JP2017004951A - Manufacturing method of organic el element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an organic EL element excellent in light-emitting life.SOLUTION: The manufacturing method of an organic EL element including a positive electrode, a negative electrode, at least one layer of organic functional layer provided between the positive electrode and the negative electrode, and an encapsulating layer includes steps of: forming the positive electrode; forming the negative electrode; forming the at least one layer of organic functional layer; and forming the encapsulating layer. The average concentration A(ppm) of formic acid to which the organic EL element under manufacturing is exposed from a time of starting a step of forming the at least one layer of organic functional layer to a time of completing a step of forming the encapsulating layer and the exposure time B (sec) satisfy 0≤A×B<100.SELECTED DRAWING: None

Description

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

  An organic electroluminescence element (hereinafter referred to as “organic EL element”) has high luminous efficiency and low driving voltage, and thus can be suitably used for display and lighting applications. The organic EL device includes an anode, a cathode, and a light emitting layer disposed between the anode and the cathode, and holes and electrons injected from the anode and the cathode, respectively, are combined in the light emitting layer. Emits light.

An organic EL element has an advantage that an organic layer such as a light emitting layer can be formed by a coating method that is easy to manufacture and can easily increase the area of the element. Regarding the environment for forming the organic layer of the organic EL element, the organic layer film forming step is performed such that the sulfur oxide concentration is 2.2 μg / m ³ or less, the nitrogen oxide concentration is 3.1 μg / m ³ or less, A method for manufacturing an organic EL element manufactured at a carbon concentration of 0.7 μg / m ³ or less has been proposed (Patent Document 1).

Japanese Patent No. 5423706

However, the organic EL device manufactured by the above manufacturing method does not necessarily have a sufficient light emission lifetime.
Then, an object of this invention is to provide the manufacturing method of the organic EL element which is excellent in the light emission lifetime.

The present invention provides the following [1] to [8].
[1]
A method for producing an organic EL device comprising an anode, a cathode, at least one organic functional layer provided between the anode and the cathode, and a sealing layer,
Including a step of forming an anode, a step of forming a cathode, a step of forming at least one organic functional layer, and a step of forming a sealing layer,
Average concentration of formic acid to which the organic EL element being manufactured is exposed from the start of the step of forming at least one organic functional layer to the end of the step of forming the sealing layer: A (ppm), and the exposure time : B (seconds) satisfies the formula (1-1).

0 ≦ A × B <100 (1-1)

[2]
The manufacturing method of the organic EL element as described in [1], wherein A satisfies the formula (2-1).

0 ≦ A <1 (2-1)

[3]
The method for producing an organic EL element according to [1] or [2], wherein B satisfies the formula (3-1).

0 ≦ B ≦ 86400 (3-1)

[4]
Average concentration of formic acid to which the organic EL element being manufactured is exposed from the start of the step of forming at least one organic functional layer to the end of the step of forming the sealing layer: C (ppm), average of nitric acid Concentration: D (ppm) and average concentration of N-methylpyrrolidone (hereinafter referred to as “NMP”): E (ppm), propylene glycol-1-monomethyl ether-2-acetate (hereinafter referred to as “PGMEA”) Average concentration: F (ppm), 1-bromopropane (hereinafter referred to as “1-BP”) average concentration: G (ppm), and exposure time: H (seconds) The method for producing an organic EL element according to any one of [1] to [3], which satisfies at least two of (4-1) to (4-5).

0 ≦ C × H <100 (4-1)
0 ≦ D × H <35 (4-2)
0 ≦ E × H <92 (4-3)
0 ≦ F × H <9 (4-4)
0 ≦ G × H <33 (4-5)

[5]
The method for producing an organic EL element according to [4], wherein C, D, E, F and G satisfy at least two of formulas (7-1) to (7-5).

0 ≦ C <1 (7-1)
0 ≦ D <1 (7-2)
0 ≦ E <1 (7-3)
0 ≦ F <1 (7-4)
0 ≦ G <2 (7-5)

[6]
H is the manufacturing method of the organic EL element as described in [4] or [5] which satisfy | fills Formula (10-1).

0 ≦ H ≦ 86400 (10-1)

[7]
Any of [1] to [6], wherein the step of forming at least one organic functional layer includes a step of forming a film by a coating method using a composition containing an organic functional material and an organic solvent. 2. A method for producing an organic EL device according to item 1.
[8]
The method for producing an organic EL element according to any one of [1] to [7], wherein at least one organic functional layer contains a polymer compound.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the organic EL element which is excellent in the light emission lifetime can be provided.

The figure which shows the relationship of the product of the average concentration of formic acid to which the organic EL element under manufacture is exposed: A (ppm) and the exposure time: B (seconds): A × B, and 3% life reduction (time) of luminance It is.

  Hereinafter, preferred embodiments of the present invention will be described.

<Explanation of common terms>
Terms commonly used in this specification have the following meanings unless otherwise specified.

The “polymer compound” means a polymer having a molecular weight distribution and having a polystyrene-equivalent number average molecular weight of 1 × 10 ³ to 1 × 10 ⁸ .

  The polymer compound may be any of a block copolymer, a random copolymer, an alternating copolymer, and a graft copolymer, or other embodiments.

“Low molecular weight compound” means a compound having no molecular weight distribution and a molecular weight of 1 × 10 ⁴ or less.

  The “crosslinking group” is a group capable of generating a new bond by being subjected to heat treatment (baking), ultraviolet irradiation treatment, radical reaction, etc., and preferably has the formula (B-1)-( B-17) is a group represented by any of the above. These groups may have a substituent.

  “The organic EL element being manufactured is exposed” means being exposed to a gas existing outside the organic EL element.

  “At the start of the step of forming at least one organic functional layer” means at the start of the step of forming the first organic functional layer.

  “Ppm” is on a volume basis.

<Method for producing organic EL element>
The production method of the present invention comprises:
A method for producing an organic EL device comprising an anode, a cathode, at least one organic functional layer provided between the anode and the cathode, and a sealing layer,
Including a step of forming an anode, a step of forming a cathode, a step of forming at least one organic functional layer, and a step of forming a sealing layer,
Average concentration of formic acid to which the organic EL element being manufactured is exposed from the start of the step of forming at least one organic functional layer to the end of the step of forming the sealing layer: A (ppm), and the exposure time : B (seconds) is a method for producing an organic EL element that satisfies the formula (1-1).

  When the organic EL element has a plurality of organic functional layers, the product A × B of the average concentration A of formic acid and the exposure time B is formic acid to which the organic EL element being manufactured is exposed in the step of forming each organic functional layer It can also be calculated from the sum of the products of the average concentration a (ppm) and the exposure time b (seconds).

Since A × B can maintain a good element lifetime, it is preferable to satisfy formula (1-2), more preferably to satisfy formula (1-3), and further to satisfy formula (1-4). It is particularly preferable that the formula (1-5) is satisfied.
0 ≦ A × B <35 (1-2)
0 ≦ A × B <30 (1-3)
0 ≦ A × B <10 (1-4)
8 ≦ A × B <10 (1-5)

The process of forming at least one organic functional layer usually includes a film forming stage, a drying stage, a standby stage, a firing stage, and a cooling stage. Among these, the drying step, the standby step, the firing step, and the cooling step can be omitted if unnecessary.
The film forming step is a step of forming a film with an organic functional material or a composition containing an organic functional material and an organic solvent by using a vacuum deposition method or a coating method.
The drying step is a step of removing the organic solvent as necessary when the film forming step is performed by a coating method. The drying step is preferably performed in a vacuum in order to flatten the film shape.
The standby stage is a stage in which the organic EL element being manufactured is held before moving to the next stage. The standby stage is preferably a short time.
The baking step is a step of removing the water in the organic solvent or the organic functional layer remaining in the drying step in order to cross-link the cross-linking group when the organic functional material has a cross-linking group. The firing step is preferably performed in an inert gas atmosphere in order to prevent oxidation of the organic functional material.
The cooling step is a step of returning the baked organic EL element being manufactured to room temperature. The cooling step is preferably performed in a dry environment with a moisture concentration of 1 ppm or less in order to prevent moisture adsorption.

Since A can maintain a good element lifetime, it is preferable to satisfy the formula (2-1), more preferably the formula (2-2), and even more preferably the formula (2-3). .
0 ≦ A <0.1 (2-2)
0 ≦ A <0.01 (2-3)

Since B can maintain a good element lifetime, it is preferable to satisfy the formula (3-1), more preferably satisfy the formula (3-2), and even more preferably satisfy the formula (3-3). .
0 ≦ B <43200 (3-2)
0 ≦ B <18000 (3-3)

  Average concentration of formic acid to which the organic EL element being manufactured is exposed from the start of the step of forming at least one organic functional layer to the end of the step of forming the sealing layer: C (ppm), average of nitric acid Concentration: D (ppm), NMP average concentration: E (ppm), PGMEA average concentration: F (ppm), 1-BP average concentration: G (ppm), and exposure time: H (seconds) Preferably satisfy at least two of the formulas (4-1) to (4-5).

  When the organic EL device has a plurality of organic functional layers, the average concentration C of formic acid, the average concentration D of nitric acid, the average concentration E of NMP, the average concentration F of PGMEA, the average concentration G of 1-BP, and the exposure time Products with H C × H, D × H, E × H, F × H, and G × H are the average concentration of formic acid to which the organic EL element being manufactured is exposed in the step of forming each organic functional layer It can also be calculated from the sum of the product of c (ppm), the average concentration d of nitric acid, the average concentration e of NMP, the average concentration f of PGMEA, and the average concentration g of 1-BP and the exposure time h (seconds).

C, D, E, F, G, and H preferably satisfy at least two of formulas (5-1) to (5-5) from the viewpoint of device lifetime, It is more preferable to satisfy at least two of (6-5), and it is particularly preferable to satisfy at least two of formulas (6-6) to (6-10).
0 ≦ C × H <30 (5-1)
0 ≦ D × H <10 (5-2)
0 ≦ E × H <10 (5-3)
0 ≦ F × H <10 (5-4)
0 ≦ G × H <10 (5-5)

0 ≦ C × H <10 (6-1)
0 ≦ D × H <3 (6-2)
0 ≦ E × H <3 (6-3)
0 ≦ F × H <7 (6-4)
0 ≦ G × H <5 (6-5)

8 ≦ C × H <10 (6-6)
2 ≦ D × H <3 (6-7)
2 ≦ E × H <3 (6-8)
0 ≦ F × H <7 (6-9)
2 ≦ G × H <5 (6-10)

F and H preferably satisfy the formula (6-11) and more preferably satisfy the formula (6-12) from the viewpoint of luminous efficiency.
4 ≦ F × H <8.5 (6-11)
4 ≦ F × H <7 (6-12)

Since C, D, E, F, and G can maintain a good element lifetime, it is preferable to satisfy at least two of the formulas (7-1) to (7-5). It is more preferable to satisfy at least two of (8-5), and it is more preferable to satisfy at least two of formulas (9-1) to (9-5).
0 ≦ C <1 (8-1)
0 ≦ D <1 (8-2)
0 ≦ E <1 (8-3)
0 ≦ F <1 (8-4)
0 ≦ G <2 (8-5)

0 ≦ C <0.01 (9-1)
0 ≦ D <0.01 (9-2)
0 ≦ E <0.1 (9-3)
0 ≦ F <0.1 (9-4)
0 ≦ G <0.02 (9-5)

Since H can maintain a good element lifetime, it is preferable to satisfy the formula (10-1), more preferably the formula (10-2), and even more preferably the formula (10-3). .
0 ≦ H <43200 (10-2)
0 ≦ H <18000 (10-3)

  In the production method of the present invention, from the start of the step of forming at least one organic functional layer to the end of the step of forming the sealing layer, in an environment where the average concentration of formic acid is low, particularly formic acid and nitric acid , NMP, PGMEA, and 1-BP are performed in an environment where the average concentration is low. Such an environment can be prepared by any method, but from the start of the process of forming at least one organic functional layer to the end of the process of forming the sealing layer, a removal filter is installed at the outside air intake. It is preferable to carry out in the indoor environment.

  Examples of the removal filter include chemical filters such as a chemical filter using activated carbon and a chemical filter using a catalyst, and the average concentration of formic acid, nitric acid, NMP, PGMEA, and 1-BP may be further reduced. Therefore, a chemical filter using activated carbon is preferable.

  The average concentrations of formic acid, nitric acid, NMP, PGMEA, and 1-BP can be measured using, for example, a detector tube manufactured by GASTECH or a VOC monitor manufactured by Nippon Ray Systems.

<Layer structure of organic EL element>
The organic EL device produced by the production method of the present invention has an anode, a cathode, at least one organic functional layer, and a sealing layer.

  The organic functional layer is a layer containing a material capable of emitting light by injecting and transporting holes or electrons by applying a current to the anode and the cathode or applying a voltage. The material used for the organic functional layer may be any material that can inject and transport holes or electrons by applying an electric current or applying a voltage to emit light. preferable.

  As the organic functional material, a known material can be used, for example, a distyryl biphenyl material, a dimesitylboryl material, a stilbene material, a dipyrylyl dicyanobenzene material, a benzoxazole material, a distyryl material, a carbazole material. , Dibenzochrysene materials, arylamine materials, pyrene-substituted oligothiophene materials, PPV oligomer materials, carbazole materials, and polyfluorene materials.

  The organic functional layer is preferably formed by a coating method using a composition containing an organic functional material and an organic solvent. Examples of coating methods include spin coating, casting, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating, spray coating, screen printing, and flexographic printing. Method, offset printing method, inkjet printing method, capillary coating method, nozzle coating method, and spin coating method, nozzle coating method, and inkjet printing method are preferable.

  The viscosity of the composition may be adjusted depending on the type of coating method, but when ink is applied to a printing method such as an ink jet printing method via an ejection device, in order to prevent clogging and flight bending at the time of ejection. Furthermore, it is preferably 1 to 20 mPa · s at 25 ° C.

  The organic solvent contained in the composition is preferably a solvent that can dissolve or uniformly disperse the solid content in the composition. Examples of the organic solvent include chlorine solvents such as 1,2-dichloroethane, 1,1,2-trichloroethane, chlorobenzene and o-dichlorobenzene; ether solvents such as tetrahydrofuran, dioxane, anisole and 4-methylanisole; toluene , Xylene, mesitylene, ethylbenzene, n-hexylbenzene, cyclohexylbenzene and other aromatic hydrocarbon solvents; cyclohexane, methylcyclohexane, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n -Aliphatic hydrocarbon solvents such as decane, n-dodecane, bicyclohexyl; ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone, acetophenone; ethyl acetate, butyl acetate, ethyl cellosolve acetate, methyl benzoate, phenyl acetate, etc. Ester solvent; ethylene glycol Glycerine, 1,2 polyhydric alcohol solvents such as hexane diol; isopropyl alcohol, alcohol solvents such as cyclohexanol; sulfoxide solvents such as dimethyl sulfoxide; N, include amide solvents such as N- dimethylformamide. A solvent may be used individually by 1 type, or may use 2 or more types together.

Examples of the organic functional layer include a hole transport layer, a hole injection layer, an electron transport layer, an electron injection layer, and a light emitting layer.
The hole transport layer, the hole injection layer, the electron transport layer, the electron injection layer, and the light emitting layer contain a hole transport material, a hole injection material, an electron transport material, an electron injection material, and a light emitting material, respectively. Each of these can be formed using a material, a hole injection material, an electron transport material, an electron injection material, and a light emitting material.

  What is necessary is just to adjust the order of the layer to laminate | stack, the number, and thickness in consideration of the light emission lifetime of the organic EL element manufactured with the manufacturing method of this invention.

  The thicknesses of the hole transport layer, the hole injection layer, the electron transport layer, the electron injection layer, and the light emitting layer are usually 1 nm to 10 μm, respectively.

  The organic EL device produced by the production method of the present invention is at least one layer of a hole injection layer and a hole transport layer between the anode and the light emitting layer from the viewpoint of hole injection properties and hole transport properties. From the viewpoint of electron injecting property and electron transporting property, it is preferable to have at least one of an electron injecting layer and an electron transporting layer between the cathode and the light emitting layer.

  In the organic EL device manufactured by the manufacturing method of the present invention, the hole transport layer, the hole injection layer, the electron transport layer, the electron injection layer, and the light emitting layer may be formed by using, for example, a powder when a low molecular weight compound is used. In the case of using a polymer compound, for example, a method by film formation from a solution or a molten state may be mentioned.

  For the hole transport layer, the hole injection layer, the electron transport layer, the electron injection layer, and the light emitting layer, a composition containing a hole transport material, a hole injection material, an electron transport material, an electron injection material, and a light emitting layer is used. And can be formed by a coating method. Examples of the coating method include the same coating methods as those used in the formation of the organic functional layer described above. Moreover, as an organic solvent contained in this composition, the thing similar to the organic solvent contained in the composition in formation of the organic functional layer mentioned above is mentioned, for example.

  In the composition, the amount of the organic solvent is usually 1000 to 100,000 parts by weight, preferably 100 to 100 parts by weight, preferably 100 parts by weight of the hole transport material, hole injection material, electron transport material, electron injection material and light emitting material. 2000 to 20000 parts by weight.

  A hole transport material, a hole injection material, an electron transport material, an electron injection material, and a light-emitting material are a hole transport layer, a hole injection layer, an electron transport layer, an electron, respectively, in the method for producing an organic EL device of the present invention. When dissolved in a solvent used when forming a layer adjacent to the injection layer and the light emitting layer, it is preferable that the material has a crosslinking group in order to avoid dissolution of the material in the solvent. After forming each layer using a material having a crosslinking group, the layer can be insolubilized by crosslinking the crosslinking group.

  The heating temperature for cross-linking each layer is usually 25 to 300 ° C., and the organic EL device produced by the production method of the present invention has an excellent emission lifetime, and is preferably 50 to 250 ° C., more preferably Is 150-200 ° C.

  The kind of light used for light irradiation for cross-linking each layer is, for example, ultraviolet light, near ultraviolet light, or visible light.

[Substrate / Electrode (Material)]
The organic EL device produced by the production method of the present invention usually has a substrate. The substrate may be any substrate as long as it can form electrodes and does not change chemically when the organic functional layer is formed. For example, the substrate is made of a material such as glass, plastic, or silicon.

  Examples of the material for the anode include conductive metal oxides and translucent metals, preferably indium oxide, zinc oxide, tin oxide; indium tin oxide (ITO), indium zinc oxide, etc. A conductive compound of silver, palladium and copper (APC); NESA, gold, platinum, silver and copper.

  Examples of the material of the cathode include metals such as lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, aluminum, zinc, indium; two or more kinds of alloys thereof; Alloys of at least one species and at least one of silver, copper, manganese, titanium, cobalt, nickel, tungsten, and tin; and graphite and graphite intercalation compounds. Examples of the alloy include a magnesium-silver alloy, a magnesium-indium alloy, a magnesium-aluminum alloy, an indium-silver alloy, a lithium-aluminum alloy, a lithium-magnesium alloy, a lithium-indium alloy, and a calcium-aluminum alloy.

  Each of the anode and the cathode may have a laminated structure of two or more layers.

  In the organic EL device produced by the production method of the present invention, at least one of the anode and the cathode is usually transparent or translucent, but the anode is preferably transparent or translucent.

  Examples of the method for forming the anode and the cathode include a vacuum deposition method, a sputtering method, an ion plating method, a plating method, and a laminating method.

[Light emitting layer (light emitting material)]
The light emitting material is usually formed of an organic compound (low molecular compound and high molecular compound) that mainly emits fluorescence or phosphorescence and a dopant that assists the organic compound. Examples of the light emitting material include a dye material, a metal complex material, and a polymer material.

  Examples of the dye-based material include cyclopentamine and derivatives thereof, tetraphenylbutadiene and derivatives thereof, triphenylamine and derivatives thereof, oxadiazole and derivatives thereof, pyrazoloquinoline and derivatives thereof, distyrylbenzene and derivatives thereof, Examples include distyrylarylene and derivatives thereof, pyrrole and derivatives thereof, thiophene ring compounds, pyridine ring compounds, perinone and derivatives thereof, perylene and derivatives thereof, oligothiophene and derivatives thereof, oxadiazole dimers, and pyrazoline dimers.

  Examples of metal complex materials include aluminum quinolinol complex, benzoquinolinol beryllium complex, benzoxazolyl zinc complex, benzothiazole zinc complex, azomethylzinc complex, porphyrin zinc complex, europium complex, etc. Examples thereof include metal complexes having Be or the like, or a rare earth metal such as Tb, Eu, or Dy, and having a ligand such as oxadiazole, thiadiazole, phenylpyridine, phenylbenzimidazole, or quinoline structure.

  Examples of the polymer material include polyparaphenylene vinylene and derivatives thereof, polythiophene and derivatives thereof, polyparaphenylene and derivatives thereof, polysilane and derivatives thereof, polyacetylene and derivatives thereof, polyfluorene and derivatives thereof, and polyvinylcarbazole and derivatives thereof. And compounds obtained by polymerizing the above dye-based materials or metal complex-based materials.

  Among the luminescent materials, blue luminescent materials include, for example, distyrylarylene and derivatives thereof, oxadiazole and derivatives thereof, and polymers thereof; polyvinylcarbazole and derivatives thereof, polyparaphenylene and derivatives thereof, polyfluorene and Examples thereof include polyvinylcarbazole and derivatives thereof, polyparaphenylene and derivatives thereof, and polyfluorene and derivatives thereof.

  Among the light emitting materials, examples of the green light emitting material include quinacridone and derivatives thereof, coumarin and derivatives thereof, and polymers thereof; polyparaphenylene vinylene and derivatives thereof, polyfluorene and derivatives thereof, and polyparaphenylene. Vinylene and its derivatives, polyfluorene and its derivatives are preferred.

  Among the light emitting materials, examples of the red light emitting material include coumarin and derivatives thereof, thiophene ring compounds, and polymers thereof; polyparaphenylene vinylene and derivatives thereof, polythiophene and derivatives thereof, polyfluorene and derivatives thereof. Polyparaphenylene vinylene and derivatives thereof, polythiophene and derivatives thereof, and polyfluorene and derivatives thereof are preferable.

  A dopant can be added to the light emitting layer for the purpose of improving the light emission efficiency and changing the light emission wavelength. Examples of the dopant include perylene and derivatives thereof, coumarin and derivatives thereof, rubrene and derivatives thereof, quinacridone and derivatives thereof, squalium and derivatives thereof, porphyrin and derivatives thereof, styryl dyes, tetracene and derivatives thereof, pyrazolone and derivatives thereof, Examples include decacyclene and phenoxazone.

  A luminescent material may be used individually by 1 type, or may use 2 or more types together.

[Hole transport layer (hole transport material)]
The hole transport material is classified into a low molecular compound and a high molecular compound, and is preferably a high molecular compound. The hole transport material may have a crosslinking group.

  Examples of the polymer compound include polyvinyl carbazole and derivatives thereof; polyarylene having an aromatic amine structure in the side chain or main chain and derivatives thereof. The polymer compound may be a compound to which an electron accepting site is bonded. Examples of the electron accepting site include fullerene, tetrafluorotetracyanoquinodimethane, tetracyanoethylene, and trinitrofluorenone, and fullerene is preferable.

  A hole transport material may be used individually by 1 type, or may use 2 or more types together.

[Electron transport layer (electron transport material)]
Electron transport materials are classified into low molecular compounds and high molecular compounds. The electron transport material may have a crosslinking group.

  Low molecular weight compounds include, for example, metal complexes having 8-hydroxyquinoline as a ligand, oxadiazole, anthraquinodimethane, benzoquinone, naphthoquinone, anthraquinone, tetracyanoanthraquinodimethane, fluorenone, diphenyldicyanoethylene and diphenoquinone. As well as these derivatives.

  Examples of the polymer compound include polyphenylene, polyfluorene, and derivatives thereof. The polymer compound may be doped with a metal.

  An electron transport material may be used individually by 1 type, or may use 2 or more types together.

[Hole injection material and electron injection material]
The hole injection material and the electron injection material are classified into a low molecular compound and a high molecular compound, respectively. The hole injection material and the electron injection material may have a crosslinking group.

  Examples of the low molecular weight compound include metal phthalocyanines such as copper phthalocyanine; carbon; metal oxides such as molybdenum and tungsten; and metal fluorides such as lithium fluoride, sodium fluoride, cesium fluoride, and potassium fluoride.

  Examples of the polymer compound include polyaniline, polythiophene, polypyrrole, polyphenylene vinylene, polythienylene vinylene, polyquinoline and polyquinoxaline, and derivatives thereof; conductive polymers such as polymers containing an aromatic amine structure in the main chain or side chain. A functional polymer.

  In the composition, the content of the hole injection material and the electron injection material is usually 1 to 100 parts by weight, preferably 5 to 100 parts by weight, with respect to 100 parts by weight of the hole injection material.

  Each of the hole injection material and the electron injection material may be used alone or in combination of two or more.

When the hole injection material or the electron injection material contains a conductive polymer, the electrical conductivity of the conductive polymer is preferably 1 × 10 ⁻⁵ S / cm to 1 × 10 ³ S / cm. In order to make the electric conductivity of the conductive polymer within such a range, the conductive polymer can be doped with an appropriate amount of ions.

  The type of ions to be doped is an anion for a hole injection material and a cation for an electron injection material. Examples of the anion include polystyrene sulfonate ion, alkylbenzene sulfonate ion, and camphor sulfonate ion. Examples of the cation include lithium ion, sodium ion, potassium ion, and tetrabutylammonium ion.

  Doping ions may be used alone or in combination of two or more.

[Sealing layer (material)]
The sealing layer only needs to have a barrier property against moisture and oxygen gas. As one form of the sealing layer, an anode, a cathode, and at least one organic functional layer included in the organic EL element are used. However, it is sealed with a substrate made of a material such as glass, plastic, or silicon in a state filled with an inert gas such as nitrogen gas or argon gas. As another form of the sealing layer, the anode, cathode, and at least one organic functional layer of the organic EL element are made of glass, through an insulating layer made of an organic compound or an insulating layer made of an inorganic compound, Examples thereof include those sealed by a substrate made of a material such as plastic or silicon. Examples of the material for the insulating layer made of an organic compound include thermoplastic resins and photocrosslinkable resins. Examples of the material for the insulating layer made of an inorganic compound include metal oxides and metal nitrides.

  In the sealing layer, a desiccant may be disposed, or a desiccant may be included therein.

  The sealing layer is usually formed last after the anode, the cathode, and at least one organic functional layer are formed.

<Uses of organic EL elements>
In order to obtain planar light emission using the organic EL element, the planar anode and cathode may be arranged so as to overlap each other. In order to obtain pattern-like light emission, a method of installing a mask provided with a pattern-like window on the surface of a planar organic EL element, a layer that is desired to be a non-light-emitting part is formed extremely thick and substantially non-light-emitting. And a method of forming an anode or a cathode, or both electrodes in a pattern. By forming a pattern by any one of these methods and arranging several electrodes so that they can be turned on and off independently, a segment type display device capable of displaying numbers, characters, and the like can be obtained. In order to obtain a dot matrix display device, both the anode and the cathode may be formed in stripes and arranged orthogonally. Partial color display and multicolor display are possible by a method of separately coating a plurality of types of polymer compounds having different emission colors, or a method using a color filter or a fluorescence conversion filter. The dot matrix display device can be driven passively or can be driven actively in combination with TFTs. These display devices can be used for displays of computers, televisions, portable terminals and the like. The planar organic EL element can be suitably used as a planar light source for backlight of a liquid crystal display device or a planar illumination light source. If a flexible substrate is used, it can be used as a curved light source and display device.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples.

<Example 1>
The following steps were performed in a space prepared using a chemical guard (manufactured by NICHIAS, model number: WAVE-HA).

(Formation of anode and hole injection layer)
An anode was formed on the glass substrate by attaching an ITO film with a thickness of 45 nm by sputtering. This substrate was washed with an organic solvent, an alkaline detergent, and ultrapure water, and dried with hot air at about 80 ° C. for about 4 hours. Next, with respect to the plane ITO film is formed, a UV-O ₃ treatment was carried out for about 15 minutes using a UV-O ₃ apparatus. A composition containing a hole injection material was dropped on the ITO film, and the film was processed by spin coating for 28 seconds to form a film having a thickness of 65 nm. It was dried on a hot plate at 80 ° C. for 4 minutes, and after a waiting time of 35 minutes, further heated at 230 ° C. for 15 minutes and then cooled for 10 minutes to form a hole injection layer.
In the step of forming the hole injection layer, the cumulative exposure amount to which the organic EL element being manufactured was exposed to formic acid was 0.0001 × 3868 = 0.3868 ppm · sec.

(Formation of hole transport layer)
A hole transport material was mixed with xylene to obtain a composition for forming a hole transport layer having a solid content concentration (hole transport material) of 0.6% by weight. Using this composition for forming a hole transport layer, the composition for forming a hole transport layer dropped onto the hole injection layer was treated by spin coating for 13 seconds to form a film with a thickness of 20 nm. After a waiting time of 8 minutes, the substrate was baked at 180 ° C. for 60 minutes in a nitrogen gas atmosphere, and then naturally cooled to room temperature to form a hole transport layer.
In the step of forming the hole transport layer, the cumulative exposure amount to which the organic EL element being manufactured was exposed to formic acid was 0.0001 × 493 = 0.0493 ppm · sec.

(Formation of light emitting layer)
A luminescent conjugated polymer compound was mixed with xylene to obtain a composition for forming a luminescent layer having a solid content concentration (luminescent conjugated polymer compound) of 1.8% by weight. By using this composition for forming a light emitting layer, the composition for forming a light emitting layer dropped on the hole transport layer by a spin coating method was processed for 34 seconds to form a film with a thickness of 80 nm. Then, it waited for 30 minutes.
In the steps so far, the cumulative exposure amount to which the organic EL element being manufactured is exposed to formic acid was 0.0001 × 1834 = 0.1834 ppm · sec.

  Then, it was made to expose to formic acid so that the integrated exposure amount by which the organic EL element under manufacture was exposed to formic acid became 7.5 ppm * sec in the sealed atmosphere where the formic acid concentration was controlled. At this time, the average concentration of formic acid was 0.5 ppm, and the exposure time was 15 seconds. The average concentration of formic acid was measured using a detector tube (model number: 81L) manufactured by Gastec. Then, after baking at 150 degreeC for 10 minute (s) under nitrogen gas atmosphere, it naturally cooled to room temperature under nitrogen gas atmosphere, and formed the light emitting layer. In the step of forming the light emitting layer, the cumulative exposure amount to which the organic EL device under production was exposed to formic acid was 7.683 ppm · sec.

(Formation of cathode)
The organic EL element under production in which the light emitting layer was formed was placed in a vapor deposition machine, and after reducing the pressure to 1.0 × 10 ⁻⁴ Pa or less, about 3 nm of sodium fluoride was used as a cathode on the light emitting layer. Next, aluminum was deposited to about 100 nm. Then, the organic EL element 1 was produced by forming a sealing layer using a glass substrate in nitrogen gas atmosphere. The time required for forming and sealing the cathode was 4500 seconds.

  As described above, during the manufacture of the organic EL element 1, the accumulated exposure amount of the organic EL element being manufactured exposed to formic acid from the start of the process of forming the organic functional layer to the end of the process of forming the sealing layer A × B was 8.1 ppm · sec. The average concentration A of formic acid was 0.00130 ppm and the exposure time B was 6210 seconds.

When voltage was applied to the organic EL element 1, red EL light emission was observed. After setting the current value so that the initial luminance was 3000 cd / m ² , the device was driven at a constant current, and the lifetime until the initial luminance was reduced by 3% (hereinafter referred to as “LT97”) was measured to be 146 hours. Met.

<Example 2>
In Example 1, it was carried out except that the organic EL element being manufactured in which the light emitting layer was formed was exposed to formic acid so that the accumulated exposure amount exposed to formic acid in an atmosphere in which the concentration of formic acid was controlled was 30 ppm · sec. An organic EL element was produced in the same manner as in Example 1 (hereinafter referred to as “organic EL element 2”). The average concentration of formic acid was 1.2 ppm and the exposure time was 25 seconds.

  As described above, during the manufacture of the organic EL element 2, the accumulated exposure amount of the organic EL element being manufactured exposed to formic acid from the start of the process of forming the organic functional layer to the end of the process of forming the sealing layer A × B was 31 ppm · sec. The average concentration A of formic acid was 0.00498 ppm and the exposure time B was 6220 seconds.

When a voltage was applied to the organic EL element 2, red EL light emission was observed. The current value was set so that the initial luminance was 3000 cd / m ² , the device was then driven at a constant current, and LT97 was measured to be 146 hours.

<Comparative Example 1>
In Example 1, it was carried out except that the organic EL element being manufactured in which the light emitting layer was formed was exposed to formic acid so that the accumulated exposure amount exposed to formic acid in an atmosphere in which the concentration of formic acid was controlled was 120 ppm · sec. An organic EL element was produced in the same manner as in Example 1 (hereinafter referred to as “organic EL element C1”). The average concentration of formic acid was 2 ppm and the exposure time was 60 seconds.

  As described above, during the manufacture of the organic EL element C1, the accumulated exposure amount of the organic EL element being manufactured exposed to formic acid from the start of the process of forming the organic functional layer to the end of the process of forming the sealing layer A × B was 121 ppm · sec. The average concentration A of formic acid was 0.01934 ppm and the exposure time B was 6255 seconds.

When a voltage was applied to the organic EL element C1, red EL light emission was observed. The current value was set so that the initial luminance was 3000 cd / m ² , the device was then driven at a constant current, and the LT97 was measured and found to be 128 hours.

<Comparative example 2>
In Example 1, it was carried out except that the organic EL element being manufactured with the light emitting layer formed was exposed to formic acid so that the accumulated exposure amount exposed to formic acid in an atmosphere in which the concentration of formic acid was controlled was 384 ppm · sec. An organic EL element was produced in the same manner as Example 1 (hereinafter referred to as “organic EL element C2”). The average concentration of formic acid was 3.2 ppm and the exposure time was 120 seconds.

  As described above, during the manufacture of the organic EL element C2, the accumulated exposure amount of the organic EL element being manufactured exposed to formic acid from the start of the process of forming the organic functional layer to the end of the process of forming the sealing layer A × B was 385 ppm · sec. The average concentration A of formic acid was 0.06097 ppm and the exposure time B was 6315 seconds.

When voltage was applied to the organic EL element C2, red EL light emission was observed. After setting the current value so that the initial luminance was 3000 cd / m ² , the device was driven with a constant current, and LT97 was measured to be 94 hours.

<Comparative Example 3>
In Example 1, it was carried out except that the organic EL device being manufactured with the light emitting layer formed was exposed to formic acid so that the accumulated exposure amount exposed to formic acid in an atmosphere in which the concentration of formic acid was controlled was 650 ppm · sec. An organic EL element was produced in the same manner as in Example 1 (hereinafter referred to as “organic EL element C3”). The average concentration of formic acid was 5 ppm and the exposure time was 130 seconds.

  As described above, during the manufacture of the organic EL element C3, the accumulated exposure amount of the organic EL element being manufactured exposed to formic acid from the start of the process of forming the organic functional layer to the end of the process of forming the sealing layer A × B was 651 ppm · sec. The average concentration A of formic acid was 0.10292 ppm and the exposure time B was 6325 seconds.

When a voltage was applied to the organic EL element C3, red EL light emission was observed. After setting the current value so that the initial luminance was 3000 cd / m ² , it was driven with a constant current, and LT97 was measured, and it was 48 hours.

Claims (8)

A method for producing an organic EL device comprising an anode, a cathode, at least one organic functional layer provided between the anode and the cathode, and a sealing layer,
Including a step of forming an anode, a step of forming a cathode, a step of forming at least one organic functional layer, and a step of forming a sealing layer,
Average concentration of formic acid to which the organic EL element being manufactured is exposed from the start of the step of forming at least one organic functional layer to the end of the step of forming the sealing layer: A (ppm), and the exposure time : B (seconds) satisfies the formula (1-1).

0 ≦ A × B <100 (1-1)
The manufacturing method of the organic EL element of Claim 1 with which A satisfy | fills Formula (2-1).

0 ≦ A <1 (2-1)
The manufacturing method of the organic EL element of Claim 1 or 2 with which B satisfy | fills Formula (3-1).

0 ≦ B ≦ 86400 (3-1)
Average concentration of formic acid to which the organic EL element being manufactured is exposed from the start of the step of forming at least one organic functional layer to the end of the step of forming the sealing layer: C (ppm), average of nitric acid Concentration: D (ppm), average concentration of N-methylpyrrolidone: E (ppm), average concentration of propylene glycol-1-monomethyl ether-2-acetate: F (ppm), and average concentration of 1-bromopropane : G (ppm) and exposure time: H (seconds) satisfy at least two of formulas (4-1) to (4-5). Manufacturing method of EL element.

0 ≦ C × H <100 (4-1)
0 ≦ D × H <35 (4-2)
0 ≦ E × H <92 (4-3)
0 ≦ F × H <9 (4-4)
0 ≦ G × H <33 (4-5)
The manufacturing method of the organic EL element of Claim 4 with which C, D, E, F, and G satisfy | fill at least 2 of Formula (7-1)-(7-5).

0 ≦ C <1 (7-1)
0 ≦ D <1 (7-2)
0 ≦ E <1 (7-3)
0 ≦ F <1 (7-4)
0 ≦ G <2 (7-5)
H is the manufacturing method of the organic EL element of Claim 4 or 5 which satisfy | fills Formula (10-1).

0 ≦ H ≦ 86400 (10-1)
  The step of forming at least one organic functional layer includes a step of forming a film by a coating method using a composition containing an organic functional material and an organic solvent. The manufacturing method of the organic EL element of description.   The method for producing an organic EL element according to claim 1, wherein at least one organic functional layer contains a polymer compound.

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