JP2005142109A - Manufacturing method of organic electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescent element restrained from generation of short-circuited part, excellent in durability. <P>SOLUTION: On the manufacturing method of the organic electroluminescent element having a positive electrode, an organic layer, and a negative electrode, at least one of the positive electrode, at least one layer out of the organic layer, or the negative electrode is formed by a vacuum evaporation method, and the range of the fluctuation of evaporation speed is controlled within ±20% of a prescribed value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing an organic electroluminescent element that suppresses the occurrence of a short-circuited portion, has extremely excellent durability, and has high light emission luminance and light emission efficiency.

  Organic light-emitting devices using organic substances are promising for use as solid light-emitting, inexpensive large-area full-color display devices and writing light source arrays, and many developments have been made. In general, an organic electroluminescent element is composed of an organic layer including a light emitting layer and a pair of counter electrodes sandwiching the layer. In light emission, when an electric field is applied between both electrodes, electrons are injected from the cathode and holes are injected from the anode. This is a phenomenon in which energy is released as light when the electrons and holes recombine in the light emitting layer and the energy level returns from the conduction band to the valence band.

  Conventionally, in an organic electroluminescence device driven by a constant current, when the anode and the cathode are short-circuited, a specific pixel does not emit light, the presence of a short-circuited portion reduces the light emission luminance of the device, and further There is a problem that the entire device does not emit light when almost all of the current flows through the short-circuited portion.

  In order to prevent the occurrence of such a short circuit, an organic electroluminescent element is proposed in which a flame-supporting gas is enclosed in an airtight case that seals the light-emitting element, and the short-circuited portion is oxidized and insulated by this flame-supporting gas. (For example, refer to Patent Document 1). However, in this element, there is a possibility that deterioration of the element itself may be promoted by an extra combustion-supporting gas in the airtight case.

In addition, a method for manufacturing a light-emitting element in which thermal damage to the light-emitting layer is suppressed by changing the deposition rate of the electrode in stages has been proposed (for example, see Patent Document 2). However, there is no description about the film forming conditions of the organic layer, and there are still concerns about the generation of dark spots and the generation of short-circuited portions due to fluctuations in the film forming speed.
Japanese Patent Laid-Open No. 11-40346 JP 2003-229254 A

  An object of the present invention is to solve the above-described problems, and to provide a method for manufacturing an organic electroluminescent element excellent in durability by suppressing the occurrence of a short-circuit portion.

As a result of intensive studies, the inventors have been able to prevent the short circuit of the element by optimizing the vapor deposition conditions of the organic layer and the cathode, and in particular, by suppressing fluctuations in the vapor deposition rate of the organic layer, the short circuit portion can be eliminated. I found. That is, the said subject was solved by the following means.
(1) A method of manufacturing an organic electroluminescent device having an anode, an organic layer, and a cathode, wherein at least one layer of the anode, the organic layer, and the cathode is formed by a vacuum deposition method, and the deposition rate of the vacuum deposition method is increased. A method for manufacturing an organic electroluminescent element, wherein the fluctuation range is within ± 20% of a set value.

  ADVANTAGE OF THE INVENTION According to this invention, an organic light emitting electric field element which has very few short circuit parts and is excellent in durability can be provided. In addition, an organic electroluminescent device having excellent light emission luminance and light emission efficiency can be provided.

Hereinafter, a method for producing the organic electroluminescent element of the present invention (hereinafter also referred to as the element of the present invention or the light emitting element) will be described in detail.
The present invention is a method for producing an organic electroluminescent device having an anode, an organic layer, and a cathode, and the fluctuation of the deposition rate of the organic layer formed by the vacuum deposition method is within ± 20% of the set value, preferably ± 10. %, More preferably within ± 5%. If the fluctuation of the deposition rate is large, the film formation becomes non-uniform, and holes (spots) and thin layers (thin wall) portions may be generated in the film. If another material or the like is deposited on that portion, a short circuit will occur as a result, and the durability of the element will also decrease. By setting the fluctuation range within ± 20%, it is possible to suppress the occurrence of a short-circuited portion and obtain a highly durable element.

  The fluctuation range of the vapor deposition rate can be suppressed to within ± 20% of the set value by detecting the vapor deposition rate during film formation and appropriately controlling the vapor deposition rate. Therefore, it is preferable that the vapor deposition apparatus used for manufacturing the light emitting device of the present invention has a vapor deposition rate detecting unit and a vapor deposition rate control unit.

  The vapor deposition rate detection means is not particularly limited as long as it can detect a time-series change in the amount of vapor deposition material deposited on the substrate, and a suitable one is selected from known vapor deposition rate detection means. Can be used. Specifically, there is a means for detecting a vapor deposition material deposited on a vibrator (for example, quartz) as a change in the natural vibration of the vibrator.

  In the present invention, the vapor deposition rate information detected by the vapor deposition rate detection means is fed back to the vapor deposition rate control means, and the control means makes the vapor deposition rate constant based on the vapor deposition rate information from the vapor deposition rate detection means. By controlling the evaporation source, fluctuations in the deposition rate can be suppressed. In this case, the vapor deposition rate may be controlled directly by the electric current or power supplied to the heater of the evaporation source, or when the evaporation source temperature control system already exists as existing equipment or off-the-shelf products. You may control so that it may become predetermined | prescribed temperature with respect to a temperature control system.

  The main vapor deposition rate control means is not particularly limited as long as it can analyze information provided from the vapor deposition rate detection means and perform heater control in accordance with the analysis. This control means can usually be constituted by a general-purpose microprocessor (MPU) and a control algorithm on a storage medium (ROM, RAM, etc.) connected to the MPU. The control means can be used regardless of the processor mode such as CISC, RISC, DSP, etc., and is composed of an analog operation circuit using an ASIC or a combination of logic circuits such as a general IC, an operational amplifier, etc. Also good.

Next, the light emitting device of the present invention will be described.
-Organic layer-
The organic layer (organic compound layer) of the light emitting device of the present invention is a layer located between the electrodes, means a layer containing an organic compound as a main component, and may appropriately contain an inorganic compound. From each characteristic, a light emitting organic layer, an electron transporting organic layer, a hole transporting organic layer, an electron injection layer, a hole injection layer and the like can be mentioned. In addition, various layers for improving color developability can be exemplified. Specific examples of the compound used for each layer are described in, for example, “Monthly Display” October 1998 issue “Organic EL Display” (Techno Times).

There is no restriction | limiting in particular as a formation position of the organic layer in the light emitting element of this invention, Although it can select suitably according to the use and objective of this light emitting element, It is preferable to form on an anode or a cathode. In this case, the organic layer is formed on the front surface or one surface of the electrode.
There is no restriction | limiting in particular about the shape of a organic layer, a magnitude | size, thickness, etc., According to the objective, it can select suitably.

  As a specific layer structure of the organic layer between the electrodes in the light emitting device of the present invention, anode / hole transporting organic layer / light emitting organic layer / electron transporting organic layer / cathode, anode / hole injection layer / Hole transporting organic layer / light emitting organic layer / electron transporting organic layer / cathode, anode / hole transporting organic layer / light emitting organic layer / electron transporting organic layer / electron injection layer / cathode, anode / hole Examples include injection layer / hole transporting organic layer / light emitting organic layer / electron transporting organic layer / electron injection layer / cathode.

  The organic layer is a dry film forming method such as a vapor deposition method or a sputtering method, a dipping method, a spin coating method, a dip coating method, a casting method, a die coating method, a roll coating method, a bar coating method, a wet film forming method such as a gravure coating method, A film can be suitably formed by any of a transfer method, a printing method, and the like. The method for forming the organic layer (organic compound layer) in the light emitting device of the present invention is preferably a vapor deposition method. As the vapor deposition method, a resistance heating vapor deposition method is preferable.

(a) Luminescent organic layer The luminescent organic layer contains at least one luminescent compound. The light emitting compound is not particularly limited, and may be a fluorescent light emitting compound or a phosphorescent light emitting compound. Further, a fluorescent compound and a phosphorescent compound may be used at the same time. In the light emitting device of the present invention, it is preferable to use light emission from an excited triplet state from the viewpoint of light emission luminance and light emission efficiency, and it is preferable to use a phosphorescent compound. In the following description of the light-emitting organic layer, the term derivative means the compound itself and its derivative.

  The fluorescent compound is not particularly limited, for example, benzoxazole, benzimidazole, benzothiazole, styrylbenzene, polyphenyl, diphenylbutadiene, tetraphenylbutadiene, naphthalimide, coumarin, perylene, perinone, oxadiazole, aldazine, Typical examples include pyraridine, cyclopentadiene, bisstyrylanthracene, quinacridone, pyrrolopyridine, thiadiazolopyridine, styrylamine, aromatic dimethylidin compounds, metal complexes of 8-quinolinol derivatives, metal complexes of phenylpyridine derivatives, organometallic complexes, and rare earth complexes. And various metal complexes, polymer compounds such as polythiophene, polyphenylene, and polyphenylene vinylene, or derivatives of the above compounds.

  The phosphorescent compound is not particularly limited, but a transition metal complex is preferable. The central metal of the transition metal complex is not particularly limited, but is preferably iridium, platinum, rhenium, or ruthenium, more preferably iridium or platinum, and particularly preferably iridium. Of the transition metal complexes, orthometalated complexes are very preferred. The orthometalated complex is “A foundation and application of organometallics” written by Akio Yamamoto, pages 150 and 232, Houhuabosha (1982) and H.H. Yersin's “Photochemistry and Photophysics of Coordination Compound”, pages 71 to 77 and pages 135 to 146, Springer-Verlag (1987), etc.

  The phosphorescent compound preferably has a phosphorescent quantum yield of 70% or higher at 20 ° C. or higher, more preferably 80% or higher, and still more preferably 85% or higher.

  Examples of the phosphorescent compound include US 6303231 B1, US 6097147, WO 00/57676, WO 00/70655, WO 01/08230, WO 01/39234 A2, WO 01/41512 A1, WO 02/02714 A2, and WO 02. / 15645 A1, Japanese Patent Application Laid-Open No. 2001-247659, Japanese Patent Application No. 2000-33561, Japanese Patent Application No. 2002-117978, Japanese Patent Application No. 2001-248165, Japanese Patent Application No. 2002-239281, Japanese Patent Application No. 2002-239684, Japanese Patent Application Laid-Open No. 2002-170684, Japanese Patent No. JP 2002-226495, JP 2002-234894, JP 2001-247659, JP 2001-298470, JP 2002-173684, JP 2002-203678, JP 2002-2 No. 03679, Nature, 395, 151 (1998), Applied Physics Letters, 75, 4 (1999), Polymer Preprints, 41, 770 (2000), Journal of American Chemical. Those described in non-patent literature such as Society, 123, 4304 (2001), Applied Physics Letters, 79, 2082 (1999) can be suitably used.

  The light-emitting organic layer may contain a host compound, a hole transport material, an electron transport material, an electrically inactive polymer binder, and the like as necessary. Note that the functions of these materials may be achieved simultaneously by one compound. For example, a carbazole derivative not only functions as a host compound but also functions as a hole transport material.

  A host compound is a compound that causes energy transfer from its excited state to the luminescent compound, and as a result, causes the luminescent compound to emit light. Specific examples include carbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives. , Fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidene compounds, porphyrin compounds, anthraquinodimethane derivatives, anthrone derivatives, diphenylquinone derivatives, thiopyran dioxide oxide Derivatives, carbodiimide derivatives, fluorenylidenemethane derivatives, distyrylpyrazine derivatives, and heterocyclic tetra Rubonic acid anhydride, phthalocyanine derivative, metal complex of 8-quinolinol derivative, metal phthalocyanine, metal complex having benzoxazole or benzothiazole as a ligand, polysilane compound, poly (N-vinylcarbazole) derivative, aniline copolymer , Conductive polymers such as thiophene oligomers and polythiophenes, polythiophene derivatives, polyphenylene derivatives, polyphenylene vinylene derivatives, polyfluorene derivatives, and the like. A host compound may be used individually by 1 type, or may use 2 or more types together. The content of the host compound in the light-emitting organic layer is preferably 0 to 99.9% by mass, and more preferably 0 to 99.0% by mass.

  The hole transport material may have any one of the function of injecting holes from the anode, the function of transporting holes, and the function of blocking electrons injected from the cathode. Is carbazole, imidazole, triazole, oxazole, oxadiazole, polyarylalkane, pyrazoline, pyrazolone, phenylenediamine, arylamine, amino-substituted chalcone, styrylanthracene, fluorenone, hydrazone, stilbene, silazane, aromatic tertiary amine compound, Conductive polymer oligomers such as styrylamine, aromatic dimethylidin compounds, porphyrin compounds, polysilane compounds, poly (N-vinylcarbazole), aniline copolymers, thiophene oligomers, polythiophenes, organometallic complexes, transition metal complexes, Or above Derivatives of compounds, and the like.

  The electron transport material may have any one of the function of injecting electrons from the cathode, the function of transporting electrons, and the function of blocking holes that can be injected from the anode. Specific examples thereof include, for example, triazole, triazine, oxazole, oxadiazole, fluorenone, anthraquinodimethane, anthrone, diphenylquinone, thiopyran dioxide, carbodiimide, fluorenylidenemethane, distyrylpyrazine, silole, naphthaleneperylene, and the like. Aromatic metal tetracarboxylic anhydrides, phthalocyanines, metal complexes of 8-quinolinol derivatives, metal phthalocyanines, various metal complexes represented by metal complexes having benzoxazole or benzothiazole as ligands, or derivatives of the above compounds Can be mentioned.

Examples of the polymer binder include polyvinyl chloride, polycarbonate, polystyrene, polymethyl methacrylate, polybutyl methacrylate, polyester, polysulfone, polyphenylene oxide, polybutadiene, hydrocarbon resin, ketone resin, phenoxy resin, polyamide, ethyl cellulose, vinyl acetate, ABS resin, Polyurethane, melamine resin, unsaturated polyester, alkyd resin, epoxy resin, silicone resin, polyvinyl butyral, polyvinyl acetal, etc. can be used. These may be used individually by 1 type and may use 2 or more types together. The light-emitting organic layer containing a polymer binder can be easily applied and formed in a large area by a wet film forming method.
The thickness of the light emitting organic layer is preferably 10 to 200 nm, and more preferably 20 to 80 nm. When the thickness exceeds 200 nm, the driving voltage may increase. On the other hand, when the thickness is less than 10 nm, the organic electroluminescent device may be short-circuited.

(b) Hole transporting organic layer The organic electroluminescent device may have a hole transporting organic layer made of the above hole transporting material, if necessary. The hole transporting organic layer may contain the polymer binder. The thickness of the hole transporting organic layer is preferably 10 to 200 nm, and more preferably 20 to 80 nm. When the thickness exceeds 200 nm, the driving voltage may increase. On the other hand, when the thickness is less than 10 nm, the organic electroluminescent device may be short-circuited.

(c) Electron transporting organic layer The organic electroluminescent device may have an electron transporting organic layer made of the above electron transporting material, if necessary. The electron transporting organic layer may contain the polymer binder. The thickness of the electron transporting organic layer is preferably 10 to 200 nm, and more preferably 20 to 80 nm. When the thickness exceeds 200 nm, the driving voltage may increase. On the other hand, when the thickness is less than 10 nm, the organic electroluminescent device may be short-circuited.

-Protective layer-
The light-emitting element of the present invention may have a protective layer in addition to the organic layer. These layers are separate layers from the organic layer in the present invention, and the protective layer material has a function of preventing substances that promote device deterioration such as moisture and oxygen from entering the device. Anything is acceptable. Specific examples thereof include metals such as In, Sn, Pb, Au, Cu, Ag, Al, Ti, and Ni, MgO, SiO, SiO ₂ , Al ₂ O ₃ , GeO, NiO, CaO, BaO, and Fe ₂ O. ₃ , metal oxides such as Y ₂ O ₃ and TiO ₂ , metal fluorides such as MgF ₂ , LiF, AlF ₃ and CaF ₂ , polyethylene, polypropylene, polymethyl methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychloro Trifluoroethylene, polydichlorodifluoroethylene, a copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene, a copolymer obtained by copolymerizing a monomer mixture containing tetrafluoroethylene and at least one comonomer, and a copolymer main chain A fluorine-containing copolymer having a cyclic structure, a water-absorbing substance having a water absorption rate of 1% or more, Examples include moisture-proof substances having a water content of 0.1% or less.
There is no particular limitation on the method for forming the protective layer. For example, vacuum deposition, sputtering, reactive sputtering, MBE (molecular beam epitaxy), cluster ion beam, ion plating, plasma polymerization (high frequency excitation ions) Plating method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, coating method, ink jet method, printing method, transfer method, and electrophotographic method can be applied.

-Board-
The substrate used in the present invention preferably does not scatter or attenuate light emitted from the organic layer. Specific examples include zirconia stabilized yttrium (YSZ), inorganic materials such as glass, polyesters such as polyethylene terephthalate, polybutylene phthalate, polyethylene naphthalate, polystyrene, polycarbonate, polyethersulfone, polyarylate, polyimide, polycycloolefin. , Organic materials such as norbornene resin and poly (chlorotrifluoroethylene). In the case of an organic material, it is preferable that it is excellent in heat resistance, dimensional stability, solvent resistance, electrical insulation, and workability.

  There is no restriction | limiting in particular about the shape of a board | substrate, a structure, a magnitude | size, It can select suitably according to the use, purpose, etc. of a light emitting element. Generally, the shape is a plate shape. The structure may be a single layer structure, a laminated structure, may be formed of a single member, or may be formed of two or more members.

  The substrate may be colorless and transparent, or may be colored and transparent. However, the substrate is preferably colorless and transparent in that it does not scatter or attenuate light emitted from the light emitting layer.

The substrate can be provided with a moisture permeation preventing layer (gas barrier layer) on the front surface or back surface (anode side).
As a material for the moisture permeation preventive layer (gas barrier layer), inorganic materials such as silicon nitride and silicon oxide are preferably used. The moisture permeation preventing layer (gas barrier layer) can be formed by, for example, a high frequency sputtering method. If necessary, the substrate may be further provided with a hard coat layer, an undercoat layer, or the like.

-Anode-
The anode usually has a function of supplying holes to the organic layer, and there is no particular limitation on the shape, structure, size, etc., depending on the use and purpose of the light-emitting element. The electrode can be appropriately selected from these electrodes.

  As a material of the anode, for example, a metal, an alloy, a metal oxide, an organic conductive compound, or a mixture thereof can be preferably cited, and a material having a work function of 4.0 eV or more is preferable. Specific examples include semiconductive metal oxides such as tin oxide (ATO, FTO) doped with antimony or fluorine, tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), etc. Metals such as gold, silver, chromium and nickel, and mixtures or laminates of these metals and conductive metal oxides, inorganic conductive materials such as copper iodide and copper sulfide, organics such as polyaniline, polythiophene and polypyrrole Examples thereof include conductive materials and laminates of these with ITO.

  The anode may be, for example, a printing method, a wet method such as a coating method, a physical method such as a vacuum deposition method, a sputtering method, or an ion plating method, a chemical method such as a CVD method or a plasma CVD method, or the like. It can be formed on the substrate according to a method appropriately selected in consideration of suitability. For example, when ITO is selected as the anode material, the anode can be formed according to a direct current or high frequency sputtering method, a vacuum deposition method, an ion plating method, or the like. Moreover, when selecting an organic electroconductive compound as an anode material, it can carry out according to the wet film forming method.

  There is no restriction | limiting in particular as a formation position in the light emitting element of this invention of an anode, Although it can select suitably according to the use and objective of this light emitting element, forming on a board | substrate is preferable. In this case, the anode may be formed on the entire one surface of the substrate or may be formed on a part thereof.

  The patterning of the anode may be performed by chemical etching such as photolithography, or may be performed by physical etching using a laser or the like, or may be performed by vacuum deposition or sputtering with a mask overlapped. It may be performed by a lift-off method or a printing method.

The thickness of the anode can be appropriately selected depending on the material and cannot be generally defined, but is usually 10 nm to 50 μm, and preferably 50 nm to 20 μm. The resistance value of the anode is preferably 10 ³ Ω / □ or less, and more preferably 10 ² Ω / □ or less.
In order to extract light emission from the anode side, the anode is preferably a transparent anode having a transmittance of preferably 60% or more, more preferably 70% or more. In this case, even if it is colorless and transparent, it is colored and transparent. It may be. The transmittance can be measured according to a known method using a spectrophotometer.

  The anode is described in detail in “New Development of Transparent Electrode Film”, published by CMC (1999), supervised by Yutaka Sawada, and these can be applied to the present invention. When using a plastic substrate with low heat resistance, a transparent anode formed using ITO or IZO at a low temperature of 150 ° C. or lower is preferable.

-Cathode-
The cathode usually has a function of injecting electrons into the organic layer, and there is no particular limitation on the shape, structure, size, etc., and a known electrode can be used depending on the use and purpose of the light-emitting element. Can be selected as appropriate.

  Examples of the material for the cathode include metals, alloys, metal oxides, electrically conductive compounds, and mixtures thereof, and those having a work function of 4.5 eV or less are preferable. Specific examples include alkali metals (eg, Li, Na, K, Cs, etc.), alkaline earth metals (eg, Mg, Ca, etc.), gold, silver, lead, aluminum, sodium-potassium alloys, lithium-aluminum alloys, magnesium. -Rare earth metals such as silver alloys, indium, ytterbium, and the like. These may be used alone, but two or more can be suitably used in combination from the viewpoint of achieving both stability and electron injection.

Among these, alkali metals and alkalinity metals are preferable from the viewpoint of electron injection properties, and materials mainly composed of aluminum are preferable from the viewpoint of excellent storage stability.
The material mainly composed of aluminum is aluminum alone, or an alloy or mixture of aluminum and 0.01 to 10% by weight of alkali metal or alkaline earth metal (for example, lithium-aluminum alloy, magnesium-aluminum alloy, etc.). Say.

  The cathode material is described in detail in JP-A-2-15595 and JP-A-5-121172.

  There is no restriction | limiting in particular in the formation method of a cathode, It can carry out according to a well-known method. For example, suitability with the above materials from among wet methods such as printing methods, coating methods, physical methods such as vacuum deposition methods, sputtering methods and ion plating methods, chemical methods such as CVD and plasma CVD methods, etc. It can be formed according to a method appropriately selected in consideration. In particular, it is preferable to form by vapor deposition. As the vapor deposition method, a resistance heating vapor deposition method is preferable. For example, when a metal or the like is selected as the cathode material, it can be vapor-deposited alone or two or more components can be vapor-deposited simultaneously. Furthermore, a plurality of metals can be vapor-deposited simultaneously to form an alloy electrode, or a previously prepared alloy may be vapor-deposited.

  The cathode patterning may be performed by chemical etching such as photolithography, physical etching by a laser, or the like, or by vacuum deposition or sputtering with a mask overlapped. It may be performed by a lift-off method or a printing method.

There is no restriction | limiting in particular as a formation position in the light emitting element of this invention of a cathode, Although it can select suitably according to the use and objective of this light emitting element, It is preferable to form on the said organic layer. In this case, the cathode may be formed on the entire organic layer or a part thereof.
In addition, a dielectric layer made of the alkali metal or the alkaline earth metal fluoride may be inserted between the cathode and the organic layer with a thickness of 0.1 to 5 nm. The dielectric layer can be formed by, for example, a vacuum deposition method, a sputtering method, an ion plating method, or the like.

The thickness of the cathode can be appropriately selected depending on the cathode material, but is preferably 0.6 to 1.5 times the total thickness of the organic layer, more preferably 0.7 to 1.4 times, 0.8 to 1.2 times is particularly preferable.
The cathode may be transparent or opaque. The transparent cathode can be formed by depositing a thin cathode material to a thickness of 1 to 10 nm and further laminating a transparent conductive material such as ITO or IZO.

-Others-
Furthermore, in the light emitting device of the present invention, a moisture absorbent or an inert liquid can be provided in the space between the sealing container and the light emitting device. The moisture absorbent is not particularly limited, but for example, barium oxide, sodium oxide, potassium oxide, calcium oxide, sodium sulfate, calcium sulfate, magnesium sulfate, phosphorus pentoxide, calcium chloride, magnesium chloride, copper chloride, fluorine Examples thereof include cesium fluoride, niobium fluoride, calcium bromide, vanadium bromide, molecular sieve, zeolite, and magnesium oxide. The inert liquid is not particularly limited, and examples thereof include paraffins, liquid paraffins, fluorinated solvents such as perfluoroalkane, perfluoroamine, and perfluoroether, chlorinated solvents, and silicone oils. .

The light-emitting element of the present invention obtains light emission by applying a direct current (which may include an alternating current component as necessary) voltage (usually 2 to 40 volts) or a direct current between the anode and the cathode. Can do.
Regarding the driving of the light emitting device of the present invention, JP-A-2-148687, JP-A-6-301355, JP-A-5-290080, JP-A-7-134558, JP-A-8-234485, JP-A-8-2441047, US Pat. No. 5,828,429. No. 6023308, Japanese Patent No. 2784615, etc. can be used.

  The light emitting device of the present invention can be effectively used for a surface light source such as a full color display, a backlight and an illumination light source, a light source array such as a printer, and the like.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

(Example 1)
Using an ITO target having an In ₂ O ₃ content of 95% by weight on a 0.5 mm thick, 2.5 cm square glass substrate, DC magnetron sputtering (conditions: substrate temperature 100 ° C., oxygen pressure 1 × 10 ⁻³ Pa), an ITO thin film (thickness 0.2 μm) was formed as a transparent anode. The surface resistance of the ITO thin film was 10Ω / □.

Next, the substrate on which the transparent anode was formed was put into a cleaning container and subjected to IPA cleaning, and then UV-ozone treatment was performed for 30 minutes.
Copper phthalocyanine was vapor-deposited on the transparent anode by a vacuum vapor deposition method at a vapor deposition rate set value of 0.30 nm / sec to provide a 10 nm hole injection layer. The actual deposition rate was 0.27 to 0.31 nm / second.
On top of that, N, N′-dinaphthyl-N, N′-diphenylbenzidine (NPD) was deposited as a hole transporting material by a vacuum deposition method at a deposition rate set value of 0.20 nm / sec. A hole transporting organic layer was provided. The actual deposition rate was 0.18 to 0.22 nm / sec.
On top of this, Alq ₃ (tris (8-hydroxyquinolinato) aluminum) as a light emitting material / electron transporting material is deposited by a vacuum deposition method at a deposition rate set value of 0.22 nm / sec. A transportable organic layer was provided. The actual deposition rate was 0.20 to 0.24 nm / sec.

Further, a patterned mask (a mask having a light emission area of 5 mm × 5 mm) was placed on the electron transport layer, and an electron injection layer having a thickness of 0.001 μm was formed by lithium vacuum evaporation. A 0.1 μm cathode was provided on this by vacuum evaporation.
Aluminum lead wires were respectively connected from the anode and the cathode to form a light emitting laminate.
This was put in a glove box substituted with argon gas and sealed with a stainless steel sealing can and an ultraviolet curable adhesive (XNR5516HV, manufactured by Nagase Ciba) to obtain the light emitting device of the present invention. .

  Using a source measure unit type 2400 manufactured by Toyo Technica, a direct current voltage was applied to the prepared light emitting element to emit light. A voltage was applied to a plurality of light emitting elements prepared under the same vapor deposition conditions to emit light, but the number of elements that did not emit light due to a short circuit was 10% or less.

(Comparative Example 1)
In Example 1, copper phthalocyanine (hole injection layer) was deposited at a rate of 0.05 to 0.10 nm / second, and NPD (hole transporting organic layer) was deposited at a rate of 0.1 to 0.25 nm / second. The light emitting device of Comparative Example 1 was prepared in the same manner as in Example 1 except that Alq ₃ (light emitting organic layer / electron transporting organic layer) was deposited at a rate of 0.2 to 0.6 nm / sec. did.

Similarly to Example 1, when a voltage was applied to a plurality of devices prepared under the same vapor deposition conditions to emit light, half of the devices did not emit light due to a short circuit.
In addition, when the durability of the light-emitting elements of Example 1 and Comparative Example 1 was compared with the luminance half-life time when driven at a constant current with an initial luminance of 2000 Cd / m ² , the light-emitting element of Example 1 was 1.5. The service life was twice as long.

(Example 2)
On the ITO substrate cleaned in the same manner as in Example 1, the hole transport material NPD was deposited by a vacuum deposition method at a deposition rate set value of 0.20 nm / sec to provide a 50 nm hole transport layer. The actual deposition rate was 0.18 to 0.22 nm / sec. On top of this, tris (2-phenylpyridyl) iridium complex and 4,4′-N, N′-dicarbazolebiphenyl Ir (ppy) ₃ were deposited in a film thickness of 36 nm at a mass ratio of 1:17. Further, the following electron transporting compound was vapor-deposited at a vapor deposition rate set value of 0.30 nm / sec to provide a 36 nm electron-transporting layer. The actual deposition rate was 0.28 to 0.32 nm. A cathode was vapor-deposited on the obtained organic thin film in the same manner as in Example 1, and sealing was performed.

(Comparative Example 2)
In Example 2, the hole transport material NPD was vapor-deposited at a rate of 0.1 to 0.25 nm / sec, and the electron-transport compound was vapor-deposited at a rate of 0.3 to 0.9 nm / sec. In the same manner as in Example 2, a light emitting device of Comparative Example 2 was produced.

  As for the elements of Example 2 and Comparative Example 2, like the elements of Example 1 and Comparative Example 1, the element of Example 2 has a much lower proportion of elements that do not emit light due to a short circuit, and is excellent in durability. It was.

  From the above results, it can be seen that the element prepared under the vapor deposition conditions of the present invention can prevent a short circuit, improve the yield, and improve the driving durability.

Claims (1)

  A method for manufacturing an organic electroluminescent device having an anode, an organic layer, and a cathode, wherein at least one layer of the anode, the organic layer, and the cathode is formed by a vacuum deposition method, and a fluctuation range of a deposition rate in the vacuum deposition method is increased. The manufacturing method of the organic electroluminescent element characterized by setting it as less than +/- 20% with respect to a setting value.