JP2017162718A - Manufacturing method of organic el element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an organic EL element, capable of improving productivity.SOLUTION: A manufacturing method of an organic EL element, comprises: organic EL element formation step S10 of forming an organic EL element by laminating a substrate side electrode, an organic EL part, and an opposite electrode onto a front surface of the substrate in this order; leak inspection step S12 of acquiring a leak current value of the organic EL element; and determination step S14 of comparing the leak current value and a standard value, and determining quality of the organic EL element. The standard value is the leak current value for one predetermined defect source acquired by dividing the leak current value acquired by the leak inspection of the organic EL element for the standard value by a lighting failure source number appeared as a lighting failure defect in a lighting state of the organic EL element for the standard value selected on the basis of a result of a lighting test of the organic EL element for the standard value of at least one defect source in the organic EL element for the standard value formed for calculating the standard value.SELECTED DRAWING: Figure 2

Description

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

  In the manufacturing method of an organic electroluminescence (organic EL) element, usually, after forming the organic EL element, a step of determining the quality of the formed organic EL element is included. As an example of a manufacturing method including such a determination step, a technique described in Patent Document 1 is known. In the technique described in Patent Document 1, a leak current value obtained by applying a reverse bias voltage to a defective organic EL element is used as a standard value for determination in a durability test of the organic EL element. Yes. Specifically, after the organic EL element is formed, the stress application process and the leak inspection process are performed in this order, and the quality of the organic EL element is determined by comparing the standard value with the leak current value obtained by the leak inspection process. ing.

Japanese Patent Laying-Open No. 2005-310659

  In the manufacturing method described in Patent Document 1, since a long time is required in the stress application step because it is necessary to apply a load equivalent to the durability test, the productivity of the organic EL element is lowered.

  Then, an object of this invention is to provide the manufacturing method of the organic EL element which can aim at the improvement of productivity.

  The organic EL device manufacturing method according to one aspect of the present invention includes a first substrate-side electrode, a first organic EL unit including a first light-emitting layer, and a first counter electrode on a surface of a first substrate. Are sequentially stacked, an organic EL element forming step for forming an organic EL element, a leak inspection step for performing a leak inspection on the organic EL element, and acquiring a leak current value of the organic EL element, and A determination step of comparing the leak current value with a standard value to determine the quality of the organic EL element, wherein the standard value is at least in a standard value organic EL element formed for standard value calculation. Among the one defect source, the number of defective lighting sources that appear as defective lighting in the lighting state of the standard value organic EL element selected based on the result of the lighting test of the standard value organic EL element is the standard. Of organic EL elements for value A leakage current value for one of the lighting failure sources obtained by dividing the leakage current values obtained in the inspection.

  In the manufacturing method, the quality of the formed organic EL element is determined by comparing the leak current value of the organic EL element with the standard value. The time required for the leak inspection of the organic EL element is a short time (for example, 1 second or 2 seconds), and the standard value has one standard value organic EL element formed for standard value calculation. Since it is a leak current value with respect to the lighting failure source, the above manufacturing method can improve the productivity of the organic EL element as a non-defective product in which the lighting failure defect is suppressed.

  The method for manufacturing an organic EL element according to an embodiment further includes a standard value acquisition step of acquiring the standard value before the determination step, and the standard value acquisition step is performed on the surface of the second substrate. The standard value element forming step of forming the standard value organic EL element by sequentially laminating the second substrate side electrode, the second organic EL portion including the second light emitting layer, and the second counter electrode. The standard value element forming step including the optical inspection step of acquiring information on the defect source by optical inspection, and the standard value organic EL element are subjected to a leak test, and the standard value organic A standard value leakage inspection process for acquiring a leakage current value of the EL element, a lighting test process for performing a lighting test on the standard value organic EL element, and information on the defect source acquired in the optical inspection process; Based on the above lighting test results Calculating the standard value by dividing the leakage current value acquired in the standard value leakage inspection step by the number of the lighting failure sources selected from the at least one defect source. May be.

  The organic EL element includes a defect source that does not cause lighting failure. However, in the above method, based on the information of at least one defect source obtained by optical inspection and the result of the lighting test, the organic EL for standard value is used. Since the lighting failure source is selected from the defect sources included in the element, the leakage current value for one lighting failure source can be calculated reliably.

  In the standard value element forming step, the optical inspection step is performed on the second substrate before the second substrate side electrode is formed, or the second substrate side electrode is formed. You may implement with respect to a 2nd board | substrate.

  The lighting failure source may be a minute foreign matter such as a fine particle fixed to the substrate itself or the substrate having the electrode. As described above, by carrying out on the second substrate before the formation of the second substrate side electrode or on the second substrate on which the second substrate side electrode is formed. It is possible to acquire information on defect sources including defective lighting sources.

  The defect source is a foreign matter, and the information on the defect source may include the position and shape of the foreign matter. The lighting failure source may be a minute foreign matter such as a fine particle fixed to the substrate itself or the substrate having the electrode. Therefore, it is possible to select a defective lighting source from the obtained defect sources by regarding the foreign matter as a defect source in the optical inspection and acquiring the position and shape as information by the optical inspection.

  An example of the optical inspection may be an automatic optical inspection.

  In the standard value leak inspection step, a reverse bias voltage may be applied to the standard value organic EL element to obtain the leak current value of the standard value organic EL element. In this case, since the reverse bias voltage does not contribute to the light emission of the standard value organic EL element, the leak current value can be obtained more accurately.

  In the leak inspection step, a reverse bias voltage may be applied to the organic EL element to obtain the leak current value of the organic EL element. In this case, since the reverse bias voltage does not contribute to the light emission of the organic EL element, the leak current value can be obtained more accurately.

  The lighting failure defect may be a defect having a luminance higher than a desired luminance, for example.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the organic EL element which can aim at the improvement of productivity can be provided.

FIG. 1 is a schematic diagram illustrating a configuration of an organic EL element manufactured by a method for manufacturing an organic EL element according to an embodiment. FIG. 2 is a flowchart of a method for manufacturing an organic EL element according to an embodiment. FIG. 3 is a schematic diagram showing a configuration of a standard value element, which is a standard value organic EL element. FIG. 4 is a flowchart of an example of the standard value acquisition process. FIG. 5 is a diagram for explaining an optical inspection process.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same reference numerals are assigned to the same elements, and duplicate descriptions are omitted. The dimensional ratios in the drawings do not necessarily match those described.

  As schematically shown in FIG. 1, an organic EL element 10 manufactured by a method for manufacturing an organic EL element according to an embodiment is an organic EL lighting panel used for illumination, for example. The organic EL element 10 includes a substrate (first substrate) 12, an anode (first substrate side electrode) 14, an organic EL unit (first organic EL unit) 16, and a cathode (first counter electrode). 18. The organic EL element 10 can take a form in which light is emitted from the anode 14 side or a form in which light is emitted from the cathode 18 side. Below, unless otherwise indicated, the form which radiate | emits light from the anode 14 side is demonstrated.

[substrate]
The board | substrate 12 has translucency with respect to visible light (light with a wavelength of 400 nm-800 nm). The substrate 12 may be a film-like substrate 12. The thickness of the substrate 12 is, for example, 30 μm or more and 700 μm or less.

  The substrate 12 may be a rigid substrate such as a glass substrate or a silicon substrate, or may be a flexible substrate such as a plastic substrate and a polymer film. A drive circuit (for example, a circuit including a thin film transistor) for driving the organic EL element 10 may be formed on the substrate 12. Such a drive circuit is usually made of a transparent material.

  A barrier film may be formed on the surface 12 a of the substrate 12. The barrier film can be, for example, a film made of silicon, oxygen, and carbon, or a film made of silicon, oxygen, carbon, and nitrogen. Specifically, examples of the material of the barrier film are silicon oxide, silicon nitride, silicon oxynitride, and the like. An example of the thickness of the barrier film is 100 nm or more and 10 μm or less.

[anode]
The anode 14 is provided on the surface 12 a of the substrate 12. For the anode 14, an electrode having optical transparency is used. As the electrode exhibiting light transmittance, a thin film of metal oxide, metal sulfide, metal or the like having high electrical conductivity can be used, and a thin film having high light transmittance is preferably used. The anode 14 may have a network structure made of a conductor (for example, metal).

  The thickness of the anode 14 can be determined in consideration of light transmittance, electrical conductivity, and the like. The thickness of the anode 14 is usually 10 nm to 10 μm, preferably 20 nm to 1 μm, and more preferably 50 nm to 500 nm. In the present specification, the substrate 12 provided with the anode 14 may be referred to as an electrode-equipped substrate 20.

[Organic EL part]
The organic EL unit 16 is provided on the anode 14. The organic EL unit 16 is a functional unit that contributes to light emission of the organic EL element 10 such as carrier movement and carrier recombination according to the voltage applied to the anode 14 and the cathode 18.

  The organic EL unit 16 includes a hole injection layer 161, a hole transport layer 162, a light emitting layer (first light emitting layer) 163, and an electron injection layer 164, which are functional layers stacked in order from the anode 14 side. is there. The organic EL unit 16 is not limited to the exemplified one as long as it includes the light emitting layer 163.

  The hole injection layer 161 is provided on the anode 14 and has a function of improving the hole injection efficiency from the anode 14 to the light emitting layer 163. The thickness of the hole injection layer 161 has an optimum value depending on the material used, and is appropriately set so that the driving voltage and the light emission efficiency become appropriate values. The thickness of the hole injection layer 161 is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, and more preferably 5 nm to 200 nm.

  The hole transport layer 162 is provided on the hole injection layer 161, and has a function of improving hole injection from the anode 14, the hole injection layer 161, or the hole transport layer 162 closer to the anode 14 to the light emitting layer 163. It is a layer which has. The thickness of the hole transport layer 162 differs depending on the material used, and is appropriately set so that the drive voltage and the light emission efficiency are appropriate values. The thickness of the hole transport layer 162 is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, and more preferably 5 nm to 200 nm.

  The light emitting layer 163 is provided on the hole transport layer 162 and is provided on the hole transport layer 162. The light emitting layer 163 is an organic layer having a function of emitting light of a predetermined wavelength. The thickness of the light emitting layer 163 has an optimum value depending on the material used, and is appropriately set so that the driving voltage and the light emission efficiency are appropriate values.

  The electron injection layer 164 is provided on the light emitting layer 163 and has a function of improving the electron injection efficiency from the cathode 18 to the light emitting layer 163. The thickness of the electron injection layer 164 varies depending on the material used, and is appropriately set so that the driving voltage and the light emission efficiency are appropriate. The thickness of the electron injection layer 164 is, for example, 1 nm to 1 μm.

[cathode]
The cathode 18 is provided on the organic EL unit 16. The thickness of the cathode 18 varies depending on the material used, and is set in consideration of electrical conductivity, durability, and the like. The thickness of the cathode 18 is usually 10 nm to 10 μm, preferably 20 nm to 1 μm, and more preferably 50 nm to 500 nm.

  Next, a method for manufacturing the organic EL element 10 according to an embodiment will be described with reference to the flowchart of the method for manufacturing the organic EL element shown in FIG. The manufacturing method of the organic EL element 10 includes an organic EL element formation step S10, a leak inspection step S12, and a determination step S14.

[Organic EL element formation process]
In organic EL element formation process S10, the organic EL element 10 is formed by laminating | stacking the anode 14, the organic EL part 16, and the cathode 18 in order on the board | substrate 12. FIG. Therefore, organic EL element formation process S10 has anode formation process S10A, organic EL part formation process S10B, and cathode formation process S10C.

<Anode formation process>
In the anode forming step S10A, the anode 14 is formed on the surface 12a. Before forming the anode 14, the surface 12a of the substrate 12 may be washed with pure water, an organic polar solvent, or the like.

  Examples of the material of the anode 14 include indium oxide, zinc oxide, tin oxide, indium tin oxide (abbreviated as ITO), indium zinc oxide (abbreviated as IZO), gold, platinum, silver, and copper. Among these, ITO, IZO, or tin oxide is preferable. The anode 14 can be formed as a thin film made of the exemplified materials. As the material of the anode 14, organic substances such as polyaniline and derivatives thereof, polythiophene and derivatives thereof may be used. In this case, the anode 14 can be formed as a transparent conductive film. As described above, the anode 14 may have a network structure made of a conductor (for example, metal). The anode 14 can be formed by a known method in the manufacture of the organic EL element 10. Examples of the method for forming the anode 14 include a vacuum deposition method, a sputtering method, an ion plating method, a plating method, and a coating method.

  As the coating method, for example, an ink jet printing method can be mentioned, but other known coating methods may be used as long as the coating method can form the anode 14. Known coating methods other than the inkjet printing method include, for example, a micro gravure coating method, a gravure coating method, a bar coating method, a roll coating method, a wire bar coating method, a spray coating method, a screen printing method, a flexographic printing method, and an offset printing method. And a nozzle printing method.

  The solvent of the coating solution containing the material of the anode 14 may be any solvent that can dissolve the material of the anode 14. Examples of the solvent include chloride solvents such as chloroform, methylene chloride and dichloroethane, ether solvents such as tetrahydrofuran, aromatic hydrocarbon solvents such as toluene and xylene, ketone solvents such as acetone and methyl ethyl ketone, ethyl acetate, butyl acetate and ethyl cell. Examples include ester solvents such as sorb acetate.

<Organic EL part formation process>
In the organic EL part forming step S <b> 10 </ b> B, the hole injection layer 161, the hole transport layer 162, the light emitting layer 163, and the electron injection layer 164 are sequentially formed on the anode 14. Each layer constituting the organic EL portion 16 can be formed by, for example, a coating method. Specifically, each of the hole injection layer 161, the hole transport layer 162, the light emitting layer 163, and the electron injection layer 164 is applied with a coating liquid containing the material of each layer on the base layer for the layer to be formed, It can be formed by drying and solidifying. The underlayer is, for example, the anode 14 for the hole injection layer 161 and the hole transport layer 162 for the hole transport layer 162. The example of the apply | coating method may be the same as the apply | coating method illustrated by anode formation process S10A.

  The solvent of the coating solution for forming the hole injection layer 161, the hole transport layer 162, the light emitting layer 163, and the electron injection layer 164 may be any solvent that dissolves the material of the layer to be formed. The example of a solvent may be the same as the solvent illustrated by anode formation process S10A.

  As the material of the hole injection layer 161, a known hole injection material can be used. Examples of the hole injection material include oxides such as vanadium oxide, molybdenum oxide, ruthenium oxide, and aluminum oxide, phenylamine compounds, starburst amine compounds, phthalocyanine compounds, amorphous carbon, polyaniline, and polyethylenedioxythiophene. And polythiophene derivatives such as (PEDOT).

  As the material of the hole transport layer 162, a known hole transport material can be used. Examples of the material for the hole transport layer 162 include polyvinyl carbazole or derivatives thereof, polysilane or derivatives thereof, polysiloxane or derivatives thereof having an aromatic amine in the side chain or main chain, pyrazoline or derivatives thereof, arylamine or derivatives thereof, Stilbene or derivatives thereof, triphenyldiamine or derivatives thereof, polyaniline or derivatives thereof, polythiophene or derivatives thereof, polyarylamine or derivatives thereof, polypyrrole or derivatives thereof, poly (p-phenylene vinylene) or derivatives thereof, or poly (2, 5-thienylene vinylene) or a derivative thereof. Examples of the material of the hole transport layer 162 include a hole transport layer material disclosed in JP 2012-144722 A, for example.

  The light emitting layer 163 is generally formed of an organic substance that mainly emits fluorescence and / or phosphorescence, or an organic substance and a dopant that assists the organic substance. The dopant is added, for example, in order to improve the luminous efficiency and change the emission wavelength. The organic substance contained in the light emitting layer 163 may be a low molecular compound or a high molecular compound. Examples of the light-emitting material constituting the light-emitting layer 163 include the following dye-based materials, metal complex-based materials, polymer-based materials, and dopant materials.

  Examples of the dye-based material include cyclopentamine or a derivative thereof, tetraphenylbutadiene or a derivative thereof, triphenylamine or a derivative thereof, oxadiazole or a derivative thereof, pyrazoloquinoline or a derivative thereof, distyrylbenzene or a derivative thereof, Styrylarylene or its derivative, pyrrole or its derivative, thiophene ring compound, pyridine ring compound, perinone or its derivative, perylene or its derivative, oligothiophene or its derivative, oxadiazole dimer or its derivative, pyrazoline dimer or its derivative, Examples include quinacridone or a derivative thereof, coumarin or a derivative thereof.

  Examples of the metal complex material include rare earth metals such as Tb, Eu, and Dy, or Al, Zn, Be, Pt, Ir, and the like as a central metal, and oxadiazole, thiadiazole, phenylpyridine, phenylbenzimidazole, and quinoline. Examples thereof include metal complexes having a structure or the like as a ligand. Examples of metal complexes include metal complexes having light emission from triplet excited states such as iridium complexes and platinum complexes, aluminum quinolinol complexes, benzoquinolinol beryllium complexes, benzoxazolyl zinc complexes, benzothiazole zinc complexes, azomethyl zinc complexes, A porphyrin zinc complex, a phenanthroline europium complex, etc. are mentioned.

  Examples of the polymer material include polyparaphenylene vinylene or derivatives thereof, polythiophene or derivatives thereof, polyparaphenylene or derivatives thereof, polysilane or derivatives thereof, polyacetylene or derivatives thereof, polyfluorene or derivatives thereof, polyvinylcarbazole or derivatives thereof, Examples include materials obtained by polymerizing at least one of the dye material and the metal complex material.

  Examples of dopant materials include perylene or derivatives thereof, coumarin or derivatives thereof, rubrene or derivatives thereof, quinacridone or derivatives thereof, squalium or derivatives thereof, porphyrin or derivatives thereof, styryl dyes, tetracene or derivatives thereof, pyrazolone or derivatives thereof, decacyclene Alternatively, derivatives thereof, phenoxazone or derivatives thereof, and the like can be given.

  As the material of the electron injection layer 164, a known electron injection material can be used. Examples of the material of the electron injection layer 164 include alkali metals, alkaline earth metals, alloys containing one or more of alkali metals and alkaline earth metals, oxides of alkali metals or alkaline earth metals, halides, carbonic acids. Examples thereof include a salt or a mixture of these substances.

  Examples of the alkali metal, alkali metal oxide, halide, and carbonate include lithium, sodium, potassium, rubidium, cesium, lithium oxide, lithium fluoride, sodium oxide, sodium fluoride, potassium oxide, potassium fluoride, and oxide. Examples include rubidium, rubidium fluoride, cesium oxide, cesium fluoride, and lithium carbonate.

  Examples of alkaline earth metal, alkaline earth metal oxide, halide and carbonate include magnesium, calcium, barium, strontium, magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride, barium oxide and barium fluoride. Strontium oxide, strontium fluoride, magnesium carbonate and the like.

<Cathode formation process>
In the cathode forming step S <b> 10 </ b> C, the cathode 18 is formed on the organic EL unit 16. The material of the cathode 18 is preferably a material having a low work function, easy electron injection into the light emitting layer 163, and high electrical conductivity. In the organic EL element 10 configured to extract light from the anode 14 side, the light emitted from the light emitting layer 163 is reflected by the cathode 18 to the anode 14 side. Therefore, the cathode 18 is made of a material having a high visible light reflectance. preferable.

  Examples of the material of the cathode 18 include alkali metals, alkaline earth metals, transition metals, and Group 13 metals of the periodic table. As the cathode 18, a transparent conductive electrode made of a conductive metal oxide, a conductive organic material, or the like may be used. The formation method of the cathode 18 can be the same as the formation method of the anode 14.

[Leak inspection process]
In the leak inspection step S <b> 12, a leak inspection is performed on the organic EL element 10 to acquire a leak current value of the organic EL element 10. Specifically, a voltage is applied between the anode 14 and the cathode 18 of the organic EL element 10 to measure the leakage current from the organic EL element 10. In the leak inspection, the voltage applied to the organic EL element 10 may be a reverse bias voltage from the viewpoint of clarifying the difference from the current that contributes to the light emission of the organic EL element 10. An example of the reverse bias voltage is −5V.

[Judgment process]
In the determination step S14, the leakage current value acquired in the leakage inspection step S12 is compared with the standard value to determine whether or not the organic EL element 10 is a non-defective product. When the leak current value is less than or equal to the standard value, the organic EL element 10 is determined as a non-defective product, and when the leak current value exceeds the standard value, the organic EL element 10 is determined as a defective product.

  In the case where a plurality of organic EL elements 10 are formed in the organic EL element forming step S10, the non-defective organic EL elements 10 can be selected from the plurality of organic EL elements 10 according to the result of the determination step S14. When one organic EL element 10 is formed in the organic EL element forming step S10 in order to obtain the formation conditions in the organic EL element forming step S10, the organic EL element 10 is a non-defective product as a result of the determination step S14. If it is determined, the formation conditions used in the organic EL element forming step S10 may be used for forming an organic EL element for a product. If the organic EL element 10 is determined to be defective, the organic EL element forming step What is necessary is just to change the formation conditions in S10 and to return to organic EL element formation process S10 again.

  The standard value is a defect (lighting failure) that causes a lighting failure when the standard value organic EL element (hereinafter referred to as “standard value element”) 10A formed for standard value calculation shown in FIG. (Defect) The leak current value calculated for one defect. Therefore, by the determination step S14, the organic EL element 10 that is unlikely to cause a lighting failure defect can be determined as a good product.

  In the present embodiment, the above-described defective lighting defect means that when the standard value element 10A (or the organic EL element 10) is turned on, the lighting state is always kept higher than the desired luminance with respect to the input current (voltage). It means a certain point-like defect (hereinafter referred to as “lighting failure defect”). Since the lighting failure defect usually appears as a white spot when the standard value element 10A (or the organic EL element 10) is turned on, the lighting failure defect is also a white spot defect.

  In this embodiment, the standard value element 10A has the same configuration as the organic EL element 10 to be manufactured, as shown in FIG. That is, the standard value element 10A includes an anode (second substrate side electrode) 14A, an organic EL portion (second organic EL portion) 16A, and a cathode (second substrate) on a substrate (second substrate) 12A. 18A, the organic EL portion 16A includes a hole injection layer 161A, a hole transport layer 162A, a light emitting layer 163A, and an electron injection layer 164A in order from the anode 14A side. It is constituted by.

  Hereinafter, unless otherwise specified, the substrate 12A included in the standard value element 10A, the anode 14A, the hole injection layer 161A, the hole transport layer 162A, the light emitting layer (second light emitting layer) 163A, the electron injection layer 164A, and the cathode 18A. The material, thickness, shape, etc. are the same as the corresponding elements of the organic EL element 10. Similarly to the case of the organic EL element 10, the substrate 12A on which the anode 14A is formed may be referred to as an electrode-equipped substrate 20A.

  Next, the standard value acquisition step S20 for acquiring the standard value used in the determination step S14 will be described with reference to FIG. The standard value acquisition step S20 includes a standard value element formation step S21, a leak inspection step (standard value leak inspection step) S22, a lighting test step S23, and a standard value calculation step S24.

[Element formation process for standard values]
The standard value element forming step S21 includes an optical inspection step S21A, an anode forming step S21B, an organic EL portion forming step S21C, and a cathode forming step S21D.

<Optical inspection process>
In the optical inspection step S21A, a defect source that is included in the substrate 12A and becomes a defect in the standard value element 10A is obtained by optical inspection. An example of the defect source is a foreign matter attached to the substrate 12A. When the standard value element 10A is formed, if the substrate 12A is previously cleaned with pure water or an organic polar solvent, the optical inspection step S21A may be performed after the substrate 12A is cleaned.

  An optical inspection method will be described with reference to FIG. As shown in FIG. 5, the substrate 12A is irradiated with illumination light L from the light source 22 disposed on one surface side of the substrate 12A, and the substrate 12 is captured by the imaging unit 24 disposed on the side opposite to the light source 22 side. A two-dimensional image is acquired. The imaging unit 24 may be an area sensor such as a CCD camera or a one-dimensional line sensor. In the case of a line sensor, the substrate 12 is scanned with the line sensor to obtain a two-dimensional image of the substrate 12A.

  In the optical inspection step S21A, the defect source pattern (including position, shape, etc.) such as foreign matter such as fine particles attached to the substrate 12A and causing defects in the organic EL element is used as the defect source. Obtain as information.

  An example of an optical inspection is an automated optical inspection (abbreviated as AOI). In this case, the optical inspection can be performed using an automatic optical inspection apparatus. The optical inspection is not limited to the AOI, and may be any method that can acquire the defect source pattern based on the image of the substrate 12A.

  Returning to FIG. 4, the steps after the optical inspection step S21A will be described.

<Anode formation process>
In the anode formation step S21B, the anode 14A is formed on the substrate 12A after the optical inspection step S21A. Since the formation method of the anode 14A is the same as that in the anode formation step S10A, description thereof is omitted.

<Organic EL part formation process>
In the organic EL part forming step S21C, the organic EL part 16A is formed on the anode 14A. That is, the hole injection layer 161A, the hole transport layer 162A, the light emitting layer 163A, and the electron injection layer 164A are formed on the anode 14A. The hole injection layer 161A, the hole transport layer 162A, the light emitting layer 163A, and the electron injection layer 164A are formed by the hole injection layer 161, the hole transport layer 162, the light emitting layer 163, and the electron injection layer 161 described in the organic EL part forming step S10B. Since it is the same as the formation method of the electron injection layer 164, description is abbreviate | omitted.

<Cathode formation process>
In the cathode forming step S21D, the cathode 18A is formed on the organic EL portion 16A. Since the method for forming the cathode 18A is the same as the method for forming the cathode 18, the description thereof is omitted.

[Leak inspection process]
In the leak inspection step S22, a leak inspection is performed by applying a voltage between the anode 14A and the cathode 18A of the standard value element 10A, and the leak current value of the standard value element 10A is acquired. From the viewpoint of clarifying the difference from the current contributing to the light emission of the standard value element 10A, the voltage applied to the standard value element 10A may be a reverse bias voltage. The application method and applied voltage of the voltage to the standard value element 10A in the leak inspection step S12 and the leak inspection step S22 may be the same as those of the organic EL element 10.

[Lighting test process]
In the lighting test step S23, a lighting test is performed on the standard value element 10A. In this lighting test, the standard value element 10A is lit for a predetermined time or more to determine whether or not a defective lighting defect occurs. For the standard value element 10A in which the lighting failure defect has occurred, the position of the lighting failure defect in the standard value element 10A is confirmed.

  The lighting failure defect does not appear immediately after the start of lighting of the standard value element 10A, and may appear after a certain period of time. Therefore, the predetermined time is a time when the lighting failure defect starts, for example, 48 hours. The predetermined time is more preferably the half-life of the standard value element 10A. However, as described above, if it is 48 hours, a standard value that can withstand practical use can be obtained.

[Standard value calculation process]
In the standard value calculation step S24, the information on the defect source obtained in the optical inspection step S21A is compared with the position of the lighting failure defect obtained from the lighting test result, so that at least one included in the standard value element 10A. All defect sources corresponding to the lighting failure defects (hereinafter referred to as “lighting failure sources”) are selected (or specified) from the two defect sources, and the leakage current in the standard value element 10A is selected with the selected number of lighting failure sources. The standard value is calculated by dividing the value.

  In the standard value acquisition step S20 shown in FIG. 4, the optical inspection step S21A is performed before the anode formation step S21B, but is performed after the anode formation step S21B and before the organic EL portion formation step S21C. Also good. That is, an optical inspection may be performed on the electrode-attached substrate 20A, which is the substrate 12 on which the anode 14A is formed.

  The standard value acquisition step S20 may be performed once before the determination step S14 in the method of manufacturing the organic EL element 10. Therefore, once the standard value is acquired in the standard value acquisition step S20, the standard value acquisition step S20 may not be performed when the organic EL element 10 is manufactured again.

  In the present embodiment, the standard value element 10 </ b> A formed in the standard value element formation step S <b> 21 is described as having the same configuration as that of the organic EL element 10 to be manufactured. However, the defective lighting is mainly caused by minute foreign matters such as fine particles fixed to the substrate 12. Therefore, the number of lighting failure sources depends on the shape (including size) of the substrate 12 and the substrate 12A. Therefore, other configurations may be different as long as at least the shapes of the substrate 12 and the substrate 12A viewed from the thickness direction match. Furthermore, the formation method of the corresponding element in the organic EL element formation step S10 and the standard value element formation step S21 may be different.

  In the standard value element forming step S21, a plurality of standard value elements 10A may be formed. A standard value calculation method in this case will be described.

  In the embodiment in which the plurality of standard value elements 10A are formed in the standard value element forming step S21, the optical inspection step S21A of the substrate 12A included in each standard value element 10A is performed when each standard value element 10A is formed. The defect source information for each standard value element 10A is acquired. In the leak inspection step S22, a leak current value for each standard value element 10A is acquired, and an average value thereof (average leak current value) is calculated. In the lighting test step S23, a lighting test is performed on each standard value element 10A, and the position of a defective lighting defect is selected (or specified) for each standard value element 10A. In the standard value calculation step S24, each standard value element is determined based on the defect source information for each standard value element 10A obtained in the optical inspection step S21A and the lighting test result obtained in the lighting test step S23. The lighting failure source at 10A is selected. An average value of the number of defective lighting sources (average number of defective lighting sources) for a plurality of standard value elements 10A calculated based on the number of defective lighting sources included in each standard value element 10A, and a plurality of standard value elements 10A. The leak current value obtained by dividing the average leak current value for is taken as the standard value.

  The method of forming the plurality of standard value elements 10A may be different. The standard value element 10A having the same formation method will be referred to as the same type of standard value element 10A. In this case, let the average leakage current value and the average number of defective lighting sources be the average leakage current value and the average number of defective lighting sources for the same type of standard value element 10A. In the standard value calculation step S24, a leak current value for one lighting failure source is calculated based on the correlation between the average leakage current value for the different standard value elements 10A and the average number of lighting failure sources, and the standard value is calculated. And it is sufficient.

  In the manufacturing method of the organic EL element 10, in the determination step S14, the organic EL element is based on the leak current value acquired in the leak inspection step S12 illustrated in FIG. 2 and the standard value acquired in the standard value acquisition step S20. It is determined whether 10 is a non-defective product. In the leak inspection in the leak inspection step S12, since the leak current value can be acquired in about several seconds (for example, 1 second or 2 seconds), the productivity of the organic EL element 10 can be improved. Further, since it is not necessary to perform a stress test or the like on the organic EL element 10 in order to determine whether the organic EL element 10 is good or bad, the organic EL element 10 that has been determined to be good and has been determined to be non-defective is deteriorated by the inspection. Absent.

  Since the standard value is a leak current value for one lighting failure source, it is possible to determine the organic EL element 10 in which lighting failure is unlikely to occur by determining whether or not it is good in the determination step S14. As a result, in the manufacturing method of the organic EL element, it is possible to efficiently produce the organic EL element 10 in which the occurrence of lighting failure is suppressed and the quality is improved.

  The defect sources acquired in the optical inspection step S21A include defect sources that do not cause lighting failures. In the standard value acquisition step S20, a lighting test of the standard value element 10A is performed, and a lighting failure source is selected from the result of the lighting test and the defect source information acquired in the optical inspection step S21A. The value is calculated. Therefore, the quality of the organic EL element 10 can be determined more reliably.

  An example of a lighting failure source is a minute foreign matter such as a fine particle fixed to the substrate 12 (or the substrate 12A). This is because if the fine particles are fixed to the substrate 12 (or the substrate 12A), a projection is generated on the anode 14 (or the anode 14A), and it is considered that leakage occurs due to the projection. A minute foreign matter such as a fine particle fixed to the anode 14 may be a source of lighting failure. This is because if the fine particles are fixed to the anode 14, it is considered that leakage occurs due to the thickness of the layer of the organic EL portion 16 being reduced in the vicinity of the fine particles. Therefore, if a foreign object is assumed as a defect source and the position and shape thereof are acquired as defect source information, a lighting failure source as a minute foreign object can be more reliably selected using the result of the lighting test. As a result, the organic EL element 10 with further improved quality can be manufactured. In order to detect the minute foreign matter fixed to the anode 14 as a defect source, the optical inspection step S21A may be performed after the anode forming step S21B as described above.

  In the leak inspection of the organic EL element 10 and the standard value element 10A in the leak inspection steps S12 and S22, in the form of performing a leak test by applying a reverse bias voltage to the organic EL element 10 and the standard value element 10A, the organic EL element It is easy to distinguish the current that contributes to the light emission of the element 10 and the standard value element 10A from the leakage current. Therefore, the standard value can be calculated more accurately, and the organic EL element 10 with further improved quality can be manufactured.

  Next, verification about the effectiveness of the judgment of the quality of the organic EL element based on the standard value will be described.

  First, standard value acquisition process S20 shown in FIG. 4 was implemented. In the standard value element forming step S21 included in the standard value acquisition process S20, the standard value element was formed using the substrate having the layer configuration shown in FIG. 3 and cleaned by two different methods. The standard value elements including substrates having different cleaning methods are referred to as a standard value element A1 and a standard value element A2. In the standard value element A1 and the standard value element A2, a glass substrate is adopted as the substrate, and the standard value element A1 and the standard value element A2 are provided on the surface of the glass substrate with an anode, a hole injection layer, and a hole. A transport layer, a light emitting layer, an electron injection layer, and a cathode were laminated.

  When forming the standard value element A1 and the standard value element A2, the glass substrate was cleaned before the optical inspection step S21A. Specifically, in the case of the standard value element A1, the glass substrate was washed with pure water for 2 minutes, and in the case of the standard value element A2, the glass substrate was washed with an organic polar solvent for 4 minutes. Then, optical inspection process S21A was implemented and the position of the defect source, the shape, etc. were acquired as information on the defect source of each standard value element A1 and each standard value element A2. Subsequently, the standard value element A1 and the standard value element A2 were formed by performing the organic EL part forming step S21C and the cathode forming step S21D.

  The standard value element A1 and the standard value element A2 were formed by the same method except that the glass substrate was washed differently. Therefore, the configuration of the standard value element A1 and the standard value element A2 (including the layer configuration and the material and thickness of each layer) are the same. In the standard value element forming step S21, 12 standard value elements A1 and 12 standard value elements A2 were formed.

After forming the standard value element A1 and the standard value element A2, the leak inspection step S22 was performed. In the leak inspection step S22, the leak current values of the standard value elements A1 and the standard value elements A2 are obtained, and the average leak current values for the 12 standard value elements A1 and the 12 standard value elements A2 are obtained. The average leakage current value was calculated. In the leak test, −5 V was applied as a reverse bias voltage to the standard value element A1 and each standard value element A2. As a result, the average leakage current value for the twelve standard value elements A1 and the average leakage current value for the twelve standard value elements A2 are 1.10 × 10 ⁻³ (A) as shown in Table 1. And 1.27 × 10 ⁻⁴ (A).

  Then, the lighting test process S23 was implemented with respect to each element A1 for standard values and each element A2 for standard values. Specifically, a voltage was applied between the anode and the cathode of each standard value element A1 and each standard value element A2, and it was continuously lit for 48 hours, and the presence or absence of defective lighting was visually confirmed. As a result, it was confirmed that defective lighting defects were generated for all the standard value elements A1 and standard value elements A2, and the positions of the defective lighting defects were acquired.

In the standard value calculation step S24, the information on the defect source obtained in the optical inspection step S21A and the information on the defective lighting defect obtained in the lighting test are obtained for each standard value element A1 and each standard value element A2. And a lighting failure source was selected from the plurality of defect sources obtained in the optical inspection step S21A. As shown in Table 1, the average number of defective lighting sources for 12 standard value elements A1 is 13, and the average number of defective lighting sources for 12 standard value elements A2 is 1.3. Met. The results of Table 1 were plotted on a graph and linear fitting was performed to calculate a leak current value for one defective lighting defect and set it as a standard value. The calculated standard value was 1.9 × 10 ⁻⁵ (A).

  Next, using the standard value calculated as described above, the effectiveness of the determination step S14 included in the method for manufacturing the organic EL element 10 was verified.

  For verification, twelve kinds of organic EL elements each having a different glass substrate cleaning method were formed. The three types of formed organic EL elements are referred to as an organic EL element B1, an organic EL element B2, and an organic EL element B3. The configuration of the organic EL element B1, the organic EL element B2, and the organic EL element B3 (including the material and thickness of each layer as well as the layer configuration) is the same as the configuration of the standard value element A1 (or standard value element A2). Met.

  Organic EL element B1, organic EL element B2, and organic EL element B3 were formed by the same method except that the glass substrate was washed differently. When forming the organic EL element B1, the glass substrate was washed with pure water for 2 minutes as in the case of the standard value element A1. When the organic EL element B2 was formed, the glass substrate was washed with an organic polar solvent for 4 minutes as in the case of the standard value element A2. When forming the organic EL element B3, the glass substrate was washed with an organic polar solvent as in the case of the standard value element A2. The cleaning time of the glass substrate of the organic EL element B3 was 8 minutes, which is twice the cleaning time performed in the formation of the organic EL element B2.

The leakage inspection step S12 shown in FIG. 2 was performed on each of the 12 formed organic EL elements B1, and the average leakage current value was calculated. Similarly, the leakage inspection step S12 shown in FIG. 2 was performed on each of the 12 formed organic EL elements B2, and the average leakage current value was calculated. Similarly, the leakage inspection step S12 shown in FIG. 2 was performed on each of the 12 formed organic EL elements B3, and the average leakage current value was calculated. In the leak inspection, −5 V was applied as a reverse bias voltage to the organic EL elements B1, B2, and B3. The calculated average leakage current value is as shown in Table 2, the average leakage current value of the organic EL element B1 is 1.10 × 10 ⁻³ (A), and the average leakage current value of the organic EL element B2 Was 1.43 × 10 ⁻⁴ (A), and the average leakage current value of the organic EL element B3 was 1.62 × 10 ⁻⁵ (A).

  Next, after twelve organic EL elements B1 were continuously lit for 48 hours, the incidence rate of defective lighting of the organic EL elements B1 was calculated. Similarly, after 12 organic EL elements B2 were continuously lit for 48 hours, the incidence rate of defective lighting of the organic EL elements B2 was calculated. Similarly, after 12 organic EL elements B3 were continuously lit for 48 hours, the incidence rate of defective lighting of the organic EL elements B3 was calculated.

The incidence rate of the defective lighting will be described by referring to the organic EL elements B1, B2, and B3 as the organic EL element B. When the number of organic EL elements B used for verification is N, the number of organic EL elements B in which defective lighting has occurred is M, and the incidence of defective lighting defects is α (%), α is as follows: Defined in
α = (M / N) × 100 (%)

  The incidence rates of defective lighting for organic EL elements B1, B2, and B3 obtained according to the above definitions are as shown in Table 2 above, which were 33.3%, 14.3%, and 0%, respectively.

Since the leak current value for one defective lighting defect which is a standard value is 1.9 × 10 ⁻⁵ (A), the organic EL element B3 is less than the standard value among the organic EL elements B1, B2 and B3. The leakage current value of the organic EL elements B1, B2 exceeded the standard value. As shown in Table 2, for the organic EL elements B1 and B2 having a leakage current value exceeding the standard value, defective lighting has occurred, and the organic EL element having a leakage current value equal to or less than the standard value With respect to B3, no defective lighting has occurred. Therefore, it was demonstrated that the quality of the organic EL element can be determined by using the standard value.

  Therefore, if the standard value is acquired in advance, the quality of the organic EL element can be easily determined by acquiring the leak current value of the organic EL element formed in the organic EL element forming step S10 shown in FIG. Therefore, the productivity of the organic EL element can be improved.

  The various embodiments and examples of the present invention have been described above. However, the present invention is not limited to the various embodiments and examples described above, and various modifications can be made without departing from the spirit of the present invention.

As described above, the organic EL portion may be a laminate including a functional layer other than the light emitting layer. Examples of the layer configuration of the organic EL element including various functional layers are shown below.
a) anode / light emitting layer / cathode b) anode / hole injection layer / light emitting layer / cathode c) anode / hole injection layer / light emitting layer / electron injection layer / cathode d) anode / hole injection layer / light emitting layer / Electron transport layer / electron injection layer / cathode e) anode / hole injection layer / hole transport layer / light emitting layer / cathode f) anode / hole injection layer / hole transport layer / light emitting layer / electron injection layer / cathode g ) Anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode h) Anode / light emitting layer / electron injection layer / cathode i) Anode / light emitting layer / electron transport layer / electron injection Layer / Cathode The symbol “/” means that the layers on both sides of the symbol “/” are joined together. The configuration of f) corresponds to the configuration shown in FIG.

  When at least one of the hole injection layer and the hole transport layer has a function of blocking electron transport, these layers may be referred to as an electron block layer. The electron transport layer is a layer having a function of improving electron injection from the cathode, the electron injection layer, or the electron transport layer closer to the cathode. When at least one of the electron injection layer and the electron transport layer has a function of blocking hole transport, these layers may be referred to as a hole blocking layer.

The organic EL element may have a single light emitting layer or two or more light emitting layers. In any one of the layer configurations a) to i) described above, when the stacked structure disposed between the anode and the cathode is “structural unit I”, the organic EL element having two light-emitting layers is provided. Examples of the configuration include the layer configuration shown in j) below. The two (structural units I) may have the same or different layer structure.
j) Anode / (structural unit I) / charge generation layer / (structural unit I) / cathode

  Here, the charge generation layer is a layer that generates holes and electrons by applying an electric field. Examples of the charge generation layer include a thin film made of vanadium oxide, ITO, molybdenum oxide, or the like.

Assuming that “(structural unit I) / charge generation layer” is “structural unit II”, examples of the configuration of the organic EL device having three or more light emitting layers include the layer configuration shown in the following k). .
k) Anode / (Structural unit II) x / (Structural unit I) / Cathode

  The symbol “x” represents an integer of 2 or more, and “(structural unit II) x” represents a stacked body in which (structural unit II) is stacked in x stages. A plurality of (structural units II) may have the same or different layer structure. An organic EL element may be configured by directly laminating a plurality of light emitting layers without providing a charge generation layer.

  In the description so far, the first and second substrate side electrodes have been described as anodes, and the first and second counter electrodes have been described as cathodes. However, the first and second substrate side electrodes are cathodes, The first and second counter electrodes may be anodes.

  DESCRIPTION OF SYMBOLS 10 ... Organic EL element, 10A ... Standard value element (Standard value organic EL element), 12 ... Substrate (first substrate), 12A ... Substrate (second substrate), 14 ... Anode (first substrate side) Electrode), 14A ... anode (second substrate side electrode), 16 ... organic EL part (first organic EL part), 16A ... organic EL part (second organic EL part), 18 ... cathode (first organic EL part) Counter electrode), 18A ... cathode (second counter electrode), 163 ... light emitting layer (first light emitting layer), 163A ... light emitting layer (second light emitting layer).

Claims (8)

An organic EL device that forms an organic EL element by sequentially laminating a first substrate-side electrode, a first organic EL unit including a first light emitting layer, and a first counter electrode on the surface of the first substrate. An element formation process;
A leakage inspection process for performing a leakage inspection on the organic EL element and obtaining a leakage current value of the organic EL element;
A determination step of comparing the leak current value with a standard value to determine the quality of the organic EL element;
With
The standard value is selected based on a result of a lighting test of the standard value organic EL element among at least one defect source in the standard value organic EL element formed for standard value calculation. One lighting failure obtained by dividing the leakage current value obtained in the leak inspection of the organic EL element for standard value by the number of lighting failure sources that appear as lighting failure defects in the lighting state of the organic EL element The leakage current value for the source,
Manufacturing method of organic EL element. A standard value acquisition step of acquiring the standard value before the determination step;
The standard value acquisition step includes
By stacking a second substrate side electrode, a second organic EL part including a second light emitting layer, and a second counter electrode in order on the surface of the second substrate, the standard value organic EL element is formed. A standard value element forming step to be formed, including an optical inspection step of acquiring information of the defect source by optical inspection; and
Performing a leak test on the standard value organic EL element to obtain a leak current value of the standard value organic EL element;
A lighting test process for performing a lighting test on the standard value organic EL element;
Based on the information of the defect source acquired in the optical inspection step and the result of the lighting test, the number of lighting defective sources selected from the at least one defect source, and the standard value leak inspection step Calculating the standard value by dividing the leakage current value acquired in step;
Having
The manufacturing method of the organic EL element of Claim 1. In the standard value element forming step, the optical inspection step is performed on the second substrate before the second substrate side electrode is formed, or the second substrate side electrode is formed. For the second substrate,
The manufacturing method of the organic EL element of Claim 2. The defect source is a foreign matter,
The defect source information includes the position and shape of the foreign matter,
The manufacturing method of the organic EL element of Claim 2 or 3. The optical inspection is an automatic optical inspection;
The manufacturing method of the organic EL element as described in any one of Claims 2-4. In the standard value leak inspection step, a reverse bias voltage is applied to the standard value organic EL element to obtain the leak current value of the standard value organic EL element.
The manufacturing method of the organic EL element as described in any one of Claims 2-5. In the leak inspection step, a reverse bias voltage is applied to the organic EL element to obtain the leak current value of the organic EL element.
The manufacturing method of the organic EL element as described in any one of Claims 1-6. The lighting failure defect is a defect having a luminance higher than a desired luminance.
The manufacturing method of the organic EL element as described in any one of Claims 1-7.

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