JP2000200686A - Manufacture of organic el element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an inexpensive organic EL element having long life, higher efficiency, weather resistance and higher stability, and manufacturable without damaging an organic layer. SOLUTION: This manufacturing method of an organic EL element has an substrate 1, a pair of hole injection electrode 2 and negative electrode 3 formed on the substrate 1 and an organic layer provided between these electrodes and related at least to emitting function and includes an inorganic insulating electron injection transporting layer 6 formed of an oxide between the organic layer and the negative electrode 3. In forming film of the inorganic insulating electron injection transporting layer 6 by spattering with a gas mixture of spattering gas and nitrogen, after forming the film, and the film is formed with a gas mixture of spattering gas and oxygen to obtain the inorganic insulating electron injection transporting layer 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In general, an organic EL device comprises a transparent electrode made of ITO or the like formed on a glass substrate, an organic amine-based hole transporting layer thereon, and, for example, an Alq3 material exhibiting electron conductivity and exhibiting strong light emission. This is a basic element having a structure in which an organic light emitting layer is laminated and an electrode having a small work function such as MgAg is formed.

[0003] The element structure reported so far has a structure in which one or more organic compound layers are interposed between a hole injection electrode and an electron injection electrode. There is a two-layer structure or a three-layer structure.

[0004] Examples of the two-layer structure include a structure in which a hole transport layer and a light emitting layer are formed between a hole injection electrode and an electron injection electrode, or a light emitting layer and an electron transport layer between a hole injection electrode and an electron injection electrode. Is formed. As an example of the three-layer structure, there is a structure in which a hole transport layer, a light emitting layer, and an electron transport layer are formed between a hole injection electrode and an electron injection electrode. Also, a single-layer structure in which a single layer has all the functions has been reported for polymers and mixed systems.

FIGS. 2 and 3 show a typical structure of an organic EL device. In FIG. 2, a hole transport layer 14 and a light emitting layer 15 which are organic compounds are formed between a hole injection electrode 12 and an electron injection electrode 13 provided on a substrate 11. In this case, the light emitting layer 15 also functions as an electron transport layer. In FIG. 3, a hole transport layer 14, an emission layer 15, and an electron transport layer 16, which are organic compounds, are formed between a hole injection electrode 12 and an electron injection electrode 13 provided on a substrate 11.

In these organic EL devices, reliability is a common problem. That is, the organic EL element has a hole injection electrode and an electron injection electrode in principle, and requires an organic layer for injecting and transporting holes and electrons efficiently between these electrodes. However, these materials are susceptible to damage at the time of manufacturing, and have a problem in affinity with electrodes. Further, it is necessary to use a metal having a low work function for an electron injection electrode for electron injection. for that reason,
As a material, MgAg, AlLi, or the like must be used. However, these materials are easily oxidized and lack stability, which is a major factor that limits the life of the organic EL element and causes reliability problems. Further, there is a problem that the deterioration of the organic thin film is significantly larger than that of the LED and LD.

Further, many organic materials are relatively expensive, and there is a great merit in replacing some of the constituent films with inexpensive inorganic materials in order to provide low-cost organic EL device application products.

Further, the luminous efficiency is improved more than ever,
It is also desired to develop a device having a lower driving voltage and lower current consumption.

In order to solve such a problem, a method has been conceived which utilizes the respective advantages of the organic material and the inorganic semiconductor material. That is, an organic / inorganic semiconductor junction in which the organic hole transport layer is replaced with an inorganic p-type semiconductor. Such a study has been discussed in Japanese Patent No. 2636341, Japanese Patent Application Laid-Open No. 2-139983, Japanese Patent Application Laid-Open No. 2-207488, and Japanese Patent Application Laid-Open No. 6-119773. Element conventional organic EL
It was not possible to obtain characteristics exceeding 100.

When an electron injection layer is laminated by a sputtering method using an inorganic material, the underlying organic layer or the like (ashing layer) is ashed and damaged, and the element characteristics are deteriorated. The life of the device may be shortened. In order to prevent such damage, a so-called reverse stacked structure in which an electron injection layer is formed before an organic layer is also conceivable, but the element configuration and the configuration as a display are limited, and the application range of the organic EL element is limited. It will be limited.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a device which can be manufactured without damaging the organic layer, has a long life, is highly efficient, has weather resistance, has high stability, and An object of the present invention is to realize a method for manufacturing an inexpensive organic EL element.

[0012]

The above object is achieved by the following constitution. (1) It has a substrate, a pair of hole injection electrodes and a negative electrode formed on the substrate, and an organic layer provided at least between the electrodes and involved in a light emitting function. Is a method for manufacturing an organic EL device having an inorganic insulating electron injecting and transporting layer formed of an oxide, wherein the inorganic insulating electron injecting and transporting layer is formed by sputtering. EL to obtain an inorganic insulating electron injecting and transporting layer by forming a film with a mixed gas of a sputtering gas and a nitrogen gas
Device manufacturing method. (2) The organic E according to (1) above, wherein the mixing ratio of the sputtering gas and the nitrogen gas (N ₂ ) is 50:50 to 90: 5.
Manufacturing method of L element. (3) The inorganic insulating electron injecting and transporting layer is selected from the group consisting of lithium oxide, rubidium oxide, potassium oxide, sodium oxide, cesium oxide, strontium oxide, magnesium oxide, and calcium oxide as main components.
The method for producing an organic EL device according to the above (1) or (2), comprising at least one kind of oxide. (4) The organic EL according to any one of (1) to (3), wherein the inorganic insulating electron injecting and transporting layer further contains silicon oxide and / or germanium oxide as a stabilizer.
Device manufacturing method. (5) The cathode is made of Al, Ag, In, Ti, Cu,
The method for manufacturing an organic EL device according to any one of (1) to (4), wherein the organic EL device is formed of one or more metal elements selected from Au, Mo, W, Pt, Pd, and Ni. (6) The thickness of the inorganic insulating electron injecting and transporting layer is set to 0.1.
Organic E according to any of (1) to (5) above,
L element manufacturing method.

[0013]

DETAILED DESCRIPTION OF THE INVENTION A method of manufacturing an organic EL device according to the present invention comprises a substrate, a pair of hole injection electrodes and a negative electrode formed on the substrate, and at least a light emitting function provided between these electrodes. A method for manufacturing an organic EL device having an organic layer involved, and an inorganic insulating electron injecting and transporting layer formed of an oxide between the organic layer and the cathode. When forming a conductive electron injection transport layer,
The inorganic insulating electron injecting and transporting layer is obtained by forming a film with a mixed gas of a sputtering gas and a nitrogen gas.

By arranging the inorganic insulating electron injecting and transporting layer made of an inorganic material as described above, an organic EL device having both the advantages of an inorganic material and the advantages of an organic material can be obtained. That is, the physical properties at the interface between the light emitting layer and the inorganic insulating electron injecting and transporting layer are stabilized, and the production becomes easy. At this time, by forming the inorganic insulating electron injecting and transporting layer with a mixed gas of a sputtering gas and a nitrogen gas, damage to the organic layer due to ashing or the like can be prevented. In addition, luminance equal to or higher than that of a device having a conventional organic electron injection layer can be obtained, and furthermore, the heat resistance and the weather resistance are high, so that the life is longer than that of the conventional device, and the occurrence of leaks and dark spots is reduced. In addition, since an inexpensive and easily available inorganic material is used instead of a relatively expensive organic substance, the production becomes easy and the production cost can be reduced.

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

Since the inorganic insulating electron injecting / transporting layer has a constitution in which a stabilizer is added to the main component, it is not necessary to form an electrode having a special electron injecting function, and the stability is relatively high. Can be used. Then, the electron injection transport efficiency of the inorganic insulating electron injection transport layer is improved, and the life of the device is extended.

The inorganic insulating electron injection layer is formed by a sputtering method. The pressure of the sputtering gas during sputtering is 0.1 to
A range of 1 Pa is preferred. The sputtering gas is an inert gas used in a normal sputtering apparatus, for example, Ar, Ne, X
e, Kr, etc. can be used. Then, a predetermined amount of N ₂
To be used. As the target, any of the above oxides may be used, and single or multiple sputtering may be performed. Note that the target is usually a mixed target containing the above main component and a stabilizer. In this case, the composition of the formed film is substantially the same as that of the target, or a composition in which oxygen is slightly lower and nitrogen is mixed. That is, nitrogen is mixed into the inorganic insulating electron injecting and transporting layer so as to compensate for oxygen deficiency.

As described above, by forming a film with the mixed gas containing nitrogen, it is possible to prevent the ashing phenomenon of the organic layer and to prevent the inorganic electron injection layer from being in a state of insufficient oxygen to deteriorate the hole trapping property. can do. In addition, the luminous efficiency of the device can be improved, and the life of the device can be significantly improved.

The mixing ratio between the nitrogen gas and the sputtering gas is 5
0:50 to 90: 5 is preferred, and especially 50:50 to 8
A range of 0:20 is preferred.

As the sputtering method, a high-frequency sputtering method using an RF power source, a DC sputtering method, or the like can be used, but RF sputtering is particularly preferred. The power of the sputtering apparatus is preferably in the range of 0.1 to 10 W / cm ² by RF sputtering, and the film formation rate is 0.1 to 50 nm / min.
Particularly, the range of 1 to 10 nm / min is preferable.

Further, the oxygen-nitrogen amount may change continuously in the film thickness direction.

The substrate temperature during film formation is room temperature (25
C) to about 150C.

The inorganic insulating electron injecting / transporting layer comprises lithium oxide (Li ₂ O) and rubidium oxide (Rb
₂ O), potassium oxide (K ₂ O), sodium oxide (Na
₂ O), cesium oxide (Cs ₂ O), strontium oxide (SrO), magnesium oxide (MgO), and calcium oxide (CaO). These may be used alone or as a mixture of two or more, and the mixing ratio when two or more are used is arbitrary. Of these, strontium oxide is most preferred, followed by magnesium oxide, calcium oxide, and then lithium oxide (Li ₂ O).
Then rubidium oxide (Rb ₂ O), followed by potassium oxide (K ₂ O), and sodium oxide (Na ₂ O) is preferred. When these are used as a mixture, it is preferable that strontium oxide is contained in an amount of 40 mol% or more, or lithium oxide and rubidium oxide in a total amount of 40 mol% or more, particularly 50 mol% or more.

The inorganic insulating electron injecting and transporting layer preferably contains silicon oxide (SiO ₂ ) and / or germanium oxide (GeO ₂ ) as a stabilizer. Either of these may be used, or both may be mixed and used, and the mixing ratio at that time is arbitrary.

Each of the above-mentioned oxides usually exists in a stoichiometric composition, but deviates somewhat from this, and a non-stoichiometric composition is obtained.
y).

The inorganic insulating electron injecting and transporting layer according to the present invention is preferably such that each of the above-mentioned components is Sr
O, MgO, CaO, Li ₂ O, Rb ₂ O, K ₂ O, Na ₂
In terms of O, Cs ₂ O, SiO ₂ and GeO ₂ , the main components are:
80-99 mol%, more preferably 90-95 mol%,
Stabilizer: 1-20 mol%, more preferably 5-10
mol%.

The thickness of the inorganic insulating electron injecting and transporting layer is preferably from 0.1 to 2 nm, more preferably from 0.3 to 2 nm.
0.8 nm.

A negative electrode is provided on the inorganic electron injection layer (on the side opposite to the light emitting layer). The negative electrode does not need to have a low work function and has an electron injecting property, and thus is not particularly limited, and a normal metal can be used. Among them, Al, Ag, In, T in terms of conductivity and ease of handling.
One, two or more metal elements selected from i, Cu, Au, Mo, W, Pt, Pd and Ni, particularly Al and Ag are preferable.

In the organic EL device of the present invention, in combination with the above-mentioned inorganic insulating electron injecting and transporting layer, it is preferable to use the above-mentioned metal element as the negative electrode, but if necessary, the following may be used. For example, K, Li, Na,
Mg, La, Ce, Ca, Sr, Ba, Sn, Zn, Z
metal element such as r, or a binary or ternary alloy system containing them to improve stability, for example, Ag · M
g (Ag: 0.1 to 50 at%), Al.Li (Li:
0.01-14 at%), In.Mg (Mg: 50-80)
at%), Al.Ca (Ca: 0.01 to 20 at%) and the like.

The thickness of the negative electrode thin film may be a certain thickness or more capable of providing electrons to the inorganic insulating electron injecting and transporting layer, and may be 50 nm or more, preferably 100 nm or more. Although the upper limit is not particularly limited, the film thickness may be generally about 50 to 500 nm.

The material for the hole injection electrode is preferably a material capable of efficiently injecting holes into the hole injection layer.
Materials with a work function of 4.5 eV to 5.5 eV are preferred. Specifically, tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO), indium oxide (In ₂ O ₃₎
), Tin oxide (SnO ₂ ) and zinc oxide (ZnO)
It is preferable to use any one of the above as the main composition. These oxides may deviate somewhat from their stoichiometric composition.
The mixing ratio of SnO ₂ to In ₂ O ₃ is 1 to 20 wt.
%, More preferably 5 to 12% by weight. The mixing ratio of ZnO ₂ to In ₂ O ₃ in IZO is usually 12
About 32% by weight.

The hole injection electrode may contain silicon oxide (SiO ₂ ) to adjust the work function.
The content of silicon oxide (SiO ₂ ) is preferably about 0.5 to 10% by mol ratio of SiO _{2 to} ITO. S
The inclusion of iO ₂ increases the work function of ITO.

The electrode on the light extraction side has an emission wavelength band,
The light transmittance is usually 400 to 700 nm, particularly preferably 50% or more, particularly 60% or more for each emitted light.
When the transmittance is low, the light emission from the light emitting layer itself is attenuated, and it becomes difficult to obtain the luminance required for the light emitting element.

The thickness of the electrode is 50 to 500 nm, especially 50
The range of -300 nm is preferred. The upper limit is not particularly limited. However, if the thickness is too large, there is a fear that the transmittance is reduced or the layer is peeled off. If the thickness is too small, a sufficient effect cannot be obtained, and there is a problem in film strength at the time of production and the like.

As shown in FIG. 1, for example, the organic EL device of the present invention comprises a substrate 1, a hole injection electrode 2, a hole injection transport layer 4, a light emitting layer 5, an inorganic insulating electron injection transport layer 6, and a negative electrode 3. Are sequentially laminated. In FIG. 1, a driving power source E is connected between the hole injection electrode 2 and the negative electrode 3. The light emitting layer 5 represents a light emitting layer in a broad sense, and includes an electron transport layer, a hole injection / transport layer, a light emitting layer in a narrow sense, and the like.

In the above device, the light emitting layers may be stacked in multiple stages. With such an element structure, it is possible to adjust the color tone of the emitted light and to increase the number of colors.

The light emitting layer is composed of a laminated film of at least one kind or two or more kinds of organic compound thin films involved in the light emitting function.

The light emitting layer has a function of injecting holes (holes) and electrons, a function of transporting them, and a function of generating excitons by recombination of holes and electrons. By using a relatively electronically neutral compound for the light emitting layer, electrons and holes can be easily injected and transported in a well-balanced manner.

The light emitting layer may have a hole injection / transport layer, an electron transport layer, etc. in addition to the light emitting layer in a narrow sense, if necessary.

The hole injecting and transporting layer has a function of facilitating the injection of holes from the hole injecting electrode, a function of stably transporting holes, and a function of preventing electrons.
The electron transport layer provided as needed has a function of facilitating the injection of electrons from the inorganic insulating electron injection / transport layer, a function of stably transporting electrons, and a function of preventing holes. These layers increase and confine holes and electrons injected into the light-emitting layer, optimize the recombination region,
Improve luminous efficiency. Note that usually, an organic electron transport layer is not provided. In addition, the hole injection transport layer is made of silicon oxide,
It may be formed using an oxide of germanium oxide with a reduced oxygen amount.

The thickness of the light emitting layer, the thickness of the hole injecting and transporting layer, and the thickness of the electron transporting layer are not particularly limited and vary depending on the forming method, but are usually about 5 to 500 nm, especially 10 to 300 nm. It is preferable that

The thickness of the hole injection / transport layer and the thickness of the electron transport layer depend on the design of the recombination / light emitting region, but may be about the same as the thickness of the light emitting layer or about 1/10 to 10 times. When the hole injection layer and the transport layer are separated from each other, the thickness of the injection layer is preferably 1 nm or more, and the thickness of the transport layer is preferably 1 nm or more. 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
Quinolinol derivatives such as metal complex dyes having 8-quinolinol or a derivative thereof as a ligand, such as (quinolinolato) aluminum; tetraphenylbutadiene, anthracene, perylene, coronene, and 12-phthaloperinone derivatives. Further, phenylanthracene derivatives described in JP-A-8-12600 (Japanese Patent Application No. 6-110569), tetraarylethene derivatives described in JP-A-8-12969 (Japanese Patent Application No. 6-114456), and the like are described. 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 10% by weight, and more preferably 0.1 to 10% by weight.
It is preferably 1 to 5% 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].

Further, in addition to 8-quinolinol or a derivative thereof, 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 are disclosed in
Phenylanthracene derivative described in JP-A-12600 (Japanese Patent Application No. 6-110569) and JP-A-8-1296
No. 9 (Japanese Patent Application No. 6-114456) is also preferable.

The light emitting layer may serve also 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 carrier hopping conduction path is formed, so that each carrier moves in a material having a favorable polarity, and carrier injection of 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 injecting and transporting compound and the electron injecting and transporting compound used in the mixed layer may be selected from the hole injecting and transporting compound and the electron injecting and transporting compound described below, respectively. Among them, as the hole injecting and transporting compound, it is preferable to use an amine derivative having strong fluorescence, for example, a triphenyldiamine derivative which is a hole transporting compound, further a styrylamine derivative, and an amine derivative having an aromatic condensed ring. .

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

Examples of the compound for the hole injecting and transporting layer include amine derivatives having strong fluorescence, for example, the above-mentioned hole transporting compounds such as triphenyldiamine derivatives, styrylamine derivatives, and amine derivatives having an aromatic condensed ring. It is preferably used.

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 injecting and transporting compound / the compound having the electron injecting and transporting function is 1/99 to less. 99/1, more preferably 10/90 to 90/10, particularly preferably 20/80
It is preferable to set it to about 80/20.

The thickness of the mixed layer is preferably not less than the thickness of one molecular layer and less than the thickness of the organic compound layer. Specifically, it is preferably 10 to 150 nm, more preferably 50 to 100 nm.

As a method for forming the 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.

The hole injecting / transporting compound is disclosed in, for example, JP-A-63-295695 and JP-A-2-19.
1694, JP-A-3-792, JP-A5-
JP-A-234681, JP-A-5-239455,
JP-A-5-299174, JP-A-7-12622
No. 5, JP-A-7-126226, JP-A-8-
Various organic compounds described in, for example, Japanese Patent No. 100172 and EP0650955A1 can be used. For example, a tetraarylbendicine compound (triaryldiamine or triphenyldiamine: TPD), an aromatic tertiary amine, a hydrazone derivative, a carbazole derivative,
Triazole derivatives, imidazole derivatives, oxadiazole derivatives having an amino group, polythiophene and the like. 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.

The electron transporting layer provided as necessary includes:
Tris (8-quinolinolato) aluminum (Alq3)
Quinoline derivatives such as organometallic complexes having 8-quinolinol or a derivative thereof as a ligand, oxadiazole derivatives, perylene derivatives, pyridine derivatives, pyrimidine derivatives, quinoxaline derivatives, diphenylquinone derivatives, nitro-substituted fluorene derivatives, etc. be able to. The electron transport layer may also serve as a light emitting layer,
In such a case, it is preferable to use tris (8-quinolinolato) aluminum or the like. The electron transport layer may be formed by vapor deposition or the like, similarly to the light emitting layer. Although the electron transport layer of this organic material is not usually required, it may be provided depending on the structure of the device and other conditions.

For forming the hole injecting and transporting layer, the light emitting layer and the electron transporting layer made of an organic material, it is preferable to use a vacuum evaporation method since a uniform thin film can be formed. When the vacuum deposition method is used, the amorphous state or the crystal grain size is 0.1 mm.
A homogeneous thin film of 2 μm or less can be obtained. 0.2 grain size
When the thickness exceeds μm, the light emission becomes non-uniform, the driving voltage of the device must be increased, and the hole 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.

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

Further, in order to prevent oxidation of the organic layers and electrodes of the device, it is preferable to seal the device with a sealing plate or the like. The sealing plate adheres and seals the sealing plate using an adhesive resin layer in order to prevent moisture from entering. The sealing gas is A
An inert gas such as r, He, N ₂ or the like is preferable. 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, resin, etc., and glass is particularly preferred. As such a glass material, an alkali glass is preferable from the viewpoint of cost, and in addition, a glass composition such as soda lime glass, lead alkali glass, borosilicate glass, aluminosilicate glass, and silica glass is also preferable. In particular, soda glass, a glass material without surface treatment can be used at low cost,
preferable. As the sealing plate, other than a glass plate, a metal plate, a plastic plate, or the like can be used.

The height of the sealing plate may be adjusted to a desired height by 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 the same as or larger than the diameter.

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. .

In the present invention, the substrate on which the organic EL structure is formed is an amorphous substrate such as glass or quartz, or a crystalline substrate such as Si, GaAs, ZnSe, or Z.
Examples include nS, GaP, and InP, and a substrate in which a crystalline, amorphous, or metal buffer layer is formed on these crystalline substrates can also be used. As the metal substrate, Mo, Al, Pt, Ir, Au, Pd, or the like can be used, and a glass substrate is preferably used. Since the substrate is usually on the light extraction side, it is preferable that the substrate has the same light transmittance as the above-mentioned electrodes.

Further, a large number of the elements of the present invention may be arranged on a plane. By changing the emission color of each element arranged on a plane, a color display can be obtained.

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 fluorescent conversion layer is used, the light resistance of the element and the contrast of display are improved.

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

The fluorescent conversion filter film absorbs EL light and emits light from the phosphor in the fluorescent conversion film to convert the color of the emitted light. 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 the fluorescent material has strong absorption in the 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.) naphthaloimide 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, in the case of being formed on the substrate in contact with the hole injection electrode, a material which is not damaged when forming the hole injection electrode (ITO, IZO, or the like) 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.

The organic EL device of the present invention is generally used as a DC-driven or pulse-driven EL device, but it can also be driven by an AC device. The applied voltage is usually 2 to 30
V.

[0081]

EXAMPLES Hereinafter, the present invention will be described in more detail by showing specific examples of the present invention. <Example 1> Corning product name 7 as a glass substrate
The 059 substrate was scrub-cleaned using a neutral detergent. Next, this substrate is fixed to a substrate holder of a sputtering apparatus,
An ITO hole injection electrode layer was formed by a DC magnetron sputtering method using an ITO oxide target.

The substrate on which the ITO film had been formed was subjected to ultrasonic cleaning using a neutral detergent, acetone and ethanol, pulled up from boiling ethanol and dried. Then, the surface is UV /
After washing with 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.

Next, polythiophene is deposited to a thickness of 10 nm at a deposition rate of 0.1 nm / sec to form a hole injection layer, and TPD is deposited to a thickness of 20 nm at a deposition rate of 0.1 nm / sec. Thus, a hole transport layer was formed.

While maintaining the reduced pressure, N, N, N ', N'-
Tetrakis (m-biphenyl) -1,1'-biphenyl-4,4'-diamine (TPD), tris (8-quinolinolato) aluminum (Alq3) and rubrene were deposited at an overall deposition rate of 0.2 nm / sec. Was deposited to a thickness of 40 nm to form a light emitting layer. TPD: Alq ³ = 1: 1 (weight ratio), and this mixture was doped with rubrene at 0.5 mol%.

Further, while maintaining the reduced pressure, the wafer was transferred to a sputtering apparatus, and strontium oxide (SrO), lithium oxide (Li ₂ O), and silicon oxide (SiO ₂ ) were used as raw materials.
Was mixed with SrO: 80 mol% Li ₂ O: 10 mol% SiO ₂ : 10 mol% with respect to all the components, and the inorganic insulating electron injection / transport layer was formed to a thickness of 0.8 nm. Was formed. The film forming conditions at this time include a substrate temperature of 25 ° C., a sputtering gas Ar,
Film formation rate 1 nm / min, operating pressure 0.5 Pa, input power 5
W / cm ² . At this time, the sputtering gas is Ar / N
_The inorganic insulative electron injecting and transporting layer was formed to a thickness of 0.8 nm while supplying 100 SCCM at ₂ : 1.

Further, while maintaining the reduced pressure, Al
A negative electrode was formed by vapor deposition to a thickness of nm.

Finally, glass sealing was performed to obtain an organic EL device (normal stack). Instead of the inorganic insulating electron injecting and transporting layer, tris (8-quinolinolato) aluminum (Alq3) was deposited at a deposition rate of 0.2 nm / sec by vapor deposition.
An electron injecting and transporting layer is formed by vapor deposition to a thickness of 0 nm, and MgAg (weight ratio: 10: 1) is vapor deposited to a thickness of 200 nm at a vapor deposition rate of 0.2 nm / sec while maintaining a reduced pressure. An organic EL device was prepared in the same manner as above except that the electrode was used, and used as a comparative sample.

When an electric field was applied to the obtained organic EL device in air, the device showed diode characteristics. When the ITO side was biased to the plus side and the Al side was biased to the minus side, the current was:
The voltage increased with an increase in the voltage, and a clear light emission was observed in a normal room when observed from the sealing plate side. Further, even when the light emitting operation was repeatedly performed, no decrease in luminance was observed.

Next, as an acceleration test, the light emission luminance and life characteristics were examined at a constant current of 100 mA / cm ² . The emission luminance was improved by about 10% as compared with a completely similar comparative sample except that the conventional organic material was used as the electron injecting and transporting layer. The luminance of the comparative sample was reduced by half in 300 hours, whereas the luminance of the sample of the present invention was reduced by 500 hours or more.

<Example 2> In Example 1, the main component and the stabilizer of the inorganic insulating electron injecting and transporting layer were changed to Sr, respectively.
From O to MgO, CaO, or a mixed oxide thereof,
From Li ₂ O to K ₂ O, Rb ₂ O, K ₂ O, Na ₂ O, Cs
GeO from SiO ₂ to ₂ O or mixed oxides thereof
_2, or SiO ₂ and substantially the same results was instead mixed oxides of GeO ₂ were obtained. Further, the material of the negative electrode is changed from Al to Ag, In, Ti, Cu, Au, Mo,
The same applies to W, Pt, Pd, Ni, or alloys thereof. Further, the mixing ratio of Ar: N ₂ is set to 50: 50-
The same was true even when the sputtering gas was changed in the range of 90: 5, and the same was true when the sputtering gas was changed from Ar to Ne, Xe, and Kr.

[0091]

As described above, according to the present invention, an element can be manufactured without damaging the organic layer.
A long-life, high-efficiency, weather-resistant, highly stable, and inexpensive method for manufacturing an organic EL device can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a configuration example of an organic EL device of the present invention.

FIG. 2 is a schematic sectional view showing a configuration example of a conventional organic EL element.

FIG. 3 is a schematic sectional view showing another configuration example of a conventional organic EL element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Hole injection electrode 3 Negative electrode 4 Hole injection transport layer 5 Light emitting layer 6 Inorganic insulating electron injection transport layer

Claims (6)

[Claims] 1. A semiconductor device comprising: a substrate; a pair of a hole injection electrode and a cathode formed on the substrate; and an organic layer provided at least between the electrodes and involved in a light emitting function. A method for manufacturing an organic EL device having an inorganic insulating electron injecting and transporting layer formed of an oxide between a cathode and a cathode, wherein the inorganic insulating electron injecting and transporting layer is formed by sputtering. In this case, a method for manufacturing an organic EL device in which an inorganic insulating electron injecting and transporting layer is obtained by forming a film with a mixed gas of a sputtering gas and a nitrogen gas (N ₂ ). 2. The method according to claim 1, wherein the mixing ratio of the sputtering gas and the nitrogen gas is 50:50 to 90: 5. 3. The inorganic insulative electron injecting and transporting layer comprises at least one selected from the group consisting of lithium oxide, rubidium oxide, potassium oxide, sodium oxide, cesium oxide, strontium oxide, magnesium oxide, and calcium oxide. 3. An oxide containing an oxide.
A method for manufacturing an organic EL device. 4. The organic EL according to claim 1, wherein the inorganic insulating electron injection / transport layer further contains silicon oxide and / or germanium oxide as a stabilizer.
Device manufacturing method. 5. The cathode according to claim 1, wherein the cathode comprises Al, Ag, In, Ti,
The method for manufacturing an organic EL device according to any one of claims 1 to 4, wherein the organic EL device is formed of one or more metal elements selected from Cu, Au, Mo, W, Pt, Pd, and Ni. 6. The method according to claim 1, wherein the thickness of the inorganic insulating electron injection / transport layer is 0.1 to 2 nm.