JPH11339967A - Organic el element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heat resistance and weather resistance, to reduce a leak and a dark spot and to improve productivity by providing an organic layer related to a luminescent function between a pair of electrodes formed on a substrate, and providing an insulating layer between the organic layer and one electrode. SOLUTION: A first electrode 2, an insulating layer 3, an organic layer 4 and a second electrode 5 are laminated in sequence on a substrate 1 to form an organic EL element. When an AC voltage is applied between the electrodes 2, 5, holes and electrodes are injected into the organic layer 4 by polarization of the insulating layer 3 and recombined for luminescent. Two or more luminescence layers may be laminated. A layer having a hole injection transport material or a layer having an electron injection transport material may be provided in the organic layer 4. A first electrode 2, organic layer 4, insulating layer 3 and a second electrode 5 may be laminated in sequence on the substrate 1. The organic layer 4 participates in a luminescent function and has a function for generating stimulater via the transport of holes and electrons and the recombination of holes and electrons.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic EL device, and more particularly, to an AC driven organic EL device.

[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) -1,1'-biphenyl-
When a layer of a tetraarylenediamine derivative such as 4,4′-diamine is formed directly on the ITO transparent electrode, 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 about 80 ° C. and insufficient heat resistance. .

An electron injection transport layer is also provided between the light emitting layer and the electron injection electrode to obtain an electron injection effect and to improve the adhesion between the two. A quinoline derivative or the like is used for the electron injection transport layer.

The organic EL element is used under a high electric field intensity in practical use and cannot escape heat generation. Therefore, the above-mentioned 4,4 ′, 4 ″ -tris (−)
N-(-3-methylphenyl) -N-phenylamino)
The heat resistance of organic materials such as triphenylamine is serious, and this causes a problem that the light emission lifetime is not sufficient.

If these organic materials deteriorate with time or the physical properties at the interface deteriorate, erroneous light emission due to leak current may occur or a non-light emitting region called a dark spot may occur. And display quality is significantly impaired.

Further, 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.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide an organic EL device which has high heat resistance and weather resistance, has little occurrence of leaks and dark spots, has high mass productivity, and can be manufactured at low cost. It is.

[0012]

The above object is achieved by the following constitution. (1) On a substrate, a pair of electrodes and at least one or more organic layers involved in at least a light emitting function are provided between the electrodes, and between the organic layer and one of the electrodes. And an organic EL device having an insulating layer. (2) The organic EL device according to (1), wherein at least one of the electrodes is tin-doped indium oxide or zinc-doped indium oxide. (3) The organic EL device according to (1) or (2), wherein the thickness of the insulating layer is 2 to 50 nm. (4) the insulating layer is one of silicon oxide, silicon nitride, lead oxide, aluminum oxide, titanium oxide, zirconium oxide, hafnium oxide, niobium oxide, tantalum oxide, lithium oxide, calcium oxide, strontium oxide, and barium oxide; The organic EL device according to any one of the above (1) to (3), comprising at least two types. (5) The organic EL device according to any one of (1) to (4), which is driven by an alternating current. (6) The organic EL according to any one of (1) to (5) above, wherein the organic layer has a layer containing an aluminum complex having 8-quinolinol or a derivative thereof as a ligand, a tetraarylbendicine compound, and rubrene. element.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The organic EL device of the present invention has a pair of electrodes on a substrate, and one or more organic layers involved in at least a light emitting function between these electrodes. An insulating layer is provided between the layer and the electrode on either side.

The electrode, the organic layer, and the insulating layer therebetween function as a capacitor, and when a voltage is applied to the electrode, dielectric polarization occurs. Therefore, by setting this to an AC voltage, electrons and holes are injected into the organic layer, and the holes and electrons are recombined in the light emitting layer to emit light. The insulating layer may be a dielectric.

Usually, an organic EL device has an organic layer such as a hole injection layer and an electron injection layer in addition to the light emitting layer. By providing an insulating layer using an inorganic material instead of providing them, heat resistance is improved, and an organic layer is sandwiched by an oxide film or the like, so that weather resistance is improved and the life of the element can be extended. 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. Furthermore,
The connectivity with the electrodes is also improved. Therefore, the occurrence of leaks and the occurrence of dark spots are small.

The thickness of the insulating layer can serve as a capacitor, and is not particularly limited as long as sufficient light emission can be obtained. Specifically, although it differs depending on the forming material, it is usually preferably 2 to 50 nm, particularly preferably 10 to 20 nm. If the thickness is smaller than this, a sufficient effect cannot be obtained. If the thickness is larger than this, sufficient light emission cannot be obtained.

Materials constituting the insulating layer include silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), lead oxide (PbO, PbO ₂ ), and aluminum oxide (Al ₂ O).
₃ ), titanium oxide (TiO ₂ ), zirconium oxide (Z
rO ₂ ), hafnium oxide (HfO ₂ ), niobium oxide (N
b ₂ O _5), tantalum oxide (Ta ₂ O _5), lithium oxide (Li ₂ O), calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO) are preferred. Further, these composite oxides, for example, barium titanate (BaTiO ₃ ), lithium niobate (LiNb)
O _3), lead zirconate (PbZrO _3), PZT-based material (Pb (TiZr) O ₃₎ or the like. These materials usually exist in the stoichiometric composition, but the O amount and the N amount may be slightly deviated. These 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. Note that the compositions of the two insulating layers may be different.

The dielectric constant of the insulating layer is preferably from 1 to 200. If the dielectric constant is smaller than this, a sufficient effect cannot be obtained.

When the insulating layer is formed on the light extraction side, the light transmittance is preferably 80% or more, particularly 90% or more for the emission wavelength band, usually 400 to 700 nm, particularly for each emitted light. When the emitted light is extracted through the insulating layer, if the transmittance is reduced, the emission itself from the light emitting layer is attenuated, and the luminance required for the light emitting element tends not to be obtained.

Since the insulating layer, which is a dielectric material, is formed between the organic layer and one of the electrodes, when AC driving is performed, the insulating layer is formed on the side where the insulating layer is formed.
The phase of the injected electrons or holes may be inverted or rotated. In this case, the phase rotation originates in the capacitor formed by the insulating layer. Therefore,
A circuit factor that cancels this out in the drive circuit, for example, an inductor component is provided, or a similar capacitor component (such as a phase compensation capacitor) is provided on the electrode having no insulating layer.
May be provided.

It is preferable that the driving frequency is set sufficiently high to reduce the influence of the capacitor (the effect of the phase). The organic EL device of the present invention is driven by an alternating current. Usually, the applied voltage is about 20 to 100 V, and the operating frequency is preferably 100 Hz or more, particularly preferably about 1 k to 10 MHz. Alternatively, similar pulse driving may be used. At this time, either constant current drive or constant voltage drive may be used.

The electrode on the side from which light is not extracted may be any conductive material, for example, Al, Ti, Ta, K,
Li, Na, Mg, La, Ce, Ca, Sr, Ba, A
g, In, Sn, Zn, Zr, and the like, or a binary or ternary alloy system containing them. Among them, Al or an Al alloy is preferable. As the Al alloy, Al and Sc, Nb, Zr, Hf, Nd, Ta, C
alloys with transition elements such as u, Si, Cr, Mo, Mn, Ni, Pd, Pt and W. When an Al alloy is used, an alloy of Al and one or more transition elements is preferable. In this case, the Al content is preferably 90 at% or more, particularly preferably 95 at% or more.

The electrode on the light extraction side is preferably a transparent or translucent electrode. Examples of the transparent electrode include ITO (tin-doped indium oxide), IZO (zinc-doped indium oxide), ZnO, SnO ₂ , In ₂ O _3, etc. In particular, ITO (tin-doped indium oxide) and IZO (zinc-doped indium oxide) Is preferred. ITO is usually In
_{Although 2} O ₃ and SnO are contained in a stoichiometric composition, the amount of O may slightly deviate from this. The mixing ratio of SnO ₂ to In ₂ O ₃ is 1 to 20% by weight, more preferably 5 to 12%.
wt% is preferred. The mixing ratio of ZnO ₂ to In ₂ O ₃ in IZO is usually about 12 to 32 wt%. In addition, both electrodes may be configured as the above-mentioned transparent electrodes to extract light from both surfaces.

The electrode on the light extraction side has an emission wavelength band,
The light transmittance is usually 400 to 700 nm, particularly preferably 80% or more, particularly 90% or more for each emitted light.
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 electrode is 50-500 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.

The insulating layer can be formed by CVD, PVD, or the like. In the PVD method, a sputtering method is preferable, and among them, an RF sputtering method is preferable.

When the insulating layer is formed by a vapor deposition method, the conditions for vacuum vapor deposition are not particularly limited, but it is preferable that the degree of vacuum be 10 ^-4 Pa or less and the vapor deposition rate be about 0.01 to 1 nm / sec. In addition, organic E containing an organic layer continuously in vacuum
It is preferable to form each layer of the L structure. 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.

When the insulating layer is formed by a sputtering method, an inert gas used in a usual sputtering apparatus can be used as a sputtering gas. Among them, it is preferable to use any of Ar, Kr, and Xe, or a mixed gas containing at least one of these gases.

When any of Ar, Kr, and Xe is used as the main sputtering gas, the product of the distance between the substrate targets is 20 to 60 Pa · cm, particularly 30 to 50 Pa · cm.
Is preferable. Under these conditions, a preferable result can be obtained by using any sputtering gas, but it is particularly preferable to use Ar.

In order to compensate for oxygen deficiency, an oxygen gas such as O ₂ may be mixed and used in addition to the sputtering gas. The partial pressure of the oxygen gas is 0.1 to 100 with respect to the sputtering gas.
% May be introduced. The substrate temperature,
Even if oxygen gas is introduced under the same partial pressure conditions depending on the film forming conditions such as sputtering gas pressure, target, distance between substrates, input power, etc., the amount of oxygen taken in the barrier layer varies, The optimal partial pressure may be adjusted as needed.

As a sputtering method, it is preferable to use an RF sputtering method. The power of the RF sputtering device is 1 to 1
A range of 0 W / cm ² is preferred. Frequency is 1-100MHz
Is preferred. The deposition rate is 5 to 100 nm / min, especially 5
The range is preferably from 50 to 50 nm / min. Operating pressure is 0.1 ~
A range of 1 Pa is preferred.

The electrode 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.

A target having the same composition as the electrode is usually used. The pressure of the sputtering gas during sputtering is preferably in the range of 0.1 to 5 Pa, more preferably 0.1 to 1 Pa.

As the sputtering gas, an inert gas used in a usual sputtering apparatus can be used. Above all, Ar, K
r or Xe, or at least one of these
It is preferable to use a mixed gas containing at least one kind of gas.
These are preferred because they are inert gases and have a relatively large atomic weight.

As a sputtering method, a high-frequency sputtering method using an RF power source or the like is possible, but it is preferable to use a DC sputtering method, which can easily control a film formation rate. DC
The power of the sputtering apparatus is preferably 0.1 to 10
W / cm ^2, in particular in the range of 0.5~7W / cm ^2. Also,
The deposition rate is 0.1 to 100 nm / min, especially 1 to 30 nm
/ Min is preferred.

When the above-mentioned electrode is formed by a vapor deposition method, the conditions for vacuum vapor deposition are not particularly limited, but it is preferable that the degree of vacuum be 10 ^-4 Pa or less and the vapor deposition rate be about 0.01 to 1 nm / 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.

FIG. 1 shows a structural example of the organic EL device of the present invention. In FIG. 1, the organic EL device of the present invention has a first electrode 2, an insulating layer 3, an organic layer 4, and a second electrode 5 on a substrate 1 in that order. When an AC voltage is applied to the substrate, holes and electrons are injected into the organic layer due to the polarization action of the insulating layer 3 and recombine to emit light. Two or more light emitting layers may be stacked. Further, a layer having a hole injecting and transporting material or a layer having an electron injecting and transporting material may be provided in the organic layer.

As shown in FIG. 2, the organic E of the present invention
The L element has a first electrode 2, an organic layer 4,
A configuration in which the insulating layer 3 and the second electrode 5 are sequentially provided may be employed.

The organic layer of the present invention is involved in the light emitting function, has the function of transporting holes (holes) and electrons, and the function of generating excitons by recombination of holes and electrons. It is preferable to use a relatively electronically neutral compound for the organic layer, that is, the light emitting layer.

The thickness of the light emitting layer is not particularly limited and varies depending on the forming method.
It is preferable that the thickness be in the range of 10 to 300 nm.

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.

The host substance is preferably a quinolinolato complex, and more preferably an aluminum complex having 8-quinolinol or a derivative thereof as a ligand. 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 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 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 is preferably a mixed layer of at least one type of hole transporting compound and at least one type of electron transporting compound, if necessary. It is preferable to include them. The content of the dopant in such a mixed layer is
The content is preferably 0.01 to 20% by weight, more preferably 0.1 to 15% by weight, based on the total amount of the hole transporting compound and the electron transporting compound.

In the mixed layer, a hopping conduction path of carriers 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 transporting compound used in the mixed layer includes, for example, JP-A-63-295695, JP-A-2-191694, JP-A-3-792, JP-A-5-234681, JP-A-5-239455
JP, JP-A-5-299174, JP-A-7-1
No. 26225, JP-A-7-126226, JP-A-8-100172, EP0650955A1
And the like can be used. For example, a tetraarylbendicine compound (triaryldiamine or triphenyldiamine: TP
D), aromatic tertiary amines, hydrazone derivatives, carbazole derivatives, 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.

As the hole transporting compound, it is preferable to use an amine derivative having strong fluorescence, for example, a triphenyldiamine derivative, a styrylamine derivative, or an amine derivative having an aromatic condensed ring.

Examples of the electron-transporting compound include quinoline derivatives, 8-quinolinol or a metal complex having a derivative thereof as a ligand, particularly tris (8-quinolinolato).
It is preferable to use aluminum (Alq ³ ). It is also preferable to use a phenylanthracene derivative or a tetraarylethene derivative. An oxadiazole derivative, a perylene derivative, a pyridine derivative, a pyrimidine derivative, a quinoxaline derivative, a diphenylquinone derivative, a nitro-substituted fluorene derivative, or the like can be used. These compounds may be used alone or in combination of two or more.

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 electron transporting compound is 1
/ 99-99 / 1, more preferably 10 / 90-90
/ 10, particularly preferably about 20/80 to 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, 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 are an aluminum complex having 8-quinolinol or a derivative thereof as a ligand, and a mixed layer in which a tetraarylbendicine compound is doped with a fluorescent substance such as rubrene or coumarin. The mixing ratio of the aluminum complex having 8-quinolinol or a derivative thereof as a ligand and the tetraarylbendicine compound is preferably in the above range. The doping fluorescent substance such as rubrene,
Preferably it is 0.01 to 20 mol%.

Further, a hole injecting and transporting layer or an electron injecting and transporting layer may be formed between the electrode and the light emitting layer on which the insulating film is not formed.

The hole injecting and transporting layer is described in, for example,
JP-A-3-295695, JP-A-2-191694, JP-A-3-792, JP-A-5-234681
JP, JP-A-5-239455, JP-A-5-5-2
JP-A-99174, JP-A-7-126225, JP-A-7-126226, JP-A-8-100172
Various organic compounds described in JP-A No. 06509555 A1 and the like can be used. For example, a tetraarylbendicine compound (triaryldiamine or triphenyldiamine: TPD), an aromatic tertiary amine,
Examples include hydrazone derivatives, 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.

When the hole injecting / transporting layer is divided into a hole injecting / transporting layer and a hole injecting / transporting layer, a preferable combination is selected from the compounds for the hole injecting / transporting layer. Can be used. At this time, it is preferable to laminate the compounds in order from the hole injecting electrode (ITO or the like) with the smallest ionization potential. Further, it is preferable to use a compound having a good thin film property on the surface of the hole injection electrode. Such a stacking order is the same when two or more hole injection transport layers are provided. With such a stacking order, the driving voltage is reduced, and the occurrence of current leakage and the occurrence and growth of dark spots can be prevented. In addition, in the case of forming an element, since a thin film of about 1 to 10 nm can be made uniform and pinhole-free because evaporation is used,
Even if a compound having a small ionization potential and having absorption in the visible region is used for the hole injection layer, it is possible to prevent a change in the color tone of the emission color and a decrease in efficiency due to reabsorption. The hole injecting and transporting layer can be formed by vapor deposition of the above compound in the same manner as the light emitting layer and the like.

In the electron injection / transport layer, tris (8-
Quinolinolato) aluminum (quinoline derivatives such as organic metal complexes of 8-quinolinol or a derivative thereof Alq ³⁾ or the like as a ligand, oxadiazole derivatives, perylene derivatives, pyridine derivatives, pyrimidine derivatives, quinoxaline derivatives, diphenylquinone derivatives, Nitro-substituted fluorene derivatives and the like can be used. 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 element in order to prevent oxidation of the organic layer and the electrode of the element and to protect the element 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 this 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., but glass is particularly preferred. As such a glass material, for example, soda-lime glass, lead-alkali glass, borosilicate glass, aluminosilicate glass,
Glass compositions such as silica glass are preferred.

The means for adjusting the height of the sealing plate is not particularly limited, but it is preferable to use a spacer. By using spacers, it is inexpensive,
A desired height can be easily obtained. 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,
Various shapes may be used as long as the function as a spacer is not hindered. The size is preferably a circle-converted diameter of 1 to 20 μm, more preferably 1 to 10 μm, and particularly preferably 2 to 8 μm. The particle having such a diameter is preferably about 100 μm or less in grain length, 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 substrate material is not particularly limited and can be appropriately determined depending on the material of the electrodes 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. 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.

Further, if a color filter capable of cutting off short-wavelength external light which 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 the EL light and emits light from the phosphor in the fluorescence conversion film to convert the color of the emitted light. It is formed from a fluorescent material and a light absorbing material.

Basically, a fluorescent 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. Actually, 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 Compounds, styryl compounds,
A coumarin compound or the like may be used.

As the binder, a material that basically does not quench the fluorescence may be selected, and a binder that can be finely patterned by photolithography, printing, or the like is preferable. Further, a material which does not suffer damage when forming a hole injection electrode such as ITO or IZO or a thin film formed thereon is preferable.

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

For forming an organic layer, it is preferable to use a vacuum deposition 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.

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 in the case where 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.

[0081]

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 having a thickness of 100 nm was formed on a glass substrate by sputtering and patterned. The glass substrate on which the ITO transparent electrode is formed is subjected to ultrasonic cleaning using a neutral detergent, acetone, and ethanol,
It was 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.

Next, using SiO ₂ as a target, RF
By sputtering, a SiO ₂ insulating layer is formed at a deposition rate of 5 nm / min.
Then, a film was formed to a thickness of 20 nm. The sputtering gas at this time was Ar 100 sccm, and the operating pressure was 1 Pa. The temperature was room temperature, and the input power was 100 at a frequency of 13.56 MHz.
W, the distance between the substrate and the target was 5 cm.

Further, N, N, N
N ', N'-tetrakis (m-biphenyl) -1,1'
-Biphenyl-4,4'-diamine (TPD), tris (8-quinolinolato) aluminum (Alq3),
Rubrene at an overall deposition rate of 0.2 nm / sec.
It was deposited to a thickness of nm to form a light emitting layer. TPD: Alq ³ =
1: 1 (weight ratio), rubrene was added to this mixture in an amount of 0.1.
Doped at 5 mol%.

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.

Further, Al was deposited to a thickness of 100 nm by sputtering to form another electrode.

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

As a comparative sample, an ITO hole injection electrode was formed on a glass substrate to a thickness of 100 nm.
N, N'-diphenyl-N, N'-bis [N- (4-methylphenyl) -N-phenyl- (4-aminophenyl)]-1,1'-biphenyl-4,4'-diamine is deposited A hole injection layer is formed by vapor deposition at a rate of 0.2 nm / sec to a thickness of 50 nm, and TPD, Alq ³ and rubrene are vapor deposited to a thickness of 40 nm at an overall deposition rate of 0.2 nm / sec to form a light emitting layer ( TPD: Alq ³ = 1: 1 (weight ratio, rubrene 0.5 mol% with respect to this mixture), a MgAg electron injection electrode having a thickness of 100 nm, and an Al protection electrode having a thickness of 100 nm. A film was formed and sealed with glass to produce an organic EL device of a comparative example.

The manufactured organic EL device of the present invention was driven at a driving voltage of 100 V and a frequency of 1 kHz. Organic EL of Comparative Example
The device was driven at a constant current of 10 mA / cm ² . As a result, it was confirmed that the organic EL device of the present invention emitted light equivalent to the organic EL device of the conventional comparative example. In addition, neither leakage nor dark spots were observed. In addition, the life was longer than that of the organic EL device of the comparative example.

The insulating layer is made of Si ₃ N ₄ , PbO, PbO ₂ , A
l ₂ O ₃ , TiO ₂ , ZrO ₂ , HfO ₂ , Nb ₂ O ₅ ,
Ta ₂ O ₅ , Li ₂ O, CaO, SrO, BaO, BaT
iO ₃ , LiNbO ₃ , PbZrO ₃ , Pb (TiZr)
Similar results were obtained with O ₃ .

<Example 2> In Example 1, after forming the ITO transparent electrode, 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 a film thickness of 50 nm to form a hole injection layer.

Next, N, N, N ', N'-tetrakis (m-biphenyl) -1,1'-biphenyl-4,4'
Diamine (TPD) is deposited at a deposition rate of 0.2 nm / sec at a thickness of 20 nm.
To form a hole transport layer.

Further, after forming the light emitting layer in the same manner as in the first embodiment, the SiO ₂ insulating layer was formed in the same manner as in the first embodiment.
The film was formed to a thickness of 20 nm at a film forming speed of 5 nm / min.

The other steps were the same as in Example 1 to obtain an organic EL device. When the obtained organic EL device was compared with a comparative sample in the same manner as in Example 1, the same results as in Example 1 were obtained.

[0094]

As described above, according to the present invention, an organic EL device having high heat resistance, high weather resistance, low occurrence of leaks and dark spots, high mass productivity, and low cost can be provided. be able to.

[Brief description of the drawings]

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

FIG. 2 is a schematic cross-sectional view schematically showing another configuration example of the organic EL device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 1st electrode 3 Insulating layer 4 Organic layer 5 2nd electrode

Claims (6)

[Claims] 1. A substrate having a pair of electrodes and one or more organic layers involved in at least a light-emitting function between these electrodes on a substrate, wherein the organic layer and one of the electrodes are An organic EL element having an insulating layer between them. 2. The organic EL device according to claim 1, wherein at least one of said electrodes is made of tin-doped indium oxide or zinc-doped indium oxide. 3. The organic EL device according to claim 1, wherein said insulating layer has a thickness of 2 to 50 nm. 4. The insulating layer is made of one of silicon oxide, silicon nitride, lead oxide, aluminum oxide, titanium oxide, zirconium oxide, hafnium oxide, niobium oxide, tantalum oxide, lithium oxide, calcium oxide, strontium oxide and barium oxide. The organic EL device according to any one of claims 1 to 3, wherein the organic EL device contains one or more species. 5. The organic EL device according to claim 1, which is driven by an alternating current. 6. The organic EL device according to claim 1, wherein the organic layer has a layer containing an aluminum complex having 8-quinolinol or a derivative thereof as a ligand, a tetraarylbendicine compound, and rubrene. .