JP2011046851A - Material for organic electroluminescent element coated with low-molecular weight material, ink composition for organic electroluminescent element and organic electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a material for an organic EL element and the organic EL element that has a layer made of a low-molecular weight material formed by a wet deposition method, hardly crystallizes and has excellent characteristics such as high luminous efficiency, low voltage drive, high color purity, long life and high heat resistance, and to provide an ink composition for the organic EL element that ensures high solubility of the low-molecular material suitable for depositing a film composing the organic luminescent material and enables easy formation of a thin film through a wet process. <P>SOLUTION: The ink composition for the organic electroluminescent element comprises a perylene compound (A), a diketopyrrolopyrrole compound (B) and a solvent. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a material used when an organic layer of an organic electroluminescence element (hereinafter abbreviated as an organic EL element) is formed by a wet film forming method such as coating. More specifically, when used in an organic EL device, the material can be formed by a wet film formation method such as a spin coating method, a cast method, or an ink jet method, and has excellent performance (high glass transition temperature, high light emission). Efficient, low voltage drive, high color purity, long life), and particularly relates to an organic EL element material, an organic EL element ink composition, and an organic EL element that can be suitably used for yellow to red light emitting materials. .

In recent years, an electroluminescent element (organic electroluminescent element) using an organic thin film has been developed. Examples of the method for forming the organic thin film include a vacuum deposition method and a wet film formation method. The wet film formation method does not require a vacuum process, and it is easy to increase the area, and there are advantages such as easy mixing of multiple materials with various functions in one layer (coating solution). An organic EL element in which an organic thin film layer is formed by a wet film forming method has been reported (see Patent Document 1).

  In addition, many known light-emitting low-molecular materials are hardly soluble, and the light-emitting layer is usually formed by vacuum deposition. However, the vacuum deposition method has a number of drawbacks such as a complicated process and the need for a large deposition apparatus. The luminescent low molecular weight material has an advantage that it can be purified with high purity by a known technique such as column chromatography as compared with the luminescent high molecular weight material. Therefore, a low-molecular material is less affected by impurities that are mixed therein, and thus may be a light-emitting material having higher light-emitting performance.

  As described above, it is expected that the light emitting layer can be made high quality, and the light emission efficiency of the organic EL element can be improved and the life can be extended. Therefore, it is desired to easily form a low molecular material by wet film formation. Has been.

  Regarding the technique of the ink composition for forming the light emitting layer of the organic EL device, there has already been reported an organic solvent. (See Patent Document 2)

  Moreover, as a low molecular light-emitting ink composition for organic EL elements used for forming a coating film, for example, an anthracene derivative has been reported. (See Patent Documents 3 and 4)

International Publication No. 03/037836 Pamphlet JP 2003-308969 A JP 2004-224766 A International Publication No. 06/070712

  In the organic EL device having a layer made of a low molecular material formed by a wet film formation method, the present invention is difficult to crystallize a layer made of a low molecular material (hereinafter sometimes referred to as a low molecular organic layer). It is an object to provide an organic EL element material and an organic EL element having excellent characteristics such as luminous efficiency, low voltage driving, high color purity, long life, and heat resistance. Another object of the present invention is to provide an ink composition for an organic EL device, which has a high solubility of a low-molecular material suitable for forming a layer constituting an organic light-emitting device and can be easily formed into a thin film by a wet process. Is to provide.

  As a result of intensive studies to solve the above problems, the present inventors have arrived at the present invention.

  That is, this invention relates to the ink composition for organic electroluminescent elements which consists of a compound (A) represented by the following general formula [1], a compound (B) represented by the following general formula [2], and a solvent. .

General formula [1]

[Wherein Ar ¹ represents a substituted or unsubstituted perylenyl group;
R ¹ and R ² are each independently a substituted or unsubstituted monovalent aromatic hydrocarbon group, or a substituted or unsubstituted monovalent aromatic heterocyclic group.
Ar ¹ and R ¹ , Ar ¹ and R ² , R ¹ and R ² may be bonded to each other to form a ring. ]

General formula [2]

[Wherein, R ^{3 to} R ⁸ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group or an aryl group (which may have a hetero atom in the ring).
Ar ² and Ar ³ each independently represent a substituted or unsubstituted aryl group (which may have a hetero atom in the ring).
X ¹ and X ² each independently represent O, S, Se, NE ¹ or CE ² E ³ , E ¹ represents an electron-withdrawing group, and E ² and E ³ represent a hydrogen atom or a substituent. At least one of them represents an electron withdrawing group. ]

  Moreover, this invention relates to the said ink composition for organic electroluminescent elements whose compound (A) is a host and whose compound (B) is a dopant.

  Further, the present invention provides an organic electroluminescent device comprising a plurality of organic layers including a light emitting layer between a pair of electrodes, wherein at least one of the organic layers wets the ink composition for an organic electroluminescent device. The present invention relates to an organic electroluminescence element which is a layer formed by a film forming method.

  Further, the present invention provides an organic electroluminescence device in which a light emitting layer or a plurality of organic layers including a light emitting layer is formed between a pair of electrodes, wherein the light emitting layer wets the ink composition for an organic electroluminescence device. The present invention relates to an organic electroluminescence element which is a layer formed by a film forming method.

  The organic EL element material of the present invention has very high heat resistance and is excellent in solubility in a solvent. By using this organic EL element material, it is possible to form a film that is hardly crystallized, has excellent thermal stability, and has excellent light emission characteristics by a wet film forming method. Moreover, since the organic EL element used as the organic EL element material according to the present invention is driven at a low voltage and has a long life, it can be suitably used as a flat panel display such as a wall-mounted television or a flat light emitter. It can be applied to light sources such as copiers and printers, light sources such as liquid crystal displays and instruments and lighting, display boards, and indicator lights, and has great technical value.

  In the present invention, the wet film forming method is a coating method, an inkjet method, a dip coating method, a die coating method, a spray coating method, a spin coating method, a roll coater method, a dipping coating method, a screen printing method, flexographic printing, The composition is applied to form a film by a screen printing method, an LB method, or the like.

  Embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention does not exceed the gist thereof. It is not specified in the contents.

  Hereinafter, the present invention will be described in detail. The present invention is an ink composition for an organic electroluminescence device comprising a compound (A) represented by the general formula [1], a compound (B) represented by the general formula [2], and a solvent. The compound (A) represented by the general formula [1] will be described.

Ar ¹ in the general formula [1] represents a substituted or unsubstituted perylenyl group, and examples of the unsubstituted perylenyl group include a 1-perylenyl group, a 2-perylenyl group, and a 3-perylenyl group. These perylenyl groups may be further substituted with other substituents.

  Examples of the substituent include a monovalent aliphatic hydrocarbon group, a monovalent aromatic hydrocarbon group, a monovalent aliphatic heterocyclic group, a monovalent aromatic heterocyclic group, a halogen atom, a cyano group, and an alkoxy group. Aryloxy group, alkylthio group, arylthio group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylsulfonyl group, arylsulfonyl group and the like.

  Here, the monovalent aliphatic hydrocarbon group refers to a monovalent aliphatic hydrocarbon group having 1 to 18 carbon atoms, such as an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group. Can be given.

  Therefore, as the alkyl group, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, hexyl group, heptyl group, octyl group, C1-C18 alkyl groups, such as a decyl group, a dodecyl group, a pentadecyl group, and an octadecyl group, are mentioned.

  Examples of the alkenyl group include vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-octenyl group, 1-decenyl group, 1 -An alkenyl group having 2 to 18 carbon atoms such as an octadecenyl group.

  Examples of the alkynyl group include ethynyl group, 1-propynyl group, 2-propynyl group, 1-butynyl group, 2-butynyl group, 3-butynyl group, 1-octynyl group, 1-decynyl group and 1-octadecynyl group. Examples thereof include alkynyl groups having 2 to 18 carbon atoms.

  In addition, the cycloalkyl group has a carbon number such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclooctadecyl group, 2-bornyl group, 2-isobornyl group, 1-adamantyl group. Examples thereof include 3 to 18 cycloalkyl groups.

  Furthermore, examples of the monovalent aromatic hydrocarbon group include monovalent monocyclic, condensed ring, and ring-aggregated aromatic hydrocarbon groups having 6 to 30 carbon atoms. Here, as a monovalent monocyclic aromatic hydrocarbon group having 6 to 30 carbon atoms, phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 2,4-xylyl group, p-cumenyl And monovalent monocyclic aromatic hydrocarbon groups having 6 to 30 carbon atoms such as a group and a mesityl group.

  Examples of the monovalent condensed ring aromatic hydrocarbon group include 1-naphthyl group, 2-naphthyl group, 1-anthryl group, 2-anthryl group, 5-anthryl group, 1-phenanthryl group, 9-phenanthryl group, 1-acenaphthyl group, 2-azurenyl group, 1-pyrenyl group, 2-triphenylyl group, 1-pyrenyl group, 2-pyrenyl group, 1-perylenyl group, 2-perylenyl group, 3-perenylenyl group, 2-trephenylenyl group, Examples thereof include monovalent condensed ring hydrocarbon groups having 10 to 30 carbon atoms such as 2-indenyl group, 1-acenaphthylenyl group, 2-naphthacenyl group, and 2-pentacenyl group.

  The monovalent ring-aggregated aromatic hydrocarbon group has 12 carbon atoms such as o-biphenylyl group, m-biphenylyl group, p-biphenylyl group, terphenylyl group, 7- (2-naphthyl) -2-naphthyl group and the like. To 30 monovalent ring-assembled hydrocarbon groups.

  In addition, as the monovalent aliphatic heterocyclic group, a monovalent fatty acid having 3 to 18 carbon atoms such as a 3-isochromanyl group, a 7-chromanyl group, a 3-coumarinyl group, a piperidino group, a morpholino group, and a 2-morpholino group. Group heterocyclic group.

  Examples of the monovalent aromatic heterocyclic group include 2-furyl group, 3-furyl group, 2-thienyl group, 3-thienyl group, 2-benzofuryl group, 2-benzothienyl group, 2-pyridyl group, 3 Examples thereof include monovalent aromatic heterocyclic groups having 3 to 30 carbon atoms such as -pyridyl group, 4-pyridyl group, 2-quinolyl group, and 5-isoquinolyl group.

  In addition, examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom.

  The alkoxyl group includes a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a tert-butoxy group, an octyloxy group, a tert-octyloxy group, a 2-bornyloxy group, a 2-isobornyloxy group, and a 1-adamantyl group. C1-C18 alkoxyl groups, such as an oxy group, are mention | raise | lifted.

  Examples of the aryloxy group include aryloxy groups having 6 to 30 carbon atoms such as a phenoxy group, a 4-tert-butylphenoxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, and a 9-anthryloxy group. .

  Examples of the alkylthio group include C1-C18 alkylthio groups such as a methylthio group, an ethylthio group, a tert-butylthio group, a hexylthio group, and an octylthio group.

  Examples of the arylthio group include arylthio groups having 6 to 30 carbon atoms such as a phenylthio group, a 2-methylphenylthio group, and a 4-tert-butylphenylthio group.

  Examples of the acyl group include C2-C18 acyl groups such as an acetyl group, a propionyl group, a pivaloyl group, a cyclohexylcarbonyl group, a benzoyl group, a toluoyl group, an anisoyl group, and a cinnamoyl group.

  Moreover, as an alkoxycarbonyl group, C2-C18 alkoxycarbonyl groups, such as a methoxycarbonyl group, an ethoxycarbonyl group, a benzyloxycarbonyl group, are mention | raise | lifted.

  Examples of the aryloxycarbonyl group include aryloxycarbonyl groups having 7 to 30 carbon atoms such as phenoxycarbonyl group and naphthyloxycarbonyl group.

  Moreover, as an alkylsulfonyl group, C1-C18 alkylsulfonyl groups, such as a mesyl group, an ethylsulfonyl group, a propylsulfonyl group, are mention | raise | lifted.

  Examples of the arylsulfonyl group include arylsulfonyl groups having 6 to 30 carbon atoms such as a benzenesulfonyl group and a p-toluenesulfonyl group.

  These substituents may be further substituted with other substituents, and these substituents may be bonded to each other to form a ring.

As Ar ¹ in the general formula [1] described above, a substituted or unsubstituted 3-perylenyl group is preferable, and an unsubstituted 3-perylenyl group is particularly preferable. Among the substituted 3-perylenyl groups, preferred substituents include the aforementioned alkyl groups, monovalent aromatic hydrocarbon groups, and monovalent aromatic heterocyclic groups. Particularly preferred substituents are 1 Valent aromatic hydrocarbon group.

R ¹ and R ² in the general formula [1] are a monovalent organic residue selected from a substituted or unsubstituted monovalent aromatic hydrocarbon group or a substituted or unsubstituted monovalent aromatic heterocyclic group. It is a group.

The substituent here is a monovalent aliphatic hydrocarbon group, a monovalent aromatic hydrocarbon group, a monovalent aliphatic heterocyclic group, a monovalent aromatic heterocyclic group, a halogen atom, a cyano group, Examples thereof include an alkoxy group, aryloxy group, alkylthio group, arylthio group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylsulfonyl group, arylsulfonyl group, amino group and the like. Monovalent aliphatic hydrocarbon group, monovalent aromatic hydrocarbon group, monovalent aliphatic heterocyclic group, monovalent aromatic heterocyclic group, halogen atom, cyano group, alkoxy group, aryloxy group, alkylthio Group, arylthio group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylsulfonyl group, arylsulfonyl group are the monovalent aliphatic hydrocarbon group and monovalent aromatic hydrocarbon group described in the substituent for Ar ¹ Monovalent aliphatic heterocyclic group, monovalent aromatic heterocyclic group, halogen atom, cyano group, alkoxy group, aryloxy group, alkylthio group, arylthio group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, Synonymous with alkylsulfonyl group and arylsulfonyl group.

  As the amino group, N-methylamino group, N-ethylamino group, N, N-diethylamino group, N, N-diisopropylamino group, N, N-dibutylamino group, N-benzylamino group, N, N-dibenzylamino group, N-phenylamino group, N-phenyl-N-methylamino group, N, N-diphenylamino group, N, N-bis (m-tolyl) amino group, N, N-bis ( p-tolyl) amino group, N, N-bis (p-biphenylyl) amino group, bis [4- (4-methyl) biphenylyl] amino group, N-α-naphthyl-N-phenylamino group, N-β- A C2-C26 amino group, such as a naphthyl-N-phenylamino group, is mentioned.

In addition, the unsubstituted monovalent aromatic hydrocarbon group and the unsubstituted monovalent aromatic heterocyclic group in R ¹ and R ² are each a monovalent aromatic hydrocarbon explained with respect to the substituent of Ar ^1. The group is synonymous with an unsubstituted monovalent aromatic heterocyclic group.

  Although the representative example of a compound (A) is shown in Table 1, a compound (A) is not limited to these.

Table 1

  The compound (A) described above can be used alone or in combination of two or more.

  Next, the compound (B) represented by the general formula [2] will be described.

Ar ² and Ar ³ in the general formula [2] are each independently a group selected from a substituted or unsubstituted aryl group, and R ^{3 to} R ⁸ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group. A group selected from a group and a substituted or unsubstituted aryl group. Here, the aryl group may be an aromatic heterocyclic group having a hetero atom in the ring. Examples of the group further substituted with these groups include a monovalent aliphatic hydrocarbon group, a monovalent aromatic hydrocarbon group, a monovalent aliphatic heterocyclic group, a monovalent aromatic heterocyclic group, a halogen atom, Examples include cyano group, alkoxy group, aryloxy group, alkylthio group, arylthio group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylsulfonyl group, arylsulfonyl group, amino group and the like.

Here, a monovalent aliphatic hydrocarbon group, a monovalent aromatic hydrocarbon group, a monovalent aliphatic heterocyclic group, a monovalent aromatic heterocyclic group, a halogen atom, a cyano group, an alkoxy group, an aryloxy A group, an alkylthio group, an arylthio group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group, an arylsulfonyl group, and an amino group are monovalent as described in R ¹ and R ² in the general formula [1]. An aliphatic hydrocarbon group, a monovalent aromatic hydrocarbon group, a monovalent aliphatic heterocyclic group, a monovalent aromatic heterocyclic group, a halogen atom, a cyano group, an alkoxy group, an aryloxy group, an alkylthio group, It is synonymous with an arylthio group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an alkylsulfonyl group, an arylsulfonyl group, and an amino group.

X ¹ and X ² in the general formula [2] represent O, S, Se, NE ¹ , CE ² E ³ . Examples of E ^{1 to} E ³ include the groups described above as substituents for the compound (A). Preferably, E ¹ is necessarily an electron-withdrawing group, and at least one of E ^{2 and} E ³ is at least one of them. It is an electron withdrawing group. Examples of these electron-withdrawing groups include COOR, COR, and CN (R is a substituent such as an alkyl group and an aryl group).

  Although the representative example of a compound (B) is shown in Table 2, a compound (B) is not limited to these.

Table 2

  The compound (B) described above can be used alone or in combination of two or more.

  The present inventors show that the above-mentioned compound (A) and compound (B) are excellent in properties when used alone or in combination with other materials. When combined, the energy from the compound (A) excited by charge recombination is efficiently transferred to the compound (B) to increase the excitation rate of the compound (B), and the compound (B) is further converted into the compound (B). Since it is uniformly dispersed in (A), the excited compound (B) emits light efficiently with little deactivation. Therefore, it is extremely useful as a material for the light emitting layer in terms of high brightness, high efficiency, and long life. It was found that a high effect can be obtained. Depending on the type of material, the compounds (A) and (B) play the opposite role, and in that case as well, a very high effect of high brightness, high efficiency and long life can be obtained. In addition, the combination of these compounds (A) and (B) easily satisfies the conditions as a host and a dopant for emitting yellow to red light, so that when used as a light emitting layer, it has high brightness and high brightness. Efficient yellow to red light emission is exhibited.

  Combining the compounds (A) and (B) is particularly useful for realizing a red light-emitting material having high color purity, high brightness, and high efficiency. Since the compound (A) has a perylene skeleton, it can be expected to emit strong light from the condensed aromatic ring, and has a high glass transition point and high melting point, and has high resistance (heat resistance) to Joule heat generated during light emission. Therefore, by using this compound (A), it is possible to increase the light emission efficiency and the light emission luminance, and to further extend the light emission lifetime, but when this is used alone as a light emitting material, there are many compounds whose emission spectrum is broad. It is difficult to increase color purity, particularly to emit high-purity red light, and improvement is desired. On the other hand, the compound (B) exhibits red light emission with particularly good color purity. However, when this is used alone as a light emitting material, the light emission intensity is weak and improvement in light emission efficiency is desired. Therefore, in order to make up for the disadvantages of each of the above-mentioned materials and take advantage of the advantages, it is very preferable to use the compounds (A) and (B) in combination.

  When used in an organic EL device, a high-purity material is required. As a purification method of the compounds (A) and (B) used in the present invention, a sublimation purification method, a recrystallization method, a reprecipitation method, A zone melting method, a column purification method, an adsorption method, or the like, or a combination of these methods can be used. Of these purification methods, the recrystallization method is preferred. For compounds having sublimation properties, it is preferable to employ a sublimation purification method. In the sublimation purification, it is preferable to employ a method in which the sublimation boat is maintained at a temperature lower than the temperature at which the target compound sublimates, and the sublimation impurities are removed in advance. In addition, it is desirable to apply a temperature gradient to the portion where the sublimate is collected so that the sublimate is dispersed in the impurities and the target product. Sublimation purification as described above is purification that separates impurities, and can be applied to the present invention.

  Next, the ink composition for organic EL elements will be described.

  The ink composition for organic EL elements to which this embodiment is applied contains at least a compound (A), a compound (B), and a solvent.

  Various solvents are applicable as the solvent contained in the ink composition for organic EL elements, and are not particularly limited. For example, aromatic hydrocarbons such as toluene, xylene, methicylene, cyclohexylbenzene and tetralin; halogenated aromatic hydrocarbons such as chlorobenzene, dichlorobenzene and trichlorobenzene; 1,2-dimethoxybenzene, 1,3-dimethoxybenzene and anisole , Phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole and other aromatic ethers; phenyl acetate, phenyl propionate, methyl benzoate, benzoic acid Aromatic esters such as ethyl, propyl benzoate and n-butyl benzoate; ketones having an alicyclic ring such as cyclohexanone and cyclooctanone; aliphatic ketones such as methyl ethyl ketone and dibutyl ketone; methyl ethyl ketone and cyclohexano Alcohol having an alicyclic ring such as ruthenium or cyclooctanol; Aliphatic alcohol such as butanol or hexanol; Aliphatic ether such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether or propylene glycol-1-monomethyl ether acetate (PGMEA); Ethyl acetate And aliphatic esters such as n-butyl acetate, ethyl lactate and n-butyl lactate.

  Of these, aromatic hydrocarbons such as toluene, xylene, methicylene, cyclohexylbenzene, tetralin and the like are preferable in that they have low water solubility and are not easily altered.

  These solvents may be used alone or in combination. In addition, the solvent which can be used is not limited to these.

  Organic EL devices use many materials that deteriorate significantly due to moisture, such as cathodes, so the presence of moisture in the composition can cause moisture to remain in the dried film and reduce device characteristics. It is not preferable because of the nature.

  Further, in order to reduce a decrease in film formation stability due to solvent evaporation from the composition during wet film formation, the solvent of the ink composition for organic EL elements has a boiling point of 100 ° C. or higher, preferably 150 boiling point. It is effective to use a solvent having a boiling point of 200 ° C. or higher, more preferably 200 ° C. or higher.

  The ink composition for an organic EL element of the present invention is preferably used for an organic EL light emitting element in which a light emitting material is a low molecular material and a layer containing the light emitting material is formed by a wet film forming method.

  Since the ink composition for organic EL elements of the present invention contains a light emitting material, it is used for forming a light emitting layer, but may be used for other layers such as a hole transport layer.

  In the present invention, as long as the object of the present invention is not impaired, the ink composition for organic EL elements of the present invention may contain other known light emitting materials in the light emitting layer as desired. A light emitting layer containing another known light emitting material may be laminated on the light emitting layer formed by forming the ink composition for an organic EL element by a wet film forming method. In this case, the light emitting layer containing another known light emitting material may be formed by a dry method such as a vacuum evaporation method.

  In general, the organic EL element is manufactured on a light-transmitting substrate. The translucent substrate referred to here is a substrate that supports the organic EL element, and is preferably a smooth substrate having a light transmittance in the visible region of 400 to 700 nm of 50% or more.

  Specifically, a glass plate, a polymer plate, etc. are mentioned. Examples of the glass plate include soda lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone.

  In the organic EL element ink composition of the present invention, the content of the organic EL element material of the present invention is preferably 0.5 wt% or more. Usually, the thickness of the light-emitting layer of the organic EL element is 10 to 100 nm, but generally it is often 50 nm or more. When the film thickness is less than 50 nm, problems such as a decrease in light emission performance and a large color tone deviation occur. In order to easily form a film thickness of 50 nm or more, the solution concentration is preferably 0.5 wt% or more. When the concentration is lower than 0.5 wt%, it is difficult to form a thick film.

  In addition to the organic EL element material and solvent described above, a known additive may be added to the ink composition for an organic EL element of the present invention as necessary.

  The ink composition for an organic EL device of the present invention is a known wet film forming method, for example, a coating method, an inkjet method, a dip coating method, a die coating method, a spray coating method, a spin coating method, a roll coater method, a dipping coating method. The film can be formed by a screen printing method, a flexographic printing method, a screen printing method, an LB method, or the like.

  Here, the organic EL element which can be produced using the ink composition for organic EL elements of the present invention will be described in detail.

  The organic EL element is composed of an element in which a single layer or a multilayer organic layer is formed between an anode and a cathode. Here, the single layer type organic EL element is an element composed of only a light emitting layer between an anode and a cathode. Point to. On the other hand, the multilayer organic EL element facilitates injection of holes and electrons into the light emitting layer in addition to the light emitting layer, and facilitates recombination of holes and electrons in the light emitting layer. For the purpose of this, it refers to a layer in which a hole injection layer, a hole transport layer, a hole blocking layer, an electron injection layer, and the like are laminated. Further, an interlayer that is adjacent to the light emitting layer between the light emitting layer and the anode and has a role of separating the light emitting layer and the anode or the light emitting layer from the hole injection layer or the hole transport layer. Layers may be inserted. Therefore, typical element configurations of the multilayer organic EL element include (1) anode / hole injection layer / light emitting layer / cathode, and (2) anode / hole injection layer / hole transport layer / light emitting layer / cathode. (3) Anode / hole injection layer / light emitting layer / electron injection layer / cathode, (4) Anode / hole injection layer / hole transport layer / light emitting layer / electron injection layer / cathode, (5) Anode / positive Hole injection layer / light emitting layer / hole blocking layer / electron injection layer / cathode, (6) anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron injection layer / cathode, (7) Anode / light emitting layer / hole blocking layer / electron injection layer / cathode, (8) anode / light emitting layer / electron injection layer / cathode, etc. (9) Anode / hole injection layer / hole transport layer / interlayer layer / light emission Layer / cathode, (10) anode / hole injection layer / interlayer layer / light emitting layer / electron injection layer / cathode, (11) anode / hole injection layer / hole transport layer / in Chromatography / light-emitting layer / electron injection layer / cathode, it is considered elements formed by laminating a multilayer structure of.

  Moreover, each organic layer mentioned above may be formed by the layer structure of two or more layers, respectively, and several layers may be laminated | stacked repeatedly. As such an example, an element configuration called “multi-photon emission” in which a part of the above-described multilayer organic EL element is multilayered has been proposed in recent years for the purpose of improving light extraction efficiency. For example, in an organic EL device composed of a glass substrate / anode / hole transport layer / electron transporting light emitting layer / electron injection layer / charge generating layer / light emitting unit / cathode, the charge generating layer and the light emitting unit There is a method of laminating a plurality of portions.

  The ink composition for organic EL devices of the present invention may be used for any of the above-described layers, but can be suitably used as a light emitting layer material particularly when producing yellow to red light emitting devices. In addition, the ink composition for organic EL devices of the present invention can be used not only as a single compound but also as a combination of two or more compounds, that is, by mixing and laminating. . Furthermore, in the light emitting layer mentioned above, you may use with another material.

For the hole injection layer, a hole injection material that exhibits an excellent hole injection effect with respect to the light emitting layer and that can form a hole injection layer excellent in adhesion to the anode interface and thin film formability is used. In addition, when such materials are laminated in multiple layers and a material having a high hole injection effect and a material having a high hole transport effect are laminated, the materials used for each are called a hole injection material and a hole transport material. Sometimes. The organic EL device material of the present invention can be suitably used for both hole injection materials and hole transport materials. These hole injection materials and hole transport materials need to have a high hole mobility and a small ionization energy of usually 5.5 eV or less. Such a hole injection layer is preferably a material that transports holes to the light emitting layer with a lower electric field strength, and further has a hole mobility of at least when an electric field of 10 ⁴ to 10 ⁶ V / cm is applied. What is 10 ^<-6 > cm ^{< 2} > / V * second is preferable. Other hole injection materials and hole transport materials that can be used by mixing with the organic EL device material of the present invention are not particularly limited as long as they have the above-mentioned preferable properties. Any material can be selected and used from those commonly used as charge transport materials for holes in a conductive material and known materials used for hole injection layers of organic EL devices.

  Specific examples of such hole injection materials and hole transport materials include triazole derivatives (see US Pat. No. 3,112,197) and oxadiazole derivatives (US Pat. No. 3,189,447). Imidazole derivatives (see Japanese Patent Publication No. 37-16096), polyarylalkane derivatives (US Pat. Nos. 3,615,402, 3,820,989, 3,542,544, JP-B-45-555, JP-A-51-10983, JP-A-51-93224, JP-A-55-17105, JP-A-56-4148, JP-A-55- No. 108667, No. 55-156953, No. 56-36656, etc.), pyrazoline derivatives and pyrazolone derivatives (US Pat. No. 3,180, No. 29, No. 4,278,746, JP-A 55-88064, No. 55-88065, No. 49-105537, No. 55-51086, No. 56-80051. No. 56-88141, No. 57-45545, No. 54-112437, No. 55-74546, etc.), phenylenediamine derivatives (US Pat. No. 3,615,404, Japanese Patent Publication Nos. 51-10105, 46-3712, 47-25336, JP 54-53435, 54-110536, 54-1119925, etc.), arylamine Derivatives (US Pat. Nos. 3,567,450, 3,180,703, 3,240,597, 3 No. 658,520, No. 4,232,103, No. 4,175,961, No. 4,012,376, JP-B 49-35702, No. 39 -27577, JP-A-55-144250, JP-A-56-119132, JP-A-56-22437, West German Patent No. 1,110,518, etc.), amino-substituted chalcone derivatives (US patents) No. 3,526,501), oxazole derivatives (disclosed in US Pat. No. 3,257,203, etc.), styryl anthracene derivatives (see JP 56-46234 A, etc.), Fluorenone derivatives (see JP-A-54-110837, etc.), hydrazone derivatives (US Pat. No. 3,717,462, JP-A-54-59143, 55-52063, 55-52064, 55-46760, 55-85495, 57-11350, 57-148749, JP-A-2-311591, etc. Stilbene derivatives (Japanese Patent Laid-Open Nos. 61-210363, 61-228451, 61-14642, 61-72255, 62-47646, 62-36674) 62-10652, 62-30255, 60-93455, 60-94462, 60-174749, 60-175052, etc.), silazane derivatives (US) Patent No. 4,950,950), polysilane (JP-A-2-204996), aniline copolymer (Japanese Unexamined Patent Publication No. 2-282263), Japanese Unexamined Patent Publication No. 1-211399, conductive polymer oligomers (especially thiophene oligomers), polyethylene dioxythiophene / polysulfonic acid (PEDOT / PSS), etc. Can do.

  As the hole injecting material and the hole transporting material, those described above can be used. Porphyrin compounds (Japanese Patent Laid-Open No. 63-295965), aromatic tertiary amine compounds and styrylamine compounds (US Pat. No. 4,127,412, JP-A-53-27033, 54-58445, 54-149634, 54-64299, 55-79450, 55-144250 No. 56-119132, No. 61-295558, No. 61-98353, No. 63-295695, etc.) can also be used. For example, 4,4′-bis (N- (1-naphthyl) -N-phenylamino) biphenyl having two condensed aromatic rings in the molecule described in US Pat. No. 5,061,569, etc. And 4,4 ′, 4 ″ -tris (N- (3-methylphenyl) -N-phenyl, in which three triphenylamine units described in JP-A-4-308688 are linked in a starburst type. Amino) triphenylamine, etc. In addition, examples of the hole injection material include phthalocyanine derivatives such as copper phthalocyanine and hydrogen phthalocyanine, and other aromatic dimethylidene compounds, p-type Si, p-type SiC, etc. These inorganic compounds can also be used as hole injection materials and hole transport materials.

Further, materials that can be used for the hole injection layer include molybdenum oxide (MnO _x ), vanadium oxide (VO _x ), ruthenium oxide (RuO _x ), copper oxide (CuO _x ), tungsten oxide (WO _x ), and iridium oxide. Inorganic oxides such as (IrO _x ) are also included.

  Specific examples of the aromatic tertiary amine derivative include, for example, N, N′-diphenyl-N, N ′-(3-methylphenyl) -1,1′-biphenyl-4,4′-diamine, N, N , N ′, N ′-(4-methylphenyl) -1,1′-phenyl-4,4′-diamine, N, N, N ′, N ′-(4-methylphenyl) -1,1′- Biphenyl-4,4′-diamine, N, N′-diphenyl-N, N′-dinaphthyl-1,1′-biphenyl-4,4′-diamine, N, N ′-(methylphenyl) -N, N '-(4-n-Butylphenyl) -phenanthrene-9,10-diamine, N, N-bis (4-di-4-tolylaminophenyl) -4-phenyl-cyclohexane, N, N'-bis (4 '-Diphenylamino-4-biphenylyl) -N, N'-diphenyl Nzine, N, N′-bis (4′-diphenylamino-4-phenyl) -N, N′-diphenylbenzidine, N, N′-bis (4′-diphenylamino-4-phenyl) -N, N ′ -Di (1-naphthyl) benzidine, N, N'-bis (4'-phenyl (1-naphthyl) amino-4-phenyl) -N, N'-diphenylbenzidine, N, N'-bis (4'- Phenyl (1-naphthyl) amino-4-phenyl) -N, N′-di (1-naphthyl) benzidine and the like can be mentioned, and these can be used for both hole injection materials and hole transport materials.

  Particularly preferred examples of the hole injection material are shown in Table 3.

  Moreover, as a hole transport material which can be used with the organic EL element material of this invention, the compound shown in following Table 4 is also mentioned.

  In order to form the hole injection layer described above, the above-mentioned compound is thinned by a known method such as a vacuum deposition method, a spin coating method, a casting method, or an LB method. The thickness of the hole injection layer is not particularly limited, but is usually 5 nm to 5 μm.

  Examples of the material used for the interlayer layer include polymers containing aromatic amines such as polyvinylcarbazole and derivatives thereof, polyarylene derivatives having aromatic amines in the side chain or main chain, arylamine derivatives, and triphenyldiamine derivatives. In addition, as a method for forming the interlayer layer, when a high molecular weight material is used, a method by film formation from a solution is exemplified.

  For the formation of an interlayer layer from a solution, a known wet film forming method, for example, a spin coating method, a casting method, a micro gravure coating method, a gravure coating method, a bar coating method, a roll coating method, a wire bar coating method, Coating methods such as a dip coating method, a spray coating method, a screen printing method, a flexographic printing method, an offset printing method, an ink jet printing method, a capillary coating method, and a nozzle coating method can be used.

  The thickness of the interlayer layer varies depending on the material to be used, and may be selected so that the driving voltage and the light emission efficiency are appropriate values. Usually, the thickness is 1 nm to 1 μm, preferably 2 to 500 nm. More preferably, it is 5-200 nm.

  On the other hand, for the electron injection layer, an electron injection material that exhibits an excellent electron injection effect with respect to the light emitting layer and that can form an electron injection layer excellent in adhesion to the cathode interface and thin film formability is used. Examples of such electron injection materials include metal complex compounds, nitrogen-containing five-membered ring derivatives, fluorenone derivatives, anthraquinodimethane derivatives, diphenoquinone derivatives, thiopyrandioxide derivatives, perylenetetracarboxylic acid derivatives, fluorenylidenemethane. Derivatives, anthrone derivatives, silole derivatives, triarylphosphine oxide derivatives, polyquinoline and its derivatives, polyquinoxaline and its derivatives, polyfluorene and its derivatives, calcium acetylacetonate, sodium acetate and the like. In addition, inorganic / organic composite materials doped with metal such as cesium in bathophenanthroline (Proceedings of the Society of Polymer Science, Vol. 50, No. 4, 660, published in 2001), and the 50th Applied Physics Related Lecture Lecture Proceedings, No. Examples of electron injection materials include BCP, TPP, T5MPyTZ, etc., published on page 3, 1402, 2003. However, a thin film necessary for device fabrication can be formed, electrons from the cathode can be injected, and electrons can be transported. If it is material, it will not specifically limit to these.

  Preferable examples of the electron injection material include metal complex compounds, nitrogen-containing five-membered ring derivatives, silole derivatives, and triarylphosphine oxide derivatives. As a preferable metal complex compound that can be used in the present invention, a metal complex of 8-hydroxyquinoline or a derivative thereof is suitable. Specific examples of the metal complex of 8-hydroxyquinoline or a derivative thereof include tris (8-hydroxyquinolinate) aluminum, tris (2-methyl-8-hydroxyquinolinato) aluminum, tris (4-methyl-8- Hydroxyquinolinato) aluminum, tris (5-methyl-8-hydroxyquinolinato) aluminum, tris (5-phenyl-8-hydroxyquinolinato) aluminum, bis (8-hydroxyquinolinato) (1-naphtholate) ) Aluminum, bis (8-hydroxyquinolinate) (2-naphtholate) aluminum, bis (8-hydroxyquinolinate) (phenolate) aluminum, bis (8-hydroxyquinolinato) (4-cyano-1-naphtholate) ) Aluminum, bis (4-methyl-8) Hydroxyquinolinato) (1-naphtholato) aluminum, bis (5-methyl-8-hydroxyquinolinato) (2-naphtholato) aluminum, bis (5-phenyl-8-hydroxyquinolinato) (phenolate) aluminum, Bis (5-cyano-8-hydroxyquinolinate) (4-cyano-1-naphtholato) aluminum, bis (8-hydroxyquinolinato) chloroaluminum, bis (8-hydroxyquinolinato) (o-cresolate) Aluminum complex compounds such as aluminum, tris (8-hydroxyquinolinato) gallium, tris (2-methyl-8-hydroxyquinolinato) gallium, tris (4-methyl-8-hydroxyquinolinato) gallium, tris ( 5-Methyl-8-hydroxyquinolinate Gallium, tris (2-methyl-5-phenyl-8-hydroxyquinolinato) gallium, bis (2-methyl-8-hydroxyquinolinato) (1-naphtholato) gallium, bis (2-methyl-8-hydroxy) Quinolinate) (2-naphtholato) gallium, bis (2-methyl-8-hydroxyquinolinato) (phenolate) gallium, bis (2-methyl-8-hydroxyquinolinato) (4-cyano-1-naphtholate) ) Gallium, bis (2,4-dimethyl-8-hydroxyquinolinato) (1-naphtholate) gallium, bis (2,5-dimethyl-8-hydroxyquinolinato) (2-naphtholato) gallium, bis (2 -Methyl-5-phenyl-8-hydroxyquinolinate) (phenolate) gallium, bis (2-methyl-5- Cyano-8-hydroxyquinolinate) (4-cyano-1-naphtholate) gallium, bis (2-methyl-8-hydroxyquinolinate) chlorogallium, bis (2-methyl-8-hydroxyquinolinate) ( In addition to gallium complex compounds such as o-cresolate) gallium, 8-hydroxyquinolinate lithium, bis (8-hydroxyquinolinato) copper, bis (8-hydroxyquinolinato) manganese, bis (10-hydroxybenzo [h ] Quinolinato) metal complex compounds such as beryllium, bis (8-hydroxyquinolinato) zinc, bis (10-hydroxybenzo [h] quinolinato) zinc.

  Among the electron injection materials that can be used in the present invention, preferable nitrogen-containing five-membered ring derivatives include oxazole derivatives, thiazole derivatives, oxadiazole derivatives, thiadiazole derivatives, and triazole derivatives. , 5-bis (1-phenyl) -1,3,4-oxazole, 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-phenyloxadiazolyl) -4-tert-butyl benzene], 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) -1,3,4-triazole, 1,4-bis [2- (5-phenyltriazolyl)] benzene and the like can be mentioned.

  Specific examples of particularly preferred oxadiazole derivatives among the electron injection materials that can be used in the present invention are shown in Table 5.

  Specific examples of particularly preferred triazole derivatives among the electron injection materials that can be used in the present invention are shown in Table 6. In Table 6, Ph represents a phenyl group.

  Specific examples of particularly preferred silole derivatives among the electron injection materials that can be used in the present invention are shown in Table 7.

  Furthermore, a hole blocking material that can prevent holes from passing through the light emitting layer from reaching the electron injection layer and form a layer having excellent thin film formability is used for the hole blocking layer. Examples of such hole blocking materials include aluminum complex compounds such as bis (8-hydroxyquinolinate) (4-phenylphenolate) aluminum, and bis (2-methyl-8-hydroxyquinolinate) ( Examples include gallium complex compounds such as 4-phenylphenolate) gallium and nitrogen-containing condensed aromatic compounds such as 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP).

The light emitting layer of the organic EL device of the present invention preferably has the following functions.
Injection function; function transport function that can inject holes from the anode or hole injection layer when an electric field is applied, and electrons from the cathode or electron injection layer; electric field of injected charges (electrons and holes) Light emitting function: A function that provides a field for recombination of electrons and holes and connects it to light emission. However, there is a difference between the ease of hole injection and the ease of electron injection. In addition, the transport ability represented by the mobility of holes and electrons may be large or small.

  In the organic EL device of the present invention, a phosphorescent material can also be used. In this case, the phosphorescent material is used as a dopant material in the light emitting layer, and the compound (A) and the compound (B) of the present invention can be used as a host material in the light emitting layer. The phosphorescent light-emitting material here means a compound that emits light when transitioning from an excited triplet state to a ground state. Examples of phosphorescent materials that can be used in the organic electroluminescent device of the present invention include organometallic complexes, where the metal atom is usually a transition metal, preferably in the fifth or sixth period, in terms of group, Group 6 to 11 elements, more preferably group 8 to 11 elements are targeted. Specific examples include iridium, platinum, and copper. 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, and the central metal includes platinum. For example, known compounds shown in Table 8 are suitably used as the phosphorescent material.

Furthermore, the material used for the anode of the organic EL device of the present invention is preferably a material having a work function (4 eV or more) metal, alloy, electrically conductive compound or a mixture thereof as an electrode substance. Specific examples of such an electrode substance include metals such as Au and conductive materials such as CuI, ITO, SnO ₂ and ZnO. In order to form this anode, a thin film can be formed from these electrode materials by a method such as vapor deposition or sputtering. The anode desirably has such a characteristic that when light emitted from the light emitting layer is extracted from the anode, the transmittance of the anode for light emission is greater than 10%. The sheet resistance of the anode is preferably several hundred Ω / □ or less. Further, although the film thickness of the anode depends on the material, it is usually selected in the range of 10 nm to 1 μm, preferably 10 to 200 nm.

  The material used for the cathode of the organic EL device of the present invention is a material having a small work function (4 eV or less) metal, alloy, electrically conductive compound and a mixture thereof as an electrode substance. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / silver alloy, aluminum / aluminum oxide, aluminum / lithium alloy, indium, and rare earth metals. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. Here, when light emitted from the light-emitting layer is extracted from the cathode, the transmittance of the cathode for light emission is preferably greater than 10%. The sheet resistance as a cathode is preferably several hundred Ω / □ or less, and the film thickness is usually 10 nm to 1 μm, preferably 50 to 200 nm.

  Regarding the method for producing the organic EL device of the present invention, an anode, a light emitting layer, a hole injection layer as necessary, and an electron injection layer as necessary are formed by the above materials and methods, and finally a cathode is formed. do it. Moreover, an organic EL element can also be produced from the cathode to the anode in the reverse order.

  This organic EL element is manufactured on a translucent substrate. This translucent substrate is a substrate that supports the organic EL element, and for the translucency, it is desirable that the transmittance of light in the visible region of 400 to 700 nm is 50% or more, preferably 90% or more, Further, it is preferable to use a smooth substrate.

  These substrates have mechanical and thermal strengths and are not particularly limited as long as they are transparent. For example, glass plates, synthetic resin plates and the like are preferably used. Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the synthetic resin plate include plates such as polycarbonate resin, acrylic resin, polyethylene terephthalate resin, polyether sulfide resin, and polysulfone resin.

  As a method for forming each layer of the organic EL element of the present invention, a dry film forming method such as vacuum deposition, electron beam irradiation, sputtering, plasma, ion plating, or a wet film forming method such as spin coating, dipping, or flow coating is used. Either method can be applied. In addition, Special Table 2002-53482, S.I. T.A. Lee, et al. , Proceedings of SID'02, p. LITI (Laser Induced Thermal Imaging) method described in 784 (2002), printing (offset printing, flexographic printing, gravure printing, screen printing), inkjet, and the like can also be applied.

  Further, in order to improve the stability of the organic EL element with respect to temperature, humidity, atmosphere and the like, a protective layer may be provided on the surface of the element, or the entire element may be covered or sealed with a resin or the like. In particular, when the entire element is covered or sealed, a photocurable resin that is cured by light is preferably used.

  The current applied to the organic EL element of the present invention is usually a direct current, but a pulse current or an alternating current may be used. The current value and the voltage value are not particularly limited as long as the element is within a range not destroying the element. However, considering the power consumption and life of the element, it is desirable to efficiently emit light with as little electrical energy as possible.

  The organic EL device driving method of the present invention can be driven not only by the passive matrix method but also by the active matrix method. Further, the method for extracting light from the organic EL device of the present invention is applicable not only to the method of bottom emission for extracting light from the anode side but also to the method of top emission for extracting light from the cathode side. These methods and techniques are described in Shinji Kido, “All about organic EL”, published by Nihon Jitsugyo Shuppansha (published in 2003).

  Examples of the main method of full colorization of the organic EL device of the present invention include a three-color coating method, a color conversion method, and a color filter method. In the three-color coating method, an evaporation method using a shadow mask, an ink jet method, and a printing method can be used. In addition, Special Table 2002-53482, S.I. T.A. Lee, et al. , Proceedings of SID'02, p. 784 (2002) can also be used. The laser thermal transfer method (also referred to as Laser Induced Thermal Imaging, LITI method) can also be used. In the color conversion method, a blue light emitting layer is used to convert green and red having a longer wavelength than blue through a color conversion (CCM) layer in which fluorescent dyes are dispersed. The color filter method uses a white light emitting organic EL element to extract light of three primary colors through a color filter for liquid crystal. In addition to these three primary colors, a part of white light is directly extracted and used for light emission. Thus, the luminous efficiency of the entire device can be increased.

  Furthermore, the organic EL element of the present invention may adopt a microcavity structure. This is because the organic EL element has a structure in which the light emitting layer is sandwiched between the anode and the cathode, and the emitted light causes multiple interference between the anode and the cathode, but the reflectance and transmission of the anode and the cathode This is a technology that actively uses the multiple interference effect and controls the emission wavelength extracted from the device by appropriately selecting the optical characteristics such as the rate and the film thickness of the organic layer sandwiched between them. . Thereby, it is also possible to improve the emission chromaticity. For the mechanism of this multiple interference effect, see J.A. Yamada et al., AM-LCD Digest of Technical Papers, OD-2, p. 77-80 (2002).

  As described above, the organic EL device of the present invention emits yellow to red light, can improve characteristics such as light emission efficiency and maximum light emission luminance, and has a long life. Since this organic EL element has a light emission luminance that can be used practically at a low driving voltage, it can reduce deterioration that has been a major problem until now. Therefore, this organic EL element can be suitably used as a flat panel display such as a wall-mounted television or a flat light emitter, and further, a light source such as a copying machine or a printer, a light source such as a liquid crystal display or instruments, a display plate, It can be applied to beacon lights.

  Hereinafter, although the following Example demonstrates the ink composition for organic EL elements of this invention, this invention is not limited to the following Example.

Example 1
Solubility measurement of compound (A01)

  In the ink composition for organic EL elements of the present invention, it is preferable that the solubility of the compound (A) in a solvent is high. This is because if the solubility of the compound (A) in the solvent is low, a uniform and stable film cannot be obtained when a thin film is formed by a spin coating method or the like. Therefore, the solubility of the compound (A01) in toluene was examined, and the results are shown in Table 9. As shown in Table 9, the compound (A01) exhibited a solubility sufficient for film formation in toluene.

Examples 2-50
Instead of the compound (A01), the compounds shown in Table 9 were used to examine the solubility in toluene. The results are shown in Table 9.

Comparative Example 1
As a comparative example, the solubility in toluene was investigated using the following comparative compound (C01) and compound (C02). The results are shown in Table 9.

  As shown in Table 9, the compound (C01) and the compound (C02) did not exhibit sufficient solubility for film formation in toluene. From these results, it was shown that the compound (A) has sufficient solubility in a solvent to be used for the ink composition for an organic EL device.

Next, although the organic EL element using the ink composition for organic EL elements of the present invention will be described with reference to the following examples, the present invention is not limited to the following examples. 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 under conditions where temperature control such as heating and cooling of the substrate was not performed. The spin coating was rotated for 1 minute at a rotational speed between 500 rpm and 2500 rpm in accordance with the solvent type and the target film thickness. The light emission characteristics of the element were measured using an organic EL element having a light emitting element area of 2 mm × 2 mm.

Example 51
On the washed glass plate with an ITO electrode, the compound (A09) and the compound (B45) shown in Table 1 were dissolved in toluene at a weight ratio of 93: 7 to prepare a 2% by weight solution. A hole injection type light emitting layer having a film thickness of 50 nm was formed by spin coating. A bis (2-methyl-8-hydroxyquinolinate) (1-naphtholate) gallium complex is deposited on the obtained hole-injection light-emitting layer to produce an electron-injection layer having a thickness of 40 nm. An alloy in which magnesium and silver were mixed at a ratio of 10: 1 was deposited thereon to form an electrode having a thickness of 100 nm, thereby obtaining an organic EL element (two-layer type).

With this element, emission luminance at a DC voltage of 5V 2100 (cd / m ² ), maximum emission luminance 14200 (cd / m ² ), luminance half life 560 (h), CIE (x, y) = (0.63, A red emission of 0.31) was obtained.

Example 52
4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (α-NPD) is vacuum-deposited on the cleaned glass plate with an ITO electrode to form a hole injection layer having a thickness of 30 nm. Formed. Next, on this hole injection layer, the compound (A04) and the compound (B03) shown in Table 1 were dissolved in toluene at a weight ratio of 95: 5 to prepare a 2 wt% solution. A light emitting layer having a thickness of 50 nm was formed by spin coating. On top of that, bis (2-methyl-5-phenyl-8-hydroxyquinolinate) (phenolate) gallium complex is deposited to form an electron injection layer with a thickness of 30 nm, and further, magnesium and silver are added thereon. An alloy mixed at a ratio of 10: 1 was deposited to form an electrode having a thickness of 100 nm, and an organic EL element (three-layer type) was obtained.

With this element, emission luminance 4150 (cd / m ² ) at a DC voltage of 5 V, maximum emission luminance 43100 (cd / m ² ), luminance half-life> 1000 (h), CIE (x, y) = (0.64) , 0.32) red light emission was obtained.

Examples 53-100
Similar to Example 52 except that the light emitting layer was prepared using the compounds shown in Table 1 and Table 2 in the ratios shown in Table 10 instead of the compound (A04) and Compound (B03) used in Example 52. An organic EL device was obtained under the conditions described above.

  The light emission characteristics of the obtained device are shown in Table 10. The “emission brightness” in the table represents a value when DC 5 V is applied. All of the organic EL devices of these examples exhibited yellow to red light emission having high luminance characteristics of a luminance half life of 1000 (h) or more and a maximum emission luminance of 30000 (cd / m 2) or more.

Comparative Example 3
The same procedure as in Example 52 was carried out except that the light emitting layer was prepared using the comparative compound (C03) and the comparative compound (C04) shown below in the ratios shown in Table 10 instead of the compound (A04) and the compound (B03) used in Example 52. An organic EL device was obtained under the same conditions as in Example 52. The results are shown in Table 10.

  As is clear from Table 10, all of the organic EL elements of the present invention had a longer lifetime and higher luminance than the organic EL element prepared in Comparative Example 3.

Example 101
HIM3 in Table 3 was dissolved in toluene at a concentration of 2% by weight, and a hole injection layer having a thickness of 70 nm was formed on a glass plate with an ITO electrode by spin coating using the obtained solution. Next, the compound (A04) in Table 1 and the compound (B45) in Table 2 were dissolved in xylene at a weight ratio of 97: 3 to prepare a 1.5 wt% solution, and the resulting solution was used. A light emitting layer with a thickness of 40 nm was formed by spin coating. Further, Compound EX5 of Table 5 was dissolved in toluene at a concentration of 2% by weight, and an electron injection layer having a thickness of 20 nm was formed by spin coating using the obtained solution. A cathode was formed thereon by vapor deposition of 1 nm of lithium oxide (Li ₂ O) and 100 nm of Al to obtain an organic EL device.

With this element, emission luminance at a DC voltage of 5V 2610 (cd / m ² ), maximum emission luminance 27600 (cd / m ² ), luminance half-life> 1000 (h), CIE (x, y) = (0.62) , 0.30) red light emission was obtained.

Examples 102-125
The same as Example 101 except that the light emitting layer was prepared using the compounds shown in Table 1 and Table 2 in the ratios shown in Table 11 instead of the compound (A04) and the compound (B45) used in Example 101. An organic EL device was obtained under the conditions described above.

  The light emission characteristics of the obtained device are shown in Table 11. The “emission brightness” in the table represents a value when DC 5 V is applied. All of the organic EL devices of these examples exhibited yellow to red light emission with high luminance characteristics of a luminance half life of 1000 (h) or more and a maximum emission luminance of 25000 (cd / m 2) or more.

Comparative Example 4
Except that the light emitting layer was prepared by using the comparative compound (C05) and the comparative compound (C06) shown below in the ratio shown in Table 11 instead of the compound (A04) and the compound (B45) used in Example 101, An organic EL device was obtained under the same conditions as in Example 101. The results are shown in Table 11.

  As is clear from Table 11, all the organic EL elements of the present invention had a longer lifetime and higher luminance than the organic EL element prepared in Comparative Example 4.

Example 126
A film of poly (3,4-ethylenedioxythiophene) / polystyrene sulfonic acid (manufactured by HC Starck, trade name: CLEVIOS P CH8000) was formed on a cleaned glass plate with an ITO electrode by a spin coating method. A hole injection layer having a thickness of 80 nm was obtained. Next, the compound (A04) in Table 1 and the compound (B49) in Table 2 are dissolved in isopropyl alcohol at a weight ratio of 99: 1 to prepare a 1% by weight solution, and spin is performed using the obtained solution. A light emitting layer having a thickness of 50 nm was formed by coating. Further, the compound of Table 6 (ET7) was dissolved in toluene at a concentration of 2% by weight, and an electron injection layer having a thickness of 30 nm was formed by spin coating using the obtained solution. A cathode was formed thereon by vapor deposition of 1 nm of lithium oxide (Li ₂ O) and 100 nm of Al to obtain an organic EL device.

With this element, emission luminance at a DC voltage of 5 V is 3880 (cd / m ² ), maximum emission luminance is 41200 (cd / m ² ), luminance half life> 1000 (h), CIE (x, y) = (0.64) , 0.31) red light emission was obtained.

Examples 127-150
Similar to Example 126 except that the light-emitting layer was prepared using the compounds shown in Table 1 and Table 2 in the ratios shown in Table 12 instead of the compound (A04) and Compound (B49) used in Example 126. An organic EL device was obtained under the conditions described above.

  The light emission characteristics of the obtained device are shown in Table 12. The “emission brightness” in the table represents a value when DC 5 V is applied. All of the organic EL devices of these examples exhibited yellow to red light emission having high luminance characteristics of a luminance half life of 1000 (h) or more and a maximum emission luminance of 30000 (cd / m 2) or more.

Comparative Example 5
Example except that the light emitting layer was prepared using the comparative compound (C07) and the comparative compound (C08) shown below in the ratios in the table instead of the compound (A04) and the compound (B49) used in Example 127 An organic EL device was obtained under the same conditions as in 101. The results are shown in Table 12.

  As is clear from Table 12, all the organic EL elements of the present invention had a longer lifetime and higher luminance than the organic EL element prepared in Comparative Example 5.

Example 151
On the glass plate with an ITO electrode, HIM2 was vapor-deposited to form a 65 nm-thick hole injection layer. Next, the compound (A04) in Table 1, the compound (B03) in Table 2, and the compound (PLM8) in Table 8 are dissolved in acetone at a weight ratio of 85: 10: 5 to prepare a 1 wt% solution. Then, a light emitting layer having a film thickness of 45 nm was formed by spin coating using the obtained solution. Furthermore, ES2 in Table 7 was deposited to form an electron transport layer having a thickness of 20 nm. On top of that, Alq3 is vacuum-deposited to form an electron injection layer having a film thickness of 10 nm, and then an electrode is formed by first depositing 1 nm of lithium fluoride and then 200 nm of Al to form an organic EL device. It was.

With this element, emission luminance at a DC voltage of 5 V 3520 (cd / m ² ), maximum emission luminance 39700 (cd / m ² ), luminance half-life> 1000 (h), CIE (x, y) = (0.63) , 0.32) red light emission was obtained.

  As described above, by using the ink composition for an organic EL device of the present invention, a high performance EL device can be produced. It is clear that remarkably high performance is exhibited with respect to the comparative compound, and high light emission efficiency, low drive voltage, long life, and high color purity yellow to red light emission of the organic EL element can be achieved.

Claims (4)

An ink composition for an organic electroluminescence device comprising a compound (A) represented by the following general formula [1], a compound (B) represented by the following general formula [2], and a solvent.
General formula [1]

[Wherein Ar ¹ represents a substituted or unsubstituted perylenyl group;
R ¹ and R ² are each independently a substituted or unsubstituted monovalent aromatic hydrocarbon group, or a substituted or unsubstituted monovalent aromatic heterocyclic group.
Ar ¹ and R ¹ , Ar ¹ and R ² , R ¹ and R ² may be bonded to each other to form a ring. ]
General formula [2]

[Wherein, R ^{3 to} R ⁸ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group or an aryl group (which may have a hetero atom in the ring).
Ar ² and Ar ³ each independently represent a substituted or unsubstituted aryl group (which may have a hetero atom in the ring).
X ¹ and X ² each independently represent O, S, Se, NE ¹ or CE ² E ³ , E ¹ represents an electron-withdrawing group, and E ² and E ³ represent a hydrogen atom or a substituent. At least one of them represents an electron withdrawing group. ]   The ink composition for organic electroluminescent elements according to claim 1, wherein compound (A) is a host and compound (B) is a dopant.   The organic electroluminescent element formed by forming a plurality of organic layers including a light emitting layer between a pair of electrodes, wherein at least one of the organic layers wets the ink composition for an organic electroluminescent element according to claim 1 or 2. An organic electroluminescence element which is a layer formed by a film forming method.   In the organic electroluminescent element formed by forming a light emitting layer or a plurality of organic layers including a light emitting layer between a pair of electrodes, the light emitting layer wets the ink composition for an organic electroluminescent element according to claim 1 or 2. An organic electroluminescence element which is a layer formed by a film forming method.