JP2002134269A - Organic EL device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL device capable of effectively removing water and maintaining stable light emitting characteristics for a long period of time. The present invention relates to an organic EL device including a substrate, an anode made of a transparent conductive film formed on the substrate, an organic light emitting layer formed on the anode, and a cathode. Then, a water absorbing agent 5 containing an organic substance having an isocyanate group is provided on at least a part of the cathode 4. The water absorbing agent 5 made of an organic substance having an isocyanate group has a high ability to chemically adsorb moisture, and can effectively remove moisture acting on the element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic EL device used for various displays, display devices, backlights for liquid crystals, and the like.

[0002]

2. Description of the Related Art Organic electroluminescent devices using an organic material as a luminous element have been attracting attention for a long time, and various studies have been conducted. Did not. However, 198
In 7 years, Kodak C.I. W. Tang et al. Proposed an organic electroluminescence having a function-separated stacked structure in which an organic material was divided into two layers, a hole transport layer and a light-emitting layer. In this case, despite the low voltage of 10 V or less,
It was found that a high emission luminance of 1000 cd / m ² or more was obtained. From then on, organic electroluminescent devices (organic EL devices) began to attract attention,
Active research has begun.

[0003] As a result of such research and development, at present, organic EL devices are 100 to 1 at a low voltage of about 10V.
Surface emission with high luminance of about 00000 cd / m ² is possible, and emission from blue to red is possible by selecting the type of fluorescent substance.

[0004]

However, when the organic EL element is driven for a certain period, a non-light-emitting portion called a dark spot occurs and grows, and the light-emitting characteristics deteriorate. The cause of such a dark spot is considered to be the greatest effect of moisture and oxygen, and particularly, even a very small amount of moisture is considered to have a great effect.

[0005] In view of the above, a device for removing moisture as much as possible such as purification of an organic material used for the organic light emitting layer, quality of vacuum at the time of forming the organic light emitting layer, sealing of the device, etc. is implemented, and is manufactured by a dry process. ing.

More specifically, for example, Japanese Patent Application Laid-Open No. 9-148
As disclosed in Japanese Patent Application Publication No. 066, there is provided a drying means made of a compound capable of chemically adsorbing moisture and maintaining a solid state even when moisture is absorbed into the package. Has been proposed. However, in Japanese Patent Application Laid-Open No. 9-148066, although alkaline earth metal oxides such as barium oxide and calcium oxide, organic substances, and the like are disclosed as compounds for drying means, stable light emission over a long period of time is disclosed. At present, the effect of maintaining the characteristics has not been obtained.

The present invention has been made in view of the above points, and an object of the present invention is to provide an organic EL device capable of effectively removing moisture and maintaining stable light emitting characteristics for a long period of time. It is the purpose.

[0008]

According to the present invention, there is provided an organic EL device comprising a substrate, an anode made of a transparent conductive film formed on the substrate, and an organic light emitting layer formed on the anode. An organic EL device including the cathode 3 and the cathode 4 is characterized in that at least a part of the cathode 4 is provided with a water absorbing agent 5 containing an organic substance having an isocyanate group.

According to a second aspect of the present invention, in the first aspect, the water absorbing agent 5, the cathode 4, the organic light emitting layer 3 and the anode 2 are surrounded by the substrate 1 and the protective film 6 so that the water absorbing agent 5, the organic light emitting layer 3 and the anode 2 are hardly permeable. It is characterized in that the film 6 is formed.

The invention of claim 3 is characterized in that, in claim 2, the protective film 6 is formed of a silicon nitride film.

An organic EL device according to a fourth aspect of the present invention comprises:
A substrate 1, an anode 2 made of a transparent conductive film formed on the substrate 1, an organic light emitting layer 3 and a cathode 4 formed on the anode 2, and a sealant 8 is provided between the substrate 1 and the sealing plate 7. In the organic EL element in which the organic light emitting layer 3 is sealed by sealing, a water absorbing agent 5 containing an organic substance having an isocyanate group is provided on at least a part of the cathode 4 or the sealing plate 7 on the substrate 1 side. It is characterized by the following.

An organic EL device according to a fifth aspect of the present invention comprises:
A substrate 1, an anode 2 made of a transparent conductive film formed on the substrate 1, an organic light emitting layer 3 and a cathode 4 formed on the anode 2, and a sealant 8 is provided between the substrate 1 and the sealing plate 7. The organic EL device in which the organic light emitting layer 3 is sealed by sealing is characterized in that at least a part of the sealant 8 is provided with a water absorbing agent 5 containing an organic substance having an isocyanate group.

The invention of claim 6 is characterized in that in any one of claims 1 to 5, the water absorbing agent 5 is formed in a film shape.

According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the water absorbing agent 5 comprises naphthylene diisocyanate, 4,4-diphenylmethane diisocyanate,
Paraphenylene diisocyanate, isopropylidene bis (4-cyclohexyl isocyanate), cyclohexyl diisocyanate, tolidine diisocyanate, lysine diisocyanate, tetramethyl xylylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, dicyclohexyl methane diisocyanate, isophorone diisocyanate It is characterized by comprising at least one organic substance selected from cyanate and hydrogenated xylylene diisocyanate.

[0015]

Embodiments of the present invention will be described below.

FIG. 1 shows an embodiment of the present invention, in which an anode 2 made of a transparent conductive film is formed on a surface of a substrate 1.
And the organic light emitting layer 3 is stacked on the surface of the anode 2 via the hole transport layer 11, and the cathode 4 is further stacked on the surface of the organic light emitting layer 3 via the electron transport layer 12. An organic EL element can be formed by using this as a basic structure. When a positive voltage is applied to the anode 2 and a negative voltage is applied to the cathode 4, the organic light emitting layer 3 is formed via the electron transport layer 12.
The electrons injected into the organic light emitting layer 3 and the holes injected into the organic light emitting layer 3 via the hole transport layer 11 recombine in the organic light emitting layer 3 to emit light.

The anode 2 serving as an electrode for injecting holes into the above-mentioned element is made of a metal, alloy, or the like having a large work function.
It is preferable to use an electrode material made of an electrically conductive compound or a mixture thereof, and it is particularly preferable to use an electrode material having a work function of 4 eV or more. As such an electrode material, specifically, a metal such as gold, CuI, I
TO (indium tin oxide), SnO ₂ , ZnO
And other conductive transparent materials.

For example, by forming these electrode materials on the substrate 1 by a method such as a vacuum evaporation method or a sputtering method, the anode 2 can be manufactured as a thin film. Here, the substrate 1 can be appropriately selected from transparent materials such as transparent glass and transparent resin, and is used when light emitted from the organic light emitting layer 3 is transmitted from the anode 2 to the outside from the substrate 1. Has a light transmittance of 10% for the anode 2.
It is preferable that it is above. The sheet resistance of the anode 2 is preferably several hundreds Ω / □ or less, particularly 100 Ω / □.
/ □ or less. The thickness of the anode 2 varies depending on the material in order to control the light transmittance, sheet resistance, and other characteristics of the anode 2 as described above.
nm or less, and preferably in the range of 10 to 200 nm.

On the other hand, the cathode 4, which is an electrode for injecting electrons into the organic light emitting layer 3, is preferably made of an electrode material made of a metal, an alloy, an electrically conductive compound and a mixture thereof having a small work function. It is preferable to use an electrode material having a work function of 5 eV or less. Such electrode material include sodium, sodium - potassium alloy, lithium, magnesium, aluminum, magnesium - silver mixture, a magnesium - indium mixture, an aluminum - lithium alloy, Al / Al ₂ O ₃ mixture, Al / Li
F mixture and the like. The cathode 4 can be produced, for example, by forming these electrode materials into a thin film by a method such as a vacuum evaporation method or a sputtering method. Further, when light emitted from the organic light emitting layer 3 is transmitted through the cathode 4 and irradiated to the outside, the cathode 4 preferably has a light transmittance of 10% or more. Here, the thickness of the cathode 4 varies depending on the material in order to control the characteristics such as the light transmittance of the cathode 4 as described above.
m, preferably in the range of 100 to 200 nm.

In the present invention, the light emitting material or doping material which can be used for the organic light emitting layer 3 includes anthracene, naphthalene, pyrene, tetracene, coronene, perylene, phthaloperylene, naphthaloperylene, diphenylbutadiene, tetraphenylbutadiene, coumarin,
Oxadiazole, bisbenzoxazoline, bisstyryl, cyclopentadiene, quinoline metal complex, tris (8-hydroxyquinolinato) aluminum complex, tris (4-methyl-8-quinolinato) aluminum complex, tris (5-phenyl-8) -Quinolinato) aluminum complex, aminoquinoline metal complex, benzoquinoline metal complex, tri- (p-terphenyl-4-yl) amine, 1-aryl-2,5-di (2-thienyl) pyrrole derivative, pyran, quinacridone , Rubrene, distilbenzene derivatives, distilarylene derivatives, various fluorescent dyes, and the like, but are not limited thereto.
In addition, the light emitting material selected from these compounds is 9
It is also preferable to include 0 to 99.5 parts by weight and 0.5 to 10 parts by weight of the doping material. The thickness of the organic light emitting layer 3 is preferably 0.5 to 500 nm, particularly 0.5 to 2 nm.
00 nm is preferred.

The hole transporting material constituting the hole transporting layer 11 has the ability to transport holes,
And an organic light emitting layer 3
Or has an excellent hole injection effect on the luminescent material,
Further, compounds that prevent the transfer of electrons to the hole transport layer 11 and have excellent thin film forming ability can be used. Specifically, phthalocyanine derivatives, naphthalocyanine derivatives, porphyrin derivatives, N, N'-bis (3-methylphenyl)-(1,1'-biphenyl) -4,4'-diamine (TPD) and 4,4 ' -Bis [N- (naphthyl)-
Aromatic diamine compounds such as N-phenyl-amino] biphenyl (α-NPD), oxazole, oxadiazole, triazole, imidazole, imidazolone, stilbene derivative, pyrazoline derivative, tetrahydroimidazole, polyarylalkane, butadiene, 4,
4 ', 4 "-tris (N- (3-methylphenyl) N-
Phenylamino) triphenylamine (m-MTDAT
A) and polymer materials such as polyvinylcarbazole, polysilane, and conductive polymers such as polyethylene dioiside thiophene (PEDOT), but are not limited thereto.

The electron transporting material constituting the electron transporting layer 12 has the ability to transport electrons, has the effect of injecting electrons from the cathode 4, and has an excellent electron transporting property with respect to the organic light emitting layer 3 or the light emitting material. Compounds that have an injection effect, prevent movement of holes to the electron transport layer 12, and have excellent thin film forming ability can be given. In particular,
Fluorene, bathophenanthroline, bathocuproine,
Anthraquinodimethane, diphenoquinone, oxazole, oxadiazole, triazole, imidazole,
Anthraquinodimethane and the like, compounds thereof, metal complex compounds and nitrogen-containing five-membered ring derivatives. In particular,
As the metal complex compound, tris (8-hydroxyquinolinato) aluminum, tri (2-methyl-8-hydroxyquinolinato) aluminum, tris (8-hydroxyquinolinato) gallium, bis (10-hydroxybenzo [ h] quinolinato) beryllium, bis (10
-Hydroxybenzo [h] quinolinato) zinc, bis (2
-Methyl-8-quinolinato) (o-cresolate) gallium, bis (2-methyl-8-quinolinate) (1-
Naphtholate) aluminum and the like, but are not limited thereto. As the nitrogen-containing five-membered ring derivative, an oxazole, thiazole, oxadiazole, thiadiazole or triazole derivative is preferable.
Specifically, 2,5-bis (1-phenyl) -1,3,3
4-oxazole, 2,5-bis (1-phenyl)-
1,3,4-thiazole, 2,5-bis (1-phenyl) -1,3,4-oxadiazole, 2- (4′-ter
t-butylphenyl) -5- (4 ″ -biphenyl) 1,
3,4-oxadiazole, 2,5-bis (1-naphthyl) -1,3,4-oxadiazole, 1,4-bis [2- (5-phenylthiadiazolyl)] benzene,
2,5-bis (1-naphthyl) -1,3,4-triazole, 3- (4-biphenylyl) -4-phenyl-5
-(4-t-butylphenyl) -1,2,4-triazole and the like, but are not limited thereto. Further, a polymer material used for a polymer organic electroluminescence device can also be used. For example,
Polyparaphenylene and its derivatives, fluorene and its derivatives, and the like.

In the organic EL device shown in FIG. 1, a water absorbing agent 5 is formed on at least the surface of the cathode 4. In the embodiment shown in FIG. 1, the anode 2, the hole transport layer 11, the organic light emitting layer 3, the electron transport layer 12, and the cathode 4
A water-absorbing agent 5 is formed so as to cover the entire exposed outer surface. Here, in the present invention, an organic substance having an isocyanate group is used as the water absorbing agent 5. As shown in the following reaction formula, an organic substance having an isocyanate group has a high ability to chemically adsorb moisture, and also maintains a solid state even after moisture absorption by adsorbing moisture. Not something.

R—NCO + H ₂ O → R—NH ₂
+ CO ₂ Specific examples of the organic substance having an isocyanate group include naphthylene diisocyanate, 4,4-diphenylmethane diisocyanate (MDI), paraphenylene diisocyanate, isopropylidene bis (4-cyclohexyl isocyanate) (IPC), and cyclohexyl diisocyanate. , Tolidine diisocyanate, lysine diisocyanate, tetramethyl xylylene diisocyanate, tolylene diisocyanate (TDI), xylylene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, and the like. It is not particularly limited to these.

Among these organic substances having an isocyanate group, the water absorbing agent 5 has a melting point of 50 from the viewpoint of heat resistance.
It is particularly preferred that the temperature is higher than or equal to ° C. Further, a polymer obtained by polymerizing the above-mentioned organic substance having an isocyanate group can also be used as the water absorbing agent 5. Also in this case, the glass transition temperature is preferably 50 ° C. or higher from the viewpoint of heat resistance.

As described above, in the organic EL device formed by providing the water absorbing agent 5 on at least the surface of the cathode 4, it is possible to prevent water from acting on the inside of the device due to water absorption (moisture absorption) by the water absorbing agent 5. In addition, it is possible to prevent the generation and growth of a non-light-emitting portion called a dark spot. In particular, light enters the organic light-emitting layer 3 and the cathode 4 from the surface of the cathode 4 and separates, thereby emitting light. A dark spot having a portion not to be formed can be effectively prevented by water absorption by the water absorbing agent 5 formed on the surface of the cathode 4. Since the water absorbing agent 5 is formed of an organic material having an isocyanate group, it has a high ability to chemically adsorb moisture as described above, and can effectively remove moisture acting on the element, and Is capable of stably maintaining the light-emitting characteristics of the device over a long period of time, and also maintains a solid state even after moisture absorption by absorbing moisture, which may cause liquefaction and adversely affect the device. It is something that will not be done. The thickness of the water absorbing agent 5 is not particularly limited, but is preferably in the range of 0.01 to 100 μm.

FIG. 2 shows another embodiment of the present invention. In the organic EL device manufactured as shown in FIG. 1, an anode 2 and a hole transport layer 1 are laminated on a substrate 1.
1. The organic light emitting layer 3, the electron transport layer 12, the cathode 4, and the water absorbing agent 5 are surrounded and covered with a protective film 6 that is hardly permeated by moisture. In FIG. 1, the water absorbing agent 5 is formed so as to cover the entire outer surfaces of the anode 2, the hole transport layer 11, the organic light emitting layer 3, the electron transport layer 12, and the cathode 4 laminated on the substrate 1. Therefore, in the embodiment of FIG. 2, the entire outer surface of the water absorbing agent 5 is further covered with the protective film 6.

The protective film 6 is formed of a material through which moisture and oxygen hardly permeate.
By forming the element, it is possible to prevent moisture and oxygen from acting on the element with the protective film 6, and to stably maintain the light emitting characteristics of the organic EL element for a long period of time. .

The protective film 6 blocks moisture and oxygen.
Is not particularly limited as long as it has the function of
Can be used, specifically, organic substances
As para-xylene, and inorganic materials as AlN, Si
O_Two, SiN, MgF_Two, In _TwoO_ThreeEtc.
You. Among them, formed by relatively low temperature CVD method
It is possible to use a silicon nitride film with a low moisture permeability.
Particularly preferable as the protective film 6. The thickness of the protective film 6 is particularly
Although not limited, a range of 0.01 to 100 μm
Enclosures are preferred.

FIG. 3 shows still another example of the embodiment of the present invention. An anode 2, a hole transport layer 11, an organic light emitting layer 3, an electron transport layer The layer 12 and the cathode 4 are stacked, and the sealing plate 7 is arranged so as to face the substrate 1 with the organic light emitting layer 3 and the like interposed therebetween, and further surrounds the organic light emitting layer 3 and the like. By providing the sealing agent 8 between the outer peripheral portion of the substrate 1 and the outer peripheral portion of the sealing plate 7 as described above, the organic light emitting layer 3, the anode 2, the cathode 4, etc. Is sealed. As the sealant 8, a thermosetting resin or the like can be used. In the embodiment of FIG. 3, the water absorbing agent 5 is provided on at least a part of the surface of the sealing plate 7 on the substrate 1 side, that is, at least a part of the inner surface of the sealing plate 7 facing the cathode 4. Other configurations are the same as those in FIG.

In the embodiment of FIG. 4, the water absorbing agent 5 is provided on at least a part of the surface of the cathode 4 as in the case of FIG. Other configurations are the same as those in FIG.

Further, in the embodiment shown in FIG.
Is formed at least in part with the water absorbing agent 5. For example, the water-absorbing agent 5 is mixed into the thermosetting resin, and the sealing agent 8 can be formed from the thermosetting resin containing the water-absorbing agent 5. Other configurations are the same as those in FIG.

In the organic EL device shown in FIGS. 3 to 5,
Since the organic light emitting layer 3, the anode 2, the cathode 4, and the like are sealed between the substrate 1, the sealing plate 7, and the sealant 8, moisture can be prevented from acting on the element, and moisture can be prevented. This water can be removed by the water absorbing agent 5 even if the organic E
The light emitting characteristics of the L element can be stably maintained over a long period of time. Substrate 1, sealing plate 7, and sealant 8
It is preferable that an inert gas such as dry nitrogen gas be sealed in the sealed space between them.

As a method of forming the water absorbing agent 5, when the water absorbing agent 5 is provided on the sealing plate 7 or the cathode 4, for example,
The above-mentioned compound having isocyanate is put into a gas-permeable bag and fixed to the inner surface of the sealing plate 7, or the inner surface of the sealing plate 7 or the cathode 4 by vacuum evaporation or spin coating. There is a method of forming a solid film on the surface. When the water absorbing agent 5 is provided in the sealing agent 8, a method of mixing the solid water absorbing agent 5 into the sealing agent 8,
Water-absorbing agent 5 that is sticky and can bond glass
There is a method of using itself as the sealant 8, and the like.

[0035]

Next, the present invention will be described specifically with reference to examples.

Example 1 An anode 2 made of a transparent electrode having a sheet resistance of 7Ω / □ is formed by sputtering ITO (indium-tin oxide) on a glass substrate 1 having a thickness of 0.7 mm. And ITO glass (manufactured by Sanyo Vacuum Co., Ltd.). The ITO glass substrate was subjected to ultrasonic cleaning with acetone, pure water, and isopropyl alcohol for 15 minutes, dried, and further subjected to UV ozone cleaning.

Next, this ITO glass substrate was set in a vacuum evaporation apparatus, and 1 × 10 ⁻⁶ Torr (1.33 × 10 ^−4).
Under reduced pressure of Pa), 4,4′-bis [N- (naphthyl)-
[N-Phenyl-amino] biphenyl (manufactured by Dojindo Laboratories Inc.) was deposited at a deposition rate of 1-2 ° / s to a thickness of 400 ° to form a hole transport layer 11 on the anode 2.

Next, tris (8-hydroxyquinolinato) aluminum complex (manufactured by Dojindo Laboratories Inc.) was added to 1
A layer was formed on the hole transport layer 11 so as to serve as both the organic light emitting layer 3 and the electron transport layer 12 by vapor deposition at a deposition rate of about 2 Å / s to a thickness of 400 Å.

Next, LiF is first deposited at a deposition rate of 0.5 to 1.0 ° to a thickness of 5 °, and then Al is deposited at a rate of 10 ° / s.
The cathode 4 is deposited on the layer which also serves as the organic light emitting layer 3 and the electron transport layer 12 by vapor deposition at a deposition rate of 1500 °.
Was formed.

Thereafter, the naphthylene diisocyanate is
The organic EL device having the structure shown in FIG. 1 was obtained by forming a film of the water-absorbing agent 5 with a thickness of 1 μm on the cathode 4 by vacuum evaporation.

The organic EL device thus obtained was subjected to a continuous light emission test for 2000 hours by applying a constant current of 10 mA / cm ² . As a result, generation of dark spots was hardly observed.

(Example 2) In Example 1, on the film of the water absorbing agent 5 formed of a naphthylene diisocyanate film,
The protection film 6 was formed by providing silicon nitride with a thickness of 300 nm by the CVD method. Otherwise in the same manner as in Example 1, an organic EL device having a configuration as shown in FIG. 2 was obtained.

The organic EL device thus obtained was subjected to a continuous light emission test for 2000 hours by applying a constant current of 10 mA / cm ² . As a result, generation of dark spots was hardly observed.

(Embodiment 3) In the same manner as in Embodiment 1, the IT
Using O glass (manufactured by Sanyo Vacuum Co.), a hole transport layer 11, a layer which also serves as an organic light emitting layer 3 and an electron transport layer 12, and a cathode 4 were formed on the anode 2.

Next, the ITO glass on which each layer was formed was transported to a glove box in a dry nitrogen atmosphere having a dew point of -76 ° C. or less without being exposed to the air. On the other hand, naphthylene diisocyanate powder as a water-absorbing agent 5 is put in a bag having air permeability, and this is adhered to a sealing plate 7 made of glass with an adhesive. A sealing agent 8 made of a cured resin is applied, a sealing plate 7 is attached to the ITO glass substrate 1 in the glove box with the sealing agent 8, and the sealing agent 8 is cured by UV, as shown in FIG. An organic EL device having such a configuration was obtained.

The organic EL device thus obtained was subjected to a continuous light emission test for 2000 hours by applying a constant current of 10 mA / cm ² . As a result, generation of dark spots was hardly observed.

(Embodiment 4) In Embodiment 3, the sealing plate 7
Instead of attaching a bag containing the water-absorbing agent 5, naphthylene diisocyanate is applied on the cathode 4 by vacuum deposition at 1 μm.
An organic EL device having a configuration as shown in FIG. 4 was obtained in the same manner as in Example 3, except that the water absorbing agent 5 was formed by forming a film having a thickness of m.

The organic EL device thus obtained was subjected to a continuous light emission test for 2000 hours by applying a constant current of 10 mA / cm ² . As a result, generation of dark spots was hardly observed.

(Embodiment 5) In Embodiment 3, the sealing plate 7
Instead of attaching a bag containing the water absorbing agent 5, a polymer (MDI) solution, which is a polymer of diphenylmethane diisocyanate, is spin-coated and a film having a thickness of 100 μm is formed on the sealing plate 7 to form the water absorbing agent 5. An organic EL device having a configuration as shown in FIG. 3 was obtained in the same manner as in Example 3 except for the above.

The organic EL device thus obtained was subjected to a continuous light emission test for 2000 hours by applying a constant current of 10 mA / cm ² . As a result, generation of dark spots was hardly observed.

(Example 6) In Example 3, the water absorbing agent 5
In addition, a powder of paraphenylene diisocyanate is mixed into the sealant 8 for use.
An organic EL device having a configuration as shown in FIG. 5 was obtained in the same manner as in Example 3, except that the water absorbing agent 5 was not provided.

The organic EL device thus obtained was subjected to a continuous light emission test for 2000 hours by applying a constant current of 10 mA / cm ² . As a result, generation of dark spots was hardly observed.

(Comparative Example 1) The same procedure as in Example 1 was repeated except that the water absorbing agent was not used.
An L element was obtained. About 10 mA for this organic EL element
As a result of conducting a continuous light emission test for 2000 hours by applying a constant current of / cm ² , generation and growth of dark spots were confirmed.

(Comparative Example 2) The same procedure as in Example 3 was repeated except that the water absorbing agent was not used.
An L element was obtained. About 10 mA for this organic EL element
As a result of conducting a continuous light emission test for 2000 hours by applying a constant current of / cm ² , generation and growth of dark spots were confirmed.

[0055]

As described above, the organic EL device according to the first aspect of the present invention comprises a substrate, an anode formed of a transparent conductive film formed on the substrate, an organic light emitting layer formed on the anode, and a cathode. In the organic EL device, a water absorbing agent containing an organic material having an isocyanate group is provided on at least a part of the cathode, so that the water absorbing agent made of the organic material having an isocyanate group has a capability of chemically adsorbing moisture. High, it can effectively remove moisture acting on the element, and can stably maintain the light emitting characteristics of the organic EL element for a long period of time. The state is maintained, and no liquefaction adversely affects the element.

According to a second aspect of the present invention, in the first aspect, a protective film hardly permeating moisture is formed so that the water absorbing agent, the cathode, the organic light emitting layer and the anode are surrounded by the substrate and the protective film. Accordingly, these can be covered with a protective film to prevent the action of moisture, and the light emission characteristics of the organic EL element can be stably maintained over a long period of time.

According to a third aspect of the present invention, in the second aspect, since the protective film is formed of a silicon nitride film, the silicon nitride film can be formed at a low temperature such as room temperature, thereby forming the protective film. In this case, it is possible to prevent the characteristics of the organic light emitting layer from deteriorating due to the action of high temperature.

Further, an organic EL device according to a fourth aspect of the present invention includes a substrate, an anode made of a transparent conductive film formed on the substrate, an organic light emitting layer and a cathode formed on the anode,
In an organic EL device in which an organic light emitting layer is sealed by sealing a gap between a substrate and a sealing plate with a sealing agent, a water absorbing agent containing an organic substance having an isocyanate group is provided on at least a part of the cathode or the sealing plate on the substrate side. Since it is provided, in addition to the water absorbing action of the water absorbing agent, it is possible to prevent the water from acting on the element even by sealing with the sealing plate and the sealant, and to improve the light emitting characteristics of the organic EL element for a long time. And can be maintained stably.

An organic EL device according to a fifth aspect of the present invention includes a substrate, an anode made of a transparent conductive film formed on the substrate, an organic light emitting layer and a cathode formed on the anode,
In the organic EL device in which the organic light emitting layer is sealed by sealing the gap between the substrate and the sealing plate with a sealant, at least a part of the sealant is provided with a water-absorbing agent containing an organic substance having an isocyanate group. In addition to the water-absorbing action of the water-absorbing agent provided in the sealant, moisture can be prevented from acting on the element even by sealing with the sealing plate and the sealant, and the light-emitting characteristics of the organic EL element can be reduced over a long period of time. It can be maintained stably.

According to the sixth aspect of the present invention, in the first to fifth aspects, the water-absorbing agent is formed in the form of a film. It is possible to obtain a high removal effect.

The invention of claim 7 is the invention according to claims 1 to 6, wherein naphthylene diisocyanate is used as the water absorbing agent.
4,4-diphenylmethane diisocyanate, paraphenylene diisocyanate, isopropylidene bis (4-
Selected from cyclohexyl diisocyanate), cyclohexyl diisocyanate, tolidine diisocyanate, lysine diisocyanate, tetramethyl xylylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, dicyclohexyl methane diisocyanate, isophorone diisocyanate, and hydrogenated xylylene diisocyanate. Since at least one kind of organic substance is used, these substances have a high ability to chemically adsorb moisture, and maintain a solid state even after the adsorption of moisture.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of an embodiment of the present invention.

FIG. 2 is a sectional view showing another example of the embodiment of the present invention.

FIG. 3 is a sectional view showing still another example of the embodiment of the present invention.

FIG. 4 is a sectional view showing still another example of the embodiment of the present invention.

FIG. 5 is a sectional view showing still another example of the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Organic light emitting layer 4 Cathode 5 Water absorbing agent 6 Protective film 7 Sealing plate 8 Sealing agent

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Junji Kido 9-4-3, Mamikita, Koryo-cho, Kitakatsuragi-gun, Nara Pref. 72) Inventor Yasuhisa Kishigami 1048 Kadoma, Kazuma, Osaka Prefecture F-term in Matsushita Electric Works Co., Ltd.

Claims (7)

[Claims] 1. An organic EL device comprising a substrate, an anode made of a transparent conductive film formed on the substrate, and an organic light emitting layer and a cathode formed on the anode, wherein at least a part of the cathode has an isocyanate group. An organic EL device comprising a water absorbing agent containing an organic substance. 2. A water absorbing agent, a cathode, an organic light emitting layer and an anode,
2. The organic EL device according to claim 1, wherein a protective film that does not easily transmit moisture is formed so as to be surrounded by the substrate and the protective film. 3. The organic EL device according to claim 2, wherein the protective film is formed of a silicon nitride film. 4. An organic light emitting device comprising: a substrate; an anode formed of a transparent conductive film formed on the substrate; an organic light emitting layer and a cathode formed on the anode; and sealing between the substrate and the sealing plate with a sealant. In the organic EL device in which the layer is sealed,
An organic EL device comprising a water absorbing agent containing an organic substance having an isocyanate group provided on at least a part of a cathode or a sealing plate on a substrate side. 5. An organic light emitting device comprising: a substrate; an anode formed of a transparent conductive film formed on the substrate; an organic light emitting layer and a cathode formed on the anode; and sealing between the substrate and the sealing plate with a sealant. In the organic EL device in which the layer is sealed,
An organic EL device comprising a sealant and a water-absorbing agent containing an organic substance having an isocyanate group provided at least in part. 6. The organic EL device according to claim 1, wherein the water absorbing agent is formed in a film shape. 7. A water-absorbing agent comprising naphthylene diisocyanate, 4,4-diphenylmethane diisocyanate, paraphenylene diisocyanate, isopropylidene bis (4-cyclohexyl isocyanate), cyclohexyl diisocyanate, tolidine diisocyanate, lysine diisocyanate, tetramethyl xylylene diisocyanate, 7. The composition according to claim 1, comprising at least one organic substance selected from the group consisting of diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and hydrogenated xylylene diisocyanate. 3. The organic EL device according to claim 1.