JP2020132556A - Cyclic azine compound, organic electroluminescent element material, electron transport material for organic electroluminescent element, and organic electroluminescent element - Google Patents

Abstract

To provide a compound that has excellent drive voltage properties and long life properties, has low crystallinity, and contributes to forming a stable amorphous film, in an organic electroluminescent element.SOLUTION: A cyclic azine compound is represented by formula (1), and has a molecular weight of 751-1000, where Ar is a phenyl group, a biphenyl group, a terphenyl group or the like, which may have one or more methyl groups; n1 and n2 are 0-3; n3 is 1-3.SELECTED DRAWING: Figure 1

Description

The present invention relates to cyclic azine compounds, materials for organic electroluminescent devices, electron transport materials for organic electroluminescent devices, and organic electroluminescent devices.

Organic electroluminescent devices are used not only for small displays but also for large televisions, lighting, and the like, and their development is being vigorously carried out.
For example, Patent Document 1 discloses a cyclic azine compound having a specific substituent, which is excellent in heat resistance, has a low driving voltage, and contributes to the provision of a long-life organic electroluminescent device as a material for an organic electroluminescent device. ..
Patent Document 2 discloses a cyclic azine compound having a diarylpyridine structure.

Japanese Unexamined Patent Publication No. 2011-063584 International Publication No. 2017/22 1974

However, in recent years, the market demand for organic electroluminescent devices has become more and more high, and there is a demand for materials having excellent current efficiency characteristics, drive voltage characteristics, and long life characteristics.
Here, the organic electroluminescent device using the cyclic azine compound disclosed in Patent Document 1 exhibits excellent driving voltage characteristics, but further improvement is required in terms of long life characteristics and current efficiency characteristics.
Further, the organic electroluminescent device using the cyclic azine compound disclosed in Patent Document 2 exhibits better current efficiency characteristics and long life characteristics than the cyclic azine compound of Patent Document 1, but has driving voltage characteristics and long life. Further improvement is required for the characteristics. Especially in recent years, since the number of years of use of smartphones has been increasing, organic electroluminescent devices are required to be able to withstand long-term use, and are also increasingly used for televisions and lighting, and demands for their lifespan. Is extremely high.

One aspect of the present invention is a cyclic azine compound, a material for an organic electroluminescent device, and electron transport for an organic electroluminescent device, which are excellent in driving voltage characteristics and long life characteristics, have low crystallinity, and contribute to the formation of a stable amorphous film. It is aimed at providing materials.
Furthermore, another aspect of the present invention is directed to providing an organic electroluminescent device having excellent drive voltage characteristics and long life characteristics.

The cyclic azine compound according to one aspect of the present invention is
Expressed by equation (1)
The molecular weight is 751 or more and less than 1000:

式（１）中、
Ａｒは、メチル基を有していてもよいフェニル基、ビフェニル基、ターフェニル基、クアテルフェニル基、又はキンキフェニル基を表し；
ｎ１、ｎ２は、それぞれ独立に、０〜３の整数を表し；
ｎ３は、１〜３の整数を表し；
ｎ３が２以上の整数である場合、複数のＡｒは、同一であっても異なっていてもよい。

In equation (1),
Ar represents a phenyl group, a biphenyl group, a terphenyl group, a quaterphenyl group, or a kinkyphenyl group which may have a methyl group;
n1 and n2 each independently represent an integer of 0 to 3;
n3 represents an integer of 1-3;
When n3 is an integer of 2 or more, the plurality of Ars may be the same or different.

Further, the cyclic azine compound according to another aspect of the present invention is a cyclic azine compound represented by any one of the formulas (1-A) to (1-C):

In the formula, ^Ra is
An unsubstituted phenylene group directly linked to a phenylene ring directly linked to a triazine ring,
It may have one or more methyl groups and is a group consisting of three phenyl rings directly or indirectly linked to the unsubstituted phenylene group;

In the formula, R ^b is
An unsubstituted phenylene group directly linked to a phenylene ring directly linked to a triazine ring,
It may have one or more methyl groups and is a group consisting of four phenyl rings directly or indirectly linked to the unsubstituted phenylene group;

In the formula, R ^c is
An unsubstituted phenylene group directly linked to a phenylene ring directly linked to a triazine ring,
It may have one or more methyl groups and is a group consisting of five phenyl rings directly or indirectly linked to the unsubstituted phenylene group.

The material for an organic electroluminescent device according to still another aspect of the present invention contains the above cyclic azine compound.
The electron transport material for an organic electroluminescent device according to still another aspect of the present invention contains the above cyclic azine compound.
The organic electroluminescent device according to still another aspect of the present invention includes the cyclic azine compound.

According to one aspect of the present invention, a cyclic azine compound, a material for an organic electroluminescent device, and an organic electroluminescent device, which are excellent in driving voltage characteristics and long life characteristics, have low crystallinity, and contribute to the formation of a stable amorphous film. Electroluminescent materials can be provided.
According to another aspect of the present invention, it is possible to provide an organic electroluminescent device having excellent drive voltage characteristics and long life characteristics.

It is schematic cross-sectional view which shows an example of the laminated structure of the organic electroluminescent device containing the cyclic azine compound which concerns on one aspect of this invention. It is a graph which shows the DSC measurement result in the second heating of the compound (1A-29) (Synthesis Example-1). It is a graph which shows the DSC measurement result in the second heating of ETL-1 (synthesis comparative example-1). It is a graph which shows the DSC measurement result in the second heating of ETL-2 (synthesis comparative example-2). It is schematic cross-sectional view which shows an example (element Example-1) of the laminated structure of the organic electroluminescent device containing the cyclic azine compound which concerns on one aspect of this invention.

Hereinafter, the cyclic azine compound according to one aspect of the present invention will be described in detail.

<Cyclic azine compound>
The cyclic azine compound according to one aspect of the present invention is
Expressed by equation (1)
The molecular weight is 751 or more and less than 1000:

In equation (1),
Ar represents a phenyl group, a biphenyl group, a terphenyl group, a quaterphenyl group, or a kinkyphenyl group which may have a methyl group;
n1 and n2 each independently represent an integer of 0 to 3;
n3 represents an integer of 1-3;
When n3 is an integer of 2 or more, the plurality of Ars may be the same or different.

Further, the cyclic azine compound according to another aspect of the present invention is a cyclic azine compound represented by any one of the formulas (1-A) to (1-C):

In the formula, ^Ra is
An unsubstituted phenylene group directly linked to a phenylene ring directly linked to a triazine ring,
It may have one or more methyl groups and is a group consisting of three phenyl rings directly or indirectly linked to the unsubstituted phenylene group;

In the formula, R ^b is
An unsubstituted phenylene group directly linked to a phenylene ring directly linked to a triazine ring,
It may have one or more methyl groups and is a group consisting of four phenyl rings directly or indirectly linked to the unsubstituted phenylene group;

In the formula, R ^c is
An unsubstituted phenylene group directly linked to a phenylene ring directly linked to a triazine ring,
It may have one or more methyl groups and is a group consisting of five phenyl rings directly or indirectly linked to the unsubstituted phenylene group.

Hereinafter, the cyclic azine compounds represented by the formulas (1) and (1-A) to (1-C) may be referred to as the cyclic azine compound (1). Definitions of substituents in the cyclic azine compound (1) and preferred specific examples thereof are as follows.

<< About n1 to n3 >>
n1 and n2 each independently represent an integer of 0 to 3. From the viewpoint of availability of raw materials, n1 and n2 are each independently preferably an integer of 0 to 2, more preferably an integer of 0 to 1, and particularly preferably an integer of 1.
n3 represents an integer of 1 to 3. When n3 is an integer of 2 or more, the plurality of Ars may be the same or different.

When n1 and n2 are integers of 1, Ar is preferably a phenyl group, a biphenyl group, or a terphenyl group which may have a methyl group. Here, when n3 is 3, each of the plurality of Ars may independently have a methyl group, preferably a phenyl group or a biphenyl group. Here, when n3 is 2, each of the plurality of Ars is a phenyl group, a biphenyl group, or a terphenyl group which may independently have a methyl group, and at least one of the plurality of Ars is It is preferably a biphenyl group or a terphenyl group. Further, here, when n is 1, Ar is preferably a terphenyl group which may have a methyl group.

When n1 is 0 and n2 is an integer of 1, Ar is preferably a phenyl group, a biphenyl group, a terphenyl group, or a quaterphenyl group which may have a methyl group. Here, when n3 is 3, the plurality of Ars are phenyl groups, biphenyl groups or terphenyl groups, each of which may independently have a methyl group, and at least one of the plurality of Ars is a biphenyl group. , Or a terphenyl group is preferred. Here, when n3 is 2, the plurality of Ars may each independently have a methyl group, preferably a biphenyl group or a terphenyl group. Further, here, when n is 1, Ar is preferably a quaterphenyl group which may have a methyl group.

When n1 and n2 are integers of 0, Ar may have a methyl group, preferably a phenyl group, a biphenyl group, a terphenyl group, a quaterphenyl group, or a quinkiphenyl group. Here, when n3 is 3, the plurality of Ars are phenyl groups, biphenyl groups, terphenyl groups or quaterphenyl groups, each of which may independently have a methyl group; among the plurality of Ars. It is preferable that at least two are biphenyl groups or terphenyl groups, or at least one of the plurality of Ars is a terphenyl group or a quaterphenyl group. Here, when n3 is 2, the plurality of Ars are biphenyl groups, terphenyl groups, or quaterphenyl groups, each of which may independently have a methyl group, and at least among the plurality of Ars. It is preferable that one is a terphenyl group or a quaterphenyl group. Further, here, when n is 1, Ar is preferably a kinkyphenyl group which may have a methyl group.

<< About the molecular weight of cyclic azine compounds >>
The molecular weight of the cyclic azine compound represented by the formula (1) is 751 or more and less than 1000. When the molecular weight of the cyclic azine compound is 751 or more, the cyclic azine compound easily forms a stable amorphous film, and in addition, a high glass transition temperature can be realized, which is preferable. Further, when the molecular weight of the cyclic azine compound is less than 1000, thermal decomposition of the cyclic azine compound during sublimation purification or vapor deposition film formation can be suppressed, which is preferable. Among these, the molecular weight range is preferably 751 or more and less than 950, more preferably 751 or more and less than 875, and particularly preferably 751 or more and less than 800.

Specific examples of the groups represented by Ar are not particularly limited, but examples thereof include the groups (1) to (5) shown below as preferable examples.

(1): Phenyl group, p-tolyl group, m-tolyl group, o-tolyl group, 2,4-dimethylphenyl group, 3,5-dimethylphenyl group, mesitylene group.

(2): Biphenyl-2-yl group, biphenyl-3-yl group, biphenyl-4-yl group, 3-methylbiphenyl-4-yl group, 2'-methylbiphenyl-4-yl group, 4'-methyl Biphenyl-4-yl group, 2,2'-dimethylbiphenyl-4-yl group, 6-methylbiphenyl-3-yl group, 5-methylbiphenyl-3-yl group, 2'-methylbiphenyl-3-yl group 4, 4'-methylbiphenyl-3-yl group, 6,2'-dimethylbiphenyl-3-yl group, 5-methylbiphenyl-2-yl group, 6-methylbiphenyl-2-yl group, 2'-methylbiphenyl -2-Il group, 4'-methylbiphenyl-2-yl group, 6,2'-dimethylbiphenyl-2-yl group.

(3): p-terphenyl-4 yl group, p-terphenyl-3 yl group, p-terphenyl-2 yl group, m-terphenyl-4 yl group, m-terphenyl-3 yl group, m -Terphenyl-2 yl group, o-terphenyl-4 yl group, o-terphenyl-3 yl group, o-terphenyl-2 yl group.

(4): p-quaterphenyl-4yl group, p-quaterphenyl-3yl group, p-quaterphenyl-2yl group, 1,1': 3', 1'': 4'', 1'''-quaterphenyl, 6'-yl group, 1,1': 3', 1'': 4'', 1'''-quaterphenyl, 5'-yl group, 1,1' : 3', 1'': 4'', 1'''-quaterphenyl, 4'-yl group, 1,1': 3', 1'': 4'', 1'''-quater Phenyl, 2'-yl group, 1,1': 3', 1'': 3'', 1'''-quaterphenyl, 6'-yl group, 1,1': 3', 1'' : 3'', 1'''-quaterphenyl, 5'-yl group, 1,1': 3', 1'': 3'', 1'''-quaterphenyl, 4'-yl group , 1,1': 3', 1'': 3'', 1'''-quaterphenyl, 2'-yl group.

(5): p-Kinkiphenyl-4-yl group, p-kinkiphenyl-3-yl group, p-kinkiphenyl-2-yl group, 1,1': 4', 1'': 3'', 1''': 4''', 1''''-kinkiphenyl, 5''-yl group, 1,1': 4', 1'': 3'', 1''': 4'' ', 1''''-kinkiphenyl, 4''-yl group, 1,1': 4', 1'': 3'', 1''': 4''', 1''''- Kinkiphenyl, 2''-yl group, 1,1': 3', 1'': 3'', 1''': 3''', 1''''-kinkiphenyl, 5''-yl Group, 1,1': 3', 1'': 3'', 1''': 3''', 1''''-kinkiphenyl, 4''-yl group, 1,1': 3 ', 1'': 3'', 1''': 3''', 1''''-kinkiphenyl, 2''-yl group.

Among these substituents, phenyl group, p-tolyl group, biphenyl-2-yl group, biphenyl-3-yl group, biphenyl-4-yl group, p-terphenyl are excellent in electron transporting material properties. -4 yl group, p-terphenyl-3 yl group, p-terphenyl-2 yl group, m-terphenyl-4 yl group, m-terphenyl-3 yl group, m-terphenyl-2 yl group, o-terphenyl-4 yl group, o-terphenyl-3 yl group, o-terphenyl-2 yl group, 1,1': 3', 1'': 4'', 1'''-quater Phenyl, 5'-yl group, 1,1': 3', 1'': 3'', 1'''-quaterphenyl, 5'-yl group, 1,1': 4', 1'' : 3'', 1''': 4''', 1''''-kinkiphenyl, 5''-yl group, 1,1': 3', 1'': 3'', 1'' ': 3''', 1''''-kinkiphenyl, 5''-yl group, preferably phenyl group, p-tryl group, biphenyl-2-yl group, biphenyl-3-yl group, Biphenyl-4-yl group, p-terphenyl-4yl group, p-terphenyl-3yl group, m-terphenyl-4yl group, m-terphenyl-3yl group, o-terphenyl-4yl group More preferably, it is a group, an o-terphenyl-3-yl group.

Among these substituents, a phenyl group, a p-tolyl group, a biphenyl-2-yl group, a biphenyl-3-yl group, a biphenyl-4-yl group, and a p-terphenyl group are excellent in electron transporting material properties. -4 yl group, p-terphenyl-3-yl group, p-terphenyl-2 yl group, m-terphenyl-4 yl group, m-terphenyl-3 yl group, m-terphenyl-2 yl group, More preferably, it is an o-terphenyl-4 yl group, an o-terphenyl-3 yl group, an o-terphenyl-2 yl group, a phenyl group, a p-tolyl group, a biphenyl-2-yl group, and a biphenyl-. 3-Il group, biphenyl-4-yl group, p-terphenyl-4yl group, p-terphenyl-3yl group, m-terphenyl-4yl group, m-terphenyl-3yl group, o- It is particularly preferable that the terphenyl-4 yl group and the o-terphenyl-3 yl group are used.

<< About ^Ra >>
^Ra is
An unsubstituted phenylene group directly linked to a phenylene ring directly linked to a triazine ring,
It may have one or more methyl groups and is a group consisting of three phenyl rings directly or indirectly linked to the unsubstituted phenylene group.
That is, ^Ra is composed of a total of four phenyl rings. Of these four phenyl rings, one phenyl ring linked to the triazine ring via the other one phenylene group may be unsubstituted, and the remaining three phenyl rings may be substituted with a methyl group.

<< About R ^b >>
R ^b is
An unsubstituted phenylene group directly linked to a phenylene ring directly linked to a triazine ring,
It may have one or more methyl groups and is a group consisting of four phenyl rings directly or indirectly linked to the unsubstituted phenylene group.
That is, R ^b is composed of a total of 5 phenyl rings. Of these five phenyl rings, one phenyl ring linked to the triazine ring via the other one phenylene group may be unsubstituted, and the remaining four phenyl rings may be substituted with a methyl group.

<< About R ^c >>
R ^c is
An unsubstituted phenylene group directly linked to a phenylene ring directly linked to a triazine ring,
It may have one or more methyl groups and is a group consisting of five phenyl rings directly or indirectly linked to the unsubstituted phenylene group.
That is, R ^c is composed of a total of 6 phenyl rings. Of these six phenyl rings, one phenyl ring linked to the triazine ring via the other one phenylene group may be unsubstituted, and the remaining five phenyl rings may be substituted with a methyl group.

When the cyclic azine compound (1) is used as a part of a component of an organic electroluminescent device (OLED), effects such as lower voltage and longer life can be obtained. In particular, when the cyclic azine compound (1) is used as an electron transport layer, these effects are further exhibited.

<< Specific example of preferable cyclic azine compound (1) >>
Hereinafter, preferred specific examples of the cyclic azine compound (1) will be shown, but the present invention is not limited to these compounds.

Cyclic azine compounds shown in Table 1-1 to 1-4 has a skeleton of, shown below in Formula (1-A), and the substituents ^{R a} the backbone has found Table 1-1-1 The compounds of (1A-1) to (1A-66), which are the groups shown in -4, are shown.
In Tables 1-1 to 1-4, m represents any number from 1 to 66. Thus, for example, in the case of (1-A2) that the compounds have a (1-A) of the skeleton, the substituents ^{R a} the backbone has is p- quaterphenyl 3-yl group (1-A2 ) Compounds are shown.

From the viewpoint of producing the cyclic azine compound in good yield, among the cyclic azine compounds shown in Tables 1-1 to 1-4, the cyclic azine compounds shown in (1-A28) to (1-A50) are preferable, and (1) The cyclic azine compounds represented by −A28) to (1-A38) are more preferable.

In addition, although preferable specific examples of the cyclic azine compound (1) are shown in Tables 1-5 to 1-6, the present invention is not limited to these compounds.
The cyclic azine compounds shown in Tables 1-5 to 1-6 have a skeleton of the formula (1-B) shown below, and the substituent ^Rb contained in the skeleton is shown in Tables 1-5-1. The compounds (1-B1) to (1-B36), which are the groups shown in -6, are shown. The definition of m in Tables 1-5 to 1-6 is the same as that in Tables 1 to 4 except that m represents an arbitrary number of 1 to 36.

From the viewpoint of producing the cyclic azine compound in high yield, among the cyclic azine compounds shown in Tables 1-5 to 1-6, the cyclic azine compounds shown in (1-B1) to (1-B15) are preferable, and (1). The cyclic azine compounds represented by −B1) to (1-B9) are more preferable.

Further, although preferable specific examples of the cyclic azine compound (1) are shown in Tables 1-7 to 1-8, the present invention is not limited to these compounds.
Cyclic azine compounds shown in Table 1-7～1-8 has a skeleton of, shown below in formula (1-C), and the substituents ^{R c} the backbone has, Table 1-7～1 The compounds (1-C1) to (1-C36), which are the groups shown in −8, are shown. The definition of m in Tables 1-7 to 1-8 is the same as that in Tables 1 to 4, except that m represents an arbitrary number of 1 to 36.

Among the cyclic azine compounds shown in Tables 1-7 to 1-8, the cyclic azine compounds shown in (1-C1) to (1-C21) are preferable, and (1) The cyclic azine compounds represented by −C1) to (1-C15) are more preferable.

Hereinafter, the use of the cyclic azine compound (1) will be described.
<Materials for organic electroluminescent devices, electron transport materials for organic electroluminescent devices>
The cyclic azine compound (1) is not particularly limited, but can be used, for example, as a material for an organic electroluminescent device. Further, the cyclic azine compound (1) can be used, for example, as an electron transport material for an organic electroluminescent device.
That is, the material for an organic electroluminescent device according to one aspect of the present invention contains the cyclic azine compound (1). Further, the electron transport material for an organic electroluminescent device according to one aspect of the present invention contains a cyclic azine compound (1). The material for an organic electroluminescent device and the electron transporting material for an organic electroluminescent device containing the cyclic azine compound (1) contribute to the production of an organic electroluminescent device having excellent long life characteristics and driving voltage characteristics.

<Organic electroluminescent device>
The organic electroluminescent device according to one aspect of the present invention contains a cyclic azine compound (1).
The configuration of the organic electroluminescent device is not particularly limited, and examples thereof include the configurations (i) to (vi) shown below.
(I): anode / light emitting layer / cathode (ii): anode / hole transport layer / light emitting layer / cathode (iii): anode / light emitting layer / electron transport layer / cathode (iv): anode / hole transport layer / Light emitting layer / electron transport layer / cathode (v): anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode (vi): anode / hole injection layer / charge generation layer / Hole transport layer / Light emitting layer / Electron transport layer / Cathode

Hereinafter, the organic electroluminescent device according to one aspect of the present invention will be described in more detail with reference to FIG. 1 by taking the configuration of (vi) above as an example. FIG. 1 is a schematic cross-sectional view showing an example of a laminated structure of an organic electroluminescent device containing a cyclic azine compound according to one aspect of the present invention.
The organic electroluminescence device shown in FIG. 1 has a so-called bottom emission type element configuration, but the organic electroluminescence device according to one aspect of the present invention is limited to the bottom emission type element configuration. is not. That is, the organic electroluminescence device according to one aspect of the present invention may have a top emission type device configuration or another known device configuration.

The organic electroluminescent device 100 includes a substrate 1, an anode 2, a hole injection layer 3, a charge generation layer 4, a hole transport layer 5, a light emitting layer 6, an electron transport layer 7, and a cathode 8 in this order. However, some of these layers may be omitted, and conversely, other layers may be added. For example, an electron injection layer may be provided between the electron transport layer 7 and the cathode 8, the charge generation layer 4 is omitted, and the hole transport layer 5 is directly provided on the hole injection layer 3. May be good. Further, for example, a single layer having a function of a plurality of layers, such as an electron injection / transport layer having a function of an electron injection layer and a function of an electron transport layer in a single layer, is provided as a plurality of layers. It may be a configuration provided in place of. Further, for example, the single-layer hole transport layer 5 and the single-layer electron transport layer 7 may each be composed of a plurality of layers.

[Layer containing a cyclic azine compound represented by the formula (1)]
The organic electroluminescent device contains a cyclic azine compound represented by the above formula (1) in one or more layers selected from the group consisting of a light emitting layer and a layer between the light emitting layer and the cathode. Therefore, in the configuration example shown in FIG. 1, the organic electroluminescent device 100 contains the cyclic azine compound (1) in at least one layer selected from the group consisting of the light emitting layer 6 and the electron transport layer 7. In particular, it is preferable that the electron transport layer 7 contains the cyclic azine compound (1). The cyclic azine compound (1) may be contained in a plurality of layers included in the organic electroluminescent device, and when an electron injection layer is provided between the electron transport layer and the cathode, the electron injection layer is provided. The cyclic azine compound (1) may be contained.
In the following, the organic electroluminescent device 100 in which the electron transport layer 7 contains the cyclic azine compound (1) will be described.

[Board 1]
The substrate is not particularly limited, and examples thereof include a glass plate, a quartz plate, and a plastic plate. Further, in the case of a configuration in which light emission is extracted from the substrate 1 side, the substrate 1 is transparent with respect to the wavelength of light.

Examples of the light-transmitting plastic film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, and polycarbonate (Plastic film). PC), cellulose triacetate (TAC), cellulose acetate propionate (CAP) and the like.

[Anode 2]
An anode 2 is provided on the substrate 1 (on the hole injection layer 3 side).
In the case of an organic electroluminescent device in which light emission is taken out through an anode, the anode is formed of a material that allows or substantially passes the light emission.

The transparent material used for the anode is not particularly limited, but for example, indium-tin oxide (ITO; Indium Tin Oxide), indium-zinc oxide (IZO; Indium Zinc Oxide), tin oxide, and aluminum.・ Dope-type tin oxide, magnesium-indium oxide, nickel-tungsten oxide, other metal oxides, metal nitrides such as gallium nitride, metal serene products such as zinc selenium, and metal sulfides such as zinc sulfide. Can be mentioned.
In the case of an organic electroluminescent device having a configuration in which light is extracted only from the cathode side, the transmission characteristics of the anode are not important. Therefore, examples of the material used for the anode in this case include gold, iridium, molybdenum, palladium, platinum and the like.
A buffer layer (electrode interface layer) may be provided on the anode.

[Hole injection layer 3, hole transport layer 5]
Between the anode 2 and the light emitting layer 6 described later, a hole injection layer 3, a charge generation layer 4 described later, and a hole transport layer 5 are provided in this order from the anode 2 side.
The hole injection layer and the hole transport layer have a function of transmitting holes injected from the anode to the light emitting layer, and the hole injection layer and the hole transport layer are interposed between the anode and the light emitting layer. As a result, more holes are injected into the light emitting layer at a lower electric field.

The hole injection layer and the hole transport layer also function as electron barrier layers. That is, the electrons injected from the cathode and transported from the electron injection layer and / or the electron transport layer to the light emitting layer are generated by the electron barrier existing at the interface between the light emitting layer and the hole injection layer and / or the hole transport layer. , Leakage into the hole injection layer and / or the hole transport layer is suppressed. As a result, the electrons are accumulated at the interface in the light emitting layer, which has the effect of improving the current efficiency and the like, and an organic electroluminescent device having excellent light emitting performance can be obtained.

The material of the hole injection layer and the hole transport layer has at least one of hole injection property, hole transport property, and electron barrier property. The material of the hole injection layer and the hole transport layer may be either an organic substance or an inorganic substance.

Specific examples of the materials for the hole injection layer and the hole transport layer include triazole derivative, oxadiazole derivative, imidazole derivative, polyarylalkane derivative, pyrazoline derivative, pyrazolone derivative, phenylenediamine derivative, arylamine derivative, and amino-substituted chalcone. Derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilben derivatives, silazane derivatives, aniline copolymers, conductive polymer oligomers (particularly thiophene oligomers), porphyrin compounds, aromatic tertiary amine compounds, styryl Examples include amine compounds. Among these, a porphyrin compound, an aromatic tertiary amine compound, and a styrylamine compound are preferable, and an aromatic tertiary amine compound is particularly preferable.

Specific examples of the aromatic tertiary amine compound and the styrylamine compound include N, N, N', N'-tetraphenyl-4,4'-diaminophenyl, N, N'-diphenyl-N, N'-. Bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine (TPD), 2,2-bis (4-di-p-tolylaminophenyl) propane, 1,1-bis (4-Di-p-tolylaminophenyl) cyclohexane, N, N, N', N'-tetra-p-tolyl-4,4'-diaminobiphenyl, 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane, bis (4-dimethylamino-2-methylphenyl) phenylmethane, bis (4-di-p-tolylaminophenyl) phenylmethane, N, N'-diphenyl-N, N' -Di (4-methoxyphenyl) -4,4'-diaminobiphenyl, N, N, N', N'-tetraphenyl-4,4'-diaminodiphenyl ether, 4,4'-bis (diphenylamino) quadri Phenyl, N, N, N-tri (p-tolyl) amine, 4- (di-p-tolylamino) -4'-[4- (di-p-tolylamino) styryl] Stilben, 4-N, N-diphenyl Amino- (2-diphenylvinyl) benzene, 3-methoxy-4'-N, N-diphenylaminostillbenzene, N-phenylcarbazole, 4,4'-bis [N- (1-naphthyl) -N-phenylamino ] Biphenyl (NPD), 4,4', 4''-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine (MTDATA) and the like.
Further, inorganic compounds such as p-type-Si and p-type-SiC can also be mentioned as examples of the material of the hole injection layer and the material of the hole transport layer.

The hole injection layer and the hole transport layer may have a single layer structure made of one or more kinds of materials, or may have a laminated structure made of a plurality of layers having the same composition or different compositions.

[Charge generation layer 4]
A charge generation layer 4 may be provided between the hole injection layer 3 and the hole transport layer 5.
The material of the charge generation layer is not particularly limited, but for example, dipyrazino [2,3-f: 2', 3'-h] quinoxaline-2,3,6,7,10,11-hexacarbonitrile (HAT). -CN).
The charge generation layer may have a single-layer structure composed of one or more kinds of materials, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions.

[Light emitting layer 6]
A light emitting layer 6 is provided between the hole transport layer 5 and the electron transport layer 7 described later.
Examples of the material of the light emitting layer include a phosphorescent light emitting material, a fluorescent light emitting material, and a heat activation delayed fluorescent light emitting material. In the light emitting layer, electron-hole pairs are recombined, resulting in light emission.

The light emitting layer may consist of a single low molecular weight material or a single polymer material, but more generally it consists of a host material doped with a guest compound. The luminescence comes primarily from the dopant and can have any color.

Examples of the host material include compounds having a biphenyl group, a fluorenyl group, a triphenylsilyl group, a carbazole group, a pyrenyl group, and an anthryl group. More specifically, DPVBi (4,4'-bis (2,2-diphenylvinyl) -1,1'-biphenyl), BCzVBi (4,4'-bis (9-ethyl-3-carbazobinylene) 1, 1'-biphenyl), TBADN (2-talshalbutyl-9,10-di (2-naphthyl) anthracene), ADN (9,10-di (2-naphthyl) anthracene), CBP (4,4'-bis) (Carbazole-9-yl) biphenyl), CDBP (4,4'-bis (carbazole-9-yl) -2,2'-dimethylbiphenyl), 2- (9-phenylcarbazole-3-yl) -9- [Examples include 4- (4-phenylphenylquinazoline-2-yl) carbazole, 9,10-bis (biphenyl) anthracene and the like.

Examples of the fluorescent dopant include anthracene, pyrene, tetracene, xanthene, perylene, rubrene, coumarin, rhodamine, quinacridone, dicyanomethylenepyran compound, thiopyran compound, polymethine compound, pyrylium, thiapyrylium compound, fluorene derivative, perifrantene derivative, and indenoperylene. Derivatives, bis (azinyl) amine boron compounds, bis (azinyl) methane compounds, carbostryl compounds, and the like can be mentioned. The fluorescent dopant may be a combination of two or more selected from these.

Examples of the phosphorescent dopant include organometallic complexes of transition metals such as iridium, platinum, palladium, and osmium.

Specific examples of the fluorescent dopant and the phosphorescent dopant include Alq3 (tris (8-hydroxyquinoline) aluminum), DPAVBi (4,5'-bis [4- (di-p-tolylamino) styryl] biphenyl), perylene, and bis [ 2- (4-n-hexylphenyl) quinoline] (acetylacetonate) iridium (III), Ir (PPy) 3 (tris (2-phenylpyridine) iridium (III)), and FIrPic (bis (3,5-) Difluoro-2- (2-pyridyl) phenyl- (2-carboxypyridyl) iridium (III))) and the like can be mentioned.

Further, the light emitting material is not limited to being contained only in the light emitting layer. For example, the light emitting material may contain a layer (hole transport layer 5 or electron transport layer 7) adjacent to the light emitting layer. This makes it possible to further increase the current efficiency of the organic electroluminescent device.

The light emitting layer may have a single layer structure made of one or more kinds of materials, or may have a laminated structure made of a plurality of layers having the same composition or different compositions.

[Electronic transport layer 7]
An electron transport layer 7 is provided between the light emitting layer 6 and the cathode 8 described later.
The electron transport layer has a function of transferring electrons injected from the cathode to the light emitting layer. By interposing the electron transport layer between the cathode and the light emitting layer, electrons are injected into the light emitting layer with a lower electric field.

As described above, the electron transport layer preferably contains the cyclic azine compound represented by the above formula (1).

Further, the electron transport layer may further contain a conventionally known electron transport material in addition to the cyclic azine compound (1). Conventionally known electron transport materials include, for example, 8-hydroxyquinolinate lithium (Liq), bis (8-hydroxyquinolinate) zinc, bis (8-hydroxyquinolinate) copper, and bis (8-hydroxyquinoli). Nart) manganese, tris (8-hydroxyquinolinate) aluminum, tris (2-methyl-8-hydroxyquinolinate) aluminum, tris (8-hydroxyquinolinate) gallium, bis (10-hydroxybenzo [h]] Kinolinate) beryllium, bis (10-hydroxybenzo [h] quinolinate) zinc, bis (2-methyl-8-quinolinate) chlorogallium, bis (2-methyl-8-quinolinate) (o-cresolate) gallium, bis (2) -Methyl-8-quinolinate) -1-naphtholate aluminum, or bis (2-methyl-8-quinolinate) -2-naphtholate gallium, 2- [3- (9-phenanthrenyl) -5- (3-pyridinyl) Phenyl] -4,6-diphenyl-1,3,5-triazine, and 2- (4,''-di-2-pyridinyl [1,1': 3', 1''-terphenyl] -5- Il) -4,6-diphenyl-1,3,5-triazine, BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), Bphenyl (4,7-diphenyl-1,10-) Phenantroline), BAlq (bis (2-methyl-8-quinolinolate) -4- (phenylphenorate) aluminum), bis (10-hydroxybenzo [h] quinolinate) berylium) and the like.

The electron transport layer may have a single layer structure composed of one or more kinds of materials, or may have a laminated structure composed of a plurality of layers having the same composition or a different composition.
When the electron transport layer has a two-layer structure in which the light emitting layer side is the first electron transport layer and the cathode side is the second electron transport layer, it is preferable that the second electron transport layer contains the cyclic azine compound (1).

[Cathode 8]
A cathode 8 is provided on the electron transport layer 7.
In the case of an organic electroluminescence device having a configuration in which only light emitted through the anode is extracted, the cathode can be formed from any conductive material.
Materials for the cathode include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, indium. , Lithium / aluminum mixture, rare earth metals and the like.
A buffer layer (electrode interface layer) may be provided on the cathode (electron transport layer side).

[Formation method of each layer]
For each layer except the electrodes (anode, cathode) described above, the material of each layer (with a material such as a binder resin and a solvent if necessary) can be used, for example, by vacuum deposition method, spin coating method, casting method, LB ( It can be formed by thinning by a known method such as the Langmuir-Blodgett method).
The film thickness of each layer formed in this manner is not particularly limited and may be appropriately selected depending on the situation, but is usually in the range of 5 nm to 5 μm.

The anode and cathode can be formed by thinning the electrode material by a method such as vapor deposition or sputtering. A pattern may be formed through a mask having a desired shape during vapor deposition or sputtering, or a thin film may be formed by vapor deposition or sputtering, and then a pattern having a desired shape may be formed by photolithography.

The film thickness of the anode and the cathode is preferably 1 μm or less, and more preferably 10 nm or more and 200 nm or less.

The organic electroluminescent element according to one aspect of the present invention may be used as a kind of lamp for lighting or an exposure light source, a projection device of a type for projecting an image, or a still image or a moving image is directly visually recognized. It may be used as a display device (display) of the type to be used. When used as a display device for moving image playback, the drive method may be either a simple matrix (passive matrix) method or an active matrix method. Further, a full-color display device can be manufactured by using two or more kinds of organic electroluminescent devices of the present embodiment having different emission colors.

The cyclic azine compound (1) according to one aspect of the present invention can be synthesized by appropriately combining known reactions (for example, Suzuki-Miyaura cross-coupling reaction).
For example, the cyclic azine compound (1) according to one aspect of the present invention can be synthesized according to any one of the following reaction formulas (a) to (d), but is interpreted in any limitation by these examples. It's not a thing.

In the reaction formulas (a) to (d), Ar and n1 to n3 have the same definitions as the formula (1).

Y represents a leaving group, and examples thereof include, but are not limited to, a chlorine atom, a bromine atom, an iodine atom, and a triflate. Of these, a bromine atom or a chlorine atom is preferable in terms of good reaction yield. However, it may be preferable to use triflate because of the availability of raw materials.

M independently represents ZnR ¹ , MgR ² , Sn (R ³ ) ₃ or B (OR ⁴ ) ₂ . However, R ¹ and R ² independently represent a chlorine atom, a bromine atom or an iodine atom, R ³ represents an alkyl group or a phenyl group having 1 to 4 carbon atoms, and R ⁴ represents a hydrogen atom and 1 carbon atom. It represents an alkyl group or a phenyl group 4, B ^(oR ₄₎ 2 two ^{R 4} ₂ may be the same or different. Further, two R ⁴ may form a ring containing an oxygen atom and / or a boron atom together.

Examples of ZnR ¹ and MgR ² include ZnCl, ZnBr, ZnI, MgCl, MgBr, MgI and the like.
Examples of Sn (R ³ ) ₃ include Sn (Me) ₃ , Sn (Bu) _{3, and the} like.
Examples of B (OR ⁴ ) ₂ include B (OH) ₂ , B (OMe) ₂ , B (O ⁱ Pr) ₂ , B (OBu) _{2, and the} like. Further, as an example of B (OR ⁴ ) ₂ in the case where two R ^4s are integrated to form a ring containing an oxygen atom and / or a boron atom, the following (C-1) to (C-6) are shown. ) Can be exemplified, and the group represented by (C-2) is desirable in terms of good yield.

Of these reaction formulas, the reaction formulas (a), (b) or (d) are preferable in that the obtained cyclic azine compound (1) has high purity.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not construed as being limited to these examples.

^{1 1} H-NMR measurement was carried out using Gemini200 (manufactured by Varian).
The light emitting characteristics of the organic electroluminescent device were evaluated by applying a direct current to the manufactured device at room temperature and using a luminance meter (product name: BM-9, manufactured by Topcon Technohouse Co., Ltd.).

The glass transition temperature and the cold crystallization temperature were measured by DSC (Differential Scanning Calorimetry) measurement using DSC7020 (manufactured by Hitachi High-Tech Science Co., Ltd.).
The measurement conditions for the DSC are as follows. The measurement was carried out in a nitrogen atmosphere (flow rate 50 ml / min). Further, the first heating, the first cooling, and the second heating were performed in this order, and the glass transition temperature at the time of the second heating was defined as the glass transition temperature of the sample.
Sample amount: 5-10 mg
Measurement condition:
<First heating>
Heating rate: 10 ° C / min
Measurement temperature range: 30 ° C to 400 ° C
<First cooling>
Quenching with dry ice <second heating>
Heating rate: 5 ° C / min
Measurement temperature range: 30 ° C to 400 ° C

<Synthesis Example-1: Synthesis of compound (1-A29)>

In a 200 mL two-necked eggplant flask under a nitrogen stream, 2,4-bis [(1,1'-biphenyl) -4-yl] -6- (3-chlorophenyl) -1,3,5-triazine (2. 00g, 4.03 mmol), 4,4,5,5-tetramethyl-2- [5'-phenyl (1,1': 3', 1''-tetraphenyl) -3-yl)] -1, 3,2-Dioxaborolane (2.10 g, 4.86 mmol) was dissolved in tetrahydrofuran (40 mL). To this, palladium acetate (18 mg, 0.08 mmol) and 2-dicyclohexylphosphino-2', 4', 6'-triisopropylbiphenyl (77 mg, 0.16 mmol; X-Phos) were dissolved in tetrahydrofuran (5 mL). The solution was added, followed by a 2 M aqueous potassium carbonate solution (3 mL, 6 mmol) and stirred at 70 ° C. for 17 hours. After allowing to cool to room temperature, methanol (100 mL) was added, and the precipitated solid was filtered off. The obtained solid was washed with water (50 mL) and methanol (50 mL). This solid was dissolved in toluene, activated carbon was added, and the mixture was stirred and then filtered through Celite. The solid precipitated by recrystallization was recovered by filtration to obtain a white solid (yield 1.96 g, yield 63.5%, HPLC purity 99.8%) of the target compound (1-A29).

^{1 1} H-NMR (CDCl ₃ ) δ (ppm): 9.09 (t, 1H), 8.87 (dt, 4H), 8.83 (td, 1H), 8.07 (t, 1H), 7 .94-7.90 (m, 3H), 7.84 (t, 1H), 7.82-7.64 (m, 16H), 7.54-7.34 (m, 12H)
The glass transition temperature of compound (1-A29) was 111 ° C., and no cold crystallization temperature was observed.

<Synthetic Comparative Example-1>
4,6-diphenyl-2- [2'-(4,6-diphenylpyridin-2-yl) -biphenyl-3-yl] -1 described in Patent Document 2 (International Publication No. 2017/221974) , 3,5-Triazine (ETL-1) was prepared by the method described in Patent Document 2.
The glass transition temperature of the compound ETL-1 was 91 ° C., and the cold crystallization temperature was 155 ° C.
<Synthetic Comparative Example-2>
Journal of Materials Chemistry, 2009, 19, p. 2,4,6-Tris (biphenyl-3-yl) -1,3,5-triazine (ETL-2) described in 8112-8118 was prepared by the method described in the literature.
The glass transition temperature of compound ETL-2 was 54 ° C., and the cold crystallization temperatures were 89 ° C. and 136 ° C.
<Synthetic Comparative Example-3>
Chemistry Letters, 2004, 33, p. 2,4,6-tris (biphenyl-4-yl) -1,3,5-triazine (ETL-3) described in 1244-1245 was prepared by the method described in the literature.
No glass transition temperature was observed for compound ETL-3.

Table 2 summarizes the glass transition temperature and cold crystallization temperature of the compounds obtained in Synthesis Example-1 and Synthesis Comparative Examples-1 to 3.

In addition, FIG. 2 shows the DSC measurement results in the second heating of the compound (1-A29: Synthesis Example-1). 3 and 4 show the DSC measurement results in the second heating of ETL-1 (Synthetic Comparative Example-1) and ETL-2 (Synthetic Comparative Example-2), respectively. The glass transition temperature and the cold crystallization temperature are both calculated from the temperature at the start of the phase transition, that is, the onset temperature.
According to FIGS. 2 to 4, it can be seen that the compound (1A-29) according to one aspect of the present invention has a higher glass transition temperature than ETL-1 and ETL-2. Furthermore, it can be seen that cold crystallization peaks are observed in ETL-1 and ETL-2, but not in the compound (1-A29) according to one aspect of the present invention. Cold crystallization is a phenomenon in which a sample recrystallizes during temperature rise. On the other hand, since ETL-3 is prone to crystallization, the glass transition temperature has not been observed, indicating that the film quality is unstable.

That is, the cyclic azine compound according to one aspect of the present invention means that crystallization is unlikely to occur and the film quality is stable. The cyclic azine compound according to one aspect of the present invention has a high glass transition temperature due to its large molecular weight. In addition, it is considered that the cyclic azine compound according to one aspect of the present invention has low molecular symmetry due to the effect of the Ar group at an appropriate position, inhibits crystallization, and maintains good amorphousness. Be done.

Then, device evaluation was carried out using the obtained compound.

<Device Example-1 (see FIG. 5)>
(Preparation of substrate 101 and anode 102)
As a substrate having an anode on its surface, a glass substrate with an ITO transparent electrode in which a 2 mm wide indium tin oxide (ITO) film (film thickness 110 nm) was patterned in a stripe shape was prepared. Then, after cleaning this substrate with isopropyl alcohol, surface treatment was performed by ozone ultraviolet cleaning.

(Preparation for vacuum deposition)
Each layer was vacuum-deposited by a vacuum-film deposition method on the surface-treated substrate after cleaning, and each layer was laminated and formed.
First, the glass substrate was introduced into a vacuum vapor deposition tank, and the pressure was reduced to 1.0 × 10 ^-4 Pa. Then, each layer was produced in the following order according to the film forming conditions of each layer.

(Preparation of hole injection layer 103)
Sublimated and purified N- [1,1'-biphenyl] -4-yl-9,9-dimethyl-N- [4- (9-phenyl-9H-carbazole-3-yl) phenyl] -9H-fluorene-2 -Amine and 1,2,3-tris [(4-cyano-2,3,5,6-tetrafluorophenyl) methylene] cyclopropane were deposited at a rate of 0.15 nm / sec at 10 nm, and a hole injection layer was formed. 103 was prepared.

(Preparation of the first hole transport layer 1051)
Sublimated and purified N- [1,1'-biphenyl] -4-yl-9,9-dimethyl-N- [4- (9-phenyl-9H-carbazole-3-yl) phenyl] -9H-fluorene-2 -Amine was formed into a film at 85 nm at a rate of 0.15 nm / sec to prepare a first hole transport layer 1051.

(Preparation of the second hole transport layer 1052)
Sublimated and purified N-phenyl-N- (9,9-diphenylfluorene-2-yl) -N- (1,1'-biphenyl-4-yl) amine was formed into a 5 nm film at a rate of 0.15 nm / sec. , The second hole transport layer 1052 was prepared.

(Preparation of light emitting layer 106)
Sublimated and purified 3- (10-phenyl-9-anthril) -dibenzofuran and 2,7-bis [N, N-di- (4-tertbutylphenyl)] amino-bisbenzofurano-9,9'-spirofluorene Was formed at a ratio of 95: 5 (mass ratio) to 20 nm to prepare a light emitting layer 106. The film formation rate was 0.18 nm / sec.

(Preparation of the first electron transport layer 1071)
Sublimated and purified 2- [3'-(9,9-dimethyl-9H-fluorene-2-yl) [1,1'-biphenyl] -3-yl] -4,6-diphenyl-1,3,5- Triazine was deposited at a rate of 0.05 nm / sec at 6 nm to prepare a first electron transport layer 1071.

(Preparation of the second electron transport layer 1072)
Synthesis The compound (1-A29) and Liq synthesized in Example-1 were formed into a film at a ratio of 50:50 (mass ratio) at 25 nm to prepare a second electron transport layer 1072. The film forming rate was 0.15 nm / sec.

(Preparation of cathode 108)
Finally, a metal mask was arranged so as to be orthogonal to the ITO stripe on the substrate, and a cathode 108 was formed. As the cathode, silver / magnesium (mass ratio 1/10) and silver were formed in this order at 80 nm and 20 nm, respectively, to form a two-layer structure. The film formation rate of silver / magnesium was 0.5 nm / sec, and the film formation rate of silver was 0.2 nm / sec.

As described above, the ² organic electroluminescent device 100 having a light emitting area of 4 mm as shown in FIG. 5 was manufactured. Each film thickness was measured with a stylus type film thickness measuring meter (DEKTAK, manufactured by Bruker).

Further, this device was sealed in a nitrogen atmosphere glove box having an oxygen and water concentration of 1 ppm or less. The sealing was performed by using a glass sealing cap and a film-forming substrate (element) with a bisphenol F type epoxy resin (manufactured by Nagase ChemteX Corporation).

A direct current was applied to the organic electroluminescent device produced as described above, and the light emission characteristics were evaluated using a luminance meter (product name: BM-9, manufactured by Topcon Technohouse Co., Ltd.). As a light emitting characteristic, the current efficiency (cd / A) when a current density of 10 mA / cm ² was passed was measured, and the element life (h) at the time of continuous lighting was measured. Note that Table 4 of the device lifetime (h) measures the luminance decay time at the time of continuous lighting when driving was prepared device at an initial luminance 1000 cd / ^{m 2,} to the luminance (cd / ^{m 2)} is reduced 5% The time required for was measured. The drive voltage, current efficiency, and device life are relative values using the result in device reference example 2 described later as a reference value (100). The obtained measurement results are shown in Table 3.

<Element reference example-1>
An organic electroluminescent device was produced and evaluated in the same manner as in Device Example-1 except that ETL-1 synthesized in Synthesis Comparative Example-1 was used instead of compound (1-A29) in Device Example-1. did. The obtained measurement results are shown in Table 3.

<Element reference example-2>
In the device Example-1, 2- [5- (9-phenanthril) -4'-(2-) described in Patent Document 1 (Japanese Patent Laid-Open No. 2011-063584) instead of compound (1-A29). An organic electroluminescent device was prepared in the same manner as in Device Example-1 except that pyrimidyl) biphenyl-3-yl] -4,6-diphenyl-1,3,5-triazine (ETL-4) was used. evaluated. The obtained measurement results are shown in Table 3.

The cyclic azine compound (1) according to one aspect of the present invention is extremely excellent in heat resistance at the time of film formation, and by using the compound, it is possible to provide an organic electroluminescent device excellent in drive voltage characteristics and long life characteristics.
Further, the cyclic azine compound (1) according to one aspect of the present invention is used as an electron transport material for an organic electroluminescent device having an excellent low driving voltage. Further, according to the cyclic azine compound (1), it is possible to provide an organic electroluminescent device having low power consumption.
Further, the cyclic azine compound according to one aspect of the present invention can provide an organic electroluminescent device having a long life because the vapor deposition film is excellent in stability.
Further, since the thin film made of the cyclic azine compound (1) according to one aspect of the present invention is excellent in electron transport ability, hole blocking ability, redox resistance, water resistance, oxygen resistance, electron injection characteristics and the like, it emits organic electroluminescence. It is useful as a material for elements, as an electron transport material, a hole block material, a light emitting host material, and the like. It is especially useful when used as an electronic transport material.
Further, since the cyclic azine compound (1) according to one aspect of the present invention has a wide bandgap and a high triplet excitation level, it is used not only for conventional fluorescent device applications but also for phosphorescent devices and thermally activated delayed fluorescence. It can be suitably used for an organic electroluminescent device using TADF).

1,101 Substrate 2,102 Anode 3,103 Hole injection layer
4 Charge generation layer 5,105 Hole transport layer 6,106 Light emitting layer 7,107 Electron transport layer 8,108 Cathode 51,1051 First hole transport layer 52,1052 Second hole transport layer 71,1071 First electron Transport layer 72,1072 Second electron transport layer 100 Organic electroluminescent element

Claims (9)

Expressed by equation (1)
Cyclic azine compound having a molecular weight of 751 or more and less than 1000:

In equation (1),
Ar represents a phenyl group, a biphenyl group, a terphenyl group, a quaterphenyl group, or a kinkyphenyl group, which may have one or more methyl groups;
n1 and n2 each independently represent an integer of 0 to 3;
n3 represents an integer of 1-3;
When n3 is an integer of 2 or more, the plurality of Ars may be the same or different. The cyclic azine compound according to claim 1, wherein n1 and n2 are independently integers of 0 or 1. Cyclic azine compound represented by any one of the formulas (1-A) to (1-C):

In the formula, ^Ra is
An unsubstituted phenylene group directly linked to a phenylene ring directly linked to a triazine ring,
It may have one or more methyl groups and is a group consisting of three phenyl rings directly or indirectly linked to the unsubstituted phenylene group;

In the formula, R ^b is
An unsubstituted phenylene group directly linked to a phenylene ring directly linked to a triazine ring,
It may have one or more methyl groups and is a group consisting of four phenyl rings directly or indirectly linked to the unsubstituted phenylene group;

In the formula, R ^c is
An unsubstituted phenylene group directly linked to a phenylene ring directly linked to a triazine ring,
It may have one or more methyl groups and is a group consisting of five phenyl rings directly or indirectly linked to the unsubstituted phenylene group. The cyclic azine compound according to claim 1, which is represented by the formula (1-A):

In the formula, ^Ra is any one of the groups listed in Tables 1-1 to 1-4.

The cyclic azine compound according to claim 1, which is represented by the formula (1-B):

In the formula, R ^b is any one of the groups listed in Tables 1-5 to 1-6.

The cyclic azine compound according to claim 1, which is represented by the formula (1-C):

In the formula, R ^c is any one of the groups listed in Tables 1-7 to 1-8.

A material for an organic electroluminescent device containing the cyclic azine compound according to any one of claims 1 to 6. An electron transport material for an organic electroluminescent device containing the cyclic azine compound according to any one of claims 1 to 6. An organic electroluminescent device containing the cyclic azine compound according to any one of claims 1 to 6.

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