JP2001060495A - Organic el element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the oxidation and deterioration of a cathode and an interface between cathode and organic layer, and the change with the lapse of time to improve the life, by successively laminating a base, a color filter layer, a barrier layer, a hole injection electrode, an organic layer having at least the luminescent function and an electron injection electrode, and specifying a coefficient of linear expansion of the barrier layer. SOLUTION: A color filter layer 2, an overcoat layer 3, a barrier layer 4, a hole injection electrode 5, a hole injection layer 6, and a luminescent layer 7 as an organic layer relative to at least the luminescent function are successively laminated on a base 1. Further an electron injection transport layer 8 and an electron injection electrode 9 are successively formed thereon, a coefficient of linear expansion of the barrier layer 4 is adjusted within a range of 1×10-4 to 1×10-6 cm/ deg.C, and coefficients of linear expansion of components are specified within a constant range. A material of the hole injection electrode 5 is, for example, a tin doped-indium oxide (ITO) having a work function of 4.5-5.5 ev. Whereby an organic EL element superior in the environmental-proof characteristic, in particular, the temperature characteristic can be provided.

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) element, and more particularly to a bonding structure of constituent thin films.

[0002]

2. Description of the Related Art Organic EL devices can be formed on glass in a large area, and are being researched and developed for displays and the like. In general, an organic EL element is formed by forming a transparent electrode such as ITO on a glass substrate, and laminating an organic amine-based hole transport layer and an organic light emitting layer made of, for example, an Alq3 material which exhibits electron conductivity and emits strong light. Further, an electrode having a small work function, such as MgAg, is formed and used as a basic element.

[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.

FIG. 2 shows a typical structure of an organic EL device. In FIG. 2, a color filter layer 12, an overcoat layer 13, and a barrier layer 14 provided on a substrate 11 are shown.
In addition, a hole transport layer 16, which is an organic compound, a light emitting layer 17, and an electron transport layer 18 are formed between the hole injection electrode 15 and the electron injection electrode 19.

Since such organic EL elements can provide high-quality display by self-emission, they are expected to be applied to display panels of AV equipment and panels of mobile instruments such as automobiles and motorcycles. ing.

By the way, when considering such application to a mobile body, environmental friendliness and reliability are serious problems. That is, the environment inside the moving body is different from ordinary home electric appliances, and is -2.
It must be able to withstand use in a temperature range from about 0 ° C. to about + 80 ° C. The organic EL element has a substrate, a hole injection electrode, and an electron injection electrode in principle, and requires an organic layer disposed between these electrodes and at least involved in a light emitting function. However, these materials have different coefficients of linear expansion, and when used repeatedly in an environment where temperature changes are severe, the electrode portion and the like may peel off to cause a non-light emitting portion or a problem of causing a leak current. Had.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to realize an organic EL device which is excellent in environmental resistance, especially in temperature resistance.

[0009]

Means for Solving the Problems That is, the above object is as follows.
This is achieved by the following configuration. (1) a substrate, a color filter layer, a barrier layer,
Organic E having a hole injection electrode, at least an organic layer involved in at least a light emitting function, and an electron injection electrode, wherein the linear expansion coefficient of the barrier layer is 1 × 10 ⁻⁴ to 1 × 10 ⁻⁶ cm / ° C.
L element. (2) The above (1), wherein the hole injection electrode is ITO.
Organic EL device. (3) The linear expansion coefficient of the substrate, the color filter layer, the barrier layer, the hole injection electrode and the electron injection electrode is 1 × 1.
The organic EL device according to the above (1) or (2), wherein the organic EL device has a temperature of ^0-4 to 1 * ^10-6 cm / C. (4) The organic EL device according to any one of (1) to (3), wherein the barrier layer contains silicon oxide as a main component, and further contains a material having a higher thermal expansion coefficient as a subcomponent. (5) The organic EL device according to (4), wherein the auxiliary component is one or more oxides of an alkaline earth element or a lanthanoid element. (6) The content of the subcomponent is 1 to 1
The organic EL device according to the above (4) or (5), wherein the content is 50 mol%. (7) An overcoat layer is further provided between the color filter layer and the barrier layer, wherein the overcoat layer has a linear expansion coefficient of 1 × 10 ⁻⁴ to 1 × 10 ⁻⁶ cm / ° C. ) To (6).

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The organic EL device of the present invention has a substrate, a color filter layer, a barrier layer, a hole injection electrode, at least an organic layer involved in at least a light emitting function, and an electron injection electrode. , The coefficient of linear expansion of the barrier layer is 1 ×
It is 10 ^-4 to 1 × 10 ^-6 cm / ° C.

Thus, the coefficient of linear expansion of the barrier layer is 1 ×
By adjusting the range of 10 ⁻⁴ to 1 × 10 ⁻⁶ cm / ° C., peeling of the electrode and the like is prevented, and environmental resistance and temperature resistance are dramatically improved.

That is, the organic EL device has a substrate, a color filter layer, a barrier layer, a hole injection electrode, at least an organic layer involved in a light emitting function, and an electron injection electrode. Linear expansion coefficient: Glass substrate: 1 × 10 ⁻⁶ cm / ° C. Color filter layer: 1 × 10 ⁻⁴ cm / ° C. Barrier layer (SiO ₂ ): 2 × 10 ⁻⁷ cm / ° C. Hole injection electrode (ITO): 1 × 10 ⁻⁴ cm / ° C. Electron injection electrode: about 1 × 10 ⁻⁵ cm / ° C. Among these, the barrier layer has a linear expansion coefficient of 2
× 10 ^-7 cm / ℃ with small linear expansion coefficient of the other components except the barrier layer is ^{1 × 10 -4 ~1 × 10 -} 6 cm /
It is in the range of ° C. Therefore, by adjusting the coefficient of linear expansion of the barrier layer within the range of 1 × 10 ⁻⁴ to 1 × 10 ⁻⁶ cm / ° C., the coefficient of linear expansion of each component of the organic EL element is adjusted to be within a certain range. Can be.

The barrier layer is usually made of silicon oxide (SiO
₂ ) is used. The coefficient of linear expansion of this silicon oxide is 2
X 10 ^-7 cm / ° C., and within this range, a material having a large linear expansion coefficient may be contained in the barrier layer. As a material having a large linear expansion coefficient, a material having a higher linear expansion coefficient than silicon oxide which is the barrier layer constituting material,
Preferably, the coefficient of linear expansion is 1 × 10 ^{−4 to} 5 × 10 ⁻⁶ cm /
Is a material that is in ° C. Specifically, Be, Mg, Ca, S
alkaline earth metal elements of r, Ba and Ra;
Co, Pr, Nd, Pm, Sm, Eu, Gd, Tb, D
Oxides, nitrides and silicides of one or more of the lanthanoid elements y, Ho, Er, Tm, Yb and Lu can be mentioned.

In this case, the composition of the barrier layer is mainly composed of silicon oxide, and when a material having a large linear expansion coefficient is used as a sub-component, depending on the linear expansion coefficient of the material to be used, the sub-component is composed of oxide or nitride. , 1 to 70 mol% in terms of silicide, especially 20
It is preferable to contain about 50 mol%.

The barrier layer is a layer for protecting the electrode and the organic layer from moisture, outgas, etc. from the color filter layer or the overcoat layer.

The thickness of the barrier layer is usually 50 to 3
It is about 00 nm.

As a method for forming the barrier layer, various physical or chemical thin film forming methods such as a sputtering method and an EB vapor deposition method are possible, but the sputtering method is preferable.

When the barrier layer is formed by a sputtering method, the pressure of the sputtering gas at the time of sputtering is preferably in the range of 0.1 to 1 Pa. As the sputtering gas, an inert gas used in a normal sputtering apparatus, for example, Ar, Ne, Xe, Kr, or the like can be used. Further, N ₂ may be used if necessary.

As the sputtering method, a high-frequency sputtering method using an RF power source, a DC reactive sputtering method, or the like can be used, but RF sputtering is particularly preferred. The power of the sputtering apparatus is preferably 0.1 to 10 W / RF sputtering.
cm ² is preferable, and the deposition rate is 0.5 to 10 nm /
min, especially in the range of 1 to 5 nm / min. The substrate temperature during film formation is from room temperature (25 ° C.) to about 150 ° C.

As the reactive gas, O ₂ , NO, N
O ₂ , N ₂ O, CO, CO ₂ , silane, disilane and the like can be mentioned. These reactive gases may be used alone or as a mixture of two or more.

As the negative electrode, in combination with an organic electron injection / transport layer or the like, the following electrode can be used as necessary as an electrode having electron injection properties. For example,
K, Li, Na, Mg, La, Ce, Ca, Sr, B
a, Sn, Zn, Zr or other metal element alone, or a binary or ternary alloy system containing them to improve stability, for example, Ag.Mg (Ag: 0.1 to 50 at%), A
l·Li (Li: 0.01 to 14 at%), In · Mg
(Mg: 50-80 at%), Al.Ca (Ca: 0.0
1 to 20 at%).

The thickness of the negative electrode thin film may be a certain thickness or more for sufficiently injecting electrons, and may be 0.1 nm or more, preferably 0.5 nm or more, particularly 1 nm or more. Also,
Although there is no particular upper limit, the film thickness is usually 1 to 50.
It may be about 0 nm.

The negative electrode (electron injecting electrode) does not need to have a low work function and an electron injecting property in combination with the following high-resistance inorganic electron injecting and transporting layer and inorganic insulating electron injecting and transporting layer. Therefore, there is no particular limitation, and ordinary metals can be used. Among them, in terms of conductivity and ease of handling, Al, Ag, In, Ti, Cu, Au, Mo,
One or two or more metal elements selected from W, Pt, Pd and Ni, particularly Al and Ag are preferred.

The thickness of the negative electrode thin film may be a certain thickness or more that can provide 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 total thickness of the negative electrode and the protective layer is not particularly limited, but 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 or the like, and is preferably a material having a work function of 4.5 eV to 5.5 eV. Specifically, tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO), indium oxide (In
₂ O ₃ ), tin oxide (SnO ₂ ) and zinc oxide (Zn
O) having a main composition of either of them is preferable. 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 wt%. Also, IZO
The mixing ratio of ZnO to In ₂ O ₃ 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, more preferably 80% or more, and particularly preferably 90% or more for each emitted light. If the transmittance is too low, the light emission itself from the light emitting layer is attenuated, and it becomes difficult to obtain the luminance required for the light emitting element.

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

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 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 device 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 it 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 preferably 0.01 to 10% by volume, and more preferably 0.1 to 5% by volume. In the case of rubrene, the content is preferably about 0.01 to 20% by volume. 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].

Further, 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 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 also serve as an electron injection / transport layer. In such a case, it is preferable to use tris (8-quinolinolato) 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 volume, more preferably 0.1 to 15% by volume.

In the mixed layer, a carrier hopping conduction path 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 injecting / transporting compound and the electron injecting / transporting compound used in the mixed layer may be selected from a hole injecting / transporting compound and an electron injecting / transporting compound described later, respectively.

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 its derivative as a ligand, particularly tris (8-quinolinolato) aluminum (Alq3). It is also preferable to use the above-mentioned phenylanthracene derivatives and tetraarylethene derivatives.

As the compound capable of injecting and transporting holes, an amine derivative having strong fluorescence, for example, a triphenyldiamine derivative which is the above-described hole transporting 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 mobilities and carrier concentrations. In general, the weight ratio of the compound of the hole injecting / transporting compound / the compound having the electron injecting / transporting function is from 1/99 to more. 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 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 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 electron injecting / transporting layer is made of a quinoline derivative such as an organometallic complex having 8-quinolinol such as tris (8-quinolinolato) aluminum (Alq3) or a derivative thereof as a ligand, an oxadiazole derivative, a perylene derivative, or pyridine. Derivatives, pyrimidine derivatives, quinoxaline derivatives, diphenylquinone derivatives, nitro-substituted fluorene derivatives and the like can be used.

The electron injecting and transporting 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 injection layer may be formed by vapor deposition or the like, similarly to the light emitting layer.

The thickness of the electron injecting and transporting layer is not particularly limited and varies depending on the forming method.
The thickness is preferably about 500 nm, particularly preferably 10 to 300 nm.

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.

For forming the light emitting layer, the hole injecting and transporting layer, and the electron injecting and transporting 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 0.2 μm or less can be obtained. If the crystal grain size exceeds 0.2 μm, the light emission becomes non-uniform, the driving voltage of the device must be increased, and the injection efficiency of electrons and holes 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 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 deterioration 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, and N ₂ 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 by using a spacer, and may be maintained at a desired height. 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 previously mixed into the sealing adhesive or may be mixed during 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 thereof 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. When the substrate is 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 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. In the case where the hole injection electrode is formed on the substrate in contact with the hole injection electrode, a material which is not damaged when the hole injection electrode (ITO, IZO) is formed 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 usually used as a DC drive type or pulse drive type EL device, but it can also be driven by AC. The applied voltage is usually 2 to 30
V.

For example, as shown in FIG. 1, the organic EL device of the present invention comprises a substrate 1, a color filter layer 2, an overcoat layer 3, a barrier layer 4, a hole injection electrode 5, a hole injection transport layer 6, and a light emitting layer 7. / Electron injection / transport layer 8 / negative electrode (electron injection electrode) 9 may be sequentially laminated. In FIG. 1, a drive power source E is connected between the hole injection electrode 2 and the negative electrode 9.

The elements of the present invention may be stacked in multiple layers in the film thickness direction. With such an element structure, it is also possible to adjust the color tone of the emitted light and to make it multi-colored.

The organic EL element of the present invention can be applied to various optical applications such as an optical pickup used for memory read / write, a relay device in an optical communication transmission line, a photocoupler, etc., in addition to a display application. Can be used for devices.

[0076]

<Example 1> A 7059 substrate (trade name, manufactured by Corning Incorporated) as a glass substrate was scrub-cleaned using a neutral detergent.

A pigment dispersion type color filter layer was formed to a thickness of 2.0 μm. This is a material in which a pigment is dispersed in an acrylic resin, and is formed by spin-coating a commercially available chemical solution, prebaking, and then repeatedly exposing, developing, and curing.

Further, in order to flatten the surface of the color filter layer, a colorless and transparent overcoat layer of an acrylic resin was formed in the same manner as the color filter layer. When the linear expansion coefficients of the color filter layer and the overcoat layer were measured, both were 1 × 10 ⁻⁴ cm / ° C.

Next, as a barrier layer, the main component SiO _{2 was used.}
To form a film in which La ₂ O ₃ was mixed as an auxiliary component. As a film forming condition, a sputtering method is used, and a target is made of Si.
The La ₂ O ₃ was used mixed in O _2. Been formed,
The composition of the barrier layer, the La ₂ O ₃ with respect to SiO ₂ 40 m
ol%. The measured linear expansion coefficient of the barrier layer was 1 × 10 ⁻⁵ cm / ° C.

An ITO hole injection electrode layer having a thickness of 200 nm was formed on the substrate on which the color filter layer, the overcoat layer, and the barrier layer were formed by RF magnetron sputtering using an ITO oxide target. This I
When the linear expansion coefficient of the TO electrode was measured, it was 1 × 10 ^-4 c
m / ° C.

After the surface of the substrate on which the ITO electrode layer and the like had been formed was washed with UV / O _3, it was fixed to a substrate holder of a vapor deposition apparatus, and the pressure in the tank was reduced to 1 × 10 ⁻⁴ Pa or less.

4,4 ', 4 "-tris (-N- (3-methylphenyl) -N-phenylamino) triphenylamine (m-MTDATA) was deposited at a deposition rate of 0.2 nm / sec to a thickness of 40 nm. Evaporation was performed to form a hole injection layer.

Next, N, N, N ', N'-tetrakis (m-biphenyl) -1,1'-biphenyl-4,4'
-Diamine (TPD) was deposited at a deposition rate of 0.2 nm / sec to a thickness of 40 nm to form a hole transport layer.

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: Alq3 =
Rubulene was doped at 5% by volume with respect to the mixture at a ratio of 1: 1 (weight ratio).

Further, the tris (8-
(Quinolinolato) aluminum (Alq3) was deposited at a deposition rate of 0.2 nm / sec to a thickness of 40 nm to form an electron injection transport layer.

Then, while maintaining the reduced pressure, AlLi (L
i: 7 at%) to a thickness of 1 nm, followed by Al
Evaporation was performed to a thickness of 0 nm to form a negative electrode for an electron injection electrode and an auxiliary electrode. When the linear expansion coefficients of these electrodes were measured, they were all 1 × 10 ⁻⁵ ° C.

As a comparative example, a comparative sample in which MgO was not mixed into the barrier layer was prepared.

Each of the obtained organic EL devices was placed in air for 1 hour.
After driving at 85 ° C. for 100 hours at a constant current density of 0 mA / cm ² , the light-emitting surface was checked. As a result, no light-emitting unevenness due to stress was observed on the surface of the light-emitting pixel after 100 hours. On the other hand, in the comparative sample, a large number of light emission unevenness which was considered to be caused by stress was confirmed.

<Example 2> In Example 1, the sub-component added to SiO ₂ of the barrier layer was changed from MgO to Be, M
g, Ca, Sr, Ba and Ra alkaline earth metal elements, La, Co, Pr, Nd, Pm, Sm, Eu, G
d, Tb, Dy, Ho, Er, Tm, Yb and Lu are replaced with one or more oxides, nitrides, and silicides of lanthanoid elements, and adjusted to an addition amount corresponding to their respective linear expansion coefficients. Other than the above, the organic EL was used in the same manner as in Example 1.
An element was obtained.

When the obtained organic EL device was evaluated in the same manner as in Example 1, it was confirmed that substantially the same effect was obtained.

[0091]

As described above, according to the present invention, it is possible to realize a long-life organic EL device by suppressing the oxidation and deterioration of the negative electrode and the interface between the negative electrode and the organic layer and the change with time.

[Brief description of the drawings]

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Color filter layer 3 Overcoat layer 4 Barrier layer 5 Hole injection electrode 6 Hole injection layer 7 Light emitting layer 8 Electron injection transport layer 9 Negative electrode (electron injection electrode) 11 Substrate 12 Color filter layer 13 Overcoat layer 14 Barrier layer 15 hole injection electrode 16 hole injection layer 17 light emitting layer 18 electron injection transport layer 19 negative electrode (electron injection electrode)

Claims (7)

[Claims] 1. A semiconductor device comprising a substrate, a color filter layer, a barrier layer, a hole injection electrode, an organic layer involved in at least a light emitting function, and an electron injection electrode, wherein the barrier layer has a linear expansion coefficient of 1 × 10 ^-4 to 1 × 10 ^-6
An organic EL device having a cm / ° C. 2. The organic EL device according to claim 1, wherein said hole injection electrode is ITO. 3. The organic compound according to claim 1, wherein the substrate, the color filter layer, the barrier layer, the hole injection electrode, and the electron injection electrode have a linear expansion coefficient of 1 × 10 ⁻⁴ to 1 × 10 ⁻⁶ cm / ° C. EL element. 4. The organic EL device according to claim 1, wherein said barrier layer contains silicon oxide as a main component, and further contains a material having a higher thermal expansion coefficient as an auxiliary component. 5. The organic EL device according to claim 4, wherein the auxiliary component is one or more oxides of an alkaline earth element or a lanthanoid element. 6. The organic EL device according to claim 4, wherein the content of the subcomponent is 1 to 50 mol% in total with respect to the main component. 7. An overcoat layer is further provided between the color filter layer and the barrier layer, and the overcoat layer has a linear expansion coefficient of 1 × 10 ^-4 to 1
The organic EL device according to claim 1, wherein the temperature is × 10 ⁻⁶ cm / ° C. 7.