JP2013108015A - Material for organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly efficient material for organic EL element.SOLUTION: The material for organic electroluminescent element is represented by formula (1), wherein X is oxygen atom or sulfur atom, one of G-Gis carbon atom bonded to L, each of the remaining G-Gis nitrogen atom or CR, each of Rand Ris hydrogen atom, 1-20C alkyl or the like, each of Ris 1-20C alkyl or the like, each of L, Lis single bond, 6-18C ring-forming arylene or 5-18C ring-forming heteroarylene, each of R is 1-20C alkyl or the like, each of a and b is an integer of 1-3, and n is an integer of 0-3.

Description

  The present invention relates to a material for an organic electroluminescence element and an organic electroluminescence element using the same.

Organic electroluminescence (EL) elements include a fluorescent type and a phosphorescent type, and an optimum element design has been studied according to each light emission mechanism. With respect to phosphorescent organic EL elements, it is known from their light emission characteristics that high-performance elements cannot be obtained by simple diversion of fluorescent element technology. 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 having high oxidation resistance and reduction resistance, which are useful in fluorescent elements, have a large energy spread 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, for example, Patent Document 1 discloses a compound having a carbazole skeleton and an adamantane skeleton as a material of a phosphorescent organic EL element that emits blue light.

International Publication No. 2003-080761 Pamphlet

  An object of the present invention is to provide a material for an organic EL element having a long lifetime.

（式（１）中、Ｘは、酸素原子又は硫黄原子である。
Ｇ_１１〜Ｇ_１８のうち１つは、Ｌ_１と結合する炭素原子であり、他のＧ_１１〜Ｇ_１８は、それぞれ、窒素原子又はＣＲ_０である。
Ｒ_０及びＲ_１は、それぞれ、水素原子、炭素数１〜２０のアルキル基、環形成炭素数３〜１８のシクロアルキル基、炭素数１〜２０のアルコキシ基、環形成炭素数３〜２０のシクロアルコキシ基、環形成炭素数６〜１８のアリールオキシ基、アミノ基、シリル基、フルオロ基、シアノ基、環形成炭素数６〜１８のアリール基、又は環形成原子数５〜１８のヘテロアリール基であり、これらは置換基Ｒで置換されていてもよい。
Ｒ_２は、それぞれ、炭素数１〜２０のアルキル基、環形成炭素数３〜１８のシクロアルキル基、炭素数１〜２０のアルコキシ基、環形成炭素数３〜２０のシクロアルコキシ基、環形成炭素数６〜１８のアリールオキシ基、アミノ基、シリル基、フルオロ基、シアノ基、環形成炭素数６〜１８のアリール基、又は環形成原子数５〜１８のヘテロアリール基であり、これらは置換基Ｒで置換されていてもよい。
Ｌ_１，Ｌ_２は、それぞれ、単結合、環形成炭素数３〜１８のシクロアルキレン基、環形成炭素数６〜１８のアリーレン基又は環形成原子数５〜１８のヘテロアリーレン基であり、これらは置換基Ｒで置換されていてもよい。
Ｒは、それぞれ、炭素数１〜２０のアルキル基、環形成炭素数３〜１８のシクロアルキル基、炭素数１〜２０のアルコキシ基、環形成炭素数３〜２０のシクロアルコキシ基、環形成炭素数６〜１８のアリールオキシ基、アミノ基、シリル基、フルオロ基、シアノ基、環形成炭素数６〜１８のアリール基、又は環形成原子数５〜１８のヘテロアリール基である。
ａ及びｂは、それぞれ１〜３の整数であり、ｎは０〜３の整数である。）
２．下記式（２）で表される１に記載の有機エレクトロルミネッセンス素子用材料。

（式（２）中、Ｘ、Ｇ_１１〜Ｇ_１８、Ｒ、Ｒ_０、Ｒ_１、Ｒ_２、Ｌ_１，Ｌ_２、ａ、ｂ及びｎは前記式（１）と同じである。）
３．下記式（３）で表される２に記載の有機エレクトロルミネッセンス素子用材料。

（式（３）中、Ｘ、Ｇ_１１〜Ｇ_１８、Ｒ、Ｒ_０、Ｒ_１、Ｒ_２、Ｌ_１，Ｌ_２、ａ、ｂ及びｎは前記式（１）と同じである。）
４．陰極と陽極の間に、発光層を含む１層以上の有機薄膜層を有し、前記有機薄膜層の少なくとも１層が、１〜３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用材料を含有する有機エレクトロルミネッセンス素子。
５．前記発光層、又は前記陰極と前記発光層の間の有機薄膜層の少なくとも１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有する４に記載の有機エレクトロルミネッセンス素子。
６．前記発光層が、ホスト材料及びりん光発光性材料を含有する４又は５に記載の有機エレクトロルミネッセンス素子。
７．前記りん光発光性材料が、イリジウム（Ｉｒ）又は白金（Ｐｔ）を含有する化合物である６に記載の有機エレクトロルミネッセンス素子。
８．前記イリジウム（Ｉｒ）又は白金（Ｐｔ）を含有する化合物が、オルトメタル化金属錯体である７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 organic EL element materials and the like are provided.
1. The material for organic electroluminescent elements represented by following formula (1).

(In Formula (1), X is an oxygen atom or a sulfur atom.
One of G _{11 to} G ₁₈ is a carbon atom bonded to L ₁ , and the other G _{11 to} G ₁₈ are a nitrogen atom or CR ₀ , respectively.
R ₀ and R ₁ are each a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 18 ring carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an alkyl group having 3 to 20 ring carbon atoms. Cycloalkoxy group, aryloxy group having 6 to 18 ring carbon atoms, amino group, silyl group, fluoro group, cyano group, aryl group having 6 to 18 ring carbon atoms, or heteroaryl having 5 to 18 ring atoms Which may be substituted with the substituent R.
R ₂ is an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 18 ring carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkoxy group having 3 to 20 ring carbon atoms, and a ring formation, respectively. An aryloxy group having 6 to 18 carbon atoms, an amino group, a silyl group, a fluoro group, a cyano group, an aryl group having 6 to 18 ring carbon atoms, or a heteroaryl group having 5 to 18 ring atoms. The substituent R may be substituted.
L ₁ and L ₂ are each a single bond, a cycloalkylene group having 3 to 18 ring carbon atoms, an arylene group having 6 to 18 ring carbon atoms, or a heteroarylene group having 5 to 18 ring atoms, and these May be substituted with a substituent R.
R is an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 18 ring carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkoxy group having 3 to 20 ring carbon atoms, and a ring forming carbon, respectively. These are an aryloxy group having 6 to 18 amino acids, an amino group, a silyl group, a fluoro group, a cyano group, an aryl group having 6 to 18 ring carbon atoms, or a heteroaryl group having 5 to 18 ring atoms.
a and b are each an integer of 1 to 3, and n is an integer of 0 to 3. )
2. The material for organic electroluminescence elements according to 1, which is represented by the following formula (2).

(In the formula (2), X, G _{11 to} G ₁₈ , R, R ₀ , R ₁ , R ₂ , L ₁ , L ₂ , a, b and n are the same as those in the formula (1).)
3. 2. The material for an organic electroluminescence element according to 2, which is represented by the following formula (3).

(In the formula (3), X, G _{11 to} G ₁₈ , R, R ₀ , R ₁ , R ₂ , L ₁ , L ₂ , a, b and n are the same as those in the formula (1).)
4). It has one or more organic thin film layers including a light emitting layer between a cathode and an anode, and at least one layer of the organic thin film layer contains the organic electroluminescent element material according to any one of 1 to 3. Organic electroluminescence device.
5. 5. The organic electroluminescent element according to 4, wherein at least one of the light emitting layer or the organic thin film layer between the cathode and the light emitting layer contains the material for an organic electroluminescent element.
6). 6. The organic electroluminescence device according to 4 or 5, wherein the light emitting layer contains a host material and a phosphorescent material.
7). 7. The organic electroluminescence device according to 6, wherein the phosphorescent material is a compound containing iridium (Ir) or platinum (Pt).
8). 8. The organic electroluminescence device according to 7, wherein the compound containing iridium (Ir) or platinum (Pt) is an orthometalated metal complex.

  According to the present invention, a long-life organic EL element material can be provided.

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（１）中、Ｘは、酸素原子又は硫黄原子である。
Ｇ_１１〜Ｇ_１８のうち１つは、Ｌ_１と結合する炭素原子であり、他のＧ_１１〜Ｇ_１８は、それぞれ、窒素原子又はＣＲ_０である。 The organic electroluminescence (EL) element material of the present invention is represented by the following formula (1).

In formula (1), X is an oxygen atom or a sulfur atom.
One of G _{11 to} G ₁₈ is a carbon atom bonded to L ₁ , and the other G _{11 to} G ₁₈ are a nitrogen atom or CR ₀ , respectively.

R ₀ and R ₁ are each a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 18 ring carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an alkyl group having 3 to 20 ring carbon atoms. Cycloalkoxy group, aryloxy group having 6 to 18 ring carbon atoms, amino group, silyl group, fluoro group, cyano group, aryl group having 6 to 18 ring carbon atoms, or heteroaryl having 5 to 18 ring atoms Which may be substituted with the substituent R.

R ₀ is preferably a hydrogen atom, an adamantyl group, a fluoro group, a cyano group, an aryl group having 6 to 18 ring carbon atoms, or a heteroaryl group having 5 to 18 ring atoms, more preferably a hydrogen atom, A fluoro group, a cyano group, a phenyl group, a biphenyl group, a terphenyl group, a triphenylene group, a pyridyl group, a pyrimidyl group, or a 1,3,5-triazinyl group.

R ₁ is preferably a hydrogen atom, an adamantyl group, an aryl group having 6 to 18 ring carbon atoms, or a heteroaryl group having 5 to 18 ring atoms, more preferably a hydrogen atom, a phenyl group, a biphenyl group, Terphenyl group, triphenylene group, pyridyl group, pyrimidyl group, 1,3,5-triazinyl group, carbazolyl group, azacarbazolyl group, diazacarbazolyl group, or the same as the group represented by A in the above formula (1) It is the basis of.

R ₂ is an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 18 ring carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkoxy group having 3 to 20 ring carbon atoms, and a ring formation, respectively. An aryloxy group having 6 to 18 carbon atoms, an amino group, a silyl group, a fluoro group, a cyano group, an aryl group having 6 to 18 ring carbon atoms, or a heteroaryl group having 5 to 18 ring atoms. The substituent R may be substituted. When n is 2 or more, the plurality of R ₂ may be the same or different from each other.

L ₁ and L ₂ are each a single bond, a cycloalkylene group having 3 to 18 ring carbon atoms, an arylene group having 6 to 18 ring carbon atoms, or a heteroarylene group having 5 to 18 ring atoms, These may be substituted with a substituent R. When a is 2 or more, the plurality of L ₁ may be the same or different, and when b is 2 or more, the plurality of L ₂ may be the same or different.
L ₁ and L ₂ are preferably the same group.

L ₁ and L ₂ are each preferably an adamantylene group (a divalent group corresponding to an adamantyl group), an arylene group having 6 to 18 ring carbon atoms, or a heteroarylene group having 5 to 18 ring atoms. It is.
When adamantane is directly bonded to a planar π-conjugated skeleton (arylene group or heteroarylene group), the effect of suppressing aggregation of the π-conjugated skeleton increases.

L ₁ and L ₂ are more preferably each a heteroarylene group having 5 to 18 ring atoms, specifically a pyridyl group, a pyrimidyl group, a 1,3,5-triazinyl group, a carbazolyl group, or an azacarbazolyl group. A divalent group corresponding to the same group as the group, diazacarbazolyl group, or group represented by A in the above formula (1) is preferable.

  R is an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 18 ring carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkoxy group having 3 to 20 ring carbon atoms, and a ring forming carbon, respectively. These are an aryloxy group having 6 to 18 amino acids, an amino group, a silyl group, a fluoro group, a cyano group, an aryl group having 6 to 18 ring carbon atoms, or a heteroaryl group having 5 to 18 ring atoms.

a and b are each an integer of 1 to 3, and n is an integer of 0 to 3. a and b are preferably 1, and n is preferably 0.
Note that the bonding positions of L ₁ , L ₂ and R ₂ in the adamantane skeleton are not limited.

The compound of the present invention is advantageous in the following points by having an adamantane skeleton.
1. The glass transition point can be increased.
2. Since the adamantane skeleton has a structure that does not have a π-conjugation effect, even if it is bonded to a π-conjugated skeleton such as aryl or heteroaryl, the singlet energy (Eg (S), S1) and Triplet energy (Eg (T), T1), ionization potential (Ip), and affinity (Af) are hardly affected. Therefore, by having an adamantane skeleton, a substituent can be introduced without causing a decrease in the energy gap of the compound.
3. The adamantane skeleton has higher chemical stability than acyclic alkyl.

In the compound of the present invention, X is preferably an oxygen atom. That is, it has a dibenzofuran skeleton or a dibenzofuran-like skeleton in which any one or more of G _{11 to} G ₁₈ are nitrogen atoms.
By having a dibenzofuran skeleton or a dibenzofuran-like skeleton, the following points are advantageous.
1. Since the triplet energy is a wide gap as a skeleton, the energy confinement effect of the luminescent dopant is high, and it is used as a luminescent layer host material or a luminescent layer peripheral material in that it realizes a highly efficient device especially in a phosphorescent device emitting short wavelengths. It is suitable for.
2. Since Af is larger than carbazole, electron injection from the cathode side adjacent layer is easier than carbazole, and the voltage is likely to be lowered.
3. It has a higher electron transport property than carbazole and is easy to lower the voltage.

In the compound of the present invention, it is preferable that at least one of L ₁ and L ₂ is bonded to the tertiary carbon of the adamantane skeleton, that is, the 1-position carbon. More preferably, it is preferable that both L ₁ and L ₂ are bonded to the tertiary carbon of the adamantane skeleton, that is, the 1-position and 3-position carbon.

When an aryl group or heteroaryl group (L ₁ , L ₂ ) is bonded to the 1-position carbon of the adamantane skeleton, the 1-position carbon becomes a quaternary carbon, and a benzyl-position hydrogen atom that is a concern about chemical instability is not generated. It is considered that the chemical stability of the compound is increased.
The benzylic hydrogen atom is a hydrogen atom activated by the π conjugation effect on the carbon adjacent to the aryl group or heteroaryl group.

Further, when both L ₁ and L ₂ are bonded to the tertiary carbon of the adamantane skeleton, that is, when the 1st and 3rd positions of the adamantane skeleton are used as linking sites, the following points are advantageous.
-It is possible to reduce benzylic hydrogen atoms, which are inferior in chemical stability, as compared to the case of linking at the 1st and 2nd positions of the adamantane skeleton.
-Compared to the case of linking at the 1st and 2nd positions, or the 2nd and 2nd positions of the adamantane skeleton, the distance between the connecting substituents is increased, and steric repulsion can be reduced, improving the stability of the compound. be able to.

式（２）中、Ｘ、Ｇ_１１〜Ｇ_１８、Ｒ_０、Ｒ_１、Ｒ_２、Ｌ_１，Ｌ_２、ａ、ｂ及びｎは上記式（１）と同じである。
尚、アダマンタン骨格におけるＬ_２、Ｒ_２の結合位置は限定されない。 The organic electroluminescent element material of the present invention is preferably represented by the following formula (2).

In the formula (2), X, G _{11 to} G ₁₈ , R ₀ , R ₁ , R ₂ , L ₁ , L ₂ , a, b and n are the same as in the above formula (1).
The bonding positions of L ₂ and R ₂ in the adamantane skeleton are not limited.

式（３）中、Ｘ、Ｇ_１１〜Ｇ_１８、Ｒ_０、Ｒ_１、Ｒ_２、Ｌ_１，Ｌ_２、ａ、ｂ及びｎは上記式（１）と同じである。
尚、アダマンタン骨格におけるＲ_２の結合位置は限定されない。 The organic electroluminescent element material of the present invention is more preferably represented by the following formula (3).

In the formula (3), X, G _{11 to} G ₁₈ , R ₀ , R ₁ , R ₂ , L ₁ , L ₂ , a, b and n are the same as those in the above formula (1).
The bonding position of R _{2 in} the adamantane skeleton is not limited.

  The molecular weight of the compound of the present invention is usually 400 or more, preferably 1000 or less, more preferably 800 or less.

In addition to the adamantane skeleton represented by B in the formula (1), the compound of the present invention may be a monovalent or divalent cycloalkyl group having 3 to 18 ring carbon atoms (preferably a monovalent or divalent valent group). It is preferable to have 1 to 5, preferably 1 to 3 adamantyl groups). In this case, the compound of the present invention has an adamantyl group as, for example, R ₀ , R ₁ , R ₂ , L ₁ and / or L ₂ .
The cycloalkyl group may be substituted with a substituent R.

  A larger number of the cycloalkyl groups (preferably adamantyl groups) is preferable because aggregation of the π-conjugated skeleton is easily suppressed. On the other hand, when the compound of the present invention is used for vapor deposition, if the molecular weight increases, the temperature required for sublimation becomes high and competes with the thermal decomposition, so that the molecular weight does not become too large, that is, the number of the cycloalkyl groups is increased. Preferably not too much.

Hereinafter, examples of each group of the above-described formula (1) 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 are preferable, and a methyl group, an ethyl group, a propyl group, an isopropyl group, and n-butyl are preferable. 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 18 carbon atoms include cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, 1-adamantyl group, 2-adamantyl group, 1-norbornyl group, 2-norbornyl group and the like. Are a cyclopentyl group, a cyclohexyl group, a 1-adamantyl group, and a 2-adamantyl group.
Examples of the cycloalkylene group having 3 to 18 carbon atoms include divalent groups of the above-described groups, and preferably 1,2-adamantylene group, 1,3-adamantylene group, 2,2-adamantylene group. It is.

Alkoxy group having 1 to 20 carbon atoms is expressed as -OY _1, examples of the above alkyl may be mentioned as examples of _{Y 1.} 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 _2, and examples of Y ₂ include the above cycloalkyl groups. The cycloalkoxy group is, for example, a cyclopentyloxy group or a cyclohexyloxy group.

The aryl group having 6 to 18 ring carbon atoms is preferably an aryl group 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 aryl group include phenyl, naphthyl, anthryl, phenanthryl, naphthacenyl, pyrenyl, chrysenyl, benzo [c] phenanthryl, benzo [g] chrysenyl, triphenylenyl, fluorenyl Group, benzofluorenyl group, dibenzofluorenyl group, biphenylyl group, terphenyl group, quarterphenyl group, fluoranthenyl group, etc., preferably phenyl group, biphenyl group, terphenyl group, tolyl group, A xylyl group, a naphthyl group, a phenanthryl group, and a triphenylenyl group.
Examples of the arylene group include divalent groups of the above-described groups.

An aryloxy group having 6 to 18 ring carbon atoms is represented as —OY _3, and examples of Y ₃ include the above aryl groups. The aryloxy group is, for example, a phenoxy group.

The heteroaryl group having 5 to 18 ring atoms is preferably a heteroaryl group having 5 to 10 ring atoms.
Specific examples of the monovalent heteroaryl group 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. Nyl group, dibenzothiophenyl group, azadibenzofuranyl group, azadibenzothiophenyl group, diazadibenzofuranyl group, diazadibenzothiophenyl group, quinolyl group, isoquinolyl group, quinoxalinyl group, carbazolyl group, phenanthridinyl Group, acridinyl group, phenanthrolinyl group, phenazinyl group, phenothiazinyl group, phenoxazinyl group, oxazolyl group, oxadiazolyl group, furazanyl group, thienyl group, benzothiophenyl group, dihydroacridinyl group, azacarbazolyl group And diazacarbazolyl group, quinazolinyl group, etc., preferably pyridinyl group, pyrimidinyl group, triazinyl group, dibenzofuranyl group, dibenzothiophenyl group, azadibenzofuranyl group, azadibenzothiophenyl group, diaza A dibenzofuranyl group, a diazadibenzothiophenyl group, a carbazolyl group, an azacarbazolyl group, and a diazacarbazolyl group;
Examples of the heteroarylene group include the divalent groups described above.

  The amino group substituted with R is an alkylamino group or dialkylamino group having 1 to 10 carbon atoms (preferably 1 to 6 carbon atoms), 6 to 30 carbon atoms (preferably 6 to 20 carbon atoms, more preferably Examples thereof include an arylamino group or a diarylamino group having 6 to 10 carbon atoms.

Examples of the silyl group substituted with R include a silyl group, an alkylsilyl group having 1 to 10 carbon atoms (preferably 1 to 6 carbon atoms), 6 to 30 carbon atoms (preferably 6 to 20 carbon atoms, more preferably carbon atoms). The arylsilyl group of several 6-10) etc. are mentioned.
Specific examples of the alkylsilyl group include a trimethylsilyl group, a triethylsilyl group, a t-butyldimethylsilyl group, a vinyldimethylsilyl group, and a propyldimethylsilyl group.
Specific examples of the arylsilyl group include a triphenylsilyl group, a phenyldimethylsilyl group, a t-butyldiphenylsilyl group, a tolylsilyl group, a trixylsilyl group, and a trinaphthylsilyl group.

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

  The material for an organic EL device of the present invention is particularly preferable as a light emitting layer of an organic EL device that emits phosphorescence or a layer adjacent to the light emitting layer, for example, a material of 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 1 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% by weight (wt%), more preferably 0.1 to 20% by weight (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, when a layer containing the material of the present invention (an 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 an electron barrier layer, and the organic layer for preventing holes from leaking from the light-emitting layer to the electron transport zone is defined as a hole barrier. Sometimes defined as a layer. In addition, an exciton blocking layer (triplet barrier layer) is an organic layer for preventing triplet excitons generated in the light emitting layer from diffusing into a peripheral layer having triplet energy lower than that of the light emitting layer. It may be defined as
Further, the material of the present invention can be used for a layer adjacent to the phosphorescent light emitting layer 40 and further used for another organic thin film layer bonded to the adjacent layer.

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. The ligands include quinolinol, benzoquinolinol, acridinol, phenanthridinol, hydroxyphenyl oxazole, hydroxyphenyl thiazole, hydroxydiaryl thiadiazole, hydroxydiaryl thiadiazole, hydroxyphenylpyridine, hydroxyphenylbenzimidazole, hydroxybenzotriazole, Hydroxyfulborane, bipyridyl, phenanthroline, phthalocyanine, porphyrin, cyclopentadiene, β-diketones, azomethines, and derivatives thereof are preferred, but are not limited thereto.

  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 the donor dopant and the organometallic complex 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 resistance heating vapor deposition, preferably with an island thickness of 0.05 nm or more and 1 nm or less.

  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 injection / transport layer, a material that transports holes to the light emitting layer with a lower electric field strength is preferable, and the mobility of holes is, for example, when an electric field of 10 ⁴ to 10 ⁶ V / cm is applied, 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, phenanthroline ring, quinazoline ring and the like.

  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.

  Next, the present invention will be described in further detail using synthesis examples and examples. However, the present invention is not limited to the following synthesis examples and examples.

In addition, the evaluation method of a compound is as follows.
(1) Triplet energy It measured using commercially available apparatus F-4500 (made by Hitachi High-Technologies Corporation). The conversion formula of triplet energy Eg (T) is as follows.
Eg (T) (eV) = 1239.85 / λ _ph

In the formula, “λ _ph ” represents a phosphorescence spectrum with the vertical axis representing the phosphorescence intensity and the horizontal axis representing the wavelength, and a tangent line is drawn with respect to the rising edge of the phosphorescence spectrum on the short wavelength side. It means the wavelength value (unit: nm) at the intersection of the tangent and the horizontal axis.
Each compound was dissolved in an EPA solvent (diethyl ether: isopentane: ethanol = 5: 5: 2 (volume ratio), each solvent is a spectroscopic grade) (sample: 10 μmol / L) to prepare a sample for phosphorescence measurement.
The phosphorescence spectrum was measured using F-4500 manufactured by Hitachi, Ltd. Specifically, the phosphorescence measurement sample placed in the quartz cell was cooled to 77 (K), and the phosphorescence measurement sample was irradiated with excitation light, and the phosphorescence intensity was measured while changing the observation wavelength. In the phosphorescence spectrum, the vertical axis represents phosphorescence intensity and the horizontal axis represents wavelength. A tangent line was drawn with respect to the rising edge of the phosphorescence spectrum on the short wavelength side, and the wavelength value λ _ph (nm) at the intersection of the tangent line and the horizontal axis was obtained.

The tangent to the rising edge on the short wavelength side of the phosphorescence spectrum is drawn as follows. When moving on the spectrum curve from the short wavelength side of the phosphorescence spectrum to the maximum value on the shortest wavelength side among the maximum values of the spectrum, tangents at each point on the curve are considered toward the long wavelength side. The slope of this tangent line increases as the curve rises (that is, as the vertical axis increases). The tangent drawn at the point where the value of the slope takes the maximum value is the tangent to the rising edge of the phosphorescence spectrum on the short wavelength side.
Note that the maximum point having a peak intensity of 10% or less of the maximum peak intensity of the spectrum is not included in the above-mentioned maximum value on the shortest wavelength side, and has the maximum slope value closest to the maximum value on the shortest wavelength side. The tangent drawn at the point where the value is taken is taken as the tangent to the rising edge of the phosphorescence spectrum on the short wavelength side.

(2) Glass transition point As for the glass transition point, a DSC8500 manufactured by Perkin Elmer Co., Ltd. is used, and a temperature rising and cooling process of the following two cycles (i) to (vi) is performed using a sample of about 3 mg. It is defined by the rising temperature of the inflection point where the baseline of the DSC curve at the time of temperature rise changes stepwise.

(I) Hold at 30 ° C. for 1 minute.
(Ii) Heat from 30 ° C. to a constant temperature below the thermal decomposition temperature of the sample at a heating rate of 10 ° C./min.
(Iii) Hold at the constant temperature for 3 minutes.
(Iv) Cool from the constant temperature to 0 ° C. at 200 ° C./min.
(V) Hold at 0 ° C. for 10 minutes.
(Vi) Heat from 0 ° C. to 200 ° C. at a heating rate of 10 ° C./min.

(3) Ionization potential (Ip)
For the ionization potential, a single layer of each layer is separately prepared by vacuum deposition on an ITO glass substrate, and a photoelectron spectrometer (manufactured by Riken Keiki Co., Ltd .: AC-3) is used in the air using a thin film on the ITO glass substrate. And measured. Specifically, the measurement was performed by irradiating the material with light and measuring the amount of electrons generated by charge separation at that time. The emitted photoelectrons were plotted by the 1/2 power with respect to the energy of the irradiation light, and the threshold of the photoelectron emission energy was defined as the ionization potential (Ip).

(4) Affinity (Af)
The affinity was calculated from the measured values of the ionization potential Ip and the energy gap Eg (singlet energy Eg (S)). The calculation formula is as follows.
Af = Ip-Eg
The energy gap Eg was measured from the absorption edge of the absorption spectrum in the toluene solution. Specifically, the absorption spectrum was measured using a commercially available visible / ultraviolet spectrophotometer, and calculated from the falling wavelength on the long wavelength side of the spectrum.

The conversion formula is as follows.
Eg (eV) = 1239.85 / λ _ab
The absorption spectrum was obtained by taking the absorbance on the vertical axis and the wavelength on the horizontal axis. In the above conversion formula relating to the energy gap Eg, “λ _ab ” (unit: nm) means a wavelength value at the intersection of the tangent line and the horizontal axis with respect to the falling edge of the absorption spectrum on the long wavelength side.
Each compound was dissolved in a toluene solvent (sample 2 × 10 ⁻⁵ mol / liter), and a sample was prepared so that the optical path length was 1 cm. Absorbance was measured while changing the wavelength.

The tangent to the falling edge on the long wavelength side of the absorption spectrum is drawn as follows.
When moving on the spectrum curve in the long wavelength direction from the maximum value on the longest wavelength side among the maximum values of the absorption spectrum, the tangent at each point on the curve is considered. This tangent repeats increasing in slope and then increasing as the curve falls (ie, as the vertical axis decreases). The tangent drawn at the point where the slope value takes the minimum value on the long wavelength side (except when the absorbance is 0.1 or less) is taken as the tangent to the fall on the long wavelength side of the absorption spectrum.
In addition, the maximum point whose absorbance value is 0.2 or less is not included in the maximum value on the longest wavelength side.

Moreover, the evaluation method of an organic EL element is as follows.
(1) External quantum efficiency (%)
The external quantum efficiency at a luminance of 1000 cd / m ² under a dry nitrogen gas atmosphere at 23 ° C. was measured using a luminance meter (Spectral luminance radiometer CS-1000 manufactured by Minolta).

(2) Half life (hours)
A continuous energization test (DC) was performed at an initial luminance of 1000 cd / m ² and the time until the initial luminance was reduced by half was measured.

(3) Voltage (V)
Using a KEITLY 236 SOURCE MEASURE UNIT under a dry nitrogen gas atmosphere at 23 ° C., voltage was applied to the electrically wired element to emit light, and the voltage applied to the wiring resistance other than the element was subtracted to measure the element applied voltage. .
Simultaneously with the application and measurement of the voltage, the luminance was also measured using a luminance meter (spectral luminance radiometer CS-1000 manufactured by Minolta Co., Ltd.), and the voltage when the element luminance was 1000 cd / m ² was read from these measurement results.

三口フラスコに３−ブロモ−Ｎ−フェニルカルバゾール（３５．４ｇ，１１０ｍｍｏｌ）、１，３−アダマンタンジオール（８．４１ｇ，５０ｍｍｏｌ）、メタンスルホン酸（６．５ｍｌ）、クロロベンゼン（５０ｍｌ）を入れ、窒素雰囲気下にて１２０℃で１２時間加熱撹拌した。
反応終了後、試料溶液をビーカーに移し、水酸化ナトリウム水溶液にてｐＨ１０以上となるよう中和を行い、その後、分液ロートを用いてトルエンで有機相を抽出した。無水硫酸マグネシウムで乾燥後、ろ過、濃縮を行った。その後、シリカゲルクロマトグラフィー（展開溶媒 ヘキサン：トルエン＝６：４）で精製し、さらに酢酸エチル／ヘキサン混合溶媒で分散洗浄を行い、白色の固体を得た。化合物の同定はＦＤ−ＭＳ及び^１Ｈ−ＮＭＲにて行った。収量は２４．５ｇ、収率は６３％であった。 Synthesis Example 1 [Synthesis of Compound 1]
(1) Synthesis of compound 1-a

A 3-necked flask was charged with 3-bromo-N-phenylcarbazole (35.4 g, 110 mmol), 1,3-adamantanediol (8.41 g, 50 mmol), methanesulfonic acid (6.5 ml), chlorobenzene (50 ml), and nitrogen. The mixture was heated and stirred at 120 ° C. for 12 hours under an atmosphere.
After completion of the reaction, the sample solution was transferred to a beaker, neutralized with an aqueous sodium hydroxide solution to have a pH of 10 or more, and then the organic phase was extracted with toluene using a separatory funnel. After drying over anhydrous magnesium sulfate, filtration and concentration were performed. Thereafter, the product was purified by silica gel chromatography (developing solvent hexane: toluene = 6: 4), and further dispersed and washed with a mixed solvent of ethyl acetate / hexane to obtain a white solid. The compound was identified by FD-MS and ¹ H-NMR. The yield was 24.5 g, and the yield was 63%.

三口フラスコに化合物１−ａ（９．７ｇ，１２．５ｍｍｏｌ）、２−ジベンゾフランボロン酸（６．３６ｇ，３０ｍｍｏｌ）、炭酸ナトリウム２Ｍ水溶液（２５ｍｌ）、Ｐｄ（ＰＰｈ_３）_４（０．５８ｇ，０．５ｍｍｏｌ）、１，２−ジメトキシエタン（２５ｍｌ）、トルエン（２５ｍｌ）を加え１０時間還流させた。 (2) Synthesis of Compound 1

In a three-necked flask, compound 1-a (9.7 g, 12.5 mmol), 2-dibenzofuranboronic acid (6.36 g, 30 mmol), sodium carbonate 2M aqueous solution (25 ml), Pd (PPh ₃ ) ₄ (0.58 g, 0 0.5 mmol), 1,2-dimethoxyethane (25 ml) and toluene (25 ml) were added and refluxed for 10 hours.

  After completion of the reaction, methanol and water were added to the reaction solution, and the deposited sample was collected by filtration and washed with water. This was dissolved in 500 ml of toluene, dried over anhydrous magnesium sulfate, and purified by silica gel chromatography (hexane: toluene = 1: 1). Further, this was recrystallized from a toluene / ethyl acetate mixed solvent to obtain a white solid. The yield was 7.60 g, and the yield was 64%.

三口フラスコにＮ−（２−ジベンゾフラニル）カルバゾール（１６．６７ｇ，５０ｍｍｏｌ）、１，３−アダマンタンジオール（１．６８ｇ，１０ｍｍｏｌ）、メタンスルホン酸（１．３ｍｌ）、１，２−ジクロロエタン（２０ｍｌ）を入れ、窒素雰囲気下にて１８時間還流させた。
反応終了後、試料溶液をビーカーに移し、水酸化ナトリウム水溶液にてｐＨ１０以上となるよう中和を行い、その後、分液ロートを用いてトルエンで有機相を抽出した。無水硫酸マグネシウムで乾燥後、ろ過、濃縮を行った。その後、シリカゲルクロマトグラフィー（展開溶媒 ヘキサン：トルエン＝６：４）で精製し、さらに酢酸エチル／ヘキサン混合溶媒で分散洗浄を行い、白色の固体を得た。化合物の同定は、ＦＤ−ＭＳ及び^１Ｈ−ＮＭＲにて行った。収量は１．８５ｇ、収率は２３％であった。 Synthesis Example 2 [Synthesis of Compound 2]

In a three-necked flask, N- (2-dibenzofuranyl) carbazole (16.67 g, 50 mmol), 1,3-adamantanediol (1.68 g, 10 mmol), methanesulfonic acid (1.3 ml), 1,2-dichloroethane ( 20 ml) and refluxed for 18 hours under a nitrogen atmosphere.
After completion of the reaction, the sample solution was transferred to a beaker, neutralized with an aqueous sodium hydroxide solution to have a pH of 10 or more, and then the organic phase was extracted with toluene using a separatory funnel. After drying over anhydrous magnesium sulfate, filtration and concentration were performed. Thereafter, the product was purified by silica gel chromatography (developing solvent hexane: toluene = 6: 4), and further dispersed and washed with a mixed solvent of ethyl acetate / hexane to obtain a white solid. The compound was identified by FD-MS and ¹ H-NMR. The yield was 1.85 g, and the yield was 23%.

三口フラスコに１−アダマンタノール（６．６７ｇ，２０ｍｍｏｌ）、Ｎ−（２−ジベンゾフラニル）カルバゾール（６．３９ｇ，４２ｍｍｏｌ）、メタンスルホン酸（２．６ｍｌ）、１，２−ジクロロエタン（２０ｍｌ）を入れ、窒素雰囲気下にて１８時間還流させた。 Synthesis Example 3 [Synthesis of Compound 3]

In a three-necked flask, 1-adamantanol (6.67 g, 20 mmol), N- (2-dibenzofuranyl) carbazole (6.39 g, 42 mmol), methanesulfonic acid (2.6 ml), 1,2-dichloroethane (20 ml) And refluxed for 18 hours under a nitrogen atmosphere.

After completion of the reaction, the sample solution was transferred to a beaker, neutralized with an aqueous sodium hydroxide solution to have a pH of 10 or more, and then the organic phase was extracted with toluene using a separatory funnel. After drying over anhydrous magnesium sulfate, filtration and concentration were performed. Thereafter, the residue was purified by silica gel chromatography (developing solvent hexane: toluene = 6: 4), and recrystallized from a mixed solvent of ethyl acetate / hexane to obtain a white solid. The compound was identified by FD-MS and ¹ H-NMR. The yield was 4.57 g, and the yield was 38%.

Ｎ−（２−ジベンゾフラニル）カルバゾールの代わりに、化合物４−ａを用いた他は合成例３と同様に化合物４を合成した。 Synthesis Example 4 [Synthesis of Compound 4]

Compound 4 was synthesized in the same manner as in Synthesis Example 3, except that compound 4-a was used instead of N- (2-dibenzofuranyl) carbazole.

Table 1 shows the physical property values of the synthesized compounds 1-4.

Comparative Example 1
A glass substrate with a 130 nm-thick ITO electrode line (manufactured by Geomatec) was ultrasonically cleaned in isopropyl alcohol for 5 minutes, and then UV ozone cleaning was performed for 30 minutes.
The glass substrate with the ITO electrode line after the cleaning is mounted on the substrate holder of the vacuum deposition apparatus, and the compound (HI1) is first thickened so as to cover the ITO electrode line on the surface on which the ITO electrode line is formed. The compound (HT1) was deposited by resistance heating at a thickness of 60 nm at a thickness of 20 nm, and thin films were sequentially formed. The film formation rate was 1 Å / s. These thin films function as a hole injection layer and a hole transport layer, respectively.

  Next, on the hole injection / transport layer, the compound (A1) and the compound (BD1) were simultaneously deposited by resistance heating to form a thin film having a thickness of 50 nm. At this time, the compound (BD1) was deposited so as to have a mass ratio of 20% with respect to the total mass of the compound (A1) and the compound (BD1). The film formation rates were 1.2 Å / s and 0.3 Å / s, respectively. This thin film functions as a phosphorescent light emitting layer.

  Next, a thin film having a thickness of 10 nm was formed on the phosphorescent light emitting layer by resistance heating vapor deposition of the compound (H1). The film formation rate was 1.2 liter / s. This thin film functions as a barrier layer. Next, a thin film having a thickness of 10 nm was formed on this barrier layer by resistance heating vapor deposition of the compound (ET1). The film formation rate was 1 Å / s. This film functions as an electron injection layer.

Next, LiF having a film thickness of 1.0 nm was deposited on the electron injection layer at a film formation rate of 0.1 Å / s. Next, metallic aluminum was vapor-deposited on the LiF film at a deposition rate of 8.0 Å / s to form a metal cathode with a film thickness of 80 nm to obtain an organic EL element. Further, the voltage, external quantum efficiency, and half life were determined by the above methods. The results are shown in Table 2. The compounds used are shown below.

Examples 1-3
In Comparative Example 1, an organic EL device was prepared and evaluated in the same manner as Comparative Example 1 except that the light emitting layer was formed using the compounds shown in Table 1 instead of the compound (A1). The results are shown in Table 2. The “half life (relative value)” is a relative value when the half life of the device of Comparative Example 1 is 100.

Comparative Example 2
An organic EL device was produced in the same manner as in Comparative Example 1 except that the compound (H1) was used instead of the compound (A1) as the light emitting layer host and the compound (A1) was used instead of the compound (H1) as the hole blocking layer. ,evaluated. The results are shown in Table 3.

Examples 4-6
In Comparative Example 2, an organic EL device was produced in the same manner as in Comparative Example 2, except that the compound shown in Table 3 was used instead of the compound (A1) as the hole blocking layer. Table 3 shows the evaluation results of the obtained elements. The “half life (relative value)” is a relative value when the half life of the device of Comparative Example 2 is 100.

  From Tables 2 and 3, it can be seen that the compounds (1) to (4) of the present invention have a long life and can provide an organic EL device that is driven at a lower voltage and higher efficiency than the comparative compound.

  The compound of the present invention can be used as a material for an organic EL device. 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 (8)

The material for organic electroluminescent elements represented by following formula (1).

(In Formula (1), X is an oxygen atom or a sulfur atom.
One of G _{11 to} G ₁₈ is a carbon atom bonded to L ₁ , and the other G _{11 to} G ₁₈ are a nitrogen atom or CR ₀ , respectively.
R ₀ and R ₁ are each a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 18 ring carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an alkyl group having 3 to 20 ring carbon atoms. Cycloalkoxy group, aryloxy group having 6 to 18 ring carbon atoms, amino group, silyl group, fluoro group, cyano group, aryl group having 6 to 18 ring carbon atoms, or heteroaryl having 5 to 18 ring atoms Which may be substituted with the substituent R.
R ₂ is an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 18 ring carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkoxy group having 3 to 20 ring carbon atoms, and a ring formation, respectively. An aryloxy group having 6 to 18 carbon atoms, an amino group, a silyl group, a fluoro group, a cyano group, an aryl group having 6 to 18 ring carbon atoms, or a heteroaryl group having 5 to 18 ring atoms. The substituent R may be substituted.
L ₁ and L ₂ are each a single bond, a cycloalkylene group having 3 to 18 ring carbon atoms, an arylene group having 6 to 18 ring carbon atoms, or a heteroarylene group having 5 to 18 ring atoms, and these May be substituted with a substituent R.
R is an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 18 ring carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkoxy group having 3 to 20 ring carbon atoms, and a ring forming carbon, respectively. These are an aryloxy group having 6 to 18 amino acids, an amino group, a silyl group, a fluoro group, a cyano group, an aryl group having 6 to 18 ring carbon atoms, or a heteroaryl group having 5 to 18 ring atoms.
a and b are each an integer of 1 to 3, and n is an integer of 0 to 3. ) The material for organic electroluminescence elements according to claim 1, which is represented by the following formula (2).

(In the formula (2), X, G _{11 to} G ₁₈ , R, R ₀ , R ₁ , R ₂ , L ₁ , L ₂ , a, b and n are the same as those in the formula (1).) The organic electroluminescent element material according to claim 2 represented by the following formula (3).

(In the formula (3), X, G _{11 to} G ₁₈ , R, R ₀ , R ₁ , R ₂ , L ₁ , L ₂ , a, b and n are the same as those in the formula (1).)   It has one or more organic thin film layers containing a light emitting layer between a cathode and an anode, At least 1 layer of the said organic thin film layer is the organic electroluminescent element material in any one of Claims 1-3. An organic electroluminescence element to be contained.   The organic electroluminescent element according to claim 4, wherein at least one of the light emitting layer or the organic thin film layer between the cathode and the light emitting layer contains the material for an organic electroluminescent element.   The organic electroluminescence device according to claim 4, wherein the light emitting layer contains a host material and a phosphorescent material.   The organic electroluminescence device according to claim 6, wherein the phosphorescent material is a compound containing iridium (Ir) or platinum (Pt).   The organic electroluminescence device according to claim 7, wherein the compound containing iridium (Ir) or platinum (Pt) is an orthometalated metal complex.

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