KR100543131B1 - Thin film for encapsulating organic electroluminescence display - Google Patents

Abstract

The present invention relates to an adhesive film for encapsulation of an organic electroluminescent device and a sealing method using the same. The adhesive film may include a polymer adhesive layer 32 having a low melting point; A polymer insulating layer 34 for preventing an electrical short between the electrode of the device and the metal film at the time of fusion; And a metal film 36. The adhesive film of the present invention can realize the encapsulation of the electroluminescent device simply by being adhered on the substrate of the device. The encapsulation process using the adhesive film of the present invention can simplify the process and improve productivity compared to the encapsulation process using a conventional metal can or glass plate.

Sealing method, adhesive film, metal film, polymer

Description

Thin film for encapsulation of organic electroluminescent device {THIN FILM FOR ENCAPSULATING ORGANIC ELECTROLUMINESCENCE DISPLAY}

1 is a view schematically showing the structure of an electroluminescent device encapsulated by a conventional encapsulation process.

Figure 2 is a view showing a cross section of the adhesive film for sealing of the electroluminescent device of the present invention.

3 is a view schematically showing the structure of an electroluminescent device encapsulated with an adhesive film of the present invention.

4 is a view showing the initial light emission characteristics of the electroluminescent device encapsulated according to the embodiment and the comparative example of the present invention.

5 is a view showing the initial reaction current characteristics of the electroluminescent device encapsulated according to the embodiment and the comparative example of the present invention.

6 is a view showing a change in light emission characteristics and lifespan according to elapsed time of an electroluminescent device encapsulated according to an embodiment and a comparative example of the present invention.

<Explanation of symbols for the main parts of the drawings>

20: substrate 22: anode

23: hole transport layer 24: light emitting layer

25: electron transport layer 26: cathode

30: adhesive film 32: polymer adhesive layer

34: polymer insulating layer 36: metal film

[Industrial use]

The present invention relates to an adhesive film for encapsulating an electroluminescent device and an encapsulation method using the same, and more particularly, to an adhesive film and an electroluminescent device using the same, which can simplify the encapsulation process of an electroluminescent device and improve productivity. It relates to a sealing method.

[Private Technology]

Recently, as the development of the information and communication industry is accelerated, higher performance is required in the field of display devices, which is one of the most important fields. Such displays can be divided into luminescent and non-luminescent. The light emitting display includes a cathode ray tube (CRT), an electroluminescence display (ELD), a light emitting diode (LED), and a plasma display panel (PDP). . Non-luminous displays include liquid crystal displays (LCDs).

The light emitting and non-light emitting displays have basic performances such as operating voltage, power consumption, brightness, that is, brightness, contrast, response speed, lifetime, and display color. However, among these, liquid crystal displays, which are widely used to date, have problems in response speed, contrast, and visual dependence among the above-described basic performances.

On the other hand, the electroluminescent device has a fast response speed and is self-luminous, so it does not need back light, has excellent brightness, and has various advantages. It is expected to take up.

A schematic cross section of the electroluminescent device is shown in FIG. 1. The anode 3, the hole transport layer 5, the light emitting layer 7, the electron transport layer 9, and the cathode 11 are sequentially stacked on the substrate 1. When the laminated electroluminescent device comes into contact with oxygen or moisture, black spots that cause device failure are generated. In addition, in the organic electroluminescent device, since the material forming the device is an organic material, the movement of electrons or holes that contribute to light emission is more sensitive to oxygen and moisture. Therefore, in order to continuously realize high luminance and long life electroluminescence, an encapsulation process is required to isolate the device from oxygen and moisture.

Conventionally, a multi-step encapsulation process is used in which an electroluminescent device is attached to a substrate 1 with a metal can or glass plate 15 by an extreme ultraviolet curing agent or other adhesive. EP 0776147A1 describes an encapsulation method in which a thin film for a device is formed on a substrate and then a metal can is adhered onto the device substrate with an adhesive and irradiated with extreme ultraviolet rays to cure the adhesive. However, since the encapsulation process has to be carried out in multiple stages such as application of adhesives, adhesion of metal cans, and irradiation with extreme ultraviolet rays, the encapsulation process is complicated, and the reproducibility is poor, which makes it difficult to expect high yields, which increases the manufacturing cost of the device. have.

In order to solve the above problems, an object of the present invention is to simplify the sealing process of the electroluminescent device and to provide an adhesive film that is easy to handle.

Another object of the present invention is to provide a method for encapsulating an electroluminescent device having a simple process and excellent productivity by using the adhesive film.

The present invention, in order to achieve the above object, the polymer adhesive layer 32 having a low melting point; A polymer insulating layer 34 for preventing an electrical short between the electrode of the device and the metal film during welding; And it provides an adhesive film for sealing the electroluminescent device comprising a metal film (36).

The present invention also provides a method for encapsulating an electroluminescent device comprising the step of adhering the adhesive film on an element substrate.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

A cross section of the adhesive film for encapsulation of the electroluminescent device of the present invention is shown in FIG. 2. The adhesive film of the present invention has a structure in which the polymer layers 32 and 34 are bonded to the metal film 36. The adhesive film may include an adhesive layer 32 including a polymer having a low melting point; A polymer insulating layer 34 for preventing an electrical short between the electrode of the device and the metal film at the time of fusion; And a metal film 36.

The encapsulant of the electroluminescent device should have perfect bonding with the substrate, oxygen or moisture should not penetrate the encapsulation surface, and the thermal conductivity of the encapsulation should be good because the electroluminescent device should dissipate the heat generated during light emission to prevent damage to the device. do. In addition, a short circuit between the metal-encapsulated electrode and the electrode should not occur.

The adhesive layer 32 is made of a polymer having a low melting point to be bonded to the device substrate. The adhesive layer 32 may be a polymer having a melting point of 100 to 200 ° C, preferably 100 to 150 ° C. Such polymers include olefin polymers, nitrile rubbers, conjugated diene rubbers, acrylate polymers and vinyl polymers. Preferred specific examples of these polymers include ultra low density polyethylene (LLDPE), low density polyethylene (LDPE), polyethylene (PE) such as high density polyethylene (HDPE), polyvinyl fluoride (PVF), polyvinyl chloride (PVC), polypropylene ( PP), nitrile rubber (NBR), styrene-butadiene rubber (SBR), polyalkylacrylates such as polyacrylates, polymethylacrylates, polyethylacrylates, polypropylacrylates, polymethylmethacrylates (PMMA) Polyalkyl methacrylates such as polyalkylmeth, polyacrylamide (PAM), poly (ethylene-co-vinyl acetate), ethylene-acrylic acid (EAA) copolymers, polyvinylacetate (PVA), polyvinyl ether (PVE) ), Polyvinyl butyral (PVB) and the like, but is not limited thereto.

When the adhesive film is fused, the polymer insulating layer 34 is coated on the polymer adhesive layer to prevent electrical short between the electrode of the device and the encapsulant including the metal film. As the polymer insulating layer, a polymer having excellent film processability and having a relatively high melting point is used. The polymer insulating layer may be a polymer having a melting point of 100 to 300 ℃, preferably 200 to 300 ℃. Such polymers include polyalkylene terephthalate, polyester-based polymers or derivatives thereof, and polyamide-based polymers. Preferred specific examples of these polymers include, but are not limited to, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate, nylon, and the like.

On the polymer insulating layer 34 is coated with a metal film 36 to prevent the transmission of oxygen and moisture to the sealing surface and to improve the thermal conductivity. The metal film 36 may be excellent in thermal conductivity to relieve heat generated when the electroluminescent device emits light. As the material of the metal film 36, any material capable of forming a foil can be used. As the metal material, metals such as aluminum (Al), stainless steel, copper (Cu), nickel (Ni), and the like may be used.

The same polymer insulating layer as the polymer insulating layer 34 may be further formed on the metal film 36. The polymer insulating layer formed on the metal film serves as a protective film to prevent the adhesive film from breaking.

The adhesive film 30 formed by stacking the polymer adhesive layer 32, the polymer insulating layer 34, the metal film 36, and / or the polymer insulating layer is bonded to the device substrate to manufacture an encapsulated electroluminescent device. Adhesion of the adhesive film may be made by heat treatment, laser treatment, or the use of an adhesive.

It is preferable that the said heat processing temperature is 100-200 degreeC which is the melting temperature of an adhesive film. Examples of the adhesive include epoxy, polyester and phenol thermosetting adhesives, vinyl acetate, acryl, polyamide, polyethylene, polyvinyl alcohol and vinyl chloride thermoplastic adhesives, butadiene, nitrile rubber and butyl. Rubber-based rubber adhesives can be preferably used.

The bonding process may be carried out in a vacuum or atmospheric pressure.

The electroluminescent device encapsulated in accordance with the encapsulation method of the present invention is shown in FIG. A device in which the anode 22, the hole transport layer 23, the light emitting layer 24, the electron transport layer 25, and the cathode 26 are sequentially stacked on the substrate 20 is surrounded by an adhesive film 30, and then a polymer The adhesive layer is fused to the element substrate and sealed.

The substrate may be a material such as glass, plastic, quartz, ceramic, or silicon, but is not limited thereto. Conventional materials can be used for the hole transport layer, the light emitting layer, the electron transport layer, and the cathode formed on the substrate.

The encapsulation method of the electroluminescent device of the present invention is electroluminescent by sealing a thin film-type adhesive film on the junction of the device substrate by heat treatment, laser treatment or adhesive, unlike the conventional multi-step extreme ultraviolet curing or encapsulation process using other adhesives. The device can be sealed.

 EXAMPLE

Hereinafter, a preferred embodiment of the present invention. However, the following examples are only presented to aid the understanding of the present invention, and the present invention is not limited to the following examples.

Example 1

An adhesive film 30 was prepared by laminating a poly (ethylene-co-vinyl acetate) film 32, a polyethylene terephthalate film 34, and an aluminum film 36. An ITO anode layer 22 was formed on the glass substrate, and N, N'-bis (naphthalen-1-yl) -N, N'-bis (phenyl) benzidine (NPB) was vacuum-deposited as a hole transport layer, and the light emitting layer and electrons were Tris- (8-hydroxy-quinolinolato) -aluminum (Alq3) was vacuum deposited as a transport layer, and lithium fluoride (LiF) was vacuum deposited to form a hole transport layer, a light emitting layer, and an electron transport layer. The tris- (8-hydroxy-quinolinolato) -aluminum (Alq 3) is a green luminescent (λ max = 520 nm) material. Then, an aluminum cathode was formed to manufacture an organic electroluminescent device. An encapsulated organic electroluminescent device having the structure shown in FIG. 3 was manufactured by covering the device with the adhesive film prepared above, followed by fusion bonding the device substrate and the adhesive film by heat treatment at a temperature of 150 ° C.

Comparative Example 1

An encapsulated organic electroluminescent device having the structure shown in FIG. 1 was prepared by attaching a metal can to an electroluminescent device manufactured in the same manner as Example 1 with an extreme ultraviolet curing adhesive and curing the adhesive by irradiating extreme ultraviolet rays. .

An initial emission spectrum of the organic electroluminescent device encapsulated according to Example 1 and Comparative Example 1 is shown in FIG. 4, and the reaction current characteristics according to the initial voltage are shown in FIG. 5. As shown in FIGS. 4 and 5, initial emission spectra of Example 1 and Comparative Example 1 and reaction current characteristics according to voltage were almost the same. This means that the change in device characteristics over time is determined by the encapsulation of the device.

6 shows a change in brightness (luminescence efficiency) over time when a DC current density of 25 mA / cm ² is applied to the organic electroluminescent devices manufactured according to Example 1 and Comparative Example 1. FIG. In FIG. 6, the y-axis shows the luminance B _t as a percentage when the initial luminance B _i is 100%. The luminance of Example 1 was 58.4% after 100 hours and 48.4% after 200 hours. In comparison, the luminance of Comparative Example 1 was 57.5% after 100 hours and 47.5% after 200 hours. As shown in FIG. 6, it can be seen that the organic electroluminescent device encapsulated according to Example 1 exhibits similar device life characteristics to the organic electroluminescent device encapsulated according to Comparative Example 1. From this fact, it can be seen that the electroluminescent device encapsulated according to the present invention can be encapsulated in a simpler manner than the conventional process while having the same characteristics as the encapsulated device according to the conventional method.

The present invention is to improve the productivity by encapsulating the electroluminescent device using an adhesive film coated with a polymer adhesive layer on the metal film to simplify the multi-step encapsulation process of bonding the existing glass plate and the metal can with an extreme ultraviolet curing agent or other adhesive. It is possible to easily handle the bag, thereby increasing the reproducibility, thereby improving the production efficiency.

All simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (7)

An adhesive layer comprising a polymer having a melting point of 100 to 200 ℃; A polymer insulating layer for preventing an electrical short between the electrode of the device and the metal film during welding; And metal film, The polymer used to form the polymer adhesive layer is any one selected from the group consisting of olefin-based polymers, nitrile rubbers, conjugated diene rubbers, acrylate polymers, and vinyl polymers. The polymer used to form the polymer insulating layer is an adhesive film for encapsulating an electroluminescent device, which is any one selected from the group consisting of polyalkylene terephthalate, polyester-based polymers or derivatives thereof, and polyamide-based polymers. delete The method of claim 1, wherein the polymer used to form the polymer adhesive layer is polyethylene (PE), polyvinyl fluoride (PVF), polyvinyl chloride (PVC), polypropylene (PP), nitrile rubber (NBR), styrene-butadiene Rubber (SBR), polyacrylate, polyalkylacrylate, polyalkyl methacrylate, polyacrylamide (PAM), poly (ethylene-co-vinyl acetate), ethylene-acrylic acid (EAA) copolymer, polyvinylacetate ( PVA), polyvinyl ether (PVE) and polyvinyl butyral (PVB) adhesive film for encapsulating an electroluminescent device which is any one polymer selected from the group consisting of. delete The electroluminescent device according to claim 1, wherein the polymer used to form the polymer insulating layer is any one polymer selected from the group consisting of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate and nylon. Adhesive film for encapsulation. The method of claim 1, wherein the metal used to form the metal film is an electroluminescent device for encapsulation of any one selected from the group consisting of aluminum (Al), stainless steel (stainless steel), copper (Cu) and nickel (Ni). Adhesive film. The adhesive film for encapsulating electroluminescent device according to claim 1, wherein the adhesive film for encapsulation further comprises a polymer insulating layer formed on the metal film.

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