JP6635627B2 - Organic electroluminescence element, method of manufacturing the same, display device, and lighting device - Google Patents

Description

  The present invention relates to an organometallic complex, an organic electroluminescence (hereinafter, electroluminescence (electroluminescence) may be referred to as “EL”) element, a method for manufacturing the same, a display device, a lighting device, and a thin-film solar cell. More specifically, the present invention relates to an organometallic complex that can be suitably used as a material for an electron injection layer provided in an organic EL device.

Organic EL devices are thin, flexible and flexible. In addition, a display device using an organic EL element can perform high-brightness and high-definition display as compared with currently mainstream liquid crystal display devices and plasma display devices. A display device using an organic EL element has a wider viewing angle than a liquid crystal display device. For this reason, display devices using organic EL elements are expected to be increasingly used as displays for televisions and mobile phones in the future.
The organic EL element is also expected to be used as a lighting device.

  The organic EL element has a structure in which a cathode, a light emitting layer, and an anode are laminated. In the organic EL device, the difference between the work function of the anode and the highest occupied orbital (HOMO) energy of the light emitting layer is smaller than the difference between the work function of the cathode and the lowest unoccupied orbital (LUMO) energy of the light emitting layer. Therefore, it is more difficult to inject electrons from the cathode than to inject holes from the anode into the light emitting layer. For this reason, in the conventional organic EL element, an electron injection layer is disposed between the cathode and the light emitting layer to promote injection of electrons from the cathode to the light emitting layer.

However, generally, a material active in oxygen or water, such as an alkali metal, is used for the electron injection layer. For this reason, the conventional organic EL element needs to be strictly sealed with a sealing layer to prevent the electron injection layer from being deteriorated by oxygen or water.
On the other hand, in order to obtain an organic EL element having excellent flexibility, it is preferable to use a plastic substrate. However, plastic substrates are materials that are difficult to seal strictly. For this reason, a plastic substrate cannot be sometimes used as a substrate of the organic EL element.

Further, in order to improve the durability while securing the performance of the organic EL element, use of an electron injection layer containing no alkali metal has been studied.
For example, Non-Patent Document 1 describes an organic EL device having an electron injection layer made of polyethyleneimine. Non-Patent Document 2 describes that amines are effective for improving the electron injection speed, and Non-Patent Document 3 describes the effect of those amino groups on electron injection at the interface between the electrode and the organic layer. Have been.

Jiangshan Chen and 6 others, "Journal Of Materials Chemistry", Vol. 22, 2012, p5164-5170 Hyosung Choi, 8 others, "Advanced Materials", Vol. 23, 2011, p. 2759 Yinhua Zho, 21 others, "Science", Vol. 336, 2012, p. 327 Young-Hoon Kim, five others, "Advanced Functional Materials", 2014, DOI: 10.1002 / adfm. 201304163 Stephane Forful, 4 others, "Advanced Materials", 2014, DOI: 10.1002 / adma. 201304666 Stephen Fofle, five others, "Advanced Materials", Vol. 26, 2014, DOI: 10.1002 / adma. 201400332

However, the electron injection layer of the conventional organic EL device has insufficient electron injection properties and / or durability.
For example, by using polyethyleneimine as a material for the electron injection layer of the organic EL element, excellent electron injection properties can be obtained. However, in the molecule of polyethyleneimine, there is an NH bond which is unstable to electrical stimulation. For this reason, the organic EL element having the electron injection layer made of polyethyleneimine had a rapid deterioration in luminance and was insufficient in durability.

The present invention has been made in view of the above circumstances, and has as its object to provide a material from which an electron injection layer having excellent electron injection properties and durability can be obtained.
Another object of the present invention is to provide an organic thin-film solar cell, an organic EL device, and a method for manufacturing an organic EL device having an electron injection layer having excellent electron injection properties and durability.
Another object of the present invention is to provide a display device and a lighting device each including an organic EL element having an electron injection layer having excellent electron injection properties and durability.

  The present inventors have focused on an organometallic complex as a material used for an electron injection layer. An organometallic complex is a ligand in which a ligand having an lone pair of electrons is coordinated to surround a metal atom, and has a large intramolecular dipole moment. The present inventors have conducted studies as described below in order to form an electron injection layer containing an organometallic complex and use the dipole direction of the organometallic complex to promote electron injection in the electron injection layer. .

For example, when an electron injection layer containing an organometallic complex is formed between the cathode of the organic EL element and the light emitting layer, the direction of the intramolecular dipole of the organometallic complex in the electron injection layer is from the cathode side. The direction may be a direction toward the light emitting layer side. That is, the organometallic complex may be oriented so that the cathode side has a negative charge and the light emitting layer side has a positive charge. As a result, the work function of the electron injection layer can be changed to a value advantageous for electron injection from the cathode to the light emitting layer, and the injection of electrons from the cathode to the light emitting layer is promoted.
However, it was difficult to align the orientation of the intramolecular dipole of the organometallic complex in the electron injection layer in a predetermined direction.

  Therefore, the present inventors have paid attention to polyethyleneimine which has been conventionally used as a material for an electron injection layer. In the electron injection layer made of polyethyleneimine, the charge of the nitrogen atom forming the amino group of polyethyleneimine forms a coordination bond with the material forming the cathode of the organic EL device. For this reason, the present inventors have examined adding an amino group capable of forming a coordination bond with the material forming the cathode to the organometallic complex. Then, they have found that the organometallic complex can be oriented in a predetermined direction by adding an amino group to a specific site far from the coordination bond between the metal atom and the ligand in the organometallic complex.

  More specifically, when an electron injection layer containing an organometallic complex having an amino group at a specific site is formed in contact with the cathode, the amino group in the organometallic complex is coordinated with the cathode material to form a dipole ( Interface dipole), and the amino groups in the organometallic complex are located close to the cathode. Then, the organometallic complex is oriented in a specific direction depending on the positional relationship between the amino group in the organometallic complex and the coordination bond between the metal atom and the ligand.

  As a result, the vector of the dipole (intramolecular dipole) generated by the coordination bond between the metal atom and the ligand is in the direction from the cathode side to the light emitting layer side. In addition, the direction of the intramolecular dipole is the same as the direction of the interface dipole generated by the coordination bond between the amino group and the cathode material. Therefore, the dipole moment (vector) of the entire electron injection layer including the organometallic complex is the direction from the cathode side to the light emitting layer side due to the addition of the intramolecular dipole and the interface dipole. Therefore, electron injection from the cathode to the light emitting layer is promoted by the electron injection layer.

  Further, the present inventors have provided an amino group in which a hydrogen atom of ammonia has been substituted with a monovalent alkyl group as an amino group to the organometallic complex. This amino group does not contain an NH bond that is unstable to electrical stimulation, and is electrically stable as compared to an amino group that contains an NH bond. Therefore, the electron injection layer containing an organometallic complex having an amino group obtained by substituting a hydrogen atom of ammonia with a monovalent alkyl group is less likely to deteriorate and has excellent durability as compared with an electron injection layer made of polyethyleneimine. .

Furthermore, the present inventors have found that by providing an amino group in which a hydrogen atom of ammonia is substituted with a monovalent alkyl group to the organometallic complex, the solubility of the organometallic complex in a solvent is improved. Therefore, such an organometallic complex is dissolved in a solvent to form a solution, and an electron injection layer containing the organometallic complex can be formed by applying the solution.
The gist of the present invention based on the above findings is as follows.

That is, the present invention relates to the following inventions.
[1] An organometallic complex represented by the following general formula (1).

(In the general formula (1), M is a metal atom, and represents a metal atom belonging to Groups 1 to 3, 12, or 13 of the periodic table. C is a carbon atom, and N is a nitrogen atom. , O represent an oxygen atom, and a dotted line from a nitrogen atom to a metal atom M represents that the nitrogen atom is coordinated to the metal atom M. Q ¹ is a dotted arc and a nitrogen atom, X ¹ , Y ¹ X ¹ and X ² each represent a carbon atom or a nitrogen atom, and Y ¹ and Y ² represent a carbon atom, a nitrogen atom, an oxygen atom, or represents a sulfur atom .Q ² is .R ^1, R ² indicating that dotted arc and carbon atoms, X ^2, aromatic with Y ² hydrocarbon ring or an aromatic heterocyclic ring is formed on the amino group represents a monovalent alkyl group, this L is the, Q ² and the amino group is bonded directly Or .n representing a linking group linking, ^{Q 2} and amino groups is 1, 2 or 3.)

[2] An organometallic complex represented by the following general formula (2).

(In the general formula (2), M is a metal atom, and represents a metal atom belonging to Groups 1 to 3, 12, or 13 of the periodic table. N is a nitrogen atom, and O is an oxygen atom. The dotted line from the nitrogen atom to the metal atom M indicates that the nitrogen atom is coordinated to the metal atom M. Q ¹ is the nitrogen-containing heterocyclic ring together with the dotted arc and the nitrogen atom, X ¹ and Y ^1. X ¹ represents a carbon atom or a nitrogen atom, Y ¹ represents a carbon atom, a nitrogen atom, an oxygen atom, or a sulfur atom, and R ¹ and R ² represent an amino group. L represents the above monovalent alkyl group, L represents a direct bond between a benzene ring and an amino group, or a linking group connecting a benzene ring and an amino group, and n represents 1, 2 or 3. is there.)

[3] An organometallic complex represented by the following general formula (3).

(In the general formula (3), M is a metal atom, and represents a metal atom belonging to Groups 1 to 3, 12, or 13 of the periodic table. N is a nitrogen atom, and O is an oxygen atom. The dotted line from the nitrogen atom to the metal atom M indicates that the nitrogen atom is coordinated to the metal atom M. Q ¹ is a nitrogen-containing heterocyclic ring together with a dotted arc, a nitrogen atom and a part of a naphthalene ring. R ¹ and R ² represent a monovalent alkyl group on an amino group, L represents that a naphthalene ring and an amino group are directly bonded, or that a naphthalene ring and an amino group And n represents 1, 2, or 3.)

[4] An organic electroluminescence having an electron injection layer between an electrode and a light emitting layer, wherein the electron injection layer contains the organometallic complex according to any one of [1] to [3]. element.
[5] The organic electroluminescent device according to [4], further including an inorganic oxide layer between the electrode and the electron injection layer.
[6] The organic electroluminescence device according to [4] or [5], wherein the average thickness of the electron injection layer is 5 to 100 nm.

[7] The organic electroluminescence according to any of [4] to [6], wherein the material is sealed using a material having a water vapor permeability of less than 1 × 10 ⁻³ g / m ² / day. element.
[8] The method for producing an organic electroluminescence device according to any one of [4] to [7], wherein the step of forming the electron injection layer includes a step of applying a solution containing the organometallic complex. A method for producing an organic electroluminescent device, comprising:

[9] A display device comprising the organic electroluminescent element according to any one of [4] to [7].
[10] A lighting device comprising the organic electroluminescent element according to any one of [4] to [7].
[11] An organic thin-film solar cell comprising an electron injection layer containing the organometallic complex according to any one of [1] to [3].

Since the organometallic complex of the present invention is represented by any one of the general formulas (1) to (3), it has excellent electron injecting properties and durability when used as a material for an electron injecting layer. An electron injection layer is obtained.
Further, the organic EL device of the present invention has an electron injection layer containing an organometallic complex represented by any of the above general formulas (1) to (3). Therefore, the dipole moment (vector) of the entire electron injection layer including the organometallic complex is in a direction from the cathode side to the light emitting layer side. Therefore, in the organic EL device of the present invention, electron injection from the cathode to the light emitting layer is promoted by the electron injection layer, and high luminous efficiency can be obtained with a low driving voltage. Since the organic metal complex of the present invention does not include an NH bond, the organic EL element is electrically connected to an electron injection layer using a compound including an amino group including an NH bond. Stable and durable. Therefore, in the organic EL device of the present invention, the deterioration of the organic EL device due to the deterioration of the electron injection layer is suppressed.

FIG. 2 is a schematic cross-sectional view illustrating an example of the organic EL device of the present invention. FIG. 3 is an explanatory diagram for explaining the orientation of the organometallic complex in the organic EL device of the present invention, and is a perspective view showing a molecular model (molecular model) of the organometallic complex on the inorganic oxide layer. FIG. 6 is a schematic cross-sectional view for explaining another example of the organic EL device of the present invention. FIG. 4A is a graph showing the relationship between the applied voltage and the current density of the elements 1 to 4. FIG. 4B is a graph showing the relationship between the applied voltage of elements 1 to 4 and the luminance. 9 is a graph showing a change in luminance with respect to an elapsed time when elements 1 and 3 are continuously driven from an initial luminance of 1000 cd / m ² . 9 is a graph showing the relationship between the applied voltage and the luminance of element 1 and element 5. FIG. 9 is a perspective view for explaining a method of sealing the element 6. 6 is a graph showing a change in luminance with respect to an elapsed time when the element 6 sealed with a resin material and the element 6 sealed with a glass material are continuously driven from an initial luminance of 1000 cd / m ² when driven continuously.

Hereinafter, the present invention will be described in detail.
"Organic metal complexes"
The organometallic complex of the present invention is an organometallic complex represented by the general formula (1).

  In the general formula (1), a dotted line from a nitrogen atom to a metal atom M indicates that the nitrogen atom is coordinated to the metal atom M. The fact that the nitrogen atom is coordinated with the metal atom M means that the nitrogen atom acts on the metal atom M in the same manner as the ligand to chemically affect the metal atom M. In the general formula (1), C represents a carbon atom, N represents a nitrogen atom, and O represents an oxygen atom.

  In the above general formula (1), M is a metal atom, and represents a metal atom belonging to Groups 1 to 3, 12 or 13 of the periodic table. The metal atom M is preferably lithium, beryllium, magnesium, calcium, barium, scandium, zinc, aluminum, or gallium. More preferably, the metal atom M is beryllium, magnesium, zinc, or aluminum. More preferably, the metal atom M is beryllium, magnesium or zinc.

In the above general formula (1), Q ¹ represents that a nitrogen-containing heterocyclic structure is formed together with a dotted arc, a nitrogen atom, X ¹ and Y ¹ . In the above general formula (1), the nitrogen-containing heterocyclic structure represented by Q ¹ may have a substituent.
In the above general formula (1), X ¹ and X ² each represent a carbon atom or a nitrogen atom, and Y ¹ and Y ² each represent a carbon atom, a nitrogen atom, an oxygen atom, or a sulfur atom. Y ¹ and Y ² may form a ring structure with X ¹ and X ² via a linking group A connecting them. As shown in the general formula (2), when the aromatic hydrocarbon ring or the aromatic heterocyclic ring represented by Q ² is a benzene ring, Y ¹ is linked to a part of the benzene ring via a linking group bonded thereto. bound may form part and X ¹ together with 5-membered ring structure or a 6-membered ring structure of the benzene ring.

Examples of the nitrogen-containing heterocyclic ring represented by Q ¹ include a 6-membered nitrogen-containing heterocyclic ring such as a pyridine ring, a pyrazine ring, a triazine ring, a pyrimidine ring, a pyridazine ring, an imidazole ring, an oxazole ring, a thiazole ring, and an oxadiazole ring. , Thiadiazole ring, triazole ring, pyrazole ring, 5-membered nitrogen-containing heterocycle such as oxazoline ring, quinoline ring, quinoxaline ring, naphthyridine ring, benzimidazole ring, condensed nitrogen-containing heterocycle such as benzothiazole ring and benzoxazole ring And the like. Among the nitrogen-containing heterocyclic ring represented by these Q ^1, a pyridine ring, a benzothiazole ring.

In the general formula (1), Q ² represents that dotted arc and carbon atoms, X ^2, aromatic with Y ² hydrocarbon ring or an aromatic heterocyclic ring is formed. Aromatic hydrocarbon ring or aromatic heterocyclic ring shown by Q ² may have a substituent.
Examples of the aromatic hydrocarbon ring represented by Q ^2, a benzene ring, a naphthalene ring, an anthracene ring, an azulene ring, a phenanthrene ring, triphenylene ring, octahydronaphthalene ring, and the like.
Examples of the aromatic heterocyclic ring represented by Q ² include a 6-membered nitrogen-containing heterocyclic ring such as a pyridine ring, a pyrazine ring, a triazine ring, a pyrimidine ring, a pyridazine ring, an imidazole ring, an oxazole ring, a thiazole ring, and a thiophene ring. And condensed aromatic heterocycles such as a 5-membered aromatic heterocycle of a pyrrole ring, a quinoline ring, a quinoxaline ring, a naphthyridine ring, a benzimidazole ring, a benzothiazole ring, a benzoxazole ring, and a carbazole ring.
Among the aromatic hydrocarbon ring or aromatic heterocyclic ring shown in these Q ^2, a benzene ring, a pyridine ring are preferred, as shown in the above general formula (2), a benzene ring is more preferable.

Examples of the linking group that forms a ring structure with Y ¹ , Y ² , X ¹ , and X ² (hereinafter sometimes referred to as “linking group A”) include the following general formulas (2-1) to (2-1). 2-9), and a structure represented by the general formula (2-1) is preferable as shown in the general formula (3). The hydrogen atom contained in the linking group A may be replaced with a monovalent substituent.

The * mark in the above general formulas (2-1) to (2-9) indicates that the linking group A is bonded to Y ¹ and Y ² at the position marked with the * mark. That is, Q ¹ and Q ² shown in the general formula (1) represent that a condensed ring may be formed via the linking group A.
In the present embodiment, a structure in which the structure represented by the general formula showing the linking group A (2-1) ~ (2-9) is represented by the general formula (2-1), by ^{Q 2} When the aromatic hydrocarbon ring or aromatic heterocyclic ring shown is a benzene ring, the ring structure composed of Y ¹ , Y ² , X ¹ , X ² and the connecting group A is as shown in the general formula (3). And a benzene ring.
Further, in the present embodiment, the nitrogen-containing heterocyclic ring represented by Q ¹ is a pyridine ring, the aromatic hydrocarbon ring or the aromatic heterocyclic ring represented by Q ² is a benzene ring, and Y ¹ , Y ² , X ¹ , It is preferable that the ring structure composed of X ² and the connecting group A is a benzene ring. In this case, the condensed ring composed of Q ¹ and Q ² and the structure represented by the general formula (2-1) is 7,8-benzoquinoline.

In the general formula (1), L represents that Q ² and an amino group are directly bonded or a linking group that connects Q ² and an amino group. The linking group represented by L is a group that connects an amino group at an arbitrary position constituting the aromatic hydrocarbon ring or aromatic heterocyclic ring represented by Q ² . The bonding position between the linking group L represented by L and Q ² is not particularly limited, but is preferably bonded at the ortho position of the carbon atom to which the oxygen atom is bonded in Q ² . Linking group L is represented by L, when attached to the ortho position of the carbon atom to oxygen atom Q ² 'are attached, for example, to form an electron injection layer containing an organic metal complex on the cathode, and the cathode The coordination bond between the metal group and the amino group of the organometallic complex makes it easy for the intramolecular dipole generated by the coordination bond between the metal atom and the ligand to be oriented in the direction from the cathode side to the light emitting layer side.

  Examples of the linking group represented by L include an alkylene linking group (eg, a methylene group, an ethylene group, a propylene group, a butylene group, etc.), an arylene linking group (eg, a phenylene group, a naphthylene group, etc.), a heterocyclic linking group ( For example, furyl group, thienylene group, pyridyl group, pyrimidyl group, triazyl group, imidazolyl group, pyrazolyl group, oxazolyl group, morpholyl group, etc., alkenylene linking group (vinylene group, etc.), alkynylene linking group, nitrogen atom, oxygen atom, etc. Is mentioned. The linking group represented by L may be a combination of two or more of the linking groups listed above. As the linking group represented by L, an alkylene linking group is particularly preferable among the above linking groups. It is preferable that the linking group represented by L is an alkylene linking group because the solubility of the organometallic complex can be improved. Further, the hydrogen atom contained in the linking group L may be replaced with a monovalent substituent.

In the general formula (1), R ¹ and R ² represent a monovalent alkyl group on an amino group, and R ¹ and R ² may be the same or different. Examples of the monovalent alkyl group represented by R ¹ and R ² include a hydrocarbon group such as a methyl group, an ethyl group and a benzyl group, and a hetero atom-containing group such as an alkoxyethyl group and a dimethylaminoethyl group.

In the general formula (1), Q ¹ , Q ² , the linking group A, and the linking group L may have the same or different monovalent substituents. In Q ¹ , Q ² , the linking group A, and the linking group L, the position or the number of the monovalent substituent bonded is not particularly limited. The monovalent substituent that may be bonded to any one or more of Q ¹ , Q ² , linking group A, and linking group L is not particularly limited, but includes, for example, a halogen atom and a hydrocarbon having 1 to 20 carbon atoms. Group, halogenated hydrocarbon group having 1 to 12 carbon atoms, heterocyclic group having 0 to 12 carbon atoms, cyano group, alkoxy group having 1 to 12 carbon atoms, alkoxycarbonyl group having 2 to 12 carbon atoms, 6 to 12 carbon atoms And an N-disubstituted amino group having 2 to 30 carbon atoms.

  The halogen atom is preferably a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom.

The hydrocarbon group having 1 to 20 carbon atoms is a straight chain having 1 to 12 carbon atoms such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a hexyl group and an octyl group. C2-C12 alkenyl groups such as vinyl, 1-propenyl, allyl and styryl; C2-C12 alkenyl such as ethynyl, 1-propynyl and propargyl An alkynyl group; a cyclic alkyl group having 5 to 12 carbon atoms such as a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group; and an aryl group having 6 to 20 carbon atoms which may be substituted with an alkyl group, an alkenyl group, an alkynyl group, and the like. Can be
Among the above-mentioned hydrocarbon groups having 1 to 20 carbon atoms, those having 1 to 8 carbon atoms are preferable, more preferably 1 to 6 carbon atoms, and still more preferably 1 to 6 carbon atoms. 4. The hydrocarbon group having 1 to 20 carbon atoms is particularly preferably one having 1 carbon atom among those described above.

The halogenated hydrocarbon group having 1 to 12 carbon atoms is a haloalkyl group having 1 to 12 carbon atoms such as fluoromethyl group, difluoromethyl group and trifluoromethyl group; aryl having 6 to 12 carbon atoms substituted by a halogen atom. Groups.
The above-mentioned halogenated hydrocarbon group having 1 to 12 carbon atoms preferably has 1 to 8 carbon atoms, more preferably 1 to 6 among those described above.

The heterocyclic group having 0 to 12 carbon atoms is a 5-membered nitrogen-containing ring group such as pentazole; triazole, tetrazole, imidazole, oxazole, isoxazole, thiazole, isothiazole, pyrazole, pyrrole, pyrrolidine, oxazoline, furan, and thiophene. And a 5-membered heterocyclic group such as pyridine, pyrazine, piperidine, morpholine and thiazine. In addition, these heterocyclic groups may be substituted with a halogen atom, an alkyl group, an aryl group, an alkoxy group, an alkenyl group, an alkynyl group, or the like.
The above-mentioned heterocyclic group having 0 to 12 carbon atoms preferably has 1 to 8 carbon atoms, more preferably 1 to 6 among those described above.

The alkoxy group having 1 to 12 carbon atoms includes a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a tert-butoxy group, a pentyloxy group, a hexyloxy group, a heptyloxy group, and an octyloxy group. And the like are preferred.
Among the above-mentioned alkoxy groups having 1 to 12 carbon atoms, those having 1 to 8 carbon atoms are preferable, more preferably 1 to 6 carbon atoms, and still more preferably 1 to 3 carbon atoms.

The alkoxycarbonyl group having 2 to 12 carbon atoms is a linear or branched one such as a methoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, a tert-butoxycarbonyl group, a hexyloxycarbonyl group, and an octyloxycarbonyl group. Is mentioned.
The above-mentioned alkoxycarbonyl group having 2 to 12 carbon atoms preferably has 2 carbon atoms among those described above.

Examples of the aryloxy group having 6 to 12 carbon atoms include a phenyloxy group and a benzyloxy group. In the aryloxy group having 6 to 12 carbon atoms, for example, the aryl group portion of the aryloxy group may be substituted with a halogen atom, an alkyl group, an aryl group, an alkoxy group, an alkenyl group, an alkynyl group, or the like.
The aryloxy group having 6 to 12 carbon atoms preferably has 6 to 10 carbon atoms, more preferably 6 to 8 carbon atoms, and still more preferably 6, among those described above.

Examples of the C2-C30 N-disubstituted amino group include a C1-C12 dialkylamino group such as a dimethylamino group, a diethylamino group, a pyrrolidinyl group, and a morpholinyl group; an N-methyl-N-phenylamino group; N-alkyl-N-arylamino group having 6 to 20 carbon atoms such as N-ethyl-N-naphthylamino group; non-cyclic having 11 to 30 carbon atoms such as diphenylamino group, carbazolyl group, phenoxazinyl group and phenothiazinyl group Suitable examples include a diarylamino group and a cyclic diarylamino group.
In addition, the acyclic diarylamino group means a group having no ring structure other than the aromatic ring. The cyclic diarylamino group refers to a group having a ring structure other than an aromatic ring. In the above-mentioned N-disubstituted amino group having 2 to 30 carbon atoms, for example, the alkyl or aryl part of the N-disubstituted amino group is substituted with a halogen atom, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group or the like. It may be.

The dialkylamino group having 1 to 12 carbon atoms preferably has 1 to 8 carbon atoms among those described above. More preferably, it is 1-6. More preferably, it is 1-4.
The above-mentioned N-alkyl-N-arylamino group having 6 to 20 carbon atoms preferably has 7 to 18 carbon atoms among those described above. More preferably, it is 7 to 15. More preferably, it is 7-11.
The acyclic diarylamino group or cyclic diarylamino group having 11 to 30 carbon atoms preferably has 11 to 20 carbon atoms, more preferably 12 to 18 carbon atoms, and still more preferably, those described above. , 12-16.

In addition, a monovalent substituent which may be bonded to any one or more of Q ¹ , Q ² , linking group A and linking group L is an acyl group such as an acetyl group, a propionyl group, a butyryl group; N, N-dialkylcarbamoyl groups such as dimethylcarbamoyl group and N, N-diethylcarbamoyl group; thiocarbonyl groups such as thioacetyl group, thiobenzoyl group and methoxythiocarbonyl group; dioxaborolanyl group, stannyl group, silyl group , An ester group, a formyl group, a thioether group, an epoxy group, an isocyanate group, a sulfo group, a sulfonyl group, a phosphoryl group and the like.

The monovalent substituent (a monovalent substituent which may be bonded to any one or more of Q ¹ , Q ² , linking group A and linking group L) is not limited as long as the effects of the present invention can be exerted. It may be substituted with a monovalent substituent such as a halogen atom, a hetero atom, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group and an aromatic ring. When the above monovalent substituent (a monovalent substituent that may be bonded to any one or more of Q ¹ , Q ² , linking group A and linking group L) further has a monovalent substituent, The position and number of monovalent substituents bonded to monovalent substituents which may be bonded to any one or more of ¹ , Q ² , linking group A and linking group L are not particularly limited.

N in the general formula (1) is a number of 1 to 3. In other words, the organometallic complex represented by the general formula (1) has one to three ligands. n is preferably determined according to the valence of the metal atom M. For example, when the metal atom M is a metal atom of the first group of the periodic table such as lithium and sodium, n is 1; and when the metal atom M is a second or twelfth group of the periodic table such as beryllium, magnesium and zinc, n is n. 2. When the metal atom M is a metal atom belonging to Group 3 or Group 13 of the periodic table, such as scandium, aluminum, or gallium, n is 3.
When n is plural, all the ligands of the organometallic complex represented by the general formula (1) may be the same, only a part may be the same, or all may be different. However, from the viewpoint of the difficulty and the purity of the synthesis of the organometallic complex, it is preferable that they are all the same. Further, since the valence of beryllium, magnesium, and zinc, which are preferable metal atoms M, is 2, n is preferably 2.

Amino groups of the organic metal complex represented by the general formula (1), of the aromatic hydrocarbon ring or aromatic heterocyclic ring indicated by nitrogen-containing heterocyclic structure, Q ² represented by Q ^1, coordinated to the metal atom M coupled to Q ² to which does not contain the nitrogen atom to which they are.

Specifically, the organometallic complex represented by the general formula (1) is preferably an organometallic complex represented by the following general formula (4).
The organometallic complex represented by the following general formula (4) is the same as the organometallic complex represented by the above general formula (1), wherein the metal atom M is beryllium, and the ring structure is composed of Q ¹ , Q ² and a linking group A. Is 7,8-benzoquinoline, the linking group L is a trimethylenelene group (—CH ₂ CH ₂ CH ₂ —), R ¹ and R ² are methyl groups, and n is 2. .

  Other preferable examples of the organometallic complex represented by the general formula (1) include, for example, organometallic complexes represented by the following general formulas (100) to (141). Among the organometallic complexes represented by the following general formulas (100) to (141), the organometallic complexes represented by the following general formulas (136) and (137) are particularly stable because they are very stable to electrical stimulation. preferable.

"Organic EL device"
Next, the organic EL device of the present invention will be described in detail with reference to examples.
FIG. 1 is a schematic cross-sectional view for explaining an example of the organic EL device of the present invention. The organic EL device 1 of this embodiment shown in FIG. 1 has a cathode 3, an inorganic oxide layer 4, an electron injection layer 5, a light emitting layer 6, a hole transport layer 7, It has a laminated structure in which the hole injection layer 8 and the anode 9 are formed in this order. The electron injection layer 5 in the organic EL device 1 shown in FIG. 1 contains the organometallic complex represented by the general formula (1).

The organic EL element 1 shown in FIG. 1 is an organic EL element (iOLED element) having an inverted structure in which a cathode 3 is arranged between a substrate 2 and a light emitting layer 6. The organic EL element 1 shown in FIG. 1 has an organic-inorganic hybrid type organic electroluminescent element in which a part (at least an inorganic oxide layer 4) constituting the organic EL element is formed using an inorganic compound. HOILED element).
The organic EL element 1 shown in FIG. 1 may be of a top emission type for extracting light to the side opposite to the substrate 2 side or a bottom emission type for extracting light to the substrate 2 side.
In the present embodiment, an organic EL element having an inverted structure will be described as an example. However, the organic EL element of the present invention may have a forward structure in which an anode is disposed between a substrate and a light emitting layer. Good. Examples of the organic EL element having a forward structure include, for example, a layer in which a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer are stacked in this order from the substrate side. Of these, some layers may not be present or may be plural, and there is no particular limitation. Even when the organic EL device of the present invention has a normal structure, the electron injection layer contains the organometallic complex represented by the general formula (1).

"substrate"
Examples of the material of the substrate 2 include a resin material and a glass material.
Examples of the resin material used for the substrate 2 include polyethylene terephthalate, polyethylene naphthalate, polypropylene, cycloolefin polymer, polyamide, polyether sulfone, polymethyl methacrylate, polycarbonate, and polyarylate. It is preferable to use a resin material as the material of the substrate 2 because the organic EL element 1 having excellent flexibility can be obtained.
Examples of the glass material used for the substrate 2 include quartz glass, soda glass, and the like.

In the organic EL device 1 of the present embodiment, as a material of the electron injection layer 5, an alkali metal or the like which is unstable in the air is not used. Therefore, if the water vapor permeability of the material used for sealing the organic EL element 1 is less than 1 × 10 ⁻³ g / m ² / day, the deterioration of the organic EL element 1 can be sufficiently suppressed. Therefore, as a material of the substrate 2 which is a member for sealing the organic EL element 1, for example, a resin material having a water vapor permeability of less than 1 × 10 ⁻³ g / m ² / day can be used. Moreover, in the organic EL element 1 of the present embodiment, sufficient durability can be obtained even when a resin material is used as the material of the substrate 2. It is not necessary to form a special barrier coat layer or the like for preventing intrusion of oxygen or water.

When the organic EL element 1 is of a bottom emission type, a transparent material is used as the material of the substrate 2.
When the organic EL element 1 is of a top emission type, not only a transparent material but also an opaque material can be used as the material of the substrate 2. Examples of the opaque substrate include a substrate made of a ceramic material such as alumina, a substrate formed by forming an oxide film (insulating film) on the surface of a metal plate such as stainless steel, and a substrate formed of a resin material.

  The average thickness of the substrate 2 can be determined according to the material of the substrate 2 and the like, and is preferably 0.1 to 30 mm, and more preferably 0.1 to 10 mm. The average thickness of the substrate 2 can be measured by a digital multimeter and a caliper.

"cathode"
The cathode 3 is formed directly on the substrate 2.
Examples of the material of the cathode 3 include oxides such as ITO (indium tin oxide), IZO (indium zinc oxide), FTO (tin oxide fluoride), In ₃ O ₃ , SnO ₂ , Sn-containing SnO ₂ , and Al-containing ZnO. Conductive materials. Among them, it is preferable to use ITO, IZO, and FTO as the material of the cathode 3.
The average thickness of the cathode 3 is not particularly limited, but is preferably from 10 to 500 nm, more preferably from 100 to 200 nm.
The average thickness of the cathode 3 can be measured by a stylus type profilometer and spectroscopic ellipsometry.

"Oxide layer"
The oxide layer 4 has a function as an electron injection layer and / or a function as a cathode.
The oxide layer 4 is a layer of a semiconductor or an insulator laminated thin film, and is one of a layer composed of a single metal oxide, a layer in which two or more metal oxides are mixed, and a layer composed of a single metal oxide. Alternatively, a layer in which both are laminated, or a layer in which two or more metal oxides are mixed.
Examples of the metal element constituting the metal oxide forming the oxide layer 4 include magnesium, calcium, strontium, barium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, indium, gallium, Examples include iron, cobalt, nickel, copper, zinc, cadmium, aluminum, and silicon.

When the oxide layer 4 includes a layer in which two or more types of metal oxides are mixed, at least one of the metal elements constituting the metal oxide is formed from magnesium, aluminum, calcium, zirconium, hafnium, silicon, titanium, or zinc. Preferably, the layer is
When the oxide layer 4 is a layer composed of a single metal oxide, a layer composed of a metal oxide selected from the group consisting of magnesium oxide, aluminum oxide, zirconium oxide, hafnium oxide, silicon oxide, titanium oxide, and zinc oxide It is preferred that

  The oxide layer 4 is a layer in which one or both of a layer in which two or more metal oxides are mixed and a layer made of a single metal oxide are stacked, or a layer in which two or more metal oxides are mixed. In some cases, titanium oxide / zinc oxide, titanium oxide / magnesium oxide, titanium oxide / zirconium oxide, titanium oxide / aluminum oxide, titanium oxide / hafnium oxide, titanium oxide / silicon oxide, zinc oxide / magnesium oxide, zinc oxide / zirconium oxide , Zinc oxide / hafnium oxide, zinc oxide / silicon oxide, calcium oxide / aluminum oxide, lamination and / or mixture of two kinds of metal oxides, titanium oxide / zinc oxide / magnesium oxide, titanium oxide / Zinc oxide / zirconium oxide, titanium oxide / zinc oxide / aluminum oxide, titanium oxide / Zinc / hafnium oxide, titanium oxide / zinc oxide / silicon oxide, indium oxide / gallium oxide / zinc oxide, from a combination of three kinds of metal oxide stack and / or mixed mention may be made of those selected.

The oxide layer 4 may include IGZO which is an oxide semiconductor and / or 12CaO.7Al ₂ O ₃ which is an electride, which shows good characteristics as a special composition. The average thickness of the oxide layer 4 is not particularly limited, but is preferably 1 to 1000 nm, and more preferably 2 to 100 nm.
The average thickness of the oxide layer 4 can be measured by a stylus type profilometer and spectroscopic ellipsometry.

"Electron injection layer"
The electron injection layer 5 contains an organometallic complex represented by the general formula (1). The organometallic complex represented by the general formula (1) contained in the electron injection layer 5 may be only one kind or two or more kinds. As the organometallic complex represented by the general formula (1), it is preferable to use the organometallic complex represented by the general formula (4).

The average thickness of the electron injection layer 5 is preferably 5 to 100 nm, more preferably 10 to 50 nm. When the average thickness of the electron injection layer 5 is 5 nm or more, the electron injection layer 5 is formed using a method of applying a solution containing an organometallic complex, whereby the electron injection layer 5 having a smooth surface is obtained. Leakage during manufacturing of the organic EL element 1 can be sufficiently prevented. When the average thickness of the electron injection layer 5 is 100 nm or less, an increase in the driving voltage of the organic EL element 1 due to the provision of the electron injection layer 5 can be sufficiently suppressed.
The average thickness of the electron injection layer 5 can be measured by, for example, a stylus-type step meter or spectroscopic ellipsometry.

"Emitting layer"
As a material for forming the light emitting layer 6, any material that can be generally used as a material for the light emitting layer 6 may be used, or a mixture of these materials may be used. Specifically, for example, bis [2- (2-benzothiazolyl) phenolato] zinc (II) (Zn (BTZ) ₂ ) and tris [1-phenylisoquinoline] iridium (III) (Ir ( piq) ₃ ).
The material forming the light emitting layer 6 may be a low molecular compound or a high molecular compound. In the present invention, the low molecular material means a material that is not a high molecular material (polymer), and does not necessarily mean an organic compound having a low molecular weight.

  Examples of the polymer material forming the light emitting layer 6 include polyacetylene-based compounds such as trans-polyacetylene, cis-polyacetylene, poly (di-phenylacetylene) (PDPA), and poly (alkylphenylacetylene) (PAPA); (Para-phenvinylene) (PPV), poly (2,5-dialkoxy-para-phenylenevinylene) (RO-PPV), cyano-substituted-poly (para-fenvinylene) (CN-PPV), poly (2 Polyparaphenylenevinylene-based compounds such as -dimethyloctylsilyl-para-phenylenevinylene) (DMOS-PPV) and poly (2-methoxy, 5- (2'-ethylhexoxy) -para-phenylenevinylene) (MEH-PPV) Poly (3-alkylthiophene) (PAT), poly (oxypropyl); Polythiophene compounds such as pyrene) triol (POPT); poly (9,9-dialkylfluorene) (PDAF), poly (dioctylfluorene-alto-benzothiadiazole) (F8BT), α, ω-bis [N, N ′ -Di (methylphenyl) aminophenyl] -poly [9,9-bis (2-ethylhexyl) fluorene-2,7-diyl] (PF2 / 6am4), poly (9,9-dioctyl-2,7-divinylene) Polyfluorene-based compounds such as fluorenyl-ortho-co (anthracene-9,10-diyl); poly (para-phenylene) (PPP), poly (1,5-dialkoxy-para-phenylene) (RO- Polyparaphenylene-based compounds such as PPP); polycarbazoles such as poly (N-vinylcarbazole) (PVK) Compounds; Polysilane compounds such as poly (methylphenylsilane) (PMPS), poly (naphthylphenylsilane) (PNPS), and poly (biphenylylphenylsilane) (PBPS); No. 2011-6457, and the like.

Examples of the low-molecular material forming the light-emitting layer 6 include a three-coordinate iridium complex having 2,2′-bipyridine-4,4′-dicarboxylic acid as a ligand, and factory (2-phenylpyridine) Iridium (Ir (ppy) ₃ ), 8-hydroxyquinoline aluminum (Alq ₃ ), tris (4-methyl-8 quinolinolate) aluminum (III) (Almq ₃ ), 8-hydroxyquinoline zinc (Znq ₂ ), (1, 10-phenanthroline) -tris- (4,4,4-trifluoro-1- (2-thienyl) -butane-1,3-dionate) europium (III) (Eu (TTA) ₃ (phen)), 2, Various metal complexes such as 3,7,8,12,13,17,18-octaethyl-21H, 23H-porphine platinum (II); Benzene compounds such as benzene (DSB) and diaminodistyrylbenzene (DADSB); naphthalene compounds such as naphthalene and nile red; phenanthrene compounds such as phenanthrene; chrysene compounds such as chrysene and 6-nitrochrysene. Perylene compounds such as perylene, N, N'-bis (2,5-di-t-butylphenyl) -3,4,9,10-perylene-di-carboximide (BPPC); Coronene compounds; Anthracene compounds such as anthracene and bisstyrylanthracene; Pyrene compounds such as pyrene; 4- (di-cyanomethylene) -2-methyl-6- (para-dimethylaminostyryl) -4H-pyran Pyran-based compounds such as (DCM); Stilbene compounds such as stilbene; thiophene compounds such as 2,5-dibenzoxazole thiophene; benzooxazole compounds such as benzoxazole; benzimidazole compounds such as benzimidazole; 2,2 ′ Benzothiazole-based compounds such as-(para-phenylenedivinylene) -bisbenzothiazole; butadiene-based compounds such as bistyryl (1,4-diphenyl-1,3-butadiene) and tetraphenylbutadiene; and naphthalimide Naphthalimide compounds; Coumarin compounds such as coumarin; Perinone compounds such as perinone; Oxadiazole compounds such as oxadiazole; Aldazine compounds; 1,2,3,4,5-pentaphenyl- 1,3-cyclopenta Cyclopentadiene compounds such as ene (PPCP); quinacridone compounds such as quinacridone and quinacridone red; pyridine compounds such as pyrrolopyridine and thiadiazolopyridine; 2,2 ′, 7,7′-tetraphenyl- Spiro compounds such as 9,9′-spirobifluorene; phthalocyanines (H ₂ Pc), metal or non-metal phthalocyanine compounds such as copper phthalocyanine; and further JP-A-2009-155325, JP-A-2011-184430 And boron compound materials described in Japanese Patent Application No. 2011-6458.

The average thickness of the light emitting layer 6 is not particularly limited, but is preferably from 10 to 150 nm, and more preferably from 20 to 100 nm.
The average thickness of the light emitting layer 6 may be measured by a stylus type step meter or may be measured by a quartz crystal film thickness meter when the light emitting layer 6 is formed.

"Hole transport layer"
As the hole transporting organic material used for the hole transporting layer 7, various p-type high molecular materials (organic polymers) and various p-type low molecular materials can be used alone or in combination.
Specifically, as a material of the hole transport layer 7, for example, N, N'-di (1-naphthyl) -N, N'-diphenyl-1,1'-biphenyl-4,4'-diamine (α -NPD), polyarylamine, fluorene-arylamine copolymer, fluorene-bithiophene copolymer, poly (N-vinylcarbazole), polyvinylpyrene, polyvinylanthracene, polythiophene, polyalkylthiophene, polyhexylthiophene, poly (p -Phenylene vinylene), polytinylene vinylene, pyrene formaldehyde resin, ethyl carbazole formaldehyde resin or derivatives thereof. These materials of the hole transport layer 7 can be used as a mixture with another compound. As an example, poly (3,4-ethylenedioxythiophene / styrenesulfonic acid) (PEDOT / PSS) or the like is given as a mixture containing polythiophene used as a material of the hole transport layer 7.

The average thickness of the hole transport layer 7 is not particularly limited, but is preferably 10 to 150 nm, and more preferably 20 to 100 nm.
The average thickness of the hole transport layer 7 can be measured by, for example, a stylus-type step meter or spectroscopic ellipsometry.

"Hole injection layer"
The hole injection layer 8 may be made of an inorganic material or may be made of an organic material. An inorganic material is more stable than an organic material, and thus is more likely to have higher resistance to oxygen and water than an organic material.
The inorganic material is not particularly limited, and for example, one or more metal oxides such as vanadium oxide (V ₂ O ₅ ), molybdenum oxide (MoO ₃ ), and ruthenium oxide (RuO ₂ ) are used. it can.
Examples of the organic material include dipyrazino [2,3-f: 2 ′, 3′-h] quinoxaline-2,3,6,7,10,11-hexacarbonitrile (HAT-CN) and 2,3,5 6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane (F4-TCNQ) or the like can be used.

The average thickness of the hole injection layer 8 is not particularly limited, but is preferably 1 to 1000 nm, and more preferably 5 to 50 nm.
The average thickness of the hole injection layer 8 can be measured at the time of film formation using a quartz oscillator film thickness meter.

"anode"
Examples of the material used for the anode 9 include Au, Pt, Ag, Cu, Al, and alloys containing these. Among them, it is preferable to use Au, Ag, and Al as the material of the anode 9.
The average thickness of the anode 9 is not particularly limited, but is preferably 10 to 1000 nm, and more preferably 30 to 150 nm. Further, even when an opaque material is used as the material of the anode 9, for example, by setting the average thickness to about 10 to 30 nm, the anode 9 can be used as a transparent anode in a top emission type organic EL device.
The average thickness of the anode 9 can be measured at the time of forming the anode 9 by using a quartz oscillator film thickness meter.

"Sealing"
The organic EL element 1 shown in FIG. 1 may be sealed if necessary.
For example, the organic EL element 1 shown in FIG. 1 includes a sealing container (not shown) having a concave space for accommodating the organic EL element 1 and an adhesive for bonding the edge of the sealing container and the substrate 2. It may be sealed. Also, for example, the organic EL element 1 shown in FIG. 1 includes a plate member (not shown) disposed on the anode 9 and a frame member (along the edge of the plate member on the side facing the anode 9). (Not shown) and an adhesive for bonding between the plate member and the frame member and between the frame member and the substrate 2.

  When the organic EL element 1 is sealed using a sealing container or a sealing member, a desiccant that absorbs moisture may be arranged in the sealing container or inside the sealing member. Further, a material that absorbs moisture may be used for the sealing container or the sealing member. A space may be formed in the sealed container or inside the sealing member.

As a material of a sealing container or a sealing member used for sealing the organic EL element 1 shown in FIG. 1, a resin material, a glass material, or the like can be used. Examples of the resin material and the glass material used for the sealing container or the sealing member include the same materials as those used for the substrate 2. The plate member and the frame member of the sealing member may be the same material or different materials.
In the organic EL device 1 of the present embodiment, as a material of the electron injection layer 5, an alkali metal or the like which is unstable in the air is not used. Therefore, if the water vapor permeability of the sealing container or the sealing member is less than 1 × 10 ⁻³ g / m ² / day, the deterioration of the organic EL element 1 can be sufficiently suppressed. Therefore, it is possible to use a resin material having a water vapor permeability of less than 1 × 10 ⁻³ g / m ² / day as a material of the sealing container or the sealing member.

"Manufacturing method of organic EL element"
Next, a method for manufacturing the organic EL element 1 shown in FIG. 1 will be described as an example of the method for manufacturing the organic EL element of the present invention.
In manufacturing the organic EL device 1 shown in FIG. 1, first, a cathode 3 is formed on a substrate 2.
The cathode 3 can be formed by a sputtering method, a vacuum deposition method, a sol-gel method, a spray pyrolysis (SPD) method, an atomic layer deposition (ALD) method, a gas phase film forming method, a liquid phase film forming method, or the like. For forming the cathode 3, a method of joining metal foils may be used.

Next, an inorganic oxide layer 4 is formed on the cathode 3.
The oxide layer 4 is formed using, for example, a spray pyrolysis method, a sol-gel method, a sputtering method, a vacuum evaporation method, or the like. The surface of the oxide layer 4 thus formed may not be smooth but have irregularities. The oxide layer 4 may not be provided.

Next, the electron injection layer 5 is formed on the oxide layer 4.
The electron injection layer 5 is preferably formed by applying a solution containing the organometallic complex represented by the general formula (1).
The solution containing the organometallic complex represented by the general formula (1) is obtained by dissolving the organometallic complex represented by the general formula (1) in a solvent.

As a solvent used for dissolving the organometallic complex represented by the general formula (1), for example, an inorganic solvent, an organic solvent, a mixed solvent containing these, or the like can be used.
Examples of the inorganic solvent include nitric acid, sulfuric acid, ammonia, hydrogen peroxide, water, carbon disulfide, carbon tetrachloride, ethylene carbonate and the like.

  Examples of the organic solvent include ketone solvents such as methyl ethyl ketone (MEK), acetone, diethyl ketone, methyl isobutyl ketone (MIBK), methyl isopropyl ketone (MIPK), cyclohexanone, methanol, ethanol, isopropanol, ethylene glycol, diethylene glycol (DEG), Alcohol solvents such as glycerin, diethyl ether, diisopropyl ether, 1,2-dimethoxyethane (DME), 1,4-dioxane, tetrahydrofuran (THF), tetrahydropyran (THP), anisole, diethylene glycol dimethyl ether (diglyme), diethylene glycol ethyl Ether solvents such as ether (carbitol), and cellosolves such as methyl cellosolve, ethyl cellosolve, and phenyl cellosolve Solvents, aliphatic hydrocarbon solvents such as hexane, pentane, heptane, and cyclohexane; aromatic hydrocarbon solvents such as toluene, xylene, and benzene; aromatic heterocycles such as pyridine, pyrazine, furan, pyrrole, thiophene, and methylpyrrolidone Compound solvents, amide solvents such as N, N-dimethylformamide (DMF) and N, N-dimethylacetamide (DMA), halogen compound solvents such as chlorobenzene, dichloromethane, chloroform and 1,2-dichloroethane, ethyl acetate, Ester solvents such as methyl acetate and ethyl formate; sulfur compound solvents such as dimethyl sulfoxide (DMSO) and sulfolane; nitrile solvents such as acetonitrile, propionitrile and acrylonitrile; formic acid, acetic acid, trichloroacetic acid, trifluoroacetic acid and the like Organic acid solution Various organic solvents and the like such as.

  Examples of the method of applying the solution containing the organometallic complex represented by the general formula (1) include spin coating, casting, microgravure coating, gravure coating, bar coating, roll coating, and wire bar coating. Various coating methods such as a method, a dip coating method, a spray coating method, a screen printing method, a flexographic printing method, an offset printing method, and an ink jet printing method can be used.

  In the electron injection layer 5 of the present embodiment, the driving voltage of the organic EL element 1 by providing the electron injection layer 5 is higher than that of, for example, an electron injection layer made of polyethyleneimine due to the electron transportability of the organometallic complex. Can be suppressed. Therefore, in order to obtain a smooth surface by covering the unevenness formed on the surface on which the electron injection layer 5 is formed (the upper surface of the oxide layer 4 in the present embodiment), the electron injection layer 5 must have a sufficient thickness. Can be formed.

Next, the light emitting layer 6 and the hole transport layer 7 are formed on the electron injection layer 5 in this order.
The method for forming the light-emitting layer 6 and the hole transport layer 7 is not particularly limited, and conventionally known various formation methods may be appropriately used according to the characteristics of the material used for the light-emitting layer 6 or the hole transport layer 7. it can.

  Specifically, as a method of forming the light emitting layer 6 and the hole transport layer 7, a coating method of applying an organic compound solution containing an organic compound to be the light emitting layer 6 or the hole transport layer 7, a vacuum deposition method, an ESDUS ( Evaporative Spray Deposition from Ultra-dilute Solution) method and the like. Among these methods of forming the light emitting layer 6 and the hole transport layer 7, it is particularly preferable to use a coating method. In addition, when the solvent solubility of the organic compound which becomes the light emitting layer 6 or the hole transport layer 7 is low, it is preferable to use a vacuum evaporation method or an ESDUS method.

When the light emitting layer 6 and the hole transport layer 7 are formed using a coating method, an organic compound to be the light emitting layer 6 or the hole transport layer 7 is dissolved in a solvent to form the light emitting layer 6 or the hole transport layer 7. An organic compound solution containing an organic compound to be 7 is formed.
The solvent used for dissolving the organic compound to be the light emitting layer 6 or the hole transport layer 7 is a solvent used for dissolving the organometallic complex represented by the general formula (1) when forming the electron injection layer 5. And the same thing can be used.

  As a solvent used for dissolving the organic compound to be the light emitting layer 6 or the hole transport layer 7, a non-polar solvent is preferable among the above solvents. Specifically, for example, aromatic hydrocarbon solvents such as xylene, toluene, cyclohexylbenzene, dihydrobenzofuran, trimethylbenzene, and tetramethylbenzene; and aromatic complex solvents such as pyridine, pyrazine, furan, pyrrole, thiophene, and methylpyrrolidone. A cyclic compound-based solvent, an aliphatic hydrocarbon-based solvent such as hexane, pentane, heptane, and cyclohexane are preferable, and these can be used alone or in combination.

  As a method for applying an organic compound solution containing an organic compound to be the light emitting layer 6 or the hole transport layer 7, there are spin coating, casting, microgravure coating, gravure coating, bar coating, roll coating, wire coating, and the like. Various coating methods such as a bar coating method, a dip coating method, a spray coating method, a screen printing method, a flexographic printing method, an offset printing method, and an ink jet printing method can be used. Among these coating methods, it is preferable to use a spin coating method or a slit coating method in that the film thickness is more easily controlled.

Next, a hole injection layer 8 and an anode 9 are formed on the hole transport layer 7 in this order.
When the hole injection layer 8 is made of an inorganic material, the hole injection layer 8 can be formed, for example, in the same manner as the oxide layer 4.
When the hole injection layer 8 is made of an organic material, the hole injection layer 8 can be formed, for example, in the same manner as the light emitting layer 6 and the hole transport layer 7.
The anode 9 can be formed, for example, in the same manner as the cathode 3.
Through the above steps, the organic EL device 1 shown in FIG. 1 is obtained.

"Sealing method"
When the organic EL element 1 shown in FIG. 1 is sealed, it can be sealed using a normal method used for sealing the organic EL element.
For example, a method of disposing the organic EL element 1 in a sealed container having a concave space for accommodating the organic EL element 1 in an inert gas, and bonding the edge of the sealed container and the substrate 2 with an adhesive. Can be used. Further, for example, a sealing member composed of a plate member and a frame member arranged along an edge of the plate member facing the anode 9 is disposed on the anode 9 of the organic EL element 1. A method of bonding between the frame member and the frame member and between the frame member and the substrate 2 with an adhesive may be used.

The organic EL device 1 shown in FIG. 1 has an electron injection layer 5 containing the organometallic complex represented by the general formula (1). Therefore, in the organic EL device 1 shown in FIG. 1, electron injection from the cathode 3 to the light emitting layer 6 is promoted. Hereinafter, the reason for this will be described with reference to FIG. 2 by taking the organometallic complex represented by the general formula (4), which is a specific example of the organometallic complex represented by the general formula (1), as an example.
FIG. 2 is an explanatory diagram for explaining the orientation of the organometallic complex in the organic EL device of the present invention, and is a perspective view showing a molecular model (molecular model) of the organometallic complex on the inorganic oxide layer. It is. In FIG. 2, atoms are represented by spheres, and bonds between the atoms are represented by bars. The small sphere in FIG. 2 indicates a hydrogen atom, and the large sphere without a notation indicates a carbon atom.

In the organometallic complex represented by FIG. 2 and the general formula (4), n in the general formula (1) is 2. As shown in FIG. 2, this organometallic complex has two 7,8-benzoquinoline nitrogen atoms coordinated as ligands to a metal atom M (from the nitrogen atom in the general formula (1) to the metal atom M). (Dotted line to the atom M) has a large intramolecular dipole. Further, the amino group in this organometallic complex is bonded to a benzene ring (Q ² in general formula (1)) that is not bonded to a pyridine ring (Q ¹ in general formula (1)) of 7,8-benzoquinoline. are, trimethylene Ren group as a linking group L - is coupled to the end of the _{(-CH 2 CH 2 CH 2)} .

  When the electron injection layer 5 containing the organometallic complex represented by the general formula (4) is formed in contact with the oxide layer 4, the amino group in the organometallic complex and the material of the oxide layer 4 are formed as shown in FIG. Are coordinated to form a dipole (interface dipole), and the amino group in the organometallic complex is arranged close to the oxide layer 4. Then, depending on the positional relationship between the amino group in the organometallic complex and the coordination bond between the metal atom M and the ligand, the organometallic complex is oriented in a specific direction as shown in FIG. That is, the organometallic complex is oriented such that the pyridine ring side of 7,8-benzoquinoline is far from the oxide layer 4 and the benzene ring side not bonded to the pyridine ring is close to the oxide layer 4.

  As a result, as shown in FIG. 2, the vector obtained by adding two dipoles (intramolecular dipoles) generated by the coordination bond between the metal atom M of the organometallic complex and the two ligands is the same as the cathode 3 side. From the direction toward the light emitting layer 6 side. In addition, as shown in FIG. 2, the direction of the intramolecular dipole is the same as the direction of the interface dipole generated by the coordination bond between the amino group and the material of the oxide layer 4. Therefore, the dipole moment (vector) of the entire electron injection layer 5 containing the organometallic complex is in the direction from the cathode 3 to the light emitting layer 6 due to the addition of the intramolecular dipole and the interface dipole. Therefore, in the organic EL device 1 having the electron injection layer 5, the electron injection from the cathode 3 to the light emitting layer 6 is promoted.

  The inventor estimated the intramolecular dipole of the organometallic complex represented by the general formula (4) by molecular orbital calculation using the Gaussian 03 program. As a result, the value of the intramolecular dipole of this organometallic complex was 5.5 Debye, which was extremely large. This indicates that the use of the organometallic complex represented by the general formula (4) as a material of the electron injection layer of the organic EL element can overcome a large barrier which has been difficult in the past. .

  When the oxide layer 4 of the organic EL element 1 is not formed, an interface dipole is generated by coordination bond between the cathode 3 and an amino group of the organometallic complex contained in the electron injection layer 5. Also in this case, as in the case where the oxide layer 4 is formed, two dipoles (intramolecular dipoles) generated by the coordination bond between the metal atom M of the organometallic complex and the two ligands are added. The combined vector is in a direction from the cathode 3 side to the light emitting layer 6 side. Also, when the cathode 3 and the electron injection layer 5 are in contact with each other, similarly to the case where the oxide layer 4 is formed, the direction of the interface dipole is the same as the direction from the cathode 3 toward the light emitting layer 6. Become.

As described above, in the organic EL device 1 having the electron injection layer 5, electron injection from the cathode 3 to the light emitting layer 6 is promoted, so that high luminous efficiency can be obtained with a low driving voltage.
In the organic EL device 1 shown in FIG. 1, when the inorganic oxide layer 4 is formed between the cathode 3 and the electron injection layer 5, electron injection from the cathode 3 can be further promoted.
Conventionally, in an organic EL element having a general inverted structure, an oxide layer for promoting electron injection is formed on the substrate side of the electron injection layer (for example, see Non-Patent Document 6). On the other hand, in the organic EL device 1 of the present embodiment, even if the inorganic oxide layer 4 is not formed between the cathode 3 and the electron injection layer 5, electrons can be sufficiently injected from the cathode 3 to the light emitting layer 6. Can be promoted. It is preferable that the oxide layer 4 is not formed because productivity is improved. Further, as the inorganic oxide layer 4, a layer having no function of promoting electron injection may be formed.

Further, the organometallic complex contained in the electron injection layer 5 is electrically stable as compared with a material containing an amino group containing an NH bond. Therefore, the organic EL element 1 shown in FIG. 1 is less likely to be deteriorated due to the deterioration of the electron injection layer 5, has excellent durability when continuously driven, and has a long life.
Further, the organic EL element 1 shown in FIG. 1 has higher resistance to oxygen and water than an organic EL element having an electron injection layer containing an alkali metal, and thus does not require strict sealing. Therefore, in the organic EL element 1, by using a resin material for one or both of the material of the substrate 2 and the material of the sealing container or the sealing member, the organic EL element 1 having excellent flexibility can be obtained. .

The organic EL element 1 shown in FIG. 1 is an organic EL element (iOLED element) having an inverted structure. In the iOLED element, the speed of holes injected from the anode to the light emitting layer is higher than that of the organic EL element having the forward structure in which the anode is disposed between the substrate and the light emitting layer, and the electron injected from the cathode to the light emitting layer. Speed tends to be slow. For this reason, conventionally, in the organic EL element having the inverted structure, the holes injected from the anode may not be sufficiently used for light emission in some cases.
On the other hand, since the organic EL element 1 of the present embodiment has the electron injection layer 5 containing the organometallic complex represented by the general formula (1), injection of electrons from the cathode 3 to the light emitting layer 6 is performed. The speed is high, and holes injected from the anode 9 can be sufficiently utilized for light emission.

  In the present embodiment, when the electron injection layer 5 is formed by a method of applying a solution containing the organometallic complex represented by the general formula (1), the electron injection layer 5 is formed by using a method other than the coating method. Compared with the case where the organic metal complex is formed, the charge of the nitrogen atom of the amino group of the organometallic complex is more likely to form a coordination bond with the oxide layer 4. Therefore, the organometallic complex is easily oriented so that the dipole moment of the entire electron injection layer 5 is in the direction from the cathode 3 side to the light emitting layer 6 side. Therefore, the electron injection layer 5 having a higher electron injection effect from the cathode 3 to the light emitting layer 6 can be obtained.

  In the present embodiment, when the electron injection layer 5 is formed by a method of applying a solution containing the organometallic complex represented by the general formula (1), the electron injection layer 5 is formed by using a method other than the coating method. An electron injection layer 5 having a smooth surface is obtained as compared with the case where the layer is formed. As a result, the crystallization of the light emitting layer 6 formed after the formation of the electron injection layer 5 is suppressed, and uniform surface light emission is obtained, and the organic EL element 1 in which the leak current is suppressed is obtained.

  In this embodiment, when the electron injection layer 5 is formed on the inorganic oxide layer 4 by applying a solution containing an organometallic complex, the surface of the oxide layer 4 has irregularities. Also, the surface of the formed electron injection layer 5 becomes smooth. Therefore, even if the surface of the oxide layer 4 formed in the present embodiment has irregularities and the luminescent layer 6 formed after the formation of the electron injection layer 5 is made of a material that is easily crystallized, the luminescent layer 6 can be effectively suppressed.

"Other examples"
FIG. 3 is a schematic sectional view for explaining another example of the organic EL device of the present invention. The difference between the organic EL element 11 shown in FIG. 3 and the organic EL element 1 shown in FIG. 1 is that the electron transport layer 10 is provided between the electron injection layer 5 and the light emitting layer 6 in the organic EL element 1 shown in FIG. Only the point provided. Therefore, in the organic EL element 11 shown in FIG. 3, the same members as those of the organic EL element 1 shown in FIG.

As a material of the electron transport layer 10, any material that can be generally used as a material of the electron transport layer may be used.
Specifically, as a material of the electron transport layer 10, a phosphine oxide derivative such as phenyl-dipyrenylphosphine oxide (POPy ₂ ), tris-1,3,5- (3 ′-(pyridine-3 ″-) Pyridine) derivatives such as (yl) phenyl) benzene (TmPyPhB), quinoline derivatives such as (2- (3- (9-carbazolyl) phenyl) quinoline (mCQ)), 2-phenyl-4,6-bis (3 Pyrimidine derivatives such as 5-dipyridylphenyl) pyrimidine (BPyPPM), pyrazine derivatives, phenanthroline derivatives such as bathophenanthroline (BPhen), 2,4-bis (4-biphenyl) -6- (4 ′-(2-pyridinyl) ) -4-biphenyl)-[1,3,5] triazine (MPT); Triazole derivatives such as nyl-4- (1'-naphthyl) -5-phenyl-1,2,4-triazole (TAZ), oxazole derivatives, 2- (4-biphenylyl) -5- (4-tert-butyl Oxadiazole derivatives such as phenyl-1,3,4-oxadiazole) (PBD), 2,2 ′, 2 ″-(1,3,5-benzotriyl) -tris (1-phenyl-1- Imidazole derivatives such as H-benzimidazole) (TPBI), aromatic tetracarboxylic anhydrides such as naphthalene and perylene, bis [2- (2-hydroxyphenyl) benzothiazolate] zinc (Zn (BTZ) ₂ ), tris ( Various metal complexes represented by 8-hydroxyquinolinato) aluminum (Alq3) and the like, 2,5-bis (6 ′-(2 ′, 2 ″ -bipyridyl))-1 1-dimethyl-3,4-organic silane derivatives typified by silole derivatives such as diphenyl silole (PyPySPyPy), and the like, can be used alone or in combination of two or more thereof. Among these electron-transporting layer 10 material, in particular, phosphine oxide derivatives such as Popy _2, metal complexes such as Alq _3, it is preferable to use pyridine derivatives such as TmPyPhB.

The average thickness of the electron transport layer 10 is not particularly limited, but is preferably from 10 to 150 nm, and more preferably from 20 to 100 nm.
The average thickness of the electron transport layer 10 can be measured by a stylus-type step meter and spectroscopic ellipsometry.
The method for forming the electron transport layer 10 is not particularly limited, and conventionally known various formation methods can be appropriately used according to the characteristics of the material used for the electron transport layer 10.

  The organic EL element 11 shown in FIG. 3 has the electron injection layer 5 containing the organometallic complex represented by the general formula (1), like the organic EL element 1 shown in FIG. Therefore, also in the organic EL element 11 shown in FIG. 3, high luminous efficiency can be obtained at a low driving voltage due to the excellent electron injection property of the electron injection layer 5. In addition, the deterioration due to the deterioration of the electron injection layer 5 hardly occurs, the durability during continuous driving is excellent, and the life is long.

The organic EL device of the present invention is not limited to the organic EL device shown in FIG. 1 or FIG.
Specifically, in the organic EL device using the organometallic complex of the present invention, it is sufficient that the cathode 3, the electron injection layer 5, the light emitting layer 6, and the anode 9 are formed on the substrate 2. The inorganic oxide layer 4, the electron transport layer, the hole transport layer, and the hole injection layer may be formed as needed.
Further, the organic EL element of the present invention may have another layer between the layers shown in FIG. 1 or FIG. Each of the cathode 3, the oxide layer 4, the electron injection layer 5, the electron transport layer, the light emitting layer 6, the hole transport layer 7, the hole injection layer 8, and the anode 9 shown in FIG. It may be composed of layers, or may be composed of two or more layers.

  When the organic EL elements 1 and 11 having the above configuration include only one of the hole transport layer 7 and the hole injection layer 8, one of the layers is adjacent to the light emitting layer 6 and the anode 9. When both the hole transport layer 7 and the hole injection layer 8 are not provided, the light emitting layer 6 and the anode 9 are stacked adjacent to each other.

The organic EL device of the present invention may have, for example, a hole blocking layer, an electronic device layer, and the like, if necessary, for the purpose of further improving the characteristics of the organic EL device.
As a material for forming these layers, a material usually used for forming these layers can be used. Further, as a method for forming these layers, a method generally used for forming these layers can be used.

  In the above-described embodiment, an organic EL element (iOLED element) having an inverted structure in which the cathode 3 is disposed between the substrate 2 and the light emitting layer 6 has been described as an example. May have a sequential structure in which an anode is arranged.

  In an organic EL element having a forward structure, an electron injection layer is usually formed on a light emitting layer. Even in this case, an interface dipole is generated by the coordination bond between the oxide layer (or the cathode) formed on the electron injection layer and the amino group of the organometallic complex contained in the electron injection layer. In this case as well, similarly to the case where the electron injection layer 5 is formed on the oxide layer 4 in the organic EL device 1 shown in FIG. 1, the coordination bond between the metal atom M of the organometallic complex and the ligand is obtained. The direction of the generated dipole (intramolecular dipole) and the direction of the interface dipole are the directions from the cathode 3 side toward the light emitting layer 6 side.

  In the organic EL device of the present invention, the luminescent color can be changed by appropriately selecting a material such as a luminescent layer, or a desired luminescent color can be obtained by using a color filter or the like in combination. Therefore, it can be suitably used as a light emitting portion or a lighting device of a display device.

The display device of the present invention includes an organic EL element having an electron injection layer containing the organometallic complex of the present invention and having excellent electron injection properties and durability. Therefore, it is preferable as a display device.
Further, the lighting device of the present invention includes an organic EL element having an electron injection layer containing the organometallic complex of the present invention and having excellent electron injection properties and durability. Therefore, it is preferable as a lighting device.

The organometallic complex of the present invention is not limited to the above-described embodiment. For example, in Non-Patent Documents 3 and 5, polyethyleneimine is used for other devices (solar cells, lighting, transistors). Similarly, it can be used for devices such as organic thin-film solar cells.
The organic thin-film solar cell of the present invention includes an electron-injecting layer containing the organometallic complex of the present invention and having excellent electron-injecting properties and durability. Therefore, it is preferable as an organic thin film solar cell.

  Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to only these examples. Unless otherwise specified, “%” means “mol%”.

`` Synthesis method of organometallic complex ''
An organometallic complex represented by the general formula (4), which is a specific example of the organometallic complex represented by the general formula (1), was synthesized by the method described below.
A compound represented by the following general formula (200) (10 g, 51.2 mmol, 1.0 eq. (Equivalent)) and anhydrous DMF (N, N-dimethylformamide) (100 mL) were added to a 200 mL reactor. Sodium hydride (2.46 g, 61.5 mmol, 1.2 eq.) Was added to the obtained solution at room temperature, and the mixture was stirred for 1 hour. Thereafter, aryl bromide (6.5 mL, 76.8 mmol, 1.5 eq.) Was added dropwise, and the mixture was stirred at room temperature for 1 hour. The reaction solution was poured into water (500 mL), and extracted twice with ethyl acetate (100 mL). . Thereafter, the organic layer was washed with water and saturated saline in this order, dried over anhydrous MgSO _4, and the solution was concentrated to obtain a brown viscous liquid (14.9 g).
This was recrystallized using IPE (isopropyl ether) and hexane to obtain a compound (12.2 g, 51.9 mmol, quant) represented by the following general formula (201) as a beige powder.

Next, a compound (1 g, 4.25 mmol, 1.0 eq.) Represented by the following general formula (201) and diethylene glycol (30 mL) were added to a 100 mL reactor, and the mixture was heated with stirring at 200 ° C. for 18 hours. Water (200 mL) was added to the obtained reaction solution to quench it, and ethyl acetate (50 mL) was added to separate the reaction solution into two layers, an aqueous layer and an organic layer. Then, the aqueous layer was extracted twice with ethyl acetate (50 mL), and the organic layer was collected, washed with water and saturated saline in this order, and dried using anhydrous MgSO ₄ . Thereafter, the solution was concentrated to obtain a pale yellow liquid (0.87 g).
This was purified by column chromatography (SiO ₂ : 40 g, heptane / ethyl acetate = 7/1 → 5/1), and a light yellow liquid compound (0.57 g, represented by the following general formula (202), (2.42 mmol, 56% yield).

The compound represented by the above general formula (202) (5 g, 21.3 mmol, 1.0 eq.) And tetrahydrofuran (THF) (30 mL) were added to a 200 mL reactor. This solution was cooled to 5 ° C., and an Et ₂ O (diethyl ether) solution (7.8 mL, 23.4 mmol, 1.1 eq.) Containing MeMgBr (methyl magnesium bromide) at a concentration of 3 mol / L was added, and the mixture was stirred for 30 minutes. did. To this yellow solution, a THF solution (55 mL, 27.6 mmol, 1.3 eq.) Containing 9-BBN (9-borabicyclo [3.3.1] nonane) at a concentration of 0.5 mol / L was slowly added, and the solution was added. Stirred at C for 1 hour. 6N-NaOHaq. (20 mL) and 30% H ₂ O ₂ (10 mL) were sequentially added, and the mixture was vigorously stirred for 30 minutes. The obtained reaction solution was neutralized with 10% aqueous ammonia chloride and extracted twice with ethyl acetate (60 mL). Thereafter, the organic layer was collected, washed with an aqueous solution of sodium thiosulfate, water, and saturated saline, and dried using anhydrous MgSO _4. The solution was concentrated to obtain a brown viscous liquid (6.3 g). Was.
This was purified by column chromatography (SiO ₂ = 200 g, hexane / ethyl acetate = 3/1 → 1/1), and a yellowish brown viscous liquid represented by the following formula (205) (4) .47 g, 17.6 mmol, 82% yield).

Next, a compound represented by the following general formula (205) (4.47 g, 17.6 mmol, 1.0 eq.) And Et ₃ N (triethylamine) (7.34 mL, 52.9 mmol, 3 .0 eq.) And THF (45 mL), and the mixture was cooled to 5 ° C. Methanesulfonyl chloride (3.02 mL, 38.8 mmol, 2.2 eq.) Was added dropwise to the solution, and the mixture was stirred for 1 hour. The obtained reaction solution was poured into water (100 mL) and extracted with ethyl acetate. The organic layer was washed with water and saturated saline, dried and concentrated to obtain a brown liquid (6.25 g).
This was purified by column chromatography (SiO ₂ = 210 g, hexane / ethyl acetate = 1/1 → 1/2), and a red-yellow viscous liquid represented by the following formula (206): .3 g).

Next, a compound (1.27 g, 3.83 mmol, 1.0 eq.) Represented by the above general formula (206) and a 10 wt / V% dimethylamine-methanol solution (30 mL) were added to a 100 mL autoclave, The mixture was heated and stirred at 80 ° C. for 3 hours, and analyzed by thin layer chromatography (TLC) to confirm that the raw materials had disappeared. The obtained yellow solution was concentrated, and the residue was poured into water (50 mL) and extracted with ethyl acetate. Then, the organic layer was washed with water and saturated saline, dried and concentrated to obtain a brown liquid (1.01 g).
This was purified by column chromatography (NH-SiO ₂ = 50 g, hexane / ethyl acetate = 1/1), and was a pale yellow viscous liquid compound (0.91 g) represented by the following general formula (207). , 3.25 mmol, 84% yield).

Next, a compound represented by the following general formula (207) (0.53 g, 1.89 mmol, 2.0 eq.), Methanol (15 mL), and sodium methoxide (0.95 mL, 4.73 mmol) were placed in a 100 mL reactor. , 5 eq.) And distilled water (2 mL), and the mixture was heated to 50 ° C. To this solution, distilled water (2 mL) in dissolved was _{BeSO 4 · 2H 2 O (0.167g} , 0.945mmol, 1.0eq.) Was slowly added dropwise. Thereafter, the mixture was stirred at 50 ° C. for 0.5 hour, and distilled water (15 mL) was added. After cooling, the resulting yellow suspension was filtered. The filtrate is stored at 5 ° C. for 7 days, and the precipitated crystals are filtered, washed with water and a small amount of cooled methanol, dried under high vacuum, and are yellow solids according to the above general formula (4). The indicated organometallic complex (0.25 g, 0.44 mmol, 46% yield) was obtained.

The identification of the organometallic complex represented by the general formula (4) was performed using 1H-NMR. 1H-NMR (400 MHz, CDCl ₃ ) δ: 1.87 (quin., J = 7.2, 7.6, 8.0 Hz, 2H), 2.10 (s, 6H), 2.31 (t, J = 7.2, 8.0 Hz), 2.83-3.11 (m, 2H), 7.26-7.29 (m, 2H), 7.54 (d, J = 8.8 Hz, 1H) ), 7.69 (d, J = 8.0 Hz, 1H), 7.87 (d, J = 9.2 Hz, 1H), 8.23-8.25 (m, 2H).

(Example 1 "Element 1")
(Production of organic EL element)
The organic EL device 1 shown in FIG. 1 was manufactured and evaluated by the following method.
[Step 1]
As the substrate 2, a commercially available transparent glass substrate having an average thickness of 0.7 mm on which a patterned electrode (cathode 3) having a thickness of 150 nm and a width of 3 mm made of ITO was prepared.
Then, the substrate 2 having the cathode 3 was subjected to ultrasonic cleaning in acetone and isopropanol for 10 minutes each, and boiled in isopropanol for 5 minutes. Thereafter, the substrate 2 having the cathode 3 was taken out of isopropanol, dried by blowing nitrogen, and subjected to UV ozone cleaning for 20 minutes.

[Step 2]
The substrate 2 on which the cathode 3 washed in [Step 1] was fixed to a substrate holder of a Miratron sputtering apparatus having a zinc metal target. After reducing the pressure in the chamber of the sputtering apparatus to a pressure of about 1 × 10 ⁻⁴ Pa, sputtering is performed in a state where argon and oxygen are introduced, and a zinc oxide layer having a thickness of about 2 nm is formed on the cathode 3 of the substrate 2. Produced. When a zinc oxide layer was formed, a metal mask was used to take out the electrode so that zinc oxide was not formed on a part of the ITO electrode (cathode 3). Thereafter, the substrate 2 having the zinc oxide layer formed on the cathode 3 was baked for 1 hour on a hot plate set at 400 ° C. in the air to form a zinc oxide layer (oxide layer 4).

[Step 3]
Next, the electron injection layer 5 containing the organometallic complex represented by the general formula (4) was formed on the oxide layer 4 by the method described below.
First, the organometallic complex represented by the general formula (4) synthesized by the above-described method for synthesizing an organometallic complex was dissolved in toluene to prepare a 0.5% by weight toluene solution. Next, the substrate 2 having the cathode 3 and the oxide layer 4 formed in [Step 2] was set on a spin coater. The electron injection layer 5 was formed by rotating the substrate 2 at 2,000 rpm for 30 seconds while dropping a 0.5% by weight toluene solution of the organometallic complex onto the oxide layer 4. The average thickness of the obtained electron injection layer 5 was 30 nm.

[Step 4]
Next, the substrate 2 on which the layers up to the electron injection layer 5 were formed was fixed to a substrate holder of a vacuum evaporation apparatus. Further, bis [2- (2-benzothiazolyl) phenolato] zinc (II) (Zn (BTZ) ₂ ) represented by the following general formula (5) and tris [1-phenylisoquinoline] represented by the following general formula (6) Iridium (III) (Ir (piq) ₃ ), N, N′-di (1-naphthyl) -N, N′-diphenyl-1,1′-biphenyl-4,4 represented by the following general formula (7) '-Diamine (α-NPD) was placed in an alumina crucible and set in an evaporation source.

Then, the pressure inside the vacuum evaporation apparatus is reduced to a pressure of about 1 × 10 ⁻⁵ Pa, and 35 nm is co-evaporated using Zn (BTZ) ₂ as a host and Ir (piq) ₃ as a dopant to form a light emitting layer 6. did. At this time, the doping concentration was such that Ir (piq) ₃ was 6% by weight based on the entire light emitting layer 6.
Next, the hole transport layer 7 was formed on the substrate 2 on which the light emitting layer 6 was formed, by depositing α-NPD to a thickness of 40 nm. Further, HAT-CN represented by the above general formula (8) was deposited by vacuum deposition in a consistent manner to form a hole injection layer 8 having a thickness of 10 nm.

[Step 5]
Next, aluminum (anode 9) was deposited on the substrate 2 on which the hole injection layer 8 was formed so as to have a thickness of 100 nm, thereby obtaining an "element 1" according to an example of the present invention.
When depositing the anode 9, a stainless steel evaporation mask was used so that the evaporation surface had a band shape with a width of 3 mm. That is, the light emitting area between the cathode 3 and the anode 9 of the manufactured element 1 was set to 9 mm ² .

(Example 2 “Element 2”)
The “element 2” according to an example of the present invention is the same as “element 1” except that the concentration of the organometallic complex in the toluene solution used for forming the electron injection layer 5 was 1.0% by weight. I got it. The average thickness of the electron injection layer 5 in the device 2 was 50 nm.

(Comparative Example 1 "Element 3")
"Element 1" was used except that an ethanol solution containing 0.5% by mass of polyethyleneimine (trade name: P1000, manufactured by Nippon Shokubai Co., Ltd.) was used instead of the toluene solution used when forming the electron injection layer 5. Similarly, an "element 3" as a comparative example of the present invention was obtained. The average thickness of the electron injection layer 5 in the element 3 was 5 nm.

(Comparative Example 2 “Element 4”)
In the same manner as in “Element 1” except that a dichloroethane solution containing 0.5% by mass of a compound represented by the following general formula (9) was used instead of the toluene solution used in forming the electron injection layer 5. "Element 4" which is a comparative example of the present invention was obtained. The average thickness of the electron injection layer 5 in the device 4 was 30 nm.

(Measurement of light emission characteristics of elements 1 to 4)
A voltage was applied to each element using a Keithley “2400 type source meter” to measure the current density. Further, the relationship between the applied voltage and the luminance of each element was examined using “LS-100” manufactured by Konica Minolta.

(Emission characteristics of elements 1 to 4)
FIG. 4A is a graph showing the relationship between the applied voltage and the current density of the elements 1 to 4. FIG. 4B is a graph showing the relationship between the applied voltage of elements 1 to 4 and the luminance.
As shown in FIGS. 4A and 4B, in the elements 1 and 2 using the organometallic complex of the present invention as a material for the electron injection layer, the compound represented by the general formula (9) was used. Compared with the element 4, higher luminance is obtained at a lower driving voltage. This is presumably because in the device 4, since the compound represented by the general formula (9) does not contain an amino group, it is difficult to inject electrons from the substrate to the light emitting layer, and a high driving voltage is required. . On the other hand, in the element 1 and the element 2, since the interface dipole generated by the coordination bond between the amino group contained in the organometallic complex and the material of the oxide layer can be used, high electron injection property can be obtained at a low driving voltage. It is considered that high luminance can be obtained.

  In the element 3 using polyethyleneimine as a material for the electron injection layer, the number of amino groups in the electron injection layer is larger than that in the elements 1 and 2 using the organometallic complex of the present invention. It is considered that the number of coordination bonds between the group and the material of the oxide layer was increased, and high luminance was obtained at a low driving voltage.

  As shown in FIG. 4B, in the elements 1 and 2 using the organometallic complex of the present invention, even if the thickness of the electron injection layer is increased as in element 2 (film thickness 50 nm), A luminance-voltage characteristic equivalent to that of the thin device 1 (thickness: 30 nm) is obtained. This is considered to be due to the high electron transportability caused by the organometallic complex of the present invention. On the other hand, for example, in the element 3 (thickness: 5 nm) using polyethyleneimine as the material of the electron injection layer, when the thickness of the electron injection organic layer is increased, the driving voltage is significantly increased.

(Durability of elements 1 and 3)
With respect to the element 1 and the element 3, a change in luminance with respect to an elapsed time when the device was continuously driven from an initial luminance of 1000 cd / m ² was examined. FIG. 5 shows the result.
As shown in FIG. 5, in the element 3 using polyethyleneimine as the material of the electron injection layer, the life until the luminance was reduced to half was 1000 hours or less. On the other hand, in the element 1 using the organometallic complex of the present invention, the life until the luminance was reduced to half was about 2000 hours, which was superior to the element 3 in durability and long life. . This is presumably because in the element 1, the material of the electron injection layer is electrically stable compared to the element 3 including the NH bond, so that the electron injection layer is less likely to be deteriorated and has a longer life. .

(Example 3 "Element 5")
"Element 5", which is an example of the present invention, was obtained in the same manner as "Element 1", except that oxide layer 4 was not formed.
With respect to the obtained “element 5”, the relationship between the applied voltage and the luminance was examined in the same manner as in “element 1”. The result is shown in FIG.

  FIG. 6 is a graph showing the relationship between the applied voltage of element 1 and element 5 and the luminance. As shown in FIG. 6, equivalent characteristics are obtained between the element 5 and the element 1. From this, it was found that in the element 1 using the organometallic complex of the present invention, high luminance was obtained at a low driving voltage with or without an oxide layer.

(Example 4 "Element 6")
Before forming the light emitting layer 6, the same procedure as in "Element 1" was performed except that an electron transport layer 10 of Zn (BTZ) _{2 having a} thickness of 10 nm was formed on the electron injection layer 5 by vapor deposition. "Element 6" according to an example of the present invention was obtained.
In Example 4, two “elements 6” were prepared, and sealed using different materials by the following method.
FIGS. 7A and 7B are perspective views for explaining a method of sealing the element 6. First, as shown in FIG. 7A, a plate member 14 and a frame member 13 arranged along the edge of the plate member 14 on the side facing the anode 9 on the anode 9 of the element 6. A sealing member was arranged. Thereafter, as shown in FIG. 7B, the space between the plate member 14 and the frame member 13 and the space between the frame member 13 and the substrate 2 were sealed by bonding with an adhesive.

One of the two elements 6 was sealed using a resin material (barrier film) as the plate member 14 and a glass material as the frame member 13. As the barrier film, a sealing film (water permeability: 3 × 10 ⁻⁴ g / m ² · day) manufactured by Oike Industry Co., Ltd. was used. Further, the other element was sealed using a sealing container having a concave shape in which the plate member 14 and the frame member 13 were integrated. A glass container (glass cap) was used as the sealing container.

The initial luminance of each of the element 6 (resin sealing) and the element 6 (glass sealing) sealed using a resin material (barrier film) and a glass material (glass cap) is 1000 cd. / M ^2, the change in luminance with respect to the elapsed time when continuously driven was examined. FIG. 8 shows the result.
As shown in FIG. 8, the life of the element 6 partially sealed with a resin material and the element 6 sealed with a glass material until the luminance was reduced to half was equal.

  4 to 6 and 8, it was confirmed that the organometallic complex of the present invention is a material having all of high electron injection properties, high durability, and high atmospheric stability. In addition, this result can be applied to a structure having a normal structure in which an anode is disposed between a substrate and a light emitting layer as long as similar charge injection properties can be realized by using the organometallic complex of the present invention. It is shown that it is.

1, 11: organic EL element, 2: substrate, 3: cathode, 4: oxide layer, 5: electron injection layer, 6: light emitting layer, 7: hole transport layer, 8: hole injection layer, 9: anode , 10: electron transport layer.

Claims (8)

Having an electron injection layer between the electrode and the light emitting layer,
An organic electroluminescence device, wherein the electron injection layer contains an organometallic complex represented by the following general formula (1).

(In the general formula (1), M is a metal atom, and represents a metal atom belonging to Groups 1 to 3, 12, or 13 of the periodic table. C is a carbon atom, and N is a nitrogen atom. , O represent an oxygen atom, and a dotted line from a nitrogen atom to a metal atom M represents that the nitrogen atom is coordinated to the metal atom M. Q ¹ is a dotted arc and a nitrogen atom, X ¹ , Y ¹ X ¹ and X ² each represent a carbon atom or a nitrogen atom, and Y ¹ and Y ² represent a carbon atom, a nitrogen atom, an oxygen atom, or represents a sulfur atom .Q ² is .R ^1, R ² indicating that dotted arc and carbon atoms, X ^2, aromatic with Y ² hydrocarbon ring or an aromatic heterocyclic ring is formed on the amino group represents a monovalent alkyl group, this L is the, Q ² and the amino group is bonded directly Or .n representing a linking group linking, ^{Q 2} and amino groups is 1, 2 or 3.) Having an electron injection layer between the electrode and the light emitting layer,
An organic electroluminescence device, wherein the electron injection layer contains an organometallic complex represented by the following general formula (2).

(In the general formula (2), M is a metal atom, and represents a metal atom belonging to Groups 1 to 3, 12, or 13 of the periodic table. N is a nitrogen atom, and O is an oxygen atom. The dotted line from the nitrogen atom to the metal atom M indicates that the nitrogen atom is coordinated to the metal atom M. Q ¹ is the nitrogen-containing heterocyclic ring together with the dotted arc and the nitrogen atom, X ¹ and Y ^1. X ¹ represents a carbon atom or a nitrogen atom, Y ¹ represents a carbon atom, a nitrogen atom, an oxygen atom, or a sulfur atom, and R ¹ and R ² represent an amino group. L represents the above monovalent alkyl group, L represents a direct bond between a benzene ring and an amino group, or a linking group connecting a benzene ring and an amino group, and n represents 1, 2 or 3. is there.)   The organic electroluminescence device according to claim 1, further comprising an inorganic oxide layer between the electrode and the electron injection layer.   The organic electroluminescent device according to any one of claims 1 to 3, wherein the electron injection layer has an average thickness of 5 to 100 nm. The organic electroluminescence device according to claim 1, wherein the device is sealed using a material having a water vapor permeability of less than 1 × 10 ⁻³ g / m ² / day. . A method for producing an organic electroluminescence device according to any one of claims 1 to 5,
The method of manufacturing an organic electroluminescence device, wherein the step of forming the electron injection layer includes a step of applying a solution containing the organometallic complex.   A display device comprising the organic electroluminescence device according to claim 1.   A lighting device comprising the organic electroluminescent element according to claim 1.

Images