing chlorine.
The protective film may be transparent or opaque, and the thickness of the protective film is about 50 to 1200 nm. The protective film can be formed by a general sputtering method, a vapor deposition method,
It may be formed by an ECVD method or the like.

Further, it is preferable to provide a sealing plate on the device in order to prevent oxidation of the organic layer and the electrode of the device and to protect the device from mechanical damage. The sealing plate is bonded and sealed with an adhesive resin or the like in order to prevent moisture from entering. The sealing gas is preferably an inert gas such as Ar, He, and N ₂ . Further, the moisture content of the sealing gas is preferably 100 ppm or less, more preferably 10 ppm or less, and particularly preferably 1 ppm or less. Although there is no particular lower limit for the water content, it is usually about 0.1 ppm.

The material of the sealing plate is preferably a flat plate, and may be a transparent or translucent material such as glass, quartz, and resin. Glass is particularly preferred. As such a glass material, an alkali glass is preferable, and in addition, a glass composition such as soda-lime glass, lead-alkali glass, borosilicate glass, aluminosilicate glass, and silica glass is also preferable. As the plate making method, a roll-out method, a download method, a fusion method, a float method, or the like is preferable. As a surface treatment method for the glass material, a polishing treatment, a SiO ₂ barrier coat treatment, or the like is preferable. Among them, soda-lime glass produced by a float method and having no surface treatment can be used at a low cost, and is preferable. As the sealing plate, other than a glass plate, a metal plate, a plastic plate, or the like can be used.

The sealing plate may be maintained at a desired height by adjusting the height using a spacer. Examples of the material of the spacer include resin beads, silica beads, glass beads, and glass fibers, and glass beads are particularly preferable. The spacer is usually a granular material having a uniform particle size, but the shape is not particularly limited, and may be various shapes as long as it does not hinder the function as the spacer. As the size, the diameter in terms of a circle is 1 to 20 μm, more preferably 1 to 10 μm, and especially 2 to 20 μm.
8 μm is preferred. Those having such a diameter have a grain length of 10
It is preferably about 0 μm or less, and the lower limit is not particularly limited, but is usually about 1 μm.

When a recess is formed in the sealing plate,
Spacers may or may not be used. The preferred size when used is within the above range,
Particularly, the range of 2 to 8 μm is preferable.

The spacer may be mixed in the sealing adhesive in advance, or may be mixed at the time of bonding. The content of the spacer in the sealing adhesive is preferably 0.01
-30 wt%, more preferably 0.1-5 wt%.

The adhesive is not particularly limited as long as it can maintain stable adhesive strength and has good airtightness, but it is preferable to use a cationic curing type ultraviolet curing epoxy resin adhesive. .

The material of the substrate is not particularly limited, and can be appropriately determined depending on the material of the electrode of the organic EL structure to be laminated. For example, a metal material such as Al, or a transparent or transparent material such as glass, quartz or resin is used. The material may be translucent or opaque. In this case, in addition to glass, ceramics such as alumina, metal sheets such as stainless steel are subjected to insulation treatment such as surface oxidation, and thermosetting resins such as phenolic resin And a thermoplastic resin such as polycarbonate.

The emission color may be controlled by using a color filter film, a color conversion film containing a fluorescent substance, or a dielectric reflection film on the substrate.

As the color filter film, a color filter used in a liquid crystal display or the like may be used.
The characteristics of the color filter may be adjusted in accordance with the light emitted from the organic EL element to optimize the extraction efficiency and the color purity.

When a color filter capable of cutting off short-wavelength external light that is absorbed by the EL element material or the fluorescence conversion layer is used, the light resistance of the element and the display contrast are improved.

Further, an optical thin film such as a dielectric multilayer film may be used instead of the color filter.

The fluorescence conversion filter film absorbs EL light and emits light from the phosphor in the fluorescence conversion film, thereby performing color conversion of the emission color. It is formed from a fluorescent material and a light absorbing material.

As the fluorescent material, basically, a material having a high fluorescence quantum yield may be used, and it is desirable that absorption is strong in an EL emission wavelength region. In practice, laser dyes and the like are suitable, and rhodamine compounds, perylene compounds, cyanine compounds, phthalocyanine compounds (including subphthalocyanines, etc.) naphthalimide compounds, condensed ring hydrocarbon compounds, condensed heterocyclic compounds A styryl compound, a coumarin compound or the like may be used.

As the binder, a material that does not quench the fluorescence may be basically selected, and a binder that can be finely patterned by photolithography, printing, or the like is preferable. Further, a material that does not suffer damage during the formation of ITO or IZO is preferable.

The light absorbing material is used when the light absorption of the fluorescent material is insufficient, but may be omitted when unnecessary. As the light absorbing material, a material that does not quench the fluorescence of the fluorescent material may be selected.

For forming the light emitting layer and the electron injection / transport layer,
It is preferable to use a vacuum evaporation method since a uniform thin film can be formed. When a vacuum deposition method is used, a homogeneous thin film having an amorphous state or a crystal grain size of 0.1 μm or less can be obtained. If the crystal grain size exceeds 0.1 μm, the light emission becomes non-uniform, the driving voltage of the device must be increased, and the charge injection efficiency is significantly reduced.

The conditions for vacuum deposition are not particularly limited.
The degree of vacuum is 0 ^-4 Pa or less, and the deposition rate is 0.01 to 1 nm /
It is preferable to set it to about sec. Further, it is preferable to form each layer continuously in a vacuum. If they are formed continuously in a vacuum, impurities can be prevented from adsorbing at the interface between the layers, so that high characteristics can be obtained. Further, the driving voltage of the element can be reduced, and the occurrence and growth of dark spots can be suppressed.

When a plurality of compounds are contained in one layer when a vacuum evaporation method is used to form each of these layers, it is preferable to co-deposit each boat containing the compounds by individually controlling the temperature.

The organic EL element is driven by a direct current or a pulse, and the applied voltage is usually about 2 to 30 V.

[0076]

EXAMPLES Hereinafter, the present invention will be described in more detail by showing specific examples of the present invention together with comparative examples.

Example 1 An ITO transparent electrode thin film was formed to a thickness of 100 nm on a glass substrate by RF sputtering.
Patterned. The glass substrate with the ITO transparent electrode was subjected to ultrasonic cleaning using a neutral detergent, acetone and ethanol, pulled up from boiling ethanol and dried. After the surface of the transparent electrode was washed with UV / O _3, it was fixed to a substrate holder of a vacuum evaporation apparatus, and the pressure in the tank was reduced to 1 × 10 ⁻⁴ Pa or less.

Then, while maintaining the reduced pressure, the wafer was transferred to another sputtering apparatus, and an inorganic hole injection layer was formed to a thickness of 10 nm at a sputtering pressure of 0.5 Pa. At that time, Ar was used as a sputtering gas, the input power was set to RF 100 W, the formed film was mainly composed of carbon, and B, Al, Ga,
One or more elements selected from In, Tl and As, or one of compounds selected from nickel oxide, chromium oxide, ferrous oxide and molybdenum oxide
B, Al, Ga, In, Tl, and As are 0.5 to 5 at%, and nickel oxide, chromium oxide, ferrous oxide, and molybdenum oxide are each 5 to 5 types in terms of metal. The film was formed so as to contain about 50 at%.
Further, the formed film was in a state where microcrystals were mixed with amorphous.

Further, N, N, N
N ', N'-tetrakis (m-biphenyl) -1,1'
-Biphenyl-4,4'-diamine (TPD) and tris (8-quinolinolato) aluminum (Alq ³ ) in a ratio of 1: 1 were mixed with rubrene of the following structure for 5 m.
The ol% -doped one was deposited to a thickness of 40 nm at an overall deposition rate of 0.2 nm / sec to form a light emitting layer.

[0080]

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Further, the tris (8-
(Quinolinolato) aluminum (Alq ³ ) was deposited at a deposition rate of 0.2 nm / sec to a thickness of 30 nm to form an electron injection transport layer.

Next, while maintaining the reduced pressure state, Mg.A
g (weight ratio 10: 1) at a deposition rate of 0.2 nm / sec.
An organic EL element was obtained by depositing Al to a thickness of 100 nm, forming an electron injection electrode, and depositing Al to a thickness of 100 nm as a protective electrode.

Lastly, a glass sealing plate is attached, and organic E
An L element was used.

As a comparative sample, N, N'-diphenyl-N, N'-
Bis [N- (4-methylphenyl) -N-phenyl-
(4-aminophenyl)]-1,1′-biphenyl-
4,4'-diamine is deposited at a deposition rate of 0.2 nm / sec at 50 nm.
To form a hole injection layer, and tris (8-quinolinolato) aluminum (Alq ³ ) was deposited at a deposition rate of 0.2.
A comparative sample was prepared in the same manner as described above except that the layer was vapor-deposited at a thickness of 50 nm at a rate of nm / sec to form an electron injection / transport / emission layer.

When a DC voltage is applied to each organic EL element,
When the device was driven at a constant current of mA / cm ² , light emission equivalent to that of the conventional comparative sample was confirmed. In addition, generation of a leak current or a dark spot was not confirmed.

[0086]

As described above, according to the present invention, heat resistance,
It has weather resistance, can suppress the generation of leak current and dark spots, has stable physical properties, and has high mass productivity.
An organic EL device that can be reduced in cost can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a configuration example of an organic EL device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Substrate 22 Hole injection electrode 23 Inorganic hole injection layer 24 Light emitting layer 25 Electron injection layer 26 Electron injection electrode

Claims (2)

[Claims] 1. An electron injection electrode, an electron injection electrode, and at least one or more organic layers involved in at least a light emitting function between these electrodes, and between the organic layer and the hole injection electrode. An inorganic hole injecting layer, the inorganic hole injecting layer being mainly composed of carbon, and containing one or more elements selected from B, Al, Ga, In, Tl and As, and / or An organic EL device comprising one or more compounds selected from nickel, nickel oxide, chromium oxide, ferrous oxide, and molybdenum oxide. 2. The inorganic hole injecting layer has a thickness of 1 to 5
2. The organic EL device according to claim 1, which has a thickness of 0 nm.