WO2014013721A1

WO2014013721A1 - Nitrogen-containing heteroaromatic ring compound and organic electroluminescence element using same

Info

Publication number: WO2014013721A1
Application number: PCT/JP2013/004339
Authority: WO
Inventors: 圭吉田; 裕基中野; 英明長島; 亮平橋本
Original assignee: 出光興産株式会社
Priority date: 2012-07-20
Filing date: 2013-07-16
Publication date: 2014-01-23
Also published as: TW201412731A

Abstract

A nitrogen-containing heteroaromatic ring compound represented by formula (1).

Description

Nitrogen-containing heteroaromatic ring compound and organic electroluminescence device using the same

The present invention relates to a nitrogen-containing heteroaromatic ring compound and an organic electroluminescence device using the same.

Organic electroluminescence (EL) elements include a fluorescent type and a phosphorescent type, and an optimum element design has been studied according to each light emission mechanism. With respect to phosphorescent organic EL elements, it is known from their light emission characteristics that high-performance elements cannot be obtained by simple diversion of fluorescent element technology.
Since phosphorescence emission is emission using triplet excitons, the energy gap of the compound used for the light emitting layer must be large. This is because the value of the energy gap (hereinafter also referred to as singlet energy) of a compound usually refers to the triplet energy of the compound (in the present invention, the energy difference between the lowest excited triplet state and the ground state). This is because it is larger than the value of).
As materials for such phosphorescent organic EL elements, compounds having a structure in which a plurality of heterocycles are bonded have been studied (see Patent Documents 1 to 6).

International Publication No. WO2008-156105 International Publication No. WO2007-77810 International Publication No. WO2008-140114 International Publication No. WO2008-146838 JP 2007-180147 A International Publication No. WO2011-19156

In the case of a phosphorescent organic EL element that emits blue light, it is necessary to use a compound having a large triplet energy in the light emitting layer and its peripheral layer as compared with a phosphorescent organic EL element that emits green to red light. Specifically, in order to obtain blue phosphorescence, it is ideal that the triplet energy of the host material used for the light emitting layer is 3.0 eV or more. In order to obtain such a material, a molecular design based on a new concept different from materials for fluorescent elements and materials used for phosphorescent elements emitting green to red light is necessary.

The inventors of the present invention have a structure including a nitrogen-containing heteroaromatic ring excellent in carrier injection property and having at least four heterocycles bonded thereto, and at least two of the heterocycles are nitrogen-containing heteroaromatic rings and Thus, the present inventors have found a material that can suppress deterioration of the material by introducing an appropriate substituent while maintaining high triplet energy.
According to the present invention, the following nitrogen-containing heteroaromatic ring compounds and the like are provided.
1. A nitrogen-containing heteroaromatic ring compound represented by the following formula (1).

[In Formula (1),
X represents an oxygen atom or a sulfur atom,
Y ₁₁ to Y ₁₈ , Y ₂₁ to Y ₂₈ and Y ₃₁ to Y ₃₈ each represent CR ₁ or a nitrogen atom;
R ₁ is a single bond, a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, a substituted or unsubstituted carbon atom having 1 to 20 alkoxy groups, substituted or unsubstituted cycloalkoxy groups having 3 to 20 ring carbon atoms, substituted or unsubstituted aromatic hydrocarbon rings having 6 to 18 ring carbon atoms, substituted or unsubstituted ring carbon atoms 6-18 aryloxy group, substituted or unsubstituted heteroaromatic ring having 5 to 18 ring atoms, substituted or unsubstituted amino group, fluorine atom, substituted or unsubstituted fluoroalkyl having 1 to 20 carbon atoms group, a substituted or unsubstituted fluoroalkoxy group having 1 to 20 carbon atoms, or a cyano group, when a plurality of CR ₁ is present, R ₁ is each the same or different Well,
A ₂ and A ₃ are each a single bond, an oxygen atom, a sulfur atom, or a group represented by the following formulas (a) to (e):

R ₂ to R ₆ are each a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, or a substituted or unsubstituted carbon number. 1-20 alkoxy group, substituted or unsubstituted cycloalkoxy group having 3-20 carbon atoms, substituted or unsubstituted aromatic hydrocarbon ring having 6-18 carbon atoms, substituted or unsubstituted ring formation Aryloxy group having 6 to 18 carbon atoms, substituted or unsubstituted heteroaromatic ring having 5 to 18 ring atoms, substituted or unsubstituted amino group, fluorine atom, substituted or unsubstituted carbon atoms having 1 to 20 carbon atoms Represents a fluoroalkyl group, a substituted or unsubstituted fluoroalkoxy group having 1 to 20 carbon atoms, or a cyano group;
HAr represents a substituted or unsubstituted monocyclic or condensed nitrogen-containing aromatic ring having 5 to 18 ring atoms, a dibenzofuran ring having a substituent, or a substituted or unsubstituted dibenzothiophene ring. ]

By using the nitrogen-containing heteroaromatic ring compound of the present invention for the light emitting layer, a low voltage phosphorescent organic EL device can be obtained. Further, by using the compound of the present invention as a material for the electron transport layer, a highly efficient and long-lived phosphorescent organic EL device can be obtained.

It is the schematic which shows the layer structure of one Embodiment of the organic EL element of this invention.

The nitrogen-containing heteroaromatic ring compound of the present invention is a compound represented by the following formula (1).

The nitrogen-containing heteroaromatic ring compound represented by the formula (1) has a structure in which at least four heterocycles are bonded, and two or more of the heterocycles are nitrogen-containing heteroaromatic rings. Both the nitrogen-containing heteroaromatic ring represented by the formula (1) and the central condensed heterocycle have high triplet energy, and by connecting them with an appropriate bond, a structure suitable for phosphorescence emission is obtained. .

In the formula (1), X represents an oxygen atom or a sulfur atom. X is preferably an oxygen atom.
Y ₁₁ to Y ₁₈ , Y ₂₁ to Y ₂₈ and Y ₃₁ to Y ₃₈ each represent CR ₁ or a nitrogen atom.

R ₁ is a single bond, a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, a substituted or unsubstituted carbon atom having 1 to 20 alkoxy groups, substituted or unsubstituted cycloalkoxy groups having 3 to 20 ring carbon atoms, substituted or unsubstituted aromatic hydrocarbon rings having 6 to 18 ring carbon atoms, substituted or unsubstituted ring carbon atoms 6-18 aryloxy group, substituted or unsubstituted heteroaromatic ring having 5 to 18 ring atoms, substituted or unsubstituted amino group, fluorine atom, substituted or unsubstituted fluoroalkyl having 1 to 20 carbon atoms Represents a group or a cyano group.

One of Y ₁₁ to Y ₁₄ has a single bond R ₁ and is bonded to the nitrogen atom of the nitrogen-containing heteroaromatic ring. Similarly, one of Y ₁₅ to Y ₁₈ and one of Y ₃₁ to Y ₃₄ have a single bond that is bonded to each other.
When a plurality of CR ₁ are present, each R ₁ may be the same or different.

A ₂ and A ₃ are each a single bond, an oxygen atom, a sulfur atom, or a group represented by any of the following formulas (a) to (e).

R ₂ to R ₆ are each a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, or a substituted or unsubstituted carbon number. 1-20 alkoxy group, substituted or unsubstituted cycloalkoxy group having 3-20 carbon atoms, substituted or unsubstituted aromatic hydrocarbon ring having 6-18 carbon atoms, substituted or unsubstituted ring formation Aryloxy group having 6 to 18 carbon atoms, substituted or unsubstituted heteroaromatic ring having 5 to 18 ring atoms, substituted or unsubstituted amino group, fluorine atom, substituted or unsubstituted carbon atoms having 1 to 20 carbon atoms It represents a fluoroalkyl group, a substituted or unsubstituted fluoroalkoxy group having 1 to 20 carbon atoms, or a cyano group.
A ₂ and A ₃ are preferably both single bonds.

HAr represents a substituted or unsubstituted monocyclic or condensed nitrogen-containing aromatic ring having 5 to 18 ring atoms, a dibenzofuran ring having a substituent, or a substituted or unsubstituted dibenzothiophene ring. Specifically, a nitrogen-containing heteroaromatic ring represented by the following formula (A-1) and a heteroaromatic ring represented by the following formula (A-2) are preferable.

In formula (A-1), Y _1a to Y _1e each represents CR _1a or a nitrogen atom. At least one of Y _1a to Y _1e is a nitrogen atom.
R _1a is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms. Group, substituted or unsubstituted cycloalkoxy group having 3 to 20 ring carbon atoms, substituted or unsubstituted aromatic hydrocarbon ring having 6 to 18 ring carbon atoms, substituted or unsubstituted ring carbon atoms having 6 to 18 carbon atoms Aryloxy group, substituted or unsubstituted heteroaromatic ring having 5 to 18 ring atoms, substituted or unsubstituted amino group, fluorine atom, substituted or unsubstituted fluoroalkyl group having 1 to 20 carbon atoms, substituted Or an unsubstituted fluoroalkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted diarylphosphino group having 12 to 30 carbon atoms, a substituted or unsubstituted carbon number 12 Represents a diarylphosphine oxide group having ˜30, a substituted or unsubstituted diarylphosphinoaryl group having 18 to 30 carbon atoms, or a cyano group. When a plurality of CR _1a are present, each R _1a may be the same or different.

Examples of the nitrogen-containing heteroaromatic ring represented by the above formula (A-1) include the following structures.

The nitrogen-containing heteroaromatic ring represented by the above formula (A-1) is preferably (a), (b), (c), (e), (g) or (j), and (a) or (b ) Is more preferable.

In formula (A-2), Y _2a to Y _2i each represent CR _2a or a nitrogen atom.
X ₂ represents an oxygen atom, a sulfur atom or —NR _2b .
R _2a is a single bond, a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, a substituted or unsubstituted carbon number of 1 to 20 alkoxy groups, substituted or unsubstituted cycloalkoxy groups having 3 to 20 ring carbon atoms, substituted or unsubstituted aromatic hydrocarbon rings having 6 to 18 ring carbon atoms, substituted or unsubstituted ring carbon atoms 6-18 aryloxy group, substituted or unsubstituted heteroaromatic ring having 5 to 18 ring atoms, substituted or unsubstituted amino group, fluorine atom, substituted or unsubstituted fluoroalkyl having 1 to 20 carbon atoms Group, substituted or unsubstituted fluoroalkoxy group having 1 to 20 carbon atoms, substituted or unsubstituted diarylphosphino group having 12 to 30 carbon atoms, substituted or unsubstituted carbon Represents a diarylphosphine oxide group having a prime number of 12 to 30, a substituted or unsubstituted diarylphosphinoaryl group having a carbon number of 18 to 30, or a cyano group, and when a plurality of CR _2a are present, each R _2a is the same or different. May be.
When X ₂ represents an oxygen atom and R _2a all represents a single bond or a hydrogen atom, at least one of Y _2a to Y _2i represents a nitrogen atom.
R _2b represents a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, or a substituted or unsubstituted aromatic group having 6 to 18 ring carbon atoms. It represents a hydrocarbon ring or a substituted or unsubstituted heteroaromatic ring having 5 to 18 ring atoms.

In formula (A-2), Y _2g is preferably CR _2a , in which case R _2a is a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 18 ring carbon atoms, a substituted or unsubstituted ring A aryloxy group having 6 to 18 ring carbon atoms, a substituted or unsubstituted heteroaromatic ring having 5 to 18 ring atoms, or a cyano group is preferable.
In Formula (A-2), at least one of Y _2a to Y _2i is preferably a nitrogen atom.

Of the nitrogen-containing heteroaromatic ring compounds represented by the formula (1), a nitrogen-containing heteroaromatic ring compound represented by the following formula (2) is preferable.

[In the formula (2), X, Y ₁₁ , Y ₁₃ to Y ₁₈ , Y ₂₁ to Y ₂₈ , Y ₃₁ to Y ₃₈ and HAr are the same as in the formula (1). ]

The compound of the formula (2) corresponds to the compound in which R ₁ of Y _{12 in} the formula (1) is a single bond, and the nitrogen bond of the nitrogen-containing heteroaromatic ring and the heterocycle having an X atom are bonded by this single bond. is doing. By having such a structure, high triplet energy can be maintained, which is suitable as a host material for a phosphorescent light-emitting element.

Among the compounds of formula (2), those represented by any of the following formulas (3) to (6) are preferred.

[Wherein, X, Y ₁₁ , Y ₁₃ to Y ₁₈ , Y ₂₁ to Y ₂₈ , Y ₃₁ to Y ₃₈ , and HAr are the same as those in formula (1). ]

Among the above compounds, the compound represented by the formula (3) has a high triplet energy and is relatively easy to synthesize.

Hereinafter, examples of the groups of the above formulas (1) to (6) will be described.
In this specification, the aromatic hydrocarbon ring includes a monocyclic aromatic hydrocarbon ring group and a condensed aromatic hydrocarbon ring group in which a plurality of hydrocarbon rings are condensed, and the heteroaromatic ring is a monocyclic heterocycle. An aromatic ring group, a hetero-fused aromatic ring group in which a plurality of heteroaromatic rings are condensed, and a hetero-fused aromatic ring group in which an aromatic hydrocarbon ring and a heteroaromatic ring are condensed are included.

In the present invention, “unsubstituted” in “substituted or unsubstituted...” Means that a hydrogen atom is bonded. The hydrogen atom includes isotopes having different numbers of neutrons, that is, light hydrogen (protium), deuterium (deuterium), and tritium.

Specific examples of the alkyl group having 1 to 20 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, s-butyl group, isobutyl group, t-butyl group, n-pentyl group, n -Hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n -Hexadecyl group, n-heptadecyl group, n-octadecyl group, neopentyl group, 1-methylpentyl group, 2-methylpentyl group, 1-pentylhexyl group, 1-butylpentyl group, 1-heptyloctyl group, 3-methyl Examples thereof include a pentyl group, and among these, those having 1 to 6 carbon atoms are preferred.

Specific examples of the cycloalkyl group having 3 to 20 ring carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a norbornyl group, an adamantyl group, and the like. Those of 5 or 6 are preferred.
The “ring-forming carbon” means a carbon atom constituting a saturated ring, an unsaturated ring, or an aromatic ring.

Examples of the alkoxy group having 1 to 20 carbon atoms include methoxy group, ethoxy group, propoxy group, butoxy group, pentyloxy group, hexyloxy group and the like, and those having 3 or more carbon atoms are linear, cyclic or branched Among them, those having 1 to 6 carbon atoms are preferable.

Examples of the cycloalkoxy group having 3 to 20 ring carbon atoms include cyclopentoxy group, cyclohexyloxy group, etc. Among them, those having 5 or 6 ring carbon atoms are preferable.

Specific examples of the aromatic hydrocarbon ring (aryl group) having 6 to 18 ring carbon atoms include phenyl group, tolyl group, xylyl group, mesityl group, o-biphenyl group, m-biphenyl group, p-biphenyl group, Examples thereof include o-terphenyl group, m-terphenyl group, p-terphenyl group, naphthyl group, phenanthryl group, triphenylene group and the like. Of these, a phenyl group, m-biphenyl group, and m-terphenyl group are preferred.

Examples of the aryloxy group having 6 to 18 ring carbon atoms include a phenoxy group and a biphenyloxy group, and a phenoxy group is preferable.

Specific examples of the heteroaromatic ring having 5 to 18 ring atoms (heteroaryl group) include pyrrolyl group, pyrazinyl group, pyridinyl group, pyrimidinyl group, pyridazinyl group, triazinyl group, indolyl group, isoindolyl group, furyl group, Benzofuranyl group, isobenzofuranyl group, dibenzofuranyl group, dibenzothiophenyl group, quinolyl group, isoquinolyl group, quinoxalinyl group, carbazolyl group, azacarbazolyl group, phenanthridinyl group, acridinyl group, phenanthrolinyl group, thienyl Group, pyrrolidinyl group, dioxanyl group, piperidinyl group, morpholinyl group, piperazinyl group, carbazolyl group, thiophenyl group, oxazolyl group, oxadiazolyl group, benzoxazolyl group, thiazolyl group, thiadiazolyl group, benzothiazolyl group, Riazoriru group, an imidazolyl group, benzimidazolyl group, pyranyl group, benzo [c] dibenzofuranyl group, and the like, are preferred for these ring atoms 6 to 14.
The “ring-forming atom” means an atom constituting a saturated ring, an unsaturated ring, or an aromatic ring.

The substituted amino group is represented by —N (R ^a ) (R ^b ), and examples of (R ^a ) and (R ^b ) include the alkyl group, aryl group, and heteroaryl group described above. Specific examples include a dimethylamino group, a diphenylamino group, a dibiphenylamino group, a phenyl dibenzofuranylamino group, a dibenzofuranylbiphenylamino group, and a di (N-phenyl) carbazolylamino group.

Examples of the fluoroalkyl group having 1 to 20 carbon atoms include groups in which one or more fluorine atoms are substituted on the above alkyl group having 1 to 20 carbon atoms. Specific examples include a trifluoromethyl group, pentafluoroethyl group, and the like. Group, 2,2,2-trifluoroethyl group and the like are preferable.
Examples of the fluoroalkoxy group having 1 to 20 carbon atoms include groups in which one or more fluorine atoms are substituted on the above-described alkoxy group having 1 to 20 carbon atoms. Specific examples include trifluoromethoxy groups, pentafluoroethoxy groups. Group, 2,2,2-trifluoroethoxy group and the like are preferable.

Examples of the diarylphosphino group having 12 to 30 carbon atoms include groups in which the above-described aromatic hydrocarbon ring (aryl group) is substituted on the phosphino group, and specifically, a diphenylphosphino group and the like are preferable.
Examples of the diarylphosphine oxide group having 12 to 30 carbon atoms include groups in which the above-described aromatic hydrocarbon ring (aryl group) is substituted on the phosphine oxide group. Specifically, a diphenylphosphine oxide group and the like are preferable.
Examples of the diarylphosphinoaryl group having 18 to 30 carbon atoms include groups in which the above-described aromatic hydrocarbon ring (aryl group) is substituted on the phosphino group of the phosphinoaryl group, specifically, diphenylphosphinophenyl. Groups and the like are preferred.

In the compound represented by the formula (1), the substituents of “substituted or unsubstituted...” Of each group include the above alkyl group, aryl group, heteroaryl group, alkoxy group, fluoroalkyl group, fluoro Alkoxy groups and other halogen atoms (fluorine, chlorine, bromine, iodine are mentioned, preferably fluorine atoms), silyl groups, hydroxyl groups, nitro groups, cyano groups, carboxy groups, aryloxy groups, aralkyl groups , Diarylphosphino group, diarylphosphine oxide group, diarylphosphinoaryl group and the like.

HAR substituents (R _1a , R _2a , R _2b ) include phenyl groups, biphenyl groups, aryl groups such as terphenyl groups, carbazole groups, dibenzofuran groups, dibenzothiophene groups, heteroaryl groups such as azacarbazole groups, A diarylphosphino group (such as a diphenylphosphino group), a diarylphosphine oxide group (such as a diphenylphosphine oxide group), and a diarylphosphinoaryl group (such as a diphenylphosphinophenyl group) are preferable.
These substituents may further have a substituent such as a cyano group, an aryl group, or a heteroaryl group.

As the substituent of the dibenzofuran ring having a substituent and the substituent (R _2a ) of the dibenzothiophene ring represented by HAr, a heteroaryl group such as a cyano group, a carbazole group, an azacarbazole group, a diarylphosphino group (diphenylphosphino group) And a diarylphosphine oxide group (such as a diphenylphosphine oxide group) and a diarylphosphinoaryl group (such as a diphenylphosphinophenyl group) are preferred.
These substituents may further have a substituent such as a cyano group, an aryl group, or a heteroaryl group.
Specific examples of the compound represented by the above formula (1) are shown below.

The synthesis of the compound represented by the formula (1) is carried out by using the conditions described in International Publication Nos. WO2009-008100 and International Publication No. 2011-132684, and a carbazole derivative and a halogenated aromatic compound in accordance with Tetrahedron 1435-1456. Page (1984) or the copper catalyst described in J. Am. Chem. Soc. It can be carried out by referring to the production conditions for the reaction using the palladium catalyst described on pages 7727-7729 (2001).

The material for an organic EL device of the present invention (hereinafter sometimes referred to as the material of the present invention) includes the above-described compound of the present invention.
The material for an organic EL device of the present invention can be suitably used as a material for an organic thin film layer constituting the organic EL device.

Next, the organic EL element of the present invention will be described.
The organic EL device of the present invention has one or more organic thin film layers including a light emitting layer between an anode and a cathode. And at least one layer of an organic thin film layer contains the organic EL element material of this invention.
In the organic EL device of the present invention, the light emitting layer preferably contains the material for an organic EL device of the present invention, and more preferably contains it as a host material in the light emitting layer.
The light emitting layer preferably contains a phosphorescent material, and the phosphorescent material is an ortho metalated complex of metal atoms selected from iridium (Ir), osmium (Os) and platinum (Pt).
Moreover, in the organic EL element of this invention, it has an organic thin film layer in the electron transport zone between a cathode and a light emitting layer, and it is preferable that this organic thin film layer contains the organic EL element material of this invention. Examples of the organic thin film layer in the electron transport zone include an electron injection layer, an electron transport layer, and a hole blocking layer.

FIG. 1 is a schematic view showing a layer structure of an embodiment of the organic EL device of the present invention.
The organic EL element 1 has a configuration in which an anode 20, a hole transport zone 30, a phosphorescent light emitting layer 40, an electron transport zone 50, and a cathode 60 are laminated on a substrate 10 in this order. The hole transport zone 30 means a hole transport layer, a hole injection layer, an electron blocking layer, or the like. Similarly, the electron transport zone 50 means an electron transport layer, an electron injection layer, a hole blocking layer, or the like. These need not be formed, but preferably one or more layers are formed. In this element, the organic thin film layer is each organic layer provided in the hole transport zone 30, each phosphor layer and the organic layer provided in the electron transport zone 50. Among these organic thin film layers, at least one layer contains the organic EL element material of the present invention. Thereby, the drive voltage of an organic EL element can be lowered.
The content of this material with respect to the organic thin film layer containing the organic EL device material of the present invention is preferably 1 to 100% by weight.

In the organic EL device of the present invention, the phosphorescent light emitting layer 40 preferably contains the organic EL device material of the present invention, and more preferably used as a host material of the light emitting layer. Since the triplet energy of the material of the present invention is sufficiently large, even when a blue phosphorescent dopant material is used, the triplet energy of the phosphorescent dopant material can be efficiently confined in the light emitting layer. . The light emitting layer can be used not only for the blue light emitting layer but also for light emitting layers of longer wavelengths (such as green to red), but is preferably used for the blue light emitting layer.

The phosphorescent light emitting layer contains a phosphorescent material (phosphorescent dopant). Examples of the phosphorescent dopant include metal complex compounds, preferably a compound having a metal atom selected from Ir, Pt, Os, Au, Cu, Re and Ru and a ligand. The ligand preferably has an ortho metal bond.
The phosphorescent dopant is preferably a compound containing a metal atom selected from Ir, Os and Pt in that the phosphorescent quantum yield is high and the external quantum efficiency of the light-emitting element can be further improved, and an iridium complex, It is more preferable that it is a metal complex such as an osmium complex and a platinum complex, among which an iridium complex and a platinum complex are more preferable, and an orthometalated iridium complex is most preferable. The dopant may be a single type or a mixture of two or more types.

The addition concentration of the phosphorescent dopant in the phosphorescent light emitting layer is not particularly limited, but is preferably 0.1 to 40% by weight (wt%), more preferably 0.1 to 30% by weight (wt%).

It is also preferable to use the material of the present invention for the organic thin film layer adjacent to the phosphorescent light emitting layer 40. For example, when a layer (cathode side adjacent layer) containing the material of the present invention is formed between the phosphorescent light emitting layer 40 and the electron transport zone 50, the layer functions as a hole blocking layer or as an exciton blocking layer. It has a function.
The barrier layer (blocking layer) is a layer having a function of a carrier movement barrier or an exciton diffusion barrier. The organic layer for preventing electrons from leaking from the light-emitting layer to the hole transport zone is mainly defined as an electron barrier layer, and the organic layer for preventing holes from leaking from the light-emitting layer to the electron transport zone is defined as a hole barrier. Sometimes defined as a layer. In addition, an exciton blocking layer (triplet barrier layer) is an organic layer for preventing triplet excitons generated in the light emitting layer from diffusing into a peripheral layer having triplet energy lower than that of the light emitting layer. It may be defined as
Further, the material of the present invention can be used for an organic thin film layer adjacent to the phosphorescent light emitting layer 40 and further used for another organic thin film layer bonded to the adjacent organic thin film layer.

In addition to the above-described embodiments, the organic EL element of the present invention can employ various known configurations. Further, light emission of the light emitting layer can be taken out from the anode side, the cathode side, or both sides.

In the organic EL device of the present invention, it is preferable that at least one of an electron donating dopant and an organometallic complex is added to the interface region between the cathode and the organic thin film layer. According to such a configuration, it is possible to improve the light emission luminance and extend the life of the organic EL element.
Examples of the electron donating dopant include at least one selected from alkali metals, alkali metal compounds, alkaline earth metals, alkaline earth metal compounds, rare earth metals, rare earth metal compounds, and the like.
Examples of the organometallic complex include at least one selected from an organometallic complex containing an alkali metal, an organometallic complex containing an alkaline earth metal, an organometallic complex containing a rare earth metal, and the like.

Examples of the alkali metal include lithium (Li) (work function: 2.93 eV), sodium (Na) (work function: 2.36 eV), potassium (K) (work function: 2.28 eV), rubidium (Rb) (work Function: 2.16 eV), cesium (Cs) (work function: 1.95 eV) and the like, and those having a work function of 2.9 eV or less are particularly preferable. Of these, K, Rb, and Cs are preferred, Rb and Cs are more preferred, and Cs is most preferred.
Examples of the alkaline earth metal include calcium (Ca) (work function: 2.9 eV), strontium (Sr) (work function: 2.0 eV to 2.5 eV), barium (Ba) (work function: 2.52 eV). A work function of 2.9 eV or less is particularly preferable.
Examples of the rare earth metal include scandium (Sc), yttrium (Y), cerium (Ce), terbium (Tb), ytterbium (Yb) and the like, and those having a work function of 2.9 eV or less are particularly preferable.
Among the above metals, preferred metals are particularly high in reducing ability, and by adding a relatively small amount to the electron injection region, it is possible to improve the light emission luminance and extend the life of the organic EL element.

Examples of the alkali metal compound include lithium oxide (Li ₂ O), cesium oxide (Cs ₂ O), alkali oxides such as potassium oxide (K ₂ O), lithium fluoride (LiF), sodium fluoride (NaF), fluorine. Examples thereof include alkali halides such as cesium fluoride (CsF) and potassium fluoride (KF), and lithium fluoride (LiF), lithium oxide (Li ₂ O), and sodium fluoride (NaF) are preferable.
Examples of the alkaline earth metal compound include barium oxide (BaO), strontium oxide (SrO), calcium oxide (CaO), and barium strontium oxide (Ba _x Sr _1-x O) (0 <x <1), Examples thereof include barium calcium oxide (Ba _x Ca _1-x O) (0 <x <1), and BaO, SrO, and CaO are preferable.
The rare earth metal compound, ytterbium fluoride _(YbF 3), scandium fluoride _(ScF 3), scandium oxide _(ScO 3), yttrium oxide _(Y _{2 O} 3), cerium oxide _(Ce _{2 O} 3), gadolinium fluoride _(GdF 3), include such terbium fluoride (TbF ₃₎ _{_{is, YbF 3, ScF 3, TbF}} 3 are preferable.

The organometallic complex is not particularly limited as long as it contains at least one of an alkali metal ion, an alkaline earth metal ion, and a rare earth metal ion as a metal ion as described above. The ligands include quinolinol, benzoquinolinol, acridinol, phenanthridinol, hydroxyphenyl oxazole, hydroxyphenyl thiazole, hydroxydiaryl thiadiazole, hydroxydiaryl thiadiazole, hydroxyphenylpyridine, hydroxyphenylbenzimidazole, hydroxybenzotriazole, Hydroxyfulborane, bipyridyl, phenanthroline, phthalocyanine, porphyrin, cyclopentadiene, β-diketones, azomethines, and derivatives thereof are preferred, but are not limited thereto.

As the addition form of the electron donating dopant and the organometallic complex, it is preferable to form a layer or an island in the interface region. As a forming method, while depositing at least one of an electron donating dopant and an organometallic complex by a resistance heating vapor deposition method, an organic material as a light emitting material or an electron injection material for forming an interface region is simultaneously deposited, and an electron is deposited in the organic material. A method of dispersing at least one of a donor dopant and an organometallic complex reducing dopant is preferable. The dispersion concentration is usually organic substance: electron donating dopant and / or organometallic complex in a molar ratio of 100: 1 to 1: 100, preferably 5: 1 to 1: 5.

In the case where at least one of the electron donating dopant and the organometallic complex is formed in a layered form, after forming the light emitting material or the electron injecting material that is the organic layer at the interface in a layered form, at least one of the electron donating dopant and the organometallic complex is formed. These are vapor-deposited by a resistance heating vapor deposition method alone, preferably with a layer thickness of 0.1 nm to 15 nm.

In the case where at least one of an electron donating dopant and an organometallic complex is formed in an island shape, a light emitting material or an electron injecting material which is an organic layer at the interface is formed in an island shape, and then the electron donating dopant and the organometallic complex are formed. At least one of them is vapor-deposited by a resistance heating vapor deposition method, preferably with an island thickness of 0.05 nm to 1 nm.

In the organic EL device of the present invention, the ratio of at least one of the main component (light-emitting material or electron injection material), the electron-donating dopant, and the organometallic complex is, as a molar ratio, the main component: the electron-donating dopant. And / or organometallic complex = 5: 1 to 1: 5, preferably 2: 1 to 1: 2.

In the organic EL element of the present invention, the configuration other than the layer using the organic EL element material of the present invention described above is not particularly limited, and a known material or the like can be used. Hereinafter, although the layer of the element of Embodiment 1 is demonstrated easily, the material applied to the organic EL element of this invention is not limited to the following.

[substrate]
As the substrate, a glass plate, a polymer plate or the like can be used.
Examples of the glass plate include soda lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfone, and polysulfone.

[anode]
The anode is made of, for example, a conductive material, and a conductive material having a work function larger than 4 eV is suitable.
Examples of the conductive material include carbon, aluminum, vanadium, iron, cobalt, nickel, tungsten, silver, gold, platinum, palladium, and their alloys, ITO substrate, tin oxide used for NESA substrate, indium oxide, and the like. Examples thereof include metal oxides and organic conductive resins such as polythiophene and polypyrrole.
The anode may be formed with a layer structure of two or more layers if necessary.

[cathode]
The cathode is made of, for example, a conductive material, and a conductive material having a work function smaller than 4 eV is suitable.
Examples of the conductive material include, but are not limited to, magnesium, calcium, tin, lead, titanium, yttrium, lithium, ruthenium, manganese, aluminum, lithium fluoride, and alloys thereof.
Examples of the alloy include magnesium / silver, magnesium / indium, lithium / aluminum, and the like, but are not limited thereto. The ratio of the alloy is controlled by the temperature of the vapor deposition source, the atmosphere, the degree of vacuum, etc., and is selected to an appropriate ratio.
If necessary, the cathode may be formed with a layer structure of two or more layers, and the cathode can be produced by forming a thin film from the conductive material by a method such as vapor deposition or sputtering.

When light emitted from the light emitting layer is taken out from the cathode, the transmittance of the cathode for light emission is preferably greater than 10%.
The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually 10 nm to 1 μm, preferably 50 to 200 nm.

[Light emitting layer]
When the phosphorescent light emitting layer is formed of a material other than the organic EL element layer material of the present invention, a known material can be used as the material of the phosphorescent light emitting layer. Specifically, Japanese Patent Application No. 2005-517938 may be referred to.
The organic EL device of the present invention may have a fluorescent light emitting layer like the device shown in FIG. A known material can be used for the fluorescent light emitting layer.

The light emitting layer may be a double host (also referred to as a host / cohost). Specifically, the carrier balance in the light emitting layer may be adjusted by combining an electron transporting host and a hole transporting host in the light emitting layer.
Moreover, it is good also as a double dopant. In the light emitting layer, each dopant emits light by adding two or more dopant materials having a high quantum yield. For example, a yellow light emitting layer may be realized by co-evaporating a host, a red dopant, and a green dopant.
The light emitting layer may be a single layer or a laminated structure. When the light emitting layer is stacked, the recombination region can be concentrated on the light emitting layer interface by accumulating electrons and holes at the light emitting layer interface. This improves the quantum efficiency.

[Hole injection layer and hole transport layer]
The hole injection / transport layer is a layer that assists hole injection into the light emitting layer and transports it to the light emitting region, and has a high hole mobility and a low ionization energy.
As the material for the hole injection / transport layer, a material that transports holes to the light emitting layer with lower electric field strength is preferable. Further, when an electric field is applied with a hole mobility of, for example, 10 ⁴ to 10 ⁶ V / cm, At least 10 ⁻⁴ cm ² / V · sec is preferable.
A cross-linkable material can be used as the material for the hole injection / transport layer.

[Electron injection layer and electron transport layer]
The electron injection / transport layer is a layer that assists the injection of electrons into the light emitting layer and transports it to the light emitting region, and has a high electron mobility.
In the organic EL element, since emitted light is reflected by an electrode (for example, a cathode), it is known that light emitted directly from the anode interferes with light emitted via reflection by the electrode. In order to efficiently use this interference effect, the electron injecting / transporting layer is appropriately selected with a film thickness of several nm to several μm. However, particularly when the film thickness is large, in order to avoid a voltage increase, 10 ⁴ to 10 ^6. The electron mobility is preferably at least 10 ⁻⁵ cm ² / Vs or more when an electric field of V / cm is applied.

As the electron transporting material used for the electron injection / transport layer, an aromatic heterocyclic compound containing one or more heteroatoms in the molecule is preferably used, and a nitrogen-containing ring derivative is particularly preferable. The nitrogen-containing ring derivative is preferably an aromatic ring having a nitrogen-containing 6-membered ring or 5-membered ring skeleton, or a condensed aromatic ring compound having a nitrogen-containing 6-membered ring or 5-membered ring skeleton, such as a pyridine ring. , Pyrimidine ring, triazine ring, benzimidazole ring, phenanthroline ring, quinazoline ring and the like.

In addition, an organic layer having semiconductivity may be formed by doping a donor material (n) and acceptor material (p). A typical example of N doping is to dope a metal such as Li or Cs into an electron transporting material, and a typical example of P doping is to dope an acceptor material such as F4TCNQ into a hole transporting material ( For example, see Japanese Patent No. 3695714).

For the formation of each layer of the organic EL device of the present invention, a known method such as a dry film forming method such as vacuum deposition, sputtering, plasma, or ion plating, or a wet film forming method such as spin coating, dipping, or flow coating is applied. be able to.
The thickness of each layer is not particularly limited, but must be set to an appropriate thickness. If the film thickness is too thick, a large applied voltage is required to obtain a constant light output, resulting in poor efficiency. If the film thickness is too thin, pinholes and the like are generated, and sufficient light emission luminance cannot be obtained even when an electric field is applied. The normal film thickness is suitably in the range of 5 nm to 10 μm, but more preferably in the range of 10 nm to 0.2 μm.

[Nitrogen-containing heteroaromatic ring compound]
Synthesis Example 1 [Synthesis of Compound A]
(1) Synthesis of Intermediate B Intermediate B was synthesized by the following steps.

In an argon atmosphere, 500 ml of dehydrated THF was added to 41 g (100 mmol) of intermediate A synthesized according to the method described in International Publication No. 2009-008100 pamphlet, and the mixture was stirred at -70 ° C. Subsequently, 62.5 ml of 1.6M n-butyllithium n-hexane solution was added dropwise. After stirring at −70 ° C. for 1 hour, 56 g (300 mmol) of triisopropyl borate was added, stirred at −70 ° C. for 1 hour, and then stirred at room temperature for 5 hours. The reaction mixture was concentrated, 1500 ml of dichloromethane and 3000 ml of 1N hydrochloric acid were added, and the mixture was stirred for 1 hour in an ice-water bath. The organic phase was separated and dried over anhydrous magnesium sulfate, and the filtrate was concentrated. The obtained solid was suspended and washed with a mixed solvent of hexane-toluene to obtain 23 g of intermediate B (yield 61%) as a white solid.

(2) Synthesis of Intermediate C Intermediate C was synthesized by the following steps.

Under an argon atmosphere, 20 g (53 mmol) of Intermediate B, 3-bromocarbazole (53 mmol), 80 ml of 2M aqueous sodium carbonate solution, 240 ml of 1,2-dimethoxyethane (DME) were added, and then 1.8 g of tetrakis (triphenylphosphine) palladium. (1.6 mmol) was added and the mixture was heated to reflux with stirring for 8 hours. The organic phase was separated off and the aqueous phase was extracted twice with 300 ml of dichloromethane. The organic phases were combined and concentrated under reduced pressure, and the resulting residue was purified by silica gel column chromatography (hexane / dichloromethane = 3/2) to obtain 14.5 g of intermediate C (yield 55%) as a pale yellow color. Obtained as a solid.

(3) (3) Synthesis of Intermediate D Intermediate D was synthesized by the following steps.

Under an argon atmosphere, carbazole 16.7 g (100 mmol), 3,5-dibromopyridine 23.7 g (100 mmol), copper iodide 19.0 g (100 mmol), trans-1,2-cyclohexanediamine 11.4 g (100 mmol), 42.4 g (200 mmol) of tripotassium phosphate was added to 200 ml of dehydrated 1,4-dioxane, and the mixture was heated to reflux with stirring for 96 hours. To the residue obtained by concentrating the reaction solution under reduced pressure, 500 ml of toluene was added and heated to 120 ° C., and the insoluble material was filtered off. The residue obtained by concentrating the filtrate under reduced pressure was purified by silica gel column chromatography (hexane / toluene = 4/1) to obtain 6.8 g of intermediate D (yield 21%) as a white solid.

(4) Synthesis of Compound A Compound A was synthesized by the following steps.

Under an argon atmosphere, Intermediate C 3.0 g (6 mmol), Intermediate D 1.94 g (6 mmol), Tris (dibenzylideneacetone) dipalladium 0.22 g (0.24 mmol), Tri-t-butylphosphonium tetrafluoroborate 0 .28 g (0.96 mmol), t-butoxy sodium 0.81 g (8.4 mmol) and dehydrated xylene 40 ml were sequentially added, and the mixture was heated to reflux with stirring for 8 hours. The residue obtained by concentrating the reaction solution under reduced pressure was purified by silica gel column chromatography (hexane / ethyl acetate = 1/4) to obtain 2.5 g (yield 56%) of Compound A as a white solid. .
The NMR measurement results of this solid are shown below.
¹ H-NMR (400 MHz, CDCl ₃ ) δ 7.28-7.55 (15H, m), 7.59-7.66 (2H, m), 7.73-7.88 (4H, m), 8 .15-8.24 (8H, m), 8.42 (1H, d, J = 2.0 Hz), 9.04 (2H, d, J = 2.0 Hz and 4.8 Hz)
Further, as a result of FD-MS analysis, m / e = 740 with respect to the molecular weight of 740.

Synthesis Example 2 [Synthesis of Compound B]
(1) Synthesis of Intermediate E Intermediate E was synthesized by the following steps.

Under a nitrogen atmosphere, in a three-necked flask, 100.1 g (575 mmol) of 2-bromo-3-hydroxypyridine, 88.5 g (632.5 mmol) of 2-fluorophenylboronic acid, 88.5 g (2300 mmol) of potassium carbonate, N, N— 1150 ml of dimethylacetamide and 13.3 g (11.5 mmol) of tetrakis (triphenylphosphine) palladium were added, and the mixture was heated and stirred at 90 ° C. for 12 hours and then heated and stirred at 160 ° C. for 8 hours.
After completion of the reaction, after cooling to room temperature, 1000 ml of toluene and 1000 ml of water were added to the sample solution, transferred to a separatory funnel and shaken well, the toluene phase was recovered, and extracted from the aqueous phase with toluene several times. The toluene solution was further washed several times with water, dried over anhydrous magnesium sulfate, passed through a silica gel short column and concentrated. The obtained sample was recrystallized from 200 ml of hexane to obtain 54.4 g of Intermediate E (yield 56%) as a pale yellow solid.

(2) Synthesis of Intermediate F Intermediate F was synthesized by the following steps.

In an air atmosphere, 52.6 g (310 mmol) of intermediate E, 155 ml of nitrobenzene, and 19.1 ml (372 mmol) of bromine were placed in a three-necked flask, and the mixture was heated and stirred at 140 ° C. for 12 hours. After completion of the reaction, the reaction solution was cooled to room temperature, and then the reaction solution was cooled in an ice water bath to add a sodium thiosulfate aqueous solution to deactivate residual bromine, and further an aqueous sodium hydroxide solution was added to adjust the aqueous phase to pH 10. The solution was transferred to a separatory funnel and extracted several times with toluene. This was dried over anhydrous magnesium sulfate, filtered and concentrated. This was purified by silica gel column chromatography (dichloromethane / ethyl acetate = 4/1), and the resulting solid was dispersed and washed with hexane, collected by filtration, and vacuum-dried (40 ° C., 6 hours) to obtain intermediate F32. 1 g (42% yield) was obtained as a pale yellow solid.

(3) Synthesis of Compound B Compound B was synthesized by the following steps.

Under an argon atmosphere, intermediate C 3.5 g (7 mmol), intermediate F 1.74 g (7 mmol), tris (dibenzylideneacetone) dipalladium 0.26 g (0.28 mmol), tri-t-butylphosphonium tetrafluoroborate 0 .33 g (1.12 mmol), t-butoxy sodium 0.94 g (9.8 mmol), and dehydrated xylene 50 ml were sequentially added, and the mixture was heated to reflux with stirring for 24 hours. The residue obtained by concentrating the reaction solution under reduced pressure was purified by silica gel column chromatography (hexane / ethyl acetate = 1/1) to obtain 3.2 g (yield 68%) of compound B as a white solid. .
As a result of FD-MS analysis, m / e = 665 with respect to the molecular weight of 665.

Synthesis Example 3 [Synthesis of Compound C]
(1) Synthesis of Intermediate G Intermediate G was synthesized by the following steps.

Under an argon atmosphere, 50 g (390 mmol) of 3-amino-2-chloropyridine, iodobenzene (936 mmol), 0.88 g (3.9 mmol) of palladium acetate, 4 ml of 2M toluene solution of tri-t-butylphosphine, sodium t-butoxy 150 g (1560 mmol) was sequentially added to 1560 ml of dehydrated toluene, and the mixture was stirred with heating under reflux for 24 hours. The residue obtained by concentrating the reaction solution under reduced pressure was purified by silica gel column chromatography (hexane / dichloromethane = 1/2) to obtain 78.8 g of the desired product (yield 72%).

(2) Synthesis of Intermediate H Intermediate H was synthesized by the following steps.

Under an argon atmosphere, 11.2 g (40 mmol) of intermediate G, 0.45 g (2 mmol) of palladium acetate, 1.47 g (4 mmol) of tricyclohexylphosphonium tetrafluoroborate, 40 ml of N, N-dimethylacetamide, and 40 ml of toluene were added successively. Then, a Dean-Stark trap was attached, and the mixture was heated to reflux with stirring for 6 hours while discharging water out of the system. The residue obtained by concentrating the reaction solution under reduced pressure was purified by silica gel column chromatography (hexane / dichloromethane = 1/10) to give 4.4 g (yield 45%) of the target product as a pale yellow solid. Obtained.

(3) Synthesis of Intermediate I Intermediate I was synthesized by the following steps.

Under an air atmosphere, 8.9 g (36.4 mmol) of the intermediate H, 100 ml of acetic acid, and 18.7 ml (36.4 mmol) of bromine were added and stirred with heating at 100 ° C. for 12 hours. After completion of the reaction, after cooling to room temperature, dichloromethane was added to the reaction solution, sodium thiosulfate aqueous solution was added while cooling in an ice water bath to deactivate residual bromine, and further aqueous sodium hydroxide solution was added to bring the aqueous phase to pH 10. It was prepared so that it might become. The solution was transferred to a separatory funnel and extracted several times with dichloromethane. This was dried over anhydrous magnesium sulfate, filtered and concentrated. This was purified by short silica gel column chromatography, and the filtrate was concentrated under reduced pressure. The solid obtained was dispersed and washed with a mixed solvent of hexane-ethyl acetate, collected by filtration, and vacuum dried (40 ° C., 5 hours). Intermediate 9.6 g (81% yield) was obtained as a white solid.

(4) Synthesis of Compound C Compound C was synthesized by the following steps.

Under argon atmosphere, intermediate C 3.5 g (7 mmol), intermediate I 2.27 g (7 mmol), tris (dibenzylideneacetone) dipalladium 0.26 g (0.28 mmol), tri-t-butylphosphonium tetrafluoroborate 0.33 g (1.12 mmol), 0.94 g (9.8 mmol) of t-butoxy sodium, and 50 ml of dehydrated xylene were sequentially added, and the mixture was heated to reflux with stirring for 16 hours. The residue obtained by concentrating the reaction solution under reduced pressure was purified by silica gel column chromatography (hexane / ethyl acetate = 2/1) to give 3.5 g (yield 86%) of compound C as a white solid. .
As a result of FD-MS analysis, m / e = 740 with respect to the molecular weight of 740.

Synthesis Example 4 [Synthesis of Compound D]
Compound D was synthesized by the following steps.

Under an argon atmosphere, Intermediate C 3.5 g (7 mmol), Intermediate A 2.9 g (7 mmol), Tris (dibenzylideneacetone) dipalladium 0.26 g (0.28 mmol), Tri-t-butylphosphonium tetrafluoroborate 0 .33 g (1.12 mmol), t-butoxy sodium 0.94 g (9.8 mmol), and 50 ml of dehydrated xylene were sequentially added, and the mixture was heated to reflux with stirring for 8 hours. The residue obtained by concentrating the reaction solution under reduced pressure was purified by silica gel column chromatography (hexane / toluene = 1/1) to obtain 2.1 g (yield 36%) of compound D as a white solid.
As a result of FD-MS analysis, it was m / e = 829 with respect to a molecular weight of 829.

[Organic EL device]
Example 1
A 25 mm × 75 mm × 1.1 mm glass substrate with an ITO transparent electrode (manufactured by Geomatic) was subjected to ultrasonic cleaning for 5 minutes in isopropyl alcohol, and further subjected to UV (Ultraviolet) ozone cleaning for 30 minutes.
The glass substrate with the transparent electrode thus cleaned is attached to the substrate holder of the vacuum evaporation apparatus, and first, on the surface of the glass substrate on which the transparent electrode line is formed, the transparent electrode is covered, The following compound I was vapor-deposited with a thickness of 20 nm to obtain a hole injection layer. Subsequently, the following compound II was vapor-deposited with a thickness of 60 nm on this film to obtain a hole transport layer.
On this hole transport layer, Compound A as a phosphorescent host material and the following compound D-1 as a phosphorescent material were co-deposited at a thickness of 50 nm to obtain a phosphorescent layer. The concentration of Compound A in the phosphorescent light emitting layer was 80% by mass, and the concentration of Compound D-1 was 20% by mass.
Subsequently, the following compound H-1 was vapor-deposited with a thickness of 10 nm on this phosphorescent light-emitting layer, whereby an electron transport layer 1 was obtained. Further, the following compound III was vapor-deposited with a thickness of 10 nm to obtain the electron transport layer 2, and then a cathode was formed by sequentially laminating 1 nm thick LiF and 80 nm thick metal Al to produce an organic EL device. did. Note that LiF was formed at a rate of 1 Å / min.

The organic EL element produced as described above was caused to emit light by direct current drive, the current density was measured, and the voltage at a current density of 1 mA / cm ² was obtained. The results are shown in Table 1.

Example 2
An organic EL device was prepared and evaluated in the same manner as in Example 1 except that Compound A was used instead of Compound H-1 as the material for the electron transport layer 1. The results are shown in Table 1.

Example 3
An organic EL device was produced in the same manner as in Example 1 except that Compound B was used instead of Compound A as the phosphorescent host material, and Compound B was used instead of Compound H-1 as the material for the electron transport layer 1. ,evaluated. The results are shown in Table 1.

Example 4
An organic EL device was prepared in the same manner as in Example 1 except that Compound C was used instead of Compound A as the phosphorescent host material and Compound C was used instead of Compound H-1 as the material for the electron transport layer 1. ,evaluated. The results are shown in Table 1.

Example 5
An organic EL device was produced in the same manner as in Example 1 except that Compound D was used instead of Compound A as the phosphorescent host material, and Compound D was used instead of Compound H-1 as the material for the electron transport layer 1. ,evaluated. The results are shown in Table 1.

Comparative Example 1
An organic EL device was prepared and evaluated in the same manner as in Example 1 except that Compound H-1 was used instead of Compound A as the phosphorescent host material. The results are shown in Table 1.

Comparative Example 2
Organic EL in the same manner as in Example 1 except that Compound H-2 was used instead of Compound A as the phosphorescent host material and Compound H-2 was used instead of Compound H-1 as the material for the electron transport layer 1. A device was fabricated and evaluated. The results are shown in Table 1.

Comparative Example 3
Organic EL in the same manner as in Example 1 except that Compound H-4 was used instead of Compound A as the phosphorescent host material and Compound H-4 was used instead of Compound H-1 as the material for the electron transport layer 1. A device was fabricated and evaluated. The results are shown in Table 1.

From the results of Examples 1 to 5, it was found that when the compound of the present invention was used for the light emitting layer, a blue light emitting device having a voltage lower than that of the comparative compound was obtained.

Example 6
An organic EL device was prepared in the same manner as in Example 1, except that Compound H-1 was used instead of Compound A as the phosphorescent host material, and Compound A was used instead of Compound H-1 as the material for the electron transport layer 1. Prepared and evaluated. The results are shown in Table 2.

Example 7
An organic EL device was prepared in the same manner as in Example 1, except that Compound H-1 was used instead of Compound A as the phosphorescent host material, and Compound B was used instead of Compound H-1 as the material for the electron transport layer 1. Prepared and evaluated. The results are shown in Table 2.

Example 8
An organic EL device was prepared in the same manner as in Example 1, except that Compound H-1 was used instead of Compound A as the phosphorescent host material, and Compound C was used instead of Compound H-1 as the material for the electron transport layer 1. Prepared and evaluated. The results are shown in Table 2.

Example 9
An organic EL device was prepared in the same manner as in Example 1 except that Compound H-1 was used instead of Compound A as the phosphorescent host material, and Compound D was used instead of Compound H-1 as the material for the electron transport layer 1. Prepared and evaluated. The results are shown in Table 2.

Comparative Example 4
Organic EL in the same manner as in Example 1 except that Compound H-1 was used instead of Compound A as the phosphorescent host material and Compound H-2 was used instead of Compound H-1 as the material for the electron transport layer 1. A device was fabricated and evaluated. The results are shown in Table 2.

Comparative Example 5
Organic EL in the same manner as in Example 1 except that Compound H-1 was used instead of Compound A as the phosphorescent host material, and Compound H-4 was used instead of Compound H-1 as the material for the electron transport layer 1. A device was fabricated and evaluated. The results are shown in Table 2.

Example 10
An organic EL device was prepared in the same manner as in Example 1, except that Compound H-3 was used instead of Compound A as the phosphorescent host material, and Compound A was used instead of Compound H-1 as the material for the electron transport layer 1. Prepared and evaluated. The results are shown in Table 2.

Example 11
An organic EL device was prepared in the same manner as in Example 1 except that Compound H-3 was used instead of Compound A as the phosphorescent host material, and Compound B was used instead of Compound H-1 as the material for the electron transport layer 1. Prepared and evaluated. The results are shown in Table 2.

Example 12
An organic EL device was prepared in the same manner as in Example 1 except that Compound H-3 was used instead of Compound A as the phosphorescent host material, and Compound C was used instead of Compound H-1 as the material for the electron transport layer 1. Prepared and evaluated. The results are shown in Table 2.

Comparative Example 6
Organic EL in the same manner as in Example 1 except that Compound H-3 was used instead of Compound A as the phosphorescent host material and Compound H-2 was used instead of Compound H-1 as the material for the electron transport layer 1. A device was fabricated and evaluated. The results are shown in Table 2.

Comparative Example 7
Organic EL device in the same manner as in Example 1 except that Compound H-3 was used instead of Compound A as the host material, and Compound H-4 was used instead of Compound H-1 as the material for the electron transport layer 1 Were made and evaluated. The results are shown in Table 2.

The organic EL device produced as described above was caused to emit light by direct current drive, the luminance and current density were measured, and the light emission efficiency (external quantum efficiency) at a current density of 1 mA / cm ² was obtained. Furthermore, the brightness | luminance 70% lifetime (time when a brightness | luminance falls to 70%) in initial stage brightness | luminance 3,000cd / m < ² > was calculated | required. The results are shown in Table 2.

From the results of Examples 6 to 12, it was found that when the compound of the present invention was used as an electron transport layer material, a device having higher efficiency and longer life than the comparative compound was obtained.

The nitrogen-containing heteroaromatic ring compound of the present invention is suitable for a material for an organic EL device, for example, a host material for an emission layer or an electron transport layer material. Moreover, the organic EL element material of the present invention that can also be used for blue phosphorescent light emitting elements can be used for organic semiconductors, organic solar cells, and the like in addition to organic EL elements.
The organic EL device of the present invention can be used for a flat light emitter such as a flat panel display of a wall-mounted television, a light source such as a copying machine, a printer, a backlight of a liquid crystal display or an instrument, a display board, a marker lamp, an illumination device, and the like.

Although several embodiments and / or examples of the present invention have been described in detail above, those skilled in the art will appreciate that these exemplary embodiments and / or embodiments are substantially without departing from the novel teachings and advantages of the present invention. It is easy to make many changes to the embodiment. Accordingly, many of these modifications are within the scope of the present invention.
All the contents of the Japanese application specification that is the basis of the priority of Paris in this application are incorporated herein.

Claims

A nitrogen-containing heteroaromatic ring compound represented by the following formula (1).

[In Formula (1),
X represents an oxygen atom or a sulfur atom,
Y 11 to Y 18 , Y 21 to Y 28 and Y 31 to Y 38 each represent CR 1 or a nitrogen atom;
R 1 is a single bond, a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, a substituted or unsubstituted carbon atom having 1 to 20 alkoxy groups, substituted or unsubstituted cycloalkoxy groups having 3 to 20 ring carbon atoms, substituted or unsubstituted aromatic hydrocarbon rings having 6 to 18 ring carbon atoms, substituted or unsubstituted ring carbon atoms 6-18 aryloxy group, substituted or unsubstituted heteroaromatic ring having 5 to 18 ring atoms, substituted or unsubstituted amino group, fluorine atom, substituted or unsubstituted fluoroalkyl having 1 to 20 carbon atoms group, a substituted or unsubstituted fluoroalkoxy group having 1 to 20 carbon atoms, or a cyano group, when a plurality of CR 1 is present, R 1 is each the same or different Well,
A 2 and A 3 are each a single bond, an oxygen atom, a sulfur atom, or a group represented by the following formulas (a) to (e):

R 2 to R 6 are each a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, or a substituted or unsubstituted carbon number. 1-20 alkoxy group, substituted or unsubstituted cycloalkoxy group having 3-20 carbon atoms, substituted or unsubstituted aromatic hydrocarbon ring having 6-18 carbon atoms, substituted or unsubstituted ring formation Aryloxy group having 6 to 18 carbon atoms, substituted or unsubstituted heteroaromatic ring having 5 to 18 ring atoms, substituted or unsubstituted amino group, fluorine atom, substituted or unsubstituted carbon atoms having 1 to 20 carbon atoms Represents a fluoroalkyl group, a substituted or unsubstituted fluoroalkoxy group having 1 to 20 carbon atoms, or a cyano group;
HAr represents a substituted or unsubstituted monocyclic or condensed nitrogen-containing aromatic ring having 5 to 18 ring atoms, a dibenzofuran ring having a substituent, or a substituted or unsubstituted dibenzothiophene ring. ]
Wherein A 2 and A 3 are both single bonds, nitrogen-containing heteroaromatic ring compound of claim 1.
The nitrogen-containing heteroaromatic ring compound according to claim 1 or 2, which is a nitrogen-containing heteroaromatic ring compound represented by the following formula (2).

[In the formula (2), X, Y 11 , Y 13 to Y 18 , Y 21 to Y 28 , Y 31 to Y 38 and HAr are the same as those in the formula (1). ]
The nitrogen-containing heteroaromatic ring compound according to any one of claims 1 to 3, which is a nitrogen-containing heteroaromatic ring compound represented by the following formula (3):

[In Formula (3), X, Y 11 , Y 13 to Y 18 , Y 21 to Y 28 , Y 31 , Y 33 to Y 38 , and HAr are the same as those in Formula (1). ]
The nitrogen-containing heteroaromatic ring compound according to any one of claims 1 to 3, which is a nitrogen-containing heteroaromatic ring compound represented by the following formula (4):

[In the formula (4), X, Y 11 , Y 13 to Y 18 , Y 21 to Y 28 , Y 32 to Y 38 , and HAr are the same as those in the formula (1). ]
The nitrogen-containing heteroaromatic ring compound according to any one of claims 1 to 3, which is a nitrogen-containing heteroaromatic ring compound represented by the following formula (5).

[In the formula (5), X, Y 11 , Y 13 to Y 18 , Y 21 to Y 28 , Y 31 to Y 32 , Y 34 to Y 38 , and HAr are the same as those in the formula (1). ]
The nitrogen-containing heteroaromatic ring compound according to any one of claims 1 to 3, which is a nitrogen-containing heteroaromatic ring compound represented by the following formula (6).

[In the formula (6), X, Y 11 , Y 13 to Y 18 , Y 21 to Y 28 , Y 31 to Y 33 , Y 35 to Y 38 , and HAr are the same as in the above formula (1). ]
The nitrogen-containing heteroaromatic ring compound according to any one of claims 1 to 7, wherein the HAr is represented by the following formula (A-1).

[In the formula (A-1),
Y 1a to Y 1e each represents CR 1a or a nitrogen atom;
At least one of Y 1a to Y 1e represents a nitrogen atom;
R 1a is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms. Group, substituted or unsubstituted cycloalkoxy group having 3 to 20 ring carbon atoms, substituted or unsubstituted aromatic hydrocarbon ring having 6 to 18 ring carbon atoms, substituted or unsubstituted ring carbon atoms having 6 to 18 carbon atoms Aryloxy group, substituted or unsubstituted heteroaromatic ring having 5 to 18 ring atoms, substituted or unsubstituted amino group, fluorine atom, substituted or unsubstituted fluoroalkyl group having 1 to 20 carbon atoms, substituted Or an unsubstituted fluoroalkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted diarylphosphino group having 12 to 30 carbon atoms, a substituted or unsubstituted carbon number 12 Represents a diarylphosphine oxide group of ˜30, a substituted or unsubstituted diarylphosphinoaryl group of 18 to 30 carbon atoms or a cyano group, and when a plurality of CR 1a are present, R 1a may be the same or different Good. ]
The nitrogen-containing heteroaromatic ring compound according to any one of claims 1 to 7, wherein the HAr is represented by the following formula (A-2).

[In the formula (A-2),
Y 2a to Y 2i each represents CR 2a or a nitrogen atom,
X 2 represents an oxygen atom, a sulfur atom or —NR 2b ,
R 2a is a single bond, a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, a substituted or unsubstituted carbon number of 1 to 20 alkoxy groups, substituted or unsubstituted cycloalkoxy groups having 3 to 20 ring carbon atoms, substituted or unsubstituted aromatic hydrocarbon rings having 6 to 18 ring carbon atoms, substituted or unsubstituted ring carbon atoms 6-18 aryloxy group, substituted or unsubstituted heteroaromatic ring having 5 to 18 ring atoms, substituted or unsubstituted amino group, fluorine atom, substituted or unsubstituted fluoroalkyl having 1 to 20 carbon atoms Group, substituted or unsubstituted fluoroalkoxy group having 1 to 20 carbon atoms, substituted or unsubstituted diarylphosphino group having 12 to 30 carbon atoms, substituted or unsubstituted carbon Represents a diarylphosphine oxide group having a prime number of 12 to 30, a substituted or unsubstituted diarylphosphinoaryl group having a carbon number of 18 to 30, or a cyano group, and when a plurality of CR 2a are present, each R 2a is the same or different. You can,
When X 2 represents an oxygen atom and R 2a all represent a single bond or a hydrogen atom, at least one of Y 2a to Y 2i represents a nitrogen atom;
R 2b represents a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, or a substituted or unsubstituted aromatic group having 6 to 18 ring carbon atoms. It represents a hydrocarbon ring or a substituted or unsubstituted heteroaromatic ring having 5 to 18 ring atoms. ]
The nitrogen-containing heteroaromatic ring compound according to claim 9, wherein in formula (A-2), at least one of Y 2a to Y 2i is a nitrogen atom.
An organic electroluminescent element material comprising the nitrogen-containing heteroaromatic ring compound according to any one of claims 1 to 10.
Between the cathode and the anode, having one or more organic thin film layers including a light emitting layer,
The organic electroluminescent element in which at least one layer of the said organic thin film layer contains the organic electroluminescent element material of Claim 11.
The organic electroluminescence device according to claim 12, wherein the light emitting layer contains the material for an organic electroluminescence device.
14. The light-emitting layer contains a phosphorescent material, and the phosphorescent material is an orthometalated complex of a metal atom selected from iridium (Ir), osmium (Os), and platinum (Pt). Organic electroluminescence device.
The organic electroluminescence device according to any one of claims 12 to 14, further comprising an organic thin film layer between the cathode and the light emitting layer, wherein the organic thin film layer contains the material for the organic electroluminescence device.
The organic electroluminescent element according to claim 15, wherein the organic thin film layer is adjacent to the light emitting layer.
The organic electroluminescence device according to any one of claims 12 to 16, wherein at least one of an electron donating dopant and an organometallic complex is added to an interface region between the cathode and the organic thin film layer.