JP2013035752A - Biscarbazole derivative and organic electroluminescence element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biscarbazole derivative capable of improving emission efficiency and an emission life of an organic electroluminescence element, and to provide an organic electroluminescence element using the derivative.SOLUTION: The biscarbazole derivative is represented by the formula.

Description

  The present invention relates to a biscarbazole derivative and an organic electroluminescence device using the same.

When a voltage is applied to an organic electroluminescence element (hereinafter referred to as an organic EL element), holes from the anode and electrons from the cathode are injected into the light emitting layer. Then, in the light emitting layer, the injected holes and electrons are recombined to form excitons. At this time, singlet excitons and triplet excitons are generated at a ratio of 25%: 75% according to the statistical rule of electron spin. When classified according to the light emission principle, the fluorescence type uses light emitted from singlet excitons, and therefore the internal quantum efficiency of the organic EL element is said to be limited to 25%. On the other hand, in the phosphorescent type, since light emission by triplet excitons is used, it is known that the internal quantum efficiency can be increased to 100% when intersystem crossing is efficiently performed from singlet excitons.
Conventionally, in an organic EL element, an optimal element design has been made according to a light emission mechanism of a fluorescent type and a phosphorescent type. In particular, it is known that phosphorescent organic EL elements cannot obtain high-performance elements by simple diversion of fluorescent element technology because of their light emission characteristics. The reason is generally considered as follows.
First, since phosphorescence emission is emission using triplet excitons, the energy gap of the compound used in 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).

Therefore, in order to efficiently confine the triplet energy of the phosphorescent dopant material in the device, first, a host material having a triplet energy larger than the triplet energy of the phosphorescent dopant material must be used for the light emitting layer. Don't be. Furthermore, an electron transport layer and a hole transport layer adjacent to the light emitting layer are provided, and a compound having a triplet energy higher than that of the phosphorescent dopant material must be used for the electron transport layer and the hole transport layer. Thus, when based on the element design concept of the conventional organic EL element, a compound having a larger energy gap than the compound used for the fluorescent organic EL element is used for the phosphorescent organic EL element. The drive voltage of the entire element increases.
In addition, hydrocarbon compounds with high oxidation resistance and reduction resistance, which are useful in fluorescent elements, have a large energy gap due to a large spread of π electron clouds. Therefore, in the phosphorescent organic EL element, such a hydrocarbon compound is difficult to select, and an organic compound containing a hetero atom such as oxygen or nitrogen is selected. As a result, the phosphorescent organic EL element is There is a problem that the lifetime is shorter than that of a fluorescent organic EL element.
Furthermore, the fact that the exciton relaxation rate of the triplet exciton of the phosphorescent dopant material is much longer than that of the singlet exciton also greatly affects the device performance. That is, since light emitted from singlet excitons has a high relaxation rate that leads to light emission, the diffusion of excitons to the peripheral layers of the light-emitting layer (for example, a hole transport layer or an electron transport layer) hardly occurs and is efficient. Light emission is expected. On the other hand, light emission from triplet excitons is spin-forbidden and has a slow relaxation rate, so that excitons are likely to diffuse to the peripheral layer, and thermal energy deactivation occurs from other than specific phosphorescent compounds. End up. That is, control of the recombination region of electrons and holes is more important than the fluorescent organic EL element.
For the above reasons, in order to improve the performance of phosphorescent organic EL elements, material selection and element design different from those of fluorescent organic EL elements are required.

As a host material (phosphorescent host material) combined with such a phosphorescent dopant material, a technique using a carbazole derivative, an aromatic amine derivative, a quinolinol metal complex, or the like has been disclosed. There was no indication of drive voltage.
As an alternative to these phosphorescent host materials, in recent years, a technique using a biscarbazole derivative as a phosphorescent host material has been disclosed (for example, see Patent Documents 1 to 3).

Japanese Patent No. 4357781 JP 2008-135498 A International Publication No. 2011/0119156

Patent Documents 1 to 3 disclose organic EL elements using a biscarbazole derivative in which the 3-positions of carbazolyl groups are bonded to each other as a phosphorescent host material.
However, the organic EL elements described in Patent Documents 1 to 3 use the biscarbazole derivative as a phosphorescent host material suitable for green light emission.

  An object of the present invention is to provide a novel biscarbazole derivative that can be used in an organic EL element suitable for light emission on a longer wavelength side than green by changing the bonding position of a carbazolyl group, and an organic EL element using the same It is to be.

As a result of intensive studies to achieve the above object, the inventors of the present invention bonded two positions of two carbazolyl groups, and further, at least one N-position of two carbazolyl groups has a ring-forming carbon number of 1 to 2. It has been found that a biscarbazole derivative in which four nitrogen-containing aromatic heterocyclic groups are bonded directly or via a linking group improves the light emission efficiency and the light emission lifetime of the organic EL device.
The present inventors have completed the present invention based on such knowledge.

  The biscarbazole derivative of the present invention is represented by the following general formula (1).

In the general formula (1),
A ₁ and A ₂ are
A substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 ring carbon atoms or a substituted or unsubstituted aromatic heterocyclic group having 1 to 30 ring carbon atoms.
However, at least one of A ₁ and A ₂ represents a substituted or unsubstituted nitrogen-containing aromatic heterocyclic group having 1 to 4 ring carbon atoms.

In Formula _(1), Y 1 ~Y ₄ is a carbon atom or a nitrogen atom bonded with the following R. However, when two adjacent ones of Y _{1 to} Y ₄ are carbon atoms, a ring containing the adjacent carbon atoms may be formed without bonding to R.
Y _{5 to} Y ₇ are a carbon atom or a nitrogen atom bonded to the following R. However, when Y ₅ and Y ₆ are carbon atoms, a ring containing carbon atoms of Y ₅ and Y ₆ may be formed without bonding to R.
Y _{8 to} Y ₁₀ are a carbon atom or a nitrogen atom bonded to the following R. However, when Y ₉ and Y ₁₀ are carbon atoms, a ring containing carbon atoms of Y ₉ and Y ₁₀ may be formed without being bonded to R.
Y _{11 to} Y ₁₄ are a carbon atom or a nitrogen atom bonded to the following R. However, when two adjacent ones of Y _{11 to} Y ₁₄ are carbon atoms, a ring containing the adjacent carbon atoms may be formed without being bonded to R.
Here, Y _{1 to} Y ₁₄ will be specifically described. When two adjacent ones in the biscarbazole skeleton, for example, Y ₁ and Y ₂ are carbon atoms to form a ring, Y ₁ and Y ₂ are not bonded to R and include these Y ₁ and Y ₂ This means that the ring structure is formed separately from the 6-membered ring of the biscarbazole skeleton containing Y ₁ to Y ₄ . When _{the Y 1} and _{Y 2} forming the ring structure, _{Y 3} and _{Y 4} is a carbon atom or a nitrogen atom, if _{Y 3} and _{Y 4} carbon atoms, without binding with R, The ring structure containing Y ₃ and Y ₄ may be formed separately from the 6-membered ring of the biscarbazole skeleton containing Y ₁ to Y ₄ , or may be bonded to R without forming a ring. The same applies to the other _{Y 5 ~Y 7, Y 8 ~Y} 10, Y 11 ~Y 14.

In the general formula (1), R is independently a hydrogen atom,
A substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 ring carbon atoms,
A substituted or unsubstituted aromatic heterocyclic group having 1 to 30 ring carbon atoms,
A substituted or unsubstituted linear, branched, or cyclic alkyl group having 1 to 30 carbon atoms,
A substituted or unsubstituted alkoxy group having 1 to 30 carbon atoms,
A substituted or unsubstituted aryloxy group having 6 to 30 ring carbon atoms,
A substituted or unsubstituted aralkyl group having 7 to 30 carbon atoms,
A substituted or unsubstituted haloalkyl group having 1 to 30 carbon atoms,
A substituted or unsubstituted haloalkoxy group having 1 to 30 carbon atoms,
A substituted or unsubstituted trialkylsilyl group having 3 to 30 carbon atoms,
A substituted or unsubstituted dialkylarylsilyl group having 8 to 40 carbon atoms,
A substituted or unsubstituted alkyldiarylsilyl group having 13 to 50 carbon atoms,
A substituted or unsubstituted triarylsilyl group having 18 to 60 carbon atoms,
Halogen atoms,
A cyano group,
Hydroxyl group,
Represents a nitro group or a carboxy group.
L _{1 to} L ₃ represent a single bond or a divalent linking group.

In the biscarbazole derivative of the present invention,
L ₃ in the general formula (1) is preferably a single bond.

In the biscarbazole derivative of the present invention,
The nitrogen-containing aromatic heterocyclic group in the general formula (1) is
It is preferably a substituted or unsubstituted pyrimidinyl group or a substituted or unsubstituted triazinyl group.

In the biscarbazole derivative of the present invention,
In the general formula (1), at least one of L ₁ and L ₂ is
A divalent group of a substituted or unsubstituted aromatic hydrocarbon compound having 6 to 30 ring carbon atoms, or a divalent group of a substituted or unsubstituted aromatic heterocyclic compound having 1 to 30 ring carbon atoms Preferably there is.

The organic electroluminescence element of the present invention is
An organic electroluminescence device comprising an organic compound layer between a cathode and an anode,
The organic compound layer includes any of the biscarbazole derivatives of the present invention.

In the organic electroluminescence device of the present invention,
The organic compound layer includes a plurality of organic thin film layers including a light emitting layer,
At least one of the plurality of organic thin film layers preferably contains any of the biscarbazole derivatives of the present invention.

In the organic electroluminescence device of the present invention,
The light emitting layer preferably contains any of the biscarbazole derivatives of the present invention.

In the organic electroluminescence device of the present invention,
The light emitting layer preferably contains a phosphorescent material.

In the organic electroluminescence device of the present invention,
The phosphorescent material preferably includes an orthometalated complex of a metal atom selected from iridium (Ir), osmium (Os), and platinum (Pt).

In the organic electroluminescence device of the present invention,
The light emitting layer preferably further includes an aromatic amine derivative.

In the organic electroluminescence device of the present invention,
The plurality of organic thin film layers preferably include a hole transport layer, a light emitting layer, and an electron transport layer.

  When the biscarbazole derivative of the present invention is used for an organic EL device, the light emission efficiency and the light emission lifetime can be improved.

It is a figure which shows schematic structure of an example of the organic electroluminescent element which concerns on embodiment of this invention.

Hereinafter, the present invention will be specifically described.
(Biscarbazole derivative)
The biscarbazole derivative of the present invention is represented by the general formula (1).
The biscarbazole derivative of the present invention has a structure in which the 2-positions of two carbazolyl groups are bonded as shown in the general formula (1). The triplet energy can be reduced by bonding at the 2-positions of two carbazolyl groups. Therefore, when the biscarbazole derivative of the present invention is used as a host material, energy can be efficiently transmitted from the host material to the dopant material for a dopant material that develops red or yellow-green color.
Moreover, bis-carbazole derivatives of the present invention, as shown in the above general formula (1), A ₁ which is attached directly or via a linking group L ₁ ~L ₂ for N-position of the carbazolyl group (9-position) Alternatively, at least one of A ₂ is a substituted or unsubstituted nitrogen-containing aromatic heterocyclic group having 1 to 4 ring carbon atoms. Since the biscarbazole derivative of the present invention has such a structure, HOMO and LUMO can be clearly separated as compared with a structure in which a nitrogen-containing aromatic heterocyclic group is bonded to a benzene ring of a carbazolyl group. Therefore, it is considered that the biscarbazole derivative of the present invention has excellent resistance to holes and electrons.

  The aromatic hydrocarbon group having 6 to 30 ring carbon atoms in the general formula (1) includes a condensed aromatic hydrocarbon group, for example, a phenyl group, a 2-biphenylyl group, a 3-biphenylyl group, 4-biphenylyl group, p-terphenyl-4-yl group, p-terphenyl-3-yl group, p-terphenyl-2-yl group, m-terphenyl-4-yl group, m-terphenyl -3-yl group, m-terphenyl-2-yl group, o-tolyl group, m-tolyl group, p-tolyl group, pt-butylphenyl group, p- (2-phenylpropyl) phenyl group, 4'-methylbiphenylyl group, 4 "-t-butyl-p-terphenyl-4-yl group, o-cumenyl group, m-cumenyl group, p-cumenyl group, 2,3-xylyl group, 3,4 -Xylyl group, 2,5-xylyl group, mesi M-quaterphenyl group, 1-naphthyl group, 2-naphthyl group, 1-phenanthrenyl group, 2-phenanthrenyl group, 3-phenanthrenyl group, 4-phenanthrenyl group, 9-phenanthrenyl group, 1-triphenylenyl group, 2 -Triphenylenyl group, 3-triphenylenyl group, 4-triphenylenyl group, 1-chrycenyl group, 2-chrycenyl group, 3-chrycenyl group, 4-chrycenyl group, 5-chrycenyl group, 6-chrycenyl group can be mentioned.

The aromatic heterocyclic group having 1 to 30 ring carbon atoms in the general formula (1) includes a condensed aromatic heterocyclic group, for example, a pyrrolyl group, a pyrazinyl group, a pyridinyl group, an indolyl group, an isoindolyl group, Furyl group, benzofuranyl group, isobenzofuranyl group, dibenzofuranyl group, dibenzothiophenyl group, quinolyl group, isoquinolyl group, quinoxalinyl group, carbazolyl group, phenanthridinyl group, acridinyl group, phenanthrolinyl group, thienyl Pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, triazine ring, indole ring, quinoline ring, acridine ring, pyrrolidine ring, dioxane ring, piperidine ring, morpholine ring, piperazine ring, carbazole ring, furan ring, thiophene Ring, oxazole ring, oxadiazole ring, Nzookisazoru ring, a thiazole ring, a thiadiazole ring, a benzothiazole ring, a triazole ring, an imidazole ring, a benzimidazole ring, pyran ring, and a group formed by dibenzofuran ring.
More specifically, 1-pyrrolyl group, 2-pyrrolyl group, 3-pyrrolyl group, pyrazinyl group, 2-pyridinyl group, 2-pyrimidinyl group, 4-pyrimidinyl group, 5-pyrimidinyl group, 6-pyrimidinyl group, 1 , 2,3-triazin-4-yl group, 1,2,4-triazin-3-yl group, 1,3,5-triazin-2-yl group, 1-imidazolyl group, 2-imidazolyl group, 1- Pyrazolyl group, 1-indolidinyl group, 2-indolidinyl group, 3-indolidinyl group, 5-indolidinyl group, 6-indolidinyl group, 7-indolidinyl group, 8-indolidinyl group, 2-imidazopyridinyl group, 3-imidazopyri Zinyl group, 5-Imidazopyridinyl group, 6-Imidazopyridinyl group, 7-Imidazopyridinyl group, 8-Imidazopyridinyl group, 3-Pyridinyl group Group, 4-pyridinyl group, 1-indolyl group, 2-indolyl group, 3-indolyl group, 4-indolyl group, 5-indolyl group, 6-indolyl group, 7-indolyl group, 1-isoindolyl group, 2-isoindolyl group Group, 3-isoindolyl group, 4-isoindolyl group, 5-isoindolyl group, 6-isoindolyl group, 7-isoindolyl group, 2-furyl group, 3-furyl group, 2-benzofuranyl group, 3-benzofuranyl group, 4-benzofuranyl group Group, 5-benzofuranyl group, 6-benzofuranyl group, 7-benzofuranyl group, 1-isobenzofuranyl group, 3-isobenzofuranyl group, 4-isobenzofuranyl group, 5-isobenzofuranyl group, 6 -Isobenzofuranyl group, 7-isobenzofuranyl group, 2-quinolyl group, 3-quinolyl group, 4-quinolyl group 5-quinolyl group, 6-quinolyl group, 7-quinolyl group, 8-quinolyl group, 1-isoquinolyl group, 3-isoquinolyl group, 4-isoquinolyl group, 5-isoquinolyl group, 6-isoquinolyl group, 7-isoquinolyl group, 8-isoquinolyl group, 2-quinoxalinyl group, 5-quinoxalinyl group, 6-quinoxalinyl group, 1-carbazolyl group, 2-carbazolyl group, 3-carbazolyl group, 4-carbazolyl group, 9-carbazolyl group, azacarbazolyl-1-yl Group, azacarbazolyl-2-yl group, azacarbazolyl-3-yl group, azacarbazolyl-4-yl group, azacarbazolyl-5-yl group, azacarbazolyl-6-yl group, azacarbazolyl-7-yl group, azacarbazolyl-8-yl group Azacarbazolyl-9-yl group, 1-phenanthridinyl group, 2-phenanthridinyl group, 3-phenanthridinyl group, 4-phenanthridinyl group, 6-phenanthridinyl group, 7-phenanthridinyl group, 8-phenanthridinyl group, 9- Phenanthridinyl group, 10-phenanthridinyl group, 1-acridinyl group, 2-acridinyl group, 3-acridinyl group, 4-acridinyl group, 9-acridinyl group, 1,7-phenanthrolin-2-yl group, 1,7-phenanthroline-3-yl group, 1,7-phenanthroline-4-yl group, 1,7-phenanthroline-5-yl group, 1,7-phenanthroline-6-yl group, 1,7-phenanthroline- 8-yl group, 1,7-phenanthroline-9-yl group, 1,7-phenanthroline-10-yl group, 1,8-phenanthroline-2-yl group, 1,8-phene group Nthroline-3-yl group, 1,8-phenanthroline-4-yl group, 1,8-phenanthroline-5-yl group, 1,8-phenanthroline-6-yl group, 1,8-phenanthroline-7-yl group 1,8-phenanthroline-9-yl group, 1,8-phenanthroline-10-yl group, 1,9-phenanthroline-2-yl group, 1,9-phenanthroline-3-yl group, 1,9-phenanthroline -4-yl group, 1,9-phenanthroline-5-yl group, 1,9-phenanthroline-6-yl group, 1,9-phenanthroline-7-yl group, 1,9-phenanthroline-8-yl group, 1,9-phenanthroline-10-yl group, 1,10-phenanthroline-2-yl group, 1,10-phenanthroline-3-yl group, 1,10-phenanthrotrol -4-yl group, 1,10-phenanthroline-5-yl group, 2,9-phenanthroline-1-yl group, 2,9-phenanthroline-3-yl group, 2,9-phenanthroline-4-yl group, 2,9-phenanthroline-5-yl group, 2,9-phenanthroline-6-yl group, 2,9-phenanthroline-7-yl group, 2,9-phenanthroline-8-yl group, 2,9-phenanthroline- 10-yl group, 2,8-phenanthroline-1-yl group, 2,8-phenanthroline-3-yl group, 2,8-phenanthroline-4-yl group, 2,8-phenanthroline-5-yl group, 2 , 8-phenanthroline-6-yl group, 2,8-phenanthroline-7-yl group, 2,8-phenanthroline-9-yl group, 2,8-phenanthroline-10-yl group, 2,7-phenanthroline-1-yl group, 2,7-phenanthroline-3-yl group, 2,7-phenanthroline-4-yl group, 2,7-phenanthroline-5-yl group, 2,7-phenanthroline- 6-yl group, 2,7-phenanthroline-8-yl group, 2,7-phenanthroline-9-yl group, 2,7-phenanthroline-10-yl group, 1-phenazinyl group, 2-phenazinyl group, 1- Phenothiazinyl group, 2-phenothiazinyl group, 3-phenothiazinyl group, 4-phenothiazinyl group, 10-phenothiazinyl group, 1-phenoxazinyl group, 2-phenoxazinyl group, 3-phenoxazinyl group, 4-phenoxazinyl group, 10- Phenoxazinyl group, 2-oxazolyl group, 4-oxazolyl group, 5-oxazolyl group, 2-oxadiazo group Group, 5-oxadiazolyl group, 3-furazanyl group, 2-thienyl group, 3-thienyl group, 2-methylpyrrol-1-yl group, 2-methylpyrrol-3-yl group, 2-methylpyrrole-4- Yl group, 2-methylpyrrol-5-yl group, 3-methylpyrrol-1-yl group, 3-methylpyrrol-2-yl group, 3-methylpyrrol-4-yl group, 3-methylpyrrol-5- Yl group, 2-t-butylpyrrol-4-yl group, 3- (2-phenylpropyl) pyrrol-1-yl group, 2-methyl-1-indolyl group, 4-methyl-1-indolyl group, 2- Methyl-3-indolyl group, 4-methyl-3-indolyl group, 2-t-butyl-1-indolyl group, 4-t-butyl-1-indolyl group, 2-t-butyl-3-indolyl group, 4 -T-butyl-3- Ndryl group, 1-dibenzofuranyl group, 2-dibenzofuranyl group, 3-dibenzofuranyl group, 4-dibenzofuranyl group, 1-dibenzothiophenyl group, 2-dibenzothiophenyl group, 3-dibenzothiophenyl group Group, 4-dibenzothiophenyl group, 1-silafluorenyl group, 2-silafluorenyl group, 3-silafluorenyl group, 4-silafluorenyl group, 1-germafluorenyl group, 2-germafluorenyl group, 3-germafluorenyl group Nyl group and 4-germafluorenyl group are mentioned.

  Examples of the linear, branched, or cyclic alkyl group having 1 to 30 carbon atoms in the general formula (1) include, for example, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, s-butyl group, Isobutyl group, t-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n- Tridecyl group, n-tetradecyl group, n-pentadecyl group, 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-methylpentyl group, hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 2-hydroxy Loxyisobutyl group, 1,2-dihydroxyethyl group, 1,3-dihydroxyisopropyl group, 2,3-dihydroxy-t-butyl group, 1,2,3-trihydroxypropyl group, chloromethyl group, 1-chloroethyl group 2-chloroethyl group, 2-chloroisobutyl group, 1,2-dichloroethyl group, 1,3-dichloroisopropyl group, 2,3-dichloro-t-butyl group, 1,2,3-trichloropropyl group, bromomethyl Group, 1-bromoethyl group, 2-bromoethyl group, 2-bromoisobutyl group, 1,2-dibromoethyl group, 1,3-dibromoisopropyl group, 2,3-dibromo-t-butyl group, 1,2,3 -Tribromopropyl group, iodomethyl group, 1-iodoethyl group, 2-iodoethyl group, 2-iodoisobutyl group, 1,2-diiodo Til group, 1,3-diiodoisopropyl group, 2,3-diiodo-t-butyl group, 1,2,3-triiodopropyl group, aminomethyl group, 1-aminoethyl group, 2-aminoethyl group, 2-aminoisobutyl group, 1,2-diaminoethyl group, 1,3-diaminoisopropyl group, 2,3-diamino-t-butyl group, 1,2,3-triaminopropyl group, cyanomethyl group, 1-cyanoethyl Group, 2-cyanoethyl group, 2-cyanoisobutyl group, 1,2-dicyanoethyl group, 1,3-dicyanoisopropyl group, 2,3-dicyano-t-butyl group, 1,2,3-tricyanopropyl group Nitromethyl group, 1-nitroethyl group, 2-nitroethyl group, 1,2-dinitroethyl group, 2,3-dinitro-t-butyl group, 1,2,3-trinitropropyl group, etc. I can get lost.

  Examples of the alkoxy group having 1 to 30 carbon atoms in the general formula (1) include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentyloxy group, and a hexyloxy group.

  The aryloxy group having 6 to 30 ring carbon atoms in the general formula (1) is a group represented by -OAr. Here, specific examples of Ar include the same as those described for the aromatic hydrocarbon group.

  Examples of the aralkyl group having 7 to 30 carbon atoms in the general formula (1) include benzyl group, 1-phenylethyl group, 2-phenylethyl group, 1-phenylisopropyl group, 2-phenylisopropyl group, and phenyl-t-. Butyl group, α-naphthylmethyl group, 1-α-naphthylethyl group, 2-α-naphthylethyl group, 1-α-naphthylisopropyl group, 2-α-naphthylisopropyl group, β-naphthylmethyl group, 1-β -Naphthylethyl group, 2-β-naphthylethyl group, 1-β-naphthylisopropyl group, 2-β-naphthylisopropyl group, 1-pyrrolylmethyl group, 2- (1-pyrrolyl) ethyl group, p-methylbenzyl group, m-methylbenzyl group, o-methylbenzyl group, p-chlorobenzyl group, m-chlorobenzyl group, o-chlorobenzyl group, p-bromobenzyl group Gyl group, m-bromobenzyl group, o-bromobenzyl group, p-iodobenzyl group, m-iodobenzyl group, o-iodobenzyl group, p-hydroxybenzyl group, m-hydroxybenzyl group, o-hydroxybenzyl group P-aminobenzyl group, m-aminobenzyl group, o-aminobenzyl group, p-nitrobenzyl group, m-nitrobenzyl group, o-nitrobenzyl group, p-cyanobenzyl group, m-cyanobenzyl group, o -Cyanobenzyl group, 1-hydroxy-2-phenylisopropyl group, 1-chloro-2-phenylisopropyl group and the like.

  Examples of the haloalkyl group having 1 to 30 carbon atoms in the general formula (1) include those in which the alkyl group having 1 to 30 carbon atoms is substituted with one or more halogen groups.

  Examples of the haloalkoxy group having 1 to 30 carbon atoms in the general formula (1) include those in which the alkoxy group having 1 to 30 carbon atoms is substituted with one or more halogen groups.

  Examples of the trialkylsilyl group having 3 to 30 carbon atoms in the general formula (1) include a trialkylsilyl group having an alkyl group exemplified as the alkyl group having 1 to 30 carbon atoms, specifically, trimethylsilyl. Group, triethylsilyl group, tri-n-butylsilyl group, tri-n-octylsilyl group, triisobutylsilyl group, dimethylethylsilyl group, dimethylisopropylsilyl group, dimethyl-n-propylsilyl group, dimethyl-n-butylsilyl group Dimethyl-t-butylsilyl group, diethylisopropylsilyl group and the like. The three alkyl groups may be the same or different from each other.

  The dialkylarylsilyl group having 8 to 40 carbon atoms in the general formula (1) has, for example, two alkyl groups exemplified as the alkyl group having 1 to 30 carbon atoms, and has 6 to 30 ring carbon atoms. A dialkylarylsilyl group having one aromatic hydrocarbon group can be mentioned.

  The alkyl diarylsilyl group having 13 to 50 carbon atoms in the general formula (1) has, for example, one alkyl group exemplified as the alkyl group having 1 to 30 carbon atoms, and has 6 to 30 ring carbon atoms. An alkyldiarylsilyl group having two aromatic hydrocarbon groups can be mentioned.

  Examples of the triarylsilyl group having 18 to 60 carbon atoms in the general formula (1) include a triarylsilyl group having three aromatic hydrocarbon groups having 6 to 30 ring carbon atoms.

L ₃ in the general formula (1) is preferably a single bond.

The nitrogen-containing aromatic heterocyclic group as A ₁ or A ₂ in the general formula (1) is preferably a substituted or unsubstituted pyrimidinyl group or a substituted or unsubstituted triazinyl group. Examples of the pyrimidinyl group include a 2-pyrimidinyl group, a 4-pyrimidinyl group, a 5-pyrimidinyl group, and a 6-pyrimidinyl group. A triazinyl group is a group formed from a triazine ring, and there are three types of triazine rings: 1,2,3-triazine, 1,2,4-triazine, and 1,3,5-triazine. Examples of the triazinyl group include a 1,2,3-triazin-4-yl group, a 1,2,4-triazin-3-yl group, and a 1,3,5-triazin-2-yl group.
By attaching a pyrimidinyl group or triazinyl group to the position of A ₁ or A ₂ , for example, compared with other nitrogen-containing aromatic heterocyclic groups, for example, holes of biscarbazole derivatives And resistance to electrons is considered to be improved.

At least one of L ₁ and L ₂ in the general formula (1) is a single bond, a divalent group of a substituted or unsubstituted aromatic hydrocarbon compound having 6 to 30 ring carbon atoms, and a substituted or unsubstituted group. It is preferably any one of divalent groups of an aromatic heterocyclic compound having 1 to 30 ring carbon atoms.
When at least one of L ₁ and L ₂ is a single bond, hole transportability is improved.
At least one of L ₁ and L ₂ is a divalent group of a substituted or unsubstituted aromatic hydrocarbon compound having 6 to 30 ring carbon atoms, or a substituted or unsubstituted aromatic complex having 1 to 30 ring carbon atoms. When it is a divalent group of a cyclic compound, the electron transport property tends to be improved.
Therefore, it is desirable to select L ₁ and L ₂ as appropriate for the purpose of adjusting the balance of carrier transport properties of the biscarbazole derivative. Thus, selecting L ₁ and L ₂ as appropriate is also effective when the biscarbazole derivative of the present invention is used as a host material.

  Specific examples of the structure of the biscarbazole derivative of the present invention include the following. However, the present invention is not limited to biscarbazole derivatives having these structures.

(Materials for organic EL elements)
The biscarbazole derivative of the present invention can be used as a material for an organic EL device. The organic EL device material may contain the biscarbazole derivative of the present invention alone or may contain other compounds.

(Configuration of organic EL element)
The organic EL device of the present invention includes an organic compound layer between a cathode and an anode.
The biscarbazole derivative of the present invention is included in the organic compound layer. The organic compound layer is formed using an organic EL element material containing the biscarbazole derivative of the present invention.
The organic compound layer has at least one organic thin film layer composed of an organic compound. The organic thin film layer may contain an inorganic compound.
In the organic EL device of the present invention, at least one of the organic thin film layers is a light emitting layer. Therefore, the organic compound layer may be composed of, for example, a single light emitting layer, such as a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, a hole barrier layer, an electron barrier layer, etc. You may have the layer employ | adopted by a well-known organic EL element. If there are a plurality of organic thin film layers, at least one of the layers contains the biscarbazole derivative of the present invention.

As a typical element configuration of the organic EL element,
(A) Anode / light emitting layer / cathode (b) Anode / hole injection / transport layer / light emitting layer / cathode (c) Anode / light emitting layer / electron injection / transport layer / cathode (d) Anode / hole injection / transport Layer / light emitting layer / electron injection / transport layer / cathode (e) Structure of anode / hole injection / transport layer / light emitting layer / barrier layer / electron injection / transport layer / cathode.
Among the above, the configuration (d) is preferably used, but it is of course not limited thereto.
The “light emitting layer” is an organic layer having a light emitting function, and includes a host material and a dopant material when a doping system is employed. At this time, the host material mainly has a function of encouraging recombination of electrons and holes and confining excitons in the light emitting layer, and the dopant material efficiently emits excitons obtained by recombination. It has a function. In the case of a phosphorescent element, the host material mainly has a function of confining excitons generated by the dopant in the light emitting layer.
The above “hole injection / transport layer” means “at least one of a hole injection layer and a hole transport layer”, and “electron injection / transport layer” means “an electron injection layer and an electron transport layer”. "At least one of them". Here, when it has a positive hole injection layer and a positive hole transport layer, it is preferable that the positive hole injection layer is provided in the anode side. Moreover, when it has an electron injection layer and an electron carrying layer, it is preferable that the electron injection layer is provided in the cathode side.
In the present invention, the electron transport layer refers to an organic layer having the highest electron mobility among the organic layers in the electron transport region existing between the light emitting layer and the cathode. When the electron transport region is composed of one layer, the layer is an electron transport layer. In addition, in the phosphorescent device, as shown in the configuration (e), a barrier layer that does not necessarily have high electron mobility is used between the light emitting layer and the electron transport layer in order to prevent diffusion of excitation energy generated in the light emitting layer. The organic layer adjacent to the light emitting layer does not necessarily correspond to the electron transport layer.

In FIG. 1, schematic structure of an example of the organic EL element in embodiment of this invention is shown.
The organic EL element 1 includes a transparent substrate 2, an anode 3, a cathode 4, and an organic compound layer 10 disposed between the anode 3 and the cathode 4.
The organic compound layer 10 includes a hole injection layer 5, a hole transport layer 6, a light emitting layer 7, an electron transport layer 8, and an electron injection layer 9 in order from the anode 3 side.

(Transparent substrate)
The organic EL element of the present invention is produced on a light-transmitting substrate. The translucent substrate referred to here is a substrate that supports the organic EL element, and is preferably a smooth substrate having a light transmittance in the visible region of 400 nm to 700 nm of 50% or more.
Specifically, a glass plate, a polymer plate, etc. are mentioned.
Examples of the glass plate include those using soda lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, quartz and the like as raw materials.
Examples of the polymer plate include those using polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, polysulfone and the like as raw materials.

(Anode and cathode)
The anode of the organic EL element plays a role of injecting holes into the hole injection layer, the hole transport layer, or the light emitting layer, and it is effective to have a work function of 4.5 eV or more.
Specific examples of the anode material include indium tin oxide alloy (ITO), tin oxide (NESA), indium zinc oxide, gold, silver, platinum, copper, and the like.
The anode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering.
When light emitted from the light emitting layer is extracted from the anode as in the present embodiment, it is preferable that the light transmittance in the visible region of the anode be greater than 10%. The sheet resistance of the anode is preferably several hundred Ω / □ or less. The film thickness of the anode depends on the material, but is usually selected in the range of 10 nm to 1 μm, preferably 10 nm to 200 nm.

As the cathode, a material having a small work function is preferable for the purpose of injecting electrons into the electron injection layer, the electron transport layer, or the light emitting layer.
The cathode material is not particularly limited, and specifically, indium, aluminum, magnesium, magnesium-indium alloy, magnesium-aluminum alloy, aluminum-lithium alloy, aluminum-scandium-lithium alloy, magnesium-silver alloy and the like can be used.
Similarly to the anode, the cathode can be produced by forming a thin film by a method such as vapor deposition or sputtering. Moreover, the aspect which takes out light emission from a cathode side is also employable.

(Light emitting layer)
The light emitting layer is preferably a molecular deposited film.
Here, the molecular deposited film is a thin film formed by deposition from a material compound in a gas phase state or a film formed by solidifying from a material compound in a solution state or a liquid phase state. Can be classified from a thin film (accumulated film) formed by the LB method according to a difference in an agglomerated structure and a higher-order structure and a functional difference resulting therefrom.
Further, as disclosed in JP-A-57-51781, a binder such as a resin and a material compound are dissolved in a solvent to form a solution, and then this is thinned by a spin coating method or the like. In addition, a light emitting layer can be formed.

(Host material)
The host material is preferably the biscarbazole derivative of the present invention. As described above, since the biscarbazole derivative of the present invention is excellent in resistance to holes and electrons, the durability of the organic EL element can be improved by using it as a host material.

(Dopant material)
The dopant material is selected from a known fluorescent material exhibiting fluorescence emission or a phosphorescent material exhibiting phosphorescence emission.
Fluorescent materials used as dopant materials (hereinafter referred to as fluorescent dopant materials) are selected from fluoranthene derivatives, pyrene derivatives, arylacetylene derivatives, fluorene derivatives, boron complexes, perylene derivatives, oxadiazole derivatives, and anthracene derivatives. It is. Preferably, a fluoranthene derivative, a pyrene derivative, and a boron complex are used.

A phosphorescent material used as a dopant material (hereinafter referred to as a phosphorescent dopant material) preferably contains a metal complex. The metal complex has a metal atom selected from iridium (Ir), platinum (Pt), osmium (Os), gold (Au), rhenium (Re), and ruthenium (Ru) and a ligand. Is preferred. In particular, an orthometalated complex in which a ligand and a metal atom form an orthometal bond is preferable. The phosphorescent dopant material contains a metal selected from iridium (Ir), osmium (Os) and platinum (Pt) in that the phosphorescent quantum yield is high and the external quantum efficiency of the light emitting device can be further improved. Ortho-metalated complexes are preferred. From the viewpoint of luminous efficiency, a metal complex composed of a ligand selected from phenylquinoline, phenylisoquinoline, phenylpyridine, phenylpyrimidine, phenylpyrazine and phenylimidazole is preferable.
Specific examples of the phosphorescent dopant material are shown below.

  Since the biscarbazole derivative of the present invention has the structure as described above, it has a property that triplet energy EgT is smaller than that of a biscarbazole derivative in which the 3-positions of the carbazolyl group are bonded to each other. Therefore, when the biscarbazole derivative of the present invention is used as a phosphorescent host material in the light emitting layer of the organic EL element of the present invention, a phosphorescent material that emits phosphorescence in the red to yellow-green wavelength region may be used as the phosphorescent dopant material. preferable. In the phosphorescent element, by using such a combination of the phosphorescent dopant material and the phosphorescent host material, the phosphorescent host material can efficiently confine the triplet energy of the phosphorescent dopant material, and the light emission efficiency is improved.

(Other materials included in the light emitting layer)
The light emitting layer of the organic EL device of the present invention preferably further contains an aromatic amine derivative. The light emitting layer includes an aromatic amine derivative in addition to the biscarbazole derivative and the dopant material of the present invention as a host material, so that hole injection and hole transport are assisted. Easier to balance.
Examples of such aromatic amine derivatives include compounds used in the following hole injection / transport layers.

(Hole injection / 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.
The hole injection / transport layer may be constituted by a hole injection layer or a hole transport layer, or may be constituted by laminating a hole injection layer and a hole transport layer.
As a material for forming the hole injecting / transporting layer, a material that transports holes to the light emitting layer with lower electric field strength is preferable, and an aromatic amine compound, for example, an aromatic amine derivative represented by the following general formula (A1) Are preferably used.

In the general formula (A1), Ar ¹ to Ar ⁴ are
An aromatic hydrocarbon group having 6 to 50 ring carbon atoms,
An aromatic heterocyclic group having 2 to 40 ring carbon atoms,
A group in which the aromatic hydrocarbon group and the aromatic heterocyclic group are bonded,
It represents a group in which these aromatic hydrocarbon groups and these condensed aromatic heterocyclic groups are bonded. However, the aromatic hydrocarbon group and aromatic heterocyclic group mentioned here may have a substituent.

In the general formula (A1), L is a linking group,
A divalent aromatic hydrocarbon group having 6 to 50 ring carbon atoms,
A single bond of a divalent aromatic heterocyclic group having 5 to 50 ring carbon atoms, or two or more aromatic hydrocarbon groups or aromatic heterocyclic groups,
Ether bond,
Thioether bond,
An alkylene group having 1 to 20 carbon atoms,
An alkenylene group having 2 to 20 carbon atoms, or a divalent group obtained by bonding with an amino group,
Represents. However, the divalent aromatic hydrocarbon group and divalent aromatic heterocyclic group mentioned here may have a substituent.

  Specific examples of the compound of the general formula (A1) are shown below, but are not limited thereto.

  Moreover, the aromatic amine of the following general formula (A2) is also suitably used for forming the hole injection / transport layer.

In the general formula (A2), the definitions from Ar ¹ to Ar ³ are the same as the definitions from Ar ¹ to Ar ^{4 in} the general formula (A1). Although the specific example of a compound of general formula (A2) is described below, it is not limited to these.

(Electron injection / transport layer)
The electron injection / transport layer is a layer that assists injection of electrons into the light emitting layer, and has a high electron mobility. The electron injection layer is provided to adjust the energy level, for example, to alleviate a sudden change in the energy level. The electron injection / transport layer includes at least one of an electron injection layer and an electron transport layer.
This embodiment preferably has an electron injection layer between the light emitting layer and the cathode, and the electron injection layer preferably contains a nitrogen-containing ring derivative as a main component. Here, the electron injection layer may be a layer that functions as an electron transport layer.
“As a main component” means that the electron injection layer contains 50% by mass or more of a nitrogen-containing ring derivative.

As the electron transporting material used for the electron injection layer, an aromatic heterocyclic compound containing at least one hetero atom 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 a 5-membered ring skeleton.
As this nitrogen-containing ring derivative, for example, a nitrogen-containing ring metal chelate complex represented by the following general formula (B1) is preferable.

R ² to R ⁷ in the general formula (B1) are independently
Hydrogen atom,
Deuterium atom,
Halogen atoms,
An oxy group,
An amino group,
A hydrocarbon group having 1 to 40 carbon atoms,
An alkoxy group,
An aryloxy group,
An alkoxycarbonyl group, or
An aromatic heterocyclic group,
These may have a substituent.
Examples of the halogen atom include fluorine, chlorine, bromine and iodine. Examples of the optionally substituted amino group include an alkylamino group, an arylamino group, and an aralkylamino group.

The alkoxycarbonyl group is represented as —COOY ′, and examples of Y ′ include the same as the alkyl group. The alkylamino group and the aralkylamino group are represented as —NQ ¹ Q ² . Specific examples of Q ¹ and Q ² are the same as those described above for the alkyl group and the aralkyl group (a group in which a hydrogen atom of the alkyl group is substituted with an aryl group). Preferred examples Is the same. One of Q ¹ and Q ² may be a hydrogen atom. The aralkyl group is a group in which a hydrogen atom of the alkyl group is substituted with the aryl group.
The arylamino group is represented by —NAr ¹ Ar ^2, and specific examples of Ar ¹ and Ar ² are the same as those described for the non-condensed aromatic hydrocarbon group. One of Ar ¹ and Ar ² may be a hydrogen atom.

M is aluminum (Al), gallium (Ga) or indium (In), and is preferably In.
L in the general formula (B1) is a group represented by the following general formula (B2) or (B3).

In the general formula (B2), R ⁸ to R ¹² are independently
A hydrogen atom or a hydrocarbon group having 1 to 40 carbon atoms, and groups adjacent to each other may form a cyclic structure. This hydrocarbon group may have a substituent.
In the general formula (B3), R ¹³ to R ²⁷ are independently
A hydrogen atom or a hydrocarbon group having 1 to 40 carbon atoms,
Adjacent groups may form a cyclic structure. This hydrocarbon group may have a substituent.
Examples of the hydrocarbon group having 1 to 40 carbon atoms represented by R ⁸ to R ¹² and R ¹³ to R ^{27 in the} general formula (B2) and the general formula (B3) include those in the general formula (B1). those from R ² similar to the specific examples to R ⁷ can be exemplified.
In addition, as the divalent group in the case where the groups adjacent to each other from R ⁸ to R ¹² and R ¹³ to R ²⁷ form a cyclic structure, a tetramethylene group, a pentamethylene group, a hexamethylene group, diphenylmethane- A 2,2′-diyl group, a diphenylethane-3,3′-diyl group, a diphenylpropane-4,4′-diyl group and the like can be mentioned.

  Moreover, it is preferable that an electron carrying layer contains at least any one of the nitrogen-containing heterocyclic derivative represented by the following general formula (B4) to (B6).

In the general formulas (B4) to (B6), R is
Hydrogen atom,
An aromatic hydrocarbon group having 6 to 60 ring carbon atoms,
Pyridyl group,
A quinolyl group,
An alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms.
n is an integer of 0 or more and 4 or less.

In the general formulas (B4) to (B6), R ¹ is
Aromatic hydrocarbon group having 6 to 60 ring carbon atoms, pyridyl group,
A quinolyl group,
An alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms.

In the general formulas (B4) to (B6), R ² and R ³ are independently
Hydrogen atom,
Aromatic hydrocarbon group having 6 to 60 ring carbon atoms, pyridyl group,
A quinolyl group,
An alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms.

In the general formulas (B4) to (B6), L is
An aromatic hydrocarbon group having 6 to 60 ring carbon atoms, a pyridinylene group,
It is a quinolinylene group or a fluorenylene group.

In the general formulas (B4) to (B6), Ar ¹ is
An aromatic hydrocarbon group having 6 to 60 ring carbon atoms, a pyridinylene group,
It is a quinolinylene group.

In the general formulas (B4) to (B6), Ar ² is
Aromatic hydrocarbon group having 6 to 60 ring carbon atoms, pyridyl group,
A quinolyl group,
An alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms.

In the general formulas (B4) to (B6), Ar ³ is
Aromatic hydrocarbon group having 6 to 60 ring carbon atoms, pyridyl group,
A quinolyl group,
An alkyl group having 1 to 20 carbon atoms,
An alkoxy group having 1 to 20 carbon atoms or a group represented by “—Ar ¹ —Ar ² ” (Ar ¹ and Ar ² are the same as described above).

In addition, the aromatic hydrocarbon groups mentioned in the description of R, R ¹ , R ² , R ³ , L, Ar ¹ , Ar ² , and Ar ^{3 in} the general formulas (B4) to (B6), The pyridyl group, quinolyl group, alkyl group, alkoxy group, pyridinylene group, quinolinylene group, and fluorenylene group may have a substituent.

  As the electron transporting compound used for the electron injecting layer or the electron transporting layer, a metal complex of 8-hydroxyquinoline or a derivative thereof, an oxadiazole derivative, or a nitrogen-containing heterocyclic derivative is preferable. As a specific example of the metal complex of the 8-hydroxyquinoline or its derivative, a metal chelate oxinoid compound containing a chelate of oxine (generally 8-quinolinol or 8-hydroxyquinoline), for example, tris (8-quinolinol) aluminum is used. Can do. And as an oxadiazole derivative, the following can be mentioned.

In each general formula of these oxadiazole derivatives, Ar ¹⁷ , Ar ¹⁸ , Ar ¹⁹ , Ar ²¹ , Ar ²² and Ar ²⁵ are
An aromatic hydrocarbon group having 6 to 40 ring carbon atoms.
However, the aromatic hydrocarbon group mentioned here may have a substituent. Ar ¹⁷ and Ar ¹⁸ , Ar ¹⁹ and Ar ²¹ , Ar ²² and Ar ²⁵ may be the same as or different from each other.
Examples of the aromatic hydrocarbon group mentioned here include a phenyl group, a naphthyl group, a biphenyl group, an anthranyl group, a perylenyl group, and a pyrenyl group. And as a substituent to these, a C1-C10 alkyl group, a C1-C10 alkoxy group, a cyano group, etc. are mentioned.

In each general formula of these oxadiazole derivatives, Ar ²⁰ , Ar ²³ and Ar ²⁴ are
A divalent aromatic hydrocarbon group having 6 to 40 ring carbon atoms.
However, the aromatic hydrocarbon group mentioned here may have a substituent.
Ar ²³ and Ar ²⁴ may be the same as or different from each other.
Examples of the divalent aromatic hydrocarbon group mentioned here include a phenylene group, a naphthylene group, a biphenylene group, an anthranylene group, a peryleneylene group, and a pyrenylene group. And as a substituent to these, a C1-C10 alkyl group, a C1-C10 alkoxy group, a cyano group, etc. are mentioned.

  As these electron transfer compounds, those having good thin film forming properties are preferably used. Specific examples of these electron transfer compounds include the following.

  The nitrogen-containing heterocyclic derivative as the electron transfer compound is a nitrogen-containing heterocyclic derivative composed of an organic compound having the following general formula, and includes a nitrogen-containing compound that is not a metal complex. For example, a 5-membered or 6-membered ring containing a skeleton represented by the following general formula (B7) and a structure represented by the following general formula (B8) can be given.

In the general formula (B8), X represents a carbon atom or a nitrogen atom. Z ₁ and Z ₂ each independently represents an atomic group capable of forming a nitrogen-containing heterocycle.

  The nitrogen-containing heterocyclic derivative is more preferably an organic compound having a nitrogen-containing aromatic polycyclic group consisting of a 5-membered ring or a 6-membered ring. Further, in the case of such a nitrogen-containing aromatic polycyclic group having a plurality of nitrogen atoms, a skeleton combining the above general formulas (B7) and (B8) or the above general formula (B7) and the following general formula (B9) is used. The nitrogen-containing aromatic polycyclic organic compound having is preferable.

  The nitrogen-containing group of the nitrogen-containing aromatic polycyclic organic compound is selected from, for example, nitrogen-containing heterocyclic groups represented by the following general formula.

In each general formula of these nitrogen-containing heterocyclic groups, R is
An aromatic hydrocarbon group having 6 to 40 ring carbon atoms,
An aromatic heterocyclic group having 2 to 40 ring carbon atoms,
An alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms.
In each general formula of these nitrogen-containing heterocyclic groups, n is an integer of 0 or more and 5 or less, and when n is an integer of 2 or more, a plurality of R may be the same or different from each other.

Furthermore, preferred specific compounds include nitrogen-containing heterocyclic derivatives represented by the following general formula (B10).
HAr-L ¹ -Ar ¹ -Ar ² (B10)
In the general formula (B10), HAr is
A nitrogen-containing heterocyclic group having 1 to 40 ring carbon atoms.
In the general formula (B10), L ¹ is
Single bond,
An aromatic hydrocarbon group having 6 to 40 ring carbon atoms or an aromatic heterocyclic group having 2 to 40 ring carbon atoms.

In the general formula (B10), Ar ¹ is
A divalent aromatic hydrocarbon group having 6 to 40 ring carbon atoms.
In the general formula (B10), Ar ² is
An aromatic hydrocarbon group having 6 to 40 ring carbon atoms or an aromatic heterocyclic group having 2 to 40 ring carbon atoms.

Further, the nitrogen-containing heterocyclic group, condensed aromatic hydrocarbon group, condensed aromatic hydrocarbon group, aromatic mentioned in the description of HAr, L ¹ , Ar ¹ , and Ar ^{2 in} the general formula (B10) The heterocyclic group and the condensed aromatic heterocyclic group may have a substituent.

  HAr in the formula of the general formula (B10) is selected from the following group, for example.

L ¹ in the formula (B10) is, for example, selected from the following group.

Ar ¹ in the formula (B10) is, for example, selected from the following arylanthranyl groups.

In the general formula of the arylanthranyl group, R ¹ to R ¹⁴ are independently
Hydrogen atom,
Halogen atoms,
An alkyl group having 1 to 20 carbon atoms,
An alkoxy group having 1 to 20 carbon atoms,
An aryloxy group having 6 to 40 ring carbon atoms,
An aromatic hydrocarbon group having 6 to 40 ring carbon atoms or an aromatic heterocyclic group having 2 to 40 ring carbon atoms.

In the general formula of the arylanthranyl group, Ar ³ is
An aromatic hydrocarbon group having 6 to 40 ring carbon atoms or an aromatic heterocyclic group having 2 to 40 ring carbon atoms.

However, R ¹ to R ^{14 in} the general formula of the arylanthranyl group, and the aromatic hydrocarbon group and aromatic heterocyclic group mentioned in the description of Ar ³ may have a substituent.
Further, any of R ¹ to R ⁸ may be a nitrogen-containing heterocyclic derivative which is a hydrogen atom.

In the general formula of the arylanthranyl group, Ar ² is selected from the following group, for example.

  In addition to the nitrogen-containing aromatic polycyclic organic compound as the electron transfer compound, the following compounds (see JP-A-9-3448) are also preferably used.

In the general formula of this nitrogen-containing aromatic polycyclic organic compound, R ¹ to R ⁴ are independently
Hydrogen atom,
Aliphatic groups,
An aliphatic cyclic group,
Represents a carbocyclic aromatic ring group or a heterocyclic group. However, the aliphatic group, aliphatic cyclic group, carbocyclic aromatic ring group, and heterocyclic group mentioned here may have a substituent.
In the general formula of this nitrogen-containing aromatic polycyclic organic compound, X ¹ and X ² independently represent an oxygen atom, a sulfur atom, or a dicyanomethylene group.

  In addition, the following compounds (see Japanese Patent Application Laid-Open No. 2000-173774) are also preferably used as the electron transfer compound.

In the general formula, R ¹ , R ² , R ^3, and R ⁴ are the same or different groups, and are an aromatic hydrocarbon group or a condensed aromatic hydrocarbon group represented by the following general formula.

In the above general formula, R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ⁹ are the same or different groups, and hydrogen atom or at least one of them is a saturated or unsaturated alkoxyl group, alkyl group, amino group A group or an alkylamino group.

  Further, the electron transport compound may be a polymer compound containing the nitrogen-containing heterocyclic group or the nitrogen-containing heterocyclic derivative.

The thickness of the electron injection layer or the electron transport layer is not particularly limited, but is preferably 1 nm or more and 100 nm or less.
Moreover, as a constituent component of the electron injection layer, it is preferable to use an insulator or a semiconductor as an inorganic compound in addition to the nitrogen-containing ring derivative. If the electron injection layer is made of an insulator or a semiconductor, current leakage can be effectively prevented and the electron injection property can be improved.

As such an insulator, it is preferable to use at least one metal compound selected from the group consisting of alkali metal chalcogenides, alkaline earth metal chalcogenides, alkali metal halides and alkaline earth metal halides. If the electron injection layer is composed of these alkali metal chalcogenides or the like, it is preferable in that the electron injection property can be further improved. Specifically, preferred alkali metal chalcogenides include, for example, lithium oxide (Li ₂ O), potassium oxide (K ₂ O), sodium sulfide (Na ₂ S), sodium selenide (Na ₂ Se), and sodium oxide (Na ₂ O). Preferred alkaline earth metal chalcogenides include, for example, calcium oxide (CaO), barium oxide (BaO), strontium oxide (SrO), beryllium oxide (BeO), barium sulfide (BaS), and calcium selenide (CaSe). . Examples of preferable alkali metal halides include lithium fluoride (LiF), sodium fluoride (NaF), potassium fluoride (KF), lithium chloride (LiCl), potassium chloride (KCl), and sodium chloride (NaCl). ) And the like. Examples of preferable alkaline earth metal halides include calcium fluoride (CaF ₂ ), barium fluoride (BaF ₂ ), strontium fluoride (SrF ₂ ), magnesium fluoride (MgF ₂ ), and beryllium fluoride. Examples thereof include fluorides such as (BeF ₂ ) and halides other than fluorides.

Moreover, as a semiconductor, barium (Ba), calcium (Ca), strontium (Sr), ytterbium (Yb), aluminum (Al), gallium (Ga), indium (In), lithium (Li), sodium (Na) , Cadmium (Cd), magnesium (Mg), silicon (Si), tantalum (Ta), antimony (Sb), oxide containing at least one element of zinc (Zn), nitride or oxynitride alone Or the combination of 2 or more types is mentioned. In addition, the inorganic compound constituting the electron injection layer is preferably a microcrystalline or amorphous insulating thin film. If the electron injection layer is composed of these insulating thin films, a more uniform thin film is formed, so that pixel defects such as dark spots can be reduced. Examples of such inorganic compounds include alkali metal chalcogenides, alkaline earth metal chalcogenides, alkali metal halides, and alkaline earth metal halides.
When such an insulator or semiconductor is used, the preferable thickness of the layer is about 0.1 nm to 15 nm. Moreover, even if the electron injection layer in this invention contains the above-mentioned reducing dopant, it is preferable.

(Electron donating dopant and organometallic complex)
The organic EL device of the present invention preferably has at least one of an electron donating dopant and an organometallic complex in an 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. Of these, K, Rb and Cs are preferred, Rb or Cs is 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), such as terbium fluoride (TbF ₃₎ can be _{mentioned, YbF 3, ScF 3, TbF} 3 are preferable.

  As described above, the organometallic complex is not particularly limited as long as it contains at least one of alkali metal ions, alkaline earth metal ions, and rare earth metal ions as metal ions. In addition, the ligand includes quinolinol, benzoquinolinol, acridinol, phenanthridinol, hydroxyphenyl oxazole, hydroxyphenyl thiazole, hydroxydiaryl oxadiazole, hydroxydiaryl thiadiazole, hydroxyphenyl pyridine, hydroxyphenyl benzimidazole, hydroxybenzotriazole, Hydroxyfulborane, bipyridyl, phenanthroline, phthalocyanine, porphyrin, cyclopentadiene, β-diketones, azomethines, and derivatives thereof are preferable, but not limited thereto.

The addition form of the electron donating dopant and the organometallic complex is preferably formed in a layered or island shape 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 which is a light-emitting material or an electron injection material for forming an interface region is vapor-deposited at the same time. A method of dispersing at least one of the donor dopant and the organometallic complex is preferable. The dispersion concentration is organic substance: electron-donating dopant, organometallic complex = 100: 1 to 1: 100, preferably 5: 1 to 1: 5 in molar ratio.
When forming at least one of the electron donating dopant and the organometallic complex in a layered form, after forming the light emitting material or the electron injecting material as 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 the electron donating dopant and the organometallic complex is formed in an island shape, after the light emitting material or the electron injecting material, which is the organic layer at the interface, is formed in an island shape, the electron donating dopant and the organometallic complex 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 the main component to at least one of the electron donating dopant and the organometallic complex is, as a molar ratio, the main component: the electron donating dopant, the organometallic complex = 5: 1 to 1. Is preferably up to 5, more preferably from 2: 1 to 1: 2.

(Method for forming each layer of organic EL element)
The formation method of each layer of the organic EL element of the present invention is not particularly limited. Conventionally known methods such as vacuum deposition and spin coating can be used. The organic compound layer containing the compound represented by the general formula (1) used in the organic EL device of the present invention is a vacuum deposition method, a molecular beam deposition method (MBE method) or a dipping method of a solution dissolved in a solvent, It can be formed by a known method such as a spin coating method, a casting method, a bar coating method, or a roll coating method.

(Thickness of each layer of organic EL element)
The thickness of the light emitting layer is preferably 5 nm to 50 nm, more preferably 7 nm to 50 nm, and most preferably 10 nm to 50 nm. By setting the thickness of the light emitting layer to 5 nm or more, it becomes easy to form the light emitting layer and adjust the chromaticity. By setting the film thickness of the light emitting layer to 50 nm or less, an increase in driving voltage can be suppressed.
The film thickness of each of the other organic compound layers is not particularly limited, but is usually preferably in the range of several nm to 1 μm. By making such a film thickness range, defects such as pinholes caused by the film thickness being too thin are prevented, and an increase in driving voltage caused by the film thickness being too thick is suppressed, resulting in deterioration of efficiency. Can be prevented.

(Measurement method of triplet energy)
The triplet energy EgT of each compound was measured by the following method.
Each compound was measured by a known phosphorescence measurement method (for example, “the world of photochemistry” (edited by the Chemical Society of Japan, 1993), page 50). Specifically, each compound is dissolved in a solvent (sample 10 [μmol / liter], EPA (diethyl ether: isopentane: ethanol = 5: 5: 5 (volume ratio), each solvent is a spectroscopic grade), and phosphorescence measurement is performed. The phosphorescence measurement sample placed in the quartz cell was cooled to 77 [K], the excitation light was irradiated onto the phosphorescence measurement sample, and the phosphorescence intensity was measured while changing the wavelength. Is the phosphorescence intensity, and the horizontal axis is the wavelength.
A tangent line was drawn with respect to the rising edge of the phosphorescence spectrum on the short wavelength side, and a wavelength value λ edge [nm] at the intersection of the tangent line and the horizontal axis was obtained. A value obtained by converting this wavelength value into an energy value by the following conversion formula was defined as EgT.
Conversion formula: EgT [eV] = 1239.85 / λedge
For phosphorescence measurement, an F-4500 type spectrofluorometer main body manufactured by Hitachi High-Technology Co., Ltd. and optional equipment for low temperature measurement were used. Note that the measurement device is not limited to this, and the measurement may be performed by combining a cooling device and a cryogenic container, an excitation light source, and a light receiving device.

[Modification of Embodiment]
In addition, this invention is not limited to the above-mentioned embodiment, The change in the range which can achieve the objective of this invention, improvement, etc. are included in this invention.

  Moreover, the structure of an organic EL element is not limited to the structural example of the organic EL element 1 shown in FIG. For example, an electron barrier layer may be provided on the anode side of the light emitting layer, and a hole barrier layer may be provided on the cathode side of the light emitting layer. Thereby, electrons and holes can be confined in the light emitting layer, and the exciton generation probability in the light emitting layer can be increased.

Further, the light emitting layer is not limited to one layer, and a plurality of light emitting layers may be stacked. When the organic EL element has a plurality of light emitting layers, it is preferable that at least one light emitting layer contains the biscarbazole derivative of the present invention.
Further, when the organic EL element has a plurality of light emitting layers, these light emitting layers may be provided adjacent to each other, or may be laminated via other layers (for example, charge generation layers). .

  EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not restrict | limited to the description content of these Examples at all.

<Synthesis of compounds>
Synthesis Example 1 (Synthesis of Compound 1)
A synthesis scheme of Compound 1 is shown below.

In the synthesis of Compound 1,
Carbazol-2-yl-trifluoromethanesulfonate (6.3 g, 20 mmol),
4,6-diphenyltriazine-2-chloride (5.4g, 20mmol), and potassium carbonate (3.3g, 24mmol)
Was dissolved in dimethyl sulfoxide (20 mL) and stirred at 100 ° C. for 8 hours.
The precipitated solid was washed with methanol to obtain Intermediate 1-1 (8.4 g, yield 77%).
Then
Intermediate 1-1 (5.5 g, 10 mmol),
Carbazole-2-boronic acid pinacol ester (2.9 g, 10 mmol), and tetrakis (triphenylphosphine) palladium (0.23 g, 0.2 mmol)
Was added to a mixture of toluene (15 mL) and 2M aqueous sodium carbonate solution (15 mL), and the mixture was stirred at 80 ° C. for 8 hours. The organic layer was separated and the solvent was distilled off under reduced pressure. The precipitated solid was purified by silica gel column chromatography to obtain Intermediate 1-2 (4.0 g, yield 71%).
Then
Intermediate 1-2 (2.8 g, 5 mmol),
Bromobenzene (0.86g, 5.5mmol),
Tris (dibenzyldenacetone) dipalladium (0.09 g, 0.1 mmol),
Tri-t-butylphosphonium tetrafluoroborate (0.11 g, 0.4 mmol), and sodium t-butoxy (0.67 g, 7 mmol)
Was added to anhydrous toluene (20 mL) and refluxed for 8 hours. After evaporating the solvent under reduced pressure, the precipitated solid was purified by silica gel column chromatography to obtain Compound 1 (2.4 g, yield 75%).
As a result of FD-MS analysis, it was m / e = 640 with respect to molecular weight 640.

Synthesis Example 2 (Synthesis Example of Compound 2)
A synthesis scheme of Compound 2 is shown below.

In the synthesis of Compound 2,
Carbazol-2-yl-trifluoromethanesulfonate (6.3 g, 20 mmol),
4,6-diphenylpyrimidine-2-chloride (5.3 g, 20 mmol), and potassium carbonate (3.3 g, 24 mmol)
Was dissolved in dimethyl sulfoxide (20 mL) and stirred at 100 ° C. for 8 hours. The precipitated solid was washed with methanol to obtain Intermediate 2-1 (8.8 g, yield 81%).
Then
Intermediate 2-1 (5.5 g, 10 mmol),
Carbazole-2-boronic acid pinacol ester (2.9 g, 10 mmol), and tetrakis (triphenylphosphine) palladium (0.23 g, 0.2 mmol)
Was added to a mixture of toluene (15 mL) and 2M sodium carbonate (15 mL), and the mixture was stirred at 80 ° C. for 8 hours. The organic layer was separated and the solvent was distilled off under reduced pressure. The precipitated solid was purified by silica gel column chromatography to obtain Intermediate 2-2 (3.5 g, yield 63%).
Then
Intermediate 2-2 (2.8 g, 5 mmol),
Bromobenzene (0.86g, 5.5mmol),
Tris (dibenzyldenacetone) dipalladium (0.09 g, 0.1 mmol),
Tri-t-butylphosphonium tetrafluoroborate (0.11 g, 0.4 mmol), and sodium t-butoxy (0.67 g, 7 mmol)
Was added to anhydrous toluene (20 mL) and refluxed for 8 hours. After evaporating the solvent under reduced pressure, the precipitated solid was purified by silica gel column chromatography to obtain compound 2 (2.2 g, yield 68%).
As a result of FD-MS analysis, it was m / e = 639 with respect to molecular weight 639.
The ionization potential (IP) of Compound 2 was 5.69 eV.
The affinity (Af) of Compound 2 was 2.57 eV.
The triplet energy (Eg (T)) of Compound 2 was 2.66 eV.

Synthesis Example 3 (Synthesis Example of Compound 3)
A synthesis scheme of Compound 3 is shown below.

In the synthesis of Compound 3, first, 2-bromocarbazole (18 g, 73 mmol) was added to a three-necked flask under an argon atmosphere.
Iodobenzene (14.9 g, 73 mmol),
CuI (14 g, 73 mmol),
Tripotassium phosphate (23.2 g, 110 mmol),
Anhydrous dioxane (100 mL), and cyclohexanediamine (8.3 g, 73 mmol)
Were added in this order and stirred at 100 ° C. for 8 hours.
Water was added to the reaction solution to precipitate a solid, which was washed with hexane and then with methanol. Furthermore, the obtained solid was purified by silica gel column chromatography to obtain Intermediate 3-1 (10.5 g, yield 45%).
Next, Intermediate 3-1 (10 g, 31 mmol) was added to anhydrous tetrahydrofuran (100 mL), and after cooling to 0 ° C., n-butyllithium 1.6 M hexane (24 mL, 38 mmol) was added dropwise. After 30 minutes, a solution of triisopropyl borate (11.7 g, 62 mmol) in anhydrous tetrahydrofuran (50 mL) was added dropwise, and the mixture was warmed to room temperature and stirred for 5 hours. After adding 1N hydrochloric acid and stirring for 30 minutes, the organic layer was separated and the solvent was distilled off under reduced pressure. The obtained solid was purified by silica gel column chromatography to obtain Intermediate 3-2 (4.9 g, yield 55%).
Then
Intermediate 3-2 (4.5 g, 15.7 mmol),
Carbazole-2-boronic acid pinacol ester (4.9 g, 15.7 mmol), and tetrakis (triphenylphosphine) palladium (0.36 g, 0.3 mmol)
Was added to toluene (25 mL) and 2M sodium carbonate mixture (25 mL), and the mixture was stirred at 80 ° C. for 8 hours. The organic layer was separated and the solvent was distilled off under reduced pressure. The precipitated solid was purified by silica gel column chromatography to obtain Intermediate 3-3 (4.5 g, yield 70%).
Then
Intermediate 3-3 (2.0 g, 5 mmol),
Intermediate 3-4 (1.93 g, 5 mmol),
Tris (dibenzyldenacetone) dipalladium (0.09 g, 0.1 mmol),
Tri-t-butylphosphonium tetrafluoroborate (0.11 g, 0.4 mmol), and sodium t-butoxy (0.67 g, 7 mmol)
Was added to anhydrous toluene (20 mL) and refluxed for 8 hours. After evaporating the solvent under reduced pressure, the precipitated solid was purified by silica gel column chromatography to obtain compound 3 (2.1 g, yield 60%).
As a result of FD-MS analysis, it was m / e = 715 with respect to the molecular weight 715.

<Production and Evaluation of Organic EL Element>
An organic EL element was produced and evaluated as follows.
The compounds used for the production of the organic EL device are as follows in addition to the compounds 1 to 3 shown in Synthesis Examples 1 to 3.

Example 1
A glass substrate with an ITO transparent electrode of 25 mm × 75 mm × thickness 1.1 mm (manufactured by Geomatic Co., Ltd.) was subjected to ultrasonic cleaning in isopropyl alcohol for 5 minutes and then UV ozone cleaning for 30 minutes.
The glass substrate with a transparent electrode line after washing is mounted on a substrate holder of a vacuum deposition apparatus, and the electron-accepting compound (C--) is first covered so as to cover the transparent electrode on the surface on which the transparent electrode line is formed. 1) was vapor-deposited to form a compound (C-1) film having a thickness of 5 nm, and this film was used as a hole injection layer.
The aromatic amine derivative (X1) is vapor-deposited as a first hole transport material on the compound (C-1) film to form an aromatic amine derivative (X1) film having a thickness of 50 nm. One hole transport layer was formed.
Following the film formation of the first hole transport layer, the aromatic amine derivative (X2) is deposited as a second hole transport material to form an aromatic amine derivative (X2) film having a film thickness of 60 nm. The film was a second hole transport layer.

Further, Compound 1 obtained in Synthesis Example 1 was deposited on the second hole transport layer to form a light emitting layer having a thickness of 45 nm. Simultaneously with the vapor deposition of Compound 1, the compound (D3) as a phosphorescent material was co-deposited. The concentration of the compound (D3) was 8.0% by mass. This co-deposited film functions as a light emitting layer using Compound 1 as a phosphorescent host material and Compound (D3) as a phosphorescent dopant material. Compound (D3) is a red light emitting material.
Then, following the formation of the light emitting layer, the compound (ET2) was vapor-deposited to form a 30 nm-thick compound (ET2) film, which was used as an electron transport layer.

Next, LiF was deposited on the electron transport layer at a deposition rate of 0.1 angstrom / min to form a 1-nm-thick LiF film, and this film was used as an electron injecting electrode (cathode).
Furthermore, metal Al was vapor-deposited on this LiF film to form a metal cathode having a thickness of 80 nm.
Thus, the organic EL element of Example 1 was produced.

Example 2
The organic EL device of Example 2 was prepared in the same manner as the organic EL device of Example 1 except that Compound 2 was used instead of Compound 1 for the phosphorescent host material of the light emitting layer of the organic EL device of Example 1. did.

Example 3
The organic EL device of Example 3 was produced in the same manner as the organic EL device of Example 1 except that Compound 3 was used instead of Compound 1 for the phosphorescent host material of the light emitting layer of the organic EL device of Example 1. did.

[Evaluation of organic EL elements]
About the produced organic EL element, luminous efficiency and luminance half life were evaluated. The results are shown in Table 1.

・ Measurement of luminous efficiency (current efficiency) The produced organic EL device was allowed to emit light at room temperature with direct current drive (current density: 10 mA / cm ² ), and the spectral radiance spectrum at that time was measured with a spectral radiance meter (Comica). Measurement was performed with Minolta Co., Ltd. (CS-1000). Luminous efficiency (unit: cd / A) was calculated from the obtained spectral radiance spectrum.

· Measurement fabricated organic EL device of the half-life, at room temperature, allowed to emit light by the DC constant current driving with the initial luminance 5000 cd / m ^2, the time was measured until the brightness is reduced by half.

As shown in Table 1, the red light-emitting organic EL elements of Examples 1 to 3 exhibit good luminous efficiency and luminance half-life.
The triplet energy EgT of compound 2 is 2.66 eV, and the triplet energy EgT of compound F1 is 2.91 eV. As described above, the physical properties of the biscarbazole derivative such as the compound F1 in which the bonding position between the carbazolyl groups is 3-position and the biscarbazole derivative such as the compound 2 in which the bonding position is 2-position are greatly different. I understood that.
In Compounds 1 to 3, a nitrogen-containing aromatic heterocyclic group is bonded to the N-position (9-position) of the carbazolyl group directly or via a linking group. Compared to a structure in which a nitrogen-containing aromatic heterocyclic group is bonded to the benzene ring of the carbazolyl group, HOMO and LUMO can be clearly separated by adopting such a compound structure. It is considered that the resistance to each charge has improved. Further, the nitrogen-containing aromatic heterocyclic group bonded directly or through a linking group to the N-position (9-position) of the carbazolyl group is a triazinyl group in the compounds 1 and 3, and is a pyrimidinyl group in the compound 2. . With such a nitrogen-containing aromatic heterocyclic group, it is considered that Compounds 1 to 3 have improved resistance to each charge. Therefore, it is considered that the organic EL elements of Examples 1 to 3 using Compounds 1 to 3 which are biscarbazole derivatives of the present invention as host materials are excellent in durability and have improved luminance half-life.

  The biscarbazole derivative of the present invention can be used as a material for an organic EL device. In addition, the organic EL element using the biscarbazole derivative of the present invention can be used as a light emitting element in a display device or a lighting device.

  DESCRIPTION OF SYMBOLS 1 ... Organic EL element, 2 ... Board | substrate, 3 ... Anode, 4 ... Cathode, 6 ... Hole transport layer, 7 ... Light emitting layer, 8 ... Electron transport layer, 10 ... Organic compound layer.

Claims (11)

A biscarbazole derivative represented by the following general formula (1).
In the general formula (1),
A ₁ and A ₂ are
A substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 ring carbon atoms or a substituted or unsubstituted aromatic heterocyclic group having 1 to 30 ring carbon atoms.
However, at least one of A ₁ and A ₂ represents a substituted or unsubstituted nitrogen-containing aromatic heterocyclic group having 1 to 4 ring carbon atoms.
Y _{1 to} Y ₄ are a carbon atom or a nitrogen atom bonded to the following R. However, when two adjacent ones of Y _{1 to} Y ₄ are carbon atoms, a ring containing the adjacent carbon atoms may be formed without bonding to R.
Y _{5 to} Y ₇ are a carbon atom or a nitrogen atom bonded to the following R. However, when Y ₅ and Y ₆ are carbon atoms, a ring containing carbon atoms of Y ₅ and Y ₆ may be formed without bonding to R.
Y _{8 to} Y ₁₀ are a carbon atom or a nitrogen atom bonded to the following R. However, when Y ₉ and Y ₁₀ are carbon atoms, a ring containing carbon atoms of Y ₉ and Y ₁₀ may be formed without being bonded to R.
Y _{11 to} Y ₁₄ are a carbon atom or a nitrogen atom bonded to the following R. However, when two adjacent ones of Y _{11 to} Y ₁₄ are carbon atoms, a ring containing the adjacent carbon atoms may be formed without being bonded to R.
R is independently a hydrogen atom,
A substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 ring carbon atoms,
A substituted or unsubstituted aromatic heterocyclic group having 1 to 30 ring carbon atoms,
A substituted or unsubstituted linear, branched, or cyclic alkyl group having 1 to 30 carbon atoms,
A substituted or unsubstituted alkoxy group having 1 to 30 carbon atoms,
A substituted or unsubstituted aryloxy group having 6 to 30 ring carbon atoms,
A substituted or unsubstituted aralkyl group having 7 to 30 carbon atoms,
A substituted or unsubstituted haloalkyl group having 1 to 30 carbon atoms,
A substituted or unsubstituted haloalkoxy group having 1 to 30 carbon atoms,
A substituted or unsubstituted trialkylsilyl group having 3 to 30 carbon atoms,
A substituted or unsubstituted dialkylarylsilyl group having 8 to 40 carbon atoms,
A substituted or unsubstituted alkyldiarylsilyl group having 13 to 50 carbon atoms,
A substituted or unsubstituted triarylsilyl group having 18 to 60 carbon atoms,
Halogen atoms,
A cyano group,
Hydroxyl group,
Represents a nitro group or a carboxy group.
L _{1 to} L ₃ represent a single bond or a divalent linking group. The biscarbazole derivative according to claim 1, wherein
Bis carbazole derivative, wherein the L ₃ in the general formula (1), is a single bond. In the biscarbazole derivative according to claim 1 or 2,
The biscarbazole derivative, wherein the nitrogen-containing aromatic heterocyclic group in the general formula (1) is a substituted or unsubstituted pyrimidinyl group or a substituted or unsubstituted triazinyl group. In the biscarbazole derivative according to any one of claims 1 to 3,
In the general formula (1), at least one of L ₁ and L ₂ is
A divalent group of a substituted or unsubstituted aromatic hydrocarbon compound having 6 to 30 ring carbon atoms, or a divalent group of a substituted or unsubstituted aromatic heterocyclic compound having 1 to 30 ring carbon atoms A biscarbazole derivative characterized by being. An organic electroluminescence device comprising an organic compound layer between a cathode and an anode,
The said organic compound layer contains the biscarbazole derivative as described in any one of Claim 1- Claim 4. The organic electroluminescent element characterized by the above-mentioned. In the organic electroluminescent element according to claim 5,
The organic compound layer includes a plurality of organic thin film layers including a light emitting layer,
5. The organic electroluminescence device according to claim 1, wherein at least one of the plurality of organic thin film layers includes the biscarbazole derivative according to claim 1. The organic electroluminescence device according to claim 6,
The said light emitting layer contains the biscarbazole derivative as described in any one of Claim 1- Claim 4. The organic electroluminescent element characterized by the above-mentioned. In the organic electroluminescent element according to claim 6 or 7,
The organic light-emitting element, wherein the light-emitting layer includes a phosphorescent material. The organic electroluminescent device according to claim 8, wherein
The organic light-emitting device, wherein the phosphorescent material includes an orthometalated complex of metal atoms selected from iridium (Ir), osmium (Os), and platinum (Pt).   10. The organic electroluminescence device according to claim 6, wherein the light emitting layer further contains an aromatic amine derivative. 11. 11. The organic electroluminescence device according to claim 6, wherein the plurality of organic thin film layers include a hole transport layer, a light emitting layer, and an electron transport layer. Luminescence element.