JP2015199752A - Iridium complex mixture, organic electroluminescent element and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an iridium complex mixture that is excellent in solubility, can be easily produced, and is excellent in durability of an element; an organic electroluminescent element using the iridium complex mixture; and a method for producing the same.SOLUTION: The iridium complex mixture has two or more iridium complexes represented by general formula (1) defined by (A)Ir(B)[A and B are bidentate ligands having different structures; A has a structure represented by general formula (2), where Rto Rare alkyl groups; and m is an integer from 0 to 2, and n is an integer from 1 to 3, satisfying m+n=3]. The bidentate ligands represented by B in the formula of at least two iridium complexes among the two or more iridium complexes are bidentate ligands having the same structure.

Description

  The present invention relates to an iridium complex mixture applicable to an organic layer of an organic electroluminescent device, an organic electroluminescent device, and a method for producing the same.

  In recent years, iridium complexes have been actively researched and developed as materials for organic electroluminescent devices because of their high luminous efficiency.

  Organic electroluminescence devices have features such as self-emission and high-speed response, and are expected to be applied to flat panel displays. In particular, organic thin films (hole transport layer) that have a hole transport property and organic materials that have an electron transport property. Since a two-layer type (laminated type) in which a thin film (electron transport layer) is laminated is reported, it has attracted attention as a large-area light-emitting element that emits light at a low voltage of 10 V or less. The stacked organic electroluminescent element has a basic configuration of positive electrode / hole transport layer / light emitting layer / electron transport layer / negative electrode.

In the manufacture of an organic electroluminescent element, generally, a method of forming each layer by a vacuum deposition method is performed.
However, the method of forming a layer by vacuum vapor deposition has a problem that a large vapor deposition apparatus is required and the cost is high. Further, there is a problem that it is difficult to increase the area of the manufactured organic electroluminescent device.

On the other hand, as a method that can be manufactured at a low cost and capable of manufacturing a large-area organic electroluminescent device, there is a coating method in which a light emitting layer is formed by coating using a coating solution.
However, since the iridium complex has low solubility in a solvent, a uniform and stable coating solution cannot be obtained. Therefore, even if a layer is formed using this coating solution, there is a problem that a uniform layer cannot be obtained and the durability of the layer is poor. Therefore, the layer containing the iridium complex is currently formed by a vacuum deposition method.

In order to increase the solubility of the iridium complex in the solvent, it is effective to make the structure of the iridium complex asymmetric about the iridium atom by using different ligands.
However, since the iridium complex having this asymmetric structure is synthesized using a plurality of ligands, it is difficult to synthesize only one kind of iridium complex. A mixture with an iridium complex having a different structure is obtained. When such an iridium complex mixture is used in the organic layer of an organic electroluminescent device, there is usually a problem that the durability of the device is lowered.
In addition, in order to obtain only the desired iridium complex from the synthesized iridium complex mixture, it is usually necessary to perform purification such as chromatography. However, many iridium complexes are difficult to purify, and purification is costly. There is a problem that it takes.

As a technique for solving these problems, firstly, a technique of an iridium complex mixture having an asymmetric structure using a 2-phenylisoquinoline derivative as one of ligands has been proposed (Patent Document 1).
However, the proposed technique has not yet reached the desired degree of solubility in the solvent of the resulting iridium complex mixture. Moreover, when the obtained iridium complex mixture is used for an organic electroluminescent element, there exists a problem that durability of an organic electroluminescent element is low.

Secondly, a technique related to an asymmetric iridium complex in which two types of ligands are used and one of the ligands has a nitro group has been proposed (Patent Document 2).
However, this proposed technique has not yet achieved the desired degree of solubility of the resulting iridium complex in a solvent.

Thirdly, a technique using an iridium complex having a 2-phenylpyridine derivative ligand having an alkyl group of a tertiary or quaternary carbon atom as a substituent has been proposed (Patent Document 3). .
However, the proposed iridium complex has not yet reached the desired degree of solubility in solvents. Moreover, in order to synthesize this iridium complex, there is a problem that purification such as chromatography is required.
In this proposal, no study has been made on an iridium complex mixture obtained by mixing two or more iridium complexes.

  Furthermore, since the iridium complex has a low yield in synthesis, an iridium complex that can be synthesized at a high yield is desired, but the iridium complexes proposed in Patent Documents 1 to 3 have a low yield in synthesis. There's a problem.

  Therefore, an iridium complex mixture having excellent solubility in a solvent, high yield in synthesis, no need for purification such as chromatography, easy production, and excellent durability of the device when used in an organic electroluminescent device In addition, there is a demand for providing an organic electroluminescent device using the iridium complex mixture and a method for producing the same.

Special table 2008-528754 JP-T-2006-507279 JP 2008-91894 A

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, the present invention is excellent in solubility in a solvent, has a high yield in synthesis, is easy to manufacture without the need for purification such as chromatography, and further, when used in an organic electroluminescent device, it has improved device durability. It is an object of the present invention to provide an excellent iridium complex mixture, an organic electroluminescence device using the iridium complex mixture, and a production method thereof.

Means for solving the problems are as follows. That is,
<1> having two or more iridium complexes represented by the following general formula (1),
The bidentate ligand represented by B in the following general formula (1) of at least two iridium complexes of the two or more iridium complexes is a bidentate ligand having the same structure. Is an iridium complex mixture.
(A) _m Ir (B) _n General formula (1)
However, in the said General formula (1), A and B represent the bidentate ligand of a different structure. A has a structure represented by the following general formula (2). m represents an integer of 0 to 2, n represents an integer of 1 to 3, and m + n = 3.
However, in said general formula (2), R < ₁ >, R < ₂ > and R < ₃ > represent an alkyl group each independently.
<2> The iridium complex mixture according to <1>, wherein the iridium of the iridium complex and the bidentate ligand are bonded to each other with a nitrogen atom and a carbon atom of the bidentate ligand.
<3> The iridium complex mixture according to any one of <1> to <2>, wherein the iridium complex represented by the general formula (1) is an iridium complex represented by the following general formula (3).
In the general formula _{(3), R} 4 ~R ₁₉ independently represents a hydrogen atom, a fluorine atom, an alkyl group, an aryl group, an alkoxy group, adjacent _R 4 _{to R 19} are bonded to each other A ring may be formed. At least one of R _{4 to} R ₁₁ has a structure represented by the following general formula (2). m, n and m + n are the same as m, n and m + n in the general formula (1), respectively.
However, in said general formula (2), R < ₁ >, R < ₂ > and R < ₃ > represent an alkyl group each independently.
<4> The above-mentioned <1> to <3>, wherein one iridium complex among the iridium complexes in which m is not 0 is 91% by mass or more and 99.99% by mass or less with respect to the total amount of all iridium complexes. The iridium complex mixture according to any one of the above.
<5> The iridium complex according to any one of <1> to <4>, wherein the iridium complex in which m is 1 is 91% by mass to 99.99% by mass with respect to the total amount of all iridium complexes. It is a mixture.
<6> The iridium complex mixture according to any one of <1> to <5>, wherein the two or more iridium complexes are main products and by-products in the synthesis of the iridium complex.
<7> having at least one organic layer between the anode and the cathode,
An organic electroluminescent device, wherein at least one of the organic layers is an organic layer containing the iridium complex mixture according to any one of <1> to <6>.
<8> The organic electroluminescence device according to <7>, wherein the organic electroluminescence device has three or more organic layers.
<9> The organic electroluminescent element according to any one of <7> to <8>, wherein the organic layer containing the iridium complex mixture is a light emitting layer.
<10> The organic electroluminescent element according to any one of <7> to <8>, wherein the organic layer containing the iridium complex mixture is a hole injection layer.
<11> A method for producing an organic electroluminescent device for producing an organic electroluminescent device according to any one of <7> to <10>, wherein an organic layer containing an iridium complex mixture is formed by coating. It is a manufacturing method of the organic electroluminescent element characterized.

  According to the present invention, the conventional problems can be solved, the solubility in a solvent is excellent, the yield in synthesis is high, the production is easy without the need for purification such as chromatography, and organic electroluminescence is further achieved. It is possible to provide an iridium complex mixture excellent in durability of an element when used in an element, an organic electroluminescent element using the iridium complex mixture, and a method for producing the same.

(Iridium complex mixture)
The iridium complex mixture of this invention has 2 or more types of iridium complexes represented by following General formula (1), and also has another compound as needed.

<Iridium complex>
As said iridium complex, if it is an iridium complex represented by following General formula (1), there will be no restriction | limiting in particular, According to the objective, it can select suitably.
(A) _m Ir (B) _n General formula (1)
However, in the said General formula (1), A and B represent the bidentate ligand of a different structure. A has a structure represented by the following general formula (2). m represents an integer of 0 to 2, n represents an integer of 1 to 3, and m + n = 3.
However, in said general formula (2), R < ₁ >, R < ₂ > and R < ₃ > represent an alkyl group each independently.

There is no restriction | limiting in particular as said bidentate ligand, According to the objective, it can select suitably, For example, the bidentate ligand represented by the following formula | equation is mentioned.
(In the formula, * represents a site bonded to iridium. R independently represents a hydrogen atom or a substituent.)

  There is no restriction | limiting in particular as an aspect of a coupling | bonding of the iridium of the said iridium complex, and a bidentate ligand, According to the objective, it can select suitably, For example, it couple | bonds with the nitrogen atom and carbon atom of a bidentate ligand Embodiment in which the bidentate ligand is bonded with two nitrogen atoms Embodiment in which the bidentate ligand is bonded with two carbon atoms Carbon atom and oxygen atom in the bidentate ligand The mode which is couple | bonded by two oxygen atoms of a bidentate ligand, etc. are mentioned. Among these, the aspect which couple | bonds with the nitrogen atom and carbon atom of a bidentate ligand is preferable at the point which is excellent in thermal stability.

In the general formula (2), R ₁ , R ₂ , and R ₃ each independently represents an alkyl group. R ₁ , R ₂ , and R ₃ are not particularly limited as long as they are alkyl groups, and can be appropriately selected according to the purpose. Examples thereof include linear alkyl groups, branched alkyl groups, and cyclic alkyl groups. Groups.
There is no restriction | limiting in particular as carbon number of the said alkyl group, Although it can select suitably according to the objective, C1-C10 is preferable, C1-C6 is more preferable, C1-C3 is especially preferable.
Examples of the alkyl group include methyl group, ethyl group, propyl group, i-propyl group, butyl group, i-butyl group, s-butyl group, t-butyl group, pentyl group, hexyl group, cyclohexyl group, heptyl. Group, octyl group, 2-ethylhexyl group, nonyl group, decyl group, 3,7-dimethyloctyl group, trifluoromethyl group, pentafluoroethyl group, perfluorobutyl group, perfluorohexyl group, perfluorooctyl group, etc. Can be mentioned.

  There is no restriction | limiting in particular as a structure represented by the said General formula (2), Although it can select suitably according to the objective, t-butyl group, t-amyl group, 3-methylpentane-3-yl group The 2-methylpentan-2-yl group is preferable because it is excellent in solubility in a solvent and carrier transportability (charge transfer).

The iridium complex represented by the general formula (1) is preferably an iridium complex represented by the following general formula (3) from the viewpoint of excellent thermal stability and solubility in a solvent.
In the general formula _{(3), R} 4 ~R ₁₉ independently represents a hydrogen atom, a fluorine atom, an alkyl group, an aryl group, an alkoxy group, adjacent _R 4 _{to R 19} are bonded to each other A ring may be formed. At least one of R _{4 to} R ₁₁ has a structure represented by the following general formula (2). m, n and m + n are the same as m, n and m + n in the general formula (1), respectively.
In addition, the bidentate ligand having R _{4 to} R ₁₁ corresponds to the bidentate ligand of A in the general formula (1). The bidentate ligand having R _{12 to} R ₁₉ corresponds to the bidentate ligand of B in the general formula (1).
However, in said general formula (2), R < ₁ >, R < ₂ > and R < ₃ > represent an alkyl group each independently. Examples and preferred embodiments of R ₁ , R ₂ and R ₃ are the same as described above.

In the general formula (3), R _{4 to} R ₁₉ each independently represent a hydrogen atom, a fluorine atom, an alkyl group, an aryl group, or an alkoxy group, and adjacent R _{4 to} R ₁₉ are bonded to each other to form a ring. It may be formed.

There is no restriction | limiting in particular as said alkyl group, According to the objective, it can select suitably, For example, a linear alkyl group, a branched alkyl group, and a cyclic | annular alkyl group are mentioned.
There is no restriction | limiting in particular as carbon number of the said alkyl group, Although it can select suitably according to the objective, C1-C10 is preferable, C1-C6 is more preferable, C1-C3 is especially preferable.
Examples of the alkyl group include methyl group, ethyl group, propyl group, i-propyl group, butyl group, i-butyl group, s-butyl group, t-butyl group, pentyl group, hexyl group, cyclohexyl group, heptyl. Group, octyl group, 2-ethylhexyl group, nonyl group, decyl group, 3,7-dimethyloctyl group, trifluoromethyl group, pentafluoroethyl group, perfluorobutyl group, perfluorohexyl group, perfluorooctyl group, etc. Can be mentioned.

There is no restriction | limiting in particular as said aryl group, According to the objective, it can select suitably, For example, you may have a substituent.
The aryl group is not particularly limited and may be appropriately selected depending on the intended purpose.For example, a phenyl group, a naphthyl group, an antonyl group, a fluorenyl group, a pyrenyl group, a phenanthrenyl group, a chrysenyl group, a fluoranthenyl group, And triphenylenyl group.
There is no restriction | limiting in particular as a substituent in the said aryl group, According to the objective, it can select suitably, For example, alkyl groups, such as a methyl group, t-butyl group, and a trifluoromethyl group, a fluorine atom, a chlorine atom, etc. And a substituted amino group such as a diphenylamino group and a t-butylamino group.

There is no restriction | limiting in particular as said alkoxy group, According to the objective, it can select suitably, For example, a linear alkoxy group, a branched alkoxy group, and a cyclic alkoxy group are mentioned.
There is no restriction | limiting in particular as carbon number of the said alkoxy group, According to the objective, it can select suitably, For example, C1-C10 is mentioned.
Examples of the alkoxy group include methoxy group, ethoxy group, propyloxy group, i-propyloxy group, butoxy group, i-butoxy group, t-butoxy group, pentyloxy group, hexyloxy group, cyclohexyloxy group, heptyl. Oxy, octyloxy, 2-ethylhexyloxy, nonyloxy, decyloxy, 3,7-dimethyloctyloxy, trifluoromethoxy, pentafluoroethoxy, perfluorobutoxy, perfluorohexyloxy, perfluoro A fluorooctyloxy group, a methoxymethyloxy group, a 2-methoxyethyloxy group and the like can be mentioned.

There is no restriction | limiting in particular as a ring which adjacent R < ₄ > -R < ₁₉ > couple | bonds and forms, According to the objective, it can select suitably, For example, a benzene ring, a cyclohexyl ring, a naphthyl ring etc. are mentioned.

As the iridium complex represented by the general formula (3), any one of the R ₅ , R ₆ and R ₉ preferably has a structure represented by the general formula (2), and the R ₅ , R ₆ or R ₉ is more preferably a structure represented by the general formula (2), and the R ₅ is particularly preferably a structure represented by the general formula (2). The preferred embodiment is advantageous in that it is excellent in solubility in a solvent, thermal stability, light emission efficiency, and carrier transportability, and the particularly preferred embodiment is advantageous in that the effect is remarkable. .

  Of the two or more iridium complexes represented by the general formula (1) that the iridium complex mixture has, at least two iridium complexes are bidentate represented by B in the general formula (1). The ligand is a bidentate ligand having the same structure.

  In the at least two iridium complexes, the bidentate ligand represented by A in the general formula (1) is a bidentate ligand having the same structure, so that synthesis and purification can be easily performed. It is preferable at the point which can do.

Examples of the combination of the at least two iridium complexes include the following combinations.

  In the iridium complex mixture, it is preferable that one iridium complex of the iridium complexes in which m is not 0 is 91% by mass or more and 99.99% by mass or less based on the total amount of all the iridium complexes. The iridium complex in which m is 1 is more preferably 91% by mass or more and 99.99% by mass or less based on the total amount of all the iridium complexes. The preferred embodiment is advantageous in that the organic electroluminescence device using the iridium complex mixture is excellent in durability and luminous efficiency, and the more preferred embodiment is advantageous in that the effect is remarkable. is there.

The iridium complex mixture is advantageous in that the two or more iridium complexes are a main product and a by-product in the synthesis of the iridium complex because they can be easily manufactured and purification such as column chromatography purification can be omitted. is there.
Here, the main product means a product of 51% by mass or more of the total product to be synthesized, and the by-product means a production of less than 49% by mass of the total product to be synthesized. Means a thing. In addition, 1 type may be sufficient as a by-product, and 2 or more types may be sufficient as it.

<Method for producing iridium complex mixture>
As a method for producing the iridium complex mixture, the iridium complex has two or more iridium complexes represented by the general formula (1), and the general formula of at least two iridium complexes of the two or more iridium complexes is used. There is no particular limitation as long as the iridium complex mixture in which the bidentate ligand represented by B in (1) is a bidentate ligand having the same structure can be produced, and it is appropriately selected according to the purpose. Examples thereof include a production method in which two or more iridium complexes having different structures are mixed, and a method in which the two or more iridium complexes are produced as a main product and a by-product in the synthesis of the iridium complex.

  The method for producing the two or more iridium complexes as a main product and a by-product in the synthesis of the iridium complex is not particularly limited and may be appropriately selected depending on the intended purpose. For example, common iridium Complex synthesis methods can be applied.

A method for producing the iridium complex mixture will be exemplified below.

-Manufacturing method of iridium complex mixture A-
--Method for producing compound 1a--
The method for producing the compound 1a includes, for example, a step of reacting 4-t-amylphenol with trifluoromethanesulfonic anhydride, a step of extracting the product with a solvent, and a step of purifying the product. Depending on the situation, other steps are included.
Specifically, trifluoromethanesulfonic anhydride is added dropwise to a pyridine solution of 4-t-amylphenol under ice cooling and allowed to react at room temperature. The reaction is then poured into water, it is poured into ethyl acetate / dilute hydrochloric acid, and the organic layer is washed with brine. Next, after drying over magnesium sulfate, it is concentrated under reduced pressure. Next, the concentrated residue is purified by silica gel column chromatography. By these steps, the compound 1a can be produced.

--Method for producing compound 1b--
The production method of the compound 1b includes, for example, a step of reacting the compound 1a with 2-tributylstannylpyridine, a step of extracting the product with a solvent, and a step of purifying the product, and if necessary, Including other processes.
Specifically, lithium chloride and ditertiary butylhydroxytoluene are added to the DMF solution of the compound 1a and 2-tributylstannylpyridine, and further dichlorobistriphenylphosphine palladium is added and reacted in a nitrogen atmosphere. Next, the reaction solution is poured into an aqueous potassium fluoride solution, ethyl acetate is added, and the mixture is filtered through Celite, and the organic layer of the filtrate is washed with brine. Next, after drying over magnesium sulfate, it is concentrated under reduced pressure. Next, the concentrated residue is purified by silica gel column chromatography. By these steps, the compound 1b can be produced.

--Method for producing compound 1c--
The method for producing the compound 1c includes, for example, a step of reacting iridium trichloride hydrate with phenylpyridine, and further includes other steps as necessary.
Specifically, phenylpyridine is added to water of iridium trichloride hydrate and an ethoxyethanol solution, and reacted. Next, the reaction solution is filtered, and the obtained filtrate is concentrated under reduced pressure. Next, water and diethyl ether are added to the concentrated residue, and the precipitated solid is collected by filtration. By these steps, the compound 1c can be produced.

--Method for producing compound 1d--
The method for producing the compound 1d includes, for example, a step of reacting the compound 1c with silver trifluoromethanesulfonate, and further includes other steps as necessary.
Specifically, a methanol and dichloromethane solution of the compound 1c and silver trifluoromethanesulfonate is stirred at room temperature, and the reaction solution is filtered. Next, the obtained filtrate is concentrated under reduced pressure. By these steps, the compound 1d can be produced.

--Method for producing iridium complex mixture A--
The method for producing the iridium complex mixture A includes, for example, a step of reacting the compound 1b and the compound 1d, and further includes other steps as necessary.
Specifically, the compound 1b and the methoxyethanol solution of the compound 1d are reacted in a nitrogen atmosphere. Next, the reaction solution is filtered to obtain crude crystals, which are recrystallized. By these steps, the iridium complex mixture A can be produced.

  The iridium complex mixture A obtained by the production method is, for example, a mixture of iridium complexes 1 to 3 having the iridium complex 1 as a main product.

(Organic electroluminescence device)
The organic electroluminescent element of the present invention has at least one organic layer between the anode and the cathode, and further has other layers as necessary.

<Organic layer>
There is no restriction | limiting in particular as said organic layer, According to the objective, it can select suitably, For example, a light emitting layer, an electron carrying layer, an electron injection layer, a positive hole transport layer, a positive hole injection layer etc. are mentioned.
At least one of the organic layers contains the iridium complex mixture. This is advantageous in that the organic layer can be easily formed by coating and the durability of the organic electroluminescent element is excellent.

  There is no restriction | limiting in particular as a structure of the said organic layer, Although it can select suitably according to the objective, It is low-voltage, luminous efficiency improvement, and durability that it is three or more layers in the said organic electroluminescent element. It is preferable in terms of improvement.

-Light emitting layer-
The material, shape, structure, size, and the like of the light emitting layer are not particularly limited and can be appropriately selected depending on the purpose. Examples of the shape include a film shape and a sheet shape. Further, examples of the planar shape include a quadrangle and a circle, and examples of the structure include a single-layer structure and a laminated structure. The size can be appropriately selected according to the application. .

  The light emitting layer is not particularly limited and may be appropriately selected depending on the intended purpose. However, the light emitting layer containing the iridium complex mixture can be easily formed by coating. In addition, even when compared with a highly pure iridium complex, the external quantum efficiency of the organic electroluminescence device does not decrease, and it is preferable in terms of excellent durability.

  The content of the iridium complex mixture is preferably 0.5% by mass to 30% by mass, more preferably 0.5% by mass to 20% by mass, and more preferably 3% by mass to the total mass of the compound constituting the light emitting layer. 10% by mass is particularly preferred. When the content is less than 0.5% by mass, the light emission efficiency may be reduced, and when it exceeds 30% by mass, the light emission efficiency may be decreased due to concentration quenching. When the content is in a particularly preferred range, it is advantageous in terms of improving luminous efficiency and durability.

  The light emitting layer may have a light emitting material other than the iridium complex mixture and a host compound.

--Luminescent material--
As the light emitting material, either a phosphorescent light emitting material or a fluorescent light emitting material can be used.

--- Phosphorescent material ---
There is no restriction | limiting in particular as said phosphorescence-emitting material, According to the objective, it can select suitably, For example, the complex etc. which contain a transition metal atom and a lanthanoid atom are mentioned.

  Examples of the transition metal atom include ruthenium, rhodium, palladium, tungsten, rhenium, osmium, iridium, platinum, and the like. Among these, rhenium, iridium, and platinum are preferable, and iridium and platinum are particularly preferable.

  Examples of the lanthanoid atom include lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Among these, neodymium, europium, and gadolinium are particularly preferable.

Examples of the ligand of the complex include G.I. Wilkinson et al., Comprehensive Coordination Chemistry, Pergamon Press, 1987, H.C. Listed by Yersin, “Photochemistry and Photophysics of Coordination Compounds”, published by Springer-Verlag, 1987, Akio Yamamoto, “Organic Metal Chemistry-Fundamentals and Applications,” published by Soukabo, 1982, etc. It is done.
Specific ligands include halogen ligands (preferably chlorine ligands), aromatic carbocyclic ligands (eg, cyclopentadienyl anion, benzene anion, naphthyl anion, etc.), nitrogen-containing hetero Ring ligands (eg, phenylpyridine, benzoquinoline, quinolinol, bipyridyl, or phenanthroline), diketone ligands (eg, acetylacetone, etc.), carboxylic acid ligands (eg, acetic acid ligands, etc.), alcoholates Examples include ligands (eg, phenolate ligands), carbon monoxide ligands, isonitrile ligands, cyano ligands, and the like. Among these, a nitrogen-containing heterocyclic ligand is particularly preferable.

The complex may have one transition metal atom in the compound, or may be a so-called binuclear complex having two or more. Different metal atoms may be contained at the same time. Among these, examples of the phosphorescent light emitting material include the following, but are not limited thereto.

  The content of the phosphorescent material is preferably 0.5% by mass to 30% by mass, more preferably 0.5% by mass to 20% by mass, and more preferably 3% by mass to the total mass of the compound constituting the light emitting layer. 10% by mass is particularly preferred. When the content is less than 0.5% by mass, the light emission efficiency may be reduced, and when it exceeds 30% by mass, the light emission efficiency may be reduced due to association of the phosphorescent material itself.

--- Fluorescent material ---
The fluorescent light emitting material is not particularly limited and may be appropriately selected depending on the purpose. For example, benzoxazole, benzimidazole, benzothiazole, styrylbenzene, polyphenyl, diphenylbutadiene, tetraphenylbutadiene, naphthalimide, coumarin , Pyran, perinone, oxadiazole, aldazine, pyralidine, cyclopentadiene, bisstyrylanthracene, quinacridone, pyrrolopyridine, thiadiazolopyridine, cyclopentadiene, styrylamine, aromatic dimethylidin compound, condensed polycyclic aromatic compound (anthracene, Phenanthroline, pyrene, perylene, rubrene, pentacene, etc.), 8-quinolinol metal complexes, various metal complexes represented by pyromethene complexes and rare earth complexes, polythiophene, Rifeniren, polymer compounds such as polyphenylene vinylene, organic silane or a derivative thereof, and the like.

Among these, specific examples of the fluorescent light emitting material include the following, but are not limited thereto.

  The content of the fluorescent light-emitting material is preferably 0.1% by mass to 30% by mass with respect to the total compound mass constituting the light emitting layer, and is 0.2% by mass to 15% by mass from the viewpoint of durability and light emission efficiency. Is more preferable, and 0.5% by mass to 12% by mass is particularly preferable.

--Host compound--
The host compound is not particularly limited and may be appropriately selected depending on the intended purpose.For example, pyrrole, indole, carbazole, azaindole, azacarbazole, polyarylalkane, pyrazoline, pyrazolone, phenylenediamine, arylamine, Amino-substituted chalcone, styrylanthracene, fluorenone, hydrazone, stilbene, silazane, pyridine, pyrimidine, triazine, triazole, oxal, oxadiazole, fluorenone, anthraquinodimethane, anthrone, diphenylquinone, thiopyran dioxide, carbodiimide, fluoreni Heterocyclic tetracarboxylic anhydrides such as redenemethane, distyrylpyrazine, fluorine-substituted aromatic compounds, naphthaleneperylene, phthalocyanine, aromatic tertiary amination , Styrylamine compounds, aromatic dimethylidin compounds, porphyrin compounds, polysilane compounds, poly (N-vinylcarbazole), aniline copolymers, thiophene oligomers, conductive polymer oligomers such as polythiophene, organic silanes, carbon Examples thereof include films, derivatives thereof, metal complexes of 8-quinolinol derivatives, metal phthalocyanines, benzoxazoles, and various metal complexes represented by metal complexes having benzothiazole as a ligand.
Among these, indole derivatives, carbazole derivatives, azaindole derivatives, azacarbazole derivatives, aromatic tertiary amine compounds, and thiophene derivatives are preferable, and indole skeleton, carbazole skeleton, azaindole skeleton, azacarbazole skeleton, or aromatic in the molecule Those having an aromatic group tertiary amine skeleton are more preferred, and compounds having a carbazole skeleton are particularly preferred.
In the present invention, a host material in which part or all of the hydrogen in the host compound is substituted with deuterium can be used (Japanese Patent Laid-Open No. 2009-277790, Japanese Translation of PCT International Publication No. 2004-515506).

Examples of the host compound include metal complexes, azole derivatives (benzimidazole derivatives, imidazopyridine derivatives, etc.), azine derivatives (pyridine derivatives, pyrimidine derivatives, triazine derivatives, etc.), and the like. Among these, in the present invention, a metal complex is preferable from the viewpoint of durability. The metal complex is more preferably a metal complex having a ligand having at least one nitrogen atom, oxygen atom or sulfur atom coordinated to a metal.
The metal ion in the metal complex is not particularly limited and may be appropriately selected depending on the intended purpose, but beryllium ion, magnesium ion, aluminum ion, gallium ion, zinc ion, indium ion, tin ion, platinum ion. Palladium ions are preferable, beryllium ions, aluminum ions, gallium ions, zinc ions, platinum ions, and palladium ions are more preferable, and aluminum ions, zinc ions, and palladium ions are particularly preferable.

  There are various known ligands contained in the metal complex. For example, “Photochemistry and Photophysics of Coordination Compounds”, Springer-Verlag, H.C. Examples include the ligands described in Yersin, published in 1987, “Organometallic Chemistry: Fundamentals and Applications”, Sakai Hanafusa, Yamamoto Akio, published in 1982, and the like.

  Examples of the ligand include an azine ligand (for example, pyridine ligand, bipyridyl ligand, terpyridine ligand, etc.), a hydroxyphenylazole ligand (for example, hydroxyphenylbenzimidazole coordination). , A hydroxyphenylbenzoxazole ligand, a hydroxyphenylimidazole ligand, a hydroxyphenylimidazopyridine ligand, etc.), an alkoxy ligand (preferably having 1 to 30 carbon atoms, more preferably 1 to 1 carbon atoms). 20, particularly preferably 1 to 10 carbon atoms, such as methoxy, ethoxy, butoxy, 2-ethylhexyloxy and the like, aryloxy ligands (preferably 6 to 30 carbon atoms, more preferably carbon numbers) 6 to 20, particularly preferably 6 to 12 carbon atoms, for example phenylo , 1-naphthyloxy, 2-naphthyloxy, 2,4,6-trimethylphenyloxy, 4-biphenyloxy, etc.), heteroaryloxy ligands (preferably having 1 to 30 carbon atoms, more preferably C1-C20, Most preferably, it is C1-C12, for example, pyridyloxy, pyrazyloxy, pyrimidyloxy, quinolyloxy etc. are mentioned, Alkylthio ligand (preferably C1-C30, More preferably carbon 1 to 20, particularly preferably 1 to 12 carbon atoms, such as methylthio and ethylthio, and arylthio ligands (preferably 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably Has 6 to 12 carbon atoms, such as phenylthio), heteroarylthio A ligand (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms such as pyridylthio, 2-benzimidazolylthio, 2-benzoxazolylthio, and 2- Benzthiazolylthio and the like), a siloxy ligand (preferably having 1 to 30 carbon atoms, more preferably 3 to 25 carbon atoms, particularly preferably 6 to 20 carbon atoms, for example, a triphenylsiloxy group, A triethoxysiloxy group, a triisopropylsiloxy group, etc.), an aromatic hydrocarbon anion ligand (preferably having 6 to 30 carbon atoms, more preferably 6 to 25 carbon atoms, and particularly preferably 6 to 6 carbon atoms). 20 and examples thereof include a phenyl anion, a naphthyl anion, and an anthranyl anion), an aromatic heterocyclic anion Ligand (preferably having 1 to 30 carbon atoms, more preferably 2 to 25 carbon atoms, particularly preferably 2 to 20 carbon atoms, such as pyrrole anion, pyrazole anion, pyrazole anion, triazole anion, oxazole anion, benzoxazole Anion, thiazole anion, benzothiazole anion, thiophene anion, and benzothiophene anion), indolenine anion ligand, etc., preferably nitrogen-containing heterocyclic ligand, aryloxy ligand, hetero An aryloxy group or a siloxy ligand, particularly preferably a nitrogen-containing heterocyclic ligand, an aryloxy ligand, a siloxy ligand, an aromatic hydrocarbon anion ligand, or an aromatic heterocyclic anion arrangement It is a rank.

  Examples of the metal complex include Japanese Patent Application Laid-Open No. 2002-235076, Japanese Patent Application Laid-Open No. 2004-214179, Japanese Patent Application Laid-Open No. 2004-221106, Japanese Patent Application Laid-Open No. 2004-221106, Japanese Patent Application Laid-Open No. 2004-221068, Japanese Patent Application Laid-Open No. Examples thereof include compounds described in 2004-327313.

Specific examples of the host compound include, but are not limited to, the following compounds.

  The content of the host compound is preferably 10% by mass to 90% by mass, more preferably 20% by mass to 80% by mass, and more preferably 30% by mass to 70% by mass with respect to the total mass of the compound constituting the light emitting layer. Particularly preferred.

  There is no restriction | limiting in particular as thickness of the said light emitting layer, Although it can select suitably according to the objective, 2 nm-500 nm are preferable, 3 nm-200 nm are more preferable, and 5 nm-100 nm are especially preferable.

-Electron injection layer, electron transport layer-
The electron injection layer and the electron transport layer are layers having a function of receiving electrons from the anode side and transporting them to the anode side.

  The material for the electron injection layer and the electron transport layer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include triazole derivatives, oxazole derivatives, oxadiazole derivatives, fluorenone derivatives, anthraquinodimethane. Derivatives, anthrone derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimide derivatives, fluorenylidenemethane derivatives, distyrylpyrazine derivatives, heterocyclic tetracarboxylic anhydrides such as naphthaleneperylene, phthalocyanine derivatives, 8-quinolinol derivatives Examples include complexes, metal phthalocyanines, metal complexes having benzoxazole or benzothiazole as a ligand.

The electron injection layer and the electron transport layer can contain a hole-accepting dopant.
The hole-accepting dopant may be an inorganic compound or an organic compound as long as it has a hole-accepting property and a property of reducing an organic compound.
There is no restriction | limiting in particular as said inorganic compound, According to the objective, it can select suitably, For example, an alkali metal, alkaline-earth metal, its metal oxide, etc. are mentioned.

  The structures of the electron injection layer and the electron transport layer are not particularly limited and can be appropriately selected according to the purpose. For example, a single layer structure or a plurality of layers having the same composition or different compositions can be used. The multilayer structure which consists of may be sufficient.

  There is no restriction | limiting in particular as thickness of the said electron injection layer and the said electron carrying layer, Although it can select suitably according to the objective, 1 nm-5 micrometers are preferable, 5 nm-1 micrometer are more preferable, 10 nm-500 nm are especially preferable. .

-Hole injection layer, hole transport layer-
The hole injection layer and the hole transport layer are layers having a function of receiving holes from the anode or the anode side and transporting them to the cathode side.

The material for the hole injection layer and the hole transport layer is not particularly limited and may be appropriately selected depending on the purpose, and may be a low molecular compound or a high molecular compound, It may be an inorganic compound.
The material for the hole injection layer and the hole transport layer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include pyrrole derivatives, carbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives. , Imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amines Compounds, styrylamine compounds, aromatic dimethylidin compounds, phthalocyanine compounds, porphyrin compounds, thiophene derivatives, organic silane derivatives, carbon, molybdenum trioxide, etc. . These may be used individually by 1 type and may use 2 or more types together.

  The hole injection layer is not particularly limited and may be appropriately selected depending on the intended purpose. However, the hole injection layer containing the iridium complex mixture is easily applied by coating the hole injection layer. It is preferable in that it can be formed in a wide range and has excellent durability.

  The content of the iridium complex mixture in the hole injection layer is preferably 5% by mass to 50% by mass and more preferably 10% by mass to 40% by mass with respect to the total compound mass constituting the hole injection layer. 10 mass%-30 mass% is especially preferable. When the content is less than 5% by mass, the durability may not be improved. When the content exceeds 50% by mass, the iridium complex may be eluted when the upper layer is applied. If the content is in a particularly preferred range, it is advantageous in terms of excellent durability.

The hole injection layer and the hole transport layer may contain an electron accepting dopant.
The electron-accepting dopant may be an inorganic compound or an organic compound as long as it is electron-accepting and has the property of oxidizing an organic compound.
There is no restriction | limiting in particular as said inorganic compound, According to the objective, it can select suitably, For example, a metal halide, a metal oxide, etc. are mentioned.
Examples of the metal halide include ferric chloride, aluminum chloride, gallium chloride, indium chloride, and antimony pentachloride.
Examples of the metal oxide include vanadium pentoxide and molybdenum trioxide.
The organic compound is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a compound having a nitro group, a halogen, a cyano group, a trifluoromethyl group or the like as a substituent, a quinone compound, an acid anhydride Compounds, fullerenes and the like.
These electron-accepting dopants may be used alone or in combination of two or more.

  The amount of the electron-accepting dopant used varies depending on the type of material, but is preferably 0.01% by mass to 50% by mass, and 0.05% by mass to 50% by mass with respect to the hole transport layer material or the hole injection material. % By mass is more preferable, and 0.1% by mass to 30% by mass is particularly preferable.

  The hole injection layer and the hole transport layer are not particularly limited and may be appropriately selected depending on the intended purpose. For example, a single layer structure may be used, or a plurality of layers having the same composition or different compositions. The multilayer structure which consists of may be sufficient.

  There is no restriction | limiting in particular as average thickness of the said positive hole injection layer and the said positive hole transport layer, Although it can select suitably according to the objective, 1 nm-500 nm are preferable, 5 nm-200 nm are more preferable, 10 nm-100 nm Is particularly preferred.

<Anode>
There is no restriction | limiting in particular as a material which comprises the said anode, According to the objective, it can select suitably, For example, an antimony, a fluorine oxide doped tin oxide (ATO, FTO), a tin oxide, a zinc oxide, an indium oxide Conductive metal oxides such as indium tin oxide (ITO) and zinc indium oxide (IZO); metals such as gold, silver, chromium and nickel; mixtures or laminates of these metals and conductive metal oxides; Inorganic conductive substances such as copper chloride and copper sulfide; organic conductive materials such as polyaniline, polythiophene, and polypyrrole; and laminates of these with ITO. Among these, a conductive metal oxide is preferable, and ITO is particularly preferable in terms of productivity, high conductivity, transparency, and the like.

  There is no restriction | limiting in particular as thickness of the said anode, Although it can select suitably according to the objective, 10 nm-50 micrometers are preferable, and 50 nm-20 micrometers are more preferable.

<Cathode>
There is no restriction | limiting in particular as a material which comprises the said cathode, According to the objective, it can select suitably, For example, an alkali metal (for example, Li, Na, K, Cs etc.), an alkaline earth metal (for example, Mg, Ca) Etc.), gold, silver, lead, aluminum, sodium-potassium alloy, lithium-aluminum alloy, magnesium-silver alloy, rare earth metals such as indium and ytterbium, and the like. These may be used alone, but two or more can be suitably used in combination from the viewpoint of achieving both stability and electron injection.
Among these, alkali metals and alkaline earth metals are preferable from the viewpoint of electron injecting properties, and materials mainly composed of aluminum are particularly preferable from the viewpoint of excellent storage stability.
The material mainly composed of aluminum is aluminum alone, an alloy of aluminum and 0.01% by mass to 10% by mass of alkali metal or alkaline earth metal, or a mixture thereof (for example, lithium-aluminum alloy, magnesium-aluminum). Alloy).

  There is no restriction | limiting in particular as thickness of the said cathode, Although it can select suitably according to the objective, 10 nm-5 micrometers are preferable, and 50 nm-1 micrometer are more preferable.

  In view of the nature of the organic electroluminescence device, at least one of the anode and the cathode is preferably transparent. Usually, the anode may have a function as an electrode for supplying holes to the organic compound layer, and the cathode may have a function as an electrode for injecting electrons into the organic compound layer.

  There is no restriction | limiting in particular about the formation method of the said anode and the said cathode, According to the objective, it can select suitably. For example, a wet method such as a printing method or a coating method; a physical method such as a vacuum deposition method, a sputtering method, or an ion plating method; a chemical method such as a CVD method or a plasma CVD method may be used. Among these, it can be formed on the substrate in accordance with an appropriately selected method in consideration of suitability with the materials constituting the anode and the cathode. For example, when ITO is selected as the material of the anode, it can be formed by direct current or high frequency sputtering, vacuum deposition, ion plating, or the like. When a metal or the like is selected as the cathode material, one or more of them can be formed simultaneously or sequentially by sputtering or the like.

  In addition, when patterning is performed when forming the anode and the cathode, it may be performed by chemical etching such as photolithography, or may be performed by physical etching using a laser or the like, and a mask is overlapped. It may be performed by vacuum deposition, sputtering, or the like, or may be performed by a lift-off method or a printing method.

<Other layers>
There is no restriction | limiting in particular as said other layer, According to the objective, it can select suitably, For example, a board | substrate etc. are mentioned.

-Board-
The organic electroluminescent element is preferably provided on a substrate, and may be provided in such a manner that the electrode and the substrate are in direct contact with each other, or may be provided with an intermediate layer interposed therebetween.
The material for the substrate is not particularly limited and may be appropriately selected depending on the intended purpose. For example, inorganic materials such as yttria-stabilized zirconia (YSZ) and glass (such as alkali-free glass and soda lime glass); polyethylene terephthalate And polyesters such as polybutylene phthalate and polyethylene naphthalate; organic materials such as polystyrene, polycarbonate, polyethersulfone, polyarylate, polyimide, polycycloolefin, norbornene resin, and poly (chlorotrifluoroethylene).

  There is no restriction | limiting in particular about the shape of the said board | substrate, a structure, a magnitude | size, It can select suitably according to the use, purpose, etc. of a light emitting element. In general, the shape of the substrate is preferably a plate shape. The structure of the substrate may be a single layer structure, a laminated structure, may be formed of a single member, or may be formed of two or more members. The substrate may be transparent or opaque, and if transparent, it may be colorless and transparent or colored and transparent.

The substrate may be provided with a moisture permeation preventing layer (gas barrier layer) on the front surface or the back surface.
Examples of the material of the moisture permeation preventive layer (gas barrier layer) include inorganic substances such as silicon nitride and silicon oxide.
The moisture permeation preventing layer (gas barrier layer) can be formed by, for example, a high frequency sputtering method.

-Protective layer-
The organic electroluminescent element may be protected by a protective layer.
The material contained in the protective layer is not particularly limited as long as it has a function of suppressing the entry of elements that promote element deterioration such as moisture and oxygen into the element. For example, metals such as In, Sn, Pb, Au, Cu, Ag, Al, Ti, Ni; MgO, SiO, SiO ₂ , Al ₂ O ₃ , GeO, NiO, CaO, BaO, Fe ₂ Metal oxides such as O ₃ , Y ₂ O ₃ and TiO ₂ ; Metal nitrides such as SiNx and SiNxOy; Metal fluorides such as MgF ₂ , LiF, AlF ₃ and CaF ₂ ; Polyethylene, polypropylene, polymethyl methacrylate, polyimide , Polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, chlorotrifluoroethylene A copolymer of dichlorodifluoroethylene, a copolymer obtained by copolymerizing a monomer mixture containing tetrafluoroethylene and at least one comonomer, a fluorinated copolymer having a cyclic structure in the copolymer main chain, water absorption Examples thereof include a water-absorbing substance having a rate of 1% or more, a moisture-proof substance having a water absorption rate of 0.1% or less, and the like.

  There is no restriction | limiting in particular as a formation method of the said protective layer, According to the objective, it can select suitably, For example, a vacuum evaporation method, sputtering method, reactive sputtering method, MBE (molecular beam epitaxy) method, cluster ion beam method , Ion plating method, plasma polymerization method (high frequency excitation ion plating method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, coating method, printing method, transfer method and the like.

-Sealing container-
The organic electroluminescent element may be entirely sealed using a sealing container. Furthermore, a water absorbent or an inert liquid may be sealed in a space between the sealing container and the organic electroluminescent element.
The moisture absorbent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, barium oxide, sodium oxide, potassium oxide, calcium oxide, sodium sulfate, calcium sulfate, magnesium sulfate, phosphorus pentoxide, chloride Calcium, magnesium chloride, copper chloride, cesium fluoride, niobium fluoride, calcium bromide, vanadium bromide, molecular sieve, zeolite, magnesium oxide, and the like can be given.
The inert liquid is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include paraffins, liquid paraffins; fluorinated solvents such as perfluoroalkane, perfluoroamine, and perfluoroether; Examples include solvents and silicone oils.

-Resin sealing layer-
The organic electroluminescent element is preferably suppressed by sealing the element performance deterioration due to oxygen or moisture from the atmosphere with a resin sealing layer.
The resin material for the resin sealing layer is not particularly limited and can be appropriately selected depending on the purpose. For example, acrylic resin, epoxy resin, fluorine resin, silicone resin, rubber resin, ester resin, Etc. Among these, an epoxy resin is particularly preferable from the viewpoint of moisture prevention function. Among the epoxy resins, a thermosetting epoxy resin or a photocurable epoxy resin is preferable.

  There is no restriction | limiting in particular as a preparation method of the said resin sealing layer, According to the objective, it can select suitably, For example, the method of apply | coating a resin solution, the method of crimping | bonding or thermocompressing a resin sheet, vapor deposition, sputtering, etc. And a dry polymerization method.

-Sealing adhesive-
The organic electroluminescent element may prevent moisture and oxygen from entering from the end portion with a sealing adhesive.
As the material of the sealing adhesive, the same material as that used for the resin sealing layer can be used. Among these, an epoxy adhesive is preferable from the viewpoint of preventing moisture from entering, and a photocurable adhesive or a thermosetting adhesive is particularly preferable.
It is also preferable to add a filler to the sealing adhesive. As the filler, for example _SiO 2, SiO (silicon oxide), SiON (silicon oxynitride), an inorganic material such as SiN (silicon nitride) are preferred. Addition of the filler increases the viscosity of the sealing adhesive, improves processing suitability, and improves moisture resistance.
The sealing adhesive may contain a desiccant. Examples of the desiccant include barium oxide, calcium oxide, and strontium oxide. The addition amount of the desiccant is preferably 0.01% by mass to 20% by mass and more preferably 0.05% by mass to 15% by mass with respect to the sealing adhesive. When the addition amount is less than 0.01% by mass, the effect of adding the desiccant is diminished, and when it exceeds 20% by mass, it is difficult to uniformly disperse the desiccant in the sealing adhesive. Sometimes.
In the present invention, the sealing adhesive containing the desiccant can be applied by an arbitrary amount using a dispenser or the like, and the substrates can be sealed by overlapping and curing after application.

<Drive>
The organic electroluminescence device obtains light emission by applying a direct current (which may include an alternating current component as necessary) voltage (usually 2 to 15 volts) or a direct current between the anode and the cathode. Can do.

The light extraction efficiency of the organic electroluminescence device is not particularly limited, and can be improved by various known devices. For example, by processing the substrate surface shape (for example, forming a fine concavo-convex pattern), controlling the refractive index of the substrate, ITO layer, organic layer, controlling the thickness of the substrate, ITO layer, organic layer, etc. It is possible to improve the external quantum efficiency.
The light extraction method from the organic electroluminescence device of the present invention may be a top emission method or a bottom emission method.

The organic electroluminescent element of the present invention may have a resonator structure. For example, a multilayer mirror made of a plurality of laminated films having different refractive indexes, a transparent or translucent electrode, a light emitting layer, and a metal electrode are superimposed on a transparent substrate. The light generated in the light emitting layer resonates repeatedly with the multilayer mirror and the metal electrode as a reflection plate.
In another preferred embodiment, a transparent or translucent electrode and a metal electrode each function as a reflecting plate on a transparent substrate, and light generated in the light emitting layer repeats reflection and resonates between them.
In order to form a resonant structure, the optical path length determined from the effective refractive index of the two reflectors and the refractive index and thickness of each layer between the reflectors is adjusted to an optimum value to obtain the desired resonant wavelength. Is done. The calculation formula in the case of the first aspect is described in JP-A-9-180883. The calculation formula in the case of the second aspect is described in Japanese Patent Application Laid-Open No. 2004-127795.

<Application>
The use of the organic electroluminescent element is not particularly limited and may be appropriately selected depending on the intended purpose. The backlight of the liquid crystal display device, the color filter, the light source of the copying machine, the indoor / outdoor lighting, the signboard, and the display board , Can be suitably used for signs and the like.

(Method for manufacturing organic electroluminescent device)
The manufacturing method of the organic electroluminescent element of this invention includes the application | coating process which forms the organic layer containing the said iridium complex mixture by application | coating, and also includes another process as needed.

<Application process>
The coating step is a step of forming an organic layer containing the iridium complex mixture by coating using a coating solution.
The application method is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include spray deposition, spin coating, curtain coating, roll coating, a printing method, and an inkjet method. Among these, spray deposition, spin coating, and an inkjet method are preferable in that a layer having a uniform thickness can be formed.

  The coating solution contains at least the iridium complex mixture and a solvent, and further contains other components as necessary.

  The solvent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, ethyl acetate, methyl ethyl ketone (MEK), cyclohexanone, tetrahydrofuran, toluene, xylene, 2-butanone, dibutyl ether, propylene glycol diacetate Etc.

  There is no restriction | limiting in particular as content of the said iridium complex mixture in the said coating liquid, Although it can select suitably according to the objective, 0.025 mass%-2 mass% are preferable, 0.05 mass%-1 % By mass is more preferable, and 0.1% by mass to 0.5% by mass is particularly preferable. When the content is less than 0.025% by mass, sufficient brightness and durability may not be obtained in the device. When the content exceeds 2% by mass, the smoothness of the coating film may be lowered, or the device In this case, the light emission efficiency may decrease due to concentration quenching. When the content is in the particularly preferred range, it is advantageous in terms of improving the smoothness of the coating film, improving the light emission efficiency of the device, and improving the durability.

<Other processes>
There is no restriction | limiting in particular as said other process, According to the objective, it can select suitably, For example, a cathode formation process, an anode formation process, etc. are mentioned.

  Examples of the present invention will be described below, but the present invention is not limited to the following examples.

(Example 1)
<Synthesis of Iridium Complex Mixture 1>
The iridium complex mixture 1 was synthesized according to the following synthesis method.

-Synthesis of Compound 1a-
To a pyridine solution (105 mL) of 4-t-amylphenol (manufactured by Tokyo Chemical Industry) (25 g), trifluoromethanesulfonic anhydride (ALDRICH) (30.7 mL) was added dropwise under ice-cooling, and 3 hours at room temperature. Reacted. The reaction solution was poured into water, which was poured into ethyl acetate / dilute hydrochloric acid, and the organic layer was washed with brine, dried over magnesium sulfate, and concentrated under reduced pressure. The concentrated residue was purified by silica gel column chromatography (developing solvent: hexane) to obtain Compound 1a (43.5 g).

-Synthesis of Compound 1b-
Lithium chloride (13.8 g) and ditertiary butylhydroxytoluene (0.4 g) were added to a DMF solution (260 mL) of the compound 1a (32.2 g) and 2-tributylstannylpyridine (manufactured by Wako Pure Chemical Industries, Ltd.) (40 g). And dichlorobistriphenylphosphine palladium (3.8 g) was added, and the mixture was reacted at 100 ° C. for 18 hours under a nitrogen atmosphere. The reaction mixture was poured into a 10% aqueous potassium fluoride solution, ethyl acetate was added, and the mixture was filtered through Celite. The organic layer of the filtrate was washed with brine, dried over magnesium sulfate, and concentrated under reduced pressure. The concentrated residue was purified by silica gel column chromatography (developing solvent: ethyl acetate / hexane = 1/5 (volume ratio)) to obtain Compound 1b (16.3 g).

-Synthesis of Compound 1c-
Phenylpyridine (26 g) was added to a solution of iridium trichloride hydrate (20 g) in ethoxyethanol (1,250 mL) and water (420 mL), and reacted at 120 ° C. for 24 hours. The reaction solution was filtered, and the obtained filtrate was concentrated under reduced pressure. Water and diethyl ether were added to the concentrated residue, and the precipitated solid was collected by filtration to obtain 32 g of Compound 1c.

-Synthesis of Compound 1d-
A solution of the compound 1c (25 g) and silver trifluoromethanesulfonate (12.2 g) in methanol (83 mL) and dichloromethane (1.7 L) was stirred at room temperature for 1 hour, and the reaction solution was filtered. The obtained filtrate was concentrated under reduced pressure to obtain 23.4 g of Compound 1d.

-Synthesis of iridium complex mixture 1-
A methoxyethanol solution (800 mL) of the compound 1b (16.3 g) and the compound 1d (23.4 g) was reacted at 95 ° C. for 18 hours in a nitrogen atmosphere. By filtering the reaction solution, crude crystals 1 were obtained. The crude crystal 1 was dissolved in toluene to obtain a toluene solution, and then isopropyl alcohol was added dropwise to the toluene solution until crystals were precipitated, followed by filtration to obtain an iridium complex mixture 1 (appearance of a pale yellow solid) 14 g) was obtained. The yield of the obtained iridium complex mixture 1 with respect to the compound 1d was 53.6%.
The obtained iridium complex mixture 1 was analyzed by analysis described later.

(Example 2)
<Synthesis of Iridium Complex Mixture 2>
The iridium complex mixture 1 obtained in Example 1 was recrystallized with dichloromethane / methanol = 1/1 (volume ratio) to obtain an iridium complex mixture 2.

(Example 3 and Example 4)
<Synthesis of Iridium Complex Mixture 3 and Iridium Complex Mixture 4>
The crude crystal 1 obtained in Example 1 was purified by sublimation, and the iridium complex mixture 3 and the iridium complex mixture 4 were taken out from the sublimation tube. In addition, what was scraped off from the position near the coarse body boat of the sublimation tube is the iridium complex mixture 3, and what was scraped off from a far position is the iridium complex mixture 4.

(Comparative Example 1 and Comparative Example 2)
<Synthesis of Iridium Complex 1 and Iridium Complex 2>
By using the toluene solution of the iridium complex mixture 1 obtained in Example 1 and performing silica gel chromatography purification (developing solvent: ethyl acetate / hexane = 1/1 (volume ratio)) three times, the iridium complex mixture 1 The iridium complex 1 and the iridium complex 2 were separated to obtain the iridium complex 1 and the iridium complex 2, respectively.

(Comparative Example 3)
<Synthesis of Iridium Complex 3>
Tris (2-phenylpyridine) iridium (III) (manufactured by ALDRICH, sublimation purification grade product) was purified by sublimation to obtain iridium complex 3.

<Analysis of Iridium Complex and Iridium Complex Mixture>
The following analysis was performed about the iridium complex mixture obtained in Examples 1-4 and the iridium complex obtained in Comparative Examples 1-3.

<< Analysis of composition ratio >>
About the iridium complex mixture and the iridium complex, the composition ratio was analyzed using the HPLC apparatus (The Shimadzu Corporation make, a high performance liquid chromatograph: Prominence gradient system).
The conditions of the HPLC apparatus are as follows.
Column: Tosoh TSK-Gel ODS-100V3 μm
Developing solution A: H ₂ O
Developing solution B: acetonitrile / methanol = 9/1 (volume ratio) (buffering agent: CH ₃ CO ₂ NH ₄ )
Gradient program:
0 to 20 minutes A: B = 30: 70 (volume ratio)
20 to 30 minutes A: B = 0: 100 (volume ratio)
The obtained results are shown in Table 1.

% In the table indicates the absorption area ratio at a detection wavelength of 254 nm. In addition, this absorption area ratio and the mass ratio of the iridium complex in an iridium complex mixture almost correspond.

The structures of the iridium complexes 1 to 3 are shown below.

(Example 5)
<Synthesis of Iridium Complex Mixture 5>
In Example 1, except that 4-t-amylphenol was replaced with 4-t-butylphenol, an iridium complex mixture 5 was obtained by the same synthesis method as in Example 1. The yield of the obtained iridium complex mixture 5 was 67%.
The obtained iridium complex mixture 5 was analyzed by analysis described later.

(Comparative Example 4 and Comparative Example 5)
<Synthesis of Iridium Complex 4 and Iridium Complex 5>
By using the toluene solution of the iridium complex mixture 5 obtained in Example 5 and performing silica gel chromatography purification (developing solvent: ethyl acetate / hexane = 1/1 (volume ratio)) three times, from the iridium complex mixture 5 The iridium complex 4 and the iridium complex 5 were separated to obtain the iridium complex 4 and the iridium complex 5, respectively.

<Analysis of Iridium Complex and Iridium Complex Mixture>
The following analysis was performed about the iridium complex mixture obtained in Example 5, and the iridium complex obtained in Comparative Examples 3-5.

<< Analysis of composition ratio >>
About the iridium complex mixture and the iridium complex, the composition ratio was analyzed using the HPLC apparatus (The Shimadzu Corporation make, a high performance liquid chromatograph: Prominence gradient system).
The conditions of the HPLC apparatus are as follows.
Column: Tosoh TSK-Gel ODS-100V3 μm
Developing solution A: THF / H ₂ O = 1/9 (volume ratio) (buffering agents: acetic acid, triethylamine)
Developing solution B: THF / H ₂ O = 9/1 (volume ratio) (buffering agents: acetic acid, triethylamine)
Gradient program:
0 to 20 minutes A: B = 50: 50 (volume ratio)
20 to 30 minutes A: B = 0: 100 (volume ratio)
The obtained results are shown in Table 2.

% In the table indicates the absorption area ratio at a detection wavelength of 254 nm. In addition, this absorption area ratio and the mass ratio of the iridium complex in an iridium complex mixture almost correspond.

The structures of the iridium complexes 4 and 5 are shown below.

<Evaluation>
<< Solubility Measurement >>
The solubility measurement was performed about the iridium complex mixture and iridium complex which were obtained in the said Examples 1-5 and Comparative Examples 1-5.

−Creation of calibration curve−
The iridium complex mixture and each powder of the iridium complex are weighed into a vial under a yellow lamp, and after adding a predetermined amount of a solvent (xylene or ethyl acetate), a tabletop ultrasonic cleaner B1510J-MTH manufactured by BRANSON is used. Ultrasound was applied for 1 hour. The solution filtered through a 0.2 μm filter was placed in a quartz cell, and the absorbance was measured with an ultraviolet-visible spectrophotometer (Shimadzu Corporation UV-2400). Three types of solutions with different concentrations were prepared, and a calibration curve was prepared by measuring the absorbance.

-Calculation of solubility-
A saturated solution was prepared at a concentration higher than the concentration at which the calibration curve was created, and the solubility was calculated from the absorbance and the calibration curve. The obtained results are shown in Table 3.

From Table 3, it can be seen that the iridium complex mixture of the present invention has high solubility compared to only one type of iridium complex.

(Example 6)
Using an iridium complex mixture as a light-emitting material, an organic electroluminescent device was produced by vacuum deposition.

<Preparation of organic electroluminescent element 1>
On a glass substrate having a thickness of 0.7 mm and a square of 2.5 cm, ITO (Indium Tin Oxide) was sputtered to a thickness of 150 nm as an anode. Next, this ITO-attached glass substrate was put into a cleaning container, subjected to ultrasonic cleaning in 2-propanol, and then subjected to UV-ozone treatment for 30 minutes. Each layer was laminated | stacked on this glass substrate with ITO.

  In addition, the vapor deposition rate in the following examples and comparative examples is 0.1 nm / second unless otherwise specified. The deposition rate was measured using a quartz resonator. The thickness of each layer below was measured using a quartz resonator.

First, on the anode (ITO), 4,4 ′, 4 ″ -tris (N, N- (2-naphthyl) -phenylamino) triphenylamine (2- TNATA) was formed by vacuum deposition so that the thickness was 40 nm.

Next, an NPD (N, N′-dinaphthyl-N, N′-diphenyl- [1,1′-biphenyl] -4,4 represented by the following structural formula as a hole transport layer is formed on the hole injection layer. '-Diamine) was formed by vacuum deposition so that the thickness was 10 nm.

Next, the host compound 1 represented by the following structural formula, which is a host compound, and the iridium complex mixture 1 are co-deposited on the hole transport layer so that the mass ratio in the light emitting layer is 95: 5. Formed a light emitting layer having a thickness of 30 nm.

Next, BAlq (Bis- (2-methyl-8-quinolinolato) -4- (phenyl-phenolate) -aluminum (III)) represented by the following structural formula as an electron injection layer is formed on the light emitting layer with a thickness of 40 nm. It formed by the vacuum evaporation method so that it might become.

  Next, lithium fluoride (LiF) was formed on the electron injection layer by a vacuum deposition method so as to have a thickness of 1 nm.

  Next, a patterned mask (a mask having a light emitting area of 2 mm × 2 mm) was placed on the lithium fluoride layer, and metallic aluminum was formed as a cathode by vacuum deposition so as to have a thickness of 100 nm.

  The laminate produced as described above was put in a glove box substituted with argon gas, and sealed with a stainless steel sealing can and an ultraviolet curable adhesive (XNR5516HV, manufactured by Nagase Ciba Co., Ltd.). Thus, an organic electroluminescence device 1 using the iridium complex mixture 1 as a light emitting layer was produced.

<Preparation of organic electroluminescent element 2>
An organic electroluminescent device 2 was prepared in the same manner as the organic electroluminescent device 1 except that the iridium complex mixture 5 was used instead of the iridium complex mixture 1 in the production of the organic electroluminescent device 1. .

(Comparative Example 6)
<Preparation of organic electroluminescent element 3>
An organic electroluminescent device 3 was prepared in the same manner as the organic electroluminescent device 1 except that the iridium complex 1 was used in place of the iridium complex mixture 1 in the manufacture of the organic electroluminescent device 1.

<Preparation of organic electroluminescent element 4>
An organic electroluminescence device 4 was produced in the same manner as the organic electroluminescence device 1 except that the iridium complex 4 was used instead of the iridium complex mixture 1 in the production of the organic electroluminescence device 1.

<Preparation of organic electroluminescent element 5>
An organic electroluminescent element 5 was produced in the same manner as the organic electroluminescent element 1 except that the iridium complex 6 was used instead of the iridium complex mixture 1 in the production of the organic electroluminescent element 1.

<Evaluation>
For each organic electroluminescent element obtained in Example 6 and Comparative Example 6, the voltage and external quantum efficiency when a constant current ( ^2.5 mA / cm ² ) was applied were measured. The evaluation results are shown in Table 4.

<< Voltage >>
Using a source measure unit 2400 manufactured by KEITHLEY, the drive voltage during energization was measured.

<< External quantum efficiency >>
Using a source measure unit type 2400 manufactured by KEITHLEY, each element was supplied with a direct current having a current density of ^2.5 mA / cm ² to emit light. The brightness and emission spectrum were measured using a luminance meter SR-3 manufactured by Topcon Corporation. Based on these measurement results, the external quantum efficiency was calculated by an emission spectrum conversion method.

As is apparent from Table 4, the organic electroluminescent device using the iridium complex mixture of the present invention as a luminescent material is compared with the organic electroluminescent device using only the main component iridium complex in the iridium complex mixture as the luminescent material. Thus, both voltage and external quantum efficiency were the same.

(Example 7)
A coating type organic electroluminescent device using an iridium complex mixture as a luminescent material was produced.

<Preparation of coating type organic electroluminescent element 1>
-Preparation of coating solution-
The iridium complex mixture 1 (0.05% by mass) and the host compound 1 (0.95% by mass) are mixed in MEK (99% by mass), and the coating liquid for organic electroluminescent elements (coating liquid 1) is obtained. Got.

-Production of coating type organic electroluminescent element 1-
On a glass substrate having a thickness of 0.7 mm and a square of 2.5 cm, ITO (Indium Tin Oxide) was sputtered to a thickness of 150 nm as an anode. Next, this ITO-attached glass substrate was put into a cleaning container, subjected to ultrasonic cleaning in 2-propanol, and then subjected to UV-ozone treatment for 30 minutes.

  On this glass substrate with ITO, a solution obtained by dissolving 2 parts by mass of PTPDES-2 (manufactured by Chemipro Kasei, Tg = 205 ° C., high Tg polymer material) in 98 parts by mass of cyclohexanone for electronics industry (manufactured by Kanto Chemical) is spin-coated Then, it was dried at 120 ° C. for 30 minutes, and further annealed at 160 ° C. for 10 minutes to form a hole injection layer having a thickness of 40 nm.

  Next, in a glove box (dew point -68 ° C., oxygen concentration 10 ppm), the coating solution 1 was spin coated on the hole injection layer to form a light emitting layer having a thickness of 30 nm.

  Next, the BAlq was deposited on the light emitting layer by a vacuum deposition method to form an electron injection layer having a thickness of 40 nm.

  Next, lithium fluoride (LiF) was formed on the electron injection layer by a vacuum deposition method so as to have a thickness of 1 nm.

  Next, a patterned mask (a mask having a light emitting area of 2 mm × 2 mm) was placed on the lithium fluoride layer, and metallic aluminum was formed as a cathode by vacuum deposition so as to have a thickness of 100 nm.

  The laminate produced as described above was put in a glove box substituted with argon gas, and sealed with a stainless steel sealing can and an ultraviolet curable adhesive (XNR5516HV, manufactured by Nagase Ciba Co., Ltd.). The coating type organic electroluminescent element 1 was produced by the above.

<Preparation of coating type organic electroluminescent element 2>
In the production of the coating type organic electroluminescence device 1, the coating type organic electroluminescence device 1 was prepared in the same manner as the coating type organic electroluminescence device 1 except that the iridium complex mixture 1 was replaced with the iridium complex mixture 2. 2 was produced.

<Preparation of coating type organic electroluminescent element 3>
In the production of the coating type organic electroluminescence device 1, the coating type organic electroluminescence device 1 was prepared in the same manner as the coating type organic electroluminescence device 1 except that the iridium complex mixture 1 was replaced with the iridium complex mixture 3. 3 was produced.

<Preparation of coating type organic electroluminescent element 4>
In the production of the coating type organic electroluminescence device 1, the coating type organic electroluminescence device 1 was prepared in the same manner as the coating type organic electroluminescence device 1 except that the iridium complex mixture 1 was replaced with the iridium complex mixture 4. 4 was produced.

<Preparation of coating type organic electroluminescent element 5>
In the production of the coating type organic electroluminescence device 1, the coating type organic electroluminescence device 1 was prepared in the same manner as the coating type organic electroluminescence device 1 except that the iridium complex mixture 1 was replaced with the iridium complex mixture 5. 5 was produced.

(Comparative Example 7)
<Preparation of Coating Type Organic Electroluminescent Element 6>
In the production of the coating type organic electroluminescence device 1, the coating type organic electroluminescence device is produced in the same manner as the coating type organic electroluminescence device 1 except that the iridium complex mixture 1 is replaced with the iridium complex 6 having the following structure. Element 6 was produced.

<Preparation of coating type organic electroluminescent element 7>
In the production of the coating type organic electroluminescence device 1, the coating type organic electroluminescence device 1 was coated in the same manner as the coating type organic electroluminescence device 1 except that the iridium complex mixture 1 was replaced with the iridium complex 7 represented by the following structural formula. Type organic electroluminescent element 7 was produced.

<Evaluation (element durability)>
About the coating type organic electroluminescent element obtained in Example 7 and Comparative Example 7, element durability evaluation was performed.
A constant current ( ^2.5 mA / cm ² ) is applied continuously to a coating type organic electroluminescent element by a source measure unit 2400 made by KEITHLEY at room temperature at an initial emission luminance of 1,000 cd / m ^2. The time until the emission luminance decreased to ½ (luminance half-life) was measured, and the time of the coating type organic electroluminescence device 1 using the iridium complex mixture 1 was normalized as 1 and evaluated. The evaluation results are shown in Table 5.
The emission luminance was measured with a luminance meter SR-3 manufactured by Topcon Corporation.

As is apparent from Table 5, compared with the coating type organic electroluminescence devices 6 and 7 using the iridium complexes 6 and 7, the coating type organic electroluminescence devices 1 to 5 using the iridium complex mixtures 1 to 5 of the present invention are Excellent durability. Moreover, the coating type organic electroluminescent elements 1-3 using the iridium complex mixtures 1-3 whose iridium complex 1 content is 91% by mass or more with respect to the iridium complex mixture, and the iridium complex 4 content is iridium complex. The coating type organic electroluminescent device 5 using the iridium complex mixture 5 that is 91% by mass or more with respect to the mixture includes the iridium complex mixture 4 in which the content of the iridium complex 1 is less than 91% by mass with respect to the iridium complex mixture. It is more excellent in durability than the coating type organic electroluminescent element 4 used.

(Example 8 and Comparative Example 8)
An iridium complex mixture and an iridium complex coating solution were prepared, and the thermal stability of the light-emitting layer formed by the coating solution was evaluated.

<Evaluation of thermal stability>
<< Preparation of coating liquid >>
-Preparation of coating solution used for light emitting layer 1-
The iridium complex mixture 1 (0.05% by mass) and the host compound 1 (0.95% by mass) were mixed with MEK (99% by mass) to obtain a coating solution used for the light emitting layer 1.
−Preparation of coating solution used for light emitting layer 2−
The iridium complex mixture 5 (0.05% by mass) and the host compound 1 (0.95% by mass) were mixed with MEK (99% by mass) to obtain a coating solution used for the light emitting layer 2.
-Preparation of coating solution used for light emitting layer 3-
The iridium complex 1 (0.05% by mass) and the host compound 1 (0.95% by mass) were mixed with MEK (99% by mass) to obtain a coating solution used for the light emitting layer 3.
-Preparation of coating solution used for light emitting layer 4-
The iridium complex 4 (0.05% by mass) and the host compound 1 (0.95% by mass) were mixed with MEK (99% by mass) to obtain a coating solution used for the light emitting layer 4.
-Preparation of coating solution used for light emitting layer 5-
A coating solution used for the light-emitting layer 5 by mixing iridium complex 8 (0.05% by mass) represented by the following structural formula and the host compound 1 (0.95% by mass) in MEK (99% by mass). Got.

<< Preparation of Evaluation Sample >>
By using quartz glass (thickness 0.7 mm, length 16 mm, width 16 mm) as a base material, and spin-coating each of the coating liquids in the glove box on the base material to form a light emitting layer having a thickness of 30 μm, An evaluation sample was prepared.

<< Thermal stability test >>
The PL quantum yield was measured using an absolute PL quantum yield measuring apparatus (C9920-02, manufactured by Hamamatsu Photonics). The measurement was performed before and after heating at 160 ° C. for 30 minutes on a hot plate in a glove box. And the PL quantum yield change rate before and behind a heating was evaluated. The evaluation results are shown in Table 6.

As is apparent from Table 6, the iridium complex mixture in which the iridium and bidentate ligand atoms are only nitrogen atoms and carbon atoms has nitrogen atoms, carbon atoms, and oxygen atoms (acetylacetonate). It can be seen that the thermal stability is higher than that of the iridium complex 8.

Example 9
A coating type organic electroluminescent device using an iridium complex mixture as a hole injection layer was prepared.

<Preparation of Coating Type Organic Electroluminescent Element 8>
-Preparation of coating solution-
Iridium complex mixture 1 (0.6% by mass) and PTPDES (manufactured by Chemipro Kasei Co., Ltd., high Tg polymer material) (1.4% by mass) to cyclohexanone for electronic industry (manufactured by Kanto Chemical) (98% by mass) The organic electroluminescent element coating liquid (Coating liquid 2) was obtained by mixing.

-Production of coating type organic electroluminescent element 8-
On a glass substrate having a thickness of 0.7 mm and a square of 2.5 cm, ITO (Indium Tin Oxide) was sputtered to a thickness of 150 nm as an anode. Next, this ITO-attached glass substrate was put into a cleaning container, subjected to ultrasonic cleaning in 2-propanol, and then subjected to UV-ozone treatment for 30 minutes.

  The coating solution 2 was spin-coated on this ITO-coated glass substrate, dried at 120 ° C. for 30 minutes, and further annealed at 160 ° C. for 10 minutes to form a hole injection layer having a thickness of 40 nm.

  Next, the NPD as a hole transport layer was formed on the hole injection layer by a vacuum deposition method so as to have a thickness of 10 nm.

Next, CBP represented by the following structural formula as a host compound and iridium complex 3 as a light emitting material were co-deposited on the hole transport layer so that the mass ratio in the light emitting layer was 95: 5, and the thickness was 30 nm. A light emitting layer was formed.

  Next, the BAlq was formed as an electron injection layer on the light emitting layer by vacuum deposition so as to have a thickness of 40 nm.

  Next, lithium fluoride (LiF) was formed on the electron injection layer by a vacuum deposition method so as to have a thickness of 1 nm.

  Next, a patterned mask (a mask having a light emitting area of 2 mm × 2 mm) was placed on the lithium fluoride layer, and metallic aluminum was formed as a cathode by vacuum deposition so as to have a thickness of 100 nm.

  The laminate produced as described above was put in a glove box substituted with argon gas, and sealed with a stainless steel sealing can and an ultraviolet curable adhesive (XNR5516HV, manufactured by Nagase Ciba Co., Ltd.). The coating type organic electroluminescent element 8 was produced by the above.

<Preparation of coating type organic electroluminescent element 9>
In the production of the coating type organic electroluminescence device 8, the coating type organic electroluminescence device 8 was prepared in the same manner as the coating type organic electroluminescence device 8 except that the iridium complex mixture 1 was replaced with the iridium complex mixture 5. 9 was produced.

(Comparative Example 9)
<Preparation of Coating Type Organic Electroluminescent Device 10>
In the production of the coating type organic electroluminescence device 8, the coating type organic electroluminescence device 10 was prepared in the same manner as the production of the coating type organic electroluminescence device 8, except that the iridium complex mixture 1 was replaced with the iridium complex 1. Was made.

<Preparation of coating type organic electroluminescent element 11>
In the production of the coating type organic electroluminescence device 8, the coating type organic electroluminescence device 11 is prepared in the same manner as the production of the coating type organic electroluminescence device 8 except that the iridium complex mixture 1 is replaced with the iridium complex 4. Was made.

<Preparation of Coating Type Organic Electroluminescent Element 12>
In the production of the coating type organic electroluminescence device 8, the coating type organic electroluminescence device 12 was prepared in the same manner as the coating type organic electroluminescence device 8 except that the iridium complex mixture 1 was replaced with the iridium complex 6. Was made.

<Preparation of Coating Type Organic Electroluminescent Element 13>
In the production of the coating type organic electroluminescent element 8, the coating solution 2 was replaced with a coating solution in which PTPDES (2.0% by mass) was mixed with cyclohexanone for electronics industry (manufactured by Kanto Chemical) (98% by mass). In the same manner as in the preparation of the coating type organic electroluminescent element 8, a coating type organic electroluminescent element 13 was prepared.

<Evaluation>
The organic EL devices obtained in Example 9 and Comparative Example 9 were evaluated as follows.

<< Voltage and external quantum efficiency >>
The voltage and the external quantum efficiency were measured when the current density was adjusted to ^2.5 mA / cm ² . In addition, the measuring method of a voltage and external quantum efficiency is the same as the above-mentioned. Table 7 shows the measurement results.

<< Element durability >>
The constant luminance (2.5 mA / cm ² ) is applied to the organic electroluminescent element at room temperature at an initial light emission luminance of 1,000 cd / m ² to continuously drive the light emission luminance to ½. Time (luminance half-life) was measured, and the time of the coating type organic electroluminescent element 8 was normalized as 1 and evaluated. Table 7 shows the evaluation results.

From Table 7, it can be seen that by adding the iridium complex mixture of the present invention to the hole injection layer, the durability is greatly improved with almost no change in voltage and external quantum efficiency.

From the results in Table 3, it can be confirmed that the iridium complex mixture of the present invention is superior in solubility in a solvent than an iridium complex having a purity of 100%.
From the results shown in Table 4, the organic electroluminescent device using the iridium complex mixture of the present invention for the light emitting layer was compared with the organic electroluminescent device using 100% pure iridium complex for the light emitting layer. It can be confirmed that both are equivalent.
From the results shown in Table 5, it can be confirmed that the organic electroluminescence device using the iridium complex mixture of the present invention for the light emitting layer is excellent in durability.
From the results of Table 7, it can be confirmed that the durability of the organic electroluminescent device in which the iridium complex mixture of the present invention is added to the hole injection layer is significantly improved as compared with the non-added device.

  The iridium complex mixture of the present invention is excellent in solubility in a solvent, has a high yield in synthesis, is easy to produce without the need for purification such as chromatography, and is durable when used in an organic electroluminescent device. Because of its excellent properties, it can be suitably used for a light emitting layer and a hole injection layer of an organic electroluminescence device.

Claims (10)

Having two or more iridium complexes represented by the following general formula (1),
The bidentate ligand represented by B in the following general formula (1) of at least two iridium complexes of the two or more iridium complexes is a bidentate ligand having the same structure,
The iridium complex mixture, wherein the two or more iridium complexes are a main product and a by-product in the synthesis of the iridium complex.
(A) _m Ir (B) _n General formula (1)
However, in the said General formula (1), A and B represent the bidentate ligand of a different structure. A has a structure represented by the following general formula (2). m represents an integer of 0 to 2, n represents an integer of 1 to 3, and m + n = 3.
However, in said general formula (2), R < ₁ >, R < ₂ > and R < ₃ > represent an alkyl group each independently.   The iridium complex mixture according to claim 1, wherein the iridium of the iridium complex and the bidentate ligand are bonded to each other by a nitrogen atom and a carbon atom of the bidentate ligand. The iridium complex mixture according to any one of claims 1 to 2, wherein the iridium complex represented by the general formula (1) is an iridium complex represented by the following general formula (3).
In the general formula _{(3), R} 4 ~R ₁₉ independently represents a hydrogen atom, a fluorine atom, an alkyl group, an aryl group, an alkoxy group, adjacent _R 4 _{to R 19} are bonded to each other A ring may be formed. At least one of R _{4 to} R ₁₁ has a structure represented by the following general formula (2). m, n and m + n are the same as m, n and m + n in the general formula (1), respectively.
However, in said general formula (2), R < ₁ >, R < ₂ > and R < ₃ > represent an alkyl group each independently.   4. The iridium according to claim 1, wherein one kind of iridium complex among the iridium complexes in which m is not 0 is 91% by mass or more and 99.99% by mass or less based on the total amount of all iridium complexes. Complex mixture.   The iridium complex mixture according to any one of claims 1 to 4, wherein the iridium complex in which m is 1 is 91 mass% or more and 99.99 mass% or less based on the total amount of all iridium complexes. Having at least one organic layer between the anode and the cathode;
An organic electroluminescent device, wherein at least one of the organic layers is an organic layer containing the iridium complex mixture according to any one of claims 1 to 5.   The organic electroluminescent element according to claim 6, comprising three or more organic layers.   The organic electroluminescent element according to any one of claims 6 to 7, wherein the organic layer containing the iridium complex mixture is a light emitting layer.   The organic electroluminescent element according to any one of claims 6 to 7, wherein the organic layer containing the iridium complex mixture is a hole injection layer. An organic electroluminescence device manufacturing method for manufacturing an organic electroluminescence device according to any one of claims 6 to 9, wherein an organic layer containing an iridium complex mixture is formed by coating. Device manufacturing method.