WO2023182184A1

WO2023182184A1 - Light-emitting layer composition, organic electroluminescent element, and production method therefor

Info

Publication number: WO2023182184A1
Application number: PCT/JP2023/010460
Authority: WO
Inventors: 和弘長山; 茜加藤; 麻優子上田; 一毅岡部
Original assignee: 三菱ケミカル株式会社
Priority date: 2022-03-25
Filing date: 2023-03-16
Publication date: 2023-09-28
Also published as: TW202346311A

Abstract

The present invention addresses the problem of providing a light-emitting layer composition which enables an improvement in light emission efficiency of an element and a light-emitting layer composition (for example, an ink for a light-emitting layer) that contains an organic solvent. The present invention relates to a light-emitting layer composition comprising a compound represented by formula (1) and a compound represented by formula (2). (The symbols n, R, and a in formula (1) and m, Q, b, and X in formula (2) are as defined in the description.)

Description

Composition for light emitting layer, organic electroluminescent device and method for manufacturing the same

The present invention relates to a composition for a light-emitting layer containing two or more types of iridium complex compounds, and is particularly useful as an ink for an organic electroluminescent device (hereinafter sometimes referred to as an "organic EL device") that forms a light-emitting layer by coating. The present invention relates to a composition for a light emitting layer containing two or more types of iridium complex compounds, and a composition for a light emitting layer further containing an organic solvent (hereinafter sometimes referred to as "ink for a light emitting layer").

Various electronic devices that utilize organic EL elements, such as organic EL lighting and organic EL displays, have been put into practical use. Organic electroluminescent devices consume less power due to the low applied voltage and are capable of emitting light in three primary colors, so they are beginning to be applied not only to large display monitors but also to small and medium-sized displays such as mobile phones and smartphones. .

An organic electroluminescent device is manufactured by laminating multiple layers such as a light emitting layer, a charge injection layer, and a charge transport layer. Currently, most organic electroluminescent devices are manufactured by depositing organic materials under vacuum, but the vacuum deposition method requires a complicated deposition process and is low in productivity. The problem with organic electroluminescent devices is that it is extremely difficult to increase the size and definition of lighting and display panels. Therefore, in recent years, wet film forming methods (coating methods) have been actively researched as a process for efficiently manufacturing organic electroluminescent elements that can be used for large displays and lighting. The wet film formation method has the advantage of being able to easily form a stable layer compared to the vacuum evaporation method, so it is expected to be applied to mass production of displays and lighting devices and large devices.

In order to make these displays and lighting devices excellent products, there is a need to develop a method to improve the luminous efficiency of organic EL elements. In display applications, it is particularly effective to increase the luminous efficiency of green, which has the highest visibility among the three primary colors of blue, green, and red.

Phosphorescent materials that can efficiently convert excitons inside devices into light are widely used. For green, tris(phenylpyridine)iridium complex and its derivatives are used. It is known that organic EL devices using these complexes have an internal quantum yield close to 1, and there is a limit to the improvement of the luminous efficiency of the device by further improving the quantum yield.

As another promising method, the use of a combination of different phosphorescent materials is being considered. For example, in Patent Document 1, by putting a plurality of phosphorescent materials into one boat of a vapor deposition machine, decomposition is suppressed by lowering the vapor deposition temperature, and the dispersibility of the vapor deposited film is further improved. It is disclosed that the characteristics of the device are improved as a result. Patent Document 2 also discloses that device characteristics are improved by combining two types of iridium complex compounds in a vapor deposition device. In Patent Document 3, when an organic EL device is created by a coating method using two types of iridium complexes having a dendrimer type structure and different generations, an element using a single dendrimer type complex is It is disclosed that the luminous efficiency is higher than that of the conventional method.

International Publication No. 2002/104080 Japanese Patent Application Publication No. 2003-077674 International Publication No. 2004/020504

The methods disclosed in Patent Documents 1 and 2 are based on a vapor deposition method, and in the coating method, the temperature applied to the material is lower than in the vapor deposition method, and the device characteristics are deteriorated due to thermal decomposition of the iridium complex compound during vapor deposition. Such problems cannot occur. Furthermore, the iridium complex compounds disclosed in these publications have low solvent solubility and cannot be used as materials for organic EL devices by coating. Patent Document 3 discloses a method of creating an element by a coating method. However, when this method is applied, the luminous efficiency may be lower when two types of dendrimer complexes with different generations are used than when a single dendrimer complex is used. It has been found.
The present invention aims to provide a composition for a light-emitting layer that can further improve the luminous efficiency of a device, and a composition for a light-emitting layer (for example, an ink for a light-emitting layer) containing an organic solvent.

As a result of intensive studies by the present inventors to solve the above problems, a composition for a light-emitting layer containing two or more types of different iridium complex compounds having a specific chemical structure has been developed for use in organic EL devices, especially green light-emitting devices. The present inventors have discovered that the present invention contributes to improving luminous efficiency, and have completed the present invention.

That is, the gist of the present invention is as follows.
[1]
A composition for a light-emitting layer, comprising a compound represented by formula (1) and a compound represented by formula (2).

[However, n represents an integer from 0 to 10. R represents a substituent, and a represents a number from 0 to the maximum integer that can be substituted by one ligand. The types of R are independently D, F, Cl, Br, I, -N(R') ₂ , -CN, -NO ₂ , -OH, -COOR', -C(=O)R', - C(=O)NR', -P(=O)(R') ₂ , -S(=O)R', -S(=O) ₂ R', -OS(=O) ₂ R', carbon A straight chain, branched or cyclic alkyl group having 1 to 5 carbon atoms, a straight chain or branched alkoxy group having 1 to 4 carbon atoms, a straight chain, branched or cyclic alkylthio group having 1 to 4 carbon atoms, a carbon number Straight chain, branched or cyclic alkenyl group with 2 to 4 carbon atoms, straight chain, branched or cyclic alkynyl group with 2 to 4 carbon atoms, diarylamino group with 10 to 40 carbon atoms, 10 to 40 carbon atoms An arylheteroarylamino group or a diheteroarylamino group having 10 to 40 carbon atoms, the alkyl group, the alkoxy group, the alkylthio group, the alkenyl group, the alkynyl group, the diarylamino group, the arylheteroaryl group. The amino group and the diheteroarylamino group may be substituted with one or more R' other than hydrogen atoms.
R' each independently represents D, F, -CN, a straight chain, branched or cyclic alkyl group having 1 to 5 carbon atoms, a straight chain or branched alkenyl group having 2 to 4 carbon atoms, and 2 or more carbon atoms. It is a straight chain or branched alkynyl group of up to 4. ]

[However, m represents an integer from 0 to 10. Q represents a substituent, and b represents from 0 to the maximum integer that can be substituted by one ligand. X represents formula (3) or (4).

[However, the broken line represents a bond with the benzene ring, each Ar ¹ independently represents a trivalent aromatic hydrocarbon group having 6 to 30 carbon atoms or a trivalent heteroaromatic group having 2 to 30 carbon atoms, and Ar Each of ² independently represents a monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms or a monovalent heteroaromatic group having 2 to 30 carbon atoms. Ar ¹ and Ar ² in formulas (3) and (4) may be substituted with Q. ]]

[2]
The composition for a light-emitting layer according to [1], wherein formula (1) is represented by the following formula (5).

[R and a are as defined in [1]. n ¹ and n ² represent numbers such that n ¹ +n ² =n. ]

[3]
In formula (3) or (4), Ar ¹ each independently represents a trivalent aromatic hydrocarbon group having 6 to 30 carbon atoms, and Ar ² each independently represents a monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms. The composition for a light-emitting layer according to [1] or [2], which represents a hydrocarbon group.
[4]
The composition for a light-emitting layer according to any one of [1] to [3], wherein X in formula (2) is represented by formula (3).

[5]
The absolute value of the difference in maximum emission wavelength between the compound represented by formula (1) and the compound represented by formula (2), measured by the following measurement method, is 0 nm or more and 20 nm or less, [1] ~ The composition for a light-emitting layer according to any one of [4].
[Measurement method: Bubbling nitrogen for 20 minutes or more into a solution in which the compound represented by formula (1) or the compound represented by formula (2) is dissolved in toluene at a concentration of 1 × 10 ^-5 mol/L at room temperature. Then, the wavelength showing the maximum value of the phosphorescence spectrum intensity obtained from the sample from which oxygen, which causes quenching, has been removed is defined as the maximum emission wavelength. ]
[6]
The ratio of the mass of the compound represented by formula (1) to the total mass of the compound represented by formula (1) and the compound represented by formula (2) is 10% or more and 80% or less, [1] The composition for a light-emitting layer according to any one of [5] to [5].
[7]
The composition for a light-emitting layer according to any one of [1] to [6], further comprising an organic solvent.
[8]
A method for manufacturing an organic electroluminescent device having an anode, a light emitting layer, and a cathode in this order on a substrate, the method comprising:
A method for manufacturing an organic electroluminescent device, comprising a step of forming the light emitting layer by a wet film forming method using the composition for a light emitting layer according to [7].

[9]
An organic electroluminescent device having an anode, a light emitting layer, and a cathode in this order on a substrate,
An organic electroluminescent device comprising a compound represented by formula (1) and a compound represented by formula (2) in a light emitting layer.

According to the present invention, there is provided a composition for a light-emitting layer containing two or more types of iridium complex compounds that can further improve the luminous efficiency when used in an organic EL element, particularly the luminous efficiency in a green element.

1 is a cross-sectional view schematically showing an example of the structure of an organic electroluminescent device of the present invention.

Embodiments of the present invention will be described in detail below, but the present invention is not limited to the following embodiments, and can be implemented with various modifications within the scope of the gist.
In this specification, the term "aromatic ring" refers to an "aromatic hydrocarbon ring" and is distinguished from a "heteroaromatic ring" containing a hetero atom as a ring constituent atom. Similarly, "aromatic group" refers to "aromatic hydrocarbon ring group", and "heteroaromatic group" refers to "heteroaromatic ring group".
Moreover, in this specification, "solvent" and "solvent" have the same meaning.

The present invention relates to a composition for a light-emitting layer containing a compound represented by formula (1) and a compound represented by formula (2).

[However, n represents an integer from 0 to 10. R represents a substituent, and a represents a number from 0 to the maximum integer that can be substituted by one ligand. The types of R are independently D, F, Cl, Br, I, -N(R') ₂ , -CN, -NO ₂ , -OH, -COOR', -C(=O)R', - C(=O)NR', -P(=O)(R') ₂ , -S(=O)R', -S(=O) ₂ R', -OS(=O) ₂ R', carbon A straight chain, branched or cyclic alkyl group having 1 to 5 carbon atoms, a straight chain or branched alkoxy group having 1 to 4 carbon atoms, a straight chain, branched or cyclic alkylthio group having 1 to 4 carbon atoms, a carbon number Straight chain, branched or cyclic alkenyl group with 2 to 4 carbon atoms, straight chain, branched or cyclic alkynyl group with 2 to 4 carbon atoms, diarylamino group with 10 to 40 carbon atoms, 10 to 40 carbon atoms An arylheteroarylamino group or a diheteroarylamino group having 10 to 40 carbon atoms, the alkyl group, the alkoxy group, the alkylthio group, the alkenyl group, the alkynyl group, the diarylamino group, the arylheteroaryl group. The amino group and the diheteroarylamino group may be substituted with one or more R' other than hydrogen atoms.

R' each independently represents D, F, -CN, a straight chain, branched or cyclic alkyl group having 1 to 5 carbon atoms, a straight chain or branched alkenyl group having 2 to 4 carbon atoms, and 2 or more carbon atoms. It is a straight chain or branched alkynyl group of up to 4. ]

[However, m represents an integer from 0 to 10. Q represents a substituent, and b represents from 0 to the maximum integer that can be substituted by one ligand. However, X represents formula (3) or (4).

<Mechanism>
The reason why the present invention can further improve the luminous efficiency when used in an organic EL element, particularly the luminous efficiency in a green element, is estimated as follows.
In order to increase the luminous efficiency of organic EL devices, in addition to developing and using luminescent materials with high quantum yields whose value is as high as 100%, it is also necessary to (a) improve the charge balance within the luminescent layer, that is, holes and electrons; (b) Eliminate leakage of charges and excitons from within the emissive layer and confine them within the emissive layer; (c) Triplet-triplet annihilation of triplet excitons. It is necessary to eliminate deactivation processes such as triplet-polaron quenching, deactivation due to interaction between triplet excitons and charges, or deactivation due to impurities with a low T1 level. Regarding (a), the medium that accepts and transports electrons into the light-emitting layer is mainly played by the electron-transporting host material, while the medium that supplies holes is the hole-transporting material as well as the light-emitting material. Iridium complexes used as materials may also play a role. This tendency is particularly strong in the case of iridium complexes having a shallow ionization potential, and this applies to iridium complexes having phenyl-pyridine type ligands such as those of the present invention. This structure is widely known to have a high quantum yield and emit excellent green light. In order to improve hole transport properties, it is desirable to have a structure in which the iridium atoms, which are easily oxidized, are not excessively shielded by ligands, such as the iridium complex shown in formula (1). However, the lack of shielding may also make undesirable deactivation processes between iridium complexes as shown in (c) more likely to occur. Furthermore, if the hole transport property is too large, holes will leak to the electron transport layer side, making it impossible to satisfy the condition (b), and the efficiency of the device will decrease. Achieving such fine adjustment of the hole transport property only by optimizing the substituents in formula (1) is difficult because there are too many types of substituents and introduction positions, or the optimal structure is difficult to achieve. It is also possible that it does not exist. The present invention uses an iridium complex having a branched aromatic hydrocarbon group or a ligand having a heteroaromatic group partially conjugated around an iridium atom, as shown in formula (2). This problem is solved. Compared to formula (1), this structure shields iridium atoms relatively highly due to its branched structure, and it is thought that the above-mentioned quenching process is also relatively unlikely to occur. Therefore, by using formula (1) and formula (2) in combination, the ability of hole transport and the concentration of the luminescent material in the luminescent layer can be set to the optimum level without causing a quenching process in the luminescent layer, and the result is We believe that we were able to increase the efficiency of the device. Note that when a long-chain alkyl group such as 2-ethylhexyl group is used instead of X in formula (2), the charge balance in (a) is It is difficult to match the two, and furthermore, when coating and forming the light-emitting layer, the host material used in combination is rich in aromatic groups, which reduces compatibility and causes aggregation, causing deterioration of device performance. do not have.

<Structure of the iridium complex of the present invention>
Three bidentate ligands such as 2-phenylpyridine can be bonded to the trivalent iridium complex compound. In this case, a complex in which all three ligands are the same is called a homoleptic complex, and a complex in which at least one ligand is different is called a heteroleptic complex. The present invention requires a homoleptic complex capable of narrowing the half-width of the emission spectrum. This is because for display applications, it is required to make the half-width as narrow as possible from the viewpoint of color purity.
Two isomers of the homoleptic iridium complex compound are known: a facial form and a meridional form. In the present invention, it is necessary that the facial body has a narrow spectral half-value width and a high quantum yield.

<<Formula (1)>>

[However, n represents an integer from 0 to 10. R represents a substituent, and a represents a number from 0 to the maximum integer that can be substituted by one ligand. The types of R are independently D, F, Cl, Br, I, -N(R') ₂ , -CN, -NO ₂ , -OH, -COOR', -C(=O)R', - C(=O)NR', -P(=O)(R') ₂ , -S(=O)R', -S(=O) ₂ R', -OS(=O) ₂ R', carbon A straight chain, branched or cyclic alkyl group having 1 to 5 carbon atoms, a straight chain or branched alkoxy group having 1 to 4 carbon atoms, a straight chain, branched or cyclic alkylthio group having 1 to 4 carbon atoms, a carbon number Straight chain or branched alkenyl group having 2 to 4 carbon atoms, straight chain or branched alkynyl group having 2 to 4 carbon atoms, diarylamino group having 10 to 40 carbon atoms, arylheteroarylamino group having 10 to 40 carbon atoms group or a diheteroarylamino group having 10 to 40 carbon atoms, the alkyl group, the alkoxy group, the alkylthio group, the alkenyl group, the alkynyl group, the diarylamino group, the arylheteroarylamino group, and the The diheteroarylamino group may be substituted with one or more R's other than hydrogen atoms.
R' each independently represents D, F, -CN, a straight chain, branched or cyclic alkyl group having 1 to 5 carbon atoms, a straight chain or branched alkenyl group having 2 to 4 carbon atoms, and 2 or more carbon atoms. It is a straight chain or branched alkynyl group of up to 4. ]
<n>
n is an integer from 0 to 10. When n is larger than 10, the size of the iridium complex becomes too large, and the distance between the vicinity of the iridium atom, which is responsible for the hole transport property, and the surface of the iridium complex molecule becomes large, and the hole transport property of the iridium complex is impaired. As a result, the light emitting life and driving life of the element may be reduced. On the other hand, if n is within this range, as described in the <mechanism> section, the iridium complex compound can exhibit charge exchange and hole transport properties without being excessively shielded, which is preferable. . Therefore, n is preferably an integer of 0 to 8, more preferably an integer of 0 to 7, and still more preferably an integer of 1 to 6.

<Binding mode of phenylene group>
The bonding mode of the n phenylene groups is not particularly limited, and there are three types independently of each other: the ortho position, the meta position, and the para position. Bonds at the ortho and meta positions are highly flexible and improve solubility, and in addition, the conjugation of π electrons is interrupted, so the T1 level can be raised and the effect of quenching green light emission can be suppressed. From the viewpoint of solubility, bonding at the ortho position is more preferable since it can generate rotamers due to steric hindrance, and from the viewpoint of durability, bonding at the meta position is even more preferable. The bond at the ortho position may change to a triphenylene structure due to oxidative coupling as shown in the following formula during operation of the organic EL device. This is because such a change may cause deterioration of the device due to an increase in the emission wavelength or a decrease in hole transportability.

On the other hand, when they are linked at the para position, the conjugation of π electrons becomes longer, so the oxidation state can be particularly stabilized, and as a result, the hole transport properties are further improved. The hole transport property mainly originates from the electron-rich iridium atom, so if the electrons of the iridium atom can be distributed more widely toward the ligand side through the π-conjugated bonds of multiple paraphenylene groups, the hole transport property can be improved. The improvement is remarkable. Therefore, a preferred structure of the phenylene group is one in which the phenylene group directly connected to the para position of the iridium atom is bonded at the para position in the phenyl group of the phenylpyridine ligand, as shown in the following formula (5). However, n ¹ represents the number of consecutive para-phenylene groups and is an integer of 1 or more, and n ² represents the number of consecutive phenylene groups further bonded to the terminal of the para-phenylene group, n ¹ + n ² = n It is. From the viewpoint of durability, all consecutive phenylene groups further bonded to the terminals of the paraphenylene ring are preferably metaphenylene groups. From the viewpoint of solubility, the range of n ¹ is preferably 1 to 3, more preferably 1 or 2, even more preferably 1, and the range of n ² is preferably 1 to 8, more preferably The number is from 2 to 7, more preferably from 3 to 6.

That is, it is preferable that formula (1) is expressed by the following formula (5).

[R and a are as defined for formula (1). n ¹ and n ² represent numbers such that n ¹ +n ² =n. ]

<Substituent R>
The type of substituent R that the formula (1) may have is selected from the following [substituent group W]. However, in the case of a non-aromatic substituent, it has the effect of electrically insulating the iridium complex compound, so if it is too large, there is a risk of reducing the hole transporting property of the iridium complex compound. The number of carbon atoms is limited to such an extent that the effect does not appear.

[Substituent group W]
D, F, Cl, Br, I, -N(R') ₂ , -CN, -NO ₂ , -OH, -COOR', -C(=O)R', -C(=O)NR', -P(=O)(R') ₂ , -S(=O)R', -S(=O) ₂ R', -OS(=O) ₂ R', straight with 1 to 5 carbon atoms Chain, branched or cyclic alkyl group, straight chain, branched alkoxy group having 1 to 4 carbon atoms, straight chain, branched or cyclic alkylthio group having 1 to 4 carbon atoms, straight chain having 2 to 4 carbon atoms , branched or cyclic alkenyl group, linear, branched or cyclic alkynyl group having 2 to 4 carbon atoms, diarylamino group having 10 to 40 carbon atoms, arylheteroarylamino group having 10 to 40 carbon atoms, carbon number 10 or more and 40 or less diheteroarylamino groups.
The alkyl group, the alkoxy group, the alkylthio group, the alkenyl group, the alkynyl group, the diarylamino group, the arylheteroarylamino group, and the diheteroarylamino group have one or more R' other than hydrogen atoms. may be replaced with .
R' will be described later.

Each substituent in the above [substituent group W] will be explained below.
Examples of straight chain, branched or cyclic alkyl groups having 1 to 5 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, n-pentyl group, isopropyl group, isobutyl group. , cyclopentyl group, etc. In the case of an alkyl group, if the number of carbon atoms is large, the iridium complex will be highly shielded and durability will be impaired, so the number of carbon atoms is preferably 1 or more, preferably 4 or less, more preferably 3 or less, and 2 or less. More preferred.

Examples of linear, branched or cyclic alkoxy groups having 1 or more and 4 or less carbon atoms include methoxy, ethoxy, n-propyloxy, n-butoxy and the like. From the viewpoint of durability, the number of carbon atoms is preferably 1 or more, preferably 3 or less, more preferably 2 or less, and most preferably 1.

Examples of linear, branched or cyclic alkylthio groups having 1 to 4 carbon atoms include methylthio group, ethylthio group, n-propylthio group, n-butylthio group, and isopropylthio group. From the viewpoint of durability, the number of carbon atoms is preferably 1 or more, preferably 3 or less, more preferably 2 or less, and most preferably 1.

Examples of linear or branched alkenyl groups having 2 or more and 4 or less carbon atoms include vinyl groups, allyl groups, propenyl groups, butadiene groups, and the like. From the viewpoint of durability, the number of carbon atoms is preferably 2 or more, preferably 3 or less, and most preferably 2.

Examples of linear or branched alkynyl groups having 2 or more and 4 or less carbon atoms include ethynyl, propionyl, and butynyl groups. From the viewpoint of durability, the number of carbon atoms is preferably 2 or more, preferably 3 or less, and most preferably 2.

Examples of the diarylamino group having 10 to 40 carbon atoms include diphenylamino group, phenyl(naphthyl)amino group, di(biphenyl)amino group, di(p-terphenyl)amino group, and the like. From the viewpoint of balance between solubility and durability, the number of carbon atoms in these diarylamino groups is preferably 10 or more, preferably 36 or less, more preferably 30 or less, and 25 or less. Most preferably.

Examples of the arylheteroarylamino group having 10 to 40 carbon atoms include phenyl(2-pyridyl)amino group, phenyl(2,6-diphenyl-1,3,5-triazin-4-yl)amino group, etc. Can be mentioned. From the viewpoint of balance between solubility and durability, the number of carbon atoms in these arylheteroarylamino groups is preferably 10 or more, more preferably 36 or less, more preferably 30 or less, 25 The following is most preferable.

Examples of the diheteroarylamino group having 10 to 40 carbon atoms include di(2-pyridyl)amino group, di(2,6-diphenyl-1,3,5-triazin-4-yl)amino group, etc. . From the viewpoint of balance between solubility and durability, the number of carbon atoms in these diheteroarylamino groups is preferably 10 or more, preferably 36 or less, more preferably 30 or less, and 25 The following is most preferable.

More preferable types of substituents include D, F, -CN, or a linear chain having 1 to 5 carbon atoms, particularly from the viewpoint of not impairing the durability as a luminescent material in an organic electroluminescent device. , branched or cyclic alkyl groups, D, F, --CN, methyl or trifluoromethyl groups are particularly preferred, with D being most preferred.

<R'>
The above R' each independently represents D, F, -CN, a straight chain, branched or cyclic alkyl group having 1 to 5 carbon atoms, a straight chain or branched alkenyl group having 2 to 4 carbon atoms, and a carbon number It is selected from 2 to 4 linear or branched alkynyl groups.

<a>
a is an integer from 0 to the maximum integer that can be substituted by one ligand in formula (1). The largest integer can be calculated as 3(n+4).

<Molecular weight>
There is no particular restriction on the molecular weight of the iridium complex compound represented by formula (1), but if it is too small, the solubility may decrease and the composition of the present invention may not be able to be used as an ink. On the other hand, if the molecular weight is too large, hole transport properties may decrease. Therefore, the molecular weight range is preferably 1,111 to 10,000, more preferably 1,300 to 8,000, even more preferably 1,500 to 5,000.

<<Formula (2)>>

<m>
m is an integer from 0 to 10. However, when m=0, X is directly bonded to the para position of the iridium atom in the benzene ring bonded to the iridium atom. If m is too large, the iridium atoms will be largely shielded, greatly impairing hole transport to the iridium complex, or the shielding will impair charge injection and energy transfer to the iridium complex, resulting in poor performance of the device. There is a risk that luminous efficiency and drive life will be reduced. Therefore, the range of m is preferably an integer of 0 to 8, more preferably an integer of 0 to 6, and even more preferably an integer of 0 to 4. Further, the preferable bonding mode of the m phenylene groups connected is the same as in formula (1).

<X>
X represents formula (3) or (4). The broken line in formula (3) or (4) represents the bond with the benzene ring.

<Ar ¹ and Ar ² >
Ar ¹ each independently represents a trivalent aromatic hydrocarbon group having 6 to 30 carbon atoms or a trivalent heteroaromatic group having 2 to 30 carbon atoms, and Ar ² each independently represents a trivalent aromatic hydrocarbon group having 6 to 30 carbon atoms; Represents a valent aromatic hydrocarbon group or a monovalent heteroaromatic group having 2 to 30 carbon atoms. The type of these aromatic hydrocarbon groups or heteroaromatic groups may be a single ring, a condensed ring, or a structure formed by bonding these groups. Ar ¹ and Ar ² may be substituted with Q. It is preferable that each Ar ¹ independently represents a trivalent aromatic hydrocarbon group having 6 to 30 carbon atoms, and each Ar ² independently represents a monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms.

As examples of the types of aromatic hydrocarbon groups or heteroaromatic groups, the corresponding parent skeletons include benzene ring, naphthalene ring, anthracene ring, benzanthracene ring, phenanthrene ring, benzophenanthrene ring, pyrene ring, Chrysene ring, fluoranthene ring, perylene ring, benzopyrene ring, benzofluoranthene ring, naphthacene ring, pentacene ring, biphenyl, terphenyl, quaterphenyl, fluorene ring, spirobifluorene ring, dihydrophenanthrene ring, dihydropyrene ring, tetrahydro Pyrene ring, indenofluorene ring, furan ring, benzofuran ring, isobenzofuran ring, dibenzofuran ring, thiophene ring, benzothiophene ring, dibenzothiophene ring, pyrrole ring, indole ring, isoindole ring, carbazole ring, benzocarbazole ring, India Locarbazole ring, indenocarbazole ring, pyridine ring, cinnoline ring, isocinnoline ring, acridine ring, phenanthridine ring, phenothiazine ring, phenoxazine ring, pyrazine ring, imidazole ring, benzimidazole ring, naphthimidazole ring, phenanthro Imidazole ring, oxazole ring, benzoxazole ring, naphthoxazole ring, thiazole ring, benzothiazole ring, pyrimidine ring, benzopyrimidine ring, pyridazine ring, quinoxaline ring, diazaanthracene ring, diazapyrene ring, phenoxazine ring, phenothiazine ring, naphthyridine ring, azacarbazole ring, benzocarboline ring, phenanthroline ring, triazole ring, benzotriazole ring, oxadiazole ring, thiadiazole ring, triazine ring, 2,6-diphenyl-1,3,5-triazine ring, tetrazole ring , a purine ring, a benzothiadiazole ring, and the like.

From the viewpoint of durability, both Ar ¹ and Ar ² are preferably a monocyclic ring having a 6-membered ring structure, a condensed ring containing a 6-membered ring structure, or an aromatic hydrocarbon group or a heteroaromatic ring having a structure in which these are combined. More preferably, the six-membered ring structure is an aromatic hydrocarbon ring, most preferably a benzene ring.

When Ar ¹ is a benzene ring, there are no restrictions on the bonding positions of the two Ar ^2s , but if a bonding site appears at the ortho position, the conjugated system of π electrons will be broken due to steric hindrance, resulting in poor durability. inferior to Therefore, when Ar ¹ is a benzene ring, preferred bonding positions are the 1st, 3rd, and 5th positions, which are meta positions to each other.

Multiple Ar ¹ 's appearing in formula (4) preferably have different structures from the viewpoint of increasing solubility, but from the viewpoint of durability, it is more preferable that they have the same structure.

From the viewpoint of increasing solubility, it is preferable that Ar ² that appears multiple times in formula (3) or formula (4) have different structures, but from the viewpoint of durability, it is more preferable that they have the same structure.

<Q>
Q represents a substituent. The type of Q is not particularly limited and should be appropriately selected in order to adjust the solubility and emission wavelength, but the type usually selected is the following [substituent group Z].

[Substituent group Z]
D, F, Cl, Br, I, -N(Q') ₂ , -CN, -NO ₂ , -OH, -SH, -COOQ', -C(=O)Q', -C(=O) NQ', -P(=O)(Q') ₂ , -S(=O)Q', -S(=O) ₂ Q', -OS(=O) ₂ Q', -SiQ' ₃ , Carbon A straight chain, branched or cyclic alkyl group having 1 to 30 carbon atoms, a straight chain, branched or cyclic alkoxy group having 1 to 30 carbon atoms, a straight chain, branched or cyclic alkylthio group having 1 to 30 carbon atoms, Straight chain, branched or cyclic alkenyl group having 2 to 30 carbon atoms, straight chain, branched or cyclic alkynyl group having 2 to 30 carbon atoms, aromatic hydrocarbon group having 5 to 60 carbon atoms, 2 carbon atoms Aromatic heterocyclic group with 5 to 40 carbon atoms, aryloxy group with 5 to 40 carbon atoms, arylthio group with 5 to 40 carbon atoms, aralkyl group with 5 to 60 carbon atoms, heteroaralkyl group with 5 to 60 carbon atoms group, a diarylamino group having 10 to 40 carbon atoms, an arylheteroarylamino group having 10 to 40 carbon atoms, or a diheteroarylamino group having 10 to 40 carbon atoms.

The alkyl group, the alkoxy group, the alkylthio group, the alkenyl group, and the alkynyl group may be further substituted with one or more Q', and one or more -CH ₂ - groups in these groups The non-adjacent -CH ₂ - groups of -C(-Q')=C(-Q')-, -C≡C-, -Si(-Q') ₂ , -C(=O)- , -NQ'-, -O-, -S-, -CONQ'-, a divalent aromatic hydrocarbon group, or a divalent aromatic heterocyclic group. Furthermore, one or more hydrogen atoms in these groups may be substituted with F, Cl, Br, I or -CN.

The aromatic hydrocarbon group, the aromatic heterocyclic group, the aryloxy group, the arylthio group, the aralkyl group, the heteroaralkyl group, the diarylamino group, the arylheteroarylamino group, and the diheteroarylamino group may each be independently further substituted with one or more Q'.
Q' will be described later.

Examples of straight chain, branched or cyclic alkyl groups having 1 to 30 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, n-pentyl group, n-hexyl group, Examples include n-octyl group, 2-ethylhexyl group, isopropyl group, isobutyl group, cyclopentyl group, cyclohexyl group, n-octyl group, norbornyl group, and adamantyl group. In the case of an alkyl group, if the number of carbon atoms is too large, the complex will be highly shielded and durability will be impaired, so the number of carbon atoms is preferably 1 or more, preferably 30 or less, more preferably 20 or less, and 12 The following are more preferred. However, in the case of a branched alkyl group, the shielding effect is greater than that of a straight-chain alkyl group or a cyclic alkyl group, so the number of carbon atoms is most preferably 8 or less.

Examples of straight chain, branched or cyclic alkoxy groups having 1 to 30 carbon atoms include methoxy group, ethoxy group, n-propyloxy group, n-butoxy group, n-hexyloxy group, isopropyloxy group, cyclohexyloxy group. group, 2-ethoxyethoxy group, 2-ethoxyethoxyethoxy group, etc. From the viewpoint of durability, the number of carbon atoms is preferably 1 or more, preferably 30 or less, more preferably 20 or less, and most preferably 12 or less.

Examples of straight chain, branched or cyclic alkylthio groups having 1 to 30 carbon atoms include methylthio group, ethylthio group, n-propylthio group, n-butylthio group, n-hexylthio group, isopropylthio group, cyclohexylthio group, Examples include 2-methylbutylthio group and n-hexylthio group. From the viewpoint of durability, the number of carbon atoms is preferably 1 or more, preferably 30 or less, more preferably 20 or less, and most preferably 12 or less.

Examples of linear, branched or cyclic alkenyl groups having 2 to 30 carbon atoms include vinyl, allyl, propenyl, heptenyl, cyclopentenyl, cyclohexenyl, cyclooctenyl and the like. From the viewpoint of durability, the number of carbon atoms is preferably 2 or more, preferably 30 or less, more preferably 20 or less, and most preferably 12 or less.

Examples of straight chain, branched or cyclic alkynyl groups having 2 or more and 30 or less carbon atoms include ethynyl, propionyl, butynyl, pentynyl, hexynyl, heptynyl, octynyl and the like. From the viewpoint of durability, the number of carbon atoms is preferably 2 or more, preferably 30 or less, more preferably 20 or less, and most preferably 12 or less.

The aromatic hydrocarbon group having 5 to 60 carbon atoms and the aromatic heterocyclic group having 2 to 60 carbon atoms may exist as a single ring or a condensed ring, or one ring may contain another ring. It may be a group formed by bonding or condensing various aromatic hydrocarbon groups or aromatic heterocyclic groups.

Examples of these include phenyl, naphthyl, anthracenyl, benzanthracenyl, phenanthrenyl, benzophenanthrenyl, pyrenyl, chrysenyl, fluoranthenyl, perylenyl, benzopyrenyl, benzoflurenyl, oranthenyl group, naphthacenyl group, pentacenyl group, biphenyl group, terphenyl group, fluorenyl group, spirobifluorenyl group, dihydrophenanthrenyl group, dihydropyrenyl group, tetrahydropyrenyl group, indenofluorenyl group, furyl group, benzofuryl group, isobenzofuryl group, dibenzofuranyl group, thiophene group, benzothiophenyl group, dibenzothiophenyl group, pyrrolyl group, indolyl group, isoindolyl group, carbazolyl group, benzocarbazolyl group, indolocarbazolyl group group, indenocarbazolyl group, pyridyl group, cinnolyl group, isocinnolyl group, acridyl group, phenanthridyl group, phenothiazinyl group, phenoxazyl group, pyrazolyl group, indazolyl group, imidazolyl group, benzimidazolyl group, naphthiimidazolyl group, Nanthroimidazolyl group, pyridineimidazolyl group, oxazolyl group, benzoxazolyl group, naphthoxazolyl group, thiazolyl group, benzothiazolyl group, pyrimidyl group, benzopyrimidyl group, pyridazinyl group, quinoxalinyl group, diazaanthracenyl group, diazapyrenyl group group, pyrazinyl group, phenoxazinyl group, phenothiazinyl group, naphthyridinyl group, azacarbazolyl group, benzocarbolinyl group, phenanthrolinyl group, triazolyl group, benzotriazolyl group, oxadiazolyl group, thiadiazolyl group, triazinyl group, 2, Examples include 6-diphenyl-1,3,5-triazin-4-yl group, tetrazolyl group, purinyl group, and benzothiadiazolyl group.

From the viewpoint of balance between solvent solubility and durability, the carbon number of these groups is preferably 5 or more, preferably 50 or less, more preferably 40 or less, and most preferably 30 or less. preferable.

Examples of the aryloxy group having 5 to 40 carbon atoms include phenoxy group, methylphenoxy group, naphthoxy group, and methoxyphenoxy group. From the viewpoint of balance between solubility and durability, the number of carbon atoms in these aryloxy groups is 5 or more, preferably 30 or less, more preferably 25 or less, and most preferably 20 or less.

Examples of the arylthio group having 5 to 40 carbon atoms include phenylthio group, methylphenylthio group, naphthylthio group, and methoxyphenylthio group. From the viewpoint of balance between solubility and durability, the number of carbon atoms in these arylthio groups is 5 or more, preferably 30 or less, more preferably 25 or less, and most preferably 20 or less.

Examples of aralkyl groups having 5 to 60 carbon atoms include 1,1-dimethyl-1-phenylmethyl group, 1,1-di(n-butyl)-1-phenylmethyl group, and 1,1-di(n-butyl)-1-phenylmethyl group. -hexyl)-1-phenylmethyl group, 1,1-di(n-octyl)-1-phenylmethyl group, phenylmethyl group, phenylethyl group, 3-phenyl-1-propyl group, 4-phenyl-1- n-butyl group, 1-methyl-1-phenylethyl group, 5-phenyl-1-n-propyl group, 6-phenyl-1-n-hexyl group, 6-naphthyl-1-n-hexyl group, 7- Examples include phenyl-1-n-heptyl group, 8-phenyl-1-n-octyl group, and 4-phenylcyclohexyl group. From the viewpoint of the balance between solubility and durability, the number of carbon atoms in these aralkyl groups is preferably 5 or more, and more preferably 40 or less.

Examples of heteroaralkyl groups having 5 to 60 carbon atoms include 1,1-dimethyl-1-(2-pyridyl)methyl group, 1,1-di(n-hexyl)-1-(2-pyridyl)methyl group, (2-pyridyl)methyl group, (2-pyridyl)ethyl group, 3-(2-pyridyl)-1-propyl group, 4-(2-pyridyl)-1-n-butyl group, 1-methyl- 1-(2-pyridyl)ethyl group, 5-(2-pyridyl)-1-n-propyl group, 6-(2-pyridyl)-1-n-hexyl group, 6-(2-pyrimidyl)-1- n-hexyl group, 6-(2,6-diphenyl-1,3,5-triazin-4-yl)-1-n-hexyl group, 7-(2-pyridyl)-1-n-heptyl group, 8 Examples include -(2-pyridyl)-1-n-octyl group and 4-(2-pyridyl)cyclohexyl group. From the viewpoint of balance between solubility and durability, the number of carbon atoms in these heteroaralkyl groups is 5 or more, preferably 50 or less, more preferably 40 or less, and 30 or less. Most preferred.

Examples of the diarylamino group having 10 to 40 carbon atoms include diphenylamino group, phenyl(naphthyl)amino group, di(biphenyl)amino group, di(p-terphenyl)amino group, and the like. From the viewpoint of balance between solubility and durability, the carbon number of these diarylamino groups is preferably 10 or more, and preferably 36 or less, more preferably 30 or less, and preferably 25 or less. Most preferred.

Examples of the arylheteroarylamino group having 10 to 40 carbon atoms include phenyl(2-pyridyl)amino and phenyl(2,6-diphenyl-1,3,5-triazin-4-yl)amino groups. It will be done. From the viewpoint of balance between solubility and durability, the number of carbon atoms in these arylheteroarylamino groups is 10 or more, preferably 36 or less, more preferably 30 or less, and 25 or less. is most preferable.

Examples of the diheteroarylamino group having 10 to 40 carbon atoms include di(2-pyridyl)amino group, di(2,6-diphenyl-1,3,5-triazin-4-yl)amino group, etc. . From the viewpoint of the balance between solubility and durability, the carbon number of these diheteroarylamino groups is 10 or more, preferably 36 or less, more preferably 30 or less, and 25 or less. is most preferable.

<Q'>
Q' is D, F, Cl, Br, I, -N(Q'') ₂ , -OH, -SH, -CN, -NO ₂ , -Si(Q'') ₃ , -B(OQ'') ₂ , -C(=O)Q'', -P(=O)(Q'') ₂ , -S(=O) ₂ Q'', -OSO ₂ Q'', carbon number 1 or more 30 The following straight chain, branched or cyclic alkyl groups, straight chain, branched or cyclic alkoxy groups having 1 to 30 carbon atoms, straight chain, branched or cyclic alkylthio groups having 1 to 30 carbon atoms, 2 or more carbon atoms Straight chain, branched or cyclic alkenyl group with 30 or less carbon atoms, straight chain, branched or cyclic alkynyl group with 2 to 30 carbon atoms, aromatic hydrocarbon group with 5 to 60 carbon atoms, 2 to 60 carbon atoms Aromatic heterocyclic group, aryloxy group having 5 to 40 carbon atoms, arylthio group having 5 to 40 carbon atoms, aralkyl group having 5 to 60 carbon atoms, heteroaralkyl group having 5 to 60 carbon atoms, carbon number It is selected from a diarylamino group having 10 to 40 carbon atoms, an arylheteroarylamino group having 10 to 40 carbon atoms, or a diheteroarylamino group having 10 to 40 carbon atoms.
When multiple Q's exist, they may be the same or different.

The alkyl group, the alkoxy group, the alkylthio group, the alkenyl group, and the alkynyl group may be further substituted with one or more R'', and one -CH ₂ - group or two The above non-adjacent -CH ₂ - groups are -C(-Q'')=C(-Q'')-, -C≡C-, -Si(-Q'') ₂ -, -C May be substituted with (=O)-, -NQ''-, -O-, -S-, -CONQ''- or a divalent aromatic hydrocarbon group or a divalent aromatic heterocyclic group . Furthermore, one or more hydrogen atoms in these groups may be substituted with F, Cl, Br, I or -CN.

Further, the aromatic hydrocarbon group, the aromatic heterocyclic group, the aryloxy group, the arylthio group, the aralkyl group, the heteroaralkyl group, the diarylamino group, the arylheteroarylamino group, and the diheteroaryl group. The amino group may be further substituted with one or more Q''.
Q'' will be described later.

Furthermore, two or more adjacent Q' may be bonded to each other while losing their respective hydrogen atoms to form an aliphatic, aromatic hydrocarbon, or heteroaromatic monocyclic or fused ring.

<Q''>
Q'' is each independently D, F, -CN, an aliphatic hydrocarbon group having 1 to 20 carbon atoms, an aromatic hydrocarbon group having 5 to 20 carbon atoms, or an aromatic group having 5 to 20 carbon atoms. selected from heterocyclic groups.
Two or more adjacent Q'' may be bonded to each other while losing their respective hydrogen atoms to form an aliphatic, aromatic hydrocarbon, or heteroaromatic monocyclic or fused ring. When multiple Q''s exist, they may be the same or different.

From the viewpoint of durability, more preferable types of the substituent Q that the formula (2) may have are D, F, a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms, and 2 carbon atoms. A linear, branched or cyclic alkenyl group having 30 or more carbon atoms, an aromatic hydrocarbon group having 5 to 60 carbon atoms, an aromatic heterocyclic group having 2 to 60 carbon atoms, an aralkyl group having 5 to 60 carbon atoms, A heteroaralkyl group having 5 to 60 carbon atoms, a diarylamino group having 10 to 40 carbon atoms, an arylheteroarylamino group having 10 to 40 carbon atoms, or a diheteroarylamino group having 10 to 40 carbon atoms. More preferable types are D, F, straight chain, branched or cyclic alkyl group having 1 to 30 carbon atoms, aromatic hydrocarbon group having 5 to 60 carbon atoms, aromatic group having 2 to 60 carbon atoms. A heterocyclic group, a diarylamino group having 10 to 40 carbon atoms, an arylheteroarylamino group having 10 to 40 carbon atoms, or a diheteroarylamino group having 10 to 40 carbon atoms, and the most preferred types are: D, F, a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms, and an aromatic hydrocarbon group having 5 to 60 carbon atoms, and D or F is preferred among them.

<b>
b ranges from 0 to the maximum integer that can be substituted by one ligand in formula (2).

<Molecular weight>
There is no particular restriction on the molecular weight of the iridium complex compound represented by formula (2), but if it is too small, the solubility may decrease and the composition of the present invention may not be able to be used as an ink. On the other hand, if the molecular weight is too large, hole transport properties may decrease. Therefore, the molecular weight range is preferably 1,339 to 15,000, more preferably 1,650 to 12,000, and still more preferably 1,750 to 10,000.

<<Preferred combination>>
The combination of the compound represented by the formula (1) and the compound represented by the formula (2) can be used as the compound represented by the formula (2) from the viewpoint of further increasing the luminous efficiency. It is preferable to use a compound represented by formula (3). Furthermore, as a compound represented by formula (1), a compound represented by formula (5) is used, and as a compound represented by formula (2), X in formula (2) is represented by formula (3). It is more preferable that the compound is

<<Specific example>>
Preferred specific examples of the iridium complex compound of the present invention are shown below, but the present invention is not limited thereto.

<<Method for measuring maximum emission wavelength in solution>>
The method for measuring the maximum emission wavelength in a solution of the iridium complex compound of the present invention is as follows.
At room temperature, a solution prepared by dissolving an iridium complex compound in toluene at a concentration of 1 x 10 ^-4 mol/L or less, preferably 1 x 10 ^-5 mol/L, was measured using a spectrophotometer (manufactured by Hamamatsu Photonics, organic EL quantum absorption). The phosphorescence spectrum is measured using a rate measuring device C9920-02). However, before measurement, it is necessary to sufficiently remove oxygen, which causes quenching, by bubbling nitrogen or by freezing and degassing. The wavelength showing the maximum value of the obtained phosphorescence spectrum intensity is regarded as the maximum emission wavelength in the present invention.

<Maximum emission wavelength of the compound represented by formula (1) and the compound represented by formula (2)>
There is no particular restriction on the maximum emission wavelength exhibited by the iridium complex compound of the present invention, but when used as a particularly preferable green light-emitting material, the compound represented by formula (1) and the compound represented by formula (2) are preferred. For any of these, the lower limit is usually 490 nm or more, preferably 500 nm or more, more preferably 520 nm or more, and the upper limit is usually 560 nm or less, preferably 550 nm or less, and even more preferably 540 nm or less.

In addition, in the composition for a light-emitting layer of the present invention, there is no particular restriction on the absolute value of the difference in maximum emission wavelength between the compound represented by formula (1) and the compound represented by formula (2), but usually It is 0 nm or more and 20 nm or less, preferably 0 nm or more and 10 nm or less, and more preferably 0 nm or more and 5 nm or less.

The method for measuring the maximum emission wavelength exhibited by the compound represented by formula (1) and the compound represented by formula (2) is as described above in <<Method for measuring maximum emission wavelength in solution>>. In detail, it can be measured by the following measuring method.
[Measurement method: Bubbling nitrogen for 20 minutes or more into a solution in which the compound represented by formula (1) or the compound represented by formula (2) is dissolved in toluene at a concentration of 1 × 10 ^-5 mol/L at room temperature. Then, the wavelength showing the maximum value of the phosphorescence spectrum intensity obtained from the sample from which oxygen, which causes quenching, has been removed is defined as the maximum emission wavelength. ]

<<Synthesis method of iridium complex compound>>
The ligand of the iridium complex compound of the present invention can be prepared by a Miyaura-Ishiyama boronation reaction or a Hartwig-Miyaura C-H boronation reaction using a building block such as a halogenated fluorene or 2-bromo-5-iodopyridine. After converting into acid esters, a skeleton can be constructed by a Suzuki-Miyaura coupling reaction between these intermediates and an aryl halide. By combining other known methods, it is possible to synthesize ligands into which various substituents have been introduced.

Regarding the synthesis method of the iridium complex compound, a method via a chlorine-bridged iridium dinuclear complex as shown in the following formula [A] (using a phenylpyridine ligand as an example for ease of understanding) (M.G. Colombo, T.C. Brunold, T. Riedener, H.U. Gudel, Inorg. A method of obtaining the target product after exchange and conversion to a mononuclear complex (S. Lamansky, P. Djurovich, D. Murphy, F. Abdel-Razzaq, R. Kwong, I. Tsyba, M. Borz, B. Mui, R Bau, M. Thompson, Inorg. Chem., 2001, 40, 1704-1711). Furthermore, a method for directly obtaining homo-tris cyclometalated iridium complexes by reacting the ligand with a tris(acetylacetonatoiridium(III)) complex in glycerol at high temperature (K. Dedeian, P. I. Djurovich, F. O. Garces, G. Carlson, R. J. Watts, Inorg. Chem., 1991, 30, 1685-1687), but are not limited to these.

For example, the typical reaction conditions represented by the following formula [A] are as follows. In the first step, a chlorine-bridged iridium dinuclear complex is synthesized by a reaction between two equivalents of the ligand and one equivalent of iridium chloride n-hydrate. As the solvent, a mixed solvent of 2-ethoxyethanol and water is usually used, but no solvent or other solvents may be used. The reaction can also be promoted by using an excess amount of the ligand or by using an additive such as a base. Other bridging anionic ligands such as bromine can also be used in place of chlorine.

There is no particular restriction on the reaction temperature, but it is usually preferably 0°C or higher, more preferably 50°C or higher. Further, the temperature is preferably 250°C or lower, more preferably 150°C or lower. Within these ranges, only the desired reaction proceeds without by-products or decomposition reactions, and high selectivity tends to be obtained.

In the second step, the desired complex is obtained by adding a halogen ion scavenger such as silver trifluoromethanesulfonate and bringing it into contact with the newly added ligand. Ethoxyethanol or diglyme is usually used as the solvent, but depending on the type of the ligand, no solvent or other solvents can be used, and a mixture of a plurality of solvents can also be used. Although the reaction may proceed without adding a halogen ion scavenger, it is not always necessary, but in order to increase the reaction yield and selectively synthesize a facial isomer with a higher quantum yield, the scavenger may be used. The addition of is advantageous. There is no particular restriction on the reaction temperature, but it is usually carried out within the range of 0°C to 250°C.

In addition, typical reaction conditions represented by the following formula [B] will be explained. The first stage dinuclear complex can be synthesized in the same manner as in formula [A]. In the second step, one equivalent or more of a 1,3-dione compound such as acetylacetone is added to the dinuclear complex, and one equivalent of a basic compound capable of extracting active hydrogen from the 1,3-dione compound such as sodium carbonate is added to the dinuclear complex. By reacting an equivalent amount or more, it is converted into a mononuclear complex coordinated with a 1,3-dionato ligand. Usually, a solvent such as ethoxyethanol or dichloromethane that can dissolve the raw material dinuclear complex is used, but if the ligand is liquid, it is also possible to carry out the reaction without a solvent. There is no particular restriction on the reaction temperature, but it is usually carried out within the range of 0°C to 200°C.

In the third step, one equivalent or more of the ligand is reacted. The type and amount of the solvent are not particularly limited, and if the ligand is liquid at the reaction temperature, no solvent may be used. There is no particular restriction on the reaction temperature, but since the reactivity is somewhat poor, the reaction is often carried out at a relatively high temperature of 100°C to 300°C. Therefore, a high boiling point solvent such as glycerin is preferably used.

After the final reaction, purification is performed to remove unreacted raw materials, reaction by-products, and solvents. Although purification operations in ordinary organic synthetic chemistry can be applied, purification is mainly performed by normal phase silica gel column chromatography as described in the above-mentioned non-patent literature. As the developing solution, a single solution or a mixture of hexane, heptane, dichloromethane, chloroform, ethyl acetate, toluene, methyl ethyl ketone, and methanol can be used. Purification may be performed multiple times under different conditions. Other chromatography techniques (reversed-phase silica gel chromatography, size exclusion chromatography, paper chromatography) and purification operations such as separation washing, reprecipitation, recrystallization, powder suspension washing, and vacuum drying are performed as necessary. It can be applied by

<Content of iridium complex compound>
The content of the iridium complex compound in the composition for a light emitting layer of the present invention is determined based on the weight of the entire composition for a light emitting layer, the amount of the compound represented by the formula (1) contained in the composition for a light emitting layer, and the amount of the compound represented by the formula (2) contained in the composition for a light emitting layer. ) is usually 0.001% by mass or more, preferably 0.01% by mass or more, and usually 99.9% by mass or less, preferably 99% by mass or less. By setting the content of the iridium complex compound in the composition for the light emitting layer within this range, holes and electrons can be efficiently injected from adjacent layers (for example, hole transport layer and hole blocking layer) to the light emitting layer. is performed, and the driving voltage can be reduced.

<Ratio of the compound represented by formula (1) and the compound represented by formula (2) in the composition for light emitting layer>
The mixing ratio of the compound represented by formula (1) and the compound represented by formula (2) in the composition for a light-emitting layer of the present invention is not particularly limited, and the optimum ratio for the device configuration to be used is determined through experiments. However, usually, the ratio of the mass of the compound represented by the formula (1) to the total mass of the compound represented by the formula (1) and the compound represented by the formula (2) is expressed as mass%. When expressed as, it is usually 1% or more, preferably 5% or more, more preferably 10% or more, even more preferably 20% or more, and usually 99% or less, preferably 95% or less, more preferably 90% or less, and Preferably it is 80% or less.
From the viewpoint of increasing dispersibility in the light emitting layer, the ratio of the mass of the compound represented by formula (1) to the total mass of the compound represented by formula (1) and the compound represented by formula (2) is: Particularly preferably, it is 10% or more and 80% or less, and most preferably 25% or more and 75% or less.

When the composition for a light emitting layer of the present invention is used for an organic electroluminescent device, for example, it may contain a charge transporting compound used in the organic electroluminescent device, especially the light emitting layer, in addition to the above-mentioned iridium complex compound and solvent. I can do it.
When forming a light emitting layer of an organic electroluminescent device using the composition for a light emitting layer of the present invention, the iridium complex compound of the present invention is used as a light emitting material, and other charge transporting compounds are included as a charge transporting host material. It is preferable.

As other charge transporting compounds that may be contained in the composition for a light-emitting layer of the present invention, those conventionally used as materials for organic electroluminescent devices can be used. For example, pyridine, carbazole, naphthalene, perylene, pyrene, anthracene, chrysene, naphthacene, phenanthrene, coronene, fluoranthene, benzophenanthrene, fluorene, acetonaphthofluoranthene, coumarin, p-bis(2-phenylethenyl)benzene, and the like. derivatives, quinacridone derivatives, DCM (4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran) compounds, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, azabenzothioxanthene, aryl Examples include fused aromatic ring compounds substituted with an amino group and styryl derivatives substituted with an arylamino group.

One type of these may be used alone, or two or more types may be used in any combination and ratio.

Further, the content of other charge transporting compounds in the composition for a light emitting layer is usually 1000 parts by mass or less, preferably 100 parts by mass, per 1 part by mass of the iridium complex compound of the present invention in the composition for a light emitting layer. parts, more preferably 50 parts by weight or less, usually 0.01 parts by weight or more, preferably 0.1 parts by weight or more, still more preferably 1 part by weight or more.

<<Ink for light-emitting layer of the present invention>>
The composition for a light emitting layer of the present invention can be used as an ink for a light emitting layer (hereinafter sometimes referred to as an ink for a light emitting layer containing an iridium complex compound) by further containing an organic solvent.
The iridium complex compound-containing ink for a light-emitting layer of the present invention can be suitably used for manufacturing a coating-type organic EL element. In particular, it can be very suitably used as a material for a light emitting layer of a green element used in an organic EL display.

The ink for a light-emitting layer containing the iridium complex compound of the present invention and an organic solvent is an ink containing the two types of iridium complex compounds of the present invention described above and an organic solvent. The ink for a light emitting layer containing the iridium complex compound of the present invention is usually used to form a layer or film by a wet film forming method, and is particularly preferably used to form an organic layer of an organic electroluminescent device. The organic layer is preferably a light-emitting layer, especially a green light-emitting layer. That is, the ink for a light emitting layer containing the iridium complex compound and the organic solvent of the present invention is preferably an ink for a light emitting layer for an organic electroluminescent device.

<Organic solvent>
The organic solvent contained in the ink for a luminescent layer containing an iridium complex compound of the present invention is a volatile liquid component used to form a layer containing an iridium complex compound by wet film formation.
The organic solvent is not particularly limited as long as it is an organic solvent in which the charge transporting compound described below can be well dissolved since the iridium complex compound of the present invention, which is the solute, has high solvent solubility.
Preferred organic solvents include, for example, alkanes such as n-decane, cyclohexane, ethylcyclohexane, decalin, and bicyclohexane; aromatic hydrocarbons such as toluene, xylene, mesitylene, phenylcyclohexane, and tetralin; chlorobenzene, dichlorobenzene, and trichlorobenzene; Halogenated aromatic hydrocarbons such as chlorobenzene; 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetol, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole , 2,4-dimethylanisole, diphenyl ether, and other aromatic ethers; phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, n-butyl benzoate, and other aromatic esters; cyclohexanone, cyclo Alicyclic ketones such as octanone and fenchone; Alicyclic alcohols such as cyclohexanol and cyclooctanol; Aliphatic ketones such as methyl ethyl ketone and dibutyl ketone; Aliphatic alcohols such as butanol and hexanol; ethylene glycol dimethyl ether, Examples include aliphatic ethers such as ethylene glycol diethyl ether and propylene glycol-1-monomethyl ether acetate (PGMEA).

Among these, alkanes and aromatic hydrocarbons are preferred, and phenylcyclohexane has a preferable viscosity and boiling point in a wet film forming process.

One type of these organic solvents may be used alone, or two or more types may be used in any combination and ratio.

The boiling point of the organic solvent used is usually 80°C or higher, preferably 100°C or higher, more preferably 120°C or higher, and usually 270°C or lower, preferably 250°C or lower, more preferably 230°C or lower. If it is less than this range, the organic solvent may evaporate from the light-emitting layer ink during wet film formation, resulting in a decrease in film formation stability.

The content of the organic solvent is preferably 1% by mass or more, more preferably 10% by mass or more, particularly preferably 50% by mass or more, and preferably 99.99% by mass or less in the iridium complex compound-containing light emitting layer ink. It is more preferably 99.9% by mass or less, particularly preferably 99% by mass or less. The thickness of the light-emitting layer is usually about 3 to 200 nm, but if the content of the organic solvent is below this lower limit, the viscosity of the ink for the light-emitting layer becomes too high, which may reduce film-forming workability. On the other hand, if the content of the organic solvent exceeds this upper limit, the thickness of the film obtained by removing the organic solvent after film formation cannot be increased, so film formation tends to become difficult.

The iridium complex compound-containing ink for a light-emitting layer of the present invention may further contain other compounds in addition to the above-mentioned compounds, etc., if necessary. For example, other solvents may be contained in addition to the above-mentioned solvents. Examples of such solvents include amides such as N,N-dimethylformamide and N,N-dimethylacetamide, and dimethylsulfoxide. One type of these may be used alone, or two or more types may be used in any combination and ratio.

<<Organic electroluminescent device>>
Below, an organic electroluminescent device (hereinafter sometimes referred to as "organic electroluminescent device of the present invention") using the ink for a light emitting layer of the present invention will be described.
The organic electroluminescent device of the present invention contains the iridium complex compound contained in the ink for a light emitting layer of the present invention.

The organic electroluminescent device of the present invention preferably has at least an anode, a cathode, and at least one organic layer between the anode and the cathode on a substrate, and at least one of the organic layers Contains an iridium complex compound contained in the ink for a light emitting layer of the present invention. The organic layer includes a light emitting layer.

The organic layer containing an iridium complex compound contained in the ink for a light emitting layer of the present invention is more preferably a layer formed using the ink for a light emitting layer containing an iridium complex compound of the present invention, and is formed by a wet film forming method. It is more preferable that the layer is made of aluminum. The layer formed by the wet film forming method is preferably the light emitting layer.
In the present invention, the wet film forming method refers to a film forming method, that is, a coating method such as a spin coating method, dip coating method, die coating method, bar coating method, blade coating method, roll coating method, spray coating method, capillary coating method, etc. We use wet film forming methods such as coating method, inkjet method, nozzle printing method, screen printing method, gravure printing method, flexographic printing method, etc., and dry the film formed by these methods to form a film. It refers to the method of doing something.

In one embodiment, the organic electroluminescent device of the present invention has an anode, a light-emitting layer, and a cathode in this order on a substrate, and the light-emitting layer contains a compound represented by the above formula (1) and a compound represented by the formula (2). It is preferable to include the represented compound.

FIG. 1 is a schematic cross-sectional view showing a suitable structural example of an organic electroluminescent device 10 of the present invention. In FIG. The hole transport layer, numeral 5 represents a light emitting layer, numeral 6 represents a hole blocking layer, numeral 7 represents an electron transport layer, numeral 8 represents an electron injection layer, and numeral 9 represents a cathode.

Known materials can be used for these structures, and although there are no particular limitations, typical materials and manufacturing methods for each layer are described below as an example. In addition, when citing publications, papers, etc., the relevant contents can be applied and applied as appropriate within the common sense of those skilled in the art.

<Substrate 1>
The substrate 1 serves as a support for the organic electroluminescent element, and typically includes a quartz or glass plate, a metal plate or metal foil, a plastic film or sheet, or the like. Among these, glass plates and plates made of transparent synthetic resins such as polyester, polymethacrylate, polycarbonate, and polysulfone are preferred. The substrate 1 is preferably made of a material with high gas barrier properties since the organic electroluminescent element is unlikely to be deteriorated by outside air. For this reason, especially when using a material with low gas barrier properties such as a synthetic resin substrate, it is preferable to provide a dense silicon oxide film or the like on at least one side of the substrate 1 to improve the gas barrier properties.

<Anode 2>
The anode 2 has a function of injecting holes into the layer on the light emitting layer side. The anode 2 is usually made of metal such as aluminum, gold, silver, nickel, palladium, or platinum; metal oxide such as indium and/or tin oxide; metal halide such as copper iodide; carbon black or poly(3); -Methylthiophene), polypyrrole, polyaniline, and other conductive polymers.
The anode 2 is usually formed by a dry method such as a sputtering method or a vacuum evaporation method. In addition, when forming the anode 2 using metal fine particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, conductive polymer fine powder, etc., an appropriate binder resin solution may be used. It can also be formed by dispersing it into a mixture and applying it on the substrate. In the case of a conductive polymer, the anode 2 can also be formed by directly forming a thin film on the substrate by electrolytic polymerization, or by coating the conductive polymer on the substrate (Appl. Phys. Lett., 60, p. 2711, 1992).

The anode 2 usually has a single layer structure, but may have a laminated structure as appropriate. When the anode 2 has a laminated structure, different conductive materials may be laminated on the first layer of the anode.

The thickness of the anode 2 may be determined depending on the required transparency, material, etc. When particularly high transparency is required, the thickness is preferably such that the visible light transmittance is 60% or more, and more preferably 80% or more. The thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more, and preferably 1000 nm or less, preferably 500 nm or less. On the other hand, if transparency is not required, the thickness of the anode 2 may be set arbitrarily depending on the required strength, etc. In this case, the anode 2 may have the same thickness as the substrate 1.

When forming a film on the surface of the anode 2, impurities on the anode are removed and its ionization potential is adjusted by treating it with ultraviolet rays + ozone, oxygen plasma, argon plasma, etc. before forming the film. It is preferable to improve the hole injection property.

<Hole injection layer 3>
A layer that has the function of transporting holes from the anode 2 side to the light emitting layer 5 side is usually called a hole injection transport layer or a hole transport layer. When there are two or more layers having the function of transporting holes from the anode 2 side to the light emitting layer 5 side, the layer closer to the anode 2 side may be referred to as the hole injection layer 3. It is preferable to use the hole injection layer 3 because it enhances the function of transporting holes from the anode 2 to the light emitting layer 5 side. When using the hole injection layer 3, the hole injection layer 3 is usually formed on the anode 2.

The film thickness of the hole injection layer 3 is usually 1 nm or more, preferably 5 nm or more, and usually 1000 nm or less, preferably 500 nm or less.

The method for forming the hole injection layer 3 may be a vacuum evaporation method or a wet film formation method. In terms of excellent film-forming properties, it is preferable to form the film by a wet film-forming method.

The hole injection layer 3 preferably contains a hole transporting compound, and more preferably contains a hole transporting compound and an electron accepting compound. Furthermore, it is preferable that the hole injection layer 3 contains a cation radical compound, and it is particularly preferable that the hole injection layer 3 contains a cation radical compound and a hole transporting compound.

<Hole transport compound>
The composition for forming a hole injection layer usually contains a hole transporting compound that becomes the hole injection layer 3.
Further, in the case of a wet film forming method, a solvent is usually also contained. It is preferable that the composition for forming a hole injection layer has high hole transport properties and can efficiently transport injected holes. For this reason, it is preferable that the hole mobility is high and that impurities that become traps are difficult to generate during manufacturing or use. Further, it is preferable that the material has excellent stability, low ionization potential, and high transparency to visible light. In particular, when the hole injection layer 3 is in contact with the light emitting layer 5, it is preferable to use a material that does not quench the light emitted from the light emitting layer 5 or a material that does not form an exciplex with the light emitting layer 5 and reduce luminous efficiency.

As the hole transporting compound, a compound having an ionization potential of 4.5 eV to 6.0 eV is preferable from the viewpoint of a charge injection barrier from the anode 2 to the hole injection layer 3. Examples of hole-transporting compounds include aromatic amine compounds, phthalocyanine compounds, porphyrin compounds, oligothiophene compounds, polythiophene compounds, benzylphenyl compounds, compounds in which tertiary amines are linked with fluorene groups, and hydrazone. Examples thereof include silazane-based compounds, silazane-based compounds, and quinacridone-based compounds.

Among the above-mentioned exemplary compounds, aromatic amine compounds are preferred, and aromatic tertiary amine compounds are particularly preferred, from the viewpoint of amorphousness and visible light transparency. Here, the aromatic tertiary amine compound is a compound having an aromatic tertiary amine structure, and also includes a compound having a group derived from an aromatic tertiary amine.
The type of aromatic tertiary amine compound is not particularly limited, but a polymeric compound with a weight average molecular weight of 1,000 or more and 1,000,000 or less (a polymeric compound with a series of repeating units) is preferred, since it is easy to obtain uniform light emission due to the surface smoothing effect. It is preferable to use Preferred examples of aromatic tertiary amine polymer compounds include polymer compounds having repeating units represented by the following formula (I).

(In formula (I), Ar ¹ and Ar ² each independently represent an aromatic group that may have a substituent or a heteroaromatic group that may have a substituent. Ar ³ ~Ar ⁵ each independently represents an aromatic group that may have a substituent or a heteroaromatic group that may have a substituent. Q is selected from the following linking group group. (Represents a selected linking group. Also, two groups bonded to the same N atom among Ar ¹ to Ar ⁵ may bond to each other to form a ring.)

The linking group is shown below.

(In each of the above formulas, Ar ⁶ to Ar ¹⁶ each independently represent an aromatic group that may have a substituent or a heteroaromatic group that may have a substituent. R ^a to R ^b each independently represents a hydrogen atom or an arbitrary substituent.)

The aromatic group and heteroaromatic group of Ar ¹ to Ar ¹⁶ in formula (I) include benzene ring, naphthalene ring, phenanthrene ring, Groups derived from a thiophene ring or a pyridine ring are preferred, and groups derived from a benzene ring or a naphthalene ring are more preferred.

Specific examples of the aromatic tertiary amine polymer compound having a repeating unit represented by formula (I) include those described in International Publication No. 2005/089024.

<Electron accepting compound>
The hole injection layer 3 preferably contains an electron-accepting compound because the conductivity of the hole-injection layer 3 can be improved by oxidizing the hole-transporting compound.

As the electron-accepting compound, a compound having oxidizing power and the ability to accept one electron from the above-mentioned hole-transporting compound is preferable. Specifically, a compound having an electron affinity of 4 eV or more is preferable, and a compound having an electron affinity of 4 eV or more is preferable. More preferably, the compound is 5 eV or more.

Examples of such electron-accepting compounds include triarylboron compounds, metal halides, Lewis acids, organic acids, onium salts, salts of arylamines and metal halides, and salts of arylamines and Lewis acids. Examples include one or more compounds selected from the group. Specifically, onium salts substituted with organic groups such as 4-isopropyl-4'-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate and triphenylsulfonium tetrafluoroborate (International Publication No. 2005/089024); High valence inorganic compounds such as iron (III) (Japanese Unexamined Patent Publication No. 11-251067), ammonium peroxodisulfate; cyano compounds such as tetracyanoethylene; tris(pentafluorophenyl)borane (Japanese Unexamined Patent Publication No. 2003-2003) Examples thereof include aromatic boron compounds such as No. 31365); fullerene derivatives and iodine.

<Cation radical compound>
The cation radical compound is preferably an ionic compound consisting of a cation radical, which is a chemical species obtained by removing one electron from a hole transporting compound, and a counter anion. However, when the cation radical is derived from a hole-transporting polymer compound, the cation radical has a structure in which one electron is removed from the repeating unit of the polymer compound.

The cation radical is preferably a chemical species obtained by removing one electron from the compound described above as a hole-transporting compound. A chemical species obtained by removing one electron from a compound preferable as a hole transporting compound is preferable from the viewpoint of amorphous property, visible light transmittance, heat resistance, solubility, and the like.
Here, the cation radical compound can be produced by mixing the above-described hole-transporting compound and electron-accepting compound. That is, by mixing the hole-transporting compound and the electron-accepting compound described above, electron transfer occurs from the hole-transporting compound to the electron-accepting compound, and the cation radical and counter anion of the hole-transporting compound are combined. A cationic ionic compound consisting of

Cation radical compounds derived from polymer compounds such as PEDOT/PSS (Adv. Mater., 2000, Vol. 12, p. 481) and emeraldine hydrochloride (J. Phys. Chem., 1990, Vol. 94, p. 7716) It is also produced by oxidative polymerization (dehydrogenation polymerization).
The oxidative polymerization herein refers to chemically or electrochemically oxidizing a monomer using peroxodisulfate or the like in an acidic solution. In the case of this oxidative polymerization (dehydrogenation polymerization), the monomer is oxidized to become a polymer, and a cation radical with one electron removed from the repeating unit of the polymer, which uses an anion derived from an acidic solution as a counter anion, is generated. generate.

<Formation of hole injection layer 3 by wet film formation method>
When forming the hole injection layer 3 by a wet film formation method, the material for the hole injection layer 3 is usually mixed with a soluble solvent (solvent for hole injection layer) to form a film forming composition (hole injection layer solvent). A composition for forming a hole injection layer is prepared, and this composition for forming a hole injection layer is formed into a film on a layer corresponding to the lower layer of the hole injection layer 3 (usually the anode 2) by a wet film formation method. , formed by drying. The formed film can be dried in the same manner as the drying method used in forming the light emitting layer 5 by the wet film forming method.

The concentration of the hole transporting compound in the composition for forming a hole injection layer is arbitrary as long as it does not significantly impair the effects of the present invention, but from the point of view of uniformity of the film thickness, a lower concentration is preferable. A higher value is preferable in that defects are less likely to occur in the hole injection layer 3. Specifically, it is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, and on the other hand, 70% by mass. It is preferably at most 60% by mass, more preferably at most 60% by mass, particularly preferably at most 50% by mass.

Examples of the solvent include ether solvents, ester solvents, aromatic hydrocarbon solvents, and amide solvents.

Examples of ether solvents include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA), and 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, and anisole. , phenethol, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole, and other aromatic ethers.

Examples of the ester solvent include aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate.
Examples of the aromatic hydrocarbon solvent include toluene, xylene, cyclohexylbenzene, 3-isopropylbiphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, methylnaphthalene, and the like.
Examples of the amide solvent include N,N-dimethylformamide and N,N-dimethylacetamide.
In addition to these, dimethyl sulfoxide and the like can also be used.

Formation of the hole injection layer 3 by a wet film forming method is usually performed by preparing a composition for forming the hole injection layer, and then applying it on a layer corresponding to the lower layer of the hole injection layer 3 (usually the anode 2). This is done by coating and drying. After forming the hole injection layer 3, the coating film is usually dried by heating, drying under reduced pressure, or the like.

<Formation of hole injection layer 3 by vacuum evaporation method>
When forming the hole injection layer 3 by vacuum evaporation, one or more of the constituent materials of the hole injection layer 3 (the aforementioned hole transporting compound, electron accepting compound, etc.) are usually deposited in a vacuum. Place it in a crucible installed in a container (when using two or more types of materials, usually put each in a separate crucible), evacuate the inside of the vacuum container to about 10 ^-4 Pa with a vacuum pump, and then heat the crucible. (when using two or more types of materials, each crucible is usually heated), and the materials in the crucible are evaporated while controlling the amount of evaporation (when using two or more types of materials, each crucible is usually heated). (evaporate while controlling the amount of evaporation) to form a hole injection layer 3 on the anode 2 on the substrate placed facing the crucible. In addition, when using two or more types of materials, the hole injection layer 3 can also be formed by putting a mixture of them in a crucible, heating and evaporating them.

The degree of vacuum during vapor deposition is not limited as long as it does not significantly impair the effects of the present invention, but is usually 0.1×10 ⁻⁶ Torr (0.13×10 ⁻⁴ Pa) or more, 9.0×10 ⁻⁶ Torr ( 12.0×10 ⁻⁴ Pa) or less. The deposition rate is not limited as long as it does not significantly impair the effects of the present invention, but is usually 0.1 Å/sec or more and 5.0 Å/sec or less. The film forming temperature during vapor deposition is not limited as long as it does not significantly impair the effects of the present invention, but is preferably 10°C or higher and 50°C or lower.

<Hole transport layer 4>
The hole transport layer 4 is a layer that has the function of transporting holes from the anode 2 side to the light emitting layer 5 side. Although the hole transport layer 4 is not an essential layer in the organic electroluminescent device of the present invention, it is preferable to provide this layer in terms of strengthening the function of transporting holes from the anode 2 to the light emitting layer 5. When providing the hole transport layer 4, the hole transport layer 4 is usually formed between the anode 2 and the light emitting layer 5. Further, if the hole injection layer 3 described above is present, it is formed between the hole injection layer 3 and the light emitting layer 5.

The film thickness of the hole transport layer 4 is usually 5 nm or more, preferably 10 nm or more, and on the other hand, usually 300 nm or less, preferably 100 nm or less.

The method for forming the hole transport layer 4 may be a vacuum evaporation method or a wet film formation method. In terms of excellent film-forming properties, it is preferable to form the film by a wet film-forming method.

The hole transport layer 4 usually contains a hole transport compound that becomes the hole transport layer 4. In particular, the hole transporting compound contained in the hole transporting layer 4 includes two or more tertiary compounds represented by 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl. Aromatic diamine containing an amine and having two or more condensed aromatic rings substituted with nitrogen atoms (Japanese Unexamined Patent Publication No. 5-234681), 4,4',4''-tris(1-naphthylphenylamino)tri Aromatic amine compounds having a starburst structure such as phenylamine (J. Lumin., Vol. 72-74, p. 985, 1997), aromatic amine compounds consisting of a triphenylamine tetramer (Chem. Commun., 2175, p. 1996), spiro compounds such as 2,2',7,7'-tetrakis-(diphenylamino)-9,9'-spirobifluorene (Synth. Metals, vol. 91, p. 209, 1997) , 4,4'-N,N'-dicarbazole biphenyl and other carbazole derivatives. Also, for example, polyvinylcarbazole, polyvinyltriphenylamine (Japanese Unexamined Patent Publication No. 7-53953), polyarylene ether sulfone containing tetraphenylbenzidine (Polym.Adv.Tech., vol. 7, p. 33, 1996) etc. can also be preferably used.

<Formation of hole transport layer 4 by wet film formation method>
When forming the hole transport layer 4 by a wet film forming method, normally, in the same manner as when forming the above-mentioned hole injection layer 3 by a wet film forming method, instead of the hole injection layer forming composition, It is formed using a composition for forming a hole transport layer.

When forming the hole transport layer 4 by a wet film forming method, the hole transport layer forming composition usually further contains a solvent. As the solvent used in the composition for forming a hole transport layer, the same solvent as that used in the above-mentioned composition for forming a hole injection layer can be used.
The concentration of the hole transporting compound in the composition for forming a hole transporting layer can be in the same range as the concentration of the hole transporting compound in the composition for forming a hole injection layer.
Formation of the hole transport layer 4 by a wet film formation method can be performed in the same manner as the film formation method of the hole injection layer 3 described above.

<Formation of hole transport layer 4 by vacuum evaporation method>
When forming the hole transport layer 4 by vacuum evaporation, normally, in the same manner as in the case where the hole injection layer 3 is formed by the vacuum evaporation method, a hole transport layer 4 is usually formed in place of the constituent material of the hole injection layer 3. It can be formed using the constituent material of the hole transport layer 4. The film forming conditions such as the degree of vacuum, the vapor deposition rate, and the temperature during vapor deposition can be the same as those for the vacuum vapor deposition of the hole injection layer 3.

<Light-emitting layer 5>
The light-emitting layer 5 is a layer that is excited by recombining holes injected from the anode 2 and electrons injected from the cathode 9 when an electric field is applied between a pair of electrodes, and has the function of emitting light. . The light emitting layer 5 is a layer formed between the anode 2 and the cathode 9, and when the hole injection layer 3 is provided on the anode 2, the light emitting layer 5 is a layer formed between the hole injection layer 3 and the cathode 9. When the hole transport layer 4 is formed on the anode 2, it is formed between the hole transport layer 4 and the cathode 9. This light-emitting layer may be a single layer or may include multiple layers.

The thickness of the light-emitting layer 5 is arbitrary as long as it does not significantly impair the effects of the present invention, but a thicker layer is preferable because defects are less likely to occur in the layer, and a thinner layer is preferable because it is easier to lower the driving voltage. . Therefore, the thickness of the light emitting layer 5 is preferably 3 nm or more, more preferably 5 nm or more, and on the other hand, it is usually preferably 200 nm or less, and even more preferably 100 nm or less.

The light-emitting layer 5 contains at least a material having luminescent properties (light-emitting material), and preferably contains a material having charge-transporting properties (charge-transporting material). As the light-emitting material, any light-emitting layer may contain the iridium complex compound of the present invention, and other light-emitting materials may be used as appropriate. Moreover, two or more types of iridium complex compounds of the present invention may be included. Hereinafter, luminescent materials other than the iridium complex compound of the present invention will be described in detail.

<Light-emitting material>
The luminescent material is not particularly limited as long as it emits light at a desired emission wavelength and does not impair the effects of the present invention, and any known luminescent material can be used. The luminescent material may be a fluorescent material or a phosphorescent material, but a material with good luminous efficiency is preferable, and a phosphorescent material is preferable from the viewpoint of internal quantum yield.

Examples of the fluorescent material include the following materials.
Examples of fluorescent materials that emit blue light (blue fluorescent materials) include naphthalene, perylene, pyrene, anthracene, coumarin, chrysene, p-bis(2-phenylethenyl)benzene, and derivatives thereof.
Examples of fluorescent materials that emit green light (green fluorescent materials) include quinacridone derivatives, coumarin derivatives, and aluminum complexes such as Al(C ₉ H ₆ NO) ₃ .
Examples of the fluorescent material that emits yellow light (yellow fluorescent material) include rubrene, perimidone derivatives, and the like.
Examples of fluorescent materials that emit red light (red fluorescent materials) include DCM (4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran)-based compounds, benzopyran derivatives, and rhodamine derivatives. , benzothioxanthene derivatives, azabenzothioxanthene, and the like.

In addition, phosphorescent materials include, for example, items 7 to 11 of the long period periodic table (hereinafter, unless otherwise specified, the term "periodic table" refers to the long period periodic table). Examples include organometallic complexes containing metals selected from the group consisting of: Preferred examples of the metal selected from Groups 7 to 11 of the periodic table include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold.

As the ligand of the organometallic complex, a ligand in which a (hetero)aryl group and pyridine, pyrazole, phenanthroline, etc. are linked, such as a (hetero)arylpyridine ligand and a (hetero)arylpyrazole ligand, is preferable. Particularly preferred are phenylpyridine ligands and phenylpyrazole ligands. Here, (hetero)aryl represents an aryl group or a heteroaryl group.

Preferred phosphorescent materials include, for example, tris(2-phenylpyridine)iridium, tris(2-phenylpyridine)ruthenium, tris(2-phenylpyridine)palladium, bis(2-phenylpyridine)platinum, and tris(2-phenylpyridine)platinum. Examples include phenylpyridine complexes such as (2-phenylpyridine)osmium and tris(2-phenylpyridine)rhenium, and porphyrin complexes such as octaethylplatinum porphyrin, octaphenylplatinum porphyrin, octaethylpalladium porphyrin, and octaphenylpalladium porphyrin.

<Charge transport material>
The charge transporting material is a material having a property of transporting positive charges (holes) or negative charges (electrons), and is not particularly limited as long as it does not impair the effects of the present invention, and known materials can be used.
As the charge transporting material, compounds conventionally used in the light-emitting layer 5 of organic electroluminescent devices can be used, and compounds used as the host material of the light-emitting layer 5 are particularly preferred.

Specific examples of the charge transporting material include aromatic amine compounds, phthalocyanine compounds, porphyrin compounds, oligothiophene compounds, polythiophene compounds, benzylphenyl compounds, and compounds in which tertiary amines are linked with fluorene groups. , hydrazone compounds, silazane compounds, silanamine compounds, phosphamine compounds, quinacridone compounds, and other compounds exemplified as hole transporting compounds for the hole injection layer 3, as well as anthracene compounds and pyrene compounds. , carbazole-based compounds, pyridine-based compounds, phenanthroline-based compounds, oxadiazole-based compounds, silole-based compounds, and other electron-transporting compounds.

Also, for example, two or more fused aromatic rings containing two or more tertiary amines represented by 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl are attached to the nitrogen atom. Substituted aromatic diamines (Japanese Unexamined Patent Publication No. 5-234681), aromatic amine compounds having a starburst structure such as 4,4',4''-tris(1-naphthylphenylamino)triphenylamine ( J. Lumin., Vol. 72-74, p. 985, 1997), Aromatic amine compounds consisting of triphenylamine tetramers (Chem. Commun., p. 2175, 1996), 2, 2', 7 , 7'-tetrakis-(diphenylamino)-9,9'-spirobifluorene (Synth. Metals, vol. 91, p. 209, 1997), 4,4'-N,N'-di Compounds exemplified as hole-transporting compounds for the hole-transporting layer 4, such as carbazole-based compounds such as carbazole biphenyl, can also be preferably used. In addition, 2-(4-biphenylyl)-5-(p-tert-butylphenyl)-1,3,4-oxadiazole (tBu-PBD), 2,5-bis(1-naphthyl)- Oxadiazole compounds such as 1,3,4-oxadiazole (BND), 2,5-bis(6'-(2',2''-bipyridyl))-1,1-dimethyl-3,4- Also included are silole compounds such as diphenylsilole (PyPySPyPy), phenanthroline compounds such as bathophenanthroline (BPhen), and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP, bathocuproine).

<Formation of light emitting layer 5 by wet film formation method>
Although the method for forming the light-emitting layer 5 may be a vacuum evaporation method or a wet film-forming method, the wet film-forming method is used in the ink for a light-emitting layer containing an iridium complex compound of the present invention.

When the light-emitting layer 5 is formed by a wet film-forming method, a light-emitting layer is usually used instead of the hole-injection layer-forming composition in the same manner as when the hole-injection layer 3 is formed by a wet film-forming method. The layer 5 is formed using a composition for forming a luminescent layer prepared by mixing the material for layer 5 with a soluble solvent (solvent for luminescent layer).

Examples of the solvent include, in addition to the ether solvents, ester solvents, aromatic hydrocarbon solvents, and amide solvents mentioned for forming the hole injection layer 3, alkane solvents, halogenated aromatic hydrocarbon solvents, Examples include aliphatic alcohol solvents, alicyclic alcohol solvents, aliphatic ketone solvents, and alicyclic ketone solvents. The solvent to be used is as exemplified as the solvent for the iridium complex compound-containing luminescent layer ink of the present invention, and specific examples of the solvent are listed below, but the solvents are limited to these as long as they do not impair the effects of the present invention. isn't it.

For example, aliphatic ether solvents such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA); 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetol, 2 - Aromatic ether solvents such as methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole, diphenyl ether; phenyl acetate, phenyl propionate, methyl benzoate, benzoic acid Aromatic ester solvents such as ethyl, propyl benzoate, n-butyl benzoate; toluene, xylene, mesitylene, cyclohexylbenzene, tetralin, 3-isopropylbiphenyl, 1,2,3,4-tetramethylbenzene, 1,4 - Aromatic hydrocarbon solvents such as diisopropylbenzene and methylnaphthalene; Amide solvents such as N,N-dimethylformamide and N,N-dimethylacetamide; Alkanes such as n-decane, cyclohexane, ethylcyclohexane, decalin, and bicyclohexane Solvents: Halogenated aromatic hydrocarbon solvents such as chlorobenzene, dichlorobenzene, and trichlorobenzene; Aliphatic alcohol solvents such as butanol and hexanol; Alicyclic alcohol solvents such as cyclohexanol and cyclooctanol; Methyl ethyl ketone and dibutyl ketone and alicyclic ketone solvents such as cyclohexanone, cyclooctanone, and fenchone. Among these, alkane solvents and aromatic hydrocarbon solvents are particularly preferred.

Furthermore, in order to obtain a more uniform film, it is preferable that the solvent evaporate from the liquid film immediately after film formation at an appropriate rate. Therefore, as mentioned above, the boiling point of the solvent used is usually 80°C or higher, preferably 100°C or higher, more preferably 120°C or higher, and usually 270°C or lower, preferably 250°C or lower, more preferably 230°C or lower. It is.

The amount of solvent to be used is arbitrary as long as it does not significantly impair the effects of the present invention, but the total content in the luminescent layer ink, that is, the iridium complex compound-containing luminescent layer ink, is such that the film forming process is difficult due to its low viscosity. A higher amount is preferable because it is easier to perform the process, and a lower amount is preferable because it is easier to form a thick film. As mentioned above, the content of the solvent is preferably 1% by mass or more, more preferably 10% by mass or more, particularly preferably 50% by mass or more, and preferably 99.99% by mass in the ink for a light emitting layer containing an iridium complex compound. % or less, more preferably 99.9% by mass or less, particularly preferably 99% by mass or less.

As a method for removing the solvent after wet film formation, heating or reduced pressure can be used. As the heating means used in the heating method, a clean oven or a hot plate is preferable because heat is applied evenly to the entire film.
The heating temperature in the heating step is arbitrary as long as it does not significantly impair the effects of the present invention, but a higher temperature is preferable in terms of shortening the drying time, and a lower temperature is preferable in terms of less damage to the material. The upper limit of the heating temperature is usually 250°C or lower, preferably 200°C or lower, and more preferably 150°C or lower. The lower limit of the heating temperature is usually 30°C or higher, preferably 50°C or higher, and more preferably 80°C or higher. Temperatures exceeding the above upper limit are undesirable because the heat resistance is higher than the heat resistance of commonly used charge transport materials or phosphorescent materials, and there is a possibility of decomposition or crystallization. If it is less than the above lower limit, it will take a long time to remove the solvent, which is not preferable. The heating time in the heating step is appropriately determined depending on the boiling point and vapor pressure of the solvent in the luminescent layer ink, the heat resistance of the material, and the heating conditions.

<Formation of light emitting layer 5 by vacuum evaporation method>
In addition to the light-emitting layer formed by the ink for a light-emitting layer containing an iridium complex compound of the present invention, other light-emitting layers can be laminated to form a plurality of light-emitting layers. At this time, a vacuum evaporation method can be used as another method for forming the light emitting layer. When forming the light-emitting layer 5 by a vacuum evaporation method, one or more of the constituent materials of the light-emitting layer 5 (the above-mentioned light-emitting materials, charge transporting compounds, etc.) are usually deposited in a crucible placed in a vacuum container. (When using two or more types of materials, each is usually placed in a separate crucible), the inside of the vacuum container is evacuated to about 10 ^-4 Pa with a vacuum pump, and the crucible is heated (when two or more types of materials are used, each is placed in a separate crucible). When using two or more materials, each crucible is usually heated), and the materials in the crucible are evaporated while controlling the amount of evaporation (when two or more materials are used, each material is usually evaporated while controlling the amount of evaporation independently). evaporation) to form a light emitting layer 5 on the hole injection layer 3 or the hole transport layer 4 placed facing the crucible. In addition, when using two or more types of materials, the light emitting layer 5 can also be formed by putting a mixture of them in a crucible, heating and evaporating them.

<Hole blocking layer 6>
A hole blocking layer 6 may be provided between the light emitting layer 5 and an electron injection layer 8, which will be described later. The hole blocking layer 6 is a layer laminated on the light emitting layer 5 so as to be in contact with the interface of the light emitting layer 5 on the cathode 9 side.

This hole blocking layer 6 has the role of blocking holes moving from the anode 2 from reaching the cathode 9, and the role of efficiently transporting electrons injected from the cathode 9 toward the light emitting layer 5. has.
The physical properties required of the material constituting the hole blocking layer 6 include high electron mobility and low hole mobility, large energy gap (difference between HOMO and LUMO), and excited triplet level (T1). One example is the high level of

Examples of materials for the hole blocking layer 6 that satisfy these conditions include bis(2-methyl-8-quinolinolato)(phenolato)aluminum and bis(2-methyl-8-quinolinolato)(triphenylsilanolate)aluminum. mixed ligand complexes such as bis(2-methyl-8-quinolato)aluminum-μ-oxo-bis-(2-methyl-8-quinolinolato)aluminum dinuclear metal complexes, distyrylbiphenyl derivatives, etc. styryl compounds (Japanese Unexamined Patent Publication No. 11-242996), triazole derivatives such as 3-(4-biphenylyl)-4-phenyl-5(4-tert-butylphenyl)-1,2,4-triazole ( (Japanese Unexamined Patent Publication No. 7-41759), phenanthroline derivatives such as bathocuproine (Japanese Unexamined Patent Publication No. 10-79297), and the like. Furthermore, a compound having at least one pyridine ring substituted at the 2, 4, and 6 positions described in International Publication No. 2005/022962 is also preferable as a material for the hole blocking layer 6.

There is no restriction on the method for forming the hole blocking layer 6, and it can be formed in the same manner as the method for forming the light emitting layer 5 described above.
The thickness of the hole blocking layer 6 is arbitrary as long as it does not significantly impair the effects of the present invention, but it is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less. be.

<Electron transport layer 7>
The electron transport layer 7 is provided between the light emitting layer 5 or the hole blocking layer 6 and the electron injection layer 8 for the purpose of further improving the current efficiency of the device.
The electron transport layer 7 is formed of a compound that can efficiently transport electrons injected from the cathode 9 toward the light emitting layer 5 between the electrodes to which an electric field is applied. The electron-transporting compound used in the electron-transporting layer 7 is one that has high electron injection efficiency from the cathode 9 or the electron-injecting layer 8, has high electron mobility, and can efficiently transport the injected electrons. It must be a compound.

Examples of electron-transporting compounds that satisfy such conditions include metal complexes such as aluminum complexes of 8-hydroxyquinoline (Japanese Patent Application Laid-Open No. 194393/1983), 10-hydroxybenzo[h ]Quinoline metal complexes, oxadiazole derivatives, distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (US patent 5645948), quinoxaline compounds (Japanese Unexamined Patent Publication No. 6-207169), phenanthroline derivatives (Japanese Unexamined Patent Publication No. 5-331459), 2-t-butyl-9,10-N,N'- Examples include dicyanoanthraquinone diimine, n-type hydrogenated amorphous silicon carbide, n-type zinc sulfide, and n-type zinc selenide.

The film thickness of the electron transport layer 7 is usually 1 nm or more, preferably 5 nm or more, and, on the other hand, usually 300 nm or less, preferably 100 nm or less.
The electron transport layer 7 is formed in the same manner as the light emitting layer 5 by being laminated on the light emitting layer 5 or the hole blocking layer 6 by a wet film formation method or a vacuum evaporation method. Usually, a vacuum evaporation method is used.

<Electron injection layer 8>
The electron injection layer 8 plays a role of efficiently injecting electrons injected from the cathode 9 into the electron transport layer 7 or the light emitting layer 5.
In order to efficiently inject electrons, the material forming the electron injection layer 8 is preferably a metal with a low work function. Examples include alkali metals such as sodium and cesium, and alkaline earth metals such as barium and calcium.
The thickness of the electron injection layer 8 is preferably 0.1 to 5 nm.

In addition, an extremely thin insulating film (film thickness of about 0.1 to 5 nm) made of LiF, MgF ₂ , Li ₂ O, Cs ₂ CO ₃ or the like is inserted as an electron injection layer 8 at the interface between the cathode 9 and the electron transport layer 7. It is also an effective method to improve the efficiency of the device (Appl. Phys. Lett., Vol. 70, p. 152, 1997; Japanese Patent Publication No. 10-74586; IEEE Trans. Electron. Devices, Vol. 44). , p. 1245, 1997; SID 04 Digest, p. 154).
Furthermore, organic electron transport materials such as nitrogen-containing heterocyclic compounds such as bathophenanthroline and metal complexes such as aluminum complexes of 8-hydroxyquinoline are doped with alkali metals such as sodium, potassium, cesium, lithium, and rubidium ( (described in Japanese Unexamined Patent Publication No. 10-270171, Japanese Unexamined Patent Publication No. 2002-100478, Japanese Unexamined Patent Application No. 2002-100482, etc.) improves electron injection and transport properties and achieves excellent film quality. This is preferable because it makes it possible to The film thickness in this case is usually 5 nm or more, preferably 10 nm or more, and usually 200 nm or less, preferably 100 nm or less.

The electron injection layer 8 is formed by laminating the light emitting layer 5 or the hole blocking layer 6 or the electron transporting layer 7 thereon by a wet film formation method or a vacuum evaporation method in the same manner as the light emitting layer 5.
The details of the wet film forming method are the same as those for the light-emitting layer 5 described above.

<Cathode 9>
The cathode 9 plays a role of injecting electrons into a layer on the side of the light emitting layer 5 (electron injection layer 8 or light emitting layer 5, etc.). As the material for the cathode 9, it is possible to use the materials used for the anode 2, but in order to efficiently inject electrons, it is preferable to use a metal with a low work function, such as tin, magnesium, etc. , indium, calcium, aluminum, silver, or alloys thereof. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy.

In terms of stability of the device, it is preferable to protect the cathode 9 made of a metal with a low work function by laminating a metal layer having a high work function and being stable against the atmosphere on the cathode 9. Examples of the metal to be laminated include metals such as aluminum, silver, copper, nickel, chromium, gold, and platinum.
The film thickness of the cathode is usually the same as that of the anode 2.

<Other constituent layers>
The above description has focused on the element having the layer structure shown in FIG. In addition to the layers in , it may have any other layers, and any layers other than the light-emitting layer 5 may be omitted.

For example, it is also effective to provide an electron blocking layer between the hole transport layer 4 and the light emitting layer 5 for the same purpose as the hole blocking layer 6. The electron blocking layer prevents electrons moving from the light-emitting layer 5 from reaching the hole-transporting layer 4, thereby increasing the probability of recombination with holes within the light-emitting layer 5 and reducing the generated excitons. It has the role of confining holes in the light emitting layer 5 and the role of efficiently transporting holes injected from the hole transport layer 4 toward the light emitting layer 5.

Characteristics required of the electron blocking layer include high hole transportability, large energy gap (difference between HOMO and LUMO), and high excited triplet level (T1).
Furthermore, when the light emitting layer 5 is formed by a wet film forming method, it is preferable to form the electron blocking layer also by a wet film forming method because device manufacturing becomes easy.
For this reason, it is preferable that the electron blocking layer also has compatibility with wet film formation, and the material used for such an electron blocking layer is a copolymer of dioctylfluorene and triphenylamine (International Publication No. 2004/084260).

Note that the structure is opposite to that shown in FIG. , anode 2 can be stacked in this order, and it is also possible to provide the organic electroluminescent element of the present invention between two substrates, at least one of which is highly transparent.
Furthermore, it is also possible to have a structure in which the layer structure shown in FIG. 1 is stacked in multiple stages (a structure in which a plurality of light emitting units are stacked). In that case, the barrier between the stages can be reduced by using V2O5, etc. as a charge generation layer instead of the interface layer between the stages (between light emitting units) (two layers if the anode is ITO and the cathode is Al). , is more preferable from the viewpoint of luminous efficiency and driving voltage.

The present invention can be applied to any type of organic electroluminescent device, such as a single device, a device arranged in an array, or a structure in which an anode and a cathode are arranged in an XY matrix.

<Display device and lighting device>
A display device (hereinafter referred to as "display device of the present invention") and a lighting device (hereinafter referred to as "lighting device of the present invention") are manufactured using the organic electroluminescent device of the present invention as described above. be able to.
There are no particular limitations on the format or structure of the display device and illumination device of the present invention, and they can be assembled using the organic electroluminescent device of the present invention according to conventional methods.
For example, the display device and the lighting device of the present invention can be manufactured using the method described in “Organic EL Display” (Ohmsha, published on August 20, 2004, written by Shizushi Tokito, Chihaya Adachi, and Hideyuki Murata). can be formed.

<<Method for manufacturing organic electroluminescent device>>
The method for manufacturing the organic electroluminescent device according to the present invention is not particularly limited, but preferably includes a step of forming a light emitting layer by a wet film forming method using a composition for a light emitting layer containing an organic solvent.
In one embodiment, a method for manufacturing an organic electroluminescent device according to the present invention is a method for manufacturing an organic electroluminescent device having an anode, a light emitting layer, and a cathode in this order on a substrate, the method comprising: It is preferable to include a step of forming the light emitting layer by a wet film forming method using the composition.

In another embodiment, a method for manufacturing an organic electroluminescent device according to the present invention is a method for manufacturing an organic electroluminescent device having an anode, a light emitting layer, and a cathode in this order on a substrate, the method comprising: It is preferable to include a step of forming the light emitting layer by a vapor deposition method using the composition.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to the following examples, and the present invention can be implemented with arbitrary changes without departing from the gist thereof.

<Measurement of maximum emission wavelength>
The iridium complex compound was dissolved in toluene (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., for spectroscopic analysis) at room temperature to prepare a 1×10 ⁻⁵ mol/L solution. This solution was placed in a quartz cell equipped with a Teflon (registered trademark) cock, and after nitrogen bubbling was performed for 20 minutes or more, the phosphorescence spectrum was measured at room temperature. The wavelength showing the maximum value of the obtained phosphorescence spectrum intensity was defined as the maximum emission wavelength.

Note that the following equipment was used to measure the emission spectrum.
Device: Hamamatsu Photonics organic EL quantum yield measurement device C9920-02
Light source: Monochrome light source L9799-01
Detector: Multi-channel detector PMA-11
Excitation light: 380nm

<Measurement of PL quantum yield>
PL quantum yield was measured as luminous efficiency. The PL quantum yield is an index indicating how efficiently light is emitted from light (energy) absorbed by a material, and was measured using the following equipment in the same manner as above.
Device: Hamamatsu Photonics organic EL quantum yield measurement device C9920-02
Light source: Monochrome light source L9799-01
Detector: Multi-channel detector PMA-11
Excitation light: 380nm

<Synthesis of iridium complex compound>
In addition, in the following synthesis examples, all reactions were carried out under a nitrogen stream. The solvent and solution used in the reaction were degassed by an appropriate method such as nitrogen bubbling.

In a 1 L eggplant flask, 3,5-dibromoanisole (25.0 g), m-terphenyl-3-boronic acid (59.9 g), tetrakis(triphenylphosphine)palladium (0) (5.2 g), 2M- Tripotassium phosphate aqueous solution (250 mL), toluene (300 mL) and ethanol (100 mL) were added, and the mixture was stirred under reflux for 8 hours in an oil bath at 105°C. After cooling to room temperature, the aqueous phase was removed and the solvent was removed under reduced pressure. The resulting residue was purified by silica gel column chromatography (dichloromethane/hexane = 1/3 to 35/65), and Intermediate 1 was obtained as white. 52.0 g of amorphous material was obtained.

Intermediate 1 (25.8 g) and dichloromethane (150 mL) were placed in a 1L eggplant flask, cooled by immersion in a dry ice/ethanol bath, and then 1M boron tribromide/dichloromethane solution (100 mL) was added from the dropping funnel for 25 minutes. It dripped. After stirring for an additional 20 minutes, the bath was removed and stirring was continued for an additional 1.5 hours at room temperature. After water (200 mL) was added and the mixture was separated and washed, it was passed through a silica gel column (dichloromethane) to obtain 26.0 g of the demethoxylated product as a white amorphous substance. Subsequently, the entire amount of the demethoxylated product, dichloromethane (200 mL), and triethylamine (7.9 mL) were placed in a 1 L eggplant flask, and while cooling in an ice water bath, trifluoromethanesulfonic anhydride (15.9 g) was added to dichloromethane ( 10 mL) solution was added dropwise over 25 minutes. After stirring at room temperature for 1 hour, a solution of sodium carbonate (2.6 g) in water (200 mL) was added for separation and washing. The oil phase was collected and dried under reduced pressure, and the resulting residue was purified by silica gel column chromatography (dichloromethane/hexane = 5/95 to 2/8) to obtain 25.4 g of Intermediate 2 as a white solid.

In a 1 L eggplant flask, 3-(2-pyridyl)phenylboronic acid pinacol ester (6.7 g), intermediate 2 (13.6 g), tetrakis(triphenylphosphine)palladium(0) (1.2 g), 2M- Tripotassium phosphate aqueous solution (25 mL), toluene (70 mL) and ethanol (30 mL) were added, and the mixture was stirred under reflux for 3.5 hours. After cooling to room temperature, the aqueous phase was removed and the solvent was removed under reduced pressure. The resulting residue was purified by silica gel column chromatography (dichloromethane/hexane = 35/65 to 6/4), and Ligand 1 was purified. 13.3g of white amorphous was obtained.

Ligand 1 (12.0 g), tris(acetylacetonato)iridium(III) (2.2 g), glycerin (14.0 g), and cyclohexylbenzene (1 mL) were placed in a 200 mL eggplant flask equipped with a Dimroth with a side tube. and immersed in an oil bath preheated to 90°C, raised the temperature of the oil bath to 210°C, then raised the temperature of the oil bath to 240°C over 2 hours, and stirred at that temperature for an additional 6.5 hours. did. After cooling to room temperature, the mixture was washed with water (50 mL) and dichloromethane (100 mL). The residue obtained by drying the oil phase under reduced pressure was purified by silica gel column chromatography (dichloromethane/hexane = 1/1) to obtain 4.1 g of D-1 as a yellow solid. The maximum emission wavelength in the toluene solution of D-1 was 516 nm, and the PLQY was 94%.

In a 1L eggplant flask, 3,5-dibromoanisole (25.3g), 3-biphenylboronic acid (39.7g), tetrakis(triphenylphosphine)palladium(0) (4.6g), 2M-tripotassium phosphate. Aqueous solution (250 mL), toluene (215 mL) and ethanol (110 mL) were added, and the mixture was stirred under reflux for 4 hours in an oil bath at 105°C. After cooling to room temperature, the aqueous phase was removed and the solvent was removed under reduced pressure. The resulting residue was purified by silica gel column chromatography (dichloromethane/hexane = 3/7 to 4/6), and Intermediate 3 was obtained as white. 38.3g of amorphous material was obtained.

Intermediate 3 (38.3 g) and dichloromethane (330 mL) were placed in a 1L eggplant flask, cooled by immersion in a dry ice/ethanol bath, and then 1M boron tribromide/dichloromethane solution (100 mL) was added from the dropping funnel for 30 minutes. It dripped. After stirring for an additional 25 minutes, the bath was removed and stirring was continued for an additional 95 minutes at room temperature. After water (200 mL) was added and the mixture was separated and washed, the oil phase was passed through magnesium sulfate (dichloromethane) to obtain 37.5 g of a crude product containing the demethoxylated product. Subsequently, the entire amount of the crude product, dichloromethane (330 mL), and triethylamine (15.0 mL) were placed in a 1 L eggplant flask, and while cooling in an ice water bath, trifluoromethanesulfonic anhydride (30.3 g) was added to dichloromethane (20 mL) from the dropping funnel. The solution was added dropwise over 30 minutes. After stirring at room temperature for 40 minutes, a solution of sodium carbonate (2.8 g) in water (200 mL) was added and washed. The oil phase was collected and dried under reduced pressure, and the resulting residue was purified by silica gel column chromatography (dichloromethane/hexane = 0/1 to 2/8) to obtain 41.8 g of Intermediate 4 as a white solid.

In a 1 L eggplant flask, intermediate 4 (41.8 g), bispinacolato diboron (24.3 g), potassium acetate (23.6 g), [Pd(dppf) ₂ Cl ₂ ]CH ₂ Cl ₂ (2.0 g) and Dimethyl sulfoxide (390 mL) was added, and the mixture was stirred in a 90°C oil bath for 4 hours. After cooling to room temperature, water (400 mL) and dichloromethane (150 mL) were added for separation and washing, and after drying over magnesium sulfate, the solvent was removed under reduced pressure and the resulting residue was subjected to silica gel column chromatography (dichloromethane/hexane/ethyl acetate= 3/7/0 to 1/1/0 to 0/9/1) to obtain Intermediate 5 (28.5 g) as a white solid.

In a 1 L eggplant flask, 3,5-dibromoanisole (6.9 g), intermediate 5 (28.5 g), tetrakis(triphenylphosphine)palladium (0) (1.2 g), 2M-tripotassium phosphate aqueous solution ( 70 mL), toluene (120 mL) and ethanol (60 mL), and the mixture was stirred under reflux for 4 hours in an oil bath at 105°C. After cooling to room temperature, the aqueous phase was removed, the solvent was removed under reduced pressure, and the resulting residue was purified by silica gel column chromatography (dichloromethane/hexane = 4/6), yielding Intermediate 6 as a white amorphous 22. I got 3g.

Intermediate 6 (22.3 g) and dichloromethane (120 mL) were placed in a 1 L eggplant flask, cooled by immersion in a dry ice/ethanol bath, and then 1M boron tribromide/dichloromethane solution (28.2 mL) was added from the dropping funnel. The mixture was added dropwise over 30 minutes. After stirring for an additional 30 minutes, the bath was removed and stirring was continued for an additional 3 hours at room temperature. After water (150 mL) was added and the mixture was separated and washed, it was passed through magnesium sulfate (dichloromethane) to obtain 21.3 g of a crude product containing the demethoxylated product. Subsequently, the entire amount of the crude product, dichloromethane (135 mL), and triethylamine (3.8 mL) were placed in a 1 L eggplant flask, and while cooling in an ice water bath, trifluoromethanesulfonic anhydride (7.5 g) was added to dichloromethane (5 mL) from the dropping funnel. The solution was added dropwise over 30 minutes. After stirring at room temperature for 30 minutes, a solution of sodium carbonate (2.6 g) in water (200 mL) was added and washed. The oil phase was collected and dried under reduced pressure, and the resulting residue was purified by silica gel column chromatography (dichloromethane/hexane = 3/7) to obtain 22.4 g of a white solid. ¹ H-NMR revealed that it was a mixture of hexane and Intermediate 7 (net weight 21.2 g).

In a 1 L eggplant flask, 3-(2-pyridyl)phenylboronic acid pinacol ester (4.3 g), a crude product containing intermediate 7 (13.3 g), and tetrakis(triphenylphosphine)palladium (0) (0.33 g ), 2M aqueous tripotassium phosphate solution (16 mL), toluene (60 mL) and ethanol (30 mL), and the mixture was stirred under reflux for 4.5 hours. After cooling to room temperature, the aqueous phase was removed and the solvent was removed under reduced pressure. The resulting residue was purified by silica gel column chromatography (dichloromethane/hexane = 4/6 to 8/2), and the ligand 2 was purified. 12.4 g of white amorphous was obtained.

Ligand 2 (11.3 g), tris(acetylacetonato)iridium(III) (1.4 g), glycerin (13.2 g), and cyclohexylbenzene (0.0 g) were placed in a 200 mL eggplant flask equipped with a Dimroth with a side tube. 25 mL) was added, the temperature of the oil bath was raised to 235°C, and the mixture was stirred for 14.5 hours. After cooling to room temperature, the mixture was washed with water (50 mL) and dichloromethane (100 mL). The residue obtained by drying the oil phase under reduced pressure was purified by silica gel column chromatography (dichloromethane/hexane = 4/6 to 1/1) to obtain 1.3 g of D-2 as a yellow solid. The maximum emission wavelength in the toluene solution of D-2 was 514 nm, and the PLQY was 91%.

In a 300 mL eggplant flask, add 3-(2-pyridyl)phenylboronic acid pinacol ester (7.9 g), 3-bromo-3'-iodo-1,1'-biphenyl (10.6 g), and tetrakis (triphenylphosphine). Palladium (0) (0.72 g), 2M aqueous tripotassium phosphate solution (35 mL), toluene (60 mL) and ethanol (30 mL) were added, and the mixture was stirred under reflux for 5 hours. After cooling to room temperature, the aqueous phase was removed and the solvent was removed under reduced pressure. The resulting residue was purified by silica gel column chromatography (dichloromethane/hexane = 1/1 to 8/2), and intermediate 8 was obtained as a brown color. 8.7 g was obtained as amorphous.

In a 1 L eggplant flask, Intermediate 8 (8.7 g), m-terphenyl-3-boronic acid (8.9 g), tetrakis(triphenylphosphine)palladium (0) (0.65 g), 2M triphosphoric acid. Potassium aqueous solution (30 mL), toluene (60 mL) and ethanol (30 mL) were added, and the mixture was stirred under reflux for 4 hours. After cooling to room temperature, the aqueous phase was removed, and the residue obtained by removing the solvent under reduced pressure was purified by silica gel column chromatography (dichloromethane/hexane = 1/1 to 1/0), and the ligand 3 was purified. 11.5 g of colorless amorphous material was obtained.

Ligand 3 (6.5 g), iridium (III) chloride n-hydrate (manufactured by Furuya Metal Co., Ltd., 2.0 g), water (20 mL) and 2 - Ethoxyethanol (60 mL) was added, and the mixture was stirred in an oil bath at 145° C. while distilling off the solvent. During the course of the reaction, 2.5 hours after the start of the reaction, the oil bath temperature was set to 150°C, 5 hours after the start of the reaction, 2-ethoxyethanol (80 mL) was added, and at the same time, the oil bath temperature was set to 155°C, and 7 hours after the start of the reaction. Diglyme (30 mL) was added. After 15 minutes, a solution of ethyldiisopropylamine (1 mL) in 2-ethoxyethanol (5 mL) was added, and after another 15 minutes, diglyme (10 mL) and 2-ethoxyethanol (20 mL) were added, and the mixture was stirred for 3 hours. Then, the oil bath temperature was further raised to 160°C and stirred for 7 hours. The volume of liquid distilled off during the reaction was 170 mL. After cooling to room temperature, the residue obtained by removal under reduced pressure was purified by silica gel column chromatography (dichloromethane/hexane/ethyl acetate = 45/45/10 to 8/0/2), and 8.4 g of yellow amorphous was obtained. Obtained. ¹ H-NMR analysis revealed that the obtained yellow amorphous contained ethyl acetate, and that the product contained 6.7 g of dinuclear complex 1.

In a 200 mL eggplant flask, put dinuclear complex 1-containing amorphous (8.4 g) obtained in the above reaction, ligand 1 (5.0 g), and diglyme (20 mL), and stir in an oil bath at 135 °C to dissolve. After that, silver (I) trifluoromethanesulfonate (1.4 g) was added, and the temperature of the oil bath was set to 140° C., and the mixture was stirred for 2 hours. Thereafter, the solvent was removed under reduced pressure and the resulting residue was purified by silica gel column chromatography (dichloromethane/hexane = 1/1) to obtain 5.2 g of ND-1 as a yellow solid. The maximum emission wavelength in a toluene solution of ND-1 was 516 nm, and the PLQY was 96%.

In a 300 mL eggplant flask, add 3-(2-pyridyl)phenylboronic acid pinacol ester (7.3 g), 3-bromo-4'-iodo-1,1'-biphenyl (9.5 g), and tetrakis (triphenylphosphine). Palladium (0) (0.62 g), 2M aqueous tripotassium phosphate solution (35 mL), toluene (50 mL) and ethanol (35 mL) were added, and the mixture was stirred under reflux for 8 hours. After cooling to room temperature, the aqueous phase was removed and the solvent was removed under reduced pressure. The resulting residue was purified by silica gel column chromatography (dichloromethane/hexane = 1/1 to 1/0), and intermediate 9 was obtained as a brown color. 10.0 g of amorphous material was obtained.

In a 1 L eggplant flask, intermediate 9 (28.7 g), bispinacolato diboron (23.7 g), potassium acetate (36.9 g), [Pd(dppf) ₂ Cl ₂ ]CH ₂ Cl ₂ (1.8 g), and Dimethyl sulfoxide (250 mL) was added, and the mixture was stirred in a 90°C oil bath for 3 hours. After cooling to room temperature, water (0.5 L) and dichloromethane (0.3 L) were added for separation and washing, and after drying over magnesium sulfate, the solvent was removed under reduced pressure and the resulting residue was subjected to silica gel column chromatography (ethyl acetate/ When purified with hexane (1/9 to 15/85), Intermediate 10 (30.1 g) was obtained as a pale yellow solid.

In a 1 L eggplant flask, intermediate 10 (30.1 g), 3-bromo-3'-iodo-1,1'-biphenyl (27.5 g), tetrakis(triphenylphosphine)palladium (0) (1.1 g) , 2M aqueous tripotassium phosphate solution (90 mL), toluene (300 mL) and ethanol (90 mL) were added, and the mixture was stirred under reflux for 4 hours. After cooling to room temperature, the aqueous phase was removed and the solvent was removed under reduced pressure. The resulting residue was purified by silica gel column chromatography (dichloromethane/hexane = 1/1 to 7/3), and Intermediate 11 was purified as a cream. 35.8 g of colored amorphous material was obtained.

In a 300 mL eggplant flask, intermediate 11 (15.3 g), m-biphenylboronic acid (7.2 g), tetrakis(triphenylphosphine) palladium (0) (1.3 g), 2M-tripotassium phosphate aqueous solution (45 mL) ), toluene (80 mL) and ethanol (45 mL) were added, and the mixture was stirred under reflux for 5 hours. After cooling to room temperature, the aqueous phase was removed and the solvent was removed under reduced pressure. The resulting residue was purified by silica gel column chromatography (dichloromethane/hexane = 1/1 to 1/0), and the ligand 4 was purified. 18.2g of white amorphous was obtained.

Ligand 4 (10.2 g), iridium (III) chloride n-hydrate (manufactured by Furuya Metal Co., Ltd., 2.76 g), water (25 mL) and 2 -Ethoxyethanol (125 mL) was added, and the mixture was stirred in an oil bath at 140° C. while distilling off the solvent. During the course of the reaction, after 2.5 hours, diglyme (40 mL) was added, and the oil bath was heated to 150°C. After an additional 2 hours, 2-ethoxyethanol (35 mL) was added and the oil bath was brought to 155°C. After another 4 hours, a solution of ethyldiisopropylamine (1.5 mL) in diglyme (2.5 mL) was added, and after another 1 hour, a solution of ethyldiisopropylamine (1.5 mL) in diglyme (2.5 mL) was added, and for another 2 hours. Stirred. The volume of liquid distilled off during the reaction was 140 mL. After cooling to room temperature, the residue obtained by removing under reduced pressure was purified by silica gel column chromatography (dichloromethane/hexane = 4/6 to 3/7) to obtain 6.7 g of dinuclear complex 2 as a bright yellow amorphous. .

Put dinuclear complex 2 (6.7 g), ligand 2 (8.0 g), and diglyme (20 mL) in a 200 mL eggplant flask, stir in an oil bath at 135°C to dissolve, and then add silver trifluoromethanesulfonate. (I) (1.21 g) was added, the temperature of the oil bath was set to 140°C, and the mixture was stirred for 1.5 hours. Thereafter, the solvent was removed under reduced pressure and the resulting residue was purified by silica gel column chromatography (dichloromethane/hexane = 1/1) to obtain 7.7 g of compound ND-2 as a yellow solid. The maximum emission wavelength in a toluene solution of ND-2 was 519 nm, and the PLQY was 94%.

[Example 1]
An organic electroluminescent device was produced by the following method.
An indium tin oxide (ITO) transparent conductive film deposited to a thickness of 50 nm on a glass substrate (manufactured by Geomatec, sputtering film) was formed into 2 mm wide stripes using normal photolithography technology and hydrochloric acid etching. The anode was formed by patterning. The substrate on which ITO was patterned was washed in the following order: ultrasonic cleaning with an aqueous surfactant solution, washing with ultrapure water, ultrasonic washing with ultrapure water, and washing with ultrapure water, and then dried with compressed air. Finally, ultraviolet ozone cleaning was performed.

As a composition for forming a hole injection layer, 3.0% by mass of a hole-transporting polymer compound having a repeating structure of the following formula (P-1) and 0.6% by mass of an electron-accepting compound (HI-1). A composition was prepared by dissolving these in ethyl benzoate.

This solution was spin-coated on the substrate in the air and dried on a hot plate in the air at 240° C. for 30 minutes to form a uniform thin film with a thickness of 40 nm, which was used as a hole injection layer.

Next, a charge transporting polymer compound having the following structural formula (HT-1) was dissolved in 1,3,5-trimethylbenzene to prepare a 2.0% by mass solution.
This solution was spin-coated on the substrate on which the hole injection layer was coated in a nitrogen glove box, and dried on a hot plate in the nitrogen glove box at 230°C for 30 minutes to form a uniform thin film with a thickness of 40 nm. and formed a hole transport layer.

Subsequently, as materials for the light emitting layer, 1.35% by mass of a compound (H-1) having the following structure, 1.35% by mass of (H-2), 2.7% by mass of (H-3), An ink for a light-emitting layer of the present invention was prepared by dissolving (Ir-D1) and (Ir-ND1) in cyclohexylbenzene at concentrations of 0.8% by mass and 0.8% by mass, respectively.

This solution was spin-coated on the substrate on which the hole transport layer was coated in a nitrogen glove box, and dried on a hot plate in the nitrogen glove box at 120°C for 20 minutes to form a uniform thin film with a thickness of 70 nm. A light-emitting layer was formed.
The substrate on which the film up to the light-emitting layer was formed was placed in a vacuum evaporation apparatus, and the inside of the apparatus was evacuated to a pressure of 2×10 ⁻⁴ Pa or less.

Next, the following structural formula (ET-1) and 8-hydroxyquinolinolatrithium were co-deposited on the light emitting layer using a vacuum evaporation method at a film thickness ratio of 2:3, and an electron transport layer with a film thickness of 30 nm was formed. was formed.

Next, a striped shadow mask with a width of 2 mm was brought into close contact with the substrate as a mask for cathode evaporation, perpendicular to the ITO stripes of the anode, and the aluminum was heated with a molybdenum boat to form an aluminum layer with a thickness of 80 nm. to form a cathode. In the manner described above, an organic electroluminescent device having a light emitting area of 2 mm x 2 mm in size was obtained.

[Example 2]
An organic electric field was prepared in the same manner as in Example 1, except that the ink for the light emitting layer of the present invention was used as the ink for the light emitting layer, and the compound (Ir-D2) having the following structure was used instead of (Ir-D1). A light emitting device was produced.

[Example 3]
An organic electric field was prepared in the same manner as in Example 1, except that the ink for the light emitting layer of the present invention was used as the ink for the light emitting layer, and the compound (Ir-ND2) having the following structure was used instead of (Ir-ND1). A light emitting device was produced.

[Example 4]
An organic electroluminescent device was produced in the same manner as in Example 2, except that the ink for the light emitting layer of the present invention was used as the ink for the light emitting layer, in which (Ir-ND2) was used instead of (Ir-ND1).

[Comparative example 1]
An organic electroluminescent device was produced in the same manner as in Example 1, except that (Ir-D2) was used instead of (Ir-ND1) as the light-emitting layer ink.

[Comparative example 2]
An organic electroluminescent device was produced in the same manner as in Example 1, except that (Ir-ND2) was used instead of (Ir-D1) as the emissive layer ink.

[Comparative example 3]
Instead of using 0.8% by mass of (Ir-D1) and 0.8% by mass of (Ir-ND1), the ink for the luminescent layer was made using 1.6% by mass of (Ir-D1). An organic electroluminescent device was produced in the same manner as in Example 1 except for using the following.

[Comparative example 4]
Instead of using 0.8% by mass of (Ir-D2) and 0.8% by mass of (Ir-ND1), 1.6% by mass of (Ir-D2) was used as the ink for the luminescent layer. An organic electroluminescent device was produced in the same manner as in Example 2 except for using the following.

[Comparative example 5]
Instead of using 0.8% by mass of (Ir-D1) and 0.8% by mass of (Ir-ND1), the ink for the luminescent layer was made using 1.6% by mass of (Ir-ND1). An organic electroluminescent device was produced in the same manner as in Example 1 except for using the following.

[Comparative example 6]
Instead of using 0.8% by mass of (Ir-D1) and 0.8% by mass of (Ir-ND2) as the ink for the luminescent layer, 1.6% by mass of (Ir-ND2) was used to create the ink for the luminescent layer. An organic electroluminescent device was produced in the same manner as in Example 3 except for using the following.

Table 1 summarizes the relative values of luminous efficiency [cd/A] at 1000 cd/m ² of the devices obtained in Examples 1 to 4 and Comparative Examples 1 to 6 (Comparative Example 6 is set as 1).

From the results in Table 1, when the compound represented by formula (1) or formula (2) is used alone, and when two types of compounds represented by formula (1) or formula (2) are used It can be seen that the luminous efficiency of the device is improved when one of each of the compounds represented by formula (1) and formula (2) is used in combination.

[Example 5]
The organic electric field was prepared in the same manner as in Example 3, except that the ink for the light emitting layer of the present invention was used as the ink for the light emitting layer, and the compound (Ir-ND3) having the following structure was used instead of (Ir-ND2). A light emitting device was produced. Note that the compound (Ir-ND3) was synthesized with reference to the method described in Japanese Patent Application Publication No. 2014-074000.

[Comparative Example 7]
An organic electroluminescent device was prepared in the same manner as in Example 3, except that a compound (Ir-ND4) having the following structure was used instead of (Ir-ND2) as the ink for the luminescent layer. Created.

Table 2 summarizes the relative values of luminous efficiency [cd/A] at 1000 cd/m ² of the devices obtained in Examples 3 and 5 and Comparative Example 7 (Comparative Example 7 is set as 1).

From the results in Table 2, it can be seen that the compound (Ir-D1) and the compound (1 ) The organic electroluminescent device produced using the luminescent layer ink of the present invention in combination with (Ir-ND2) or (Ir-ND3) exhibits higher luminous efficiency. Recognize.

[Example 6]
An organic electric field was prepared in the same manner as in Example 3, except that the ink for the light emitting layer of the present invention was used as the ink for the light emitting layer, and the compound (Ir-D3) having the following structure was used instead of (Ir-D1). A light emitting device was produced. Note that the compound (Ir-D3) was synthesized with reference to the method described in Japanese Patent Application Publication No. 2014-074000 and Japanese Patent Application Publication No. 2012-036388.

[Example 7]
An organic electroluminescent device was produced in the same manner as in Example 6, except that the ink for the light emitting layer of the present invention was used as the ink for the light emitting layer, in which (Ir-ND3) was used instead of (Ir-ND2).

[Example 8]
An organic electroluminescent device was prepared in the same manner as in Example 6, except that a light-emitting layer ink containing a compound (Ir-ND5) having the following structure instead of (Ir-ND2) was used as the light-emitting layer ink. Created. Note that the compound (Ir-ND5) was synthesized with reference to the method described in Japanese Patent Application Publication No. 2014-074000.

[Comparative example 8]
An organic electroluminescent device was produced in the same manner as in Example 6, except that (Ir-ND4) was used instead of (Ir-ND2) as the light-emitting layer ink.

Table 3 summarizes the relative values of luminous efficiency [cd/A] at 1000 cd/m ² of the devices obtained in Examples 6 to 8 and Comparative Example 8 (Comparative Example 8 is set as 1).

From the results in Table 3, compared to the emissive layer ink which is a combination of the compound (Ir-D3) represented by formula (2) and the compound (Ir-ND4), the combination of compound (Ir-D3) and formula (1) The organic electroluminescent device produced using the ink for a light-emitting layer of the present invention, which is a combination of the compound (Ir-ND2), the compound (Ir-ND3), or the compound (Ir-ND5), which is a compound represented by It can be seen that it exhibits high luminous efficiency.

[Comparative Example 9]
31.5 mg of [Ir(ppy) ₃ ] was placed in a glass vial, and cyclohexylbenzene was added to make the total content 3935 mg (0.8% by mass). Even after shaking for 5 minutes at room temperature (22°C), it did not completely melt, so it was heated at 100°C for 30 minutes, but it did not completely melt. Further, 8.00 g of cyclohexylbenzene was added and heated again at 100° C. for 30 minutes, but it did not completely dissolve. It was found that [Ir(ppy) ₃ ] is significantly lacking in solvent solubility compared to the iridium complex compound used in the present invention.

Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that those skilled in the art can come up with various changes or modifications within the scope of the claims, and these naturally fall within the technical scope of the present invention. Understood. Further, each of the constituent elements in the above embodiments may be arbitrarily combined without departing from the spirit of the invention.

Note that this application is based on a Japanese patent application (Japanese Patent Application No. 2022-050596) filed on March 25, 2022, the contents of which are incorporated as a reference in this application.

The ink for a light emitting layer of the present invention can provide an organic electroluminescent device with further improved luminous efficiency.

1 Substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Hole blocking layer 7 Electron transport layer 8 Electron injection layer 9 Cathode 10 Organic electroluminescent element

Claims

A composition for a light-emitting layer, comprising a compound represented by formula (1) and a compound represented by formula (2).

[However, n represents an integer from 0 to 10. R represents a substituent, and a represents a number from 0 to the maximum integer that can be substituted by one ligand. The types of R are independently D, F, Cl, Br, I, -N(R') 2 , -CN, -NO 2 , -OH, -COOR', -C(=O)R', - C(=O)NR', -P(=O)(R') 2 , -S(=O)R', -S(=O) 2 R', -OS(=O) 2 R', carbon A straight chain, branched or cyclic alkyl group having 1 to 5 carbon atoms, a straight chain or branched alkoxy group having 1 to 4 carbon atoms, a straight chain, branched or cyclic alkylthio group having 1 to 4 carbon atoms, a carbon number Straight chain, branched or cyclic alkenyl group with 2 to 4 carbon atoms, straight chain, branched or cyclic alkynyl group with 2 to 4 carbon atoms, diarylamino group with 10 to 40 carbon atoms, 10 to 40 carbon atoms An arylheteroarylamino group or a diheteroarylamino group having 10 to 40 carbon atoms, the alkyl group, the alkoxy group, the alkylthio group, the alkenyl group, the alkynyl group, the diarylamino group, the arylheteroaryl group. The amino group and the diheteroarylamino group may be substituted with one or more R' other than hydrogen atoms.
R' each independently represents D, F, -CN, a straight chain, branched or cyclic alkyl group having 1 to 5 carbon atoms, a straight chain or branched alkenyl group having 2 to 4 carbon atoms, and 2 or more carbon atoms. It is a straight chain or branched alkynyl group of up to 4. ]

[However, m represents an integer from 0 to 10. Q represents a substituent, and b represents from 0 to the maximum integer that can be substituted by one ligand. X represents formula (3) or (4).

[However, the broken line represents a bond with the benzene ring, each Ar 1 independently represents a trivalent aromatic hydrocarbon group having 6 to 30 carbon atoms or a trivalent heteroaromatic group having 2 to 30 carbon atoms, and Ar Each of 2 independently represents a monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms or a monovalent heteroaromatic group having 2 to 30 carbon atoms. Ar 1 and Ar 2 in formulas (3) and (4) may be substituted with Q. ]]
The composition for a light-emitting layer according to claim 1, wherein formula (1) is represented by the following formula (5).

[R and a are as defined in claim 1. n 1 and n 2 represent numbers such that n 1 +n 2 =n. ]
In formula (3) or (4), Ar 1 each independently represents a trivalent aromatic hydrocarbon group having 6 to 30 carbon atoms, and Ar 2 each independently represents a monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms. The composition for a light-emitting layer according to claim 1 or 2, which represents a hydrocarbon group.
The composition for a light-emitting layer according to any one of claims 1 to 3, wherein X in formula (2) is represented by formula (3).
Claims 1 to 3, wherein the absolute value of the difference in maximum emission wavelength between the compound represented by formula (1) and the compound represented by formula (2), measured by the following measuring method, is 0 nm or more and 20 nm or less. 4. The composition for a light-emitting layer according to any one of 4.
[Measurement method: Bubbling nitrogen for 20 minutes or more into a solution in which the compound represented by formula (1) or the compound represented by formula (2) is dissolved in toluene at a concentration of 1 × 10 -5 mol/L at room temperature. Then, the wavelength showing the maximum value of the phosphorescence spectrum intensity obtained from the sample from which oxygen, which causes quenching, has been removed is defined as the maximum emission wavelength. ]
Claim 1, wherein the mass ratio of the compound represented by formula (1) to the total mass of the compound represented by formula (1) and the compound represented by formula (2) is 10% or more and 80% or less. The composition for a light-emitting layer according to any one of items 1 to 5.
The composition for a light-emitting layer according to any one of claims 1 to 6, further comprising an organic solvent.
A method for manufacturing an organic electroluminescent device having an anode, a light emitting layer, and a cathode in this order on a substrate, the method comprising:
A method for manufacturing an organic electroluminescent device, comprising the step of forming the light emitting layer by a wet film forming method using the composition for a light emitting layer according to claim 7.
An organic electroluminescent device having an anode, a light emitting layer, and a cathode in this order on a substrate,
An organic electroluminescent device comprising a compound represented by formula (1) and a compound represented by formula (2) in a light emitting layer.

[However, n represents an integer from 0 to 10. R represents a substituent, and a represents a number from 0 to the maximum integer that can be substituted by one ligand. The types of R are independently D, F, Cl, Br, I, -N(R') 2 , -CN, -NO 2 , -OH, -COOR', -C(=O)R', - C(=O)NR', -P(=O)(R') 2 , -S(=O)R', -S(=O) 2 R', -OS(=O) 2 R', carbon A straight chain, branched or cyclic alkyl group having 1 to 5 carbon atoms, a straight chain or branched alkoxy group having 1 to 4 carbon atoms, a straight chain, branched or cyclic alkylthio group having 1 to 4 carbon atoms, a carbon number Straight chain, branched or cyclic alkenyl group with 2 to 4 carbon atoms, straight chain, branched or cyclic alkynyl group with 2 to 4 carbon atoms, diarylamino group with 10 to 40 carbon atoms, 10 to 40 carbon atoms An arylheteroarylamino group or a diheteroarylamino group having 10 to 40 carbon atoms, the alkyl group, the alkoxy group, the alkylthio group, the alkenyl group, the alkynyl group, the diarylamino group, the arylheteroaryl group. The amino group and the diheteroarylamino group may be substituted with one or more R' other than hydrogen atoms.
R' each independently represents D, F, -CN, a straight chain, branched or cyclic alkyl group having 1 to 5 carbon atoms, a straight chain or branched alkenyl group having 2 to 4 carbon atoms, and 2 or more carbon atoms. It is a straight chain or branched alkynyl group of up to 4. ]

[However, m represents an integer from 0 to 10. Q represents a substituent, and b represents from 0 to the maximum integer that can be substituted by one ligand. X represents formula (3) or (4).

[However, the broken line represents a bond with the benzene ring, each Ar 1 independently represents a trivalent aromatic hydrocarbon group having 6 to 30 carbon atoms or a trivalent heteroaromatic group having 2 to 30 carbon atoms, and Ar Each of 2 independently represents a monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms or a monovalent heteroaromatic group having 2 to 30 carbon atoms. Ar 1 and Ar 2 in formulas (3) and (4) may be substituted with Q. ]]