JP2024125195A - Iridium complex compound, composition for organic electroluminescence device, and method for producing organic electroluminescence device - Google Patents

Abstract

To provide an iridium complex compound that has high solvent solubility suitable for the wet deposition technique and enhances luminous efficiency of red organic EL devices when used as an assistance dopant in red luminous devices.SOLUTION: The present invention provides an iridium complex compound represented by a formula (1) (where each substituent is as defined in the specifications).SELECTED DRAWING: Figure 1

Description

The present invention relates to an iridium complex compound, and in particular to an iridium complex compound useful as a material for the light-emitting layer of an organic electroluminescent element (hereinafter sometimes referred to as an "organic EL element"), a composition for an organic electroluminescent element containing the compound, and a method for producing an organic electroluminescent element using the composition for an organic electroluminescent element.

Various electronic devices that use organic EL elements, such as organic EL lighting and organic EL displays, have been put to practical use. Organic EL elements consume little power due to the low applied voltage, and are capable of emitting the three primary colors, so they are beginning to be used not only in large display monitors, but also in small and medium-sized displays such as mobile phones and smartphones.
An organic EL element is manufactured by stacking a plurality of layers, such as a light-emitting layer, a charge injection layer, and a charge transport layer. Currently, most organic EL elements are manufactured by depositing organic materials under vacuum. However, the vacuum deposition method requires a complicated deposition process, resulting in poor productivity. Furthermore, organic EL elements manufactured by the vacuum deposition method have a problem in that it is extremely difficult to enlarge the panels of lighting and displays. For this reason, in recent years, wet film formation (coating) has been actively researched as a process for efficiently manufacturing organic EL elements that can be used for large displays and lighting. The wet film formation method has the advantage of being able to easily form a stable layer compared to the vacuum deposition method, and is therefore expected to be applied to mass production of displays and lighting devices and large devices.

On the other hand, the performance required for an organic EL element is improved luminous efficiency and a long operating life. If these requirements cannot be met simultaneously, it will be difficult to use the element as an organic EL display material.

In particular, for red organic EL elements, attention has been focused on how to improve the luminous efficiency, i.e., the luminous intensity (candela) per unit current. In order to widen the color gamut of the display and produce images with better color reproducibility, red elements must use red luminous materials that emit light at longer wavelengths. However, there are two essential problems in terms of luminous efficiency when it comes to increasing the wavelength in the red region.
The first problem is the visibility of the human eye (spectral luminous efficiency), in that the visibility of light with wavelengths over 600 nm drops sharply as the wavelength increases, resulting in a large reduction in the luminous efficiency.
The second problem is that there exists a law known as the energy gap law, which states that as the excitation energy decreases (emission of long wavelengths occurs), the interaction with the vibrational state of the emitting molecule increases, and the rate of non-radiative deactivation increases exponentially. As a result, the luminescence quantum yield decreases, i.e., the luminescence efficiency decreases.
Therefore, improving the luminous efficiency of the red elements is extremely important for improving the performance of organic EL displays.

One of the methods for improving the characteristics of red elements is to have an assist dopant coexist in the light-emitting layer. Usually, the light-emitting layer of an organic EL element contains a host molecule that transports charges and a dopant molecule that emits light by obtaining excitation energy generated by the recombination of holes and electrons. Recombination can occur on the host or the dopant, but it is often designed to cause recombination on the dopant, which is expected to improve the light-emitting efficiency. However, in red elements, red-emitting dopant molecules often have poor durability. As a result of such a design, the load is concentrated on the dopant molecule, resulting in a short operating life.
To improve this, there is a method in which a second dopant molecule having a wider energy gap than the dopant molecule (in other words, a shorter maximum emission wavelength when light is emitted) is made to coexist, and excitons are generated on the second dopant, and then energy is transferred to a red light-emitting dopant having a narrower energy gap to emit light. The life of the element can be extended by distributing the load using a highly durable second dopant, i.e., an assist dopant. In addition, since the red light-emitting dopant has a narrow HOMO-LUMO gap, there are cases in which a host material suitable for injecting holes or electrons cannot be prepared. However, if a material having a wide energy gap is used as an assist dopant and the element is designed to cause recombination on the assist dopant, the reactive current can be reduced and the luminous efficiency can be improved. A preferred assist dopant in such a red element is one that emits light in yellow-green to yellow or orange by itself.

The advantage of the wet film-forming method over the vacuum deposition method is that it allows many components to coexist in the light-emitting layer, improving performance. With the vacuum deposition method, it becomes difficult to control the deposition rate at a constant rate as the number of material types increases, whereas with the wet film-forming method, as long as each material dissolves in an organic solvent (hereinafter sometimes simply referred to as "solvent"), it is possible to create an ink with a constant component ratio, even if the number of material types increases.

In recent years, attempts have been made to improve the performance of organic EL elements by using two types of iridium complex compounds in inks as a light-emitting dopant and an assist dopant to increase the luminous efficiency of the organic EL element and reduce the driving voltage (for example, Patent Documents 1 and 2).
In addition, as examples of iridium complex compounds capable of emitting yellow-green to yellow light, structures having a fluorenylpyridine ligand or a thieno[3,2-c]pyridine ligand have been disclosed (Patent Documents 3 to 6 and Non-Patent Document 1). There has also been a report of an example of a device in which this compound is used as an assist dopant to make a red light-emitting material emit light (Non-Patent Document 2).

International Publication No. 2015/192939 International Publication No. 2016/015815 JP 2002-332291 A International Publication No. 2015/105014 US Patent Application Publication No. 2016/0164007 US Patent Application Publication No. 2018/0175309

C. Fang, J. Miao, B. Jiang, C. Yang, H. Wu, J. Qin, Y. Cao, Organic Electronics 14 (2013) 3392-3398. Y. Zou, J. Hu, M. Yu, J. Miao, Z. Xie, Y. Qiu, X. Cao, C. Yang, Adv. Mater. 2022, 34, 2201442.

However, in the assist dopant structures disclosed in Patent Documents 1 and 2, the emitted light is green and has a large energy difference with the red dopant, so that the energy transfer is slow and, as a result, the luminescence of the assist dopant itself is observed. This adversely affects the element characteristics such as color purity as a red element.
In addition, the compounds specifically disclosed in Patent Documents 3 to 6 and Non-Patent Documents 1 and 2 are difficult to use as materials for a wet film formation method due to insufficient solubility in solvents, and even when a coating-type organic EL element is produced by improving the solvent, coating conditions, etc., the element has a short life and is not sufficient in terms of properties as an assist dopant, such as low efficiency of energy transfer to a red dopant.

The present invention aims to provide an iridium complex compound that has high solvent solubility that can be used in wet film formation methods and that improves the luminous efficiency of red organic EL elements when used as an assist dopant in red light-emitting elements.

As a result of intensive research conducted by the inventors to solve the above problems, they discovered that an iridium complex compound having a specific chemical structure has high solubility in solvents and at the same time contributes to improving the luminous efficiency and operating life of red-emitting organic EL elements, and thus completed the present invention.

In other words, the gist of the present invention is as follows:

Aspect 1 of the present invention is
The iridium complex compound is represented by the following formula (1).

In the above formula (1), Ir represents an iridium atom.
R ¹ to R ¹⁰ each independently represent a hydrogen atom, a fluorine atom, a cyano group, a linear, branched or cyclic alkyl group having from 1 to 30 carbon atoms, an aromatic hydrocarbon group having from 5 to 60 carbon atoms, an aromatic heterocyclic group having from 5 to 60 carbon atoms, an aralkyl group having from 5 to 60 carbon atoms, or a heteroaralkyl group having from 5 to 60 carbon atoms. These substituents may further have a substituent.
^R11 and ^R12 each independently represent a linear, branched or cyclic alkyl group having from 1 to 30 carbon atoms, an aromatic hydrocarbon group having from 5 to 60 carbon atoms, an aromatic heterocyclic group having from 5 to 60 carbon atoms, an aralkyl group having from 5 to 60 carbon atoms, or a heteroaralkyl group having from 5 to 60 carbon atoms. These substituents may further have a substituent.
Any two adjacent R ² to R ⁵ and any two adjacent R ¹¹ and R ¹² may be bonded to each other while losing a hydrogen atom to form a ring.

Aspect 2 of the present invention relates to an iridium complex compound according to aspect 1,
The iridium complex compound is one in which the substituents R ¹ , R ² , R ⁶ , R ⁷ and R ¹⁰ are hydrogen atoms.

A third aspect of the present invention relates to an iridium complex compound according to the first or second aspect,
In the iridium complex compound, the substituent R ¹¹ is a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms.

A fourth aspect of the present invention relates to an iridium complex compound according to any one of the first to third aspects,
In the iridium complex compound, any one of the substituents ^R3 and ^R4 is a hydrogen atom.

A fifth aspect of the present invention relates to an iridium complex compound according to any one of the first to fourth aspects,
The iridium complex compound is one in which the substituent R ⁸ is a hydrogen atom, a linear or branched alkyl group having from 1 to 30 carbon atoms, or an aromatic hydrocarbon group having from 5 to 60 carbon atoms.

Aspect 6 of the present invention is
The organic electroluminescent device includes an emitting layer containing the iridium complex compound according to any one of Embodiments 1 to 5 and a red emitting material having a maximum emission wavelength of 600 nm or longer.

A seventh aspect of the present invention is the organic electroluminescent device of the sixth aspect,
The organic electroluminescent device is characterized in that the red light emitting material is an iridium complex compound represented by formula (201).

[In the above formula (201), M represents a metal selected from Groups 7 to 11 of the periodic table.
Ring A1 represents an aromatic hydrocarbon ring structure which may have a substituent or an aromatic heterocyclic structure which may have a substituent.
Ring A2 represents an aromatic heterocyclic structure which may have a substituent.
R ²⁰¹ and R ²⁰² are each independently a structure represented by the above formula (202), and "*" represents bonding to ring A1 or ring A2. R ²⁰¹ and R ²⁰² may be the same or different, and when a plurality of R ²⁰¹ and R ²⁰² are present, they may be the same or different.
Ar ²⁰¹ represents a divalent aromatic hydrocarbon ring structure which may have a substituent, or a divalent aromatic heterocyclic structure which may have a substituent. When a plurality of Ar ²⁰¹ are present, they may be the same or different.
Ar ²⁰² represents a divalent aromatic hydrocarbon ring structure which may have a substituent, a divalent aromatic heterocyclic structure which may have a substituent, or a divalent aliphatic hydrocarbon structure which may have a substituent. When a plurality of Ar ²⁰² are present, they may be the same or different.
Ar ²⁰³ represents a monovalent aromatic hydrocarbon ring structure which may have a substituent, or a monovalent aromatic heterocyclic ring structure which may have a substituent. When there are a plurality of Ar ²⁰³ , they may be the same or different.
The substituents bonded to ring A1, the substituents bonded to ring A2, or the substituents bonded to ring A1 and the substituents bonded to ring A2 may be bonded to each other to form a ring.
B ²⁰¹ -L ²⁰⁰ -B ²⁰² represents an anionic bidentate ligand. B ²⁰¹ and B ²⁰² each independently represent a carbon atom, an oxygen atom, or a nitrogen atom, and these atoms may be atoms constituting a ring. L ²⁰⁰ represents a single bond, or an atomic group constituting a bidentate ligand together with B ²⁰¹ and B ^202. When a plurality of B ²⁰¹ -L ²⁰⁰ -B ²⁰² are present, they may be the same or different.
i1 and i2 each independently represent an integer of 0 to 12.
i3 is an integer of 0 or more, the upper limit of which is the number that can be substituted for Ar ²⁰² .
j is an integer of 0 or more, the upper limit of which is the number that can be substituted on Ar ²⁰¹ .
k1 and k2 each independently represent an integer of 0 or more, which is the upper limit of the number that can be substituted on ring A1 and ring A2.
m is an integer from 1 to 3.

Aspect 8 of the present invention is
An ink for forming a light-emitting layer of a coating-type organic electroluminescent device, comprising the iridium complex compound according to any one of Aspects 1 to 5, a red light-emitting material having a maximum emission wavelength of 600 nm or more, and an organic solvent.

The iridium complex compound of the present invention has high solvent solubility that allows it to be used in wet film formation methods, and when used as an assist dopant in a red light-emitting element, it can improve the luminous efficiency of the red organic EL element.

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

The following describes in detail the embodiments of the present invention, but the present invention is not limited to the following embodiments and can be modified in various ways within the scope of the invention.
In this specification, a hydrogen atom (H) includes its isotope, a deuterium atom (D).

[Iridium Complex Compounds]
The iridium complex compound of the present invention is a compound represented by the following formula (1).

In the above formula (1), Ir represents an iridium atom.
R ¹ to R ¹⁰ each independently represent a hydrogen atom, a fluorine atom, a cyano group, a linear, branched or cyclic alkyl group having from 1 to 30 carbon atoms, an aromatic hydrocarbon group having from 5 to 60 carbon atoms, an aromatic heterocyclic group having from 5 to 60 carbon atoms, an aralkyl group having from 5 to 60 carbon atoms, or a heteroaralkyl group having from 5 to 60 carbon atoms. These substituents may further have a substituent.
^R11 and ^R12 each independently represent a linear, branched or cyclic alkyl group having from 1 to 30 carbon atoms, an aromatic hydrocarbon group having from 5 to 60 carbon atoms, an aromatic heterocyclic group having from 5 to 60 carbon atoms, an aralkyl group having from 5 to 60 carbon atoms, or a heteroaralkyl group having from 5 to 60 carbon atoms. These substituents may further have a substituent.
Any two adjacent R ² to R ⁵ and any two adjacent R ¹¹ and R ¹² may be bonded to each other while losing a hydrogen atom to form a ring.

<Mechanism>
The iridium complex compound of the present invention has higher solubility in solvents than conventional materials, and at the same time, it can improve the luminous efficiency and driving life of a red organic EL device using this iridium complex compound. The reason for this is presumed to be as follows.
The 2-fluorenyl-5-phenylpyridine skeleton, which is the main structure of the ligand of the iridium complex compound of the present invention, is highly linear, and it is considered that the overlap between the HOMO and LUMO is very large. It is expected that the rate of relaxation from the excited state of this iridium complex compound is fast, and in fact, the PL quantum yield of the solution shows a value equivalent to that of other similar structures. In addition, the half-width of the emission spectrum of this iridium complex compound is considerably narrower than that of other similar structures. This suggests that the transition from the excited state to the lowest ground state, which is the basis of the main peak, occurs more frequently, and it is considered that the energy transfer to the red dopant occurs quickly and more effectively. If the energy transfer is slow, when the organic EL element is driven, the excited state is converted to heat due to a quenching process separate from light emission, such as collisions between excited triplets on the assist dopant (triplet-triplet annihilation) or collisions between excited triplets and holes (triplet-polaron quenching), resulting in a decrease in efficiency. In addition, a decomposition reaction accompanied by dissociation of chemical bonds from the higher energy state generated at the same time occurs, resulting in a decrease in driving life; however, the iridium complex compound of the present invention solves these problems.

Furthermore, it is preferable that the pyridine moiety is [3,2-c]thienopyridine. It is believed that the electron-accepting property is improved by adjusting the excited triplet energy to an appropriate level as an assist dopant for red light-emitting materials and by extending the LUMO, which is mainly distributed on the pyridine ring, to the thiophene ring, which results in easier recombination of holes and electrons on the assist dopant and improved efficiency.

In order to achieve such an effect, it is essential that the complex is a homoleptic complex, that is, a complex having three bidentate ligands of the same structure (L ₃ Ir complex: L represents a bidentate ligand). When the three ligands of iridium are different (for example, L ₂ IrX complex: X represents an auxiliary ligand), the proportion of HOMO or LUMO localized on L or X increases, resulting in a decrease in excited triplet energy, a decrease in quantum yield, and the slowing of energy transfer to the red light-emitting material due to the appearance of various vibration modes. As a result, the efficiency as a red light-emitting element decreases, and the binding force between the iridium atom and each ligand becomes biased, which reduces the durability of the element.

<Substituents R ¹ to R ¹² >
The substituents R ¹ to R ¹² in formula (1) may be the same or different within the range of types described below, and may be selected in accordance with the requirements for precise control of the desired emission wavelength and compatibility with the solvent used. An optimal type can be selected taking into consideration compatibility with a host compound and a red light emitting compound when used in an organic EL device.
In addition, two adjacent R ² to R ⁵ and R ¹¹ and R ¹² can be bonded to each other while losing one hydrogen atom, as exemplified in the following formula, to form a ring. However, if the number of condensed ring structures of the ligands near the iridium atom increases, the solvent solubility of the iridium complex compound is significantly impaired, or the excited triplet energy is large due to the expansion of the π-electron conjugated system. It is preferred that two adjacent R ² to R ⁵ and R ¹¹ and R ¹² do not form such a ring, since this may cause degradation.

<Substituents R ¹ to R ¹⁰ >
R ¹ to R ¹⁰ in formula (1) each independently represent a hydrogen atom, a fluorine atom, a cyano group, a linear, branched or cyclic alkyl group having from 1 to 30 carbon atoms, a cyclic group having from 5 to 60 carbon atoms, The substituents are aromatic hydrocarbon groups, aromatic heterocyclic groups having 5 to 60 carbon atoms, aralkyl groups having 5 to 60 carbon atoms, and heteroaralkyl groups having 5 to 60 carbon atoms. It may have the following structure.

<Substituents R ¹¹ and R ¹² >
The substituents ^R11 and ^R12 are each independently a linear, branched or cyclic alkyl group having from 1 to 30 carbon atoms, an aromatic hydrocarbon group having from 5 to 60 carbon atoms, an aromatic heterocyclic group having from 5 to 60 carbon atoms, an aralkyl group having from 5 to 60 carbon atoms, or a heteroaralkyl group having from 5 to 60 carbon atoms. These substituents may further have a substituent.

Examples of linear, branched 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 and adamantyl groups. In the case of alkyl groups, if the number of carbon atoms is too large, the complex is highly shielded and durability is impaired, so the preferred number of carbon atoms is 20 or less, more preferably 12 or less, and most preferably 8 or less. However, in the case of branched alkyl groups, the shielding effect is greater than that of linear alkyl groups and cyclic alkyl groups, so the most preferred number of carbon atoms is 8 or less.

The aromatic hydrocarbon group having from 5 to 60 carbon atoms and the aromatic heterocyclic group having from 5 to 60 carbon atoms may exist as a single ring or a condensed ring, or may be a group formed by further bonding or condensing another type of aromatic hydrocarbon group or aromatic heterocyclic group to one ring.
Examples of these include a phenyl group, a naphthyl group, anthracenyl group, a benzoanthracenyl group, a phenanthrenyl group, a benzophenanthrenyl group, a pyrenyl group, a chrysenyl group, a fluoranthenyl group, a perylenyl group, a benzopyrenyl group, a benzofluoranthenyl group, a naphthacenyl group, a pentacenyl group, a biphenyl group, a terphenyl group, a fluorenyl group, a spirobifluorenyl group, a dihydrophenanthrenyl group, a dihydropyrenyl group, a tetrahydropyrenyl group, an indenofluorenyl group, a furyl group, a benzofuryl group, an isobenzofuryl group, a dibenzofuranyl group, a thiophene group, a benzothiophenyl group, a dibenzothiophenyl group, a pyrrolyl group, an indolyl group, an isoindolyl group, a carbazolyl group, a benzocarbazolyl group, an indolocarbazolyl group, an indenocarbazolyl group, a pyridyl group, a cinnolyl group, an isocinnolyl group, an acridyl group, a phenoxy group, a phenyl ... anthracenyl group, phenothiazinyl group, phenoxazyl group, pyrazolyl group, indazolyl group, imidazolyl group, benzimidazolyl group, naphthimidazolyl group, phenanthroimidazolyl group, pyridineimidazolyl group, oxazolyl group, benzoxazolyl group, naphthoxazolyl group, thiazolyl group, benzothiazolyl group, pyrimidyl group, benzopyrimidyl group, pyridazinyl group, quinoxalinyl group, diazaanthracenyl group, Examples of such groups include an isyl group, a diazapyrenyl group, a pyrazinyl group, a phenoxazinyl group, a phenothiazinyl group, a naphthyridinyl group, an azacarbazolyl group, a benzocarbolinyl group, a phenanthrolinyl group, a triazolyl group, a benzotriazolyl group, an oxadiazolyl group, a thiadiazolyl group, a triazinyl group, a 2,6-diphenyl-1,3,5-triazin-4-yl group, a tetrazolyl group, a purinyl group, and a benzothiadiazolyl group.
From the viewpoint of the balance between solvent solubility and durability, these groups preferably have 50 or less carbon atoms, more preferably 40 or less, and most preferably 30 or less.

Examples of aralkyl groups having 5 to 60 carbon atoms include 1,1-dimethyl-1-phenylmethyl, 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, and 4-phenylcyclohexyl. From the viewpoint of the balance between solubility and durability, it is more preferable that the number of carbon atoms in these aralkyl groups is 40 or less.

Examples of heteroaralkyl groups having 5 to 60 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 group, 6-(2-pyridyl)-1-n-hexyl group, 6-(2-pyrimidyl)-1-n-hexyl group, 6-(2,6-diphenyl-1,3,5-triazin-4-yl)-1-n-hexyl group, 7-(2-pyridyl)-1-n-heptyl group, 8-(2-pyridyl)-1-n-octyl group, 4-(2-pyridyl)cyclohexyl group, etc. From the viewpoint of the balance between solubility and durability, these heteroaralkyl groups are preferably 50 or less, more preferably 40 or less, and most preferably 30 or less.

There is no limitation on the type of substituent that the substituents R ¹ to R ¹² may further have, but is preferably a fluorine atom, a cyano group, a linear, branched or cyclic alkyl group having from 1 to 30 carbon atoms, an aromatic hydrocarbon group having from 5 to 60 carbon atoms, an aromatic heterocyclic group having from 5 to 60 carbon atoms, an aralkyl group having from 5 to 60 carbon atoms, or a heteroaralkyl group having from 5 to 60 carbon atoms.
The substituents R ¹ , R ² , R ⁶ , R ⁷ and R ¹⁰ are preferably hydrogen atoms from the viewpoints of maintaining the planar structure of the ligand and maintaining durability without sterically interfering with the bond between the ligand and the iridium atom.

Substituent ^R3 or ^R4 is important for controlling the hole transport property of the iridium complex compound of the present invention when it exists in the light-emitting layer as an assist dopant.From this viewpoint, the types of particularly preferred substituents are hydrogen atom, linear or branched alkyl group having 1 to 30 carbon atoms, aromatic hydrocarbon group having 5 to 60 carbon atoms and aromatic heterocyclic group having 5 to 60 carbon atoms, aralkyl group having 5 to 60 carbon atoms or heteroaralkyl group having 5 to 60 carbon atoms.In order not to significantly impair hole transport property, it is preferable that the fluorene part is not sterically shielded, so it is more preferable that at least one of the substituents ^R3 or ^R4 is a hydrogen atom, and it is particularly preferable that one of the substituents ^R3 and ^R4 is a hydrogen atom.

The substituent R ⁸ is a substituent at a position with high substitution activity in the thiophene ring, and the introduction of a strong substituent increases durability, whereas the introduction of a bulky substituent may affect efficiency since the [3,2-c]thienopyridine ring is the site for electron injection. Therefore, from the viewpoint of extending the driving life, it is particularly preferred that the substituent is a hydrogen atom, a linear or branched alkyl group having 1 to 30 carbon atoms, or an aromatic hydrocarbon group having 5 to 60 carbon atoms, whereas from the viewpoint of increasing efficiency, it is particularly preferred that the substituent is a hydrogen atom, a linear or branched alkyl group having 1 to 10 carbon atoms, or an aromatic hydrocarbon group having 5 to 20 carbon atoms.
Similarly, from the viewpoint of improving efficiency, R ⁹ which is a substituent on the [3,2-c]thienopyridine ring is preferably a hydrogen atom, a linear or branched alkyl group having from 1 to 10 carbon atoms, or an aromatic hydrocarbon group having from 5 to 20 carbon atoms.

From the viewpoint of maintaining high solubility of the iridium complex compound, it is preferable that either one of the substituents R ¹¹ and R ¹² , and more preferably both of them, is a linear, branched or cyclic alkyl group having a carbon number of 1 to 30. For example, it is preferable that the substituent R ¹¹ is a linear, branched or cyclic alkyl group having a carbon number of 1 to 30. The substituents R ¹¹ and R ¹² may be different from each other, but it is preferable that they are the same type of substituent for ease of production.

<Specific examples>
Specific examples of the iridium complex compound of the present invention other than those shown in the examples given later will be shown below, but the present invention is not limited to these.

<Method for measuring maximum emission wavelength in solution>
The method for measuring the maximum emission wavelength in a solution of the iridium complex compound of the present invention is as follows.
A solution of an iridium complex compound dissolved in toluene at a concentration of 1×10 ⁻⁴ mol/L or less at room temperature is subjected to phosphorescence spectrum measurement using a spectrophotometer (Organic EL Quantum Yield Measurement System C9920-02, manufactured by Hamamatsu Photonics K.K.). The wavelength showing the maximum intensity of the obtained phosphorescence spectrum is regarded as the maximum emission wavelength in the present invention.
The iridium complex compound of the present invention has a maximum emission wavelength of usually 530 nm or more, preferably 550 nm or more, more preferably 570 nm or more, and preferably has an upper limit equal to or lower than the maximum emission wavelength of the red light-emitting dopant used together.

<Method for synthesizing iridium complex compound>
The ligands of the iridium complex compounds of the present invention can be constructed by converting building blocks such as halogenated fluorenes and 2-bromo-5-iodopyridines to borate esters by the Miyaura-Ishiyama boration reaction or the Hartwig-Miyaura C-H boration reaction, and then subjecting these intermediates to the Suzuki-Miyaura coupling reaction with aryl halides. By combining this with other known methods, ligands with various substituents can be synthesized.

Regarding the synthesis method of iridium complex compounds, there are a method via a chlorine-bridged iridium dinuclear complex as shown in the following formula [A] (using a phenylpyridine ligand as an example for ease of understanding) (M. G. Colombo, T. C. Brunold, T. Riedener, H. U. Gudel, Inorg. Chem., 1994, 33, 545-550), and a method via a dinuclear complex as shown in the following formula [B]. and a method of converting the chlorine bridge of the acetylacetonate to a mononuclear complex and then obtaining the target compound (S. Lamansky, P. Djurovich, D. Murphy, F. Abdel-Razzaq, R. Kwong, I. Tsyba, M. Borz, B. Mui, R. Bau, M. Thompson, Inorg. Chem., 2001, 40, 1704-1711). Further, a method of reacting a ligand with a tris(acetylacetonatoiridium(III)) complex at high temperature in glycerin to directly obtain a homo-triscyclometalated iridium complex (K. Dedean, P.I. Djurovich, F.O. Garces, G. Carlson, R.J. Watts, Inorg. Chem., 1991, 30, 1685-1687) is also available, but is not limited to these.

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

There are no particular limitations on the reaction temperature, but it is usually preferred to set the temperature at 0°C or higher, and more preferably at 50°C or higher. It is also preferred to set the temperature at 250°C or lower, and more preferably at 150°C or lower. Within these ranges, the desired reaction proceeds without the generation of by-products or decomposition reactions, and high selectivity tends to be obtained.

In the second step, a halide ion trapping agent such as silver trifluoromethanesulfonate is added and brought into contact with the newly added ligand to obtain the desired complex. The solvent is usually ethoxyethanol or diglyme, but depending on the type of ligand, no solvent or other solvents can be used, or multiple solvents can be mixed. The reaction may proceed without adding a halide ion trapping agent, so it is not necessarily required, but adding the trapping agent is advantageous for increasing the reaction yield and selectively synthesizing facial isomers with higher quantum yields. There are no particular restrictions on the reaction temperature, but it is usually carried out in the range of 0°C to 250°C.

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

In the third step, one or more equivalents of the ligand are reacted. There is no particular restriction on the type and amount of the solvent, and if the ligand is liquid at the reaction temperature, no solvent is necessary. There is no particular restriction on the reaction temperature, but since the reactivity is somewhat poor, the reaction is often carried out at a relatively high temperature of 100°C to 300°C. Therefore, a solvent with a high boiling point such as glycerin is preferably used.
After the final reaction, purification is performed to remove unreacted raw materials, reaction by-products, and solvents. Although purification procedures in ordinary organic synthesis chemistry can be applied, purification is mainly performed by normal phase silica gel column chromatography as described in the above non-patent literature. As the developing solution, a single or mixed solution of hexane, heptane, dichloromethane, chloroform, ethyl acetate, toluene, methyl ethyl ketone, and methanol can be used. Purification may be performed multiple times under different conditions. Other chromatography techniques (reverse phase silica gel chromatography, size exclusion chromatography, paper chromatography), separation washing, reprecipitation, recrystallization, suspension washing of powder, drying under reduced pressure, and other purification procedures can be performed as necessary.

<Uses of iridium complex compounds>
The iridium complex compound of the present invention can be suitably used as a material for an organic EL device, particularly as an assist dopant in a red organic EL device, and can also be suitably used as a light-emitting material for a yellow-green to orange light-emitting organic EL device.

[Red light-emitting material]
The iridium complex compound of the present invention is preferably used together with a red light emitting material as a composition for forming a light emitting layer. The light emitting material refers to the component that mainly emits light in the composition of the present invention.
The maximum emission wavelength of the red light-emitting material depends on the shape of its spectrum, but is usually 580 nm or more, preferably 600 nm or more, more preferably 620 nm or more, and usually 700 nm or less, preferably 650 nm or less, more preferably 640 nm or less. There is no particular limitation on the method for measuring the maximum emission wavelength, but since it differs depending on the state of the measurement sample such as a solution or solid film and the concentration thereof, it can be determined with good reproducibility by using the measurement method of the maximum emission wavelength of a solution described later.
As the red light emitting material, known materials can be used, and fluorescent materials or phosphorescent materials can be used alone or in combination. From the viewpoint of internal quantum efficiency, phosphorescent materials are preferred.

[Phosphorescent material]
The chemical structures of phosphorescent materials that emit red light are diverse, and it is difficult to specify the structure. The type of ligand directly bonded to the central metal has a large effect on the emission wavelength, but the emission wavelength can also be changed significantly depending on the substituents introduced into the ligand. Therefore, after explaining the general structure of phosphorescent materials, we will first explain the types of structures that are more suitable for red light-emitting materials.

The phosphorescent material is a material that emits light from an excited triplet state. Representative examples of the phosphorescent material include metal complex compounds having Ir, Pt, Eu, etc., and the material preferably has a structure including a metal complex.
Among metal complexes, examples of phosphorescent organometallic complexes that emit light via a triplet state include Werner-type complexes or organometallic complex compounds containing, as a central metal, a metal selected from Groups 7 to 11 of the long-form periodic table (hereinafter, unless otherwise specified, the term "periodic table" refers to the long-form periodic table). As such phosphorescent materials, a compound represented by the following formula (201) or a compound represented by the below-described formula (205) is preferred, and a compound represented by the following formula (201) is more preferred.

[In the above formula (201), M represents a metal selected from Groups 7 to 11 of the periodic table.
Ring A1 represents an aromatic hydrocarbon ring structure which may have a substituent or an aromatic heterocyclic structure which may have a substituent.
Ring A2 represents an aromatic heterocyclic structure which may have a substituent.
R ²⁰¹ and R ²⁰² are each independently a structure represented by the above formula (202), and "*" represents bonding to ring A1 or ring A2. R ²⁰¹ and R ²⁰² may be the same or different, and when a plurality of R ²⁰¹ and R ²⁰² are present, they may be the same or different.
Ar ²⁰¹ represents a divalent aromatic hydrocarbon ring structure which may have a substituent, or a divalent aromatic heterocyclic structure which may have a substituent. When a plurality of Ar ²⁰¹ are present, they may be the same or different.
Ar ²⁰² represents a divalent aromatic hydrocarbon ring structure which may have a substituent, a divalent aromatic heterocyclic structure which may have a substituent, or a divalent aliphatic hydrocarbon structure which may have a substituent. When a plurality of Ar ²⁰² are present, they may be the same or different.
Ar ²⁰³ represents a monovalent aromatic hydrocarbon ring structure which may have a substituent, or a monovalent aromatic heterocyclic ring structure which may have a substituent. When there are a plurality of Ar ²⁰³ , they may be the same or different.
The substituents bonded to ring A1 may be bonded to each other, the substituents bonded to ring A2 may be bonded to each other, or the substituents bonded to ring A1 and the substituents bonded to ring A2 may be bonded to each other to form a ring.
B ²⁰¹ -L ²⁰⁰ -B ²⁰² represents an anionic bidentate ligand. B ²⁰¹ and B ²⁰² each independently represent a carbon atom, an oxygen atom, or a nitrogen atom, and these atoms may be atoms constituting a ring. L ²⁰⁰ represents a single bond, or an atomic group constituting a bidentate ligand together with B ²⁰¹ and B ^202. When a plurality of B ²⁰¹ -L ²⁰⁰ -B ²⁰² are present, they may be the same or different.
i1 and i2 each independently represent an integer of 0 to 12.
i3 is an integer of 0 or more, the upper limit of which is the number that can be substituted for Ar ²⁰² .
j is an integer of 0 or more, the upper limit of which is the number that can be substituted on Ar ²⁰¹ .
k1 and k2 each independently represent an integer of 0 or more, which is the upper limit of the number that can be substituted on ring A1 and ring A2.
m is an integer from 1 to 3.

(M)
In the above formula (201), M is a metal selected from Groups 7 to 11 of the periodic table, and examples thereof include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, gold, and europium.

(Ring A1)
In the above formula (201), ring A1 represents an aromatic hydrocarbon ring structure which may have a substituent or an aromatic heterocyclic structure which may have a substituent.
The aromatic hydrocarbon ring in ring A1 is preferably an aromatic hydrocarbon ring having 6 to 30 carbon atoms, and specifically, a benzene ring, a naphthalene ring, an anthracene ring, a triphenylyl ring, an acenaphthene ring, a fluoranthene ring, or a fluorene ring is preferred.

The aromatic heterocycle in ring A1 is preferably an aromatic heterocycle having 3 to 30 carbon atoms and containing a nitrogen atom, oxygen atom, or sulfur atom as a heteroatom, and more preferably a furan ring, a benzofuran ring, a thiophene ring, or a benzothiophene ring.

Ring A1 is more preferably a benzene ring, a naphthalene ring, or a fluorene ring, particularly preferably a benzene ring or a fluorene ring, and most preferably a benzene ring.

(Ring A2)
In the above formula (201), ring A2 represents an aromatic heterocyclic structure which may have a substituent.
The aromatic heterocycle in ring A2 is preferably a monocyclic ring, a condensed ring, or a structure in which monocyclic rings are linked, of an aromatic heterocycle having 3 to 30 carbon atoms and containing a nitrogen atom, an oxygen atom, or a sulfur atom as a heteroatom.
Specific examples of the monocyclic or condensed ring include a pyridine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, an imidazole ring, an oxazole ring, a thiazole ring, a benzothiazole ring, a benzoxazole ring, a benzimidazole ring, a quinoline ring, an isoquinoline ring, a quinoxaline ring, a quinazoline ring, a naphthyridine ring, and a phenanthridine ring. More preferred are a pyridine ring, a pyrazine ring, a pyrimidine ring, an imidazole ring, a benzothiazole ring, a benzoxazole ring, a quinoline ring, an isoquinoline ring, a quinoxaline ring, and a quinazoline ring. More preferred are a pyridine ring, an imidazole ring, a benzothiazole ring, a quinoline ring, an isoquinoline ring, a quinoxaline ring, and a quinazoline ring. Most preferred are a pyridine ring, a benzothiazole ring, a quinoline ring, an isoquinoline ring, a quinoxaline ring, and a quinazoline ring.

The structure in which the single rings are linked is represented by the following formula (203), in which a pyridine ring and a triazine ring are bonded.

In formula (203), *1 represents a bond to ring A1 in formula (201), and *2 represents coordination to M in formula (201).

Preferred combinations of ring A1 and ring A2 for red phosphorescent light-emitting materials, expressed as (ring A1-ring A2), are (benzene ring-pyridine ring-triazine ring), (benzene ring-quinoline ring), (benzene ring-isoquinoline ring), (benzene ring-quinoxaline ring), (benzene ring-quinazoline ring), and (benzene ring-benzothiazole ring).

The substituents which the ring A1 and the ring A2 may have can be arbitrarily selected, but are preferably one or more kinds of substituents selected from the [Substituent group S] described below.
The substituents bonded to ring A1 may be bonded to each other, the substituents bonded to ring A2 may be bonded to each other, or the substituents bonded to ring A1 and the substituents bonded to ring A2 may be bonded to each other to form a ring.

(Ar ²⁰¹ , Ar ²⁰² , Ar ²⁰³ )
In the above formula (201), Ar ²⁰¹ represents a divalent aromatic hydrocarbon ring structure which may have a substituent, or a divalent aromatic heterocyclic structure which may have a substituent. When multiple Ar ²⁰¹ are present, they may be the same or different.
In the above formula (201), Ar ²⁰² represents a divalent aromatic hydrocarbon ring structure which may have a substituent, a divalent aromatic heterocyclic ring structure which may have a substituent, or a substituted When a plurality of Ar ²⁰² are present, they may be the same or different.
In the above formula (201), Ar ²⁰³ represents a monovalent aromatic hydrocarbon ring structure which may have a substituent, or a monovalent aromatic heterocyclic structure which may have a substituent. When there are multiple Ar ²⁰³ , they may be the same or different.

When any of Ar ²⁰¹ , Ar ²⁰² , and Ar ²⁰³ is an aromatic hydrocarbon ring structure which may have a substituent, the aromatic hydrocarbon ring structure is preferably an aromatic hydrocarbon ring having a carbon number of 6 to 30. Specifically, a benzene ring, a naphthalene ring, an anthracene ring, a triphenylyl ring, an acenaphthene ring, a fluoranthene ring, or a fluorene ring is preferred, a benzene ring, a naphthalene ring, or a fluorene ring is more preferred, and a benzene ring is most preferred.

When any of Ar ²⁰¹ , Ar ²⁰² and Ar ²⁰³ is a fluorene ring which may have a substituent, the 9- and 9'-positions of the fluorene ring preferably have a substituent or are bonded to an adjacent structure.

When any of Ar ²⁰¹ , Ar ²⁰² , and Ar ²⁰³ is a benzene ring which may have a substituent, it is preferable that at least one benzene ring is bonded to an adjacent structure at an ortho position or a meta position, and it is more preferable that at least one benzene ring is bonded to an adjacent structure at a meta position.

When any of Ar ²⁰¹ , Ar ²⁰² and Ar ²⁰³ is an aromatic heterocyclic structure which may have a substituent, the aromatic heterocyclic structure is preferably an aromatic heterocyclic ring having 3 to 30 carbon atoms and containing a nitrogen atom, an oxygen atom or a sulfur atom as a heteroatom.
Specific examples include a pyridine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, an imidazole ring, an oxazole ring, a thiazole ring, a benzothiazole ring, a benzoxazole ring, a benzimidazole ring, a quinoline ring, an isoquinoline ring, a quinoxaline ring, a quinazoline ring, a naphthyridine ring, a phenanthridine ring, a carbazole ring, a dibenzofuran ring, and a dibenzothiophene ring, and preferably a pyridine ring, a pyrimidine ring, a triazine ring, a carbazole ring, a dibenzofuran ring, or a dibenzothiophene ring.

When any of Ar ²⁰¹ , Ar ²⁰² and Ar ²⁰³ is a carbazole ring which may have a substituent, the N-position of the carbazole ring preferably has a substituent or is bonded to an adjacent structure.

When Ar ²⁰² is an aliphatic hydrocarbon structure which may have a substituent, the aliphatic hydrocarbon structure is an aliphatic hydrocarbon structure having a straight chain, branched chain, or cyclic structure, preferably an aliphatic hydrocarbon structure having 1 to 24 carbon atoms, more preferably an aliphatic hydrocarbon structure having 1 to 12 carbon atoms, and still more preferably an aliphatic hydrocarbon structure having 1 to 8 carbon atoms.

(i1, i2, i3, j, k1, k2, m)
In the above formula (201), i1 and i2 each independently represent an integer of 0 or more and 12 or less.
Each of i1 and i2 is independently preferably an integer of 1 to 12, more preferably an integer of 1 to 8, and further preferably an integer of 1 to 6. By being in this range, the solubility and charge transport It is expected to improve sexual function.

In the above formula (201), i3 is an integer of 0 or more, which is the upper limit of the number that can be substituted for Ar ²⁰² .
i3 preferably represents an integer of 0 to 5, more preferably an integer of 0 to 2, and even more preferably 0 or 1.

In the above formula (201), j is an integer of 0 or more, which is the upper limit of the number that can be substituted on Ar ²⁰¹ .
j preferably represents an integer of 0 to 2, and more preferably 0 or 1.

In the above formula (201), k1 and k2 each independently represent an integer of 0 or more, which is the upper limit of the number that can be substituted on ring A1 and ring A2.
k1 and k2 each preferably represent an integer of 0 to 3, more preferably an integer of 1 to 3, even more preferably 1 or 2, and particularly preferably 1.

In the above formula (201), m is an integer of 1 to 3.
m preferably represents an integer of 2 or 3, and particularly preferably 3.

(Substituent)
The substituents that Ring A1, Ring A2, Ar ²⁰¹ , Ar ²⁰² , and Ar ²⁰³ may have can be selected arbitrarily, but are preferably one or more substituents selected from the following [Substituent Group S], more preferably an alkyl group or an aryl group, particularly preferably an alkyl group, and most preferably unsubstituted.

[Substituent Group S]
An alkyl group, preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 12 carbon atoms, still more preferably an alkyl group having 1 to 8 carbon atoms, and particularly preferably an alkyl group having 1 to 6 carbon atoms.
An alkoxy group, preferably an alkoxy group having 1 to 20 carbon atoms, more preferably an alkoxy group having 1 to 12 carbon atoms, and even more preferably an alkoxy group having 1 to 6 carbon atoms.
An aryloxy group, preferably an aryloxy group having 6 to 20 carbon atoms, more preferably an aryloxy group having 6 to 14 carbon atoms, even more preferably an aryloxy group having 6 to 12 carbon atoms, and particularly preferably an aryloxy group having 6 carbon atoms.
A heteroaryloxy group, preferably a heteroaryloxy group having 3 to 20 carbon atoms, more preferably a heteroaryloxy group having 3 to 12 carbon atoms.
An alkylamino group, preferably an alkylamino group having 1 to 20 carbon atoms, more preferably an alkylamino group having 1 to 12 carbon atoms.
An arylamino group, preferably an arylamino group having 6 to 36 carbon atoms, more preferably an arylamino group having 6 to 24 carbon atoms.
An aralkyl group, preferably an aralkyl group having 7 to 40 carbon atoms, more preferably an aralkyl group having 7 to 18 carbon atoms, and even more preferably an aralkyl group having 7 to 12 carbon atoms.
A heteroaralkyl group, preferably a heteroaralkyl group having 7 to 40 carbon atoms, more preferably a heteroaralkyl group having 7 to 18 carbon atoms.
An alkenyl group, preferably an alkenyl group having 2 to 20 carbon atoms, more preferably an alkenyl group having 2 to 12 carbon atoms, even more preferably an alkenyl group having 2 to 8 carbon atoms, and particularly preferably an alkenyl group having 2 to 6 carbon atoms.
An alkynyl group, preferably an alkynyl group having 2 to 20 carbon atoms, more preferably an alkynyl group having 2 to 12 carbon atoms.
An aryl group, preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 24 carbon atoms, still more preferably an aryl group having 6 to 18 carbon atoms, and particularly preferably an aryl group having 6 to 14 carbon atoms.
A heteroaryl group, preferably a heteroaryl group having 3 to 30 carbon atoms, more preferably a heteroaryl group having 3 to 24 carbon atoms, still more preferably a heteroaryl group having 3 to 18 carbon atoms, and particularly preferably a heteroaryl group having 3 to 14 carbon atoms.
An alkylsilyl group, preferably an alkylsilyl group having an alkyl group with 1 to 20 carbon atoms, and more preferably an alkylsilyl group having an alkyl group with 1 to 12 carbon atoms.
An arylsilyl group, preferably an arylsilyl group having 6 to 20 carbon atoms in the aryl group, and more preferably an arylsilyl group having 6 to 14 carbon atoms in the aryl group.
An alkylcarbonyl group, preferably an alkylcarbonyl group having 2 to 20 carbon atoms.
An arylcarbonyl group, preferably an arylcarbonyl group having 7 to 20 carbon atoms.
A hydrogen atom, a deuterium atom, a fluorine atom, a cyano group, or _--SF.sub.5 .

In the above groups, one or more hydrogen atoms may be replaced with a fluorine atom, or one or more hydrogen atoms may be replaced with a deuterium atom.

Unless otherwise specified, an aryl group is an aromatic hydrocarbon group, and a heteroaryl group is an aromatic heterocyclic group.

(Preferred groups in [Substituent group S])
Among the above [Substituent group S],
Preferred are an alkyl group, an alkoxy group, an aryloxy group, an arylamino group, an aralkyl group, an alkenyl group, an aryl group, a heteroaryl group, an alkylsilyl group, an arylsilyl group, a group in which one or more hydrogen atoms of these groups are replaced with fluorine atoms, a fluorine atom, a cyano group, or _-SF5 .
More preferably, it is an alkyl group, an arylamino group, an aralkyl group, an alkenyl group, an aryl group, a heteroaryl group, a group in which one or more hydrogen atoms of these groups are replaced with fluorine atoms, a fluorine atom, a cyano group, or _-SF5 .
More preferred are an alkyl group, an alkoxy group, an aryloxy group, an arylamino group, an aralkyl group, an alkenyl group, an aryl group, a heteroaryl group, an alkylsilyl group, and an arylsilyl group.
Particularly preferred are an alkyl group, an arylamino group, an aralkyl group, an alkenyl group, an aryl group, and a heteroaryl group.
Most preferred are an alkyl group, an arylamino group, an aralkyl group, an aryl group and a heteroaryl group.

These [Substituent group S] may further have a substituent selected from [Substituent group S] as a substituent. The preferred groups, more preferred groups, even more preferred groups, particularly preferred groups, and most preferred groups of the substituents that may be had are the same as the preferred groups in [Substituent group S].

(B ²⁰¹ -L ²⁰⁰ -B ²⁰² )
In the above formula (201), B ²⁰¹ -L ²⁰⁰ -B ²⁰² represent an anionic bidentate ligand. B ²⁰¹ and B ²⁰² each independently represent a carbon atom, an oxygen atom, or a nitrogen atom. These atoms may be atoms constituting a ring. L ²⁰⁰ represents a single bond or an atomic group constituting a bidentate ligand together with B ²⁰¹ and B ^202. B ²⁰¹ -L ²⁰⁰ -B When there are multiple ²⁰² , they may be the same or different.
The structure represented by B ²⁰¹ -L ²⁰⁰ -B ²⁰² is preferably a structure represented by the following formula (203) or (204).

R ²¹¹ , R ²¹² and R ²¹³ each represent a substituent. The substituent is not particularly limited, but is preferably a group selected from the above [Substituent Group S].

Ring B3 represents an aromatic heterocyclic structure containing a nitrogen atom which may have a substituent.
Ring B3 is preferably a pyridine ring.
The substituent that Ring B3 may have is not particularly limited, but is preferably a group selected from the above [Substituent Group S].

(Preferred structure of formula (201))
Among the structures represented by the formula (202) in the formula (201), a structure having a group linked to benzene rings, a structure having an aromatic hydrocarbon group or an aromatic heterocyclic group to which an alkyl group or an aralkyl group is bonded to ring A1 or ring A2, and a structure having a dendron bonded to ring A1 or ring A2 are preferable.

In the structure having a group linked to a benzene ring,
Ar ²⁰¹ is a benzene ring structure, i1 is an integer of 1 to 6, and at least one of the benzene rings is bonded to an adjacent structure at the ortho or meta position.
This structure is expected to improve the solubility and charge transport properties.

In the structure having an aromatic hydrocarbon group or aromatic heterocyclic group to which an alkyl group or an aralkyl group is bonded in the ring A1 or the ring A2,
Ar ²⁰¹ is an aromatic hydrocarbon ring structure or an aromatic heterocyclic ring structure, i1 is an integer of 1 to 6,
Ar ²⁰² is an aliphatic hydrocarbon structure, i2 is an integer of 1 to 12, preferably an integer of 3 to 8,
When Ar ²⁰³ is present, it is a benzene ring structure, and i3 is 0 or 1. In the case of this structure, Ar ²⁰¹ is preferably the aromatic hydrocarbon ring structure, more preferably a structure in which 1 to 5 benzene rings are linked, and more preferably one benzene ring.
This structure is expected to improve the solubility and charge transport properties.

In the structure in which a dendron is bonded to ring A1 or ring A2,
Ar ²⁰¹ and Ar ^{202 each} represent a benzene ring structure;
Ar ²⁰³ is a benzene ring structure, a biphenyl structure or a terphenyl structure;
i1 and i2 each independently represents an integer from 1 to 6, i3 is 2, and j is 2.
This structure is expected to improve the solubility and charge transport properties.

(Specific example)
The red-emitting phosphorescent material represented by formula (201) is not particularly limited, but specific examples thereof include the following structures.
In addition, Me means a methyl group, and Ph means a phenyl group.

(Equation (205))
The compound represented by the following formula (205) will be described below.

In formula (205), ^M2 represents a metal, T represents a carbon atom or a nitrogen atom, and ^R92 to ^R95 each independently represent a substituent, provided that when T is a nitrogen atom, ^R94 and ^R95 do not exist.

In formula (205), ^M2 represents a metal. Specific examples include metals selected from Groups 7 to 11 of the periodic table. Among these, preferred are ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold, and particularly preferred are divalent metals such as platinum and palladium.

In addition, in formula (205), R ⁹² and R ⁹³ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, a cyano group, an amino group, an acyl group, an alkoxycarbonyl group, a carboxyl group, an alkoxy group, an alkylamino group, an aralkylamino group, a haloalkyl group, a hydroxyl group, an aryloxy group, an aromatic hydrocarbon group, or an aromatic heterocyclic group.

Furthermore, when T is a carbon atom, R ⁹⁴ and R ⁹⁵ each independently represent a substituent represented by the same examples as R ⁹² and R ^93. When T is a nitrogen atom, R ⁹⁴ or R ⁹⁵ does not exist that is directly bonded to T.

Furthermore, R ⁹² to R ⁹⁵ may further have a substituent. The substituent may be the same as those exemplified for R ⁹² and R ^93. Furthermore, any two or more groups among R ⁹² to R ⁹⁵ may be bonded to each other to form a ring.

(Molecular Weight)
The molecular weight of the phosphorescent material is preferably 5000 or less, more preferably 4000 or less, particularly preferably 3000 or less. The molecular weight of the phosphorescent material is usually 1000 or more, preferably 1100 or more, and more preferably 1200 or more. It is believed that by having the molecular weight within this range, the phosphorescent materials do not aggregate with each other and can be uniformly mixed with the iridium complex compound of the present invention and/or other charge transport materials, thereby making it possible to obtain a light-emitting layer with high luminous efficiency.

The molecular weight of the phosphorescent material is preferably large in that it has a high Tg, melting point, decomposition temperature, etc., and the heat resistance of the phosphorescent material and the formed light-emitting layer is excellent, and that deterioration of film quality due to gas generation, recrystallization, molecular migration, etc., and an increase in impurity concentration due to thermal decomposition of the material are unlikely to occur. On the other hand, the molecular weight of the phosphorescent material is preferably small in that it is easy to purify the organic compound.

[Iridium complex compound-containing composition]
Since the iridium complex compound of the present invention has excellent solubility in a solvent, it is preferably used together with a solvent. Hereinafter, a composition containing the iridium complex compound of the present invention and a solvent (hereinafter, sometimes referred to as an "iridium complex compound-containing composition") will be described.

The iridium complex compound-containing composition according to the present invention contains the iridium complex compound of the present invention and a solvent. The iridium complex compound-containing composition according to the present invention is usually used to form a layer or film by a wet film-forming method, and is preferably used to form an organic layer of an organic electroluminescent device. The organic layer is preferably a light-emitting layer. In other words, the iridium complex compound-containing composition is preferably a composition for organic electroluminescent devices, i.e., the composition for organic electroluminescent devices according to the present invention, and is particularly preferably used as a composition for forming a light-emitting layer.

The content of the iridium complex compound of the present invention in the iridium complex compound-containing composition is usually 0.001% by mass or more, preferably 0.01% by mass or more, and usually 99.9% by mass or less, preferably 99% by mass or less. By setting the content of the iridium complex compound in the composition within this range, holes and electrons are efficiently injected from adjacent layers (e.g., hole transport layer and hole blocking layer) to the light-emitting layer, and the driving voltage can be reduced. The iridium complex compound of the present invention may be contained in the iridium complex compound-containing composition alone or in a combination of two or more types.

When the iridium complex compound-containing composition according to the present invention is used as a composition for organic electroluminescence elements, for example, for organic electroluminescence elements, it may contain, in addition to the above-mentioned iridium complex compound and solvent, the above-mentioned red light-emitting material, preferably a phosphorescent light-emitting material and a charge-transporting compound, which are used in the organic electroluminescence element, particularly in the light-emitting layer.
When the iridium complex compound-containing composition according to the present invention is used to form a light-emitting layer of an organic electroluminescent device, the iridium complex compound according to the present invention can be used as an assist dopant in combination with a red light-emitting material as described above. Alternatively, since the iridium complex compound according to the present invention itself emits light in the range of yellow-green to yellow to orange, the complex compound itself can be used as a light-emitting material and another charge-transporting compound can be included as a charge-transporting host material.

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

Among these, alkanes and aromatic hydrocarbons are preferable, and in particular, phenylcyclohexane has a viscosity and boiling point suitable for the wet film formation process.
These solvents may be used alone or in any combination of two or more in any ratio.
The boiling point of the solvent used is usually 80° C. or higher, preferably 100° C. or higher, more preferably 120° C. or higher, and usually 270° C. or lower, preferably 250° C. or lower, more preferably 230° C. or lower. If the boiling point is below this range, the film formation stability may decrease due to evaporation of the solvent from the composition during wet film formation.

The content of the solvent in the iridium complex compound-containing composition 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% by mass or less, particularly preferably 99% by mass or less. The thickness of the light-emitting layer is usually about 3 to 200 nm, but if the solvent content falls below this lower limit, the viscosity of the composition becomes too high, which may reduce the workability of film formation. On the other hand, if the solvent content exceeds this upper limit, the thickness of the film obtained by removing the solvent after film formation cannot be achieved, which tends to make film formation difficult.

The content of the red light-emitting material, such as the phosphorescent material, contained in the iridium complex compound-containing composition as a composition for organic electroluminescent elements is usually 0.01 parts by mass or more, preferably 0.2 parts by mass or more, more preferably 0.25 parts by mass or more, and usually 10 parts by mass or less, preferably 4 parts by mass or less, more preferably 2 parts by mass or less, per 1 part by mass of the iridium complex compound of the present invention in the iridium complex compound-containing composition. If the content of the red light-emitting material is less than the above lower limit, the iridium complex compound of the present invention itself may emit light, and the color purity as red may decrease. If the content is more than the above upper limit, the proportion of the red light-emitting material that the assist dopant can contribute to is too small, and the device performance may decrease.

As other charge transporting compounds that may be contained in the iridium complex compound-containing composition according to the present invention, those that have been used as materials for conventional organic electroluminescent devices can be used.
Examples of the compound include pyridine, carbazole, naphthalene, perylene, pyrene, anthracene, chrysene, naphthacene, phenanthrene, coronene, fluoranthene, benzophenanthrene, fluorene, acetonaphthofluoranthene, coumarin, p-bis(2-phenylethenyl)benzene and derivatives thereof, quinacridone derivatives, DCM (4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran)-based compounds, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, azabenzothioxanthene, condensed aromatic ring compounds substituted with an arylamino group, and styryl derivatives substituted with an arylamino group.

These may be used alone or in any combination of two or more in any ratio.
The content of other charge transport compounds in the iridium complex compound-containing composition is usually 1,000 parts by mass or less, preferably 100 parts by mass or less, and more preferably 50 parts by mass or less, and usually 0.01 parts by mass or more, preferably 0.1 parts by mass or more, and more preferably 1 part by mass or more, relative to 1 part by mass of the iridium complex compound of the present invention in the iridium complex compound-containing composition.

The iridium complex compound-containing composition according to the present invention may contain other compounds in addition to the above compounds, etc., as necessary. For example, in addition to the above solvents, another solvent may be contained. Examples of such solvents include amides such as N,N-dimethylformamide and N,N-dimethylacetamide, and dimethyl sulfoxide. These may be used alone or in any combination and ratio of two or more types.

(Ink for forming light-emitting layer of coating-type organic electroluminescent device)
The iridium complex compound-containing composition according to the present invention can be preferably used as an ink for forming a light-emitting layer of a coating-type organic electroluminescent device for forming a light-emitting layer by a wet film-forming method. Preferred aspects of the components and characteristics contained in the ink for forming a light-emitting layer of a coating-type organic electroluminescent device according to the present invention are the same as those described above for the iridium complex compound-containing composition according to the present invention.
From the viewpoint of exhibiting high luminous efficiency as a red light emitting element, specifically, the ink for forming the light emitting layer of the coating type organic electroluminescent element according to the present invention preferably contains the iridium complex compound of the present invention, the above-mentioned red light emitting material, and an organic solvent, and preferably contains as the red light emitting material a red light emitting material having a maximum emission wavelength of 600 nm or more, and it is more preferable that the red light emitting material is the iridium complex compound represented by the above-mentioned formula (201).

[Organic electroluminescent element]
An organic electroluminescent device can be manufactured using an iridium complex compound-containing composition containing the above-mentioned iridium complex compound of the present invention as a composition for organic electroluminescent devices, and the manufactured organic electroluminescent device (hereinafter, may be referred to as "organic electroluminescent device of the present invention") contains the iridium complex compound of the present invention.
The organic electroluminescent device of the present invention preferably has at least an anode, a cathode, and at least one organic layer between the anode and the cathode on a substrate, and at least one of the organic layers contains the iridium complex compound of the present invention. The organic layer includes a light-emitting layer.

The organic layer containing the iridium complex compound of the present invention is more preferably a layer formed using the composition for organic electroluminescent elements of the present invention, and even more preferably a layer formed by a wet film-forming method. The layer formed by the wet film-forming method is preferably the light-emitting layer.

In the present invention, the wet film formation method refers to a film formation method, i.e., a coating method, which employs a wet film formation method such as spin coating, dip coating, die coating, bar coating, blade coating, roll coating, spray coating, capillary coating, inkjet printing, nozzle printing, screen printing, gravure printing, flexographic printing, etc., and then dries the film formed by these methods to form a film.

FIG. 1 is a schematic cross-sectional view showing a preferred structural example of an organic electroluminescent device 10 of the present invention. In FIG. 1, reference numeral 1 denotes a substrate, reference numeral 2 denotes an anode, reference numeral 3 denotes a hole injection layer, reference numeral 4 denotes a hole transport layer, reference numeral 5 denotes a light-emitting layer, reference numeral 6 denotes a hole blocking layer, reference numeral 7 denotes an electron transport layer, reference numeral 8 denotes an electron injection layer, and reference numeral 9 denotes a cathode.
The materials applied to these structures can be known materials and are not particularly limited, but representative materials and manufacturing methods for each layer are described below as examples. In addition, when publications, papers, etc. are cited, the relevant contents are assumed to be applicable and applicable as appropriate within the scope of common sense of a person skilled in the art.

<Substrate 1>
The substrate 1 is a support for the organic electroluminescent element, and is usually made of a quartz or glass plate, a metal plate or metal foil, a plastic film or sheet, or the like. Of these, a glass plate or a plate made of a transparent synthetic resin such as polyester, polymethacrylate, polycarbonate, or polysulfone is preferred. The substrate 1 is preferably made of a material with high gas barrier properties, since the organic electroluminescent element is less likely to deteriorate due to the outside air. For this reason, 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 increase the gas barrier properties.

<Anode 2>
The anode 2 has a function of injecting holes into the layer on the light-emitting layer side. The anode 2 is usually made of a metal such as aluminum, gold, silver, nickel, palladium, or platinum, a metal oxide such as indium and/or tin oxide, a metal halide such as copper iodide, or a conductive polymer such as carbon black, poly(3-methylthiophene), polypyrrole, or polyaniline.

The anode 2 is usually formed by a dry method such as sputtering or vacuum deposition. When the anode 2 is formed using fine metal particles such as silver, fine copper iodide particles, carbon black, fine conductive metal oxide particles, fine conductive polymer powder, etc., it can be formed by dispersing them in an appropriate binder resin solution and applying it to the substrate 1. When using a conductive polymer, the anode 2 can be formed by forming a thin film directly on the substrate 1 by electrolytic polymerization, or by applying the conductive polymer to the substrate 1 (Appl. Phys. Lett., Vol. 60, p. 2711, 1992).

The anode 2 usually has a single-layer structure, but may have a laminated structure as appropriate. When the anode 2 has a laminated structure, a different conductive material may be laminated on the first anode layer.
The thickness of the anode 2 may be determined according to the required transparency and material. When particularly high transparency is required, a thickness that provides a visible light transmittance of 60% or more is preferable, and a thickness that provides a visible light transmittance of 80% or more is more preferable. The thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more, and 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 arbitrarily determined according to the required strength, and 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 remove impurities on the anode and adjust its ionization potential to improve hole injection properties by performing a treatment such as ultraviolet light + ozone, oxygen plasma, or argon plasma before forming the film.

<Hole injection layer 3>
A layer that transports holes from the anode 2 side to the light-emitting layer 5 side is usually called a hole injection transport layer or a hole transport layer. When there are two or more layers that transport holes from the anode 2 side to the light-emitting layer 5 side, the layer closer to the anode 2 side may be called a hole injection layer 3. The hole injection layer 3 is preferably used in order to enhance the function of transporting holes from the anode 2 to the light-emitting layer 5 side. When the hole injection layer 3 is used, the hole injection layer 3 is usually formed on the anode 2.

The thickness of the hole injection layer 3 is usually 1 nm or more, preferably 5 nm or more, and usually 1000 nm or less, preferably 500 nm or less.
The hole injection layer 3 may be formed by a vacuum deposition method or a wet film formation method. In terms of excellent film formability, the wet film formation method is preferred.
The hole injection layer 3 preferably contains a hole transporting compound, more preferably contains a hole transporting compound and an electron accepting compound, and further preferably contains a cation radical compound, particularly preferably contains a cation radical compound and a hole transporting compound.

(Hole transport compound)
The composition for forming the hole injection layer usually contains a hole transporting compound that becomes the hole injection layer 3 .
In the case of a wet film formation method, the composition usually further contains a solvent. It is preferable that the composition for forming the hole injection layer has high hole transportability and can efficiently transport injected holes. For this reason, it is preferable that the hole mobility is large and impurities that become traps are unlikely to occur during production or use. It is also preferable that the composition has excellent stability, small ionization potential, and high transparency to visible light. In particular, when the hole injection layer 3 is in contact with the light emitting layer 5, it is preferable that the composition does not quench the light emission from the light emitting layer 5 or does not form an exciplex with the light emitting layer 5 to reduce the light emitting efficiency.

From the viewpoint of the charge injection barrier from the anode 2 to the hole injection layer 3, a compound having an ionization potential of 4.5 eV to 6.0 eV is preferable as the hole transport compound. Examples of hole transport compounds include aromatic amine compounds, phthalocyanine compounds, porphyrin compounds, oligothiophene compounds, polythiophene compounds, benzylphenyl compounds, compounds in which a tertiary amine is linked via a fluorene group, hydrazone compounds, silazane compounds, and quinacridone compounds.

Among the above-mentioned exemplary compounds, aromatic amine compounds are preferred from the viewpoint of amorphousness and visible light transmittance, and aromatic tertiary amine compounds are particularly preferred. Here, the aromatic tertiary amine compounds are compounds having an aromatic tertiary amine structure, and also include compounds having a group derived from an aromatic tertiary amine.
The type of aromatic tertiary amine compound is not particularly limited, but it is preferable to use a polymer compound (polymerized compound having a series of repeating units) having a weight average molecular weight of 1000 to 1,000,000, in terms of the ease of obtaining uniform light emission due to the surface smoothing effect. Preferred examples of aromatic tertiary amine polymer compounds include polymer compounds having a repeating unit represented by the following formula (I).

[In formula (I), Ar ¹¹ and Ar ¹² each independently represent an aromatic group which may have a substituent or an aromatic heterocyclic group which may have a substituent. Ar ¹³ to Ar ¹⁵ each independently represent an aromatic group which may have a substituent or an aromatic heterocyclic group which may have a substituent. Q represents a linking group selected from the following group of linking groups. In addition, among Ar ¹¹ to Ar ¹⁵ , two groups bonded to the same N atom may bond to each other to form a ring.]
The linking groups are shown below.

[In the above formulas, Ar ¹⁶ to Ar ²⁶ each independently represent an aromatic group which may have a substituent or an aromatic heterocyclic group which may have a substituent. R ^a to R ^b each independently represent a hydrogen atom or any substituent.]

As the aromatic group and aromatic heterocyclic group of Ar ¹¹ to Ar ²⁶ , from the viewpoints of the solubility, heat resistance, and hole injection and transport properties of the polymer compound, groups derived from a benzene ring, a naphthalene ring, a phenanthrene ring, a thiophene ring, and a pyridine ring are preferred, and groups derived from a benzene ring and a naphthalene ring are more preferred.
Specific examples of the aromatic tertiary amine polymeric compound having a repeating unit represented by formula (I) include those described in WO 2005/089024.

(Electron Accepting Compound)
The hole injection layer 3 preferably contains an electron accepting compound because the conductivity of the hole injection layer 3 can be improved by oxidation of the hole transporting compound.
As the electron-accepting compound, a compound having an oxidizing power and an ability to accept one electron from the above-mentioned hole-transporting compound is more preferable. Specifically, a compound having an electron affinity of 4 eV or more is more preferable, and a compound having an electron affinity of 5 eV or more is even more preferable.

Examples of such electron-accepting compounds include one or more 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. Specific examples include onium salts substituted with organic groups such as 4-isopropyl-4'-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate and triphenylsulfonium tetrafluoroborate (WO 2005/089024); high-valent inorganic compounds such as iron(III) chloride (JP 11-251067 A) and ammonium peroxodisulfate; cyano compounds such as tetracyanoethylene; aromatic boron compounds such as tris(pentafluorophenyl)borane (JP 2003-31365 A); fullerene derivatives, and iodine.

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

The cation radical is preferably a chemical species obtained by removing one electron from the compound described above as the hole transporting compound, which is preferable in terms of amorphousness, visible light transmittance, heat resistance, solubility, etc.
Here, the cation radical compound can be generated by mixing the above-mentioned hole transporting compound and the electron accepting compound. That is, by mixing the above-mentioned hole transporting compound and the electron accepting compound, electrons are transferred from the hole transporting compound to the electron accepting compound, and a cation ion compound consisting of the cation radical of the hole transporting compound and a counter anion is generated.

Cation radical compounds derived from polymer compounds such as PEDOT/PSS (Adv. Mater., 2000, vol. 12, p. 481) and emeraldine hydrochloride (J. Phys. Chem., 1990, vol. 94, p. 7716) can also be produced by oxidative polymerization (dehydrogenative polymerization).
The oxidative polymerization referred to here is a method in which a monomer is chemically or electrochemically oxidized in an acidic solution using peroxodisulfate or the like. In the case of this oxidative polymerization (dehydrogenative polymerization), the monomer is oxidized to polymerize, and a cation radical is generated by removing one electron from the repeating unit of the polymer, with the anion derived from the acidic solution as the counter anion.

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

The concentration of the hole transport compound in the composition for forming the hole injection layer is arbitrary as long as it does not significantly impair the effects of the present invention, but in terms of uniformity of the film thickness, a lower concentration is preferable, while in terms of preventing defects from occurring in the hole injection layer 3, a higher concentration is preferable. The concentration of the hole transport compound in the composition for forming the hole injection layer is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and particularly preferably 0.5% by mass or more, while preferably 70% by mass or less, more preferably 60% by mass or less, and particularly preferably 50% by mass or less.

Examples of the solvent include ether-based solvents, ester-based solvents, aromatic hydrocarbon-based solvents, and amide-based solvents.
Examples of the ether solvent include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA), and aromatic ethers such as 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, and 2,4-dimethylanisole.

Examples of the ester solvent include aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate.
Examples of aromatic hydrocarbon solvents include toluene, xylene, cyclohexylbenzene, 3-isopropylbiphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, and methylnaphthalene.

Examples of the amide solvent include N,N-dimethylformamide and N,N-dimethylacetamide.
In addition, dimethyl sulfoxide and the like can also be used.
The formation of the hole injection layer 3 by a wet film formation method is usually carried out by preparing a composition for forming the hole injection layer, applying the composition to a layer (usually the anode 2) corresponding to the layer below the hole injection layer 3 to form a film, and drying the composition. After the hole injection layer 3 is formed, the applied film is usually dried by heating, drying under reduced pressure, or the like.

(Formation of Hole Injection Layer 3 by Vacuum Deposition Method)
When forming the hole injection layer 3 by the vacuum deposition method, one or more of the constituent materials of the hole injection layer 3 (such as the above-mentioned hole transporting compound and electron accepting compound) are usually placed in a crucible installed in a vacuum container (when two or more materials are used, each is usually placed in a separate crucible), and the inside of the vacuum container is evacuated to about 1.0 × 10 ^-4 Pa with a vacuum pump, and then the crucible is heated (when two or more materials are used, each crucible is usually heated), and the material in the crucible is evaporated while controlling the evaporation amount (when two or more materials are used, each is usually evaporated while controlling the evaporation amount independently), and the hole injection layer 3 is formed on the anode 2 on the substrate placed opposite the crucible. Note that when two or more materials are used, a mixture of those materials can also be placed in a crucible, heated, and evaporated to form the hole injection layer 3.

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

<Hole transport layer 4>
The hole transport layer 4 is a layer that transports holes from the anode 2 side to the light emitting layer 5 side. Although the hole transport layer 4 is not an essential layer in the organic electroluminescent device of the present invention, it is preferable to provide this layer in terms of enhancing 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. Furthermore, when the above-mentioned hole injection layer 3 is present, it is formed between the hole injection layer 3 and the light emitting layer 5.

The thickness of the hole transport layer 4 is usually 5 nm or more, preferably 10 nm or more, and on the other hand, usually 300 nm or less, preferably 100 nm or less.
The hole transport layer 4 may be formed by a vacuum deposition method or a wet film formation method. In terms of excellent film formability, the wet film formation method is preferred.

The hole transport layer 4 usually contains a hole transport compound that becomes the hole transport layer 4. Examples of the hole transport compound contained in the hole transport layer 4 include aromatic diamines containing two or more tertiary amines and having two or more condensed aromatic rings substituted with nitrogen atoms, such as 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (JP Patent Publication No. 5-234681), and aromatic amine compounds having a starburst structure, such as 4,4',4''-tris(1-naphthylphenylamino)triphenylamine (J. Lumin. , vol. 72-74, p. 985, 1997), aromatic amine compounds consisting of triphenylamine tetramers (Chem. Commun., p. 2175, 1996), spiro compounds such as 2,2',7,7'-tetrakis-(diphenylamino)-9,9'-spirobifluorene (Synth. Metals, vol. 91, p. 209, 1997), carbazole derivatives such as 4,4'-N,N'-dicarbazole biphenyl, etc. Also preferably used are polyvinyl carbazole, polyvinyl triphenylamine (JP-A-7-53953), polyarylene ether sulfone containing tetraphenylbenzidine (Polym. Adv. Tech., vol. 7, p. 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, it is usually formed using a composition for forming a hole transport layer instead of the composition for forming a hole injection layer, in the same manner as when the above-mentioned hole injection layer 3 is formed by a wet film formation method.
When the hole transport layer 4 is formed by a wet film formation method, the composition for forming a hole transport layer usually further contains a solvent. The solvent used in the composition for forming a hole transport layer may be the same as the solvent used in the composition for forming a hole injection layer described above.

The concentration of the hole transporting compound in the composition for forming a hole transport layer can be in the same range as the concentration of the hole transporting compound in the composition for forming a hole injection layer.
The hole transport layer 4 can be formed by a wet film formation method similar to the above-mentioned method for forming the hole injection layer 3 .

(Formation of Hole Transport Layer 4 by Vacuum Deposition)
When the hole transport layer 4 is formed by the vacuum deposition method, it can be formed in the same manner as when the hole injection layer 3 is formed by the vacuum deposition method, by using the material of the hole transport layer 4 instead of the material of the hole injection layer 3. The film formation conditions such as the degree of vacuum, deposition rate, and temperature during deposition can be the same as those during the vacuum deposition of the hole injection layer 3.

<Light-emitting layer 5>
The light-emitting layer 5 is a layer that is excited by the recombination of holes injected from the anode 2 and electrons injected from the cathode 9 when an electric field is applied between the pair of electrodes, and thus emits light.
The light-emitting layer 5 is a layer formed between the anode 2 and the cathode 9. When the hole injection layer 3 is present on the anode 2, the light-emitting layer 5 is formed between the hole injection layer 3 and the cathode 9. When the hole transport layer 4 is present on the anode 2, the light-emitting layer 5 is formed between the hole transport layer 4 and the cathode 9.

The thickness of the light-emitting layer 5 can be any thickness as long as it does not significantly impair the effects of the present invention. However, a thicker layer is preferable in that defects are less likely to occur in the film, and a thinner layer is preferable in that it is easier to achieve a low driving voltage. For this reason, the thickness of the light-emitting layer 5 is preferably 3 nm or more, more preferably 5 nm or more, and usually preferably 200 nm or less, more preferably 100 nm or less.

The light-emitting layer 5 contains at least a material having light-emitting properties (light-emitting material), and preferably also contains a material having charge transport properties (charge transport material).
As the light-emitting material, it is sufficient that any one of the light-emitting layers contains the iridium complex compound of the present invention, and other light-emitting materials may also be used appropriately.
From the viewpoint of exhibiting high luminous efficiency as a red light-emitting element, the organic electroluminescent element of the present invention preferably contains in the light-emitting layer 5 the iridium complex compound of the present invention and the above-mentioned red light-emitting material, preferably contains as the red light-emitting material a red light-emitting material having a maximum emission wavelength of 600 nm or more, and more preferably the red light-emitting material is the iridium complex compound represented by the above-mentioned formula (201).
Hereinafter, light-emitting materials other than the iridium complex compound of the present invention will be described in detail.

(Light Emitting Material)
The light-emitting material is not particularly limited as long as it emits light at a desired emission wavelength and does not impair the effects of the present invention, and any known light-emitting material can be used. The light-emitting material may be a fluorescent material or a phosphorescent material, but a material with good luminous efficiency is preferred, and a phosphorescent material is preferred from the viewpoint of internal quantum efficiency. Specifically, the light-emitting material is preferably the red light-emitting material described above.

Examples of the fluorescent material include the following materials.
Examples of fluorescent light-emitting materials that give blue light (blue fluorescent light-emitting materials) include naphthalene, perylene, pyrene, anthracene, coumarin, chrysene, p-bis(2-phenylethenyl)benzene, and derivatives thereof.
Examples of fluorescent materials that emit green light (green fluorescent materials) include quinacridone derivatives, coumarin derivatives, and aluminum complexes such as Al(C ₉ H ₆ NO) ₃ .

Examples of fluorescent light-emitting materials that give yellow light emission (yellow fluorescent light-emitting materials) include rubrene and perimidon derivatives.
Examples of fluorescent materials that emit red light (red fluorescent materials) include DCM (4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran) compounds, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, and azabenzothioxanthene.

Examples of phosphorescent materials include organometallic complexes containing a metal selected from Groups 7 to 11 of the long-form periodic table (hereinafter, unless otherwise specified, the term "periodic table" refers to the long-form periodic table). Preferred examples of metals selected from Groups 7 to 11 of the periodic table include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold.

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

Specific examples of preferred phosphorescent materials include phenylpyridine complexes such as tris(2-phenylpyridine)iridium, tris(2-phenylpyridine)ruthenium, tris(2-phenylpyridine)palladium, bis(2-phenylpyridine)platinum, tris(2-phenylpyridine)osmium, and tris(2-phenylpyridine)rhenium, as well as porphyrin complexes such as octaethylplatinum porphyrin, octaphenylplatinum porphyrin, octaethylpalladium porphyrin, and octaphenylpalladium porphyrin.

Polymer-based light-emitting materials include polyfluorene-based materials such as poly(9,9-dioctylfluorene-2,7-diyl), poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl))diphenylamine)], and poly[(9,9-dioctylfluorene-2,7-diyl)-co-(1,4-benzo-2{2,1'-3}-triazole)], and polyphenylenevinylene-based materials such as poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene].

(Charge Transporting Material)
The charge transporting material is a material that has a positive charge (hole) or negative charge (electron) transporting property, and is not particularly limited as long as it does not impair the effects of the present invention, and any known material can be used.
As the charge transporting material, compounds conventionally used in the light emitting layer 5 of an organic electroluminescent device can be used, and in particular, compounds used as a host material in the light emitting layer 5 are preferred.

Specific examples of charge transport materials include aromatic amine compounds, phthalocyanine compounds, porphyrin compounds, oligothiophene compounds, polythiophene compounds, benzylphenyl compounds, compounds in which a tertiary amine is linked via a fluorene group, hydrazone compounds, silazane compounds, silanamine compounds, phosphamine compounds, and quinacridone compounds, which are listed as examples of hole transport compounds for the hole injection layer 3. In addition, examples of charge transport materials include electron transport compounds such as anthracene compounds, pyrene compounds, carbazole compounds, pyridine compounds, phenanthroline compounds, oxadiazole compounds, and silole compounds.

Other examples of charge transport materials include aromatic diamines containing two or more tertiary amines, such as 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl, in which two or more condensed aromatic rings are substituted with nitrogen atoms (JP Patent Publication 5-234681), aromatic amine compounds having a starburst structure, such as 4,4',4''-tris(1-naphthylphenylamino)triphenylamine (J. Lumin., Vol. 72-74, p. 985, 1997), and triphenylamine. Also preferably usable are the compounds exemplified as the hole transport compound for the hole transport layer 4, such as aromatic amine compounds consisting of a tetramer of diphenylamine (Chem. Commun., p. 2175, 1996), fluorene compounds such as 2,2',7,7'-tetrakis-(diphenylamino)-9,9'-spirobifluorene (Synth. Metals, vol. 91, p. 209, 1997), and carbazole compounds such as 4,4'-N,N'-dicarbazolebiphenyl. Other examples include oxadiazole compounds such as 2-(4-biphenylyl)-5-(p-tert-butylphenyl)-1,3,4-oxadiazole (tBu-PBD) and 2,5-bis(1-naphthyl)-1,3,4-oxadiazole (BND), silole compounds such as 2,5-bis(6'-(2',2"-bipyridyl))-1,1-dimethyl-3,4-diphenylsilole (PyPySPyPy), and phenanthroline compounds such as bathophenanthroline (BPhen) and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP, bathocuproine).

(Formation of the light-emitting layer 5 by a wet film formation method)
The method for forming the light-emitting layer 5 may be a vacuum deposition method or a wet film-forming method, but the wet film-forming method is preferred because of its excellent film-forming properties. In particular, it is preferred to form the light-emitting layer 5 by the wet film-forming method using the composition for organic electroluminescent elements of the present invention.
When the light-emitting layer 5 is formed by a wet film-forming method, it is usually formed using a composition for forming a light-emitting layer prepared by mixing a material for the light-emitting layer 5 with a soluble solvent (solvent for the light-emitting layer) instead of the composition for forming a hole-injection layer, in the same manner as in the case of forming the hole-injection layer 3 described above by a wet film-forming method. In the present invention, it is preferable to use the composition for forming an organic electroluminescent element of the present invention, which is the above-mentioned iridium complex compound-containing composition, as the composition for forming the light-emitting layer.

Examples of the solvent include the ether-based solvents, ester-based solvents, aromatic hydrocarbon-based solvents, and amide-based solvents mentioned for forming the hole injection layer 3, as well as alkane-based solvents, halogenated aromatic hydrocarbon-based solvents, aliphatic alcohol-based solvents, alicyclic alcohol-based solvents, aliphatic ketone-based solvents, and alicyclic ketone-based solvents. The solvents used are as exemplified for the iridium complex compound-containing composition according to the present invention, and specific examples of the solvents are given below, but are not limited to these as long as they do not impair the effects of the present invention.

For example, aliphatic ether solvents such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA); aromatic ether solvents such as 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole, and diphenyl ether; aromatic ester solvents such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate; toluene, xylene, mesitylene, cyclohexylbenzene, tetralin, and 3-isopropyl biphenyl. Examples of suitable solvents include aromatic hydrocarbon solvents such as phenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, and methylnaphthalene; amide solvents such as N,N-dimethylformamide and N,N-dimethylacetamide; alkane solvents such as n-decane, cyclohexane, ethylcyclohexane, decalin, and bicyclohexane; halogenated aromatic hydrocarbon solvents such as chlorobenzene, dichlorobenzene, and trichlorobenzene; aliphatic alcohol solvents such as butanol and hexanol; alicyclic alcohol solvents such as cyclohexanol and cyclooctanol; aliphatic ketone solvents such as methyl ethyl ketone and dibutyl ketone; and alicyclic ketone solvents such as cyclohexanone, cyclooctanone, and fenchone. Among these, alkane solvents and aromatic hydrocarbon solvents are particularly preferred.

In order to obtain a more uniform film, it is preferable that the solvent evaporates at an appropriate rate from the liquid film immediately after film formation. For this reason, as described above, the boiling point of the solvent used is usually 80°C or higher, preferably 100°C or higher, more preferably 120°C or higher, and usually 270°C or lower, preferably 250°C or lower, more preferably a boiling point of 230°C or lower.

The amount of the solvent used may be any amount as long as it does not significantly impair the effects of the present invention. However, the total content in the composition for forming an emitting layer, i.e., the composition for an organic electroluminescent device, is preferably high in terms of facilitating film formation due to low viscosity, while being low in terms of facilitating film formation in a thick film.
As described above, the content of the solvent in the composition for organic electroluminescent elements is preferably 1 mass % or more, more preferably 10 mass % or more, particularly preferably 50 mass % or more, and is preferably 99.99 mass % or less, more preferably 99.9 mass % or less, particularly preferably 99 mass % or less.

The solvent can be removed after the wet film formation by heating or reducing pressure. In the heating method, a clean oven or a hot plate is preferable as a heating means for applying heat uniformly to the entire film.
The heating temperature in the heating step is arbitrary as long as it does not significantly impair the effects of the present invention, but a higher temperature is preferable in terms of shortening the drying time, and a lower temperature is preferable in terms of less damage to the material. The upper limit of the heating temperature is usually 250°C or less, preferably 200°C or less, and more preferably 150°C or less. The lower limit of the heating temperature is usually 30°C or more, preferably 50°C or more, and more preferably 80°C or more. A temperature exceeding the upper limit is higher than the heat resistance of the charge transport material or phosphorescent material that is usually used, and may cause decomposition or crystallization, which is not preferable. A temperature below the lower limit is not preferable because it takes a long time to remove the solvent. The heating time in the heating step is appropriately determined depending on the boiling point and vapor pressure of the solvent in the composition for forming the light-emitting layer, the heat resistance of the material, and the heating conditions.

(Formation of the light-emitting layer 5 by vacuum deposition method)
When the light-emitting layer 5 is formed by the vacuum deposition method, one or more of the constituent materials of the light-emitting layer 5 (such as the above-mentioned light-emitting material and charge-transporting compound) are usually placed in a crucible installed in a vacuum vessel (when two or more materials are used, each is usually placed in a separate crucible), and the inside of the vacuum vessel is evacuated to about 1.0×10 ⁻⁴ Pa with a vacuum pump, and then the crucible is heated (when two or more materials are used, each crucible is usually heated) to evaporate the materials in the crucible while controlling the amount of evaporation (when two or more materials are used, each is usually evaporated while controlling the amount of evaporation independently), and the light-emitting layer 5 is formed on the hole injection layer 3 or hole transport layer 4 placed opposite the crucible. When two or more materials are used, a mixture of those materials can also be placed in a crucible and heated and evaporated to form the light-emitting layer 5.

The degree of vacuum during deposition is not limited as long as it does not significantly impair the effects of the present invention, but is usually 0.1×10 ⁻⁶ Torr (0.13×10 ⁻⁴ Pa) or more and 9.0×10 ⁻⁶ Torr (12.0×10 ⁻⁴ Pa) or less. The deposition rate is not limited as long as it does not significantly impair the effects of the present invention, but is usually 0.1 Å/sec or more and 5.0 Å/sec or less. The film formation temperature during deposition is not limited as long as it does not significantly impair the effects of the present invention, but is preferably 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 an electron injection layer 8 described later. The hole blocking layer 6 is a layer laminated on the light emitting layer 5 so as to be in contact with the interface of the light emitting layer 5 on the cathode 9 side.
The hole blocking layer 6 has a role of preventing holes migrating from the anode 2 from reaching the cathode 9, and a role of efficiently transporting electrons injected from the cathode 9 toward the light emitting layer 5. Required physical properties of the material constituting the hole blocking layer 6 include high electron mobility and low hole mobility, a large energy gap (difference between HOMO and LUMO), and a high excited triplet level (T1).

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

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

<Electron transport layer 7>
The electron transport layer 7 is provided between the light emitting layer 5 or the hole blocking layer 6 and the electron injection layer 8 for the purpose of further improving the current efficiency of the element.
The electron transport layer 7 is made of a compound capable of efficiently transporting electrons injected from the cathode 9 between the electrodes to which an electric field is applied, toward the light emitting layer 5. The electron transporting compound used in the electron transport layer 7 is required to have a high efficiency of electron injection from the cathode 9 or the electron injection layer 8, and to have high electron mobility so as to efficiently transport the injected electrons.

Examples of electron transport compounds that satisfy these conditions include metal complexes such as aluminum complexes of 8-hydroxyquinoline (JP Patent Publication 59-194393), metal complexes of 10-hydroxybenzo[h]quinoline, oxadiazole derivatives, distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (US Patent Publication 5,645,948), quinoxaline compounds (JP Patent Publication 6-207169), phenanthroline derivatives (JP Patent Publication 5-331459), 2-t-butyl-9,10-N,N'-dicyanoanthraquinone diimine, n-type hydrogenated amorphous silicon carbide, n-type zinc sulfide, and n-type zinc selenide.

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

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

The thickness of the electron injection layer 8 is preferably 0.1 to 5 nm.
In addition, inserting an extremely thin insulating film (thickness: about 0.1 to 5 nm) such as LiF, MgF ₂ , Li ₂ O, or Cs ₂ CO ₃ as an electron injection layer 8 at the interface between the cathode 9 and the electron transport layer 7 is also an effective method for improving the efficiency of the element (Appl. Phys. Lett., Vol. 70, p. 152, 1997; JP-A-10-74586; IEEE Trans. Electron. Devices, Vol. 44, p. 1245, 1997; SID 04 Digest, p. 154).

Furthermore, organic electron transporting materials, typified by nitrogen-containing heterocyclic compounds such as bathophenanthroline and metal complexes such as aluminum complexes of 8-hydroxyquinoline, are doped with alkali metals such as sodium, potassium, cesium, lithium, rubidium, etc. (described in JP-A-10-270171, JP-A-2002-100478, JP-A-2002-100482, etc.), which improves electron injection and transport properties and enables excellent film quality to be achieved at the same time, which is preferable. In this case, the film thickness is usually 5 nm or more, preferably 10 nm or more, and usually 200 nm or less, preferably 100 nm or less.
The electron injection layer 8 is formed by laminating it on the light emitting layer 5 or the hole blocking layer 6 or the electron transport layer 7 thereon by a wet film formation method or a vacuum deposition method in the same manner as the light emitting layer 5 .
The details of the wet film formation method are the same as those of the light-emitting layer 5 described above.

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

From the viewpoint of element stability, it is preferable to protect the cathode 9 made of a metal having a low work function by laminating a metal layer having a high work function and stable against the atmosphere on the cathode 9. Examples of the metal to be laminated include aluminum, silver, copper, nickel, chromium, gold, platinum, and the like.
The thickness of the cathode is usually the same as that of the anode 2 .

<Other constituent layers>
The above has mainly been described with reference to the element having the layer structure shown in FIG. 1 . However, in the organic electroluminescent element of the present invention, any layer may be present between the anode 2 and the cathode 9 and the light-emitting layer 5 in addition to the layers described above, as long as the performance is not impaired. Furthermore, any layer other than the light-emitting layer 5 may be omitted.

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

The properties required for the electron blocking layer include high hole transporting ability, a large energy gap (difference between HOMO and LUMO), and a high excited triplet level (T1).
When the light-emitting layer 5 is formed by a wet film-forming method, it is preferable to also form the electron blocking layer by a wet film-forming method, since this makes it easier to manufacture the element.
For this reason, it is preferable that the electron blocking layer also has compatibility with wet film formation, and examples of materials used for such electron blocking layers include copolymers of dioctylfluorene and triphenylamine, such as F8-TFB (WO 2004/084260).

It is also possible to have a structure opposite to that shown in FIG. 1 , that is, to laminate the cathode 9, the electron injection layer 8, the electron transport layer 7, the hole blocking layer 6, the light-emitting layer 5, the hole transport layer 4, the hole injection layer 3, and the anode 2 in this order on the substrate 1, and it is also possible to provide the organic electroluminescent device of the present invention between two substrates, at least one of which is highly transparent.
Furthermore, it is possible to form a structure in which the layer configuration shown in Fig. 1 is stacked in multiple stages (a structure in which multiple light-emitting units are stacked). In this case, it is preferable from the viewpoints of luminous efficiency and driving voltage to use, for example, _V2O5 or the like as a charge generating layer instead of the interface layer between stages (between light-emitting units) (when the anode is ITO and the _cathode is Al, the two layers are used), since the barrier between the stages is reduced.
The present invention can be applied to any organic electroluminescent device, whether it is a single device, a device having a structure in which the devices are arranged in an array, or a structure in which the anodes and cathodes are arranged in an XY matrix.

[Display device and lighting device]
The organic electroluminescent device of the present invention as described above can be used to manufacture a display device and a lighting device. The type and structure of the display device and lighting device using the organic electroluminescent device of the present invention are not particularly limited, and they can be assembled according to a conventional method using the organic electroluminescent device of the present invention.
For example, a display device and a lighting device can be formed by a method such as that described in "Organic EL Display" (Ohmsha, published on August 20, 2004, by Tokito Shizuo, Adachi Chihaya, and Murata Hideyuki).

The present invention will be explained in more detail below with reference to examples. However, the present invention is not limited to the following examples, and the present invention can be modified as desired without departing from the gist of the invention.

In the following synthesis examples, all reactions were carried out under a nitrogen stream. Solvents and solutions used in the reactions were degassed using an appropriate method such as nitrogen bubbling.

[Synthesis of Iridium Complex Compounds]
Synthesis Example 1: Synthesis of compound (D-1)

2-Bromo-7-iodofluorene (46.30 g), 3-(6-phenyl-n-hexyl)phenylboronic acid (35.50 g), tetrakis(triphenylphosphine)palladium(0) (5.40 g), 2M tripotassium phosphate aqueous solution (150 mL), toluene (300 mL) and ethanol (100 mL) were placed in a 1 L eggplant flask and stirred under reflux for 3 hours. After cooling to room temperature, the aqueous phase was removed and the solvent was removed under reduced pressure. The residue was purified by silica gel column chromatography (dichloromethane/hexane = 15/85 to 2/8), yielding 51.34 g of 2-bromo-7-{3-(6-phenyl-n-hexyl)}phenylfluorene as a white solid.

2-Bromo-7-{3-(6-phenyl-n-hexyl)}phenylfluorene (23.70 g) and tetrahydrofuran (200 mL) were placed in a 500 mL eggplant flask, and potassium tert-butoxide (16.65 g) was added to the solution little by little. The solution turned deep orange. After immersing the flask in an ice-water bath, methyl iodide (9.2 mL) was added dropwise over 8 minutes using a syringe, and the reaction solution turned into an ochre-colored slurry. After stirring for 2 hours, water (70 mL) was added and the mixture was concentrated under reduced pressure. The resulting residue was extracted with water (80 mL), 1N hydrochloric acid (10 mL), saturated saline (50 mL), and dichloromethane (400 mL), and the oil phase was dried over sodium sulfate, filtered, and then concentrated under reduced pressure. The resulting residue was purified by silica gel chromatography (dichloromethane/hexane = 1/9 to 4/6), yielding 22.50 g of 2-bromo-9,9-dimethyl-7-{3-(6-phenyl-n-hexyl)}phenylfluorene as a pale yellow oil.

2-Bromo-7-{3-(6-phenyl-n-hexyl)}phenylfluorene (22.50 g), bispinacolatodiboron (12.33 g), potassium acetate (13.05 g), [Pd(dppf) ₂ Cl ₂ ]CH ₂ Cl ₂ (1.08 g) and dimethyl sulfoxide (350 mL) were placed in a 500 mL recovery flask and stirred in an oil bath at 90° C. for 4 hours. After cooling to room temperature, water (0.3 L) and dichloromethane (0.2 L twice and 0.1 L once) were added for liquid separation and extraction. The combined oil phase was dried over magnesium sulfate and then filtered. The solvent was removed from the filtrate under reduced pressure to obtain a residue, which was purified by silica gel column chromatography (ethyl acetate/hexane = 5/95 to 1/1) to obtain intermediate 1 (23.45 g) as a pale yellow oil.

Intermediate 1 (7.91 g), 4-chlorothieno[3,2-c]-pyridine (PharmaBlock, 2.64 g), tetrakis(triphenylphosphine)palladium(0) (0.33 g), 2M aqueous tripotassium phosphate solution (18 mL), and toluene/ethanol = 2/1 (53 mL) were placed in a 1 L recovery flask and stirred under reflux for 6 hours. After cooling to room temperature, the aqueous phase was removed, and the solvent was removed under reduced pressure to obtain a residue, which was purified by silica gel column chromatography (dichloromethane/hexane = 6/4 to 1/0) to obtain 7.39 g of Ligand 1 as a pale yellow oil.

Ligand 1 (4.20 g), iridium (III) chloride n-hydrate (Furuya Metals, 1.29 g), water (6.5 mL), and 2-ethoxyethanol (42 mL) were placed in a 200 mL eggplant flask equipped with a Dimroth tube and immersed in a 125°C oil bath. The temperature of the oil bath was gradually raised to 150°C while the solvent was distilled off and stirred for 7 hours. After cooling to room temperature, 2-ethoxyethanol (20 mL) was added, and the temperature of the oil bath was increased to 155°C and stirred for 8 hours. 2-ethoxyethanol was added in amounts of 20 mL, 20 mL, and 30 mL after 3 hours, 4 hours, and 6 hours, respectively. The amount of liquid distilled up to this point was 121 mL. After cooling to room temperature, the solvent was removed under reduced pressure and the resulting residue was purified by silica gel column chromatography (dichloromethane), yielding 3.27 g of dinuclear complex 1 as an orange solid.

Dinuclear complex 1 (3.88 g), ligand 1 (2.87 g), and diglyme (25 mL) were placed in a 100 mL recovery flask and dissolved by stirring in an oil bath at 150°C. Silver trifluoromethanesulfonate (I) (0.67 g) was then added and stirred for 4.5 hours. After cooling, the solvent was removed under reduced pressure and the resulting residue was purified by silica gel column chromatography (dichloromethane/hexane = 1/1), yielding 1.98 g of compound (D-1) as a reddish-orange solid.

In a 200 mL recovery flask, intermediate 2 (10.77 g), 4-chlorothieno[3,2-c]-pyridine (PharmaBlock, 4.38 g), tetrakis(triphenylphosphine)palladium(0) (0.87 g), tripotassium phosphate (11.00 g), toluene/ethanol=2/1 (75 mL) and water (20 mL) were placed and refluxed with stirring for 8 hours. After cooling to room temperature, the aqueous phase was removed, and the solvent was removed under reduced pressure to obtain a residue, which was purified by silica gel column chromatography (dichloromethane/hexane=1/1 to 7/3) to obtain 10.1 g of ligand 2 as a pale yellow oil.
Intermediate 2 was synthesized by the method described in International Publication No. 2021/161974.

Ligand 2 (5.43 g), iridium (III) chloride n-hydrate (Furuya Metals, 1.78 g), water (8.1 mL), and 2-ethoxyethanol (60 mL) were placed in a 200 mL recovery flask equipped with a Dimroth tube and placed in an aluminum block heater preheated to 100°C, and the temperature was raised to 145°C while stirring. After 2 hours, the temperature was raised to 150°C while distilling off the solvent, and the mixture was stirred for a further 6 hours. After cooling to room temperature, the solvent was removed under reduced pressure, and the resulting residue was used directly in the next reaction.

In a 500 mL recovery flask, all of the residue obtained in the previous reaction was dissolved in dichloromethane (100 mL), sodium carbonate (4.34 g) and acetylacetone (2.62 g) were added, and the mixture was refluxed and stirred for 4 hours. After cooling to room temperature, the mixture was filtered, and the filtrate was purified by silica gel column chromatography (dichloromethane/hexane = 1/1) to obtain 3.64 g of acac complex 2.

Acac complex 2 (3.64 g), ligand 2 (3.58 g), and cyclohexylbenzene (3 mL) were placed in a 100 mL recovery flask, which was then placed on an aluminum block heater and heated to 250°C while stirring. After 1 hour and 20 minutes, silver(I) trifluoromethanesulfonate (0.64 g) was added and the mixture was stirred for another 3.5 hours. After cooling to room temperature, the mixture was dissolved in dichloromethane (50 mL) and purified by silica gel column chromatography (dichloromethane/hexane = 4/6) and reverse phase silica gel column chromatography (octadecylsilyl-modified silica gel, acetonitrile/tetrahydrofuran = 58/42), yielding 0.54 g of compound (D-2) as a red solid.

[Example 1]
An organic electroluminescent device was prepared in the following manner.
A transparent conductive film of indium tin oxide (ITO) was deposited on a glass substrate to a thickness of 50 nm (a sputter-formed film made by Sanyo Vacuum Industrial Co., Ltd.) and patterned into 2 mm-wide stripes using normal photolithography and hydrochloric acid etching to form an anode. The substrate on which the ITO pattern was thus formed was ultrasonically cleaned with a surfactant aqueous solution, washed with ultrapure water, ultrasonically cleaned with ultrapure water, and washed with ultrapure water, in that order, then dried with compressed air, and finally washed with ultraviolet ozone.

As a composition for forming a hole injection layer, a composition was prepared by dissolving 3.0 mass % of a hole transporting polymer compound having a repeating structure represented by the following formula (P-1) and 0.6 mass % of an electron accepting compound represented by the following formula (HI-1) in ethyl benzoate.
This solution was spin-coated on the substrate in the atmosphere and dried for 30 minutes at 240° C. on a hot plate in the atmosphere to form a uniform thin film with a thickness of 40 nm, which was used as a hole injection layer.

Next, 100 parts by mass of a charge transporting polymer compound having a structure represented by the following formula (HT-1) was dissolved in mesitylene to prepare a 2.0% by mass solution.
This solution was spin-coated in a nitrogen glove box onto the substrate on which the hole injection layer had been formed, and dried for 30 minutes at 230° C. on a hot plate in the nitrogen glove box to form a uniform thin film with a thickness of 40 nm, which was used as a hole transport layer.

Next, as materials for the light-emitting layer, 50 parts by mass of a compound represented by the following formula (H-1), 50 parts by mass of a compound represented by the following formula (H-2), 15 parts by mass of a compound serving as a red light-emitting dopant represented by the following formula (RD-1), and 15 parts by mass of the following compound (D-1) serving as an assist dopant were weighed out and dissolved in cyclohexylbenzene to prepare a 6.5% by mass solution as a composition for forming the light-emitting layer.

This composition for forming the light-emitting layer was spin-coated in a nitrogen glove box onto the substrate on which the hole transport layer had been coated, and then dried for 20 minutes at 120°C on a hot plate in the nitrogen glove box to form a uniform thin film with a thickness of 60 nm, which served as the light-emitting layer. The compound represented by formula (RD-1) is a dopant with a maximum emission wavelength of 626 nm, and the compound (D-1) synthesized in Synthesis Example 1 is a dopant with a maximum emission wavelength of 597 nm.

The substrate on which the light-emitting layer had been formed was placed in a vacuum deposition apparatus, and the inside of the apparatus was evacuated until the pressure became 2×10 ⁻⁴ Pa or less.
Next, a compound represented by the following formula (HB-1) and 8-hydroxyquinolinolatolithium were co-deposited on the light-emitting layer at a rate of 1 Å/sec by vacuum deposition so as to have a thickness ratio of 2:3, thereby forming a hole-blocking layer having a thickness of 30 nm.

Next, a 2 mm wide striped shadow mask was attached to the substrate as a mask for cathode deposition so as to be perpendicular to the ITO stripes of the anode, and the mask was placed in another vacuum deposition apparatus. Aluminum was heated in a molybdenum boat to form an aluminum layer with a thickness of 80 nm at a deposition rate of 1 to 8.6 Å/sec, forming a cathode.
In this manner, an organic electroluminescent device having a light-emitting area measuring 2 mm×2 mm was obtained.
When a voltage was applied to the obtained organic electroluminescent device, red light emission originating from the compound represented by formula (RD-1) was observed.

[Comparative Example 1]
An organic electroluminescent device was produced in the same manner as in Example 1, except that a compound represented by the following formula (CD-1) was used instead of compound (D-1), and the composition for forming an emitting layer was such that the mass ratio of the compounds represented by each formula was (H-1):(H-2):(CD-1):(RD-1)=50:50:15:15.
The compound represented by the following formula (CD-1) is a dopant having a maximum emission wavelength of 584 nm.

[Comparative Example 2]
An organic electroluminescent device was produced in the same manner as in Example 1, except that a compound represented by the following formula (CD-2) was used instead of the compound (D-1), and the composition for forming an emitting layer was such that the mass ratio of the compounds represented by each formula was (H-1):(H-2):(CD-2):(RD-1)=50:50:15:15.
The compound represented by the following formula (CD-2) is a dopant having a maximum emission wavelength of 589 nm.

[Element Evaluation]
The obtained organic electroluminescent devices of Example 1 and Comparative Example 1 were measured for current luminous efficiency (cd/A) and external quantum efficiency EQE (%) when emitting light at a luminance of 1000 cd/ ^m2 . The ratio of the current luminous efficiency of Example 1 to the current luminous efficiency of Comparative Example 1, which was set to 1, was calculated and shown in Table 1 below as relative luminous efficiency. In addition, the value of ΔEQE=EQE (Example 1)-EQE (Comparative Example 1), which is obtained by subtracting the EQE of Comparative Example 1 from the EQE of Example 1, is also shown in Table 1 below.
As shown in the results in Table 1, the organic electroluminescent device (Example 1) in which the compound (D-1), which is an iridium complex compound of the present invention, is used as an assist dopant in the light-emitting layer material was found to have a higher current luminous efficiency than the organic electroluminescent devices (Comparative Examples 1 and 2) in which the compounds represented by the formulas (CD-1, CD-2) were used.

[Example 2]
An organic electroluminescent device was produced in the same manner as in Example 1, except that a compound represented by the following formula (RD-2) was used instead of the compound represented by formula (RD-1), and the composition for forming an emitting layer was such that the mass ratio of the compounds represented by each formula was (H-1):(H-2):(D-1):(RD-2)=50:50:30:2.
The compound represented by the following formula (RD-2) is a dopant having a maximum emission wavelength of 619 nm.

[Comparative Example 3]
An organic electroluminescent device was produced in the same manner as in Example 1, except that the compound represented by formula (CD-2) was used instead of the compound represented by formula (D-1), and the composition for forming an emitting layer was such that the mass ratio of the compounds represented by each formula was (H-1):(H-2):(CD-2):(RD-2)=50:50:30:2.

[Element Evaluation]
For the obtained organic electroluminescent devices of Example 2 and Comparative Example 3, the organic electroluminescent devices were driven at a current density of 60 mA/ ^cm2 , and the time LT90 at which the relative luminance reached 90% was measured, and the relative lifetime was recorded when the LT90 of Comparative Example 3 was taken as 100. The results are shown in Table 2 below.
As shown in the results in Table 2, the organic electroluminescent device (Example 2) in which the compound (D-1), which is an iridium complex compound of the present invention, is used as an assist dopant in the light-emitting layer material has a significantly improved driving life compared to the organic electroluminescent device (Comparative Example 3) in which the compound represented by formula (CD-2) is used.

[Measurement of PL quantum yield of solution]
As the luminous efficiency, the PL quantum yield (PLQY) was measured. The PL quantum yield is an index showing the efficiency with which light emission can be obtained from the light (energy) absorbed by a material, and was measured by the following procedure.
The iridium complex compound was dissolved in toluene (Fujifilm Wako Pure Chemical Industries, Ltd., for spectroscopic analysis) at room temperature to prepare a 1×10 ⁻⁵ mol/L solution. This solution was placed in a quartz cell equipped with a Teflon (registered trademark) cock, and nitrogen bubbling was performed for 20 minutes or more. PLQY was then measured at room temperature using the following device. The wavelength showing the maximum value of the phosphorescence spectrum intensity obtained at this time was taken as the maximum emission wavelength.
Apparatus: Hamamatsu Photonics Organic EL Quantum Yield Measurement Apparatus C9920-02
Light source: Monochrome light source L9799-01
Detector: Multichannel detector PMA-11
Excitation light: 380 nm

As the iridium complex compounds, the above compounds (D-1), (D-2), (CD-1), (CD-2), (CD-3) and acac complex 2 were used. Compound (CD-3) is a compound represented by the following formula, and is the same as the compound represented by formula (D-6) described in WO 2023/136252.

When compound (D-1) is compared with compounds (CD-1) and (CD-2) having a similar structure, the PLQY values are almost the same, but the maximum emission wavelength of compound (D-1) is longer. A similar tendency was observed when compound (D-2) is compared with compound (CD-3).
Compounds (D-1) and (D-2) are considered to be more preferable as an assist dopant for red light-emitting materials. Although the acac complex 2 has a slightly longer emission maximum wavelength than the corresponding tris complex (compound (D-2)), the PLQY value was significantly lower. It is known that the larger the PLQY value of the assist dopant, the faster the rate of energy transfer (fluorescence resonance energy transfer), and the higher this rate, the more improved the luminous efficiency of the element will be. Therefore, compound (D-2) is considered to have more preferable properties as an assist dopant than acac complex 2.

The iridium complex compound of the present invention can be suitably used as a material for organic EL devices, particularly as an assist dopant in red organic EL devices. It can also be suitably used as a light-emitting material for yellow-green to orange-emitting organic EL devices.

REFERENCE SIGNS LIST 1 Substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light-emitting layer 6 Hole blocking layer 7 Electron transport layer 8 Electron injection layer 9 Cathode 10 Organic electroluminescent device

Claims (8)

An iridium complex compound represented by the following formula (1):

In the above formula (1), Ir represents an iridium atom.
R ¹ to R ¹⁰ each independently represent a hydrogen atom, a fluorine atom, a cyano group, a linear, branched or cyclic alkyl group having from 1 to 30 carbon atoms, an aromatic hydrocarbon group having from 5 to 60 carbon atoms, an aromatic heterocyclic group having from 5 to 60 carbon atoms, an aralkyl group having from 5 to 60 carbon atoms, or a heteroaralkyl group having from 5 to 60 carbon atoms. These substituents may further have a substituent.
^R11 and ^R12 each independently represent a linear, branched or cyclic alkyl group having from 1 to 30 carbon atoms, an aromatic hydrocarbon group having from 5 to 60 carbon atoms, an aromatic heterocyclic group having from 5 to 60 carbon atoms, an aralkyl group having from 5 to 60 carbon atoms, or a heteroaralkyl group having from 5 to 60 carbon atoms. These substituents may further have a substituent.
Any two adjacent R ² to R ⁵ and any two adjacent R ¹¹ and R ¹² may be bonded to each other while losing a hydrogen atom to form a ring. 2. The iridium complex compound according to claim 1, wherein the substituents ^R1 , ^R2 , ^R6 , ^R7 and ^R10 are hydrogen atoms. 3. The iridium complex compound according to claim 1, wherein the substituent R ¹¹ is a linear, branched or cyclic alkyl group having from 1 to 30 carbon atoms. The iridium complex compound according to claim 1 or 2, wherein any one of the substituents ^R3 and ^R4 is a hydrogen atom. 3. The iridium complex compound according to claim 1, wherein the substituent R ⁸ is a hydrogen atom, a linear or branched alkyl group having from 1 to 30 carbon atoms, or an aromatic hydrocarbon group having from 5 to 60 carbon atoms. An organic electroluminescent device in which the light-emitting layer contains the iridium complex compound according to claim 1 or 2 and a red light-emitting material having a maximum light-emitting wavelength of 600 nm or more. The organic electroluminescent device according to claim 6, wherein the red light emitting material is an iridium complex compound represented by formula (201):

[In the above formula (201), M represents a metal selected from Groups 7 to 11 of the periodic table.
Ring A1 represents an aromatic hydrocarbon ring structure which may have a substituent or an aromatic heterocyclic structure which may have a substituent.
Ring A2 represents an aromatic heterocyclic structure which may have a substituent.
R ²⁰¹ and R ²⁰² are each independently a structure represented by the above formula (202), and "*" represents bonding to ring A1 or ring A2. R ²⁰¹ and R ²⁰² may be the same or different, and when a plurality of R ²⁰¹ and R ²⁰² are present, they may be the same or different.
Ar ²⁰¹ represents a divalent aromatic hydrocarbon ring structure which may have a substituent, or a divalent aromatic heterocyclic structure which may have a substituent. When a plurality of Ar ²⁰¹ are present, they may be the same or different.
Ar ²⁰² represents a divalent aromatic hydrocarbon ring structure which may have a substituent, a divalent aromatic heterocyclic structure which may have a substituent, or a divalent aliphatic hydrocarbon structure which may have a substituent. When a plurality of Ar ²⁰² are present, they may be the same or different.
Ar ²⁰³ represents a monovalent aromatic hydrocarbon ring structure which may have a substituent, or a monovalent aromatic heterocyclic ring structure which may have a substituent. When there are a plurality of Ar ²⁰³ , they may be the same or different.
The substituents bonded to ring A1 may be bonded to each other, the substituents bonded to ring A2 may be bonded to each other, or the substituents bonded to ring A1 and the substituents bonded to ring A2 may be bonded to each other to form a ring.
B ²⁰¹ -L ²⁰⁰ -B ²⁰² represents an anionic bidentate ligand. B ²⁰¹ and B ²⁰² each independently represent a carbon atom, an oxygen atom, or a nitrogen atom, and these atoms may be atoms constituting a ring. L ²⁰⁰ represents a single bond, or an atomic group constituting a bidentate ligand together with B ²⁰¹ and B ^202. When a plurality of B ²⁰¹ -L ²⁰⁰ -B ²⁰² are present, they may be the same or different.
i1 and i2 each independently represent an integer of 0 to 12.
i3 is an integer of 0 or more, the upper limit of which is the number that can be substituted for Ar ²⁰² .
j is an integer of 0 or more, the upper limit of which is the number that can be substituted on Ar ²⁰¹ .
k1 and k2 each independently represent an integer of 0 or more, which is the upper limit of the number that can be substituted on ring A1 and ring A2.
m is an integer from 1 to 3. An ink for forming a light-emitting layer of a coating-type organic electroluminescent device, comprising the iridium complex compound according to claim 1 or 2, a red light-emitting material having a maximum light-emitting wavelength of 600 nm or more, and an organic solvent.

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