JP2002175881A - Light emitting element - Google Patents

Abstract

(57) [Problem] To provide a light emitting element which is excellent in light emission luminance, light emission efficiency and durability, and can be effectively used for a surface light source such as a full color display, a backlight, an illumination light source, and a light source array such as a printer. SOLUTION: The light emitting element of the present invention has a transparent electrode on a substrate,
A light-emitting laminate including at least one organic compound layer including a light-emitting layer containing a phosphorescent compound and a back electrode, and a sealing member that shields the organic compound layer from external air. It is characterized in that a material that adsorbs oxygen or a material that reacts with oxygen is provided in a space between the sealing member and the sealing member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device having excellent light emission luminance, light emission efficiency and durability.

[0002]

2. Description of the Related Art Organic light-emitting elements using organic substances are expected to be used as solid-state light-emitting inexpensive large-area full-color display elements and writing light source arrays, and active research and development have been advanced in recent years. . In general, an organic light-emitting device includes an organic compound layer including a light-emitting layer and a pair of counter electrodes sandwiching the organic compound layer. When a voltage is applied to such an organic light emitting device, electrons are injected from the cathode into the organic compound layer, and holes are injected from the anode. The electrons and holes are recombined in the light emitting layer, and light is emitted by emitting energy as light when the energy level returns from the conduction band to the valence band.

The conventional organic light emitting device has a problem that the driving voltage is high and the light emission luminance and light emission efficiency are low. In recent years, various techniques for solving this problem have been reported. For example, an organic light-emitting device having an organic thin film formed by vapor deposition of an organic compound is known (Applied Physics Letters, 51, 913, 1987). ). This organic light-emitting device has a laminated two-layer structure of an electron transporting layer made of an electron transporting material and a hole transporting layer made of a hole transporting material, and exhibits significantly improved emission characteristics as compared with a single-layered device. A low molecular weight amine compound is used as the hole transport material, and an 8-quinolinol aluminum complex (Al
q) is used, and the emission color is green. Many organic light-emitting devices having vapor-deposited organic thin films have been reported thereafter (Macromolecular Symposium, Vol. 125, p. 1,
However, such an organic light-emitting device has a very low luminous efficiency as compared with an inorganic LED device and a fluorescent tube, which is a serious problem in practical use.

[0004] Most of the conventional organic light-emitting devices utilize fluorescence emitted from singlet excitons of an organic light-emitting material. In a simple quantum chemistry mechanism, the ratio of a singlet exciton capable of obtaining fluorescence emission to a triplet exciton capable of obtaining phosphorescence emission in an exciton state is 1: 3. That is,
As long as fluorescent light is used, only 25% of the excitons can be effectively used, and the light emitting efficiency of the fluorescent light emitting device is low. Under such circumstances, a phosphorescent device using an iridium phenylpyridine complex has recently been reported (Applied Physics Letter, Vol. 75, pp. 4, 1999, Japanese Journal of Applied Physics, Vol. 38, L1502, 1
999 years). These phosphorescent devices exhibit luminous efficiencies that are 2-3 times higher than those of conventional fluorescent luminous devices, but their luminous efficiencies are lower than the theoretical luminous efficiency limit, and the luminous efficiency is further improved for practical use. Is required. Further, as compared with the conventional fluorescent light emitting device, the phosphorescent light emitting device is inferior in durability, and improvement thereof is strongly desired.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a light source array such as a full-color display, a back light, a surface light source such as an illumination light source, and a light source array such as a printer, which is excellent in light emission luminance, light emission efficiency and durability. It is to provide a light emitting device.

[0006]

Means for Solving the Problems As a result of intensive studies in view of the above problems, the present inventor has found that a phosphorescent light-emitting device using a triplet exciton is different from a fluorescent light-emitting device using a singlet exciton. It is easily affected and the fact that the quenching phenomenon is caused by oxygen is found. By installing a material that adsorbs oxygen or reacts with oxygen in the sealing member of the light emitting element, phosphorescence with excellent light emitting characteristics and durability is provided. The inventors have found that a light-emitting element can be obtained, and have reached the present invention.

That is, the light emitting device of the present invention comprises a light emitting laminate comprising a transparent electrode, one or more organic compound layers including a light emitting layer containing a phosphorescent compound and a back electrode laminated on a substrate, and an organic compound. A sealing member that blocks the layer from outside air, and a space between the light emitting laminate and the sealing member,
A material which adsorbs oxygen or reacts with oxygen is provided. The light-emitting device of the present invention exhibits high luminance and luminous efficiency, and has excellent durability (particularly, durability under high temperature and high humidity), and is a full-color display, a backlight, a surface light source such as an illumination light source, and a light source such as a printer. It can be used effectively for arrays and the like.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The light-emitting device of the present invention comprises a light-emitting laminate comprising a transparent electrode, one or more organic compound layers and a back electrode laminated on a substrate, and sealing the organic compound layer to release external air. It has a sealing member for blocking. The organic compound layer includes a light emitting layer, and the light emitting layer contains a phosphorescent compound. If necessary, an organic compound layer other than the light-emitting layer, a protective layer, and the like may be provided.

A space exists between the light emitting laminate and the sealing member, and a material that adsorbs oxygen or reacts with oxygen is provided in the space. If no space is provided between the light emitting laminate and the sealing member, the element may be short-circuited because the thin film included in the light emitting laminate is extremely thin. The material that adsorbs oxygen and the material that reacts with oxygen used in the present invention are not particularly limited as long as they can reduce the surrounding oxygen concentration such as oxygen scavengers and antioxidants.
It may be solid or liquid. In order to increase the amount of adsorbed or reacted oxygen, it is preferable to use a powdery material having a large surface area as these materials.

The material for adsorbing oxygen or reacting with oxygen may be inorganic or organic. Specific examples of inorganic substances include alkali metals (lithium, sodium, potassium, rubidium, cesium, etc.) and alkaline earth metals (beryllium, magnesium,
Calcium, strontium, barium, etc.), low valent metal compounds (V ₂ O ₃ , Nb ₂ O ₃ , CrO, MoO ₂ , WO ₂ , Mn ₂ O ₃ , Fe
O, OsO ₂ , CoO, low-valent metal oxides such as NiO, etc.), Group III elements (boron, aluminum, gallium, indium, etc.), phosphorus, sulfur, molecular sieve, zeolite,
Carbon molecular sieves, zeolite molecular sieves and the like can be mentioned. Specific examples of organic substances include phenol-based antioxidants (hindered phenol compounds, etc.), amine-based antioxidants (phenylenediamine compounds, etc.), and phosphorus-based antioxidants (phosphite compounds, phosphonite compounds, etc.). And sulfur-based antioxidants (such as thioether compounds). These materials may be used alone or in combination of two or more.

The amount of the material that adsorbs oxygen or the material that reacts with oxygen is not particularly limited, and the size of the light-emitting laminate, the size of the entire light-emitting element, the oxygen adsorption characteristics of these materials, the reaction characteristics with oxygen, etc. May be appropriately selected according to the conditions.

As the sealing member, a sealing cap, a sealing cover and the like can be used. The material forming the sealing member may be any material having low moisture permeability and low oxygen permeability, and specific examples thereof include glass, inorganic materials such as ceramics, stainless steel, and the like.
Metals such as iron and aluminum, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polystyrene, polycarbonate,
Polymer materials such as polyether sulfone, polyarylate, allyl diglycol carbonate, polyimide, polycycloolefin, norbornene resin, poly (chlorotrifluoroethylene), Teflon (registered trademark), and polytetrafluoroethylene-polyethylene copolymer Is mentioned. Among them, a polymer material is preferable for forming a flexible light-emitting element or a coating-type light-emitting element.

In the present invention, the sealing step of installing the sealing member on the light emitting laminate is preferably performed in an atmosphere of an inert gas such as nitrogen or argon. When the sealing member is installed on the light emitting laminate, a sealing agent (adhesive) may be used as appropriate.
As the sealant, an ultraviolet curable resin, a thermosetting resin, a two-component curable resin, a moisture curable resin, an anaerobic curable resin, a hot melt resin, or the like can be used.

FIGS. 1 to 3 are schematic sectional views each showing an embodiment of the light emitting device of the present invention. Each of the light-emitting elements shown in FIGS. 1 to 3 has a light-emitting laminate 7 in which a transparent electrode 2, an organic compound layer 3, and a back electrode 4 are laminated on a substrate 1, and sealing for sealing the organic compound layer 3. It has a member 9. In these embodiments, the sealing member 9 is adhered to the base material 1, the transparent electrode lead 5, the back electrode lead 6, and the like with a sealing agent (adhesive) 8, and installed on the light emitting laminate 7. In the present invention, the sealing member 9 may be provided only on the back electrode 4 side as shown in FIG. 1, or the entire light emitting laminate 7 may be covered with the sealing member 9 as shown in FIGS. If the organic compound layer 3 can be shielded from the outside air, the shape, size,
The thickness and the like are not particularly limited. When the entire light emitting laminate 7 is covered with the sealing member 9 as in the light emitting elements shown in FIGS. 2 and 3, the sealing members 9 may be thermally fused to each other without using the sealing agent 8. .

As shown in FIGS. 1 to 3, a space 10 exists between the light emitting laminate 7 and the sealing member 9, and a material 12 that adsorbs oxygen or reacts with oxygen is provided in the space 10. Install.
The installation method is not particularly limited. For example, as shown in FIG. 1, a concave portion 11 is provided inside the sealing member 9 and inserted therein, or attached to the inner surface of the sealing member 9 using an adhesive tape or the like. Good. The space 10 may be filled with a powdery or liquid material that adsorbs oxygen or a material 12 that reacts with oxygen.

The space 10 may be filled with a moisture absorbent or an inert liquid. The water absorbent is not particularly limited, and specific examples thereof include barium oxide, sodium oxide, potassium oxide, calcium oxide, sodium sulfate, calcium sulfate, magnesium sulfate, phosphorus pentoxide, calcium chloride,
Examples thereof include magnesium chloride, copper chloride, cesium fluoride, niobium fluoride, calcium bromide, vanadium bromide, molecular sieve, zeolite, and magnesium oxide. As the inert liquid, paraffins, liquid paraffins, fluorine solvents (perfluoroalkane, perfluoroamine, perfluoroether, etc.), chlorine solvents, silicone oils and the like can be used.

In the light-emitting device of the present invention, the structure of the light-emitting laminate is such that a transparent electrode / light-emitting layer / back electrode, a transparent electrode / light-emitting layer / electron transport layer / back electrode, and a transparent electrode / hole transport layer are formed on a substrate. / Emitting layer / Electron transport layer / Back electrode, Transparent electrode / Hole transport layer / Emitting layer / Back electrode, Transparent electrode / Emitting layer / Electron transport layer / Electron injection layer / Back electrode, Transparent electrode / Hole injection layer /
A configuration in which a hole transport layer / light-emitting layer / electron transport layer / electron injection layer / back electrode and the like are stacked in this order, a configuration in which these are stacked in reverse, and the like may be used. The light emitting layer contains a phosphorescent compound, and light is normally extracted from the transparent electrode. Specific examples of the compound used for each layer are described in, for example, “OLED Display” (Techno Times), a separate volume of “Monthly Display”, October 1998.

The formation position of the organic compound layer is not particularly limited and can be appropriately selected depending on the use and purpose of the light emitting device. However, it is preferable to form the organic compound layer on a transparent electrode or a back electrode. At this time, the organic compound layer may be formed on the entire surface or a part of the transparent electrode or the back electrode. The shape of the organic compound layer,
The size and thickness can also be appropriately selected according to the purpose.

The organic compound layer may be formed by a dry film forming method or a wet film forming method. However, when the wet film forming method is used, the area of the organic compound layer can be easily increased, and high luminance and luminous efficiency can be obtained. A light-emitting element having an excellent quality can be efficiently obtained at low cost, which is preferable. As a dry film forming method, a vapor deposition method, a sputtering method, etc. can be used, and as a wet film forming method, a dipping method, a spin coating method, a dip coating method, a casting method, a die coating method,
Roll coating, bar coating, gravure coating and the like can be used. These film forming methods can be appropriately selected according to the material of the organic compound layer. When the film is formed by a wet film forming method, the film may be dried after forming the film. Drying is performed by selecting conditions such as temperature and pressure so as not to damage the coating layer.

The coating solution used in the above wet film-forming method usually comprises a material for an organic compound layer and a solvent for dissolving or dispersing the same. The solvent is not particularly limited, and may be selected according to the material used for the organic compound layer. Specific examples of the solvent include halogen solvents (chloroform, carbon tetrachloride, dichloromethane, 1,2-dichloroethane, chlorobenzene, etc.), ketone solvents (acetone, methyl ethyl ketone,
Diethyl ketone, n-propyl methyl ketone, cyclohexanone, etc., aromatic solvents (benzene, toluene, xylene, etc.), ester solvents (ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate) , Γ-butyrolactone, diethyl carbonate, etc.),
Examples include ether solvents (such as tetrahydrofuran and dioxane), amide solvents (such as dimethylformamide and dimethylacetamide), dimethylsulfoxide, and water. The amount of the solid content relative to the solvent in the coating solution is not particularly limited, and the viscosity of the coating solution can be arbitrarily selected according to the film forming method.

The light emitting device of the present invention usually emits light when a DC voltage (which may include an AC component) or a DC current of about 2 to 40 volts is applied between the transparent electrode and the back electrode. When driving the light emitting device of the present invention,
2-148687, 6-301355, 5-29080, 7-134558
No. 8-234685, No. 8-241047, U.S. Pat.
And the driving methods described in Japanese Patent No. 6023308 and Japanese Patent No. 2784615 can be used. Hereinafter, each layer constituting the light emitting laminate used in the present invention will be described in detail, but the present invention is not limited thereto.

(A) Substrate The substrate used in the present invention is preferably made of a material that does not transmit moisture or a material that has a very low moisture permeability. The material preferably does not scatter or attenuate the light emitted from the organic compound layer. Specific examples thereof include inorganic materials such as zirconia-stabilized yttrium (YSZ), glass, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polystyrene, polycarbonate, polyether sulfone,
Polyarylate, allyl diglycol carbonate, polyimide, polycycloolefin, norbornene resin,
Organic materials such as poly (chlorotrifluoroethylene) and the like can be mentioned. Among them, an organic material which is excellent in heat resistance, dimensional stability, solvent resistance, electric insulation and workability, and has low air permeability and low moisture absorption can be particularly preferably used. The substrate may be formed of a single material or may be formed of two or more materials.
The material of the base material may be appropriately selected according to the transparent electrode material,
For example, when the transparent electrode is made of indium tin oxide (ITO), it is preferable to use a material having a small difference in lattice constant from ITO.

The shape, structure, size, etc. of the substrate can be appropriately selected according to the use and purpose of the light emitting device. The shape is generally plate-like. The structure may be a single layer structure or a laminated structure. The substrate may be formed of a single member or may be formed of two or more members. The substrate may be colorless and transparent or colored and transparent, but is preferably colorless and transparent in that light emitted from the light emitting layer is not scattered or attenuated.

A moisture permeation preventing layer (gas barrier layer) may be provided on the surface of the substrate on the electrode side, the surface on the side opposite to the electrode, or both. It is preferable to use an inorganic substance such as silicon nitride or silicon oxide as a material constituting the moisture permeation preventing layer. The moisture permeation preventing layer can be formed by a high frequency sputtering method or the like. Also,
The substrate may be provided with a hard coat layer or an undercoat layer as needed.

(B) Transparent electrode Usually, the transparent electrode has a function as an anode for supplying holes to the organic compound layer, but it can also function as a cathode. In this case, the back electrode functions as an anode. Less than,
The case where the transparent electrode is used as the anode will be described.

The shape, structure, size and the like of the transparent electrode are not particularly limited, and can be appropriately selected according to the use and purpose of the light emitting device. As a material for forming the transparent electrode, a metal, an alloy, a metal oxide, an electrically conductive compound, a mixture thereof, or the like can be used, and preferably, the work function is 4 eV.
The above materials are used. Specific examples include tin oxide (ATO) doped with antimony, tin oxide (FTO) doped with fluorine, and semiconductive metal oxides (tin oxide, zinc oxide,
Indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), etc.), metals (gold, silver, chromium, nickel, etc.), mixtures or laminates of these metals and conductive metal oxides, inorganic conductive materials (Copper iodide, copper sulfide, etc.),
Organic conductive materials (polyaniline, polythiophene, polypyrrole, etc.) and laminates thereof with ITO are listed.

The transparent electrode is formed on the substrate by a wet method such as a printing method or a coating method, a physical method such as a vacuum deposition method, a sputtering method, an ion plating method, or a chemical method such as a CVD method or a plasma CVD method. Can be formed.
The formation method may be appropriately selected in consideration of suitability for the transparent electrode material. For example, when ITO is used as the material of the transparent electrode, a direct current or high frequency sputtering method, a vacuum deposition method, an ion plating method, or the like may be used. When an organic conductive material is used as the material of the transparent electrode, a wet film forming method may be used.

The patterning of the transparent electrode can be performed by chemical etching using photolithography or the like, physical etching using a laser or the like. Alternatively, patterning may be performed by vacuum evaporation using a mask, sputtering, a lift-off method, a printing method, or the like.

The position for forming the transparent electrode may be appropriately selected according to the use and purpose of the light emitting device, but is preferably formed on a substrate. At this time, the transparent electrode may be formed on the entire surface of the substrate or only on a part thereof.

The thickness of the transparent electrode may be appropriately selected according to its material, but is usually 10 nm to 50 μm, preferably 5 nm.
0 nm to 20 μm. The transparent electrode preferably has a resistance value of 10 ³ Ω / □ or less, more preferably 10 ² Ω / □ or less. The transparent electrode may be colorless and transparent or colored and transparent. In order to extract light emission from the transparent electrode side, the transmittance is preferably 60% or more, more preferably 70% or more. The transmittance can be measured according to a known method using a spectrophotometer.

Further, the electrodes described in detail in "New Development of Transparent Conductive Film" (edited by Yutaka Sawada, published by CMC, 1999) can also be applied to the present invention. In particular, when a plastic substrate having low heat resistance is used, it is preferable to use ITO or IZO as a transparent electrode material and form a film at a low temperature of 150 ° C. or lower.

(C) Back Electrode Normally, the back electrode has a function as a cathode for injecting electrons into the organic compound layer, but can also function as an anode. In this case, the transparent electrode functions as a cathode. Hereinafter, a case where the back electrode is a cathode will be described.

The shape, structure, size, and the like of the back electrode are not particularly limited, and can be appropriately selected according to the use and purpose of the light emitting device. As a material for forming the back electrode, a metal, an alloy, a metal oxide, an electrically conductive compound, a mixture thereof, or the like can be used.
Use the material below V. Specific examples include alkali metals (Li, Na, K, Cs, etc.) and alkaline earth metals (Mg, Ca
Etc.), gold, silver, lead, aluminum, sodium-potassium alloy, lithium-aluminum alloy, magnesium-
Silver alloy, indium, rare earth metal (ytterbium, etc.)
And the like. These may be used alone, but it is preferable to use two or more of them in order to achieve both stability and electron injection properties. Among these materials, alkali metals and alkaline earth metals are preferable from the viewpoint of electron injecting property, and materials mainly composed of aluminum are preferable from the viewpoint of storage stability. Here, the material mainly composed of aluminum refers to aluminum alone, an alloy or a mixture of aluminum and 0.01 to 10% by mass of an alkali metal or an alkaline earth metal (such as a lithium-aluminum alloy and a magnesium-aluminum alloy). As the material of the back electrode,
Those described in detail in JP-A-2-15595 and JP-A-5-121172 can also be used.

The back electrode can be formed by a wet method such as a printing method or a coating method, a physical method such as a vacuum evaporation method, a sputtering method, an ion plating method, or a chemical method such as a CVD method or a plasma CVD method. it can. The formation method may be appropriately selected in consideration of suitability with the back electrode material. For example, when two or more kinds of metals or the like are used as the material of the back electrode, the materials can be formed by sputtering the materials simultaneously or sequentially.

The patterning of the back electrode can be performed by chemical etching using photolithography or the like, physical etching using a laser or the like. Alternatively, patterning may be performed by vacuum evaporation using a mask, sputtering, a lift-off method, a printing method, or the like.

The formation position of the back electrode may be appropriately selected according to the use and purpose of the light emitting device, but is preferably formed on the organic compound layer. At this time, the back electrode may be formed on the entire surface of the organic compound layer or only on a part thereof. Further, a dielectric layer made of an alkali metal or alkaline earth metal fluoride is provided between the back electrode and the organic compound layer by 0.1.
It may be installed with a thickness of ５5 nm. The dielectric layer can be formed by a vacuum deposition method, a sputtering method, an ion plating method, or the like.

The thickness of the back electrode may be appropriately selected according to its material, but is usually 10 nm to 5 μm, preferably 5 nm.
0 nm to 1 μm. The back electrode may be transparent or opaque. The transparent back electrode is composed of one layer of the material described above.
A thin film having a thickness of about 10 nm may be formed, and a transparent conductive material such as ITO or IZO may be laminated.

(D) Light Emitting Layer In the light emitting device of the present invention, the light emitting layer contains a phosphorescent compound. The phosphorescent compound used in the present invention is not particularly limited as long as it can emit light from triplet excitons. As the phosphorescent compound, an orthometalated complex or a porphyrin complex is preferably used, and an orthometalated complex is more preferably used. Among porphyrin complexes, porphyrin platinum complexes are preferred. The phosphorescent compounds may be used alone or in combination of two or more.

The orthometalated complex referred to in the present invention is described in "Basic and applied organometallic chemistry" by Akio Yamamoto, p.
Page, Shokabosha (1982), Photochemistr by H. Yersin
y and Photophysics of Coordination Compounds, '' 71
-77 and 135-146, Springer-Verlag (1987)
Etc. are generic names of the compound groups described in the above. The ligand forming the orthometalated complex is not particularly limited, but may be a 2-phenylpyridine derivative, a 7,8-benzoquinoline derivative,
It is preferably a (2-thienyl) pyridine derivative, a 2- (1-naphthyl) pyridine derivative or a 2-phenylquinoline derivative. These derivatives may have a substituent. Further, other ligands may be included in addition to the ligands essential for forming these ortho-metalated complexes. As the central metal forming the orthometalated complex, any transition metal can be used, and in the present invention, rhodium, platinum, gold, iridium, ruthenium, palladium and the like can be preferably used. Of these, iridium is particularly preferred. The organic compound layer containing such an ortho-metalated complex is excellent in light emission luminance and light emission efficiency. Specific examples of the orthometalated complex are also described in Japanese Patent Application No. 2000-254171, paragraphs 0152 to 0180.

The orthometalated complex used in the present invention is In
org. Chem., 30, 1685, 1991; Inorg. Chem., 27, 346.
4, 1988, Inorg. Chem., 33, 545, 1994, Inorg. Chim.
Acta, 181, 245, 1991; J. Organomet. Chem., 335, 2
93, 1987, J. Am. Chem. Soc., 107, 1431, 1985 and the like.

The content of the phosphorescent compound in the light emitting layer is not particularly limited, but is, for example, 0.1 to 70% by mass,
It is preferably 0% by mass. When the content of the phosphorescent compound is less than 0.1% by mass or more than 70% by mass, the effect may not be sufficiently exhibited.

In the present invention, the light emitting layer may contain a host compound, a hole transporting material, an electron transporting material, an electrically inactive polymer binder, and the like, if necessary.

The above-mentioned host compound is a compound that causes energy transfer from its excited state to the phosphorescent compound, thereby causing the phosphorescent compound to emit light. Specific examples thereof 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, and styryl anthracene 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, thiopyrandioxide Derivatives, carbodiimide derivatives, fluorenylidenemethane derivatives, distyrylpyrazine derivatives, and naphthaleneperylene Carboxylic acid anhydrides, phthalocyanine derivatives, 8-quinolinol derivative metal complexes, metal phthalocyanine, metal complexes having benzoxazole or benzothiazole as a ligand, polysilane compounds, poly (N-
(Vinyl carbazole) derivatives, aniline copolymers, thiophene oligomers, conductive polymers such as polythiophene,
Examples thereof include a polythiophene derivative, a polyphenylene derivative, a polyphenylenevinylene derivative, and a polyfluorene derivative. The host compound may be used alone or in combination of two or more.

The hole transport material is not particularly limited as long as it has any of a function of injecting holes from the anode, a function of transporting holes, and a function of blocking electrons injected from the cathode. Alternatively, it may be a low molecular material or a high molecular material. Specific examples thereof 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 derivative, hydrazone derivative, stilbene derivative, silazane derivative, aromatic tertiary amine compound, styrylamine compound, aromatic dimethylidene compound, porphyrin compound, polysilane compound, poly (N-vinylcarbazole) derivative, aniline copolymer, thiophene Examples thereof include oligomers, conductive polymers such as polythiophene, polythiophene derivatives, polyphenylene derivatives, polyphenylenevinylene derivatives, and polyfluorene derivatives. These may be used alone or in combination of two or more.

The electron transporting material is not particularly limited as long as it has any of a function of injecting electrons from the cathode, a function of transporting electrons, and a function of blocking holes injected from the anode. For example, triazole derivatives, oxazole derivatives, oxadiazole derivatives, fluorenone derivatives, anthraquinodimethane derivatives, anthrone derivatives,
Diphenylquinone derivatives, thiopyrandioxide derivatives, carbodiimide derivatives, fluorenylidenemethane derivatives, distyrylpyrazine derivatives, heterocyclic tetracarboxylic anhydrides such as naphthaleneperylene, phthalocyanine derivatives, metal complexes of 8-quinolinol derivatives, metallophthalocyanines, Metal complexes having benzoxazole or benzothiazole as ligands, aniline copolymers, thiophene oligomers, conductive polymers such as polythiophene, polythiophene derivatives, polyphenylene derivatives, polyphenylenevinylene derivatives, polyfluorene derivatives, etc. can be used. .

As the polymer binder, 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 and the like can be used. The light emitting layer containing the polymer binder can be easily applied to a large area by a wet film forming method.

The thickness of the light emitting layer is preferably from 10 to 200 nm, more preferably from 20 to 80 nm. 200nm thickness
If it exceeds, the driving voltage may increase, and if it is less than 10 nm, the light emitting element may be short-circuited.

(E) Electron Transport Layer The light emitting device of the present invention may have an electron transport layer made of the above-described electron transport material, if necessary. The electron transport layer may contain the polymer binder described above. The thickness of the electron transport layer is preferably from 10 to 200 nm, more preferably from 20 to 80 nm. When the thickness exceeds 200 nm, the driving voltage may increase, and when the thickness is less than 10 nm, the light emitting element may short-circuit.

(F) Hole Transport Layer The light emitting device of the present invention may have a hole transport layer made of the above-described hole transport material, if necessary. The hole transport layer may contain the polymer binder described above. The thickness of the hole transport layer is preferably from 10 to 200 nm, more preferably from 20 to 80 nm. When the thickness exceeds 200 nm, the driving voltage may increase, and when the thickness is less than 10 nm, the light emitting element may short-circuit.

(G) Others The light emitting device of the present invention is disclosed in JP-A-7-85974 and JP-A-7-192866.
, No. 8-22891, No. 10-275682, No. 10-106746 and the like. The protective layer is formed on the uppermost surface of the light emitting device. Here, the uppermost surface refers to the outer surface of the back electrode when the base material, the transparent electrode, the organic compound layer and the back electrode are laminated in this order, and the base material, the back electrode, the organic compound layer and the transparent electrode in this order. When laminating, it refers to the outer surface of the transparent electrode. The shape, size, thickness and the like of the protective layer are not particularly limited. The material forming the protective layer is not particularly limited as long as it has a function of preventing the light emitting element such as moisture or oxygen from deteriorating or permeating into the element. Silicon, germanium oxide, germanium dioxide and the like can be used.

The method for forming the protective layer is not particularly limited, and examples thereof include a vacuum deposition method, a sputtering method, a reactive sputtering method, a molecular epitaxy method, a cluster ion beam method, an ion plating method, a plasma polymerization method, a plasma CVD method, Laser CVD, thermal CVD, coating, etc. can be applied.

It is preferable that the light emitting element is provided with a sealing layer for preventing intrusion of moisture or oxygen. As a material for forming the sealing layer, a copolymer of tetrafluoroethylene and at least one comonomer, a fluorinated copolymer having a cyclic structure in the copolymer main chain, polyethylene, polypropylene, polymethyl methacrylate, polyimide, Polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, chlorotrifluoroethylene or copolymer of dichlorodifluoroethylene with other comonomers, water absorption 1%
The above water-absorbing substances, moisture-proof substances having a water absorption of 0.1% or less, metals (In, Sn, Pb, Au, Cu, Ag, Al, Tl, Ni, etc.), metal oxides (MgO, SiO, SiO ₂ , Al ₂ O ₃ , GeO, NiO, CaO, BaO, F
e ₂ O ₃ , Y ₂ O ₃ , TiO ₂ etc.), metal fluorides (MgF ₂ , LiF, AlF
₃ , CaF ₂ etc.), liquid fluorinated carbon (perfluoroalkane, perfluoroamine, perfluoroether etc.),
What disperse | distributed the adsorbent of moisture and oxygen in this liquid fluorinated carbon etc. can be used.

[0053]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

Example 1 A glass plate having a thickness of 0.2 mm was cut into 2.5 cm square to prepare a substrate, which was introduced into a vacuum chamber. On this substrate, a DC magnetron sputtering (condition: substrate temperature of 100 ° C., using an ITO target having a SnO ₂ content of 10% by mass).
An ITO transparent electrode was formed at an oxygen pressure of 1 × 10 ⁻³ Pa). The thickness of the transparent electrode was 0.2 μm, and the surface resistance was 10Ω / □.

The substrate on which the transparent electrode is formed is placed in a cleaning container.
After IPA cleaning, UV-ozone treatment was performed for 30 minutes. Subsequently, N, N'-dinaphthyl-N, N'-diphenylbensidine was vacuum-deposited on the transparent electrode at a rate of 1 nm / sec to a thickness of 0.04 μm.
An m hole transport layer was formed. Next, a tris (2-phenylpyridine) iridium complex (phosphorescent material) and 4,4′-N, N′-dicarbazolebiphenyl (host material) were placed on the hole transport layer at 0.1 nm / sec and 1 nm / Co-evaporation was performed at a speed of seconds to form a light emitting layer having a thickness of 0.024 μm. Furthermore, 2,2 ', 2''-(1,3,5-benzenetriyl) tris [3-
(2-Methylphenyl) -3H-imidazo [4,5-b] pyridine]
An electron transport layer having a thickness of 0.024 μm was formed by vapor deposition at a speed of nm / sec.

A patterned mask (a mask having a light emitting area of 5 mm × 5 mm) was set on the obtained electron transport layer, and a magnesium / silver alloy (magnesium: silver = 10: 1 (molar ratio)) was set in a vapor deposition apparatus. 0.25 μm and silver 0.3
A back electrode was formed by μm evaporation. An aluminum lead wire was connected from the transparent electrode and the back electrode to form a light-emitting laminate.

A stainless steel sealing cover provided with a concave portion inside was placed in a glove box replaced with nitrogen gas, and 10 mg of magnesium powder as an oxygen adsorbent was placed in the concave portion and fixed with an adhesive tape. Subsequently, the light-emitting laminate obtained as described above was put into this glove box, and sealed with an ultraviolet-curing adhesive (XNR5493, manufactured by Chise Nagase, Ltd.) with the sealing cover provided with an oxygen adsorbent. Example 1 A light-emitting element of Example 1 having the same configuration as the element shown in FIG.

[0058] Similarly, except for using FeO powder in place of the Example 2 Magnesium powder of Example 1 to prepare a light-emitting device of Example 2.

[0059] Similarly, except for using 2,6-di -t- butyl-4-methylphenol powder in place Example 3 Magnesium powder as in Example 1 to prepare a light-emitting device of Example 3.

[0060] Similarly, except for using triphenyl phosphite powder in place of Example 4 Magnesium powder as in Example 1 to prepare a light-emitting element of Example 4.

[0061] Similarly, except for not fixed to the magnesium powder in the recess of the comparative example 1 the sealing cover as in Example 1 to prepare a light-emitting device of Comparative Example 1.

Evaluation of Light Emission Luminance and Emission Efficiency Using a source measure unit 2400 manufactured by Toyo Technica, a DC voltage was applied to each light emitting element obtained as described above to emit light, and the luminance was measured. Maximum brightness
L _max, the voltage V _max when the maximum luminance L _max is obtained, the luminance 20
Luminous efficiency η ₂₀₀ when emitted at 0 cd / m ² , luminance 2000 cd /
Luminous efficiency η ₂₀₀₀ when emitted at m ² (external quantum efficiency)
I asked. The maximum luminance L _max , voltage V _max , and luminous efficiencies η ₂₀₀ and η ₂₀₀₀ after leaving each light-emitting element under a high-temperature and high-humidity condition of 85 ° C. and 95% RH for 30 days were evaluated for durability. . Table 1 shows the results.

[0063]

[Table 1]

As shown in Table 1, the light emitting device of Comparative Example 1 in which no material for adsorbing oxygen or a material reacting with oxygen was used exhibited low light emission luminance and light emission efficiency, and its durability was poor. In comparison, the light emitting devices of Examples 1 to 4 of the present invention exhibited excellent light emission luminance, light emission efficiency and durability.

[0065]

As described in detail above, the light emitting device of the present invention, which effectively utilizes triplet excitons, is excellent in light emission luminance, light emission efficiency, and durability, and is suitable for full color displays, backlights, illumination light sources, and the like. Surface light sources, light source arrays such as printers, and the like.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one embodiment of a light emitting device of the present invention.

FIG. 2 is a schematic sectional view showing one embodiment of the light emitting device of the present invention.

FIG. 3 is a schematic sectional view showing one embodiment of the light emitting device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... Transparent electrode 3 ... Organic compound layer 4 ... Back electrode 5 ... Transparent electrode lead 6 ... Back electrode lead 7 ... Light emitting laminated body 8 ... Sealant (adhesive) 9 Sealing member 10 Space 11 Concavity 12 Material that adsorbs oxygen or reacts with oxygen

Claims (1)

[Claims] 1. A light-emitting laminate comprising a transparent electrode, one or more organic compound layers including a light-emitting layer containing a phosphorescent compound, and a back electrode laminated on a base material, and the organic compound layer formed by external air. In a light-emitting element having a sealing member that blocks light from a light-emitting element, a material that adsorbs oxygen or reacts with oxygen is provided in a space between the light-emitting laminate and the sealing member. Light emitting element.