JP2002043055A - Organic electroluminescent element and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a more simple and surer drying means for organic EL element. SOLUTION: This method of manufacturing an organic EL element, having a layered body 1 formed by pinching at least an organic light emitting layer between a counterposed pair of electrodes, an airtight container 3 for housing the laminate so as to shield it from the outside air and a drying means 4, arranged separately from the laminated body inside of the airtight container. As the drying means, a moisture absorbing formed body is fixed to at least one part inside of the airtight container.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel organic EL device and a method for manufacturing the same.

[0002]

2. Description of the Related Art An organic EL (electroluminescence) element has a structure in which an organic light emitting layer made of an organic compound is sandwiched between a pair of electrodes. Organic EL elements are expected to be used for flat panel displays and the like because they have characteristics such as high-luminance light emission, high-speed response, high energy conversion rate, and high color developing properties.

However, when the organic EL element is driven for a certain period, the light emission characteristics such as light emission luminance and light emission uniformity may deteriorate with time. This phenomenon is a problem due to so-called black spots (dark spots). That is, the organic EL
Moisture adsorbed on the surface of the component of the element or invaded into the organic EL element penetrates into the laminate composed of the pair of electrodes and the luminescent material sandwiched between them through defects on the surface of the cathode, etc. And the cathode are separated from each other, and as a result, energization is hindered, so that a portion where light emission is impossible, that is, a so-called black spot is generated.

In order to solve the problem of black spots, organic E
It is necessary to lower the humidity inside the L element. As one method for reducing the humidity, for example, a structure in which a protective layer containing a desiccant and a sealing layer are further laminated on the outside of a structure formed by laminating an anode, an organic luminescent material, and a cathode (particularly, Kaihei 7
No. 169567) is known.

[0005] However, in the above technique, another problem occurs due to the formation of the protective layer. That is, leakage current and crosstalk are likely to occur due to the formation of the protective layer, which may adversely affect light emission characteristics.

On the other hand, a laminate in which an organic light emitting material layer is sandwiched between a pair of electrodes facing each other is housed in an airtight case, and is separated from the laminate to form diphosphorus pentoxide (P ₂₎ in the airtight case.
There is known an organic EL device in which a laminate and a drying unit are hollow-sealed in an airtight case by disposing a drying unit made of O ₅ ) (Japanese Patent Application Laid-Open No. 3-26991).

However, in this technique, P ₂ O _{5 as} a desiccant absorbs water vapor in the atmosphere and dissolves to form phosphoric acid, and this phosphoric acid adversely affects the laminate. In addition, since the method of enclosing the drying means made of P ₂ O ₅ is limited, it is not suitable for production on an industrial scale.

[0008]

Accordingly, an object of the present invention is to provide a simpler and more reliable drying means in an organic EL device.

[0009]

Means for Solving the Problems In view of these problems of the prior art, the present inventor has made extensive studies and found that the above object can be achieved by fixing a hygroscopic molded article in an airtight container. Thus, the present invention has been completed.

That is, the present invention provides the following organic EL
The present invention relates to an element and a method for manufacturing the element.

1.1) A laminate having at least an organic light-emitting layer sandwiched between a pair of opposing electrodes, 2) an airtight container for housing the laminate and shutting off outside air, and 3) inside the airtight container. An organic EL element having a drying means arranged separately from the laminate, wherein a hygroscopic molded body is fixed to at least a part of the airtight container as the drying means. Organic EL element.

2. Item 2. The organic EL device according to Item 1, wherein the hygroscopic molded article contains a hygroscopic agent and a resin component.

3. Item 1. The hygroscopic molded article is obtained by molding a mixture comprising a hygroscopic agent and a resin component.
The organic EL device according to the above.

4. 4. The organic EL device according to the above item 2 or 3, wherein the moisture absorbent contains at least one of an alkaline earth metal oxide and a sulfate.

[0015] 5. Item 4. The organic EL device according to item 2 or 3, wherein the resin component is at least one kind of gas-permeable resin.

6.1) A laminate having at least an organic light-emitting layer sandwiched between a pair of electrodes facing each other, 2) an airtight container for housing the laminate and shutting off outside air, and 3) inside the airtight container. A method of manufacturing an organic EL device having a drying means disposed separately from the laminate, comprising a step of fixing a hygroscopic molded body as a drying means to at least a part of the airtight container. Of manufacturing an organic EL device.

7.1) A laminate in which at least an organic light emitting layer is sandwiched between a pair of electrodes facing each other, 2) an airtight container for containing the laminate and shutting off outside air, and 3) an inside of the airtight container In the method for producing an organic EL device having a drying means separated from the laminate, a first step of producing a hygroscopic molded article containing a hygroscopic agent and a resin component, and using the hygroscopic molded body as a drying means A method for manufacturing an organic EL device, comprising a second step of fixing the organic EL device to at least a part of the airtight container.

[8] Item 8. The method according to Item 7, wherein the first step is a step of forming a mixture comprising a hygroscopic agent and a resin component to manufacture a hygroscopic molded article.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The organic EL device of the present invention is 1) a laminate having at least an organic light emitting layer sandwiched between a pair of electrodes facing each other, and 2) an airtight device for accommodating the laminate and blocking outside air. And 3) an organic EL device having a drying means disposed in the airtight container so as to be separated from the laminate, wherein a moisture-absorbing molded body is at least part of the airtight container as the drying means. Characterized in that it is fixed to

That is, the organic EL device of the present invention uses a known organic E
Components of L element (electrode (anode / cathode), organic light emitting layer,
Containers (airtight containers), substrates, carriers, etc.) can be employed. Therefore, for example, an organic EL element (1) having a configuration as shown in FIG. 1 can be employed. In this organic EL device, a laminate (6) composed of an ITO electrode (3), an organic light emitting layer (4) and a cathode (5) is formed on a glass substrate (2), and dried so as not to come into contact with the laminate. Means (8) are provided, and these are sealed by a glass sealing can (7) and a sealing material (9).

In the organic EL device shown in FIG. 1, the laminate (6) has a three-layer structure including the ITO electrode (3), the organic light emitting layer (4) and the cathode (5). In addition to the above-described layers, a multilayer structure in which one or two or more of an electron transport layer, a hole transport layer, and the like are stacked as a carrier transport layer may be employed as needed.

On the glass substrate (1), a laminate (6) in which an ITO electrode (3), an organic light emitting layer (4), and a cathode (5) are laminated in order is formed. Drying means (8) are arranged in isolation. The laminate (6) and the drying means (8) are sealed in an airtight container in which the glass substrate (1) and the glass sealing can (7) are airtightly bonded by a sealing material (9). I have. The inside of the hermetic container is filled with a dry inert gas or maintained in a vacuum or a state close to the vacuum.

In the present invention, the hygroscopic molded article is fixed to at least a part of the airtight container as the drying means.

The hygroscopic molded article is not particularly limited as long as it can reduce or remove moisture in the airtight container. For example, a molded article containing a moisture absorbent and a resin component can be suitably used. The shape of the hygroscopic molded body is not limited,
What is necessary is just to set suitably according to the use of the final product, the purpose of use, the site | part used, etc. For example, a sheet form, a pellet form, a plate form, a film form, a granule (granulated body) etc. can be mentioned. These sizes and the like can be appropriately set according to the size and the like of the container.

The hygroscopic agent may be any as long as it has at least a function of adsorbing moisture, and is particularly preferably a compound which chemically adsorbs moisture and maintains a solid state even if it absorbs moisture. Such compounds include, for example, metal oxides and inorganic and organic acid salts of metals. In the present invention, it is particularly preferable to use at least one of alkaline earth metal oxides and sulfates.

Examples of the alkaline earth metal oxide include calcium oxide (CaO), barium oxide (BaO),
Magnesium oxide (MgO) and the like.

As the sulfate, for example, lithium sulfate (L
i_TwoSO_Four), Sodium sulfate (Na _TwoSO_Four), Calcium sulfate
Cium (CaSO_Four), Magnesium sulfate (MgS
O_Four), Cobalt sulfate (CoSO_Four), Gallium sulfate (G
a_Two(SO_Four)_Three), Titanium sulfate (Ti (SO_Four)_Two), Sulfuric acid
Nickel acid (NiSO_Four) And the like. Other
Also, an organic material having hygroscopicity is used as the hygroscopic agent of the present invention.
Can be used.

On the other hand, the resin component is not particularly limited as long as it does not hinder the moisture removing action of the moisture absorbent, and is preferably a material having a high gas permeability (ie, a material having a low barrier property, especially a gas permeable material). Resin). Examples of such a material include polymer materials such as polyolefin, polyacryl, polyacrylonitrile, polyamide, polyester, epoxy, and polycarbonate. Among these, a polyolefin-based material is preferred in the present invention. Specifically, polyethylene,
In addition to polypropylene, polybutadiene, polyisoprene and the like, copolymers of these and the like can be mentioned.

In the present invention, the contents of the hygroscopic agent and the resin component may be appropriately set according to the type of the hygroscopic agent and the resin component. The weight ratio may be about 70% to about 15% by weight. Preferably, the amount is about 40 to 80% by weight of the hygroscopic agent and 60 to 20% by weight of the resin component, and most preferably about 50 to 70% by weight of the hygroscopic agent and 50 to 30% by weight of the resin component.

The hygroscopic molded article is obtained by uniformly mixing these components and molding them into a desired shape.
In this case, it is preferable that the moisture absorbent, the gas adsorbent, and the like are sufficiently dried in advance and then mixed. When mixing with the resin component, the mixture may be heated to a molten state as necessary. As a forming method, a known forming or granulating method may be adopted. For example, in addition to press forming (including hot press forming), extrusion forming, and the like, a rolling granulator, a twin-screw granulator, or the like is used. Granules can be applied.

In the present invention, the hygroscopic molded article is desirably obtained by molding a mixture comprising a hygroscopic agent and a resin component. That is, by producing a hygroscopic molded body using a material that does not contain a third component such as a solvent,
Detrimental effects of these third components remaining in the molded article (for example, the remaining solvent is adsorbed by the desiccant to reduce the performance of the adsorbent, or the remaining solvent is volatilized with time in an airtight container. Harmful effects of the operation) can be avoided.

When the hygroscopic molded article is in the form of a sheet, a sheet obtained by further stretching the sheet can be suitably used as the hygroscopic sheet. The stretching process is
What is necessary is just to implement according to a well-known method, and any of uniaxial stretching, biaxial stretching, etc. may be sufficient. Further, a fluororesin is used as a resin component, and a mixture containing the fluororesin and a hygroscopic agent is formed and processed into a sheet shape, and further a fibrillated product can be suitably used.

When the hygroscopic molded article is formed into a sheet, the thickness of the sheet may be appropriately set according to the intended use of the final product. For example, when the organic EL device of the present invention is used for a display of a mobile phone, it is usually 50 to 400.
It may be about μm, preferably 100 to 200 μm.

In the organic EL device of the present invention, the hygroscopic molded article is fixed to at least a part of the hermetic container. The fixing method is not particularly limited as long as it can be fixed to the airtight container without fail. For example, a method of attaching a hygroscopic molded article and an airtight container to a known adhesive, an adhesive (preferably a non-solvent type adhesive) or the like, a method of heat-sealing the hygroscopic molded article to the airtight container, A method of fixing the molded body to the airtight container with a fixing member such as a screw may be used.

For example, an adhesive layer having release paper can be formed on a moisture-absorbent sheet, and when fixed to an airtight container, the release paper can be peeled off and fixed with the adhesive layer. Further, it can be fixed to an airtight container with a solventless adhesive using an ethylene vinyl alcohol copolymer (EVOH) or the like. Commercial products can also be used as the solventless adhesive.

In the present invention, the airtight container may be subjected to a surface enlargement treatment before fixing the hygroscopic molded article. A portion of the inner surface of the airtight container to which the hygroscopic molded body is fixed is subjected to a surface enlargement treatment to increase the surface roughness of the inner surface (roughness)
By doing so, the hygroscopic molded article and the airtight container can be more strongly fixed. The surface enlargement treatment may be performed according to a known method. The surface roughness (Ra) can be appropriately determined according to the material of the hygroscopic molded article or the airtight container to be used, but is usually about 0.2 to 0.6 μm.

The method for manufacturing the organic EL device of the present invention comprises the following steps: 1)
A laminate in which at least an organic light emitting layer is sandwiched between a pair of opposing electrodes; 2) an airtight container for storing the laminate and shutting off outside air; and 3) separating the laminate from the laminate in the airtight container. A method of manufacturing an organic EL device having a drying means arranged in a manner comprising a step of fixing a hygroscopic molded body as a drying means to at least a part of the airtight container.

In the production method of the present invention, a known method for producing an organic EL element or operating conditions is employed as it is, except that a step of fixing a hygroscopic molded body as a drying means to at least a part of the hermetic container is included. be able to.

In the production method of the present invention, a first step of producing a hygroscopic molded article containing a hygroscopic agent and a resin component, and a second step of fixing the hygroscopic molded article to at least a part of the hermetic container as a drying means It is preferable to have a step.

In this case, in the first step, it is desirable to produce a hygroscopic molded article by molding a mixture comprising a hygroscopic agent and a resin component. That is, by producing a molded article that does not contain a third component such as a solvent, it is possible to avoid a problem due to the volatilization of the solvent remaining in the molded article over time.
The proportions of the moisture absorbent and the resin component may be the same as described above.

The method of fixing the hygroscopic molded article can be carried out in the same manner as described above. The fixing position is not particularly limited as long as it is a position where moisture in the airtight container can be removed. For example, when the hygroscopic molded article is in the form of a sheet, as shown in FIG. 1, the sheet (8) is installed on a part (or the whole) of the inner wall surface in the airtight container, separated from the laminate (6). good. In other words, the sheet may be fixed so as not to directly contact the laminate (6). By fixing in this state, moisture can be removed, and the occurrence of a non-light-emitting portion (so-called black spot) is suppressed or prevented, so that a display with high display quality can be provided.

[0042]

According to the present invention, since a hygroscopic molded article is particularly employed as the drying means, the drying means can be more easily and reliably applied to the organic EL device.

Thus, the installation of the drying means can be mechanized. Accordingly, the chance of moisture entering the atmosphere is reduced, and an atmosphere having a high dry state from the beginning can be created. That is, organic EL in a highly dry state
Since the element can be manufactured and water can be reliably removed even after the manufacture, it is possible to provide a more reliable organic EL element on an industrial scale.

Also, unlike the case where a conventional drying agent (powder) is used as it is as a drying means, the problem that the powder falls off and is scattered in the airtight container can be avoided. Furthermore, when powder is used, it is necessary to secure a storage portion. However, in the present invention, such a need is not particularly made, and it is possible to contribute to miniaturization and weight reduction of the device.

When a hygroscopic molded product obtained by molding a mixture comprising a hygroscopic agent and a resin component is used as the drying means, it is possible to more reliably prevent the performance of the organic EL element from deteriorating. That is, since the third component such as the solvent does not remain in the hygroscopic molded article, the adverse effects of these third components can be avoided.

In the production method of the present invention, since a pre-produced hygroscopic molded article is used and is fixed to at least a part of an airtight container, unlike the case of using a resin melt, it is 50 ° C. or less ( (Preferably at room temperature), which is advantageous in terms of cost. Further, there is no need to consider heat resistance of the airtight container, and airtight containers made of various kinds of materials can be used.

The organic EL device of the present invention having such features is useful for flat panel displays such as portable telephones, audio equipment, measuring instruments, etc., and also for uses such as computer displays and television displays.

[0048]

The following examples are provided to further clarify the features of the present invention. However, the present invention is not limited to these examples.

Example 1 First, a pellet-shaped hygroscopic molded article was prepared.

The desiccant CaO was heated at 900 ° C. for 1 hour to sufficiently dehydrate it, then cooled in a limited dry atmosphere at 180 to 200 ° C., and finally cooled to room temperature. After dry mixing 65% by weight of this CaO and 35% by weight of polyethylene (molecular weight: about 100,000) as a resin component, about 23%
The mixture was heated to 0 ° C., melted and kneaded, and the kneaded material was hot-pressed into a pellet-shaped hygroscopic molded product (φ1.5 mm
× thickness 300 μm).

The pellet was placed in the cavity of the organic EL device. FIG. 2 shows a schematic view of a cross section of the organic EL element on which the hygroscopic molded body is installed. Glass base (11)
Is mounted with an organic EL display (display element) (12). The display element is housed in a metal cavity (airtight container) (13), and a pellet (14), which is a hygroscopic molded body, is heat-sealed to the bottom. The cavity (13) is sealed with a known UV epoxy sealing adhesive (15). In the cavity (16), a dry inert gas (eg, argon gas) is sealed.

Test Example 1 The organic EL device obtained in Example 1 was subjected to an accelerated moisture absorption test. In the moisture absorption acceleration test, the organic EL element was left for 500 hours in an atmosphere at a temperature of 60 ° C. and a relative humidity of 90%, and the state before and after the test was compared. The states before and after the test are shown in FIGS. 3 and 4, respectively.

An organic EL without using a hygroscopic molded product
A similar test was performed on the element (Comparative Example 1). The states before and after the test are shown in FIGS. 5 and 6, respectively.

A similar test was conducted on an organic EL device (Comparative Example 2) using a conventional method (BaO powder in the same amount as CaO used in Example 1) as a drying means. The states before and after the test are shown in FIGS. 7 and 8, respectively.

As is clear from FIGS. 5 and 6, and FIGS. 7 and 8, in Comparative Example 1, almost the entire surface was black after the test, and only the light gray portion at the center had a light emitting portion remaining. Further, in Comparative Example 2, although not as large as Comparative Example 1, noticeable black spots were observed before and after the test.

On the other hand, as shown in FIGS. 3 and 4,
In the organic EL device of the present invention, neither deterioration in luminance nor growth of dark spots was observed, and it was found that the original light emitting portion was maintained as it was and excellent moisture absorption performance was exhibited.

[Brief description of the drawings]

FIG. 1 is a schematic view (cross-sectional view) showing an example of an organic EL device of the present invention.

FIG. 2 is a schematic diagram (cross-sectional view) of the organic EL device manufactured in Example 1.

FIG. 3 is an image diagram showing a result of observing a state of the organic EL element of Example 1 before a moisture absorption promotion test.

FIG. 4 is an image diagram showing a result of observing a state of the organic EL device of Example 1 after a moisture absorption promotion test.

FIG. 5 is an image diagram showing a result of observing a state of the organic EL element of Comparative Example 1 before a moisture absorption promotion test.

FIG. 6 is an image diagram showing the result of observing the state of the organic EL device of Comparative Example 1 after the moisture absorption promotion test.

FIG. 7 is an image diagram showing a result of observing a state of the organic EL element of Comparative Example 2 before a moisture absorption promotion test.

FIG. 8 is an image diagram showing the result of observing the state of the organic EL device of Comparative Example 2 after the moisture absorption promotion test.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Ohata 4- 3146-7, Yawatabara, Yonezawa City, Yamagata Prefecture Inside Yonezawa Plant of Tohoku Pioneer Co., Ltd. (72) Inventor Yoshitaka Nonaka 4-3146, Yawatabara, Yonezawa City, Yamagata Prefecture 7 Yonezawa Plant, Tohoku Pioneer Co., Ltd. (72) Inventor Atsushi Nishino 19-9, Minamisuien-cho, Neyagawa-shi, Osaka (72) Inventor Yohei Kawaguchi 2-6-10 Koraibashi, Chuo-ku, Osaka-shi, Osaka Pref. Branch office (72) Inventor Masayuki Fujimori 270, Taga-cho, Taga-cho, Inugae-gun, Shiga Prefecture Inside the Shiga Plant, Dainic Co., Ltd. F term (reference) 3K007 AB13 AB18 BB01 BB04 BB05 CA01 CB01 DA01 DB03 EA01 EB00 FA02

Claims (8)

[Claims] 1. A laminated body having at least an organic light-emitting layer sandwiched between a pair of electrodes facing each other, 2) an airtight container for accommodating the laminated body and blocking outside air, and 3) an inside of the airtight container. An organic EL element having a drying means disposed separately from the laminate, wherein the hygroscopic molded body is fixed to at least a part of the airtight container as the drying means. Organic EL element. 2. The organic EL device according to claim 1, wherein the hygroscopic molded article contains a hygroscopic agent and a resin component. 3. The organic EL device according to claim 1, wherein the hygroscopic molded article is obtained by molding a mixture comprising a hygroscopic agent and a resin component. 4. The organic EL device according to claim 2, wherein the desiccant contains at least one of an alkaline earth metal oxide and a sulfate. 5. The organic EL device according to claim 2, wherein the resin component is at least one kind of gas-permeable resin. 6. A laminate comprising at least an organic light-emitting layer sandwiched between a pair of electrodes facing each other, 2) an airtight container for accommodating the laminate and shutting off outside air, and 3) an inside of the airtight container. A method of manufacturing an organic EL device having a drying means separated from the laminate, comprising a step of fixing a hygroscopic molded body as a drying means to at least a part of the airtight container. Of manufacturing an organic EL device. 7. A laminate comprising at least an organic light emitting layer sandwiched between a pair of electrodes facing each other, 2) an airtight container for accommodating the laminate and shutting off outside air, and 3) an inside of the airtight container. A method of manufacturing an organic EL device having a drying means separately disposed from the laminate, wherein the first step of manufacturing a hygroscopic molded article containing a hygroscopic agent and a resin component, and using the hygroscopic molded body as a drying means A method for manufacturing an organic EL device, comprising a second step of fixing the organic EL device to at least a part of the airtight container. 8. The production method according to claim 7, wherein the first step is a step of producing a hygroscopic molded article by molding a mixture comprising a hygroscopic agent and a resin component.