JP2002033188A - Organic el display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the corrosion of the layered part of a cathode layer and an ITO leading electrode in a sealed internal space, which often leads to a disconnection, in an organic EL display device having a sealed structure for isolating an organic EL display element from the external atmosphere in which the ITO-leading electrode for guiding a cathode layer electrode out of the sealed space to drive the organic EL element is attached to an ITO anode, and the cathode layer is laminated on and connected to the ITO-leading electrode. SOLUTION: In this organic EL display device having the sealed structure, an intermediate layer area consisting of a hardly corrosive metallic material, e.g., an intermediate layer area hardly corrosive metallic material containing Mn, is formed between the ITO-leading electrode and the cathode layer at least in the laminated position of the ITO-leading electrode and the cathode layer. Accordingly, corrosion in the laminated part within the sealed space can be suppressed to provide an organic EL display device with excellent durability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an organic EL device, an organic electroluminescent device, an organic electroluminescent device, an organic LED device and the like which can be used for, for example, various information display devices, backlights of liquid crystal displays, and the like. The present invention relates to an organic EL display device using an organic electroluminescence element (hereinafter, referred to as an organic EL element) utilizing an electroluminescence phenomenon of an organic thin film to be formed.
The present invention relates to an electrode structure of an organic EL display device in which elements are sealed from an external atmosphere.

[0002]

2. Description of the Related Art Conventionally, an organic EL display element 80 is constructed, for example, as shown in FIG. An anode layer 82 made of a striped ITO (Indium Tin Oxide) transparent electrode provided on a glass substrate 81, and an organic E layer laminated thereon.
It is composed of an L layer 83 and a striped cathode layer 84 orthogonal to the anode layer 82.

According to the organic EL element 80 having such a configuration, by supplying power from an external power supply (not shown) between the pair of electrodes 82 and 84, the organic EL element 83 is separated from the organic EL layer 83 sandwiched between the electrodes 82 and 84. Light emission occurs, which becomes visible. In this example, since a dot matrix type using stripe-shaped electrodes is used, a desired control signal is input to the stripe-shaped anode layer 82 and the cathode layer 84 so that the organic EL layer sandwiched between the electrodes is formed. 83 can be controlled for light emission in dot units.

The anode layer 82 is made of nickel, gold, platinum, palladium, alloys thereof, or metals having a large work function such as tin oxide (SnO ₂ ) or copper iodide, alloys or compounds thereof, and conductive materials such as polypyrrole. Although a conductive polymer or the like can be used, generally, an ITO transparent electrode layer is often used. The cathode layer 84 is preferably made of a metal material having a small work function (low work function metal material) capable of improving electron injection efficiency in order to make the material effective for electron injection. Aluminum, magnesium, magnesium indium alloy, magnesium aluminum Alloys, magnesium silver alloys, aluminum lithium alloys and the like are used. The organic EL layer 83 has a two-layer structure of a hole transport layer 83a and an organic light emitting layer 83b in order from the anode layer 82 side.
N, N′-diphenyl-N,
N'-bis (3-methylphenyl) 1,1'-biphenyl-4,4'-diamine (Triphenyldiamine, hereinafter TPD)
) As the organic light emitting layer 83b.
-Hydroxyquinoline) aluminum (Tris- (8-hydrox
yquinoline) aluminum complex (hereinafter abbreviated as Alq3) and the like.

While the organic EL element 80 having such a structure can emit light at a low voltage, when it is driven as it is in the atmosphere, the deterioration is accelerated by moisture, heat, etc., and the light emission characteristics are deteriorated. In particular, when oxygen or moisture is present around the element, oxidization is promoted, and phenomena such as deterioration of the organic material, peeling of the film, growth of dark spots (non-light-emitting portions), and no light emission appear, resulting in a long life. There is a problem that it is short.

[0006] To solve such a problem, organic E
It has been proposed to seal the L element so that it does not come into contact with the atmosphere. The organic EL display device 90 shown in FIG.
One glass substrate 81 on which the element 80 is formed, and an organic EL
The other sealing substrate 91 that is disposed to face the layer 83 and the like so as to cover the layer 83 and the like.
And the two substrates 8 so that the organic EL layer 83 is not exposed to the outside air.
A seal layer 92 is provided to seal and seal between the first and the first 91.

For example, in Japanese Patent Laid-Open No. 5-41281, a dehydrating agent 96a such as synthetic zeolite is contained in a fluorocarbon oil in a space 93 between an organic EL element 80 and a sealing substrate 91 as shown in FIG. It has been proposed to improve the sealing performance by filling with an inert liquid 96 or the like. According to the present invention, the organic EL element 80 is not exposed to the external atmosphere, so that an organic EL display device having a long life is provided. However, there is a problem that the inert liquid 96 must be filled, and the method of manufacturing the organic EL display device is complicated and time-consuming.

[0008] In Japanese Patent Application Laid-Open Nos. 3-261091 and 9-148066, as shown in FIG. 8B, diphosphorus pentoxide, Drying agent 94 such as barium oxide (BaO)
An organic EL display device 90 having a configuration in which a drying unit 98 in which is fixed by an adhesive 95 and stored is provided.
For example, in the case of using barium oxide powder, an adhesive material 95a such as a double-sided tape is provided on the sealing substrate 91, a small amount of barium oxide powder 94 is fixed thereon, and a polyimide material having micropores to cover them is further provided. These are fixed with an adhesive material 95 such as a tape, and drying means 98 is provided.
The barium oxide 94 is prevented from scattering in the L display device 90. Also in the present invention, there is provided an organic EL display device 90 having a longer life and having the above-described problems such as dark spots.

[0009]

In order to light the above-mentioned organic EL display device 90, an anode 82 and a cathode 84 which are drawn out of a region sealed by the substrates 81 and 91 and an external control (not shown) The organic EL element 80 is driven by connecting a circuit and applying a predetermined electric signal. Therefore, the anode layer 82 made of an ITO transparent electrode or the like is used.
Is extended (left side in the drawing) to form an external extraction anode 82.
a. A part of the cathode layer 84 (the right side in the drawing) is extended to form an externally extracted cathode 84a.

At this time, the externally extracted cathode 84a is connected to FIG.
As shown in (a), when a relatively soft electrode material such as aluminum (Al) is used for the external extraction cathode 84a when the external extraction cathode 84a is formed only with the cathode layer 84, the operation of connecting the external control circuit and the external extraction cathode 84a is performed. During the process, the external extraction cathode 84a is liable to be damaged, for example, causing disconnection. Therefore,
As shown in FIG. 8B, the external extraction ITO 85 provided in the same step as the anode layer 82, and the external extraction ITO 8
It is conceivable that disconnection hardly occurs by adopting a two-layer structure of the external extraction cathode 84a stacked on the cathode 5.

However, this organic EL display device is
When driven in a high-temperature atmosphere of 5 ° C. or more, in the externally-acquired cathode 84 a of this laminated structure, corrosion may occur in the laminated portion 97 in the void located in the sealed void 93, and disconnection may occur. XPS
((X-ray Photoelectron Spectroscopy) analysis revealed that aluminum oxide was formed. The void 93, which is a sealing space of the organic EL display device 90, was sealed in a nitrogen atmosphere. In addition, an external extraction cathode 84a laminated on the external extraction ITO 85
In the two-layer structure described above, no remarkable change was observed in the portions exposed to the outside other than the laminated portion 97 in the gap.

The organic EL display device 90 shown in FIG.
In the above, three kinds of different types are used: a case where a single aluminum metal is used as the external extraction cathode 84a, a case where an alloy of aluminum and lithium is used, and a case where a layer of a lithium layer and aluminum whose film thickness monitor value is 100 nm or less is formed. When the organic EL display device 90 having the above configuration was manufactured and a driving test was performed in a high temperature atmosphere of 85 ° C. or higher, corrosion was observed in the laminated portion 97 within the voids after several days in any case, and other portions were observed. No corrosion was observed. In addition, a similar test was performed using nitrogen gas sealed in the void and oxygen added, and the same result was obtained.

From these results, it is understood that the corrosion due to oxidation of the laminated portion 97 in the gap is not related only to the amount of residual oxygen in the atmosphere of the gap 93 or the interface between the ITO 85 for external extraction and the cathode 84a for external extraction. It was presumed that this would be a problem specific to the organic EL display device 90 provided with the drying means. Therefore, the present invention relates to an organic EL display device provided with a drying unit in a sealed space, wherein an ITO 8 for external extraction is provided.
The first object is to effectively prevent corrosion in the laminated portion 97 in the air gap between the cathode 5 and the externally extracted cathode 84a.

[0014]

According to one aspect of the present invention, there is provided a first substrate on which an organic EL element is formed, sealing means for separating the organic EL element from an external atmosphere, and an organic EL element. In an organic EL display device having an electrode terminal led out from the sealing means to supply an electric signal to an electrode of the element, the first substrate includes an anode layer made of a translucent electrode material, an organic material, EL provided with light emitting layer made of
EL device having a layer and a cathode layer laminated in this order;
An external extraction electrode made of the same material as the anode layer of the device is provided, and the external extraction electrode has a cathode layer laminated thereon,
An organic EL, wherein an intermediate layer region containing a hardly corrosive metal material is formed between the external extraction electrode and the cathode layer at least in a laminated portion of the cathode layer and the external extraction electrode. Display device.

According to the invention of this aspect, corrosion in the laminated portion is remarkably reduced, and the organic EL having a long life and high reliability is provided.
A display device may be obtained.

According to another aspect of the present invention, the external electrode is an ITO electrode, and the cathode layer is an electrode mainly composed of aluminum.
The above-mentioned object is achieved by the L display device. ADVANTAGE OF THE INVENTION According to this invention, the corrosion action in the laminated part of an ITO electrode and an aluminum electrode in a sealing space can be suppressed remarkably.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS. In the following description, portions having the same function are denoted by the same reference numerals for the sake of easy understanding, and portions having overlapping descriptions are partially omitted.

FIGS. 1 and 2 show an organic EL according to the present invention.
1 shows a configuration of a first embodiment of a display device. In FIG. 1 and FIG. 2, an organic EL display device 10 includes two glass substrates 11 and 1 disposed one above the other in parallel with each other.
2, an organic EL element 16 including an anode layer 13, an organic EL layer 14, and a cathode layer 15 sequentially laminated from the lower side on the lower first glass substrate 11, and the upper second glass substrate 1
2 includes a drying means 4 provided on the inner surface, and a seal layer 17 for adhering and fixing both substrates so as to surround the periphery of the organic EL element 16. Further, a part of the anode layer 13 and a part of the cathode layer 15 are led out to the outside from the substrate edge portions 11a and 11b, which are different sides of the first glass substrate, and serve as terminals that can be connected to a control device (not shown).

The EL element 16 is provided on the inner surface of the first glass substrate 11 serving as an organic EL element substrate (the upper surface side in FIG. 2).
Is formed. The anode layer 13 is formed of an ITO transparent electrode patterned into a predetermined shape on the inner surface of the first glass substrate, and a part thereof is extended to the substrate edge 11a outside the seal layer 17 to form an external extraction anode 13a. ing. Further, on the side near the substrate edge 11b, an external extraction ITO 2
0 is also formed in the same step, and a terminal group connectable to a control device (not shown) is provided.

The cathode layer 15, which is the other electrode, has a two-layer structure of a first cathode layer 15a and a second cathode layer 15b, each having a thin film of less than 100 nm at the interface with the organic EL layer 14. The cathode layer 15 is preferably made of a material having a lower work function and a higher electron injection efficiency than the anode layer 13 and a low resistance to corrosion. Therefore, an alkali metal, for example, lithium (Li) is vapor-deposited as the first cathode layer 15a, and aluminum is sequentially vapor-deposited and formed as the second cathode layer 15b. Further, the second cathode layer 15b is formed to have a predetermined shape by using an unillustrated vapor deposition mask or the like so as to be laminated also on the external extraction ITO 20.

The organic EL layer 14 includes the anode layer 13 and the cathode layer 1.
5 and a desired light emission can be obtained from the organic EL layer 14 by applying a current between both electrodes. Organic EL
The layer 14 is formed as, for example, a two-layer structure of a hole injection / transport layer 14a and an organic light emitting layer 14b in order from the anode layer 13 side. The organic EL layer 14 further includes an organic light emitting layer 14.
b, a three-layer structure in which an electron transport layer having a function of facilitating the injection of electrons from the cathode layer 15 or a hole injection layer / hole transport layer / light emitting layer / electron transport layer; A multi-layer structure composed of a hole transport layer / light-emitting layer, a hole transport layer / light-emitting layer / electron transport layer, or a single-layer organic EL layer;
An EDOT (Poly (3,4) ethylenedioxythiophene) buffer layer provided with a single-layer organic layer via a buffer layer may be used.

The second glass substrate 12 serving as a sealing substrate is smaller in size than the first glass substrate 11, and various materials such as metals, resins and ceramics can be used without being limited to glass. When light is emitted to the outside from the first glass substrate 11, the second glass substrate may be made of a light-shielding substrate material.

A drying agent 2 is provided inside the second glass substrate 12.
A drying means 4 is provided in which a barium oxide powder is adhered with a double-sided tape 1 and then fixed by covering them with a polyimide tape 3 having small holes. As the drying agent used as the drying means 4, various fine powder solid substances that physically and / or chemically adsorb moisture can be used other than barium oxide (BaO). For example, a desiccant such as activated carbon, zeolite, activated alumina and silica gel that physically adsorbs water, diphosphorus pentoxide (P ₂ O ₅ ), calcium oxide (CaO), and magnesium oxide Alkali metal oxides such as MgO), sodium oxide (Na ₂ O), lithium sulfate (Li ₂ SO ₄ ), sodium sulfate (Na ₂ S)
O ₄ ), sulfates such as calcium sulfate (CaSo ₄ ),
Metal halides such as calcium chloride (CaCl ₂ ), strontium chloride (SrCl ₂ ), tantalum fluoride (TaF ₅ ), magnesium bromide (MgBr ₂ ), barium iodide (BaI ₂ ), and barium perchlorate (Ba ( Cl
Perchlorates such as O ₄ ) ₂ ) can be used. Also, calcium hydride (CaH ₂ ) and lithium aluminum hydride (AlLiH ₄ ) described in JP-A-2000-3783, and JP-A-2000-11397.
No. 6 strontium hydride (Sr
Compounds such as H ₄ ) and barium hydride (BaH ₂ ) can also be used. These have a particle size of 1 to 100 μm,
Preferably, the thickness is about 10 μm. This is because if the particle size is too large, the void 19 must be provided large.

The seal layer 17 is made of, for example, an ultraviolet curable resin,
The organic EL element 16 is made of a thermosetting resin or the like, surrounds the periphery of the organic EL element 16, and the first glass substrate 11 and the second glass substrate 12 are bonded and fixed to hermetically seal the organic EL element 16 from an external atmosphere. When the substrates 11 and 12 are sealed, the sealing is performed in an inert gas atmosphere such as high-purity nitrogen in which impurities are controlled so that oxygen and moisture do not actively remain in the voids 19. are doing.

The configuration up to this point is basically the same as that of the conventional organic EL display device. However, in the embodiment of the present invention, at least the interface between the external extraction cathode 15 c and the external extraction ITO 20, particularly, The intermediate layer 21 is formed on the interface 22a in the sealing inner laminated portion 22.

The intermediate layer 21 is provided to prevent the cathode layer 15 from being corroded in the encapsulation laminated portion 22 when the organic EL display device 10 is driven in a high temperature environment. Cr, Mg, Ni, Mn-Al alloy (Mn content about 1.2%), Al-Mg alloy, Al-
A non-corrosive metal material such as an Mg-Si alloy is used. When the alloy material is formed by a vapor deposition method or the like, it is preferable to use an alloy material with little adverse effect even if a composition change occurs,
(A) is better than an alloy having a large melting point difference such as a Mn-Al alloy.
(melting point of l = 660 ° C., melting point of Mn = 258 ° C.), an alloy obtained by adding Mg (melting point = 650 ° C.) to Al, and the like are more preferable. Further, when the amount of the hardly corrosive metal material such as Mn added to the Al alloy is in the range of 0.01 to 20%, the effect of preventing corrosion is high. The thickness of the intermediate layer 21 is formed to be greater than 0.5 nm, preferably 1 to 10 nm, as monitored by a film thickness monitor using a quartz oscillator. In the present embodiment, after the organic EL layer 14 is formed, the organic EL layer 14 is transferred to a vapor deposition chamber while maintaining a vacuum state, and the first cathode layer 15a, the intermediate layer 21, and the second cathode layer 15b are continuously formed. The intermediate layer 21
Need only be at least in the encapsulation lamination part 22, and the organic EL
It is optional for the cathode terminal 15c on the element 14 or outside.

Organic EL display device 1 sealed as described above
Even at 0, if the thickness of the intermediate layer 21 is smaller than 0.5 nm, the corrosion prevention effect becomes poor. Conversely, if the thickness of the intermediate layer 21 is greater than 10 nm, the voltage-current characteristics tend to decrease, so it is preferable that the thickness be smaller than this.
However, this does not apply to the case where the intermediate layer 21 is not formed in the organic EL element 16 portion but formed only in the laminated portion 22.

The organic EL display device 10 is configured as described above, and corrosion does not occur even when a continuous lighting test is performed in a high-temperature environment of 85 ° C. or higher.

FIG. 3 shows an organic EL according to another embodiment of the present invention.
1 shows a display device 30. The organic EL display device 30 includes two glass substrates 11,
12, an anode layer 13, an organic EL layer 14, and a cathode layer 35, which are sequentially laminated on the lower first glass substrate 11 from below.
, A drying means 4 provided on the inner surface of the upper second glass substrate, and a seal layer 17 for bonding and fixing the two substrates so as to surround the periphery of the organic EL element.
And is composed of Further, the anode layer 13 and the cathode layer 15 are connected to the substrate edge 1 which is a different side of the first glass substrate.
It is led out from the 1a and 11b sides, and has the same configuration as the organic EL display device 10 of the previous embodiment.

In the above embodiment, a cathode layer having a two-layer structure of an alkali metal and an aluminum second cathode layer is used as the cathode layer, and the intermediate layer 21 is disposed in the sealing inner laminated portion 22 and the organic EL element 16 portion. However, in this embodiment, an aluminum-lithium alloy is used as the cathode layer 35, and the cathode layer 35 is laminated on the ITO 20 for external extraction only through the intermediate layer 21 only at the location of the lamination part 22 inside the sealing. In other places, the layers are laminated without the intermediate layer 21 interposed therebetween. The intermediate layer 21 is formed in a predetermined shape using an evaporation mask after forming the organic EL layer 14 and before forming the cathode layer 35.

The organic EL display device 30 is configured as described above. Even when a continuous lighting test is performed in a high-temperature environment of 85 ° C. or more, the organic EL display device 30 is significantly corroded as compared with the case where the intermediate layer 21 is not formed. The occurrence has been reduced.

FIG. 4 shows an organic EL display device 40 according to still another embodiment of the present invention. The organic EL display device 40 includes two glass substrates 11 and 12 that are arranged parallel to one another and that are vertically stacked to form a sealed space, the organic EL element 16 disposed in the sealed space, and the drying unit 4. And the basic configuration is the same as that of the organic EL display device 10 in the above embodiment.

In this embodiment, an ITO 20 for external extraction and an ITO layer to be the anode layer 13 are formed,
Subsequently, Mn was continuously formed as the intermediate layer 21, and thereafter, the intermediate layer 21, the ITO 20 for external extraction, and the anode layer 13 were etched into a predetermined shape using a known photolithography technique. Next, the organic EL layer 14 and the cathode layer 15 are sequentially laminated and formed, and the cathode layer 15 and the external extraction ITO 20 are electrically connected in the sealing inner laminated portion 22 to form the organic EL display device 40. .

The organic EL display device 40 is configured as described above. Even when a continuous lighting test is performed in a high-temperature environment of 85 ° C. or more, the organic EL display device 40 is significantly corroded as compared with the case where the intermediate layer 21 is not formed. The occurrence has been reduced. An anode layer 13 made of an ITO transparent electrode and an ITO 20
Can be formed into a predetermined shape continuously after the film is integrally formed, so that the intermediate layer 21 can be reliably provided at a predetermined position.

Although the above-described embodiment is a preferred specific example of the present invention, various technically preferable limitations are given. However, the scope of the present invention is not limited to these embodiments. Various modifications are also included in the present invention. For example, as the intermediate layer 21, a material having a high adhesion strength to the external extraction ITO 20 or the cathode layer 15 (Mn or Mn)
(In the case of using an Al alloy, the adhesion strength is higher than that in the case of using Au)), so that peeling does not easily occur at the place where the seal layer 17 is provided and even when the intermediate layer 21 is still formed. Appropriate applications such as are also included in the present invention.

Hereinafter, the present invention will be described with reference to specific examples. [Sample 1] A resistance value of 10Ω /
The ITO transparent electrode 13 of □ was formed by a sputtering method, the transparent electrode 13 was etched into a predetermined shape using a known photolithography method, and then subjected to ultrasonic cleaning using acetone, isopropyl alcohol, etc., and dried. After the substrate 11 is further subjected to ultraviolet cleaning, it is set in a vacuum evaporation tank,
The pressure inside the vacuum chamber was reduced to about 1 × 10 ⁻⁵ Torr.
Here, first, TPD is used as a hole transport layer in an amount of 0.2 to 0.4.
100 nm is deposited at a deposition rate of nm / sec, and then Alq3 is applied as a green light-emitting layer at 0.2 to 0.4 nm / sec.
100 nm was deposited at a deposition rate of c. Subsequently, while maintaining a vacuum state, Li is 0.1 nm, and M
n was continuously deposited as 5 nm and Al as the cathode layer 15 was 0.14 μm. On the other hand, a double-sided tape 1 is provided on the inner surface of the second glass substrate 12, a BaO powder desiccant 2 is adhered thereon, and further fixed by a polyimide tape 3 provided with micropores so as to cover them. Drying means 4 was provided.
A first glass substrate on which the organic EL element 16 is formed and a second glass substrate provided with the drying means 4 are overlapped with a predetermined gap 19 so that the organic EL element 16 and the drying means 4 face each other; The edge was sealed with a seal layer 17. Seal layer 1
7 is to apply the photo-curable adhesive to the second before performing the superposition.
A glass substrate was formed with a width of 2 mm on an edge portion thereof using a dispenser, and was bonded to the first glass substrate using this substrate. Note that these sealing steps are performed in a high-purity nitrogen atmosphere in which the content of water and the amount of impurities are controlled,
The space 19 was filled with high-purity nitrogen.

[Comparative Sample] An organic EL display device was manufactured under the same conditions as in Sample 1 except that the Mn intermediate layer 21 was not provided.

[Sample 2] The thickness of the Mn intermediate layer 21 was 2
Organic EL under the same conditions as sample 1 except that
A display device was manufactured. [Sample 3] An organic EL display device was manufactured under the same conditions as in Sample 1 except that the thickness of the Mn intermediate layer 21 was changed to 0.1 μm. [Sample 4] An organic EL display device was manufactured under the same conditions as in Sample 1 except that the thickness of the Mn intermediate layer 21 was changed to 60 nm. [Sample 5] Al-Mn alloy (Mn
An organic EL display device was manufactured under the same conditions as in Sample 1 except that 0.1 μm (about 1.2 wt%) was formed. [Sample 6] An organic EL display device was manufactured under the same conditions as in Sample 1, except that 200 nm of Au was formed as the intermediate layer 21 to make ITO / Au / Li / Al. [Sample 7] An organic EL display device was manufactured under the same conditions as in Sample 1 except that 200 nm of Ni was formed as the intermediate layer 21 to obtain ITO / Ni / Al. [Sample 8] An organic EL display device was manufactured under the same conditions as in Sample 1 except that 200 nm of Ag was formed as the intermediate layer 21 to make ITO / Ag / Al. [Sample 9] Organic EL display device under the same conditions as the comparative sample except that only double-sided tape 1 and BaO powder 2 were used as drying means 4 provided on the second glass substrate and were not fixed with polyimide tape 3. Was prepared. [Sample 10] An organic EL display device was manufactured under the same conditions as the comparative sample except that no drying means 4 was provided on the second glass substrate.

Each of the comparative sample and the working sample thus prepared was subjected to an electric current test in a high-temperature environment at a temperature of 85 ° C. FIGS. 5, 6, and 7 are enlarged micrographs of the surface observation results of the laminated portion and the like in the sealing of the representative sample after the current test was performed in such an environment. FIG.
In (a), the cathode 20 for ITO external connection and Li / A
1 shows a laminated portion with the cathode layer 15, and FIG.
5 is an enlarged photograph. As shown in the drawing, corrosion is observed in the laminated portion (denoted as ITO / Al in the drawing),
Corrosion was not observed in the Li / Al electrode portion having no laminated structure (described as Al in the figure).

FIG. 6C shows Sample 1 in which Mn was provided as an intermediate layer 21 over the entire observation region.
(D) shows the sample 5 in which Al-Mn is provided as the intermediate layer 21 on the entire surface of the observation region, and (e) shows the sample 6, but the intermediate layer 21 is provided in a half area on the left side.
However, the intermediate layer 21 is not formed in a region on the right half. Therefore, corrosion was observed in the laminated portion where no intermediate layer was formed. In addition, the enlarged micrographs of these surface observation results are observed at the same magnification as in FIG. In FIG. 7, (f) and (g) show a sample 7 provided with Ni as the intermediate layer 21.
And Sample 8 provided with Ag as the intermediate layer 21.
The intermediate layer 21 is present in a region approximately half of the left side of the drawing, but the intermediate layer 21 is not formed in a region approximately half of the right side. (H) shows the surface state of Sample 9, in which no intermediate layer is formed over the entire observation region. The enlarged micrographs of these surface observation results are also observed at the same magnification as in FIG.

In the comparative sample (FIGS. 5 (a) and 5 (b)) and the sample 8 (FIG. 7 (g)), corrosion occurred in the laminated portion within one day. Analysis of the corroded portion by XPS showed that the aluminum cathode was oxidized. Sample 1 (FIG. 6 (c)), Samples 2, 3 and 4 (not shown), Sample 5 (FIG. 6 (d)), Sample 6 (FIG. 6 (e)) and Sample 7 (FIG. 7 (f)) The sample No. had the same surface state as the initial stage without corrosion of the laminated portion even after 15 days or more. In these samples, almost no change was observed in the current-voltage characteristics and the light emission starting voltage. In sample 9 (FIG. 7 (h)), the laminated portion hardly changed after about 3 days, but after 10 days or more, deterioration was observed. Further, the growth of dark spots in the light emitting portion of the organic EL element 16 was not observed in any of the organic EL display devices of Samples 1 to 9 and Comparative Example. In sample 10 (not shown), no change was observed in the laminated portion even after about 3 days, but the organic E
A dark spot grew in the light emitting portion of the L element 16, and good light emission could not be obtained.

When the sample 9 is compared with the comparative sample,
The only difference is whether or not the polyimide tape 3 is fixed. Nevertheless, the above differences appeared. Although the cause is not clear, in an organic EL display device in which BaO is fixed with polyimide tape and sealed, barium oxide reacts with moisture to form barium hydroxide, and the barium hydroxide and the polyimide tape are combined. If present, it is presumed that the above-mentioned corrosion phenomenon, particularly the oxidation phenomenon of aluminum at a portion where aluminum and the ITO transparent electrode are laminated, remarkably progresses. In Samples 1 to 7 of the organic EL display device having a configuration in which such a corrosion phenomenon is easily exposed, corrosion was effectively prevented. Organic E like sample 10 without means
If other causes of defects such as dark spots can be solved in the L display device, an organic EL display device having excellent characteristics in which a corrosion phenomenon is prevented by using the present invention will be obtained.

[0043]

As described above, according to the present invention, in a sealed organic EL display device, in a sealing inner laminated portion where an ITO electrode is laminated to take out a cathode layer outside a sealing region, By providing the intermediate layer, corrosion of the cathode layer material can be effectively reduced.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a first embodiment of an organic EL display device according to the present invention.

FIG. 2 is a schematic sectional view showing an AA part of the organic EL display device of FIG.

FIG. 3 is a schematic sectional view showing an organic EL display device according to another embodiment of the present invention.

FIG. 4 is a schematic sectional view showing an organic EL display device according to still another embodiment of the present invention.

FIG. 5 is an enlarged photograph of the comparative sample of the organic EL display device, showing the state of corrosion of the laminated portion.

FIG. 6 is an enlarged photograph of the representative sample of the organic EL display device, showing the state of corrosion of the laminated portion.
(C) shows sample 1, (d) shows sample 5, and (e) shows sample 6.

FIG. 7 is an enlarged photograph of the representative sample of the organic EL display device, showing the state of corrosion of the laminated portion.
(F) shows sample 7, (g) shows sample 8, and (h) shows sample 9.

FIG. 8 is a schematic sectional view illustrating a conventional organic EL display device.

FIG. 9 is a partially cutaway perspective view illustrating a conventional dot matrix type organic EL element.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 double-sided tape 2,94 desiccant 3 polyimide tape 4,98 drying means 10,30,40,90 organic EL display device 11,81 first glass (organic EL element) substrate 12,91 second glass (sealing) substrate 13, 82 Anode layer 14, 83 Organic EL layer 15, 35, 84 Cathode layer 16, 80 Organic EL element 17, 92 Seal layer 20, 85 ITO 21 for taking out outside Intermediate layer 22, 97 Sealing lamination part 93 Void 96 Inert liquid

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tsutomu Akagi 2-13-1 Nakameguro, Meguro-ku, Tokyo F-term in Stanley Electric Co., Ltd. (reference) 3K007 AB11 BA06 BB01 BB05 CA01 CB01 CC05 DA01 DB03 EB00 FA02

Claims (2)

[Claims] A first substrate on which an organic EL element is formed;
An organic EL display device comprising: a sealing unit that separates the organic EL element from an external atmosphere; and an electrode terminal that is led out of the sealing unit to supply an electric signal to an electrode of the organic EL device. An anode layer made of a translucent electrode material,
An organic EL element having a light emitting layer made of an organic material and an organic EL element in which a cathode layer is sequentially laminated, and an external extraction electrode made of the same material as the anode layer of the organic EL element are provided. The external extraction electrode includes a cathode. Layers are laminated, and an intermediate layer region containing a hardly corrosive metal material is formed between the external extraction electrode and the cathode layer at least in a laminated portion of the cathode layer and the external extraction electrode. An organic EL display device comprising: 2. The organic EL display device according to claim 1, wherein said external extraction electrode is an ITO electrode, and said cathode layer is an electrode mainly composed of aluminum.