JP7646364B2 - Composition containing an iridium complex, organic light-emitting element having the same, display device, imaging device, electronic device, lighting device, and mobile object - Google Patents

Description

The present invention relates to a composition containing an iridium complex with reduced isomers, and an organic light-emitting device, a display device, an imaging device, an electronic device, a lighting device, and a mobile object that contain the composition.

An organic light-emitting element (also called an organic electroluminescent element or organic light-emitting element) is an electronic element having a first electrode, a second electrode, and an organic compound layer disposed between these electrodes. By injecting electrons and holes from this pair of electrodes, excitons of the light-emitting organic compound in the organic compound layer are generated, and when the excitons return to the ground state, the organic light-emitting element emits light.

Recent advances in organic light-emitting devices have been remarkable, including low driving voltages, diverse emission wavelengths, fast response, and the ability to make light-emitting devices thinner and lighter.

To improve the performance of light-emitting devices, there is a demand for the development of even higher-performance light-emitting organic compounds, and this development is being actively pursued. Light-emitting organic compounds are divided into two types: fluorescent materials and phosphorescent materials, and it is known that, in principle, phosphorescent materials have higher luminous efficiency than fluorescent materials.

Patent document 1 describes the following compound A as a phosphorescent material with high luminous efficiency.

JP 2009-114137 A

Patent Document 1 describes compound A and a method for synthesizing the same. Although an organic light-emitting element having compound A is described as a highly efficient and long-life element, there is room for improvement in the element life of organic light-emitting elements having compound A. When compound A is synthesized using the synthesis method described in Patent Document 1, it contains about 1.4% of an isomer of compound A. The inclusion of this isomer may result in a shorter element life of the organic light-emitting element than when the isomer is not contained, and it is therefore desirable to reduce this isomer.

The present invention has been made in consideration of the above problems, and its object is to provide an iridium complex and a composition containing the iridium complex, in which the isomers of the iridium complex are reduced.

One embodiment of the present invention relates to an iridium complex having an iridium atom, a first ligand, a second ligand, and a third ligand bonded to the iridium atom, the second ligand having the same structure as the first ligand, and the third ligand having a structure different from the first ligand and the second ligand, and an iridium complex having an iridium atom, a fourth ligand, a fifth ligand, and the third ligand, and an isomer of the iridium complex, wherein a fourth ligand is a ligand represented by the same rational formula as the first ligand, and the fifth ligand is a ligand represented by the same rational formula as the second ligand, wherein the iridium complex is represented by general formula [1] or general formula [2] described below, and the composition ratio of the isomer to the total of the iridium complex and the isomer is 1.0% or less.

The present invention provides a composition that contains an iridium complex and has a reduced amount of isomers of the iridium complex.

1A is a schematic cross-sectional view showing an example of a pixel of a display device according to an embodiment of the present invention, and FIG. 1B is a schematic cross-sectional view showing an example of a display device using an organic light-emitting element according to an embodiment of the present invention. 1 is a schematic diagram of an example of a display device using an organic light-emitting element according to one embodiment of the present invention. 1A is a schematic diagram illustrating an example of an imaging device according to an embodiment of the present invention, and FIG. 1B is a schematic diagram illustrating an example of a portable device according to an embodiment of the present invention. 1A is a schematic diagram illustrating an example of a display device according to an embodiment of the present invention, and FIG. 1B is a schematic diagram illustrating an example of a foldable display device. 1A is a schematic diagram showing an example of an illumination device according to an embodiment of the present invention, and FIG. 1B is a schematic diagram showing an automobile as an example of a moving body according to an embodiment of the present invention.

The following describes an embodiment of the present invention. The present invention is not limited to the following description, and it will be readily understood by those skilled in the art that various changes can be made in form and details without departing from the spirit and scope of the present invention. In other words, the present invention is not to be interpreted as being limited by the following description.

A composition according to one embodiment of the present invention includes an iridium atom, an iridium complex having a first ligand, a second ligand, and a third ligand bonded to the iridium atom, the second ligand having the same structure as the first ligand, and the third ligand having a structure different from the first ligand and the second ligand, and an isomer of the iridium complex having an iridium atom, a fourth ligand, a fifth ligand, and the third ligand, the fourth ligand being represented by the same rational formula as the first ligand, and the fifth ligand being represented by the same rational formula as the second ligand, characterized in that the composition ratio of the isomer to the total of the iridium complex and the isomer is 1.0% or less. More preferably, the composition ratio of the isomer is 0.6% or less. Even more preferably, the composition ratio of the isomer is 0.2% or less.

An iridium complex according to one embodiment of the present invention has an iridium atom, a first ligand, a second ligand, and a third ligand. The first to third ligands are bonded to the iridium atom. The bond may be called a covalent bond or a coordinate bond. The first and second ligands have the same structure, and the third ligand has a different structure from the first and second ligands.

The isomer of the iridium complex according to one embodiment of the present invention is a complex having a fourth ligand, a fifth ligand, and a third ligand. The fourth ligand is represented by the same rational formula as the first ligand, and the fifth ligand is represented by the same rational formula as the second ligand. The first and fourth ligands, and the second and fifth ligands have the same rational formula, so that only the substitution position of the substituent and the configuration with respect to Ir may differ. The properties of the ligands do not differ greatly, but there may be a difference in the performance of the iridium complex as a whole. In other words, it has been found that an organic light-emitting device with excellent device life can be constructed by reducing the isomer of the iridium complex as an impurity. The composition according to one embodiment of the present invention is a composition that has a long device life when made into an organic light-emitting device by reducing the isomer from the composition.

[Composition ratio]
In this specification, the composition ratio of an isomer represents the ratio of the isomer to the total of an iridium complex and an isomer of the iridium complex. The composition ratio can be measured, for example, by high performance liquid chromatography (HPLC). More specifically, a spectrum is obtained with the horizontal axis representing the absorption wavelength and the vertical axis representing the absorbance. The excitation wavelength is not particularly limited, but may be 254 nm. The amount of the compound can be estimated from the area defined by this spectrum and the horizontal axis. The composition ratio can then be calculated from the area ratio between the iridium complex and its isomer. The measurement using HPLC is just one example, and the method for measuring the composition ratio of the composition according to the present invention is not limited thereto.

[Isomers]
In this specification, isomers are described. It is known that isomers include structural isomers and stereoisomers.

1. Structural isomers An iridium complex has, for example, an iridium atom, a first ligand having a substituent, a second ligand having the same structure as the first ligand, and a third ligand. The same structure means that the ligands are represented by the same molecular formula and rational formula, and the same substituents are provided at the same substitution positions. A structural isomer has, for example, an iridium atom, a fourth ligand represented by the same rational formula as the first ligand, a fifth ligand represented by the same rational formula as the second ligand, and a third ligand. That is, a structural isomer satisfies at least one of the following (1) and (2).
(1) The first ligand and the fourth ligand have different structures.
(2) The second ligand and the fifth ligand have different structures.

The first and second ligands may have a structure having a substituent, and the fourth or fifth ligand may have a structure in which the substitution position of the substituent is different from that of the first or second ligand. The structural isomer may have a structure that satisfies both (1) and (2).

More specifically, the structural isomer has an iridium atom, a fourth ligand having the same structure as the first ligand, a fifth ligand having a substituent at a different position from the second ligand, and a third ligand. Or, the structural isomer has an iridium atom, a fourth ligand having a substituent at a different position from the first ligand, a fifth ligand having a substituent at a different position from the second ligand, and a third ligand. Here, the first ligand and the fourth ligand have the same rational formula, so the performance of the ligand itself does not differ greatly. However, the performance of the iridium complex may differ greatly if the ligand is a structural isomer. The same is true for the second ligand and the fifth ligand.

Iridium complexes and structural isomers of said iridium complexes have the following structural formulas, for example:

2. Stereoisomers On the other hand, stereoisomers are known as optical isomers and geometric isomers. An iridium complex has, for example, an iridium atom, a first ligand, a second ligand having the same structure as the first ligand, and a third ligand having a structure different from the first and second ligands. A stereoisomer has an iridium atom, a fourth ligand having the same structure as the first ligand, a fifth ligand having the same structure as the second ligand, and a third ligand. The fourth ligand and the fifth ligand have a fourth ligand and a fifth ligand having different stereoconfigurations with respect to the iridium atom. That is, a stereoisomer satisfies at least one of (3) and (4).
(3) The first ligand and the fourth ligand have different steric configurations with respect to the iridium atom.
(4) The second ligand and the fifth ligand have different steric configurations with respect to the iridium atom.

The stereoisomer may have a structure that satisfies both (3) and (4).

Specifically, the stereoisomer is an iridium complex having an iridium atom and a first ligand, a second ligand, and a third ligand. The stereoisomer has an iridium atom, a fourth ligand, a fifth ligand, and a third ligand. The first ligand, the second ligand, the fourth ligand, and the fifth ligand have the same structure. They may have different configurations with respect to iridium from each other. The third ligand has a different structure from the first to fifth ligands. The stereoisomers have the same structure, but may have significantly different performance as an iridium complex.

The iridium complex and the stereoisomer of the iridium complex may have, for example, the following structural formula. Here, the ligands are described in a simplified form. The ligand having a carbon atom and a nitrogen atom may be a ligand having a ring structure, and the ligand having an oxygen atom may be a structure such as an acetylacetone structure. These examples of ligands are merely examples, and do not exclude other structures.

In this embodiment, the iridium complex is of the HNT (Homo-N-Trans) type, and the isomer may be any other stereoisomer.

After extensive research, the inventors discovered that reducing these isomers can improve the element life of an organic light-emitting device that contains the composition.

[Iridium complex]
Next, an iridium complex according to one embodiment of the present invention will be described. The iridium complex according to this embodiment is represented by the following general formula [1] or [2].

In general formula [1] and general formula [2], R ¹ to R ¹⁸ are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a cyano group, a substituted or unsubstituted aromatic hydrocarbon group, and a substituted or unsubstituted heteroaromatic group.

Ring A represents a cyclic structure selected from a benzene ring, a naphthalene ring, a fluorene ring, a phenanthrene ring, a 9,9-spirobifluorene ring, a chrysene ring, and a substituted or unsubstituted heteroaromatic group. The cyclic structure may further have a substituent. L represents a bidentate ligand.

IrL is represented by any of the following general formulas [3] to [5].

In the general formulas [3] to [5], R ¹⁹ to R ³³ are each independently selected from a hydrogen atom, an alkyl group, a substituted or unsubstituted aromatic hydrocarbon group, and a substituted or unsubstituted heteroaromatic group.

The iridium complex according to this embodiment is preferably an iridium complex represented by general formula [6].

In the general formula [6], R ³⁴ to R ⁴⁸ are each independently selected from a hydrogen atom and a substituted or unsubstituted alkyl group. R ⁴² to R ⁴⁵ may be bonded to each other to form a ring structure. Specifically, R ⁴² to R ⁴⁵ may be bonded to form a naphthalene ring, a fluorene ring, a phenanthrene ring, a 9,9-spirobifluorene ring, or a chrysene ring, including a benzene ring having R ⁴² to R ⁴⁵ .

In the iridium complex contained in the composition according to the present embodiment, R ⁴⁵ in the general formula [6] is an alkyl group and R ⁴³ is a hydrogen atom, and in the isomer of the iridium complex contained in the composition, R ⁴⁵ in the general formula [6] may be a hydrogen atom and R ⁴³ may be an alkyl group. The alkyl group represented by R ⁴³ or R ⁴⁵ may be a methyl group.

In the iridium complex contained in the composition according to this embodiment, R ³⁷ in the general formula [6] may be a cyano group.

The halogen atom according to this embodiment is any one of fluorine, chlorine, iodine, and bromine. Of these, fluorine is preferred.

The alkyl group according to the present embodiment may be an alkyl group having 1 to 20 carbon atoms. The alkyl group may have a halogen atom as a substituent. The halogen atom is preferably fluorine. The alkyl group may be an alkyl group having 1 to 8 carbon atoms, or may have 1 to 4 carbon atoms. When a halogen atom is used as a substituent, any hydrogen atom of the alkyl group may be substituted, but a trifluoromethyl group is preferable. More specifically, the alkyl group may be a methyl group, an ethyl group, a normal propyl group, an isopropyl group, a normal butyl group, a tertiary butyl group, a secondary butyl group, an octyl group, a cyclohexyl group, a 1-adamantyl group, a 2-adamantyl group, or the like, but is not limited thereto.

The alkoxy group according to this embodiment may be an alkoxy group having 1 to 20 carbon atoms. The alkoxy group may also be an alkoxy group having 1 to 6 carbon atoms. More specific examples of the alkoxy group include, but are not limited to, a methoxy group, an ethoxy group, a propoxy group, a 2-ethyl-octyloxy group, and a benzyloxy group.

The aromatic hydrocarbon group according to this embodiment may be an aromatic hydrocarbon group having 6 to 18 carbon atoms. More specifically, examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, an indenyl group, a biphenyl group, a terphenyl group, a fluorenyl group, a phenanthryl group, and a triphenylenyl group, but are not limited to these.

The heteroaromatic group according to the present embodiment may be a heteroaromatic group having 3 to 15 carbon atoms. The heteroatom may be a nitrogen atom, an oxygen atom, a sulfur atom, or a combination thereof. More specifically, the heteroaromatic group may be a pyridyl group, a pyrimidyl group, a pyrazyl group, a triazyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an oxazolyl group, an oxadiazolyl group, a thiazolyl group, a thiadiazolyl group, a carbazolyl group, an acridinyl group, a phenanthrolyl group, or the like, but is not limited thereto.

The above alkyl groups, alkoxy groups, aromatic hydrocarbon groups, and heteroaromatic ring groups may further have a substituent. Examples of the substituents that may further be included include alkyl groups having 1 to 4 carbon atoms, such as methyl groups, ethyl groups, normal propyl groups, isopropyl groups, normal butyl groups, and tertiary butyl groups; aralkyl groups, such as benzyl groups; aromatic hydrocarbon groups, such as phenyl groups and biphenyl groups; heterocyclic groups, such as pyridyl groups and pyrrolyl groups; amino groups, such as dimethylamino groups, diethylamino groups, dibenzylamino groups, diphenylamino groups, and ditolylamino groups; alkoxy groups, such as methoxy groups, ethoxy groups, and propoxy groups; aryloxy groups, such as phenoxy groups; halogen atoms, such as fluorine, chlorine, bromine, and iodine; and cyano groups, but are not limited to these.

Specific structural formulas of the iridium complexes of the present invention are shown below.

Among the above exemplary compounds, compounds (1) to (64) and compounds (79) to (94) are iridium complexes having a ligand represented by general formula [5]. These iridium complexes contain one acac-based ligand (diketone-based bidentate ligand) having a small molecular weight. Therefore, the molecular weight of the complex itself is relatively small, and sublimation purification is easy. Furthermore, it is more preferable that R ³¹ to R ³³ in general formula [5] are hydrogen atoms or alkyl groups, and R ³² is a hydrogen atom.

Among the exemplary compounds, compounds (65) to (71) are iridium complexes having a ligand represented by the general formula [4]. These iridium complexes contain one picolinic acid derivative as a ligand in the molecule. When a picolinic acid derivative is introduced as a ligand, the emission peak wavelength of the complex itself can be shifted to a shorter wavelength compared to the case where an acac-based ligand is introduced.

Among the example compounds, compounds (72) to (78) are iridium complexes having a ligand represented by general formula [3]. These iridium complexes contain one phenylpyridine (ppy) derivative in the molecule. Since the ligand ppy is a non-emissive ligand in these iridium complexes, red luminescence derived from the arylbenzo[f]isoquinoline ligand can be obtained from the iridium complex. The presence of the ppy ligand may result in a high quantum yield.

[Method for reducing isomers]
The isomers of the iridium complex according to the present embodiment can be reduced by performing sublimation purification, recrystallization, dispersion washing, GPC purification, and column purification multiple times. The above purification may be performed multiple times for one type, or multiple types may be combined. In addition, when synthesizing the iridium complex, the composition ratio of the isomers can be reduced by extracting the iridium complex by providing a difference between the solubility of the iridium complex and the solubility of its isomer.

[Organic Compound Layer of the Organic Light-Emitting Device According to an Embodiment of the Invention]
Next, the organic compound layer of the organic light-emitting element according to one embodiment of the present invention will be described.

The organic light-emitting device according to this embodiment has at least a pair of electrodes, a first electrode and a second electrode, and an organic compound layer disposed between these electrodes. In the organic light-emitting device according to this embodiment, the organic compound layer may be a single layer or a laminate consisting of multiple layers, so long as it has a light-emitting layer. The pair of electrodes may be an anode and a cathode.

When the organic compound layer is a laminate consisting of multiple layers, the organic compound layer may have a light-emitting layer. In addition to the light-emitting layer, the organic compound layer may have a hole injection layer, a hole transport layer, an electron blocking layer, a hole/exciton blocking layer, an electron transport layer, an electron injection layer, etc. The light-emitting layer may be a single layer or a laminate consisting of multiple layers. The hole transport layer and the electron transport layer are also called charge transport layers.

In the organic light-emitting device of this embodiment, the composition according to this embodiment is contained in at least one of the organic compound layers. Specifically, the composition according to this embodiment is contained in any of the above-mentioned hole injection layer, hole transport layer, electron blocking layer, light-emitting layer, hole/exciton blocking layer, electron transport layer, electron injection layer, etc., and is preferably contained in the light-emitting layer.

In the organic light-emitting device of this embodiment, when the composition according to this embodiment is contained in the light-emitting layer, the light-emitting layer may be a layer consisting of only the composition according to this embodiment, or may be a layer having a first organic compound and a second organic compound different from the first organic compound in addition to the composition according to this embodiment. The first organic compound may have a minimum triplet energy greater than the minimum triplet energy of the iridium complex contained in the composition. The second organic compound may have a minimum triplet energy greater than the minimum triplet energy of the iridium complex contained in the composition and less than the minimum triplet energy of the first organic compound. Here, when the light-emitting layer is a layer having the first organic compound and the second organic compound, the first organic compound may be a host of the light-emitting layer. The second organic compound may be an assist material. The iridium complex contained in the composition may be a guest or a dopant.

The host is the compound that has the largest weight ratio among the compounds that make up the light-emitting layer. The guest or dopant is the compound that has a smaller weight ratio than the host among the compounds that make up the light-emitting layer, and is the compound that is mainly responsible for emitting light. The assist material is the compound that has a smaller weight ratio than the host among the compounds that make up the light-emitting layer, and assists the guest in emitting light. The assist material is also called the second host.

Here, when the iridium complex according to this embodiment is used as a guest in the light-emitting layer, the concentration of the guest is preferably 0.01% by weight to 20% by weight, and more preferably 0.1% by weight to 5.0% by weight, relative to the entire light-emitting layer. The entire light-emitting layer refers to the total weight of the compounds that constitute the light-emitting layer.

The inventors conducted various studies and found that when the iridium complex contained in the composition according to this embodiment is used as a guest in the light-emitting layer, an element that exhibits high efficiency and high luminance light output and is extremely durable can be obtained. This light-emitting layer may be a single layer or multiple layers, and it is also possible to mix the light emitted by the light-emitting layer with the blue light emitted by this embodiment by including a light-emitting material having another light-emitting color. Multiple layers means a state in which the light-emitting layer and another light-emitting layer are laminated. In this case, the light-emitting color of the organic light-emitting element is not limited to blue. More specifically, it may be white or an intermediate color. In the case of white, the other light-emitting layer emits a color other than blue, i.e., red or green. In addition, the film is formed by deposition or coating.

The organic compound according to this embodiment can be used as a constituent material of an organic compound layer other than the light-emitting layer that constitutes the organic light-emitting device of this embodiment. Specifically, it may be used as a constituent material of an electron transport layer, an electron injection layer, a hole transport layer, a hole injection layer, a hole blocking layer, etc. In this case, the emission color of the organic light-emitting device is not limited to blue. More specifically, it may be white or an intermediate color.

When manufacturing the organic light-emitting device according to this embodiment, conventionally known low-molecular-weight and high-molecular-weight hole-injecting or hole-transporting compounds, host compounds, light-emitting compounds, electron-injecting or electron-transporting compounds, etc. can be used together as necessary.

Examples of these compounds are given below:

As the hole injection transport material, a material with high hole mobility is preferred so that it can easily inject holes from the anode and transport the injected holes to the light emitting layer. In addition, a material with a high glass transition temperature is preferred to reduce deterioration of film quality such as crystallization in organic light emitting devices. Examples of low molecular weight and high molecular weight materials with hole injection transport performance include triarylamine derivatives, arylcarbazole derivatives, phenylenediamine derivatives, stilbene derivatives, phthalocyanine derivatives, porphyrin derivatives, poly(vinylcarbazole), poly(thiophene), and other conductive polymers. Furthermore, the above hole injection transport materials are also suitable for use in electron blocking layers.

Specific examples of compounds that can be used as hole injection and transport materials are shown below, but the present invention is not limited to these.

Among the hole transport materials listed above, HT16 to HT18 can reduce the driving voltage when used in a layer in contact with the anode. HT16 is widely used in organic light-emitting elements. HT2, HT3, HT10, and HT12 may be used in the organic compound layer adjacent to HT16. Also, multiple materials may be used in one organic compound layer. For example, combinations of HT2 and HT4, HT3 and HT10, and HT8 and HT9 may be used.

Light-emitting materials mainly involved in the light-emitting function include, in addition to the iridium complex according to one embodiment of the present invention, condensed ring compounds (e.g., fluorene derivatives, naphthalene derivatives, pyrene derivatives, perylene derivatives, tetracene derivatives, anthracene derivatives, rubrene, etc.), quinacridone derivatives, coumarin derivatives, stilbene derivatives, organoaluminum complexes such as tris(8-quinolinolato)aluminum, iridium complexes, platinum complexes, rhenium complexes, copper complexes, europium complexes, ruthenium complexes, and polymer derivatives such as poly(phenylenevinylene) derivatives, poly(fluorene) derivatives, and poly(phenylene) derivatives.

Specific examples of compounds that can be used as luminescent materials are shown below, but of course they are not limited to these.

Examples of the light-emitting layer host or light-emitting assist material contained in the light-emitting layer include aromatic hydrocarbon compounds or their derivatives, as well as carbazole derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, organic aluminum complexes such as tris(8-quinolinolato)aluminum, and organic beryllium complexes.

It is particularly preferable that the host material has an anthracene, tetracene, perylene, fluorene, or pyrene skeleton in the molecular skeleton. This is because, in addition to being composed of hydrocarbons as described above, they have S1 energy that can cause sufficient energy transfer to the organic compound of the present invention.

As the aromatic hydrocarbon compound host material, a compound represented by the following general formula [7] is preferable.
Ar1-(Ar2)p-(Ar3)q-Ar1 General formula [7]

In the general formula [7], p and q each represent 0 or 1, and p+q represents 1 or more.
Ar1 is any one of the substituents shown in the following substituent group α.
Ar2 and Ar3 each represent any one of the substituents shown in the following Substituent Group β. Ar2 and Ar3 may be the same or different.

Specific examples of compounds that can be used as the light-emitting layer host or light-emitting assist material contained in the light-emitting layer are shown below, but the present invention is not limited to these.

The electron transport material can be arbitrarily selected from those capable of transporting electrons injected from the cathode to the light-emitting layer, and is selected in consideration of the balance with the hole mobility of the hole transport material. Materials having electron transport properties include oxadiazole derivatives, oxazole derivatives, pyrazine derivatives, triazole derivatives, triazine derivatives, quinoline derivatives, quinoxaline derivatives, phenanthroline derivatives, organic aluminum complexes, and condensed ring compounds (e.g., fluorene derivatives, naphthalene derivatives, chrysene derivatives, anthracene derivatives, etc.). Furthermore, the above electron transport materials are also suitable for use in hole blocking layers.

Specific examples of compounds that can be used as electron transport materials are shown below, but of course the materials are not limited to these.

The electron injection material can be selected from those that allow easy injection of electrons from the cathode, taking into consideration the balance with hole injection properties. Organic compounds include n-type dopants and reducing dopants. Examples include compounds containing alkali metals such as lithium fluoride, lithium complexes such as lithium quinolinol, benzimidazolidene derivatives, imidazolidene derivatives, fulvalene derivatives, and acridine derivatives.

[Configuration of organic light-emitting element]
The organic light-emitting element is provided by forming a first electrode, an organic compound layer, and a second electrode on an insulating layer provided on a substrate. A protective layer, a color filter, etc. may be provided on the second electrode. When a color filter is provided, a planarizing layer may be provided between the protective layer and the color filter. The planarizing layer may be made of acrylic resin, etc. One of the first electrode and the second electrode may be an anode, and the other may be a cathode.

[substrate]
Examples of the substrate include quartz, glass, silicon wafer, resin, and metal. In addition, a switching element such as a transistor and wiring may be provided on the substrate, and an insulating layer may be provided thereon. As the insulating layer, any material can be used as long as it is possible to form a contact hole to ensure electrical continuity between the anode 2 and the wiring, and to ensure insulation from wiring that is not connected. For example, resin such as polyimide, silicon oxide, silicon nitride, etc. can be used.

[electrode]
A pair of electrodes can be used. The pair of electrodes may be an anode and a cathode. When an electric field is applied in the direction in which the organic light-emitting element emits light, the electrode with a higher potential is the anode, and the other is the cathode. It can also be said that the electrode that supplies holes to the light-emitting layer is the anode, and the electrode that supplies electrons is the cathode.

The material that constitutes the anode should have as large a work function as possible. For example, metals such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, tungsten, etc., mixtures containing these metals, alloys combining these metals, metal oxides such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide can be used. Conductive polymers such as polyaniline, polypyrrole, and polythiophene can also be used.

One of these electrode materials may be used alone, or two or more may be used in combination. The anode may be composed of a single layer or multiple layers.

When used as a reflective electrode, for example, chromium, aluminum, silver, titanium, tungsten, molybdenum, or alloys or laminates of these can be used. When used as a transparent electrode, a transparent conductive layer of oxide such as indium tin oxide (ITO) or indium zinc oxide can be used, but is not limited to these. Photolithography technology can be used to form the electrode.

On the other hand, the material for the cathode should have a small work function. Examples of such materials include alkali metals such as lithium, alkaline earth metals such as calcium, aluminum, titanium, manganese, silver, lead, and chromium, or mixtures containing these metals. Alternatively, alloys combining these metal elements can be used. For example, magnesium-silver, aluminum-lithium, aluminum-magnesium, silver-copper, and zinc-silver can be used. Metal oxides such as indium tin oxide (ITO) can also be used. These electrode materials may be used alone or in combination of two or more types. The cathode may have a single layer or a multilayer structure. Among these, silver is preferably used, and a silver alloy is even more preferable in order to suppress the aggregation of silver. As long as the aggregation of silver can be suppressed, the alloy ratio is not important. For example, it may be 1:1.

The cathode may be a top-emission element using an oxide conductive layer such as ITO, or a bottom-emission element using a reflective electrode such as aluminum (Al), and is not particularly limited. The method for forming the cathode is not particularly limited, but DC and AC sputtering methods are more preferable because they provide good film coverage and make it easier to reduce resistance.

[Protective Layer]
A protective layer may be provided on the cathode. For example, by bonding glass provided with a moisture absorbent on the cathode, the intrusion of water or the like into the organic compound layer can be reduced, and the occurrence of display defects can be reduced. In another embodiment, a passivation film such as silicon nitride may be provided on the cathode to reduce the intrusion of water or the like into the organic EL layer. For example, after forming the cathode, the cathode may be transported to another chamber without breaking the vacuum, and a silicon nitride film having a thickness of 2 μm may be formed by the CVD method to serve as a protective layer. A protective layer may be provided using the atomic layer deposition method (ALD method) after the film formation by the CVD method.

[Color filter]
A color filter may be provided on the protective layer. For example, a color filter taking into consideration the size of the organic light-emitting element may be provided on another substrate and then bonded to the substrate on which the organic light-emitting element is provided, or a color filter may be patterned on the protective layer described above using a photolithography technique. The color filter may be made of a polymer.

[Planarization layer]
A planarizing layer may be provided between the color filter and the protective layer. The planarizing layer may be made of an organic compound, and may be a low molecular weight or a high molecular weight compound, but is preferably a high molecular weight compound.

The planarization layer may be provided above and below the color filter, and may be made of the same or different materials. Specific examples include polyvinylcarbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenolic resin, epoxy resin, silicone resin, and urea resin.

[Counter substrate]
A counter substrate may be provided on the planarization layer. The counter substrate is called a counter substrate because it is provided at a position corresponding to the aforementioned substrate. The material of the counter substrate may be the same as that of the aforementioned substrate. When the aforementioned substrate is a first substrate, the counter substrate may be a second substrate.

[Formation of Organic Compound Layer]
The organic compound layers (such as a hole injection layer, a hole transport layer, an electron blocking layer, a light emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer) constituting the organic light emitting device according to one embodiment of the present invention are formed by the method described below.

The organic compound layer constituting the organic light-emitting device according to one embodiment of the present invention can be formed using a dry process such as vacuum deposition, ionization deposition, sputtering, plasma, etc. Alternatively to the dry process, a wet process can be used in which the compound is dissolved in an appropriate solvent and a layer is formed using a known coating method (e.g., spin coating, dipping, casting, LB method, inkjet method, etc.).

Here, if a layer is formed by a vacuum deposition method or a solution coating method, crystallization is unlikely to occur and the layer has excellent stability over time. In addition, when forming a film by a coating method, a film can be formed by combining with an appropriate binder resin.

Examples of the binder resin include, but are not limited to, polyvinylcarbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenol resin, epoxy resin, silicone resin, urea resin, etc.

These binder resins may be used alone as homopolymers or copolymers, or two or more types may be mixed together. If necessary, known additives such as plasticizers, antioxidants, and ultraviolet absorbers may be used in combination.

[Use of the organic light-emitting device according to one embodiment of the present invention]
The organic light-emitting device according to an embodiment of the present invention can be used as a component of a display device or a lighting device, and can also be used as an exposure light source for an electrophotographic image forming device, a backlight for a liquid crystal display device, a light-emitting device having a white light source and a color filter, etc.

The display device may be an image information processing device that has an image input unit that inputs image information from an area CCD, a linear CCD, a memory card, etc., has an information processing unit that processes the input information, and displays the input image on the display unit.

The display unit of the imaging device or inkjet printer may have a touch panel function. The driving method of this touch panel function may be an infrared method, a capacitive method, a resistive film method, or an electromagnetic induction method, and is not particularly limited. The display device may also be used in the display unit of a multifunction printer.

Next, the display device according to this embodiment will be described with reference to the drawings.

Figure 1(a) is a schematic cross-sectional view of an example of a pixel constituting a display device according to this embodiment. The pixel has a sub-pixel 10. The sub-pixels are divided into 10R, 10G, and 10B according to their light emission. The emitted color may be distinguished by the wavelength emitted from the light-emitting layer, or the light emitted from the sub-pixel may be selectively transmitted or color-converted by a color filter or the like. Each sub-pixel has a reflective electrode 2 as a first electrode on an interlayer insulating layer 1, an insulating layer 3 covering the edge of the reflective electrode 2, an organic compound layer 4 covering the first electrode and the insulating layer, a transparent electrode 5, a protective layer 6, and a color filter 7.

The interlayer insulating layer 1 may have a transistor and a capacitance element disposed underneath or inside it. The transistor and the first electrode may be electrically connected via a contact hole or the like (not shown).

The insulating layer 3 is also called a bank or pixel separation film. It covers the edge of the first electrode and is disposed so as to surround the first electrode. The part where the insulating layer is not disposed contacts the organic compound layer 4 and becomes the light-emitting region.

The organic compound layer 4 has a hole injection layer 41, a hole transport layer 42, a first light-emitting layer 43, a second light-emitting layer 44, and an electron transport layer 45.

The second electrode 5 may be a transparent electrode, a reflective electrode, or a semi-transparent electrode.

The protective layer 6 reduces the penetration of moisture into the organic compound layer. Although the protective layer is illustrated as being a single layer, it may be multiple layers. Each layer may include an inorganic compound layer and an organic compound layer.

The color filters 7 are divided into 7R, 7G, and 7B according to their colors. The color filters may be formed on a planarization film (not shown). Also, a resin protective layer (not shown) may be provided on the color filters. Also, the color filters may be formed on a protective layer 6. Alternatively, they may be provided on an opposing substrate such as a glass substrate and then bonded together.

Figure 1(b) is a cross-sectional schematic diagram showing an example of a display device having an organic light-emitting element and a transistor connected to the organic light-emitting element. The transistor is an example of an active element. The transistor may be a thin-film transistor (TFT).

The display device 100 in FIG. 1(b) has a substrate 11 made of glass, silicon, or the like, and an insulating layer 12 on top of it. An active element 18 such as a TFT is arranged on the insulating layer, along with a gate electrode 13, a gate insulating film 14, and a semiconductor layer 15 of the active element. The TFT 18 also comprises a semiconductor layer 15, a drain electrode 16, and a source electrode 17. An insulating film 19 is provided on top of the TFT 18. An anode 21 constituting the organic light-emitting element and the source electrode 17 are connected via a contact hole 20 provided in the insulating film.

The method of electrical connection between the electrodes (anode, cathode) included in the organic light-emitting element and the electrodes (source electrode, drain electrode) included in the TFT is not limited to the embodiment shown in FIG. 1(b). In other words, it is sufficient that either the anode or the cathode is electrically connected to either the TFT source electrode or the drain electrode. TFT stands for thin film transistor.

In the display device 100 of FIG. 1(b), the organic compound layer is illustrated as one layer, but the organic compound layer 22 may be multiple layers. A first protective layer 24 and a second protective layer 25 are provided on the cathode 23 to reduce deterioration of the organic light-emitting element.

In the display device 100 of FIG. 1(b), a transistor is used as the switching element, but other switching elements may be used instead.

The transistors used in the display device 100 of FIG. 2(b) are not limited to transistors using single crystal silicon wafers, but may be thin film transistors having an active layer on the insulating surface of a substrate. Examples of active layers include single crystal silicon, amorphous silicon, non-single crystal silicon such as microcrystalline silicon, and non-single crystal oxide semiconductors such as indium zinc oxide and indium gallium zinc oxide. Thin film transistors are also called TFT elements.

The transistors included in the display device 100 of FIG. 1(b) may be formed within a substrate such as a Si substrate. Formed within a substrate here means that the substrate itself, such as a Si substrate, is processed to produce the transistors. In other words, having a transistor within a substrate can be seen as the substrate and the transistor being formed integrally.

The organic light-emitting element according to this embodiment has its emission brightness controlled by a TFT, which is an example of a switching element, and by providing the organic light-emitting element on multiple surfaces, an image can be displayed with the emission brightness of each element. The switching element according to this embodiment is not limited to a TFT, and may be a transistor formed from low-temperature polysilicon, or an active matrix driver formed on a substrate such as a Si substrate. On the substrate can also be within the substrate. Whether to provide a transistor within the substrate or to use a TFT is selected according to the size of the display unit; for example, if the size is about 0.5 inches, it is preferable to provide the organic light-emitting element on a Si substrate.

Figure 2 is a schematic diagram showing an example of a display device according to this embodiment. The display device 1000 may have a touch panel 1003, a display panel 1005, a frame 1006, a circuit board 1007, and a battery 1008 between an upper cover 1001 and a lower cover 1009. The touch panel 1003 and the display panel 1005 are connected to flexible printed circuits FPCs 1002 and 1004. Transistors are printed on the circuit board 1007. The battery 1008 may not be provided if the display device is not a portable device, and may be provided in a different position even if the display device is a portable device.

The display device according to this embodiment may have a color filter having red, green, and blue colors. The color filters may be arranged such that the red, green, and blue colors are arranged in a delta arrangement.

The display device according to this embodiment may be used as a display unit of a mobile terminal. In this case, it may have both a display function and an operation function. Examples of the mobile terminal include mobile phones such as smartphones, tablets, and head-mounted displays.

The display device according to this embodiment may be used in the display section of an imaging device having an optical section with multiple lenses and an imaging element that receives light that has passed through the optical section. The imaging device may have a display section that displays information acquired by the imaging element. The display section may be a display section exposed to the outside of the imaging device, or a display section disposed within the viewfinder. The imaging device may be a digital camera or a digital video camera. The imaging device may also be called a photoelectric conversion device.

FIG. 3(a) is a schematic diagram showing an example of an imaging device according to this embodiment. The imaging device 1100 may have a viewfinder 1101, a rear display 1102, an operation unit 1103, and a housing 1104. The viewfinder 1101 may have a display device according to this embodiment. In this case, the display device may display not only the image to be captured, but also environmental information, imaging instructions, etc. The environmental information may include the intensity of external light, the direction of external light, the speed at which the subject moves, the possibility that the subject will be blocked by an obstruction, etc.

The optimal timing for capturing an image is very short, so it is better to display information as soon as possible. Therefore, it is preferable to use a display device using the organic light-emitting element of the present invention. This is because organic light-emitting elements have a fast response speed. A display device using organic light-emitting elements can be used more preferably than liquid crystal display devices, which require high display speed.

The imaging device 1100 has an optical section (not shown). The optical section has multiple lenses, and forms an image on an imaging element housed in a housing 1104. The focus of the multiple lenses can be adjusted by adjusting their relative positions. This operation can also be performed automatically.

FIG. 3B is a schematic diagram showing an example of an electronic device according to this embodiment. The electronic device 1200 has a display unit 1201, an operation unit 1202, and a housing 1203. The housing 1203 may have a circuit, a printed circuit board having the circuit, a battery, and a communication unit. The operation unit 1202 may be a button or a touch panel type reaction unit. The operation unit may be a biometric recognition unit that recognizes a fingerprint and performs unlocking, etc. An electronic device having a communication unit can also be called a communication device. The electronic device may further have a camera function by including a lens and an image sensor. An image captured by the camera function is displayed on the display unit. Examples of the electronic device include a smartphone and a laptop computer.

Figure 4 is a schematic diagram showing an example of a display device according to this embodiment. Figure 4(a) shows a display device such as a television monitor or a PC monitor. The display device 1300 has a frame 1301 and a display unit 1302. The light-emitting device according to this embodiment may be used for the display unit 1302.

It has a frame 1301 and a base 1303 that supports a display unit 1302. The base 1303 is not limited to the form shown in FIG. 4(a). The bottom side of the frame 1301 may also serve as the base.

Furthermore, the frame 1301 and the display unit 1302 may be curved. The radius of curvature may be 5000 mm or more and 6000 mm or less.

Figure 4(b) is a schematic diagram showing another example of the display device according to this embodiment. The display device 1310 in Figure 4(b) is configured to be bendable, and is a so-called foldable display device. The display device 1310 has a first display unit 1311, a second display unit 1312, a housing 1313, and a bending point 1314. The first display unit 1311 and the second display unit 1312 may have a light-emitting device according to this embodiment. The first display unit 1311 and the second display unit 1312 may be a single display unit without a joint. The first display unit 1311 and the second display unit 1312 can be separated by the bending point. The first display unit 1311 and the second display unit 1312 may each display different images, or the first and second display units may display a single image.

Figure 5 (a) is a schematic diagram showing an example of a lighting device according to this embodiment. The lighting device 1400 may have a housing 1401, a light source 1402, a circuit board 1403, an optical film 1404, and a light diffusion section 1405. The light source may have an organic light-emitting element according to this embodiment. The optical filter may be a filter that improves the color rendering of the light source. The light diffusion section can effectively diffuse the light of the light source, such as for lighting up, and deliver the light over a wide range. The optical filter and the light diffusion section may be provided on the light emission side of the lighting. If necessary, a cover may be provided on the outermost part.

The lighting device is, for example, a device that illuminates a room. The lighting device may emit white light, daylight white light, or any other color from blue to red. It may have a dimming circuit that adjusts the light intensity. The lighting device may have the organic light-emitting element of the present invention and a power supply circuit connected thereto. The power supply circuit is a circuit that converts AC voltage into DC voltage. Furthermore, white has a color temperature of 4200K, and daylight white has a color temperature of 5000K. The lighting device may have a color filter.

The lighting device according to this embodiment may also have a heat dissipation section. The heat dissipation section dissipates heat from within the device to the outside, and examples of the heat dissipation section include metals with high specific heat, liquid silicon, etc.

Figure 5(b) is a schematic diagram of an automobile, which is an example of a moving body according to this embodiment. The automobile has tail lamps, which are an example of a lamp. The automobile 1500 has tail lamps 1501, and may be configured to turn on the tail lamps when braking or the like is performed.

The tail lamp 1501 may have an organic light-emitting element according to this embodiment. The tail lamp may have a protective member that protects the organic EL element. The protective member may be made of any material as long as it has a relatively high strength and is transparent, but it is preferable that the protective member is made of polycarbonate or the like. Polycarbonate may be mixed with a furandicarboxylic acid derivative, an acrylonitrile derivative, or the like.

The automobile 1500 may have a body 1503 and a window 1502 attached to it. The window may be a transparent display as long as it is not a window for checking the front and rear of the automobile. The transparent display may have an organic light-emitting element according to this embodiment. In this case, the constituent materials of the electrodes and the like of the organic light-emitting element are made of transparent materials.

The moving body according to this embodiment may be a ship, an aircraft, a drone, or the like. The moving body may have a body and a lamp provided on the body. The lamp may emit light to indicate the position of the body. The lamp has an organic light-emitting element according to this embodiment.

As explained above, by using a device using the organic light-emitting element according to this embodiment, it is possible to achieve a display with good image quality and stability even over long periods of time.

The following describes examples. However, the present invention is not limited to these examples.

[Synthesis Example 1]
Synthesis of Compound (16) Compound (16) was synthesized according to the following procedure. First, the synthesis of the ligand will be described.

In a nitrogen atmosphere, 1.36 g of boronic acid, 2.14 g of halogen, 0.38 g of tetrakistriphenylphosphine palladium, 15 ml of toluene, 7.5 ml of ethanol, and 15 ml of 2M aqueous sodium carbonate solution were added to a 100 ml eggplant flask. The temperature was raised from room temperature to 90°C, and the mixture was stirred for 16 hours and 30 minutes. Toluene and water were added, and magnesium sulfate was added to the organic layer from which the organic layer was extracted, and the mixture was filtered. After concentration, the mixture was columned with chloroform. The resulting liquid was concentrated and recrystallized with heptane, and 2.288 g of the ligand was obtained. The structure was identified by ¹ H NMR and GC-MS.

Next, we will explain the synthesis of chlorobridge dimers.

In a nitrogen atmosphere, 1.36 g of iridium chloride, 2.288 g of ligand, 30 ml of 2-ethoxyethanol, and 15 ml of water were added to a 100 ml recovery flask. The temperature was raised from room temperature to 120°C and stirred for 20 hours. Water was added and the mixture was suction filtered. The mixture was redispersed in ethanol and washed. Toluene was added, the temperature was raised to 100°C, and after cooling, 2.65 g was obtained by filtration. The structure was identified by ¹ H NMR.

In a nitrogen atmosphere, 1.3 g of the dimer, 0.45 g of sodium carbonate, 1045 μl of 2,2,6,6-tetramethylheptane-3,5-dione, and 40 ml of 2-ethoxyethanol were added to a 100 ml eggplant flask. The temperature was raised from room temperature to 120°C and stirred for 13 hours. Water and ethanol were added and suction filtered. Chlorobenzene was added and dissolved, and the mixture was filtered through Celite. The resulting liquid was concentrated and then recrystallized with chloroform-methanol to obtain 0.73 g of a red powder. The structure was identified by ¹ H NMR and MALDI-MASS. X-ray structural analysis also showed that the product was of the HNT type.

[Synthesis Examples 2 to 7]
Compound (31), compound (56), compound (22), compound (91), compound (92) and compound (94) were synthesized according to Synthesis Example 1.

[Measurement of composition ratio of composition]
The composition ratio of the composition containing compound (16) obtained in Synthesis Example was measured by the following procedure: 1 mg of the red powder obtained in Synthesis Example was collected, dissolved in 1 mL of dichloromethane, and subjected to HPLC measurement, and the content of compound (16) was 98.5% and the content of the isomer was 1.5%.

HPLC measurement conditions: The column used was an ODS-SP 5 μm 4.6 * 150 mm, and methanol was used as the developing solvent. The flow rate was 1.0 mL/min.

The retention time of compound (16) was 6.1 min, and that of the isomer was 5.6 min. LC-MASS showed that they had the same molecular weight, confirming that they were isomers.

[Comparative Example 1]
The red powder obtained in Synthesis Example 1 was purified by sublimation at 360° C. and 3×10 ⁻³ Pa, and the powder from the higher temperature side was recovered. It was found to be 98.9% compound (16) and 1.1% isomer.

Using the composition purified in Comparative Example 1 above, an organic light-emitting device having an anode/hole injection layer/hole transport layer/electron blocking layer/light-emitting layer/hole blocking layer/electron transport layer/cathode structure was fabricated on a substrate as follows.

A transparent conductive support substrate (ITO substrate) was prepared by forming an ITO film as an anode on a glass substrate by sputtering to a thickness of 100 nm. On this ITO substrate, the organic compound layer and electrode layer shown below were successively formed by vacuum deposition using resistance heating in a vacuum chamber at 1×10 ⁻⁵ Pa. The opposing electrodes were fabricated to have an area of 3 mm ² .
Hole injection layer (10 nm) HT16
Hole transport layer (30 nm) HT3
Electron blocking (EB) layer (10 nm) HT7
Emitting layer (30 nm) host material: EM33, assist material: GD10, guest material: composition (4 wt%)
Hole blocking (HB) layer (45 nm) ET12
Electron transport layer (20nm) ET7
Metal electrode layer 1 (0.5 nm) LiF
Metal electrode layer 2 (100 nm) Al

Next, to prevent the organic light-emitting element from deteriorating due to moisture absorption, a protective glass plate was placed over it in a dry air atmosphere and sealed with an acrylic resin adhesive.

For the obtained organic light-emitting device, a constant current of 20 mA/ ^cm2 was applied between the ITO electrode as the anode and the Al electrode as the cathode, and the driving life measurement was performed. LT ₉₅ : The time (hr) for the brightness to decay to 95% of the initial brightness was 140 hours.

[Comparative Example 2]
The red powder obtained in Synthesis Example 1 was purified by sublimation at 360° C. and 3×10 ⁻³ Pa. The powder recovered from the low temperature side was found to be 96.5% compound (16) and 3.5% isomer.

An organic light-emitting device was fabricated in the same manner as in Comparative Example 1, except that the composition obtained in Comparative Example 2 was used instead of the composition obtained in Comparative Example 1.

The organic light-emitting device thus obtained was subjected to measurement of its operating life by applying a constant current of 20 mA/cm ² between the ITO electrode as the anode and the Al electrode as the cathode, and the LT ₉₅ was found to be 135 hours.

[Example 1]
The red powder obtained in Synthesis Example 1 was redispersed twice in toluene and washed. After vacuum drying at 150° C., sublimation purification was performed at 360° C. and 3×10 ⁻³ Pa, and the powder on the high temperature side was recovered. The content was 99.1% of compound (16) and 0.9% of the isomer.

An organic light-emitting device was fabricated in the same manner as in Comparative Example 1, except that the composition obtained in Example 1 was used instead of the composition obtained in Comparative Example 1.

The organic light-emitting device thus obtained was subjected to measurement of its operating life by applying a constant current of 20 mA/cm ² between the ITO electrode as the anode and the Al electrode as the cathode, and the LT ₉₅ was found to be 170 hours.

[Example 2]
The red powder obtained in Synthesis Example 1 was dissolved in chloroform and purified using a GPC purification apparatus (LC-9104: manufactured by Japan Analytical Industry Co., Ltd., column: JAIGEL-2H-40 x 2). The solution was concentrated and vacuum dried at 150°C, and then sublimation purification was performed at 360°C and 3 x ^10-3 Pa, and the powder on the high temperature side was recovered. The composition ratio was measured to find that the compound (16) accounted for 99.6% and the isomer accounted for 0.4%.

An organic light-emitting device was fabricated in the same manner as in Comparative Example 1, except that the composition obtained in Example 2 was used instead of the composition obtained in Comparative Example 1.

The organic light-emitting device thus obtained was subjected to measurement of its operating life by applying a constant current of 20 mA/cm ² between the ITO electrode as the anode and the Al electrode as the cathode, and the LT ₉₅ was found to be 200 hours.

[Example 3]
An organic light-emitting device was produced in the same manner as in Example 1, except that a composition containing the compound (31) obtained in Synthesis Example 2 was used instead of the composition obtained in Synthesis Example 1.

The organic light-emitting device thus obtained was subjected to measurement of its operating life by applying a constant current of 20 mA/cm ² between the ITO electrode as the anode and the Al electrode as the cathode, and the LT ₉₅ was found to be 335 hours.

[Example 4]
An organic light-emitting device was produced in the same manner as in Example 1, except that a composition containing the compound (56) obtained in Synthesis Example 3 was used instead of the composition obtained in Synthesis Example 1.

The organic light-emitting device thus obtained was subjected to measurement of its operating life by applying a constant current of 20 mA/cm ² between the ITO electrode as the anode and the Al electrode as the cathode, and the LT ₉₅ was found to be 500 hours.

[Example 5]
An organic light-emitting device was produced in the same manner as in Example 1, except that the composition containing the compound (22) obtained in Synthesis Example 4 was used instead of the composition obtained in Synthesis Example 1.

The organic light-emitting device thus obtained was subjected to measurement of its operating life by applying a constant current of 20 mA/cm ² between the ITO electrode as the anode and the Al electrode as the cathode, and the LT ₉₅ was found to be 210 hours.

[Example 6]
An organic light-emitting device was produced in the same manner as in Example 1, except that a composition containing the compound (91) obtained in Synthesis Example 5 was used instead of the composition obtained in Synthesis Example 1.

The organic light-emitting device thus obtained was subjected to measurement of its operating life by applying a constant current of 20 mA/cm ² between the ITO electrode as the anode and the Al electrode as the cathode, and the LT ₉₅ was found to be 535 hours.

[Example 7]
An organic light-emitting device was produced in the same manner as in Example 1, except that a composition containing the compound (92) obtained in Synthesis example 6 was used instead of the composition obtained in Synthesis example 1.

The organic light-emitting device thus obtained was subjected to measurement of its operating life by applying a constant current of 20 mA/cm ² between the ITO electrode as the anode and the Al electrode as the cathode, and the LT ₉₅ was found to be 485 hours.

[Example 8]
An organic light-emitting device was produced in the same manner as in Example 1, except that a composition containing the compound (94) obtained in Synthesis Example 7 was used instead of the composition obtained in Synthesis Example 1.

The organic light-emitting device thus obtained was subjected to measurement of its operating life by applying a constant current of 20 mA/cm ² between the ITO electrode as the anode and the Al electrode as the cathode, and the LT ₉₅ was found to be 470 hours.

The results of Examples 1 to 8 and Comparative Examples 1 and 2 are summarized in Table 1.

As described above, it has been found that the lifetime of an organic light-emitting device can be improved by setting the composition ratio of the iridium complex isomer to 1.0% or less in the composition according to the present invention.

LIST OF REFERENCE NUMERALS 1 Interlayer insulating layer 2 Reflective electrode 3 Insulating layer 4 Organic compound layer 5 Transparent electrode 6 Protective layer 7 Color filter 10 Subpixel 11 Substrate 12 Insulating layer 13 Gate electrode 14 Gate insulating film 15 Semiconductor layer 16 Drain electrode 17 Source electrode 18 Thin film transistor 19 Insulating film 20 Contact hole 21 Lower electrode 22 Organic compound layer 23 Upper electrode 24 First protective layer 25 Second protective layer 26 Organic light-emitting element 100 Display device 1000 Display device 1001 Upper cover 1002 Flexible printed circuit 1003 Touch panel 1004 Flexible printed circuit 1005 Display panel 1006 Frame 1007 Circuit board 1008 Battery 1009 Lower cover 1100 Imaging device 1101 Viewfinder 1102 Rear display 1103 Operation unit 1104 Housing 1200 Electronic device 1201 Display unit 1202 Operation unit 1203 Housing 1300 Display device 1301 Frame 1302 Display unit 1303 Base 1310 Display device 1311 First display unit 1312 Second display unit 1313 Housing 1314 Bend point 1400 Illumination device 1401 Housing 1402 Light source 1403 Circuit board 1404 Optical film 1405 Light diffusion unit 1500 Automobile 1501 Tail lamp 1502 Window 1503 Vehicle body

Claims (20)

an HNT (Homo-N-Trans) type iridium complex having an iridium atom, a first ligand, a second ligand, and a third ligand bonded to the iridium atom, the second ligand having the same structure as the first ligand, and the third ligand having a structure different from the first ligand and the second ligand;
an iridium atom, a fourth ligand, a fifth ligand, and the third ligand;
The fourth ligand is a ligand represented by the same rational formula as the first ligand,
and an isomer of the iridium complex, wherein the fifth ligand is a ligand represented by the same rational formula as the second ligand,
The iridium complex is represented by the following general formula [1] or general formula [2]:
A composition comprising the isomer in a ratio of 1.0% or less to the total of the iridium complex and the isomer.

In general formula [1] and general formula [2], L is a bidentate ligand, and R ¹ to R ¹⁸ are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a cyano group, a substituted or unsubstituted aromatic hydrocarbon group, and a substituted or unsubstituted heteroaromatic group.
Ring A represents a cyclic structure selected from a benzene ring, a naphthalene ring, a fluorene ring, a phenanthrene ring, a 9,9-spirobifluorene ring, a chrysene ring, and a substituted or unsubstituted heteroaromatic group. The cyclic structure may have a substituent.
IrL is represented by any one of the following general formulas [3] to [5].

In the general formulae [3] to [5], R ¹⁹ to R ³³ are each independently selected from a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aromatic hydrocarbon group, and a substituted or unsubstituted heteroaromatic group. The composition according to claim 1, characterized in that the composition ratio of the isomer is 0.6% or less. 3. The composition according to claim 1, wherein the isomer is a structural isomer of the iridium complex and satisfies at least one of the following (1) and (2):
(1) The first ligand and the fourth ligand have different structures.
(2) The second ligand and the fifth ligand have different structures. The composition according to claim 3, characterized in that the first ligand and the second ligand have a structure having a substituent, and the fourth ligand or the fifth ligand has a structure in which the substitution position of the substituent is different from that of the first ligand or the second ligand. The composition according to claim 3 or 4, characterized in that it satisfies both (1) and (2). The composition according to claim 1 or 2, characterized in that the isomer is a stereoisomer of the iridium complex and satisfies at least one of the following (3) and (4):
(3) The first ligand and the fourth ligand have different steric configurations with respect to the iridium atom.
(4) The second ligand and the fifth ligand have different steric configurations with respect to the iridium atom. The composition according to claim 6, characterized in that it satisfies both (3) and (4). The composition according to any one of claims 1 to 7, characterized in that the iridium complex is an iridium complex represented by the following general formula [6]:

In the general formula [6], R ³⁴ to R ⁴⁸ are each independently selected from a hydrogen atom and a substituted or unsubstituted alkyl group, and R ⁴² to R ⁴⁵ may be bonded to each other to form a ring structure. The iridium complex is represented by the general formula [6], in which R ⁴⁵ is a hydrogen atom and R ⁴³ is an alkyl group;
The composition according to claim 8, characterized in that, in the isomer of the iridium complex, R ⁴⁵ in the general formula [6] is an alkyl group and R ⁴³ is a hydrogen atom. The composition according to claim 8 or 9 , characterized in that in the iridium complex, R ³⁷ in the general formula [6] is a cyano group. An organic light-emitting device having a first electrode, a second electrode, and an organic compound layer disposed between the first electrode and the second electrode,
The organic compound layer comprises the composition according to claim 1 . the organic compound layer is a light-emitting layer, and the light-emitting layer further comprises a first organic compound;
The organic light-emitting element according to claim 11, wherein the first organic compound is a compound having a minimum excited triplet energy greater than that of the iridium complex contained in the composition. The organic light-emitting element according to claim 12, characterized in that the light-emitting layer further contains a second organic compound, and the lowest excited triplet energy of the second organic compound is equal to or greater than the lowest excited triplet energy of the iridium complex contained in the composition and equal to or less than the lowest excited triplet energy of the first organic compound. the organic compound layer further includes a first charge transport layer disposed between the first electrode and the light-emitting layer, and a second charge transport layer disposed between the second electrode and the light-emitting layer,
14. The organic light-emitting element according to claim 12, wherein the first electrode is in contact with the first charge transport layer, and the second electrode is in contact with the second charge transport layer. A display device having a plurality of pixels, at least one of which has an organic light-emitting element according to any one of claims 11 to 14 and a transistor connected to the organic light-emitting element. The display device according to claim 15, characterized in that it has a color filter on the light-emitting side of the organic light-emitting element. an optical unit having a plurality of lenses, an image sensor that receives light that has passed through the optical unit, and a display unit that displays an image captured by the image sensor;
An imaging device, wherein the display section comprises the organic light-emitting element according to claim 11 . An electronic device comprising: a display unit having the organic light-emitting element according to any one of claims 11 to 14; a housing in which the display unit is provided; and a communication unit provided in the housing and communicating with the outside. A lighting device comprising a light source having the organic light-emitting element according to any one of claims 11 to 14, and a light diffusion section or an optical film that transmits the light emitted by the light source. A moving body comprising a lighting device having the organic light-emitting element according to any one of claims 11 to 14, and a body on which the lighting device is provided.

Images