JP4491894B2 - Organic electroluminescence display element and method for manufacturing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic EL display element that is a light-emitting display as a display device and is one of flat panel displays, and a method for manufacturing the organic EL display element.
[0002]
[Prior art]
Since an organic electroluminescence display element (hereinafter referred to as an organic EL display element) is a self-luminous type, a display using the organic electroluminescence display element has a feature of exhibiting high luminance and a high viewing angle, and can be driven at a low voltage. .
[0003]
The organic EL display element is a structure in which an organic substance is sandwiched between an anode electrode and a cathode electrode facing each other, and the organic substance further includes a light emitting layer, a hole injection layer / light emitting layer, a light emitting layer / electron injection layer, a hole injection. A layered body such as a layer / a light emitting layer / an electron injection layer, or a structure in which a light emitting material is mixed with at least one of a hole injection material and an electron injection material.
[0004]
When the organic EL display element light emitting material, hole injecting material, organic material that is an electron injecting material, and the electrode (cathode) line provided on the organic material are left exposed to the atmosphere, they are exposed to atmospheric moisture, oxygen, etc. Deteriorated by Due to the influence of moisture, oxygen, etc. in the atmosphere, for example, peeling occurs at the interface between the organic substance and the electrode, or the constituent material is altered. As a result, a non-light emitting region is generated, or light emission of a predetermined quality cannot be maintained.
[0005]
As a method for solving this problem, as described in JP-A-5-36475, JP-A-5-89959, JP-A-7-169567, etc., a nitrogen atmosphere or other inert gas atmosphere Among them, a technique for blocking moisture, oxygen, etc. in the atmosphere by tightly fixing an airtight case or the like covering an organic EL display element is known.
[0006]
However, in order to completely block moisture, oxygen, etc. in the atmosphere, the hermetic case is formed of metal or glass, which is about 1/2 to 1/3 of the thickness and weight of the organic EL display element. Therefore, when the organic EL display element is further reduced in thickness and weight, an airtight case that covers the organic EL display element becomes an obstacle.
[0007]
Further, as described in JP-A-4-73886, there is a method of providing a protective film of an organic substance such as polybutadiene or an inorganic substance such as SiO ₂ on the organic EL display element by vapor deposition or sputtering. Due to the presence of defects such as pinholes and cracks, the sealing was not sufficient.
[0008]
[Problems to be solved by the invention]
The present invention has been made to solve these problems, and by improving sealing defects, the influence of moisture, oxygen, etc. in the atmosphere is eliminated as much as possible, there is little deterioration over time, and initial performance is improved. The present invention provides a thin and light-weight organic EL display element that can be maintained for a long time and a method for manufacturing the same.
[0009]
[Means for Solving the Problems]
In order to achieve the above object in the present invention, first, in claim 1 , an organic light emitting layer is sandwiched between an electrode and a counter electrode, at least one of which is transparent or translucent on the substrate, In the organic electroluminescence display element having a sealing layer to cover, the sealing layer is a first sealing layer made of an inorganic material, a second sealing layer made of a metal alkoxide formed on the first sealing layer, Organic having at least a third sealing layer made of an inorganic material formed on the second sealing layer and a fourth sealing layer made of a metal alkoxide formed on the third sealing layer An electroluminescent display element is provided.
According to a second aspect of the present invention, the organic light emitting layer is sandwiched between at least one of the transparent and translucent electrode and the counter electrode on the substrate, and the sealing layer covering the organic light emitting layer and the counter electrode is made of an inorganic substance. A sealing layer, a second sealing layer made of a metal alkoxide formed on the first sealing layer, a third sealing layer made of an inorganic material formed on the second sealing layer, and a third sealing A fourth sealing layer made of a metal alkoxide formed on the layer, and a method for producing an organic electroluminescence display element, comprising at least a sealing layer made of a metal alkoxide in a vacuum Provided is a method for producing an organic electroluminescence display element characterized by a film forming step.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of the organic EL display element of the present invention will be described in detail according to a manufacturing process in a case where an electrode on a substrate is an anode and a counter electrode is a cathode.
[0011]
First, a transparent electrode layer is formed on a light-transmitting insulator substrate by sputtering or the like, and the transparent electrode layer is patterned by photolithography and wet etching to form a plurality of line-shaped electrodes (anodes).
[0012]
As the substrate in the present invention, a quartz substrate, a glass substrate, a plastic substrate, or the like can be used.
[0013]
As a material for the plurality of electrodes (anodes) in the present invention, transparent electrode materials such as ITO (indium tin composite oxide), indium zinc composite oxide, and zinc aluminum composite oxide can be used.
[0014]
In order to reduce the resistance, a metal such as copper, chromium, aluminum, titanium, or a laminate thereof can be partially provided on the anode as an auxiliary electrode. Moreover, although it is not necessary to form the insulating layer for short circuit prevention on an anode, it does not limit to not having an insulating layer.
[0015]
The organic light emitting layer in the present invention can be formed in a single layer structure containing a fluorescent material or a multilayer structure.
[0016]
Examples of the organic light emitting layer in the case of forming a multilayer film include a hole injection transport layer / electron transport light emitting layer or a two layer structure comprising a hole transport light emitting layer / electron transport layer and a hole injection transport layer / light emission. There is a three-layer structure composed of a layer / electron transport layer. Further, it is possible to form a multilayer, and each layer is formed on the substrate in order.
[0017]
Examples of the hole injecting and transporting layer 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-tolylamino) Phenyl) cyclohexane, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine, N, N′-di (1-naphthyl)- It can be selected from aromatic amine-based low molecular hole injection transport layers such as N, N′-diphphenyl-1,1′-biphenyl-4,4′-diamine and other existing hole transport materials.
[0018]
Examples of the light-emitting material include 9,10-diarylanthracene derivatives, pyrene, coronene, perylene, rubrene, 1,1,4,4-tetraphenylbutadiene, tris (8-quinolinolato) aluminum complex, tris (4-methyl- 8quinolinolato) 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, Su (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 Body, naphthalimide-based phosphor, N, N′-diaryl-substituted pyrrolopyrrole-based phosphor, etc., and these can be used alone or mixed with other low-molecular materials or polymer materials.
[0019]
Examples of electron transport materials include 2- (4-bifinylyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole and oxadiazole derivatives synthesized by Hamada et al. Journal, page 1540, 1991), bis (10-hydroxybenzo [h] quinolinolato) beryllium complex, triazole compounds described in JP-A-7-90260, and the like.
[0020]
The low molecular organic light emitting layer can be formed by a vacuum deposition method. The film thickness of the low molecular weight organic light-emitting layer is 1 μm or less, preferably 50 to 150 nm, even when formed by a single layer or a stacked layer.
[0021]
In addition, the organic light-emitting layer includes polyparaphenylene vinylene, poly (2-methoxy-5- (2′ethylexoxy) -1,4-paraphenylene vinylene, poly (3-alkylthiophene), poly (9,9-diaxylfluorene). ), Conjugated polymer systems such as poly (paraphenylene), poly (N-vinylcarbazole), 2,5-bis (5-t-butyl-2,5-benzoxazoyl) thiophene, zinc bis-benzothiazole phenolate A known polymer material such as a polymer dispersion system such as a polymer dispersion can be used for the polymer-based organic light-emitting layer, such as N, N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, propylene. After dissolving in an organic solvent such as carbonate or γ-butyrolactone or water, spin coating, cast It can be formed by a coating method such as a coating method, a dipping method, a bar coating method, a roll coating method, a gravure coating method, a micro gravure method, etc. The film thickness of the polymer organic light emitting layer is 1 nm to 10 μm, preferably 10 nm to 1 μm.
[0022]
As the material of the counter electrode (cathode), a substance having high electron injection efficiency is used. 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 organic light emitting layer, and Al or Cu having high stability and conductivity is placed. Laminated and used.
[0023]
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, which are low work functions, and stable Ag, An alloy system with a metal element such as Al or Cu is used. Specifically, alloys such as MgAg, AlLi, and CuLi can be used.
[0024]
As a method for forming the counter electrode (cathode), a vacuum evaporation method, an electron beam evaporation method, a sputtering method, or the like can be used depending on the material. The thickness of the counter electrode is desirably about 10 nm to 1 μm.
[0025]
Thereafter, a first sealing layer and a second sealing layer are sequentially formed in order to suppress deterioration of the organic light emitting layer and the counter electrode due to moisture and oxygen in the atmosphere. First, the organic light emitting layer and the counter electrode are completely covered with the first sealing layer. The first sealing layer is made of an inorganic material having a water vapor barrier property and / or an oxygen barrier property.
[0026]
The first sealing layer may have a multilayer structure of the inorganic material. In this case, if the first layer is made of an insulating material, the second and subsequent layers are simple metals such as magnesium, aluminum, titanium, and silver. Alternatively, an alloy may be used, and for example, a multilayer structure such as GeO / Al / GeO can be used.
[0027]
As a method for forming the first sealing layer, a vacuum deposition method, a sputtering method, a CVD method, or the like can be used depending on the material. The thickness of the sealing is not limited as long as the water vapor barrier property and / or the oxygen barrier property are sufficient, but preferably about 0.1 μm to 10 μm.
[0028]
Next, since there are defects such as pinholes and cracks in the first sealing layer alone and it cannot be said that the sealing is sufficient, the second sealing layer is laminated on the first sealing layer. The layer, the organic light emitting layer and the counter electrode are completely covered with the second sealing layer. A first sealing layer made of an inorganic material and a second sealing layer made of a metal alkoxide, a hydrolyzate of the metal alkoxide, or a mixture thereof are sequentially laminated so that the second sealing layer becomes the first sealing layer. Fill and reinforce defects such as pinholes and cracks generated in the layer. Therefore, the structure of the sealing layer composed of the first sealing layer and the second sealing layer is densely formed, exhibits high gas barrier properties, and has moisture resistance.
[0029]
The metal alkoxide used in the present invention has a general formula such as tetraethoxysilane [Si (OC ₂ H ₅ ) ₄ ], triisopropoxy aluminum [Al (O-2′-C ₃ H ₇ ) ₃ ],
M (OR) _n
(M: metal such as Si, Ti, Al and Zr, R: alkyl group such as CH ₃ and C ₂ H ₅ ).
[0030]
The second sealing layer is formed by coating a metal alkoxide, a hydrolyzate thereof, an aqueous solution containing a mixture thereof, or a coating agent mainly composed of a water / alcohol mixed solution with an inert gas such as argon gas or a nitrogen atmosphere. Among them, it can be applied by a conventionally known means such as a dipping method, a roll coating method, a screen printing method, a spray method, etc., but there is a possibility that the organic substance and the cathode are contaminated by moisture in the coating agent. Therefore, as a method of forming without using a coating agent, a vacuum process such as a vacuum deposition method or a CVD method can be used. The thickness of the second sealing layer is not limited as long as defects such as pinholes and cracks in the first sealing layer can be sufficiently filled, but it is preferably about 0.1 μm to 10 μm.
[0031]
In addition, it is possible to manufacture an organic EL display element using the materials and the forming method described above, in which the electrode on the substrate is a cathode and the counter electrode is an anode. Further, in order to further improve the barrier property, the same sealing film as the first sealing layer and the second sealing layer described above are used as the third sealing layer and the fourth sealing layer, respectively. It may be laminated to make the sealing layer more multilayer. Furthermore, the sealing layer described above is made of metals such as Al, Fe, Ni, Zn and alloys thereof, inorganic materials such as glass and ceramics, acrylic, fluorine, polycarbonate, polyester, polyamide, polystyrene, polyethylene, You may coat | cover with the protective layer which consists of vapor deposition films of resin, such as a polypropylene.
[0032]
【Example】
[Example 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 glass substrate 1 by a sputtering method. Furthermore, in order to improve transparency and conductivity, heat treatment was performed in air at 230 ° C. for 1 hour to crystallize the ITO film.
[0033]
Next, the ITO film was patterned by a photolithography method and a wet etching method to form an electrode 2.
[0034]
Next, copper phthalocyanine, N, N′-di (1-naphthyl) -N, N′-diphenyl-1,1′-biphenyl-4,4′-diamine, tris (8-quinolinolato) aluminum as the organic light emitting layer 3 The complexes were sequentially vacuum-deposited with thicknesses of 10 nm, 40 nm, and 50 nm, and then binary co-deposition was performed while rotating the substrate with MgAg as the counter electrode (cathode) 4.
[0035]
Next, SiO ₂ , Al, SiO ₂ , and Al were vacuum-deposited in order of 200 nm, 200 nm, 200 nm, and 200 nm as the first sealing layer 5 on the counter electrode 4.
[0036]
Next, tetraethoxysilane [Si (OC ₂ H ₅ ) ₄ ] as a second sealing layer 6 was vacuum deposited on the first sealing layer 5 to a thickness of 200 nm. The obtained organic EL display element did not observe dark spot expansion, and had an initial luminance of 300 cd / m ² and a half-life of 5500 hours.
[0037]
[Comparative Example 1]
An organic EL display element was produced in the same manner as in Example 1 except that the second sealing layer was not provided. In the obtained organic EL display element, dark spot expansion was observed, and the display quality was slightly deteriorated. The initial luminance was 300 cd / m ² and the half life was 1000 hours.
[0038]
[Comparative Example 2]
A counter electrode (cathode) was simply vacuum-deposited without forming the first sealing layer and the second sealing layer in the organic EL display device produced in the same process as in Example 1. In the obtained organic EL display element, dark spots were observed to expand, and the display quality was remarkably deteriorated. The initial luminance was 300 cd / m ² and the half life was 70 hours.
[0039]
【The invention's effect】
According to the present invention, the first sealing layer is covered with the second sealing layer, and defects such as pinholes and cracks existing in the first sealing layer are filled, thereby minimizing the influence of moisture and outside air. It is possible to provide a long-life organic EL display element that can be excluded, has little deterioration over time, and can maintain initial performance for a long time, and a method for manufacturing the same.
[0040]
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a cross-sectional structure of an example of an organic EL display element of the present invention.
FIG. 2 is an explanatory view showing a cross-sectional structure of an example of a conventional organic EL display element.
[Explanation of symbols]
1 Substrate 2 Electrode (Anode)
3 Organic light emitting layer 4 Counter electrode (cathode)
5 First sealing layer 6 Second sealing layer

Claims (2)

  In an organic electroluminescence display element having at least one of a transparent or translucent electrode and a counter electrode sandwiched between an organic light emitting layer and a sealing layer covering the organic light emitting layer and the counter electrode, the sealing layer includes: A first sealing layer made of an inorganic material; a second sealing layer made of a metal alkoxide formed on the first sealing layer; and a third sealing layer made of an inorganic material formed on the second sealing layer; And an organic electroluminescence display element having at least a fourth sealing layer made of a metal alkoxide formed on the third sealing layer. An organic light-emitting layer is sandwiched between at least one of a transparent or translucent electrode and a counter electrode on the substrate, and a sealing layer covering the organic light-emitting layer and the counter electrode includes a first sealing layer made of an inorganic material and a first sealing layer. A second sealing layer made of a metal alkoxide formed on the stopper layer, a third sealing layer made of an inorganic material formed on the second sealing layer, and a metal alkoxide formed on the third sealing layer A method for producing an organic electroluminescence display element comprising at least a fourth sealing layer comprising:
The manufacturing method of the organic electroluminescent display element characterized by forming the sealing layer which consists of a metal alkoxide at least in a vacuum.

Images