JP6031302B2 - Heteroaromatic compound and organic electroluminescence device using the same - Google Patents

Description

  The present invention relates to a heteroaromatic compound, in particular, a dihydroacridine derivative, a material for an organic electroluminescence device including the same, and an organic electroluminescence device including the material.

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. 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 light emitting layer, a host material having a triplet energy larger than the triplet energy of the phosphorescent dopant material must first be used for the light emitting layer. I must. 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 a phosphorescent organic EL element, it is difficult to select such a hydrocarbon compound, and an organic compound containing a heteroatom 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.
In particular, 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 without loss of efficiency, the triplet energy of the host material used for the light-emitting layer needs to be approximately 3.0 eV or more. In order to obtain a compound satisfying the performance required as an organic EL material while having such a high triplet energy, not simply combining molecular parts having a high triplet energy such as a heterocyclic compound, Molecular design based on a new concept that considers the electronic state of π electrons is required.

  Under such circumstances, various compounds have been studied as materials for phosphorescent organic EL elements that emit blue light. For example, Patent Document 1 discloses a host material in which dihydroacridine and dibenzothiophene or carbazole are combined.

JP 2010-180204 A

  An object of the present invention is to provide a compound that balances electron transport properties and hole transport properties in a light emitting layer. Moreover, it is providing the organic electroluminescent element of a low voltage and long lifetime by utilizing this.

（式（Ａ）中、Ａｃは下記式（１）〜（５）のいずれかであり、
Ｌ_１及びＬ_２は、それぞれ、単結合、置換もしくは無置換の環形成炭素数６〜１８の芳香族炭化水素環、又は置換もしくは無置換の環形成原子数５〜１８のヘテロ芳香族環であり、
Ａは、置換もしくは無置換のジベンゾフラン環、又は置換もしくは無置換のジベンゾチオフェン環であり、
Ａｒは、水素原子、置換もしくは無置換の環形成炭素数６〜１８の芳香族炭化水素環、又は置換もしくは無置換の環形成原子数５〜１８のヘテロ芳香族環であり、
ｎは１又は２であり、
ｎが１の場合、Ａｃは下記式（１）又は（２）であり、ｎが２の場合、Ａｃは下記式（３）〜（５）のいずれかであり、ｎが２の場合、複数のＬ_１、Ｌ_２、Ａ及びＡｒは、それぞれ同一でも異なっていてもよい。

（式（１）〜（５）中、Ｘ_１１〜Ｘ_１８は、それぞれ、ＣＲ_４、Ｌ_１と結合する炭素原子、又は窒素原子であり、
Ｒ_１〜Ｒ_４は、それぞれ、水素原子、置換もしくは無置換の炭素数１〜２０のアルキル基、置換もしくは無置換の環形成炭素数３〜２０のシクロアルキル基、置換もしくは無置換の炭素数１〜２０のアルコキシ基、置換もしくは無置換の環形成炭素数３〜２０のシクロアルコキシ基、置換もしくは無置換の環形成炭素数６〜１８の芳香族炭化水素環、置換もしくは無置換の環形成炭素数６〜１８のアリールオキシ基、置換もしくは無置換の環形成原子数５〜１８のヘテロ芳香族環、置換もしくは無置換のアミノ基、フッ素原子、置換もしくは無置換の炭素数１〜２０のフルオロアルキル基、又はシアノ基である。
＊は、Ｌ_１との結合位置を示す。））
２．Ｘ_１１〜Ｘ_１８が、それぞれ、ＣＲ_４、又はＬ_１と結合する炭素原子である１に記載の化合物。
３．Ｒ_１及びＲ_２が、それぞれ、置換もしくは無置換の炭素数１〜２０のアルキル基、又はフェニル基である１又は２に記載の化合物。
４．Ｒ_１及びＲ_２が、共にメチル基である１〜３のいずれかに記載の化合物。
５．Ａが、置換もしくは無置換のジベンゾフラン環である１〜４のいずれかに記載の化合物。
６．Ａｒが、水素原子、置換もしくは無置換のベンゼン環、置換もしくは無置換のカルバゾール環、置換もしくは無置換のアザカルバゾール環、置換もしくは無置換のジヒドロアクリジン環、置換もしくは無置換のジベンゾフラン環、又は置換もしくは無置換のジベンゾチオフェン環である１〜５のいずれかに記載の化合物。
７．Ｌ_１及びＬ_２の一方又は両方が単結合である１〜６のいずれかに記載の化合物。
８．１〜７のいずれかに記載の化合物を含む有機エレクトロルミネッセンス素子用材料。
９．陰極と陽極の間に発光層を含む一層以上の有機薄膜層を有し、前記有機薄膜層のうち少なくとも１層が８に記載の有機エレクトロルミネッセンス素子用材料を含む有機エレクトロルミネッセンス素子。
１０．前記発光層が前記有機エレクトロルミネッセンス素子用材料をホスト材料として含む９に記載の有機エレクトロルミネッセンス素子。
１１．前記発光層が燐光発光材料を含有する９又は１０に記載の有機エレクトロルミネッセンス素子。
１２．前記燐光発光材料がイリジウム（Ｉｒ）、オスミウム（Ｏｓ）、白金（Ｐｔ）から選択される金属原子のオルトメタル化錯体である１１に記載の有機エレクトロルミネッセンス素子。
１３．前記陰極と前記発光層の間に電子注入層を有し、前記電子注入層が含窒素環誘導体を含む９〜１２のいずれかに記載の有機エレクトロルミネッセンス素子。
１４．前記陰極と前記発光層の間に有機薄膜層を有し、前記有機薄膜層が前記有機エレクトロルミネッセンス素子用材料を含む９〜１３のいずれかに記載の有機エレクトロルミネッセンス素子。
１５．前記陽極と前記発光層の間に有機薄膜層を有し、前記有機薄膜層が前記有機エレクトロルミネッセンス素子用材料を含む９〜１３のいずれかに記載の有機エレクトロルミネッセンス素子。 According to the present invention, the following compounds and the like are provided.
1. A compound represented by the following formula (A).

(In the formula (A), Ac is any one of the following formulas (1) to (5),
L ₁ and L ₂ are each a single bond, a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 18 ring carbon atoms, or a substituted or unsubstituted heteroaromatic ring having 5 to 18 ring atoms. Yes,
A is a substituted or unsubstituted dibenzofuran ring, or a substituted or unsubstituted dibenzothiophene ring,
Ar is a hydrogen atom, a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 18 ring carbon atoms, or a substituted or unsubstituted heteroaromatic ring having 5 to 18 ring atoms;
n is 1 or 2,
When n is 1, Ac is the following formula (1) or (2), when n is 2, Ac is any one of the following formulas (3) to (5), and when n is 2, L ₁ , L ₂ , A and Ar may be the same or different.

(In the formulas (1) to (5), X _{11 to} X ₁₈ are a carbon atom or a nitrogen atom bonded to CR ₄ or L ₁ , respectively.
R _{1 to} R ₄ 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, and 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 atoms, substituted or unsubstituted amino group, fluorine atom, substituted or unsubstituted 1 to 20 carbon atoms It is a fluoroalkyl group or a cyano group.
* Indicates a binding position with the _{L 1.} ))
2. 2. The compound according to 1, wherein X _{11 to} X ₁₈ are each a carbon atom bonded to CR ₄ or L ₁ .
3. 3. The compound according to 1 or 2, wherein R ₁ and R ₂ are each a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms or a phenyl group.
4). R ₁ and _{R 2} are both A compound according to any one of 1 to 3 methyl groups.
5. The compound in any one of 1-4 whose A is a substituted or unsubstituted dibenzofuran ring.
6). Ar is a hydrogen atom, a substituted or unsubstituted benzene ring, a substituted or unsubstituted carbazole ring, a substituted or unsubstituted azacarbazole ring, a substituted or unsubstituted dihydroacridine ring, a substituted or unsubstituted dibenzofuran ring, or a substituted Or the compound in any one of 1-5 which is an unsubstituted dibenzothiophene ring.
7). A compound according to any one of 1 to 6 one or both of L ₁ and L ₂ is a single bond.
The material for organic electroluminescent elements containing the compound in any one of 8.1-7.
9. An organic electroluminescence device comprising one or more organic thin film layers including a light emitting layer between a cathode and an anode, wherein at least one of the organic thin film layers comprises the material for an organic electroluminescence device according to 8.
10. 10. The organic electroluminescence device according to 9, wherein the light emitting layer includes the organic electroluminescence device material as a host material.
11. 11. The organic electroluminescence device according to 9 or 10, wherein the light emitting layer contains a phosphorescent material.
12 12. The organic electroluminescence device according to 11, wherein the phosphorescent material is an orthometalated complex of metal atoms selected from iridium (Ir), osmium (Os), and platinum (Pt).
13. The organic electroluminescence device according to any one of 9 to 12, which has an electron injection layer between the cathode and the light emitting layer, and the electron injection layer contains a nitrogen-containing ring derivative.
14 The organic electroluminescent element according to any one of 9 to 13, which has an organic thin film layer between the cathode and the light emitting layer, and the organic thin film layer contains the material for an organic electroluminescent element.
15. The organic electroluminescence device according to any one of 9 to 13, which has an organic thin film layer between the anode and the light emitting layer, and the organic thin film layer contains the material for an organic electroluminescence device.

  ADVANTAGE OF THE INVENTION According to this invention, the compound which balances electron transport property and hole transport property in a light emitting layer can be provided. Moreover, a low voltage and long-life organic electroluminescent element can be provided by utilizing this.

It is a figure which shows one Embodiment of the organic EL element of this invention. It is a figure which shows other embodiment of the organic EL element of this invention.

（式（Ａ）中、Ａｃは下記式（１）〜（５）のいずれかである。
Ｌ_１及びＬ_２は、それぞれ、単結合、置換もしくは無置換の環形成炭素数６〜１８の芳香族炭化水素環、又は置換もしくは無置換の環形成原子数５〜１８のヘテロ芳香族環である。
Ａは、置換もしくは無置換のジベンゾフラン環、又は置換もしくは無置換のジベンゾチオフェン環である。
Ａｒは、水素原子、置換もしくは無置換の環形成炭素数６〜１８の芳香族炭化水素環、又は置換もしくは無置換の環形成原子数５〜１８のヘテロ芳香族環である。
ｎは１又は２であり、ｎが１の場合、Ａｃは下記式（１）又は（２）であり、ｎが２の場合、Ａｃは下記式（３）〜（５）のいずれかであり、ｎが２の場合、複数のＬ_１、Ｌ_２、Ａ及びＡｒは、それぞれ同一でも異なっていてもよい。

（式（１）〜（５）中、Ｘ_１１〜Ｘ_１８は、それぞれ、ＣＲ_４、Ｌ_１と結合する炭素原子、又は窒素原子である。
Ｒ_１〜Ｒ_４は、それぞれ、水素原子、置換もしくは無置換の炭素数１〜２０のアルキル基、置換もしくは無置換の環形成炭素数３〜２０のシクロアルキル基、置換もしくは無置換の炭素数１〜２０のアルコキシ基、置換もしくは無置換の環形成炭素数３〜２０のシクロアルコキシ基、置換もしくは無置換の環形成炭素数６〜１８の芳香族炭化水素環、置換もしくは無置換の環形成炭素数６〜１８のアリールオキシ基、置換もしくは無置換の環形成原子数５〜１８のヘテロ芳香族環、置換もしくは無置換のアミノ基、フッ素原子、置換もしくは無置換の炭素数１〜２０のフルオロアルキル基、又はシアノ基である。
＊は、Ｌ_１との結合位置を示す。）） The compound of the present invention is represented by the following formula (A).

(In the formula (A), Ac is any one of the following formulas (1) to (5).
L ₁ and L ₂ are each a single bond, a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 18 ring carbon atoms, or a substituted or unsubstituted heteroaromatic ring having 5 to 18 ring atoms. is there.
A is a substituted or unsubstituted dibenzofuran ring or a substituted or unsubstituted dibenzothiophene ring.
Ar is a hydrogen atom, a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 18 ring carbon atoms, or a substituted or unsubstituted heteroaromatic ring having 5 to 18 ring atoms.
n is 1 or 2, when n is 1, Ac is the following formula (1) or (2), and when n is 2, Ac is any of the following formulas (3) to (5) , N is 2, the plurality of L ₁ , L ₂ , A and Ar may be the same or different.

(In the formula _{(1) ~ (5),} X 11 ~X 18 , _{respectively,} CR 4, _{L 1} and bonded to a carbon atom, or a nitrogen atom.
R _{1 to} R ₄ 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, and 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 atoms, substituted or unsubstituted amino group, fluorine atom, substituted or unsubstituted 1 to 20 carbon atoms It is a fluoroalkyl group or a cyano group.
* Indicates a binding position with the _{L 1.} ))

  The compound of the present invention has a charge balance by having a dihydroacridine skeleton having a shallow ionization potential and excellent hole injection properties compared with carbazole and dibenzofuran or dibenzothiophene having electron resistance and electron transport performance. Excellent.

One or both of L ₁ and L ₂ are preferably a single bond, and more preferably one is an aromatic hydrocarbon ring having 6 to 18 ring carbon atoms (for example, a benzene ring) or a carbazole ring. The other is a single bond. This is preferable because the triplet energy (T1) can be kept large. Further, when the linking group (L ₁ , L ₂ ) becomes longer, T1 may become smaller.

  A is preferably a substituted or unsubstituted dibenzofuran ring. A substituted or unsubstituted dibenzofuran ring is preferable because it has electron resistance and is superior in electron transport performance.

  Ar is preferably a substituted or unsubstituted benzene ring, a substituted or unsubstituted carbazole ring, a substituted or unsubstituted azacarbazole ring, a substituted or unsubstituted dihydroacridine ring, a substituted or unsubstituted dibenzofuran ring, or a substituted Or it is an unsubstituted dibenzothiophene ring. These groups are preferable because of excellent electron resistance and a large T1.

In the above formulas (1) to (5), X _{11 to} X ₁₈ are preferably each CR ₄ or a carbon atom bonded to L ₁ , and when X _{11 to} X ₁₈ are each CR ₄ , R ₄ is Preferably they are a hydrogen atom, a phenyl group, or a C1-C6 alkyl group.
R ₁ and R ₂ are preferably each a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a phenyl group, more preferably an alkyl group having 1 to 6 carbon atoms, and still more preferably. Are both methyl groups. It is preferable that both R ₁ and R ₂ are methyl groups because T1 can be kept large.
R ₃ is preferably a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 18 ring carbon atoms, and more preferably a phenyl group. is there.

Hereinafter, examples of each group of the above-described formula (A) will be described.
Examples of the alkyl group having 1 to 20 carbon atoms include linear or branched alkyl groups, specifically, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, sec- A butyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group and the like can be mentioned, and preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, and n-butyl Group, isobutyl group, sec-butyl group and tert-butyl group, preferably methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group and tert-butyl group.

  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 1-adamantyl group, a 2-adamantyl group, a 1-norbornyl group, and a 2-norbornyl group. Of these, a cyclopentyl group and a cyclohexyl group are preferable.

  A C1-C20 alkoxy group is represented as -OY and the example of said alkyl is mentioned as an example of Y. The alkoxy group is, for example, a methoxy group or an ethoxy group. The alkoxy group may be substituted with a fluorine atom, and in this case, a trifluoromethoxy group or the like is preferable.

  A cycloalkoxy group having 3 to 20 ring carbon atoms is represented as —OY, and examples of Y include the above-described cycloalkyl groups. The cycloalkoxy group is, for example, a cyclopentyloxy group or a cyclohexyloxy group.

The aromatic hydrocarbon ring having 6 to 18 ring carbon atoms is preferably an aromatic hydrocarbon ring having 6 to 12 ring carbon atoms. The “ring-forming carbon” means a carbon atom constituting a saturated ring, an unsaturated ring, or an aromatic ring.
Specific examples of the monovalent group of the aromatic hydrocarbon ring include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a naphthacenyl group, a pyrenyl group, a chrycenyl group, a benzo [c] phenanthryl group, and a benzo [g] chrysenyl group. , Triphenylenyl group, fluorenyl group, benzofluorenyl group, dibenzofluorenyl group, biphenylyl group, terphenyl group, quarterphenyl group, fluoranthenyl group, etc., preferably phenyl group, biphenyl group, terphenyl Group, tolyl group, xylyl group and naphthyl group.
When the aromatic hydrocarbon ring has a substituent, the substituent is preferably the above alkyl group, and the substituted aromatic hydrocarbon ring includes a 9,9-dimethylfluorenyl group.
Examples of the divalent or higher group of the aromatic hydrocarbon ring include the divalent or higher group of the group described above.

  The aryloxy group having 6 to 18 ring carbon atoms is represented as -OY, and examples of Y include the above aromatic hydrocarbon rings. The aryloxy group is, for example, an phenoxy group.

The heteroaromatic ring having 5 to 18 ring atoms is preferably a heteroaromatic ring having 5 to 12 ring atoms.
Specific examples of the monovalent group of the heteroaromatic ring include pyrrolyl group, pyrazinyl group, pyridinyl group, pyrimidinyl group, triazinyl group, indolyl group, isoindolyl group, imidazolyl 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, dihydroacridinyl group, dihydroazaacridinyl group, phenanthate Examples include a rolinyl group, a phenazinyl group, a phenothiazinyl group, a phenoxazinyl group, an oxazolyl group, an oxadiazolyl group, a furanyl group, a thienyl group, a benzothiophenyl group, a quinazolyl group, and preferably a dibenzofuranyl group, a dibenzothiopheny group. Group, a carbazolyl group, a azacarbazolyl group.
Examples of the divalent or higher group of the heteroaromatic ring include the divalent or higher group of the above-described group.

As the substituted or unsubstituted amino group, an amino group, an alkylamino group having 1 to 10 carbon atoms (preferably 1 to 6 carbon atoms) or a dialkylamino group, 6 to 30 carbon atoms (preferably having 6 to 20 carbon atoms, More preferably, an arylamino group or a diarylamino group having 6 to 10 carbon atoms is used.
Preferably, it is a diphenylamino group.

  Examples of the fluoroalkyl group include groups in which one or more fluorine atoms are substituted on the above-described alkyl group having 1 to 20 carbon atoms. Specific examples include a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a fluoroethyl group, a trifluoromethylmethyl group, and a pentafluoroethyl group. Preferably, they are a trifluoromethyl group and a pentafluoroethyl group.

Examples of the substituent of “substituted or unsubstituted...” Of each group described above include the above R _{1 to} R ₄ groups, that is, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted group. Or an unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkoxy group having 3 to 20 ring carbon atoms, substituted or unsubstituted Substituted aromatic hydrocarbon ring having 6 to 18 carbon atoms, substituted or unsubstituted aryloxy group having 6 to 18 ring carbon atoms, substituted or unsubstituted heteroaromatic ring having 5 to 18 ring atoms A substituted or unsubstituted amino group, a fluorine atom, a substituted or unsubstituted fluoroalkyl group having 1 to 20 carbon atoms, a cyano group, and the like.
In the present invention, the hydrogen atom includes isotopes having different numbers of neutrons, that is, light hydrogen (protium), deuterium (deuterium), and tritium (tritium).

Specific examples of the compound represented by the above formula (A) are shown below.

The compound of this invention can be conveniently used as a material of the organic thin film layer which comprises an organic EL element.
The material for an organic EL device of the present invention is particularly preferable as a material for a light emitting layer of an organic EL device or a layer adjacent to the light emitting layer, for example, a hole transport layer, an electron transport layer, a hole barrier layer, or an electron barrier layer. .

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.

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 or a hole injection layer. Similarly, the electron transport zone 50 means an electron transport layer, an electron injection 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.
In addition, the content of this material with respect to the organic thin film layer containing the organic EL element 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 material for the organic EL device of the present invention, and is particularly preferably used as a host material for 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. . In addition, it can be used not only for the blue light emitting layer but also for a light emitting layer of longer wavelength light (green to red, etc.).

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 30 wt% (wt%), more preferably 0.1 to 10 wt% (wt%).

It is also preferable to use the material of the present invention in a layer adjacent to the phosphorescent light emitting layer 40. For example, the hole transport zone 30 or the electron transport zone 50 preferably contains the material of the present invention.
In addition, when a layer containing the material of the present invention (anode-side adjacent layer) is formed between the hole transport zone 30 and the phosphorescent light emitting layer 40 of the device of FIG. 1, the layer functions as an electron barrier layer. It functions as an exciton blocking layer.
On the other hand, 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 the electron barrier layer, and the organic layer for preventing holes from leaking from the light-emitting layer to the electron transport zone is the 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
This material can also be used for other organic thin film layers bonded to a layer adjacent to the phosphorescent light emitting layer 40.

Furthermore, when two or more light emitting layers are formed, it is also suitable as a space layer formed between the light emitting layers.
FIG. 2 is a schematic view showing the layer structure of another embodiment of the organic EL device of the present invention.
The organic EL element 2 is an example of a hybrid type organic EL element in which a phosphorescent light emitting layer and a fluorescent light emitting layer are laminated.
The organic EL element 2 has the same configuration as the organic EL element 1 except that a space layer 42 and a fluorescent light emitting layer 44 are formed between the phosphorescent light emitting layer 40 and the electron transport zone 50. In the configuration in which the phosphorescent light emitting layer 40 and the fluorescent light emitting layer 44 are laminated, the excitons formed in the phosphorescent light emitting layer 40 are not diffused into the fluorescent light emitting layer 44, so that a space layer 42 is provided between the fluorescent light emitting layer 44 and the phosphorescent light emitting layer 40. May be provided. Since the material of the present invention has a large triplet energy, it can function as a space layer.

  In the organic EL element 2, for example, a white light emitting organic EL element can be obtained by setting the phosphorescent light emitting layer to emit yellow light and the fluorescent light emitting layer to blue light emitting layer. In this embodiment, the phosphorescent light-emitting layer and the fluorescent light-emitting layer are formed one by one. However, the present invention is not limited to this, and two or more layers may be formed, and can be appropriately set according to the application such as lighting and display device. For example, when a full color light emitting device is formed using a white light emitting element and a color filter, a plurality of wavelength regions such as red, green, blue (RGB), red, green, blue, yellow (RGBY) are used from the viewpoint of color rendering. In some cases, it may be preferable to include luminescence.

  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.

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, 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.

  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 preferred, but are 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 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 an 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 and the electron donating dopant and the organometallic complex is, as a molar ratio, the main component: the electron donating dopant and / or the organometallic complex = 5. Is preferably 1: 1 to 1: 5, and more preferably 2: 1 to 1: 2.

  In the organic EL element of this invention, it is not specifically limited about structures other than the layer which uses the organic EL element material of this invention mentioned above, A well-known material etc. 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%.
Further, 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 small ionization energy of usually 5.6 eV or less.
As the material for the hole injecting and transporting layer is preferably made of a material which can transport holes to the emitting layer at a lower electric field strength, The hole mobility thereof is, for example, 10 4 ^{to 10} when an electric field is applied in 6 V / ^cm, It is preferable if it is at least 10 ⁻⁴ cm ² / V · sec.

Specific examples of the material for the hole injection / transport layer include triazole derivatives (see US Pat. No. 3,112,197) and oxadiazole derivatives (see US Pat. No. 3,189,447). ), Imidazole derivatives (see JP-B-37-16096, etc.), polyarylalkane derivatives (US Pat. Nos. 3,615,402, 3,820,989, 3,542,544). Specification, Japanese Patent Publication Nos. 45-555, 51-10983, Japanese Patent Laid-Open Nos. 51-93224, 55-17105, 56-4148, 55-108667, 55-156953, 56-36656, etc.), pyrazoline derivatives and pyrazolone derivatives (US Pat. No. 3,180,729, No. 4) 278,746, JP-A 55-88064, 55-88065, 49-105537, 55-51086, 56-80051, 56-88141. No. 57-45545, No. 54-112537, No. 55-74546, etc.), phenylenediamine derivatives (US Pat. No. 3,615,404, JP-B 51-10105, 46-3712, 47-25336, 54-1119925, etc.), arylamine derivatives (US Pat. Nos. 3,567,450, 3,240,597) No. 3,658,520, No. 4,232,103, No. 4,175,961, No. 4,012,376 Description, JP-B-49-35702, JP-A-39-27577, JP-A-55-144250, JP-A-56-119132, JP-A-56-22437, West German Patent No. 1,110,518 ), Amino-substituted chalcone derivatives (see US Pat. No. 3,526,501, etc.), oxazole derivatives (disclosed in US Pat. No. 3,257,203 etc.), styrylanthracene derivatives (See JP 56-46234 A, etc.), fluorenone derivatives (see JP 54-110837 A, etc.), hydrazone derivatives (US Pat. No. 3,717,462, JP 54-59143 A). Gazette, 55-52063, 55-52064, 55-46760, 57-11350, 57 148749, JP-A-2-315991, etc.), stilbene derivatives (JP-A-61-210363, JP-A-61-222851, JP-A-61-14622, JP-A-61-72255, 62-47646, 62-36674, 62-10652, 62-30255, 60-93455, 60-94462, 60-174749, 60 -175052, etc.), silazane derivatives (US Pat. No. 4,950,950), polysilanes (JP-A-2-204996), aniline copolymers (JP-A-2-282263) Etc.
In addition, inorganic compounds such as p-type Si and p-type SiC can also be used as the hole injection material.

  As the material for the hole injection / transport layer, a cross-linkable material can be used. Mater. 2008, 20, 413-422, Chem. Mater. Examples include a layer obtained by insolubilizing a cross-linking material such as 2011, 23 (3), 658-681, WO2008108430, WO2009102027, WO2009123269, WO2010016555, WO2010018813 by heat, light or the like.

[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 thick, 10 ⁴ to 10 ^{6 in} order to avoid voltage increase It is preferable that the electron mobility is 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 injecting / transporting 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 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 and phenanthroline ring.

  In addition, an organic layer having semiconducting properties 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.

アルゴン雰囲気下、国際公開第２００９−００８１００号パンフレットに記載の方法に従って合成した２，８−ジブロモジベンゾフラン３２．６ｇ（１００ｍｍｏｌ）、３−（Ｎ−カルバゾリル）フェニルボロン酸２８．７ｇ（１００ｍｍｏｌ）、２Ｍ炭酸ナトリウム水溶液１００ｍｌ、１，２−ジメトキシエタン（ＤＭＥ）１００ｍｌ、トルエン１００ｍｌを加え、次いで、テトラキス（トリフェニルホスフィン）パラジウム２．３１ｇ（２ｍｍｏｌ）を加えて、１０時間加熱還流攪拌した。反応溶液を減圧下で濃縮して得られた残渣に、トルエン１０００ｍｌを加えて１２０℃に加熱し、不溶物を濾別した。濾液を減圧下で濃縮して得られた残渣をシリカゲルカラムクロマトグラフィー（ヘキサン／トルエン＝４／１）で精製することにより、中間体Ａ１９．５ｇ（収率４０％）を白色固体として得た。 [Synthesis of compounds]
Synthesis Example 1 [Synthesis of Compound A]
(1) Synthesis of Intermediate A Intermediate A was synthesized by the following steps.

Under an argon atmosphere, 32.6 g (100 mmol) of 2,8-dibromodibenzofuran synthesized according to the method described in WO2009-008100 pamphlet, 28.7 g (100 mmol) of 3- (N-carbazolyl) phenylboronic acid, 2M A sodium carbonate aqueous solution (100 ml), 1,2-dimethoxyethane (DME) (100 ml) and toluene (100 ml) were added, and tetrakis (triphenylphosphine) palladium (2.31 g, 2 mmol) was added, and the mixture was heated to reflux with stirring for 10 hours. To the residue obtained by concentrating the reaction solution under reduced pressure, 1000 ml of toluene was added and heated to 120 ° C., and insoluble matters were 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 19.5 g of Intermediate A (yield 40%) as a white solid.

アルゴン雰囲気下、中間体Ａ１９．５ｇ（４０ｍｍｏｌ）、特開２０１０−１８０２０４号公報に記載の方法に従って合成した中間体Ｂ８．４ｇ（４０ｍｍｏｌ）、トリス（ジベンジリデンアセトン）ジパラジウム０．３７ｇ（０．４ｍｍｏｌ）、トリ−ｔ−ブチルホスホニウムテトラフルオロほう酸塩０．４６ｇ（１．６ｍｍｏｌ）、ｔ−ブトキシナトリウム５．４ｇ（５６ｍｍｏｌ）、無水トルエン１００ｍｌを順次加えて８時間加熱還流攪拌した。反応溶液を減圧下で濃縮して得られた残渣をシリカゲルカラムクロマトグラフィー（ヘキサン／ジクロロメタン＝３／１）で精製することにより、化合物Ａ１６．０ｇ（収率６５％）を白色固体として得た。
ＦＤ−ＭＳ分析の結果、分子量６１６に対してｍ／ｅ＝６１６であった。 (2) Synthesis of Compound A Compound A was synthesized by the following steps.

Under an argon atmosphere, Intermediate A 19.5 g (40 mmol), Intermediate B 8.4 g (40 mmol) synthesized according to the method described in JP 2010-180204 A, Tris (dibenzylideneacetone) dipalladium 0.37 g (0. 4 mmol), 0.46 g (1.6 mmol) of tri-t-butylphosphonium tetrafluoroborate, 5.4 g (56 mmol) of t-butoxy sodium, and 100 ml of anhydrous toluene 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 / dichloromethane = 3/1) to obtain 16.0 g of Compound A (yield 65%) as a white solid.
As a result of FD-MS analysis, it was m / e = 616 with respect to molecular weight 616.

アルゴン雰囲気下、中間体Ｂ２０．９ｇ（１００ｍｍｏｌ）、３−ブロモヨードベンゼン２８．３ｇ（１００ｍｍｏｌ）、ヨウ化銅１９．０ｇ（１００ｍｍｏｌ）、ｔｒａｎｓ−１，２−シクロヘキサンジアミン１１．４ｇ（１００ｍｍｏｌ）、リン酸三カリウム４２．４ｇ（２００ｍｍｏｌ）を脱水１，４−ジオキサン１５０ｍｌに加えて、９６時間加熱還流攪拌した。反応溶液を減圧下で濃縮して得られた残渣に、トルエン５００ｍｌを加えて１２０℃に加熱し、不溶物を濾別した。濾液を減圧下で濃縮して得られた残渣をシリカゲルカラムクロマトグラフィー（ヘキサン／ジクロロメタン＝３／１）で精製することにより、中間体Ｃ２９．１ｇ（収率８０％）を淡黄色固体として得た。 Synthesis Example 2 [Synthesis of Compound B]
(1) Synthesis of Intermediate C Intermediate C was synthesized by the following steps.

Under an argon atmosphere, intermediate B 20.9 g (100 mmol), 3-bromoiodobenzene 28.3 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 150 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 / dichloromethane = 3/1) to obtain 29.1 g of intermediate C (yield 80%) as a pale yellow solid. .

アルゴン雰囲気下、国際公開第２００９−００８１００号パンフレットに記載の方法に従って合成した中間体Ｄ４．１ｇ（１０ｍｍｏｌ）に脱水テトラヒドロフラン（ＴＨＦ）５０ｍｌを加え、−７０℃で攪拌した。次いで、１．６Ｍのｎ−ブチルリチウムｎ−ヘキサン溶液６．２５ｍｌを滴下装入した。−７０℃で１時間攪拌した後、ホウ酸トリイソプロピル５．６ｇ（３０ｍｍｏｌ）を加え、−７０℃で１時間攪拌した後、室温で５時間攪拌した。反応液を濃縮後、ジクロロメタン４００ｍｌと１Ｎ塩酸５０ｍｌを加えて、氷水浴下で、１時間攪拌した。有機相を分取して、無水硫酸マグネシウムで乾燥してから濾液を濃縮した。得られた固体をヘキサン−トルエンの混合溶媒で懸濁洗浄することにより、中間体Ｅ２．３ｇ（収率６０％）を白色固体として得た。 (2) Synthesis of Intermediate E Intermediate E was synthesized by the following steps.

Under an argon atmosphere, 50 ml of dehydrated tetrahydrofuran (THF) was added to 4.1 g (10 mmol) of the intermediate D synthesized according to the method described in the pamphlet of International Publication No. 2009-008100, and the mixture was stirred at -70 ° C. Then, 6.25 ml of 1.6M n-butyllithium n-hexane solution was added dropwise. After stirring at −70 ° C. for 1 hour, 5.6 g (30 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, 400 ml of dichloromethane and 50 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 2.3 g of Intermediate E (yield 60%) as a white solid.

アルゴン雰囲気下、中間体Ｃ２．２ｇ（６ｍｍｏｌ）、中間体Ｅ２．３ｇ（６ｍｍｏｌ）、２Ｍ炭酸ナトリウム水溶液６ｍｌ、１，２−ジメトキシエタン（ＤＭＥ）６ｍｌ、トルエン２０ｍｌを加え、次いで、テトラキス（トリフェニルホスフィン）パラジウム０．２１ｇ（０．１８ｍｍｏｌ）を加えて、８時間加熱還流攪拌した。反応溶液を減圧下で濃縮して得られた残渣に、トルエン２００ｍｌを加えて１２０℃に加熱し、不溶物を濾別した。濾液を減圧下で濃縮して得られた残渣をシリカゲルカラムクロマトグラフィー（ヘキサン／トルエン＝３／１）で精製することにより、化合物Ｂ２．６ｇ（収率７０％）を白色固体として得た。
ＦＤ−ＭＳ分析の結果、分子量６１６に対してｍ／ｅ＝６１６であった。 (3) Synthesis of Compound B Compound B was synthesized by the following steps.

Under an argon atmosphere, Intermediate C 2.2 g (6 mmol), Intermediate E 2.3 g (6 mmol), 2 M aqueous sodium carbonate solution 6 ml, 1,2-dimethoxyethane (DME) 6 ml, toluene 20 ml were added, followed by tetrakis (triphenyl Phosphine) palladium 0.21 g (0.18 mmol) was added, and the mixture was heated to reflux with stirring for 8 hours. To the residue obtained by concentrating the reaction solution under reduced pressure, 200 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 = 3/1) to obtain 2.6 g (yield 70%) of compound B as a white solid.
As a result of FD-MS analysis, it was m / e = 616 with respect to molecular weight 616.

アルゴン雰囲気下、２，８−ジブロモジベンゾフラン３２．６ｇ（１００ｍｍｏｌ）、ジベンゾフラン−２−ボロン酸２１．２ｇ（１００ｍｍｏｌ）、２Ｍ炭酸ナトリウム水溶液１００ｍｌ、１，２−ジメトキシエタン（ＤＭＥ）１００ｍｌ、トルエン１００ｍｌを加え、次いで、テトラキス（トリフェニルホスフィン）パラジウム２．３１ｇ（２ｍｍｏｌ）を加えて、１５時間加熱還流攪拌した。反応溶液を減圧下で濃縮して得られた残渣に、トルエン１０００ｍｌを加えて１２０℃に加熱し、不溶物を濾別した。濾液を減圧下で濃縮して得られた残渣をシリカゲルカラムクロマトグラフィー（ヘキサン／トルエン＝３／１）で精製することにより、中間体Ｆ１４．５ｇ（収率３５％）を白色固体として得た。 Synthesis Example 3 [Synthesis of Compound C]
(1) Synthesis of Intermediate F Intermediate F was synthesized by the following steps.

Under an argon atmosphere, 32.6 g (100 mmol) of 2,8-dibromodibenzofuran, 21.2 g (100 mmol) of dibenzofuran-2-boronic acid, 100 ml of 2M aqueous sodium carbonate solution, 100 ml of 1,2-dimethoxyethane (DME), and 100 ml of toluene. Then, tetrakis (triphenylphosphine) palladium (2.31 g, 2 mmol) was added, and the mixture was heated to reflux with stirring for 15 hours. To the residue obtained by concentrating the reaction solution under reduced pressure, 1000 ml of toluene was added and heated to 120 ° C., and insoluble matters were filtered off. The filtrate was concentrated under reduced pressure, and the resulting residue was purified by silica gel column chromatography (hexane / toluene = 3/1) to obtain Intermediate F (14.5 g, yield 35%) as a white solid.

中間体Ｆ４．１ｇ（１０ｍｍｏｌ）を出発原料として、合成例２（２）の方法に従って、８−（ジベンゾフラン−２−イル）ジベンゾフラン−２−ボロン酸を合成し、中間体Ｃと合成例２（３）の方法に従って反応させることにより、化合物Ｃ２．８ｇ（収率４５％、２工程）を白色固体として得た。
ＦＤ−ＭＳ分析の結果、分子量６１７に対してｍ／ｅ＝６１７であった。 (2) Synthesis of Compound C Compound C was synthesized by the following steps.

8- (dibenzofuran-2-yl) dibenzofuran-2-boronic acid was synthesized according to the method of Synthesis Example 2 (2) using 4.1 g (10 mmol) of Intermediate F as a starting material, and Intermediate C and Synthesis Example 2 ( By reacting according to the method of 3), 2.8 g of compound C (yield 45%, 2 steps) was obtained as a white solid.
As a result of FD-MS analysis, it was m / e = 617 with respect to molecular weight 617.

アルゴン雰囲気下、２−ヨードジベンゾフラン３８ｇ（１５４ｍｍｏｌ）、３−ブロモカルバゾール４５．４ｇ（１５４ｍｍｏｌ）、ヨウ化銅８．８ｇ（４６．３ｍｍｏｌ）、ｔｒａｎｓ−１，２−シクロヘキサンジアミン１７．６ｇ（１５４ｍｍｏｌ）、リン酸三カリウム６８．８ｇ（３２４ｍｍｏｌ）を脱水１，４−ジオキサン７００ｍｌに加えて、１４時間加熱還流攪拌した。反応溶液を減圧下で濃縮して得られた残渣に、テトラヒドロフラン５００ｍｌを加えて撹拌し、シリカゲルを通して不溶物を濾別した。濾液を減圧下で濃縮して得られた残渣をトルエンに溶解してシリカゲルカラムクロマトグラフィー（トルエン１００％）で精製することにより、中間体Ｇ３８ｇ（収率５９％）を白色固体として得た。 Synthesis Example 4 [Synthesis of Compound D]
(1) Synthesis of intermediate G

Under an argon atmosphere, 2-iododibenzofuran 38 g (154 mmol), 3-bromocarbazole 45.4 g (154 mmol), copper iodide 8.8 g (46.3 mmol), trans-1,2-cyclohexanediamine 17.6 g (154 mmol) Then, 68.8 g (324 mmol) of tripotassium phosphate was added to 700 ml of dehydrated 1,4-dioxane, and the mixture was heated to reflux with stirring for 14 hours. To the residue obtained by concentrating the reaction solution under reduced pressure, 500 ml of tetrahydrofuran was added and stirred, and the insoluble material was filtered off through silica gel. The residue obtained by concentrating the filtrate under reduced pressure was dissolved in toluene and purified by silica gel column chromatography (toluene 100%) to obtain Intermediate G38g (yield 59%) as a white solid.

アルゴン雰囲気下、中間体Ｇ２．５ｇ（６．１ｍｍｏｌ）、中間体Ｂ１．４ｇ（６．１ｍｍｏｌ）、トリス（ジベンジリデンアセトン）ジパラジウム０．１１ｇ（０．１２ｍｍｏｌ）、トリ−ｔ−ブチルホスホニウムテトラフルオロほう酸塩０．１４ｇ（０．４８ｍｍｏｌ）、ｔ−ブトキシナトリウム０．８２ｇ（８．５ｍｍｏｌ）、無水トルエン５０ｍｌを順次加えて８時間加熱還流攪拌した。反応溶液を減圧下で濃縮して得られた残渣をシリカゲルカラムクロマトグラフィー（ヘキサン／ジクロロメタン＝２／３）で精製することにより、化合物Ｄ１．５ｇ（収率４５％）を白色固体として得た。
ＦＤ−ＭＳ分析の結果、分子量５４０に対してｍ／ｅ＝５４０であった。 (2) Synthesis of compound D

Under an argon atmosphere, Intermediate G 2.5 g (6.1 mmol), Intermediate B 1.4 g (6.1 mmol), Tris (dibenzylideneacetone) dipalladium 0.11 g (0.12 mmol), Tri-t-butylphosphonium tetra 0.14 g (0.48 mmol) of fluoroborate, 0.82 g (8.5 mmol) of t-butoxy sodium, and 50 ml of anhydrous toluene 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 / dichloromethane = 2/3) to give Compound D (1.5 g, yield 45%) as a white solid.
As a result of FD-MS analysis, it was m / e = 540 with respect to molecular weight 540.

アルゴン雰囲気下、中間体Ｆ３．０ｇ（７．３ｍｍｏｌ）、中間体Ｂ１．５ｇ（７．３ｍｍｏｌ）、トリス（ジベンジリデンアセトン）ジパラジウム０．１３ｇ（０．１４ｍｍｏｌ）、トリ−ｔ−ブチルホスホニウムテトラフルオロほう酸塩０．１７ｇ（０．５９ｍｍｏｌ）、ｔ−ブトキシナトリウム０．９８ｇ（１０．２ｍｍｏｌ）、無水トルエン６０ｍｌを順次加えて８時間加熱還流攪拌した。反応溶液を減圧下で濃縮して得られた残渣をシリカゲルカラムクロマトグラフィー（ヘキサン／トルエン＝１／２）で精製することにより、化合物Ｅ３．６ｇ（収率９１％）を白色固体として得た。
ＦＤ−ＭＳ分析の結果、分子量５４１に対してｍ／ｅ＝５４１であった。 Synthesis Example 5 [Synthesis of Compound E]

Under an argon atmosphere, Intermediate F 3.0 g (7.3 mmol), Intermediate B 1.5 g (7.3 mmol), Tris (dibenzylideneacetone) dipalladium 0.13 g (0.14 mmol), Tri-t-butylphosphonium tetra 0.17 g (0.59 mmol) of fluoroborate, 0.98 g (10.2 mmol) of t-butoxy sodium, and 60 ml of anhydrous toluene 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 = 1/2) to obtain 3.6 g (yield 91%) of compound E as a white solid.
As a result of FD-MS analysis, it was m / e = 541 with respect to the molecular weight 541.

The results of ¹ H-NMR measurement are shown below.
¹ H-NMR (400 MHz, CDCl ₃ ) δ 1.74 (6H, s), 6.31-6.34 (2H, m), 6.91-6.99 (4H, m), 7.34-7 .38 (1H, m), 7.43-7.50 (4H, m), 7.58-7.66 (2H, m), 7.71-7.75 (2H, m), 7.80 −7.85 (2H, m), 7.98-8.01 (1H, m), 8.02 (1H, d, J = 2.0 Hz), 8.18 (2H, dd, J = 1. 6Hz, 6.0Hz)

アルゴン雰囲気下、ジベンゾフラン−２−ボロン酸２１．２ｇ（１００ｍｍｏｌ）、３−ブロモカルバゾール２４．６ｇ（１００ｍｍｏｌ）、２Ｍ炭酸ナトリウム水溶液１００ｍｌ、１，２−ジメトキシエタン（ＤＭＥ）１００ｍｌ、トルエン１００ｍｌを加え、次いで、テトラキス（トリフェニルホスフィン）パラジウム２．３１ｇ（２ｍｍｏｌ）を加えて、２０時間加熱還流攪拌した。反応溶液を減圧下で濃縮して得られた残渣に、トルエン１０００ｍｌを加えて１２０℃に加熱し、不溶物を濾別した。濾液を減圧下で濃縮して得られた残渣をシリカゲルカラムクロマトグラフィー（トルエンのみ）で繰り返し精製することにより、中間体Ｈ１７．０ｇ（収率５１％）を白色固体として得た。 Synthesis Example 6 [Synthesis of Compound F]
(1) Synthesis of intermediate H

Under an argon atmosphere, 21.2 g (100 mmol) of dibenzofuran-2-boronic acid, 24.6 g (100 mmol) of 3-bromocarbazole, 100 ml of 2M aqueous sodium carbonate solution, 100 ml of 1,2-dimethoxyethane (DME), and 100 ml of toluene were added. Next, 2.31 g (2 mmol) of tetrakis (triphenylphosphine) palladium was added, and the mixture was heated to reflux with stirring for 20 hours. To the residue obtained by concentrating the reaction solution under reduced pressure, 1000 ml of toluene was added and heated to 120 ° C., and insoluble matters were filtered off. The residue obtained by concentrating the filtrate under reduced pressure was repeatedly purified by silica gel column chromatography (toluene only) to obtain 17.0 g of intermediate H (yield 51%) as a white solid.

アルゴン雰囲気下、中間体Ｈ１０．０ｇ（３０ｍｍｏｌ）、２−ブロモジベンゾフラン７．４ｇ（３０ｍｍｏｌ）、トリス（ジベンジリデンアセトン）ジパラジウム０．５５ｇ（０．６０ｍｍｏｌ）、トリ−ｔ−ブチルホスホニウムテトラフルオロほう酸塩０．７０ｇ（２．４ｍｍｏｌ）、ｔ−ブトキシナトリウム４．１ｇ（４２ｍｍｏｌ）、無水トルエン１５０ｍｌを順次加えて８時間加熱還流攪拌した。反応溶液を減圧下で濃縮して得られた残渣をシリカゲルカラムクロマトグラフィー（ジクロロメタンのみ）で精製し、さらに濃縮して得られた固体を１，２−ジメトキシエタンで洗浄することにより、中間体Ｉ９．５ｇ（収率６４％）を白色固体として得た。 (2) Synthesis of intermediate I

Under argon atmosphere, intermediate H 10.0 g (30 mmol), 2-bromodibenzofuran 7.4 g (30 mmol), tris (dibenzylideneacetone) dipalladium 0.55 g (0.60 mmol), tri-t-butylphosphonium tetrafluoroborate 0.70 g (2.4 mmol) of salt, 4.1 g (42 mmol) of t-butoxy sodium, and 150 ml of anhydrous toluene 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 (dichloromethane only), and the solid obtained by further concentration was washed with 1,2-dimethoxyethane to obtain intermediate I9. 0.5 g (64% yield) was obtained as a white solid.

アルゴン雰囲気下、中間体Ｉ９．５ｇ（１９ｍｍｏｌ）、Ｎ−ブロモコハク酸イミド３．４ｇ（１９ｍｍｏｌ）、無水Ｎ，Ｎ−ジメチルホルムアミド４０ｍｌを順次加えて５時間室温で攪拌した。反応溶液を減圧下で濃縮して得られた残渣をシリカゲルカラムクロマトグラフィー（ヘキサン／ジクロロメタン＝９／１〜１／９）で精製することにより、中間体Ｊ５．２ｇ（収率４７％）を白色固体として得た。 (3) Synthesis of intermediate J

Under an argon atmosphere, 9.5 g (19 mmol) of the intermediate I, 3.4 g (19 mmol) of N-bromosuccinimide and 40 ml of anhydrous N, N-dimethylformamide were sequentially added and stirred at room temperature for 5 hours. The residue obtained by concentrating the reaction solution under reduced pressure was purified by silica gel column chromatography (hexane / dichloromethane = 9/1 to 1/9) to obtain 5.2 g of intermediate J (yield 47%) as white. Obtained as a solid.

アルゴン雰囲気下、中間体Ｊ２．６６ｇ（４．６ｍｍｏｌ）、中間体Ｂ１．０ｇ（４．７８ｍｍｏｌ）、トリス（ジベンジリデンアセトン）ジパラジウム８４ｍｇ（０．０９２ｍｍｏｌ）、トリ−ｔ−ブチルホスホニウムテトラフルオロほう酸塩０．１１ｇ（０．３８ｍｍｏｌ）、ｔ−ブトキシナトリウム０．６２ｇ（６．４５ｍｍｏｌ）、無水トルエン５０ｍｌを順次加えて８時間加熱還流攪拌した。反応溶液を減圧下で濃縮して得られた残渣をシリカゲルカラムクロマトグラフィー（ヘキサン／トルエン＝１／１）で精製することにより、化合物Ｆ２．５ｇ（収率７６％）を白色固体として得た。
ＦＤ−ＭＳ分析の結果、分子量７０６に対してｍ／ｅ＝７０６であった。 (4) Synthesis of compound F

Under an argon atmosphere, Intermediate J 2.66 g (4.6 mmol), Intermediate B 1.0 g (4.78 mmol), Tris (dibenzylideneacetone) dipalladium 84 mg (0.092 mmol), Tri-t-butylphosphonium tetrafluoroborate 0.11 g (0.38 mmol) of salt, 0.62 g (6.45 mmol) of t-butoxy sodium, and 50 ml of anhydrous toluene 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 Compound F 2.5 g (yield 76%) as a white solid.
As a result of FD-MS analysis, it was m / e = 706 with respect to molecular weight 706.

[Organic EL device]
Example 1
[Production of organic EL element]
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, Compound I was deposited at a thickness of 20 nm to obtain a hole injection layer. Next, Compound II was deposited on the film at a thickness of 60 nm to obtain a hole transport layer.

  On this hole transport layer, Compound A as a phosphorescent host material and Compound D-1 as a phosphorescent material were co-evaporated 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, Compound H-1 was vapor-deposited with a thickness of 10 nm on the phosphorescent light emitting layer to obtain a first electron transporting layer. Further, Compound III was deposited at a thickness of 10 nm to obtain a second electron transport layer, and then 1 nm thick LiF and 80 nm thick metal Al were sequentially laminated to obtain a cathode. Note that LiF, which is an electron injecting electrode, was formed at a rate of 1 Å / min.
The compounds used in Examples and Comparative Examples are shown below.

[Light-emitting performance evaluation of organic EL elements]
The organic EL element produced as described above was caused to emit light by direct current drive, the luminance and current density were measured, and the voltage and luminous efficiency (external quantum efficiency) at a current density of 1 mA / cm ² were determined. Furthermore, the brightness | luminance 70% lifetime (time when a brightness | luminance falls to 70%) in initial stage brightness | luminance 3,000 cd / m < ² > was calculated | required. 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 B was used instead of Compound A as the phosphorescent host material. The results are shown in Table 1.

Example 3
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 first electron transport layer material. The results are shown in Table 1.

Example 4
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 first electron transport layer material. ,evaluated. The results are shown in Table 1.

Example 5
An organic EL device was prepared and evaluated in the same manner as in Example 1 except that Compound D was used instead of Compound A as the phosphorescent host material. The results are shown in Table 1.

Example 6
An organic EL device was prepared and evaluated in the same manner as in Example 1 except that Compound E was used instead of Compound A as the phosphorescent host material. The results are shown in Table 1.

Example 7
An organic EL device was prepared and evaluated in the same manner as in Example 1 except that Compound F was used instead of Compound A as the phosphorescent host material. 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-2 was used instead of Compound A as the phosphorescent host material. The results are shown in Table 1.

  Since the compound of the present invention has a dihydroacridine skeleton excellent in hole injectability, the devices of Examples 1 to 7 increased the amount of holes injected into the light emitting layer, and the voltage was lower than that of the device of the comparative example. In addition, when the compounds used in Examples 1 to 7 were combined with a dibenzofuran skeleton having electron resistance and electron transport performance, an element having improved charge balance and high luminous efficiency and a long lifetime was obtained.

Example 8
In Example 1, the hole transport layer was prepared by depositing Compound II with a thickness of 50 nm and further depositing Compound A with a thickness of 10 nm thereon, and the compound instead of Compound A as the phosphorescent host material in the light emitting layer. An organic EL element was produced in the same manner as in Example 1 except that H-1 was used, and the voltage and external quantum efficiency were evaluated in the same manner as in Example 1. The results are shown in Table 2.

Example 9
An organic EL device was prepared and evaluated in the same manner as in Example 8 except that Compound B was used instead of Compound A in the hole transport layer. The results are shown in Table 2.

Example 10
An organic EL device was prepared and evaluated in the same manner as in Example 8 except that Compound D was used instead of Compound A in the hole transport layer. The results are shown in Table 2.

Example 11
An organic EL device was prepared and evaluated in the same manner as in Example 8 except that Compound E was used instead of Compound A in the hole transport layer. The results are shown in Table 2.

Example 12
An organic EL device was prepared and evaluated in the same manner as in Example 8 except that Compound F was used instead of Compound A in the hole transport layer. The results are shown in Table 2.

Comparative Example 2
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 2.

  Since the compound of the present invention is excellent in hole injection property, it can also be used as a hole transport layer. In addition, since the compound of the present invention having a high triplet energy can confine a high triplet energy necessary for blue phosphorescence emission in the light emitting layer, a highly efficient blue phosphorescent light emitting device was obtained.

  Table 3 shows triplet energies of the compound of the present invention used as the hole transport layer and Compound II.

Triplet energy (E ^T (eV)) was evaluated by the following method.
First, a sample was dissolved in an EPA solvent (diethyl ether: isopentane: ethanol = 5: 5: 2 (volume ratio)) at 10 μmol / L to obtain a sample for phosphorescence measurement. This phosphorescence measurement sample was placed in a quartz cell, irradiated with excitation light at a temperature of 77 K, and the emitted phosphorescence spectrum was measured. Based on this, a value obtained by the conversion formula E ^T (eV) = 1239.85 / λ _edge was defined as triplet energy.
The above-mentioned “λ _edge ” means that when the phosphorescence spectrum is represented by taking the phosphorescence intensity on the vertical axis and the wavelength on the horizontal axis, the tangent line is drawn with respect to the rising _edge on the short wavelength side of the phosphorescence spectrum. Means the wavelength value (unit: nm) of the intersection.
For the measurement of the phosphorescence spectrum, an F-4500 type spectrofluorometer main body manufactured by Hitachi High-Technology Co., Ltd. and an optional component for low temperature measurement were used.

  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 instruments, a display board, a marker lamp, and the like.

Claims (14)

A compound represented by the following formula (A).

(In the formula (A), Ac is the following formula (1),
L ₁ and L ₂ are each a single bond, a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 12 ring carbon atoms, or a substituted or unsubstituted heteroaromatic ring having 5 to 18 ring atoms. Yes,
A is a substituted or unsubstituted dibenzofuran ring,
Ar is a hydrogen atom, a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 18 ring carbon atoms, or an unsubstituted heteroaromatic ring having 5 to 18 ring atoms.
However, when the heteroaromatic ring of L ₁ and L ₂ and the dibenzofuran ring of A have a substituent, the substituent is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted group, respectively. A cycloalkyl group having 3 to 20 ring carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkoxy group having 3 to 20 ring carbon atoms, a substituted or unsubstituted ring formation C6-C18 aromatic hydrocarbon ring, substituted or unsubstituted ring-forming aryloxy group having 6 to 18 carbon atoms, substituted or unsubstituted heteroaromatic ring having 5 to 18 ring atoms, substituted or unsubstituted A substituted amino group, a fluorine atom, a substituted or unsubstituted fluoroalkyl group having 1 to 20 carbon atoms, or a cyano group.

(In formula (1), X _{11 to} X ₁₈ are each CR ₄ or a nitrogen atom ,
R ₁ and R ₂ 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. It is a fluoroalkyl group of formula 1-20.
R ⁴ is a hydrogen atom.
* Indicates a binding position with the _{L 1.} )) The compound according to claim 1, wherein X _{11 to} X ₁₈ are each CR ₄ . The compound according to claim 1 or 2, wherein R ₁ and R ₂ are each a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms. The compound according to any one of claims 1 to 3, wherein R ₁ and R ₂ are both methyl groups.   Ar is a hydrogen atom, a substituted or unsubstituted benzene ring, an unsubstituted carbazole ring, an unsubstituted azacarbazole ring, an unsubstituted dihydroacridine ring, an unsubstituted dibenzofuran ring, or an unsubstituted dibenzothiophene ring Item 5. The compound according to any one of Items 1 to 4. The compound according to any one of claims 1 to 5, wherein one or both of L ₁ and L ₂ is a single bond.   The material for organic electroluminescent elements containing the compound in any one of Claims 1-6.   The organic electroluminescent element which has one or more organic thin film layers containing a light emitting layer between a cathode and an anode, and at least 1 layer contains the organic electroluminescent element material of Claim 7 among the said organic thin film layers.   The organic electroluminescent element according to claim 8, wherein the light emitting layer contains the material for an organic electroluminescent element as a host material.   The organic electroluminescent element according to claim 8 or 9, wherein the light emitting layer contains a phosphorescent material.   The organic electroluminescent device according to claim 10, wherein the phosphorescent material is an orthometalated complex of a metal atom selected from iridium (Ir), osmium (Os), and platinum (Pt).   The organic electroluminescence device according to any one of claims 8 to 11, further comprising an electron injection layer between the cathode and the light emitting layer, wherein the electron injection layer contains a nitrogen-containing ring derivative.   The organic electroluminescent element according to claim 8, further comprising an organic thin film layer between the cathode and the light emitting layer, wherein the organic thin film layer includes the material for an organic electroluminescent element.   The organic electroluminescent element according to claim 8, further comprising an organic thin film layer between the anode and the light emitting layer, wherein the organic thin film layer includes the material for the organic electroluminescent element.

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