JP4178887B2 - Organic electroluminescence device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic electroluminescence element (hereinafter abbreviated as an organic EL element) used as a display such as an information display terminal or a surface emitting light source.
[0002]
[Prior art]
The organic EL element is expected as a flat panel display that replaces a cathode ray tube or a liquid crystal display because of its advantages such as a wide viewing angle, a high response speed, and low power consumption.
[0003]
An organic EL element has a structure in which an organic light emitting medium layer is sandwiched between an anode layer and a cathode layer, at least one of which is transparent, and light is generated in the organic light emitting medium layer by injecting current from both electrodes. It is.
[0004]
The organic EL element deteriorates due to moisture or oxygen in the atmosphere when the light emitting medium layer or the cathode layer is left exposed to the atmosphere. As a specific example, there is a phenomenon in which a non-light-emitting region called a dark spot occurs and expands with time.
[0005]
Means for solving this problem is disclosed in Patent Document 1, Patent Document 2, and the like. In these methods, a luminescent medium layer and a cathode layer are continuously formed under vacuum on a glass substrate on which a transparent anode layer is formed, and an EL element is covered and sealed in a dry nitrogen atmosphere with a metal or glass sealing can. Is the method.
[0006]
However, in order to manufacture such an EL element, a plurality of vacuum deposition apparatuses and nitrogen sealing apparatuses capable of transporting a glass substrate under vacuum are necessary, so that productivity is low and manufacturing cost is high. There was a problem. Further, since a glass substrate or a metal sealing can is used, there is a limit to reducing the thickness and weight of the element.
[0007]
On the other hand, in recent years, a polymer light-emitting medium layer is formed on a plastic film or glass by a wet method such as a spin coat method, a gravure printing method, or an ink jet method, and sealed with a film having a high barrier property such as a metal foil. A method is disclosed.
[0008]
The problem with this sealing method is that the adhesive resin layer is in contact with the cathode layer and that a space for enclosing the desiccant cannot be provided. For this reason, the device which lowers | hangs the moisture content and moisture permeability of an adhesive resin layer as much as possible is needed. As means for solving this problem, a method of mixing a desiccant into the adhesive resin layer is disclosed.
[0009]
However, when a barrier film such as a metal foil is bonded using an adhesive resin layer mixed with a desiccant, the shrinkage stress caused by the difference in shrinkage between the metal foil and the adhesive resin layer is not absorbed when the adhesive resin layer is cured. The barrier film such as the metal foil easily peels off.
[0010]
In order to solve this problem, there is a method of dispersing a plasticizer such as rubber fine particles in the adhesive resin layer. As a result, the residual stress is relaxed and the adhesiveness is improved, but there is a problem that the moisture permeability and water absorption rate of the adhesive resin deteriorate.
[0011]
[Patent Document 1]
JP-A-5-182759 [Patent Document 2]
JP-A-5-36475 [0012]
[Problems to be solved by the invention]
The present invention has been made in order to solve the above-mentioned problems, and the problem is that it is a thin and lightweight organic material that has excellent moisture resistance and adhesion and has a structure capable of blocking external moisture over a long period of time. It is to provide an EL element.
[0013]
[Means for Solving the Problems]
The present invention has been made to solve the above problems.
According to a first aspect of the present invention, there is provided an organic electroluminescence device having at least a transparent anode layer, an organic light emitting medium layer, a cathode layer, and a sealing layer on a translucent substrate, and preventing peeling on the sealing layer. The organic electroluminescent element is characterized in that resin fine particles are dispersed in the adhesive resin layer that is laminated and constitutes the peeling prevention layer .
According to a second aspect of the present invention, the sealing layer and the peeling prevention layer each include at least an adhesive resin layer and a barrier layer, and the sealing layer is covered with the peeling prevention layer. The organic electroluminescence device according to claim 1.
A third aspect of the invention according to claim 3 is characterized in that a desiccant is dispersed in the adhesive resin layer constituting the sealing layer. It is an electroluminescence element .
[0014]
DETAILED DESCRIPTION OF THE INVENTION
As an example of the organic EL element of the present invention and the manufacturing process thereof, a description will be given based on FIG.
FIG. 1 shows an example of the manufacturing process of the organic EL element of the present invention step by step. First, the transparent anode layer 2 is provided on the translucent substrate 1 and patterned (FIG. 1A). Thereafter, the organic light emitting medium layer 3 and then the cathode layer 4 are laminated (FIG. 1B). Further, the organic EL element is sealed with a sealing layer 5 (FIG. 1C) composed of an adhesive resin layer 6 and a barrier layer 7, and finally, a peeling prevention layer 9 composed of an adhesive resin layer 10 and a barrier layer 11 is used. By covering the organic EL element (FIG. 1D), the organic EL element of the present invention is obtained.
[0015]
As the translucent substrate 1, any substrate can be used as long as it has translucency and insulation. For example, a plastic film or sheet such as polyethylene terephthalate, polyethylene naphthalate, polypropylene, polyethersulfone, polycarbonate, cycloolefin polymer, polyarylate, polyamide, polymethyl methacrylate, glass or quartz can be used. A transparent barrier film such as an inorganic thin film, a transparent barrier film, or the like may be laminated on these substrates as necessary.
[0016]
FIG. 1A shows a transparent anode layer 2 that also serves as an extraction electrode 2a for an anode and a cathode, after the transparent anode layer 2 is formed on the translucent substrate 1 and then patterned using a photolithographic etching method or the like. The place where the extraction electrode 2b is formed is illustrated. As a material of the transparent anode layer 2, a metal oxide such as indium tin oxide, indium zinc oxide and zinc aluminum oxide, a metal thin film such as gold and platinum, and a fine particle of these metal oxide and metal are used as a binder resin. A transparent conductive ink or the like dispersed in can be used.
[0017]
As a method for forming the transparent anode layer 2, depending on the material, dry film forming methods such as resistance heating vapor deposition, electron beam vapor deposition, reactive vapor deposition, ion plating, and sputtering, gravure printing, screen A wet film forming method such as a printing method can be used.
[0018]
As a patterning method of the transparent anode layer 2, a mask vapor deposition method, a photolithography method, a wet etching method, a dry etching method, or the like can be used depending on the material and the film forming method.
[0019]
Further, in order to improve the adhesion between the translucent substrate 1 and the transparent anode layer 2, the surface of the translucent substrate 1 may be previously subjected to a surface treatment such as corona discharge treatment, plasma treatment, or UV ozone treatment. Furthermore, a single layer or a plurality of layers of an inorganic insulating film such as silicon oxide, silicon nitride, silicon oxynitride, and aluminum oxide, a metal film such as chromium and titanium, and a polymer resin film such as acrylic resin and epoxy resin , May be laminated.
[0020]
Next, the organic light emitting medium layer 3 is formed (FIG. 1B). Here, before the organic light emitting medium layer 3 is formed, surface treatment such as corona discharge treatment, plasma treatment, or UV ozone treatment is preferably performed for the purpose of surface cleaning or surface modification of the transparent anode layer 2.
[0021]
The organic light emitting medium layer 3 in the present invention is composed of a single layer or a multilayer film including at least a light emitting layer. Examples of the configuration in which the organic light emitting medium layer 3 is a multilayer include a hole transport layer, an electron transporting light emitting layer or a hole transporting light emitting layer, a two layer structure comprising an electron transport layer, a hole transport layer, and light emission A three-layer structure including a layer and an electron transport layer, or further functional differentiation, can be multilayered.
[0022]
As a material for the hole transport layer, 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, Low molecular materials such as aromatic amines such as N′-diphenyl-1,1′-biphenyl-4,4′-diamine, polymer materials such as polythiophene and polyaniline, polythiophene oligomer materials, and other existing hole transport materials You can choose from.
[0023]
As the material for the light emitting layer, 9,10-diarylanthracene derivatives, pyrene, coronene, perylene, rubrene, 1,1,4,4-tetraphenylbutadiene, tris (8-quinolinolato) aluminum complex, tris (4-methyl- 8-quinolinolato) aluminum complex, bis (8-quinolinolato) zinc complex, tris (4-methyl-5-trifluoromethyl-8-quinolinolato) aluminum complex, tris (4-methyl-5-cyano-8-quinolinolato) aluminum Complex, bis (2-methyl-5-trifluoromethyl-8-quinolinolato) [4- (4-cyanophenyl) phenolate] aluminum complex, bis (2-methyl-5-cyano-8-quinolinolato) [4- ( 4-cyanophenyl) phenolate] aluminum complex, Lis (8-quinolinolato) scandium complex, bis [8- (para-tosyl) aminoquinoline] zinc complex and cadmium complex, 1,2,3,4-tetraphenylcyclopentadiene, pentaphenylcyclopentadiene, poly-2,5 -Diheptyloxy-para-phenylene vinylene, coumarin phosphor, perylene phosphor, pyran phosphor, anthrone phosphor, porphyrin phosphor, quinacridone phosphor, N, N'-dialkyl-substituted quinacridone fluorescence , Naphthalimide-based phosphors, N, N′-diaryl-substituted pyrrolopyrrole-based phosphors, polymer materials such as polyfluorene, polyparaphenylene vinylene, polythiophene, and other existing light-emitting materials Can do.
[0024]
As a material for the electron transport layer, 2- (4-bifinylyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole, 2,5-bis (1-naphthyl) -1, Examples include 3,4-oxadiazole, oxadiazole derivatives, bis (10-hydroxybenzo [h] quinolinolato) beryllium complexes, and triazole compounds.
[0025]
The organic light emitting medium layer 3 may be formed by vacuum evaporation such as resistance heating or electron beam, or coating such as spin coating, spray coating, flexo, gravure, roll coating, or intaglio offset depending on the material. Method and printing method can be used. The thickness of the organic light emitting medium layer 3 is 1000 nm or less, preferably 50 to 150 nm, even in a single layer or multiple layers.
[0026]
Next, the cathode layer 4 is formed (FIG. 1B). As a material for the cathode layer 4, it is preferable to use a substance having a high electron injection efficiency. Specifically, a single metal such as Mg, Al, or Yb is used, or a compound such as Li, oxidized Li, or LiF is sandwiched by about 1 nm at the interface in contact with the light emitting medium, and Al or Cu having high stability and conductivity is placed. Laminated and used. Alternatively, in order to achieve both electron injection efficiency and stability, one or more metals such as Li, Mg, Ca, Sr, La, Ce, Er, Eu, Sc, Y, and Yb having a low work function and stable Ag, Al An alloy system with a metal element such as Cu or Cu is used. Specifically, alloys such as MgAg, AlLi, and CuLi can be used.
[0027]
As a method for forming the cathode layer 4, a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, a sputtering method, a laminating method, or the like can be used. The thickness of the cathode is preferably about 10 nm to 1000 nm.
[0028]
Next, the sealing layer 5 is laminated on the cathode layer 4 (FIG. 1C). Here, in order to protect the cathode layer 4, before laminating the sealing layer 5, an inorganic insulating film such as silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, acrylic resin, epoxy resin, etc. A polymer resin film or a metal film such as chromium or titanium may be a single layer or a stacked layer.
[0029]
The sealing layer 5 is preferably composed of at least an adhesive resin layer 6 and a barrier layer 7.
As the adhesive resin layer 6, a thermosetting adhesive resin such as an epoxy resin, an acrylic resin, silicone, or a phenol resin, a photocurable adhesive resin, a thermoplastic adhesive resin, or the like can be used. In particular, it is preferable to use an epoxy resin adhesive resin that is excellent in moisture resistance and water resistance and has little shrinkage during curing.
[0030]
Further, in the adhesive resin layer 6, it is preferable to disperse the desiccant 8 in the adhesive resin layer 6 in order to reduce the moisture and moisture permeability in the resin as much as possible.
As a material for the desiccant 8, at least one or more chemical adsorption desiccants such as barium oxide and calcium oxide and physical adsorption desiccants such as zeolite can be used. In particular, a desiccant is mixed to remove the initial moisture content of the adhesive resin, and after removing the desiccant that has absorbed moisture, a new desiccant is added to absorb moisture from the outside. It is more preferable to use the mixture.
[0031]
The film thickness of the adhesive resin layer 6 is preferably 0.001 mm to 1 mm. This is because, when the thickness of the adhesive resin layer 6 is thicker than 1 mm, there arises a problem that the organic EL element is deteriorated due to an increase in the moisture permeation amount from the end portion, and a problem that the curing shrinkage amount is increased. It is. On the other hand, when the thickness is less than 0.001 mm, the organic EL element may come into contact with the barrier layer 7, and when the metal foil is used as the barrier layer 7, there is a problem that the organic EL element is short-circuited.
As a method for forming the adhesive resin layer 6, a coating method such as roll coating, spin coating, screen printing, spray coating, or the like can be used depending on the material.
[0032]
As the desiccant 8, it is preferable to adjust the particle diameter and the amount of dispersion according to the film thickness of the adhesive resin layer 6. The particle size is preferably 50% or less of the film thickness of the adhesive resin layer 6 so that the cathode layer 4 is not damaged when the sealing layer 5 is bonded. Further, the amount of dispersion is preferably about 1 to 30 wt% of the adhesive resin so as not to affect the moisture permeability and the adhesive force.
[0033]
For the barrier layer 7, it is desirable to select a material excellent in humidity barrier and gas barrier properties. On a plastic film such as polyethylene terephthalate, polyethylene naphthalate, or polycarbonate, a metal oxide such as silicon oxide or aluminum oxide, or silicon nitride is used. , Metal nitrides such as aluminum nitride, metal fluorides such as aluminum fluoride, films deposited with metals and alloys such as aluminum, nickel and copper, and metal foils and alloy foils made of these metal materials, glass plates and metal plates Etc. can be used. In particular, it is preferable to use a metal foil or an alloy foil that can be reduced in thickness and weight and has excellent humidity barrier and gas barrier properties. In order to facilitate the handling of these metal foils, a plastic film such as polyethylene terephthalate may be laminated or used.
[0034]
Next, in order to prevent exfoliation of the sealing layer 5 and improve adhesiveness, a peeling prevention layer 9 is laminated so as to cover the entire sealing layer 5 (FIG. 1D). The peeling prevention layer 9 should just be provided with the adhesive resin layer 10 at least.
As the adhesive resin layer 10, a thermosetting adhesive resin made of an epoxy resin, an acrylic resin, silicone, a phenol resin, a photocurable adhesive resin, a thermoplastic adhesive resin, or the like can be used. Compared with the adhesive resin layer 6 constituting the sealing layer 5, it is desirable to use a resin that further suppresses shrinkage at the time of curing, in particular, an epoxy resin that is excellent in moisture resistance and water resistance and has little shrinkage at the time of curing. It is preferable to use a system adhesive resin.
[0035]
The adhesive resin layer 10 is desirably mixed with resin fine particles 12 in order to relieve residual stress at the time of curing, prevent the separation of adjacent layers, and improve adhesiveness. As the material of the resin fine particles 12, plastic fine particles, rubber fine particles such as acrylic rubber and nitrile rubber can be used as a single component or multiple components. In addition, after removing the moisture content of the adhesive resin layer 10 in advance using a desiccant, the desiccant that has adsorbed moisture may be removed, and the resin fine particles 12 may be mixed. You may mix and use a desiccant newly. As a material for the desiccant, at least one or more chemical adsorption desiccants such as barium oxide and calcium oxide and physical adsorption desiccants such as zeolite can be used.
[0036]
The particle diameter of the resin fine particles 12 is preferably 0.001 mm to 0.1 mm, and the amount of dispersion is preferably about 1 to 30 wt%. The film thickness of the adhesive resin layer 10 is preferably 0.01 mm to 1 mm. This is because when the thickness of the adhesive resin layer 10 is smaller than 0.01 mm, the ratio of the resin fine particles 12 directly contacting the barrier layer 7 and the barrier layer 11 without the adhesive resin increases, and the adhesive force decreases. This is because such a problem arises. On the other hand, if the thickness is greater than 1 mm, there is a problem that the organic EL element deteriorates due to an increase in the moisture permeation amount from the end portion, and a problem that the amount of curing shrinkage increases.
As a method for forming the adhesive resin layer 10, a coating method such as roll coating, spin coating, screen printing, spray coating, or the like can be used depending on the material.
[0037]
The peeling prevention layer 9 can fulfill its function even if it has a structure composed only of the adhesive resin layer 10, but it is more preferable to provide a barrier layer 11 in order to improve the moisture resistance of the entire organic EL element.
For the barrier layer 11, it is desirable to select a material excellent in humidity barrier and gas barrier properties. On a plastic film such as polyethylene terephthalate, polyethylene naphthalate, or polycarbonate, a metal oxide such as silicon oxide or aluminum oxide, or silicon nitride is used. , Metal nitrides such as aluminum nitride, metal fluorides such as aluminum fluoride, films deposited with metals and alloys such as aluminum, nickel and copper, and metal foils and alloy foils made of these metal materials, glass plates and metal plates Etc. can be used. In particular, it is preferable to use a metal foil or an alloy foil that can be reduced in thickness and weight and has excellent humidity barrier and gas barrier properties. In order to facilitate the handling of these metal foils, a plastic film such as polyethylene terephthalate may be laminated or used.
[0038]
【Example】
Hereinafter, an example of an embodiment of an EL device and a manufacturing method thereof according to the present invention will be described. Example 1 and Comparative Examples 1 to 3 will be described with reference to FIG.
[0039]
(Example 1)
150 nm of indium tin oxide (ITO) was formed as the transparent anode layer 2 on the glass substrate as the translucent substrate 1 using the sputtering method. Next, the ITO film as the transparent anode layer 2 was patterned by using a photolithography method and a wet etching method to form a transparent anode layer 2 also serving as an extraction electrode 2a and a cathode extraction electrode 2b (FIG. 1A). ).
Next, after the surface of the ITO film is treated with UV ozone, poly [2-methoxy-5- (2′-ethyl-hexyloxy) -1,4-phenylenevinylene] (MEHPPV) is spin-coated as the organic light emitting medium layer 3. The cathode layer 4 was formed by stacking Ca (20 nm) and Ag (200 nm) in this order by the vacuum deposition method (FIG. 1B).
Furthermore, the sealing layer 5 was laminated | stacked on the cathode layer 4 (FIG.1 (c)). After laminating an epoxy resin thermosetting adhesive mixed with 5 wt% of barium oxide powder (drying agent 8) as the adhesive resin layer 6, an aluminum foil (50 μm) was laminated as the barrier layer 7.
Finally, the peeling prevention layer 9 was laminated so as to cover the entire sealing layer 5 (FIG. 1 (d)). As the adhesive resin layer 10, an epoxy resin thermosetting adhesive mixed with acrylic rubber fine particles (resin fine particles 12) having a particle diameter of 0.01 mm was laminated, and then an aluminum foil (50 μm) was laminated as the barrier layer 11. .
The obtained organic EL device was stored in a constant temperature bath at 40 ° C. and 90% RH for 1000 hours. As a result, both the barrier layer 7 and the barrier layer 11 did not peel together, and the organic EL device was allowed to emit light. No spot expansion was observed.
[0040]
(Comparative Example 1)
In the organic EL element of Example 1, the organic EL element in the state of FIG. 1C was stored in a constant temperature bath of 40 ° C. and 90% RH without forming the peeling prevention layer 9, and as a result, the barrier layer 7 was It peeled off from the adhesive resin layer 6, and the organic EL element did not light-emit.
[0041]
(Comparative Example 2)
In the organic EL element of Example 1, the barrier layer 7 and the barrier layer 11 were peeled off as a result of being stored in a constant temperature bath of 40 ° C. and 90% RH without mixing the desiccant 8 in the adhesive resin layer 6. However, dark spots occurred and expanded, and 30% of the pixel area was occupied by dark spots.
[0042]
(Comparative Example 3)
In the organic EL device of Example 1, the barrier resin layer 10 and the barrier layer 11 were peeled off as a result of being stored in a constant temperature bath at 40 ° C. and 90% RH without mixing the rubber fine particles 12 in the adhesive resin layer 10. As a result, the organic EL element did not emit light.
[0043]
【The invention's effect】
According to the first aspect of the present invention, by providing the sealing layer 5 and the peeling prevention layer 9 on the organic EL element, it is excellent in moisture resistance and adhesiveness, can block external moisture for a long time, and is thin and lightweight. An organic EL element can be provided.
According to the invention which concerns on Claim 2, the adhesiveness of the sealing layer 5 improves by providing the peeling prevention layer 9 so that the sealing layer 5 may be coat | covered, and it can hold | maintain moisture resistance over a long period of time. According to the invention of claim 3. By mixing the desiccant 8 into the adhesive resin layer 6 of the sealing layer 5, moisture resistance can be improved.
According to the invention which concerns on Claim 4, adhesiveness can be improved by mixing the resin microparticles | fine-particles 12 in the adhesive resin 10 of the peeling prevention layer 9. FIG.
[0044]
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a manufacturing process of an organic electroluminescence element of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Translucent board | substrate 2 Transparent anode layer 2a Extraction electrode 2b for anodes Extraction electrode 3 for cathodes 3 Organic light emitting medium layer 4 Cathode layer 5 Sealing layer 6 Adhesive resin layer 7 Barrier layer 8 Desiccant 9 Peeling prevention layer 10 Adhesive resin Layer 11 Barrier layer 12 Resin fine particles

Claims (3)

In an organic electroluminescence device having at least a transparent anode layer, an organic light emitting medium layer, a cathode layer, and a sealing layer on a translucent substrate, a peeling prevention layer is laminated on the sealing layer , and the peeling prevention layer is configured. An organic electroluminescent element , wherein resin fine particles are dispersed in the adhesive resin layer .   2. The organic electro according to claim 1, wherein each of the sealing layer and the peeling prevention layer comprises at least an adhesive resin layer and a barrier layer, and the sealing layer is covered with the peeling prevention layer. Luminescence element.   The organic electroluminescence device according to claim 1, wherein a desiccant is dispersed in the adhesive resin layer constituting the sealing layer.

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