JP7367574B2 - aromatic compounds - Google Patents

Description

The present invention relates to aromatic compounds with high thermal durability.
The present invention also provides an organic electroluminescent device (hereinafter sometimes referred to as "OLED" or "device") containing the compound, a composition containing the compound and a solvent, and an organic electroluminescent device containing the compound. The present invention relates to lighting devices and display devices.
The present invention also relates to a method for forming a thin film and a method for manufacturing an organic electroluminescent device.

In recent years, as thin film type electroluminescent elements, organic electroluminescent elements using organic thin films have been developed instead of those using inorganic materials. An organic electroluminescent device (OLED) typically has a hole injection layer, a hole transport layer, an organic light emitting layer, an electron transport layer, etc. between an anode and a cathode. Materials suitable for each layer are being developed, and the colors of emitted light are also being developed into red, green, and blue. Furthermore, research is underway on coating-type OLEDs, which have higher material utilization efficiency and lower manufacturing costs than conventional vapor-deposited OLEDs.

In coating type OLEDs, there is a demand for longer life of the element and driving with lower power consumption. There are various factors that can affect the lifespan of an element and the improvement of power consumption, but for example, the thermal durability and crystallinity of the materials that make up the element are thought to have a major influence on the lifespan. .

Further, in order to manufacture an organic electroluminescent device by a wet film forming method, all the materials used must be able to be dissolved in an organic solvent and used as an ink. If the material used has poor solubility, operations such as heating for a long time are required, which may cause the material to deteriorate before use. Furthermore, if a uniform state cannot be maintained for a long time in a solution state, the material will precipitate from the solution, making it impossible to form a film using an inkjet device or the like. Materials used in the wet film forming method are required to have solubility in two senses: to dissolve quickly in an organic solvent, and to maintain a uniform state without precipitating after dissolution.

In an organic electroluminescent device using an organic thin film made of a plurality of low-molecular materials formed by a wet film-forming method, Non-Patent Document 1 describes a device that uses phosphorescence to increase the luminous efficiency of the device. ing. The biphenyl derivatives shown below are used as the charge transport material of the organic electroluminescent device described in Non-Patent Document 1.

Further, Patent Documents 1 and 2 report OLED materials using a nitrogen-containing polyfused ring compound as a host compound of a phosphorescent compound.

International Publication No. 2015/014434 Special Publication No. 2013-510803

Japanese Journal of Applied Physics Vol.44,No.1B, 2005, pp.626-629

However, the compound described in Non-Patent Document 1, the compound described in Patent Document 1, and the compound described in Patent Document 2 have high charge transport properties in the light emitting layer, and the life of an organic electroluminescent device containing the compound is shortened. It may decrease.

Further, the compound described in Non-Patent Document 1, the compound described in Patent Document 1, and the compound described in Patent Document 2 do not have sufficient heat resistance.

The present invention has been made in view of the above-mentioned conventional situation, and an object thereof is to provide an aromatic compound that moderates the charge transport property within an organic layer such as a light emitting layer and has excellent heat resistance. do.

Another object of the present invention is to provide an organic electroluminescent device having the compound, a composition containing the compound and a solvent, and a lighting device and a display device including the organic electroluminescent device. Furthermore, an object of the present invention is to provide a method for forming a thin film and a method for manufacturing an organic electroluminescent device using the composition.

As a result of intensive studies by the present inventors, we found that by using an aromatic compound with a specific structure including a dibenzofuran structure, the aromatic compound can moderate the charge transport property within an organic layer such as a light emitting layer, and Tg (Glass transition temperature) and excellent heat resistance, and arrived at the present invention.
That is, the gist of the present invention resides in the following <1> to <10>.

<1> An aromatic compound represented by the following general formula (1).

In formula (1), R ¹ and R ² are each independent and are represented by the following general formula (2) or the following general formula (3), and R ³ is an alkyl group, an alkenyl group, an alkynyl group, or an alkoxy group. , an aryloxy group, an alkoxycarbonyl group, an acyl group, a halogen atom, a haloalkyl group, an alkylthio group, an arylthio group, a silyl group, a siloxy group, a cyano group, or an aralkyl group, and a is an integer of 0 to 6. However, at least one of R ¹ and R ² is represented by the following general formula (2).

In formula (2), the asterisk (*) represents a bond with formula (1), Ar ¹ is a divalent aromatic hydrocarbon group having 20 or less carbon atoms that may have a substituent, n is an integer of 1 or more.

In formula (3), the asterisk (*) represents a bond with formula (1), and ^Ar2 is a divalent aromatic hydrocarbon group having 20 or less carbon atoms that may have a substituent, Ar ³ is a monovalent aromatic hydrocarbon group having 20 or less carbon atoms which may have a substituent, and m is an integer of 1 or more.
<2> An organic electroluminescent element having an anode and a cathode on a substrate, and an organic layer between the anode and the cathode,
The organic electroluminescent device, wherein the organic layer has a layer containing an organic electroluminescent device material, and the organic electroluminescent device material is the aromatic compound according to <1>.
<3> The organic electroluminescent device according to <2>, wherein the layer containing the organic electroluminescent device material is a light emitting layer.
<4> A display device comprising the organic electroluminescent element according to <2> or <3>.
<5> A lighting device comprising the organic electroluminescent element according to <2> or <3>.
<6> A composition containing the aromatic compound according to <1> and a solvent.
<7> The composition according to <6>, further containing a phosphorescent material and a host material.
<8> A thin film forming method comprising the step of forming a film from the composition according to <6> or <7> by a wet film forming method.
<9> A method for manufacturing an organic electroluminescent device having an anode and a cathode on a substrate, and an organic layer between the anode and the cathode,
A method for manufacturing an organic electroluminescent device, comprising the step of forming the organic layer by a wet film forming method using the composition according to <6> or <7>.
<10> The method for manufacturing an organic electroluminescent device according to <9>, wherein the organic layer is a light emitting layer.

The aromatic compound of the present invention moderates charge transport properties in organic layers such as light emitting layers and has excellent heat resistance. Further, since the aromatic compound of the present invention has excellent solubility in various solvents and is amorphous, it is possible to form a thin film by a wet film forming method.

Therefore, by using the aromatic compound of the present invention, it is possible to easily provide an organic electroluminescent device that has excellent driving stability and can be driven at a low driving voltage.

The organic electroluminescent device of the present invention, which includes a light-emitting layer formed using the aromatic compound of the present invention, has excellent electrochemical stability, low driving voltage, and high efficiency, so that it can be used for flat panel displays, etc. (e.g. OA computer displays and wall-mounted TVs), in-vehicle display elements, mobile phone displays, light sources that take advantage of the characteristics of surface light emitters (e.g. light sources for copying machines, backlight sources for liquid crystal displays and instruments), displays It can be applied to boards and marker lights, and its technical value is great.

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

Embodiments of the present invention will be described in detail below, but the present invention is not limited to the following embodiments, and can be implemented with various modifications within the scope of the gist.

In the present invention, "may have a substituent" means that it may have one or more substituents.

<Aromatic compound of the present invention>
The aromatic compound of the present invention is an aromatic compound characterized by having a structure containing a dibenzofuran structure represented by the following general formula (1).

In formula (1), R ¹ and R ² are each independent and are represented by the following general formula (2) or the following general formula (3), and R ³ is an alkyl group, an alkenyl group, an alkynyl group, or an alkoxy group. , an aryloxy group, an alkoxycarbonyl group, an acyl group, a halogen atom, a haloalkyl group, an alkylthio group, an arylthio group, a silyl group, a siloxy group, a cyano group, or an aralkyl group, and a is an integer of 0 to 6. However, at least one of R ¹ and R ² is represented by the following general formula (2).

In formula (2), the asterisk (*) represents a bond with the dibenzofuran structure of formula (1), and Ar ¹ is a divalent aromatic hydrocarbon group having 20 or less carbon atoms that may have a substituent. and n is an integer of 1 or more.

In formula (3), the asterisk (*) represents a bond with the dibenzofuran structure of formula (1), and Ar ² is a divalent aromatic hydrocarbon group having 20 or less carbon atoms that may have a substituent. , Ar ³ is a monovalent aromatic hydrocarbon group having 20 or less carbon atoms which may have a substituent, and m is an integer of 1 or more.

When a is 2 or more, a plurality of R ^3s may be the same or different. R ³ is preferably an alkyl group, an alkoxy group, or an aralkyl group. Specific examples and preferred ranges of R ³ are the same as the corresponding substituents in substituent group Z described below.
Further, from the viewpoints of durability and heat resistance, the aromatic compound of the present invention is preferably an aromatic compound represented by the following general formula (1a) when a is 0.

In formula (1a), the definitions of R ¹ and R ² are the same as the definitions of R ¹ and R ² in formula (1).

The compound represented by the general formula (1) of the present invention has aromatic ring groups at the 1st and 2nd positions of the dibenzofuran skeleton, which reduces intermolecular interaction due to steric hindrance and reduces crystallinity. It is thought that this makes it possible to suppress charge transport properties in the light emitting layer.

Furthermore, since the compound represented by the general formula (1) of the present invention has two or more dibenzofuran skeletons, it has excellent heat resistance.

<Ar ¹ >
In formula (2), Ar ¹ represents a divalent aromatic hydrocarbon group having 20 or less carbon atoms which may have a substituent. Examples of the aromatic hydrocarbon group having 20 or less carbon atoms include a benzene ring, a naphthalene ring, a phenanthrene ring, a chrysene ring, a pyrene ring, a benzanthracene ring, and a perylene ring. From the viewpoint of solubility of the compound, a benzene ring and a naphthalene ring are preferred, and a benzene ring is more preferred.

From the viewpoints of solubility and heat resistance of the compound, n is more preferably 2 or more, preferably 7 or less, more preferably 5 or less, even more preferably 4 or less, and particularly preferably 3 or less.

When n is 2 or more, a plurality of Ar ¹ 's may be the same or different.
When a plurality of Ar ¹ 's exist, it is preferable that all Ar ¹ 's are benzene rings.
Note that n is the number of repetitions of Ar ¹ .

^<Ar2>
In formula (3), Ar ² is a divalent aromatic hydrocarbon group having 20 or less carbon atoms which may have a substituent. Examples of the aromatic hydrocarbon group having 20 or less carbon atoms include a benzene ring, a naphthalene ring, a phenanthrene ring, a chrysene ring, a pyrene ring, a benzanthracene ring, and a perylene ring. From the viewpoint of solubility of the compound, a benzene ring and a naphthalene ring are preferred, and a benzene ring is more preferred.

From the viewpoints of solubility and heat resistance of the compound, m is more preferably 2 or more, further preferably 3 or more, preferably 7 or less, more preferably 5 or less, and even more preferably 4 or less.

When m is 2 or more, a plurality of Ar ² 's may be the same or different.
When a plurality of Ar ^2s exist, it is more preferable that all Ar ^2s are benzene rings.
Note that m is the number of repetitions of ^Ar2 .

<Ar ³ >
In formula (3), Ar ³ is a monovalent aromatic hydrocarbon group having 20 or less carbon atoms which may have a substituent. Examples of the aromatic hydrocarbon group having 20 or less carbon atoms include a benzene ring, a naphthalene ring, a phenanthrene ring, a chrysene ring, a pyrene ring, a benzanthracene ring, and a perylene ring. From the viewpoint of solubility and heat resistance of the compound, a benzene ring, a naphthalene ring, and a phenanthrene ring are preferred, and a benzene ring is more preferred.

<(Ar ¹ ) _n , (Ar ² ) _m >
At least one of (Ar ¹ ) _n and (Ar ² ) _m has a partial structure represented by the following formula (11) or a partial structure represented by the following formula (12) from the viewpoint of the solubility and heat resistance of the compound. , and at least one partial structure selected from the partial structures represented by the following formula (13).

In each of the above formulas (11) to (13), * represents a bond with an adjacent structure or a hydrogen atom, and at least one of the two * represents a bond position with an adjacent structure.

More preferably, at least one of (Ar ¹ ) _n and (Ar ² ) _m has at least a partial structure represented by formula (11) or a partial structure represented by formula (12).
More preferably, (Ar ¹ ) _n and (Ar ² ) _m each have at least a partial structure represented by formula (11) or a partial structure represented by formula (12).
Particularly preferably, (Ar ¹ ) _n and (Ar ² ) _m each have a partial structure represented by formula (11) and a partial structure represented by formula (12).

Formula (12) is preferably the following formula (12-2).

In addition, the structures represented by the following formulas (14) to (18), which include a plurality of structures selected from the partial structures represented by the formula (11) and the partial structures represented by the formula (12), Partial structures are more preferred.

A structure including a plurality of structures selected from the partial structure represented by formula (11) and the partial structure represented by formula (12) is, for example, formula (14), as shown in formula (14a) below, This partial structure has one partial structure represented by formula (11) and two partial structures represented by formula (12).

Further preferably, at least one of (Ar ¹ ) _n and (Ar ² ) _m has at least a partial structure represented by formula (15) or a partial structure represented by formula (17).

Preferably, the formula (15) is the following formula (15-2).

Preferably, the formula (17) is the following formula (17-2).

Preferably, the formula (18) is the following formula (18-2).

Further, as the structure including the partial structure represented by formula (13), it is more preferable to have a partial structure represented by the following formula (19) or a partial structure represented by the following formula (20).

In each of the above formulas (14) to (20), * represents a bond with an adjacent structure or a hydrogen atom, and at least one of the two * represents a bond position with an adjacent structure.

<Substituents that Ar ¹ to Ar ³ may have>
The substituent that Ar ¹ to Ar ³ may have can be selected from, for example, substituent group Z described below.

[Substituent group Z]
Substituent group Z includes alkyl groups, alkenyl groups, alkynyl groups, alkoxy groups, aryloxy groups, alkoxycarbonyl groups, acyl groups, halogen atoms, haloalkyl groups, alkylthio groups, arylthio groups, silyl groups, siloxy groups, and cyano groups. , an aralkyl group, or an aromatic hydrocarbon group.

Examples of the alkyl group include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert-butyl group, n-hexyl group, and cyclohexyl group. , dodecyl group, etc., which have a carbon number of usually 1 or more, preferably 4 or more, and usually 24 or less, preferably 12 or less, and are linear, branched, or cyclic alkyl groups.

Examples of the alkenyl group include alkenyl groups such as vinyl groups, which usually have 2 or more carbon atoms and usually 24 or less carbon atoms, preferably 12 or less carbon atoms.

Examples of the alkynyl group include an alkynyl group such as an ethynyl group, which usually has 2 or more carbon atoms and usually has 24 or less carbon atoms, preferably 12 or less carbon atoms.

Examples of the alkoxy group include alkoxy groups such as a methoxy group and an ethoxy group, which usually have 1 or more carbon atoms and usually have 24 or less carbon atoms, preferably 12 or less carbon atoms.

Examples of the aryloxy group include aryloxy groups or heteroaryloxy groups having a carbon number of usually 4 or more, preferably 5 or more, and usually 36 or less, preferably 24, such as a phenoxy group, a naphthoxy group, or a pyridyloxy group. Examples include groups.

Examples of the alkoxycarbonyl group include alkoxycarbonyl groups such as a methoxycarbonyl group and an ethoxycarbonyl group, which usually have 2 or more carbon atoms and usually have 24 or less carbon atoms, preferably 12 or less carbon atoms.

Examples of the acyl group include acyl groups such as an acetyl group and a benzoyl group, which usually have 2 or more carbon atoms and usually have 24 or less carbon atoms, preferably 12 or less carbon atoms.

Examples of the halogen atom include halogen atoms such as a fluorine atom and a chlorine atom.

Examples of the haloalkyl group include haloalkyl groups such as a trifluoromethyl group, which usually have 1 or more carbon atoms and usually have 12 or less carbon atoms, preferably 6 or less carbon atoms.

Examples of the alkylthio group include alkylthio groups such as a methylthio group and an ethylthio group, which usually have 1 or more carbon atoms and usually have 24 or less carbon atoms, preferably 12 or less carbon atoms.

Examples of the arylthio group include arylthio groups such as a phenylthio group, a naphthylthio group, and a pyridylthio group, which usually have 4 or more carbon atoms, preferably 5 or more carbon atoms, and usually have 36 or less carbon atoms, preferably 24 or less carbon atoms.

Examples of the silyl group include silyl groups such as trimethylsilyl group and triphenylsilyl group, which usually have 2 or more carbon atoms, preferably 3 or more carbon atoms, and usually have 36 or less carbon atoms, preferably 24 or less carbon atoms.

Examples of the siloxy group include siloxy groups such as trimethylsiloxy group and triphenylsiloxy group, which usually have 2 or more carbon atoms, preferably 3 or more carbon atoms, and usually have 36 or less carbon atoms, preferably 24 or less carbon atoms.

Examples of the aralkyl group include aralkyl groups having usually 7 or more carbon atoms, preferably 10 or more carbon atoms, and usually 30 or less carbon atoms, preferably 18 or less carbon atoms, such as benzyl group and 2-phenylethyl group.

Examples of the aromatic hydrocarbon group include aromatic hydrocarbon groups such as a phenyl group and a naphthyl group, which usually have 6 or more carbon atoms and usually have 36 or less carbon atoms, preferably 24 or less carbon atoms.

Examples of alkyl groups having 10 or less carbon atoms include methyl groups, ethyl groups, branched, straight chain or cyclic propyl groups, branched, straight chain or cyclic butyl groups, branched, straight chain or cyclic pentyl groups, branched , a linear or cyclic hexyl group, a branched, linear or cyclic octyl group, a branched, linear or cyclic nonyl group, a branched, linear or cyclic decyl group. From the viewpoint of stability of the compound, a methyl group, an ethyl group, a branched, linear or cyclic propyl group, and a branched, linear or cyclic butyl group are preferred, and a branched propyl group is particularly preferred.

Examples of aromatic hydrocarbon groups having 20 or less carbon atoms are monovalent substituents on aromatic rings, such as benzene ring, naphthalene ring, phenanthrene ring, anthracene ring, chrysene ring, pyrene ring, benzanthracene ring, perylene ring. etc. From the viewpoint of compound solubility, benzene rings and naphthalene rings are preferred.

Examples of aralkyl groups having 30 or less carbon atoms include benzyl group, 2-phenylethyl group, 2-phenylpropyl-2-yl group, 2-phenylbutyl-2-yl group, and 3-phenylpentyl-3-yl group. , 3-phenyl-1-propyl group, 4-phenyl-1-butyl group, 5-phenyl-1-pentyl group, 6-phenyl-1-hexyl group, 7-phenyl-1-heptyl group, 8-phenyl- 1-octyl group, etc.

Among the substituent group Z, preferred are alkyl groups, alkoxy groups, aromatic hydrocarbon groups, and aralkyl groups, and more preferred are alkyl groups having 10 or less carbon atoms and aromatic hydrocarbon groups having 20 or less carbon atoms. , an aralkyl group having 30 or less carbon atoms, and from the viewpoint of heat resistance and durability, a benzene ring is more preferable. Most preferably, Ar ¹ to Ar ³ have no substituents.

Moreover, each substituent in the above substituent group Z may further have a substituent. As those further substituents, the same ones as the above substituents (substituent group Z) can be used.

<Specific example>
Specific examples of the aromatic compound represented by formula (1) are shown below, but the present invention is not limited thereto.

<Applications of aromatic compounds>
The aromatic compound of the present invention can be suitably used as a material used in organic electroluminescent devices, that is, as a charge transport material for organic electroluminescent devices, and can also be suitably used as a charge transport material for other light emitting devices. be.

In particular, the aromatic compound of the present invention has steric hindrance due to having a dibenzofuran ring and an aromatic hydrocarbon group as a basic skeleton and having aromatic ring groups at the 1st and 2nd positions of the dibenzofuran ring. By having an aromatic ring group at the 1st position, due to steric hindrance with the hydrogen atom at the 8th position, the torsion with the dibenzofuran ring becomes larger than when the aromatic ring group is located at other bonding positions, resulting in higher nonconjugation. This seems to be a trend. In addition, by having an aromatic ring group at the 1st and 2nd positions as adjacent positions, it is possible to have an aromatic ring group at the conjugated 3rd position. The conjugation length is less likely to expand than when an aromatic ring group is present at the position.

Therefore, the aromatic compound of the present invention has a large energy gap (difference between HOMO and LUMO) and a high excited triplet level (T1), so it can be used as a host material, especially a phosphorescent material, in a light emitting layer of an organic electroluminescent device. Useful as host material.

In particular, the aromatic compound of the present invention can be used to manufacture organic electroluminescent devices by vacuum evaporation, and can also be used to form thin films by wet film formation. It is also suitable as a material for electroluminescent devices.

Therefore, if it is possible to manufacture an organic electroluminescent device using the material for an organic electroluminescent device comprising the aromatic compound of the present invention by a vacuum evaporation method, it is also possible to manufacture an organic electroluminescent device using the composition for an organic electroluminescent device containing the aromatic compound of the present invention. Alternatively, an organic electroluminescent device can also be manufactured by a wet film forming method.

The obtained organic electroluminescent device has excellent driving stability and can be driven with a low driving voltage.

<Materials for organic electroluminescent devices>
The organic electroluminescent device material of the present invention is composed of the aromatic compound of the present invention, and preferably dissolves in toluene in an amount of 2% by mass or more, more preferably 5% by mass or more.

As will be described later, aromatic hydrocarbons are preferred as the solvent contained in the composition for organic electroluminescent devices. Toluene is cited as a typical example of aromatic hydrocarbons, and solubility in toluene is used as an index showing the solubility of materials for organic electroluminescent devices.

It is preferable that the solubility of the material for an organic electroluminescent device of the present invention in toluene is 2% by mass or more, since the layer constituting the organic electroluminescent device can be easily formed by a wet film forming method. There is no particular limit to the upper limit of this solubility, but it is usually about 50% by mass.

<Composition for organic electroluminescent device>
The composition for an organic electroluminescent device of the present invention usually contains the aromatic compound of the present invention and a solvent, and preferably further contains a luminescent material and a host material.

[1] Solvent The solvent contained in the composition for an organic electroluminescent device of the present invention is not particularly limited as long as it is a solvent that can satisfactorily dissolve the aromatic compound of the present invention as a solute.

Since the aromatic compound of the present invention has high solubility, various solvents can be used. For example, aromatic hydrocarbons such as toluene, xylene, methysylene, cyclohexylbenzene, and tetralin; halogenated aromatic hydrocarbons such as chlorobenzene, dichlorobenzene, and trichlorobenzene; 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, and anisole. Aromatic ethers such as , phenethol, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole; phenyl acetate, phenyl propionate, methyl benzoate, benzoic acid Aromatic esters such as ethyl, propyl benzoate, and n-butyl benzoate; Ketones with alicyclic rings such as cyclohexanone and cyclooctanone; Aliphatic ketones such as methyl ethyl ketone and dibutyl ketone; alcohol; aliphatic alcohols such as butanol and hexanol; aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA); ethyl acetate, n-butyl acetate, ethyl lactate, Aliphatic esters such as n-butyl lactate can be used. Among these, aromatic hydrocarbons such as toluene, xylene, methysylene, cyclohexylbenzene, and tetralin are preferred because they have low solubility in water and do not change easily.

Many organic electroluminescent devices use materials such as cathodes that are significantly degraded by moisture, so the presence of moisture in the composition can cause moisture to remain in the film after drying, reducing the characteristics of the device. This is not desirable due to the possibility.

Examples of methods for reducing the amount of water in the composition include using a nitrogen gas blanket, using a desiccant, dehydrating the solvent in advance, and using a solvent with low water solubility. Among these, it is preferable to use a solvent with low water solubility because it can prevent the solution film from absorbing moisture in the atmosphere and becoming white during the wet film forming process.

From this point of view, the composition for an organic electroluminescent device of the present invention contains, for example, a solvent whose solubility in water at 25° C. is 1% by mass or less, preferably 0.1% by mass or less. It is preferable that the content is at least % by mass.

In addition, in order to reduce the decrease in film formation stability due to solvent evaporation from the composition during wet film formation, the solvent for the composition for organic electroluminescent elements should have a boiling point of 100°C or higher, preferably a boiling point of 150°C or higher. It is effective to use a solvent with a boiling point of 200°C or higher, more preferably 200°C or higher.

In addition, in order to obtain a more uniform film, it is necessary for the solvent to evaporate from the liquid film immediately after film formation at an appropriate rate. It is effective to use a solvent having a boiling point of more preferably 120°C or higher, usually lower than 270°C, preferably lower than 250°C, more preferably lower than 230°C.

A solvent that satisfies the above-mentioned conditions, that is, the solubility of the solute, the evaporation rate, and the solubility of water, may be used alone, or a mixture of two or more solvents may be used.

[2] Luminescent material It is preferable that the composition for an organic electroluminescent device of the present invention further contains a luminescent material. The luminescent material refers to a component that mainly emits light in the composition for an organic electroluminescent device of the present invention, and corresponds to a dopant component in the organic electroluminescent device. That is, the amount of light emitted from the composition for organic electroluminescent devices (unit: cd/m ² ) is usually 10 to 100%, preferably 20 to 100%, more preferably 50 to 100%, and most preferably 80 to 100%. If 100% of the luminescence is identified as being from a certain component material, it is defined as a luminescent material.

As the luminescent material, any known material can be used, and a fluorescent material or a phosphorescent material can be used alone or in combination, but from the viewpoint of internal quantum efficiency, a phosphorescent material is preferable.

When used in the composition for an organic electroluminescent device of the present invention, the maximum emission peak wavelength of this luminescent material is preferably in the range of 390 to 490 nm.

In addition, for the purpose of improving solubility in a solvent, it is also important to reduce the symmetry and rigidity of the luminescent material molecules, or to introduce lipophilic substituents such as alkyl groups.

Examples of fluorescent dyes that emit blue light (blue fluorescent dyes) include perylene, pyrene, anthracene, coumarin, p-bis(2-phenylethenyl)benzene, and derivatives thereof.
Examples of fluorescent dyes that give green light (green fluorescent dyes) include quinacridone derivatives and coumarin derivatives.

Examples of fluorescent dyes that give yellow luminescence (yellow fluorescent dyes) include rubrene, perimidone derivatives, and the like.
Examples of fluorescent dyes that emit red light (red fluorescent dyes) include DCM compounds, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, azabenzothioxanthene, and the like.

(phosphorescent material)
A phosphorescent material refers to a material that emits light from an excited triplet state. For example, a typical example is a metal complex compound containing Ir, Pt, Eu, etc., and the structure of the material preferably includes a metal complex.

Among metal complexes, phosphorescent organometallic complexes that emit light via the triplet state are known from the long period periodic table (hereinafter, unless otherwise specified, when we refer to the periodic table, we refer to the long period periodic table). ) Examples include Werner type complexes or organometallic complexes containing a metal selected from Groups 7 to 11 as a central metal. Such a phosphorescent material is preferably a compound represented by formula (201) or a compound represented by formula (205) described below, more preferably a compound represented by 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 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 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 exist, they may be the same or different.

Ar ²⁰¹ and Ar ²⁰³ each independently represent an aromatic hydrocarbon ring structure that may have a substituent or an aromatic heterocyclic structure that may have a substituent.

Ar ²⁰² is an aromatic hydrocarbon ring structure that may have a substituent, an aromatic heterocyclic structure that may have a substituent, or an aliphatic hydrocarbon structure that may have a substituent. represents.

Substituents bonded to ring A1, substituents bonded to ring A2, or substituents bonded to ring A1 and substituents bonded to ring A2 may bond 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 that constitutes a bidentate ligand together with B ²⁰¹ and B ²⁰² . When a plurality of B ²⁰¹ -L ²⁰⁰ -B ²⁰² exist, they may be the same or different.

i1 and i2 each independently represent an integer from 0 to 12.
i3 is an integer of 0 or more with an upper limit of the number that can be replaced by Ar ²⁰² .
j is an integer of 0 or more with an upper limit of the number that can be replaced by Ar ²⁰¹ .
k1 and k2 are each independently an integer of 0 or more, with the upper limit being the number that can be substituted into ring A1 and ring A2.
m is an integer from 1 to 3.

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 triphenyl ring, an acenaphthene ring, a fluoranthene ring, 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, an oxygen atom, or a sulfur atom as a hetero atom, and more preferably a furan ring or a benzofuran ring. , a thiophene ring, and 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.

The aromatic heterocycle in ring A2 is preferably an aromatic heterocycle having 3 to 30 carbon atoms and containing any of a nitrogen atom, an oxygen atom, or a sulfur atom as a heteroatom,
Specifically, pyridine ring, pyrimidine ring, pyrazine ring, triazine ring, imidazole ring, oxazole ring, thiazole ring, benzothiazole ring, benzoxazole ring, benzimidazole ring, quinoline ring, isoquinoline ring, quinoxaline ring, quinazoline ring, Examples include naphthyridine ring and 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, an imidazole ring, a benzothiazole ring, a quinoline ring, a quinoxaline ring, and a quinazoline ring.

A preferable combination of ring A1 and ring A2 is expressed as (ring A1-ring A2),
(benzene ring - pyridine ring), (benzene ring - quinoline ring), (benzene ring - quinoxaline ring), (benzene ring - quinazoline ring), (benzene ring - imidazole ring), (benzene ring - benzothiazole ring). .

The substituents that ring A1 and ring A2 may have can be arbitrarily selected, but are preferably one or more substituents selected from substituent group S described below.

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 6 to 30 carbon atoms,
Specifically, a benzene ring, a naphthalene ring, an anthracene ring, a triphenyl ring, an acenaphthene ring, a fluoranthene ring, and a fluorene ring are preferable.
More preferably, a benzene ring, a naphthalene ring, a fluorene ring,
Most preferred is a benzene ring.

When any of Ar ²⁰¹ , Ar ²⁰² , and Ar ²⁰³ is a fluorene ring that may have a substituent, the 9- and 9'-positions of the fluorene ring have a substituent or are bonded to adjacent structures. It is preferable that

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 the ortho or meta position. More preferably, at least one benzene ring is bonded to an adjacent structure at the 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 either a nitrogen atom, an oxygen atom, or a sulfur atom as a heteroatom,
Specifically, pyridine ring, pyrimidine ring, pyrazine ring, triazine ring, imidazole ring, oxazole ring, thiazole ring, benzothiazole ring, benzoxazole ring, benzimidazole ring, quinoline ring, isoquinoline ring, quinoxaline ring, quinazoline ring, Naphthyridine ring, phenanthridine ring, carbazole ring, dibenzofuran ring, dibenzothiophene ring,
More preferred are a pyridine ring, a pyrimidine ring, a triazine ring, a carbazole ring, a dibenzofuran ring, and 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 may have a substituent or be bonded to an adjacent structure. preferable.

When Ar ²⁰² is an aliphatic hydrocarbon structure that may have a substituent,
The aliphatic hydrocarbon structure is an aliphatic hydrocarbon structure having a linear, branched, or cyclic structure,
Preferably, it is an aliphatic hydrocarbon having 1 or more and 24 or less carbon atoms,
More preferably, it is an aliphatic hydrocarbon having 1 or more and 12 or less carbon atoms,
More preferably, it is an aliphatic hydrocarbon having 1 or more and 8 or less carbon atoms.

i1 and i2 are each independently preferably an integer of 1 to 12, more preferably an integer of 1 to 8, and even more preferably an integer of 1 to 6. Within this range, it is expected that solubility and charge transport properties will be improved.

i3 preferably represents an integer of 0 to 5, more preferably an integer of 0 to 2, and more preferably 0 or 1.

j preferably represents an integer of 0 to 2, more preferably 0 or 1.

k1 and k2 preferably represent an integer of 0 to 3, more preferably an integer of 1 to 3, more preferably 1 or 2, particularly preferably 1.

The substituents that Ar ²⁰¹ , Ar ²⁰² , and Ar ²⁰³ may have can be arbitrarily selected, but are preferably one or more substituents selected from the substituent group S described below, and more preferably hydrogen An atom, an alkyl group, or an aryl group, particularly preferably a hydrogen atom or an alkyl group, and most preferably an unsubstituted (hydrogen atom).

Unless otherwise specified, the substituent is preferably a group selected from the following substituent group S.

<Substituent group S>
・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, particularly preferably an alkyl group having 1 to 6 carbon atoms .
-Alkoxy group, preferably an alkoxy group having 1 to 20 carbon atoms, more preferably an alkoxy group having 1 to 12 carbon atoms, still more preferably an alkoxy group having 1 to 6 carbon atoms.
-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, particularly preferably an aryloxy group having 6 to 12 carbon atoms Aryloxy group.
- 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.
-Aralkyl group, preferably an aralkyl group having 7 to 40 carbon atoms, more preferably an aralkyl group having 7 to 18 carbon atoms, even more preferably an aralkyl group having 7 to 12 carbon atoms.
・Heteroaralkyl group, preferably a heteroaralkyl group having 7 to 40 carbon atoms, more preferably a heteroaralkyl group having 7 to 18 carbon atoms,
・Alkenyl group, preferably an alkenyl group having 2 to 20 carbon atoms, more preferably an alkenyl group having 2 to 12 carbon atoms, still more preferably an alkenyl group having 2 to 8 carbon atoms, 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.
-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, particularly preferably an aryl group having 6 to 14 carbon atoms .
・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, particularly preferably a heteroaryl group having 3 to 30 carbon atoms 14 heteroaryl groups.
- An alkylsilyl group, preferably an alkylsilyl group in which the alkyl group has 1 to 20 carbon atoms, more preferably an alkylsilyl group in which the alkyl group has 1 to 12 carbon atoms.
- An arylsilyl group, preferably an arylsilyl group in which the aryl group has 6 to 20 carbon atoms, more preferably an arylsilyl group in which the aryl group has 6 to 14 carbon atoms.
- An alkylcarbonyl group, preferably an alkylcarbonyl group having 2 to 20 carbon atoms.
-Arylcarbonyl group, preferably an arylcarbonyl group having 7 to 20 carbon atoms.
- Hydrogen atom, deuterium atom, fluorine atom, cyano group, or -SF 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, aryl is an aromatic hydrocarbon and heteroaryl is an aromatic heterocycle.

(Preferred group in substituent group S)
Among these substituent groups S,
Preferably, 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, and one or more hydrogen atoms of these groups are fluorine. a group substituted with an atom, a fluorine atom, a cyano group, or _-SF5 ,
More preferably 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 is replaced with a fluorine atom, a fluorine atom, a cyano group, or , - SF ₅ ,
More preferred are alkyl groups, alkoxy groups, aryloxy groups, arylamino groups, aralkyl groups, alkenyl groups, aryl groups, heteroaryl groups, alkylsilyl groups, and arylsilyl groups,
Particularly preferred are alkyl groups, arylamino groups, aralkyl groups, alkenyl groups, aryl groups, and heteroaryl groups,
Most preferred are alkyl groups, arylamino groups, aralkyl groups, aryl groups, and heteroaryl groups.

These substituent group S may further have a substituent selected from substituent group S as a substituent. Preferable groups, more preferable groups, still more preferable groups, particularly preferable groups, and most preferable groups of the substituents that may be included are the same as the preferable groups in substituent group S, etc.

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

In a structure having a group in which benzene rings are connected,
Ar ²⁰¹ is a benzene ring structure, i1 is 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 solubility and charge transport properties.

In 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,
Ar ²⁰¹ is an aromatic hydrocarbon structure or an aromatic heterocyclic structure, i1 is 1 to 6,
Ar ²⁰² is an aliphatic hydrocarbon structure, i2 is 1 to 12, preferably 3 to 8;
Ar ²⁰³ is a benzene ring structure, and i3 is 0 or 1.
In the case of this structure, Ar ²⁰¹ is preferably the aromatic hydrocarbon structure described above, more preferably a structure in which 1 to 5 benzene rings are connected, and more preferably one benzene ring.
This structure is expected to improve solubility and charge transport properties.

In a structure in which a dendron is bonded to ring A1 or ring A2,
Ar ²⁰¹ and Ar ²⁰² are benzene ring structures,
Ar ²⁰³ is a biphenyl or terphenyl structure,
i1 and i2 are 1 to 6, i3 is 2, and j is 2.
This structure is expected to improve solubility and charge transport properties.

Among the structures represented by B ²⁰¹ -L ²⁰⁰ -B ²⁰² , a structure represented by the following formula (203) or (204) is preferable.

R ²¹¹ , R ²¹² and R ²¹³ represent a substituent.

Ring B3 represents a nitrogen atom-containing aromatic heterocyclic structure which may have a substituent.
Ring B3 is preferably a pyridine ring.

The phosphorescent material represented by formula (201) is not particularly limited, but specifically includes the following structures.
In addition, Me means a methyl group, and Ph means a phenyl group.

Here, the compound represented by the following formula (205) will be explained.

In formula (205), M ² represents a metal, and T represents a carbon atom or a nitrogen atom. R ⁹² to R ⁹⁵ each independently represent a substituent. However, when T is a nitrogen atom, R ⁹⁴ and R ⁹⁵ are not present.

In formula (205), M ² represents a metal. Specific examples include metals selected from Groups 7 to 11 of the periodic table. Among these, ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, or gold is preferred, and divalent metals such as platinum and palladium are particularly preferred.

In addition, in formula (205), R ⁹² and R ⁹³ are each independently 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, It represents 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.

Further, 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 . Further, when T is a nitrogen atom, R ⁹⁴ or R ⁹⁵ directly bonded to T does not exist.

Furthermore, R ⁹² to R ⁹⁵ may further have a substituent. As the substituent, the above-mentioned substituents listed as R ⁹² and R ⁹³ can be used. Furthermore, any two or more groups among R ⁹² to R ⁹⁵ may be linked to each other to form a ring.

(molecular weight)
The molecular weight of the phosphorescent material is preferably 5,000 or less, more preferably 4,000 or less, particularly preferably 3,000 or less. Further, the molecular weight of the phosphorescent material is usually 800 or more, preferably 1000 or more, and more preferably 1200 or more. It is considered that by having a molecular weight in this range, the phosphorescent materials do not aggregate with each other and are uniformly mixed with the charge transporting material, thereby making it possible to obtain a luminescent layer with high luminous efficiency.

The molecular weight of the phosphorescent material is high in Tg, melting point, decomposition temperature, etc., the phosphorescent material and the formed light emitting layer have excellent heat resistance, and the film quality due to gas generation, recrystallization, molecular migration, etc. A larger value is preferable in that it is less likely to cause a decrease in the concentration of impurities or an increase in impurity concentration due to thermal decomposition of the material. On the other hand, the molecular weight of the phosphorescent material is preferably small in terms of ease of purification of the organic compound.

[3] Host material The composition for an organic electroluminescent device of the present invention preferably contains a host material.

The host material of the light emitting layer is a material having a skeleton with excellent charge transport properties, and is preferably selected from electron transport materials, hole transport materials, and bipolar materials capable of transporting both electrons and holes.

Specific examples of skeletons with excellent charge transport properties include aromatic structures, aromatic amine structures, triarylamine structures, dibenzofuran structures, naphthalene structures, phenanthrene structures, phthalocyanine structures, porphyrin structures, thiophene structures, benzylphenyl structures, Examples include a fluorene structure, a quinacridone structure, a triphenylene structure, a carbazole structure, a pyrene structure, an anthracene structure, a phenanthroline structure, a quinoline structure, a pyridine structure, a pyrimidine structure, a triazine structure, an oxadiazole structure, and an imidazole structure.

As the electron transport material, compounds having a pyridine structure, a pyrimidine structure, and/or a triazine structure, which have excellent electron transport properties and a relatively stable structure, are more preferable, and compounds having a pyrimidine structure and/or a triazine structure are more preferable. preferable.

The hole-transporting material is a compound having a structure with excellent hole-transporting properties, and among the skeletons with excellent charge-transporting properties, a carbazole structure, a dibenzofuran structure, a triarylamine structure, a naphthalene structure, a phenanthrene structure, or a pyrene structure is used. is preferable as a structure with excellent hole transport properties, and a carbazole structure, a dibenzofuran structure, or a triarylamine structure is more preferable.

The host material of the light emitting layer preferably has a fused ring structure of 3 or more rings, and more preferably a compound having 2 or more fused ring structures of 3 or more rings or a compound having at least one fused ring of 5 or more rings. preferable. These compounds increase the rigidity of molecules, making it easier to obtain the effect of suppressing the degree of molecular motion in response to heat. Further, the fused rings of 3 or more rings and the fused rings of 5 or more rings preferably have an aromatic hydrocarbon ring or an aromatic heterocycle from the viewpoint of charge transportability and material durability.

Specifically, the fused ring structure of three or more rings includes an anthracene structure, a phenanthrene structure, a pyrene structure, a chrysene structure, a naphthacene structure, a triphenylene structure, a fluorene structure, a benzofluorene structure, an indenofluorene structure, an indrofluorene structure, Examples include a carbazole structure, an indenocarbazole structure, an indolocarbazole structure, a dibenzofuran structure, and a dibenzothiophene structure.

From the viewpoint of charge transport properties and solubility, at least one selected from the group consisting of a phenanthrene structure, a fluorene structure, an indenofluorene structure, a carbazole structure, an indenocarbazole structure, an indolocarbazole structure, a dibenzofuran structure, and a dibenzothiophene structure. Preferably, from the viewpoint of durability against charges, a carbazole structure or an indolocarbazole structure is more preferable.

In the present invention, from the viewpoint of durability against charges of the organic electroluminescent device, it is preferable that at least one of the host materials of the light emitting layer is a material having a pyrimidine skeleton or a triazine skeleton.

The host material of the light-emitting layer is preferably a polymeric material from the viewpoint of excellent flexibility. A light-emitting layer formed using a material with excellent flexibility is preferable as a light-emitting layer of an organic electroluminescent device formed on a flexible substrate. When the host material contained in the light emitting layer is a polymeric material, the molecular weight is preferably 5,000 or more and 1,000,000 or less, more preferably 10,000 or more and 500,000 or less, and even more preferably 10,000 or more. 100,000 or less.

In addition, the host material for the emissive layer is a low-molecular weight compound that is easy to synthesize and purify, easy to design electron transport performance and hole transport performance, and easy to adjust the viscosity when dissolved in a solvent. It is preferable that When the host material contained in the light emitting layer is a low molecular weight material, the molecular weight is preferably 5,000 or less, more preferably 4,000 or less, particularly preferably 3,000 or less, and most preferably 2,000 or less. 000 or less, usually 300 or more, preferably 350 or more, more preferably 400 or more.

[4] Other Components The composition for an organic electroluminescent device of the present invention may contain various other solvents, as necessary, in addition to the solvent and luminescent material described above. Examples of such other solvents include amides such as N,N-dimethylformamide and N,N-dimethylacetamide, and dimethylsulfoxide.

Further, the composition for an organic electroluminescent device of the present invention may contain various additives such as a leveling agent and an antifoaming agent.
Furthermore, when laminating two or more layers by a wet film formation method, in order to prevent these layers from becoming compatible, a photocurable resin or a thermosetting resin is used to harden and insolubilize after film formation. It is also possible to contain.

[5] Material concentration and blending ratio in the composition for organic electroluminescent devices The aromatic compound of the present invention, the luminescent material, and components that can be added as necessary (leveling agents, etc.) in the composition for organic electroluminescent devices, etc. The solid content concentration is usually 0.01% by mass or more, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, and most preferably 1% by mass or more. The content is usually 80% by mass or less, preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, most preferably 20% by mass or less. When the concentration is within this range, it is easy to form a thin film with a desired thickness and a uniform thickness, which is preferable.

Further, in the composition for an organic electroluminescent device of the present invention, the mass mixing ratio of luminescent material/aromatic compound is usually 0.1/99.9 or more, more preferably 0.5/99.5 or more. , more preferably 1/99 or more, most preferably 2/98 or more, usually 50/50 or less, more preferably 40/60 or less, still more preferably 30/70 or less. , most preferably 20/80 or less. If this ratio falls below the lower limit or exceeds the upper limit, the luminous efficiency may drop significantly.

[6] Method for preparing composition for organic electroluminescent device The composition for organic electroluminescent device of the present invention comprises the aromatic compound of the present invention, the above-mentioned luminescent material as necessary, and leveling material that can be added as necessary. It is prepared by dissolving a solute consisting of various additives such as antifoaming agents and antifoaming agents in an appropriate solvent.

In order to shorten the time required for the dissolution step and to maintain a uniform solute concentration in the composition, the solute is usually dissolved while stirring the liquid. The dissolution step may be carried out at room temperature, but if the dissolution rate is slow, it may be carried out by heating. After the dissolution step, a filtration step such as filtering may be performed as necessary.

[7] Properties, physical properties, etc. of composition for organic electroluminescent device (moisture concentration)
When an organic electroluminescent device is manufactured by forming a layer by a wet film forming method using the composition for an organic electroluminescent device of the present invention, if moisture is present in the composition for an organic electroluminescent device used, the formed film may be damaged. It is preferable that the water content in the composition for an organic electroluminescent device of the present invention be as small as possible, since water may be mixed into the organic electroluminescent device composition, impairing the uniformity of the film. In addition, in general, organic electroluminescent devices often use materials such as cathodes that are significantly degraded by moisture, so if moisture is present in the composition for organic electroluminescent devices, moisture will be present in the film after drying. This is not preferable because it may remain and deteriorate the characteristics of the device.

Specifically, the amount of water contained in the composition for an organic electroluminescent device of the present invention is usually 1% by mass or less, preferably 0.1% by mass or less, and more preferably 0.01% by mass or less.

As a method for measuring the water concentration in a composition for an organic electroluminescent device, a method described in the Japanese Industrial Standards "Method for measuring moisture in chemical products" (JIS K0068:2001) is preferable, such as the Karl Fischer reagent method (JIS K0211). -1348), etc.

(uniformity)
The composition for an organic electroluminescent device of the present invention is preferably in a uniform liquid state at room temperature in order to improve the stability in a wet film formation process, for example, the stability of ejection from a nozzle in an inkjet film formation method. . The term "uniform liquid state at room temperature" means that the composition is a liquid consisting of a homogeneous phase and does not contain any particle component having a particle size of 0.1 μm or more.

(physical properties)
If the viscosity of the organic electroluminescent device composition of the present invention is extremely low, for example, non-uniformity of the coating surface due to excessive liquid film flow during the film forming process, nozzle ejection failure during inkjet film forming, etc. are likely to occur. If the viscosity of the organic electroluminescent device composition of the present invention is extremely high, nozzle clogging during inkjet film formation is likely to occur. Therefore, the viscosity of the composition of the present invention at 25° C. is usually 2 mPa·s or more, preferably 3 mPa·s or more, more preferably 5 mPa·s or more, and usually 1000 mPa·s or less, preferably 100 mPa·s or less. , more preferably 50 mPa·s or less.

In addition, if the surface tension of the organic electroluminescent device composition of the present invention is high, the wettability of the film-forming liquid to the substrate will be reduced, the leveling property of the liquid film will be poor, and the film-forming surface will be disturbed during drying. Therefore, the surface tension of the composition of the present invention at 20° C. is usually less than 50 mN/m, preferably less than 40 mN/m.

Furthermore, when the vapor pressure of the composition for an organic electroluminescent device of the present invention is high, problems such as changes in solute concentration due to evaporation of the solvent may easily occur. Therefore, the vapor pressure of the composition of the present invention at 25° C. is usually 50 mmHg or less, preferably 10 mmHg or less, more preferably 1 mmHg or less.

<Organic electroluminescent device>
The organic electroluminescent device of the present invention has an anode and a cathode on a substrate, and an organic layer between the anode and the cathode, the organic layer containing a material for an organic electroluminescent device. The organic electroluminescent device material is characterized in that it contains the aromatic compound of the present invention.

The layer containing the aromatic compound is preferably formed using the material for an organic electroluminescent device or the composition for an organic electroluminescent device of the present invention.
Moreover, it is preferable that the layer containing the organic electroluminescent element material is a light emitting layer.

Furthermore, it is preferable that the layer containing the aromatic compound is doped with an organometallic complex. As this organometallic complex, those exemplified as the luminescent material can be used.

In addition, the aromatic compound of the present invention has a large energy gap (difference between HOMO and LUMO), a high excited triplet level (T1), and has high hole transport properties, so it may be included in the electron blocking layer. preferable. Below, the layer structure of the organic electroluminescent device of the present invention, its general formation method, etc. will be explained with reference to FIG.

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

In the present invention, wet film forming methods include, for example, spin coating, dip coating, die coating, bar coating, blade coating, roll coating, spray coating, capillary coating, inkjet, and screen printing. It refers to a wet film forming method such as method, gravure printing method, flexographic printing method, etc. Among these film-forming methods, spin coating, spray coating, and inkjet methods are preferred. This is because the spin coating method, spray coating method, and inkjet method are compatible with the liquid properties specific to the coating composition used for organic electroluminescent devices.

[1] Substrate The substrate 1 serves as a support for the organic electroluminescent element, and may be a quartz or glass plate, a metal plate or metal foil, a plastic film or sheet, or the like. Particularly preferred are glass plates and plates made of transparent synthetic resins such as polyester, polymethacrylate, polycarbonate, and polysulfone. When using a synthetic resin substrate, it is necessary to pay attention to gas barrier properties. If the gas barrier property of the substrate is too low, the organic electroluminescent device may deteriorate due to outside air passing through the substrate. For this reason, one preferable method is to provide a dense silicon oxide film or the like on at least one side of the synthetic resin substrate to ensure gas barrier properties.

[2] Anode The anode 2 plays the role 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 an oxide of indium and/or tin, a metal halide such as copper iodide, carbon black, or It is composed of conductive polymers such as poly(3-methylthiophene), polypyrrole, and polyaniline.

The anode 2 is usually formed by a sputtering method, a vacuum evaporation method, or the like. In addition, when forming the anode 2 using metal fine particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, conductive polymer fine powder, etc., an appropriate binder resin solution may be used. The anode 2 can also be formed by dispersing the mixture and coating it on the substrate 1. Furthermore, in the case of a conductive polymer, a thin film can be directly formed on the substrate 1 by electrolytic polymerization, or the anode 2 can be formed by coating the conductive polymer on the substrate 1 (Appl. Phys. Lett. ., vol. 60, p. 2711, 1992).

The anode 2 usually has a single layer structure, but it can also have a laminated structure made of a plurality of materials if desired.

The thickness of the anode 2 varies depending on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode 2 is usually about 5 nm or more, preferably about 10 nm or more, and about 1000 nm or less, preferably about 500 nm or less. The thickness of the anode 2 may be arbitrary if it is opaque, and the thickness of the anode 2 may be the same as the thickness of the substrate 1. Furthermore, it is also possible to laminate different conductive materials on the anode 2 described above.

In order to remove impurities attached to the anode 2, adjust the ionization potential, and improve hole injection properties, the surface of the anode 2 was subjected to ultraviolet (UV)/ozone treatment, oxygen plasma treatment, and argon plasma treatment. It is preferable to

[3] Hole injection layer The hole injection layer 3 is a layer that transports holes from the anode 2 to the light emitting layer 5, and is usually formed on the anode 2.

The method for forming the hole injection layer 3 of the present invention may be a vacuum evaporation method or a wet film formation method, and is not particularly limited, but from the viewpoint of reducing dark spots, the hole injection layer 3 may be formed by a wet film formation method. is preferred.

The thickness of the hole injection layer 3 is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less.

(Formation of hole injection layer by wet film formation method)
When forming the hole injection layer 3 by a wet film forming method, the material constituting the hole injection layer 3 is usually mixed with an appropriate solvent (solvent for hole injection layer) to form a film forming composition ( A composition for forming a hole injection layer is prepared, and this composition for forming a hole injection layer is applied onto a layer corresponding to the lower layer of the hole injection layer 3 (usually an anode) by an appropriate method. A hole injection layer 3 is formed by forming a film and drying it.

(Hole transporting compound)
The composition for forming a hole injection layer usually contains a hole transporting compound and a solvent as constituent materials of the hole injection layer.

Hole-transporting compounds are usually compounds with hole-transporting properties used in the hole injection layer of organic electroluminescent devices, even if they are polymeric compounds such as polymers, monomers, etc. Although it may be a low molecular compound, a high molecular compound is preferable.

The hole transporting compound is preferably a compound having an ionization potential of 4.5 eV to 6.0 eV from the viewpoint of a charge injection barrier from the anode 2 to the hole injection layer 3. Examples of hole-transporting compounds include aromatic amine derivatives, phthalocyanine derivatives, porphyrin derivatives, oligothiophene derivatives, polythiophene derivatives, benzylphenyl derivatives, compounds in which tertiary amines are linked with fluorene groups, hydrazone derivatives, silazane derivatives, and silanamine. Examples include derivatives, phosphamine derivatives, quinacridone derivatives, polyaniline derivatives, polypyrrole derivatives, polyphenylene vinylene derivatives, polythienylene vinylene derivatives, polyquinoline derivatives, polyquinoxaline derivatives, carbon, and the like.

In the present invention, the derivative includes, for example, an aromatic amine derivative, the aromatic amine itself and a compound having an aromatic amine as its main skeleton, and even if it is a polymer, it may be a monomer. It may be a mercury.

The hole transporting compound used as the material for the hole injection layer 3 may contain any one type of such compounds alone, or may contain two or more types of such compounds. When containing two or more hole-transporting compounds, the combination is arbitrary, but one or more aromatic tertiary amine polymer compounds and one or two other hole-transporting compounds are used. It is preferable to use the above in combination.

Among the above-mentioned examples, 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 compound is a compound having an aromatic tertiary amine structure, and also includes a compound having a group derived from an aromatic tertiary amine.

The type of aromatic tertiary amine compound is not particularly limited, but from the viewpoint of uniform light emission due to the surface smoothing effect, polymer compounds (polymerized compounds with repeating units) having a weight average molecular weight of 1,000 or more and 1,000,000 or less are preferred. preferable. A preferred example of the aromatic tertiary amine polymer compound includes a polymer compound having a repeating unit represented by the following formula (I).

(In formula (I), Ar ⁵¹ and Ar ⁵² each independently represent an aromatic hydrocarbon group that may have a substituent or an aromatic heterocyclic group that may have a substituent. .Ar ⁵³ to Ar ⁵⁵ each independently represent an aromatic hydrocarbon group that may have a substituent or an aromatic heterocyclic group that may have a substituent.Y is the following: Represents a linking group selected from the group of linking groups.In addition, two groups bonded to the same N atom among Ar ⁵¹ to Ar ⁵⁵ may be bonded to each other to form a ring.)

(In each of the above formulas, Ar ⁵⁶ to Ar ⁶⁶ each independently represent an aromatic hydrocarbon group that may have a substituent or an aromatic heterocyclic group that may have a substituent. R ³¹ and R ³² each independently represent a hydrogen atom or an arbitrary substituent.)

The aromatic hydrocarbon groups and aromatic heterocyclic groups of Ar ⁵⁶ to Ar ⁶⁶ include benzene rings, naphthalene rings, phenanthrene rings, and thiophene rings from the viewpoint of solubility of polymer compounds, heat resistance, and hole injection/transport properties. A group derived from a ring or a pyridine ring is preferable, and a group derived from a benzene ring or a naphthalene ring is more preferable.

The aromatic hydrocarbon group and aromatic heterocyclic group of Ar ⁵⁶ to Ar ⁶⁶ may further have a substituent. The molecular weight of the substituent is usually 400 or less, preferably about 250 or less. Preferred examples of the substituent include an alkyl group, an alkenyl group, an alkoxy group, an aromatic hydrocarbon group, and an aromatic heterocyclic group.

When R ³¹ and R ³² are arbitrary substituents, examples of the substituents include alkyl groups, alkenyl groups, alkoxy groups, silyl groups, siloxy groups, aromatic hydrocarbon groups, aromatic heterocyclic groups, etc. .

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

In addition, as a hole-transporting compound, a conductive polymer (PEDOT/PSS) is made by polymerizing 3,4-ethylenedioxythiophene, a derivative of polythiophene, in high molecular weight polystyrene sulfonic acid. is also preferred. Alternatively, the ends of this polymer may be capped with methacrylate or the like.

The concentration of the hole transporting compound in the composition for forming a hole injection layer is arbitrary as long as it does not significantly impair the effects of the present invention, but from the viewpoint of uniformity of the film thickness, it is usually 0.01% by mass or more, preferably is 0.1% by mass or more, more preferably 0.5% by mass or more, and usually 70% by mass or less, preferably 60% by mass or less, more preferably 50% by mass or less. If this concentration is too high, unevenness in film thickness may occur, and if this concentration is too low, defects may occur in the formed hole injection layer.

(electron-accepting compound)
The composition for forming a hole injection layer preferably contains an electron-accepting compound as a constituent material of the hole injection layer. Here, the electron-accepting compound is preferably a compound having oxidizing power and the ability to accept one electron from the above-mentioned hole-transporting compound. Specifically, a compound having an electron affinity of 4 eV or more is preferable. , a compound having an electron affinity of 5 eV or more is more preferable.

Examples of such electron-accepting compounds include triarylboron compounds, metal halides, Lewis acids, organic acids, onium salts, salts of arylamines and metal halides, and salts of arylamines and Lewis acids. Examples include one or more compounds selected from the group.

Specifically, onium salts substituted with organic groups such as 4-isopropyl-4'-methyldiphenyliodonium tetrakis(pendafluorophenyl)borate and triphenylsulfonium tetrafluoroborate (International Publication No. 2005/089024); chloride High valence inorganic compounds such as iron (III) (JP 11-251067), ammonium peroxodisulfate; cyano compounds such as tetracyanoethylene, tris(pendafluorophenyl)borane (JP 2003-31365) aromatic boron compounds such as; fullerene derivatives; iodine; sulfonate ions such as polystyrene sulfonate ions, alkylbenzenesulfonate ions, camphor sulfonate ions, and the like.

These electron-accepting compounds can improve the electrical conductivity of the hole-injecting layer by oxidizing the hole-transporting compound.

The content of the electron-accepting compound relative to the hole-transporting compound in the hole-injection layer or the composition for forming the hole-injection layer is usually 0.1 mol% or more, preferably 1 mol% or more, and usually It is 100 mol% or less, preferably 40 mol% or less.

(Other constituent materials)
In addition to the above-mentioned hole-transporting compound and electron-accepting compound, the material for the hole-injecting layer may further contain other components as long as the effects of the present invention are not significantly impaired. Examples of other components include various luminescent materials, electron transporting compounds, binder resins, coating properties improvers, and the like. In addition, only one type of other components may be used, or two or more types may be used in combination in any combination and ratio.

(solvent)
At least one of the solvents in the hole injection layer forming composition used in the wet film forming method is preferably a compound capable of dissolving the above-mentioned constituent material of the hole injection layer. The boiling point of this solvent is usually 110°C or higher, preferably 140°C or higher, more preferably 200°C or higher, and usually 400°C or lower, preferably 300°C or lower. If the boiling point of the solvent is too low, the drying rate may be too fast and the film quality may deteriorate. Furthermore, if the boiling point of the solvent is too high, it is necessary to increase the temperature in the drying process, which may adversely affect other layers or the substrate.

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

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

Examples of the ester solvent include aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate.

Examples of aromatic hydrocarbon solvents include toluene, xylene, cyclohexylbenzene, 3-ylopropylbiphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, cyclohexylbenzene, methylnaphthalene, etc. Can be mentioned.

Examples of the amide solvent include N,N-dimethylformamide and N,N-dimethylacetamide.

In addition, dimethyl sulfoxide and the like can also be used.
These solvents may be used alone or in any combination and ratio of two or more.

(Film forming method)
After preparing a composition for forming a hole injection layer, this composition is coated on a layer corresponding to the lower layer of the hole injection layer 3 (usually the anode 2) by wet film formation, and then dried. A hole injection layer 3 is formed.

The temperature in the film forming step is preferably 10° C. or higher, and preferably 50° C. or lower in order to prevent defects in the film due to the formation of crystals in the composition.

The relative humidity in the film forming process is not limited as long as it does not significantly impair the effects of the present invention, but is usually 0.01 ppm or more and usually 80% or less.

After film formation, the film of the hole injection layer forming composition is usually dried by heating or the like. Examples of heating means used in the heating step include a clean oven, hot plate, infrared rays, halogen heater, and microwave irradiation. Among these, a clean oven and a hot plate are preferred in order to apply heat evenly to the entire film.

The heating temperature in the heating step is preferably a temperature equal to or higher than the boiling point of the solvent used in the hole injection layer forming composition, unless the effects of the present invention are significantly impaired. Further, in the case of a mixed solvent containing two or more types of solvents used in the hole injection layer, it is preferable that at least one type of solvent is heated at a temperature equal to or higher than the boiling point of the solvent. Considering the increase in the boiling point of the solvent, it is preferable to heat at a temperature of 120° C. or higher and 410° C. or lower in the heating step.

In the heating step, the heating time is not limited as long as the heating temperature is higher than the boiling point of the solvent of the hole injection layer forming composition and the coating film is not sufficiently insolubilized, but is preferably 10 seconds or longer, usually 180 seconds. minutes or less. If the heating time is too long, components of other layers tend to diffuse, and if the heating time is too short, the hole injection layer tends to become non-uniform. Heating may be performed in two steps.

(Formation of hole injection layer by vacuum evaporation method)
When forming the hole injection layer 3 by a vacuum evaporation method, one or more of the constituent materials of the hole injection layer 3 (the aforementioned hole transporting compound, electron accepting compound, etc.) are added in a vacuum container. (If two or more materials are used, put them in each crucible.) After evacuating the inside of the vacuum container to about 10 ^-4 Pa with an appropriate vacuum pump, heat the crucible (2 or more materials). When using more than one type of material, heat each crucible) and evaporate by controlling the amount of evaporation (when using two or more types of materials, evaporate by controlling the amount of evaporation independently for each), and A hole injection layer 3 is formed on the anode 2 of the substrates placed facing each other. In addition, when using two or more types of materials, the hole injection layer 3 can also be formed by putting the mixture in a crucible, heating and evaporating it.

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

[4] Hole Transport Layer The hole transport layer 4 of the present invention may be formed by a vacuum evaporation method or a wet film forming method, and is not particularly limited. It is preferable to form by a film forming method.

The hole transport layer 4 can be formed on the hole injection layer 3 when there is a hole injection layer, and on the anode 2 when there is no hole injection layer 3. Furthermore, the organic electroluminescent device of the present invention may have a configuration in which the hole transport layer is omitted.

The material forming the hole transport layer 4 is preferably a material that has high hole transport properties and can efficiently transport injected holes. For this purpose, it is preferable that the ionization potential is low, the transparency to visible light is high, the hole mobility is high, the stability is excellent, and impurities that become traps are hardly generated during production or use. In addition, in many cases, the hole transport layer 4 is in contact with the light-emitting layer 5, so it does not quench the light emitted from the light-emitting layer 5 or form an exciplex with the light-emitting layer 5, thereby reducing efficiency. It is preferable.

The material for the hole transport layer 4 may be any material that has conventionally been used as a constituent material of the hole transport layer, for example, the hole transport material used for the hole injection layer 3 described above. Examples of the compounds include those listed above. In addition, arylamine derivatives, fluorene derivatives, spiro derivatives, carbazole derivatives, pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, phthalocyanine derivatives, porphyrin derivatives, silole derivatives, oligothiophene derivatives, fused polycyclic aromatic Examples include group derivatives, metal complexes, and the like.

Further, for example, polyvinylcarbazole derivatives, polyarylamine derivatives, polyvinyltriphenylamine derivatives, polyfluorene derivatives, polyarylene derivatives, polyarylene ether sulfone derivatives containing tetraphenylbenzidine, polyarylene vinylene derivatives, polysiloxane derivatives, polythiophene derivatives, poly(p-phenylene vinylene) derivatives, and the like. These may be alternating copolymers, random polymers, block polymers or graft copolymers. It may also be a polymer whose main chain is branched and has three or more terminal parts, or a so-called dendrimer.

Among these, polyarylamine derivatives and polyarylene derivatives are preferred.
As the polyarylamine derivative, a polymer containing a repeating unit represented by the following formula (II) is preferable. In particular, a polymer consisting of repeating units represented by the following formula (II) is preferred, and in this case, Ar ^a or Ar ^b may be different in each repeating unit.

(In formula (II), Ar ^a and Ar ^b each independently represent an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent.)

Examples of the aromatic hydrocarbon group which may have a substituent include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, and an acenaphthene ring. Examples include groups derived from a 6-membered monocyclic ring or 2 to 5 condensed rings, such as a ring, a fluoranthene ring, a fluorene ring, and a group formed by connecting two or more of these rings with a direct bond.

Examples of the aromatic heterocyclic group which may have a substituent include a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, and a carbazole ring. , pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, shinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, azulene ring, etc. Examples include a ring or a group derived from 2 to 4 condensed rings, and a group in which two or more of these rings are connected by a direct bond.

From the viewpoint of solubility and heat resistance, Ar ^a and Ar ^b are each independently selected from the group consisting of a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a triphenylene ring, a pyrene ring, a thiophene ring, a pyridine ring, and a fluorene ring. A group derived from a selected ring or a group formed by connecting two or more benzene rings (for example, a biphenyl group or a terphenyl group) is preferable. Among these, a group derived from a benzene ring (phenyl group), a group formed by connecting two benzene rings (biphenyl group), and a group derived from a fluorene ring (fluorenyl group) are preferable.

Examples of substituents that the aromatic hydrocarbon group and aromatic heterocyclic group in Ar ^a and Ar ^b may have include an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, and a dialkyl group. Examples include an amino group, a diarylamino group, an acyl group, a halogen atom, a haloalkyl group, an alkylthio group, an arylthio group, a silyl group, a siloxy group, a cyano group, an aromatic hydrocarbon ring group, and an aromatic heterocyclic group.

As a polyarylene derivative, an arylene group such as an aromatic hydrocarbon group or an aromatic heterocyclic group, which may have a substituent as exemplified as Ar ^a or Ar ^b in the above formula (II), is used as a repeating unit. Examples include polymers having

As the polyarylene derivative, a polymer having a repeating unit represented by the following formula (III-1) and/or the following formula (III-2) is preferable.

(In formula (III-1), R ^a , R ^b , R ^c and R ^d are each independently an alkyl group, an alkoxy group, a phenylalkyl group, a phenylalkoxy group, a phenyl group, a phenoxy group, an alkylphenyl group, It represents an alkoxyphenyl group, an alkylcarbonyl group, an alkoxycarbonyl group, or a carboxy group. t and s each independently represent an integer of 0 to 3. If t or s is 2 or more, the plurality contained in one molecule R ^a or R ^b may be the same or different, and adjacent R ^a or R ^b may form a ring.)

(In formula (III-2), R ^e and R ^f are each independently synonymous with R ^a , R ^b , R ^c or R ^d in the above formula (III-1). r and u are each independently represents an integer from 0 to 3. When r or u is 2 or more, multiple R ^e and R ^f contained in one molecule may be the same or different, and adjacent R ^{e or} R ^f may form a ring with each other. X represents an atom or atomic group constituting a 5-membered ring or a 6-membered ring.)

Specific examples of X include an oxygen atom, a boron atom that may have a substituent, a nitrogen atom that may have a substituent, a silicon atom that may have a substituent, and A phosphorus atom which may have a substituent, a sulfur atom which may have a substituent, a carbon atom which may have a substituent, or a group formed by bonding these.

In addition, the polyarylene derivative may have a repeating unit represented by the following formula (III-3) in addition to the repeating unit represented by the above formula (III-1) and/or the above formula (III-2). is preferred.

(In formula (III-3), Ar ^c to Ar ⁱ each independently represent an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent. v and w each represent (Independently represents 0 or 1.)

Specific examples of Ar ^c to Ar ⁱ are the same as Ar ^a and Ar ^b in formula (II) above.

Specific examples of the above formulas (III-1) to (III-3) and polyarylene derivatives include those described in JP-A No. 2008-98619.

When forming the hole transport layer 4 by a wet film formation method, a composition for forming a hole transport layer is prepared in the same manner as in the formation of the hole injection layer 3 described above, and then heated and dried after wet film formation. .

The composition for forming a hole transport layer contains a solvent in addition to the hole transport compound described above. The solvent used is the same as that used for the hole injection layer forming composition. Further, the film forming conditions, heating drying conditions, etc. are the same as those for forming the hole injection layer 3.

When forming the hole transport layer by vacuum evaporation, the conditions for forming the film are the same as those for forming the hole injection layer 3 described above.

The hole transport layer 4 may contain various light emitting materials, electron transport compounds, binder resins, coatability improvers, etc. in addition to the above hole transport compounds.

Moreover, the hole transport layer 4 may be a layer formed by crosslinking a crosslinkable compound. The crosslinkable compound is a compound having a crosslinkable group, and forms a network polymer compound by crosslinking.

Examples of crosslinking groups include groups derived from cyclic ethers such as oxetane and epoxy; groups derived from unsaturated double bonds such as vinyl, trifluorovinyl, styryl, acrylic, methacryloyl, and cinnamoyl; Examples include groups derived from cyclobutene.

The crosslinking compound may be a monomer, oligomer, or polymer. The crosslinkable compound may contain only one type, or may contain two or more types in any combination and ratio.

As the crosslinkable compound, it is preferable to use a hole transporting compound having a crosslinkable group. Examples of hole-transporting compounds include those listed above, and examples of cross-linking compounds include compounds in which a cross-linking group is bonded to the main chain or side chain of these hole-transporting compounds. It will be done. In particular, the crosslinkable group is preferably bonded to the main chain via a linking group such as an alkylene group. In addition, especially as a hole transporting compound, a polymer containing a repeating unit having a crosslinkable group is preferable, and the crosslinkable group is present in the above formula (II) or formulas (III-1) to (III-3). is preferably a polymer having repeating units bonded directly or via a linking group.

As the crosslinkable compound, it is preferable to use a hole transporting compound having a crosslinkable group. Examples of hole-transporting compounds include nitrogen-containing aromatic compound derivatives such as pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, carbazole derivatives, phthalocyanine derivatives, and porphyrin derivatives; triphenylamine derivatives ; silole derivatives; oligothiophene derivatives; fused polycyclic aromatic derivatives; metal complexes and the like.

Among them, nitrogen-containing aromatic derivatives such as pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, and carbazole derivatives; triphenylamine derivatives; silole derivatives; fused polycyclic aromatic derivatives; metal complexes, etc. Preferably, triphenylamine derivatives are particularly preferred.

In order to form the hole transport layer 4 by crosslinking a crosslinkable compound, a composition for forming a hole transport layer is usually prepared by dissolving or dispersing the crosslinkable compound in a solvent, and the film is formed by wet film formation. to crosslink.

The composition for forming a hole transport layer may contain, in addition to the crosslinkable compound, an additive that promotes the crosslinking reaction. Examples of additives that promote crosslinking reactions include polymerization initiators and polymerization promoters such as alkylphenone compounds, acylphosphine oxide compounds, metallocene compounds, oxime ester compounds, azo compounds, and onium salts; condensed polycyclic hydrocarbons; Porphyrin compounds; photosensitizers such as diarylketone compounds, and the like.

Moreover, the composition for forming a hole transport layer may further contain a coating property improver such as a leveling agent and an antifoaming agent; an electron-accepting compound; a binder resin, and the like.

The composition for forming a hole transport layer usually contains a crosslinkable compound in an amount of 0.01% by mass or more, preferably 0.05% by mass or more, and more preferably 0.1% by mass or more. Further, the composition for forming a hole transport layer usually contains a crosslinkable compound in an amount of 50% by mass or less, preferably 20% by mass or less, and more preferably 10% by mass or less.

After forming a composition for forming a hole transport layer containing a crosslinkable compound at such a concentration on the lower layer (usually the hole injection layer 3), the crosslinkable compound is heated and/or irradiated with electromagnetic energy such as light. is crosslinked to form a network-like polymer compound.

Conditions such as temperature and humidity during film formation are the same as those during wet film formation of the hole injection layer 3. The heating method after film formation is not particularly limited. The heating temperature condition is usually 120°C or higher, preferably 400°C or lower.

The heating time is usually 1 minute or more, preferably 24 hours or less. The heating means is not particularly limited, but means such as placing the laminate having the formed layers on a hot plate or heating it in an oven can be used. For example, conditions such as heating on a hot plate at 120° C. or higher for 1 minute or longer can be used.

In the case of irradiation with electromagnetic energy such as light, irradiation can be performed by directly using an ultra-high-pressure mercury lamp, high-pressure mercury lamp, halogen lamp, infrared lamp, or other ultraviolet, visible, or infrared light source, or by using a built-in light source as described above. Examples include a method of irradiating using a mask aligner and a conveyor type light irradiation device. Examples of irradiation with electromagnetic energy other than light include a method of irradiation using a device that irradiates microwaves generated by a magnetron, a so-called microwave oven.

Although it is preferable to set the irradiation time to conditions necessary to reduce the solubility of the film, the irradiation is usually 0.1 seconds or more, preferably 10 hours or less.

Heating and irradiation with electromagnetic energy such as light may be performed alone or in combination. When combining, the order of implementation is not particularly limited.

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

[5] Light Emitting Layer A light emitting layer 5 is provided on the hole injection layer 3 or on the hole transport layer 4 when the hole transport layer 4 is provided. The light emitting layer 5 is a layer that is excited by recombination of holes injected from the anode 2 and electrons injected from the cathode 9 between the electrodes to which an electric field is applied, and becomes a main light emission source.

(Material of light emitting layer)
The light-emitting layer 5 contains, as its constituent material, at least a material having light-emitting properties (light-emitting material), and preferably a compound having hole-transporting properties (hole-transporting compound) or an electron-transporting compound. Contains a compound (electron-transporting compound) that has the following properties. A light-emitting material may be used as a dopant material, and a hole-transporting compound, an electron-transporting compound, or the like may be used as a host material.

The luminescent material is not particularly limited, and any substance that emits light at a desired wavelength and has good luminous efficiency may be used, but in the present invention, it is preferable to use the luminescent material described above. On the other hand, it is preferable to use the aromatic compound of the present invention as a host material, especially as a hole-transporting compound.

In particular, in the organic electroluminescent device of the present invention, the light-emitting layer thereof is preferably formed by a wet film forming method using the composition for an organic electroluminescent device of the present invention.

Furthermore, the light-emitting layer 5 may contain other components as long as the effects of the present invention are not significantly impaired. In addition, when forming the light-emitting layer 5 by a wet film-forming method, it is preferable to use a low molecular weight material (molecular weight: usually 10,000 or less, preferably 5,000 or less).

<Formation of light emitting layer>
When forming the light-emitting layer 5 by a wet film-forming method, the material used for the light-emitting layer is dissolved in an appropriate solvent, and a composition for forming a light-emitting layer (if the aromatic compound of the present invention is included, a composition for an organic electroluminescent device) is prepared. It is formed by preparing a material) and forming a film using it.

The emissive layer solvent to be included in the emissive layer forming composition for forming the emissive layer 5 by a wet film forming method is the solvent described above as the solvent contained in the organic electroluminescent device composition of the present invention. The same is true.

Further, the solid content concentration of the luminescent material, charge transporting compound, etc. in the composition for forming a luminescent layer is usually 0.01% by mass or more and usually 70% by mass or less. If this concentration is too high, uneven film thickness may occur, and if this concentration is too low, defects may occur in the film.

After wet film formation of the composition for forming a luminescent layer, the resulting coating film is dried and the solvent is removed to form a luminescent layer. Specifically, the method is the same as that described in the formation of the hole injection layer above. The wet film forming method is not limited as long as it does not significantly impair the effects of the present invention, and any of the methods described above can be used.

The thickness of the light-emitting layer 5 is arbitrary as long as it does not significantly impair the effects of the present invention, but is usually in the range of 3 nm or more, preferably 5 nm or more, and usually 200 nm or less, preferably 100 nm or less. If the film thickness of the light-emitting layer 5 is too thin, defects may occur in the film, and if it is too thick, the driving voltage may increase.

[6] Hole Blocking Layer In the organic electroluminescent device of the present invention, a hole blocking layer 6 is preferably provided between the light emitting layer 5 and an electron injection layer 8, which will be described later. The hole blocking layer 6 is a layer laminated on the light emitting layer 5 so as to be in contact with the interface of the light emitting layer 5 on the cathode 9 side.

This hole blocking layer 6 has the role of blocking holes moving from the anode 2 from reaching the cathode 9, and the role of efficiently transporting electrons injected from the cathode 9 toward the light emitting layer 5. has.

The physical properties required of the material constituting the hole blocking layer 6 include high electron mobility and low hole mobility, large energy gap (difference between HOMO and LUMO), and excited triplet level (T1). One example is the high level of

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

Note that the hole blocking layer 6 may be made of only one material, or two or more materials may be used in any combination and ratio.

There are no restrictions on the method of forming the hole blocking layer 6. Therefore, the hole blocking layer 6 can be formed by a wet film formation method, a vacuum evaporation method, or other methods.

The thickness of the hole blocking layer 6 is arbitrary as long as it does not significantly impair the effects of the present invention, but it is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less. be.

Further, a hole relaxing layer may be provided instead of the hole blocking layer.

[7] Electron Transport Layer An electron transport layer 7 may be provided between the light emitting layer 5 and an electron injection layer 8, which will be described later.
The electron transport layer 7 is provided for the purpose of further improving the luminous efficiency of the device, and is intended to efficiently transport electrons injected from the cathode 9 in the direction of the luminescent layer 5 between the electrodes to which an electric field is applied. It is formed by compounds that can.

The electron transporting compound used in the electron transporting layer 7 is usually one that has high electron injection efficiency from the cathode 9 or the electron injection layer 8, has high electron mobility, and efficiently transports the injected electrons. Use a compound that can. Compounds that meet these conditions include, for example, metal complexes such as aluminum complexes of 8-hydroxyquinoline (Japanese Patent Application Laid-open No. 194393/1983), metal complexes of 10-hydroxybenzo[h]quinoline, and oxadiazole derivatives. , distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (US Pat. No. 5,645,948), quinoxaline compounds ( JP-A-6-207169), phenanthroline derivative (JP-A-5-331459), 2-tert-butyl-9,10-N,N'-dicyanoanthraquinone diimine, n-type hydrogenated amorphous silicon carbide , n-type zinc sulfide, n-type zinc selenide, etc.

Note that the material for the electron transport layer 7 may be used alone or in combination of two or more in any combination and ratio.

There are no restrictions on the method for forming the electron transport layer 7. Therefore, the electron transport layer 7 can be formed by a wet film formation method, a vapor deposition method, or other methods.

The thickness of the electron transport layer 7 is arbitrary as long as it does not significantly impair the effects of the present invention, but it is usually 1 nm or more, preferably 5 nm or more, and usually 300 nm or less, preferably 100 nm or less.

[8] Electron Injection Layer The electron injection layer 8 plays a role of efficiently injecting electrons injected from the cathode 9 into the light emitting layer 5. In order to efficiently inject electrons, the material forming the electron injection layer 8 is preferably a metal with a low work function. Examples include alkali metals such as sodium and cesium, alkaline earth metals such as barium and calcium, and the like.

Examples include lithium fluoride (LiF), magnesium fluoride (MgF ₂ ), lithium oxide (Li ₂ O), cesium (II) carbonate (CsCO ₃ ), etc. (Applied Physics Letters, 1997, vol. 70, p. 152) ; JP-A-10-74586; IEEE Transactions on Electron Devices, 1997, Vol. 44, p. 1245; SID 04 Digest, p. 154, etc.).

The thickness of the electron injection layer is usually preferably 0.1 nm or more and 5 nm or less.

Furthermore, an alkali metal such as sodium, potassium, cesium, lithium, or rubidium is doped into an organic electron-transporting compound represented by a nitrogen-containing heterocyclic compound such as bathophenanthroline or a metal complex such as an aluminum complex of 8-hydroxyquinoline ( (See JP-A No. 10-270171, JP-A No. 2002-100478, JP-A No. 2002-100482, etc.) This is preferable because electron injection and transport properties can be improved and excellent film quality can be achieved at the same time. . The film thickness in this case is usually 5 nm or more, preferably 10 nm or more, and usually 200 nm or less, preferably 100 nm or less.

Note that the electron injection layer 8 may be made of only one type of material, or two or more types may be used in combination in any combination and ratio.

There are no restrictions on the method for forming the electron injection layer 8. Therefore, the electron injection layer 8 can be formed by a wet film formation method, a vapor deposition method, or other methods.

[9] Cathode The cathode 9 plays a role of injecting electrons into a layer on the light emitting layer 5 side (electron injection layer 8 or light emitting layer 5, etc.).

As the material for the cathode 9, it is possible to use the materials used for the anode 2, but in order to efficiently inject electrons, metals with a low work function are preferable, such as tin, magnesium, indium, Suitable metals such as calcium, aluminum, silver, or alloys thereof are used. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy.

Note that the cathode 9 may be made of only one type of material, or two or more types may be used in combination in any combination and ratio.

The thickness of the cathode 9 is usually the same as that of the anode 2.

Further, in order to protect the cathode 9 made of a low work function metal, it is preferable to further layer a metal layer having a high work function and being stable in the atmosphere, since this increases the stability of the device. Metals such as aluminium, silver, copper, nickel, chromium, gold, platinum are used for this purpose. Note that these materials may be used alone or in combination of two or more in any combination and ratio.

[10] Other Layers The organic electroluminescent device of the present invention may have other configurations without departing from the spirit thereof. For example, as long as the performance is not impaired, an arbitrary layer may be provided between the anode 2 and the cathode 9 in addition to the layers described above, or an arbitrary layer may be omitted. .

[11] Electron blocking layer Examples of the arbitrary layer include an electron blocking layer. The electron blocking layer is provided between the hole injection layer 3 or the hole transport layer 4 and the light emitting layer 5. The electron blocking layer prevents electrons moving from the light emitting layer 5 from reaching the hole injection layer 3, increasing the probability of recombination of holes and electrons within the light emitting layer 5, and forming It has the role of confining excitons in the light emitting layer 5 and the role of efficiently transporting holes injected from the hole injection layer 3 toward the light emitting layer 5. Particularly when a phosphorescent material or a blue luminescent material is used as the luminescent material, it is effective to provide an electron blocking layer.

Characteristics required of the electron blocking layer include high hole transportability, large energy gap (difference between HOMO and LUMO), and high excited triplet level (T1). Furthermore, when the light-emitting layer 5 is produced by a wet film-forming method, the electron blocking layer is also required to be compatible with wet film-forming. Examples of materials used for such an electron blocking layer include the aromatic compound of the present invention, a copolymer of dioctylfluorene and triphenylamine represented by F8-TFB (International Publication No. 2004/084260), etc. .

In addition, only one type of material for the electron blocking layer may be used, or two or more types may be used in combination in any combination and ratio.

There are no restrictions on the method of forming the electron blocking layer. Therefore, the electron blocking layer can be formed by a wet film formation method, a vapor deposition method, or other methods.

Furthermore, in the layered structure described above, it is also possible to laminate components other than the substrate in the reverse order. For example, in the layer configuration shown in FIG. The hole injection layer 3 and the anode 2 may be provided in this order.

Furthermore, it is also possible to construct the organic electroluminescent device of the present invention by laminating components other than the substrates between two substrates, at least one of which is transparent.

Further, it is also possible to have a structure in which a plurality of components (light-emitting units) other than the substrate are stacked (a structure in which a plurality of light-emitting units are stacked). In that case, instead of the interface layer between each stage (between the light emitting units) (if the anode is ITO and the cathode is Al, these two layers), a charge made of vanadium pentoxide (V ₂ O ₅ ), etc. Providing a carrier generation layer (CGL) reduces barriers between stages, which is more preferable from the viewpoints of luminous efficiency and driving voltage.

Furthermore, the organic electroluminescent device of the present invention may be configured as a single organic electroluminescent device, or may be applied to a configuration in which a plurality of organic electroluminescent devices are arranged in an array, with an anode and a cathode. It may also be applied to a configuration in which are arranged in an XY matrix.
Further, each layer described above may contain components other than those described as materials, as long as the effects of the present invention are not significantly impaired.

The organic electroluminescent device of the present invention is used in display devices such as organic EL displays and lighting devices such as organic EL lighting. The organic electroluminescent device of the present invention can be used, for example, by the method described in "Organic EL Display" (Ohmsha, published August 20, 2004, written by Shizushi Tokito, Chinaya Adachi, and Hideyuki Murata). Organic EL displays and organic EL lighting can be formed.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. In addition, the values of various conditions and evaluation results in the following examples have meaning as preferred values of the upper limit or lower limit in the embodiments of the present invention, and the preferred range is the value of the upper limit or lower limit described above and the following. It may be a range defined by a value of an example or a combination of values of examples.

In addition, in this specification, Me means a methyl group, Et means an ethyl group, Ac means an acetyl group, Ph means a phenyl group, and dppf means a 1,1'-bis(diphenylphosphor group). fino) ferrocene, DMSO means dimethylsulfoxide, DME means 1,2-dimethoxyethane, DCM means dichloromethane, Tf means trifluoromethylsulfonyl group (CF ₃ SO ₂ -) do.

<Example 1: Synthesis example of compound 1>
(Synthesis of intermediate 1)

Dibenzofuran-4-boronic acid (10.4 g, 49.1 mmol), 1-bromo-3-iodobenzene (13.9 g, 49.1 mmol) were mixed with toluene (100 mL), ethanol (61 mL), and phosphorus. Tripotassium acid aqueous solution (2.0 mol/L, 61 mL) was sequentially added and heated to 55°C. Then, PdCl ₂ (PPh ₃ ) ₂ (0.34 g, 0.49 mmol) was added and stirred at 65° C. for 5 hours. After cooling to room temperature, a saturated aqueous sodium chloride solution was added, and extraction was performed using toluene. The organic layer was washed with a saturated aqueous sodium chloride solution, dried over magnesium sulfate, and then the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain Intermediate 1 (yield: 12.4 g, yield: 78%).

(Synthesis of intermediate 2)

Dehydrated DMSO (100 mL) was added to Intermediate 1 (12.4 g, 38.4 mmol), bis(pinacolatodiboron) (14.6 g, 57.6 mmol), and potassium acetate (11.3 g, 115.2 mmol), Heated to 50°C. PdCl ₂ (dppf)CH ₂ Cl ₂ (3.14 g, 3.84 mmol) was added and stirred at 90° C. for 4 hours. After cooling to room temperature, distilled water was added and suction filtration was performed. The filtered material was dissolved in dichloromethane, washed with a saturated aqueous sodium chloride solution, dried over magnesium sulfate, and then the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain Intermediate 2 (yield: 14.0 g, yield: 99%).

(Synthesis of intermediate 3)

Intermediate 2 (14.0 g, 37.8 mmol), 1-bromo-4-iodobenzene (10.7 g, 37.8 mmol) with nitrogen bubbled toluene (100 mL), ethanol (47 mL), tripotassium phosphate Aqueous solutions (2.0 mol/L, 47 mL) were sequentially added and heated to 55°C. Then, PdCl ₂ (PPh ₃ ) ₂ (0.26 g, 0.37 mmol) was added and stirred at 65° C. for 6 hours. After cooling to room temperature, a saturated aqueous sodium chloride solution was added, and extraction was performed using toluene. The organic layer was washed with a saturated aqueous sodium chloride solution, dried over magnesium sulfate, and then the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain Intermediate 3 (9.90 g, 66% yield).

(Synthesis of intermediate 4)

3-terphenylboronic acid (10.1 g, 37.0 mmol), 1-bromo-4-iodobenzene (10.5 g, 37.0 mmol), toluene (100 mL) with nitrogen bubbled, ethanol (46 mL), phosphorus. Tripotassium acid aqueous solution (2.0 mol/L, 46 mL) was sequentially added and heated to 55°C. Then, PdCl ₂ (PPh ₃ ) ₂ (0.26 g, 0.37 mmol) was added and stirred at 65° C. for 3 hours. After cooling to room temperature, a saturated aqueous sodium chloride solution was added, and extraction was performed using toluene. The organic layer was washed with a saturated aqueous sodium chloride solution, dried over magnesium sulfate, and then the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain Intermediate 4 (yield: 12.7 g, yield: 89%).

(Synthesis of intermediate 5)

Dehydrated DMSO (100 mL) was added to Intermediate 4 (10.4 g, 27.0 mmol), bis(pinacolatodiboron) (10.3 g, 40.5 mmol), and potassium acetate (7.95 g, 81.0 mmol), Heated to 50°C. PdCl ₂ (dppf)CH ₂ Cl ₂ (1.10 g, 1.35 mmol) was added and stirred at 90° C. for 8 hours. After cooling to room temperature, distilled water was added and suction filtration was performed. The filtered material was dissolved in dichloromethane, washed with a saturated aqueous sodium chloride solution, dried over magnesium sulfate, and then the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain Intermediate 5 (yield: 10.7 g, yield: 92%).

(Synthesis of intermediate 6)

Dimethoxyethane (60 mL) with nitrogen bubbling was added to 1-bromo-2-dibenzofuranol (2.30 g, 8.74 mmol) and Intermediate 5 (3.78 g, 8.74 mmol), and the mixture was heated to 55°C. Potassium carbonate aqueous solution (2.0 mol/L, 15 mL) and Pd(PPh ₃ ) ₄ (0.10 g, 0.087 mmol) were added in this order, and the mixture was stirred at 90° C. for 6 hours. After cooling to room temperature, distilled water was added and extraction was performed using ethyl acetate. The organic layer was washed with a saturated aqueous sodium chloride solution, dried over magnesium sulfate, and then the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain Intermediate 6 (4.10 g, 96% yield).

(Synthesis of intermediate 7)

Dichloromethane (100 mL) with nitrogen bubbling and triethylamine (2.9 mL, 21.0 mmol) were added to Intermediate 6 (4.10 g, 8.39 mmol), and the mixture was cooled to -5°C to -10°C. Trifluoromethanesulfonic anhydride (1.8 mL, 12.6 mmol) diluted in dichloromethane (20 mL) was added dropwise, and the mixture was stirred at -5°C to -10°C for 3 hours, and further stirred at room temperature for 1 hour. Distilled water was added and extraction was performed using dichloromethane. The organic layer was washed with a saturated aqueous sodium chloride solution, dried over magnesium sulfate, and then the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain Intermediate 7 (4.90 g, 94% yield).

(Synthesis of intermediate 8)

Dehydrated DMSO (100 mL) was added to Intermediate 7 (4.90 g, 7.89 mmol), bis(pinacolatodiboron) (3.00 g, 11.8 mmol), and potassium acetate (2.32 g, 23.6 mmol), Heated to 50°C. PdCl ₂ (dppf)CH ₂ Cl ₂ (0.64 g, 0.79 mmol) was added and stirred at 90° C. for 13 hours. After cooling to room temperature, distilled water was added and suction filtration was performed. The filtered material was dissolved in dichloromethane, washed with a saturated aqueous sodium chloride solution, dried over magnesium sulfate, and then the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain Intermediate 8 (0.94 g, 20% yield).

(Synthesis of compound 1)

Intermediate 8 (0.94 g, 1.57 mmol), Intermediate 3 (0.69 g, 1.73 mmol) were mixed with toluene (6 mL), ethanol (2.0 mL), and tripotassium phosphate aqueous solution (2 0 mol/L, 2.0 mL) were added in this order and heated to 55°C. Then, Pd(PPh ₃ ) ₄ (15 mg, 0.013 mmol) was added and stirred at 90° C. for 7 hours. After cooling to room temperature, a saturated aqueous sodium chloride solution was added, and extraction was performed using toluene. The organic layer was washed with a saturated aqueous sodium chloride solution, dried over magnesium sulfate, and then the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain Compound 1 (0.98 g, 79% yield).

<Example 2: Synthesis example of compound 2>
(Synthesis of intermediate 9)

3-terphenylboronic acid (8.02 g, 29.3 mmol), 3-bromo-3'-iodo-1,1'-biphenyl (10.5 g, 29.3 mmol) in toluene (100 mL) with nitrogen bubbling. , ethanol (37 mL), and tripotassium phosphate aqueous solution (2.0 mol/L, 37 mL) were added in this order, and the mixture was heated to 60°C. Then, PdCl ₂ (PPh ₃ ) ₂ (0.20 g, 0.29 mmol) was added and stirred at 65° C. for 6 hours. After cooling to room temperature, a saturated aqueous sodium chloride solution was added, and extraction was performed using toluene. The organic layer was washed with a saturated aqueous sodium chloride solution, dried over magnesium sulfate, and then the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain Intermediate 9 (11.1 g, 82% yield).

(Synthesis of intermediate 10)

Dehydrated DMSO (100 mL) was added to Intermediate 9 (5.00 g, 10.8 mmol), bis(pinacolatodiboron) (4.14 g, 16.3 mmol), and potassium acetate (3.19 g, 32.5 mmol), Heated to 50°C. PdCl ₂ (dppf)CH ₂ Cl ₂ (0.88 g, 1.08 mmol) was added and stirred at 90° C. for 5 hours. After cooling to room temperature, distilled water was added and suction filtration was performed. The filtered material was dissolved in dichloromethane, washed with a saturated aqueous sodium chloride solution, dried over magnesium sulfate, and then the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain Intermediate 10 (5.16 g, 94% yield).

(Synthesis of intermediate 11)

Dimethoxyethane (40 mL) with nitrogen bubbling was added to 1-bromo-2-dibenzofuranol (1.10 g, 4.18 mmol) and Intermediate 10 (2.13 g, 4.18 mmol), and the mixture was heated to 55°C. Potassium carbonate aqueous solution (2.0 mol/L, 7.3 mL) and Pd(PPh ₃ ) ₄ (48 mg, 0.042 mmol) were added in this order, and the mixture was stirred at 90° C. for 4 hours. After cooling to room temperature, distilled water was added and extraction was performed using ethyl acetate. The organic layer was washed with a saturated aqueous sodium chloride solution, dried over magnesium sulfate, and then the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain Intermediate 11 (2.28 g, 97% yield).

(Synthesis of intermediate 12)

Dichloromethane (60 mL) with nitrogen bubbling and triethylamine (1.4 mL, 10.1 mmol) were added to Intermediate 11 (2.28 g, 4.04 mmol), and the mixture was cooled to -5°C to -10°C. Trifluoromethanesulfonic anhydride (0.90 mL, 6.06 mmol) diluted in dichloromethane (20 mL) was added dropwise, and the mixture was stirred at -5°C to -10°C for 3 hours, and further stirred at room temperature for 1 hour. Distilled water was added and extraction was performed using dichloromethane. The organic layer was washed with a saturated aqueous sodium chloride solution, dried over magnesium sulfate, and then the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain Intermediate 12 (2.63 g, 94% yield).

(Synthesis of intermediate 13)

Dehydrated DMSO (35 mL) was added to Intermediate 12 (2.63 g, 3.77 mmol), bis(pinacolatodiboron) (1.44 g, 5.66 mmol), and potassium acetate (1.11 g, 11.3 mmol), Heated to 50°C. PdCl ₂ (dppf)CH ₂ Cl ₂ (0.15 g, 0.19 mmol) was added and stirred at 90° C. for 10 hours. After cooling to room temperature, distilled water was added and suction filtration was performed. The filtered material was dissolved in dichloromethane, washed with a saturated aqueous sodium chloride solution, dried over magnesium sulfate, and then the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain Intermediate 13 (1.59 g, 63% yield).

(Synthesis of compound 2)

Intermediate 13 (1.59 g, 2.36 mmol), Intermediate 3 (1.04 g, 2.59 mmol) were mixed with toluene (12 mL), ethanol (3.0 mL), and tripotassium phosphate aqueous solution (2 0 mol/L, 3.0 mL) were added in this order and heated to 50°C. Then, Pd(PPh ₃ ) ₄ (27 mg, 0.024 mmol) was added and stirred at 90° C. for 10 hours. After cooling to room temperature, a saturated aqueous sodium chloride solution was added, and extraction was performed using toluene. The organic layer was washed with a saturated aqueous sodium chloride solution, dried over magnesium sulfate, and then the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain Compound 2 (1.55 g, 76% yield).

<Evaluation of Compound 1 and Compound 2>
The glass transition temperature (Tg) of Compound 1 and Compound 2 was evaluated by differential scanning calorimetry (DSC). The Tg of Compound 1 and Compound 2 was 125.4°C and 127.2°C, respectively.

1. Substrate 2. Anode 3. Hole injection layer 4. Hole transport layer 5. Luminescent layer 6. Hole blocking layer7. Electron transport layer 8. Electron injection layer 9. Cathode 10. organic electroluminescent device

Claims (10)

An aromatic compound represented by the following general formula (1).

In formula (1), R ¹ is represented by the following general formula (3), R ² is represented by the following general formula (2) , and a is 0 .

In formula (2), the asterisk (*) represents a bond with formula (1), Ar ¹ is a divalent aromatic hydrocarbon group having 20 or less carbon atoms, and n is an integer of 1 or more.

In formula (3), the asterisk (*) represents a bond with formula (1), ^Ar2 is a divalent aromatic hydrocarbon group having 20 or less carbon atoms, and ^Ar3 is a monovalent aromatic hydrocarbon group having 20 or less carbon atoms. They are the following aromatic hydrocarbon groups, and m is an integer of 1 or more. An organic electroluminescent element having an anode and a cathode on a substrate, and an organic layer between the anode and the cathode,
An organic electroluminescent device, wherein the organic layer has a layer containing an organic electroluminescent device material, and the organic electroluminescent device material is the aromatic compound according to claim 1. The organic electroluminescent device according to claim 2, wherein the layer containing the organic electroluminescent device material is a light emitting layer. A display device comprising the organic electroluminescent element according to claim 2 or 3. A lighting device comprising the organic electroluminescent element according to claim 2 or 3. A composition comprising the aromatic compound according to claim 1 and a solvent. 7. The composition of claim 6, further comprising a phosphorescent material and a host material. A thin film forming method comprising the step of forming a film from the composition according to claim 6 or 7 by a wet film forming method. A method for manufacturing an organic electroluminescent device having an anode and a cathode on a substrate, and an organic layer between the anode and the cathode, the method comprising:
A method for manufacturing an organic electroluminescent device, comprising the step of forming the organic layer by a wet film forming method using the composition according to claim 6 or 7. The method for manufacturing an organic electroluminescent device according to claim 9, wherein the organic layer is a light emitting layer.

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