JP4438459B2 - Material for organic phosphorescent light emitting device and organic phosphorescent light emitting device using the same - Google Patents

Description

  The present invention relates to a material for an organic phosphorescent light emitting device used for a flat light source and a display, and a light emitting device with high luminance and high efficiency.

  An organic electroluminescence (EL) element using an organic substance is expected to be used as an inexpensive large-area full-color display element of a solid light emitting type and has been developed in many ways. In general, an organic EL element is composed of 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 side, holes are injected from the anode side, the electrons recombine with holes in the light emitting layer, and the energy level starts from the conduction band. It is a phenomenon in which energy is released as light when returning to the valence band.

Conventional organic EL elements have a higher driving voltage and lower light emission luminance and light emission efficiency than inorganic EL elements. Further, the characteristic deterioration has been remarkably not put into practical use.
In recent years, organic EL elements in which thin films containing organic compounds having high fluorescence quantum efficiency that emit light at a low voltage of 10 V or less have been reported and attracted interest (see Non-Patent Document 1). This method uses a metal chelate complex as a light emitting layer and an amine compound as a hole injection layer to obtain a high luminance green light emission. The luminance is several thousand cd / m ² at a direct current voltage of 6 to 7 V, maximum. The luminous efficiency is 1.5 lm / W, and the performance is close to the practical range (see Non-Patent Document 1).

  Furthermore, an organic EL element using light emission from a triplet excited state (hereinafter, abbreviated as an organic phosphorescent light emitting element), which has greatly improved efficiency, compared to a conventional organic EL element using a singlet excited state, has been reported. It has attracted attention (see Non-Patent Documents 2 and 3).

  Many of the organic phosphorescent light emitting devices so far contain a compound having a carbazole skeleton as shown in the following compound (hereinafter abbreviated as CBP). However, these compounds have very high crystallinity and it is difficult to obtain a stable film. Therefore, organic phosphorescent light emitting devices using these materials have a problem that their lifetime is short. Further, these compounds have hole transport properties, but due to their high ionization potential, there is a tendency that injected holes tend to escape to the cathode side. In order to improve this, a hole blocking layer is inserted on the cathode side. However, commonly used bathophenanthroline, bathocuproine, etc. have very high crystallinity and often become unstable films. In addition, other blocking materials could not provide sufficient characteristics. Therefore, a significant improvement in lifetime or initial characteristics can be expected by improving at least one of the materials.

CBP

On the other hand, a metal complex having tropolone, which is a seven-membered ring compound, and a derivative thereof as a ligand has photoluminescence characteristics and electron transport properties, and has a three-dimensionally bulky structure due to complexation. High film stability can be expected. For this reason, it is expected that it can be suitably used for an electron injection / transport layer and an electron transporting light emitting layer of an organic EL element, and examples of actual application to an organic EL element are already known (see Patent Document 1). However, only a few examples of organic EL elements using fluorescent emission are described, and no application examples to organic phosphorescent light emitting elements are found.
Applied Physics Letters, 51, 913, 1987 Nature, 395, 151 pages, 1998 Applied Physics Letters, 75, 4 pages, 1999 Japanese Patent Laid-Open No. 9-157642

  An object of the present invention is to provide an organic phosphorescent light emitting device material having high luminance and luminous efficiency and excellent stability during repeated use, and an organic phosphorescent light emitting device using the same.

The present invention relates to a material for an organic phosphorescent device comprising a metal complex compound (A) represented by the following general formula [1] and a phosphorescent material (B) other than the metal complex compound (A) .

General formula [1]

[Wherein, X ¹ and X ² are each independently any one of O, S and NR;
R and R ^{1 to} R ⁵ are each independently a hydrogen atom, a halogen atom, a cyano group, a nitro group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, A substituted or unsubstituted alkylthio group, a substituted or unsubstituted arylthio group, a substituted or unsubstituted amino group, a substituted or unsubstituted acyl group, a substituted or unsubstituted carbocyclic group, a substituted or unsubstituted heterocyclic group; is there. The adjacent substituents may be integrated to form a ring.
A ligand containing a 7-membered ring having the above structure becomes an anionic ligand, and when a plurality of ligands are coordinated, each may be the same or different.
n is 1 or more and up to the cation valence of M.
M represents a metal selected from Group 1 or Group 14 of the periodic table, X ¹ double-bonded to the seven-membered ring is coordinated to metal atom M, and X ² single-bonded to the seven-membered ring is metal atom M Covalently join.
L is a monodentate or bidentate ligand composed of an organic compound or an organic residue other than the above ligand, or a partial structure bonded to the other metal in the polynuclear complex via an oxygen atom or an organic ligand. To express. L may have two or more of the same or different.
n ′ represents the number of L and may be 0.
The sum of the anion valences of the ligand containing the seven-membered ring and the ligand L matches the cation valence of the metal atom M so as to form an electrically neutral complex as a whole.
The ligand containing a 7-membered ring and L may be bonded to each other at a portion other than the metal atom M between the ligands. ]

  The present invention also relates to the above organic phosphorescent light emitting device material wherein n ′ is 0.

  The present invention also relates to the material for an organic phosphorescent light emitting device, wherein M is a rare earth or a metal selected from any of Groups 6 to 11 of the periodic table.

  The present invention also relates to the above organic phosphorescent light emitting device material, wherein M is a metal selected from the group 8 or group 10 of the periodic table and the platinum group element of the fifth or sixth period.

  The present invention also relates to the above organic phosphorescent light emitting device material, wherein M is a metal selected from Group 1, Group 2, Group 3, Group 12, or Group 13 of the Periodic Table.

  The present invention also relates to the above organic phosphorescent light emitting device material, wherein M is any one of Mg, Ca, Zn, Al, and Ga.

  The present invention also relates to the above organic phosphorescent light emitting device material, wherein the phosphorescent light emitting material (B) comprises an iridium or platinum complex comprising an organic compound or a ligand of an organic residue.

  The present invention also provides an organic phosphorescent light-emitting device in which a light-emitting layer or a plurality of organic compound thin films including a light-emitting layer is formed between a pair of electrodes, wherein the light-emitting layer contains the organic phosphorescent light-emitting device material. The present invention relates to a light emitting element.

  In the present invention, the content of the metal complex compound (A) in which M is a metal selected from Group 1, Group 2, Group 12, Group 12, or Group 13 of the periodic table is such that the entire light emitting layer is contained in the light emitting layer. The organic phosphorescent light-emitting device occupying 50% by weight or more of the above.

  In the present invention, the content of the metal complex compound (A) in which M is a rare earth or a metal selected from Group 6 or Group 11 of the periodic table is less than 50% by weight of the entire light emitting layer in the light emitting layer. The above organic phosphorescent light emitting device.

  The present invention further relates to the above organic phosphorescent light emitting device, wherein an electron injection layer is formed between the cathode and the light emitting layer.

  The present invention further relates to the organic phosphorescent light emitting device, wherein a hole blocking layer is formed between the electron injection layer and the light emitting layer.

  The present invention further relates to the organic phosphorescent light emitting device, wherein a hole injection layer is formed between the anode and the light emitting layer.

  The material for an organic phosphorescent light emitting device of the present invention is particularly excellent in stability, and an organic phosphorescent light emitting device using the material has excellent initial characteristics such as luminance and luminous efficiency, and has a long light emitting lifetime and good environmental characteristics. It is an organic phosphorescent light emitting device.

  That is, the present invention provides an organic phosphorescent light-emitting device in which an organic layer having a light-emitting region is provided between an anode and a cathode, and includes an organic substance that emits light from a triplet excited state by current injection as a constituent element. When the compound shown in the present invention is contained, the device is characterized in that it has excellent device performance and durability due to its electrical properties and chemical stability.

Hereinafter, the metal complex compound (A) of the present invention will be specifically described.
A feature of the metal complex compound (A) of the present invention is that the ligand has a seven-membered carbocyclic ring, and the adjacent positions thereof have two heteroatoms having a lone pair of electrons (X ¹ , X 1 in the general formula [1] ² ), one of which (X ¹ ) has a ring and a double bond, and the other (X ² ) has a ring and a single bond. Ligand before forming a complex with a metal is a hydrogen atom is bonded to X ^2. Specifically, the heteroatoms X ¹ and X ² are any one of O, S, and NR (R is a general substituent), and the combination is not particularly limited. A typical example of this ligand structure is tropolone in which both X ¹ and X ² are oxygen atoms, and a natural product called hinokitiol is well known as a derivative. Hereinafter, the ligand that characterizes the present invention is referred to as a tropolone-based ligand.

In the metal complex compound (A) of the present invention, the substituent R of NR as an example of the above-mentioned heteroatoms X ¹ and X ² , and R ^{1 to} R ⁵ of the general formula [1] are hydrogen atoms or the following general ones Is a typical substituent. Specific types include halogen atoms, cyano groups, nitro groups, substituted or unsubstituted alkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted aryloxy groups, substituted or unsubstituted alkylthio groups, substituted Alternatively, an unsubstituted arylthio group, a substituted or unsubstituted amino group, a substituted or unsubstituted acyl group, or a substituted or unsubstituted carbocyclic group or heterocyclic group can be mentioned. In the following, more detailed representative examples of each substituent will be shown, but the present invention is not limited thereto, and these substituents may further have a substituent bonded thereto. Furthermore, these substituents may form a ring with adjacent substituents.

  Examples of the halogen atom serving as a substituent in the present invention include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

  Examples of the substituted or unsubstituted alkyl group in the present invention include methyl group, ethyl group, propyl group, butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, stearyl group, 2-phenylisopropyl group, trichloromethyl group, trifluoromethyl group, benzyl group, α-phenoxybenzyl group, α, α-dimethylbenzyl group, α, α-methylphenylbenzyl group, α, α-ditrifluoromethylbenzyl group , Triphenylmethyl group, α-benzyloxybenzyl group and the like.

  Examples of the substituted or unsubstituted alkoxy group in the present invention include an unsubstituted alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a tert-butoxy group, an octyloxy group, and a tert-octyloxy group; , 3-trifluoroethoxy group, and substituted alkoxy group such as benzyloxy group.

  Examples of the substituted or unsubstituted aryloxy group in the present invention include unsubstituted aryloxy groups such as phenoxy group, 4-tert-butylphenoxy group, 1-naphthyloxy group, 2-naphthyloxy group, and 9-anthryloxy group. And substituted aryloxy groups such as 4-nitrophenoxy group, 3-fluorophenoxy group, pentafluorophenoxy group and 3-trifluoromethylphenoxy group.

  Examples of the substituted or unsubstituted alkylthio group in the present invention include an unsubstituted alkylthio group such as methylthio group, ethylthio group, tert-butylthio group, hexylthio group, and octylthio group, 1,1,1-tetrafluoroethylthio group, And substituted alkylthio groups such as benzylthio group and trifluoromethylthio group.

  Examples of the substituted or unsubstituted arylthio group in the present invention include an unsubstituted arylthio group such as a phenylthio group, a 2-methylphenylthio group, and a 4-tert-butylphenylthio group, a 3-fluorophenylthio group, and a pentafluorophenylthio group. And substituted arylthio groups such as a 3-trifluoromethylphenylthio group.

  Examples of the substituted or unsubstituted amino group in the present invention include an amino group, a mono- or dialkylamino group, a mono- or diarylamino group, and an alkylarylamino group. Specific examples of the alkylamino group include an ethylamino group, a diethylamino group, a dipropylamino group, a dibutylamino group, a benzylamino group, and a dibenzylamino group. Specific examples of the arylamino group include a phenylamino group, ( 3-methylphenyl) amino group, (4-methylphenyl) amino group, etc. Specific examples of the arylamino group include phenylamino group, phenylmethylamino group, diphenylamino group, ditolylamino group, dibiphenylylamino group Di (4-methylbiphenyl) amino group, di (3-methylphenyl) amino group, di (4-methylphenyl) amino group, naphthylphenylamino group, bis [4- (α, α'-dimethylbenzyl) phenyl There are amino groups and the like. Specific examples of the alkylarylamino group include an N-ethyl-N-phenylamino group and an N-methyl-N-naphthylamino group. Also included are structures in which substituents to amino groups such as bis (methoxyphenyl) amino group and bis (acetoxyethyl) amino group are further substituted.

  Examples of the substituted or unsubstituted acyl group in the present invention include formyl group, acetyl group, propionyl group, butyryl group, isobutyryl group, valeryl group, isovaleryl group, pivaloyl group, hexanoyl group, octanoyl group, acryloyl group, and methacryloyl group. Alkyl-substituted acyl groups such as alkyl-substituted acyl groups, benzoyl groups, toluoyl groups, naphthoyl groups, and other cyclohexylcarbonyl groups, chloroformyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, (N-substituted) carbamoyl groups, etc. There is.

  The substituted or unsubstituted carbocyclic group in the present invention includes a monocyclic group or a condensed polycyclic group.

  Specific examples of the monocyclic group include a monocyclic cycloalkyl group and a monocyclic aryl group.

  Examples of the monocyclic cycloalkyl group include cycloalkyl groups such as a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group.

  A monocyclic aryl group includes a phenyl group.

  Examples of the substituted or unsubstituted condensed polycyclic group include a condensed polycyclic aryl group and a condensed polycyclic cycloalkyl group.

  Examples of the condensed polycyclic aryl group include a naphthyl group, anthryl group, phenanthryl group, fluorenyl group, acenaphthyl group, azulenyl group, heptaenyl group, pyrenyl group, perylenyl group, and triphenylenyl group.

  Examples of the substituted or unsubstituted heterocyclic group in the present invention include a monocyclic heterocyclic group and a condensed polycyclic heterocyclic group.

Examples of monocyclic heterocyclic groups include thienyl, furyl, pyrrolyl, imidazolyl, pyrazolyl, pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl, triazinyl, triazolyl, oxazolyl, thiazolyl, oxadiazolyl, There are thiadiazolyl and imidadiazolyl groups.
As the condensed polycyclic heterocyclic group, indolyl group, quinolyl group, isoquinolyl group, phthalazinyl group, quinoxalinyl group, quinazolinyl group, carbazolyl group, acridinyl group, phenazinyl group, benzofuryl group, isothiazolyl group, isoxazolyl group, furazanyl group, phenoxazinyl group Benzothiazolyl group, benzoxazolyl group, benzimidazolyl group, benzotriazolyl group, pyranyl group and the like. Examples of other condensed polycyclic groups include 1-tetralyl group, 2-tetralyl group, tetrahydroquinolyl group and the like.

Here, when the hydrogen atom of X ² is desorbed from the structure, the tropolone-based ligand becomes a monovalent anionic ligand and can form a complex with a metal atom. At this time, X ¹ is coordinated to a metal atom, and X ² is covalently bonded to the metal atom. However, after complex formation, X ¹ and X ² can be interchanged by the resonance structure without recombination of the bonds, so that it is not usually necessary to distinguish them.

  In general, the metal atom M in the present invention may be anything as long as it is an atom that forms some complex. Specifically, it is a metal selected from Group 1 to Group 14 of the Periodic Table, and includes metals belonging to alkali metals, alkaline earth metals, rare earth-containing transition metals, zinc group, boron group and carbon group.

  Preferably, the metal atom M is a metal selected from Group 1, 2, 3, 12, or 13 of the periodic table, and more preferably Mg, Ca, Zn, Al, or Ga. In the present invention, the reason why the group 2 Be is excluded from the particularly preferable metal is that it is not preferable to use it widely industrially because toxicity is pointed out. However, it does not mean that the characteristics are inferior or technically problematic. In the case of the complex compound (A) composed of these metals, it is preferable to use it as a host material, an electron injection material, or a hole blocking material in a light emitting layer described later. The ratio in the light emitting layer as the host material is preferably 50% by weight or more based on the entire light emitting layer.

  In another preferred embodiment, the metal atom M is a rare earth or a metal selected from any one of Groups 6 to 11 of the periodic table, more preferably the Groups 8 to 10 of the periodic table, and the 5th or 6th period. It is a metal selected from platinum group elements with a period. More specifically, iridium or platinum can be mentioned. In the case of the complex compound (A) composed of these metals, it is suitable to be used as a dopant material in a light emitting layer to be described later, and in particular, it is used as a doping material having phosphorescence, that is, one kind of phosphorescent light emitting material (B). Is good. Moreover, it is preferable that the ratio in the light emitting layer as a doping material is less than 50 weight% with respect to the whole light emitting layer.

  In the present invention, when a plurality of ligands are coordinated to a metal atom, the above tropolone-based ligands may be completely the same, but the partial types such as the types of substituents and heteroatoms may be partially different. It doesn't matter. Moreover, you may have the ligand L which consists of an organic compound or organic residue which is not the category of the said tropolone-type ligand. This ligand is a monodentate ligand that coordinates to the metal with only one atom, or a bidentate ligand that coordinates with two atoms. However, a bidentate ligand is preferred from the viewpoint of the stability of the complex. It is also conceivable that three or more atoms are coordinated to one atom at the same time. In this case, it can be considered that the ligands have formed a bond. Furthermore, a polynuclear complex in which one ligand is simultaneously coordinated to two or more metal atoms is also conceivable. In this case, the bridging ligand that connects two or more metal atoms may be an organic ligand or a divalent anionic oxygen atom. In this polynuclear complex, the tropolone-based ligand may be coordinated to only one metal, or may be present on a plurality or all of the metals. However, it is preferable that other than the bridging ligand is a tropolone-based ligand.

  In the present invention, what kind of ligand is coordinated depends on various complex factors such as the number of coordination of metal atoms, the size in the space of the ligand, and the positional relationship of the coordination atoms. Although it cannot be expressed in a single word, generally, in the case of a metal atom having a cation valence of 2 or more, the coordination number is often 4-coordinate or 6-coordinated. In the case of a monovalent alkali metal, it is two-coordinated, and in most cases, only one tropolone-based ligand is coordinated. In addition, rare earth metals sometimes take eight coordination. Depending on the ligand, 6 atoms cannot enter the coordination site at the same time due to spatial restrictions and stability, and may be 5-coordinated. However, in the case of the present invention, it is desirable that the entire complex be neutral in terms of charge from the viewpoint of forming a film by vapor deposition or forming a film having high electrical properties in wet coating. For this reason, the sum total of the anion valence which consists of a tropolone-type ligand and the other ligand L needs to correspond with the cation valence of a metal. Therefore, when the coordination number is twice the valence, that is, in the case of divalent tetracoordinated Zn or trivalent hexacoordinated Al, only the tropolone-based ligand that is a monovalent anionic ligand, Alternatively, a neutral complex can be formed with other monovalent ligands, but in the case where the coordination number is not twice the valence, for example, in the case of divalent hexacoordinated Ru or trivalent octacoordinated Eu. Needs to add a charge neutral zero-valent ligand. In addition, when a monodentate ligand is used, valence adjustment is required as a whole.

  In the present invention, it is not restricted that the types of a plurality of ligands entering one metal atom are different, but from the viewpoint of the stability of the complex, it is possible that a ligand having similar properties may enter. The weak part is difficult because it is difficult to make. That is, a complex formed only with a monovalent anionic ligand is preferable as long as it is a neutral complex and is not subject to spatial restrictions. In the present invention, a complex formed only with a tropolone-based ligand is more preferable.

  In the present invention, tropolone-based ligands, other ligands, or tropolone-based ligands and other ligands may be bonded at a portion other than the metal atom M. In some cases, one fused ring may be formed by linking.

  In the metal complex compound (A) of the present invention, an aqueous solution in which a metal salt as a central atom is dissolved is added to a solution in which a corresponding tropolone-based ligand is dissolved in an organic solvent, and neutralized with an alkali as necessary. Can be obtained. In the case of an alkali metal complex, an alkali metal hydroxide can also be used. In the case of a complex other than an alkali metal, it can also be obtained by once synthesizing an alkali metal complex and then mixing this aqueous solution with an aqueous solution of a corresponding metal salt. As the metal salt, a metal inorganic salt or a metal organic salt can be used. Specific examples of metal inorganic salts include hydrochlorides, sulfates, sulfites, nitrates, nitrites, and carbonates. Metal organic salts include formate, acetate, propionate, and oxalate. , Gluconate, naphthenate and the like, but are not particularly limited thereto. In addition, as the organic solvent for dissolving the tropolone-based ligand, alcohol-based solvents such as methanol, ethanol, and 2-propanol are used. In the case of a ligand that is hardly soluble in alcohols, other soluble solvents such as dimethylformamide and tetrahydrofuran may be used.

  Details of the method for synthesizing the complex are described in, for example, H.C. Iinuma, J .; Chem. Soc. Japan, 64, 742 (1943), B.I. E. Bryant et al. , J .; Am. Chem. Soc. 75, 3784 (1953). As for the synthesis of the tropolone derivative serving as a ligand, Daigaku Organic Chemistry Vol. 13, “Non-benzene aromatic ring compounds”, 1960, published by Asakura Shoten et al. 15 “New Aromatic Chemistry” edited by the Chemical Society of Japan, 1977, published by the Society Publishing Center, page 101 and beyond.

  When it is composed of two or more tropolone-based ligands, when it contains a ligand other than the tropolone-based ligand, in the case of a polynuclear complex, the ratio of compounds to be ligands, the order of addition, substitution of metals and ligands It is prepared by using. Separation and purification are performed as necessary.

Although the typical example of the metal complex compound (A) of this invention is specifically illustrated below, this invention is not limited to this representative example. Note that heteroatoms (single bonds and double bonds, coordination bonds and covalent bonds) corresponding to the general formulas X ¹ and X ² in the structural formula can be interchanged by resonance as described above. They are not separately written, nor are they more stable structures selected when the atomic species are different or when there are (especially highly polar) ring substituents.

  Since the metal complex compound (A) in the present invention has an electron withdrawing group, the electron transport property is generally good. An electron-withdrawing group having a double bond such as a carbonyl group can be expected to stabilize the triplet excited state. This electron-withdrawing group has an effect of enhancing conjugation by conjugation and complexation in the ligand. Furthermore, it is possible to form an electronic interaction with other ligands through or through metal atoms. Because the action is strengthened, the interaction between electron-attracting groups and the influence of the electronic influence on the whole molecule are made, and the stronger effect is exerted on the electron transport property and the stability of the triplet excited state. become. Further, the complexation increases the molecular rigidity, has a high structural stability, and has a high glass transition point and melting point. For this reason, resistance to Joule heat (heat resistance) generated in the organic layer, between the organic layers, or between the organic layer and the metal electrode during electroluminescence is improved. Therefore, when used as an organic phosphorescent light emitting device material, high emission luminance This is also advantageous when light is emitted for a long time.

  In addition, since an electron withdrawing group having a double bond such as a carbonyl group can be expected to stabilize the triplet excited state, it is more than a conventional fluorescent organic EL element that uses only a singlet excited state. In the organic phosphorescent light emitting device, when used simultaneously with the phosphorescent light emitting material (B), an effect of enhancing the light emission can be expected, so that it can be suitably used for a light emitting layer, a hole blocking layer, and the like.

  An organic phosphorescent light-emitting device is a device in which a single-layer or multilayer organic thin film is formed between an anode and a cathode. The basic configuration is the same as that of a conventional organic EL element, but is characterized in that material selection and layer configuration are devised so that triplet excited state energy can be used for light emission. In the present invention, the “phosphorescent light-emitting element” means not only a case where a light-emitting material or a doping material directly emits light from a triplet state, but also a triplet generated by recombination of charges injected from both electrodes. It includes all elements having a structure designed to have a mechanism and a process that can be effectively used for light emission in the element without turning the excited state into energy emission other than light. In this sense, the metal complex compound (A) of the present invention is suitable as a material constituting each layer because it easily generates and maintains a triplet excited state structurally and physically. In particular, when it is used as a component of a light emitting layer in which the triplet excited state is most present during device driving, the maximum effect is exhibited.

  When the organic EL element or the organic phosphorescent light emitting element is a single layer type, a light emitting layer is provided between the anode and the cathode. The light emitting layer contains a light emitting material, and may further contain a hole injecting material or an electron injecting material in order to transport holes injected from the anode or electrons injected from the cathode to the light emitting material. The electron injection material is a material having the ability to inject electrons from the cathode, and the electron transport material is a material having the ability to transport the injected electrons to the light emitting layer. The hole injection material is a material having the ability to inject holes from the anode, and the hole transport material is a material having the ability to transport the injected holes to the light emitting layer. The multilayer type includes (anode / hole injection layer / light emitting layer / cathode), (anode / hole injection layer / hole transport layer / light emitting layer / cathode), (anode / light emitting layer / electron injection layer / cathode), (Anode / light emitting layer / electron transport layer / electron injection layer / cathode), (anode / hole injection layer / light emitting layer / electron injection layer / cathode), (anode / hole injection layer / hole transport layer / light emitting layer) There is an organic phosphorescent light emitting device laminated in a multilayer structure of / electron transport layer / electron injection layer / cathode). The multilayer hole transport layer and electron transport layer may be composed of a plurality of layers. Here, a hole injection layer and a hole transport layer, in some cases up to a light emitting layer having a strong hole transport property, up to a hole injection band, an electron injection layer and an electron transport layer, and in some cases to a light emitting layer having a strong electron transport property May be referred to as an electron injection band, and materials used in each band may be collectively referred to as a hole injection material (or hole transport material) or an electron injection material (or electron transport material). In the case of an organic phosphorescent light emitting device, the electron transporting layer is required to prevent holes from escaping from the light emitting layer to the cathode side due to the electron transportability in terms of device characteristics and materials used. In order to give more importance to the blocking property, it is often called a hole blocking layer or a hole blocking layer, and the material used for this layer is sometimes called a hole blocking material. Since these designations are given to emphasize one aspect of the necessary characteristics of the material for the target element, the essence of the material does not differ depending on the designation. The material of each of these layers and the structure thereof are selected and determined according to various factors such as the energy level of the material, heat resistance, and adhesion to the organic layer or metal electrode.

  If necessary, in addition to the material of the present invention, a known light emitting material, doping material, hole injecting material, and electron injecting material containing a further existing organic fluorescent dye can be used for the light emitting layer. The organic phosphorescent light emitting element can prevent a decrease in luminance and lifetime due to quenching by adopting a multilayer structure. If necessary, a light emitting material, a doping material, a hole injection material, and an electron injection material can be used in combination. Further, by using a doping material, emission luminance and luminous efficiency can be improved, and light emission ranging from blue to red can be obtained.

  Examples of the phosphorescent material (B) or doping material that can be used in the light emitting layer together with the metal complex compound (A) of the present invention include a metal complex composed of an organic compound or a ligand of an organic residue. The metal atom is usually a transition metal, and is preferably an element of the 5th or 6th period in the period, and from the 6th group to the 11th group in the group, and more preferably in the 8th to 10th group. Specific examples include iridium and platinum. Examples of the ligand include 2-phenylpyridine and 2- (2'-benzothienyl) pyridine, and the carbon atom on these ligands is directly bonded to the metal. Another example is a porphyrin or tetraazaporphyrin ring complex. Examples of the central metal include platinum. Although the typical example of a phosphorescent luminescent material is specifically illustrated below, this invention is not limited to this representative example. Note that this example is an example of a material for which it is known that light is emitted directly from a triplet excited state, and there is another mechanism that can be used for light emission effectively without losing triplet excitation energy in the device. In addition, more materials can be used as the light emitting material or the doping material, and the possibility that the existing organic fluorescent dye, the organic EL light emitting material, and the doping material can be used for the organic phosphorescent light emitting element is not denied.

 Any of the above-mentioned materials that can be used in the light-emitting layer and the abundance ratio of the compound of the present invention in the light-emitting layer may be the main component, but preferably the above-mentioned phosphorescent light-emitting material (B) or doping material In other words, the metal compound (A) of the present invention is used as a host material having an abundance ratio of 50% by weight or more.

The metal complex compound (A) of the present invention can be used as a doping material in addition to being used as a host material in the light emitting layer. In that case, any compound can be used as long as the compound itself has strong light emission, but in the present invention, it is preferable that light is emitted through an excited state other than a singlet such as a triplet excited state. Specifically, the metal atom M is a rare earth or a metal selected from any of Groups 6 to 11 of the periodic table, more preferably a Group 8 or 10 of the periodic table, and a platinum group of the 5th or 6th period. It is a metal selected from elements. More specifically, iridium or platinum can be mentioned . Further, the ratio in the light emitting layer as a doping material is preferably 50% by weight or less.

  Host materials that can be used in combination with the metal complex compound (A) include quinoline metal complexes, oxadiazoles, benzothiazole metal complexes, benzoxazole metal complexes, benzimidazole metal complexes, triazoles, imidazoles, oxazoles, oxadiazoles, and stilbenes. , Butadiene, benzidine type triphenylamine, styrylamine type triphenylamine, diamine type triphenylamine fluorenone, diaminoanthracene type triphenylamine, diaminophenanthrene type triphenylamine, anthraquinodimethane, diphenoquinone, thiadiazole, tetrazole, perylenetetra Carboxylic acid, fluorenylidenemethane, anthraquinodimethane, triphenylene, anthrone and their derivatives, polyvinylcarbazole, There are polymeric materials such as a conductive polymer such as Rishiran.

  However, in the present invention, when the metal complex compound (A) emits phosphorescence, the host material is preferably a material that stabilizes the triplet excited state and can effectively transfer energy to the doping material. Examples of such materials include compounds having a heterocyclic ring, particularly a nitrogen-containing ring. Specifically, there are monocyclic rings such as pyrrole, oxazole, thiazole, imidazole, pyridine, pyrimidine, pyrazine, and other rings. Examples thereof include compounds having condensed indole, carbazole, benzoxazole, benzimidazole, quinoxaline and the like in the structure, and metal complexes having these structures as ligands. Among these, a compound having a carbazole ring can be particularly preferably used. In addition, a carbonyl group or a compound having an electron withdrawing double bond derived from a carbonyl group can be preferably used because it has an effect of stabilizing the triplet excited state. Further, compounds having two or more different types of heterocycles in the structure, and compounds having both an electron withdrawing double bond such as a carbonyl group and a heterocycle can also be suitably used. Also, two or more of the metal complex compounds (A) of the present invention can be used for the host material and the doping material, respectively.

  As a hole injection material, it has the ability to transport holes, has a hole injection effect from the anode, an excellent hole injection effect for the light emitting layer or the light emitting material, and excitons generated in the light emitting layer. Examples thereof include compounds that prevent movement to an electron injection zone or an electron injection material and have an excellent thin film forming ability. Specifically, phthalocyanine derivatives, naphthalocyanine derivatives, porphyrin derivatives, oxazole, oxadiazole, triazole, imidazole, imidazolone, imidazolethione, pyrazoline, pyrazolone, tetrahydroimidazole, oxazole, oxadiazole, hydrazone, acyl hydrazone, polyaryl Alkane, stilbene, butadiene, benzidine type triphenylamine, styrylamine type triphenylamine, diamine type triphenylamine, etc., and their derivatives, and polymer materials such as polyvinyl carbazole, polysilane, conductive polymer, etc. However, it is not limited to these.

  Among the hole injection materials that can be used in the organic phosphorescent light emitting device of the present invention, more effective hole injection materials are arylamine derivatives, phthalocyanine compounds, or triphenylene derivatives. Specific examples of the arylamine derivative include triphenylamine, tolylamine, tolyldiphenylamine, N, N′-diphenyl-N, N′-di-m-tolyl-4,4′-biphenyldiamine, N, N, N ', N'-tetra (p-tolyl) -p-phenylenediamine, N, N, N', N'-tetra-p-tolyl-4,4'-biphenyldiamine, N, N'-diphenyl-N, N′-di (1-naphthyl) -4,4′-biphenyldiamine, N, N′-di (4-n-butylphenyl) -N, N′-di-p-tolyl-9,10-phenanthrenediamine 4,4 ′, 4 ″ -tris (N-phenyl-Nm-tolylamino) triphenylamine, 1,1-bis [4- (di-p-tolylamino) phenyl] cyclohexane, or the like There are oligomers or polymers having tertiary amine skeletons, though not particularly limited thereto.

Specific examples of the phthalocyanine (Pc) compound include H ₂ Pc, CuPc, CoPc, NiPc, ZnPc, PdPc, FePc, MnPc, ClAlPc, ClGaPc, ClInPc, ClSnPc, Cl ₂ SiPc, (HO) AlPc, (HO) ) There are, but are not limited to, phthalocyanine derivatives and naphthalocyanine derivatives such as GaPc, VOPc, TiOPc, MoOPc, and GaPc-O-GaPc.

  Specific examples of triphenylene derivatives include hexaalkoxytriphenylenes such as hexamethoxytriphenylene, hexaethoxytriphenylene, hexahexyloxytriphenylene, hexabenzyloxytriphenylene, trimethylenedioxytriphenylene, triethylenedioxytriphenylene, hexaphenoxytriphenylene, hexanaphthyl. Examples include, but are not limited to, hexaaryloxytriphenylenes such as oxytriphenylene, hexabiphenylyloxytriphenylene, and triphenylenedioxytriphenylene, and hexaacyloxytriphenylenes such as hexaacetoxytriphenylene and hexabenzoyloxytriphenylene.

  As an electron injection material, it has the ability to transport electrons, has a hole injection effect from the cathode, and an excellent electron injection effect for the light-emitting layer or light-emitting material, and hole injection of excitons generated in the light-emitting layer Examples thereof include compounds that prevent migration to the zone and have an excellent thin film forming ability. For example, there are fluorenone, anthraquinodimethane, diphenoquinone, thiopyran dioxide, oxazole, oxadiazole, triazole, imidazole, perylenetetracarboxylic acid, fluorenylidenemethane, anthraquinodimethane, anthrone, and their derivatives. However, it is not limited to these. Further, it can be sensitized by adding an electron accepting substance to the hole injecting material and an electron donating substance to the electron injecting material.

  In the organic phosphorescent light emitting device of the present invention, a more effective electron injection material is a metal complex compound or a nitrogen-containing five-membered ring derivative. Specifically, as the metal complex compound, 8-hydroxyquinolinate lithium, bis (8-hydroxyquinolinate) zinc, bis (8-hydroxyquinolinato) copper, bis (8-hydroxyquinolinato) manganese , Tris (8-hydroxyquinolinato) aluminum, tris (2-methyl-8-hydroxyquinolinato) aluminum, tris (8-hydroxyquinolinato) gallium, bis (10-hydroxybenzo [h] quinolinato) beryllium Bis (10-hydroxybenzo [h] quinolinato) zinc, bis (2-methyl-8-hydroxyquinolinato) chlorogallium, bis (2-methyl-8-hydroxyquinolinato) (o-cresolate) gallium, Bis (2-methyl-8-hydroxyquinolinate) (1-naphthlar ) Aluminum, bis (2-methyl-8-hydroxyquinolinato) (2-naphtholato) gallium, bis (2-methyl-8-hydroxyquinolinato) phenolate gallium, bis (o- (2-benzoxazolyl) (L) phenolate) zinc, bis (o- (2-benzothiazolyl) phenolate) zinc, bis (o- (2-benzotriazolyl) phenolate) zinc, and the like, but are not limited thereto.

  Further, as the nitrogen-containing five-membered ring derivative, an oxazole, thiazole, oxadiazole, thiadiazole or triazole derivative is preferable. Specifically, 2,5-bis (1-phenyl) -1,3,4-oxazole, dimethyl POPOP, 2,5-bis (1-phenyl) -1,3,4-thiazole, 2,5- Bis (1-phenyl) -1,3,4-oxadiazole, 2- (4′-tert-butylphenyl) -5- (4 ″ -biphenyl) -1,3,4-oxadiazole, 2, 5-bis (1-naphthyl) -1,3,4-oxadiazole, 1,4-bis [2- (5-phenyloxadiazolyl)] benzene, 1,4-bis [2- (5-phenyl) Oxadiazolyl) -4-tert-butylbenzene], 2- (4′-tert-butylphenyl) -5- (4 ″ -biphenyl) -1,3,4-thiadiazole, 2,5-bis (1- Naphthyl) -1,3,4-thiadiazole, 1,4-bis [2- (5 Phenylthiadiazolyl)] benzene, 2- (4′-tert-butylphenyl) -5- (4 ″ -biphenyl) -1,3,4-triazole, 2,5-bis (1-naphthyl) -1, Examples include, but are not limited to, 3,4-triazole and 1,4-bis [2- (5-phenyltriazolyl)] benzene.

  As a hole blocking material, it has the ability to prevent holes from being transported to the cathode, has the effect of preventing the exciton generated in the light emitting layer from moving to the electron injection zone, and has excellent thin film forming ability Compounds. Many of the electron injection materials can be used as hole blocking materials. For example, 2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3,4-triazole and 2,5- Azoles (nitrogen-containing five-membered rings) represented by bis (1-phenyl) -1,3,4-oxadiazole, phenanthroline derivatives represented by bathocuproine, bis (2-methyl-8-hydroxyquinolinate) ) (4-biphenyloxolate) aluminum (III), nitrogen-containing six-membered rings such as metal complexes represented by bis (2-methyl-8-hydroxyquinolinato) phenolate gallium and the ligands Metal complexes, silacyclobutene (silole) derivatives, and the like, but are not limited thereto.

  In addition, since the metal complex compound (A) of the present invention has an electron withdrawing group, the electron transporting property is higher than the hole transporting property, and is suitable as a kind of the above-described hole blocking material or electron injecting material. It is possible to use.

  In order to improve the stability of the organic phosphorescent light-emitting device obtained by the present invention with respect to temperature, humidity, atmosphere, etc., a protective layer may be provided on the surface of the device, or the entire device may be protected with silicon oil, resin, etc. Is possible.

  As the conductive material used for the anode of the organic phosphorescent light emitting device, a material having a work function larger than 4 eV is suitable, and carbon, aluminum, vanadium, iron, cobalt, nickel, tungsten, silver, gold, platinum, palladium And their alloys, metal oxides such as tin oxide and indium oxide used for ITO substrates and NESA substrates, and organic conductive resins such as polythiophene and polypyrrole.

  As the conductive material used for the cathode, those having a work function smaller than 4 eV are suitable, and magnesium, calcium, tin, lead, titanium, yttrium, lithium, ruthenium, manganese, aluminum, and alloys thereof are used. However, it is not limited to these. Examples of alloys include magnesium / silver, magnesium / indium, lithium / aluminum, and the like, but are not limited thereto. The ratio of the alloy is controlled by the temperature of the vapor deposition source, the atmosphere, the degree of vacuum, etc., and is selected to an appropriate ratio. Further, as a cathode, an alkali metal such as lithium fluoride, magnesium fluoride, or lithium oxide, a fluoride of an alkaline earth metal, or an oxide is formed on the organic layer with a film thickness of 1 nm or less, and aluminum or silver is formed thereon. A metal having a relatively high conductivity such as, for example, may be formed. Moreover, the anode and the cathode may be formed with a layer structure of two or more layers if necessary.

  In the organic phosphorescent light emitting device, in order to emit light efficiently, it is desirable that at least one of them is sufficiently transparent in the light emitting wavelength region of the device. The substrate is also preferably transparent. The transparent electrode is set using the above-described conductive material so as to ensure a predetermined translucency by a method such as vapor deposition or sputtering. The electrode on the light emitting surface preferably has a light transmittance of 10% or more. The substrate is not limited as long as it has mechanical and thermal strength and has transparency. For example, a glass substrate, a polyethylene plate, a polyethylene terephthalate plate, a polyethersulfone plate, Examples thereof include a transparent resin such as a polypropylene plate.

  The formation of each layer of the organic phosphorescent light emitting device according to the present invention applies any of dry deposition methods such as vacuum deposition, sputtering, plasma, and ion plating, and wet deposition methods such as spin coating, dipping, and flow coating. can do. The film thickness is not particularly limited, but must be set to an appropriate film thickness. If the film thickness is too thick, a large applied voltage is required to obtain a constant light output, resulting in poor efficiency. If the film thickness is too thin, pinholes and the like are generated, and sufficient light emission luminance cannot be obtained even when an electric field is applied. The normal film thickness is suitably in the range of 5 nm to 10 μm, but more preferably in the range of 10 nm to 0.2 μm.

  In the case of the wet film-forming method, the material for forming each layer is dissolved or dispersed in an appropriate solvent such as ethanol, chloroform, tetrahydrofuran, dioxane or the like to form a thin film, and any solvent may be used. In any organic thin film layer, an appropriate resin or additive may be used for improving film formability and preventing pinholes in the film. Usable resins include insulating resins such as polystyrene, polycarbonate, polyarylate, polyester, polyamide, polyurethane, polysulfone, polymethyl methacrylate, polymethyl acrylate, and cellulose, and copolymers thereof, poly-N-vinyl. Examples thereof include photoconductive resins such as carbazole and polysilane, and conductive resins such as polythiophene and polypyrrole. Examples of the additive include an antioxidant, an ultraviolet absorber, and a plasticizer.

  As described above, by using the compound of the present invention in the light emitting layer of the organic phosphorescent light emitting device, the characteristics of the organic phosphorescent light emitting device such as the light emission efficiency and the maximum light emission luminance can be improved. In addition, this element is extremely stable against heat and current, and can be used for light emission brightness that can be used practically at a low driving voltage, so that deterioration that has been a major problem until now can be greatly reduced. I was able to.

  Hereinafter, the present invention will be described in more detail based on examples.

Synthesis Method of Compound (1) A sodium hydroxide aqueous solution was prepared by dissolving 0.27 g of 96% sodium hydroxide in 20 g of water. To this aqueous solution, 1.2 g of tropolone was added and dissolved by stirring at 50 ° C. for 10 minutes to obtain an aqueous solution of tropolone Na complex. An aluminum chloride aqueous solution prepared by dissolving 0.8 g of aluminum chloride in 10 g of water was added dropwise to the aqueous solution to precipitate a solid. The precipitate was filtered and dried to obtain 3.3 g (yield 85%) of the target compound (1). Further sublimation purification was performed.

Method of synthesizing compound (2) 5.0 g (0.03 mol) of 4-isopropyltropolone (also known as hinokitiol) was dissolved in 50 ml of methanol, and 3.4 g (0.015 mol) of Zn (CH ₃ COO) was dissolved. ) When an aqueous solution in which ₂ · 2H ₂ O was dissolved in 150 ml of water was mixed, a pale yellow precipitate was formed. Extraction was performed 3 times with 50 ml of methylene chloride, and the solvent and acetic acid were distilled off under reduced pressure to leave a pale yellow solid. This solid was recrystallized from ethanol, filtered, and dried under reduced pressure at 100 ° C. to obtain 4.8 g of a pale yellow solid of the target compound (2) (yield 80%). Further sublimation purification was performed.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to the following Example. In the examples, all mixing ratios are weight ratios unless otherwise specified. Vapor deposition (vacuum deposition) was performed in a vacuum of 10 ⁻⁶ Torr and under conditions without temperature control such as substrate heating and cooling. In the evaluation of the light emission characteristics of the element, the characteristics of an organic EL element having an electrode area of 2 mm × 2 mm were measured. The measurement recorded current, luminance, and chromaticity at each voltage while increasing by 1V. The maximum light emission luminance and efficiency are the maximum values measured for each voltage, and the voltage at that time varies depending on the element.

Example 1
Compound (2), compound (D2), N, N ′-(3-methylphenyl) -N, N′-diphenyl-1,1′-biphenyl-4,4 ′ is placed on the cleaned glass plate with ITO electrode. -Diamine (TPD), 2,5-bis (1-naphthyl) -1,3,4-oxadiazole, polycarbonate resin (Teijin Chemicals: Panlite K-1300) at 20: 5: 15: 10: 50 A light emitting layer having a thickness of 100 nm was obtained by dissolving in tetrahydrofuran by weight and spin coating. The film obtained at this time was very stable, and the phenomenon of aggregation and crystallization was not observed. On top of this, an electrode having a thickness of 150 nm was formed from an alloy in which magnesium and silver were mixed at a ratio of 10: 1 to obtain an organic phosphorescent light emitting device. The light emission characteristics of this device were green light emission with a light emission luminance of 170 (cd / m ² ) at a DC voltage of 10 V, a maximum light emission luminance of 8800 (cd / m ² ), and a light emission efficiency of 4.3 (cd / A). .

Example 2
N, N '-(1-naphthyl) -N, N'-diphenyl-1,1'-biphenyl-4,4'-diamine (NPD) is vacuum-deposited on a cleaned glass plate with an ITO electrode. A hole injection layer having a thickness of 20 nm was obtained. Next, the compound (1) and the compound (D1) were co-evaporated at a ratio of 93: 7 to prepare a light-emitting layer having a thickness of 40 nm, and then bis (2-methyl-5-phenyl-8-hydroxyquinolinato) pheno An electron injection layer having a thickness of 30 nm was obtained by depositing a gallium complex. On top of this, an electrode having a thickness of 100 nm was formed from an alloy in which magnesium and silver were mixed at a ratio of 10: 1 to obtain an organic phosphorescent light emitting device. This device emitted green light with a light emission luminance of 2700 (cd / m ² ), a maximum light emission luminance of 76500 (cd / m ² ), and a light emission efficiency of 37 (cd / A) at a DC voltage of 10V.

Example 3
A device was fabricated in the same manner as in Example 2 except that the compound (44) was used instead of the compound (1). This device emitted green light with a luminance of 5200 (cd / m ² ), a maximum luminance of 56200 (cd / m ² ), and a luminous efficiency of 32 (cd / A) at a DC voltage of 10V.

Example 4
NPD was vacuum-deposited on the cleaned glass plate with an ITO electrode to obtain a hole injection layer having a thickness of 30 nm. Next, the compound (10) and the compound (D5) were co-evaporated at a ratio of 95: 5 to prepare a light-emitting layer having a thickness of 40 nm, and then bis (2-methyl-8-hydroxyquinolinate) (p-phenylphenol) Lat) An aluminum complex was vapor-deposited to form a hole blocking layer having a thickness of 10 nm, and further tris (8-hydroxyquinolinato) aluminum complex (Alq3) was vapor-deposited to obtain an electron injection layer having a thickness of 30 nm. On top of this, first, 1 nm of lithium fluoride and then 200 nm of aluminum were vapor-deposited to form an electrode to obtain an organic phosphorescent light emitting device. This device emitted red light with a luminance of 810 (cd / m ² ) at a DC voltage of 10 V, a maximum luminance of 31400 (cd / m ² ), and a luminous efficiency of 8.7 (cd / A).

Example 5
On the washed glass plate with an ITO electrode, the compound (56) and the compound (D6) were dissolved in methylene chloride at a ratio of 98: 2, and a hole injection type light emitting layer having a thickness of 50 nm was obtained by a spin coating method. Next, bathocuproine was evaporated to form a hole blocking layer having a thickness of 5 nm, and further Alq3 was evaporated to obtain an electron injection layer having a thickness of 30 nm. On top of that, first, 0.5 nm of lithium fluoride and then 200 nm of aluminum were vapor-deposited to form an electrode to obtain an organic phosphorescent device. This device obtained red light emission with a light emission luminance of 290 (cd / m ² ) at a DC voltage of 10 V, a maximum light emission luminance of 9800 (cd / m ² ), and a light emission efficiency of 5.2 (cd / A).

Example 6
NPD was vacuum-deposited on the cleaned glass plate with an ITO electrode to obtain a hole injection layer having a thickness of 30 nm. Next, the compound (4) and the compound (D3) were co-evaporated at a ratio of 94: 6 to obtain a light emitting layer having a thickness of 50 nm. Next, a bis (2-methyl-8-hydroxyquinolinate) (p-cyanophenolate) gallium complex is vacuum-deposited to form a 20-nm-thick hole blocking layer, and Alq3 is further deposited to deposit 20-nm-thick electrons. A layer was obtained. On top of this, an electrode having a thickness of 250 nm was formed from an alloy in which magnesium and silver were mixed at a ratio of 10: 1 (weight ratio) to obtain an organic phosphorescent device. This device obtained blue light emission with a light emission luminance of 5900 (cd / m ² ), a maximum light emission luminance of 26700 (cd / m ² ), and a light emission efficiency of 8.2 (cd / A) at a DC voltage of 10V.

Example 7
Copper phthalocyanine was vacuum-deposited on the washed glass plate with an ITO electrode to obtain a hole injection layer having a thickness of 20 nm. Subsequently, the compound (16) was vacuum-deposited to obtain a 30 nm-thick hole transport layer. Further, the compound (22) and the compound (D1) were co-evaporated at a ratio of 93: 7 to prepare a light emitting layer with a thickness of 40 nm, and then bathocuproine was evaporated to form a hole blocking layer with a thickness of 10 nm. Was vacuum-deposited to prepare an electron injection layer having a thickness of 30 nm. An electrode was formed thereon by vacuum deposition of 0.7 nm of lithium fluoride (LiF) and then 150 nm of aluminum (Al) to obtain an organic phosphorescent device. This device obtained green light emission with a light emission luminance of 2200 (cd / m ² ) at a DC voltage of 10 V, a maximum light emission luminance of 82500 (cd / m ² ), and a light emission efficiency of 48 (cd / A). Further, the half-life when driven at a constant current at an emission luminance of 500 (cd / m ² ) was 5200 hours.

Example 8
Copper phthalocyanine was vacuum-deposited on the washed glass plate with the ITO electrode to obtain a 10 nm-thick hole injection layer. Subsequently, 4,4′-bis [N- (9-phenanthryl) -N-phenylamino] biphenyl was vacuum-deposited to obtain a 40 nm-thick hole transport layer. Next, the compound (60) and the compound (D4) were co-evaporated at a ratio of 92: 8 to prepare a light-emitting layer having a thickness of 50 nm, and 3- (4-biphenylyl) -4-phenyl-5- (4- tert-Butylphenyl) -1,2,4-triazole was deposited to form a 5 nm thick hole blocking layer, and then bis (2-methyl-8-hydroxyquinolinate) (p-cyanopheno) Lat) gallium complex was deposited to obtain an electron injection layer having a thickness of 30 nm. Further, an electrode having a thickness of 250 nm was formed from an alloy in which magnesium and silver were mixed at a weight ratio of 10: 1 to obtain an organic phosphorescent device. This device emitted light with a direct current voltage of 10 V and a light emission luminance of 2410 (cd / m ² ), a maximum light emission luminance of 32100 (cd / m ² ), and a light emission efficiency of 11 (cd / A). Further, the half-life when driven at a constant current at an emission luminance of 500 (cd / m ² ) was 4200 hours.

Example 9
NPD was vacuum-deposited on the cleaned glass plate with an ITO electrode to obtain a hole injection layer having a thickness of 30 nm. Next, the compound (11) and the compound (D7) were co-evaporated at a ratio of 97: 3 to form a light emitting layer having a thickness of 40 nm, and then only the compound (11) was evaporated alone to form a positive film having a thickness of 30 nm. A hole blocking layer and further Alq3 were vacuum deposited to form an electron injection layer having a thickness of 20 nm. First, an electrode was formed by vacuum deposition of lithium fluoride at 0.5 nm and aluminum at 200 nm to obtain an organic phosphorescent device. This device produced red light emission with a light emission luminance of 1240 (cd / m ² ) at a DC voltage of 10 V, a maximum light emission luminance of 18300 (cd / m ² ), and a light emission efficiency of 9.4 (cd / A). Further, the half-life when driven at a constant current at an emission luminance of 500 (cd / m ² ) was 4700 hours.

Example 10
NPD was vacuum-deposited on the cleaned glass plate with an ITO electrode to obtain a hole injection layer having a thickness of 50 nm. Next, the compound (52) and the compound (D3) were co-evaporated at a weight ratio of 85:15 to form a light-emitting layer having a thickness of 40 nm, and then bis (2-methyl-8-hydroxyquinolinate) (p -Phenylphenolate) An aluminum complex was vapor-deposited to form a hole blocking layer having a thickness of 10 nm, and further Alq3 was vapor-deposited to obtain an electron injection layer having a thickness of 30 nm. Furthermore, an electrode was first formed thereon by vacuum deposition of 0.5 nm of magnesium fluoride and 200 nm of aluminum, to obtain an organic phosphorescent light emitting device. This device emitted light with a luminance of 1860 (cd / m ² ), a maximum luminance of 64800 (cd / m ² ), and a luminous efficiency of 5.7 (cd / A) at a DC voltage of 10 V. Further, the half-life when driven at a constant current at an emission luminance of 500 (cd / m ² ) was 2400 hours.

Comparative Example 1
A device was prepared in the same manner as in Example 1 except that the following compound (C1) was used instead of the compound (2). The spin coat film has the disadvantage that it easily aggregates and crystallizes. The light emission characteristics of this element were that light emission with a direct current voltage of 10 V was 50 (cd / m ² ), the maximum light emission brightness was 2300 (cd / m ² ), and the light emission efficiency was 1.8 (cd / A). The light and dark areas were mixed, not uniform light emission. Further, when the device was driven at a constant current with an emission luminance of 500 (cd / m ² ), it was short-circuited in about 1 hour.
Compound (C1)

Comparative Example 2
A device was prepared in the same manner as in Example 2 except that CBP was used instead of the compound (1). With respect to the light emission characteristics of this device, light emission with a direct current voltage of 10 V of light emission luminance of 1700 (cd / m ² ), maximum light emission luminance of 48000 (cd / m ² ), and light emission efficiency of 25 (cd / A) was obtained. However, the half-life when driven at a constant current with an emission luminance of 500 (cd / m ² ) was 820 hours.

Comparative Example 3
A device was prepared in the same manner as in Example 10 except that the following compound (C2) was used instead of the compound (52). With respect to the light emission characteristics of the device, light emission with a direct current voltage of 10 V of light emission luminance of 2560 (cd / m ² ), maximum light emission luminance of 30100 (cd / m ² ), and light emission efficiency of 4.5 (cd / A) was obtained. However, the half life when driven at a constant current at an emission luminance of 500 (cd / m ² ) was 180 hours.
Compound (C2)

Example 11
A device was prepared in the same manner as in Example 4 except that the compound (31) was used instead of the compound (10). This device obtained red light emission with a light emission luminance of 540 (cd / m ² ) at a DC voltage of 10 V, a maximum light emission luminance of 14100 (cd / m ² ), and a light emission efficiency of 11.2 (cd / A). The half life when driven at a constant current at an emission luminance of 500 (cd / m ² ) was 8700 hours.

Example 12
Copper phthalocyanine was vacuum-deposited on the washed glass plate with an ITO electrode to obtain a hole injection layer having a thickness of 20 nm. Subsequently, NPD was vacuum-deposited to obtain a hole transport layer having a thickness of 30 nm. Further, the compound (51) and the compound (D2) were co-evaporated at a ratio of 90:10 to prepare a light emitting layer having a thickness of 40 nm, and then bis (2-methyl-8-hydroxyquinolinate) (p- A 10-nm-thick hole blocking layer was formed by vapor-depositing a cyanophenolate) aluminum complex, and Alq3 was further vacuum-deposited to form an electron-injecting layer having a thickness of 30 nm. An electrode was formed thereon by vacuum-depositing lithium fluoride at 0.7 nm and then aluminum at 200 nm to obtain an organic phosphorescent device. This device emitted light with a luminance of 7810 (cd / m ² ), a maximum luminance of 87200 (cd / m ² ), and a luminous efficiency of 44 (cd / A) at a DC voltage of 10V. Further, the half-life when driven at a constant current at an emission luminance of 500 (cd / m ² ) was 4700 hours.

Example 13
On the washed glass plate with an ITO electrode, 4,4′-bis [N- (9-phenanthryl) -N-phenylamino] biphenyl was vacuum-deposited to obtain a hole injection layer having a thickness of 30 nm. Next, the compound (30) and the compound (D3) were co-evaporated at a ratio of 95: 5 to obtain a light-emitting layer having a thickness of 50 nm. Next, a bis (2-methyl-8-hydroxyquinolinate) (p-phenylphenolate) aluminum complex was vacuum-deposited to form a 10 nm-thick hole blocking layer, and bis (2-methyl-5-phenyl-8). -Hydroxyquinolinato) phenolate gallium complex was evaporated to obtain an electron injection layer having a thickness of 30 nm. On top of this, an electrode having a thickness of 250 nm was formed from an alloy in which magnesium and silver were mixed at a ratio of 10: 1 (weight ratio) to obtain an organic phosphorescent device. This device obtained blue light emission with a light emission luminance of 7100 (cd / m ² ), a maximum light emission luminance of 69100 (cd / m ² ), and a light emission efficiency of 8.2 (cd / A) at a DC voltage of 10V.

Example 14
A device was prepared in the same manner as in Example 7 except that the compound (42) was used instead of the compound (22) in the light emitting layer. This device emitted green light with a luminance of 6120 (cd / m ² ) at a DC voltage of 10 V, a maximum luminance of 56700 (cd / m ² ), and a luminous efficiency of 45 (cd / A). Further, the half-life when driven at a constant current at an emission luminance of 500 (cd / m ² ) was 7900 hours.

Example 15
4,4 ′, 4 ″ -tris [N- (1-naphthyl) -N-phenylamino] triphenylamine is vacuum-deposited on a cleaned glass plate with an ITO electrode to form a 20 nm-thick hole injection layer. Next, NPD was vacuum-deposited to obtain a 30 nm-thick hole transport layer, and compound (10) and compound (D6) were co-deposited at a ratio of 97: 3 to give a thickness of 40 nm. Then, a 5 nm-thick hole blocking layer was deposited by vapor deposition of bathophenanthroline, and an electron injection layer having a thickness of 30 nm was created by vacuum-depositing Alq3. An electrode was formed by vacuum deposition of 0.7 nm and then 200 nm of aluminum to obtain an organic phosphorescent light emitting device having an emission luminance of 5240 (cd / m ² ) at a DC voltage of 10 V and a maximum emission luminance of 11800. (Cd / m ² ), emission efficiency of 5.2 (cd / A) was obtained, and the half-life when driven at a constant current at an emission luminance of 500 (cd / m ² ) was 8200 hours. .

Example 16
NPD was vacuum-deposited on the cleaned glass plate with an ITO electrode to obtain a hole injection layer having a thickness of 30 nm. Next, the compound (18) and the compound (D5) were co-evaporated at a ratio of 98: 2 to prepare a light emitting layer having a film thickness of 40 nm, and then bis (2-methyl-8-hydroxyquinolinate) (p-phenylphenol) Lat) An aluminum complex was evaporated to form a hole blocking layer having a thickness of 10 nm, and further Alq3 was evaporated to obtain an electron injection layer having a thickness of 30 nm. On top of this, first, 1 nm of lithium fluoride and then 200 nm of aluminum were vapor-deposited to form an electrode to obtain an organic phosphorescent light emitting device. This device obtained red light emission with a light emission luminance of 1550 (cd / m ² ) at a DC voltage of 10 V, a maximum light emission luminance of 19900 (cd / m ² ), and a light emission efficiency of 6.2 (cd / A).

Example 17
NPD was vacuum-deposited on the cleaned glass plate with an ITO electrode to obtain a hole injection layer having a thickness of 30 nm. Next, the compound (25) and the compound (D1) were co-evaporated at a ratio of 95: 5 to prepare a light emitting layer having a thickness of 40 nm, and then a bis (2-methyl-8-hydroxyquinolinato) phenolate aluminum complex was formed. A hole blocking layer having a thickness of 10 nm was deposited, and Alq3 was further deposited to obtain an electron injection layer having a thickness of 30 nm. On top of this, first, 1 nm of lithium fluoride and then 200 nm of aluminum were vapor-deposited to form an electrode to obtain an organic phosphorescent light emitting device. This device emitted green light with a luminance of 3250 (cd / m ² ) at a DC voltage of 10 V, a maximum luminance of 88400 (cd / m ² ), and a luminous efficiency of 46 (cd / A).

Example 18
On the washed glass plate with an ITO electrode, 4,4′-bis [N- (9-phenanthryl) -N-phenylamino] biphenyl was vacuum-deposited to obtain a hole injection layer having a thickness of 30 nm. Next, the compound (40) and the compound (D1) were co-evaporated at a ratio of 93: 7 to prepare a light emitting layer having a thickness of 40 nm, and then bis (2-methyl-5-phenyl-8-hydroxyquinolinato) pheno Lat aluminum complex was evaporated to form a hole blocking layer having a thickness of 10 nm, and Alq3 was further evaporated to obtain an electron injection layer having a thickness of 30 nm. On top of this, first, 1 nm of lithium fluoride and then 200 nm of aluminum were vapor-deposited to form an electrode to obtain an organic phosphorescent light emitting device. This device emitted green light with a luminance of 3250 (cd / m ² ) at a DC voltage of 10 V, a maximum luminance of 98800 (cd / m ² ), and a luminous efficiency of 51 (cd / A). Further, the half-life when driven at a constant current at an emission luminance of 500 (cd / m ² ) was 9500 hours.

Comparative Example 4
A device was prepared in the same manner as in Example 18 except that the following compound (C3) was used instead of the compound (40). This element has a light emission luminance of 940 (cd / m ² ) at a DC voltage of 10 V, a maximum light emission luminance of 9800 (cd / m ² ), a light emission efficiency of 12 (cd / A), and a light emission luminance of 500 (cd / m ^2). ), The half-life when driven at a constant current was 580 hours.
Compound (C3)

In the devices other than the examples in which the half life was specified in this example, when the device was driven at a constant current with a light emission luminance of 500 (cd / m ² ), all of the devices of the examples were reduced from 80% of the initial luminance at 1000 hours. There was nothing I did.

The organic phosphorescent light emitting device of the present invention can be applied to flat panel displays such as wall-mounted televisions, flat light emitters, light sources such as copiers and printers, light sources such as liquid crystal displays and instruments, display boards, and indicator lights. And its industrial value is very large. The material of the present invention can also be used in the fields of conventional organic EL devices, electrophotographic photoreceptors, photoelectric conversion devices, solar cells, image sensors and the like.

Claims (13)

A material for an organic phosphorescent device comprising a metal complex compound (A) represented by the following general formula [1] and a phosphorescent material (B) other than the metal complex compound (A) .
General formula [1]

[Wherein, X ¹ and X ² are each independently any one of O, S and NR;
R and R ^{1 to} R ⁵ are each independently a hydrogen atom, a halogen atom, a cyano group, a nitro group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, A substituted or unsubstituted alkylthio group, a substituted or unsubstituted arylthio group, a substituted or unsubstituted amino group, a substituted or unsubstituted acyl group, a substituted or unsubstituted carbocyclic group, a substituted or unsubstituted heterocyclic group; is there. The adjacent substituents may be integrated to form a ring.
A ligand containing a 7-membered ring having the above structure becomes an anionic ligand, and when a plurality of ligands are coordinated, each may be the same or different.
n is 1 or more and up to the cation valence of M.
M represents a metal selected from Group 1 or Group 14 of the periodic table, X ¹ double-bonded to the 7-membered ring is coordinated to metal atom M, and X ² single-bonded to the 7-membered ring is metal atom M Covalently join.
L is a monodentate or bidentate ligand composed of an organic compound or an organic residue other than the above ligand, or a partial structure bonded to the other metal in the polynuclear complex via an oxygen atom or an organic ligand. To express. L may have two or more of the same or different.
n ′ represents the number of L and may be 0.
The sum of the anion valences of the ligand containing the seven-membered ring and the ligand L matches the cation valence of the metal atom M so as to form an electrically neutral complex as a whole.
The ligand containing 7-membered ring and L may be bonded to each other at a portion other than the metal atom M between the ligands. ] The material for an organic phosphorescent device according to claim 1, wherein n ′ is 0. The material for an organic phosphorescent device according to claim 1 or 2, wherein M is a rare earth or a metal selected from any one of Groups 6 to 11 of the periodic table. 4. The material for an organic phosphorescent light emitting device according to claim 3, wherein M is a metal selected from the group 8 or group 10 of the periodic table and the platinum group element of the fifth period or the sixth period. The material for an organic phosphorescent device according to claim 1 or 2, wherein M is a metal selected from Group 1, Group 2, Group 3, Group 12, or Group 13 of the Periodic Table. The material for organic phosphorescent light emitting device according to claim 5, wherein M is any one of Mg, Ca, Zn, Al, and Ga. The material for an organic phosphorescent device according to any one of claims 1 to 6 , wherein the phosphorescent material (B) comprises an iridium or platinum complex composed of an organic compound or a ligand of an organic residue. An organic phosphorescent light-emitting device formed by forming a light-emitting layer or a plurality of layers of organic compound thin films including a light-emitting layer between a pair of electrodes, wherein the light-emitting layer contains the material for an organic phosphorescent light-emitting device according to any one of claims 1 to 7. Organic phosphorescent light emitting device. In the light emitting layer, the content of the metal complex compound (A) in which M is a metal selected from Group 1, Group 2, Group 12, Group 12 or Group 13 is 50% by weight or more of the entire light emitting layer. The organic phosphorescent light-emitting device according to claim 8 . M is a metal complex compound is a metal selected from any of the rare earth or the periodic table 6 or 11 aromatic content of (A) is, in the light emitting layer, claim occupy less than 50% by weight of the entire light emitting layer 8 or 9. The organic phosphorescent light emitting device according to 9 . Further, cathode and organic phosphorescent device according to any one of claims 8 to 10, characterized in that to form an electron injection layer between the light emitting layer. Et al of the organic phosphorescent device according to claim 8 to 11, wherein one of and forming a hole blocking layer between the electron injection layer and the light emitting layer. Furthermore, anode and an organic phosphorescent device according to any one of claims 8-12, characterized in that to form the hole injection layer between the light emitting layer.