JP2021166212A - Organic electroluminescent element - Google Patents

Abstract

To provide an organic electroluminescent element which is improved in voltage rise during driving, durability and color shift.SOLUTION: An organic electroluminescent element of the present invention includes: an anode; a cathode; a first luminous layer and a second luminous layer provided between the anode and the cathode; and an intermediate connector layer provided between the first luminous layer and the second luminous layer. The organic electroluminescent element is characterized in that the intermediate connector layer contains alkali metal or alkaline earth metal, and a compound having a structure represented by the following general formula (1) is contained in the intermediate connector layer or in a layer between the intermediate connector layer and the first luminous layer. [In the general formula (1), A1 and A2 each represent a residue forming a 6-membered aromatic heterocycle with a nitrogen atom, while the 6-membered aromatic heterocycle may be condensed, and L represents a single bond, an aromatic hydrocarbon ring, an aromatic heterocycle or an alkyl group.]SELECTED DRAWING: None

Description

The present invention relates to an organic electroluminescent element, and more particularly to an organic electroluminescent element having improved voltage rise, durability and color shift during driving.

The organic electroluminescence device (hereinafter, also referred to as an organic EL device) has a structure in which a light emitting layer containing a light emitting compound is sandwiched between a cathode and an anode. By applying an electric field to this, excitons are generated by recombination of holes injected from the anode and electrons injected from the cathode in the light emitting layer. It is a light emitting element that utilizes the emission of light (fluorescence / phosphorescence) when the excitons are deactivated. Further, the organic EL element is an all-solid-state element composed of a film of an organic material having a thickness of only about submicron between the electrodes, and can emit light at a voltage of about several V to several tens of V. Therefore, it is expected to be used for next-generation flat displays and lighting.

Since the organic electroluminescence material (hereinafter, also referred to as organic EL material) is an insulating organic molecule, electrons and holes cannot be directly injected into the dopant from the anode and the cathode (charge according to the so-called ohm law). Cannot be injected).
That is, since the energy barrier between the anode and the light emitting layer is large, it is not possible to directly inject holes. , It is necessary to reduce the energy barrier.
Therefore, a thin film hole injection / transport layer having intermediate energy is required between the anode and the light emitting layer. Similarly, an electron injection / transport layer is required on the electron side.
Furthermore, since it is a general principle that charges move by hopping between π-conjugated sites of organic molecules, all organic EL materials are selected from compounds having a chemical structure that combines aromatic compounds such as benzene and pyridine. (See, for example, Patent Document 1).

Specifically, as shown in FIG. 1, it is considered that electrons are injected from the cathode into the LUMO energy level of the organic molecule to form an anion radical. Since anion radicals are unstable, they transfer electrons to adjacent molecules. When this process is repeated continuously, it seems as if only the electrons are moving from the right side to the center of the schematic diagram. As described above, in order to drive the organic EL element at a low voltage, a material having a high electron hopping is particularly required as an electron transport material.

Generally, a nitrogen-containing aromatic compound is used for the electron transport layer, but an intermediate connector layer is provided between the first light emitting layer and the second light emitting layer, and between the first light emitting layer and the second light emitting layer. When a general electron transport material is used for the intermediate connector layer or the electron transport layer existing between the first light emitting layer and the intermediate connector layer in the organic EL element, the voltage rise during driving, durability and color There is a problem in terms of deviation.
Further, although it is known that a nitrogen-containing aromatic compound is used to suppress the aggregation of silver (see, for example, Patent Documents 2 and 3), there are reports of suppressing the diffusion of alkali metals and alkaline earth metals. No.

JP-A-2010-166070 Patent No. 5577186 International Publication No. 2013/161602

The present invention has been made in view of the above problems and situations, and a problem to be solved thereof is to provide an organic electroluminescence device in which voltage rise during driving, durability and color shift are improved.

In the process of examining the cause of the above problem in order to solve the above problems, the present inventor has an intermediate connector layer provided between the first light emitting layer and the second light emitting layer being an alkali metal or an alkaline earth metal. By containing a compound having a specific structure in the intermediate connector layer or the layer between the intermediate connector layer and the first light emitting layer, alkali metal or alkaline earth metal can be diffused into the light emitting layer. We have found that it is possible to provide an organic electroluminescence element which can be suppressed and has improved voltage rise during driving, durability and color shift, and has arrived at the present invention.
That is, the above problem according to the present invention is solved by the following means.

［一般式（１）中、Ａ１及びＡ２は、窒素原子とともに６員の芳香族複素環を形成する残基を表し、この６員の芳香族複素環は縮環してもよい。Ｌは、単結合、芳香族炭化水素環、芳香族複素環又はアルキル基を表す。］ 1. 1. An anode, a cathode, a first light emitting layer and a second light emitting layer provided between the anode and the cathode, and an intermediate connector layer provided between the first light emitting layer and the second light emitting layer. It is an organic electroluminescence element that has
The intermediate connector layer contains an alkali metal or an alkaline earth metal, and the intermediate connector layer contains an alkali metal or an alkaline earth metal.
An organic electroluminescence device, wherein the intermediate connector layer or a layer between the intermediate connector layer and the first light emitting layer contains a compound having a structure represented by the following general formula (1).

[In the general formula (1), A1 and A2 represent residues that form a 6-membered aromatic heterocycle together with a nitrogen atom, and the 6-membered aromatic heterocycle may be condensed. L represents a single bond, an aromatic hydrocarbon ring, an aromatic heterocycle or an alkyl group. ]

［一般式（２）中、Ｒａ、Ｒｂ及びＲｃは、水素原子又は置換基を表す。Ｒａ、Ｒｂ及びＲｃのうち少なくとも一つが、６員の芳香族複素環を表し、この６員の芳香族複素環は縮環してもよい。ｎ１は、１〜４の整数を表す。］ 2. The first item, wherein the intermediate connector layer or the layer between the intermediate connector layer and the first light emitting layer contains a compound having a structure represented by the following general formula (2). Organic electroluminescence element.

[In the general formula (2), Ra, Rb and Rc represent a hydrogen atom or a substituent. At least one of Ra, Rb and Rc represents a 6-membered aromatic heterocycle, and the 6-membered aromatic heterocycle may be fused. n1 represents an integer of 1 to 4. ]

［一般式（３）中、Ｒｅ、Ｒｄ及びＲｆは、水素原子又は置換基を表す。Ｒｅ、Ｒｄ及びＲｆのうち少なくとも一つが、６員の芳香族複素環を表し、この６員の芳香族複素環は縮環してもよい。ｎ２は、１〜４の整数を表す。］ 3. 3. The first item, wherein the intermediate connector layer or the layer between the intermediate connector layer and the first light emitting layer contains a compound having a structure represented by the following general formula (3). Organic electroluminescence element.

[In the general formula (3), Re, Rd and Rf represent a hydrogen atom or a substituent. At least one of Re, Rd and Rf represents a 6-membered aromatic heterocycle, and the 6-membered aromatic heterocycle may be fused. n2 represents an integer of 1 to 4. ]

［一般式（４）中、Ｒｇ、Ｒｈ、Ｒｉ及びＲｊは、水素原子又は置換基を表す。Ｒｇ、Ｒｈ、Ｒｉ及びＲｊのうち少なくとも一つが、６員の芳香族複素環を表し、この６員の芳香族複素環は縮環してもよい。Ｌ_２は、単結合、芳香族炭化水素環、芳香族複素環又はアルキル基を表す。］ 4. The first item, wherein the intermediate connector layer or the layer between the intermediate connector layer and the first light emitting layer contains a compound having a structure represented by the following general formula (4). Organic electroluminescence element.

[In the general formula (4), Rg, Rh, Ri and Rj represent a hydrogen atom or a substituent. At least one of Rg, Rh, Ri and Rj represents a 6-membered aromatic heterocycle, and the 6-membered aromatic heterocycle may be fused. L ₂ represents a single bond, an aromatic hydrocarbon ring, an aromatic heterocycle or an alkyl group. ]

［一般式（５）中、Ａｒは、カルバゾール、ジベンゾフラン、アザジベンゾフラン、ジベンゾチオフェン、アザジベンゾチオフェン、アザカルバゾール、ナフタレン、アントラセン、フェナンスレン又はフルオレンを表す。Ｒｋは、水素原子又は置換基を表す。Ｒｋのうち少なくとも二つが、６員の芳香族複素環を表し、この６員の芳香族複素環は縮環してもよい。ｎ３は２以上を表す。］ 5. The first item, wherein the intermediate connector layer or the layer between the intermediate connector layer and the first light emitting layer contains a compound having a structure represented by the following general formula (5). Organic electroluminescence element.

[In general formula (5), Ar represents carbazole, dibenzofuran, azadibenzofuran, dibenzothiophene, azadibenzothiophene, azacarbazole, naphthalene, anthracene, phenanthrene or fluorene. Rk represents a hydrogen atom or a substituent. At least two of Rk represent a 6-membered aromatic heterocycle, and the 6-membered aromatic heterocycle may be fused. n3 represents 2 or more. ]

［一般式（６）中、Ｙ_１及びＹ_２は、Ｏ、Ｓ又はＮ−Ｒ_１を表す。Ｘ_１〜Ｘ_１６は、Ｃ−Ｒ_２又はＮを表す。Ｘ_１〜Ｘ_１６のうち少なくとも二つは、Ｎを表す。Ｌ_１は、単結合、芳香族炭化水素環、芳香族複素環又はアルキル基を表す。Ｒ_１及びＲ_２は、芳香族炭化水素環、芳香族複素環又はアルキル基を表す。］ 6. The first item, wherein the intermediate connector layer or the layer between the intermediate connector layer and the first light emitting layer contains a compound having a structure represented by the following general formula (6). Organic electroluminescence element.

[In the general formula (6), Y ₁ and Y ₂ represent O, S or N-R ₁ . X _{1 to} X ₁₆ represent _{CR 2} or N. At least two of _{X 1 to} X _{16 represent N.} L ₁ represents a single bond, an aromatic hydrocarbon ring, an aromatic heterocycle or an alkyl group. R ₁ and R ₂ represent an aromatic hydrocarbon ring, an aromatic heterocycle or an alkyl group. ]

7. The organic electroluminescence element according to any one of items 1 to 6, wherein the intermediate connector layer contains Li, Na, K, Mg or Ca.

8. The organic electroluminescence device according to any one of items 1 to 6, wherein the intermediate connector layer contains Li.

9. The item according to any one of items 1 to 8, wherein the intermediate connector layer contains any of the compounds having a structure represented by the general formulas (1) to (6). Organic electroluminescence element.

10. Items 1 to 1, wherein the layer between the intermediate connector layer and the first light emitting layer contains any of the compounds having a structure represented by the general formulas (1) to (6). The organic electroluminescence device according to any one of items up to item 8.

According to the above means of the present invention, it is possible to provide an organic electroluminescence device in which a voltage rise during driving, durability and color shift are improved.
Although the mechanism of expression or mechanism of action of the effect of the present invention has not been clarified, it is inferred as follows.
The compound having the structure represented by the general formula (1) used in the organic electroluminescence device of the present invention has an aromatic heterocycle containing a nitrogen atom in the molecule, and therefore, it can be used with an alkali metal or an alkaline earth metal. Interact and fix alkali metals or alkaline earth metals. That is, the diffusion of alkali metals or alkaline earth metals can be suppressed.
Here, in a general aromatic heterocycle containing a nitrogen atom, the interaction with the alkali metal or the alkaline earth metal is weak, and the effect of suppressing the diffusion of the alkali metal or the alkaline earth metal is weak. Therefore, as a result of diligent studies, a strong effect can be obtained mainly in the case of a compound that forms the following two interactions (a compound having the following structures A and B). In the compounds having the following structures A and B, the case where Li is used as the alkali metal is shown.
A: When a nitrogen (N) atom is present at the ortho position of the condensed ring structure B: When there are many freely rotating nitrogen (N) atoms in the molecule, two molecules interact with each other.

Therefore, in the case of the compound having the structure represented by the general formulas (2), (3) and (6) as the compound having the structure A, the compound having the structure B has the general formula (4) and In the case of the compound having the structure represented by (5), the diffusion of alkali metal or alkaline earth metal can be surely suppressed, and as a result, the voltage rise during driving, durability and color shift are improved. It is presumed that it can be done.

Schematic diagram for explaining the charge transport / injection mechanism Schematic diagram showing an example of the configuration of an organic EL element Schematic diagram showing an example of a display device composed of an organic EL element Schematic diagram of display unit A Pixel schematic Schematic diagram of a passive matrix full-color display device Schematic diagram of the lighting device Schematic diagram of the lighting device

The organic electroluminescence element of the present invention comprises an anode, a cathode, a first light emitting layer and a second light emitting layer provided between the anode and the cathode, and between the first light emitting layer and the second light emitting layer. An organic electroluminescence element having an intermediate connector layer provided in the above, wherein the intermediate connector layer contains an alkali metal or an alkaline earth metal, and the intermediate connector layer or the intermediate connector layer and the first The layer between the light emitting layers is characterized by containing a compound having a structure represented by the general formula (1).
This feature is a technical feature common to or corresponding to each of the following embodiments.

In an embodiment of the present invention, a compound having a structure represented by the general formulas (2) to (6) in the intermediate connector layer or a layer between the intermediate connector layer and the first light emitting layer. It is preferable to contain any of them because they can interact with the alkali metal or the alkaline earth metal and suppress the diffusion of the alkali metal or the alkaline earth metal.

The inclusion of Li, Na, K, Mg or Ca in the intermediate connector layer interacts with the nitrogen atom in the compound having the structure represented by the general formula (1), and alkali metal or alkaline earth It is preferable in that the diffusion of metal can be suppressed.

The inclusion of any of the compounds having the structures represented by the general formulas (1) to (6) in the intermediate connector layer suppresses the diffusion of the alkali metal or the alkaline earth metal to the light emitting layer. It is preferable from the viewpoint of preventing intrusion, and the layer between the intermediate connector layer and the first light emitting layer contains any of the compounds having a structure represented by the general formulas (1) to (6). However, it is preferable in that it suppresses the diffusion of the alkali metal or the alkaline earth metal and prevents the invasion into the light emitting layer.

Hereinafter, the present invention, its constituent elements, and modes and modes for carrying out the present invention will be described. In the present application, "~" is used to mean that the numerical values described before and after the value are included as the lower limit value and the upper limit value.

[Overview of the organic EL device of the present invention]
The organic EL element of the present invention comprises an anode, a cathode, a first light emitting layer and a second light emitting layer provided between the anode and the cathode, and between the first light emitting layer and the second light emitting layer. An organic electroluminescence element having an intermediate connector layer provided, wherein the intermediate connector layer contains an alkali metal or an alkaline earth metal, and the intermediate connector layer or the intermediate connector layer and the first light emitting The layer between the layers is characterized by containing a compound having a structure represented by the following general formula (1).
Specific examples of the layer between the intermediate connector layer and the first light emitting layer include a first electron transport layer described later.

<Alkali metal or alkaline earth metal>
Examples of the alkali metal or alkaline earth metal contained in the intermediate connector layer include Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba, Ra and the like, and among them, the general formula ( Li, Na, K, Mg or Ca are preferable, and Li is preferable in that it can interact with the nitrogen atom in the compound having the structure represented by 1) and suppress the diffusion of alkali metal or alkaline earth metal. Especially preferable.

［一般式（１）中、Ａ１及びＡ２は、窒素原子とともに６員の芳香族複素環を形成する残基を表し、この６員の芳香族複素環は縮環してもよい。Ｌは、単結合、芳香族炭化水素環、芳香族複素環又はアルキル基を表す。］ <Compound having a structure represented by the general formula (1)>

[In the general formula (1), A1 and A2 represent residues that form a 6-membered aromatic heterocycle together with a nitrogen atom, and the 6-membered aromatic heterocycle may be condensed. L represents a single bond, an aromatic hydrocarbon ring, an aromatic heterocycle or an alkyl group. ]

In the general formula (1), examples of the residue forming the 6-membered aromatic heterocycle formed with the nitrogen atom represented by A1 and A include pyridine, pyrimidine, pyrazine, triazine and the like. Examples of the fused 6-membered aromatic heterocycle include quinazoline, quinoline, isoquinoline, azadibenzofuran, azacarbazole, azadibenzothiophene, benzimidazole ring, benzoquinoline ring and benzoisoquinoline ring.
The aromatic hydrocarbon ring represented by L is phenyl, biphenyl, terphenyl, naphthalene, anthracene, phenanthrene or fluorene, and the aromatic heterocycle is carbazole, dibenzofuran, azadibenzofuran, dibenzothiophene, azadibenzothiophene, azacarbazole, Examples of the alkyl group include methyl, ethyl, isopropyl, propyl, butyl, t-butyl, hexyl and the like.

Further, the compound having a structure represented by the general formula (1) is preferably a compound having a structure represented by any of the following general formulas (2) to (6).

［一般式（２）中、Ｒａ、Ｒｂ及びＲｃは、水素原子又は置換基を表す。Ｒａ、Ｒｂ及びＲｃのうち少なくとも一つが、６員の芳香族複素環を表し、この６員の芳香族複素環は縮環してもよい。ｎ１は、１〜４の整数を表す。］ <Compound having a structure represented by the general formula (2)>

[In the general formula (2), Ra, Rb and Rc represent a hydrogen atom or a substituent. At least one of Ra, Rb and Rc represents a 6-membered aromatic heterocycle, and the 6-membered aromatic heterocycle may be fused. n1 represents an integer of 1 to 4. ]

Examples of the substituent represented by Ra, Rb and Rc in the general formula (2) include an aromatic hydrocarbon ring, an aromatic heterocycle, an alkyl, a cyano, a halogen atom and the like. Further, the 6-membered aromatic heterocycle represented by at least one of Ra, Rb and Rc is the same as that mentioned in A1 and A2 of the general formula (1).

［一般式（３）中、Ｒｅ、Ｒｄ及びＲｆは、水素原子又は置換基を表す。Ｒｅ、Ｒｄ及びＲｆのうち少なくとも一つが、６員の芳香族複素環を表し、この６員の芳香族複素環は縮環してもよい。ｎ２は、１〜４の整数を表す。］ <Compound having a structure represented by the general formula (3)>

[In the general formula (3), Re, Rd and Rf represent a hydrogen atom or a substituent. At least one of Re, Rd and Rf represents a 6-membered aromatic heterocycle, and the 6-membered aromatic heterocycle may be fused. n2 represents an integer of 1 to 4. ]

In the general formula (3), the substituents represented by Re, Rd and Rf are the same as the substituents represented by Ra, Rb and Rc in the general formula (2). Further, the aromatic heterocycle having at least one of Re, Rd and Rf having 6 members is the same as that mentioned in A1 and A2 of the general formula (1).

［一般式（４）中、Ｒｇ、Ｒｈ、Ｒｉ及びＲｊは、水素原子又は置換基を表す。Ｒｇ、Ｒｈ、Ｒｉ及びＲｊのうち少なくとも一つが、６員の芳香族複素環を表し、この６員の芳香族複素環は縮環してもよい。Ｌ_２は、単結合、芳香族炭化水素環、芳香族複素環又はアルキル基を表す。］ <Compound having a structure represented by the general formula (4)>

[In the general formula (4), Rg, Rh, Ri and Rj represent a hydrogen atom or a substituent. At least one of Rg, Rh, Ri and Rj represents a 6-membered aromatic heterocycle, and the 6-membered aromatic heterocycle may be fused. L ₂ represents a single bond, an aromatic hydrocarbon ring, an aromatic heterocycle or an alkyl group. ]

In the general formula (4), the substituents represented by Rg, Rh, Ri and Rj are the same as the substituents represented by Ra, Rb and Rc in the general formula (2). Further, the aromatic heterocycle having at least one of Rg, Rh, Ri and Rj having 6 members is the same as that mentioned in A1 and A2 of the general formula (1).
The aromatic hydrocarbon ring, aromatic heterocycle, and alkyl group represented by L ₂ are the same as those listed in L of the general formula (1), respectively.

［一般式（５）中、Ａｒは、カルバゾール、ジベンゾフラン、アザジベンゾフラン、ジベンゾチオフェン、アザジベンゾチオフェン、アザカルバゾール、ナフタレン、アントラセン、フェナンスレン又はフルオレンを表す。Ｒｋは、水素原子又は置換基を表す。Ｒｋのうち少なくとも二つが、６員の芳香族複素環を表し、この６員の芳香族複素環は縮環してもよい。ｎ３は２以上を表す。］ <Compound having a structure represented by the general formula (5)>

[In general formula (5), Ar represents carbazole, dibenzofuran, azadibenzofuran, dibenzothiophene, azadibenzothiophene, azacarbazole, naphthalene, anthracene, phenanthrene or fluorene. Rk represents a hydrogen atom or a substituent. At least two of Rk represent a 6-membered aromatic heterocycle, and the 6-membered aromatic heterocycle may be fused. n3 represents 2 or more. ]

In the general formula (5), the substituent represented by Rk is the same as the substituent represented by Ra, Rb and Rc in the general formula (2). The 6-membered aromatic heterocycle represented by Rk is the same as that given in A1 and A2 of the general formula (1).

［一般式（６）中、Ｙ_１及びＹ_２は、Ｏ、Ｓ、Ｎ−Ｒ_１を表す。Ｘ_１〜Ｘ_１６は、Ｃ−Ｒ_２又はＮを表す。Ｘ_１〜Ｘ_１６のうち少なくとも二つは、Ｎを表す。Ｌ_１は、単結合、芳香族炭化水素環、芳香族複素環又はアルキル基を表す。Ｒ_１及びＲ_２は、芳香族炭化水素環、芳香族複素環、アルキル基を表す。］ <Compound having a structure represented by the general formula (6)>

[In the general formula (6), Y ₁ and Y ₂ represent O, S, and N-R ₁ . X _{1 to} X ₁₆ represent _{CR 2} or N. At least two of _{X 1 to} X _{16 represent N.} L ₁ represents a single bond, an aromatic hydrocarbon ring, an aromatic heterocycle or an alkyl group. R ₁ and R ₂ represent an aromatic hydrocarbon ring, an aromatic heterocycle, and an alkyl group. ]

In the general formula (6), the _{aromatic hydrocarbon ring, the aromatic heterocycle, and the alkyl group represented by L 1} are the same as those listed in L of the general formula (1), respectively.

Examples of the compounds having the structures represented by the general formulas (2) to (6) are listed below, but the present invention is not limited thereto.

[Structure of organic EL element]
The organic EL element 110 shown in FIG. 2 includes an anode 111, a first light emitting layer 119, an intermediate connector layer 113, a second light emitting layer 123, and a cathode 115. Then, each of these layers is laminated and formed on the support substrate 116. Details of each of these configurations will be described later.

In the organic EL element 110, the anode 111 is formed on the support substrate 116, and the first light emitting unit 112 having the first light emitting layer 119 is formed on the anode 111. Further, an intermediate connector layer 113 is formed on the first light emitting unit 112, and a second light emitting unit 114 having a second light emitting layer 123 is formed on the intermediate connector layer 113. Further, a cathode 115 is formed on the second light emitting unit 114.

The organic EL element 110 has a so-called bottom emission type configuration in which the anode 111 is composed of a transparent electrode, the cathode 115 functions as a reflective electrode, and light is taken out from the support substrate 116 side.
Further, it is a so-called tandem type configuration in which the first light emitting unit 112 and the second light emitting unit 114 are laminated via the intermediate connector layer 113.

As a configuration other than the organic EL element 110, the anode 111 is composed of a reflective electrode, the cathode 115 functions as a transparent electrode, and light is taken out from the cathode 115 side, so-called top emission type, or the anode 111 is transparent. It may be a transparent type structure composed of electrodes, having a structure in which the cathode 115 functions as a transparent electrode, and extracting light from the support substrate 116 side and the cathode 115 side.

The first light emitting unit 112 and the second light emitting unit 114 have at least one light emitting layer or the like containing a light emitting organic material.

[Details of organic EL element configuration]
Hereinafter, the anode 111 of the organic EL element 110 shown in FIG. 2, the first light emitting unit 112 having the first light emitting layer 119, the intermediate connector layer 113, the second light emitting unit 114 having the second light emitting layer 123, and the cathode 115. Details of each configuration and the configuration of the support substrate 116 provided with the organic EL element 110 will be described.
It should be noted that each configuration of the organic EL element described below is an example for explaining the embodiment, and other configurations can be appropriately applied to the extent that the above-mentioned organic EL element can be configured. ..

<Intermediate connector layer>
In the organic EL element of the present invention, an intermediate connector layer is provided between the first light emitting layer provided in the first light emitting unit and the second light emitting layer provided in the second light emitting unit.
Then, the intermediate connector layer contains the alkali metal or alkaline earth metal, and the intermediate connector layer (specifically, the charge generation layer) or between the intermediate connector layer and the first light emitting layer. (Specifically, the first electron transport layer) contains a compound having a structure represented by the general formula (1).
The intermediate connector layer may contain a compound other than an alkali metal, an alkaline earth metal, or a compound having a structure represented by the general formula (1).

The intermediate connector layer is a layer having an interface with an organic compound layer that electrically connects a plurality of light emitting units in series in an electric field.

As the intermediate connector layer, an organic compound or an inorganic compound can be used alone or in combination of two or more.
The intermediate connector layer is formed of at least one layer or more, but is preferably composed of two or more layers, and particularly preferably includes one or both of a p-type semiconductor layer and an n-type semiconductor layer. Further, it may be a bipolar layer capable of generating and transporting holes and electrons inside the layer by an external electric field. Further, metals, metal oxides, alloys thereof and the like that can be used as ordinary electrode materials can be preferably used.
As described above, the intermediate connector layer can be configured as a charge generation layer having a function of injecting electrons into one light emitting unit and a function of injecting holes into the other light emitting unit.

Further, the intermediate connector layer can be formed by using the same materials as the anode and the cathode. Further, the intermediate connector layer can be formed by using a material having a lower conductivity than that of the anode and the cathode.

In the intermediate connector layer, as a layer having a function of injecting electrons, for example, an insulator such as lithium oxide, lithium fluoride, or cesium carbonate or a semiconductor can be used. Alternatively, a material obtained by adding an electron-donating substance to a substance having a high electron-transporting property can also be used.

Organic compounds include nanocarbon materials, organic metal complex compounds that function as organic semiconductor materials (organic acceptors, organic donors), organic salts, aromatic hydrocarbon compounds and their derivatives, heteroaromatic hydrocarbon compounds, and derivatives thereof. And so on.
Examples of the inorganic compound include metals, inorganic oxides, and inorganic salts.

Examples of substances having high electron transport properties include tris (4-methyl-8-quinolinolato) aluminum (abbreviation: Almq ₃ ), bis (10-hydroxybenzo [h] quinolinato) berylium (abbreviation: BeBq ₂ ), and bis (abbreviation: BeBq 2). A metal complex having a quinoline skeleton or a benzoquinoline skeleton such as 2-methyl-8-quinolinolato) (4-phenylphenolato) aluminum (abbreviation: BAlq) can be used.
In addition, bis [2- (2-hydroxyphenyl) benzoxazolato] zinc (abbreviation: Zn (BOX) ₂ ), bis [2- (2-hydroxyphenyl) benzothiazolate] zinc (abbreviation: Zn (abbreviation: Zn) A metal complex having an oxazole-based or thiazole-based ligand such as BTZ) _{2) can also be used.}

In addition to the metal complex, 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis [5- (P-tert-butylphenyl) -1,3,4-oxadiazole-2-yl] benzene (abbreviation: OXD-7), 3- (4-biphenylyl) -4-phenyl-5- (4-tert) -Butylphenyl) -1,2,4-triazole (abbreviation: TAZ), vasocuproin (abbreviation: BCP) and the like can also be used.

The above-mentioned substance having high electron transportability mainly has ^{an electron mobility of 10-6} cm ² / V · s or more. It is also possible to use a substance other than the above as long as it is a substance having a higher electron transport property than holes.

By adding an electron donating substance to a substance having a high electron transporting property, the electron injecting property can be enhanced. Therefore, the drive voltage of the light emitting element can be reduced. As the electron donating substance, an alkali metal, an alkaline earth metal, a rare earth metal, a metal belonging to Group 13 in the periodic table of elements, an oxide thereof, or a carbonate thereof can be used. Specifically, it is preferable to use lithium (Li), cesium (Cs), magnesium (Mg), calcium (Ca), ytterbium (Yb), indium (In), lithium oxide, cesium carbonate and the like. Moreover, you may use an organic compound such as tetrathianaphthalcene as a donor substance.

Further, as a layer having a function of injecting holes in the intermediate connector layer, for example, a semiconductor or an insulator such as molybdenum oxide, vanadium oxide, rhenium oxide, or ruthenium oxide can be used. Alternatively, a material obtained by adding an electron-accepting substance to a substance having a high hole transport property can be used. Alternatively, a layer made of an electron-accepting substance may be used.

Examples of substances having high hole transport properties include 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (abbreviation: NPB or α-NPD) and N, N'-bis (abbreviation: NPB or α-NPD). 3-Methylphenyl) -N, N'-diphenyl- [1,1'-biphenyl] -4,4'-diamine (abbreviation: TPD), 4,4', 4 "-tris (N, N-diphenylamino) ) Triphenylamine (abbreviation: TDATA), 4,4', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] Triphenylamine (abbreviation: MTDATA) and other aromatic amine compounds Can be used.

The above-mentioned substance having high hole transportability is mainly a substance having a hole mobility of ^10-6 cm ^{2 / V · s or more.} However, a substance other than the above may be used as long as it is a substance having a higher hole transport property than electrons. Moreover, the above-mentioned host material may be used.

By adding an electron-accepting substance to a substance having a high hole-transporting property, the hole-injecting property can be enhanced. Therefore, the drive voltage of the light emitting element can be reduced. As the electron accepting substance, 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil and the like can be used. In addition, transition metal oxides can be used. Further, oxides of metals belonging to Groups 4 to 8 in the Periodic Table of the Elements can be used. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, and renium oxide are preferable because they have high electron acceptability. Of these, molybdenum oxide is particularly preferable because it is stable in the atmosphere, has low hygroscopicity, and is easy to handle.

Further, by using one or both of a structure in which an electron-accepting substance is added to a substance having a high hole-transporting property and a structure in which an electron-accepting substance is added to a substance having a high electron-transporting property. Even when the intermediate connector layer is thickened, it is possible to suppress an increase in the drive voltage. Therefore, by thickening the intermediate connector layer, it is possible to prevent a short circuit due to a minute foreign substance, an impact, or the like, and it is possible to obtain a highly reliable light emitting element without increasing the driving voltage.

In the intermediate connector layer, another layer may be introduced between the layer having the function of injecting holes and the layer having the function of injecting electrons, if necessary. For example, a conductive layer such as ITO or an electronic relay layer may be provided. The electron relay layer has a function of reducing a voltage loss that occurs between a layer having a function of injecting holes and a layer having a function of injecting electrons. Specifically, it is preferable to use a material having a LUMO level of about −5.0 eV or more, and more preferably to use a material having a LUMO level of −5.0 eV or more and −3.0 eV or less. For example, 3,4,9,10-perylenetetracarboxylic dianhydride (abbreviation: PTCDA), 3,4,9,10-perylenetetracarboxylic bisbenzoimidazole (abbreviation: PTCBI) and the like can be used.

<Light emitting unit>
As shown in FIG. 2, the first light emitting unit 112 is provided between the anode 111 and the intermediate connector layer 113, and the second light emitting unit 112 is provided between the intermediate connector layer 113 and the cathode 115.
The first light emitting unit 112 includes at least a first light emitting layer 119 containing a light emitting organic material, and the second light emitting unit 114 includes at least a second light emitting layer 123 containing a light emitting organic material. In the first light emitting unit 112 and the second light emitting unit 114, between the first light emitting layer 119 and the anode 111, between the first light emitting layer 119 and the intermediate connector layer 113, and between the intermediate connector layer 113 and the cathode 115. Other layers may be provided between and.

Hereinafter, the first light emitting unit 112 and the second light emitting unit 114 are collectively described as a light emitting unit, and the first light emitting layer 119 provided in the first light emitting unit 112 and the second light emitting unit provided in the second light emitting unit 114 are provided. The layer 123 will be described as a light emitting layer as a whole.

Typical element configurations of the light emitting unit include, but are not limited to, the following configurations.
(1) Hole injection transport layer / light emitting layer / electron injection transport layer (2) hole injection transport layer / light emitting layer / hole blocking layer / electron injection transport layer (3) hole injection transport layer / electron blocking layer / Light emitting layer / hole blocking layer / electron injection transport layer (4) hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer (5) hole injection layer / hole transport layer / light emitting layer / Hole blocking layer / Electron transporting layer / Electron injection layer (6) Hole injection layer / Hole transporting layer / Electron blocking layer / Light emitting layer / Hole blocking layer / Electron transporting layer / Electron injection layer (7) Hole Injection layer / hole transport layer / light emitting layer / electron transport layer

Of the above configurations, the configuration (7) is particularly preferable, and as a specific configuration of the tandem type organic EL element using this configuration, as shown in FIG. 2, the anode 111 / first light emitting unit (first positive light emitting unit) Hole injection layer 117 / first hole transport layer 118 / first light emitting layer 119 / first electron transport layer 120) 112 / intermediate connector layer 113 / second light emitting unit (second hole injection layer 121 / second hole) Examples thereof include a transport layer 122 / a second light emitting layer 123 / a second electron transport layer 124) 114 / a cathode 115.
Further, as a configuration of a tandem type organic EL element other than the above configuration, although not shown, the anode / first light emitting unit (first hole injection layer / first hole transport layer / first light emitting layer / first electron transport). Layer / 1st electron injection layer) / Intermediate connector layer / 2nd light emitting unit (2nd hole injection layer / 2nd hole transport layer / 2nd light emitting layer / 2nd electron transport layer / 2nd electron injection layer) / Examples include a cathode.
In the above configuration, the light emitting layer is composed of a single layer or a plurality of layers.
The electron transport layer is a layer having a function of transporting electrons. The electron transport layer also includes an electron injection layer and a hole blocking layer in a broad sense. Further, the electron transport layer may be composed of a plurality of layers.
The hole transport layer is a layer having a function of transporting holes. The hole transport layer also includes a hole injection layer and an electron blocking layer in a broad sense. Further, the hole transport layer may be composed of a plurality of layers.

A phosphorescent light emitting material and a fluorescent light emitting material may be mixed in the light emitting layer in the light emitting unit, but it is preferably composed of only the phosphorescent light emitting material or the fluorescent light emitting material. The fluorescent light emitting layer and the phosphorescent light emitting layer are preferably host-dopant type light emitting layers. Further, the light emitting dopant contained in the light emitting layer may be contained at a uniform concentration with respect to the film thickness direction of the light emitting layer, or may have a concentration distribution.

When a plurality of light emitting units are provided in the organic EL element, light emitting units having different configurations can be used in combination, but it is preferable that the light emitting units have the same layer configuration except for the light emitting layer. Further, it is preferable that each light emitting unit has the same number of light emitting layers. As a result, the number of materials used can be reduced, which has advantages in terms of production such as cost and quality control. Further, in the case of the vapor deposition process, there is an advantage in terms of production efficiency such that the film forming chamber can be easily shared by each light emitting unit.

Further, when light emitting units exhibiting different emission colors are laminated to obtain white light emission, it is preferable that these light emitting units have a complementary color relationship with each other. For example, by providing a blue light emitting unit and a light emitting unit exhibiting a complementary color of yellowish green, yellow, or orange, an organic EL element exhibiting white light emission can be obtained. The "complementary color" relationship refers to the relationship between colors that become achromatic when mixed. That is, white light emission can be obtained by mixing the light emission of a substance that emits a color having a complementary color relationship.

In addition to the blue light emitting layer, a layer exhibiting green and red light emitting colors is provided in any of the light emitting units because high quality white light emission can be obtained and it is easy to adjust the chromaticity in a wider range. It is preferable to have. Further, the light emitting unit may be provided with a light emitting layer in which blue, green, and red light emitting materials are mixed in one light emitting layer to exhibit white light emission.

The emission colors of organic EL elements and compounds are shown in Figure 4.16 on page 108 of the "New Color Science Handbook" (edited by the Japan Color Society, Tokyo University Press, 1985), and the spectral radiance meter CS-2000 (Konica Minolta). The result measured by (manufactured by) is applied to the CIE chromaticity coordinates to determine.
Deviation _{D uv} from a blackbody radiation locus of light color, correlated color temperature is in the range of 2500～7500K, shall the light included in the scope of -20 to + 20 is referred to as white light. Definition of Duv (= 1000d _uv) is JIS Z 8725: According to the 1999 "distribution temperature and color temperature and correlated color temperature measurement method of the light source."

The film thickness of each layer included in each light emitting unit is not particularly limited. From the viewpoint of the homogeneity of the film to be formed, the prevention of applying an unnecessary high voltage during light emission, and the improvement of the stability of the light emission color with respect to the drive current, it is preferable to adjust the temperature within the range of 5 to 200 nm. , More preferably, it is adjusted in the range of 10 to 100 nm or less.

The method for forming the individual layers included in each light emitting unit is not particularly limited as long as it can form a thin film, and for example, a vapor deposition method, a sputtering method, a wet process (spin coating method, a casting method, an inkjet method, an LB). Method, spray method, printing method, slot type coater method) and the like. Of these, the vacuum deposition method, spin coating method, inkjet method, printing method, and slot type coater method are particularly preferable from the viewpoints that damage to the lower layer is small and a homogeneous film without pinholes can be easily obtained.

Hereinafter, each constituent layer of the light emitting unit will be described.

《Light emitting layer》
The light emitting layer according to the present invention is a layer in which electrons and holes injected from an electrode or an electron transporting layer and a hole transporting layer recombine to emit light, and the light emitting portion is in the layer of the light emitting layer. May also be the interface between the light emitting layer and the adjacent layer.
The total thickness of the light emitting layer is not particularly limited, but from the viewpoint of film homogeneity, prevention of applying an unnecessary high voltage during light emission, and improvement of emission color stability with respect to drive current. It is preferably adjusted to the range of 2 nm to 5 μm, more preferably to the range of 2 to 200 nm, and particularly preferably to the range of 5 to 100 nm.

The light emitting layer is produced by using, for example, a vacuum deposition method or a wet method (also referred to as a wet process, for example, a spin coating method, a casting method, a die coating method, a blade coating method, or a roll coating method) using a light emitting dopant or a host compound described later. It can be formed by forming a film by a method, an inkjet method, a printing method, a spray coating method, a curtain coating method, an LB method (Langmuir Bloodgett method can be mentioned) or the like.
The light emitting layer of the organic EL element of the present invention preferably contains a light emitting dopant (phosphorescent light emitting dopant, fluorescent light emitting dopant, etc.) compound and a host compound.

(1) Luminous Dopant A luminescent dopant (a luminescent dopant, a dopant compound, or simply a dopant) will be described.
Examples of the luminescent dopant include a fluorescent dopant (also referred to as a fluorescent dopant, a fluorescent compound, or a fluorescent compound), a phosphorescent dopant (also referred to as a phosphorescent dopant, a phosphorescent compound, a phosphorescent compound, or the like). .) Can be used.

(1.1) Phosphorescent dopant Phosphorescent dopant is a compound in which light emission from the excited triplet is observed, specifically, a compound that emits phosphorescent light at room temperature (25 ° C.), and has a phosphorescent quantum yield. Is defined as a compound of 0.01 or more at 25 ° C., with a preferred phosphorescent quantum yield of 0.1 or more.
The phosphorus photon yield can be measured by the method described on page 398 (1992 edition, Maruzen) of Spectroscopy II of the 4th edition Experimental Chemistry Course 7. The phosphorescence quantum yield in a solution can be measured using various solvents, but the phosphorescence dopant used in the present invention achieves the above phosphorescence quantum yield (0.01 or more) in any of any solvents. Just do it.

There are two types of light emission of the phosphorescent dopant in principle. One is that carrier recombination occurs on the host compound to which the carrier is transported to generate an excited state of the light emitting host compound, and this energy is used as the phosphorescent dopant. It is an energy transfer type that obtains light emission from a phosphorescent dopant by moving it. The other is a carrier trap type in which the phosphorescent dopant serves as a carrier trap, carriers are recombined on the phosphorescent dopant, and light emission from the phosphorescent dopant is obtained. In either case, the excited state energy of the phosphorescent dopant is required to be lower than the excited state energy of the host compound.

(1.2) Fluorescent dopant Examples of the fluorescent dopant include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, and pyrylium dyes. Examples thereof include perylene dyes, fluorescein dyes, polythiophene dyes, rare earth complex phosphors and the like, and compounds having a high fluorescence quantum yield represented by laser dyes.

(Combined use with conventionally known dopants)
Further, the light emitting dopant used in the present invention may be used in combination with a plurality of types of compounds, may be used in combination with phosphorescent dopants having different structures, or may be used in combination with phosphorescent dopant and fluorescent dopant.
Here, as the light emitting dopant, a conventionally known compound described in International Publication No. 2013/061850 can be preferably used, but the present invention is not limited thereto.

(2) Host Compound The host compound (also referred to as a light emitting host or a light emitting host compound) that can be used in the present invention has a mass ratio of 20% or more in the light emitting layer among the compounds contained in the light emitting layer. It is defined as a compound having a phosphorescent quantum yield of less than 0.1 at room temperature (25 ° C.). Preferably, the phosphorus photon yield is less than 0.01. Further, among the compounds contained in the light emitting layer, the mass ratio in the layer is preferably 20% or more.

The host compound that can be used in the present invention is not particularly limited, and compounds conventionally used in organic EL devices can be used. Typically, carbazole derivatives, triarylamine derivatives, aromatic derivatives, nitrogen-containing heterocyclic compounds, thiophene derivatives, furan derivatives, oligoarylene compounds and the like have a basic skeleton, or carboline derivatives and diazacarbazole derivatives (here). The diazacarbazole derivative refers to a derivative in which at least one carbon atom of the hydrocarbon ring constituting the carboline ring of the carboline derivative is replaced with a nitrogen atom.)

As the known host compound that can be used in the present invention, a compound having a hole transporting ability and an electron transporting ability, preventing a long wavelength of light emission, and having a high Tg (glass transition temperature) is preferable.
Further, in the present invention, conventionally known host compounds may be used alone or in combination of two or more. By using a plurality of types of host compounds, it is possible to adjust the movement of electric charges, and it is possible to improve the efficiency of the organic EL device. Further, by using a plurality of conventionally known compounds, it is possible to mix different luminescences, and thereby an arbitrary luminescence color can be obtained.

Further, the host compound used in the present invention may be a low molecular weight compound, a high molecular weight compound having a repeating unit, or a low molecular weight compound having a polymerizable group such as a vinyl group or an epoxy group (polymerizable host compound). Often, one or more such compounds may be used.

Specific examples of known host compounds include the compounds described in the following documents.
JP 2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357977, 2002-334786, 2002-8860, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579, 2002. 2002-105445, 2002-343568, 2002-141173, 2002-352957, 2002-203683, 2002-363227, 2002-231453, 2003 -3165, 2002-234888, 2003-27048, 2002-255934, 2002-260861, 2002-280183, 2002-299060, 2002- 302516, 2002-305083, 2002-305084, 2002-308837 and the like.

"cathode"
As the cathode, a metal having a small work function (4 eV or less) (referred to as an electron-injectable metal), an alloy, an electrically conductive compound, or a mixture thereof as an electrode material is also used. Specific examples of such electrode materials 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 ) Examples include mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the viewpoint of electron injectability and durability against oxidation and the like, a mixture of an electron injectable metal and a second metal which is a stable metal having a larger work function value than this, for example, a magnesium / silver mixture. A magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, a lithium / aluminum mixture, aluminum and the like are suitable.
In particular, it is preferably composed mainly of silver, and the alloy containing silver as a main component is, for example, silver magnesium (AgMg), silver copper (AgCu), silver palladium (AgPd), silver palladium copper (AgPdCu). , Silver indium (AgIn) and the like.
The "main component" in the present invention means that the film or layer contains 50% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more. ..

If necessary, the cathode using an alloy containing silver as a main component may be divided into a plurality of layers and laminated.
The film thickness of the cathode is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm. When an alloy containing silver as a main component is used, the film thickness is preferably 15 nm or less, and preferably in the range of 4 to 12 nm. When the film thickness is within the range, the component of light absorbed or reflected by the film can be reduced, the light transmittance can be maintained, and the conductivity of the layer can be ensured.

As described above, when the cathode contains silver as a main component, it is preferably adjacent to the organic functional layer containing the compound having the structure represented by the general formula (1).
The organic functional layer containing the compound having the structure represented by the general formula (1) is preferably adjacent to the cathode, and even when the cathode is formed on the organic functional layer, it is placed on the cathode. The organic functional layer may be formed. Further, the cathode may be formed on the organic functional layer, the organic functional layer may be further formed on the cathode, and the cathode may be sandwiched between the two organic functional layers.

When a silver-based cathode is formed on the upper part of the organic functional layer, a compound having a structure represented by the general formula (1) in which silver atoms constituting the cathode are contained in the metal affinity layer. By interacting with each other, the diffusion distance of silver atoms on the surface of the organic functional layer is reduced, and silver aggregation (migration) at specific points can be suppressed.
That is, the silver atom first forms a two-dimensional nucleus on the surface of the organic functional layer having an atom having an affinity for the silver atom, and then forms a two-dimensional single crystal layer around it, which is a layered growth type (a layered growth type). The film is formed by the film growth of Frank-van der Merwe (FM type).

In general, an island-like growth type (Volumer) in which silver atoms attached on the surface of an organic functional layer are bonded while diffusing on the surface to form a three-dimensional nucleus and grow in a three-dimensional island shape. -Weber: VW type) film growth is considered to facilitate island-like film formation.
However, in the present invention, it is presumed that the compound having the structure represented by the general formula (1) contained in the organic functional layer suppresses the island-like growth and promotes the layered growth.
Therefore, a cathode having a thin film thickness but a uniform film thickness can be obtained. As a result, it is possible to obtain a transparent electrode in which conductivity is ensured while maintaining light transmission due to its thin film thickness.

Further, when an organic functional layer is formed on the upper part of the cathode, the silver atoms constituting the cathode interact with the atoms having an affinity for the silver atoms contained in the organic functional layer, and the motility is suppressed. it is conceivable that. As a result, diffused reflection can be suppressed by improving the surface smoothness of the cathode, and the light transmittance can be improved.
It is speculated that such interaction suppressed changes in the film quality of the cathode in response to physical stimuli such as heat and temperature, and improved durability.

The cathode can be produced by forming a thin film by a method such as vapor deposition or sputtering on a general electrode material in addition to an alloy containing silver as a main component. The sheet resistance value as a cathode is several hundred Ω / sq. The following is preferable, and 25Ω or less is particularly preferable.
In order to transmit the emitted light, it is preferable that either the anode or the cathode of the organic EL element is transparent or translucent to improve the emission brightness, and the light transmittance of the cathode is 50% or more. preferable.
Further, a transparent or translucent cathode can be produced by producing the above metal on the cathode having a film thickness of 1 to 20 nm and then producing a conductive transparent material described later in the description of the anode on the cathode. By applying this, it is possible to manufacture an element in which both the anode and the cathode are transparent.

《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons.
The present invention is characterized in that the first electron transport layer, which is a layer between the intermediate connector layer and the first light emitting layer, contains a compound having a structure represented by the general formula (1). ..
In a broad sense, the electron injection layer and the hole blocking layer are also included in the electron transport layer. The electron transport layer may be provided with a single layer or a plurality of layers. Further, an electron injection transport layer containing a material contained in the electron injection layer described later may be provided.
The electron transport layer may have a function of transferring electrons injected from the cathode to the light emitting layer, and as a constituent material of the electron transport layer, any conventionally known compound may be selected and used in combination. Is also possible.

Examples of conventionally known materials used for the electron transport layer (hereinafter referred to as electron transport materials) include polycyclic aromatic hydrocarbons such as nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyrandioxide derivatives, and naphthalene perylene. Heterocyclic tetracarboxylic acid anhydride, carbodiimide, fleolenilidene methane derivative, anthracinodimethane and antron derivative, oxadiazole derivative, carbolin derivative, or carbon atom of the hydrocarbon ring constituting the carbolin ring of the carbolin derivative. Examples thereof include a derivative having a ring structure in which at least one is substituted with a nitrogen atom, a hexaazatriphenylene derivative and the like.
Further, among the above oxadiazole derivatives, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is replaced with a sulfur atom, and a quinoxalin derivative having a quinoxalin ring known as an electron-withdrawing group can also be used as an electron transport material.
It is also possible to use a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain.

Also, metal complexes of 8-quinolinol derivatives, such as tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum, tris (2-methyl-8-quinolinol). Aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), etc., and the central metal of these metal complexes are placed in In, Mg, Cu, Ca, Sn, Ga or Pb. The replaced metal complex can also be used as an electron transporting material.
In addition, metal-free or metal phthalocyanine, or those whose terminals are substituted with an alkyl group, a sulfonic acid group, or the like can also be used as an electron transport material.
Inorganic semiconductors such as n-type-Si and n-type-SiC can also be used as electron transport materials.

The electron transport layer uses an electron transport material, for example, a vacuum deposition method, a wet method (also referred to as a wet process, for example, a spin coating method, a casting method, a die coating method, a blade coating method, a roll coating method, an inkjet method, a printing method, or a spray method. It is preferably formed by thinning by a coating method, a curtain coating method, an LB method (Langmuir Bloodgett method or the like can be mentioned) or the like.

The thickness of the electron transport layer is not particularly limited, but is usually about 5 to 5000 nm, preferably 5 to 200 nm. The electron transport layer may have a one-layer structure composed of one or more of the above materials.
Further, an n-type dopant such as a metal compound such as a metal complex or a metal halide may be doped and used.

As an example of a conventionally known electron transport material preferably used for forming an electron transport layer of the organic EL device of the present invention, the compound described in International Publication No. 2013/061850 can be preferably used. Not limited to.

<< Injection layer: Electron injection layer (cathode buffer layer), hole injection layer >>
The injection layer may be provided as necessary, and may have an electron injection layer and a hole injection layer, and may be present between the anode and the light emitting layer or the hole transport layer, and between the cathode and the light emitting layer or the electron transport layer. ..
The injection layer is a layer provided between the electrode and the organic functional layer in order to reduce the driving voltage and improve the emission brightness. It is described in detail in Volume 2, Chapter 2, "Electrode Materials" (pages 123 to 166) of "Issued)", and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).

The details of the anode buffer layer (hole injection layer) are described in JP-A-9-45479, 9-2660062, 8-288609, etc., and as a specific example, copper phthalocyanine is used. Representative phthalocyanine buffer layer, hexaazatriphenylene derivative buffer layer as described in Japanese Patent Application Laid-Open No. 2003-591432, JP-A-2006-135145, etc., oxide buffer layer typified by vanadium oxide, amorphous carbon. Examples thereof include a buffer layer, a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) and polythiophene, and an orthometallated complex layer typified by a tris (2-phenylpyridine) iridium complex.

The details of the cathode buffer layer (electron injection layer) are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like, and specifically, strontium, aluminum, and the like. Metal buffer layer represented by, lithium metal fluoride, alkali metal compound buffer layer represented by potassium fluoride, magnesium fluoride, alkaline earth metal compound buffer layer represented by cesium fluoride, represented by aluminum oxide. An oxide buffer layer and the like can be mentioned. The buffer layer (injection layer) is preferably a very thin film, and the film thickness is preferably in the range of 0.1 nm to 5 μm, although it depends on the material.

<< Blocking layer: Hole blocking layer, Electron blocking layer >>
The blocking layer is provided as needed in addition to the basic constituent layer of the organic compound thin film as described above. For example, it is described in JP-A-11-204258, No. 11-204359, and page 237 of "Organic EL Element and Its Industrialization Frontline (November 30, 1998, published by NTS Co., Ltd.)". There is a hole blocking (hole block) layer.

The hole blocking layer has the function of an electron transporting layer in a broad sense, and is made of a hole blocking material having a function of transporting electrons and a significantly small ability to transport holes. It is possible to improve the recombination probability of electrons and holes by blocking the above.
In addition, the above-mentioned structure of the electron transport layer can be used as a hole blocking layer, if necessary.
The hole blocking layer of the organic EL device of the present invention is preferably provided adjacent to the light emitting layer.
In the hole blocking layer, the carbazole derivative, the carboline derivative, and the diazacarbazole derivative mentioned as the above-mentioned host compounds (here, the diazacarbazole derivative is a nitrogen atom in any one of the carbon atoms constituting the carboline ring. It is preferable to contain (meaning the one replaced with).

On the other hand, the electron blocking layer has the function of a hole transporting layer in a broad sense, and is made of a material having a function of transporting holes and an extremely small ability to transport electrons, and transports electrons while transporting electrons. By blocking, the recombination probability of electrons and holes can be improved.
Further, the structure of the hole transport layer described later can be used as an electron blocking layer as needed. The layer thickness of the hole blocking layer and the electron transporting layer according to the present invention is preferably in the range of 3 to 100 nm, and more preferably in the range of 5 to 30 nm.

《Hole transport layer》
The hole transport layer is made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer may be provided as a single layer or a plurality of layers.
The hole transporting material has either injection or transport of holes or an electron barrier property, and may be either an organic substance or an inorganic substance. For example, triazole derivatives, oxaziazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples thereof include stillben derivatives, silazane derivatives, aniline-based copolymers, conductive polymer oligomers, and particularly thiophene oligomers.
Further, azatriphenylene derivatives as described in JP-A-2003-591432 and JP-A-2006-135145 can also be used as the hole transport material in the same manner.

As the hole transporting material, the above-mentioned ones can be used, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.
Typical examples of aromatic tertiary amine compounds and styrylamine compounds are 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-diphenylaminostylben; N-phenylcarbazole, as well as the two condensed aromatics described in US Pat. No. 5,061569. Those having a ring in the molecule, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), triphenylamine described in JP-A-4-308688. Examples thereof include 4,4', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine (MTDATA) in which units are linked in a three-star burst type.

Further, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.
Inorganic compounds such as p-type-Si and p-type-SiC can also be used as hole injection materials and hole transport materials.

Further, Japanese Patent Application Laid-Open No. 11-251067, J. Am. Hung et. al. So-called p-type hole transporting materials as described in the literature (Applied Physics Letters 80 (2002), p. 139) can also be used. In the present invention, it is preferable to use these materials because a light emitting device with higher efficiency can be obtained.

The hole transport layer can be formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an inkjet method, or an LB method. can.
The thickness of the hole transport layer is not particularly limited, but is usually in the range of about 5 nm to 5 μm, preferably in the range of 5 to 200 nm. The hole transport layer may have a one-layer structure composed of one or more of the above materials.

It is also possible to use a hole transport layer having a high p property doped with impurities. Examples thereof include JP-A-4-297076, JP-A-2000-196140, and JP-A-2001-102175. Apple. Phys. , 95, 5773 (2004) and the like.
In the present invention, it is preferable to use such a hole transport layer having a high p property because a device having lower power consumption can be manufactured.

"anode"
As the anode in the organic EL element, a metal having a large work function (4 eV or more), an alloy, an electrically conductive compound, or a mixture thereof as an electrode material is preferably used. Specific examples of such an electrode material include metals such as Au and conductive transparent materials such as _{CuI, ITO, SnO 2, and ZnO.}
Further, a material such as IDIXO (In ₂ O _3- ZnO) which is amorphous and can produce a transparent conductive film may be used. For the anode, a thin film may be formed by forming a thin film of these electrode materials by a method such as thin film deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when pattern accuracy is not required so much (about 100 μm or more). , The pattern may be formed through a mask having a desired shape during vapor deposition or sputtering of the electrode material.

Alternatively, when a coatable substance such as a conductive organic compound is used, a wet film forming method such as a printing method or a coating method can also be used. When emitting light from this anode, it is desirable to increase the light transmittance to more than 10%, and the sheet resistance value as the anode is several hundred Ω / sq. The following is preferable. Further, the film thickness depends on the material, but is usually selected in the range of 10 to 1000 nm, preferably 10 to 200 nm.

《Support board》
The types of support substrates (hereinafter, also referred to as substrates, substrates, substrates, supports, etc.) that can be used in the organic EL element of the present invention are not particularly limited, and are transparent. It may be opaque. When light is taken out from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable support substrate is a resin film capable of imparting flexibility to the organic EL element.

Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, and cellulose acetate propionate. CAP), cellulose acetate phthalate, cellulose esters such as cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones, polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylates, Arton (trade name: JSR) or Appel. Examples thereof include films such as cycloolefin resins (trade name: manufactured by Mitsui Kagaku Co., Ltd.).

A film of an inorganic substance, an organic substance, or a hybrid film of both of them may be formed on the surface of the resin film, and the water vapor permeability (25 ± 0.5 ° C.) measured by a method according to JIS K 7129-1992. it is preferable that the relative humidity of (90 ± 2)%) is less gas-barrier film 0.01g ^/ m 2 · 24h, more, oxygen permeability measured by the method based on JIS K 7126-1987 ^{There, 1 × 10 -3 mL / m} 2 · 24h · atm or less, the water vapor permeability is preferably ^{1 × 10 -5 g / m 2} · 24h or less high gas barrier film.

The material for forming the gas barrier layer may be any material that causes deterioration of the device such as moisture and oxygen but has a function of suppressing infiltration, and for example, silicon oxide, silicon dioxide, silicon nitride and the like can be used. .. Further, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and layers made of an organic material. The stacking order of the inorganic layer and the organic functional layer is not particularly limited, but it is preferable to stack the inorganic layer and the organic functional layer alternately a plurality of times.

The method for forming the gas barrier layer is not particularly limited, and for example, vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma weight. Although legal, plasma CVD method, laser CVD method, thermal CVD method, coating method and the like can be used, the atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.
Examples of the opaque support substrate include a metal plate such as aluminum and stainless steel, a film or opaque resin substrate, and a ceramic substrate.

The external extraction yield of the light emitted from the organic EL device of the present invention at room temperature is preferably 1% or more, more preferably 5% or more.
Here, the external extraction quantum yield (%) = the number of photons emitted to the outside of the organic EL element / the number of electrons passed through the organic EL element × 100.
Further, a hue improving filter such as a color filter may be used in combination, or a color conversion filter that converts the emission color from the organic EL element into multiple colors using a phosphor may be used in combination. When a color conversion filter is used, the λmax of light emission of the organic EL element is preferably 480 nm or less.

[Method for manufacturing organic EL elements]
As an example of a method for manufacturing an organic EL element, an anode / first light emitting unit (hole injection layer / hole transport layer / first light emitting layer / electron transport layer) / intermediate connector layer / second light emitting unit (hole injection layer) A method for manufacturing an element composed of / a hole transport layer / a first light emitting layer / an electron transport layer) / a cathode will be described.
First, a thin film made of a desired electrode substance, for example, an anode substance is formed on a suitable substrate so as to have a film thickness of 1 μm or less, preferably 10 to 200 nm, to prepare an anode.
Next, on top of this, the first light emitting unit (hole injection layer, hole transport layer, first light emitting layer, electron transport layer), the intermediate connector layer, and the second light emitting unit (hole injection layer, positive), which are element materials, are used. A thin film containing an organic compound such as a hole transport layer, a first light emitting layer, and an electron transport layer) is formed.

As a method for forming the thin film, for example, a thin film can be formed by a vacuum deposition method, a wet method (also referred to as a wet process) or the like.
Wet methods include spin coating method, casting method, die coating method, blade coating method, roll coating method, inkjet method, printing method, spray coating method, curtain coating method, LB method, etc., but a precise thin film can be formed. From the viewpoint of high productivity, a method having high suitability for the roll-to-roll method such as a die coating method, a roll coating method, an inkjet method, and a spray coating method is preferable. Further, a different film forming method may be applied to each layer.

Examples of the liquid medium for dissolving or dispersing an organic EL material such as a light emitting dopant used in the present invention include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, and halogenated hydrocarbons such as dichlorobenzene. Aromatic hydrocarbons such as toluene, xylene, mesitylene and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin and dodecane, and organic solvents such as dimethylformamide (DMF) and DMSO can be used.
Further, as a dispersion method, dispersion can be performed by a dispersion method such as ultrasonic waves, high shear force dispersion, or media dispersion.

After forming these layers, a thin film made of a cathode substance is formed on the thin film so as to have a film thickness in the range of 1 μm or less, preferably 50 to 200 nm, and a cathode is provided to obtain a desired organic EL device. ..
Further, in the reverse order, the cathode / second light emitting unit (electron transport layer / second light emitting layer / hole transport layer / hole injection layer) / intermediate connector layer / first light emitting unit (electron transport layer / first light emitting unit). It is also possible to prepare in the order of light emitting layer / hole transport layer / hole injection layer) / anode.
The organic EL device of the present invention is preferably manufactured from the hole injection layer to the cathode consistently by one vacuuming, but it may be taken out in the middle and a different film forming method may be applied. At that time, it is preferable to carry out the work in a dry inert gas atmosphere.

<Sealing>
Examples of the sealing means used in the present invention include a method of adhering a sealing member, an electrode, and a support substrate with an adhesive.
The sealing member may be arranged so as to cover the display area of the organic EL element, and may have an intaglio shape or a flat plate shape. Further, transparency and electrical insulation are not particularly limited.

Specific examples thereof include a glass plate, a polymer plate / film, and a metal plate / film. Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz.
Examples of the polymer plate include those formed of polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, polysulfone and the like.
Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium and tantalum.

In the present invention, a polymer film or a metal film can be preferably used because the device can be thinned.
Further, the polymer film is measured by the oxygen permeability measured by the method based on JIS K 7126-1987 is ^{1 × 10 -3 mL / m 2} · 24h · atm or less, in conformity with JIS K 7129-1992 method is water vapor transmission rate (25 ± 0.5 ° C., relative humidity (90 ± 2)%) is preferably one of the following ^{1 × 10 -3 g / m 2} · 24h.
Sandblasting, chemical etching, etc. are used to process the sealing member into a concave shape.

Specific examples of the adhesive include acrylic acid-based oligomers, photocurable and thermosetting adhesives having a reactive vinyl group of methacrylic acid-based oligomers, and moisture-curable adhesives such as 2-cyanoacrylic acid ester. be able to. In addition, heat and chemical curing type (two-component mixture) such as epoxy type can be mentioned. Further, hot melt type polyamide, polyester and polyolefin can be mentioned. In addition, a cation-curable type ultraviolet-curable epoxy resin adhesive can be mentioned.

Since the organic EL element may be deteriorated by heat treatment, it is preferable that the organic EL element can be adhesively cured from room temperature to 80 ° C. Further, the desiccant may be dispersed in the adhesive. A commercially available dispenser may be used to apply the adhesive to the sealing portion, or printing may be performed as in screen printing.

Further, it is also possible to preferably cover the electrode and the light emitting unit on the outside of the electrode on the side facing the support substrate with the light emitting unit sandwiched therein, and form a layer of an inorganic substance or an organic substance in contact with the support substrate to form a sealing film. .. In this case, the material for forming the film may be any material that causes deterioration of the element such as moisture and oxygen but has a function of suppressing infiltration, and for example, silicon oxide, silicon dioxide, silicon nitride or the like may be used. can.
Further, in order to improve the fragility of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of an organic material. The method for forming these films is not particularly limited, and for example, vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma. A polymerization method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method and the like can be used.

In the gas phase and liquid phase, an inert gas such as nitrogen or argon or an inert liquid such as fluorinated hydrocarbon or silicone oil may be injected into the gap between the sealing member and the display region of the organic EL element. preferable. It is also possible to create a vacuum. Further, a hygroscopic compound can be enclosed inside.
Examples of the hygroscopic compound include metal oxides (for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide, etc.) and sulfates (for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate, etc.). Etc.), metal halides (eg calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide, etc.), perchlorates (eg, perchloric acid) Barium, magnesium perchlorate, etc.) and the like, and anhydrous salts are preferably used for sulfates, metal halides and perchlorates.

<Protective film, protective plate>
A protective film or a protective plate may be provided on the outer side of the sealing film or the sealing film on the side facing the support substrate with the light emitting unit sandwiched in order to increase the mechanical strength of the element. In particular, when sealing is performed by the sealing film, its mechanical strength is not necessarily high, so it is preferable to provide such a protective film and a protective plate. As a material that can be used for this, a glass plate, a polymer plate / film, a metal plate / film, etc. similar to those used for the sealing can be used, but the polymer film is lightweight and thin. Is preferably used.

<Light extraction>
The organic EL element emits light inside a layer having a higher refractive index than air (refractive index is about 1.7 to 2.1), and can extract only about 15 to 20% of the light generated in the light emitting layer. Is generally said. This is because light incident on the interface (intersection between the transparent substrate and air) at an angle θ equal to or greater than the critical angle causes total internal reflection and cannot be taken out of the element, and the transparent electrode or light emitting layer and the transparent substrate This is because the light is totally reflected between them, the light is waveguideed through the transparent electrode or the light emitting layer, and as a result, the light escapes toward the side surface of the element.

As a method for improving the efficiency of light extraction, for example, a method of forming irregularities on the surface of a transparent substrate to prevent total reflection at the interface between the transparent substrate and the air (US Pat. No. 4,774,435), and condensing light on the substrate. A method of improving efficiency by imparting properties (Japanese Patent Laid-Open No. 63-314795), a method of forming a reflective surface on a side surface of an element (Japanese Patent Laid-Open No. 1-220394), and between a substrate and a light emitter. A method of introducing a flat layer having an intermediate refractive index to form an antireflection film (Japanese Patent Laid-Open No. 62-172691), and introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter. Method (Japanese Patent Laid-Open No. 2001-202827), a method of forming a diffraction lattice between layers of a substrate, a transparent electrode layer or a light emitting layer (including the space between the substrate and the outside world) (Japanese Patent Laid-Open No. 11-283751), etc. There is.

In the present invention, these methods can be used in combination with the organic EL element of the present invention, but a method of introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter, or the substrate, transparent. A method of forming a diffraction lattice between layers of either the electrode layer or the light emitting layer (including between the substrate and the outside world) can be preferably used.
In the present invention, by combining these means, it is possible to obtain an element having higher brightness or excellent durability.

When a medium having a low refractive index is formed between the transparent electrode and the transparent substrate with a thickness longer than the wavelength of light, the light emitted from the transparent electrode has a higher efficiency of being taken out to the outside as the refractive index of the medium is lower. ..
Examples of the low refractive index layer include airgel, porous silica, magnesium fluoride, and a fluorine-based polymer. Since the refractive index of the transparent substrate is generally about 1.5 to 1.7, it is preferable that the low refractive index layer has a refractive index of about 1.5 or less. Further, it is more preferably 1.35 or less.
Further, it is desirable that the thickness of the low refractive index medium is at least twice the wavelength in the medium. This is because the effect of the low-refractive-index layer diminishes when the thickness of the low-refractive-index medium becomes about the wavelength of light and the film thickness of the electromagnetic wave exuded by evanescent enters the substrate.

The method of introducing the diffraction grating into the interface where total reflection occurs or any medium is characterized by having a high effect of improving the light extraction efficiency. This method utilizes the property that the diffraction lattice can change the direction of light to a specific direction different from the refraction by so-called Bragg diffraction such as first-order diffraction or second-order diffraction, and among the light generated from the light emitting layer. Light that cannot go out due to total reflection between layers is diffracted by introducing a diffraction lattice in either layer or in a medium (inside a transparent substrate or in a transparent electrode), and the light is emitted to the outside. It is something to take out.

It is desirable that the diffraction grating to be introduced has a two-dimensional periodic refractive index. This is because the light emitted by the light emitting layer is randomly generated in all directions, so in a general one-dimensional diffraction grating that has a periodic refractive index distribution only in one direction, only the light traveling in a specific direction is diffracted. However, the efficiency of light extraction does not increase so much.
However, by making the refractive index distribution a two-dimensional distribution, light traveling in all directions is diffracted, and the light extraction efficiency is improved.

As described above, the position where the diffraction grating is introduced may be in any of the layers or in the medium (in the transparent substrate or in the transparent electrode), but it is desirable that the diffraction grating is introduced in the vicinity of the organic light emitting layer where light is generated.
At this time, the period of the diffraction grating is preferably about 1/2 to 3 times the wavelength of the light in the medium.
The arrangement of the diffraction grating is preferably a square lattice shape, a triangular lattice shape, a honeycomb lattice shape, or the like, and the arrangement is repeated two-dimensionally.

<Condensing sheet>
The organic EL device of the present invention is processed so as to provide a microlens array-like structure on the light extraction side of the substrate, or by combining with a so-called condensing sheet, in a specific direction, for example, with respect to the light emitting surface of the device. By condensing light in the front direction, the brightness in a specific direction can be increased.
As an example of a microlens array, a quadrangular pyramid having a side of 30 μm and an apex angle of 90 degrees is arranged two-dimensionally on the light extraction side of the substrate. One side is preferably 10 to 100 μm. If it is smaller than this, the effect of diffraction is generated and it is colored, and if it is too large, the thickness becomes thick, which is not preferable.

As the condensing sheet, for example, a sheet that has been put into practical use in an LED backlight of a liquid crystal display device can be used. As such a sheet, for example, a brightness increasing film (BEF) manufactured by Sumitomo 3M Ltd. can be used.
The shape of the prism sheet may be, for example, a base material having a Δ-shaped stripe having an apex angle of 90 degrees and a pitch of 50 μm, or a shape having a rounded apex angle and a randomly changing pitch. It may have a formed shape or another shape.
Further, in order to control the light emission angle from the light emitting element, the light diffusing plate / film may be used in combination with the condensing sheet. For example, a diffusion film (light-up) manufactured by Kimoto Co., Ltd. can be used.

[Use]
The organic EL element of the present invention can be used as an electronic device, a display device, a display, and various light emitting devices. Light emitting devices include, for example, lighting devices (household lighting, interior lighting), clock and liquid crystal backlights, signage advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, and light. Examples include, but are not limited to, the light source of the sensor. In particular, it can be effectively used as a backlight of a liquid crystal display device and a light source for lighting.

If necessary, the organic EL device of the present invention may be patterned by a metal mask, an inkjet printing method, or the like at the time of film formation. In the case of patterning, only the electrodes may be patterned, or the electrodes and the light emitting layer may be patterned. The entire layer of the device may be patterned, and a conventionally known method can be used in manufacturing the device.

The luminescent colors of the organic EL element of the present invention and the compound according to the present invention are shown in FIG. 7.16 on page 108 of the "New Color Science Handbook" (edited by the Japan Color Society, Tokyo University Press, 1985). It is determined by the color when the result measured by a total of CS-1000 (manufactured by Konica Minolta Co., Ltd.) is applied to the CIE radiance coordinates.
When the organic EL element of the present invention is a white element, white means that the chromaticity in the CIE 1931 color system at ^{1000 cd / m 2 is X when the 2 degree viewing angle front luminance is measured by the above method.} = 0.33 ± 0.07, Y = 0.33 ± 0.1.

<Display device>
The organic EL element of the present invention can also be used in a display device. The display device may be monochromatic or multicolored, but here, a multicolor display device will be described.
In the case of a multicolor display device, a shadow mask is provided only when the light emitting layer is formed, and a film can be formed on one surface by a vapor deposition method, a casting method, a spin coating method, an inkjet method, a printing method, or the like.
When patterning only the light emitting layer, the method is not limited, but a vapor deposition method, an inkjet method, a spin coating method, and a printing method are preferable.

The configuration of the organic EL element provided in the display device is selected from the above-mentioned configuration examples of the organic EL element, if necessary.
The method for manufacturing the organic EL device is as shown in the above-described aspect of manufacturing the organic EL device of the present invention.
When a DC voltage is applied to the multicolor display device thus obtained, light emission can be observed by applying a voltage of about 2 to 40 V with the positive polarity of the anode and the negative polarity of the cathode. Further, even if a voltage is applied with the opposite polarity, no current flows and no light emission occurs. When an AC voltage is further applied, light is emitted only when the anode is in the + state and the cathode is in the-state. The AC waveform to be applied may be arbitrary.

The multicolor display device can be used as a display device, a display, and various light emitting light sources. Full-color display is possible by using three types of organic EL elements of blue, red, and green emission in a display device and a display.
Examples of display devices and displays include televisions, personal computers, mobile devices, AV devices, teletext displays, information displays in automobiles, and the like. In particular, it may be used as a display device for reproducing a still image or a moving image, and the drive method when used as a display device for reproducing a moving image may be either a simple matrix (passive matrix) method or an active matrix method.
Light sources include household lighting, interior lighting, backlights for clocks and liquid crystals, signboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, light sources for optical sensors, etc. The present invention is not limited thereto.

Hereinafter, an example of a display device having the organic EL element of the present invention will be described with reference to the drawings.
FIG. 3 is a schematic view showing an example of a display device composed of an organic EL element. It is a schematic diagram of the display of a mobile phone or the like which displays image information by light emission of an organic EL element.

The display 1 includes a display unit A having a plurality of pixels, a control unit B that scans an image of the display unit A based on image information, a wiring unit C that electrically connects the display unit A and the control unit B, and the like.
The control unit B is electrically connected via the display unit A and the wiring unit C, sends a scanning signal and an image data signal to each of a plurality of pixels based on image information from the outside, and the scanning signal is used to send pixels for each scanning line. Lights up sequentially according to the image data signal, scans the image, and displays the image information on the display unit A.

FIG. 4 is a schematic view of a display device based on the active matrix method.
The display unit A has a wiring unit C including a plurality of scanning lines 5 and a data line 6 and a plurality of pixels 3 and the like on the substrate. The main members of the display unit A will be described below.
FIG. 4 shows a case where the light emitted by the pixel 3 (emitted light L) is taken out in the direction of the white arrow (downward).

The scanning line 5 and the plurality of data lines 6 of the wiring portion are each made of a conductive material, and the scanning line 5 and the data line 6 are orthogonal to each other in a grid pattern and are connected to the pixel 3 at orthogonal positions (details are shown in the figure). Not).
When a scanning signal is applied from the scanning line 5, the pixel 3 receives an image data signal from the data line 6 and emits light according to the received image data.
Full-color display is possible by appropriately arranging pixels in the red region, pixels in the green region, and pixels in the blue region of the emission color on the same substrate.

Next, the light emitting process of the pixel will be described. FIG. 5 is a schematic view showing a pixel circuit.
The pixel includes an organic EL element 10, a switching transistor 11, a drive transistor 12, a capacitor 13, and the like. Full-color display can be performed by using organic EL elements that emit red, green, and blue as the organic EL elements 10 for a plurality of pixels and arranging them side by side on the same substrate.

In FIG. 5, an image data signal is applied from the control unit B to the drain of the switching transistor 11 via the data line 6. Then, when a scanning signal is applied from the control unit B to the gate of the switching transistor 11 via the scanning line 5, the driving of the switching transistor 11 is turned on, and the image data signal applied to the drain is the condenser 13 and the driving transistor 12. It is transmitted to the gate of.

By transmitting the image data signal, the capacitor 13 is charged according to the potential of the image data signal, and the drive transistor 12 is driven on. In the drive transistor 12, the drain is connected to the power supply line 7, the source is connected to the electrode of the organic EL element 10, and the power supply line 7 is connected to the organic EL element 10 according to the potential of the image data signal applied to the gate. Current is supplied.

When the scanning signal is transferred to the next scanning line 5 by the sequential scanning of the control unit B, the driving of the switching transistor 11 is turned off. However, since the capacitor 13 retains the potential of the charged image data signal even when the drive of the switching transistor 11 is turned off, the drive of the drive transistor 12 is kept on and the next scanning signal is applied. The light emission of the organic EL element 10 continues until. When the next scanning signal is applied by the sequential scanning, the driving transistor 12 is driven according to the potential of the next image data signal synchronized with the scanning signal, and the organic EL element 10 emits light.
That is, for the light emission of the organic EL element 10, the switching transistor 11 and the drive transistor 12, which are active elements, are provided for the organic EL element 10 of each of the plurality of pixels, and the organic EL element 10 of each of the plurality of pixels 3 emits light. It is carried out. Such a light emitting method is called an active matrix method.

Here, the light emission of the organic EL element 10 may be light emission of a plurality of gradations by a multi-valued image data signal having a plurality of gradation potentials, or may be on or off of a predetermined amount of light emission by a binary image data signal. good. Further, the potential of the capacitor 13 may be continuously maintained until the next scanning signal is applied, or may be discharged immediately before the next scanning signal is applied.
In the present invention, the light emission drive of the passive matrix method in which the organic EL element emits light in response to the data signal only when the scanning signal is scanned may be used instead of the active matrix method described above.

FIG. 6 is a schematic view of a display device based on the passive matrix method. In FIG. 6, a plurality of scanning lines 5 and a plurality of image data lines 6 are provided in a grid pattern so as to face each other with the pixel 3 interposed therebetween.
When the scanning signal of the scanning line 5 is applied by the sequential scanning, the pixel 3 connected to the applied scanning line 5 emits light according to the image data signal.
In the passive matrix method, the pixel 3 does not have an active element, and the manufacturing cost can be reduced.
By using the organic EL element of the present invention, a display device having improved luminous efficiency was obtained.

<Lighting device>
The organic EL element of the present invention can also be used in a lighting device.
The organic EL element of the present invention may be used as an organic EL element having a resonator structure. The purpose of using the organic EL element having such a resonator structure includes a light source of an optical storage medium, a light source of an electrophotographic copying machine, a light source of an optical communication processor, a light source of an optical sensor, and the like. Not limited. Further, it may be used for the above purpose by oscillating a laser.
Further, the organic EL element of the present invention may be used as a kind of lamp such as for lighting or an exposure light source, a projection device of a type for projecting an image, or a type for directly visually recognizing a still image or a moving image. It may be used as a display device (display).
When used as a display device for video reproduction, the drive system may be either a passive matrix system or an active matrix system. Alternatively, a full-color display device can be manufactured by using two or more kinds of organic EL elements of the present invention having different emission colors.

For example, when a plurality of light emitting materials are used, white light emission can be obtained by simultaneously emitting a plurality of light emitting colors and mixing the colors. The combination of a plurality of emission colors may include three emission maximum wavelengths of the three primary colors of red, green and blue, or two emissions utilizing the relationship of complementary colors such as blue and yellow and blue-green and orange. It may contain a maximum wavelength.

Further, in the method for forming the organic EL element of the present invention, a mask may be provided only when the light emitting layer, the hole transport layer, the electron transport layer, or the like is formed, and the mask may be applied separately. Since the other layers are common, patterning such as a mask is not required, and an electrode film can be formed on one surface by a vapor deposition method, a casting method, a spin coating method, an inkjet method, a printing method, or the like, and productivity is also improved.
According to this method, unlike a white organic EL device in which light emitting elements of a plurality of colors are arranged in parallel in an array, the elements themselves are light emitting white.

(One aspect of lighting equipment)
The non-light emitting surface of the organic EL element of the present invention is covered with a glass case, a glass substrate having a thickness of 300 μm is used as a sealing substrate, and an epoxy-based photocurable adhesive (Lux manufactured by Toa Synthetic Co., Ltd.) is used as a sealing material around the glass substrate. Track LC0629B) is applied, which is placed on the cathode and brought into close contact with the transparent support substrate, irradiated with UV light from the glass substrate side, cured, sealed, and illuminated as shown in FIGS. 7 and 8. The device can be formed.
FIG. 7 shows a schematic view of the lighting device, and the organic EL element (organic EL element 101 in the lighting device) of the present invention is covered with a glass cover 102 (note that the sealing work with the glass cover is lighting. The organic EL element 101 in the apparatus was carried out in a glove box in a nitrogen atmosphere (in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more) without being brought into contact with the atmosphere.
FIG. 8 shows a cross-sectional view of the lighting device, in which 105 is a cathode, 106 is an organic functional layer, and 107 is a glass substrate with a transparent electrode. The glass cover 102 is filled with nitrogen gas 108, and a water catching agent 109 is provided.
By using the organic EL element of the present invention, a lighting device having improved luminous efficiency was obtained.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. The compounds used in the following examples are shown.

[Example 1]
<Manufacturing of organic EL element 1-1>
ITO (indium tin oxide) was formed as an anode on a glass substrate having a thickness of 50 mm × 50 mm and a thickness of 0.7 mm to a thickness of 150 nm. After patterning, the transparent substrate to which the ITO transparent electrode was attached was ultrasonically cleaned with isopropyl alcohol. Then, it was dried with dry nitrogen gas, and UV ozone washing was performed for 5 minutes. Then, this transparent substrate was fixed to the substrate holder of a commercially available vacuum vapor deposition apparatus.
Each of the vapor deposition crucibles in the vacuum deposition apparatus was filled with the constituent materials of each layer in the optimum amount for manufacturing the device. As the crucible for vapor deposition, a crucible made of molybdenum or tungsten made of a resistance heating material was used.
After depressurizing to a degree of vacuum of 1 × 10 ^-4 Pa, a crucible for vapor deposition containing HAT-CN (1,4,5,8,9,12-hexaazatriphenylenehexacarbonitrile) was energized and heated. Then, the film was deposited on the ITO transparent electrode at a vapor deposition rate of 0.1 nm / sec to form a first hole injection layer having a layer thickness of 20 nm.
Next, compound 4-A represented by the following structural formula was vapor-deposited on the first hole injection layer at a vapor deposition rate of 0.1 nm / sec to form a first hole transport layer having a layer thickness of 50 nm.

Further, compound 4-B represented by the following structural formula was vapor-deposited on the first hole transport layer at a vapor deposition rate of 0.1 nm / sec to form an electron blocking layer having a layer thickness of 10 nm.

Compound 4-C represented by the following structural formula as the host compound of the first light emitting layer and compound 4-D as the blue fluorescent light emitting dopant are used at a vapor deposition rate of 0.1 nm / sec so as to be 95% and 5% by volume, respectively. Co-deposited to form a first light emitting layer having a layer thickness of 30 nm.

Then, as the first electron transport layer, the compound 4-E represented by the above structural formula was vapor-deposited at a vapor deposition rate of 0.1 nm / sec to form a first electron transport layer having a layer thickness of 30 nm.
Through the above steps, a first light emitting unit composed of a first hole injection layer, a first hole transport layer, an electron blocking layer, a first light emitting layer, and a first electron transport layer was produced.

Next, the comparative compounds 1 and Li are co-deposited at a vapor deposition rate of 0.1 nm / sec so as to be 95% and 5% by volume, respectively, and charged as an intermediate connector layer having a layer thickness of 20 nm on the first electron transport layer. A development layer was formed.
Then, HAT-CN (1,4,5,8,9,12-hexaazatriphenylenehexacarbonitrile) was deposited in the same manner as the first hole transport layer at a vapor deposition rate of 0.1 nm / sec to the intermediate connector layer (charge). A second hole injection layer having a thickness of 20 nm was formed by vapor deposition on the generation layer).
Next, compound 4-A was vapor-deposited on the second hole injection layer at a vapor deposition rate of 0.1 nm / sec to form a second hole transport layer having a layer thickness of 60 nm.
Compound 4-F shown in the above structural formula as the host compound of the second light emitting layer, Ir (ppy) ₃ as the green phosphorescent dopant, and Ir (piq) ₃ as the red phosphorescent dopant were 79%, 20%, and 1 respectively. A second light emitting layer having a layer thickness of 20 nm was formed by co-depositing at a vapor deposition rate of 0.1 nm / sec so as to have a volume% of%.

Then, in the same manner as the first electron transport layer, compound 4-E was vapor-deposited at a vapor deposition rate of 0.1 nm / sec to form a second electron transport layer having a layer thickness of 30 nm.
Through the above steps, a second light emitting unit composed of a second hole injection layer, a second hole transport layer, a second light emitting layer, and a second electron transport layer was produced.
Further, after forming LiQ on the second electron transport layer with a film thickness of 2 nm, aluminum 100 nm was vapor-deposited to form a cathode.
The non-light emitting surface side of the element was covered with a can-shaped glass case in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more, and an electrode take-out wiring was installed to prepare an organic EL element 1-1.

<Manufacturing of organic EL elements 1-2-1-40>
An organic EL element 1-2 to 1-40 was produced in the same manner as the organic EL element 1-1 except that the compound of the charge generation layer was changed as an intermediate connector layer as shown in Table I below.
In the organic EL elements 1-1 to 1-40, the charge generation layer contains 5% of Li, but the notation of Li is omitted in the table.

[evaluation]
(1) Measurement of initial voltage For each of the manufactured organic EL elements, the front brightness of each organic EL element on both the transparent electrode side (that is, the transparent substrate side) and the counter electrode side (that is, the cathode side) is measured. The voltage when the sum was 1000 cd / m ² was measured as the drive voltage (V). A spectral radiance meter CS-1000 (manufactured by Konica Minolta) was used for the measurement of the brightness.
The drive voltage obtained above was applied to the following equation to obtain the relative drive voltage of each organic EL element with respect to the drive voltage of the organic EL element 1-1.
Relative drive voltage (%) = (drive voltage of each organic EL element / drive voltage of organic EL element 1-1) × 100
The smaller the obtained numerical value, the more preferable the result.

(2) Measurement of voltage rise during driving The organic EL element produced above is made to ^{emit light at room temperature under a constant current condition of 2.5} mA / cm 2, and when the drive voltage immediately after the start of light emission and the brightness decrease by 5%. The drive voltage of was measured.
By comparing the obtained drive voltages before and after energization, the amount of change in the drive voltage (value obtained by subtracting the drive voltage after drive from the drive voltage before drive) was obtained.
The amount of change in the drive voltage obtained above was applied to the following equation to obtain the relative value of the amount of change in the drive voltage of each organic EL element with respect to the amount of change in the drive voltage of the organic EL element 1-1.
Voltage increase change amount (%) during driving = (drive voltage change amount of each organic EL element / drive voltage change amount of organic EL element 1-1) × 100
The smaller the obtained numerical value, the more preferable the result.

(3) Measurement of voltage rise after high-temperature storage The organic EL element produced above is made to ^{emit light at a temperature of 80 ° C. under a constant current condition of 2.5} mA / cm 2, and the drive voltage immediately after the start of light emission and 100 hours after the start of light emission. The later drive voltage was measured.
The obtained drive voltages before and after high-temperature storage were compared to determine the amount of change in drive voltage (value obtained by subtracting the drive voltage after high-temperature storage from the drive voltage before high-temperature storage).
The amount of change in the drive voltage obtained above is applied to the following equation, and the relative value of the amount of change in the drive voltage of each organic EL element with respect to the amount of change in the drive voltage of the organic EL element 1-1 is relatively driven under high temperature storage. Obtained as a voltage change.
Relative drive voltage change amount (%) due to high temperature storage = (drive voltage change amount of each organic EL element / drive voltage change amount of organic EL element 1-1) × 100
The smaller the obtained numerical value, the more preferable the result.

(4) Color shift For the measurement of the chromaticity of each organic EL element obtained above, for example, Noboru Daejeon "Color Engineering 2nd Edition" (Tokyo Denki University Press) and the like can be referred to.
Specifically, the emission spectrum of each organic EL element when lit at room temperature (within a range of about 23 to 25 ° C.) ^{under a constant current density condition of 50 mA / cm 2 is measured by the spectral radiance meter CS-.} It was measured using 2000 (manufactured by Konica Minolta). Then, the spectrum obtained by this measurement is converted from the primary stimuli [X], [Y], [Z] defined in the CIE1931 color system to the chromaticity coordinates x, y using the tristimulus values X, Y, Z. Converted.
Similarly, the emission brightness of each organic EL element when lit under a constant current density condition of 50 mA / cm ^{2 at room temperature was measured using a spectral radiance meter CS-2000 (manufactured by Konica Minolta).} .. Further, continuous driving was performed under the same conditions, and the time until the brightness decreased by 30% was determined as the light emission lifetime.
Then, the _{chromaticity difference ΔE xy} was calculated from the _{initial (LT 100} ) chromaticity coordinates x and y and the chromaticity coordinates x and y when the brightness decreased by 30% (LT ₇₀ ) by the following formula.
ΔE _xy = [(x _LT100 −x _LT70 ) ² + (y _LT100 −y _LT70 ) ² ] ^1/2
The chromaticity difference ΔE _xy obtained above was applied to the following equation to obtain the relative chromaticity difference of each organic EL element with respect to the chromaticity difference of the organic EL element 1-1.
Relative chromaticity difference (%) = (chromaticity difference of each organic EL element / chromaticity difference of organic EL element 1-1) × 100

[Example 2]
<Manufacturing of organic EL elements 2-1 to 2-7>
In the production of the organic EL element 1-1 in Example 1, the organic EL element 2-1 was produced in the same manner except that Li used as the material of the intermediate connector layer (charge generation layer) was changed to Na. Further, in the production of the organic EL element 2-1 the organic EL element 2-2-2-7 was produced in the same manner except that the comparative compound 1 was as shown in Table II below.
In the organic EL elements 2-1 to 2-7, the charge generation layer contains 5% of Na, but the notation of Na is omitted in the table.
Further, in Example 2, the same evaluation as in Example 1 was performed, and a relative evaluation was performed on the organic EL element 2-1 instead of the organic EL element 1-1.

[Example 3]
<Manufacturing of organic EL elements 3-1 to 3-7>
In the production of the organic EL element 1-1 in Example 1, the organic EL element 3-1 was produced in the same manner except that Li used as the material of the intermediate connector layer (charge generation layer) was changed to Ca. Further, in the production of the organic EL element 3-1 the organic EL element 3-2-3-7 was produced in the same manner except that the comparative compound 1 was as shown in Table III below.
In the organic EL elements 3-1 to 3-7, the charge generation layer contains 5% of Ca, but the notation of Ca is omitted in the table.
Further, in Example 3, the same evaluation as in Example 1 was performed, and a relative evaluation was performed on the organic EL element 3-1 instead of the organic EL element 1-1.

[Example 4]
<Manufacturing of organic EL elements 4-1 to 4-32>
In the production of the organic EL device 1-1 in the first embodiment, the organic EL device 4- 1-4-32 were prepared.
Further, in Example 4, the same evaluation as in Example 1 was performed, and a relative evaluation was performed on the organic EL element 4-1 instead of the organic EL element 1-1.

From the results shown in the above tables, it is recognized that the organic EL element of the present invention has improved voltage rise during driving, durability after high temperature storage, and color shift as compared with the organic EL element of the comparative example.

1 Display 3 Pixels 5 Scanning line 6 Data line 7 Power supply line 10 Organic EL element 11 Switching transistor 12 Drive transistor 13 Condenser 101 Organic EL element in the lighting device 102 Glass cover 105 Cathode 106 Organic functional layer 107 Glass substrate with transparent electrode 108 Nitrogen Gas 109 Water trapping agent 110 Organic EL element 111 Anopole 112 First light emitting unit 113 Intermediate connector layer 114 Second light emitting unit 115 Cathode 116 Support substrate 117 First hole injection layer 118 First hole transport layer 119 First light emitting layer 120 First 1 Electron transport layer 121 Second hole injection layer 122 Second hole transport layer 123 Second light emitting layer 124 Second electron transport layer A Display unit B Control unit C Wiring unit L Emission light

Claims (10)

An anode, a cathode, a first light emitting layer and a second light emitting layer provided between the anode and the cathode, and an intermediate connector layer provided between the first light emitting layer and the second light emitting layer. It is an organic electroluminescence element that has
The intermediate connector layer contains an alkali metal or an alkaline earth metal, and the intermediate connector layer contains an alkali metal or an alkaline earth metal.
An organic electroluminescence device, wherein the intermediate connector layer or a layer between the intermediate connector layer and the first light emitting layer contains a compound having a structure represented by the following general formula (1).

[In the general formula (1), A1 and A2 represent residues that form a 6-membered aromatic heterocycle together with a nitrogen atom, and the 6-membered aromatic heterocycle may be condensed. L represents a single bond, an aromatic hydrocarbon ring, an aromatic heterocycle or an alkyl group. ] The first aspect of the present invention, wherein the intermediate connector layer or the layer between the intermediate connector layer and the first light emitting layer contains a compound having a structure represented by the following general formula (2). Organic electroluminescence element.

[In the general formula (2), Ra, Rb and Rc represent a hydrogen atom or a substituent. At least one of Ra, Rb and Rc represents a 6-membered aromatic heterocycle, and the 6-membered aromatic heterocycle may be fused. n1 represents an integer of 1 to 4. ] The first aspect of the present invention, wherein the intermediate connector layer or the layer between the intermediate connector layer and the first light emitting layer contains a compound having a structure represented by the following general formula (3). Organic electroluminescence element.

[In the general formula (3), Re, Rd and Rf represent a hydrogen atom or a substituent. At least one of Re, Rd and Rf represents a 6-membered aromatic heterocycle, and the 6-membered aromatic heterocycle may be fused. n2 represents an integer of 1 to 4. ] The first aspect of the present invention, wherein the intermediate connector layer or the layer between the intermediate connector layer and the first light emitting layer contains a compound having a structure represented by the following general formula (4). Organic electroluminescence element.

[In the general formula (4), Rg, Rh, Ri and Rj represent a hydrogen atom or a substituent. At least one of Rg, Rh, Ri and Rj represents a 6-membered aromatic heterocycle, and the 6-membered aromatic heterocycle may be fused. L ₂ represents a single bond, an aromatic hydrocarbon ring, an aromatic heterocycle or an alkyl group. ] The first aspect of the present invention, wherein the intermediate connector layer or the layer between the intermediate connector layer and the first light emitting layer contains a compound having a structure represented by the following general formula (5). Organic electroluminescence element.

[In general formula (5), Ar represents carbazole, dibenzofuran, azadibenzofuran, dibenzothiophene, azadibenzothiophene, azacarbazole, naphthalene, anthracene, phenanthrene or fluorene. Rk represents a hydrogen atom or a substituent. At least two of Rk represent a 6-membered aromatic heterocycle, and the 6-membered aromatic heterocycle may be fused. n3 represents 2 or more. ] The first aspect of the present invention, wherein the intermediate connector layer or the layer between the intermediate connector layer and the first light emitting layer contains a compound having a structure represented by the following general formula (6). Organic electroluminescence element.

[In the general formula (6), Y ₁ and Y ₂ represent O, S or N-R ₁ . X _{1 to} X ₁₆ represent _{CR 2} or N. At least two of _{X 1 to} X _{16 represent N.} L ₁ represents a single bond, an aromatic hydrocarbon ring, an aromatic heterocycle or an alkyl group. R ₁ and R ₂ represent an aromatic hydrocarbon ring, an aromatic heterocycle or an alkyl group. ] The organic electroluminescence element according to any one of claims 1 to 6, wherein the intermediate connector layer contains Li, Na, K, Mg or Ca. The organic electroluminescence device according to any one of claims 1 to 6, wherein the intermediate connector layer contains Li. The invention according to any one of claims 1 to 8, wherein the intermediate connector layer contains any of the compounds having a structure represented by the general formulas (1) to (6). Organic electroluminescence element. Claim 1 according to claim 1, wherein the layer between the intermediate connector layer and the first light emitting layer contains any of the compounds having a structure represented by the general formulas (1) to (6). Item 2. The organic electroluminescence device according to any one of items up to item 8.

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