JP5620217B2 - Manufacturing method of organic EL device - Google Patents

Description

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

  In recent years, organic EL devices have attracted attention as a lighting device that can replace incandescent lamps and fluorescent lamps, and many studies have been made. In addition, an organic EL method is attracting attention as a method for changing to a liquid crystal method or a plasma method in a display member typified by a television.

Here, the organic EL device is obtained by laminating an organic EL element on a base material such as a glass substrate or a transparent resin film.
In addition, the organic EL element has two or more light-transmitting electrodes facing each other, and a light emitting layer made of an organic compound is laminated between the electrodes. The organic EL device emits light by the energy of recombination of electrically excited electrons and holes.
Since the organic EL device is a self-luminous device, a high-contrast image can be obtained when used as a display material. In addition, light of various wavelengths can be emitted by appropriately selecting the material of the light emitting layer. Further, since the thickness is extremely thin compared to incandescent lamps and fluorescent lamps, and the light is emitted in a planar shape, there are few restrictions on the installation location.

A typical layer structure of the organic EL device is as shown in FIG. The organic EL device 200 shown in FIG. 5 has a configuration called a bottom emission type. A transparent electrode layer 202, a functional layer 203, and a back electrode layer 205 are laminated on a substrate 201, and these are sealed portions. It is sealed with 206. (For example, Patent Document 1)
The functional layer 203 is formed by laminating a plurality of thin films of organic compounds. The functional layer 203 is usually formed with a very thin film thickness of several hundred nm.

  A typical functional layer 203 has a layer structure as shown in FIG. 6, and includes a hole injection layer 210, a hole transport layer 211, a light emitting layer 212, and an electron transport layer 213. Further, an electron injection layer is inserted between the electron transport layer 213 and the back electrode layer 205 as necessary.

  That is, light emitted from the light emitting layer is emitted through the laminated structure constituting the organic EL device, and functions as a self light emitting device.

JP 2004-363034 A

  However, the functional layer is an extremely thin thin film as described above, and it is necessary to withstand the electric field applied to the positive and negative electrodes with the thin film thickness. If the number is large, a short circuit occurs, and the element itself does not emit light, resulting in a decrease in yield. As such a defect, for example, there is a portion where the film thickness in the functional layer is thin due to steep unevenness generated in some cases in the transparent electrode layer, and the electric field is locally concentrated to cause a short circuit. Also, for example, discontinuous points of the back electrode layer and local non-uniformities of the organic layer itself that may occur when the back electrode layer is formed with dust attached to the surface of the organic layer It is thought to constitute a defect.

  Therefore, the present invention solves the above-described problems, and an object of the present invention is to develop an organic EL device having a high yield and excellent visibility.

As a result of various studies to solve the above problems, the present inventor has found that the yield can be improved by forming a dark spot that satisfies a predetermined condition in a region that should emit light when energized. Tried.
Here, the dark spot is a non-light emitting point generated due to moisture or oxygen when sealing is insufficient, for example. When the generated dark spot grows and expands, it adversely affects the durability and quality of the organic EL device. In general, a sufficiently sealed element is not affected by moisture or oxygen, so that no dark spot is generated. However, when the element is lit in a state exposed to moisture or oxygen, an oxide is formed on the back electrode. Since the portion where the oxide is formed is partially insulated, it is considered that when the element is energized, the corresponding portion does not emit light, that is, becomes a dark spot.

The dark spot immediately after lighting is a size that cannot be seen with the naked eye, but if the lighting continues further, it grows with this as the core. Further, the dark spot is generated even in a storage state where no lighting is performed, and grows with time.
Moreover, in order to ship the organic EL device as a product, good visibility is required. When a dark spot exceeding the reference is generated at the time of shipment in a stable state that is lit for a certain period of time, the visibility deteriorates, so that the product is treated as a defective product, that is, the yield is reduced.

Thus, the dark spot has been conventionally recognized as degrading the quality of the element, and it has been considered that suppressing the generation as much as possible is an important problem of the organic EL device.
However, the inventor previously formed a dark spot due to the formation of oxide in a region that should emit light when energized, and made the current leak location an insulator, thereby preventing the occurrence of a short circuit due to the above-described defects. I found out that it can be prevented. In other words, the metal layer used for the back electrode has a considerable moisture and oxygen blocking effect, but the current leak location is a discontinuous point on the back electrode due to steep irregularities or dust generated in the transparent electrode layer. Therefore, it was considered that dark spots are likely to occur due to intrusion of moisture and oxygen from there, and therefore, it was found that the occurrence of a short circuit can be prevented by preferentially insulating the electrode leak portion. It was also found that dark spot growth can be suppressed by sealing after dark spot formation. Furthermore, if dark spots are formed based on this method, the appearance may be poor in some cases. However, as a result of further improvements and extensive studies, the present inventor has made light on the surface of the substrate. It was invented to provide a scattering layer that scatters.

In the organic EL device in which at least the first electrode layer having translucency, the organic light emitting layer, and the second electrode layer are laminated on the base material, the invention thus derived is a region that should emit light when energized. In the organic EL device, a dark spot satisfying all of the following conditions (1) to (3) is formed, and a scattering layer for scattering light is provided on the surface of the substrate. is there.
(1) There is no dark spot having a diameter of 1 mm or more.
(2) There are one or more dark spots having a diameter of 50 μm or more per square centimeter.
(3) There are 5 or more dark spots with a diameter of 20 μm or more per square centimeter.

According to such a configuration, since a predetermined dark spot is already formed in a region to emit light when energized, it is possible to prevent occurrence of a short circuit due to the above-described defect, and it is also possible to suppress the growth of the dark spot. Yield is improved.
Moreover, since the scattering layer which scatters light is provided in the surface of a base material, luminous efficiency can be improved. In addition, poor visual appearance due to dark spots can be improved.

A preferred embodiment is the above-described organic EL device, in which a dark spot that satisfies the following condition (4) is formed in the region that should emit light when energized.
(4) There are a plurality of dark spots having a diameter of 50 μm or more, and the distance between the centers of the two dark spots closest to each other is 2 mm or more.

  According to this configuration, it is possible to sufficiently improve the poor appearance due to the dark spot.

  In a preferred embodiment, the scattering layer is a sheet, and the scattering layer is formed by providing the sheet on the surface of a substrate.

  According to this configuration, since the scattering layer is a sheet, it is easy to design the scattering layer.

  A preferred embodiment is characterized in that a scattering layer is formed by forming irregularities on the surface of the substrate.

  According to this structure, since the unevenness | corrugation is formed in the surface of a base material and the scattering layer is formed, another new material is not required and it leads to cost reduction.

The invention according to claim 1 includes a laminate in which at least a first electrode layer having translucency, an organic light emitting layer, and a second electrode layer are laminated on a substrate, and the laminate is sealed. In a method of manufacturing an organic EL device sealed with a member, a step of forming a scattering layer that scatters light on the surface of a substrate, and a dark spot when energized before sealing the laminate with a sealing member Having a step of forming a defective portion,
In the step of forming the defect portion, the stacked body is placed in an environment of a predetermined condition until a dark spot that satisfies all of the following conditions (1) to (3) is formed. This is a method for manufacturing an organic EL device.
(1) There is no dark spot having a diameter of 1 mm or more.
(2) There are one or more dark spots having a diameter of 50 μm or more per square centimeter.
(3) There are 5 or more dark spots with a diameter of 20 μm or more per square centimeter.

  According to this configuration, the organic EL device can be efficiently manufactured.

The invention according to claim 2 is characterized in that, in the step of forming the defect portion, the dark spot to be formed is further adjusted so as to satisfy the following condition (4). This is a method for manufacturing an EL device.
(4) There are a plurality of dark spots having a diameter of 50 μm or more, and the distance between the centers of the two dark spots closest to each other is 2 mm or more.

According to a third aspect of the present invention, in the step of forming a defect portion that becomes a dark spot when energized, the predetermined condition is performed by at least one of the following methods. This is a method for manufacturing the organic EL device.
(1) Exposing the laminate to an atmosphere of water vapor.
(2) A liquid is sprayed on the laminate.
(3) The laminate is immersed in a liquid.
(4) Exposing the laminate to an aerobic atmosphere.
(5) Exposing the laminate to an active gas atmosphere.
(6) The laminate is exposed to the atmosphere.

  According to this configuration, it becomes easy to form a defective portion that becomes a dark spot when energized.

  The invention according to claim 4 is the method for manufacturing an organic EL device according to any one of claims 1 to 3, wherein a scattering layer is formed by providing a sheet on the surface of the substrate.

  The invention according to claim 5 is the method for producing an organic EL device according to any one of claims 1 to 3, wherein the scattering layer is formed by forming irregularities on the surface of the substrate.

  In a preferred embodiment, the step of forming a defect portion that becomes a dark spot when energized is performed under energization of the laminate.

  According to such a configuration, since a defective portion is formed under energization, light emission can be confirmed at the same time. That is, the work process can be shortened.

  According to the present invention, an organic EL device having a high yield and excellent visibility can be provided.

1 is a cross-sectional view of an organic EL device according to a first embodiment of the present invention. It is a cross-sectional perspective view of the laminated body of FIG. It is sectional drawing of the organic electroluminescent apparatus of 2nd Embodiment of this invention. It is a cross-sectional perspective view of the laminated body of FIG. It is sectional drawing which shows the typical layer structure of an organic electroluminescent apparatus. It is sectional drawing which shows the typical layer structure of an organic EL element.

  The present invention relates to an organic EL device and a method for manufacturing the organic EL device. FIG. 1 shows an organic EL device 1 according to the first embodiment of the present invention.

  As shown in FIGS. 1 and 2, the organic EL device 1 includes a first electrode layer 3, a functional layer 5, and a second electrode layer 6 stacked in this order on one surface of a substrate 2 (base material). These are sealed by a sealing member 8. A scattering layer 7 is provided on the other surface of the substrate 2. That is, the scattering layer 7 is disposed on the light extraction side. In addition, the thing except the sealing member 8 among the organic EL apparatuses 1 is represented by the laminated body 11 (organic EL element).

  Further, the organic EL element of the present invention is preferably an integrated organic EL element. In this case, as shown in FIG. 2, the first electrode layer 3 is partially removed from the first electrode layer 3 as shown in FIG. An electrode layer separation groove 15 is provided. The functional layer 5 is provided with a functional layer separation groove 16 from which the functional layer 5 has been partially removed. Both the second electrode layer 6 and the functional layer 5 are provided with unit light emitting element separation grooves 17 in which both the second electrode layer 6 and the functional layer 5 are partially removed.

  The material of the substrate 2 is not particularly limited, and is appropriately selected from, for example, a flexible film substrate or a plastic substrate. In particular, a glass substrate or a transparent film substrate is preferable in terms of transparency and good workability.

  Examples of the film substrate include thermoplastic resins and thermosetting resins. As the thermoplastic resin, acrylic resin, polyester, polycarbonate resin, polyolefin, cycloolefin polymer (COP) or the like can be used, and as the thermosetting resin, polyurethane or the like can be used. Among these, a substrate mainly composed of a cycloolefin polymer (COP) having excellent optical isotropy and water vapor blocking properties is particularly preferable.

  Examples of cycloolefin polymers (COP) include norbornene polymers, copolymers of norbornene and olefins, and polymers of unsaturated alicyclic hydrocarbons such as cyclopentadiene. In particular, from the viewpoint of water vapor barrier properties, it is preferable that the main chain and side chain of the constituent molecules do not contain a functional group having a large polarity. That is, it is preferable that the main chain and the side chain of the constituent molecules do not contain a carbonyl group or a hydroxyl group.

  The thickness of the film substrate is preferably about 0.03 mm to 3.0 mm. This thickness range is preferable from the viewpoint of the strength against bending and scratching of the substrate in addition to the ease of handling of the substrate and the weight at the time of device fabrication. In addition, polyethylene naphthalate (PEN) and polyethersulfone (PES) are also suitable from the viewpoint of excellent heat resistance.

The material of the first electrode layer 3 is not particularly limited. For example, a metal such as indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO ₂ ), or zinc oxide (ZnO) is used. An oxide or a metal such as silver (Ag) or chromium (Cr) is employed. In terms of being able to effectively extract light generated from the light emitting layer in the functional layer 5, ITO or IZO having high transparency can be used particularly preferably.

  The functional layer 5 is a layer provided between the first electrode layer 3 and the second electrode layer 6 and having at least one light emitting layer. The functional layer 5 is composed of a plurality of layers mainly made of organic compounds. The functional layer 5 can be formed of a known material such as a low molecular dye material or a conjugated polymer material used in a general organic EL device. The functional layer may have a multilayer structure including a plurality of layers such as a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer.

In particular, when such a multilayer multilayer structure is adopted, an alkali metal or an alkali such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF ₂ ), etc. is used for the electron injection layer in the functional layer. It is preferable to employ an earth metal compound or the like and laminate the electron injection layer in the functional layer 5 so as to be adjacent to the second electrode layer 6. With this electron injection layer, various conductive materials such as aluminum (Al), silver (Ag), ITO, ITO containing silicon, etc. can be used regardless of the work function between the second electrode layer 6 and the electron injection layer. It can be used as the two-electrode layer 6.

  Moreover, you may add the several dopant which shows different light emission to the light emitting layer of the functional layer 5. FIG. Moreover, you may add a dopant to layers other than a light emitting layer, for example, an electron carrying layer, a hole transport layer, etc.

  The method for forming each layer constituting the functional layer 5 is not particularly limited, and is a vacuum deposition method, a sputtering method, a CVD method, a dipping method, a roll coating method (printing method), a spin coating method, a barcode method, a spray method. The film can be formed by a known method such as a die coating method or a flow coating method. At this time, each layer may be formed by the same film formation method, or may be formed by different film formation methods.

  The material of the second electrode layer 6 is not particularly limited, but aluminum (Al) and silver (Ag) are preferable. For example, a metal, an alloy, or an electric conduction having a small work function of 3.8 eV or less. Compounds, mixtures thereof, and the like can also be used. Specifically, elements belonging to Group I or Group II of the periodic table and their alloys can be used. Specifically, alkali metals such as lithium (Li) and cesium (Cs), alkaline earth metals such as magnesium (Mg), calcium (Ca), and strontium (Sr), and alloys containing them (Mg : Ag, Al: Li) can be employed.

  By using the second electrode layer 6 having a work function in the range of 3.8 eV or less, it is possible to increase the electron injection property into the functional layer 5.

The material of the sealing member 8 is not particularly limited. For example, glass, metal, polyester such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate , Cellulose acetate butyrate, cellulose acetate propionate (CAP), cellulose acetate phthalate (TAC), cellulose esters such as cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene , Polycarbonate, norbornene resin, polymethylpentene, polyetherketone, polyimide, polyethersulfone (PES), Rephenylene sulfide, polysulfones, polyether imide, polyether ketone imide, polyamide, fluororesin, nylon, polymethyl methacrylate, acrylic or polyarylates, cycloolefin resin, aluminum on metal foil and resin film such as aluminum and stainless steel A film in which a metal film of copper, nickel, stainless steel or the like is laminated can be used.
Further, a moisture absorbing material or an oxygen absorbing material may be provided on the element side of the sealing member 8, or may be blended in the sealing member itself. By adapting the configuration in which the moisture absorbing material and oxygen absorbing material are provided, it becomes possible to remove moisture and oxygen that are no longer necessary in the dark spot formation / growth process, which will be described later. Figured. As such an absorbent, for example, barium oxide (BaO), calcium oxide (CaO), alkali metal, alkaline earth metal, or active iron oxide fine powder can be used.

  When the eyes are moved to the scattering layer 7, as shown in FIG. 1, the scattering layer 7 has a sheet-like sheet portion 14 and a convex portion 10 in which protrusions are continuously arranged.

  By having the convex portion 10, the total reflection of light generated in the light emitting layer inside the functional layer 5 is reduced, and an effect of improving the light extraction efficiency can be expected by changing the light emission angle.

  Although the structure of the convex part 10 of the scattering layer 7 is not specifically limited, For example, what has a microlens structure, a pyramid structure, a photonic array structure, etc. can be used preferably.

  The convex part 10 is a method of forming a resin by finely patterning it with light and then heating it. It can be produced by a method of taking a mold after curing, a method of cutting a material applied to a substrate by an etching method, or the like.

  Although the height of the convex part 10 does not have a restriction | limiting in particular, It is preferable that they are 1 micrometer-500 micrometers. More preferably, it is the range of 5 micrometers-100 micrometers. The height of the convex portion 10 here refers to the height from the lower surface of the convex portion 10 (the upper surface of the sheet portion 14) to the apex of the convex portion 10.

  By having the convex portion 10 in this range, the total reflection of light can be reduced and the light emission angle can be changed, so that improvement in light extraction efficiency and the like can be expected. In addition, the dark spot when energized is inconspicuous, and the poor appearance due to the dark spot can be improved.

  The material of the scattering layer 7 is not particularly limited as long as it shows transparency at least in the visible light region. For example, it is preferably made of a soft material such as a resin for ease of molding, but is not limited to this, and a hard material such as glass may be used.

  Examples of transparent soft materials include polymethyl methacrylate, polyacrylate, polycarbonate, polyvinyl alcohol, polyvinyl pyrrolidone, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl chloride, melanin resin, phenol resin, alkyd resin, epoxy resin, polyurethane resin, Polyester resin, maleic acid resin, polyamide resin, polyimide amide resin, cyclic polyolefin resin, norbornene resin, 4-methylpentene resin, polysulfone resin, polyethersulfone resin, polyarylate resin, polyethylene terephthalate resin, polyethylene telenaphthalate resin, polypropylene Naphthalate resin, fluorine resin, polyurethane resin, polystyrene resin, polyethylene resin, polypropylene Resins, polyvinyl chloride resins, polyester resins, silicone resins, maleic acid resins. From these materials, the refractive index condition can be selected and used as appropriate.

  The material of the sheet | seat part 14 and the convex part 10 which comprise the scattering layer 7 may be the same, and the thing of a different material may be used. As a combination of these materials, a soft material or a hard material having transparency can be used in combination from the above materials.

  The refractive index of the scattering layer 7 is preferably about the same as the refractive index of the substrate 2.

  In addition, the organic EL device 1 includes a defective portion 12 as shown in FIG. The defect portions 12 are randomly distributed. The defective portion 12 is transparent except when energized.

Next, a method for manufacturing the organic EL device 1 according to this embodiment will be described.
The organic EL device 1 is manufactured using a vacuum vapor deposition device (not shown) and a laser scribing device (not shown).

First, the first electrode layer 3 is formed on the substrate 2.
For the first electrode layer 3, indium tin oxide (ITO), tin oxide (SnO ₂ ), zinc oxide (ZnO), or the like is used. The first electrode layer 3 is formed on the substrate 2 by sputtering or CVD.

  Subsequently, a first laser scribing process is performed as necessary to form the first electrode layer separation groove 15 in the first electrode layer 3.

  The laser scribing device has an XY table, a laser generator, and an optical engagement member. The first laser scribing step is performed by placing the substrate 2 on an XY table and moving the substrate 2 linearly at a constant speed in the vertical direction while irradiating the laser beam. Then, the X / Y table is moved in the horizontal direction to shift the irradiation position of the laser beam, and the substrate 2 is linearly moved again in the vertical direction while irradiating the laser beam.

  The substrate after the first laser scribing process is cleaned on the surface in some cases in order to remove the scattered film. A known cleaning method can be applied as the cleaning method.

  Next, the hole injection layer 12, the hole transport layer 11, the light emitting layer 10, the electron transport layer 8, and the like are sequentially deposited on the substrate to form the functional layer 5.

  Then, a second laser scribing step is performed on the substrate taken out from the vacuum deposition apparatus as necessary, and the functional layer separation groove 16 is formed in the functional layer 5.

  Subsequently, the substrate is inserted into a vacuum deposition apparatus, and the second electrode layer 6 is formed on the functional layer 5.

  Subsequently, a third laser scribing process is performed as necessary to form unit light emitting element isolation grooves 17 in both the second electrode layer 6 and the functional layer 5.

  Further, a power supply electrode (not shown) is formed, a separation groove (not shown) on the outside thereof is formed, and the second electrode layer 6 and the like on the outer portion of the separation groove are removed as necessary.

  And the process (dark spot formation and growth process) of forming the defective part used as a dark spot is performed.

An electric field is applied to the laminated body 11 obtained by the above-described process and energized. And while energizing, the laminated body 11 is installed in the environment of a predetermined condition until the dark spot which satisfies all the conditions of the following (1)-(3) is formed.
(1) There is no dark spot having a diameter of 1 mm or more.
(2) There are one or more dark spots having a diameter of 50 μm or more per square centimeter.
(3) There are 5 or more dark spots with a diameter of 20 μm or more per square centimeter.

At this time, preferably, the dark spot to be formed is adjusted so as to satisfy the following condition (4).
(4) There are a plurality of dark spots having a diameter of 50 μm or more, and the distance between the centers of the two dark spots closest to each other is 2 mm or more.

As specific conditions of the environment in which the stacked body 11 is installed, it is installed under one or more of the following conditions.
(1) Expose the laminate to an atmosphere of water vapor.
(2) A liquid is sprayed on the laminate.
(3) Immerse the laminate in a liquid.
(4) Expose the laminate to an aerobic atmosphere.
(5) Expose the laminate to an active gas atmosphere.
(6) The laminate is exposed to the atmosphere.

When a dark spot with the above conditions is formed, the energization is stopped. As a result, the defect portion 12 is formed at a position corresponding to the dark spot. The dark spot formation / growth step is preferably performed while the laminate 11 is energized in the environment (1) to (6), but the laminate 11 is left in the environment (1) to (6). Thus, a dark spot may be formed.
Then, the sealing operation by the sealing member 8 is performed to complete the organic EL device 1 of the present embodiment.

  Even if the organic EL device 1 formed as described above is lit for a long period of time, an oxide is already formed in the defect portion 12 and the defect portion 12 is an insulator. Occurrence can be prevented, and dark spot expansion can be suppressed by sealing after the dark spot formation / growth process. As a result, the yield is high and the visibility is excellent.

  In the above-described embodiment, the scattering layer 7 is adhered on the substrate 2, but the present invention is not limited to this, and the convex portion 10 may be formed by cutting or deforming the substrate 2. Hereinafter, the second embodiment will be described. In addition, the thing similar to 1st Embodiment attaches the same code | symbol, and abbreviate | omits description.

  As shown in FIGS. 3 and 4, the organic EL device 20 has a structure in which a first electrode layer 3, a functional layer 5, and a second electrode layer 6 are laminated on a substrate 21 in this order. These are sealed by the sealing member 8.

  The substrate 21 is provided with a convex portion 22 on the light extraction side.

  The convex portion 22 of the substrate 21 is formed by performing processing such as cutting on the substrate 2 itself. In the second embodiment, since the substrate 21 has a function as the scattering layer 7, the substrate 21 has both a role as a base material and a role as the scattering layer 7 in the first embodiment.

  It is desirable that the refractive index of the substrate 21 be approximately the same as the refractive index of the first electrode layer 3.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

  A specific example of the present invention and a manufacturing procedure of an organic EL device of a comparative example with respect to the example and evaluation results thereof will be described.

[Comparative Example 1]
As the substrate for forming the organic EL device, a glass substrate on which ITO (indium / tin oxide, film thickness 150 nm) was formed by patterning was used as the first electrode layer. The substrate was washed with a surfactant using a brush, ultrasonically washed with pure water, and then dried in an oven. The substrate was moved to a vacuum deposition apparatus, and the material was deposited in vacuum as follows.

  On the first electrode layer, a mixed layer of 4,4′-bis [N- (2-naphthyl) -N-phenyl-amino] biphenyl (hereinafter abbreviated as NPB) and molybdenum trioxide is used as a hole injection layer. A film having a thickness of 10 nm was formed by vacuum evaporation. NPB and molybdenum trioxide of the hole injection layer were formed by a co-evaporation method so that the film thickness ratio was 9: 1.

  Next, NPB was formed as a hole transport layer with a film thickness of 50 nm (deposition rate: 0.08 nm / sec to 0.12 nm / sec) by a vacuum evaporation method.

  Next, tris (8-quinolinolato) aluminum (hereinafter abbreviated as Alq3) as a light emitting layer / electron transporting layer is formed to a thickness of 70 nm (deposition rate: 0.24 nm / sec to 0.28 nm / sec) by vacuum deposition. A film was formed.

Next, LiF was used as the electron injection layer, and a film having a thickness of 1 nm (deposition rate: 0.03 nm / sec to 0.05 nm / sec) was formed by a vacuum evaporation method.
Finally, Al was deposited as a cathode with a film thickness of 150 nm (deposition rate: 0.3 nm / sec to 0.5 nm / sec) by a vacuum deposition method, and an organic EL laminate having a light emitting region of 18 mm × 18 mm was produced. .

  The organic EL laminate (organic EL element) formed by vacuum deposition as described above was taken out in the atmosphere (temperature: 25 degrees Celsius, humidity: 50%) and allowed to stand for 24 hours.

  Next, the organic EL laminate was moved into a glove box having a sealing mechanism filled with a nitrogen atmosphere. A sealing casing made of a glass plate with the center cut off (in addition, an ultraviolet curable resin is applied as a sealing resin around the sealing casing) is placed on the organic EL laminate. An organic EL device having a sealing structure was manufactured by curing a sealing resin portion by bringing a sealing casing into close contact and irradiating a UV lamp through a mask. This was designated as Comparative Example 1.

[Example 1]
A total reflection reducing film (base film: polyethylene) having a convex hemispherical lens structure having a diameter of 32 μm and a height of 8 μm as a scattering layer 7 on the outer surface of the glass substrate of the organic EL device of Comparative Example 1, that is, on the light extraction side. Using terephthalate (refractive index: 1.57, thickness: 25 μm), lens part: thermoplastic resin (refractive index: 1.58)), formed on substrate 2 via adhesive (refractive index: 1.53) did. This was designated Example 1.

[Comparative Example 2]
In the manufacturing procedure of Comparative Example 1, each material was formed into a film by vacuum vapor deposition and then taken out into the atmosphere and allowed to stand for 3 hours. Other than that, an organic EL device was produced in exactly the same manner as Comparative Example 2.

[Example 2]
In the production procedure of Example 1, each material was deposited by vacuum deposition and then taken out into the atmosphere and allowed to stand for 3 hours. Other than that, an organic EL device was produced in exactly the same manner as Example 2.

[Comparative Example 3]
In the manufacturing procedure of Comparative Example 1, each material was deposited by vacuum deposition and then taken out into the atmosphere and allowed to stand for 20 minutes. Other than that, an organic EL device was produced in exactly the same manner as Comparative Example 3.

[Comparative Example 4]
In the manufacturing procedure of Comparative Example 1, each material was deposited by vacuum deposition and then taken out into the atmosphere, and moved from a vacuum atmosphere to a glove box filled with a nitrogen atmosphere for sealing. Other than that, an organic EL was prepared in exactly the same manner as Comparative Example 4.

[Measurement of current luminous efficiency]
The organic EL devices of Examples 1 and 2 and Comparative Examples 3 and 4 were each driven under a condition of 32.4 mA (10 mA / cm ² ), and current emission efficiency was measured. The measurement results are shown in Table 1.

  In Examples 1 and 2, by providing the scattering layer 7, the luminous efficiency was higher than those of Comparative Examples 1 to 4.

(Visibility measurement)
In each example and each comparative example, the light emission state was visually observed, and the visibility by dark spots was measured. The measurement results are shown in Table 2.

  A large number of dark spots were confirmed in Comparative Examples 1 and 2, and Comparative Examples 3 and 4 showed a good light emission state. The light emission state of each organic EL device was observed using an optical microscope. In Comparative Example 1, many dark spots having a diameter of 500 μm or less were observed. In Comparative Example 2, many dark spots with a diameter of 80 μm or less were observed, but the number of dark spots was smaller than that of Comparative Example 1, and many dark spots with a diameter of 20 μm or more were also observed. Although dark spots were not visually observed in Comparative Example 3, many dark spots having a diameter of 10 μm or less were observed by optical microscope observation. In Comparative Example 4, no dark spot was observed.

Twenty-four organic EL devices of Comparative Examples 1, 2, 3, and 4 were produced, respectively, and driven under the condition of 32.4 mA (10 mA / cm ² ). The results of confirming the state of each light emission after 480 hours are shown in Table 3.

  In Comparative Example 1, two of the 24 organic EL devices did not emit light, and the yield was 93%. In Comparative Example 2, four of the 24 organic EL devices did not emit light, and the yield was 87%. In Comparative Example 3, 8 of the 24 organic EL devices did not emit light, and the yield was 67%. In Comparative Example 4, 20 of the 24 organic EL devices did not emit light, and the yield was 17%.

  Thus, when the yield after driving for 480 hours is compared, the yield increases in the order of Comparative Examples 1, 2, 3, and 4, and the yield increases as the organic EL device becomes larger due to generation and growth of dark spots. It became clear that was seen. This is because a minute short-circuit portion formed by dust or particles in the stack of the organic EL device is oxidized by moisture in the atmosphere and has insulation properties. For this reason, the short circuit part which does not contribute to light emission is electrically self-repaired. In particular, it is considered that a defective portion that cannot be covered by a minute dark spot can be insulated by the dark spot that has grown greatly, and the yield is further improved.

  However, with regard to Comparative Examples 1 and 2 in which the yield is particularly improved, when the organic EL device is caused to emit light, there is a visual problem that a large number of dark spots are visible as black spots.

  That is, the comparative example does not satisfy both high yield and good visibility.

[Comparative Example 5]
An organic EL device was produced in the same manner as in Comparative Example 1 except that the standing time in the atmosphere was 48 hours. As a result of observing the light emission state of the organic EL device using an optical microscope, dark spots having a diameter of 1 mm or more were observed. In this apparatus, a total reflection reducing film was formed as the scattering layer 7 in the same manner as in Example 1, but unlike Example 1 in which the presence of dark spots was not visually confirmed, the appearance that the presence of dark spots could be confirmed through the film. It became a bad device.

Example 3
An organic EL device was produced in the same manner as in Comparative Example 1 except that the cleaning with the brush was shortened to one-fourth the time of Comparative Example 1. As a result of observing the light emission state of the organic EL device using an optical microscope, it was observed that a plurality of dark spots having a diameter of 60 μm or more exist with a center distance of about 1 mm. When a total reflection-reducing film was formed as a scattering layer 7 in this apparatus in the same manner as in Example 1 and observed visually, the appearance was not so bad that the presence of dark spots could be confirmed through the film, but light was emitted through the film. Variations in in-plane brightness were confirmed, resulting in a device with a slightly poor appearance.

1 Organic EL device 2 Substrate (base material)
3 First electrode layer 5 Functional layer (organic light emitting layer)
6 Second electrode layer 7 Scattering layer 10 Convex portion 11 Laminated body 12 Defect portion 20 Organic EL device 21 Substrate (base material)
22 Convex

Claims (6)

An organic EL device comprising a laminate in which at least a first electrode layer having translucency, an organic light emitting layer, and a second electrode layer are laminated on a substrate, and the laminate is sealed with a sealing member. In the method of manufacturing
A step of forming a scattering layer that scatters light on the surface of the substrate, and a step of forming a defect portion that becomes a dark spot during energization before sealing the laminate with a sealing member,
In the step of forming the defect portion, the stacked body is placed in an environment of a predetermined condition until a dark spot that satisfies all of the following conditions (1) to (3) is formed. A method for manufacturing an organic EL device.
(1) There is no dark spot having a diameter of 1 mm or more.
(2) There are one or more dark spots having a diameter of 50 μm or more per square centimeter.
(3) There are 5 or more dark spots with a diameter of 20 μm or more per square centimeter. 2. The method of manufacturing an organic EL device according to claim 1, wherein in the step of forming the defect portion, the dark spot to be formed is further adjusted to satisfy the following condition (4).
(4) There are a plurality of dark spots having a diameter of 50 μm or more, and the distance between the centers of the two dark spots closest to each other is 2 mm or more. 3. The method of manufacturing an organic EL device according to claim 1, wherein the step of forming a defect portion that becomes a dark spot when energized is performed by at least one of the following methods under the predetermined condition .
(1) Exposing the laminate to an atmosphere of water vapor.
(2) A liquid is sprayed on the laminate.
(3) The laminate is immersed in a liquid.
(4) Exposing the laminate to an aerobic atmosphere.
(5) Exposing the laminate to an active gas atmosphere.
(6) The laminate is exposed to the atmosphere.   The method for producing an organic EL device according to claim 1, wherein a sheet is provided on the surface of the base material to form a scattering layer.   The method for producing an organic EL device according to claim 1, wherein the scattering layer is formed by forming irregularities on the surface of the substrate.   The method of manufacturing an organic EL device according to claim 1, wherein the step of forming a defective portion that becomes a dark spot when energized is performed under energization of the laminate.

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