TW202346311A - Light-emitting layer composition, organic electroluminescent element, and production method therefor - Google Patents

Abstract

An object of the present invention is to provide a composition for a light-emitting layer that can further improve the luminous efficiency of an element, and a composition for the light-emitting layer (for example, an ink for a light-emitting layer) that further contains an organic solvent. The present invention relates to a composition for a light-emitting layer, including a compound represented by formula (1) and a compound represented by formula (2). (n, R, and a in formula (1), and m, Q, b, and X in formula (2) are as described in the specification)

Description

Composition for light-emitting layer, organic electroluminescent element, and method for manufacturing organic electroluminescent element

The present invention relates to a composition for a light-emitting layer containing two or more iridium complex compounds, and in particular to an organic electroluminescent element that can be effectively used to form a light-emitting layer by coating (hereinafter, A composition for a light-emitting layer containing an ink containing two or more iridium complex compounds, and a composition for a light-emitting layer further containing an organic solvent (hereinafter sometimes referred to as an "organic EL element") layer of ink").

Various electronic devices using organic EL elements, such as organic electroluminescence (EL) lighting and organic EL displays, are being put into practical use. Organic electroluminescent elements consume less power due to low applied voltage and can emit light in three primary colors. Therefore, they are not only used in large display monitors, but are also beginning to be used in small and medium-sized displays such as mobile phones and smart phones.

Organic electroluminescent elements are manufactured by laminating multiple layers such as a light-emitting layer, a charge injection layer, and a charge transport layer. At present, most organic electroluminescent devices are manufactured by evaporating organic materials under vacuum. However, the evaporation process of the vacuum evaporation method is complicated and the productivity is poor. In addition, in organic electroluminescent devices manufactured by the vacuum evaporation method, , there is a problem that it is extremely difficult to achieve large-scale or high-definition lighting or display panels. Therefore, in recent years, wet film formation methods (coating methods) have been actively studied as a process for efficiently manufacturing organic electroluminescent elements that can be used for large-scale displays or lighting. The wet film formation method has the advantage of being able to easily form a stable layer compared to the vacuum evaporation method. Therefore, the wet film formation method is expected to be used in mass production or large-scale devices of displays and lighting devices.

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

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

As another powerful technique, the use of a combination of different phosphorescent materials is being studied. For example, Patent Document 1 discloses that a plurality of phosphorescent materials are placed in a boat of a vapor deposition machine to lower the vapor deposition temperature, thereby suppressing decomposition and improving the dispersion of the vapor deposition film. Therefore, As a result, the characteristics of the element are improved. Patent Document 2 also discloses improving device characteristics by combining two iridium complex compounds in a vapor-deposited device. Patent Document 3 discloses that when two iridium complexes having a dendritic polymer type structure and different generation numbers are used to produce an organic EL element by a coating method, it is different from using a single dendritic complex. The luminous efficiency is higher than that of polymer complex elements. [Prior art documents] [Patent Document]

Patent Document 1: International Publication No. 2002/104080 Patent Document 2: Japanese Patent Application Publication No. 2003-077674 Patent Document 3: International Publication No. 2004/020504

[Problem to be solved by the invention]

The methods disclosed in Patent Document 1 and Patent Document 2 are based on the vapor deposition method. In the coating method, compared with the vapor deposition method, the temperature applied to the material is lower, and no iridium ions are generated during the vapor deposition. The thermal decomposition and deterioration of compound compounds leads to the degradation of device characteristics. Furthermore, the iridium complex compounds disclosed in these have low solvent solubility and cannot be used as materials for organic EL devices based on coating methods. Patent Document 3 discloses a method of manufacturing a device by a coating method. However, when this method was tried and applied, it was found that the use of two dendrimer-type complexes with different generation numbers sometimes showed worse results than the case of using a single dendrimer-type complex. Low luminous efficiency. An object of the present invention is to provide a composition for a light-emitting layer that can further improve the luminous efficiency of an element, and a composition for the light-emitting layer (for example, an ink for a light-emitting layer) that further contains an organic solvent. [Means to solve the problem]

The inventors of the present invention have conducted diligent research to solve the above-mentioned problems, and have found that a composition for a light-emitting layer containing two or more different iridium complex compounds having a specific chemical structure can help improve organic EL elements, especially green light emission. The luminous efficiency of the element was determined to complete the present invention.

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

[Chemical 1]

[Wherein, n represents an integer from 0 to 10; R represents a substituent, a represents 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', linear alkyl group, branched alkyl group or cyclic alkyl group with 1 to 5 carbon atoms, Linear alkoxy group, branched alkoxy group having 1 to 4 carbon atoms, linear alkylthio group, branched alkylthio group or cyclic alkylthio group having 1 to 4 carbon atoms, 2 to 4 carbon atoms The following linear alkenyl group, branched alkenyl group or cyclic alkenyl group, linear alkynyl group, branched alkynyl group or cyclic alkynyl group having 2 to 4 carbon atoms, diarylamine having 10 to 40 carbon atoms group, an arylheteroarylamine group with a carbon number of 10 or more and 40 or less, or a diheteroarylamino group with a carbon number of 10 or more and 40 or less, the alkyl group, the alkoxy group, the alkylthio group, The alkenyl group, the alkynyl group, the diarylamine group, the arylheteroarylamine group and the diarylamine group may be substituted by R' other than one or more hydrogen atoms; R 'are independently D, F, -CN, linear alkyl group, branched alkyl group or cyclic alkyl group having 1 to 5 carbon atoms, linear alkenyl group or branched alkenyl group with 2 to 4 carbon atoms , straight chain alkynyl group or branched alkynyl group with a carbon number of 2 or more and 4 or less]

[Chemicalization 2]

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

[Chemical 3]

[Wherein, the dotted line represents the bond with the benzene ring, Ar ¹ each independently represents a trivalent aromatic hydrocarbon group with 6 to 30 carbon atoms or a trivalent heteroaromatic group with 2 to 30 carbon atoms, and Ar ² each independently represents the carbon number A monovalent aromatic hydrocarbon group with 6 to 30 carbon atoms or a monovalent heteroaromatic group with 2 to 30 carbon atoms; Ar ¹ and Ar ² in formula (3) and formula (4) may be substituted by the Q mentioned above]]

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

[Chemical 4]

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

[3] The composition for a light-emitting layer according to [1] or [2], wherein in the formula (3) or the formula (4), Ar ¹ each independently represents a trivalent aromatic having 6 to 30 carbon atoms. The hydrocarbon group and Ar ² each independently represent a monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms. [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 composition for a light-emitting layer according to any one of [1] to [4], wherein the compound represented by formula (1) measured by the following measurement method is the same as the compound represented by formula (2) The absolute value of the difference in maximum emission wavelengths shown by the compounds is 0 nm or more and 20 nm or less. [Measurement method: A solution obtained by dissolving a compound represented by formula (1) or a compound represented by formula (2) in toluene at a concentration of 1×10 ^-5 mol/L at room temperature is bubbled with nitrogen for 20 minutes or more, obtain a sample from which oxygen that causes extinction has been removed, and the wavelength showing the maximum value of the phosphorescence spectrum intensity obtained from the sample is regarded as the maximum emission wavelength] [6] As any one of [1] to [5] The composition for a light-emitting layer according to the item above, wherein the mass ratio of the compound represented by the formula (1) to the total mass of the compound represented by the formula (2) is 10%. Above and below 80%. [7] The composition for a light-emitting layer according to any one of [1] to [6], further containing an organic solvent. [8] A method of manufacturing an organic electroluminescent element. The organic electroluminescent element has an anode, a luminescent layer and a cathode in sequence on a substrate. The method of manufacturing an organic electroluminescent element includes: using [7] The composition for the light-emitting layer is used and the step of forming the light-emitting layer by a wet film forming method.

[9] An organic electroluminescent element, which has an anode, a luminescent layer and a cathode in sequence on a substrate. In the organic electroluminescent element, The light-emitting layer contains the compound represented by formula (1) and the compound represented by formula (2).

[Chemistry 5]

[Wherein, n represents an integer from 0 to 10; R represents a substituent, a represents 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', linear alkyl group, branched alkyl group or cyclic alkyl group with 1 to 5 carbon atoms, Linear alkoxy group, branched alkoxy group having 1 to 4 carbon atoms, linear alkylthio group, branched alkylthio group or cyclic alkylthio group having 1 to 4 carbon atoms, 2 to 4 carbon atoms The following linear alkenyl group, branched alkenyl group or cyclic alkenyl group, linear alkynyl group, branched alkynyl group or cyclic alkynyl group having 2 to 4 carbon atoms, diarylamine having 10 to 40 carbon atoms group, an arylheteroarylamine group with a carbon number of 10 or more and 40 or less, or a diheteroarylamino group with a carbon number of 10 or more and 40 or less, the alkyl group, the alkoxy group, the alkylthio group, The alkenyl group, the alkynyl group, the diarylamine group, the arylheteroarylamine group and the diarylamine group may be substituted by R' other than one or more hydrogen atoms; R 'are independently D, F, -CN, linear alkyl group, branched alkyl group or cyclic alkyl group having 1 to 5 carbon atoms, linear alkenyl group or branched alkenyl group with 2 to 4 carbon atoms , straight chain alkynyl group or branched alkynyl group with a carbon number of 2 or more and 4 or less]

[Chemical 6]

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

[Chemical 7]

[Wherein, the dotted line represents the bond with the benzene ring, Ar ¹ each independently represents a trivalent aromatic hydrocarbon group with 6 to 30 carbon atoms or a trivalent heteroaromatic group with 2 to 30 carbon atoms, and Ar ² each independently represents the carbon number A monovalent aromatic hydrocarbon group with 6 to 30 carbon atoms or a monovalent heteroaromatic group with 2 to 30 carbon atoms; Ar ¹ and Ar ² in formula (3) and formula (4) may be substituted by the Q]] [Effects of the Invention]

The present invention provides a composition for a light-emitting layer, which contains two or more iridium complex compounds, and can further improve the luminous efficiency when used in organic EL elements, especially the luminous efficiency in green elements.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments and can be implemented with various modifications within the scope of the spirit. In addition, in this specification, "aromatic ring" refers to "aromatic hydrocarbon ring" and is distinguished from "heteroaromatic ring" containing heteroatoms as ring constituent atoms. Similarly, the term "aromatic group" refers to an "aromatic hydrocarbon ring group", and the term "heteroaromatic group" refers to a "heteroaromatic ring group". In addition, in this specification, "solvent" and "solvent" have the same meaning.

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

[Chemical 8]

[Wherein, n represents an integer from 0 to 10; R represents a substituent, a represents 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', linear alkyl group, branched alkyl group or cyclic alkyl group with 1 to 5 carbon atoms, Linear alkoxy group, branched alkoxy group having 1 to 4 carbon atoms, linear alkylthio group, branched alkylthio group or cyclic alkylthio group having 1 to 4 carbon atoms, 2 to 4 carbon atoms The following linear alkenyl group, branched alkenyl group or cyclic alkenyl group, linear alkynyl group, branched alkynyl group or cyclic alkynyl group having 2 to 4 carbon atoms, diarylamine having 10 to 40 carbon atoms group, an arylheteroarylamine group with a carbon number of 10 or more and 40 or less, or a diheteroarylamino group with a carbon number of 10 or more and 40 or less, the alkyl group, the alkoxy group, the alkylthio group, The alkenyl group, the alkynyl group, the diarylamine group, the arylheteroarylamine group and the diarylamine group may be substituted by R' other than one or more hydrogen atoms;

R' is each independently D, F, -CN, a linear alkyl group with a carbon number of 1 to 5, a branched alkyl group or a cyclic alkyl group, a linear alkenyl group or a branched alkenyl group with a carbon number of 2 to 4 group, a straight chain alkynyl group or a branched alkynyl group with a carbon number of 2 or more and 4 or less]

[Chemical 9]

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

[Chemical 10]

[Wherein, the dotted line represents the bond with the benzene ring, Ar ¹ each independently represents a trivalent aromatic hydrocarbon group with 6 to 30 carbon atoms or a trivalent heteroaromatic group with 2 to 30 carbon atoms, and Ar ² each independently represents the carbon number A monovalent aromatic hydrocarbon group with 6 to 30 carbon atoms or a monovalent heteroaromatic group with 2 to 30 carbon atoms; Ar ¹ and Ar ² in formula (3) and formula (4) may be substituted by the Q mentioned above]]

＜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 inferred as follows. In order to improve the luminous efficiency of organic EL elements, in addition to the need to develop and use a luminescent material with a high quantum yield and a value that shows 100% as much as possible, it is necessary to: (a) balance the charges in the luminescent layer, that is, Make the number of holes and electrons equal; (b) eliminate the leakage of charges or excitons from the luminescent layer and seal them into the luminescent layer; (c) remove the pair annihilation of triplet excitons (triplet-triplet state Annihilation (triplet-triplet annihilation), or deactivation caused by the interaction between triplet excitons and charges (triplet-polaron quenching), or caused by impurities with low T1 energy levels deactivation and other deactivation processes. Regarding (a), the medium that accepts electrons and transports them in the light-emitting layer is mainly provided by the electron transport host material. However, on the other hand, the medium that supplies holes is not only provided by the hole transport material, but is also sometimes provided by the hole transport material. Iridium complexes used as luminescent materials bear. This tendency is particularly strong in the case of an iridium complex with a shallow ionization potential, and the iridium complex having a phenyl-pyridine type ligand as in the present invention is consistent with this situation. It is widely known that this structure shows high quantum yield and performs excellent green emission. In order to improve hole transport, it is ideal that the iridium complex shown in formula (1) has a structure in which the sites are not excessively shielded from easily oxidized iridium atoms. However, in the case of less shielding, there is also the possibility that an undesirable deactivation process between iridium complexes such as (c) may easily occur. Furthermore, when the hole transportability is too large, the holes leak to the electron transport layer side, and the condition (b) cannot be satisfied, and the efficiency of the device decreases. In the case where such fine adjustment of hole transport properties is achieved only by optimizing the substituents of formula (1), it may be difficult due to too many types of substituents or introduction positions, or there may be cases where the optimal structure does not exist. possibility. The present invention solves this problem by using in combination an iridium complex having a branched aromatic hydrocarbon group or a heteroaromatic group partially conjugated around an iridium atom, as shown in formula (2). Match the seats. It is believed that compared with formula (1), this structure utilizes its branched structure to shield iridium atoms to a higher degree, and is also relatively less prone to the extinction process described previously. Therefore, it is believed that by combining formula (1) and formula (2), the hole transport capability and the concentration of the luminescent material in the luminescent layer can be optimized to the optimal level without the extinction process occurring in the luminescent layer. As a result, the efficiency of the element can be further improved. Furthermore, when a long-chain alkyl group such as 2-ethylhexyl is used instead of X in the formula (2), it is difficult to match the charge balance of (a) because it is an insulator that does not allow electric charges to flow at all. Furthermore, when the luminescent layer is coated and film-formed, it is not preferable because the host material used in combination is rich in aromatic groups and has reduced compatibility and agglomeration, resulting in poor device performance.

<Structure of the iridium complex of the present invention> In trivalent iridium complex compounds, three bidentate coordination sites such as 2-phenylpyridine can be bonded. At this time, a complex with three identical ligands is called an isotactic complex, and a complex with only one different ligand is called a non-identical complex. In the present invention, an isotactic ligand complex capable of narrowing the half-value width of the emission spectrum is required. The reason for this is that for display applications, the half-value width is required to be as small as possible from the viewpoint of color purity. Among isoligand-type iridium complex compounds, two types of isomers are known: a facial form and a meridional form. In the present invention, it is necessary to have a planar body with a narrow spectral half-value width and a high quantum yield.

＜＜Formula (1)＞＞

[Chemical 11]

[Wherein, n represents an integer from 0 to 10; R represents a substituent, a represents 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', linear alkyl group, branched alkyl group or cyclic alkyl group with 1 to 5 carbon atoms, Linear alkoxy group, branched alkoxy group having 1 to 4 carbon atoms, linear alkylthio group, branched alkylthio group or cyclic alkylthio group having 1 to 4 carbon atoms, 2 to 4 carbon atoms The following linear or branched alkenyl groups, linear or branched alkynyl groups with 2 to 4 carbon atoms, diarylamine groups with 10 to 40 carbon atoms, 10 to 40 carbon atoms Arylheteroarylamine group or diheteroarylamine group having 10 to 40 carbon atoms, the alkyl group, the alkoxy group, the alkylthio group, the alkenyl group, the alkynyl group, The diarylamine group, the arylheteroarylamine group and the diheteroarylamine group can be substituted by more than one R' other than a hydrogen atom; R' is independently D, F, - CN, linear alkyl group, branched alkyl group or cyclic alkyl group with 1 to 5 carbon atoms, linear alkenyl group or branched alkenyl group with 2 to 4 carbon atoms, straight chain alkenyl group with 2 to 4 carbon atoms. Alkynyl or branched alkynyl] <n> n is an integer from 0 to 10. If n is greater than 10, the size of the iridium complex becomes too large, and the distance between the vicinity of the iridium atom responsible for hole transport and the surface of the iridium complex molecule becomes large, and the hole transport property of the iridium complex is impaired. , as a result, there is a risk of reducing the luminous life or driving life of the element. On the contrary, if n is within this range, it is preferable because the iridium complex compound can transfer charges or exhibit hole transport properties without being excessively shielded as described in the section "Mechanism". Therefore, n is preferably an integer of 0 to 8, more preferably an integer of 0 to 7, and even more preferably an integer of 1 to 6.

＜Bonding method of phenylene group＞ The bonding modes of the n linked phenylene groups are independently ortho-position, meta-position, and para-position, and are not particularly limited. The bonding at the ortho and meta positions is flexible and improves solubility. In addition, the conjugation of π electrons is broken midway, so the T1 energy level can be increased and the effect of quenching the green emission can be suppressed. From the viewpoint of solubility, a bond at the ortho position that can produce a rotamer due to steric hindrance is more preferable, and from a durability viewpoint, a bond at the meta position is more preferable. The reason is that during the driving process of the organic EL device, the bond at the ortho position may undergo a change to a triphenyl structure caused by oxidative coupling as shown in the following formula. Such a change may cause element deterioration due to a longer emission wavelength, a decrease in hole transport properties, or the like.

[Chemical 12]

On the other hand, if they are connected at a para position, the conjugation of π electrons becomes longer, so that the oxidation state in particular can be stabilized, and as a result, hole transport properties can be further improved. The electron hole transportability mainly comes from the electron-rich iridium atom. Therefore, if the electrons of the iridium atom can be distributed more widely to the ligand side through the π conjugated bonds of multiple p-phenylene groups, the hole transport will be improved. Sexuality improved significantly. Therefore, a preferred structure of the phenylene group is as shown in the following formula (5). In the phenyl group of the phenylpyridine ligand, the phenylene group directly bonded to the para position of the iridium atom is bonded at the para position. Knot. Among them, n ¹ represents the number of continuous p-phenylene groups, and is an integer greater than 1, n ² represents the number of consecutive p-phenylene groups further bonded to the end of the p-phenylene group, and n ¹ +n ² =n. From the viewpoint of durability, it is preferable that all of the continuous phenylene groups bonded to the end of the p-phenylene ring are all m-phenylene groups. From the viewpoint of solubility, the range of n ¹ is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1, and the range of n ² is preferably 1 to 8, more preferably 2 to 7, More preferably, it is 3-6.

That is, Formula (1) is preferably represented by the following Formula (5).

[Chemical 13]

[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]. Among them, in the case of a non-aromatic substituent, it has the effect of electrically insulating the iridium complex compound. Therefore, if the substituent is too large, the hole transport property of the iridium complex compound may be reduced. The substituent R is limited to a carbon number that does not exhibit this effect.

[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', carbon number A linear alkyl group of 1 or more and 5 or less, a branched alkyl group or a cyclic alkyl group, a linear alkoxy group with a carbon number of 1 or more and 4 or less, a branched alkoxy group, a linear alkyl group with a carbon number of 1 or more and 4 or less. Thio group, branched alkylthio group or cyclic alkylthio group, straight-chain alkenyl group with 2 to 4 carbon atoms, branched alkenyl group or cyclic alkenyl group, straight-chain alkynyl group with 2 to 4 carbon atoms, branched Alkynyl or cyclic alkynyl group, diarylamine group with 10 to 40 carbon atoms, arylheteroarylamine group with 10 to 40 carbon atoms, diarylamine group with 10 to 40 carbon atoms Amino group. The alkyl group, the alkoxy group, the alkylthio group, the alkenyl group, the alkynyl group, the diarylamine group, the arylheteroarylamine group and the diarylamine group The amine group may be substituted by more than one R' other than a hydrogen atom. R' will be described later.

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

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

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

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

Examples of the linear or branched alkynyl group having 2 to 4 carbon atoms include an ethynyl group, a propynyl group, a butynyl group, and the like. From the viewpoint of durability, the carbon number is preferably 2 or more, more preferably 3 or less, and most preferably 2.

Examples of the diarylamine group having a carbon number of 10 or more and 40 or less include a diphenylamine group, a phenyl(naphthyl)amine group, a bis(biphenyl)amine group, and a bis(p-terphenyl)amine group. )amine group, etc. From the viewpoint of the balance between solubility and durability, the carbon number of these diarylamine groups is preferably 10 or more, and is preferably 36 or less, more preferably 30 or less, and most preferably 25 or less.

Examples of the arylheteroarylamine group having a carbon number of 10 or more and 40 or less include phenyl(2-pyridyl)amine group, phenyl(2,6-diphenyl-1,3,5-tri Azin-4-yl)amine group, etc. From the viewpoint of the balance between solubility and durability, the carbon number of these arylheteroarylamine groups is preferably 10 or more, and is preferably 36 or less, more preferably 30 or less, and most preferably 25 or less. .

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

As a more preferable type of substituent, particularly from the viewpoint of not impairing the durability as a light-emitting material in an organic electroluminescent element, D, F, -CN, or having a carbon number of 1 or more can be listed independently. And the linear alkyl group, branched alkyl group or cyclic alkyl group with a value of less than 5 is particularly preferably D, F, -CN, methyl or trifluoromethyl, and the most preferred one is D.

＜R'＞ The R's are independently selected from D, F, -CN, linear alkyl groups with 1 to 5 carbon atoms, branched alkyl or cyclic alkyl groups, and linear alkenyl groups with 2 to 4 carbon atoms. Or in a branched alkenyl group, a linear or branched alkynyl group with a carbon number of 2 or more and 4 or less.

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

＜Molecular weight＞ The molecular weight of the iridium complex compound represented by formula (1) is not particularly limited. However, if it is too small, the solubility decreases, and the composition of the present invention may not be used as an ink. On the contrary, if the molecular weight is too large, the hole transportability may decrease. Therefore, the molecular weight range is preferably from 1111 to 10000, more preferably from 1300 to 8000, and even more preferably from 1500 to 5000.

＜＜Formula (2)＞＞

[Chemical 14]

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

[Chemical 15]

[Wherein, the dotted line represents the bond with the benzene ring, Ar ¹ each independently represents a trivalent aromatic hydrocarbon group with 6 to 30 carbon atoms or a trivalent heteroaromatic group with 2 to 30 carbon atoms, and Ar ² each independently represents the carbon number A monovalent aromatic hydrocarbon group with 6 to 30 carbon atoms or a monovalent heteroaromatic group with 2 to 30 carbon atoms; Ar ¹ and Ar ² in formula (3) and formula (4) may be substituted by the Q mentioned above]]

＜m＞ m is an integer from 0 to 10. When m=0, in the benzene ring bonded to the iridium atom, X is directly bonded to the para position relative to the iridium atom. If m is too large, the iridium atoms will be greatly shielded, and the hole transport properties to the iridium complex will be greatly impaired, or the charge injection and energy transfer to the iridium complex will be impaired due to the shielding, so as a result, the device will The luminous efficiency or driving life may 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. In addition, the preferred bonding method of m connected phenylene groups is the same as formula (1).

＜X＞ X represents formula (3) or formula (4). The dotted line in Formula (3) or Formula (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. A monovalent aromatic hydrocarbon group or a monovalent heteroaromatic group having 2 to 30 carbon atoms. The types of these aromatic hydrocarbon groups or heteroaromatic groups may be single rings or condensed rings, or they may be structures formed by bonding. Ar ¹ and Ar ² may also be replaced by Q. Preferably, 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.

As examples of the types of aromatic hydrocarbon groups or heteroaromatic groups, if the corresponding parent skeletons are listed, they can be listed: benzene ring, naphthalene ring, anthracene ring, benzanthracene ring, phenanthrene ring, benzophenanthrene ring Ring, pyrene ring, pyrene ring, fluoranthene ring, perylene ring, benzopyrene ring, benzofluoranthene ring, fused tetraphenyl ring, fused pentaphenyl ring, biphenyl, terphenyl, tetraphenyl, fluorene ring, spiro Difluorene ring, dihydrophenanthrene ring, dihydropyrene ring, tetrahydropyrene 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, indolocarbazole ring, indenocarbazole ring, pyridine ring, cinnoline ring, Isosinoline ring, acridine ring, phenanthridine ring, thiazide ring, thioxazine ring, pyrazine ring, imidazole ring, benzimidazole ring, naphthoimidazole ring, phenanzimidazole ring, oxazole ring, benzene Oxazole ring, naphthoxazole ring, thiazole ring, benzothiazole ring, pyrimidine ring, benzopyrimidine ring, pyridazine ring, quinoxaline ring, diazaanthracene ring, diazapyrene ring, phenoxazole ring Azine ring, thiazine 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, purine ring, benzothiadiazole ring, etc.

From the viewpoint of durability, both Ar ¹ and Ar ² are preferably a single ring with a six-membered ring structure or a condensed ring containing a six-membered ring structure, or an aromatic hydrocarbon group or a heteroaromatic ring with a structure in which these are bonded. , and 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 is no restriction on the bonding position of the two Ar ^2. However, if there are sites bonding to each other at the ortho positions, the conjugated system of π electrons will be cut off due to steric hindrance, so it is durable. Poor sex. Therefore, when Ar ¹ is a benzene ring, the preferred bonding positions are the 1-position, 3-position, and 5-position which are meta-positions to each other.

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

From the viewpoint of improving solubility, the plurality of Ar ² appearing in formula (3) or (4) are preferably different structures, but from the viewpoint of durability, the same structure is more preferable. ＜Q＞

Q represents a substituent. The type of Q is not particularly limited and should be appropriately selected to adjust the solubility or emission wavelength. However, the type that is usually selected is the following [substituent group Z].

[Substituent Group Z] Selected from 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 , a linear alkyl group, a branched alkyl group or a cyclic alkyl group with a carbon number of 1 to 30, a linear alkoxy group, a branched alkoxy group or a cyclic alkyl group with a carbon number of 1 to 30 alkoxy group, a linear alkylthio group, a branched alkylthio group or a cyclic alkylthio group with a carbon number of 1 to 30, a linear alkenyl group, a branched alkenyl group or a cyclic alkenyl group with a carbon number of 2 to 30 group, a linear alkynyl group, a branched alkynyl group or a cyclic alkynyl group with a carbon number of 2 or more and 30 or less, an aromatic hydrocarbon group with a carbon number of 5 or more and 60 or less, an aromatic heterocyclic group with a carbon number of 2 or more and 60 or less, 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 , a diarylamine group having a carbon number of 10 or more and 40 or less, an arylheteroarylamine group having a carbon number of 10 or more and 40 or less, or a diheteroarylamine group having a carbon number of 10 or more and 40 or less.

The alkyl group, the alkoxy group, the alkylthio group, the alkenyl group and the alkynyl group may be further substituted by more than one Q', one or two of these groups -CH ₂ - The above non-adjacent -CH ₂ - groups can be substituted as -C(-Q')=C(-Q')-, -C≡C-, -Si(-Q') ₂ -, -C(=O )-, -NQ'-, -O-, -S-, -CONQ'- or a divalent aromatic hydrocarbon group or a divalent aromatic heterocyclic group. In addition, more than one hydrogen atom in these groups may be substituted by 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 diarylamine group, the The arylheteroarylamine group and the diheteroarylamine group may be further substituted by one or more Q' independently. Q' will be described later.

Examples of linear alkyl groups, branched alkyl groups or cyclic alkyl groups having 1 to 30 carbon atoms include: methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, isopropyl, isobutyl, cyclopentyl, cyclohexyl, n-octyl, norbornyl, adamantyl, etc. In the case of an alkyl group, if the number of carbon atoms is too large, the complex will be highly obscured and the durability will be impaired. Therefore, the number of carbon atoms is preferably 1 or more, and is preferably 30 or less, more preferably 20 or less, and still more preferably Preferably below 12. Among them, in the case of a branched alkyl group, the shielding effect is greater than that of a linear alkyl group or a cyclic alkyl group, so the number of carbon atoms is preferably 8 or less.

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

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

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

Examples of a linear, branched or cyclic alkynyl group having 2 to 30 carbon atoms include an ethynyl group, a propynyl group, a butynyl group, a pentynyl group, a hexynyl group, and a heptynyl group. , octynyl, etc. From the viewpoint of durability, the number of carbon atoms is preferably 2 or more, more preferably 30 or less, more preferably 20 or less, and most preferably 12 or less.

The aromatic hydrocarbon group with a carbon number of 5 to 60 and the aromatic heterocyclic group with a carbon number of 2 to 60 may exist as a single ring or a condensed ring, or may have other types of aromatic hydrocarbon groups on one ring. Or a group formed by bonding or ring-condensing aromatic heterocyclic groups.

Examples of these include: phenyl, naphthyl, anthracenyl, benzanthracenyl, phenanthrenyl, benzophenanthryl, pyrenyl, ceryl, fluoranthryl, perylene, benzopyrenyl, benzene Fluoranthranyl, fused tetraphenyl, fused pentaphenyl, biphenyl, terphenyl, fluorenyl, spirodifluorenyl, dihydrophenanthranyl, dihydropyrenyl, tetrahydropyrenyl, indenofluorenyl , Furyl, benzofuryl, isobenzofuryl, dibenzofuranyl, thienyl, benzothienyl, dibenzothienyl, pyrrolyl, indolyl, isoindolyl, carbazolyl , benzocarbazolyl, indolocarbazolyl, indenocarbazolyl, pyridyl, cinnolinyl, isosinolinyl, acridinyl, phenanthridinyl, phenanthiazinyl, phenanthioxazinyl, Pyrazolyl, indazolyl, imidazolyl, benzimidazolyl, naphthoimidazolyl, phenanthroimidazolyl, pyridine imidazolyl, oxazolyl, benzoxazolyl, naphzooxazolyl, thiazolyl, benzene Thiazolyl, pyrimidinyl, benzopyrimidinyl, pyridazinyl, quinoxalinyl, diazaanthracenyl, diazapyrenyl, pyrazinyl, pyrazinyl, phenylthiazinyl, naphthyridinyl , azacarbazolyl, benzocarboline, phenanthrolinyl, triazolyl, benzotriazolyl, oxadiazolyl, thiadiazolyl, triazinyl, 2,6-diphenyl-1 ,3,5-triazin-4-yl, tetrazolyl, purinyl, benzothiadiazolyl, etc.

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

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

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

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

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

Examples of the diarylamine group having a carbon number of 10 or more and 40 or less include a diphenylamine group, a phenyl(naphthyl)amine group, a bis(biphenyl)amine group, and a bis(p-terphenyl)amine group. )amine group, etc. From the viewpoint of the balance between solubility and durability, the carbon number of these diarylamine groups is 10 or more, and preferably 36 or less, more preferably 30 or less, most preferably 25 or less.

Examples of the arylheteroarylamine group having a carbon number of 10 or more and 40 or less include phenyl(2-pyridyl)amine group, phenyl(2,6-diphenyl-1,3,5-tri Azin-4-yl)amine group, etc. From the viewpoint of the balance between solubility and durability, the carbon number of these arylheteroarylamine groups is 10 or more, and preferably 36 or less, more preferably 30 or less, most preferably 25 or less.

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

<Q'>Q' is selected from 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 A linear alkyl group, a branched alkyl group or a cyclic alkyl group with a carbon number of 1 or more and 30 or less, a linear alkoxy group, a branched alkoxy group or a cyclic alkoxy group with a carbon number of 1 or more and 30 or less, a carbon number of 1 or more And a linear alkylthio group, a branched alkylthio group or a cyclic alkylthio group with 30 or less carbon atoms, a linear alkenyl group, a branched alkenyl group or a cyclic alkenyl group with a carbon number of 2 or more and less than 30 carbon atoms, or a linear alkenyl group with a carbon number of 2 or more and less than 30 carbon atoms. Linear alkynyl group, branched alkynyl group or cyclic alkynyl group, aromatic hydrocarbon group with 5 to 60 carbon atoms, aromatic heterocyclic group with 2 to 60 carbon atoms, aromatic hydrocarbon group with 5 to 40 carbon atoms. Aryloxy group, arylthio group with 5 to 40 carbon atoms, aralkyl group with 5 to 60 carbon atoms, heteroaralkyl group with 5 to 60 carbon atoms, 10 to 40 carbon atoms A diarylamine group, an arylheteroarylamine group having a carbon number of 10 or more and 40 or less, or a diheteroarylamine group having a carbon number of 10 or more and 40 or less. When there are multiple Q's, 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 by more than one R'', one or two of these groups -CH ₂ - More than two non-adjacent -CH ₂ - groups can be substituted as -C(-Q'')=C(-Q'')-, -C≡C-, -Si(-Q'') ₂ -, - C(=O)-, -NQ''-, -O-, -S-, -CONQ''- or a divalent aromatic hydrocarbon group or a divalent aromatic heterocyclic group. In addition, more than one hydrogen atom in these groups may be substituted by F, Cl, Br, I or -CN.

In addition, the aromatic hydrocarbon group, the aromatic heterocyclic group, the aryloxy group, the arylthio group, the aralkyl group, the heteroaralkyl group, and the diarylamine group , the aryl heteroarylamino group and the diheteroarylamine group may be further substituted by more than one Q''. Q'' will be described later.

In addition, two or more adjacent Q's may bond with each other while losing their respective hydrogen atoms to form an aliphatic, aromatic or heteroaromatic monocyclic or condensed ring.

＜Q''＞ Q'' is each independently selected from D, F, -CN, an aliphatic hydrocarbon group with a carbon number of 1 to 20, an aromatic hydrocarbon group with a carbon number of 5 to 20, or an aromatic hetero group with a carbon number of 5 to 20. in the ring base. Two or more adjacent Q''s may bond with each other while losing their respective hydrogen atoms to form an aliphatic, aromatic hydrocarbon, or heteroaromatic monocyclic or condensed ring. When there are multiple Q'''s, they may be the same or different.

From the viewpoint of durability, more preferred types of the substituent Q that the formula (2) can have are D, F, a linear alkyl group, a branched alkyl group or a cyclic alkyl group with a carbon number of 1 to 30, and carbon Linear alkenyl group, branched alkenyl group or cyclic alkenyl group with a number of 2 or more and 30 or less, aromatic hydrocarbon group with a carbon number of 5 or more and 60 or less, aromatic heterocyclic group with a carbon number of 2 or more and 60 or less, carbon number 5 Aralkyl groups with more than 60 carbon atoms, heteroaralkyl groups with more than 5 carbon atoms and less than 60 carbon atoms, diarylamine groups with more than 10 carbon atoms and less than 40 carbon atoms, arylheteroarylamine groups with more than 10 carbon atoms and less than 40 carbon atoms. group, or a diheteroarylamine group with a carbon number of 10 or more and 40 or less, and more preferred types are D, F, a linear alkyl group, a branched alkyl group or a cyclic alkyl group with a carbon number of 1 or more and 30 or less, Aromatic hydrocarbon group with 5 to 60 carbon atoms, aromatic heterocyclic group with 2 to 60 carbon atoms, diarylamine group with 10 to 40 carbon atoms, aryl group with 10 to 40 carbon atoms Heteroarylamine group, or diheteroarylamine group with a carbon number of 10 to 40, the best type is D, F, a linear alkyl group, a branched alkyl group or a cyclic group with a carbon number of 1 to 30 An alkyl group or an aromatic hydrocarbon group having 5 or more carbon atoms and 60 or less carbon atoms, of which D or F is preferred.

＜b＞ b is 0 to the maximum integer that can be replaced by one coordination agent in formula (2).

＜Molecular weight＞ The molecular weight of the iridium complex compound represented by formula (2) is not particularly limited. However, if it is too small, the solubility decreases, and the composition of the present invention may not be used as an ink. On the contrary, if the molecular weight is too large, the hole transportability may decrease. Therefore, the molecular weight range is preferably from 1,339 to 15,000, more preferably from 1,650 to 12,000, and even more preferably from 1,750 to 10,000.

＜＜Better combination＞＞ From the viewpoint of further improving the luminous efficiency, the combination of the compound represented by the formula (1) and the compound represented by the formula (2) is preferably a compound in which X in the formula (2) is represented by the formula (3). Compound represented by formula (2). In addition, it is more preferable to use a compound represented by formula (5) as the compound represented by formula (1), and as the compound represented by formula (2), use a compound represented by formula (2) represented by formula (3) compound.

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

<Specific examples of compounds represented by formula (1)>

[Chemical 16]

<Specific examples of compounds represented by formula (2)>

[Chemical 17]

<<Measurement method of the maximum emission wavelength in the solution>> The method of measuring the maximum emission wavelength in the solution of the iridium complex compound of the present invention is as follows. For a solution in which an iridium complex compound is dissolved in toluene at a concentration of 1×10 ^-4 mol/L or less, preferably 1×10 ^-5 mol/L at room temperature, a spectrophotometer (Hamamatsu Photon (Hamamatsu Photon) Organic EL quantum yield measuring device C9920-02 manufactured by Hamamatsu Photonics) measured the phosphorescence spectrum. However, it is necessary to fully remove oxygen that causes extinction by nitrogen bubbling or freezing degassing before measurement. 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)> The maximum emission wavelength shown by the iridium complex compound of the present invention is not particularly limited. When used as a particularly preferred green light-emitting material, the compound represented by formula (1) and the compound represented by formula (2) For any compound, 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, more preferably 540 nm or less.

In addition, in the composition for the light-emitting layer of the present invention, the absolute value of the difference between the maximum emission wavelengths of the compound represented by formula (1) and the compound represented by formula (2) is not particularly limited, and is usually 0. nm or more and 20 nm or less, preferably 0 nm or more and 10 nm or less, more preferably 0 nm or more and 5 nm or less.

The method for measuring the maximum luminescence wavelength shown by the compound represented by formula (1) and the compound represented by formula (2) is as described in <<Measurement method of maximum luminescence wavelength in solution>>, in more detail , can be measured by the following measurement method. [Measurement method: A solution obtained by dissolving a compound represented by formula (1) or a compound represented by formula (2) in toluene at a concentration of 1×10 ^-5 mol/L at room temperature is bubbled with nitrogen for 20 minutes or more to obtain a sample from which oxygen that causes extinction has been removed, and the wavelength showing the maximum value of the phosphorescence spectrum intensity obtained from the sample is regarded as the maximum emission wavelength]

＜＜Synthetic method of iridium complex compound＞＞ The ligand of the iridium complex compound of the present invention can use building blocks such as halogenated fluorene or 2-bromo-5-iodopyridine, through the Miyaura-Ishiyama boronation reaction or Hartwig-Miyaura C-H Borylation reaction (Hartwig-Miyaura C-H borylation) is converted into borate ester, and the skeleton is constructed through the Suzuki-Miyaura coupling reaction of these intermediates and halogenated aryl groups. By combining other known methods, ligands incorporating various substituents can be synthesized.

An example of a method for synthesizing an iridium complex compound is a method of cross-linking an iridium binuclear complex via chlorine represented by the following formula [A] (for ease of understanding, a phenylpyridine ligand is used as an example) ( M.G.Colombo, T.C.Brunold, T.Riedener, H.U.Gudel, Inorg.Chem., 1994, 33, 545-550); A method of obtaining the target compound from a dinuclear complex of the following formula [B] by further exchanging chlorine cross-linking with acetoacetone to convert it into a mononuclear complex (S. Lamansky, P. P. Djurovich, D. Murphy, F. Abdel-Razzaq, R. Kwong, I. Qi I.Tsyba, M.Borz, B.Mui, R.Bau, M.Thompson, Inorganic Chemistry (Inorg. Chem.), 2001, 40, 1704-1711), etc. Furthermore, there is a method of directly obtaining a homo-tricyclometallated iridium complex by reacting a ligand with a tris(acetylacetone iridium (III)) complex in glycerin at a high temperature (K. Dai De'an (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 conditions of a typical reaction represented by the following formula [A] are as follows. As the first stage, a chlorine cross-linked iridium dinuclear complex is synthesized by reacting 2 equivalents of ligands with 1 equivalent of iridium chloride n-hydrate. The solvent is usually a mixed solvent of 2-ethoxyethanol and water, but no solvent or other solvents can also be used. It is also possible to use excessive amounts of ligands or use additives such as bases to promote the reaction. Other cross-linking anionic ligands such as bromine can also be used instead of chlorine.

The reaction temperature is not particularly limited, but is generally preferably 0°C or higher, more preferably 50°C or higher. In addition, the temperature is preferably 250°C or lower, and more preferably 150°C or lower. By being within these ranges, only the target reaction can be carried out without by-products or decomposition reactions, and there is a tendency to obtain high selectivity.

[Chemical 18]

In the second stage, a halide ion trapping agent like silver triflate is added to contact the newly added ligand to obtain the target complex. The solvent is usually ethoxyethanol or diglyme, but depending on the type of ligand, there may be no solvent or other solvents may be used, or a mixture of multiple solvents may be used. The reaction may proceed even without adding a halogen ion trapping agent, so it is not necessarily necessary. However, in order to increase the reaction yield and selectively synthesize facial isomers with higher quantum yields, adding this trapping agent agent is beneficial. The reaction temperature is not particularly limited, but is usually carried out in the range of 0°C to 250°C.

In addition, typical reaction conditions represented by the following formula [B] will be described. The first-stage dinuclear complex can be synthesized in the same manner as formula [A]. In the second stage, the activity of the 1,3-diketone compound can be extracted by mixing the dinuclear complex with more than 1 equivalent of acetoacetone-like 1,3-diketone compound and more than 1 equivalent of sodium carbonate-like compound. Basic compounds of hydrogen react and convert into mononuclear complexes coordinated by 1,3-diketone ligands. Usually, a solvent such as ethoxyethanol or methylene chloride that can dissolve the dinuclear complex used as a raw material is used. When the ligand is in liquid form, it can also be carried out without a solvent. The reaction temperature is not particularly limited, but is usually carried out in the range of 0°C to 200°C.

[Chemical 19]

In the third stage, more than 1 equivalent of the ligand is reacted. The type and amount of the solvent are not particularly limited. When the ligand is liquid at the reaction temperature, it can also be solvent-free. The reaction temperature is not particularly limited, but since the reactivity is slightly insufficient, the reaction is often carried out at a higher temperature of 100°C to 300°C. Therefore, a solvent with a high boiling point such as glycerol can be preferably used.

After the final reaction, purification is performed to remove unreacted raw materials, reaction by-products and solvents. Common purification operations in organic synthetic chemistry can be applied, but as described in the non-patent literature, purification is mainly performed by parallel-phase silica gel column chromatography. A single or mixed solution of hexane, heptane, methylene chloride, chloroform, ethyl acetate, toluene, methyl ethyl ketone, and methanol can be used as the developing solution. Refining can also be carried out multiple times with changing conditions. Other chromatography techniques (reversed-phase silica gel chromatography, size exclusion chromatography, paper chromatography) or purification such as liquid separation cleaning, reprecipitation, recrystallization, powder suspension cleaning, and vacuum drying can be implemented as needed. operate.

<Content of iridium complex compound> The content of the iridium complex compound in the composition for the light-emitting layer of the present invention is the total of the compound represented by the formula (1) and the compound represented by the formula (2) contained in the composition for the light-emitting layer. The mass ratio relative to the mass of the entire composition for the light-emitting layer is usually 0.001 mass % or more, preferably 0.01 mass % or more, and usually 99.9 mass % or less, preferably 99 mass % or less. By setting the content of the iridium complex compound in the composition for the light-emitting layer to this range, holes or holes can be efficiently transferred from an adjacent layer (for example, a hole transport layer or a hole blocking layer) to the light-emitting layer. The injection of electrons can reduce the driving voltage.

<The ratio of the compound represented by formula (1) to the compound represented by formula (2) in the composition for the light-emitting layer> The mixing ratio of the compound represented by the formula (1) and the compound represented by the formula (2) in the composition for the light-emitting layer of the present invention is not particularly limited, and is determined through experiments based on the optimal structure of the device used. An optimal ratio is sufficient. Usually, the proportion of the compound represented by the formula (1) is expressed in mass % relative to the total mass of the compound represented by the formula (1) and the compound represented by the formula (2). The mass ratio is usually 1% or more, preferably 5% or more, more preferably 10% or more, further preferably 20% or more, and usually 99% or less, preferably 95% or less, more preferably 90% or less, more preferably 80% or less. From the viewpoint of improving dispersion 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 (2) is particularly preferred. It is 10% or more and 80% or less, and the optimum is 25% or more and 75% or less.

When the composition for the light-emitting layer of the present invention is used for, for example, an organic electroluminescent element, in addition to the iridium complex compound or solvent, the organic electroluminescent element, particularly the light-emitting layer, may also be contained. Charge transport compounds used in. When the composition for a light-emitting layer of the present invention is used to form a light-emitting layer of an organic electroluminescent element, it is preferable to include the iridium complex compound of the present invention as a light-emitting material and other charge transport compounds as a charge transport compound. Subject material.

As other charge-transporting compounds that can be contained in the composition for the light-emitting layer of the present invention, those previously used as materials for organic electroluminescent elements can be used. Examples include: pyridine, carbazole, naphthalene, perylene, pyrene, anthracene, pyridine, tetraphenyl, phenanthrene, kone, fluoranthene, benzophenanthrene, fluorene, acetylnaphthofluoranthene, coumarin, p-bis( 2-Phenylvinyl)benzene and its derivatives, quinacridone derivatives, DCM (4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminobenzene) Vinyl)-4H-pyran (4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran))-based compounds, benzopyran derivatives, rose bengal derivatives, benzothiane Anthene derivatives, azabenzothioxanthene, arylamine group-substituted condensed aromatic ring compounds, arylamine group-substituted styryl derivatives, etc.

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

In addition, the content of other charge transport compounds in the composition for the light-emitting layer is usually 1000 parts by mass or less, preferably 100 parts by mass, relative to 1 part by mass of the iridium complex compound of the present invention in the composition for the light-emitting layer. or less, and more preferably 50 parts by mass or less, and usually 0.01 part by mass or more, preferably 0.1 part by mass or more, and still more preferably 1 part by mass 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 a light-emitting layer ink (hereinafter, it may also be referred to as a light-emitting layer ink containing an iridium complex compound) by further containing an organic solvent. The ink for a light-emitting layer containing an iridium complex compound of the present invention can be suitably used to produce a coating-type organic EL element. In particular, it can be excellently used as a light-emitting layer material for a green element of 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 two kinds of the iridium complex compound of the present invention and an organic solvent. The ink for a light-emitting layer containing the iridium complex compound of the present invention is generally 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 element. The organic layer is particularly preferably a light-emitting layer, and more preferably is a green light-emitting layer. That is, the ink for the light-emitting layer containing the iridium complex compound of the present invention and an organic solvent is preferably an ink for the light-emitting layer for an organic electroluminescent element.

＜Organic solvent＞ The organic solvent contained in the ink for a light-emitting 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 iridium complex compound of the present invention as a solute in an organic solvent has high solvent solubility, and therefore is not particularly limited as long as it is an organic solvent in which a charge transport compound described below is well dissolved. Preferred organic solvents include, for example, alkanes such as n-decane, cyclohexane, ethylcyclohexane, decalin, and dicyclohexane; toluene, xylene, mesitylene, and phenylcyclohexane. , tetralin and other aromatic hydrocarbons; chlorobenzene, dichlorobenzene, trichlorobenzene and other halogenated aromatic hydrocarbons; 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole , Phenylethyl ether, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole, diphenyl ether and other aromatic ethers; aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, n-butyl benzoate, etc.; cyclohexanone, cyclooctanone, quinone, etc. Alicyclic ketones such as 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 Categories; aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA), etc.

Among them, alkanes or aromatic hydrocarbons are preferred. In particular, phenylcyclohexane has better viscosity and boiling point in the 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 is usually 270°C or lower, preferably 250°C or lower, more preferably 230°C or lower. If it is lower than this range, during wet film formation, the organic solvent evaporates from the ink for the light-emitting layer, and the film-forming stability may be reduced.

The content of the organic solvent in the ink for the light-emitting layer containing an iridium complex compound 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. , more preferably 99.9 mass% or less, particularly preferably 99 mass% or less. Normally, the thickness of the light-emitting layer is about 3 nm to 200 nm. If the content of the organic solvent is less than this lower limit, the viscosity of the ink for the light-emitting layer becomes too high, and the film-forming workability may be reduced. On the other hand, if the content of the organic solvent exceeds the upper limit, the thickness of the film obtained by removing the organic solvent after film formation will not be obtained, so film formation tends to be difficult.

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

＜＜Organic Electroluminescence Elements＞＞ Hereinafter, an organic electroluminescent element using the ink for a light-emitting layer of the present invention (hereinafter, sometimes referred to as the “organic electroluminescent element of the present invention”) will be described. The organic electroluminescent element 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 element 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 includes the present invention. The iridium complex compound contained in the ink for the light-emitting layer. The organic layer includes a light emitting layer.

The organic layer containing the 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 further preferably is a layer formed by wet A layer formed by a film-forming method. The layer formed by the wet film forming method is preferably the light-emitting layer. In the present invention, the so-called wet film forming method refers to the method using, for example, spin coating, dip coating, die coating, rod coating, blade coating, roller coating, spray coating, capillary coating, inkjet As the film forming method, i.e., the coating method, a wet film forming method such as the nozzle printing method, screen printing method, gravure printing method, and flexographic printing method is used, and the film formed by these methods is dried. method for film formation.

In one aspect, the organic electroluminescent element of the present invention preferably has an anode, a light-emitting layer, and a cathode in order on the substrate, and the light-emitting layer contains the compound represented by the formula (1) and the formula (2) ) represented by the compound.

1 is a schematic cross-sectional view showing a preferred structural example of the organic electroluminescent element 10 of the present invention. In FIG. 1 , symbol 1 represents a substrate, symbol 2 represents an anode, symbol 3 represents a hole injection layer, and symbol 4 represents Symbol 5 represents the hole transport layer, symbol 5 represents the light-emitting layer, symbol 6 represents the hole blocking layer, symbol 7 represents the electron transport layer, symbol 8 represents the electron injection layer, and symbol 9 represents the cathode.

The materials used in these structures can be known materials and are not particularly limited. Representative materials and manufacturing methods for each layer are described below as examples. In addition, when citing publications, papers, etc., the corresponding contents can be appropriately applied and applied within the common sense of those skilled in the art.

<Substrate 1> The substrate 1 becomes the support of the organic electroluminescent element, and usually a quartz or glass plate, a metal plate or metal foil, a plastic film or a sheet is used. Among these, a glass plate or a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, or polyester is preferred. From the viewpoint that the organic electroluminescent element is less likely to be degraded by external gas, the substrate 1 is preferably made of a material with high gas barrier properties. Therefore, especially when a material with low gas barrier properties such as a synthetic resin substrate is used, 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 the function of injecting holes into the layer on the light-emitting layer side. The anode 2 usually includes: metals such as aluminum, gold, silver, nickel, palladium, and platinum; metal oxides such as indium and/or tin oxides; halide metals 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 sputtering or vacuum evaporation. In addition, when the anode 2 is formed using metal fine particles such as silver, copper iodide and other fine particles, carbon black, conductive metal oxide fine particles, conductive polymer fine powder, etc., it can also be dispersed in an appropriate binder. agent resin solution and coated onto the substrate to form. In addition, 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 (Applied Physics Letters, Appl. Phys . Lett.), Vol. 60, pp. 2711, 1992).

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

The thickness of the anode 2 may be determined based on required transparency, material, etc. In particular, when high transparency is required, it is preferable to have a thickness that has a visible light transmittance of 60% or more, and further preferably a thickness of 80% or more. The thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more, and is usually 1000 nm or less, preferably 500 nm or less. On the other hand, when transparency is not required, the thickness of the anode 2 may be any thickness depending on 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, it is preferable to perform ultraviolet + ozone, oxygen plasma, argon plasma, etc. treatment before film formation, thereby removing impurities on the anode and adjusting its ionization potential to make the holes Improved injectability.

<Hole injection layer 3> The layer responsible for 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. Furthermore, when there are two or more layers responsible for 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 called the hole injection layer 3 . In order to enhance the function of transporting holes from the anode 2 to the light-emitting layer 5 side, it is preferable to use the hole injection layer 3 . In the case of 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 is usually 1000 nm or less, preferably 500 nm or less.

The hole injection layer 3 may be formed by vacuum evaporation or wet film formation. In terms of excellent film-forming properties, it is preferably formed 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, the hole injection layer 3 preferably contains a cationic radical compound, and particularly preferably contains a cationic 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 . In addition, in the case of wet film-forming methods, solvents are usually included. The composition for forming the hole injection layer preferably has high hole transport properties and can efficiently transport injected holes. Therefore, it is preferable that the hole mobility is high and that impurities that become traps are less likely to be generated during production or use. In addition, it is preferred to have excellent stability, low ionization potential, and high transparency to visible light. Especially when the hole injection layer 3 is in contact with the light-emitting layer 5 , it is preferable not to extinguish the light emitted from the light-emitting layer 5 or to form an exciplex with the light-emitting layer 5 so as not to reduce the luminous efficiency. By.

As the hole transport compound, a compound having an ionization potential of 4.5 eV to 6.0 eV is preferred from the viewpoint of inhibiting charge injection 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, and trifluorenyl compounds with a fluorenyl group. Compounds linked to amines, hydrazone compounds, silazane compounds, quinacridone compounds, etc.

Among the above-described exemplary compounds, in terms of amorphous properties and visible light transmittance, aromatic amine compounds are preferred, and aromatic tertiary amine compounds are particularly preferred. Here, the aromatic tertiary amine compound refers to a compound having an aromatic tertiary amine structure, and also includes compounds having a group derived from an aromatic tertiary amine. The type of the aromatic tertiary amine compound is not particularly limited. In order to easily obtain uniform light emission due to the surface smoothing effect, it is preferable to use a polymer compound with a weight average molecular weight of 1,000 or more and 1,000,000 or less (repeat Polymeric compounds with linked units). Preferred examples of the aromatic tertiary amine polymer compound include polymer compounds having repeating units represented by the following formula (I).

[Chemistry 20]

(In formula (I), Ar ¹ and Ar ² each independently represent an aromatic group which may have a substituent or a heteroaromatic group which may have a substituent; Ar ³ to Ar ⁵ each independently represent an aromatic group which may have a substituent. A group or a heteroaromatic group that may have a substituent; Q represents a linking group selected from the following linking group group; in addition, among Ar ¹ to Ar ⁵ , two groups bonded to the same N atom may be bonded to each other. knot to form a ring)

The connecting groups are shown below.

[Chemistry 21]

(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 represent a hydrogen atom or any substitution. base)

The aromatic group and heteroaromatic group of Ar ¹ to Ar ¹⁶ in formula (I) are preferably derived from a benzene ring in view of the solubility, heat resistance, and hole injection transport properties of the polymer compound. , a naphthalene ring, a phenanthrene ring, a thiophene ring, and a pyridine ring, and more preferably a group derived from a benzene ring and a naphthalene ring.

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

＜Electron-accepting compounds＞ Since the conductivity of the hole injection layer 3 can be improved by oxidation of the hole-transporting compound, the hole injection layer 3 preferably contains an electron-accepting compound.

As the electron-accepting compound, a compound having an oxidizing ability and an ability to accept a single electron from the hole-transporting compound is preferred. Specifically, a compound having an electron affinity of 4 eV or more is preferred, and an electron affinity is further preferred. Compounds with an affinity above 5 eV.

Examples of such electron-accepting compounds include compounds selected from the group consisting of triarylboron compounds, metal halides, Lewis acids, organic acids, onium salts, salts of arylamines and metal halides, and salts of arylamines and Lewis acids. One or more than two compounds in a group, etc. Specific examples include onium salts in which organic groups are substituted, such as 4-isopropyl-4'-methyldiphenylphosphonium tetrakis(pentafluorophenyl)borate and triphenylsonium tetrafluoroborate. International Publication No. 2005/089024); iron (III) chloride (Japanese Patent Application Publication No. 11-251067), inorganic compounds with high atomic valence such as ammonium peroxodisulfate; cyano compounds such as tetracyanoethylene; Aromatic boron compounds such as (pentafluorophenyl)borane (Japanese Patent Application Publication No. 2003-31365); fullerene derivatives and iodine, etc.

＜Cationic radical compounds＞ As the cationic radical compound, an ionic compound including a cationic radical, which is a chemical species in which one electron has been removed from the hole-transporting compound, and a counteranion is preferred. Among them, when the cationic radical is derived from a hole-transporting polymer compound, the cationic radical has a structure in which one electron has been removed from the repeating unit of the polymer compound.

As the cationic radical, a chemical species in which one electron has been removed from the compound described above as a hole-transporting compound is preferred. From the viewpoints of amorphousness, visible light transmittance, heat resistance, solubility, etc., a chemical species in which one electron has been removed from the hole-transporting compound is preferred. Here, the cationic radical compound can be generated by mixing the hole-transporting compound and the electron-accepting compound. That is, by mixing the hole-transporting compound and the electron-accepting compound, electrons move from the hole-transporting compound to the electron-accepting compound, and a cationic radical containing the hole-transporting compound and a counteranion are generated. Cationic ionic compounds.

Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), PEDOT/PSS (Advanced Materials, Adv.Mater .), 2000, Vol. 12, p. 481) or aniline green (emeraldine) hydrochloride (The Journal of Chemical Physics, J. Phys. Chem., 1990, Vol. 94, p. 7716), etc. Cationic radical compounds derived from polymer compounds can also be generated by oxidative polymerization (dehydrogenation polymerization). The oxidative polymerization mentioned here is to chemically or electrochemically oxidize monomers in an acidic solution using peroxodisulfate or the like. In the case of this oxidative polymerization (dehydrogenation polymerization), the monomer is polymerized by oxidation, and an anion derived from an acidic solution is used as a counteranion to generate a cation in which one electron has been removed from the repeating unit of the polymer. free radicals.

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

The concentration of the hole transport compound in the hole injection layer forming composition is arbitrary as long as the effect of the present invention is not significantly impaired, but it is preferably low in terms of uniformity of film thickness. On the one hand, from the viewpoint that defects are less likely to occur in the hole injection layer 3, it is preferably high. Specifically, it is preferably 0.01 mass% or more, further preferably 0.1 mass% or more, particularly preferably 0.5 mass% or more, and on the other hand, it is preferably 70 mass% or less, further preferably 60 mass% or less, Particularly preferred is 50% by mass or less.

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

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, anisole, phenethyl ether, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2 , 4-dimethylanisole and other aromatic ethers, etc.

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

The hole injection layer 3 is usually formed by a wet film forming method by preparing a composition for forming the hole injection layer, and then applying it to a layer corresponding to the lower layer of the hole injection layer 3 (usually Anode 2) is applied and dried. The hole injection layer 3 is usually dried by heating or drying under reduced pressure after the film is formed.

<Formation of hole injection layer 3 by vacuum evaporation> When forming hole injection layer 3 by vacuum evaporation, the constituent material of hole injection layer 3 (the hole transport layer) is usually One or two or more kinds of chemical compounds, electron-accepting compounds, etc.) are put into a crucible placed in a vacuum container (when two or more materials are used, they are usually put into different crucibles respectively), and the After the vacuum pump exhausts the vacuum container to about 10 ^-4 Pa, the crucible is heated (when two or more materials are used, the crucibles are usually heated separately), while controlling the evaporation amount of the materials in the crucible. They are evaporated (when two or more materials are used, the evaporation amounts are usually controlled independently to evaporate) to form the hole injection layer 3 on the anode 2 on the substrate placed facing the crucible. Furthermore, when two or more materials are used, a mixture of these materials can also be put into a crucible and heated to evaporate to form the hole injection layer 3 .

As long as the effect of the present invention is not significantly impaired, the degree of vacuum during evaporation is not particularly limited, but is usually 0.1×10 ^-6 Torr (0.13×10 ^-4 Pa) or more and 9.0×10 ^-6 Torr ( 12.0×10 ^-4 Pa) or less. The vapor deposition rate is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 Å/second or more and 5.0 Å/second or less. The film-forming temperature during vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but it is preferably performed at 10°C or more and 50°C or less.

＜Hole transport layer 4＞ The hole transport layer 4 is a layer responsible for transporting holes from the anode 2 side to the light emitting layer 5 side. The hole transport layer 4 is not an essential layer for the organic electroluminescent element of the present invention, but it is preferably provided in order to enhance the function of transporting holes from the anode 2 to the light-emitting layer 5 . When the hole transport layer 4 is provided, the hole transport layer 4 is usually formed between the anode 2 and the light-emitting layer 5 . In addition, when the hole injection layer 3 is present, the hole transport layer 4 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, is usually 300 nm or less, preferably 100 nm or less.

The hole transport layer 4 may be formed by vacuum evaporation or wet film formation. In terms of excellent film-forming properties, it is preferably formed by a wet film-forming method.

The hole transport layer 4 usually contains a hole transport compound forming the hole transport layer 4 . Examples of the hole transport compound contained in the hole transport layer 4 include compounds represented by 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl. Aromatic diamines with two or more tertiary amines and two or more condensed aromatic rings substituted with nitrogen atoms (Japanese Patent Laid-Open No. 5-234681); 4,4',4''-tris(1- Naphthylphenylamino) triphenylamine and other aromatic amine compounds with starburst structures (J. Lumin., Volume 72-74, Page 985, 1997); Tetrakis containing triphenylamine Polymeric aromatic amine compounds (Chem. Commun., p. 2175, 1996); 2,2',7,7'-tetrakis-(diphenylamino)-9,9'-spiro Spirocyclic compounds such as difluorene (Synth. Metals, Volume 91, Page 209, 1997); carbazole derivatives such as 4,4'-N,N'-dicarbazolebiphenyl, etc. In addition, for example, polyarylene ether esters containing polyvinylcarbazole, polyvinyltriphenylamine (Japanese Patent Application Laid-Open No. 7-53953), and polyarylene ethertriene containing tetraphenylbenzidine (Advanced Metals Polymers for Advanced Technologies (Polym. Adv. Tech.), Volume 7, Page 33, 1996), etc.

<Formation of hole transport layer 4 by wet film formation method> When the hole transport layer 4 is formed by a wet film formation method, generally the hole transport layer forming composition is used instead of the hole injection layer 3 by the wet film formation method. The hole injection layer forming composition is formed.

When the hole transport layer 4 is formed by a wet film formation method, usually the hole transport layer forming composition further contains a solvent. The solvent used in the hole transport layer forming composition may be the same solvent as the solvent used in the hole injection layer forming composition. The concentration of the hole transport compound in the hole transport layer forming composition may be in the same range as the concentration of the hole transport compound in the hole injection layer forming composition. The hole transport layer 4 can be formed by a wet film formation method in the same manner as the hole injection layer 3 .

<Formation of hole transport layer 4 by vacuum evaporation> Regarding the case where the hole transport layer 4 is formed by vacuum evaporation, generally the same as when the hole injection layer 3 is formed by vacuum evaporation, the constituent material of the hole transport layer 4 can be used. It is formed in place of the constituent material of the hole injection layer 3 . Regarding film formation conditions such as vacuum degree, vapor deposition speed, and temperature during vapor deposition, the film can be formed using the same conditions as during vacuum vapor deposition of the hole injection layer 3 .

<Light-emitting layer 5> The light-emitting layer 5 is a layer responsible for the function of emitting light when the holes injected from the anode 2 recombine with the electrons injected from the cathode 9 and are excited when electricity is applied between a pair of electrodes. The luminescent layer 5 is a layer formed between the anode 2 and the cathode 9, and when there is a hole injection layer 3 on the anode 2, the luminescent layer 5 is formed between the hole injection layer 3 and the cathode 9. When the anode 2 is When there is a hole transport layer 4 on 2, the light-emitting layer 5 is formed between the hole transport layer 4 and the cathode 9. The light-emitting layer can be a single layer or include multiple layers.

The film thickness of the light-emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired. However, a thick film is preferable because defects are less likely to occur in the film, and on the other hand, it is easy to set a low driving voltage. In terms of thickness, it is better to be thin. Therefore, the film thickness of the light-emitting layer 5 is preferably 3 nm or more, and more preferably 5 nm or more, and on the other hand, it is generally preferably 200 nm or less, and further preferably 100 nm or less.

The light-emitting layer 5 contains at least a material having light-emitting properties (light-emitting material), and preferably further contains a material having charge-transporting properties (charge-transporting material). As a light-emitting material, as long as the iridium complex compound of the present invention is included in any light-emitting layer, other light-emitting materials may be appropriately used. In addition, two or more types of iridium complex compounds of the present invention may be included. Hereinafter, other light-emitting 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 known luminescent materials can be applied. The luminescent material may be a fluorescent luminescent material or a phosphorescent luminescent material, but a material with good luminescent efficiency is preferred. From the viewpoint of internal quantum yield, a phosphorescent luminescent material is preferred.

Examples of fluorescent light-emitting materials include the following materials. Examples of the fluorescent material that provides blue light emission (blue fluorescent material) include naphthalene, perylene, pyrene, anthracene, coumarin, p-bis(2-phenylvinyl)benzene, and the like. Some derivatives, etc. Examples of fluorescent materials that provide green emission (green fluorescent materials) include quinacridone derivatives, coumarin derivatives, aluminum complexes such as Al(C ₉ H ₆ NO) ₃ , and the like. Examples of fluorescent materials that provide yellow light emission (yellow fluorescent materials) include rubrene, perimidone derivatives, and the like. Examples of a fluorescent material that emits red light (red fluorescent material) include: DCM (4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyrene) -4H-pyran) compounds, benzopyran derivatives, rose bengal derivatives, benzothioxanthene derivatives, azabenzothioxanthene, etc.

Examples of the phosphorescent material include those selected from the long-period periodic table (hereinafter, when called “periodic table”, it refers to the long-period periodic table unless otherwise specified). Organometallic complexes of metals from Group 11 to Group 11, etc. Preferable examples of the metal selected from Groups 7 to 11 of the periodic table include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, gold, and the like.

As the ligand of the organometallic complex, a (hetero)aryl group linked to a pyridine, pyrazole, phenanthroline, etc., such as a (hetero)arylpyridine ligand or a (hetero)arylpyrazole ligand, is preferred. The resulting ligand is particularly preferably a phenylpyridine ligand and a phenylpyrazole ligand. Here, (hetero)aryl means an aryl group or a heteroaryl group.

Preferred phosphorescent materials include, specifically, tris(2-phenylpyridine)iridium, tris(2-phenylpyridine)ruthenium, tris(2-phenylpyridine)palladium, bis(2- Phenylpyridine) platinum, tris(2-phenylpyridine)osmium, tris(2-phenylpyridine)rhenium and other phenylpyridine complexes and octaethylplatinum porphyrin, octaphenylplatinum porphyrin, octaethyl Porphyrin complexes such as palladium porphyrin, octaphenylpalladium porphyrin, etc.

＜Charge transport materials＞ The charge transport material is a material that has positive charge (hole) or negative charge (electron) transport properties. There is no particular limitation as long as the effect of the present invention is not impaired, and known materials can be used. As the charge-transporting material, compounds previously used for the light-emitting layer 5 of the organic electroluminescent element can be used, and compounds used as the host material of the light-emitting layer 5 are particularly preferred.

Specific examples of the charge transport material include aromatic amine compounds, phthalocyanine compounds, porphyrin compounds, oligothiophene compounds, polythiophene compounds, benzylphenyl compounds, and fluorenyl-linked compounds. Compounds made of tertiary amines, hydrazone compounds, silazane compounds, silane amine compounds, phosphatamide compounds, quinacridone compounds, etc. are exemplified as the hole transport compound of the hole injection layer 3 Compounds, etc. In addition, electron-transporting compounds such as anthracene-based compounds, pyrene-based compounds, carbazole-based compounds, pyridine-based compounds, phenanthroline-based compounds, oxadiazole-based compounds, and silole-based compounds can also be cited.

In addition, for example, it is also preferable to use: 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl containing two or more tertiary amines and two or more An aromatic diamine whose condensed aromatic ring is substituted with a nitrogen atom (Japanese Patent Application Publication No. 5-234681); 4,4',4''-tris(1-naphthylphenylamino)triphenylamine and other aromatic amine compounds having a starburst structure (J. Lumin., vol. 72-74, page 985, 1997); aromatic amine compounds containing a tetramer of triphenylamine (Chemistry Chem. Commun., page 2175, 1996); 2,2',7,7'-tetrakis-(diphenylamino)-9,9'-spirobifluorene and other fluorene compounds (synthetic metal (Synth. Metals), Vol. 91, p. 209, 1997); carbazole compounds such as 4,4'-N,N'-dicarbazolebiphenyl, etc. are used as hole transport compounds of the hole transport layer 4 Illustrated compounds, etc. In addition, 2-(4-biphenyl)-5-(p-tert-butylphenyl)-1,3,4-oxadiazole (tBu-PBD), 2,5-bis( 1-Naphthyl)-1,3,4-oxadiazole (BND) and other oxadiazole compounds; 2,5-bis(6'-(2',2''-bipyridyl))-1, Silole compounds such as 1-dimethyl-3,4-diphenylsilole (PyPySPyPy); 4,7-diphenyl-1,10-phenanthroline (BPhen), 2,9-dimethyl Phenyl-4,7-diphenyl-1,10-phenanthroline (bathocuproin, BCP) and other phenanthroline compounds.

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

When the light-emitting layer 5 is formed by a wet film-forming method, generally similar to the case of forming the hole injection layer 3 by a wet film-forming method, a material that forms the light-emitting layer 5 and a soluble material are used. A composition for forming a light-emitting layer prepared by mixing a solvent (solvent for a light-emitting layer) is formed in place of the composition for forming a hole injection layer.

Examples of the solvent include, in addition to the ether solvents, ester solvents, aromatic hydrocarbon solvents, and amide solvents listed for the formation of the hole injection layer 3, alkane solvents, and halogenated aromatic hydrocarbon solvents. , aliphatic alcohol solvents, alicyclic alcohol solvents, aliphatic ketone solvents and alicyclic ketone solvents, etc. The solvent used is as exemplified as the solvent of the ink for the light-emitting layer containing the iridium complex compound of the present invention. Specific examples of the solvent are listed below, but they are not limited to these as long as the effects of the present invention are not impaired. some.

Examples include: aliphatic ether solvents such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA); 1,2-dimethoxybenzene, 1,3 -Dimethoxybenzene, anisole, phenylethyl ether, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4- Aromatic ether solvents such as dimethyl anisole and diphenyl ether; aromatic solvents such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, n-butyl benzoate, etc. Ester solvents; toluene, xylene, mesitylene, cyclohexylbenzene, tetralin, 3-isopropylbiphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropyl Aromatic hydrocarbon solvents such as benzene and methylnaphthalene; amide solvents such as N,N-dimethylformamide and N,N-dimethylacetamide; n-decane, cyclohexane, and ethyl cyclohexane Alkane solvents such as hexane, decalin, and bicyclohexane; halogenated aromatic hydrocarbon solvents such as chlorobenzene, dichlorobenzene, and trichlorobenzene; aliphatic alcohol solvents such as butanol and hexanol; cyclohexane Alicyclic alcohol solvents such as alcohol and cyclooctanol; aliphatic ketone solvents such as methyl ethyl ketone and dibutyl ketone; alicyclic ketone solvents such as cyclohexanone, cyclooctanone, and fentanone, etc. Among these, alkane-based solvents and aromatic hydrocarbon-based solvents are particularly preferred.

In addition, in order to obtain a more uniform film, it is preferable that the solvent evaporates from the liquid film just after film formation at an appropriate speed. Therefore, the boiling point of the solvent used is as described above, and is usually 80°C or higher, preferably 100°C or higher, more preferably 120°C or higher, usually 270°C or lower, preferably 250°C or lower, and more preferably 230°C. below ℃.

The amount of solvent used is arbitrary as long as the effect of the present invention is not significantly impaired. However, the total content in the ink for the light-emitting layer, that is, the ink for the light-emitting layer containing the iridium complex compound is easy to use because of its low viscosity. In terms of performing a film forming operation, it is preferable that it is high, and on the other hand, in terms of making it easy to form a thick film, it is preferable that it is low. As mentioned above, the content of the solvent in the ink for the light-emitting layer containing the iridium complex compound is preferably 1 mass % or more, more preferably 10 mass % or more, particularly preferably 50 mass % or more, and more preferably 99.99 mass % % or less, more preferably 99.9 mass % or less, particularly preferably 99 mass % or less.

As a solvent removal method after wet film formation, heating or pressure reduction can be used. As the heating means used in the heating method, a clean oven or a heating plate is preferred in terms of uniformly supplying heat to the entire film. The heating temperature in the heating step is arbitrary as long as the effect of the present invention is not significantly impaired. However, in terms of shortening the drying time, a high temperature is preferred, and in terms of causing less damage to the material, a high temperature is preferred. Because the temperature is low. The upper limit of the heating temperature is usually 250°C or lower, preferably 200°C or lower, and further preferably 150°C or lower. The lower limit of the heating temperature is usually 30°C or higher, preferably 50°C or higher, and further preferably 80°C or higher. A temperature exceeding the upper limit is undesirable because it has higher heat resistance than commonly used charge transport materials or phosphorescent materials and may cause decomposition or crystallization. If the lower limit is less than the above-mentioned lower limit, removal of the solvent requires a long time, which is undesirable. The heating time in the heating step can be appropriately determined based on the boiling point or vapor pressure of the solvent in the ink for the light-emitting layer, the heat resistance of the material, and the heating conditions.

<Formation of light-emitting layer 5 by vacuum evaporation> In addition to the light-emitting layer formed from the light-emitting layer ink of the present invention containing an iridium complex compound, other light-emitting layers may be laminated to form a multi-layered light-emitting layer. At this time, the vacuum evaporation method can be used among other formation methods of the light-emitting layer. When the light-emitting layer 5 is formed by vacuum evaporation, one or more of the constituent materials of the light-emitting layer 5 (the light-emitting material, the charge transport compound, etc.) are usually placed in a vacuum container. in a crucible (when two or more materials are used, they are usually placed in different crucibles), use a vacuum pump to exhaust the vacuum container to about 10 ^-4 Pa, and then heat the crucible (when using two or more materials, they are usually placed in different crucibles). When more than two materials are used, the crucible is usually heated separately) and the evaporation amount of the material in the crucible is controlled while evaporating (when two or more materials are used, the evaporation amount is usually controlled independently to evaporate the material). (evaporates), forming a light-emitting layer 5 on the hole injection layer 3 or hole transport layer 4 placed facing the crucible. Furthermore, when two or more materials are used, the mixture may be put into a crucible and heated to evaporate to form the light-emitting layer 5 .

The degree of vacuum during evaporation is not limited as long as the effect of the present invention is not significantly impaired, but it is usually 0.1×10 ^-6 Torr (0.13×10 ^-4 Pa) or more and 9.0×10 ^-6 Torr (12.0×10 ^{- 4} Pa) or less. The vapor deposition rate is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 Å/second or more and 5.0 Å/second or less. The film forming temperature during vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but it is preferably carried out at 10°C or more and 50°C or less.

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

The hole blocking layer 6 has the function of blocking the holes moving from the anode 2 from reaching the cathode 9 and transmitting the electrons injected from the cathode 9 to the direction of the light-emitting layer 5 efficiently. Physical properties required for the material constituting the hole blocking layer 6 include high electron mobility and low hole mobility, and the difference between the energy gap (HOMO and lowest unoccupied molecular orbital (LUMO)). ) is large and the excited triplet energy level (T1) is high.

Examples of materials for the hole blocking layer 6 that satisfy such conditions include: bis(2-methyl-8-hydroxyquinoline)(phenol)aluminum, bis(2-methyl-8-hydroxyquinoline)( Mixed coordination complexes such as bis(2-methyl-8-quinolinolato)(triphenyl silanolato)aluminum, bis(2-methyl-8-hydroxyquinoline)aluminum-μ- Metal complexes such as oxo-bis-(2-methyl-8-hydroxyquinoline) aluminum dinuclear metal complex, styryl compounds such as distyryl biphenyl derivatives (Japanese Patent Application Laid-Open No. 11- 242996), 3-(4-biphenyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole and other triazole derivatives (Japan Patent No. Kaihei No. 7-41759), phenanthroline derivatives such as bathocuproin (Japanese Patent Application Publication No. 10-79297), etc. Furthermore, a compound having at least one pyridine ring substituted at positions 2, 4, and 6 described in International Publication No. 2005/022962 is also suitable as the material for the hole blocking layer 6 .

The formation method of the hole blocking layer 6 is not limited, and it can be formed in the same manner as the formation method of the light-emitting layer 5 . As long as the effect of the present invention is not significantly impaired, the film thickness of the hole blocking layer 6 is arbitrary, but is usually 0.3 nm or more, preferably 0.5 nm or more, and is usually 100 nm or less, preferably 50 nm. the following.

<Electron transport layer 7> For the purpose of further improving the current efficiency of the element, 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 . The electron transport layer 7 is formed of a compound that can efficiently transport electrons injected from the cathode 9 to the direction of the light-emitting layer 5 between electrodes to which electricity is provided. The electron-transporting compound used in the electron-transporting layer 7 needs to be a compound that has high electron injection efficiency from the cathode 9 or the electron-injection layer 8 , has high electron mobility, and can efficiently transport the injected electrons.

Specific examples of electron-transporting compounds that satisfy such conditions include metal complexes such as aluminum complexes of 8-hydroxyquinoline (Japanese Patent Laid-Open No. Sho 59-194393). , 10-hydroxybenzo[h]quinoline metal complex, oxadiazole derivatives, distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complex, 5 -Hydroxyflavone metal complex, benzoxazole metal complex, benzothiazole metal complex, triphenzimidazolylbenzene (US Patent No. 5645948), quinoxaline compound (Japanese Patent Laid-Open No. 6 -207169), phenanthroline derivatives (Japanese Patent Application Laid-Open No. 5-331459), 2-tert-butyl-9,10-N,N'-dicyananthraquinonediimide, n-type hydrogenation Amorphous silicon carbide, n-type zinc sulfide, n-type zinc selenide, etc.

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, is usually 300 nm or less, preferably 100 nm or less. The electron transport layer 7 is formed by laminating the light-emitting layer 5 or the hole blocking layer 6 by a wet film forming method or a vacuum evaporation method in the same manner as the light-emitting layer 5 . Vacuum evaporation is usually 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. As examples, alkali metals such as sodium and cesium, alkaline earth metals such as barium and calcium, and the like can be used. The film thickness of the electron injection layer 8 is preferably 0.1 nm to 5 nm.

In addition, inserting an extremely thin insulating film (film thickness about 0.1 nm to 5 nm) such as LiF, MgF ₂ , Li ₂ O, Cs ₂ CO ₃ as the electron injection layer 8 at the interface between the cathode 9 and the electron transport layer 7 is also an improvement. An effective method for improving the efficiency of components (Appl. Phys. Lett., Vol. 70, p. 152, 1997; Japanese Patent Application Laid-Open No. 10-74586; IEEE Transactions on Electronic Devices, IEEE Trans. Electron. Devices), Volume 44, Page 1245, 1997; Society for Information Display (SID) 04 Digest, Page 154). Furthermore, organic electron transport is represented by nitrogen-containing heterocyclic compounds such as 4,7-diphenyl-1,10-phenanthroline or metal complexes such as aluminum complexes of 8-hydroxyquinoline. The material is doped with alkali metals such as sodium, potassium, cesium, lithium, and rubidium (described in Japanese Patent Laid-Open No. 10-270171, Japanese Patent Laid-Open No. 2002-100478, Japanese Patent Laid-Open No. 2002-100482, etc.), It is preferable because it has excellent film quality with improved electron injection properties and improved transport properties. 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.

Like the light-emitting layer 5, the electron injection layer 8 is formed by being laminated on the light-emitting layer 5 or the hole blocking layer 6 or the electron transport layer 7 thereon by a wet film forming method or a vacuum evaporation method. The details in the case of the wet film formation method are the same as in the case of the light-emitting layer 5 .

＜Cathode 9＞ The cathode 9 functions to inject electrons into a layer on the light-emitting layer 5 side (electron injection layer 8 or light-emitting layer 5 , etc.). As the material of the cathode 9, the material used for the anode 2 can be used. However, in terms of efficiently injecting electrons, it is preferable to use a metal with a low work function. For example, tin, magnesium, indium, Calcium, aluminum, silver and other metals or their alloys, etc. Specific examples include low work function alloy electrodes such as magnesium-silver alloys, magnesium-indium alloys, and aluminum-lithium alloys.

In terms of the stability of the element, it is preferable to laminate a metal layer with a high work function and stable to the atmosphere on the cathode 9 to protect the cathode 9 containing a metal with a low work function. Examples of laminated metals 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 structural layers＞ The above description has centered on the element with the layer structure shown in FIG. 1 . However, between the anode 2 and the cathode 9 and the light-emitting layer 5 of the organic electroluminescent element of the present invention, as long as the performance is not impaired, there are other In addition to the layers described above, any layer may be provided, and any layer other than the light-emitting layer 5 may be omitted.

For example, for the same purpose as the hole blocking layer 6, it is also effective to provide an electron blocking layer between the hole transport layer 4 and the light emitting layer 5. The electron blocking layer has the following functions: by blocking electrons moving from the luminescent layer 5 from reaching the hole transport layer 4, it increases the probability of recombination with holes in the luminescent layer 5, and confines the generated excitons in the luminescent layer 5. and the function of efficiently transporting the holes injected from the hole transport layer 4 toward the direction of the light-emitting layer 5 .

Characteristics required for an electron blocking layer include high hole transportability, a large energy gap (difference between HOMO and LUMO), and a high excited triplet energy level (T1). In addition, when the light-emitting layer 5 is formed by a wet film-forming method, it is preferable that the electron blocking layer is also formed by a wet film-forming method because element manufacturing becomes easier. Therefore, the electron blocking layer is preferably also suitable for wet film formation. As a material used in such an electron blocking layer, a copolymer of dioctylfluorene and triphenylamine represented by F8-TFB can be cited. (International Publication No. 2004/084260) etc.

Furthermore, the opposite structure to that shown in Figure 1 is also possible, that is, the cathode 9, the electron injection layer 8, the electron transport layer 7, the hole blocking layer 6, the light emitting layer 5, and the hole transport layer 4 are sequentially stacked on the substrate 1 , the hole injection layer 3 and the anode 2, the organic electroluminescent element of the present invention can also be disposed between at least one of two substrates with high transparency. Furthermore, a structure in which a plurality of layers of the layer structure shown in FIG. 1 is superimposed (a structure in which a plurality of light-emitting units are stacked) may be adopted. At this time, if V ₂ O ₅ or the like is used as a charge generation layer instead of the interface layer between levels (between light-emitting units) (the anode is indium tin oxide (ITO) and the cathode is Al, it means that These two layers), there will be fewer barriers between levels, which will be better from the viewpoint of luminous efficiency and driving voltage.

The present invention is applicable to any of the organic electroluminescent elements that are single elements, elements that have a structure arranged in an array, or structures that have an anode and a cathode arranged in an X-Y matrix.

＜Display device and lighting device＞ A display device (hereinafter referred to as the "display device of the present invention") and a lighting device (hereinafter referred to as the "illuminating device of the present invention") can be manufactured using the organic electroluminescent element of the present invention as described above. There are no particular restrictions on the form or structure of the display device and lighting device of the present invention. The organic electroluminescent element of the present invention can be used and assembled according to conventional methods. For example, the display of the present invention can be formed by the method described in "Organic EL Display" (Ohmsha, published on August 20, 2004, written by Seishi Toto, Chihaya Adachi, and Hideyuki Murata) Fixtures and lighting fixtures.

＜＜Manufacturing method of organic electroluminescent element>> The manufacturing method of the organic electroluminescent device of the present invention is not particularly limited, but preferably includes the following steps: using a composition for a light-emitting layer containing an organic solvent and forming a light-emitting layer by a wet film forming method. In one aspect, the manufacturing method of the organic electroluminescent element based on the present invention is preferably: a method of manufacturing an organic electroluminescent element having an anode, a luminescent layer and a cathode in sequence on a substrate, and includes using an organic electroluminescent element containing The step of forming the light-emitting layer by a wet film-forming method using the composition for the light-emitting layer of a solvent.

In addition, in another aspect, the method for manufacturing an organic electroluminescent element based on the present invention is preferably: a method for manufacturing an organic electroluminescent element having an anode, a luminescent layer and a cathode in sequence on a substrate, and includes The step of forming the light-emitting layer by evaporation using the composition for the light-emitting layer. [Example]

Hereinafter, an Example is shown and this invention is demonstrated more concretely. However, the present invention is not limited to the following examples, and the present invention can be implemented with any modifications without departing from the gist of the present invention.

<Measurement of Maximum Luminescence Wavelength> An iridium complex compound was dissolved in toluene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., for spectroscopic analysis) at room temperature to prepare a 1×10 ^-5 mol/L solution. The solution was placed in a quartz cell equipped with a Teflon (registered trademark) stopper, and nitrogen bubbling was performed for more than 20 minutes, and then the phosphorescence spectrum was measured at room temperature. The wavelength showing the maximum value of the obtained phosphorescence spectrum intensity was regarded as the maximum emission wavelength.

In addition, the following equipment was used for the measurement of the emission spectrum. Device: Organic EL quantum yield measurement device C9920-02 manufactured by Hamamatsu Photonics Light source: Monochromatic light source L9799-01 Detector: Multi-channel detector PMA-11 Excitation light: 380 nm

[Measurement of photoluminescence (PL) quantum yield] As the luminous efficiency, the PL quantum yield was measured. The PL quantum yield is an index showing how efficiently the light (energy) absorbed by the material can emit light, and is measured using the following equipment as described above. Device: Organic EL quantum yield measurement device C9920-02 manufactured by Hamamatsu Photonics Light source: Monochromatic light source L9799-01 Detector: Multi-channel detector PMA-11 Excitation light: 380 nm

＜Synthesis of iridium complex compounds＞ Furthermore, in the following synthesis examples, the reactions were all carried out under nitrogen flow. The solvent or solution used in the reaction must be degassed by an appropriate method such as nitrogen bubbling.

<Synthesis Example 1: Synthesis of D-1>

[Chemistry 22]

Put 3,5-dibromoanisole (25.0 g), m-terphenyl-3-boronic acid (59.9 g), and tetrakis(triphenylphosphine)palladium (0) (5.2 g) into a 1 L eggplant-shaped flask. ), 2 M tripotassium phosphate aqueous solution (250 mL), toluene (300 mL) and ethanol (100 mL), reflux and stir in an oil bath at 105°C for 8 hours. After cooling to room temperature, the water phase was removed and the solvent was removed under reduced pressure. The obtained residue was purified by silica gel column chromatography (methylene chloride/hexane = 1/3~35/65). The result was: 52.0 g of intermediate 1 were obtained in the form of a white amorphous substance.

[Chemistry 23]

Put Intermediate 1 (25.8 g) and dichloromethane (150 mL) into a 1 L eggplant-shaped flask, immerse it in a dry ice/ethanol bath for cooling, and add 1 M-tribromide dropwise from the dropping funnel over 25 minutes. Boron/dichloromethane solution (100 mL). After further stirring for 20 minutes, the bath liquid was removed and the mixture was further stirred at room temperature for 1.5 hours. After adding water (200 mL) for liquid separation and cleaning, the mixture was passed through a silica column (methylene chloride). As a result, 26.0 g of demethoxylated product was obtained in the form of white amorphous material. Then, put the entire amount of the demethoxylated product, methylene chloride (200 mL) and triethylamine (7.9 mL) into a 1 L eggplant-shaped flask, and cool it in an ice-water bath for 25 minutes. A solution of trifluoromethanesulfonic anhydride (15.9 g) in dichloromethane (10 mL) was added dropwise from the dropping funnel. After stirring at room temperature for 1 hour, a solution of sodium carbonate (2.6 g) in water (200 mL) was added for liquid separation and washing. The oil phase was recovered and dried under reduced pressure. The obtained residue was purified by silica gel column chromatography (methylene chloride/hexane = 5/95~2/8). As a result, 25.4 g was obtained as a white solid. The intermediate 2.

[Chemistry 24]

In a 1 L eggplant-shaped flask, put 3-(2-pyridyl)phenylboronic acid pinacol ester (6.7 g), intermediate 2 (13.6 g), tetrakis(triphenylphosphine)palladium (0) (1.2 g), 2 M tripotassium phosphate aqueous solution (25 mL), toluene (70 mL) and ethanol (30 mL), and stir under reflux for 3.5 hours. After cooling to room temperature, the water phase was removed and the solvent was removed under reduced pressure. The obtained residue was refined by silica gel column chromatography (methylene chloride/hexane = 35/65~6/4). The result was: 13.3 g of ligand 1 was obtained in the form of white amorphous material.

[Chemical 25]

In a 200 mL eggplant-shaped flask including a Dimroth with a side tube, add ligand 1 (12.0 g), tris(acetylacetone)iridium(III) (2.2 g), and glycerin (14.0 g) and cyclohexylbenzene (1 mL), and immersed in an oil bath preheated to 90°C. After raising the temperature of the oil bath to 210°C, it took 2 hours to raise the temperature of the oil bath to 240°C. At this temperature The mixture was further stirred for 6.5 hours. After cooling to room temperature, use water (50 mL) and dichloromethane (100 mL) for liquid separation and washing. The oil phase was dried under reduced pressure, and the obtained residue was purified by silica column chromatography (methylene chloride/hexane = 1/1). As a result, 4.1 g of D-1 was obtained as a yellow solid. The maximum luminescence wavelength of D-1 in the toluene solution is 516 nm, and the photoluminescence quantum yield (PLQY) is 94%.

<Synthesis Example 2: Synthesis of D-2>

[Chemical 26]

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

[Chemical 27]

Put Intermediate 3 (38.3 g) and dichloromethane (330 mL) into a 1 L eggplant-shaped flask, immerse it in a dry ice/ethanol bath for cooling, and add 1 M-tribromide dropwise from the dropping funnel over 30 minutes. Boron/dichloromethane solution (100 mL). After further stirring for 25 minutes, the bath liquid was removed and the mixture was further stirred at room temperature for 95 minutes. After adding water (200 mL) for liquid separation and washing, the oil phase was passed through magnesium sulfate (methylene chloride). As a result, 37.5 g of a crude product containing a demethoxylated product was obtained. Immediately afterwards, the entire amount of the crude product, methylene chloride (330 mL) and triethylamine (15.0 mL) were put into a 1 L eggplant-shaped flask, and the solution was allowed to drip over 30 minutes while cooling in an ice-water bath. A solution of trifluoromethanesulfonic anhydride (30.3 g) in dichloromethane (20 mL) was added dropwise from the funnel. After stirring at room temperature for 40 minutes, a solution of sodium carbonate (2.8 g) in water (200 mL) was added for liquid separation and washing. The oil phase was recovered and dried under reduced pressure. The obtained residue was purified by silica gel column chromatography (methylene chloride/hexane = 0/1 to 2/8). As a result, 41.8 g was obtained as a white solid. The intermediate 4.

[Chemical 28]

Put intermediate 4 (41.8 g), dipinopinacol diboron (24.3 g), potassium acetate (23.6 g), [Pd(dppf) ₂ Cl ₂ ]CH ₂ Cl ₂ ( 2.0 g) and dimethylstyrene (390 mL), stir in an oil bath at 90°C for 4 hours. After cooling to room temperature, water (400 mL) and dichloromethane (150 mL) were added for liquid separation and washing. After drying with magnesium sulfate, the solvent was removed under reduced pressure, and the obtained residue was subjected to silica column chromatography. Purification was carried out using the method (dichloromethane/hexane/ethyl acetate = 3/7/0~1/1/0~0/9/1), and intermediate 5 (28.5 g) was obtained as a white solid.

[Chemical 29]

In a 1 L eggplant-shaped flask, put 3,5-dibromoanisole (6.9 g), intermediate 5 (28.5 g), tetrakis(triphenylphosphine)palladium (0) (1.2 g), 2 M- Tripotassium phosphate aqueous solution (70 mL), toluene (120 mL) and ethanol (60 mL) were refluxed and stirred in an oil bath at 105°C for 4 hours. After cooling to room temperature, the water phase was removed and the solvent was removed under reduced pressure. The obtained residue was purified by silica gel column chromatography (methylene chloride/hexane = 4/6). The result was white amorphous. 22.3 g of intermediate 6 were obtained.

[Chemical 30]

Put Intermediate 6 (22.3 g) and dichloromethane (120 mL) into a 1 L eggplant-shaped flask, immerse it in a dry ice/ethanol bath for cooling, and add 1 M-tribromide dropwise from the dropping funnel over 30 minutes. Boron/dichloromethane solution (28.2 mL). After further stirring for 30 minutes, the bath liquid was removed and the mixture was further stirred at room temperature for 3 hours. After adding water (150 mL) for separation and washing, the mixture was passed through magnesium sulfate (methylene chloride) to obtain 21.3 g of a crude product containing a demethoxylated product. Immediately afterwards, the entire amount of the crude product, methylene chloride (135 mL) and triethylamine (3.8 mL) were put into a 1 L eggplant-shaped flask, and the solution was allowed to drip over 30 minutes while cooling in an ice-water bath. A solution of trifluoromethanesulfonic anhydride (7.5 g) in dichloromethane (5 mL) was added dropwise from the funnel. After stirring at room temperature for 30 minutes, a solution of sodium carbonate (2.6 g) in water (200 mL) was added for liquid separation and washing. The oil phase was recovered and dried under reduced pressure. The obtained residue was purified by silica gel column chromatography (methylene chloride/hexane = 3/7). As a result, 22.4 g of white solid was obtained. According to ¹ H-nuclear magnetic resonance ( ¹ H-NMR), it was found to be a mixture of hexane and intermediate 7 (net weight 21.2 g).

[Chemical 31]

In a 1 L eggplant-shaped flask, 3-(2-pyridyl)phenylboronic acid pinacol ester (4.3 g), crude product containing intermediate 7 (13.3 g), tetrakis(triphenylphosphine)palladium ( 0) (0.33 g), 2 M tripotassium phosphate aqueous solution (16 mL), toluene (60 mL) and ethanol (30 mL), stir 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 obtained residue was purified by silica gel column chromatography (methylene chloride/hexane = 4/6~8/2). The result was: 12.4 g of ligand 2 was obtained in the form of white amorphous material.

[Chemical 32]

In a 200 mL eggplant-shaped flask including a Daisch with a side tube, place ligand 2 (11.3 g), tris(acetyl acetone)iridium(III) (1.4 g), glycerol (13.2 g) and cyclohexyl Benzene (0.25 mL), increase the temperature of the oil bath to 235°C, and stir for 14.5 hours. After cooling to room temperature, use water (50 mL) and dichloromethane (100 mL) for liquid separation and washing. The oil phase was dried under reduced pressure, and the obtained residue was purified by silica gel column chromatography (methylene chloride/hexane = 4/6 to 1/1). As a result, 1.3 g was obtained as a yellow solid. D-2. The maximum luminescence wavelength of D-2 in the toluene solution is 514 nm, and the PLQY is 91%.

<Synthesis Example 3: Synthesis of ND-1>

[Chemical 33]

Put 3-(2-pyridyl)phenylboronic acid pinacol ester (7.9 g), 3-bromo-3'-iodo-1,1'-biphenyl (10.6 g) into a 300 mL eggplant-shaped flask. Tetrakis(triphenylphosphine)palladium(0) (0.72 g), 2 M tripotassium phosphate aqueous solution (35 mL), toluene (60 mL) and ethanol (30 mL) were stirred under reflux for 5 hours. After cooling to room temperature, the water phase was removed and the solvent was removed under reduced pressure. The obtained residue was purified by silica gel column chromatography (methylene chloride/hexane = 1/1 to 8/2). The result was: 8.7 g of intermediate 8 was obtained as a brown amorphous substance.

[Chemical 34]

Put intermediate 8 (8.7 g), m-terphenyl-3-boronic acid (8.9 g), tetrakis(triphenylphosphine)palladium (0) (0.65 g), and 2 M-phosphoric acid into a 1 L eggplant-shaped flask. Tripotassium aqueous solution (30 mL), toluene (60 mL) and ethanol (30 mL) were refluxed and stirred for 4 hours. After cooling to room temperature, the aqueous phase was removed and the solvent was removed under reduced pressure. The obtained residue was purified by silica gel column chromatography (dichloromethane/hexane=1/1~1/0). The result was: 11.5 g of ligand 3 was obtained in the form of colorless amorphous material.

[Chemical 35]

In a 200 mL three-necked flask including a Daisch with a side tube, put Coordinator 3 (6.5 g), iridium (III) chloride hydrate (manufactured by Furuya Metals, 2.0 g), Water (20 mL) and 2-ethoxyethanol (60 mL) were stirred in an oil bath at 145°C while distilling off the solvent. Halfway through, 2.5 hours after the reaction started, the oil bath temperature was set to 150°C. 5 hours after the reaction started, 2-ethoxyethanol (80 mL) was added. At the same time, the oil bath temperature was set to 155°C. 7 hours after the reaction started. After 1 hour, add diglylene glycol (30 mL). After 15 minutes, a solution of ethyldiisopropylamine (1 mL) in 2-ethoxyethanol (5 mL) was added, and 15 minutes after this, diglylene glycol (10 mL) and 2 -ethoxyethanol (20 mL), stir for 3 hours, then increase the temperature of the oil bath to 160°C and stir for 7 hours. The volume of liquid removed by distillation during the reaction was 170 mL. After cooling to room temperature, remove under reduced pressure, and the obtained residue is refined by silica gel column chromatography (methylene chloride/hexane/ethyl acetate = 45/45/10~8/0/2). As a result, 8.4 g of yellow amorphous material was obtained. ¹ H-NMR analysis revealed that the obtained yellow amorphous substance contained ethyl acetate, and that the product contained 6.7 g of binuclear complex 1.

[Chemical 36]

In a 200 mL eggplant-shaped flask, put the amorphous substance containing binuclear complex 1 (8.4 g), ligand 1 (5.0 g), and diglylene glycol (20 mL) obtained in the above reaction. After stirring and dissolving in an oil bath at 135°C, silver (I) trifluoromethanesulfonate (1.4 g) was added, the temperature of the oil bath was set to 140°C, and the mixture was stirred for 2 hours. Then, the solvent was removed under reduced pressure, and the obtained residue was purified by silica gel column chromatography (methylene chloride/hexane = 1/1). As a result, 5.2 g of ND-1 was obtained as a yellow solid. The maximum luminescence wavelength of ND-1 in toluene solution is 516 nm, and the PLQY is 96%.

<Synthesis Example 4: Synthesis of ND-2>

[Chemical 37]

Put 3-(2-pyridyl)phenylboronic acid pinacol ester (7.3 g), 3-bromo-4'-iodo-1,1'-biphenyl (9.5 g) into a 300 mL eggplant-shaped flask. Tetrakis(triphenylphosphine)palladium(0) (0.62 g), 2 M tripotassium phosphate aqueous solution (35 mL), toluene (50 mL) and ethanol (35 mL) were 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 obtained residue was purified by silica gel column chromatography (dichloromethane/hexane=1/1~1/0). The result was: 10.0 g of intermediate 9 was obtained in the form of brown amorphous material.

[Chemical 38]

In a 1 L eggplant-shaped flask, put intermediate 9 (28.7 g), dipinopinacol diboron (23.7 g), potassium acetate (36.9 g), [Pd(dppf) ₂ Cl ₂ ]CH ₂ Cl ₂ ( 1.8 g) and dimethylstyrene (250 mL), stir in an oil bath at 90°C for 3 hours. After cooling to room temperature, water (0.5 L) and dichloromethane (0.3 L) were added for liquid separation and washing. After drying with magnesium sulfate, the solvent was removed under reduced pressure, and the obtained residue was subjected to silica gel column chromatography. Purification was carried out using the method (ethyl acetate/hexane = 1/9 to 15/85), and Intermediate 10 (30.1 g) was obtained as a light yellow solid.

[Chemical 39]

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

[Chemical 40]

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

[Chemical 41]

In a 200 mL three-necked flask including a Daisch with a side tube, put Coordinator 4 (10.2 g), iridium (III) chloride hydrate (manufactured by Furuya Metals, 2.76 g), Water (25 mL) and 2-ethoxyethanol (125 mL) were stirred in an oil bath at 140°C while distilling off the solvent. Halfway through, after 2.5 hours, diglycerene (40 mL) was added, and the oil bath was set to 150°C. Furthermore, 2-ethoxyethanol (35 mL) was added after 2 hours, and the oil bath was set to 155°C. Then, after 4 hours, a solution of ethyldiisopropylamine (1.5 mL) in diglyceryl ether (2.5 mL) was added, and after 1 hour, a solution of ethyldiisopropylamine (1.5 mL) in diglycerin was added. dimethyl ether (2.5 mL) solution and stirred for 2 hours. The volume of liquid removed by distillation during the reaction was 140 mL. After cooling to room temperature, the solution was removed under reduced pressure. The obtained residue was purified by silica gel column chromatography (dichloromethane/hexane = 4/6~3/7). The result was golden amorphous. 6.7 g of dinuclear complex 2 was obtained.

[Chemical 42]

Put binuclear complex 2 (6.7 g), ligand 2 (8.0 g), and diglylene glycol (20 mL) into a 200 mL eggplant-shaped flask, and stir to dissolve in an oil bath at 135°C. Then, silver (I) trifluoromethanesulfonate (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. Then, the solvent was removed under reduced pressure, and the obtained residue was purified by silica gel column chromatography (methylene chloride/hexane = 1/1). As a result, 7.7 g of compound ND-2 was obtained as a yellow solid. . The maximum luminescence wavelength of ND-2 in toluene solution is 519 nm, and the PLQY is 94%.

[Example 1] An organic electroluminescent device is produced by the following method. For those in which an indium tin oxide (ITO) transparent conductive film is deposited on a glass substrate to a thickness of 50 nm (manufactured by Geomatec, a sputtered film product), ordinary photolithography techniques and hydrochloric acid etching are used. And patterned into 2 mm wide stripes, thus forming the anode. The substrate on which ITO is patterned in the above manner is cleaned in this order: ultrasonic cleaning with a surfactant aqueous solution, water washing with ultrapure water, ultrasonic cleaning with ultrapure water, and water washing with ultrapure water. , use compressed air to dry it, and finally perform ultraviolet ozone cleaning.

As a composition for forming a hole injection layer, 3.0 mass% of a hole transporting polymer compound having a repeating structure of the following formula (P-1) and 0.6 mass% of an electron-accepting compound (HI-1) were dissolved in Composition made from ethyl benzoate.

[Chemical 43]

The solution was spin-coated on the substrate in the atmosphere, and dried on a hot plate at 240° C. for 30 minutes in the atmosphere to form a uniform thin film with a thickness of 40 nm, which was used as the 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 mass% solution. The solution was spin-coated on the substrate coated with the hole injection layer in a nitrogen glove box, and dried at 230° C. for 30 minutes using a heating plate in the nitrogen glove box to form a uniform film thickness of 40 nm. thin film as a hole transport layer.

[Chemical 44]

Next, as materials for the light-emitting layer, the compound (H-1) having the following structure was used at a concentration of 1.35 mass%, the compound (H-2) was used at a concentration of 1.35 mass%, and the compound (H-3) was used at a concentration of 2.7 The compound (Ir-D1) was dissolved in cyclohexylbenzene at a concentration of 0.8 mass%, and the compound (Ir-ND1) was dissolved in cyclohexylbenzene at a concentration of 0.8 mass% to prepare the ink for the light-emitting layer of the present invention.

[Chemical 45]

[Chemical 46]

[Chemical 47]

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

Next, the following structural formula (ET-1) and lithium 8-hydroxyquinolate were co-evaporated on the light-emitting layer at a film thickness ratio of 2:3 by vacuum evaporation to form an electron transport layer with a film thickness of 30 nm. .

[Chemical 48]

Then, as a mask for cathode evaporation, a striped shadow mask with a width of 2 mm is closely connected to the substrate so that it is orthogonal to the ITO stripes of the anode, and the aluminum is heated with a molybdenum boat to form a film. An 80 nm thick aluminum layer forms the cathode. Operating in the described manner, an organic electroluminescent element having a light-emitting area portion of 2 mm×2 mm size was obtained.

[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 the compound (Ir-D2) having the following structure was used instead of (Ir-D1), it was produced in the same manner as in Example 1. Electromechanical luminescent components.

[Chemical 49]

[Example 3] Except for using the ink for the light-emitting layer of the present invention in which the compound (Ir-ND2) having the following structure was used instead of (Ir-ND1) as the ink for the light-emitting layer, it was produced in the same manner as in Example 1. Electromechanical luminescent components.

[Chemical 50]

[Example 4] An organic electroluminescent element 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 element was produced in the same manner as in Example 1, except that the ink for the light-emitting layer was used as the ink for the light-emitting layer in which (Ir-D2) was used instead of (Ir-ND1).

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

[Comparative example 3] In addition to using a luminescent layer ink that uses 1.6 mass% (Ir-D1) instead of 0.8 mass% (Ir-D1) and 0.8 mass% (Ir-ND1), , an organic electroluminescent element was produced in the same manner as in Example 1.

[Comparative example 4] In addition to using a luminescent layer ink that uses 1.6 mass% (Ir-D2) instead of 0.8 mass% (Ir-D2) and 0.8 mass% (Ir-ND1), , an organic electroluminescent element was produced in the same manner as in Example 2.

[Comparative example 5] In addition to using a luminescent layer ink that uses 1.6 mass% (Ir-ND1) instead of 0.8 mass% (Ir-D1) and 0.8 mass% (Ir-ND1), , an organic electroluminescent element was produced in the same manner as in Example 1.

[Comparative example 6] In addition to using a luminescent layer ink that uses 1.6 mass% (Ir-ND2) instead of 0.8 mass% (Ir-D1) and 0.8 mass% (Ir-ND2), , an organic electroluminescent element was produced in the same manner as in Example 3.

The relative values of the luminous efficiency [cd/A] of the devices obtained in Examples 1 to 4 and Comparative Examples 1 to 6 at 1000 cd/m ² (comparative example 6 is set to 1) are summarized in the table. 1 in.

[Table 1] Luminous material Relative value of luminous efficiency at 1000 cd/m ² [cd/A] Example 1 Ir-D1 Ir-ND1 1.022 Example 2 Ir-D2 Ir-ND1 1.022 Example 3 Ir-D1 Ir-ND2 1.020 Example 4 Ir-D2 Ir-ND2 1.037 Comparative example 1 Ir-D1 Ir-D2 0.907 Comparative example 2 Ir-ND1 Ir-ND2 0.986 Comparative example 3 Ir-D1 0.953 Comparative example 4 Ir-D2 0.894 Comparative example 5 Ir-ND1 1.018 Comparative example 6 Ir-ND2 1

From the results in Table 1, it can be seen that compared with the case of using the compound represented by the formula (1) or the formula (2) alone, and the case of using two compounds represented by the formula (1) or the formula (2), the When the compounds represented by formula (1) and formula (2) are used in combination one at a time, the luminous efficiency of the element is improved.

[Example 5] The ink for the light-emitting layer of the present invention was produced in the same manner as in Example 3 except that the compound (Ir-ND3) having the following structure was used instead of (Ir-ND2). Electromechanical luminescent components. In addition, the compound (Ir-ND3) was synthesized by referring to the method described in Japanese Patent Application Laid-Open No. 2014-074000.

[Chemistry 51]

[Comparative Example 7] Organic electroluminescence was produced in the same manner as in Example 3, except that an ink for a light-emitting layer using a compound (Ir-ND4) having the following structure was used as the ink for the light-emitting layer instead of (Ir-ND2). element.

[Chemistry 52]

The relative values of the luminous efficiency [cd/A] at 1000 cd/m ² of the devices obtained in Example 3, Example 5, and Comparative Example 7 (comparative Example 7 is set to 1) are summarized in Table 2.

[Table 2] Luminous material Relative value of luminous efficiency at 1000 cd/m ² [cd/A] Example 3 Ir-D1 Ir-ND2 2.322 Example 5 Ir-D1 Ir-ND3 1.728 Comparative example 7 Ir-D1 Ir-ND4 1

From the results in Table 2, it can be seen that compared with the ink for the light-emitting layer that combines the compound (Ir-D1) represented by the formula (2) and the compound (Ir-ND4), the use of the compound (Ir-D1) combined with the compound (Ir-ND4) represented by the formula The organic electroluminescent element produced by the ink for the light-emitting layer of the present invention of the compound represented by (1) (Ir-ND2) or (Ir-ND3) shows higher luminous efficiency.

[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 the compound (Ir-D3) having the following structure was used instead of (Ir-D1), it was produced in the same manner as in Example 3. Electromechanical luminescent components. In addition, the compound (Ir-D3) was synthesized with reference to the methods described in Japanese Patent Laid-Open No. 2014-074000 and Japanese Patent Laid-Open No. 2012-036388.

[Chemistry 53]

[Example 7] An organic electroluminescent element 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] Organic electroluminescence was produced in the same manner as in Example 6, except that an ink for a light-emitting layer using a compound (Ir-ND5) having the following structure was used as the ink for the light-emitting layer instead of (Ir-ND2). element. In addition, the compound (Ir-ND5) was synthesized by referring to the method described in Japanese Patent Application Laid-Open No. 2014-074000.

[Chemistry 54]

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

The relative values of the 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 to 1) are summarized in Table 3.

[Table 3] Table 3 Luminous material Relative value of luminous efficiency at 1000 cd/m ² [cd/A] Example 6 Ir-D3 Ir-ND2 3.782 Example 7 Ir-D3 Ir-ND3 2.422 Example 8 Ir-D3 Ir-ND5 2.069 Comparative example 8 Ir-D3 Ir-ND4 1

According to the results in Table 3, it can be seen that compared with the ink for the light-emitting layer that combines the compound (Ir-D3) represented by the formula (2) and the compound (Ir-ND4), the use of the compound (Ir-D3) combined with the compound (Ir-ND4) represented by the formula (1) The organic electroluminescent element produced by the ink for the light-emitting layer of the present invention showing the compound represented by the compound (Ir-ND2), the compound (Ir-ND3) or the compound (Ir-ND5) shows higher luminous efficiency. .

[Comparative Example 9] 31.5 mg of [Ir(ppy) ₃ ] was placed in a glass vial, and cyclohexylbenzene was added so that the total content became 3935 mg (0.8% by mass). It was not completely dissolved even after shaking for 5 minutes at room temperature (22°C), so it was heated at 100°C for 30 minutes, but it was still not completely dissolved. Furthermore, 8.00 g of cyclohexylbenzene was added and heated at 100° C. for 30 minutes again, but it was not completely dissolved. It is found that the solvent solubility of [Ir(ppy) ₃ ] is greatly insufficient compared with the iridium complex compound used in the present invention.

Various embodiments have been described above with reference to the drawings, but the present invention is of course not limited to the examples. It is obvious to those skilled in the art that various modifications or corrections can be conceivable within the scope described in the patent application, and it should be understood that these also belong to the technical scope of the present invention. In addition, the constituent elements in the above-described embodiments may be combined arbitrarily within the scope that does not deviate from the gist of the invention.

In addition, this application is based on a Japanese patent application filed on March 25, 2022 (Japanese Patent Application No. 2022-050596), and the content is incorporated into this application by reference. [Industrial availability]

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

1:Substrate 2:Anode 3: Hole injection layer 4: Hole transport layer 5: Luminous layer 6: Hole blocking layer 7:Electron transport layer 8:Electron injection layer 9:Cathode 10: Organic electroluminescent components

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

1:Substrate

2:Anode

3: Hole injection layer

4: Hole transport layer

5: Luminous layer

6: Hole blocking layer

7:Electron transport layer

8:Electron injection layer

9:Cathode

10: Organic electroluminescent components

Claims (9)

A composition for a light-emitting layer, including a compound represented by formula (1) and a compound represented by formula (2), Among them, n represents an integer from 0 to 10; R represents a substituent, and a represents 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', linear alkyl group, branched alkyl group or cyclic alkyl group with 1 to 5 carbon atoms, carbon A linear alkoxy group, a branched alkoxy group having a carbon number of 1 or more and 4 or less, a linear alkylthio group, a branched alkylthio group or a cyclic alkylthio group having a carbon number of 1 or more and 4 or less, a carbon number of 2 or more and 4 or less. Linear alkenyl group, branched alkenyl group or cyclic alkenyl group, straight chain alkynyl group, branched alkynyl group or cyclic alkynyl group having 2 to 4 carbon atoms, diarylamine group having 10 to 40 carbon atoms , an arylheteroarylamine group with a carbon number of 10 or more and 40 or less or a diheteroarylamino group with a carbon number of 10 or more and 40 or less, the alkyl group, the alkoxy group, the alkylthio group, the The alkenyl group, the alkynyl group, the diarylamine group, the arylheteroarylamine group and the diarylamine group may be substituted by R' other than one or more hydrogen atoms; R' Each independently is D, F, -CN, a linear alkyl group, a branched alkyl group or a cyclic alkyl group having 1 to 5 carbon atoms, a linear or branched alkenyl group having 2 to 4 carbon atoms, A linear or branched alkynyl group with a carbon number of 2 or more and 4 or less, Among them, m represents an integer from 0 to 10; Q represents a substituent, b represents 0 to the maximum integer that can be substituted by one ligand; X represents formula (3) or formula (4); Among them, the dotted line represents the bond with the benzene ring, Ar ¹ each independently represents a trivalent aromatic hydrocarbon group with 6 to 30 carbon atoms or a trivalent heteroaromatic group with 2 to 30 carbon atoms, and Ar ² each independently represents a carbon number of 6 A monovalent aromatic hydrocarbon group with ∼30 carbon atoms or a monovalent heteroaromatic group with 2 to 30 carbon atoms; Ar ¹ and Ar ² in formula (3) and formula (4) may be substituted by 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. The composition for a light-emitting layer according to claim 1 or 2, wherein in formula (3) or formula (4), Ar ¹ each independently represents a trivalent aromatic hydrocarbon group having 6 to 30 carbon atoms, and Ar ² respectively represents Independently represents a monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms. 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). The composition for a light-emitting layer according to any one of claims 1 to 4, wherein the compound represented by formula (1) measured by the following measurement method and the compound represented by formula (2) are represented by: The absolute value of the difference between the maximum emission wavelengths is 0 nm or more and 20 nm or less. Measurement method: The compound represented by formula (1) or the compound represented by formula (2) is added to a concentration of 1×10 ^-5 at room temperature. mol/L was dissolved in toluene, and nitrogen was bubbled for 20 minutes or more to obtain a sample in which oxygen, which causes extinction, was removed. The wavelength showing the maximum value of the phosphorescence spectrum intensity obtained from the sample was defined as the maximum luminescence. wavelength. The composition for a light-emitting layer according to any one of claims 1 to 5, wherein, with respect to the total mass of the compound represented by formula (1) and the compound represented by formula (2), The mass ratio of the compound is 10% or more and 80% or less. The composition for a light-emitting layer according to any one of claims 1 to 6, further comprising an organic solvent. A method of manufacturing an organic electroluminescent element. The organic electroluminescent element has an anode, a luminescent layer and a cathode in sequence on a substrate. The method of manufacturing an organic electroluminescent element includes: The step of forming the light-emitting layer by a wet film-forming method using the composition for the light-emitting layer according to claim 7. An organic electroluminescent element having an anode, a luminescent layer and a cathode in sequence on a substrate. In the organic electroluminescent element, the luminescent layer contains a compound represented by formula (1) and a compound represented by formula (2). compound, Among them, n represents an integer from 0 to 10; R represents a substituent, and a represents 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', linear alkyl group, branched alkyl group or cyclic alkyl group with 1 to 5 carbon atoms, carbon A linear alkoxy group, a branched alkoxy group having a carbon number of 1 or more and 4 or less, a linear alkylthio group, a branched alkylthio group or a cyclic alkylthio group having a carbon number of 1 or more and 4 or less, a carbon number of 2 or more and 4 or less. Linear alkenyl group, branched alkenyl group or cyclic alkenyl group, straight chain alkynyl group, branched alkynyl group or cyclic alkynyl group having 2 to 4 carbon atoms, diarylamine group having 10 to 40 carbon atoms , an arylheteroarylamine group with a carbon number of 10 or more and 40 or less or a diheteroarylamino group with a carbon number of 10 or more and 40 or less, the alkyl group, the alkoxy group, the alkylthio group, the The alkenyl group, the alkynyl group, the diarylamine group, the arylheteroarylamine group and the diarylamine group may be substituted by R' other than one or more hydrogen atoms; R' Each independently is D, F, -CN, a linear alkyl group, a branched alkyl group or a cyclic alkyl group having 1 to 5 carbon atoms, a linear or branched alkenyl group having 2 to 4 carbon atoms, A linear or branched alkynyl group with a carbon number of 2 or more and 4 or less, Among them, m represents an integer from 0 to 10; Q represents a substituent, b represents 0 to the maximum integer that can be substituted by one ligand; X represents formula (3) or formula (4); Among them, the dotted line represents the bond with the benzene ring, Ar ¹ each independently represents a trivalent aromatic hydrocarbon group with 6 to 30 carbon atoms or a trivalent heteroaromatic group with 2 to 30 carbon atoms, and Ar ² each independently represents a carbon number of 6 A monovalent aromatic hydrocarbon group with ∼30 carbon atoms or a monovalent heteroaromatic group with 2 to 30 carbon atoms; Ar ¹ and Ar ² in formula (3) and formula (4) may be substituted by Q.