JP2008235196A - Manufacturing method for organic el device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method capable of enhancing the reliability and stability as a product of an organic EL device provided with a protection film. <P>SOLUTION: In this manufacturing method for the organic EL device, the protection film is formed to coat an organic EL element by applying and curing a moisture-curable substance on a surface of the organic EL element, after layering the first electrode, a light emitting layer and the second electrode in this order, on a substrate, to form the organic EL element. A voltage is impressed between the first electrode and the second electrode, after forming the organic EL element and before curing the moisture-curable substance, and the organic EL element is exposed thereafter under an environment of high temperature and high humidity, followed to be aged, and the moisture-curable substance is cured therein, in the manufacturing method. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an organic EL (electroluminescence) device.

  The organic EL device has a structure in which an organic EL element is formed by sequentially stacking a first electrode, a light emitting layer, and a second electrode on a substrate. In such an organic EL device, in order to ensure reliability and stability as a product, a voltage is applied between the first electrode and the second electrode, and the defective portion is subjected to dielectric breakdown ( For example, see Patent Document 1).

  However, in order to prevent moisture and oxygen from entering the inside of the element, an organic EL device in which a sealing film made of silicon nitride or a protective film made of silicone resin or the like is provided on the surface of the organic EL element (for example, a patent) In Reference 2), when a conventional voltage application is performed, there is a risk that the sealing film and the protective film may be destroyed as well as the defective part is not only dielectrically broken down. When the sealing film and the protective film are destroyed in this way, moisture and oxygen enter the element from the inside to generate dark spots, and the dark spots grow with time.

JP 2003-282253 A JP 2000-223264 A

However, if such a broken part of the film is so small that it cannot be visually recognized, it is difficult to find it by a lighting inspection, and there is a problem that a dark spot grows after shipping and the product becomes defective. .
Accordingly, the present invention has been made to solve the above-described conventional problems, and an organic EL device capable of improving the reliability and stability as a product of an organic EL device having a sealing film and a protective film. It aims at providing the manufacturing method of.

As a result of diligent research and development, the present inventors have solved the above-described problems by applying a voltage between the first electrode and the second electrode, and then setting the organic EL element at high temperature and high humidity. The present invention was completed by conceiving that it is effective to perform aging by exposure to the above environment and to form a protective film by curing a moisture curable substance.
That is, in the method for manufacturing an organic EL device according to the present invention, a first electrode, a light emitting layer, and a second electrode are sequentially stacked on a substrate to form an organic EL element, and then moisture is applied to the surface of the organic EL element. An organic EL device manufacturing method for forming a protective film so as to cover an organic EL element by applying and curing a curable substance, after the formation of the organic EL element and before the curing of the moisture curable substance In addition, a voltage is applied between the first electrode and the second electrode, and then the organic EL element is exposed to a high temperature and high humidity environment to perform aging and to cure the moisture curable substance. .
The voltage application in the present invention is preferably performed after application of the moisture curable substance and before curing of the moisture curable substance. Further, this voltage is preferably a reverse bias voltage.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the organic electroluminescent apparatus which can improve the reliability and stability as a product of the organic electroluminescent apparatus provided with the sealing film and the protective film can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic cross-sectional view of an organic EL device manufactured by a method for manufacturing an organic EL device according to an embodiment. The organic EL device includes an anode 2 as a first electrode formed on the substrate 1, a light emitting layer 3 formed on the anode 2, a cathode 4 as a second electrode formed on the light emitting layer 3, An organic EL element A including the anode 2, the light emitting layer 3, and the sealing film 5 covering the cathode 4 is provided, and a protective film 6 is formed so as to cover the entire organic EL element A.

  Next, a method for manufacturing the organic EL device according to the embodiment will be described. FIG. 2 is a process flow diagram of the manufacturing method of the organic EL device according to the embodiment. As shown in FIG. 2, the anode 2 is formed on the surface of the substrate 1, the light emitting layer 3 is then formed on the surface of the anode 2, the cathode 4 is formed on the surface of the light emitting layer 3, and the anode 2, the organic EL element A is formed on the glass substrate 1 by forming the sealing film 5 that covers the light emitting layer 3 and the cathode 4 (organic EL element forming step). After the formation of the organic EL element A, a voltage is applied between the anode 2 and the cathode 4 of the organic EL element A to break down the defective portion present in the organic EL element A (voltage application step). Thereafter, a moisture curable substance is applied onto the surface of the organic EL element A (moisture curable substance application step). Subsequently, by exposing the organic EL element A to an environment of high temperature and high humidity, for example, 30 ° C. to 80 ° C., 60% RH to 90% RH, for example, for 4 hours to 48 hours to cure the moisture curable substance. The protective film 6 is formed (high temperature and high humidity treatment process). In this way, the organic EL device is manufactured. In this high-temperature and high-humidity treatment step, if there are defective portions remaining without being broken down or portions where the sealing film 5 is broken in the organic EL element A, these grow as dark spots. The organic EL device in which the dark spot has grown can be easily excluded as a defective product in the subsequent lighting inspection. That is, the high-temperature and high-humidity treatment process combines the curing of the moisture curable substance and the aging of dark spots.

  As described above, a voltage is applied between the anode 2 and the cathode 4 to break down the defective portion, and then a moisture curable material is applied on the surface of the organic EL element A. Leakage and short-circuiting due to defective parts after shipping, growth of dark spots due to film breakage, etc. by performing aging and curing of moisture curable substances together by exposure to high temperature and high humidity environment Can be greatly reduced. Therefore, an organic EL device with high reliability and stability can be provided.

  Note that the voltage applied between the anode 2 and the cathode 4 is a reverse bias voltage, that is, a voltage at which the potential of the cathode 4 is higher than the anode 2 in order to allow current to flow efficiently only to the defective portion. It is preferable that The voltage value and application time may be set as appropriate according to the layer structure of the organic EL device so as not to damage the organic EL element A. The voltage value is, for example, about 3 V to 10 V, and the application time is, for example, 1 second to 10 seconds are preferable.

  In the organic EL device manufactured as described above, for example, when the light extraction direction is the substrate 1 side, a forward bias voltage of about 4 to 5 V between the anode 2 and the cathode 4 is used. Is applied to the light, the light emitted from the light emitting layer 3 is directly incident on the anode 2 or reflected on the cathode 4 and then incident on the anode 2, and further transmitted through the substrate 1 and emitted.

For the protective film 6 in the organic EL device, a substance that reacts with moisture (moisture) and cures can be used, and a liquid film is preferable from the viewpoint that it can be uniformly and uniformly applied on the surface of the organic EL element A. . Specific examples of such moisture curable substances include polysilazane, moisture curable silicone, moisture curable silicone rubber, and the like. Here, the polysilazane includes a derivative in which a hydrogen part bonded to Si of perhydropolysilazane is partially substituted with an alkyl group or the like. Alkyl groups, particularly those having a low molecular weight methyl group, are supple after curing and have excellent adhesion to the sealing film 5, so that the occurrence of cracks is suppressed even if the thickness of the protective film 6 is increased. The As an alkyl group, a C1-C4 alkyl group is preferable.
Various methods such as a spin method, a dipping method, a flow method, a roll coating method, and a screen printing method can be used as a method for applying the moisture curable substance described above.

  The substrate 1 is a plate-like member for supporting the organic EL element A. When the light extraction direction is the substrate 1 side, for example, a glass substrate, an acrylic resin substrate, or the like is used as the substrate 1. When the light extraction direction is opposite to the substrate 1, an opaque substrate such as a silicon substrate or a metal substrate can be used in addition to the transparent substrate.

For the anode 2 that is the first electrode, a known electrode material is used, and when the light extraction direction is the substrate 1 side, for example, ITO (indium tin oxide), IZO (indium zinc oxide), ZnO A transparent electrode material such as (zinc oxide) is used.
For the cathode 4 as the second electrode, a known electrode material is used, and when the light extraction direction is the substrate 1 side, a metal or an alloy can be used, for example, Ag or Al.
When the light extraction direction is opposite to the substrate 1, a metal, an alloy, or the like is used for the anode 2, and a transparent electrode material is used for the cathode 4.

  A known light-emitting material such as Alq3 is used for the light-emitting layer formed between the anode 2 as the first electrode and the cathode 4 as the second electrode, and emits monochromatic light such as red, green, blue, and yellow. The thing of the structure shown, the luminescent color by those combination, for example, the thing of the structure which shows white light emission, etc. are used. In addition, between the electrodes, one or a plurality of layers employed in a known organic EL device such as a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, a hole block layer, and a buffer layer are appropriately used. Each layer can be appropriately selected from known materials.

  A known sealing film material is used for the sealing film 5, and for example, silicon nitride, silicon oxide, silicon oxynitride, silicon carbide, alumina, or the like is used. Preferably silicon nitride is used. The sealing film 5 may be, for example, a single layer film of silicon nitride, a double layer film of silicon nitride and silicon oxide, or silicon nitride, silicon oxide, silicon oxynitride, silicon carbide, alumina. The multilayer film which laminated | stacked etc. may be sufficient. When an insulating film is used for the first layer (side in contact with the cathode 4), the second and subsequent layers may be metal films such as Al, Pt, Au, Ag, Cu, Cr, and Ti.

  The layers formed between the anode 2, the light emitting layer 3, the cathode 4, the sealing film 5, and other electrodes described above are formed by a known thin film forming method such as a sputtering method, a spin coating method, a CVD method, or a vacuum evaporation method. do it.

  In the above-described embodiment, the case where the voltage application is performed before the moisture curable substance is applied has been described. However, if the moisture curable substance is not cured, it may be applied. By applying a voltage after applying the moisture curable substance, it is possible to make it difficult to cause the sealing film 5 to be broken. In addition, it is possible to avoid mixing of foreign matters into the protective film 6 caused by the destruction of the sealing film 5.

[Example 1]
The organic EL device was manufactured as follows.
An ITO layer (anode) having a thickness of 190 nm was formed on a transparent glass substrate by reactive sputtering. Thereafter, the substrate was washed with alkali, then with pure water, dried, and then subjected to ultraviolet ozone cleaning.
The cleaned substrate is transferred to a vacuum deposition apparatus (vacuum degree: about 5.0 × 10 ⁻⁵ Pa), and copper phthalocyanine having a thickness of 10 nm is deposited on the surface of the anode as a hole injection layer by a carbon crucible. The film was formed at a speed of 0.1 nm / s. Next, a 30-nm-thick triphenylamine tetramer was formed as a hole transport layer on the hole injection layer with a carbon crucible at a deposition rate of 0.1 nm / s. Furthermore, on the hole transport layer, 4,4′-bis (2,2′-diphenylvinyl) biphenyl (DPVBi) having a film thickness of 30 nm was formed as a light emitting layer with a carbon crucible at a deposition rate of 0.1 nm / s. Thereafter, Alq3 having a film thickness of 20 nm was formed as an electron transport layer on the light emitting layer with a carbon crucible at a deposition rate of 0.01 nm / s.
Further, on the electron transport layer, lithium fluoride (LiF) having a film thickness of 0.5 nm was formed as an electron injection layer with a carbon crucible at a deposition rate of 0.03 nm / s. Next, 100 nm-thick aluminum as a cathode was formed on the electron injection layer at a deposition rate of 1 nm / s using a tungsten boat.
Then, the substrate on which the anode, hole injection layer, hole transport layer, light emitting layer, electron transport layer, electron injection layer and cathode were formed was transferred to the CVD chamber of the plasma CVD apparatus, and the pressure was exhausted to 1 × 10 ⁻³ Pa. By flowing SiH ₄ at 100 sccm, NH ₃ at 50 sccm, and N ₂ at 1000 sccm, adjusting the pressure to 75 Pa, supplying high frequency power of 13.56 MHz and 600 W to the pair of electrodes, and discharging the gas, the electrodes and the entire layers are discharged. As a sealing film, silicon nitride having a thickness of 1 μm was deposited.

  After forming the organic EL element on the substrate in this manner, this was taken out from the CVD chamber, and a reverse bias voltage was applied between the anode and the cathode at 5 V for 5 seconds. Next, using a spinner with a rotation speed of 500 rpm, polysilazane (manufactured by AZ Electronic Materials, trade name: Aquamica) was applied as a moisture curable substance so as to cover the entire organic EL element. Next, this was exposed to an environment of temperature 60 ° C. and humidity 90% RH for 24 hours to age and polysilazane was cured to form a protective film having a thickness of 0.5 μm.

  When the lighting test of the organic EL device thus obtained was performed, no defects were found. Subsequently, when the life / reliability evaluation (60 ° C., 90% RH) was performed on the organic EL device after the lighting inspection, no dark spots were observed on the screen even after 500 hours. It was.

[Example 2]
A non-alcohol-type one-component liquid silicone rubber (GE Toshiba Silicone Co., Ltd., TES399) is used as a moisture-curing substance, exposed to a temperature of 40 ° C. and a humidity of 60% RH for 24 hours, and subjected to aging. An organic EL device was obtained in the same manner as in Example 1 except that the rubber was cured to form a protective film having a thickness of 100 μm.
When the lighting test of the organic EL device thus obtained was performed, no defects were found. Subsequently, when the life / reliability evaluation (60 ° C., 90% RH) was performed on the organic EL device after the lighting inspection, no dark spots were observed on the screen even after 500 hours. It was.

[Comparative Example 1]
An organic EL device was obtained in the same manner as in Example 1 except that no reverse bias voltage was applied.
When the lighting test of the organic EL device thus obtained was performed, no defects were found. Subsequently, when the life / reliability evaluation (60 ° C., 90% RH) was performed on the organic EL device after the lighting inspection, the dark spot grew to a visible size after 24 hours.

[Comparative Example 2]
An organic EL device was obtained in the same manner as in Example 1 except that an ultraviolet curable silicone hard coat was used instead of polysilazane, and a protective film having a thickness of 5 μm was formed by curing with ultraviolet irradiation.
When the lighting test of the organic EL device thus obtained was performed, no defects were found. Subsequently, when the life / reliability evaluation (60 ° C., 90% RH) was performed on the organic EL device after the lighting inspection, the dark spot grew to a visible size after 24 hours.

It is a schematic cross section of the organic EL device manufactured by the manufacturing method of the organic EL device according to the embodiment. It is a process flow figure of a manufacturing method of an organic EL device concerning an embodiment.

Explanation of symbols

  1 substrate, 2 anode, 3 light emitting layer, 4 cathode, 5 sealing film, 6 protective film, A organic EL element.

Claims (3)

An organic EL element is formed by sequentially laminating a first electrode, a light emitting layer, and a second electrode on a substrate to form an organic EL element, and then applying and curing a moisture curable material on the surface of the organic EL element. An organic EL device manufacturing method for forming a protective film so as to cover
A voltage is applied between the first electrode and the second electrode after the formation of the organic EL element and before the moisture curable substance is cured, and then the organic EL element is exposed to a high temperature and high humidity environment. A method for producing an organic EL device, comprising aging and curing a moisture curable substance.   2. The method of manufacturing an organic EL device according to claim 1, wherein the voltage is applied after the moisture curable substance is applied and before the moisture curable substance is cured.   The method of manufacturing an organic EL device according to claim 1, wherein the voltage is a reverse bias voltage.

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