JPH08236271A - Organic electroluminescent device and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] [Object] To provide an organic electroluminescent device capable of maintaining stable light emitting characteristics for a long period of time and suppressing the generation of dark spots. [Structure] An organic electroluminescent device comprising a substrate, an anode, an organic light emitting layer, and a cathode laminated on the substrate, and a protective layer, a sealing layer, and an outside air blocking material layer formed on the outer surface of the laminate in this order from the inside. The organic electroluminescent element in which the sealing layer is mainly composed of a resin that satisfies the following conditions (a), (b), and (c). (A) The elongation specified in JIS K 6911 is 100.
%that's all. (B) Shore A hardness specified by JIS K 6301 is 20 or more. (C) Glass transition point of -40 ° C or lower, -40 to +10
It exhibits rubber-like elasticity in the temperature range of 0 ° C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent device and a method for manufacturing the same, and more particularly, to a method for encapsulating a thin film type device which emits light by applying an electric field to a light emitting layer made of an organic compound. Is.

[0002]

2. Description of the Related Art Conventionally, as a thin film type electroluminescence (EL) element, Zn which is an inorganic material 〓-〓 group compound semiconductor is used.
It is general that S, CaS, SrS, etc. are doped with Mn or a rare earth element (Eu, Ce, Tb, Sm, etc.), which is the emission center, but the EL element made from the above inorganic material is 1). AC drive is required (50 to 1000 Hz), 2) high drive voltage (up to 200 V), 3) full colorization is difficult (especially blue is a problem), and 4) peripheral drive circuit costs are high. ing.

However, in recent years, in order to improve the above problems,
EL devices using organic thin films have been developed. In particular, in order to improve the light emission efficiency, the type of electrode is optimized for the purpose of improving the efficiency of carrier injection from the electrode, and the organic hole transport layer made of an aromatic diamine and the organic light emission made of an aluminum complex of 8-hydroxyquinoline. Of an organic electroluminescent device provided with a layer (Appl. Phy
s. Lett. , 51, p. 913, 1987), the luminous efficiency has been greatly improved as compared with the conventional EL device using a single crystal such as anthracene, and is close to practical characteristics.

In addition to the electroluminescence device using the low molecular weight material as described above, poly (p-phenylene vinylene) (Nature, 347, 539) is used as a material for the organic light emitting layer.
P., 1990, etc.), poly [2-methoxy-5- (2-
Ethylhexyloxy) -1,4-phenylene vinylene] (Appl. Phys. Lett., 58, 19
82, etc.), poly (3-alkylthiophene) (Jp
n. J. Appl. Phys, Vol. 30, L1938 et al.) And other electroluminescent devices using polymer materials, and devices such as polyvinylcarbazole mixed with low-molecular light emitting materials and electron transfer materials (applied physics, Vol. 61). , 10
Page 44, 1992) is also under development.

In the organic electroluminescent device as described above, indium tin oxide (IT) is usually used as the anode.
A transparent electrode such as O) is used, and a metal electrode having a low work function such as a magnesium alloy, an aluminum-lithium alloy, or calcium is used as the cathode in order to efficiently inject electrons. These cathode materials are easily oxidized by moisture and oxygen in the atmosphere, and as a result, the cathode is peeled from the organic layer to generate defects generally referred to as dark spots (indicating a portion that does not emit light on the light emitting surface of the device). The number and size of dark spots in this organic electroluminescent device increase during long-term storage or driving of the device,
For this reason, the device is made unstable and the life is shortened. Therefore, in order to improve the stability and the reliability of the organic electroluminescence device, sealing for protecting the device from moisture and oxygen in the atmosphere is essential.

As a method for sealing an organic electroluminescence device, a method of molding with an acrylic resin (Japanese Patent Laid-Open No. 3-37991) and a method of putting P ₂ O ₅ together in an airtight case and shielding from the outside air (Japanese Patent Laid-Open No. 3-37991) 261091), a method of forming a protective film of a metal oxide or the like and then making it airtight using a glass plate or the like (JP-A-4-212284), a method of providing a plasma polymerized film and a photocurable resin layer ( JP-A-5
No. -36475), a method of holding it in an inert liquid made of fluorinated carbon (JP-A-4-363890, etc.), and a method of holding it in a silicone oil after providing a polymer protective film (JP-A-5-36). No. 36475), a method of adhering a glass plate coated with polyvinyl alcohol on a protective film such as an inorganic oxide with an epoxy resin (Japanese Patent Laid-Open No. 5-89).
959), a method of encapsulating in liquid paraffin or silicone oil (JP-A-5-129080),
Method using UV curable resin (Japanese Patent Laid-Open No. 5-18275)
No. 9, etc.) and the like are disclosed.

[0007]

However, none of the conventional methods for sealing an organic electroluminescent device has been satisfactory. For example, the method of simply enclosing the element in an airtight structure together with a hygroscopic agent is insufficient in suppressing dark spots. Further, the method of holding in fluorinated carbon (for example, Fluorinert under the trade name) or silicone oil not only complicates the sealing step by including the step of injecting a liquid, but also increases the number of dark spots completely. There is also a problem in that the liquid cannot penetrate the cathode, and rather the liquid penetrates into the interface between the cathode and the organic layer and promotes peeling of the cathode. The method of adhesion-sealing with an ultraviolet curable resin is not practical because the element contained in the solvent contained in the adhesive may be damaged and the element may be damaged by ultraviolet rays, and the cathode may peel from the organic layer due to stress strain during curing. The sealing method using epoxy resin or acrylic resin is
At present, it is insufficient as an adhesive for sealing because the element is largely damaged by curing.

The deterioration of the organic electroluminescent device due to the dark spots and the unstable emission characteristics are a serious problem for a light source such as a backlight of a facsimile, a copying machine, a liquid crystal display, and a flat panel display. This is also a characteristic not desirable as a display element.

In view of the above situation, the present inventor has conducted extensive studies for the purpose of providing an organic electroluminescent device capable of maintaining stable light emitting characteristics for a long period of time and suppressing the generation of dark spots. And (b) the organic electroluminescent device has an elongation of 100 defined by JIS K 6911.
% Or more, (b) Shore A hardness specified by JIS K 6301 is 20 or more, and (c) glass transition point is -4.
It was found that the above problems can be solved by providing a sealing layer containing a resin exhibiting rubber-like elasticity in the temperature range of -40 to + 100 ° C at 0 ° C or less, and the present invention has been completed. It was

[0010]

That is, the gist of the present invention is that an anode, an organic light emitting layer and a cathode are laminated on a substrate,
An organic electroluminescence device comprising a protective layer, a sealing layer, and an outside air blocking material layer formed in this order from the inside on the outer surface of the laminate, wherein the sealing layer is defined in (a) JIS K 6911. Elongation of 100% or more, (b) JIS K 6301
The Shore A hardness is 20 or more and (c) the glass transition point is −40 ° C. or lower, and a resin having rubber-like elasticity in a temperature range of −40 to + 100 ° C. is contained as a main component. An organic electroluminescent device and a method for manufacturing the same.

Hereinafter, a method for manufacturing an organic electroluminescent device of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing a structural example of a general organic electroluminescent device used in the present invention, where 1 is a substrate, 2 is an anode, 3 is an organic light emitting layer, and 4 is a cathode.

The substrate 1 serves as a support for the organic electroluminescence device, and a plate of quartz or glass, a metal plate or metal foil, a plastic film or sheet, etc. is used. In particular, a glass plate and a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, and polysulfone are preferable. When using a synthetic resin substrate, it is necessary to pay attention to the gas barrier property. If the gas barrier property of the substrate is too low, the organic electroluminescent element may deteriorate due to the outside air passing through the substrate, which is not preferable. Therefore, a method of providing a dense silicon oxide film or the like on the synthetic resin substrate to secure the gas barrier property is also a preferable method.

An anode 2 is provided on the substrate 1, and the anode 2 plays a role of injecting holes into the organic light emitting layer. This anode is usually a metal such as aluminum, gold, silver, nickel, palladium, platinum, a metal oxide such as an oxide of indium and / or tin, a halogenated metal such as copper iodide, carbon black, or poly. (3-
Methylthiophene), polypyrrole, polyaniline, and other conductive polymers. The anode 2 is usually formed by a sputtering method, a vacuum vapor deposition method, or the like. In the case of fine particles of metal such as silver, fine particles of copper iodide, carbon black, fine particles of conductive metal oxide, fine particles of conductive polymer, etc., they are dispersed in an appropriate binder resin solution and then placed on the substrate 1. The anode 2 can also be formed by applying to Further, in the case of a conductive polymer, a thin film may be directly formed on the substrate 1 by electrolytic polymerization, or the conductive polymer may be applied on the substrate 1 to form the anode 2 (Appl. Phys. Lett. , 6
0, 2711, 1992). The anode 2 can also be formed by stacking different materials. The thickness of the anode 2 depends on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case,
The thickness is usually 5 to 1000 nm, preferably 10 to 5
It is about 00 nm. The anode 2 may be the same as the substrate 1 if it may be opaque. Further, it is also possible to stack different conductive materials on the anode 2.

An organic light emitting layer 3 is provided on the anode 2. The organic light emitting layer 3 efficiently transports and recombines the holes injected from the anode 2 and the electrons injected from the cathode 4 between the electrodes to which an electric field is applied, and emits light efficiently by the recombination. Formed from material. Usually, in order to improve the luminous efficiency, the organic light emitting layer 3 is divided into a hole transporting layer 3a and an electron transporting layer 3b so as to have a function separation type (Appl. Phys). . Le
tt. , 51, 913, 1987).

In the above-mentioned function-separated device, the material of the hole transport layer 3a is a material having a high hole injection efficiency from the anode 2 and capable of efficiently transporting the injected holes. It is necessary. For that purpose, it is required that the ionization potential is small, the hole mobility is large, the stability is excellent, and the impurities serving as traps are not easily generated during manufacturing or use.

As such a hole transport material, for example, an aromatic diamine compound in which a tertiary aromatic amine unit such as 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane is linked (Japanese Patent Application Laid-Open No. 2000-242242) Sho 59-19439
3), 4,4'-bis [N- (1-naphthyl)-
Aromatic amines containing two or more tertiary amines represented by N-phenylamino] biphenyl and having two or more condensed aromatic rings substituted with nitrogen atoms (Japanese Patent Laid-Open No. 5-234681) and triphenylbenzene. An aromatic triamine having a starburst structure as a derivative (US Pat.
3,774), aromatic diamines such as N, N'-diphenyl-N, N'-bis (3-methylphenyl) biphenyl-4,4'-diamine (US Pat. No. 4,764,62).
No. 5), α, α, α ′, α′-tetramethyl-α, α ′
-Bis (4-di-p-tolylaminophenyl) -p-xylene (JP-A-3-269084), triphenylamine derivative which is sterically asymmetric as a whole molecule (JP-A-4-12971), pyrenyl A compound in which a plurality of aromatic diamino groups are substituted in the group (Japanese Patent Laid-Open No. 4-17539).
5), an aromatic diamine in which a tertiary aromatic amine unit is linked by an ethylene group (JP-A-4-264189), and an aromatic diamine having a styryl structure (JP-A-4).
No. 290851), one in which an aromatic tertiary amine unit is linked by a thiophene group (JP-A-4-304466).
No. 3), a starburst type aromatic triamine (JP-A-4-308688), a benzylphenyl compound (JP-A-4-364153), and a fluorene group containing 3
A compound in which a primary amine is linked (JP-A-5-25473), a triamine compound (JP-A-5-239455), and bisdipyridylaminobiphenyl (JP-A-5-3).
20634), N, N, N-triphenylamine derivatives (JP-A-6-1972), aromatic diamines having a phenoxazine structure (Japanese Patent Application No. 5-290728).
No.), a diaminophenylphenanthridine derivative (Japanese Patent Application No. 6-45669), and a hydrazone compound (JP-A-2-
311591), silazane compounds (US Pat. No. 4,950,950), silanamine derivatives (JP-A-6-49079), phosphamine derivatives (JP-A-6-25659), quinacridone compounds and the like. . These compounds may be used alone,
If necessary, they may be mixed and used.

In addition to the above compounds, polyvinylcarbazole and polysilane (Ap) are used as materials for the hole transport layer 3a.
pl. Phys. Lett. , 59, 2760, 1
991), polyphosphazene (JP-A-5-3109)
49), polyamide (JP-A-5-310949), polyvinyltriphenylamine (Japanese Patent Application No. 5-2).
05377), a polymer having a triphenylamine skeleton (JP-A-4-133605), and a polymer in which triphenylamine units are linked by a methylene group or the like (Synthe).
tic Metals, 55-57, 4163, 1
993), polymethacrylates containing aromatic amines (J. Polym. Sci., Polym. Che.
m. Ed. 21: pp. 969, 1983).

A hole transport layer 3a is formed by laminating the above hole transport material on the anode 2 by a coating method or a vacuum deposition method. In the case of the coating method, one or more hole transporting materials and, if necessary, an additive such as a binder resin or a coatability improving agent that does not become a hole trap are added and dissolved to prepare a coating solution. Then, it is applied on the anode 2 by a method such as a spin coating method and dried to form the organic hole transport layer 3a. Examples of the binder resin include polycarbonate, polyarylate, polyester and the like. The addition amount of the binder resin decreases the hole mobility when it is added in a large amount.
The following are preferred.

In the case of the vacuum vapor deposition method, the hole transport material is placed in a crucible installed in a vacuum container, the interior of the vacuum container is evacuated to about 10 ⁻⁴ Pa by an appropriate vacuum pump, and then the crucible is heated. Then, the hole transport material is evaporated, and the hole transport layer 3a is formed on the anode 2 on the substrate 1 placed facing the crucible.
To form.

When the hole transport layer 3a is formed, a metal complex and / or metal salt of an aromatic carboxylic acid is further used as an acceptor (JP-A-4-320484).
A benzophenone derivative and a thiobenzophenone derivative (JP-A-5-295361), fullerenes (JP-A-5-331458), etc., at 10 ^-3 to 10% by weight.
It is possible to drive at a low voltage by doping at a concentration of 1 to generate holes as free carriers.

The thickness of the hole transport layer 3a is usually 10 to 3
00 nm, preferably 30 to 100 nm. In order to uniformly form such a thin film, the vacuum evaporation method is often used.

To further improve the efficiency of hole injection, and
A hole injection layer 3a 'is also inserted between the hole transport layer 3a and the anode 2 for the purpose of improving the adhesion of the entire organic layer to the anode (FIG. 3). As a material used for the hole injection layer 3a ', a material having a low ionization potential, a high conductivity and a thermally stable thin film formed on the anode is desirable, and a phthalocyanine compound or a porphyrin compound (JP-A-57- No. 51781, JP-A-63
No. 295695) is used. Hole injection layer 3
By inserting a ′, it is possible to reduce the driving voltage of the element at the initial stage and at the same time suppress an increase in voltage when the element is continuously driven with a constant current. It is also possible to improve conductivity by doping the hole injection layer 3a ′ with an acceptor in the same manner as the hole transport layer 3a.

The thickness of the hole injection layer 3a 'is usually 2-1.
00 nm, preferably 5 to 50 nm. In order to uniformly form such a thin film, the vacuum evaporation method is often used. An electron transport layer 3b is formed on the hole transport layer 3a.
Is provided. The electron-transporting layer 3b efficiently transfers electrons from the cathode between the electrodes to which an electric field is applied.
Formed of a compound that can be transported in the direction of.

The electron-transporting compound used in the electron-transporting layer 3b needs to be a compound having a high electron injection efficiency from the cathode 4 and capable of efficiently transporting the injected electrons. For that purpose, it is required that the compound has a high electron affinity, a high electron mobility, excellent stability, and an impurity that becomes a trap and is hard to be generated during the production or the use.

As materials satisfying such conditions, aromatic compounds such as tetraphenyl butadiene (Japanese Patent Laid-Open No. Sho 5 (1999) -58138)
7-51781), a metal complex such as an aluminum complex of 8-hydroxyquinoline (JP-A-59-1943).
93), a cyclopentadiene derivative (JP-A-2-
289675), perinone derivatives (JP-A-2-2)
No. 89676), an oxadiazole derivative (JP-A-2-216791), and a bisstyrylbenzene derivative (JP-A 1-245087, 2-222248).
4), perylene derivative (JP-A-2-189890).
JP-A No. 3-791), coumarin compounds (JP-A-2-191694, JP-A-3-792), rare earth complexes (JP-A-1-256584), and distyrylpyrazine derivatives (JP-A-2-252793). Gazette), p-phenylene compound (JP-A-3-33183), thiadiazolopyridine derivative (JP-A-3-37292), pyrrolopyridine derivative (JP-A-3-37293), naphthyridine derivative (special Kaihei 3-203982
Issue).

Electron transport layer 3b using these compounds
Can generally play a role of transporting electrons and a role of producing light emission upon recombination of holes and electrons at the same time. When the hole transport layer 3a has a light emitting function, the electron transport layer 3b may serve only to transport electrons.

For the purpose of improving the luminous efficiency of the device and changing the luminescent color, for example, a fluorescent dye for laser such as coumarin is doped with aluminum complex of 8-hydroxyquinoline as a host material (J. Appl. Ph.
ys. , 65, 3610, 1989) and the like. Also in the present invention, the emission characteristics of the device can be further improved by doping the above-mentioned organic electron transport material as a host material with various fluorescent dyes at 10 ⁻³ to 10 mol%. The thickness of the electron transport layer 3b is usually 10
-200 nm, preferably 30-100 nm.

The electron transport layer can be formed in the same manner as the hole transport layer, but the vacuum vapor deposition method is usually used. As a method of further improving the luminous efficiency of the organic electroluminescent device, another electron transport layer 3c can be further stacked on the electron transport layer 3b. The compound used for the electron transport layer 3c is required to be capable of easily injecting electrons from the cathode and have a higher electron transport capability. As such an electron transport material, an oxadiazole derivative (A
ppl. Phys. Lett. , 55, 1489 pages,
1989 and others) and polymethylmethacrylate (P
Systems dispersed in resin such as MMA (Appl. Phys.
Lett. , 61, 2793, 1992), phenanthroline derivative (JP-A-5-331459), n-type hydrogenated amorphous silicon carbide, n-type zinc sulfide, n-type zinc selenide and the like. The thickness of the electron transport layer 3c is usually 5 to 200 nm, preferably 10
-100 nm.

Single-layer organic light-emitting layer 3 without function separation
As the above-mentioned poly (p-phenylene vinylene)
(Nature, 347, 539, 1990 et al.), Poly [2-methoxy-5- (2-ethylhexyloxy) -1,4-phenylenevinylene] (Appl.
Phys. Lett. , 58, 1982, 1991.
Etc.), poly (3-alkylthiophene) (Jpn.
J. Appl. Phys, Volume 30, L1938, 19
1991, etc.), a system in which a light emitting material and an electron transfer material are mixed with a polymer such as polyvinylcarbazole (Applied Physics, 61, 1044, 1992).

The cathode 4 plays a role of injecting electrons into the organic light emitting layer 3. The material used for the cathode 4 may be the material used for the anode 2, but a metal having a low work function is preferable for efficient electron injection, and tin, magnesium, indium, calcium, Suitable metals such as aluminum and silver or alloys thereof are used. The film thickness of the cathode 4 is usually the same as that of the anode 2. For the purpose of protecting the cathode made of low work function metal,
Further, by stacking a metal layer having a high work function and stable on the atmosphere, the stability of the device is increased. Metals such as aluminum, silver, nickel, chromium, gold and platinum are used for this purpose.

Besides the structure shown in FIGS. 1 to 3, an organic electroluminescent device having the following layer structure is used in the present invention;

[0032]

[Table 1]

In the above-mentioned layer structure, the interface layer is for improving the contact between the cathode and the organic layer. An aromatic diamine compound (JP-A-6-267658) and a quinacridone compound (Japanese Patent Application No. 5-116204). ), A naphthacene derivative (Japanese Patent Application No. 5-116205), an organic silicon compound (Japanese Patent Application No. 5-116206), an organic phosphorus compound (Japanese Patent Application No. 5-116207), a compound having an N-phenylcarbazole skeleton (special No. 6-199562), N
-Vinylcarbazole polymer (Japanese Patent Application No. 6-200942)
No.) and the like. The thickness of the interface layer is
Usually, it is 2 to 100 nm, preferably 5 to 30 nm. Instead of providing the interface layer, a region containing 50% by weight or more of the material of the interface layer may be provided near the cathode interface of the organic light emitting layer and the electron transport layer.

In order to improve the stability and reliability of the organic electroluminescent device, it is necessary to seal the entire device. The sealing method of the present invention will be described below with reference to the structural example of FIG. In order to suppress dark spots, the device must first be placed in an airtight structure. At that time, it was found that it was difficult to suppress dark spots when there was a free volume in the closed space. The reason for this is that the cathode 4
It is considered that since the adhesive force to the organic light emitting layer 3 is very weak, the cathode 4 is easily separated from the organic light emitting layer 3 due to heat generation during driving when a free volume exists in the vicinity of the cathode 4. In this respect, it is difficult to avoid dark spots by the method of sealing with an inert gas or an inert liquid. Therefore, it is necessary to fill the space sealed with some solid state material, but if you use conventional adhesives such as acrylic resin, epoxy resin, cyanoacrylate resin, UV curable resin, etc. Since the layer is hard, the curing shrinkage strain and internal stress generated at the time of curing are concentrated on the interface of the bonding portion with the organic electroluminescent element, so that the cathode 4 is severely peeled or the element is short-circuited.

As a material for the sealing layer 6, a resin satisfying the following conditions (a), (b) and (c), which is different from the conventional sealing agent, is the most suitable as a sealing agent for an organic electroluminescence device. The present inventor found out. (A) The elongation specified in JIS K 6911 is 100.
%that's all. (B) Shore A hardness specified by JIS K 6301 is 20 or more. (C) Glass transition point of -40 ° C or lower, -40 to +10
It exhibits rubber-like elasticity in the temperature range of 0 ° C.

The above-mentioned rubber-like elasticity usually means a state having a remarkably small elastic modulus and a reversible elastic region of a strain up to several hundreds%, for example, a shear elastic modulus of 10 ⁷ to 10 ⁹ dyne.
/ Cm ² (10 ⁶ to 10 ⁸ N / m ² ) or so. A modified silicone-based elastic adhesive can be exemplified as the sealing agent satisfying the above characteristics. A modified silicone-based elastic adhesive is an adhesive based on a resin that has a reactive silyl group terminal and that the silyl group reacts with water to crosslink, commonly known as a special silicone-modified polymer. As a typical modified silicone-based elastic adhesive, there are two components: a component mainly composed of a base resin having a reactive silyl group terminal and a component mainly composed of a compound having a functional group which reacts with a silyl group to bond. Examples of the adhesive include Preferred examples of the compound having a functional group that reacts with and bonds to the silyl group include epoxy resins such as bisphenol A diglycidyl ether.

As the base resin having a reactive silyl group terminal, a resin obtained by silyl-modifying the terminal of polypropylene oxide, for example, a compound represented by the following structural formula,

[0038]

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Can be exemplified. This polymer undergoes a molecular chain extension reaction and a cross-linking reaction due to a hydrolysis reaction with water to become a rubber-like elastic body. The above-mentioned modified silicone-based elastic adhesive has a glass transition temperature of about −60 ° C., and shows a rubber-like elasticity in the temperature range of −60 ° C. to 120 ° C. as a characteristic after curing, and a conventional epoxy resin. About 3
It shows a small rigidity and a Shore hardness in the range of 40 to 90. As a result, as a characteristic of this modified silicone-based elastic adhesive, curing shrinkage strain generated at the time of curing, internal stress strain generated from external mechanical stress and difference in linear expansion coefficient with the adherend, etc. The effect of preventing the peeling of the cathode 4 is to absorb and disperse it, to reduce the residual stress at the interface of the adhesive portion, to press the cathode 4 against the organic light emitting layer 3 with an appropriate adhesive force. Furthermore, it is a highly reliable adhesive that is resistant to thermal shock and heat cycles.

Specific modified silicone-based elastic adhesives include PM165, PM200 and PM4 manufactured by Cemedine.
Examples thereof include elastic adhesives marketed under the trade names of 00, EP001, and Konishi's MOS7. Further, Peg α (trade name) manufactured by Cemedine Co., which further contains cyanoacrylate in order to further increase the curing speed, is also effective as an adhesive for sealing. These are usually room temperature curable.

In order to further enhance the effect as the sealing layer, it is further effective to add a hygroscopic agent such as silica gel, zeolite, calcium chloride, activated carbon, nylon and polyvinyl alcohol as a filler to the above modified silicone elastic adhesive. Target. The content of the filler is usually preferably 10 to 50% by weight.

When the sealing layer 6 is provided, the stress applied to the cathode 4 is relaxed, and further, the reaction between the chemical component of the adhesive used for the sealing layer and the element is suppressed to prevent damage to the element. It is necessary to provide the protective layer 5 between the cathode 4 and the sealing layer 6. The material of the protective layer 5 may be an inorganic material or an organic material as long as it is a material that has electrical insulation properties, a stable film shape, and does not damage the device. Specific examples of the material of the protective layer 5 include metal oxides (Japanese Patent Application Laid-Open No. Hei 4-
212284, JP-A-4-73886, JP-A-5-335080), metal fluoride (JP-A-4-212284), metal sulfide (JP-A-4).
-212284), metal nitrides (JP-A-4-7)
3886), polymers (JP-A-4-137483, JP-A-4-206386, JP-A-4-23).
3192, JP-A-4-267097, JP-A-4-355096), plasma polymerized film (JP-A-5-101886), organic silicon compounds, organic compositions of organic electroluminescent elements, and the like. However, it is not limited thereto. The thickness of the protective layer 5 is usually 5
It is 0 nm to 10 μm, preferably 100 nm to 1 μm.

A protective layer 5 is provided on the organic electroluminescent device,
Then, after providing the sealing layer 6, the outside air blocking material layer 7 for blocking the element from the outside air is attached to the substrate 1 by using an appropriate adhesive 8. The outside air blocking material layer is required to have a gas barrier property like the substrate. Therefore, an electrically insulating glass plate or an electrically insulating resin plate or film provided with a dense silicon oxide film or the like is usually used. The adhesive 8 may have any gas barrier property, and examples thereof include an epoxy adhesive, an acrylic adhesive, a polyurethane adhesive, and a modified silicone elastic adhesive.

When the above-mentioned sealing method is applied to actual device fabrication, the device may be short-circuited. This is because, for example, when there is a void defect in the organic light emitting layer or a defect due to dust during fabrication, the cathode near the defect is depressed into the void space by the force from the sealing layer, and as a result, the cathode and the anode are separated. Due to a short circuit. However, when the film thickness of the cathode 4 is smaller than the film thickness of the organic light emitting layer 3, the cathode breaks when it is depressed and a short circuit does not occur. Therefore, the thickness of the cathode 4 is preferably smaller than that of the organic light emitting layer 3. This short circuit phenomenon is also related to the surface roughness of the anode 2.
If there are ridges and valleys in the ridge, for example, the organic light emitting layer 3 is deposited vertically on the substrate 1 on the slope of the mountain of the anode 2, but in the direction perpendicular to the slope of the mountain of the anode 2. Looking,
The film thickness of the organic layer is reduced by the inclination of the slope. From this, it is desirable that the surface roughness of the anode 2 is suppressed to about the surface roughness of the substrate 1, and the 10-point average roughness Rz (defined by JIS) is preferably 10 nm or less.

The present invention can be applied to any one of the organic electroluminescence device, a single device, a device having a structure arranged in an array, and a structure having an anode and a cathode arranged in an XY matrix. You can

[0046]

EXAMPLES Next, the present invention will be described more specifically by way of examples, but the present invention is not limited to the description of the following examples unless it exceeds the gist.

Example 1 An organic electroluminescent device having the structure shown in FIG. 2 was prepared by the following method.
It was made in. Indium tin oxide on glass substrate
(ITO) transparent conductive film deposited to 120 nm (Geo)
Made by MATEC Co., Ltd .; Electron beam coating product; Sheet resistance 15Ω)
Stylus-type surface roughness tester (Rank Taylor Hobson
Ten-point average roughness Rz of ITO surface
When (JIS B0601) was measured, it was 7.4 nm.
there were. This ITO glass substrate is used for normal photolithography.
A strike of 2mm width using Phy technology and hydrochloric acid etching
To form an anode. Pattern formed
The ITO substrate was ultrasonically cleaned with acetone and deionized with pure water.
Cleaning with water and ultrasonic cleaning with isopropyl alcohol
After cleaning with, dry with nitrogen blow, and finally ultraviolet ozone.
It was washed and placed in a vacuum evaporation apparatus. Rough discharge of equipment
After the air is pumped by the oil rotary pump, the degree of vacuum in the device is 2
× 10^-6Torr (about 2.7 × 10 ^-FourPa) or less
Drain using an oil diffusion pump equipped with a liquid nitrogen trap
I noticed. Enter the ceramic crucible placed in the above equipment.
4,4'-bis [N- (1-naphthyl) shown below.
) -N-Phenylamino] biphenyl (H1)

[0048]

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The vapor deposition was performed by heating with a tantalum wire heater around the crucible. The temperature of the crucible at this time is 250
Control was performed in the range of ~ 260 ° C. Degree of vacuum during vapor deposition 1.7 ×
10 ^-6 Torr (about 2.3 × 10 ^-4 Pa), deposition time 3
The hole transport layer 3a having a film thickness of 60 nm was obtained in 30 minutes.

Next, as a material of the electron transport layer 3b having a light emitting function, aluminum 8-hydroxyquinoline complex represented by the following structural formula, Al (C ₉ H ₆ NO) ₃ (E1),

[0051]

Embedded image

The above was vapor-deposited on the hole transport layer 3a in the same manner. The temperature of the crucible at this time is 270-300 ° C
Controlled in the range of. The degree of vacuum during vapor deposition is 1.3 × 10 ^-6 T
orr (about 1.7 × 10 ⁻⁴ Pa), deposition time is 3 minutes 10
In seconds, the film thickness of the vapor-deposited electron transport layer 3b was 75 nm. The substrate temperature during vacuum deposition of the hole transport layer 3a and the electron transport layer 3b was kept at room temperature.

Here, vapor deposition up to the electron transport layer 3b is performed.
Once removed the element from the vacuum vapor deposition device into the atmosphere.
2mm wide stripes as a mask for cathode deposition
The shadow mask is orthogonal to the ITO stripe on the anode 2.
To the device, and place it in another vacuum deposition device.
Place it in the same manner as the organic layer, and the vacuum degree in the device is 2 × 10 ^-6
Torr (about 2.7 × 10^-FourExhaust until below Pa)
did. Then, as the cathode 4, an alloy of magnesium and silver
The electrode will be 140nm thick by the two-source simultaneous vapor deposition method.
It was vapor-deposited. For vapor deposition, use a molybdenum boat and vacuum.
1 × 10^-FiveTorr (about 1.3 × 10^-3Pa), vapor deposition
It took 3 minutes and 20 seconds. Also, the source of magnesium and silver
The child ratio was 10: 1.2. Further on, the vacuum of the device
Use the molybdenum boat to break the aluminum
With a thickness of 110 nm on the magnesium-silver alloy film
Layered to complete the cathode 4. Vacuum for aluminum deposition
Degree is 1.5 × 10^-FiveTorr (about 2.0 × 10^-3P
a), the vapor deposition time was 1 minute and 20 seconds. More magnesi
Base for vapor deposition of two-layer cathode of um-silver alloy and aluminum
The plate temperature was kept at room temperature.

As described above, an organic electroluminescence device having a size of 2 mm × 2 mm was obtained. After taking out this device from the cathode vapor deposition apparatus, the device was then sealed. First,
After the above-mentioned element was installed again in the above-mentioned organic layer vapor deposition apparatus, the compound (H1) was laminated on the cathode 4 to a thickness of 150 nm on the cathode 4 in the same manner as described above to form the protective layer 5. .
At this time, the degree of vacuum is 1.5 × 10 ⁻⁶ Torr (about 2.0 ×
10 ⁻⁴ Pa), the vapor deposition time was 7 minutes and 30 seconds, and the substrate temperature was room temperature. The device was taken out of the apparatus into the atmosphere, put in a nitrogen glove box, and the following work was performed.

After mixing an appropriate amount of a two-component mixed type modified silicone elastic adhesive (made by Cemedine, trade name EP001), about 30% by weight of silica gel powder (particle size 50 to 50).
300 μm) was further added as a filler, and then coated on the protective layer 5 in a thickness of about 1 mm to form a sealing layer 6. The resin obtained by the elastic adhesive is JIS K 6
The elongation specified in 911 is 200%, and JIS K
6301 has a Shore A hardness of 78,
It had a glass transition point of -60 ° C and exhibited rubber-like elasticity in the temperature range of -40 to + 100 ° C. After curing at room temperature for 40 minutes, a glass plate having a thickness of 1.1 mm as the outside air barrier layer 7 is attached to the adhesive portion 8 using an epoxy resin (Ciba-Geigy, trade name Araldite) to seal the element. Was completed.

The organic electroluminescence device thus obtained was stored at room temperature in the atmosphere, and a positive DC voltage was applied to the anode 2 and a negative DC voltage was applied to the cathode 4 to cause the device to emit light. The change with time was measured. For the measurement of the dark spot, the light emitting surface of the device was photographed by a CCD camera and then binarized by image analysis for quantification.

FIG. 5 shows the time-dependent change in the emission luminance when 11 V was applied to the device, and FIG. 6 shows the time-dependent change in the dark spot. Even after being stored in the atmosphere for 60 days, the emission brightness is 1 of the initial brightness.
Almost no decrease was observed at 140 cd / m ^{2 with} respect to 47 cd / m ^2, and the dark spot was less than 1% of the total light emitting area even after 60 days.

Comparative Example 1 A sealing element was produced in the same manner as in Example 1 except that an epoxy resin (manufactured by Ciba-Geigy, trade name Araldite) was used as the material of the sealing layer 6. The epoxy resin did not show rubber-like elasticity. FIG. 5 shows the time-dependent change in the emission luminance when DC 8 V was applied to this element, and FIG. 6 shows the time-dependent change in the dark spot. After being stored in the atmosphere for 60 days, the emission luminance was 103 cd compared to the initial luminance of 282 cd / m ² .
/ M ² and decreased to 40% or less, and the dark spot reached 46% of the total light emitting area after 60 days.

Example 2 An organic electroluminescent device having the structure shown in FIG. 3 was produced by the following method. An ITO glass substrate patterned in the same manner as in Example 1 was placed in a vacuum vapor deposition device. After performing rough evacuation of the equipment with an oil rotary pump, install an oil diffusion pump equipped with a liquid nitrogen trap until the degree of vacuum inside the equipment becomes 2 × 10 ⁻⁶ Torr (about 2.7 × 10 ⁻⁴ Pa) or less. Evacuated using. Copper phthalocyanine (H2) shown below placed in a molybdenum boat arranged in the above-mentioned device (crystal form is β type)

[0060]

[Chemical 4]

Was vapor-deposited by heating. Vacuum degree 2 × 10
^-6Torr (about 2.7 × 10^-FourPa), deposition time 55 seconds
By vapor deposition to obtain a hole injection layer 3a 'with a thickness of 20 nm.
Was. Next, as a hole transport layer 3a, it is put in a ceramic crucible.
The compound (H1) prepared above was treated in the same manner as in Example 1 to obtain the above-mentioned holes.
It was stacked on the injection layer 3a '. Vacuum degree 1.5 × 10 ^-6T
orr (about 2.0 × 10^-FourPa), deposition time 3 minutes 30 seconds
Is evaporated to obtain a hole transport layer 3a having a film thickness of 60 nm.
Was.

Subsequently, the electron transport layer 3 having a light emitting function.
b was laminated on the hole transport layer 3a in the same manner as in Example 1 using the compound (E1). Vacuum degree 1.5 × 10 ^-6 T
Vapor deposition was performed at orrr (about 2.0 × 10 ⁻⁴ Pa) for a vapor deposition time of 2 minutes and 10 seconds to obtain an electron transport layer 3b having a film thickness of 75 nm.

The above hole injection layer 3a 'and hole transport layer 3a.
And the substrate temperature when vacuum-depositing the electron transport layer 3b is room temperature.
Held in. Here, vapor deposition up to the electron transport layer 3b is performed.
Once removed the element from the vacuum vapor deposition device into the atmosphere.
2mm wide stripes as a mask for cathode deposition
Place the shadow mask orthogonal to the ITO stripe on the anode.
Close to the device as shown, and set it in another vacuum evaporation system
Then, the cathode 4 was formed as follows. First, magnesium
55nm film thickness of silver and silver alloy electrode by two-source simultaneous vapor deposition method
Was deposited so that Molybdenum boat is used for vapor deposition
Vacuum degree 1 × 10^-FiveTorr (about 1.3 × 10 ^-3P
a), vapor deposition time of 1 minute and 15 seconds, magnesium and silver atoms
The ratio was 10: 1. Further on, the true
Use aluminum molybdenum boat without breaking the sky
A 50 nm thick film on the magnesium-silver alloy film.
Layered to complete the cathode 4. Vacuum for aluminum deposition
Degree is 1.5 × 10^-FiveTorr (about 2.0 × 10^-3P
a), the vapor deposition time was 1 minute and 15 seconds. More magnesi
Base for vapor deposition of two-layer cathode of um-silver alloy and aluminum
The plate temperature was kept at room temperature.

As described above, an organic electroluminescence device having a size of 2 mm × 2 mm was obtained. After taking out this device from the cathode vapor deposition apparatus, the device was then sealed. First,
After the above element was installed again in the above-mentioned organic layer vapor deposition apparatus, the compound (E1) was laminated on the cathode 4 in a thickness of 200 nm to form the protective layer 5 in the same manner as described above. .
At this time, the degree of vacuum is 2 × 10 ⁻⁶ Torr (about 2.7 × 10
^-4 Pa), the vapor deposition time was 6 minutes and 10 seconds, and the substrate temperature was room temperature. The device was taken out of the apparatus into the atmosphere, placed in a nitrogen glove box, and sealed in the same manner as in Example 1.

The thus obtained organic electroluminescent device was driven in the atmosphere at a constant current to obtain a current density of 15 mA / c.
DC was continuously driven as m ² . The initial brightness at this time is 3
It was 70 cd / m ² . FIG. 7 shows a change with time in luminance during driving. The dark spot after continuous driving for 570 hours was less than 0.1%.

Comparative Example 2 The sealing agent used for the sealing layer 6 was silicone oil (Shin-Etsu Silicon).
Silica gel powder in corn company, trade name KF-54)
A sealing element was prepared in the same manner as in Example 2 except that the sealing agent was changed.
I made a child. Constant current drive of this element in the atmosphere
Current density at 15mA / cm² DC continuous drive as
Was. The initial brightness at this time is 360 cd / m ² Met. Drive
FIG. 7 shows a change with time in luminance during movement. After driving for 333 hours
The dark spot reached 54%.

Comparative Example 3 A sealing element was manufactured in the same manner as in Example 2 except that the protective layer 5 was not provided. This device was continuously driven in the atmosphere at a constant current for a current density of 15 mA / cm ² . The initial luminance at this time was 220 cd / m ² , and the initial light emission was non-uniform. FIG. 7 shows a change with time in luminance during driving. After driving for 310 hours, the dark spot is 29%
Reached

Example 3 Using the compound (E1) as a host for the electron transport layer 3b having a light emitting function, rubrene (D1) shown below was used.

[0069]

Embedded image

A sealing element was prepared in the same manner as in Example 2 except that the element was formed by the two-source simultaneous vapor deposition using the dope as a dye. The concentration of rubrene contained in the electron transport layer 3b is 2.7.
It was mol%.

The thus obtained organic electroluminescent device was driven in the atmosphere at a constant current to obtain a current density of 15 mA / c.
DC was continuously driven as m ² . The initial brightness at this time is 5
It was 35 cd / m ² . FIG. 8 shows a change with time in luminance during driving. Dark spot after driving for 380 hours is 0.1
Was less than%. The half-life of luminance is expected to be about 10,000 hours from the rate of decrease in luminance shown in FIG.
A dramatic driving life was achieved compared to the L element. The voltage change was 7.2 V at the initial stage, and it was 8.0 after 380 hours.
It was suppressed to an increase of V and 1 V or less.

Example 4 The sealing element produced in the same manner as in Example 3 was tested by a small environment tester (SH220 type manufactured by Tabai Espec Co., Ltd.) at 60
Element characteristics after storage for 24 hours under the condition of ° C-90% RH were measured. Table 1 below shows the measurement results together with the characteristics before storage.
Shown in

[0073]

[Table 2]

In the above environmental test, there was no deterioration in luminance and luminous efficiency, no increase in dark spots was observed, and it was shown that the sealing method of the present invention has sufficient reliability even under high temperature and high humidity.

[0075]

According to the organic electroluminescent element sealing method of the present invention, since it has a sealing layer made of a specific adhesive,
It is possible to obtain a sealing element that exhibits stable light emission characteristics during storage and driving in the atmosphere. Therefore, the organic electroluminescent device according to the present invention is a light source (for example, a light source of a copying machine, a liquid crystal display or a backlight of a meter, etc.) that makes use of the characteristics of a flat panel display (for example, for OA computers or wall-mounted televisions) or a surface light emitter. It can be applied to light sources), display boards, and marker lights, and its technical value is great.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of an organic electroluminescence device.

FIG. 2 is a schematic cross-sectional view showing another example of the organic electroluminescence device.

FIG. 3 is a schematic cross-sectional view showing still another example of the organic electroluminescent element.

FIG. 4 is a schematic view showing an example of a method for sealing an organic electroluminescent element according to the present invention.

FIG. 5 is a graph showing changes over time in the emission luminance (initial luminance is 1) of the organic electroluminescent elements in Example 1 and Comparative Example 1 when stored in the atmosphere.

FIG. 6 is a graph showing changes over time in dark spots of the organic electroluminescent elements of Example 1 and Comparative Example 1 when stored in the atmosphere.

FIG. 7 shows the emission luminance (initial luminance of 1 when the organic electroluminescent elements of Example 2, Comparative Example 2 and Comparative Example 3 were driven in the atmosphere).
Is a graph showing changes over time.

FIG. 8 is a graph showing a change over time in the light emission luminance (initial luminance is 1) of the organic electroluminescent element in Example 3 when driven in air.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Organic light emitting layer 4 Cathode 3a Hole transport layer 3b Electron transport layer 3a 'Hole injection layer 5 Protective layer 6 Sealing layer 7 Outside air blocking layer 8 Adhesive part

Claims (7)

[Claims] 1. An anode, an organic light emitting layer, and a cathode are laminated on a substrate, and a protective layer is formed on the outer surface of the laminate in order from the inside.
An organic electroluminescent device comprising a sealing layer and an outside air blocking material layer, wherein the sealing layer is one of the following (a), (b) and (c):
An organic electroluminescent device comprising a resin which satisfies the condition of (3) as a main component. (A) The elongation specified in JIS K 6911 is 100.
%that's all. (B) Shore A hardness specified by JIS K 6301 is 20 or more. (C) Glass transition point of -40 ° C or lower, -40 to +10
It exhibits rubber-like elasticity in the temperature range of 0 ° C. 2. The organic electroluminescence device according to claim 1, wherein the resin satisfying the conditions (a), (b) and (c) is a modified silicone elastic adhesive. 3. The silica gel, zeolite,
The organic electroluminescent element according to claim 1 or 2, which contains at least one hygroscopic agent selected from calcium chloride, activated carbon, nylon and polyvinyl alcohol. 4. The organic electroluminescent device according to claim 1, wherein the outside air blocking material layer is made of electrically insulating glass or electrically insulating polymer. 5. The organic electroluminescent device according to claim 1, wherein a film thickness of the cathode is smaller than a film thickness of the organic light emitting layer. 6. The anode is indium tin oxide, and the surface roughness thereof is 10 nm or less.
5. The organic electroluminescent element according to any one of 5 to 5. 7. After laminating an anode, an organic light emitting layer and a cathode on a substrate and providing a protective layer on the outer surface of the laminate, the following conditions (a), (b) and (c) are applied. The organic electroluminescent element according to claim 1, wherein a sealing layer containing a filling resin as a main component is formed, and an outside air blocking material layer is further provided outside the sealing layer. Manufacturing method. (A) The elongation specified in JIS K 6911 is 100.
%that's all. (B) Shore A hardness specified by JIS K 6301 is 20 or more. (C) Glass transition point of -40 ° C or lower, -40 to +10
It exhibits rubber-like elasticity in the temperature range of 0 ° C.