JP2008171606A - Manufacturing method and manufacturing system of organic EL element - Google Patents

Abstract

Performance degradation due to moisture of a sealing plate for sealing an organic EL layer or the like of an organic EL element is prevented.
The sealing plate is dehydrated in the hermetic work chamber 15, and the hermetic work chamber 16 for pre-treatment and the hermetic work chamber 17 for applying a sealant are used to bond the organic EL element substrate. Transport to work chamber 14. The airtight working chambers 16, 17, and 14 constitute an integrated apparatus having an airtight atmosphere with moisture management, and the dewatered sealing plate is transferred to the airtight working chamber 14 without absorbing moisture, and is organic. Bonding with the EL element substrate is performed.
[Selection] Figure 2

Description

  The present invention relates to an organic EL element manufacturing method and a manufacturing system for manufacturing an organic EL element having a sealing plate for sealing an organic EL layer.

  The organic EL element has a configuration in which an organic thin film containing a fluorescent organic compound is sandwiched between a cathode and an anode.

Then, electrons and holes are injected into the organic thin film and recombined to generate excitons, and light emission (fluorescence, phosphorescence) when the excitons are deactivated is used. To emit light. The characteristics of this organic EL element are that it can emit surface light with a high luminance of about 100 to 100,000 cd / m ² at a low voltage of 10 V or less, and can emit light from blue to red by selecting the type of fluorescent material. It is a thing. In addition, the organic thin film is formed by a vacuum evaporation method for a low molecular (monomer) organic EL material and further by a vacuum evaporation method for electrode formation.

  The organic EL element having the above configuration is a current-driven light emitting element, and the element generates heat during high current light emission. When oxygen or moisture is present around each laminated film or the element, the element constituent material is promoted to oxidize, causing a problem that light emission failure due to alteration of the constituent material, a so-called dark spot is generated and grows. Therefore, it is necessary to eliminate the contact of the element with the atmosphere between each film forming process and between the processes, and to suppress damage due to oxygen and moisture adhesion to the element film. Therefore, after vapor deposition film formation, the atmosphere in the working space is limited and the element is sealed with a metal or glass sealing plate, and many proposals have been made for maintaining a working environment for sealing.

For example, the working space to be sealed is limited to 100 PPM or less having the same moisture content as the airtight space by the sealing plate of the organic EL element, or sealed in an atmosphere in which the moisture concentration and oxygen concentration are controlled to 5 PPM or less respectively ( Have been proposed (see Patent Documents 1 and 2). It has also been proposed to perform sealing under a reduced pressure of 1 × 10 ⁻¹ to 1 × 10 ⁻¹⁰ Torr (see Patent Document 3).

  Furthermore, regarding the element substrate, a proposal has been made to carry out the sealing operation without exposure to the atmosphere in an inert gas atmosphere by performing a heat dehydration process before film formation in an integrated unit (see Patent Document 4).

Regarding the sealing plate, it has been proposed to remove moisture by heating at 100 ° C. or higher, and then seal the element part in a transparent protective cap in the range of a dew point temperature of −85 ° C. to −35 ° C. in a nitrogen atmosphere. (See Patent Document 5).
JP-A-10-233283 Japanese Patent Laid-Open No. 11-45778 JP-A-10-335061 Republished patent WO01 / 072091 JP 2003-109752 A

  In the above conventional technique, although the moisture management of the element substrate (organic EL element substrate) on which the electrode and the organic EL layer are formed and the moisture management of the sealing work space for joining the sealing plate to the element substrate are performed, the sealing is performed. The element substrate and the sealing plate are bonded together with insufficient moisture management of the stop plate itself. For this reason, problems such as deterioration in performance of the organic EL element and increase in variation have occurred.

  For example, when the sealing plate is put into the bonding chamber with the organic EL element substrate after the cleaning process, there is a problem that the panel performance is deteriorated due to insufficient moisture removal from the sealing plate. In addition, when the vacuum degassing treatment of the sealing plate is performed in a vacuum drying furnace, the apparatus is a separate body, and the sealing plate after the dehydration treatment is once taken out to the atmosphere and then put into the bonding chamber. For this reason, there has been a problem that the panel performance deteriorates due to re-adhesion of moisture to the sealing plate.

  An object of the present invention is to provide a manufacturing method and a manufacturing system of an organic EL element that can suppress the reattachment of moisture after removing moisture from the sealing plate and contribute to improvement in element performance and long life. Is.

  The method for producing an organic EL element of the present invention comprises a step of preparing an organic EL element substrate having an organic EL layer disposed between a pair of electrodes, and a dehydration of a sealing plate for sealing the organic EL element substrate And a step of bonding the dehydrated sealing plate to the organic EL element substrate, and the sealing plate from dehydration to bonding is kept in an airtight atmosphere with controlled moisture concentration. It is characterized by that.

  An organic EL element manufacturing system according to the present invention includes an apparatus for forming an organic EL element substrate having an organic EL layer disposed between a pair of electrodes, and a sealing plate for sealing the organic EL element substrate. A dehydration chamber for performing a dehydration process, a bonding chamber for performing a bonding process between the sealing plate and the organic EL element substrate, and an intermediate processing chamber interposed between the dehydration chamber and the bonding chamber; The intermediate processing chamber and the bonding chamber have an airtight atmosphere in which the moisture concentration is controlled.

  Intermediate treatment such as UV ozone treatment after the sealing plate is dehydrated is performed in an airtight atmosphere in which the moisture concentration is controlled, and is bonded to the organic EL element substrate. As a result, a high-performance organic EL element free from the influence of moisture from the sealing plate can be obtained.

  The best mode for carrying out the present invention will be described with reference to the drawings.

  As shown in FIG. 1, an organic EL element substrate that is a laminated structure includes a first electrode (anode) 2 made of an ITO transparent electrode, a hole injection layer 3, an organic light emitting layer 4, and an electron injection layer on a substrate 1. 5 and an organic EL layer 10 and a second electrode (cathode) 6 are sequentially stacked. And the box-shaped sealing board 7 is bonded together so that this laminated structure may be sealed. The sealing plate 7 is formed of glass, metal, ceramics, a low moisture permeability polymer material, or the like. For the sealant 8 that seals the periphery of the sealing plate 7, an ultraviolet curable adhesive is used. The sealing plate 7 may have a flat plate shape or may be partially grooved. If the function of sealing the laminated structure is fulfilled, the shape of the sealing plate 7 is not limited.

The first electrode 2 that is an anode may or may not need transparency depending on the light extraction structure. However, a material having a large work function (4 eV or more) is suitable. As the transparent anode, CuI, ITO, SnO ₂ , ZnO, MgIn ₂ O ₄ , Zn ₂ In ₂ O ₅ , InGaZnO _{4 and the} like are preferable. Regarding the light transmittance, the larger the transmittance at the visible light wavelength, the better, and it is preferably 80% or more. As the opaque anode, in addition to the above transparent anode material, general materials such as aluminum, chromium, gold, copper, and alloys and oxides thereof may be used.

  Depending on the light extraction structure, the second electrode 6 that is a cathode may or may not need transparency. However, a material having a small work function (4 eV or less) is suitable. As the transparent cathode, thin films such as cesium and magnesium, sodium, lithium, indium, rare earth metals and alloys, oxides and carbonates are preferable. Regarding the light transmittance, the higher the transmittance at the visible light wavelength, the better, and preferably 80% or more. In order to lower the resistance value, it is preferable to combine with ITO. As an opaque cathode material, cesium and magnesium, sodium, lithium, indium, rare earth metals and alloys, oxides, carbonates and the like are preferable. Furthermore, in order to lower the resistance value, the cathode material may be compounded with general materials such as aluminum, chromium, gold, copper, and alloys and oxides thereof.

  The organic EL layer 10 provided between the pair of electrodes 2 and 6 constituting the anode and the cathode is composed of a plurality of layers. Each thin film preferably has a molecular weight of 5000 or less, and at least two kinds selected from a light emitting material, a hole injection material, an electron injection material, a hole transport material, and an electron transport material can be used.

  In order to make the organic light-emitting layer 4 an amorphous film with good light emission efficiency, it is preferable that the difference between the melting point mp and the glass transition point Tg is 50 ° C. or more. Further, the number of layers may be two or more.

  The light emitting materials for each color include triarylamine derivatives, stilbene derivatives, polyarylenes, aromatic condensed polycyclic compounds, aromatic heterocyclic compounds, aromatic heterocyclic condensed ring compounds, metal complex compounds, etc. The body can be used. However, the present invention is not limited to this.

  As the hole injection layer 3, soluble phthalocyanine compounds, triarylamine compounds, conductive polymers, perylene compounds, Eu complexes, and the like can be used, but are not limited thereto.

  As the electron injection layer 5, Alq3 in which an 8-hydroxyquinoline trimer is coordinated to aluminum, an azomethine zinc complex, a distyrylbiphenyl derivative system, or the like can be used, but is not limited thereto.

  The thickness of each layer of the organic EL layer 10 provided between the pair of electrodes 2 and 6 constituting the anode and the cathode needs to be about 0.05 to 0.2 μm, and most particularly the first electrode 2 serving as the anode. The near layer is about 0.01 to 0.05 μm. The film thickness is based on the thickness on the first electrode 2.

  For example, when ITO is used as the transparent electrode for the anode and the electrode is directly formed on the substrate, the ITO pattern is formed by sputtering, vapor deposition, or the like. Then, after applying the resist, the wiring pattern is exposed and developed, the ITO without the resist is etched with acid, and finally the resist is peeled off to form. Alternatively, after patterning with a resist, ITO is formed into a film, and then formed by a “lift-off method” in which the ITO is also peeled at the same time when the resist is peeled off.

  For example, when aluminum is used as the metal electrode for the cathode, the pattern formation method is the same as that for the transparent electrode. When the substrate is directly on the substrate, a photolithographic etching method or a lift-off method is used, and a shadow mask is used after the organic EL layer is formed.

  FIG. 2 shows an organic EL element manufacturing system for manufacturing the organic EL element of FIG. 1, and shows a first apparatus (11 to 13) for forming a laminated structure to be an organic EL element substrate. Have. Moreover, it has the 2nd apparatus (14-17) for preparing a sealing plate and bonding together with an organic EL element substrate.

  The substrate of the organic EL element substrate is first cleaned and dried by an external device, and then carried into the airtight working chamber 11 where moisture is removed from the substrate by vacuum dehydration. Subsequently, it moves to the airtight working chamber 12 and performs UV ozone pretreatment. Subsequently, it moves to the vacuum chamber 13 and forms each layer of the organic EL layer and the second electrode by vapor deposition. A plurality of vacuum chambers 13 are provided, and each of the organic EL layers is formed by vapor deposition, and the second electrode, which is a transparent electrode, is formed by sputtering. Next, the organic EL element substrate moves to the hermetic work chamber 14 which is a bonding chamber capable of decompression.

  On the other hand, the sealing plate is first washed and dried by an external device, and then carried into an airtight working chamber 15 that is a dehydration chamber, and moisture is removed from the sealing plate by vacuum dehydration. Subsequently, it moves to the airtight working chamber (intermediate processing chamber) 16 and pretreatment with UV ozone is performed. Furthermore, it moves to the airtight working chamber (intermediate processing chamber) 17 and the sealing agent is applied to the outer periphery of the sealing plate by the dispenser device. In some cases, a getter sheet is attached or a desiccant is applied and processed. The sealing plate moves to the airtight working chamber 14 through such an intermediate processing chamber.

  Thereafter, the airtight working chamber 14 is decompressed and the organic EL element substrate and the sealing plate are bonded to form a panel. Furthermore, UV curing is also performed with pressure applied. Thereafter, the panel is carried out from the airtight working chamber 14 to the outside.

  Here, as the working environment of the organic EL element substrate, the airtight working chambers 11, 12, and 14 are controlled to have a moisture concentration of 10 PPM or less. In addition, as a work environment of the sealing plate, the airtight work chambers 15, 16, and 17 are also controlled to have a water concentration of 10 PPM or less. Each of the airtight working chambers 11, 12, 14, 15, 16, and 17 is equipped with a nitrogen circulation purification device and can supply nitrogen circulation. Or circulation supply of dry air is possible. Each airtight working chamber and the vacuum chamber 13 are connected by a gate valve.

  The organic EL element was manufactured with the organic EL manufacturing apparatus shown in FIG.

  The substrate was a non-alkali glass (trade name: Corning 1737) having a thickness of 0.7 mm, and an ITO (15Ω / □) film was formed on the substrate as an anode, and then a pattern was formed by photolithography etching.

First, the substrate was subjected to pure water ultrasonic cleaning and IPA ultrasonic cleaning using a separate apparatus, and then pulled up with IPA vapor and dried. Thereafter, the substrate was introduced into the organic EL manufacturing apparatus through the substrate carry-in port 21, and then the airtight working chamber 22 was leaked with a vacuum pump, and 10 PPM of dry air was sealed. Next, the surface of the transparent electrode was cleaned with UV ozone. Next, the inside of the airtight working chamber 23 was heated to 80 ° C., and then the organic EL element substrate was held for 30 minutes while the pressure was reduced to 1 × 10 ⁻⁴ Pa or less. Next, the organic EL element substrate was moved to the vacuum transfer chamber 24 while maintaining the vacuum, and then transferred sequentially to the vacuum working chamber 26 for each film formation by the transfer robot 25.

  First, the hole transport layer was formed by depositing 0.02 μm of triphenylamine hexamer by vapor deposition. Next, the organic light emitting layer was formed by depositing 1.0 wt% of coumarin into a 9,9-dioctylfluorene pentamer by vapor deposition. Next, an electron transport layer was formed by depositing a pentamer of 9,9-dioctylfluorene by a vapor deposition method to a thickness of 0.04 μm. Then, an electron injection layer was formed by depositing 0.01% of Li by doping Li with 1.8% by vapor deposition. Next, a cathode (metal layer) was formed by depositing Al to a thickness of 0.12 μm. The organic EL element substrate is moved to an airtight working chamber (bonding chamber) 27 that can be decompressed.

  The sealing plate is made of alkali-free glass (trade name: Corning 1737) having a thickness of 0.7 mm, and an etching engraving process having a depth of 0.4 mm is performed on the central portion while leaving an outer peripheral width of 2 mm.

The sealing plate was subjected to pure water ultrasonic cleaning and IPA ultrasonic cleaning using a separate device, and then pulled up and dried with IPA vapor, and charged into the organic EL manufacturing apparatus through the sealing plate inlet 28. Next, after leaking the airtight working chamber 29 with a vacuum pump, dry air having a moisture concentration of 10 PPM was sealed, and the etching surface of the sealing plate was cleaned with UV ozone. Next, after heating the airtight working chamber (dehydration processing chamber) 30 to 80 ° C., the sealing plate is held for 30 minutes while reducing the pressure to 1 × 10 ⁻⁴ Pa or less, and the airtight working chamber 30 is leaked with nitrogen having a moisture concentration of 10 PPM. did. Next, the sealing plate was moved to a normal pressure transfer chamber 31 in a nitrogen environment having a moisture concentration of 10 PPM, and was sequentially transferred to each normal pressure work chamber (intermediate processing chamber) 33 by the transfer robot 32.

  Here, it was first transported to a working environment in a nitrogen environment having a moisture concentration of 10 PPM, and a getter sheet was attached to the inner surface of the sealing plate having a depth of 0.4 mm.

  Subsequently, it is transported to a normal pressure working chamber in a nitrogen environment having a moisture concentration of 10 PPM, and a sealing agent is applied to the glass outer peripheral width 2 mm portion of the sealing plate with a dispenser device. The sealant is a UV curable adhesive [trade name: World Rock 8723L, manufactured by Kyoritsu Chemical Industry]. At this time, the needle inner diameter is 0.41 mm, the coating pressure is 240 Pa, the coating speed is 10 mm / sec, and the gap between the needle tip and the sealing plate is 20 μm. Next, the sealing plate is moved to the hermetic work chamber 27 where pressure can be reduced.

Here, the organic EL element substrate and the sealing plate were aligned in a reduced pressure state in a nitrogen environment having a moisture concentration of 10 PPM, and two sheets were bonded together. Further, at the same position, the surface of the organic EL element was covered with a light-shielding mask, and the surface of the sealing plate was irradiated with UV light [ORAND HANDY UV500] at an illuminance of 80 mW / cm ² for 5 minutes to cure the material of the sealant. The organic EL element panel is taken out from the panel discharge port 34. Thus, an organic EL element panel was prepared.

(Comparative Example 1)
An organic EL element substrate was prepared in the same process as in this example. The sealing plate was subjected to a vacuum treatment using a separate apparatus after a cleaning process using a separate apparatus. Thereafter, the air was once leaked, transported to the air, and then introduced into the organic EL manufacturing apparatus. In all other cases, a moisture atmosphere management with a moisture concentration of 10 PPM was performed in the same manner as in this example, and an organic EL element panel was prepared.

(Comparative Example 2)
An organic EL element substrate was prepared in the same process as in this example. The sealing plate was put into an organic EL manufacturing apparatus after washing with a separate device, but the etched surface of the sealing plate was UV / O ₃ washed without vacuum dehydration. In all other cases, a moisture atmosphere management with a moisture concentration of 10 PPM was performed in the same manner as in this example, and an organic EL element panel was prepared.

(Comparative Example 3)
An organic EL element substrate was prepared in the same process as in this example. All the sealing plates were processed in the same manner as in this example except that the moisture environment of the organic EL production apparatus was maintained at a moisture concentration of 100 PPM, thereby producing an organic EL element panel.

  The organic EL element panels prepared in this example, Comparative Example 1, Comparative Example 2, and Comparative Example 3 were compared and examined for brightness, lifetime and deterioration rate, and dark spots.

  The luminance of the organic EL device prepared in this example was 150,000 candela, and the lifetime was 5% deterioration at 10,000 hours. Further, dark spots with a diameter of 100 μm or more were not generated.

  The luminance of the organic EL device produced in Comparative Example 1 was 100,000 candela, and the lifetime was 40% after 10,000 hours. In addition, dark spots with a diameter of 100 μm or more were generated.

  The luminance of the organic EL device prepared in Comparative Example 2 was 100,000 candela, and the lifetime was 40% after 10,000 hours. In addition, dark spots with a diameter of 100 μm or more were generated.

  The luminance of the organic EL device produced in Comparative Example 3 was 100,000 candela, and the lifetime was 10% deterioration at 10,000 hours. Further, dark spots with a diameter of 100 μm or more were not generated.

It is a schematic cross section which shows the film | membrane structure of an organic EL element. It is a figure which shows the manufacturing system of the organic EL element by one embodiment. It is a figure which shows the organic electroluminescent manufacturing apparatus by one Example.

Explanation of symbols

1 substrate 2 first electrode (anode)
4 Organic light emitting layer 6 Second electrode (cathode)
7 Sealing plate 8 Sealing agent 10 Organic EL layer 11, 12, 14, 15, 16, 17 Airtight working chamber 13 Vacuum chamber

Claims (5)

Preparing an organic EL element substrate having an organic EL layer disposed between a pair of electrodes;
A step of dehydrating a sealing plate for sealing the organic EL element substrate;
Bonding the dehydrated sealing plate to the organic EL element substrate, and maintaining the sealing plate from dehydration to bonding in an airtight atmosphere with controlled moisture concentration Manufacturing method of EL element.   2. The method of manufacturing an organic EL element according to claim 1, wherein the sealing plate is dehydrated by vacuum drying.   3. The method of manufacturing an organic EL element according to claim 1, wherein the moisture concentration of the airtight atmosphere is controlled by nitrogen or dry air.   The method for producing an organic EL element according to any one of claims 1 to 3, wherein the moisture concentration in the airtight atmosphere is controlled to 10 ppm or less.   An apparatus for forming an organic EL element substrate having an organic EL layer disposed between a pair of electrodes, a dehydration treatment chamber for dehydrating a sealing plate for sealing the organic EL element substrate, and the sealing A bonding chamber that performs a bonding process between the stop plate and the organic EL element substrate; and an intermediate processing chamber that is interposed between the dehydration processing chamber and the bonding chamber. An organic EL element manufacturing system, wherein the bonding chamber has an airtight atmosphere in which the moisture concentration is controlled.

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