JP2002260847A - Electroluminescence element sealing film and sealed organic electroluminescence element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing film that seals an organic EL element and cuts it out from water or oxygen and enables stable driving for a long period. SOLUTION: The organic EL element sealing film 11 has a vapor deposition membrane 13 of silicon oxide or aluminum on the surface of a gas barrier resin film 12 and is laminated with a moisture absorption resin film 14 having dispersed moisture absorbent on its rear surface, and an adhesive layer 15 is provided on the surface of this moisture absorption resin film. It is possible that a second gas barrier resin film is laminated on the surface of the above moisture absorption resin film and an adhesive layer is provided on the surface of this second gas barrier resin film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing film which enables an organic electroluminescence element to be stable for a long period of time by shielding the element from moisture and oxygen, and an organic electroluminescence element contained in such a film. And a sealed organic electroluminescent device obtained by sealing and bonding the same.

[0002]

2. Description of the Related Art Organic electroluminescent elements (hereinafter, referred to as organic EL elements) have a low-voltage DC drive, high efficiency, and high brightness, and can be made thin. Practical use of the device has been promoted.

In this organic EL device, as shown in FIG. 1, typically, a transparent substrate 1, for example, a glass substrate is laminated with an anode 2 composed of a transparent electrode, and an organic hole is formed on the anode. A transport layer 3, an organic light emitting layer 4, and a cathode 5 composed of a metal electrode are laminated in this order, and the anode and the cathode are connected to an external power source 6. In some cases, an organic electron transport layer (not shown) may be laminated between the organic light emitting layer and the cathode.

In such an organic EL device, the organic hole transport layer is in close contact with the anode, transports holes from the anode to the organic light emitting layer, and blocks electrons.
On the other hand, the organic electron transporting layer is in close contact with the cathode and transports electrons from the cathode to the organic light emitting layer, where the electrons injected from the cathode and the holes injected from the anode into the organic light emitting layer. When light is recombined, light emission occurs, which is emitted outside through the transparent electrode (anode) and the transparent substrate. On the other hand, the cathode usually has a small work function (4e
V or less) It is made of an opaque metal. Thus, according to such an organic EL element, light emission in the organic light emitting layer can be extracted from the transparent electrode (anode) side to the outside as described above.

According to such an organic EL device, the fluorescent organic substance forming the organic light emitting layer has low mechanical strength, is sensitive to heat, an organic solvent, moisture, oxygen, etc. When the organic EL element is operated in the inside, the organic substance is deteriorated in a short time, the light emission luminance is reduced, and in some cases, the element is destroyed. Further, the metal forming the cathode is also oxidized by moisture, and peels off at the interface with the organic layer or forms an oxide. As a result, the conductivity decreases, and the light emission luminance of the element decreases.

Therefore, conventionally, in order to cope with the above-described problem by shielding the organic EL element from moisture and oxygen,
The organic EL element is covered with a metal tube to seal the element, or is bonded to a resin film to seal the element. However, the metal tube is sealed from moisture and oxygen. Is excellent, but it is bulky, so that the inherent advantage of the organic EL element, which can be made thin, cannot be utilized. Furthermore, metal tubes are inconvenient to handle, and organic E
The number of steps for manufacturing the L element is increased, which also increases the manufacturing cost.

On the other hand, according to sealing with a resin film,
Although it is simple and can solve the problem of bulkiness when using the above metal tube, on the other hand, the effect of shutting off moisture and oxygen is insufficient, for example, if operated continuously for 7 days, There is a case where the light emission luminance is greatly reduced and cannot be put to practical use.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the conventional organic EL device, and is intended to replace the conventional metal tube or resin film with the organic EL device. It is an object of the present invention to provide a film for sealing for preventing a moisture or oxygen and enabling a stable operation for a long time, that is, a film for sealing an organic EL element. Further, the present invention relates to a method for sealing and bonding an organic EL element in such a film.
It relates to the L element.

[0009]

The sealing film for an organic EL device according to the present invention has a vapor-deposited film of silicon oxide or aluminum on the surface of a gas barrier resin film and a moisture absorbent dispersed on the back surface. A hygroscopic resin film is laminated, and an adhesive layer is provided on the surface of the hygroscopic resin film. According to the sealing film for an organic EL element of the present invention, it is possible to effectively prevent the light emitting layer and the cathode of the organic EL element from deteriorating.

According to the present invention, a second gas barrier resin film may be laminated on the surface of the hygroscopic resin film, and an adhesive layer may be provided on the surface of the second gas barrier resin film. .

[0011]

FIG. 2 shows a basic embodiment of an organic EL element sealing film 11 according to the present invention. That is,
The organic EL device sealing film 11 according to the present invention has a vapor-deposited film 13 of silicon oxide or aluminum on the surface of a gas barrier resin film 12 and a hygroscopic resin film 14 in which a hygroscopic agent is dispersed on the back surface. The adhesive layer 15 is provided on the surface of the hygroscopic resin film.

The above-mentioned gas barrier resin film refers to a resin film having an excellent barrier property against water vapor (moisture) and oxygen. Therefore, as the gas barrier resin film, for example, a film made of polyethylene terephthalate, polyethylene naphthylate, polyethylene, polypropylene, polystyrene, etc. is used,
Preferably, a polyethylene terephthalate film is used. The gas barrier resin film is usually 5 to 5
It has a thickness in the range of 00 μm, preferably 10-100 μm.

According to the present invention, the gas barrier resin film has a silicon oxide or aluminum vapor-deposited film on its surface, and the gas-barrier resin film is exposed to water vapor and oxygen by these vapor-deposited films. Has even higher barrier properties. These deposited films can be formed by using a vacuum thin film forming technique such as vacuum deposition, ion plating, and sputtering. Further, the thickness of these deposited films is usually in the range of 5 nm to 100 μm, preferably in the range of 10 nm to 10 μm.

According to the present invention, the gas barrier resin film has a back surface laminated with a moisture absorbing film in which a moisture absorbing agent is dispersed. As the above-mentioned moisture absorbing agent, for example, alkaline earth metal oxides such as calcium oxide and barium oxide are preferable, but silica gel, alumina and the like are also used. Although not particularly limited, the resin film usually contains such a moisture absorbent in the range of 10 to 40% by weight.

On the other hand, as the hygroscopic resin film, for example, a film made of polyamide, polyvinyl alcohol, ethylene-vinyl alcohol copolymer resin, vinyl alcohol-acrylate copolymer, or the like is used. In addition, a vinyl chloride resin film is used if necessary. However, according to the invention, in particular, ethylene-
A vinyl alcohol copolymer resin film is preferably used. Such a hygroscopic film is usually 10 to 5
It has a thickness in the range of 00 μm, preferably in the range of 50-250 μm.

The film for sealing an organic EL element according to the present invention has an adhesive layer on the surface of such a hygroscopic resin film. As the adhesive, although not particularly limited, for example, a urethane adhesive, an epoxy adhesive, an acrylic adhesive, and a cyanoacrylate adhesive are used. These adhesives may be water-based, solvent-based, or non-solvent-based, and may be thermosetting or photocurable. For example, a photo-curable resin adhesive is an example of an adhesive that is preferably used in the present invention because it does not require heating when sealing and bonding an organic EL element in a film. Such a photocurable resin adhesive, for example,
As the photocurable epoxy-based adhesive and the like, commercially available products are used as they are.

FIG. 3 shows a second embodiment of the film 11 for sealing an organic EL element according to the present invention. That is, the film 11 for sealing an organic EL element according to the present invention comprises a gas-barrier resin film 12 having a silicon oxide or aluminum vapor-deposited film 13 on the surface thereof, And a second gas barrier resin film 1 on the surface of the hygroscopic resin film.
6 and an adhesive layer 15 on the surface of the second gas barrier resin film.

That is, in the second embodiment, the first
The second gas barrier resin film differs from the second embodiment only in that a second gas barrier resin film 16 is laminated between the hygroscopic resin film 14 and the adhesive layer 15. May be the same as the first gas barrier resin film.

The organic EL device which can be sealed using the film according to the present invention has, in its structure,
It is not limited. Therefore, typically, first,
As described with reference to FIG. 1, but
The present invention is not at all limited by the configuration of the organic EL element. Thus, for example, the cathode may be transparent.

FIG. 4 shows the sealing film 23 as described above.
The sealing organic EL element formed by sealing and bonding the organic EL element 22 on the substrate 21 by using FIG.

To explain a typical organic EL device, a glass substrate is usually used as a transparent substrate.
As the anode, for example, indium tin oxide (ITO)
And a transparent electrode made of indium oxide, tin oxide, or the like. The thickness of the anode is usually in the range of 0.01 to 1 μm, preferably in the range of 0.01 to 0.5 μm. Further, for example, 4,4′-bis (N, N
-Phenyl-m-tolylamino) diphenylamine (T
PD) and 4,4 ', 4 "-tris (N, N-phenyl-m-tolylamino) triphenylamine (MTDATA) are used, and their film thickness is usually in the range of 1 nm to 1 μm. For example, tris (8-quinolinol) aluminum (Alq ₃ ) is used for the layer, and its film thickness is usually in the range of 1 nm to 1 μm.
When the device includes an electron transport layer, the film thickness is usually 1
The thickness is in the range of 1 nm to 1 μm, and when the conductive polymer layer is included, the thickness thereof is usually in the range of 1 to 100 nm.

For the cathode, a metal having a small work function (4 eV or less), for example, magnesium, calcium, potassium, sodium, lithium or the like is preferably used. Further, such a metal having a small work function and a metal having a large work function (exceeding 4 eV), for example, aluminum,
A mixture or alloy with silver or the like is also used.

[0023]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited by these examples.

Example 1 A 200 μm thick vinyl chloride resin film in which 20% by weight of barium oxide was dispersed as a hygroscopic agent
A laminated film was formed by laminating a 5 μm polyethylene terephthalate film. After performing a primer treatment on the surface of the polyethylene terephthalate film of the laminated film, aluminum is vacuum-deposited to a thickness of 50 nm, and on the other hand, a photocurable epoxy-based adhesive layer is provided on the back surface of the vinyl chloride resin film. To obtain a film for sealing an organic EL device.

An MTDATA layer having a thickness of 50 nm and a TP having a thickness of 10 nm are formed on an indium tin oxide (ITO) transparent electrode.
The D layer is laminated in this order by vacuum evaporation to form a hole transport layer. On this hole transport layer, a light emitting layer (Alq ₃ layer,
(Film thickness: 50 nm) was vacuum-deposited and laminated, and a magnesium-silver alloy (film thickness: 200 nm) was further vacuum-deposited on the light emitting layer to form an organic EL device. As shown in FIG. 4, the organic EL element was sealed and adhered to the substrate so as to be fixed on the substrate.

Under the conditions of room temperature (25 ° C.) and a relative humidity of 70%, a voltage is applied to the organic EL element thus sealed on the substrate with the sealing film so that the initial luminance becomes 300 cd / m ^2. It was turned on and its luminance was examined over time.
Table 1 shows the results.

Example 2 A 20 μm thick polyethylene terephthalate film was laminated on the front and back surfaces of a 200 μm thick ethylene-vinyl alcohol copolymer resin film in which 20% by weight of barium oxide was dispersed as a moisture absorbent. did. After performing a primer treatment on the surface of one polyethylene terephthalate film of the laminated film, aluminum is vacuum-deposited to a thickness of 50 nm,
A photocurable epoxy-based adhesive layer was provided on the surface of the other polyethylene terephthalate film to obtain an organic EL device sealing film according to the present invention.

Using this film, the same organic EL device as in Example 1 was sealed and adhered to a substrate in the same manner as in Example 1. As described above, the organic EL element sealed on the substrate with the sealing film was operated by applying a voltage so that the initial luminance became 300 cd / m ^2, and the change with time of the luminance was examined. Table 1 shows the results.

Example 3 As a hygroscopic agent, a 20 μm-thick polyethylene terephthalate film was laminated on both sides of a 200 μm-thick polyvinyl alcohol resin film in which 20% by weight of barium oxide was dispersed to form a laminated film.
After a primer treatment is performed on one polyethylene terephthalate film surface of this laminated film,
Vacuum evaporation was performed to a thickness of 0 nm, and a photocurable epoxy adhesive layer was provided on the surface of the other polyethylene terephthalate film to obtain an organic EL device sealing film according to the present invention.

Using the above-mentioned film, the same organic EL device as in Example 1 was sealed and bonded so as to be fixed on a substrate in the same manner as in Example 1. Thus, the organic EL device sealed with the sealing film was operated by applying a voltage so that the initial brightness became 300 cd / m ^2, and the change over time in the brightness of the device was examined. Table 1 shows the results.

COMPARATIVE EXAMPLE 1 The same organic EL device as in Example 1 was exposed to the air as it was, and was sealed in a sealing film and operated in the same manner as in Example 1 without being adhered. The changes were examined. Table 1 shows the results.

Comparative Example 2 A metal tube having a height of 10 mm having an opening and a bottom was filled with barium oxide, and absorbent cotton was filled as a gas-permeable filling material on the bottom to obtain a metal tube for sealing. The same organic EL element as in Example 1 was placed on a substrate, and the sealing metal tube was covered so as to cover the organic EL element. Then, the metal tube was bonded and fixed to the substrate with an epoxy resin adhesive. , Organic EL
The device was sealed in a metal tube.

In the same manner as in Example 1, the organic EL device sealed in a metal tube on the substrate had an initial luminance of 300 cd / m ^2.
The device was operated by applying a voltage so as to obtain a change in luminance over time. Table 1 shows the results.

Comparative Example 3 A 200 μm thick ethylene-vinyl alcohol copolymer resin film containing no barium oxide was coated on the front and back surfaces with a thickness of 2 μm.
Each of the 0 μm polyethylene terephthalate films was laminated to form a laminated film. After performing a primer treatment on the surface of one polyethylene terephthalate film of the laminated film, 50
The film was vacuum-deposited to a thickness of nm, and a photocurable epoxy-based adhesive layer was provided on the surface of the other polyethylene terephthalate film to obtain a film for sealing an organic EL device.

Using this film, the same organic EL device as in Example 1 was sealed and adhered to a substrate in the same manner as in Example 1. In the same manner as in Example 1, the organic EL element sealed on the substrate with the sealing film has an initial luminance of 300.
The device was operated by applying a voltage so as to attain cd / m ^2, and the change over time in the luminance was examined. Table 1 shows the results.

[0036]

[Table 1]

[0037]

As described above, the sealing film for an organic EL device according to the present invention has an excellent barrier property against moisture and oxygen. By sealing and adhering the organic EL device into the film, the sealing film is long. It can be operated stably over a period. Moreover, it is easier to handle and less bulky than a conventional metal tube.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a normal organic electroluminescence element.

FIG. 2 is a cross-sectional view of an essential part showing one embodiment of the film for sealing an organic EL element according to the present invention.

FIG. 3 is a sectional view of a main part showing another embodiment of the film for sealing an organic EL element according to the present invention.

FIG. 4 is a sectional view of a main part showing a sealed organic EL device according to the present invention.

[Description of Signs] 1 ... Transparent substrate 2 ... Transparent electrode (anode) 3 ... Organic hole transport layer 4 ... Organic light emitting layer 5 ... Metal electrode (cathode) 6 ... Power supply 7 ... Ultra thin metal film 8 ... Transparent electrode 11 ... Organic EL element sealing film 12 ... (first) gas barrier resin film 13 ... vapor-deposited film of silicon oxide or aluminum 14 ... hygroscopic resin film 15 ... adhesive layer 16 ... second gas barrier resin film 21 ... substrate 22: Organic EL element 23: Sealing film

Claims (13)

[Claims] 1. A gas barrier resin film having a silicon oxide or aluminum vapor deposited film on its surface,
A sealing film for organic electroluminescence, characterized in that a hygroscopic resin film in which a hygroscopic agent is dispersed is laminated on the back surface, and an adhesive layer is provided on the surface of the hygroscopic resin film. 2. The film for sealing organic electroluminescence according to claim 1, wherein the gas barrier resin film comprises a polyethylene terephthalate film. 3. The sealing film for organic electroluminescence according to claim 1, wherein the hygroscopic resin film comprises an ethylene-vinyl alcohol copolymer resin film. 4. The sealing film for organic electroluminescence according to claim 1, wherein the hygroscopic agent is an alkaline earth metal oxide. 5. The film for sealing organic electroluminescence according to claim 1, wherein the desiccant is silica gel or alumina. 6. The sealing film for organic electroluminescence according to claim 1, wherein the adhesive is a photocurable resin adhesive. 7. A first gas barrier resin film having a silicon oxide or aluminum vapor deposited film on the surface thereof and a hygroscopic resin film having a hygroscopic agent dispersed on the back surface thereof. A sealing film for organic electroluminescence, wherein a second gas barrier resin film is laminated on the surface, and an adhesive layer is further provided on the surface of the second gas barrier resin film. 8. The film for sealing organic electroluminescence according to claim 7, wherein the first and / or second gas barrier resin film comprises a polyethylene terephthalate film. 9. The sealing film for organic electroluminescence according to claim 7, wherein the hygroscopic resin film comprises an ethylene-vinyl alcohol copolymer resin film. 10. The sealing film for organic electroluminescence according to claim 7, wherein the hygroscopic agent is an alkaline earth metal oxide. 11. The sealing film for organic electroluminescence according to claim 7, wherein the hygroscopic agent is silica gel or alumina. 12. The film for sealing organic electroluminescence according to claim 7, wherein the adhesive is a photocurable resin adhesive. 13. A sealed organic electroluminescent device comprising a film according to any one of claims 1 to 12, wherein the organic electroluminescent device is sealed and adhered on a substrate.