JP2001307873A - Organic electroluminescent display device and method of manufacturing the same - Google Patents

Abstract

(57) [Summary] [PROBLEMS] By improving sealing failure, the effect of moisture and oxygen in the air is eliminated as much as possible, and there is little deterioration over time, and a long-life organic EL display that can maintain initial performance for a long time. An element is provided. An organic electroluminescent device having an electrode, a fluorescent medium, a counter electrode, and a sealing layer covering at least the fluorescent medium and the counter electrode on a substrate.
The organic material, wherein the sealing layer is a laminate in which at least a barrier layer 6a made of a metal film or an inorganic film, a resin layer 7 made of an acrylic monomer or an acrylic oligomer, and a barrier layer 6b are sequentially formed. Electroluminescence display element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting display as a display device, and more particularly, to an organic electroluminescent display element which is one of flat panel displays and a method of manufacturing the organic electroluminescent display element.

[0002] In the following description, "electroluminescence" is referred to as "EL".

[0003]

2. Description of the Related Art Since an organic EL display element is of a self-luminous type, a display using the same has a feature that it has high luminance, a wide viewing angle, and can be driven at a low voltage.

[0004] The organic EL display element basically has a structure in which at least one light emitting medium composed of an organic substance is sandwiched between an anode and a cathode, and a predetermined current is applied between the two electrodes so that the light emitting medium emits light. I do. Usually, each of the anode and the cathode is constituted by a plurality of electrode lines, and the anode line and the cathode line are orthogonal to each other to constitute a simple matrix display. The luminescent medium present at the intersection of each anode line and cathode line forms one pixel.

In an organic EL display element, if the light emitting medium and the cathode line are left exposed to the atmosphere, they are deteriorated by moisture, oxygen and the like in the atmosphere. Under the influence of moisture, oxygen, and the like in the atmosphere, for example, separation occurs at the interface between the light emitting medium and the electrode, or the constituent materials are altered. As a result, a non-light-emitting area called a dark spot occurs, or light emission of a predetermined quality cannot be maintained.

As a method for solving this problem, for example,
As described in JP-A-5-36475, JP-A-5-89959, JP-A-7-169567, etc., an airtight case or the like that covers an organic EL display element in a nitrogen atmosphere or an inert gas atmosphere. A technique is known in which the substrate is closely fixed on a light-transmitting insulating substrate to block moisture, oxygen and the like in the atmosphere.

However, the hermetic case is formed of metal or glass, and is about half the thickness and weight of the organic EL display element.
Occupies ~ 1/3. Therefore, when the organic EL display element is to be made thinner and lighter, it is preferable to remove the hermetic case or the like covering the organic EL display element and completely seal the organic EL display element only with the sealing film.

[0008] When a voltage is applied to the organic EL display element, a local short circuit may occur, and the heat generated thereby may cause the organic layer to evaporate. The energy may cause pinholes and cracks in the sealing layer, which may cause passage of external moisture, oxygen, and the like. Therefore, even when the sealing is completely performed only with the sealing layer, it is not possible to completely shut off moisture, oxygen, and the like in the air, and a dark spot may be generated as the driving time elapses. In some cases, light emission of a predetermined quality cannot be maintained.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in order to solve these problems. By improving the sealing failure, the effects of moisture and oxygen in the atmosphere are eliminated as much as possible. An object of the present invention is to provide a long-life organic EL display element capable of maintaining initial performance for a long time with little deterioration over time and a method of manufacturing the same.

[0010]

In order to achieve the above object of the present invention, first, in claim 1, an electrode, a fluorescent medium and a counter electrode on a substrate, and at least a sealing covering the fluorescent medium and the counter electrode are provided. The sealing layer is a laminated body in which at least a barrier layer, a resin layer, and a barrier layer are sequentially formed, wherein the sealing layer is a laminated body.

According to a second aspect, based on the premise of the first aspect, the barrier layer has a metal film having at least a water vapor barrier property and / or an oxygen barrier property,
Or, it is an organic electroluminescent display element characterized by being an inorganic film or a laminated film thereof.

According to a third aspect of the present invention, there is provided an organic electroluminescent display device according to the first and second aspects, wherein the resin layer is made of an acrylic monomer or an acrylic oligomer. is there.

According to a fourth aspect of the present invention, there is provided an organic electroluminescence device having an electrode, a fluorescent medium, a counter electrode, and a sealing layer covering at least the fluorescent medium and the counter electrode on a substrate. A step of coating with a barrier layer, a step of coating the barrier layer with a resin layer,
A method for manufacturing an organic electroluminescent display element, comprising a step of curing the resin layer and a step of covering the resin layer with a barrier layer.

According to a fifth aspect of the present invention, based on the premise of the fourth aspect, an organic electroluminescent display element is characterized in that the steps from the formation of the light emitting medium to the formation of the sealing layer are continuously performed in a vacuum. This is a method of manufacturing.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an example of an organic EL display device of the present invention will be described in detail according to a manufacturing process in which an electrode on a substrate is an anode and a counter electrode is a cathode.

First, a transparent conductive film is formed on a transparent insulating substrate by a sputtering method or the like, and the transparent conductive film is patterned by a photolithography method and a wet etching method to form a plurality of electrodes (anode lines).

As the substrate in the present invention, a quartz substrate,
A glass substrate, a plastic substrate, or the like can be used.

As a material for the plurality of anode lines in the present invention, a transparent electrode material such as ITO (indium-tin composite oxide), indium-zinc composite oxide, and zinc-aluminum composite oxide can be used.

Incidentally, in order to reduce the resistance, a metal such as copper, chromium, aluminum and titanium or a laminate thereof can be partially provided as an auxiliary electrode in the transparent conductive film. Further, it is not necessary to form a short-circuit prevention insulating layer on the anode, but the invention is not limited to the absence of the insulating layer.

Thereafter, a light emitting medium and a counter electrode (cathode) are deposited. At the time of deposition of the counter electrode, the counter electrode is connected to a lead electrode formed in advance, generally, a transparent conductive film which is patterned while forming an electrode (anode line). The extraction electrode is extended from the inside to the outside of the light emitting display area.

The luminescent medium of the present invention can be formed of a single-layer film containing a fluorescent substance or a multilayer film.

When the light-emitting medium is formed of a multilayer film, examples of the structure of the light-emitting medium include a hole injection / transport layer, an electron-transport light-emitting layer or a hole-transport light-emitting layer, and a two-layer structure including an electron-transport layer.
There is a three-layer structure including a light emitting layer and an electron transport layer. Further, it is also possible to form a multi-layer, and each layer is sequentially formed on a substrate.

Examples of the hole injecting and transporting material include metal phthalocyanines such as copper phthalocyanine and tetra (t-butyl) copper phthalocyanine, and metal-free phthalocyanines, quinacridone compounds, 1,1-bis (4-di-p- Tolylaminophenyl) cyclohexane, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1 ′
-Biphenyl-4,4'-diamine, N, N'-di (1
-Naphthyl) -N, N'-diphenyl-1,1'-biphenyl-4,4'-diamine and other aromatic amine-based low-molecular-weight hole injecting and transporting materials, poly (paraphenylenevinylene),
It can be selected from polymeric hole transport materials such as polyaniline and polythiophene derivatives, and other existing hole transport materials.

Examples of light emitting materials include 9,10-diarylanthracene derivatives, pyrene, coronene, perylene, rubrene, 1,1,4,4-tetraphenylbutadiene, tris (8-quinolinolato) aluminum complex, tris (4 -Methyl-8-quinolinolate) aluminum complex, bis (8-quinolinolate) zinc complex, tris (4-methyl-5-trifluoromethyl-8-quinolinolate) aluminum complex, tris (4-methyl-
5-cyano-8-quinolinolate) aluminum complex,
Bis (2-methyl-5-trifluoromethyl-8-quinolinolate) [4- (4-cyanophenyl) phenolate] aluminum complex, bis (2-methyl-5-cyano-8-quinolinolate) [4- (4- Cyanophenyl)
Phenolate] aluminum complex, tris (8-quinolinolate) scandium complex, bis [8- (para-tosyl) aminoquinoline] zinc complex and cadmium complex,
1,2,3,4-tetraphenylcyclopentadiene,
Pentaphenylcyclopentadiene, poly-2,5-diheptyloxy-para-phenylenevinylene, coumarin-based phosphor, perylene-based phosphor, pyran-based phosphor, anthrone-based phosphor, porphyrin-based phosphor, quinacridone-based phosphor, Low molecular materials such as N, N'-dialkyl-substituted quinacridone-based phosphors, naphthalimide-based phosphors, N, N'-diaryl-substituted pyrrolopyrrole-based phosphors, and high-molecular materials such as polyparavinylene derivatives and polyfluorene derivatives;
Other existing light emitting materials can be used.

Examples of the organic electron transporting material include 2- (4
-Bifinylyl) -5- (4-t-butylphenyl)
-1,3,4-oxadiazole, 2,5-bis (1-
Naphthyl) -1,3,4-oxadiazole, oxadiazole derivatives, bis (10-hydroxybenzo [h] quinolinolate) beryllium complexes, triazole compounds and the like.

The luminous medium can be formed by a vacuum deposition method. The thickness of the luminescent medium is 1 μm or less even when it is formed as a single layer or a stacked layer, and preferably 5 μm or less.
0 to 150 nm.

As the cathode material, a substance having a high electron injection efficiency is used. Specifically, a single metal such as Mg, Al, or Yb may be used, or Li or oxidized Li, L
Al and Cu having high stability and conductivity are stacked and used with a compound such as iF sandwiched by about 1 nm.

Alternatively, in order to achieve both electron injection efficiency and stability, low work functions of Li, Mg, Ca, Sr, La, C
one or more metals such as e, Er, Eu, Sc, Y, Yb;
An alloy system with a stable metal element such as Ag, Al, or Cu is used. Specifically, alloys such as MgAg, AlLi, and CuLi can be used.

As a method for forming the counter electrode (cathode), a resistance heating evaporation method, an electron beam evaporation method, a reactive evaporation method, an ion plating method, or a sputtering method can be used depending on the material. The thickness of the cathode is desirably about 10 nm to 1 μm.

Finally, the moisture in the atmosphere of the luminescent medium and the cathode,
In order to suppress deterioration due to oxygen, a sealing layer is sequentially formed on the structure. First, a barrier layer is laminated to completely cover the structure. The barrier layer is formed of a metal film having a water vapor barrier property and / or an oxygen barrier property, an inorganic film, or a laminated film thereof. In the case of a laminated film, a combination with an organic layer may be used. When using a conductive barrier film, care must be taken not to short-circuit the cathode.

As the metal film used in the present invention, aluminum, magnesium, copper or the like can be used.

As the inorganic film used in the present invention, oxides such as aluminum oxide, magnesium oxide and silicon oxide, fluorides such as aluminum fluoride and magnesium fluoride, and nitrides such as aluminum nitride and silicon nitride are used. Can be used.

As a method of forming the barrier layer, a resistance heating evaporation method, an electron beam evaporation method, a reactive evaporation method, an ion plating method, and a sputtering method can be used depending on the material. The thickness of the seal is not limited as long as it has a sufficient water vapor barrier property and / or oxygen barrier property.
About 100 μm, preferably about 0.1 μm to 10 μm is desirable.

Next, a resin layer is formed on the barrier layer. For the resin layer, a thermosetting resin, a photocurable resin, an electron beam curable resin, or the like can be used. However, when selecting the resin,
Care must be taken not to dissolve the luminescent medium with a solvent during film formation, and not to destroy the luminescent medium with heat during curing. Therefore, it is more preferable to use a vacuum film forming method without using a solvent for forming the resin layer. In addition, the resin includes a thermosetting resin such as a phenol resin, an unsaturated polyester, and a silicon resin that can be cured by heat without destroying the light emitting medium, a photocurable resin that does not affect the light emitting medium when cured, or an electron beam. A curable resin can be used. In particular, for resin,
It is preferable to use an acrylic monomer or an acrylic oligomer because it can be formed in a vacuum and is cured with light or an electron beam.

The photo-curable resin or the electron beam-curable resin contains an aliphatic acrylate, an alicyclic acrylate, an aromatic acrylate, an OH group or an allyl group, a glycidyl group, a carboxyl group, a chromo group, or a bromo group. Resin monomers or oligomers such as functional group-containing acrylates, phosphorus acrylates and metal acrylates can be used. Alternatively, a methacrylate having the same skeleton as the acrylate may be used. Alternatively, resin monomers or oligomers such as pyrrolidone and vinyl acetate can be used. In addition, a polymerization initiator or the like may be mixed and used together to promote curing.

The resin layer may be formed according to the material by resistance heating evaporation, flash evaporation, electron beam evaporation,
A sputtering method can be used. After the film is formed, it is cured by a predetermined method. After film formation, curing is preferably performed in a vacuum.

Next, the barrier layer is formed again on the resin layer.

In the organic EL display device thus manufactured, when a voltage is applied, heat is generated due to a short circuit, and the energy causes the first barrier layer to be destroyed, thereby generating pinholes and cracks through which water vapor and oxygen pass. Even so, pinholes and cracks are blocked by the resin layer. Therefore, the pinholes and cracks connected from the first barrier layer do not come into contact with the outside air due to the second barrier layer.

The sealing layer is not limited to three layers consisting of the barrier layer / resin layer / barrier layer, but may be four or more layers.

In addition, using the above-described materials and forming method, an organic electrode having an electrode on a substrate serving as a cathode and an opposing substrate serving as an anode is used.
It goes without saying that the L display element can be manufactured.

[0041]

[Embodiment 1] An embodiment of the present invention will be described with reference to FIG. First, an ITO film was formed as an anode on a substrate 1 made of glass by a sputtering method. Further, in order to improve transparency and conductivity, a heat treatment was performed in air at 230 ° C. for 1 hour to crystallize the ITO film.

Next, the ITO film 2 was patterned by photolithography and wet etching to form an electrode (anode) 2.

Next, copper phthalocyanine, N, N'-di (1-naphthyl) -N, N'-diphenyl-1,1'-biphenyl-4,4'-diamine, tris ( 8-Quinolinolato) aluminum complex was sequentially vacuum-deposited with a film thickness of 10 nm, 40 nm, and 50 nm, and then MgAg as a counter electrode (cathode) 4 was binary co-deposited while rotating the substrate.

Next, a sealing layer 5 is formed. First, SiO ₂ and Al are sequentially formed as the barrier layer 6a to a thickness of 200 nm
Vacuum evaporation was performed at a film thickness of 0 nm.

Next, polyethylene glycol acrylate was vacuum-deposited to a thickness of 2 μm as a resin layer 7 on the barrier layer 6a, and electron beam curing was performed in a vacuum. The electron beam curing was performed at an electron irradiation amount of 10 Mrad and an acceleration voltage of 120 kV.

Next, A is formed on the resin layer 7 as a barrier layer 6b.
1 and SiO ₂ were sequentially vacuum deposited to a thickness of 200 nm and 200 nm.

In the obtained organic EL display element, enlargement of a dark spot was not observed, and the initial luminance was 300 cd / m ² and the half-life was 6000 hours. Even a minute dark spot having a diameter of about 1 μm or less generated during the life measurement did not expand.

[Example 2] Epoxy ester 70PA (manufactured by Kyoei Chemical Co., Ltd.) was vacuum-deposited with a thickness of 2 μm as a resin layer on the organic EL display element manufactured in the same process as in Example 1, and immediately the electron Wire curing was performed. The electron beam curing was performed at an electron irradiation amount of 20 Mrad and an acceleration voltage of 200 kV. In the obtained organic EL display element, enlargement of a dark spot was not observed, and the initial luminance was 300 cd / m ² and the half-life was 4000 hours. Even a minute dark spot having a diameter of about 1 μm or less generated during the life measurement did not expand.

[Comparative Example] In the organic EL display element manufactured in the same process as in Example 1, without forming a resin layer, the barrier layer was simply vacuum-deposited with SiO ₂ and Al in order of 200 nm and 200 nm in thickness. did. No dark spots were observed in the obtained organic EL display element at the beginning of the measurement, but dark spots were generated and enlarged during the lifetime measurement, and the display quality was significantly deteriorated. The half life was 2,000 hours at an initial luminance of 300 cd / m ² .

[0050]

According to the present invention, by completely covering the structure with a sealing layer in which a barrier layer, a resin layer, and a barrier layer are sequentially laminated, when a voltage is applied, heat is generated due to a short circuit, Even if the first barrier layer is destroyed by the energy and a pinhole or a crack which becomes a passage for water vapor or oxygen is generated, the resin layer blocks the pinhole or the crack. Therefore, the pinholes and cracks connected from the first barrier layer do not come into contact with the outside air due to the second barrier layer. Accordingly, it is possible to provide a long-life organic EL display element capable of minimizing the influence of moisture, outside air, and the like, reducing deterioration with time, and maintaining initial performance for a long time, and a method of manufacturing the same.

[0051]

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a cross-sectional structure of an example of an organic EL display element of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 translucent insulating substrate 2 electrode (anode) 3 organic luminescent medium 4 opposing substrate (cathode) 5 sealing layer 6 a barrier layer 6 b barrier layer 7 resin layer

Claims (5)

[Claims] 1. An organic electroluminescent device comprising a substrate provided with an electrode, a fluorescent medium, a counter electrode, and a sealing layer covering at least the fluorescent medium and the counter electrode, wherein the sealing layer comprises at least a barrier layer, a resin layer, An organic electroluminescent display element, which is a laminate in which barrier layers are sequentially formed. 2. The organic electroluminescent display according to claim 1, wherein the barrier layer is a metal film having at least a water vapor barrier property and / or an oxygen barrier property, an inorganic film, or a laminated film thereof. element. 3. The method according to claim 1, wherein the resin layer is made of an acrylic monomer or an acrylic oligomer.
And the organic electroluminescent display device according to claim 2. 4. An organic electroluminescence device having an electrode, a fluorescent medium and a counter electrode on a substrate and a sealing layer covering at least the fluorescent medium and the counter electrode, wherein at least the structure is covered with a barrier layer. And a step of coating the barrier layer with a resin layer, a step of curing the resin layer, and a step of coating the resin layer with a barrier layer. 5. The method according to claim 4, wherein the steps from the formation of the light emitting medium to the formation of the sealing layer are continuously performed in a vacuum.