JP2001307871A - Electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EL element which cuts off moisture from outside, restrains a deterioration of the EL element for long term, and is thin-type, light weight, and low cost. SOLUTION: The EL element coated and sealed the EL element fabricated on a transparent substrate by a moisture proof film 5 with a sealant layer constituted of a thermoplastic adhesive property resin in which a barrier layer and a melt flow rate are 5 (g/10 min) or more and 20 (g/10 min) or less at least, can bury a gap part made by a difference of a grade of a drawer electrode of respective electrodes completely, and does not deteriorate a tensile strength, anti stress cracking nature, a workability or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroluminescent element (hereinafter, referred to as an EL element) which is expected to be widely used as a display for an information display terminal or a surface emitting light source, and has excellent moisture resistance. It is characterized in that the EL element can be manufactured thinly, lightly and at low cost.

[0002]

2. Description of the Related Art EL elements are expected to be used as flat panel displays in place of cathode ray tubes and liquid crystal displays because of their advantages such as a wide viewing angle, a high response speed, and low power consumption.

An EL element has a structure in which an organic or inorganic light emitting medium layer is sandwiched between two electrodes, at least one of which is transparent.
In the case of an inorganic light emitting medium layer, light emission occurs in the light emitting medium layer by applying a DC or AC voltage (hereinafter, an example in which a DC voltage is applied to an organic light emitting medium layer will be described).

Usually, after forming a transparent anode layer and a light emitting medium layer made of ITO or the like on a light transmitting substrate, a cathode layer is formed by a vacuum evaporation method, a sputtering method or the like. This cathode layer is liable to cause local film defects such as pinholes due to the influence of foreign substances on the substrate.

When such a film defect occurs in the cathode layer, moisture in the air penetrates and the EL element is deteriorated. As a specific example, there is a phenomenon that a non-light-emitting area called a dark spot is generated and expands with time.

As means for solving this problem, Patent No. 28
No. 13495, Patent No. 2813499, JP-A-7-169567 and the like, and JP-A-6-36878, JP-A
Two examples of the method described in JP-A-6-223973 and JP-A-6-338393 are given.

In the former, an EL case is tightly fixed to a light-transmitting substrate in an atmosphere of nitrogen or an inert gas, so that an EL device is used.
This is a method for sealing the element.

However, since the airtight case is made of metal or glass, there is a problem that the airtight case occupies about 1/3 to 1/2 of the total weight of the EL element. Therefore, E
This method is not suitable for reducing the thickness and weight of the L element.

Further, since the means for adhering the airtight case to the light-transmitting substrate uses a photocurable resin, there is a problem that the element is deteriorated by outgas from the photocurable resin.

In the manufacturing process, there are a step of applying a photocurable resin to the hermetic case, a step of bonding the translucent substrate and the hermetic case, and a step of curing the photocurable resin. There is a problem in cost.

The latter method is a method in which an element is sandwiched between a pair of moisture-resistant films and sealed, and is mainly used for sealing an inorganic EL element. At least one of the moisture-resistant films needs to be translucent, and a plastic film or the like on which an inorganic thin film is laminated is used.

However, when the EL element is sealed by using this method, when the EL element is stored in a thermostat at 40 ° C. and 90% RH for 1000 hours, a non-light-emitting area called a dark spot expands, and the light-emitting area becomes 30 to 90%. There is a problem that it is reduced to 40% (initial area 100). The difference is that inorganic EL
The element has a feature that, in addition to the moisture-resistant film, the insulating layer or the phosphor as the light-emitting medium layer can be subjected to the moisture-resistant treatment.

In order to completely suppress the deterioration of the EL element, the barrier property of the current light-transmitting and moisture-resistant film is insufficient, and a glass substrate is used. However, in this case, since the thermoplastic resin used as the sealant film has no adhesiveness to glass, it is necessary to use the thermoplastic adhesive resin as the sealant.

Another problem with the sealant film is that when there is a step such as a transparent anode layer or a film electrode in the thermocompression-bonded portion, the gap between the steps cannot be completely filled, and moisture or the like passes through the gap. Penetrates and degrades the element.

[0015]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to block external moisture and maintain EL for a long period of time.
Thin, lightweight, low-cost EL that suppresses element deterioration
It is to provide an element.

[0016]

According to the present invention, in order to solve the above-mentioned problems, first, in claim 1, on a light-transmitting substrate,
At least a transparent anode layer, a light-emitting medium layer, and a cathode layer are sequentially laminated, and in an electroluminescent element sealed and covered with a moisture-resistant film, the moisture-resistant film has at least a barrier layer and a JIS K 7210 prescribed melt flow rate of 5 ( g /
And a sealant layer made of a thermoplastic adhesive resin of 10 (min) to 20 (g / 10 min). According to a second aspect, based on the premise of the first aspect, the electroluminescent element is characterized in that the barrier layer is made of a metal foil. Further, a third aspect is based on the premise of the first aspect, wherein the thermoplastic adhesive resin is made of an acid-modified product of polyethylene or polypropylene.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an example of an EL device of the present invention and a manufacturing process thereof will be described with reference to FIG.

In the present embodiment, glass is used as the light-transmitting substrate 1. However, any substrate can be used as long as it has light-transmitting properties, insulating properties, and sufficient moisture resistance. For example, a quartz substrate or a resin film can be used.

First, a transparent anode layer 2 is formed on a translucent substrate 1 by a sputtering method or the like. Next, the transparent conductive film is patterned by a photolithography method and a wet etching method to form a transparent anode layer 2 also serving as a lead electrode 2a and a cathode lead electrode 2b.

As the material of the transparent anode layer in the present invention, ITO (indium tin composite oxide), indium zinc composite oxide, zinc aluminum composite oxide and the like can be used.

Next, the light emitting medium layer 3 and the cathode layer 4 are sequentially formed. Here, the cathode layer 4 is formed so as to be connected to the cathode lead electrode 2b formed in advance.

In the case of an organic substance, the light emitting medium layer in the present invention can be formed as a single layer film containing a fluorescent substance or a multilayer film. When the organic light emitting medium layer is formed of a multilayer film, examples of the structure of the organic light emitting medium layer include a hole injection transport layer, an electron transport light emitting layer or a hole transport light emitting layer, a two-layer structure including an electron transport layer, and a hole injection transport layer. And a three-layer structure including an electron transport layer. It is also possible to form a more multilayer,
Each layer is sequentially formed on a substrate.

Examples of the hole injecting / transporting material include metal phthalocyanines such as copper phthalocyanine and tetra (t-butyl) copper phthalocyanine, and metal-free phthalocyanines;
Quinacridone compounds, 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,
1'-biphenyl-4,4'-diamine, N, N'-di (1-naphthyl) -N, N'-diphenyl-1,1'-
Select from aromatic amine-based low molecular hole injection / transport materials such as biphenyl-4,4'-diamine, high molecular hole transport materials such as polythiophene and polyaniline, polythiophene oligomer materials, and other existing hole transport materials. Can be.

Examples of light emitting materials include 9,10-diarylanthracene derivatives, pyrene, coronene, perylene, rubrene, 1,1,4,4-tetraphenylbutadiene, tris (8-quinolinolato) aluminum complex, tris (4 -Methyl-8-quinolinolate) aluminum complex, bis (8-quinolinolate) zinc complex, tris (4-methyl-5-trifluoromethyl-8-quinolinolate) aluminum complex, tris (4-methyl-
5-cyano-8-quinolinolate) aluminum complex,
Bis (2-methyl-5-trifluoromethyl-8-quinolinolate) [4- (4-cyanophenyl) phenolate] aluminum complex, bis (2-methyl-5-cyano-8-quinolinolate) [4- (4- Cyanophenyl)
Phenolate] aluminum complex, tris (8-quinolinolate) scandium complex, bis [8- (para-tosyl) aminoquinoline] zinc complex and cadmium complex,
1,2,3,4-tetraphenylcyclopentadiene,
Pentaphenylcyclopentadiene, poly-2,5-diheptyloxy-para-phenylenevinylene, coumarin-based phosphor, perylene-based phosphor, pyran-based phosphor, anthrone-based phosphor, porphyrin-based phosphor, quinacridone-based phosphor, Low-molecular materials such as N, N'-dialkyl-substituted quinacridone-based phosphors, naphthalimide-based phosphors, N, N'-diaryl-substituted pyrrolopyrrole-based phosphors, and polymers such as polyfluorene, polyparaphenylenevinylene, and polythiophene Materials and other existing light emitting materials can be used.

Examples of the organic electron transporting material include 2- (4
-Bifinylyl) -5- (4-t-butylphenyl)
-1,3,4-oxadiazole, 2,5-bis (1-
Naphthyl) -1,3,4-oxadiazole, oxadiazole derivatives synthesized by Hamada et al. (Journal of the Chemical Society of Japan, p. 1540, 1991) and bis (10-hydroxybenzo [h] quinolinolato) beryllium complex, The triazole compounds described in Kaihei 7-90260 are exemplified.

The method for forming the light-emitting medium layer depends on the material.
A vacuum evaporation method, a coating method such as spin coating, spray coating, flexo, gravure, microgravure, intaglio offset, or a printing method can be used. The thickness of the light-emitting medium layer is 1000 nm or less even when it is formed as a single layer or a stacked layer, and is preferably 50 to 1 nm.
50 nm.

As the cathode material, a substance having a high electron injection efficiency is used. Specifically, a single metal such as Mg, Al, or Yb may be used, or Li or Li oxide,
Al and Cu having high stability and conductivity are stacked and used with a compound such as LiF sandwiched by about 1 nm.

Alternatively, in order to achieve both electron injection efficiency and stability, the work functions of Li, Mg, Ca, Sr, La,
An alloy system of at least one metal such as Ce, Er, Eu, Sc, Y, and Yb and a stable metal element such as Ag, Al, and Cu is used. Specifically, MgAg, AlLi, CuL
An alloy such as i can be used.

As a method for forming the cathode, a resistance heating evaporation method, an electron beam evaporation method, a reactive evaporation method, an ion plating method, and a sputtering method can be used depending on the material. The thickness of the cathode is desirably about 10 nm to 1000 nm.

Finally, in order to block moisture from the outside and suppress deterioration of the EL element for a long period of time, the EL element is covered and sealed with a moisture resistant film 5.

The moisture-resistant film has at least a barrier layer and a sealant layer made of a thermoplastic adhesive resin having a melt flow rate specified by JIS K 7210 of 5 (g / 10 min) or more and 20 (g / 10 min) or less.

The barrier layer is a thin layer made of a material having a function of blocking moisture from the outside. As a material,
Examples thereof include a metal and a metal oxide.

The barrier layer may be formed by vapor deposition or coating on a support made of a flexible resin film such as polyethylene terephthalate or nylon. There is. Therefore, it is desirable to adopt a method using a metal foil as the barrier layer.

As the material of the metal foil, aluminum,
Metal materials such as copper and nickel, and alloy materials such as stainless steel and aluminum alloy can be used, but aluminum is preferable in view of workability and cost. The film thickness is 1
It is desirable that the thickness is about 100 μm to 100 μm, preferably about 10 μm to 50 μm. Further, a film such as polyethylene terephthalate or nylon may be laminated in advance in order to facilitate handling during manufacture.

As the thermoplastic adhesive resin, JIS K 7210
The specified melt flow rate is 5 (g / 10min) or more and 20 (g / 10mi)
n) The following, more preferably 6 (g / 10min) or more 1
Use 5 (g / 10min) or less. This is because if a resin having a melt flow rate of 5 (g / 10 min) or less is used, it is impossible to completely fill the gap 2c caused by the step between the extraction electrodes 2a and 2b of each electrode, and the resin has a flow rate of 20 (g / 10min). This is because the use of the above-mentioned resin deteriorates tensile strength, stress cracking resistance, workability, and the like.

The thermoplastic adhesive resin is not particularly limited as long as it satisfies the above-mentioned values, but it is not limited to acid-modified polyolefins such as polyethylene, polypropylene and ethylene-propylene copolymer, and ethylene-vinyl acetate. An acid-modified polymer, an ethylene / acrylic acid copolymer, an ethylene / methacrylic acid copolymer, an ionomer, or the like can be used. In particular, it is desirable to use an acid-modified product of polyethylene or polypropylene that has a small amount of outgas components that deteriorate the EL element.

The thickness of the thermoplastic adhesive resin varies depending on the level difference between the extraction electrodes 2a and 2b.
It is on the order of μm to 100 μm.

When the EL element is covered and sealed with a moisture-resistant film, a thermoplastic resin layer is disposed on the element side, and thermocompression-bonded to the light-transmitting substrate 1 at the end of the film. Alternatively, the whole may be thermocompression-bonded by passing between hot rolls.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an EL device according to the present invention and a method for manufacturing the same will be described. FIG. 1 is an explanatory cross-sectional view of an EL element.
Table 1 summarizes the comparison of the moisture resistance performance of the EL devices obtained in Examples 1 to 3 and Comparative Example.

Example 1 First, a transparent anode layer 2 was formed on a transparent substrate 1 glass by sputtering as ITO.
A film was formed (see FIG. 1A). Further, in order to improve transparency and conductivity, a heat treatment was performed in air at 230 ° C. for 1 hour to crystallize the ITO film.

Next, the transparent anode layer 2 was patterned by photolithography and wet etching to form a transparent anode layer 2 also serving as an extraction electrode 2a and a cathode extraction electrode 2b (see FIG. 1B). ).

Next, copper phthalocyanine, N, N'-di (1-naphthyl) -N, N'-diphenyl-1,1'-
Biphenyl-4,4'-diamine, tris (8-quinolinolate) aluminum complex in order, 10nm, 40nm, 50nm
The film thickness was formed by vacuum evaporation. Next, as the cathode layer 4, MgAg was formed to a thickness of 200 nm by binary co-evaporation.

Next, polyethylene terephthalate (12 μm), biaxially stretched nylon (
15 μm), an aluminum foil (20 μm), and an acid-modified product of polypropylene (Mitsui Chemical QE050) (30 μm) having a melt flow rate of 7 (g / 10 min) were sequentially laminated by dry lamination and extrusion lamination (FIG. 1 (c) to FIG. 1 (c)).
(E)).

Next, in a dry nitrogen atmosphere, the substrate on which the EL element was fabricated and the moisture-resistant film were overlaid, and thermocompression-bonded at the end of the film to cover and seal the element. The obtained EL device was
As a result of storing for 1000 hours in a thermostat at 40 ° C. and 90% RH, no enlargement of the dark spot was observed.

Example 2 An EL device manufactured in the same process as in Example 1 and a polypropylene acid-modified product used in the moisture-resistant film of Example 1 had a melt flow rate of 6.2 (g / 10
Min) is an acid-modified polyethylene (Mitsui Chemicals NF55
0), and the EL element was covered and sealed in the same steps as in Example 1. As a result of storing the obtained EL element in a thermostat at 40 ° C. and 90% RH for 1000 hours, no enlargement of a dark spot was observed.

[Comparative Example] An acid-modified polypropylene of the moisture-resistant film of Example 1 was melted at a melt flow rate of 3 (g).
/ 10min) acid-modified polypropylene (Mitsui Chemicals QF5
00), and the EL element was sealed in the same process as in Experimental Example 1. The obtained EL element was stored in a thermostat at 40 ° C. and 90% RH for 1000 hours. As a result, the dark spot was enlarged, and the area of the luminescent pixel was reduced to about 70%.

[0047]

[Table 1]

^{* 1)} PERMATRA manufactured by Modern Control (MOCON)
N W6 40 ° C 90RH% ^{* 2)} Stored in a constant temperature bath at 40 ° C 90RH% for 1000 hours, relative to the initial light emitting area of 100

[0049]

According to the first aspect of the present invention, an EL device manufactured on a transparent substrate is heated at least with a barrier layer and a melt flow rate of 5 (g / 10min) or more and 20 (g / 10min) or less. By covering and sealing with a moisture-proof film having a sealant layer made of a plastic adhesive resin, it is possible to completely fill gaps caused by steps of the extraction electrodes of each electrode, and also to obtain tensile strength and stress cracking resistance, Since the workability and the like do not decrease, moisture from the outside is blocked, and the deterioration of the EL element is suppressed for a long time.
In addition, a thin, lightweight, low-cost EL element can be provided. According to the second aspect of the present invention, since the moisture resistance is increased, it is preferable as an embodiment of the first aspect of the present invention. According to the third aspect of the present invention, since the outgas component that deteriorates the EL element is small, it is preferable as the embodiment of the first aspect of the present invention.

[0050]

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of a cross-sectional structure of an EL element of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 translucent substrate 2 transparent anode layer 2 a anode extraction electrode 2 b cathode extraction electrode 2 c step gap portion 3 light emitting medium layer 4 cathode layer 5 moisture resistant film

Continuation of the front page (72) Inventor Takao Minato 1-5-1, Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd. F term (reference) 3K007 AB11 BB00 CA01 CB01 EA01 FA02

Claims (3)

[Claims] 1. A transparent anode layer on a transparent substrate,
A light-emitting medium layer and a cathode layer are sequentially laminated, and in an electroluminescence device formed by covering and sealing with a moisture-resistant film, the moisture-resistant film has at least a barrier layer and a JI.
SK 7210 prescribed melt flow rate is 5 (g / 10min) or more 20
(g / 10min) An electroluminescent device comprising a sealant layer made of the following thermoplastic adhesive resin. 2. The electroluminescent device according to claim 1, wherein the barrier layer is made of a metal foil. 3. The method according to claim 1, wherein the sealant layer is made of an acid-modified polyethylene or polypropylene.
The electroluminescent device according to the above.