JP5318182B2 - Manufacturing method of organic EL element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL element with high reliability. <P>SOLUTION: A manufacturing method for an organic EL element comprises: a step of forming a plurality of organic EL elements each including a first electrode, a second electrode, and an organic EL layer including at least a light-emitting layer sandwiched between the first electrode and the second electrode on a substrate; a step of forming a moisture barrier layer across the organic EL elements; a step of dividing the substrate on which the steps up to the step of forming the moisture barrier layer have been performed, so that plural pieces of the organic EL elements are obtained; and a step of providing a resin layer for covering a side end part of the substrate and a side end part of the moisture barrier layer of the divided organic EL element. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

The present invention relates to a method for manufacturing an organic EL element.

  An organic EL element in which at least a substrate, a first electrode, an organic EL layer, a second electrode, and a moisture-proof layer are laminated is known. The organic EL layer is sealed by a moisture-proof layer and emits light when a voltage is applied by an external drive circuit. In order to extract light from the organic EL layer to the outside, one of the electrodes is transparent, and generally an ITO (Indium Tin Oxide) transparent electrode is used.

  Organic EL elements that emit light based on the above principle are excellent in visibility or flexibility, and have various color development properties. Therefore, they are used in displays and display elements such as in-vehicle components and mobile phones.

  Although it is an organic EL element having these characteristics, on the other hand, the problem that it is generally very weak against moisture is well known. As an example, when the moisture contained in the environmental atmosphere at the time of sealing the organic EL layer or the moisture that permeates through the defective portion of the moisture-proof layer enters the organic EL element, non-light emission called a dark spot There is a problem of a lifetime in which a region is generated and light emission cannot be maintained.

  In addition, the emission efficiency of the organic EL element may be reduced due to oxidation of the electrode by oxygen as well as moisture.

  The following method is known as a measure for solving the problem relating to the reduction in the lifetime of the organic EL element due to the influence of moisture and oxygen. The upper surface of the organic EL element is sealed with a moisture-proof layer made of an inorganic material such as silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, titanium oxide, amorphous silicon, diamond-like carbon, or SiCN (Patent Document 1, Patent Document 2, Patent Document 3 and Patent document 4).

  FIG. 5 shows a typical schematic cross-sectional view of a top emission type organic EL device in which the light emitting side surface is sealed with a moisture-proof layer. As shown in the figure, an organic EL element composed of a glass substrate 1, an anode 2, an organic EL layer 3, a cathode 4, and a moisture-proof layer 5 is sealed with a glass plate 14 and an adhesive layer 13 (Patent Document 5).

JP-A-8-111286 JP 2000-58256 A JP 2000-208253 A JP 2002-117773 A JP 2004-281380 A

  In order to form the moisture-proof layer, a so-called plasma CVD method is generally performed, which is performed by exposing a substrate of an organic EL element provided up to a cathode to a plasma atmosphere of a source gas. When producing an organic EL element, the anode, the organic EL layer, the cathode, and the moisture-proof layer are formed on a large glass substrate, and then divided into a plurality of organic EL elements. Therefore, the cut end face of the moisture-proof layer is exposed at the side edge of the organic EL element as shown in FIG.

  When a reliability test such as a high-temperature and high-humidity test is performed on such an organic EL element, moisture permeates from the interface between the moisture-proof layer and the substrate at the side edge of the organic EL element, which causes the moisture-proof layer to peel off. Or the luminous efficiency of the organic EL element is reduced.

  In order to solve this problem, a method of preventing the moisture-proof layer from being formed on the cut portion of the substrate using a mask is conceivable, but the thickness of the moisture-proof layer adjacent to the mask portion is reduced, so that a sufficient effect as a moisture-proof layer is achieved. There is a problem that it can not be demonstrated.

  In view of the above circumstances, the present invention improves the reliability of an organic EL element in which the cut end surface of the moisture-proof layer is exposed by cutting and dividing into a plurality of organic EL elements after forming the moisture-proof layer. For the purpose. That is, an object of the present invention is to provide a highly reliable organic EL element in which moisture does not enter from the interface between the moisture-proof layer and the underlying glass substrate at the side edge portion and the moisture-proof layer does not peel off.

As a means for solving the problems of the background art described above, a method for producing an organic EL element according to the present invention includes:
A plurality of organic EL elements each including a first electrode, a second electrode, and an organic EL layer including at least a light emitting layer sandwiched between the first electrode and the second electrode are formed on a substrate. And a process of
Plasma CVD anti Shimeso over a plurality of the organic EL element, a resistance heating deposition method, a step of forming by electron beam evaporation or sputtering,
Cutting the substrate on which the moisture proof layer is formed and dividing it into a plurality of organic EL elements;
Providing a resin layer covering a side edge of the moisture-proof layer of the divided organic EL element and a side edge of the substrate;
It is characterized by having.

  According to the present invention, at least a substrate, a first electrode, an organic EL layer, a second electrode, and a moisture-proof layer are laminated, and the moisture-proof layer is formed up to the peripheral edge of the substrate. A resin layer is provided so as to cover the side edge of the moisture-proof layer. Therefore, the reliability of the organic EL element in which the cut end surface of the moisture-proof layer is exposed is improved. That is, since the side edge portion of the moisture-proof layer is covered with the resin layer, the moisture-proof layer does not peel off from the interface between the moisture-proof layer and the glass substrate therebelow at the side edge portion. It becomes a highly organic EL element.

It is sectional drawing which showed the structure of the organic EL element in this invention typically. 3 is a partial cross-sectional view schematically showing the structure of the organic EL element of Example 1. FIG. 5 is a partial cross-sectional view schematically showing the structure of an organic EL element of Example 2. FIG. 6 is a partial cross-sectional view schematically showing the structure of an organic EL element of Example 3. FIG. It is sectional drawing which showed typically the organic EL element of a general top emission system. It is sectional drawing which showed typically the organic EL element which the cut end surface of the moisture-proof layer exposed.

  FIG. 1 shows a schematic cross-sectional view of the organic EL device in the present invention. In FIG. 1, 1 is a glass substrate, 2 is a first electrode, 3 is an organic EL layer, 4 is a second electrode, 5 is a moisture-proof layer, and 6 is a resin layer.

  First, the moisture-proof layer 5 and the resin layer 6 are demonstrated among each member which comprises the organic EL element in this invention.

  The moisture-proof layer 5 is provided to protect the organic EL element from the influence of moisture and oxygen and prevent its deterioration. As the material, for example, inorganic substances such as silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, titanium oxide, amorphous silicon, diamond-like carbon, and SiCN are suitable. Of these, silicon nitride is preferred because it has excellent moisture resistance, film-forming properties, and crack resistance. In the case of a top emission type organic EL element, transparency is also required. Since silicon nitride is slightly colored, a method such as doping with hydrogen is employed to increase transparency.

  The thickness of the moisture-proof layer 5 is, for example, 500 to 10,000 nm. If it is less than 500 nm, sufficient moisture resistance cannot be exhibited due to pinholes or the like, and if it exceeds 10000 nm, cracks are likely to occur due to external stress.

  A method for forming the moisture-proof layer 5 may be selected from plasma CVD, resistance heating vapor deposition, electron beam vapor deposition, and sputtering. In the case of silicon nitride, the plasma CVD method is generally used.

  The resin layer 6 is provided so as to cover at least the side edge of the moisture-proof layer 5. Therefore, the reliability of the organic EL element in which the cut end face of the moisture-proof layer 5 is exposed is improved by cutting and dividing into a plurality of organic EL elements. That is, since the side edge portion of the moisture-proof layer 5 is covered with the resin layer 6, moisture enters from the interface between the moisture-proof layer 5 and the glass substrate 1 below the side edge portion, and the moisture-proof layer 5 is peeled off. And a highly reliable organic EL element. The resin layer 6 is preferably provided so as to cover not only the side edge portion of the moisture-proof layer 5 but also the upper surface of the side edge portion of the moisture-proof layer 5, and further provided to cover the side edge portion and the lower surface of the glass substrate 1. Is more preferable. In short, the resin layer 6 only needs to be provided so as to cover the interface between the moisture-proof layer 5 and the glass substrate 1.

  The material constituting the resin layer 6 is not particularly limited as long as it has sufficient adhesion to the moisture-proof layer 5 and can suppress the ingress of moisture into the interface between the moisture-proof layer 5 and the glass substrate 1. . For example, acrylic resin, silicon resin, fluorine resin, epoxy resin, ethylene polymer resin, metal alkoxide polymer, and the like can be given. Among them, acrylic resin, epoxy resin, polyisobutylene resin, isobutene-isoprene copolymer resin, and metal alkoxide polymer have high moisture resistance and are preferably used in the present invention.

  Specific examples of the acrylic resin and the epoxy resin include a liquid acrylic resin and a liquid epoxy resin mixed with a curing agent such as a photoreaction initiator and a thermal reaction initiator and cured.

  As the metal alkoxide polymer, a polymer produced by a so-called sol-gel method in which a metal alkoxide compound such as alkoxysilane or alkoxytitanium is hydrolyzed and polymerized in a solution of alcohol or the like is preferably used.

  It is desirable to add a silane coupling agent or a titanium coupling agent to the resin layer 6 in order to improve the adhesion to the moisture-proof layer 5. The addition amount is appropriately 0.5 to 5.0 parts by weight with respect to 100 parts by weight of the resin.

  The resin layer 6 is formed by applying a liquid resin. For example, it may be performed by dipping or by discharging resin from a dispenser. Furthermore, it may be performed by screen printing, roll coating, or the like.

  Next, a method for manufacturing the organic EL element of the present invention will be described with reference to FIG.

  A plurality of organic EL elements composed of the first electrode 2, the organic EL layer 3, and the second electrode 4 are formed on a glass substrate 1 by a film forming apparatus such as a vapor deposition apparatus or a spin coater, and a moisture-proof layer 5 is further formed. Thus, an organic EL element substrate is produced.

  After the substrate is cut into a plurality of organic EL elements, a resin layer 6 is formed on the side edge where the moisture-proof layer 5 is exposed.

  Finally, the organic EL element of the present invention emits light by connecting the electrodes 2 and 3 to an external circuit (not shown).

  Hereinafter, the organic EL device of the present invention will be described in detail based on specific examples. In addition, this invention is not limited to a following example at all, and can be variously changed within the range of the summary.

<Example 1>
A first embodiment of the present invention will be described with reference to FIG. In FIG. 2, 7 is a glass substrate on which a TFT circuit is formed, 2 is an anode, 3 is an organic EL layer, 4 is a cathode, 5 is a moisture-proof layer, 8 is an element isolation film, 9 is a planarizing film, and 6 is a resin layer. It is. Below, the detailed manufacturing method of an organic EL element is described.

[Flattening film formation]
A planarizing film 9 made of acrylic resin was formed on a glass substrate 7 on which TFT circuits of a plurality of panels were formed by a photolithography method, and the unevenness due to the circuit was flattened.

[Cr electrode formation]
A Cr target was DC sputtered on the glass substrate 7 on which the planarizing film 9 was formed, and a Cr film having a thickness of 100 nm was formed as the anode 2. At this time, a pixel electrode of 20 μm × 100 μm was formed using a film formation mask. Using Ar gas, the pressure was 0.2 Pa and the input power was 300 W.

[Atmospheric release]
The glass substrate 7 which had been processed up to the above step was taken out of the sputtering apparatus, was successively ultrasonically washed with acetone and isopropyl alcohol (IPA), then was boiled and washed with IPA and then dried. Further, UV / ozone cleaning was performed.

[Element isolation film formation]
In order to separate each pixel, an element isolation film 8 made of polyimide resin was formed by a photolithography method.

[Preprocessing]
It moved to the organic electroluminescent vapor deposition apparatus, evacuated, and 50-W RF electric power was supplied to the ring-shaped electrode provided near the board | substrate in the pre-processing chamber, and the oxygen plasma cleaning process was performed. The oxygen pressure was 0.6 Pa and the treatment time was 40 seconds.

[Hole transport layer formation]
The glass substrate 7 that has been subjected to the above steps is moved from the pretreatment chamber to the film formation chamber, and after the film formation chamber is evacuated to 1 × 10 ⁻⁴ Pa, αNPD having hole transportability is formed by resistance heating vapor deposition. A film was formed under the condition of a film speed of 0.2 to 0.3 nm / sec, and a hole transport layer having a film thickness of 35 nm was formed. Note that the hole transport layer, the light emitting layer, and the electron injection layer were deposited on predetermined portions by using the same deposition mask. The predetermined portion is a portion on the glass substrate 7 where the pixel electrode Cr is exposed.

[Light emitting layer formation]
Subsequently, Alq3, which is an alkylate complex, was formed on the hole transport layer by resistance heating vapor deposition under the same film formation conditions as the hole transport layer to form a light emitting layer having a film thickness of 15 nm.

[Electron injection electrode layer formation]
A film is formed on the light emitting layer by resistance heating co-evaporation so that Alq3 and cesium carbonate (Cs2CO3) are mixed at a film thickness ratio of 9: 1 to adjust the respective vapor deposition rates. An electron injection layer was formed. Specifically, the material set in each evaporation boat is evaporated by resistance heating method, the organic layer is ~ 0.5 nm / sec, and the co-deposition layer is also adjusted to each boat current value, so that it is ~ 0.5 nm. Film formation was performed at a deposition rate of / sec.

[Cathode (transparent conductive film) formation]
The glass substrate 7 which has been subjected to the above steps is transferred to another film formation chamber, and a film is formed on the electron injection layer to a thickness of 130 nm by a DC magnetron sputtering method using an ITO target, and a cathode made of ITO. 4 was formed.

[Dampproof layer formation]
The moisture-proof layer 5 was formed. That is, a silicon nitride film having a thickness of 1 μm was deposited on the cathode 4 by plasma CVD. At this time, the silicon nitride film was not deposited by the mask only on the electrode portion to which the FPC was connected in the mounting process described later. Otherwise, a silicon nitride film was deposited on the entire surface over a plurality of organic EL elements.

  As described above, on the glass substrate 7 on which the TFT circuit is formed, the planarization film 9, the anode 2, the element isolation film 8, the organic EL layer 3 (hole transport layer, light emitting layer, electron injection electrode layer), A cathode 4 and a moisture-proof layer 5 were provided to produce an organic EL device.

[Cutting process]
A substrate having a plurality of organic EL elements was cut using a precision glass scriber and separated into individual organic EL elements.

[Side edge sealing process]
It moves to the process of sealing the side edge part of the moisture-proof layer 5 with resin. That is, the resin layer 6 was formed by applying an ultraviolet curable adhesive to the side edge of the organic EL element with a precision dispenser.

Here, as the ultraviolet curable adhesive, a photocationic polymerization type liquid epoxy resin in which 1.0 part by weight of an epoxy silane coupling agent was added to 100 parts by weight of the resin was used. Then, the adhesive was irradiated with an ultraviolet ray having an irradiation intensity of 100 mW / cm ² in a wavelength region of 300 to 390 nm with a metal halide lamp so as to have an irradiation dose of 6000 mJ / cm ² , and further heated at 100 ° C. for 30 minutes.

[Mounting process]
Finally, a flexible printed wiring board (FPC) necessary for connecting a drive circuit (not shown) for driving the organic EL element was mounted. That is, FPC was bonded to an extraction line (not shown) of the organic EL element by thermocompression bonding with an anisotropic conductive film (ACF) to join the FPC.

  A high-temperature and high-humidity test was conducted in which the organic EL device produced by the above process was stored for 1000 hours in an environment of 60 ° C./90% RH. Thereafter, when the appearance was observed visually and with an optical microscope, no problem was found. Further, no abnormality was observed in the light emission characteristics of the organic EL element evaluated by applying a voltage between the anode 2 and the cathode 3.

<Example 2>
A second embodiment of the present invention will be described with reference to FIG. In FIG. 3, 7 is a glass substrate on which a TFT circuit is formed, 11 is a sealing glass, 10 is a transparent filling layer, 12 is an ultraviolet curable adhesive, 2 is an anode, 3 is an organic EL layer, 4 is a cathode, 5 Is a moisture-proof layer, 8 is an element isolation film, 9 is a planarizing film, and 6 is a resin layer. Below, the detailed manufacturing method of an organic EL element is described. In addition, since it is the same as that of Example 1 until the cutting process, description is abbreviate | omitted.

[Sealing process]
In order to impart barrier properties to the organic EL element with a sealing material that does not allow water vapor in the air to enter, the process proceeds to the formation of the transparent filling layer 10 and the sealing step using the ultraviolet curable adhesive 12.

  As the transparent filling layer 10, a two-component thermosetting type acrylic ester liquid adhesive was used. That is, this liquid resin was applied on the sealing glass 11 by a spin coater with a thickness of 15 μm, and heat cured on a hot plate (not shown) to obtain an adhesive. The heating condition at that time is 80 ° C./30 minutes.

  After heat curing, the organic EL element formed up to the moisture-proof layer 5 and cut was bonded to the sealing glass 11 on which the transparent filling layer 10 was formed.

  After bonding, in order to improve the barrier property of moisture from the outside, the side edge portion of the sealing glass 11 was sealed with the ultraviolet curable adhesive 12 with a precision dispenser.

  Further, the same ultraviolet curable adhesive was subsequently applied to the side edge portion of the organic EL element with a precision dispenser to form the resin layer 6.

Examples of the ultraviolet curable adhesive, using the cationic photopolymerizable liquid epoxy resin, such as a dose of 6000 mJ / cm ² ultraviolet irradiation intensity 100 mW / cm ² in the wavelength region of 300~390nm metal halide lamp The adhesive was irradiated.

  These sealing steps were performed in a glove box (not shown) in which the moisture concentration was controlled to 10 ppm or less, and consideration was given to minimize deterioration of the organic EL element due to moisture in the step.

  Finally, FPC was joined in the same manner as in Example 1 to complete the organic EL device. When this organic EL element was subjected to the same high-temperature and high-humidity test as in Example 1 and the organic EL element after the test was evaluated, no abnormality was observed in the appearance and light emission characteristics.

<Example 3>
A third embodiment of the present invention will be described with reference to FIG. In FIG. 4, 7 is a glass substrate on which a TFT circuit is formed, 11 is a sealing glass, 10 is a transparent filling layer, 2 is an anode, 3 is an organic EL layer, 4 is a cathode, 5 is a moisture-proof layer, and 8 is element isolation. A film 9 is a planarizing film. Below, the detailed manufacturing method of an organic EL element is described. In addition, since it is the same as that of Example 1 until the cutting process, description is abbreviate | omitted.

[Sealing process]
In order to impart barrier properties to the organic EL element with a sealing material that does not allow water vapor in the air to enter, the process proceeds to a sealing step by forming the transparent filling layer 10.

  As the transparent resin of the transparent filling layer 10, a thermosetting epoxy liquid resin in which 1.0 part by weight of an epoxy silane coupling agent was added to 100 parts by weight of the resin was used. This liquid resin is applied on the sealing glass 11 by screen printing to a thickness of 15 μm, and the organic EL element formed by cutting up to the moisture-proof layer 5 and the sealing glass 11 on which the transparent filling layer 10 is formed are attached in a vacuum. Combined. At this time, the sealing glass 11 was made slightly larger than the organic EL element so that the transparent filling layer 10 covered the side edge of the organic EL element. That is, in this embodiment, the transparent filling layer 10 also serves as a resin layer that covers the side edge of the moisture-proof layer 5.

  After bonding, the transparent filling layer 10 was hardened by heating at 100 ° C. for 60 minutes.

  These sealing steps were performed in a glove box (not shown) in which the moisture concentration was controlled to 10 ppm or less, and consideration was given to minimize deterioration of the organic EL element due to moisture in the step.

  Finally, FPC was joined in the same manner as in Example 1 to complete the organic EL device. When this organic EL element was subjected to the same high-temperature and high-humidity test as in Example 1 and the organic EL element after the test was evaluated, no abnormality was observed in the appearance and light emission characteristics.

<Example 4>
Since the process up to the cutting step is the same as that of the first embodiment, the description thereof is omitted.

[Side edge sealing process]
Instead of the ultraviolet curable adhesive of Example 1, the side edge of the moisture-proof layer 5 was sealed with an alkoxysilane polymer. That is, after immersing the side edge portion of the organic EL element in an alcohol solution of alkoxysilane containing a catalyst, the resin layer 6 made of an alkoxysilane polymer was formed by heating at 100 ° C. for 30 minutes.

  Finally, FPC was joined in the same manner as in Example 1 to complete the organic EL device. When this organic EL element was subjected to the same high-temperature and high-humidity test as in Example 1 and the organic EL element after the test was evaluated, no abnormality was observed in the appearance and light emission characteristics.

<Comparative Example 1>
An organic EL element was produced in the same manner as in Example 1 except that the resin layer was not formed.

  When this organic EL device was observed visually and with an optical microscope after the high-temperature and high-humidity test in the same manner as in Example 1, cracks were generated in the moisture-proof layer from the side edges, and peeling of the moisture-proof layer was observed.

  Further, when the organic EL element was caused to emit light, it was confirmed that the organic EL layer of the pixel in the peripheral portion of the panel was deteriorated to greatly reduce the light emission efficiency, and that some of the pixels did not emit light.

<Comparative example 2>
An organic EL device was produced in the same manner as in Example 2 except that the resin layer was not formed.

  When this organic EL device was observed visually and with an optical microscope after the high-temperature and high-humidity test in the same manner as in Example 1, cracks were generated in the moisture-proof layer from the side edges, and peeling of the moisture-proof layer was observed.

  Further, when the organic EL element was caused to emit light, it was confirmed that the organic EL layer of the pixel in the vicinity of the side edge portion of the organic EL element was deteriorated and the light emission efficiency was lowered although it was lighter than Comparative Example 1.

  DESCRIPTION OF SYMBOLS 1 Glass substrate, 2 1st electrode, 3 Organic EL layer, 4 2nd electrode, 5 Moisture-proof layer, 6 Resin layer, 7 Glass substrate which formed TFT circuit, 8 Element isolation film, 9 Planarization film, 10 Transparent Filling layer, 11 sealing glass, 12 UV curable resin, 13 adhesive layer, 14 glass plate

Claims (2)

A plurality of organic EL elements each including a first electrode, a second electrode, and an organic EL layer including at least a light emitting layer sandwiched between the first electrode and the second electrode are formed on a substrate. And a process of
Plasma CVD anti Shimeso over a plurality of the organic EL element, a resistance heating deposition method, a step of forming by electron beam evaporation or sputtering,
Cutting the substrate on which the moisture proof layer is formed and dividing it into a plurality of organic EL elements;
Providing a resin layer covering a side edge of the moisture-proof layer of the divided organic EL element and a side edge of the substrate;
The manufacturing method of the organic EL element characterized by having. The step of providing a resin layer that covers the side edge of the moisture-proof layer of the divided organic EL element and the side edge of the substrate,
A step of applying a resin material for sealing glass,
Bonding the surface of the sealing glass on which the resin material is formed to the divided organic EL element;
Curing the resin material and providing a resin layer covering the side edge of the moisture-proof layer of the divided organic EL element and the side edge of the substrate;
The manufacturing method of the organic EL element of Claim 1 characterized by the above-mentioned.

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