JPWO2007029586A1 - Method for manufacturing organic electroluminescence element - Google Patents

Abstract

An object of the present invention is to provide a method for manufacturing an organic EL element in which the manufacturing load at the time of forming a protective film is reduced without reducing the protection resistance against moisture and oxygen. The present invention relates to a method of manufacturing an organic electroluminescent element in which a protective film is formed on an organic electroluminescent element formed on a substrate, and the step of forming the protective film forms the first protective film in a vacuum environment. The step (103) and the step (104) of forming the second protective film under an atmospheric pressure environment are included.

Description

  The present invention relates to a method for manufacturing an organic EL element in which a protective film is formed on an organic electroluminescence (EL) element.

  In recent years, organic EL elements have attracted attention as self-luminous elements. An organic EL element is an element that emits light by supplying a current between electrodes, in which a light emitting layer made of a thin film of an organic compound is sandwiched between electrodes on a substrate such as glass.

  Since organic EL elements are easily deteriorated by oxygen and moisture and their presence shortens the product life, immediately after forming the organic EL element from the viewpoint of reliability, as a protective film (also referred to as a barrier film), It is desirable to cover it with a stable protective film against oxygen and water to completely block it from the outside air. Examples of the protective film include a metal nitride film and an oxide film. In the case of a so-called top emission configuration in which light emitted from the organic EL element is extracted in the direction of transmitting from the protective film, a protective film with high transparency is required.

  On the other hand, the protective film is formed using a thin film manufacturing method such as an electron beam method, a sputtering method, a plasma CVD method, or an ion plating method. These thin film manufacturing methods can form a film relatively easily even with a high melting point material in a vacuum environment.

  As a conventional protective film forming technique, a technique using a facing target type sputtering apparatus is disclosed (for example, refer to Patent Document 1). However, in these conventional thin film forming methods, the protective film has a single layer structure, so that the effect on moisture permeation in a high-temperature and high-humidity environment is insufficient, and protrusions on the surface of the organic EL element For example, cracks were likely to occur in the protective film at the same level difference, and the resistance to moisture and oxygen was insufficient.

  In view of this, a technique for laminating a plurality of inorganic protective films sandwiching a thermosetting resin to form a protective film is disclosed (for example, see Patent Document 2). By laminating the protective film, resistance to moisture and oxygen is improved, and generation of cracks due to steps is reduced by the thermosetting resin.

  However, in this protective film configuration, a plurality of protective films must be formed in a vacuum environment in the manufacturing process, which may increase the cost of the manufacturing apparatus as compared to a single-layer protective film forming process. It was an issue.

  On the other hand, as a protective film, a technique is disclosed in which a sheet-like sealing member in which a protective film is formed on an organic EL element is bonded (see, for example, Patent Document 3).

However, it is difficult to realize the working environment of the technique for holding the organic EL element by vacuum suction and the technique for applying the resin material by the syringe in a vacuum environment. For this reason, the deterioration by the water | moisture content or oxygen of the organic EL element before the sealing operation in an atmospheric pressure environment has been a problem.
JP 2002-332567 A JP 2004-119138 A JP 2005-4063 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for manufacturing an organic EL element in which a manufacturing load at the time of forming a protective film is reduced without reducing protection resistance against moisture and oxygen. Is to provide.

  The above object of the present invention has been achieved by the following constitution.

  1. In the method of manufacturing an organic electroluminescent element in which a protective film is formed on an organic electroluminescent element formed on a substrate, after the first protective film is formed in a vacuum environment, the second protective film is formed in an atmospheric pressure environment. A method for producing an organic electroluminescence element, comprising forming the organic electroluminescence element.

  2. 2. The method for producing an organic electroluminescent element according to 1 above, wherein the first protective film is formed using any one of an electron beam method, a sputtering method, a plasma CVD method, and an ion plating method.

  3. 3. The method of manufacturing an organic electroluminescent element according to 1 or 2, wherein the first protective film is either silicon nitride oxide or silicon nitride.

  4). The formation of the second protective film is carried out under an atmospheric pressure environment and an environment with a dew point temperature of −10 ° C. or lower. The organic electroluminescent element according to any one of the above items 1 to 3, Production method.

  5). Said 2nd protective film is a resin film, The manufacturing method of the organic electroluminescent element of any one of said 1-4 characterized by the above-mentioned.

  6). 6. The method for producing an organic electroluminescent element according to any one of 1 to 5, wherein a protective film is formed in advance on the resin film.

  7. The organic electroluminescent element according to any one of 1 to 6, wherein an intermediate layer is provided in an atmospheric pressure environment between the first protective film and the second protective film. Manufacturing method.

  According to the present invention, it was possible to provide a method for manufacturing an organic EL element in which the manufacturing load at the time of forming a protective film was reduced without reducing the protection resistance against moisture and oxygen.

1 is a schematic diagram showing a configuration of an organic EL element 10. FIG. It is a block diagram which shows the manufacturing process at the time of protective film formation. It is a schematic diagram of the magnetron sputtering apparatus which forms a 1st protective film. It is a schematic diagram of the laminating apparatus which forms a 2nd protective film. It is a cross-sectional schematic diagram of the organic EL element sealed using the sealing material of the glass material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Organic EL element 11 Board | substrate 12 Anode 13 Organic layer 14 Cathode 20 Vacuum tank 21 Exhaust port 30 Target 31 Cathode 32 Magnet 50 Power supply 50a Matching unit 51 Pasting means 52 Laminating means 53 Cutting means 54 Curing means 55 Sealing film 60 Conveying means 100 Magnetron sputtering equipment 200 Laminating equipment

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  Hereinafter, an example showing an embodiment of the present invention will be described with reference to the drawings.

  First, the organic EL element will be described below.

  FIG. 1 is a schematic diagram showing the configuration of the organic EL element 10.

  In the figure, an organic EL element 10 is an element in which an anode 12, an organic layer 13, and a cathode 14 are laminated on a substrate 11.

  The anode 12 is a transparent electrode made of a conductive material having a work function of 4 eV or more and a transmittance of 40% or more, such as indium tin oxide (ITO), indium zinc oxide (IZO), gold, tin oxide, and zinc oxide.

  The organic layer 13 is composed of a single layer or a plurality of layers containing an organic compound or complex of several nm to several μm including the light emitting layer. For example, typically, an element composed of three layers, such as a hole transport layer in contact with the anode, a light emitting layer containing a light emitting material, and an electron transport layer in contact with the cathode, a lithium fluoride layer, an inorganic metal salt layer, or A layer containing them may be arranged at an arbitrary position.

  The cathode 14 is a reflective electrode made of a metal material having a work function of less than 4 eV and a reflectance of 60% or more, such as aluminum, sodium, lithium, magnesium, silver, and calcium.

  The substrate 11 may be a substrate for a solid substrate such as glass or quartz, or polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetherether. It is a base material for flexible substrates such as ketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), cellulose triacetate (TAC), and cellulose acetate propionate (CAP).

  The organic EL element 10 according to the present invention emits light using the excitation energy generated by the combination of electrons and holes in the organic layer 13 by an electric current supplied from the outside through the anode 12 and the cathode 14. In the device, the light from the organic layer 13 is in this case extracted through the anode 12. Examples of light emission that uses excitation energy include fluorescence that uses singlet excitation energy for light emission, or phosphorescence that uses triplet excitation energy for light emission.

  In particular, phosphorescence is desirable light emission as a light source because triplet excitons contribute to light emission, and thus higher light emission efficiency can be obtained than fluorescence.

  Light emitted from the light emitting layer of the organic EL element 10 is emitted through the anode 12 and the substrate 11 (referred to as bottom emission), but is substantially transparent in which a thin film cathode material and a highly transmissive anode material are laminated. You may make it the structure of the top emission which inject | emits light from a cathode.

  Next, a manufacturing process when forming a protective film on these organic EL elements will be described.

  FIG. 2 is a block diagram showing a manufacturing process when forming the protective film.

  In the manufacturing method of the organic EL element of the present invention, the organic EL element is formed in a vacuum environment in the organic EL element forming process 102 from the substrate cleaned in the cleaning process 101. In the protective film forming step 103, the first protective film is formed in the same vacuum environment. Thereafter, the process proceeds to the second protective film forming step 104 from the vacuum environment, and the second protective film is formed under the atmospheric pressure environment.

  Details of each manufacturing process will be described below.

  In the cleaning step 101, the substrate on which the anode has been patterned in advance is wet-cleaned by ultrasonic waves using various cleaning liquids and rinsing agents, and dry cleaning is performed by UV irradiation, oxygen plasma cleaning under a predetermined pressure, and the like. It is a process. The substrate may be an active type in which TFTs are arranged in a matrix in advance, or a passive type having only a wiring matrix.

The cleaned substrate is then transferred to the organic EL element forming step 102. Here, in a vacuum environment having a pressure of 10 ⁻³ Pa or less, an organic layer and a cathode are laminated on the anode of the substrate by vapor deposition to form an organic EL element.

The substrate on which the organic EL element is formed is transported to the first protective film forming step 103, and in a vacuum environment having a pressure of 10 ⁻¹ Pa or less, a known electron beam method, sputtering method, plasma CVD method, A first protective film is formed so as to cover the organic EL element by a thin film manufacturing method such as an ion plating method.

  The substrate on which the first protective film is formed is transported to the second protective film forming step 104. The second protective film forming step is managed in a dry environment having a dew point temperature of −10 ° C. or lower in addition to an atmospheric pressure environment of approximately several tens of thousands Pa to several tens of thousands Pa from the above vacuum environment. The lower limit of the dew point temperature according to the invention is preferably −30 ° C.

  Since the first protective film is already used as a protective film, sufficient protection resistance against moisture is ensured in this dry environment, and the environment in which the second protective film is formed by the second protective film forming step 104 is ensured. There is no need for a vacuum environment.

  Next, the protection formation apparatus in the organic EL manufacturing method of the present invention will be described below.

  In the first protective film forming step of the present invention, any one of an electron beam method, a sputtering method, a plasma CVD method, and an ion plating method is used as a protective film forming method for forming the first protective film.

  Any of these methods is a method capable of forming a thin film under vacuum, and if these methods are used, an organic EL element formed by a vacuum deposition method is used in a vacuum environment with little influence of water or oxygen ( A protective film can be formed under a reduced pressure environment.

  For example, in the electron beam method (vacuum deposition method), under vacuum, a material to be formed with a thin film is irradiated with an electron beam, heated and evaporated, and the evaporated material is attached (deposited) on a substrate to form a thin film. It is a manufacturing method. The film formation speed is high and the damage to the substrate is small.

  The plasma CVD method uses RF high frequency (for example, 13.56 MHz) to excite a gas material introduced into a certain vacuum environment, generate plasma, and form a thin film purified by reaction and decomposition of the material molecules on the substrate. In this method, components are deposited to form a thin film.

  The ion plating method is a method for producing a thin film by evaporating a material to be formed into a thin film, ionizing the material by radio frequency (RF), and depositing the material on a substrate.

  In the sputtering method, the material (target material) to be formed into a thin film is collided with plasma, ions, or the like generated by plasma discharge, so that the material is splashed (sputtering). This splashed material is deposited on a substrate to produce a thin film.

  Compared to the plasma CVD method, ion plating method, etc., which require introduction of the raw materials necessary for thin film formation as a gas component, and compared to the electron beam method, the sputtering method has less restrictions on the target material and has a high melting point. Of these, sputtering is a particularly preferable method in the present invention because a thin film can be formed relatively easily using a material.

  Hereinafter, a magnetron sputtering apparatus will be described as the first protective film forming step 103.

  FIG. 3 is a schematic diagram of a sputtering apparatus for forming the first protective film.

  The magnetron sputtering apparatus 100 includes a vacuum chamber 20, an exhaust port 21, a target 30, a cathode 31, a magnet 32, a substrate 11, a power source 500, a matching unit 510, and the like.

  The vacuum tank 20 is a tank that provides a decompression space that is blocked from outside air, and the inside of the tank is decompressed by a vacuum pump (not shown) connected to the exhaust port 21.

  The target 30 is the same material as the constituent material of the protective film formed on the organic EL element or the same material as the constituent material by reaction with the sputtering gas. The protective film is a film including at least one kind of metal oxide film, nitride film, metal thin film, and diamond-like carbon film, and is a thin film having a thickness of 50 nm to 50 μm.

  The target 30 is connected to the cathode 31. When a voltage is applied from the power source 50 via the cathode 31 and the sputtering gas is introduced from the gas supply port 33, the target 30 is in a vacuum or a reduced pressure environment at a predetermined gas pressure. Plasma is generated in the space inside the target 30 to perform sputtering.

  The magnet 32 is, for example, a permanent magnet such as a Fe-Nd-B or Sm-Co rare earth sintered magnet, a Ba or Sr ferrite sintered magnet, a bond magnet such as a ferrite magnet, or a cast magnet such as an alnico magnet. The magnetic field generating means for generating a predetermined magnetic field such as an electromagnet. The magnet 32 may be disposed at a position where a predetermined magnetic field is generated in the plasma generation space. However, as shown in the drawing, the structure disposed on the surface opposite to the inner surface of the target 30 where sputtering is performed has This is a preferable configuration from the viewpoint of storage efficiency in the vacuum chamber 20.

  Further, a cooling means (not shown) may be provided so as to be in contact with the magnet 32 so that the magnet 32 is heated to a high temperature due to sputtering and the magnetic force is reduced.

  The substrate 11 is a substrate on which the target 30 is sputtered and a protective film is formed thereon, and is a substrate such as the organic EL element 10 described above. In order to improve the uniformity of the film thickness distribution of the protective film, it is preferable to rotate the substrate 11 during sputtering by the rotation support member 42. However, the substrate 11 is not limited to the substrate rotation, and the substrate 11 is fixedly supported without rotating. May be.

  The power source 50 is a power source for applying a voltage to the target 30 and generates a direct current, an alternating current, or an alternating current to which a direct current bias is applied depending on the conductivity of the material. When an AC voltage is applied, impedance matching with the target 30 is performed by the matching unit 50a.

  The matching unit is normally used as a set when using a high frequency power source for plasma in an RF magnetron sputtering apparatus that applies an alternating voltage, and a chamber that is a place where the high frequency power output from the high frequency power source for plasma is generated. It is a device for sending in efficiently.

  Next, the apparatus of the second protective film forming step 104 will be described below.

  FIG. 4 is a schematic view of a laminating apparatus for forming a second protective film.

  The laminating apparatus 200 includes a conveying unit 50, an attaching unit 51, a laminating unit 52, a cutting unit 53, a curing unit 54, a sealing film 55, and the like.

  The transport means 50 is a transport means for forming a second protective film on the organic EL element 10 on which the first protective film is formed by the first protective film forming means, using a laminating apparatus. Here, although the sheet | seat organic EL element is conveyed by the conveyor, you may convey the board | substrate wound by the film-like continuous roll with a roller.

  The affixing means 51 is a means for affixing an adhesive layer for forming a second protective film on the organic EL element. In FIG. 4, the affixing means 51 is applied to the first protective film of the organic EL element 10 with a syringe and is irradiated with ultraviolet rays. A hardened adhesive is applied.

  As the sealing film, a flexible thin resin film such as polyethylene terephthalate, polyethylene naphthalate, polycarbonate, ethylene polyvinyl alcohol, ethylene vinyl acetate, ETFE or the like is used. A laminated film may also be used.

  Moreover, as an adhesive agent, ultraviolet curable resin, such as an epoxy type, an acrylic type, an acrylic urethane type, can be used, for example. Further, a thermosetting resin may be used. Application | coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print it like screen printing.

  Moreover, not only this but an adhesive sheet as disclosed by Unexamined-Japanese-Patent No. 2004-139777 may be affixed on a sealing film.

  The laminating means 52 is a means for laminating the sealing film 55 fed from the long roller to the organic EL element 10. In the figure, the sealing film 55 is laminated on the organic EL element 10 by pressing and heating the upper and lower rollers.

  The cutting unit 53 is a unit that cuts excess portions of the sealing film 55 laminated on the organic EL element 10. In the figure, the sealing film is cut along the edge of the organic EL element 10 by a cutter. The cutting means is not limited to a cutter, and a small amount of cutting waste is good if a circular rotating cutter with vibration is used.

  The curing unit 54 is a unit that cures the adhesive layer pasted by the pasting unit 51. FIG. 4 shows an example in which an ultraviolet curable resin is used as the adhesive layer, which is irradiated with a UV light source and cured by a photoreaction.

  In the manufacturing method of the present invention, since the first protective film is formed in advance, damage to the organic EL element due to moisture and oxygen is reduced in the step of forming the second protective film. The work environment does not need to be in a vacuum environment.

  Therefore, the apparatus in the second protective film forming step for forming the second protective film does not need to be vacuum-compatible, and the cost of the manufacturing apparatus is reduced. In addition, the process of forming the second protective film can be performed in a vacuum environment because, for example, repair work for a wrinkle failure that occurred in the bonding process and maintenance work such as replacement of a cutter used in the cutting process can be performed under an atmospheric pressure environment. Compared with the case where the work is performed by returning to the atmospheric pressure environment from the bottom, the work efficiency can be improved and the process stop time can be shortened.

  Next, the present invention will be described more specifically, but the present invention is not limited to these.

  Specific conditions for forming the protective film will be described below.

Example 1
First, as an example of a method for producing an organic EL element, production of an organic EL element composed of an anode / hole transport layer / light emitting layer / cathode will be described.

<< Preparation of the organic EL element 1 >>: The present invention A cleaned glass 100 mm square substrate is placed in a vapor deposition vacuum chamber maintained in a vacuum environment having a vacuum degree of 10 ^-5 Pa. In an evaporation vacuum chamber, an anode was prepared by forming ITO, which is an anode material, by an electron beam method so as to have a thickness of 1000 mm. Next, α-NPD, which is an organic EL element material, was vapor-deposited at a rate of 2 liters / second as a hole transporting layer to a thickness of 500 liters. Next, Alq ₃ was deposited as a light emitting layer at a rate of 2 liters / second to form a thickness of 600 liters. After these layers were formed, the cathode material was formed by vapor-depositing aluminum, which is a cathode material, at a rate of 3 liters / second so as to have a film thickness of 2000 liters.

  Next, the produced organic EL element 1 was transported to a sputtering apparatus which is a first protective film forming step in order to form a first protective film while maintaining a vacuum environment. The sputtering apparatus shown in FIG. 2 was used.

Silicon nitride (Si ₃ N ₄ ) was used as a target material to form a target in a cylindrical shape, and the distance between the upper end of the cylindrical target and the substrate of the organic EL element was set to 7 cm. The gas pressure was 1.33 × 10 ⁻² Pa using argon containing 2% by volume of oxygen as the sputtering gas.

  When the film forming rate was monitored with a crystal resonator when the input power was 100 W with an AC power supply with a frequency of 13.56 MHz, the power supply was 1 振動 子 / sec. Under these conditions, a protective film (also referred to as a barrier film) having a thickness of 5000 mm was formed on the organic EL element 1 to produce the organic EL element 1 having the first protective film.

  Next, the organic EL element 1 having the first protective film is transported from a vacuum environment to a second protective film forming step in a dry air atmospheric pressure environment with a dew point temperature of −10 ° C., and the second protective film is Formed.

  After applying 5516XNR made by Nagase Chemtech as an ultraviolet curable resin on the organic EL element by the laminating apparatus in the second protective film forming step, the sealing film was heated and pressure-bonded by a roller at 100 ° C. and laminated to the EL element. . The sealing film used was a film in which Bridgestone EVA (ethylene vinyl acetate thickness 0.4 mm) and Asahi Glass ETFE (Aflex thickness 25 μm) weathering resin were bonded together.

Then, after cutting off the unnecessary part of the sealing film, the lamination was completed by irradiating with a UV light source until the integrated irradiation energy reached 6000 mJ / cm ² , thereby producing the organic EL element 1 having the second protective film.

<< Preparation of Organic EL Element 1-2 >>: Comparative Example A cleaned glass 100 mm square substrate is placed in a vapor deposition vacuum chamber maintained in a vacuum environment having a vacuum degree of 10 ⁻⁵ Pa. In an evaporation vacuum chamber, an anode was prepared by forming ITO, which is an anode material, by an electron beam method so as to have a thickness of 1000 mm.

Next, α-NPD, which is an organic EL element material, was vapor-deposited at a rate of 2 liters / second as a hole transporting layer to a thickness of 500 liters. Next, Alq ₃ was deposited as a light emitting layer at a rate of 2 liters / second to form a thickness of 600 liters. After these layers were formed, aluminum as a cathode material was deposited thereon at a rate of 3 mm / second to form a cathode so as to have a film thickness of 2000 mm, thereby producing an organic EL device.

  As shown in the schematic cross-sectional view of FIG. 5, the produced organic EL element is covered with a glass material sealing material 15 so that the organic EL material is shielded from the outside air in an atmosphere of dry nitrogen, and bonded with a UV curable resin. A sealing material was adhered to the substrate with the agent 16 and sealed to prepare a comparative sample.

"Evaluation results"
Each of the produced sealed organic EL element samples was driven at a constant current of ^2.5 mA / cm ² , and each sample was evaluated.

  Immediately after the production, the organic EL element 1-1 of the present invention has the same external extraction efficiency and driving voltage as compared with the organic EL element 1-2 of the comparative example, and the organic EL element is formed when the protective film is formed. It shows that there is little damage to.

In addition, the external extraction efficiency was measured using a spectral radiance meter CS-1000 (manufactured by Konica Minolta) when each sample was driven at a constant current of ^2.5 mA / cm ² to emit light. External extraction efficiency (%) was calculated and compared. In addition, the driving voltage was compared when it was driven with a constant current of ^2.5 mA / cm ² .

Further, each of the produced sealed elements was stored for 500 hours under a high-temperature and high-humidity condition of 60 ° C. and 90% RH, and then driven with a constant current of ^2.5 mA / cm ^2. The efficiency and driving voltage and the number of non-light emitting points (dark spots) that can be visually confirmed in the range of 2 mm × 2 mm square were compared between the samples. The organic EL element 1 of the present invention is an organic material of a comparative example. Even in comparison with the EL element 1-2 (organic EL element sealed with glass), the same storage characteristics were confirmed for external extraction efficiency, drive voltage, and dark spot.

Claims (7)

In the method of manufacturing an organic electroluminescent element in which a protective film is formed on an organic electroluminescent element formed on a substrate, after the first protective film is formed in a vacuum environment, the second protective film is formed in an atmospheric pressure environment. A method for producing an organic electroluminescence element, comprising forming the organic electroluminescence element. The organic electroluminescence device according to claim 1, wherein the first protective film is formed by any one of an electron beam method, a sputtering method, a plasma CVD method, and an ion plating method. Method. 3. The method of manufacturing an organic electroluminescence element according to claim 1, wherein the first protective film is either silicon nitride oxide or silicon nitride. The formation of the second protective film is carried out under an atmospheric pressure environment and an environment with a dew point temperature of -10 ° C or lower. The manufacturing method of the organic electroluminescent element of description. The method of manufacturing an organic electroluminescence element according to any one of claims 1 to 4, wherein the second protective film is a resin film. The method for producing an organic electroluminescence element according to any one of claims 1 to 5, wherein a protective film is formed in advance on the resin film. The intermediate layer is provided in an atmospheric pressure environment between the first protective film and the second protective film, and any one of claims 1 to 6 The manufacturing method of the organic electroluminescent element of 1 item | term.