JP3535659B2 - Manufacturing method of organic EL device - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing an organic EL device.

[0002]

2. Description of the Related Art An organic EL device has a structure in which an organic light emitting body is sandwiched between a pair of electrodes facing each other. Holes are injected from an anode and electrons are injected from a cathode. The holes and electrons are recombined in the organic material layer to emit light. As such an organic EL device, a device having a single organic material layer, a device having a multilayer structure having a hole injection layer or an electron injection layer, and the like are known.

As a manufacturing method of these, as shown in FIG. 4, copper phthalocyanine is used as a hole injection layer and 1, 1 is used as a hole transport layer on a glass substrate a on which a transparent electrode b such as ITO is vapor-deposited. -Bis (4-di-p-tolylaminophenyl) -cyclohexane, an organic material layer c containing aluminum trisoxine, etc. as an electron injecting and transporting layer is formed by vapor deposition, and a Mg-Ag alloy is vapor-deposited as a cathode d thereon. SiO2 layer e formed by the purpose of acid resistance and waterproofing
A method of covering the entire surface by vapor deposition has been adopted (for example, JP-A-63-295695).

Further, as disclosed in JP-A-4-2096, a hole injecting and transporting layer and a light emitting layer are sequentially formed on an ITO glass by a spin coating method, and metallic Mg is used as a cathode on the film. The method of vapor deposition was adopted.

[0005]

However, in the first manufacturing method, since the multilayer structure must be sequentially formed by vacuum vapor deposition, there are problems that productivity is low and manufacturing cost is high. Further, also in the second manufacturing method, it is difficult to adhere a metal plate in terms of accuracy and adhesiveness when forming a metal Mg as a cathode after forming a film by a spin coating method. However, it has to be formed by vacuum vapor deposition, and as in the above case, the productivity is poor and the manufacturing cost is high.

[0006]

In order to solve the above problems, in the present invention, a cathode to be formed on a substrate is superposed by a wet method with a metal having a large work function and a metal having a small work function. In order to obtain both the necessity for electron injection and the low resistance and state stabilization of the above metal. Further, particles of an alkaline earth metal or a metal boride are used as a metal having a small work function, and an organic material layer is formed on the unevenness of the particles to increase the contact interface area of the organic material layer, which is advantageous for light emission. There is. On the organic layer formed on the unevenness of the particles, by forming an anode with a conductive adhesive having conductive particles having a smaller particle size than the particles,
The conductive particles easily enter the irregularities of the organic material layer, and no inconvenience occurs in charge transport. Further, the transparent substrate is adhered by the conductive adhesive of the anode, and the element is sealed at the same time as the transparent substrate is adhered, which makes the manufacturing process advantageous and extends the life.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a method for manufacturing an organic EL device which has an organic material layer between an anode and a cathode, and emits light by applying a direct current to the organic material layer. A metal layer having a large work function and a metal layer having a small work function formed thereon by a wet method to form a cathode, an organic material layer is formed on the cathode, and a transparent conductive film is formed on the organic material layer by a wet method. A positive electrode made of a conductive adhesive is formed, and a transparent substrate is bonded onto the anode made of the transparent conductive adhesive. In the above-mentioned cathode, it is preferable that a metal layer having a large work function is formed on the surface of the substrate by a plating method, and a metal having a small work function is formed thereon by a wet method.

The cathode may be formed by forming a conductive adhesive containing a metal having a large work function on the surface of the substrate by a wet method, and then forming a metal having a small work function on the surface by a wet method. Further, it is preferable that the metal particles having a small work function have a larger particle diameter than the conductive particles contained in the transparent conductive adhesive of the anode. Further, the transparent conductive adhesive also serves as a sealing layer for the element.

As described above, the cathode is formed on the substrate by the wet method, which is industrially advantageous. Since particles of alkaline earth metal or metal boride are used as a metal having a small work function and an organic material layer is formed on the irregularities of the particles, a large contact interface area of the organic material layer is provided, which is advantageous for light emission. . On the organic layer formed on the unevenness of the particles, since the anode is formed by a conductive adhesive having conductive particles having a particle size smaller than this particle, conductive particles easily enter the unevenness of the organic layer, charge There is no inconvenience in transportation. Further, since the transparent substrate is adhered by the conductive adhesive of the anode, the element can be sealed at the same time as the transparent substrate is adhered, so that the manufacturing process becomes advantageous and the life is improved.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the preferred embodiments shown in the drawings. FIG. 1 is a cross-sectional view schematically showing the organic EL element in the present embodiment, in which a metal layer 2-1 having a large work function by plating Ag of about 1 μm on a substrate 1 made of glass or a synthetic resin such as an epoxy resin. Then, Mg particles having a particle size of 10 to 100 μm, which is a metal having a small work function, toluene and a binder are mixed in a weight ratio of 10:10:
The mixture of 1 is applied on the Ag-plated metal layer 2-1 and cured at room temperature or under heating to form the metal layer 2-2.
Was formed. The cathode 2 was formed by the metal layer 2-1 and the metal layer 2-2. An ethanol solution of polyvinylcarbazole having a concentration of about 1% by weight was applied by a spin coating method so as to cover the cathode 2, and ethanol was dried to form an organic material layer 3. Polyvinylcarbazole used as the organic material layer 3 is an electron-donating organic compound having a hole-transporting ability like triphenylamines. Further, a conductive adhesive containing conductive particles 4a such as ITO is applied by printing so as to cover the organic material layer 3 to form the anode 4, and the glass transparent substrate 5 is pressure-contacted to the anode 4 before the conductive adhesive is cured. Adhesion was achieved by curing the adhesive. By pressing the transparent substrate 5 under pressure, the adhesive is extruded and the side surface of the element is sealed. In this way organic EL
The manufacturing of the device has been completed.

Generally, the cathode 2 needs a metal having a small work function in order to inject electrons into the organic layer 3. Therefore, conventionally, an alkaline earth metal such as Mg is used, and further, Ag or the like having a large work function is mixed and used for lowering resistance and stabilizing the state of the alkaline earth metal. Therefore, in general, the interface with the organic matter is rich in Mg (for example, Mg: Ag).
= Atomic ratio is 10: 1).

However, in the present invention, as shown in an enlarged scale in FIG. 2, a grain size of 10 is formed on the Ag-plated metal layer 2-1.
A metal layer 2-2 of Mg particles of ˜100 μm is formed, and a thin organic material layer 3 of 0.1 μm or less surrounds the upper and lower sides of the unevenness of the Mg particles along the particle shape. Therefore, the contact interface area required for charge transport can be increased. The conductive adhesive containing ITO (anode 4) applied to the upper side of the unevenness of the organic material layer 3 contains the ITO particles 4
Since the diameter of a is as small as 1 to 10 μm, it easily enters into the concave portion of the organic material layer 3 and causes no problem in charge transport between the anode 4 and the organic material layer 3. In order to flatten the cathode 2 as in the prior art, the Mg particles have to be made into fine particles having a diameter of 1 to 10 μm or less, which is expensive. Is 10 to 100 μm, and it is not necessary to use fine particles. Therefore, not only can the cost be reduced, but as described above, the contact interface area becomes large, which is more advantageous. Although the dimensions of each member are not accurate in the drawings, the ratio of the dimensions is shown differently for easy understanding.

The organic EL device thus manufactured is
By applying a direct current to the organic material layer 3, 15
The emission brightness at 700 V was 700 cd / m ² . This emission brightness is equivalent to that of an organic EL device in which a polyvinylcarbazole layer is formed on the anode and a cathode is formed by vacuum vapor deposition by the conventional manufacturing method, and sufficient performance is obtained by the manufacturing method of the present invention. It has been found that an organic EL device having the same can be manufactured.

The metal having a low work function constituting the cathode 2 is not limited to the above Mg, but other alkaline earth metal or metal boride particles can be used.

FIG. 3 shows another embodiment in which a conductive adhesive containing Ag is used in place of the Ag plating described above, and the conductive adhesive is applied onto the substrate 1 by printing. The metal layer 2-3 was formed, and the same metal layer 2-2 as in the first embodiment was formed on the metal layer 2-3. This metal layer 2-3,2-
2, the cathode 20 is formed. Note that the substantially same parts as those in FIG. 2 are designated by the same reference numerals. With this configuration, the same emission brightness as in the case of FIG. 2 can be obtained.

[0016]

Since the cathode is formed by the wet method, it is easier to manufacture than the dry method such as the vacuum deposition method, and the productivity can be improved, the initial yield can be increased, and the cost can be reduced. it can. Since the metal layer having a large work function and the metal layer having a small work function are formed as the cathode in an overlapping manner, both the necessity for electron injection, the low resistance of the metal, and the state stabilization can be obtained. And the organic EL element manufactured by this manufacturing method can obtain sufficient light emission brightness.

The diameter of metal particles having a small work function is
When the diameter of the conductive particles contained in the transparent conductive adhesive of the anode is reduced, the organic layer on the cathode is surrounded along the particle shape, and the contact interface area required for charge transport can be increased. In addition, the conductive particles easily enter the recesses of the organic material layer, and no problem occurs in the charge transport between the anode and the organic material layer.

When the transparent substrate is laminated and pressure-contacted before the conductive adhesive as the anode is cured, the adhesive protruding causes
Since the side surface of the element is sealed, the number of steps is small and it is effective in improving the life of the element.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an organic EL device manufactured by a manufacturing method of the present invention.

FIG. 2 is a cross-sectional view showing an enlarged part of the organic EL element of FIG.

FIG. 3 is a cross-sectional view showing an enlarged part of an organic EL element in another example.

FIG. 4 is a cross-sectional view of an organic EL element for explaining a conventional manufacturing method.

[Explanation of symbols]

1 substrate 2,20 cathode 2-1 Metal layer with large work function 2-2 Metal layer with low work function 2-3 Metal layer with high work function (conductive adhesive) 3 Organic matter layer 4 Anode (transparent conductive adhesive) 5 transparent substrate

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A 8-124679 (JP, A) JP-A 4-363896 (JP, A) JP-A 3-141588 (JP, A) JP-A 4- 320486 (JP, A) JP 5-251186 (JP, A) JP 7-263145 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H05B 33/00-33 / 28

Claims (5)

(57) [Claims] 1. A method of manufacturing an organic EL device, which comprises an organic material layer between an anode and a cathode, and emits light by applying a direct current to the organic material layer, which comprises a work function formed on a substrate surface. A cathode is formed by a large metal layer and a metal layer having a low work function formed thereon by a wet method, an organic material layer is formed on the cathode, and a transparent conductive adhesive is formed on the organic material layer by a wet method. A method for producing an organic EL device, which comprises forming an anode and adhering a transparent substrate on the anode made of the transparent conductive adhesive. 2. The cathode according to claim 1, wherein a metal layer having a large work function is formed on the substrate surface by a plating method,
A method for manufacturing an organic EL device, characterized in that a metal layer having a small work function is formed thereon by a wet method. 3. The cathode according to claim 1, wherein a conductive adhesive containing a metal having a large work function is formed on the surface of the substrate by a wet method, and a metal layer having a small work function is formed thereon by a wet method. A method for manufacturing an organic EL device, comprising: 4. The particle according to claim 1, wherein the metal particle having a small work function has a particle diameter larger than that of the conductive particle contained in the transparent conductive adhesive of the anode. Method for manufacturing organic EL device. 5. The method for manufacturing an organic EL device according to claim 1, wherein the transparent conductive adhesive also serves as a sealing layer for the device.