JP2005068068A - Organic compound, charge transport material, organic electroluminescent element material, and organic electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compound having high solubility, high amorphous nature, proper charge mobility and electroluminescence; and to provide an organic electroluminescent element using the compound. <P>SOLUTION: The organic compound has b -NR<SP>1</SP>R<SP>2</SP>groups [b is an integer of 1-(a+2); and R<SP>1</SP>and R<SP>2</SP>are each independently an arbitrary substituent] on a base skeleton obtained by m-bonding (a) aromatic 6-membered rings [(a) is an integer of ≥3] regulated so that each -NR<SP>1</SP>R<SP>2</SP>group may be bonded to m-position in the aromatic 6-membered rings. The aromatic 6-membered ring may have a substituent except the -NR<SP>1</SP>R<SP>2</SP>groups, and the two or more aromatic 6-membered rings contained in one molecule may be the same or different rings. The two or more -NR<SP>1</SP>R<SP>2</SP>groups contained in one molecule may be the same or different groups. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a novel organic compound, and more particularly to an organic compound that has high heat resistance, excellent film forming properties, and is stable even when subjected to electrical oxidation or reduction.

  The electroluminescent element has features such as high visibility because it has self-luminous properties and excellent impact resistance because it is completely solid, and therefore, it has attracted attention as a light emitting element in various display devices. Among them, an organic electroluminescent element using an organic compound can significantly reduce the applied voltage, (1) is easy to downsize, (2) has low power consumption, and (3) surface emission. In addition, since (4) the light emission of the three primary colors is easy, research for practical application as a next-generation light-emitting element has been actively conducted.

  The organic electroluminescent elements reported so far basically emit light by a combination of a hole transport layer and an electron transport layer. In other words, holes injected from the anode move through the hole transport layer, recombine near the interface between the two layers, and electrons injected from the cathode and move through the electron transport layer. The principle is to emit light by exciting at least one of the transport layers.

  One of the major problems when applying such an organic electroluminescent element to the field of flat panel displays is to improve luminous efficiency. In particular, low power consumption is a point in application to display elements of portable devices. In application to small character display elements, the simple matrix driving method is mainly adopted. However, in this method, it is necessary to illuminate the element with a high duty ratio in a very short time, and therefore, the voltage is high. Thus, there is a problem that the power emission efficiency is lowered.

  Recently, as one of attempts to increase the light emission efficiency of an element, an element using phosphorescence has been studied in place of a conventional element using fluorescence. If phosphorescence is used, that is, light emission from a triplet excited state is used, an efficiency improvement of about three times is expected as compared with a conventional device using fluorescence (singlet). For this purpose, it has been studied to use a coumarin derivative or a benzophenone derivative as a light emitting layer (see Non-Patent Document 1), but only a very low luminance was obtained. Thereafter, the use of a europium complex has been studied as an attempt to utilize the triplet state, but this also did not lead to highly efficient light emission.

  Recently, it has been reported that highly efficient red light emission is possible by using the following platinum complex (T-1) (see Non-Patent Document 2). Then, the efficiency is greatly improved by further green light emission by doping the light emitting layer with the iridium complex (T-2) shown below (see Non-Patent Document 3).

有機電界発光素子をフラットパネル・ディスプレイ等の表示素子に応用するためには、素子の発光効率を改善すると同時に駆動時の安定性を十分に確保する必要がある。
しかしながら、前述の文献に記載の燐光分子（Ｔ−２）を用いた有機電界発光素子は、高効率発光ではあるが、駆動安定性が実用には不十分であり（非特許文献４参照）、高効率な表示素子の実現は困難な状況である。

In order to apply the organic electroluminescence device to a display device such as a flat panel display, it is necessary to improve the light emission efficiency of the device and at the same time to ensure sufficient stability during driving.
However, the organic electroluminescent element using the phosphorescent molecule (T-2) described in the above-mentioned document has high efficiency light emission, but has insufficient driving stability for practical use (see Non-Patent Document 4). Realization of a highly efficient display element is a difficult situation.

It is estimated that the main cause of the drive deterioration is due to deterioration of the light emitting layer.
The charge injected from the electrode becomes an electron-hole pair (exciton) with a certain probability. In general, light emission (phosphorescence) by triplet excitons has a longer lifetime than light emission (fluorescence) by singlet excitons. Conversely, thermal stability of singlet excitons is higher than that of triplet excitons. Is also expensive. Here, when the current applied to the element increases, the charge injected into the light emitting layer increases, and accordingly, the amount of charges that do not become excitons also increases. Further, among those that have become excitons, those that do not contribute to light emission in the light emitting layer and are thermally deactivated increase. For this reason, the temperature of the light emitting layer is increased, and in particular, triplet excitons are inferior in thermal stability to singlet excitons, so that the device is considered to deteriorate. This is also presumed from the fact that the luminous efficiency of the organic electroluminescent element using phosphorescent molecules (T-2) greatly decreases with the increase in injection current (see Non-Patent Document 3).

  Many of the organic electroluminescence devices using phosphorescent molecules developed so far are characterized by using a material containing a carbazolyl group as a host of the light emitting layer. For example, Non-Patent Document 3 uses the following biphenyl derivatives as host materials.

しかし、上記（Ｈ−１）は非常に結晶化しやすく、Ｔｇも低いため、膜の安定性が悪いことが知られている。また、素子としての発光効率も十分満足のいくものではなかった。
また、特許文献１には、ホスト材料として以下に示す化合物（Ｈ−２）が開示されている。

However, it is known that the above (H-1) is very easy to crystallize and Tg is low, so that the stability of the film is poor. Moreover, the luminous efficiency as an element was not fully satisfactory.
Patent Document 1 discloses a compound (H-2) shown below as a host material.

この化合物は、製膜性には優れているものの、耐熱性に重大な課題を有する。
上述の理由から、燐光分子を用いた有機電界発光素子においては、実用化に向けて素子の耐熱性、製膜性、発光効率の両立に大きな問題を抱えているのが実状である。
特表２００３−５１５８９７号公報 第51回応用物理学会連合講演会、28a-PB-7、1990年 Nature, 395巻，151頁，1998年 Appl. Phys. Lett., 75巻，4頁，1999 Jpn. J. Appl. Phys., 38巻，L1502頁，1999年

Although this compound is excellent in film forming property, it has a serious problem in heat resistance.
For the above-described reasons, organic electroluminescent devices using phosphorescent molecules have a serious problem in achieving compatibility between the heat resistance, film-forming property, and luminous efficiency of the device for practical use.
Special table 2003-515897 gazette The 51st Japan Society of Applied Physics, 28a-PB-7, 1990 Nature, 395, 151, 1998 Appl. Phys. Lett., 75, 4, pp. 1999 Jpn. J. Appl. Phys., 38, L1502, 1999

  As a result of intensive studies aimed at providing an organic electroluminescence device having high efficiency and high driving stability in view of the above situation, the present inventor solves the above problems by using a specific compound in the light emitting layer. I found that I can do it.

That is, the present invention provides b (b is an integer of 1 to (a + 2)) -NR on a basic skeleton in which a (6 is an integer of 3 or more) aromatic 6-membered rings are m-linked. ¹ R ² group (R ¹ and R ² each independently represents an arbitrary substituent), and each of the —NR ¹ R ² groups is m with respect to the m-linked site in the aromatic 6-membered ring. An organic compound characterized by being bonded to the -position (provided that the aromatic 6-membered ring may have a substituent in addition to the -NR ¹ R ² group, and a plurality of groups included in one molecule) The 6-membered aromatic rings may be the same or different from each other, and the plurality of —NR ¹ R ² groups contained in one molecule may be the same or different from each other. ), A charge transport material comprising the compound, an organic electroluminescent device material, and an organic electroluminescent device having a layer containing the compound.

  Depending on the compound, the glass transition temperature Tg tends to decrease due to the presence of the m-linked site, but the organic compound of the present invention secured a relatively high Tg by setting a ≧ 3. Further, when the molecular weight is increased to increase Tg, the band gap tends to be narrowed depending on the compound, and there is a possibility that the application is limited when used for an organic electroluminescence device or the like. However, since the compound of the present invention can ensure a wide band gap even if the molecular weight is high, the applicable range of application is wide.

Furthermore, since the compound of the present invention exhibits high amorphous properties, it can be said that it is an excellent material because it can be easily applied to various applications from the viewpoint of excellent film formability during thin film formation.

According to the light emitting layer of the organic electroluminescent element using the organic compound of the present invention, it is possible to emit light with high luminance and high efficiency at a low voltage, and further, the stability of the element is improved.
In addition, due to its excellent heat resistance, film-forming property, charge transportability, and light emission characteristics, it can be used in accordance with the layer structure of the device, light emitting material, hole injection material, hole transport material, electron injection material, electron transport material, hole It can also be applied as a blocking material, an electronic blocking material, or the like.

Therefore, the organic electroluminescent device according to the present invention is a flat panel display (for example, for OA computers and wall-mounted televisions), an in-vehicle display device, a light source utilizing characteristics of a mobile phone display or a surface light emitter (for example, a light source of a copying machine, It can be applied to liquid crystal displays and back light sources for instruments, display panels, and indicator lights, and its technical value is great.
In addition, since the organic compound of the present invention has essentially excellent redox stability, it is useful to use it for an electrophotographic photoreceptor.

The organic compound of the present invention comprises b (b is an integer of 1 to (a + 2)) on a basic skeleton in which a (a is an integer of 3 or more) aromatic 6-membered rings are m-linked. —NR ¹ R ² group (R ¹ and R ² are each independently an arbitrary substituent), and each of the —NR ¹ R ² groups is relative to the m-linked site in the aromatic 6-membered ring. , Substituted at the m-position.
However, the aromatic 6-membered ring may have a substituent other than the —NR ¹ R ² group, and the plurality of aromatic 6-membered rings contained in one molecule may be the same or different from each other. May be. In addition, a plurality of —NR ¹ R ² groups contained in one molecule may be the same as or different from each other. Hereinafter, the aromatic 6-membered ring in the organic compound of the present invention may be referred to as “ring A”.

  In the present invention, m-linkage means that when one ring A is bonded to other two or three rings A (four or more are not allowed in the present invention), the bonding positions of the rings A to each other Are in an m-position relationship to each other. That means

で表される結合位置から選ばれる２以上（分子の末端に位置する環では１カ所）で、他の環Ａと結合していることを表す。
環Ａに特に制限はなく、１分子中に含まれる複数の環Ａは、互いに同一であっても異なっていてもよい。以下に、環Ａとして好ましい例を示すが、これらに限定されるものではない。

2 or more selected from the bonding positions represented by (1 in the ring located at the end of the molecule), it represents that they are bonded to the other ring A.
There is no restriction | limiting in particular in the ring A, The several ring A contained in 1 molecule may mutually be same or different. Hereinafter, preferred examples of the ring A are shown, but the invention is not limited thereto.

上記環構造ではｍ−連結部位の記載を省略したが、前述した関係を満たす位置で、各々複数の環Ａが結合し、本発明の有機化合物を構成する。
環Ａとしては、前記例示したものの中でも、適度な酸化還元電位差を有する観点および電気的酸化還元に対する安定性の観点からＡ−１、Ａ−２およびＡ−３がより好ましく、Ａ−１およびＡ−２が更に好ましく、Ａ−１が最も好ましい。

In the above ring structure, the description of the m-linked site is omitted, but a plurality of rings A are bonded to each other at the position satisfying the above-described relationship to constitute the organic compound of the present invention.
As ring A, among those exemplified above, A-1, A-2 and A-3 are more preferable from the viewpoint of having an appropriate redox potential difference and stability against electrical redox, and A-1 and A -2 is more preferred, and A-1 is most preferred.

In the ring A, it is important that three or more of the same or different rings A are connected in a substantially straight line or branched form by m-connection. As a result, the [1,1 ';3', 1 ''] terphenyl unit maintains a reasonably wide oxidation-reduction potential difference and electrochemical stability, while having a high glass transition temperature and excellent film-forming properties. Large molecules can be constructed.
For example, if a [1,1 ′; 4 ′, 1 ″] terphenyl unit is present, the conjugated structure is excessively extended and the redox potential difference is significantly reduced.

In addition, the presence of [1,1 ';2', 1 ''] terphenyl unit completely divides the conjugated structure at that part, which increases the redox potential difference but decreases the electrochemical stability. To do.
In the organic compound of the present invention, specific examples are shown below as examples of the basic skeleton formed by m-linking of a ring A, but are not limited thereto.

In the above formula, R ^{101 to} R ¹¹⁶ represent positions to which —NR ¹ R ² group can be bonded, and in the case of the organic compound of the present invention, b per molecule selected from R ^{101 to} R ¹¹⁶ (however, , B is an integer of 1 or more and (a + 2) or less) is a —NR ¹ R ² group.

Among the basic skeletons exemplified above,
・ The film-forming property when a thin film is formed is particularly excellent.
・ Since it has excellent solubility, it is also suitable for wet film formation.
-By forming the molecular skeleton with as simple a unit as possible, when subjected to electrical oxidation or reduction, the phenomenon of localization of electrons and holes in the molecule, that is, electrical stress concentration is less likely to occur. Because of the fact that the durability against repeated electrochemical redox can be drastically improved, and that the benzene ring is made ring A, an appropriately wide redox potential difference can be given. 1-5,7,9,10,13-17,19,20 are more preferable, and AS-1-5,7 are still more preferable.

In the organic compound of the present invention, the —NR ¹ R ² group is a unit that mainly characterizes the electrical redox property of the compound, and the number in one molecule is b (where b is 1 or more and (a + 2) or less). Integer). Preferably, it is an integer of b ≧ (a / 2), more preferably an integer of b ≧ (2a / 3). Preferably, it is an integer satisfying b ≦ a.
The number of —NR ¹ R ² groups per ring A is preferably 1 or 0. When a ring A having ^two —NR ¹ R ² groups (three or more are not allowed in the present invention) is bonded, an electron or a hole is attached to that part (ring A and two —NR ¹ on ring A). (R ² group). Setting the number of —NR ¹ R ² groups per ring A to 1 or 0 is preferable because a compound having high durability and a large redox potential difference can be obtained.

It is important that the —NR ¹ R ² group is bonded to the m-position with respect to any of the m-linked sites in the ring A.
When the —NR ¹ R ² group is in the p-position with respect to the m-linkage site, the conjugated structure is excessively extended and the redox potential difference is significantly reduced. In addition, when the —NR ¹ R ² group is in the o-position with respect to the m-linkage site, the conjugated structure is completely divided at that portion, and the redox potential difference increases, but the electrochemical stability is increased. Decreases.

The aromatic 6-membered ring constituting the basic skeleton in the organic compound of the present invention may have an optional substituent other than the —NR ¹ R ² group as long as the performance of the compound is not impaired. Examples of the substituent include the same groups as those described as an optional substituent that the ring A ⁰ may have in the general formula (I) described later, and among these, a preferable group is also included in the ring A ^0. Same as in the ure group.
The molecular weight of the organic compound of the present invention is usually 4000 or less, preferably 3000 or less, more preferably 2000 or less. Moreover, it is 200 or more normally, Preferably it is 300 or more, More preferably, it is 400 or more. When the molecular weight exceeds the upper limit value, the sublimation property is lowered, and as described later, for example, there is a possibility of hindering the vapor deposition operation in the case of producing an organic electroluminescent element, and when the molecular weight is lower than the lower limit value, glass The transition point, melting point, mechanization temperature and the like are lowered, and the heat resistance when applied to various uses may be lowered.
The organic compound of the present invention is particularly preferably represented by the following general formula (I).

（式中、環Ａ⁰は−ＮＲ¹Ｒ²基以外にも置換基を有していてもよい芳香族６員環を表し、
Ｒ¹およびＲ²は任意の置換基を表し、ｎは１〜６の整数を表す。但し、１分子中に含まれる複数の環Ａ⁰、Ｒ¹およびＲ²は、各々同じものを表す。）
前記一般式（Ｉ）において、環Ａ⁰としては、環Ａとして前述したものと同様の構造が
挙げられ、好ましい構造も同様である。

(In the formula, ring A ⁰ represents an aromatic 6-membered ring optionally having a substituent other than the —NR ¹ R ² group,
R ¹ and R ² represent an arbitrary substituent, and n represents an integer of 1 to 6. However, the plurality of rings A ⁰ , R ¹ and R ² contained in one molecule each represent the same thing. )
In the general formula (I), examples of the ring A ⁰ include the same structures as those described above for the ring A, and preferred structures are also the same.

R ¹ and R ² represent an arbitrary substituent and may be the same or different from each other. To illustrate,
An alkyl group which may have a substituent (preferably a linear or branched alkyl group having 1 to 8 carbon atoms, such as methyl, ethyl, n-propyl, 2-propyl, n-butyl, isobutyl, tert -Butyl group, etc.)
An alkenyl group which may have a substituent (preferably an alkenyl group having 2 to 9 carbon atoms, such as vinyl, allyl, 1-butenyl and the like),
An alkynyl group which may have a substituent (preferably an alkynyl group having 2 to 9 carbon atoms, such as ethynyl and propargyl groups);
An aralkyl group which may have a substituent (preferably an aralkyl group having 7 to 15 carbon atoms, such as a benzyl group);
An acyl group which may have a substituent (preferably an acyl group having 2 to 10 carbon atoms which may have a substituent, for example, a formyl, acetyl, benzoyl group, etc.),
An alkoxycarbonyl group which may have a substituent (preferably an alkoxycarbonyl group having 2 to 10 carbon atoms which may have a substituent, including, for example, a methoxycarbonyl, ethoxycarbonyl group, etc.),
An aryloxycarbonyl group which may have a substituent (preferably an aryloxycarbonyl group having 7 to 13 carbon atoms which may have a substituent, such as a phenoxycarbonyl group);
An alkylcarbonyloxy group which may have a substituent (preferably an alkylcarbonyloxy group having 2 to 10 carbon atoms which may have a substituent, such as an acetoxy group);
Halogen atom (especially fluorine atom or chlorine atom)
Carboxyl group,
An aromatic hydrocarbon group which may have a substituent (for example, benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, fluoranthene ring, etc. A monovalent group derived from a 5- or 6-membered monocyclic ring or a 2-5 condensed ring is included)
Or an aromatic heterocyclic group which may have a substituent (for example, furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, Pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzoisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring , Pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, benzimidazole ring, perimidine ring, quinazoline ring, etc. Group is included) And the like.

Examples of the substituent that each of the above-described groups may have include an alkyl group having about 1 to 6 carbon atoms; an alkoxy group having about 1 to 6 carbon atoms; and an aryloxy group including an aromatic hydrocarbon group having about 6 to 10 carbon atoms. Group: alkylamino group having at least one alkyl group having about 1 to 6 carbon atoms: arylamino group having at least one aromatic hydrocarbon group having about 6 to 10 carbon atoms; aromatic having about 6 to 20 carbon atoms A hydrocarbon group; an alkylthio group having about 1 to 6 carbon atoms; an arylthio group having an aromatic hydrocarbon group having about 6 to 10 carbon atoms; an acyl group having about 2 to 20 carbon atoms.
R ¹ and R ² preferably have an aromatic hydrocarbon group which may have a substituent or a substituent from the viewpoint of charge transportability, electrochemical stability, heat resistance and the like. An aromatic heterocyclic group which may be substituted, and most preferably an aromatic hydrocarbon group which may have a substituent.

As specific examples of —NR ¹ R ^2, the following can be mentioned as preferable examples because the charge transportability and the electrical redox durability are improved, or a moderately wide redox potential difference is obtained.

（上記各構造中、Ｌ⁰は、水素原子あるいは、Ｒ¹およびＲ²が有しうる基として後述する
基に代表される、任意の置換基を表す。好ましくは、後述の基に代表される任意の置換基である。なお、Ｒ¹およびＲ²基は、Ｌ⁰以外にも後述する基に代表される任意の置換基を
有していても良い。）
中でも、より好ましくはＲ−１、Ｒ−２、Ｒ−３、およびＲ−８であり、Ｒ−１、Ｒ−３、およびＲ−８が更に好ましい。

(In the above structures, L ⁰ represents a hydrogen atom or an arbitrary substituent represented by a group described later as a group that R ¹ and R ² may have. Preferably, it is represented by a group described later. (The R ¹ and R ² groups may have an optional substituent represented by the group described later in addition to L ^0. )
Among these, R-1, R-2, R-3, and R-8 are more preferable, and R-1, R-3, and R-8 are more preferable.

On the other hand, in the organic compound of the present invention, R ¹ and R ² are bonded to each other from the viewpoint of improving the emission quantum efficiency by suppressing the non-radiative deactivation (thermal deactivation) of excitons due to unnecessary molecular motion. A compound forming a ring is preferred. The —NR ¹ R ² group (hereinafter referred to as “cyclic-NR ¹ R ² group”) in which R ¹ and R ² groups are bonded to each other to form a ring is not shared on the N atom contained in itself. It preferably has π electrons that can be conjugated with an electron pair, and the group as a whole is preferably an aromatic group (aromatic hydrocarbon group and aromatic heterocyclic group). Particularly preferred is an N-azolyl group.

Specific examples of more preferable cyclic -NR ¹ R ² groups are shown below, but the present invention is not limited thereto.

(In each of the above structures, L ¹ and L ² represent a hydrogen atom or an arbitrary substituent represented by a group described later as a group that the cyclic —NR ¹ R ² group may have. In addition to L ¹ and L ² , the cyclic —NR ¹ R ² group may have an optional substituent typified by a group described later. )
Among these, R-14, R-15, R-16, R-21, R-22, R-24, R-27, R-32, R-39, and R-40 are more preferable from the viewpoints described above. R-14, R-16, R-21, R-22, R-27, R-39 and R-40 are more preferred, R-14 and R-27 are more preferred, and R-27 is most preferred.

The cyclic —NR ¹ R ² group may have an arbitrary substituent, for example,
An alkyl group which may have a substituent (preferably a linear or branched alkyl group having 1 to 8 carbon atoms, such as methyl, ethyl, n-propyl, 2-propyl, n-butyl, isobutyl, tert -Butyl group, etc.)
An alkenyl group which may have a substituent (preferably an alkenyl group having 2 to 9 carbon atoms, such as vinyl, allyl, 1-butenyl and the like),
An alkynyl group which may have a substituent (preferably an alkynyl group having 2 to 9 carbon atoms, such as ethynyl and propargyl groups);
An aralkyl group which may have a substituent (preferably an aralkyl group having 7 to 15 carbon atoms, such as a benzyl group);
An amino group which may have a substituent [preferably, an alkylamino group having one or more alkyl groups having 1 to 8 carbon atoms which may have a substituent (for example, methylamino, dimethylamino, diethylamino, Dibenzylamino group, etc.),
An arylamino group having an aromatic hydrocarbon group having 6 to 12 carbon atoms which may have a substituent (for example, phenylamino, diphenylamino, ditolylamino group, etc.);
A heteroarylamino group having a 5- or 6-membered aromatic heterocyclic ring which may have a substituent (for example, pyridylamino, thienylamino, dithienylamino group, etc.);
An acylamino group having an acyl group having 2 to 10 carbon atoms which may have a substituent (for example, acetylamino, benzoylamino group and the like are included)],
An alkoxy group which may have a substituent (preferably an alkoxy group having 1 to 8 carbon atoms which may have a substituent, including methoxy, ethoxy, butoxy groups, etc.),
An aryloxy group which may have a substituent (preferably an aromatic hydrocarbon group having 6 to 12 carbon atoms, such as phenyloxy, 1-naphthyloxy, 2-naphthyloxy group, etc. ),
An optionally substituted heteroaryloxy group (preferably having a 5- or 6-membered aromatic heterocyclic group, including, for example, pyridyloxy, thienyloxy groups),
An acyl group which may have a substituent (preferably an acyl group having 2 to 10 carbon atoms which may have a substituent, for example, a formyl, acetyl, benzoyl group, etc.),
An alkoxycarbonyl group which may have a substituent (preferably an alkoxycarbonyl group having 2 to 10 carbon atoms which may have a substituent, including, for example, a methoxycarbonyl, ethoxycarbonyl group, etc.),
An aryloxycarbonyl group which may have a substituent (preferably an aryloxycarbonyl group having 7 to 13 carbon atoms which may have a substituent, such as a phenoxycarbonyl group);
An alkylcarbonyloxy group which may have a substituent (preferably an alkylcarbonyloxy group having 2 to 10 carbon atoms which may have a substituent, such as an acetoxy group);
Halogen atom (especially fluorine atom or chlorine atom)
Carboxyl group,
A cyano group,
Hydroxyl group,
Mercapto group,
An alkylthio group which may have a substituent (preferably an alkylthio group having 1 to 8 carbon atoms, including, for example, a methylthio group, an ethylthio group, etc.), and an arylthio which may have a substituent A group (preferably an arylthio group having 6 to 12 carbon atoms, including, for example, a phenylthio group, a 1-naphthylthio group, etc.),
A sulfonyl group which may have a substituent (for example, mesyl group, tosyl group and the like are included),
A silyl group which may have a substituent (for example, a trimethylsilyl group, a triphenylsilyl group, etc.),
An optionally substituted boryl group (for example, a dimesitylboryl group),
Phosphino group which may have a substituent (for example, diphenylphosphino group and the like are included),
An aromatic hydrocarbon group which may have a substituent (for example, benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, fluoranthene ring, etc. A monovalent group derived from a 5- or 6-membered monocyclic ring or a 2-5 condensed ring is included)
Or an aromatic heterocyclic group which may have a substituent (for example, furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, Pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzoisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring , Pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, benzimidazole ring, perimidine ring, quinazoline ring, etc. Group is included) And the like.

  Examples of the substituent that each group described above may have include at least one alkyl group having about 1 to 6 carbon atoms, an alkoxy group having about 1 to 6 carbon atoms, and an aromatic hydrocarbon group having about 6 to 10 carbon atoms. An aryloxy group having at least one alkyl chain having about 1 to 6 carbon atoms, an arylamino group having at least one aromatic hydrocarbon group having about 6 to 10 carbon atoms, and about 6 to 20 carbon atoms Aromatic hydrocarbon group, an alkylthio group having about 1 to 6 carbon atoms, an arylthio group having at least one aromatic hydrocarbon group having about 6 to 10 carbon atoms, an acyl group having about 2 to 20 carbon atoms, and the like. It is done.

From the viewpoint of limiting molecular vibrations in the compound, the cyclic —NR ¹ R ² group is unsubstituted, an alkyl group that may have a substituent, or an aromatic that may have a substituent. A case of having a hydrocarbon group (in particular, an aromatic hydrocarbon group having about 6 to 12 carbon atoms) is preferred, and a case of being unsubstituted or substituted by a methyl group or a phenyl group is particularly preferred.
Ring A may be substituted with a group different from the —NR ¹ R ² group. Examples of such a substituent include the same groups as those described above as the group that the cyclic —NR ¹ R ² group may have, and preferred groups are also the same. The bonding position of these arbitrary groups in ring A is not particularly limited, but is preferably the m-position with respect to the m-linkage site in the same manner as the —NR ¹ R ² group.

  The molecular weight of the compound represented by the general formula (I) is usually 4000 or less, preferably 3000 or less, more preferably 2000 or less. Moreover, it is 200 or more normally, Preferably it is 300 or more, More preferably, it is 400 or more. If the molecular weight exceeds the upper limit value, the sublimation property may be significantly reduced, which may hinder the vapor deposition operation when producing the electroluminescent device. If the molecular weight is lower than the lower limit value, the glass transition temperature, melting point, and vaporization may occur. Temperature etc. are too low and heat resistance may be insufficient.

  Although the preferable specific example of a compound represented with general formula (I) below is shown, this invention is not limited to these.

The organic compound of the present invention can be synthesized by a combination of known methods. Specifically, 1) a basic skeleton in which an aromatic 6-membered ring is m-linked is first formed, and then -NR ¹
A method of introducing an R ² group, and 2) using an aromatic 6-membered ring unit having an —NH ² group as a starting material, coupling an aromatic 6-membered ring unit having an —NR ¹ R ² group or an —NH 2 group A method is mentioned.

1) As a method of first forming a basic skeleton in which an aromatic 6-membered ring is m-linked, and then introducing a —NR ¹ R ² group, for example, the following methods (a) and (b) are: One that is suitable for the structure of the target compound may be employed.
(A) A small excess of halogenated aromatic boronic acid such as 3-fluorophenylboronic acid, 3,5-difluorophenylboronic acid, 3-fluoro-4-phenylphenylboronic acid (to the halogen atom of the halide described later) 1.1 to 1.5 times equivalent), 1,3-dibromo-5-fluorobenzene, 1,3-diiodobenzene, 1,3,5-tribromobenzene, trichlorotriazine, 3,3 Aromatic di- or tri-substituted halides such as' -diiodobiphenyl, palladium catalyst catalysts (about 1 to 5 mol%) such as tetrakis (triphenylphosphine) palladium, cesium carbonate, potassium phosphate, sodium carbonate, etc. In the presence of a base (about 1.5 to 5 times equivalent to the halogen atom of the halide), toluene-ethanol, toluene -Water, tetrahydrofuran, dioxane, dimethoxyethane, N, N-dimethylformamide, or the like, or a mixed solvent system thereof (the boronic acid concentration is about 1 to 100 mmol%) in an inert gas atmosphere for about 5 to 24 hours. By heating and refluxing, a basic skeleton having a fluorine atom as a substituent is formed.

  Next, an azole compound such as carbazole, indole, pyrrole, imidazole (about 1.1 to 10 equivalents relative to the fluorine atom on the basic skeleton having the fluorine atom as a substituent) is added in a dry gas atmosphere and / or insoluble. In an active gas atmosphere, in a solvent such as tetrahydrofuran, dioxane, ether, N, N-dimethylformamide and the like, a strong base such as sodium hydride, tert-butoxypotassium, n-butyllithium (described later) at a temperature range of −78 to + 60 ° C. The azole compound to be reacted is about 0.9 to 2 equivalents relative to hydrogen on N) and stirred for 0.1 to 5 hours.

The obtained compound is mixed with a solution of the above-obtained basic skeleton having a fluorine atom as a substituent, such as tetrahydrofuran, dioxane, ether, N, N-dimethylformamide and the like, and stirred for 1 to 60 hours while heating under reflux. By doing so, among the organic compounds of the present invention, an organic compound having an N-azolyl group as the —NR ¹ R ² group can be obtained.
(B) A small excess of halogenated aromatic boronic acid such as 3-bromophenylboronic acid, 3,5-dibromophenylboronic acid, 3,5-dichlorophenylboronic acid (1 relative to the halogen atom of the halide described later) .About.1-1.5 times equivalent), 1,3-diiodobenzene, 1-bromo-3,5-diiodobenzene, 1,3,5-triiodobenzene, trichlorotriazine, 3,3′- An aromatic di- or tri-substituted halide such as diiodobiphenyl and a palladium catalyst such as tetrakis (triphenylphosphine) palladium (about 0.01 to 1 equivalent to the halogen atom of the halide), cesium carbonate, In the presence of a base such as potassium phosphate or sodium carbonate (about 1.5 to 5 equivalents relative to the halogen atom of the halide), toluene, Ethanol, water, tetrahydrofuran, dioxane, dimethoxyethane, N, N-dimethylformamide, or the like, or a mixed solvent system thereof (having a halide concentration of about 1 to 100 mmol%) in an inert gas atmosphere for 5 to 24 hours By heating to reflux to the extent, a basic skeleton having a bromine atom and / or a chlorine atom as a substituent is formed.

Furthermore, if necessary, the basic skeleton having a bromine group is present in the presence of potassium iodide (1.5 to 10 equivalents relative to the bromine atom on the basic skeleton) and copper iodide (1 to 10 equivalents). Then, the bromine group is converted to an iodine group by stirring at 100 to 300 ° C. for 5 to 24 hours in a solvent such as N, N-dimethylformamide (the halide concentration is about 0.1 to 10 mol%). A basic skeleton can be obtained.
Next, a basic skeleton having a bromine atom or / and a chlorine atom as a substituent, diphenylamine, 1-naphthalenylphenylamine, 2-naphthalenylphenylamine, 9-phenanthrenylphenylamine, 9-phenanthrenyl- a diarylamine compound such as p-tolylamine (about 1.0 to 100 equivalents to the bromine atom and / or chlorine atom on the basic skeleton having the bromine atom or / and chlorine atom as a substituent), ) Or (ii), the organic compound of the present invention can be obtained.

  (I) Copper catalyst such as copper powder, copper wire, copper halide (CuX (X = Cl, Br, I)), copper oxide (CuO) (basic skeleton having the bromine atom and / or chlorine atom as a substituent) In the presence of about 1 to 5 equivalents with respect to the bromine atom and / or chlorine atom), in the presence of an inert gas stream, no solvent or a solvent such as tetraglyme or polyethylene glycol (0.1 mol with respect to 1 mol of the basic skeleton). In the temperature range of 20 to 300 ° C., the mixture is stirred and mixed for 1 to 60 hours.

(Ii) a divalent palladium catalyst such as Pd ₂ (dba) ₃ (Pd = palladium, dba = dibenzylideneacetone), Pd (dba) ₂ , palladium acetate, and BINAP (= 2,2′-bis (diphenylphosphine) Fino-1,1'-binaphthyl), tri (tert-butyl) phosphine, triphenylphosphine, 1,2-bis (diphenylphosphino) ethane, 1,3-bis (diphenylphosphino) propane, 1,3 A combination of ligands such as bis (diphenylphosphino) butane and dppf (= 1,1′-bis (diphenylphosphino) ferrocene), a zero-valent palladium complex such as Pd (PPh) ₄ , or PdCl ₂ ( dppf) such as palladium chloride complex such as ₂ catalyst (usually Yusuke substituent the bromine atom or / and chlorine atoms About 0.01-1 equivalent to 1 equivalent of bromine atom and / or chlorine atom on the basic skeleton) and strong bases such as tert-butoxy potassium, tert-butoxy sodium, potassium carbonate, triethylamine as necessary ( Usually, in the presence of 1.1 to 10 equivalents to 1 equivalent of hydrogen halide that can be produced by the reaction, a copper catalyst such as copper iodide (usually 1 equivalent of hydrogen halide that can be produced by the reaction), if necessary. 1 to 10 equivalents) in the presence of a solvent such as tetrahydrofuran, dioxane, dimethoxyethane, N, N-dimethylformamide, dimethyl sulfoxide, xylene, toluene, triethylamine (usually replacing the bromine atom or / and chlorine atom). The concentration of the basic skeleton in the base is about 0.1 to 100 mmol%), and the mixture is stirred at 30 to 200 ° C. for 1 to 60 hours. That.

2) Starting from an aromatic 6-membered ring unit having —NH ₂ group, —NR ¹ R ² group or —N
As a method for coupling an aromatic 6-membered ring unit having an H ₂ group, for example,
First, a small excess of aminoarylboronic acids such as 3-aminophenylboronic acid (about 1.1 to 1.5 times equivalent to the halogen atom of the halide described later), 1,3-diiodobenzene, Aromatic di- or tri-substituted halides such as 1-amino-3,5-diiodobenzene, 1,3,5-triiodobenzene, trichlorotriazine, 3,3′-diiodobiphenyl and tetrakis (triphenyl Phosphine) Palladium catalyst such as palladium (about 0.01 to 1 equivalent to the halogen atom of the halide), base such as cesium carbonate, potassium phosphate, sodium carbonate (1 to the halogen atom of the halide). In the presence of toluene, ethanol, water, tetrahydrofuran, dioxane, dimethoxyethane, N , N-dimethylformamide or the like, or a mixed solvent system thereof (having a halide concentration of about 1 to 100 mmol%), and heating to reflux in an inert gas atmosphere for about 5 to 24 hours to replace the amino group The basic skeleton of the group is formed.

This is reacted with an aryl halide such as aryl iodide or aryl bromide under the same conditions as in the reaction of arylamine and aryl halide described above (in this case, however, aryl halide is used in excess). Can be synthesized.
In addition to those described in the above 1) and 2), known methods such as a Grignard reaction, a method using zinc, a method using tin, and the like can be applied to coupling of aromatic 6-membered rings, For the introduction of the amino group, the method described in the section of “4th edition Experimental Chemistry Course 20” (edited by the Chemical Society of Japan, Maruzen), Chapter 6 (Amine) can be applied.

Since the organic compound of the present invention has an appropriate charge transport property, it can be suitably used as an electrophotographic photosensitive member, an organic electroluminescent device, a photoelectric conversion device, an organic solar cell, an organic rectifying device and the like as a charge transport material.
In addition, since it is difficult to crystallize and has a high glass transition temperature, it has excellent thin film formability. Therefore, it is possible to provide an organic electroluminescent device that has excellent heat resistance and can be stably driven (emitted) for a long period of time. Suitable as a material.

Then, the organic electroluminescent element using the compound of this invention is demonstrated.
The organic electroluminescent element of the present invention has an anode, a cathode, and a light emitting layer provided between the two electrodes, and the present invention as the light emitting layer or as a layer between the light emitting layer and the anode or cathode. It is characterized by having a layer containing the organic compound.
When the organic compound of the present invention is contained in a hole transporting layer provided between the light emitting layer and the anode, it is desirable to have a moderately low oxidation potential and a moderately high reduction potential. In particular, since it is necessary to be stable even in repeated electrical oxidation, those in which R ¹ and R ² in the —NR ¹ R ² group are not linked (for example, a diarylamino group) are desirable. More preferable examples include R-1, R-2, R-3, and R-8 among the structures listed above as specific examples, and R-1, R-2, and R-8 are more preferable.

In addition, when contained in an electron transporting layer provided between the light emitting layer and the cathode, it is desirable to have a moderately high oxidation potential and a moderately low reduction potential, especially for repeated electrical reduction. Need to be stable. Thus, R ¹ and R ² in the -NR ¹ R ² groups, cyclic -NR ¹ R ² group is desirable comprising linked directly or through a linking group, it contains many among them N atoms or fused ring group structure in It is more preferable that Preferable examples include, for example, R-14, R-15, R-20, R-21, R-24, R-25, R-26, R-27, R-28 among the structures listed above as specific examples. , R-29, R-30, R-31, R-32, R-33, R-34, R-35, R-36, R-37, R-40, R-41, R-42, R -43, R-44, R-45, R-46, etc., and R-14, R-15, R-20, R-21, R-24, R-27, R-28, R-32 , R-34, and R-40 are more preferable.

Furthermore, when it is contained in the light-emitting layer, particularly as a host material, it is desirable to have a moderately high oxidation potential and a moderately high reduction potential. Sex is necessary. Thus, R ¹ and R ² in the -NR ¹ R ² groups, cyclic -NR ¹ R ² group is desirable comprising linked directly or through a linking group, further comprises an aromatic heterocyclic fused ring group More preferable is a structure containing a moderate amount of. Preferable examples include, for example, R-14, R-15, R-16, R-21, R-22, R-24, R-27, R-32, R-39 among the structures listed above as specific examples. , R-40 and the like, R-14, R-16, R-21, R-22, R-27, R-39 and R-40 are more preferable, and R-14 and R-27 are more preferable. R-27 is most preferred.

In the present invention, the organic compound of the present invention has a large number of —NR ¹ R ² groups, is excellent in hole transportability, and has a wide oxidation-reduction potential difference. When used as a host material, it is preferable because its advantages are most utilized.
In the organic electroluminescent element of the present invention, two or more organic compounds of the present invention may be contained in the same layer. When the organic compound of the present invention is contained in two or more layers, the compounds contained in these layers may be the same or different.

In the organic electroluminescence device of the present invention, the cathode-light emitting layer is referred to as an “electron transport layer”,
In the case of two or more, the layer in contact with the cathode is referred to as an “electron injection layer”, and the other layers are collectively referred to as an “electron transport layer”. Of the layers provided between the cathode and the light emitting layer, the layer in contact with the light emitting layer may be particularly referred to as a “hole blocking layer”.
Embodiments of an organic electroluminescent device of the present invention will be described below in detail with reference to the accompanying drawings, taking as an example the case where the organic compound of the present invention is contained in a light emitting layer.

FIG. 1 is a cross-sectional view schematically showing a structural example of a general organic electroluminescence device used in the present invention. 1 is a substrate, 2 is an anode, 4 is a hole transport layer, 5 is a light emitting layer, and 6 is a light emitting layer. A hole blocking layer, 8 represents a cathode.
The substrate 1 serves as a support for the organic electroluminescent element, and a quartz or glass plate, a metal plate or a metal foil, a plastic film, a sheet, or the like is used. In particular, a glass plate, a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, polysulfone, or a film is preferable. When using a synthetic resin substrate, it is necessary to pay attention to gas barrier properties. If the gas barrier property of the substrate is too small, the organic electroluminescent element may be deteriorated by the outside air that has passed through the substrate, which is not preferable. For this reason, a method of providing a gas barrier property by providing a dense silicon oxide film or the like on at least one surface of the synthetic resin substrate is also a preferable method.

  An anode 2 is provided on the substrate 1, and the anode 2 plays a role of hole injection into the hole transport layer 4. The anode 2 is usually made of metal such as aluminum, gold, silver, nickel, palladium, platinum, metal oxide such as oxide of indium and / or tin, metal halide such as copper iodide, carbon black, or poly It is composed of conductive polymers such as (3-methylthiophene), polypyrrole, and polyaniline. In general, the anode 2 is often formed by a sputtering method, a vacuum deposition method, or the like. Further, when the anode 2 is formed of metal fine particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, and conductive polymer fine powder, It can also be formed by dispersing and coating on the substrate 1. Further, when the anode 2 is formed of a conductive polymer, a polymerized thin film can be directly formed on the substrate 1 by electrolytic polymerization, or a conductive polymer can be applied to the substrate 1 (Appl). Phys. Lett., 60, 2711, 1992).

The anode 2 usually has a single-layer structure, but it can also have a laminated structure made of a plurality of materials if desired.
The thickness of the anode 2 varies depending on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably about 500 nm or less. When it may be opaque, the thickness of the anode 2 is arbitrary, and if desired, it may be formed of metal to serve as the substrate 1.

  In the element having the configuration shown in FIG. 1, a hole transport layer 4 is provided on the anode 2. As conditions required for the material of the hole transport layer, it is necessary that the material has a high hole injection efficiency from the anode and can efficiently transport the injected holes. For this purpose, the ionization potential is small, the transparency to visible light is high, the hole mobility is high, the stability is high, and impurities that become traps are less likely to be generated during manufacturing and use. Required. Further, in order to contact the light emitting layer 5, it is required not to quench the light emitted from the light emitting layer or to form an exciplex with the light emitting layer to reduce the efficiency. In addition to the above general requirements, when the application for in-vehicle display is considered, the element is further required to have heat resistance. Therefore, a material having a Tg value of 85 ° C. or higher is desirable.

As such a hole transport material, for example, 4,4′-bis [N- (1-naphthyl)-
N-phenylamino] aromatic diamine containing two or more tertiary amines typified by biphenyl and having two or more condensed aromatic rings substituted with nitrogen atoms (Japanese Patent Laid-Open No. 5-234811), 4,4 ′ , 4'-tris (1-naphthylphenylamino) triphenylamine and other aromatic amine compounds having a starburst structure (J. Lumin., 72-74, 985, 1997), tetraphenylamine tetramer Aromatic amine compounds (Chem. Commun., 2175, 1996), spiro compounds such as 2,2 ′, 7,7′-tetrakis- (diphenylamino) -9,9′-spirobifluorene ( Synth.
Metals, 91, 209, 1997). These compounds may be used alone or in combination as necessary.

In addition to the above compounds, polyarylene ether sulfone (Polym. Adv. Tech.) Containing polyvinyl carbazole, polyvinyl triphenylamine (Japanese Patent Laid-Open No. 7-53953), and tetraphenylbenzidine as the material of the hole transport layer 4 is used. , 7, p. 33, 1996).
The hole transport layer 4 may be formed by a normal coating method such as a spray method, a printing method, a spin coating method, a dip coating method, or a die coating method, a wet film forming method such as various printing methods such as an ink jet method or a screen printing method, or a vacuum. It can be formed by a dry film formation method such as a vapor deposition method.

  In the case of the coating method, one or more hole transport materials are added, and if necessary, additives such as binder resins and coating property improving agents that do not trap holes are added and dissolved in a suitable solvent. A solution is prepared, applied onto the anode 2 by a method such as spin coating, and dried to form the hole transport layer 4. Examples of the binder resin include polycarbonate, polyarylate, and polyester. When the binder resin is added in a large amount, the hole mobility is lowered. Therefore, it is desirable that the binder resin be less, and usually 50% by weight or less is preferable.

In the case of the vacuum evaporation method, the hole transport material is put in a crucible installed in a vacuum vessel, the inside of the vacuum vessel is evacuated to about 10 ⁻⁴ Pa with a suitable vacuum pump, and then the crucible is heated, The hole transport material is evaporated and a hole transport layer 4 is formed on the substrate 1 on which the anode 2 is formed, which is placed facing the crucible.
The thickness of the hole transport layer 4 is usually 5 nm or more, preferably 10 nm or more, and is usually 300 nm or less, preferably 100 nm or less. In order to uniformly form such a thin film, a vacuum deposition method is generally used.

In the element shown in FIG. 1, a light emitting layer 5 is provided on the hole transport layer 4. The light emitting layer 5 is excited by recombination of holes injected from the anode and moving through the hole transport layer and electrons injected from the cathode and moved through the hole blocking layer 6 between the electrodes to which an electric field is applied. And formed from a compound that exhibits strong luminescence.
The compound used for the light emitting layer 5 is a compound that has a stable thin film shape, exhibits a high emission (fluorescence or phosphorescence) quantum yield in a solid state, and can efficiently transport holes and / or electrons. It is necessary to be. Further, it is required to be a compound that is electrochemically and chemically stable and does not easily generate impurities as traps during production or use.

Since the organic compound of the present invention satisfies such a condition, it is preferably used as a light emitting layer material in an organic electroluminescent element. The light emitting layer 5 may be a layer made of only the compound, but is preferably a layer containing a light emitting material (dopant) for various purposes described below.
For the purpose of improving the light emission efficiency of the device and changing the emission color, for example, doping a fluorescent dye for laser such as coumarin with an aluminum complex of 8-hydroxyquinoline as a host material (J. Appl. Phys., Volume 65). , 3610, 1989) and the like, and it is preferable to dope a fluorescent dye also to the light emitting layer in the organic electroluminescent device of the present invention.

  As a doping material, various fluorescent dyes can be used in addition to coumarin. Examples of fluorescent dyes that emit blue light include perylene, pyrene, anthracene, coumarin, and derivatives thereof. Examples of the green fluorescent dye include quinacridone derivatives and coumarin derivatives. Examples of yellow fluorescent dyes include rubrene and perimidone derivatives. Examples of red fluorescent dyes include DCM compounds, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, azabenzothioxanthene and the like.

Other than the above-mentioned fluorescent dyes for doping, depending on the host material, listed in Laser Research, 8, 694, 803, 958 (1980); 9, 9, 85 (1981). Fluorescent dyes and the like that can be used as a doping material for the light emitting layer.
The amount of the fluorescent dye doped with respect to the host material is preferably 10 ⁻³ wt% or more, and more preferably 0.1 wt%. Moreover, 10 weight% or less is preferable and 3 weight% or less is more preferable. If the lower limit is not reached, it may not be possible to contribute to improving the luminous efficiency of the device. If the upper limit is exceeded, concentration quenching may occur, leading to a reduction in luminous efficiency.

  On the other hand, a light-emitting layer that emits phosphorescence is usually formed including a phosphorescent dopant and a host material. Examples of the phosphorescent dopant include organometallic complexes containing a metal selected from Groups 7 to 11 of the periodic table, and charge transporting organic compounds having a T1 higher than the T1 (lowest excited triplet level) of the metal complex. It is preferable to use it as a host material. The organic compound of the present invention can also be suitably used as a host material in the light emitting layer that exhibits phosphorescence.

  Preferred examples of the metal in the phosphorescent organometallic complex containing a metal selected from Groups 7 to 11 of the periodic table include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold. As these organometallic complexes, compounds represented by the following general formula (i) or general formula (ii) are preferable.

（式中、Ｍは金属、ｎは該金属の価数を表す。ＬおよびＬ’は二座配位子を表す。ｊは０または１または２を表す。）

(In the formula, M represents a metal, n represents a valence of the metal, L and L ′ represent a bidentate ligand, and j represents 0, 1 or 2.)

（式中、Ｍ⁷は金属、Ｔは炭素または窒素を表わす。Ｔが窒素の場合はＲ¹⁴、Ｒ¹⁵は無く
、Ｔが炭素の場合はＲ¹⁴、Ｒ¹⁵は水素原子、ハロゲン原子、アルキル基、アラルキル基、アルケニル基、シアノ基、アミノ基、アシル基、アルコキシカルボニル基、カルボキシル基、アルコキシ基、アルキルアミノ基、アラルキルアミノ基、ハロアルキル基、水酸基、アリールオキシ基、置換基を有していてもよい芳香族炭化水素基または芳香族複素環基を表わす。

(Wherein M ⁷ represents a metal, T represents carbon or nitrogen. When T is nitrogen, there is no R ¹⁴ or R ¹⁵ , and when T is carbon, R ¹⁴ or R ¹⁵ represents a hydrogen atom, a halogen atom, or an alkyl. Group, aralkyl group, alkenyl group, cyano group, amino group, acyl group, alkoxycarbonyl group, carboxyl group, alkoxy group, alkylamino group, aralkylamino group, haloalkyl group, hydroxyl group, aryloxy group, substituent Represents an aromatic hydrocarbon group or an aromatic heterocyclic group.

R ¹² and R ¹³ are hydrogen atom, halogen atom, alkyl group, aralkyl group, alkenyl group, cyano group, amino group, acyl group, alkoxycarbonyl group, carboxyl group, alkoxy group, alkylamino group, aralkylamino group, haloalkyl group , A hydroxyl group, an aryloxy group, an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent, and may be linked to each other to form a ring. )
In the general formula (i), the bidentate ligands L and L ′ each represent a ligand having the following partial structure.

（環Ａ¹および環Ａ¹’は各々独立に、芳香族炭化水素基または芳香族複素環基を表わし、置換基を有していてもよい。環Ａ²および環Ａ²’は含窒素芳香族複素環基を表わし、置換基を有していてもよい。Ｒ’、Ｒ’’およびＲ’’’はそれぞれハロゲン原子；アルキル基；アルケニル基；アルコキシカルボニル基；メトキシ基；アルコキシ基；アリールオキシ基；ジアルキルアミノ基；ジアリールアミノ基；カルバゾリル基；アシル基；ハロアルキル基またはシアノ基を表す。）
一般式（ｉ）で表される化合物として、さらに好ましくは下記一般式（ｉａ）、（ｉｂ）（ｉｃ）で表される化合物が挙げられる。

(Ring A ¹ and Ring A ¹ ′ each independently represent an aromatic hydrocarbon group or an aromatic heterocyclic group, which may have a substituent. Ring A ² and Ring A ² ′ are nitrogen-containing aromatics. Represents a heterocyclic group, and may have a substituent, R ′, R ″ and R ′ ″ each represent a halogen atom; an alkyl group; an alkenyl group; an alkoxycarbonyl group; a methoxy group; an alkoxy group; An oxy group; a dialkylamino group; a diarylamino group; a carbazolyl group; an acyl group; a haloalkyl group or a cyano group.)
More preferred examples of the compound represented by the general formula (i) include compounds represented by the following general formulas (ia), (ib) (ic).

（式中、Ｍ⁴は金属、ｎは該金属の価数を表す。環Ａ¹は置換基を有していてもよい芳香族炭化水素基を表わし、環Ａ²は置換基を有していてもよい含窒素芳香族複素環基を表わ
す。）

(In the formula, M ⁴ represents a metal, n represents a valence of the metal, ring A ¹ represents an aromatic hydrocarbon group which may have a substituent, and ring A ² has a substituent. Represents a nitrogen-containing aromatic heterocyclic group which may be

（式中、Ｍ⁵は金属、ｎは該金属の価数を表す。環Ａ¹は置換基を有していてもよい芳香族炭化水素基または芳香族複素環基を表わし、環Ａ²は置換基を有していてもよい含窒素
芳香族複素環基を表わす。）

(In the formula, M ⁵ represents a metal, and n represents a valence of the metal. Ring A ¹ represents an optionally substituted aromatic hydrocarbon group or aromatic heterocyclic group, and ring A ² represents (It represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.)

（式中、Ｍ⁶は金属、ｎは該金属の価数を表し、ｊは０または１または２を表す。環Ａお
よび環Ａ¹’は各々独立に、置換基を有していてもよい芳香族炭化水素基または芳香族複
素環基を表わし、環Ａ²および環Ａ²’は各々独立に、置換基を有していてもよい含窒素芳香族複素環基を表わす。）
一般式（ｉａ）、（ｉｂ）、（ｉｃ）で表される化合物の環Ａ１および環Ａ１として、好ましくは、フェニル基、ビフェニル基、ナフチル基、アントリル基、チエニル基、フリル基、ベンゾチエニル基、ベンゾフリル基、ピリジル基、キノリル基、イソキノリル基、またはカルバゾリル基が挙げられる。

(In the formula, M ⁶ represents a metal, n represents a valence of the metal, and j represents 0, 1 or 2. Ring A and ring A ¹ ′ may each independently have a substituent. Represents an aromatic hydrocarbon group or an aromatic heterocyclic group, and ring A ² and ring A ² ′ each independently represent a nitrogen-containing aromatic heterocyclic group which may have a substituent.
As the ring A1 and ring A1 of the compounds represented by the general formulas (ia), (ib), and (ic), a phenyl group, a biphenyl group, a naphthyl group, an anthryl group, a thienyl group, a furyl group, a benzothienyl group are preferable. Benzofuryl group, pyridyl group, quinolyl group, isoquinolyl group, or carbazolyl group.

As ring A ² and ring A ² ′, a pyridyl group, pyrimidyl group, pyrazyl group, triazyl group, benzothiazole group, benzoxazole group, benzimidazole group, quinolyl group, isoquinolyl group, quinoxalyl group, or phenanthridyl Groups.
Examples of the substituent that the compounds represented by the general formulas (ia), (ib) and (ic) may have include a halogen atom such as a fluorine atom; a C 1-6 carbon atom such as a methyl group and an ethyl group An alkyl group; an alkenyl group having 2 to 6 carbon atoms such as a vinyl group; an alkoxycarbonyl group having 2 to 6 carbon atoms such as a methoxycarbonyl group and an ethoxycarbonyl group; an alkoxy group having 1 to 6 carbon atoms such as a methoxy group and an ethoxy group; An aryloxy group such as a phenoxy group and a benzyloxy group; a dialkylamino group such as a dimethylamino group and a diethylamino group; a diarylamino group such as a diphenylamino group; a carbazolyl group; an acyl group such as an acetyl group; A haloalkyl group; a cyano group, and the like, which may be linked to each other to form a ring.

In addition, the substituent of ring A ¹ and the substituent of ring A ² are bonded, or the substituent of ring A ¹ ′ and the substituent of ring A ² ′ are bonded to form one condensed ring. As such a condensed ring, a 7,8-benzoquinoline group and the like can be mentioned.
As the substituent for ring A ¹ , ring A ¹ ′, ring A ^2, and ring A ² ′, an alkyl group, an alkoxy group, an aromatic hydrocarbon group, a cyano group, a halogen atom, a haloalkyl group, a diarylamino group, Or a carbazolyl group is mentioned.

M ⁴ to M ⁵ in the formulas (ia) and (ib) are preferably ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum or gold.
M ⁷ in formula (ii) is preferably ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum or gold, and particularly preferably a divalent metal such as platinum or palladium.

Specific examples of the organometallic complexes represented by the general formulas (i), (ia), (ib) and (ic) are shown below, but are not limited to the following compounds.

前記一般式（ii）で表わされる有機金属錯体の具体例を以下に示すが、下記の化合物に限定されるわけではない。なお、式中のＭｅはメチル基、Ｅｔはエチル基を表す。

Specific examples of the organometallic complex represented by the general formula (ii) are shown below, but are not limited to the following compounds. In the formula, Me represents a methyl group, and Et represents an ethyl group.

さらに、本発明の有機化合物を含む発光層は、燐光性ドーパントと共に、前述の蛍光色素をも含有していてもよい。
発光層中にドーパントとして含有される有機金属錯体の量は、０．１重量％以上が好ましく、また３０重量％以下が好ましい。下限値を下回ると素子の発光効率向上に寄与できない場合があり、上限値を上回ると有機金属錯体同士が２量体を形成する等の理由で濃度消光が起き、発光効率の低下に至る可能性がある。

Furthermore, the light emitting layer containing the organic compound of the present invention may also contain the aforementioned fluorescent dye together with the phosphorescent dopant.
The amount of the organometallic complex contained as a dopant in the light emitting layer is preferably 0.1% by weight or more, and more preferably 30% by weight or less. If the lower limit is not reached, it may not be possible to contribute to improving the luminous efficiency of the device. If the upper limit is exceeded, concentration quenching may occur due to the formation of a dimer between organometallic complexes, etc. There is.

  The amount of the phosphorescent dopant in the light emitting layer exhibiting phosphorescence tends to be preferably slightly larger than the amount of the fluorescent dye (dopant) contained in the light emitting layer in a conventional device using fluorescence (singlet). There is. When the fluorescent dye is contained in the light emitting layer together with the phosphorescent dopant, the amount of the fluorescent dye is preferably 0.05% by weight or more, and more preferably 0.1% by weight or more. Moreover, 10 weight% or less is preferable and 3 weight% or less is more preferable.

The thickness of the light emitting layer 5 is usually 3 nm or more, preferably 5 nm or more, and is usually 200 nm or less, preferably 100 nm or less.
In addition, the light emitting layer 5 may contain components other than the above in the range which does not impair the performance of this invention.
For example, a metal complex such as an aluminum complex of 8-hydroxyquinoline (JP 59-194393 A), a metal complex of 10-hydroxybenzo [h] quinoline (JP 6-322362 A), a bisstyrylbenzene derivative ( JP-A-1-245087 and JP-A-2-222484), bisstyrylarylene derivatives (JP-A-2-247278), metal complexes of (2-hydroxyphenyl) benzothiazole (JP-A-8-315983) , A light emitting layer material that emits fluorescence such as silole derivatives, carbazole derivatives such as 4,4′-N, N′-dicarbazolebiphenyl (WO 00/70655), tris (8-hydroxyquinoline) aluminum (USP) 6,303,238), 2,2 ′, 2 ″-(1,3,5- Luminescent layer that generates phosphorescence such as benzenetolyl) tris [1-phenyl-1H-benzimidazole] (Appl. Phys. Lett., 78, 1622, 2001), polyvinylcarbazole (Japanese Patent Laid-Open No. 2001-257076), etc. It may contain materials.

The light emitting layer can also be formed by the same method as the hole transport layer. A method for doping the above-described fluorescent dye and / or phosphorescent dye (phosphorescent dopant) into the host material of the light emitting layer will be described below.
In the case of coating, the above light emitting layer host material, dope dye, and if necessary, additives such as a binder resin that does not become an electron trap or a light quenching quencher, and a coating property improving agent such as a leveling agent are added and dissolved. The applied coating solution is prepared, applied onto the hole transport layer 4 by a method such as spin coating, and dried to form the light emitting layer 5. Examples of the binder resin include polycarbonate, polyarylate, and polyester. When the amount of the binder resin added is large, the hole / electron mobility is lowered. Therefore, the smaller amount is desirable, and 50% by weight or less is preferable.

In the case of the vacuum deposition method, the host material is put in a crucible installed in a vacuum vessel, the dye to be doped is put in another crucible, and the inside of the vacuum vessel is 1.0 × 10 ⁻⁴ Torr with an appropriate vacuum pump. After evacuating to a degree, each crucible is heated and evaporated simultaneously to form a layer on the substrate placed opposite the crucible. As another method, a mixture of the above materials in a predetermined ratio may be evaporated using the same crucible.

When each said dopant is doped in a light emitting layer, although doped uniformly in the film thickness direction of a light emitting layer, there may exist concentration distribution in a film thickness direction. For example, it may be doped only in the vicinity of the interface with the hole transport layer, or conversely, it may be doped in the vicinity of the interface of the hole blocking layer.
The light emitting layer can also be formed by the same method as the hole transport layer, but usually a vacuum deposition method is used.

In the element shown in FIG. 1, the hole blocking layer 6 is laminated on the light emitting layer 5 so as to be in contact with the cathode side interface of the light emitting layer 5.
The hole blocking layer has a role of blocking the holes moving from the hole transport layer from reaching the cathode, and a compound that can efficiently transport the electrons injected from the cathode toward the light emitting layer. Preferably it is formed. The physical properties required for the material constituting the hole blocking layer are required to have high electron mobility and low hole mobility. The hole blocking layer 6 has a function of confining holes and electrons in the light emitting layer and improving luminous efficiency.

  The ionization potential of the hole blocking layer used in the present invention is preferably 0.1 eV or more larger than the ionization potential of the light emitting layer (or the ionization potential of the host material when the light emitting layer contains a host material and a dopant). The ionization potential is defined by the energy required to emit electrons at the HOMO (highest occupied molecular orbital) level of the material to the vacuum level. The ionization potential can be defined directly by photoelectron spectroscopy or can be determined by correcting the electrochemically measured oxidation potential relative to the reference electrode. In the case of the latter method, for example, when a saturated sweet potato electrode (SCE) is used as a reference electrode,

で定義される。（“Ｍｏｌｅｃｕｌａｒ Ｓｅｍｉｃｏｎｄｕｃｔｏｒｓ”，Ｓｐｒｉｎｇｅｒ−Ｖｅｒｌａｇ，１９８５年、９８頁）。
さらに、本発明で用いられる正孔阻止層の電子親和力（ＥＡ）は、発光層の電子親和力（発光層がホスト材料とドーパントを含んでいる場合にはホスト材料の電子親和力）と比較して同等以上であることが好ましい。電子親和力もイオン化ポテンシャルと同様に真空準位を基準として、真空準位にある電子が物質のＬＵＭＯ（最低空分子軌道）レベルに落ちて安定化するエネルギーで定義される。電子親和力は、上述のイオン化ポテンシャルから光学的バンドギャップを差し引いて求められるか、電気化学的な還元電位から下記の式で同様に求められる。

Defined by ("Molecular Semiconductors", Springer-Verlag, 1985, page 98).
Furthermore, the electron affinity (EA) of the hole blocking layer used in the present invention is equivalent to the electron affinity of the light emitting layer (when the light emitting layer contains a host material and a dopant, the electron affinity of the host material). The above is preferable. Similar to the ionization potential, the electron affinity is also defined by the energy at which the electrons in the vacuum level fall to the LUMO (lowest unoccupied molecular orbital) level of the material and stabilize, with the vacuum level as a reference. The electron affinity can be obtained by subtracting the optical band gap from the above-mentioned ionization potential, or similarly obtained from the electrochemical reduction potential by the following formula.

従って、本発明で用いられる正孔阻止層は、酸化電位と還元電位をもちいて、（正孔阻止材料の酸化電位）−（発光材料の酸化電位）≧０．１Ｖ（正孔阻止材料の還元電位）≧（発光材料の還元電位）と表現することも出来る。

Therefore, the hole blocking layer used in the present invention uses an oxidation potential and a reduction potential, and (the oxidation potential of the hole blocking material) − (the oxidation potential of the light emitting material) ≧ 0.1 V (the reduction of the hole blocking material). It can also be expressed as (potential) ≧ (reduction potential of the light emitting material).

Further, in the case of an element having an electron transport layer described later, the electron affinity of the hole blocking layer is preferably equal to or less than that of the electron transport layer.
(Reduction potential of electron transport material) ≧ (Reduction potential of hole blocking material) ≧ (Reduction potential of light emitting material)
As a hole blocking material satisfying such conditions, a mixed ligand complex represented by the following general formula (VII) is preferably used.

（式中、Ｒ¹⁶〜Ｒ²¹は、水素原子または任意の置換基を表す。Ｍ⁸はアルミニウム、ガリ
ウム、インジウムから選ばれる金属原子を表す。Ｌ⁵は以下に示す一般式（VIIａ）、（VIIｂ）、（VIIｃ）のいずれかで表される。

(Wherein R ^{16 to} R ²¹ represent a hydrogen atom or an arbitrary substituent. M ⁸ represents a metal atom selected from aluminum, gallium, and indium. L ⁵ represents a general formula (VIIa) shown below, ( It is represented by either VIIb) or (VIIc).

（式中、Ａr¹¹〜Ａr¹⁵は、置換基を有していてもよい芳香族炭化水素基または置換基を有していてもよい芳香族複素環基を表し、Ｚ³はシリコンまたはゲルマニウムを表す。）
前記一般式（VII） において、Ｒ¹⁶〜Ｒ²¹は水素原子または任意の置換基を表すが、好ましくは水素原子；塩素、臭素等のハロゲン原子；メチル基、エチル基等の炭素数１〜６のアルキル基；ベンジル基等のアラルキル基；ビニル基等の炭素数２〜６のアルケニル基；シアノ基；アミノ基；アシル基；メトキシ基、エトキシ基等の炭素数１〜６のアルコキシ基；メトキシカルボニル基、エトキシカルボニル基等の炭素数２〜６のアルコキシカルボニル基；カルボキシル基；フェノキシ基、ベンジルオキシ基などのアリールオキシ基；ジエチルアミノ基、ジイソプロピルアミノ基等のジアルキルアミノ基；ジベンジルアミノ基、ジフェネチルアミノ基などのジアラルキルアミノ基；トリフルオロメチル基等のα−ハロアルキル基；水酸基；置換基を有していてもよいフェニル基、ナフチル基等の芳香族炭化水素基；置換基を有していてもよいチエニル基、ピリジル基等の芳香族複素環基を表わす。

(In the formula, Ar ^{11 to} Ar ¹⁵ represent an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent, and Z ³ represents silicon or germanium. Represents.)
In the general formula (VII), R ^{16 to} R ²¹ represent a hydrogen atom or an arbitrary substituent, preferably a hydrogen atom; a halogen atom such as chlorine or bromine; a carbon number of 1 to 6 such as a methyl group or an ethyl group. An aralkyl group such as a benzyl group; an alkenyl group having 2 to 6 carbon atoms such as a vinyl group; a cyano group; an amino group; an acyl group; an alkoxy group having 1 to 6 carbon atoms such as a methoxy group and an ethoxy group; A C2-C6 alkoxycarbonyl group such as a carbonyl group or an ethoxycarbonyl group; a carboxyl group; an aryloxy group such as a phenoxy group or a benzyloxy group; a dialkylamino group such as a diethylamino group or a diisopropylamino group; a dibenzylamino group; Diaralkylamino groups such as diphenethylamino groups; α-haloalkyl groups such as trifluoromethyl groups; hydroxyl groups; substituents Represents an aromatic hydrocarbon group such as a phenyl group and naphthyl group which may have a substituent; an aromatic heterocyclic group such as a thienyl group and a pyridyl group which may have a substituent.

Examples of the substituent that the aromatic hydrocarbon group and the aromatic heterocyclic group may have include: a halogen atom such as a fluorine atom; an alkyl group having 1 to 6 carbon atoms such as a methyl group and an ethyl group; and a carbon number such as a vinyl group. An alkenyl group having 2 to 6 carbon atoms; an alkoxycarbonyl group having 2 to 6 carbon atoms such as a methoxycarbonyl group and an ethoxycarbonyl group; an alkoxy group having 1 to 6 carbon atoms such as a methoxy group and an ethoxy group; a phenoxy group and a benzyloxy group Aryloxy groups; dialkylamino groups such as dimethylamino groups and diethylamino groups; acyl groups such as acetyl groups; haloalkyl groups such as trifluoromethyl groups; cyano groups and the like. R ¹⁶ to R ²¹ are more preferably a hydrogen atom, an alkyl group, a halogen atom or a cyano group. R ¹⁹ is particularly preferably a cyano group.

In the above formula (VII), as Ar ^{11 to} Ar ¹⁵ , specifically, an aromatic hydrocarbon group such as phenyl group, biphenyl group, naphthyl group or the like which may have a substituent, thienyl group, pyridyl group, etc. Represents an aromatic heterocyclic group.
Preferred specific examples of the compound represented by the general formula (VII) are shown below, but are not limited thereto.

なお、これらの化合物は正孔阻止層中に、単独で用いてもよいし、必要に応じて、各々混合して用いてもよい。

In addition, these compounds may be used independently in a hole-blocking layer, and may be mixed and used as needed.

正孔阻止材料としては、前記一般式（VII） の混合配位子錯体の他に、以下の構造式で示される１，２，４−トリアゾール環残基を少なくとも１個有する化合物を用いることができる。

As the hole blocking material, in addition to the mixed ligand complex of the general formula (VII), a compound having at least one 1,2,4-triazole ring residue represented by the following structural formula may be used. it can.

  Specific examples of the compound having at least one 1,2,4-triazole ring residue represented by the above structural formula are shown below.

正孔阻止材料として、さらに、以下の構造式で示されるフェナントロリン環を少なくとも１個有する化合物が挙げられる。

Examples of the hole blocking material further include compounds having at least one phenanthroline ring represented by the following structural formula.

前記構造式で表わされるフェナントロリン環を少なくとも１個有する化合物の具体例を以下に示す。

Specific examples of the compound having at least one phenanthroline ring represented by the above structural formula are shown below.

正孔阻止層６の膜厚は、通常０．３以上、好ましくは０．５ｎｍ以上であり、また通常１００ｎｍ以下、好ましくは５０ｎｍ以下である。正孔阻止層も正孔輸送層と同様の方法で形成することができるが、通常は真空蒸着法が用いられる。

The film thickness of the hole blocking layer 6 is usually 0.3 or more, preferably 0.5 nm or more, and is usually 100 nm or less, preferably 50 nm or less. The hole blocking layer can also be formed by the same method as the hole transporting layer, but usually a vacuum deposition method is used.

  The cathode 8 serves to inject electrons into the light emitting layer 5 through the hole blocking layer 6. The material used for the cathode 8 can be the material used for the anode 2, but a metal having a low work function is preferable for efficient electron injection, such as tin, magnesium, indium, calcium, A suitable metal such as aluminum or silver or an alloy thereof is used. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy. Furthermore, inserting an ultrathin insulating film (0.1 to 5 nm) such as LiF, MgF2, or Li2O at the interface between the cathode and the light emitting layer or the electron transporting layer is also an effective method for improving the efficiency of the device (Appl Phys., Lett., 70, 152, 1997; JP-A-10-74586; IEEE Trans. Electron. Devices, 44, 1245, 1997). The film thickness of the cathode 8 is usually the same as that of the anode 2. For the purpose of protecting the cathode made of a low work function metal, further laminating a metal layer having a high work function and stable to the atmosphere on the cathode increases the stability of the device. For this purpose, metals such as aluminum, silver, copper, nickel, chromium, gold, platinum are used.

For the purpose of further improving the luminous efficiency of the device, an electron transport layer 7 may be provided between the hole blocking layer 6 and the cathode 8 as shown in FIGS. The electron transport layer 7 is formed of a compound that can efficiently transport electrons injected from the cathode between the electrodes to which an electric field is applied in the direction of the hole blocking layer 6.
Materials satisfying such conditions include metal complexes such as aluminum complexes of 8-hydroxyquinoline (Japanese Patent Laid-Open No. 59-194393), metal complexes of 10-hydroxybenzo [h] quinoline, oxadiazole derivatives, Styryl biphenyl derivative, silole derivative, 3- or 5-hydroxyflavone metal complex, benzoxazole metal complex, benzothiazole metal complex, trisbenzimidazolylbenzene (US Pat. No. 5,645,948), quinoxaline compound No. 207169), phenanthroline derivatives (Japanese Patent Laid-Open No. 5-331459), 2-t-butyl-9,10-N, N'-dicyanoanthraquinonediimine, n-type hydrogenated amorphous silicon carbide, n-type sulfide Examples include zinc and n-type zinc selenide.

The thickness of the electron transport layer 6 is usually 5 nm or more, preferably 10 nm or more, and is usually 200 nm or less, preferably 100 nm or less.
The electron transport layer 7 is formed by laminating on the hole blocking layer 6 by a coating method or a vacuum deposition method in the same manner as the hole transport layer 4. Usually, a vacuum deposition method is used.
An anode buffer layer 3 is also inserted between the hole transport layer 4 and the anode 2 for the purpose of further improving the efficiency of hole injection and improving the adhesion of the entire organic layer to the anode. (See FIG. 3). By inserting the anode buffer layer 3, the driving voltage of the initial element is lowered, and at the same time, an increase in voltage when the element is continuously driven with a constant current is suppressed. As conditions required for the material used for the anode buffer layer, a uniform thin film can be formed with good contact with the anode, and it is thermally stable, that is, the melting point and the glass transition temperature are high. The glass transition temperature is preferably 100 ° C. or higher. Furthermore, the ionization potential is low, hole injection from the anode is easy, and the hole mobility is high.

  For this purpose, phthalocyanine compounds such as copper phthalocyanine (JP-A 63-295695), polyaniline (Appl. Phys. Lett., 64, 1245, 1994), polythiophene (Optical Materials, 9, 125, 1998), etc., sputtered carbon films (Synth. Met., 91, 73, 1997), metals such as vanadium oxide, ruthenium oxide, molybdenum oxide Oxides (J. Phys. D, 29, 2750, 1996) have been reported.

  In addition, a layer containing a hole injection / transporting low molecular organic compound and an electron accepting compound (described in JP-A-11-251067, JP-A-2000-159221, etc.), an aromatic amino group, etc. A layer obtained by doping the contained non-conjugated polymer compound with an electron-accepting compound as necessary (Japanese Patent Laid-Open Nos. 11-135262, 11-283750, 2000-36390, Examples include JP 2000-150168, JP-A 2001-223084, and WO 97/33193), or layers containing a conductive polymer such as polythiophene (JP-A 10-92584). It is not limited to.

As the anode buffer layer material, either a low molecular compound or a high molecular compound can be used.
In the case of the anode buffer layer, a thin film can be formed in the same manner as the hole transport layer, but in the case of an inorganic material, a sputtering method, an electron beam evaporation method, or a plasma CVD method is further used.
When the anode buffer layer 3 formed as described above is formed using a low molecular weight compound, the lower limit is usually 3 nm, preferably about 10 nm, and the upper limit is usually 100 nm, preferably about 50 nm. is there. The lower limit of the thickness of the anode buffer layer 3 formed using the polymer compound is usually 5 nm, preferably about 10 nm, and the upper limit is usually about 1000 nm, preferably about 500 nm.

  The organic electroluminescence device of the present invention has a structure opposite to that shown in FIG. 1, that is, a cathode 8, a hole blocking layer 6, a light emitting layer 5, a hole transport layer 4 and an anode 2 can be laminated on a substrate in this order. As described above, it is also possible to provide the organic electroluminescence device of the present invention between two substrates, at least one of which is highly transparent. Similarly, the layers can be stacked in the reverse order of the layer configuration shown in FIG. 2 or FIG. Moreover, in any layer structure of FIGS. 1-3, in the range which does not deviate from the meaning of this invention, it may have arbitrary layers other than the above-mentioned, and the layer which has the function of several said layers together By providing, it is possible to appropriately modify the layer structure, for example.

  The organic electroluminescent device of the present invention has been described above by taking the layer structure containing the organic compound of the present invention in the light emitting layer as an example. As described above, the organic compound of the present invention includes the light emitting layer and the cathode or anode. The light emitting layer in that case may be selected from the organic compounds of the present invention or may be composed of other materials. Also good.

The present invention can be applied to any of an organic electroluminescent element having a single element, an element having a structure arranged in an array, and a structure having an anode and a cathode arranged in an XY matrix.
According to the present invention, by using the organic compound of the present invention, it is possible to obtain an organic electroluminescent element having excellent driving stability, a long driving life, and high light emission efficiency and low driving voltage.

EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited to description of a following example, unless the summary is exceeded.
(Example 1)

窒素雰囲気下、３−フルオロフェニルボロン酸（１．２ｇ）、１，３−ジブロモ−５−フルオロベンゼン（０．８ｇ）、テトラキス（トリフェニルフォスフィノ）パラジウム（０．４ｇ）、２Ｍリン酸カリウム水溶液（６．４ｍｌ）、トルエン（５０ｍｌ）を、加熱還流下、６．３時間撹拌した。トルエン（１００ｍｌ）を加えた後、水（２×１００ｍｌ）で洗浄し、硫酸マグネシウムで乾燥した後、濃縮した。これをカラムクロマトグラフィーにて精製し、3,5',3''-トリフルオロ-[1,1';3',1'']ターフェニル（１．０ｇ）を得た
。

Under a nitrogen atmosphere, 3-fluorophenylboronic acid (1.2 g), 1,3-dibromo-5-fluorobenzene (0.8 g), tetrakis (triphenylphosphino) palladium (0.4 g), 2M potassium phosphate An aqueous solution (6.4 ml) and toluene (50 ml) were stirred for 6.3 hours under heating and reflux. Toluene (100 ml) was added, washed with water (2 × 100 ml), dried over magnesium sulfate and concentrated. This was purified by column chromatography to obtain 3,5 ′, 3 ″ -trifluoro- [1,1 ′; 3 ′, 1 ″] terphenyl (1.0 g).

Sodium hydride (55%, 0.5 g) was allowed to act on carbazole (2.0 g) in anhydrous DMF (50 ml) under a nitrogen atmosphere, and then 3,5 ′, 3 ″ -trifluoro- [1, 1 ′; 3 ′, 1 ″] terphenyl (0.9 g) was added dropwise, and the mixture was stirred for 24 hours with heating under reflux. Water (30 ml) and methanol (30 ml) were added to the resulting solution, filtered and washed with methanol. The obtained solid was purified by column chromatography to obtain Target 1 (1.2 g). This had a glass transition temperature of 147 ° C. and a vaporization temperature of 528 ° C.

¹ H-NMR (270 MHz, CDCl3), 8.17-8.13 (m, 6H), 7.96-7.88 (m, 5H), 7.80-7.68 (m, 4H), 7.62-7.52 (m, 4H), 7.46-7.28 ( m, 16H)
DEI-MS m / z = 725 (M ⁺ )
(Example 2)
A thin film of the compound obtained in Example 1 was formed on a glass substrate by vacuum deposition. The compound was placed in a ceramic crucible installed in a vacuum vapor deposition apparatus, and the surroundings of the crucible were heated with a tantalum wire heater for vapor deposition. At this time, the temperature of the crucible was controlled to 260 to 273 ° C., the degree of vacuum at the time of vapor deposition was 2.4 × 10 ⁻⁴ Pa, the vapor deposition rate was 1.4 nm / second, and the film thickness was 50 nm.

The obtained thin film was a transparent amorphous film, and no crystallization was observed after storage for 1 month at room temperature in a nitrogen atmosphere. From this, the compound of this invention is used suitably as a layer material of the organic electroluminescent element excellent in stability and heat resistance.
(Comparative Example 1)
In the same manner as in Example 2, a thin film of CBP (compound described as (H-1) in the text) was prepared. This thin film was observed to be crystallized and clouded after 24 hours.
(Example 3)
An organic electroluminescent element having the structure shown in FIG. 3 was produced by the following method.

  An indium tin oxide (ITO) transparent conductive film 2 deposited on a glass substrate 1 with a thickness of 150 nm (sputtered film; sheet resistance 15 Ω) is formed into a 2 mm wide stripe using normal photolithography and hydrochloric acid etching. An anode was formed by patterning. The patterned ITO substrate was cleaned in the order of ultrasonic cleaning with acetone, water with pure water, and ultrasonic cleaning with isopropyl alcohol, dried with nitrogen blow, and finally subjected to ultraviolet ozone cleaning.

Next, an aromatic diamine-containing polyether (P-1) having the following structure as the anode buffer layer 3
(Weight average molecular weight 25,300; glass transition temperature 171 ° C.) and 10% by weight of the following compound (P-2) based on this (P-1) were spin-coated on the glass substrate under the following conditions.

溶媒 安息香酸エチル
Ｐ−１濃度 20[mg/ml]
Ｐ−２濃度 2[mg/ml]
スピナ回転数 1500[rpm]
スピナ回転時間 30[秒]
乾燥条件 100℃１時間

上記のスピンコートにより膜厚30nmの均一な薄膜が形成された。

Solvent Ethyl benzoate P-1 concentration 20 [mg / ml]
P-2 concentration 2 [mg / ml]
Spinner speed 1500 [rpm]
Spinner rotation time 30 [seconds]
Drying conditions 100 ° C for 1 hour

A uniform thin film having a thickness of 30 nm was formed by the above spin coating.

Next, the substrate 1 on which the anode buffer layer 3 was applied and formed was placed in a vacuum evaporation apparatus. After rough evacuation of the apparatus using an oil rotary pump, the apparatus was evacuated using a cryopump until the degree of vacuum in the apparatus was 3.0 × 10 ⁻⁵ Pa or less.
The following 4,4′-bis [N- (1-), placed in a ceramic crucible placed in the above device
Phenanthyl) -N-phenylamino] biphenyl

をるつぼの周囲のタンタル線ヒーターで加熱して蒸着を行った。この時のるつぼの温度は、301〜311℃の範囲で制御した。蒸着時の真空度3.0x10^-5Pa、蒸着速度は0.2nm/秒で膜厚60nmの正孔輸送層４を得た。

Vapor deposition was performed by heating with a tantalum wire heater around the crucible. At this time, the temperature of the crucible was controlled in the range of 301 to 311 ° C. A hole transport layer 4 having a thickness of 60 nm was obtained at a vacuum degree of 3.0 × 10 ⁻⁵ Pa and a deposition rate of 0.2 nm / sec.

  Subsequently, as the light-emitting layer 5, the compound (ELE-3) and the iridium complex indicated by (T-2) in the text were placed in separate ceramic crucibles, and film formation was performed by a binary simultaneous vapor deposition method.

実施例１で得られた本発明化合物のるつぼ温度は 254℃に、蒸着速度は 0.10nm／秒に
制御し、イリジウム錯体（Ｔ−２）は307〜308℃の温度範囲に制御し、膜厚30nmでイリジウム錯体（Ｔ−２）が本発明化合物に５重量％含有された発光層５を正孔輸送層４の上に積層した。蒸着時の真空度は5.0x10^-5Paであった。

The crucible temperature of the compound of the present invention obtained in Example 1 was controlled to 254 ° C., the deposition rate was controlled to 0.10 nm / second, and the iridium complex (T-2) was controlled to a temperature range of 307 to 308 ° C. The light emitting layer 5 containing 5% by weight of the iridium complex (T-2) in the compound of the present invention at 30 nm was laminated on the hole transport layer 4. The degree of vacuum during the deposition was 5.0 × 10 ⁻⁵ Pa.

Further, a compound shown as (HB-12) in the text as a hole blocking layer 6 was laminated with a crucible temperature of 192 ° C. and a film thickness of 10 nm at a deposition rate of 0.1 nm / second. The degree of vacuum during the deposition was 3.7 × 10 ⁻⁵ Pa.
On the hole blocking layer 6, an aluminum 8-hydroxyquinoline complex represented by the following structural formula (ET-1) as an electron transport layer 7, Al (C 9 H 6 NO) 3

を同様にして蒸着した。この時のアルミニウムの８−ヒドロキシキノリン錯体のるつぼ温度は 240〜 241℃の範囲で制御し、蒸着時の真空度は3.7x10^-5Pa、蒸着速度は0.2nm/秒で膜厚は35nmとした。

Was deposited in the same manner. At this time, the crucible temperature of the aluminum 8-hydroxyquinoline complex was controlled in the range of 240 to 241 ° C, the degree of vacuum during deposition was 3.7x10 ^-5 Pa, the deposition rate was 0.2 nm / sec, and the film thickness was 35 nm. .

The substrate temperature when vacuum-depositing the hole transport layer, the light emitting layer, the hole blocking layer, and the electron transport layer was maintained at room temperature.
Here, the element on which the electron transport layer 7 has been deposited is once taken out from the vacuum deposition apparatus into the atmosphere, and a 2 mm wide stripe-shaped shadow mask is used as a cathode deposition mask. The device was placed in close contact with each other so as to be orthogonal to each other, placed in another vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus was 1 × 10 ⁻⁴ Pa or less in the same manner as the organic layer. As the cathode 8, first, lithium fluoride (LiF) was formed on the electron transport layer 7 with a film thickness of 0.5 nm at a deposition rate of 0.01 nm / second and a degree of vacuum of 1 × 10 ⁻⁴ Pa using a molybdenum boat. . Next, aluminum was similarly heated by a molybdenum boat to form an aluminum layer having a thickness of 80 nm at a deposition rate of 0.5 nm / second and a degree of vacuum of 5 × 10 ⁻⁴ Pa, thereby completing the cathode 8. The substrate temperature at the time of vapor deposition of the above two-layer cathode 8 was kept at room temperature.

As described above, an organic electroluminescent element having a light emitting area portion having a size of 2 mm × 2 mm was obtained. The light emission characteristics of this element are shown in Table-1. In Table 1, luminous efficiency is a value at 100 cd / m ² , luminance / current is a slope of luminance-current density characteristics, and voltage is a value at 100 cd / m ² . The maximum wavelength of the emission spectrum of the device was 512 nm, which was identified as that from the iridium complex (T-2).
(Comparative Example 2)
A device was fabricated in the same manner as in Example 3 except that the compound obtained in Example 1 which was the host material of the light emitting layer was replaced with CBP (compound used in Comparative Example 1). The light emission characteristics of this element are shown in Table-1. The maximum wavelength of the emission spectrum of the device was 512 nm, which was almost the same as in Example 3, and was identified as that from the iridium complex (T-2). Compared with Example 3, the luminous efficiency is low.

The schematic cross section which showed an example of the organic electroluminescent element. The schematic cross section which showed another example of the organic electroluminescent element. The schematic cross section which showed another example of the organic electroluminescent element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Anode buffer layer 4 Hole transport layer 5 Light emitting layer 6 Hole blocking layer 7 Electron transport layer 8 Cathode

Claims (11)

On a basic skeleton in which a (6 is an integer of 3 or more) aromatic 6-membered rings are m-linked, b (b is an integer of 1 to (a + 2)) -NR ¹ R ² groups ( R ¹ and R ² each independently have an arbitrary substituent)
An organic compound characterized in that all of the —NR ¹ R ² groups are bonded to the m-position with respect to the m-linked site in the aromatic 6-membered ring.
(However, the aromatic 6-membered ring may have a substituent other than the —NR ¹ R ² group, and the plurality of aromatic 6-membered rings contained in one molecule may be the same or different from each other. In addition, a plurality of —NR ¹ R ² groups contained in one molecule may be the same as or different from each other.) The organic compound according to claim 1, wherein each of the a 6-membered aromatic rings has 1 or 0 -NR ¹ R ² groups. The organic compound of Claim 1 represented by general formula (I).

(In the formula, ring A ⁰ represents an aromatic 6-membered ring optionally having a substituent other than the —NR ¹ R ² group,
R ¹ and R ² represent an arbitrary substituent, and n represents an integer of 1 to 6. However, the plurality of rings A ⁰ , R ¹ and R ² contained in one molecule each represent the same thing. ) -NR ¹ R ² groups are N- azolyl group, claims 1 to organic compounds according to any one claim of 3. A charge transport material comprising the organic compound according to any one of claims 1 to 4. The organic electroluminescent element material containing the organic compound as described in any one of Claims 1 thru | or 4. In an organic electroluminescence device having an anode, a cathode, and a light emitting layer provided between both electrodes on a substrate,
The organic electroluminescent element which has a layer containing the organic compound as described in any one of Claims 1 thru | or 4. The organic electroluminescent element of Claim 7 whose layer containing the compound as described in any one of Claims 1 thru | or 4 is a light emitting layer. The organic electroluminescent element according to claim 8, wherein the light emitting layer comprises the organic compound according to any one of claims 1 to 4 as a host material, and the host material is doped with an organometallic complex. Furthermore, the organic electroluminescent element of Claim 8 or 9 which has a hole-blocking layer which contact | connects the cathode side interface of a light emitting layer. The electroluminescent element according to claim 8, wherein the light emitting layer emits green to red light.

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