JP2016096123A - Organic electroluminescent element, method of manufacturing the same, and organic electroluminescent lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element capable of achieving long life with an easy manufacturing process, and to provide a method of manufacturing the same, and an organic EL lighting system.SOLUTION: An organic electroluminescent element has a first electrode, a second electrode, at least one light-emitting unit including a luminous layer, arranged between the first and second electrodes, and a charge generation layer arranged between the light-emitting unit and second electrode when there is one light-emitting unit, and arranged between adjoining light-emitting units when there are more than one light-emitting units. The charge generation layer is a layer containing an organometallic complex having a specific structure and at least one kind of oxide thereof (A), at least one kind of specific transition metal nanoparticles (B), and an amine compound.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an organic electroluminescence element (hereinafter also referred to as an organic EL element), a manufacturing method thereof, and an organic electroluminescence lighting apparatus (hereinafter also referred to as an organic EL lighting apparatus).

  The organic EL element is a charge injection type self-luminous organic EL element utilizing light emission generated when electrons and holes that have reached the light emitting layer are recombined.

An organic EL element generally has a structure in which an organic layer having a light emitting layer is disposed between a first electrode (usually an anode) which is a transparent electrode and a second electrode (usually a cathode) on a transparent substrate. Provided. This organic layer had a two-layer structure consisting of a light emitting layer and a hole injection layer in the early organic EL elements, but now, in order to obtain high light emission efficiency and a long driving life, an electron injection layer, an electron Various multilayer structures such as a five-layer structure composed of a transport layer, a light emitting layer, a hole transport layer, and a hole injection layer have been proposed.
In these layers other than the light-emitting layer such as the electron injection layer, the electron transport layer, the hole transport layer, and the hole injection layer, the effect of facilitating injection and transport of charges to the light-emitting layer, or blocking, is effective. It is said that there are effects such as maintaining the balance of the hole current and suppressing diffusion of light energy excitons.

In recent years, in addition to flat displays using organic EL elements, illumination apparatuses using organic EL elements have attracted attention as one of light source devices. An illumination device using an organic EL element has various excellent characteristics such as self-light emission, wide viewing angle, and high-speed response.
In order to use as a light source device, it is required to satisfy all of high efficiency, high luminance, and long life. However, the lifetime of the organic EL element and the emission luminance are in a trade-off relationship, and it is difficult to achieve both high luminance and long lifetime.

  A stack type (also called multi-photon type) organic EL element in which two or more light-emitting units including an organic light-emitting layer are stacked has been proposed as a technique for increasing the efficiency, the brightness, and the lifetime (for example, patents). Reference 1). According to the stack type organic EL element, when a voltage is applied between two electrodes, a plurality of light emitting layers emit light simultaneously as if they are connected in series, and light from each light emitting layer is added up. When a constant current is applied, light can be emitted with higher brightness than that of a conventional organic electroluminescence element, and the trade-off between the lifetime and the light emission brightness as described above can be improved. In the stack type organic EL element, an organic EL element having high characteristics cannot be obtained by simply laminating light emitting units including an organic light emitting layer. A charge generation layer for generating holes and electrons is provided.

On the other hand, there are two main methods for manufacturing organic EL elements, known as film formation by vacuum evaporation (dry process) and coating film formation using a solution (solution coating method). In addition, a solution coating method that is excellent in terms of high productivity and the like has attracted attention. Even when the organic EL element is used as a lighting device, it is required to increase the area of the organic EL element.
However, the charge generation layer is currently formed by a dry process. For example, in Patent Document 2, a charge generation layer is formed by laminating a metal having a work function of 3.0 ev or less such as Li and a metal having a work function of 4.0 eV or more such as vanadium oxide by a vacuum deposition method. doing. For example, in Patent Document 3, a charge generation layer in which a mixed layer of a phenanthroline derivative and an alkaline earth metal element and hexanitrile azatriphenylene (HATCN6) are stacked is formed. In Patent Document 4, a layered product of an Alq layer and a mixed layer of LiF and aluminum as an n-type doped layer, an alkali metal layer, a layer containing only a hole transporting material, and a hole transporting material as a p-type doped layer And molybdenum oxide are both formed by vapor deposition. Further, in Patent Document 5, although there is a description that the charge generation layer may be formed by coating or dissolving copper phthalocyanine and C60 in a solvent, as shown in the comparative example described later. Actually, it is impossible to form a layer that functions as a charge generation layer by a coating method, and in the example of Patent Document 5, a charge generation layer using C60 is formed by a vapor deposition method. In Patent Document 6, MoO ₃ and Li are co-deposited, followed by MoO ₃ , and then MoO ₃ and α-NPD (4,4′-bis [N- (naphthyl) -N-phenyl-amino). The charge generation layer is formed by co-evaporation with biphenyl).

JP 2003-272860 A JP 2010-146895 A JP 2013-207167 A Japanese Patent No. 4896544 Japanese Patent No. 5277319 Japanese Patent No. 5237541

As described above, conventionally, although there was an idea of forming a charge generation layer by a solution coating method, it was actually difficult to form a stable film.
In order for the charge generation layer formed by the coating method to function as the charge generation layer, first, the charge generation layer itself formed by the coating method must have a film-forming property that forms a uniform film and the stability of the thin film. is necessary. In addition, in order to form the charge generation layer by the coating method, it is necessary to suppress dissolution of the electron injecting and transporting layer, the light emitting layer, and the like, which are lower layers when the charge generation layer is formed. Even when a metal layer such as an aluminum layer provided for reduction of the electron injection / transport layer or the like is used, the metal layer is a thin film of about 2 nm, so that the solvent penetrates and reaches the lower electron injection / transport layer or the like. obtain. In addition, when the charge generation layer itself is a thin film, when the layer is further formed on the charge generation layer by a coating method, the solvent for forming the upper layer penetrates into the lower layer of the charge generation layer through the charge generation layer. It has been found that the problem of dissolving the lower layer of the charge generation layer also occurs. The film forming property of the charge generation layer and the stability of the thin film including the adjacent layers when formed by the coating method are important because they are greatly related to the lifetime characteristics of the device. Thus, the formation of the charge generation layer by the solution coating method has a difficulty that cannot be overcome simply by having the material soluble in a certain solvent.
On the other hand, if the charge generation layer can be formed only by vapor deposition, there is a problem that even if the light-emitting layer is formed separately by a solution coating method such as an ink jet method, the advantages of the solution coating method cannot be utilized. there were. The charge generation layer is also desired to be produced by a solution coating method that is excellent in terms of an increase in area, high productivity, and the like.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an organic EL element capable of forming a charge generation layer by a solution coating method and capable of achieving a long life while being easy in manufacturing process, and its It aims at providing the manufacturing method and the organic electroluminescent illuminating device using the said organic electroluminescent element.

As a result of intensive studies to achieve the above object, the present inventors have used a specific organometallic complex or a specific transition metal-containing nanoparticle, so that the solution coating method can be used to form an adjacent inorganic layer or organic layer. It has been found that the film can function well as a charge generation layer while being able to form a highly stable film having excellent adhesion, and the present invention has been completed.
That is, the organic electroluminescence element of the present invention is
A first electrode, a second electrode, and at least one light-emitting unit including a light-emitting layer disposed between the first electrode and the second electrode; and when there is one light-emitting unit, the light-emitting unit and the second electrode A charge generation layer disposed between the adjacent light emitting units when the number of the light emitting units is two or more.
The charge generation layer is a layer containing at least one of the following (A) and (B) and an amine compound.

(A) at least one compound represented by the following general formula (I) and an oxide thereof;

(In General Formula (I), M is at least one of molybdenum, tungsten, and vanadium, and R ¹ and R ² may each independently have a substituent and include a hetero atom. And represents an aliphatic hydrocarbon group, an aromatic ring group, or a combination thereof, where n represents a positive number of 1 to 3, and m represents a positive number of 0 to 2.)

(B) Transition metal-containing nanoparticles comprising at least one transition metal compound selected from the group consisting of transition metal oxides, transition metal carbide oxides, transition metal nitride oxides, and transition metal sulfide oxides, and a protective agent The transition metal is at least one of molybdenum, tungsten, and vanadium, and the transition metal-containing nanoparticles are formed by attaching a protective agent that protects the surface to the particle surface. A linking group capable of linking to a transition metal compound and an organic group having 1 or more carbon atoms. One or more transition metal compound nanoparticles selected from the group consisting of groups;

(In the formula, Z ₁ , Z ₂ and Z ₃ each independently represent a halogen atom or an alkoxy group, and R represents a hydrogen atom or a methyl group.)

Moreover, the method for producing an organic electroluminescent element of the present invention includes a first electrode, a second electrode, at least one light emitting unit including a light emitting layer disposed between the first electrode and the second electrode, An organic compound having a charge generation layer disposed between the light emitting unit and the second electrode when there is one light emitting unit, and disposed between adjacent light emitting units when there are two or more light emitting units. A method for producing an electroluminescent device, comprising:
(A ′) One or more inks containing at least one of the compound represented by the general formula (I) and the (B) and an amine compound are mixed or used. And a step of forming the charge generation layer by a coating method.

  In the organic EL device of the present invention, the charge generation layer is a layer in which a layer containing at least one of (A) and (B) and a layer containing the amine compound are laminated. However, it is preferable from the viewpoint of improving the function as a charge generation layer and improving the light emission efficiency, luminance, and lifetime.

  In the method for producing an organic EL device of the present invention, the ink (α) containing at least one of (A ′) and (B), and the ink containing the amine compound are used. Having a step of forming a charge generation layer in which a layer containing at least one of (A ′) and (B) and a layer containing the amine compound are laminated has the function as a charge generation layer. It is preferable in terms of improving and improving luminous efficiency, luminance, and lifetime.

  In the organic EL device of the present invention and the method for producing the organic EL device, in the transition metal compound nanoparticle of (B), the protective agent is a hydroxyl group, a carbonyl group, a carboxyl group, in addition to the linking group, It preferably has one or more hydrophilic groups selected from the group consisting of amino groups, thiol groups, silanol groups, sulfo groups, sulfonates and ammonium groups. A charge generation layer can be stably formed on the electron transport layer and the light-emitting layer, which are easily dissolved in a hydrophobic solvent, by a solution coating method using a hydrophilic solvent, and on the hydrophilic charge generation layer. In addition, even if the organic layers are formed adjacent to each other by a solution coating method using a hydrophobic solvent, they can be stably formed.

  Moreover, in the manufacturing method of the organic EL element of this invention, having an oxidation process which oxidizes the metal contained in at least 1 sort (s) of said (A ') and (B) improves luminous efficiency, brightness | luminance, and lifetime. This is preferable.

  Moreover, in this invention, the organic electroluminescent illuminating device (henceforth an organic EL illuminating device) provided with the organic electroluminescent element which concerns on the said this invention is also provided.

  In the present invention, there is also provided an ink for forming a charge generation layer of an organic electroluminescence device, which contains at least one of (A ′) and (B).

  According to the present invention, an organic EL element capable of forming a charge generation layer by a solution coating method and having a simple manufacturing process, and capable of achieving a long life, a manufacturing method thereof, and an organic EL using the organic EL element A lighting device can be provided.

It is a section conceptual diagram showing the basic layer composition of the 1st organic EL element concerning the present invention. It is a cross-sectional schematic diagram which shows the basic layer structure of the 2nd organic EL element which concerns on this invention. It is a partial process figure which shows an example of the manufacturing method of the organic EL element which concerns on this invention. It is a partial process figure which shows an example of the manufacturing method of the organic EL element which concerns on this invention. It is a partial process figure which shows an example of another manufacturing method of the organic EL element which concerns on this invention. It is a partial process figure which shows an example of another manufacturing method of the organic EL element which concerns on this invention. It is a partial process figure which shows an example of another manufacturing method of the organic EL element which concerns on this invention. It is a partial process figure which shows an example of another manufacturing method of the organic EL element which concerns on this invention. It is a section conceptual diagram showing the composition of an example of the organic EL lighting device concerning the present invention. 4 is a TOF-SIMS measurement result of the reaction product 1 obtained in Synthesis Example 1. FIG. The partially expanded view of the XPS spectrum of the layer containing said (A) obtained in Example 1 is shown. The electric current-applied voltage characteristic curve of Example 1 and Comparative Example 1 is shown. The luminance-applied voltage characteristic curves of Example 1 and Comparative Example 1 are shown.

1. Organic EL element The organic EL element of the present invention comprises a first electrode, a second electrode, at least one light-emitting unit including a light-emitting layer disposed between the first electrode and the second electrode, and the light-emitting unit includes A charge generation layer disposed between the light emitting unit and the second electrode in one case, and disposed between adjacent light emitting units in the case of two or more light emitting units;
The charge generation layer is a layer containing at least one of the following (A) and (B) and an amine compound.

(A) at least one compound represented by the following general formula (I) and an oxide thereof;

(In General Formula (I), M is at least one of molybdenum, tungsten, and vanadium, and R ¹ and R ² may each independently have a substituent and include a hetero atom. And represents an aliphatic hydrocarbon group, an aromatic ring group, or a combination thereof, where n represents a positive number of 1 to 3, and m represents a positive number of 0 to 2.)

(B) Transition metal-containing nanoparticles comprising at least one transition metal compound selected from the group consisting of transition metal oxides, transition metal carbide oxides, transition metal nitride oxides, and transition metal sulfide oxides, and a protective agent The transition metal is at least one of molybdenum, tungsten, and vanadium, and the transition metal-containing nanoparticles are formed by attaching a protective agent that protects the surface to the particle surface. A linking group capable of linking to a transition metal compound and an organic group having 1 or more carbon atoms. One or more transition metal compound nanoparticles selected from the group consisting of groups;

(In the formula, Z ₁ , Z ₂ and Z ₃ each independently represent a halogen atom or an alkoxy group, and R represents a hydrogen atom or a methyl group.)

Since the compound represented by the specific general formula (I) in (A) is an organometallic complex of a specific metal having a specific ligand, unlike the case of using a transition metal oxide of an inorganic compound, Soluble in solvent. In addition, since the specific transition metal-containing nanoparticles (B) contain an organic moiety as a protective agent for protecting the particle surface in the nanoparticles, they are dispersed in a solvent, unlike the case of using transition metal oxides of inorganic compounds. Have sex.
In the organic EL device of the present invention, the charge generation layer comprises at least one of the compound represented by the specific general formula (I) in (A) and the (B) specific transition metal-containing nanoparticles, and an amine. Since it is a layer containing a system compound, since each component is stably dissolved or dispersible in a solvent, a film can be formed by a solution coating method, and the manufacturing process is easy. In particular, at least one of the compound represented by the general formula (I) in (A) and the (B) specific transition metal-containing nanoparticles is selected by appropriately selecting a ligand or a protective agent. Solvents that dissolve, such as hydrophilicity and hydrophobicity, can be appropriately changed. Therefore, a material that can be dissolved in a solvent that does not dissolve the lower layer can be used in accordance with the materials such as the electron injecting and transporting layer and the light emitting layer as the lower layer, and the remaining film ratio of the lower layer can be increased. In addition, at least one of the compound represented by the general formula (I) in (A) and the (B) specific transition metal-containing nanoparticles can each have high solvent solubility or dispersibility. Since the solid content concentration of the ink can be increased, it is possible to form a uniform layer having a relatively thick film thickness of about 5 to 150 nm, more preferably about 20 to 150 nm as the total film thickness of the charge generation layer. Is possible. Thus, when a layer is further formed on the charge generation layer by a coating method, the solvent at the time of forming the upper layer of the charge generation layer penetrates through the charge generation layer to dissolve the lower layer of the charge generation layer or Problems such as trapping charges generated in the charge generation layer by the soaked solvent becoming a residual solvent can be suppressed, and the charge generation function is not impaired.

The transition metal contained in at least one of the compound represented by the general formula (I) in (A) and the (B) specific transition metal-containing nanoparticles is at least one of molybdenum, tungsten, and vanadium. It is a seed, both of which are highly reactive and easily form a charge transfer complex with an amine compound, and thus have an excellent charge generation function. If the layer containing at least one of (A) and (B) is a sea-island structure or a spotted film, the contact area with the adjacent amine compound is small and it is difficult to form a charge transfer complex. In addition, since at least one of (A) and (B) is relatively thick and can form a uniform layer, a charge transfer complex is easily formed between the layers even when laminated with an amine compound layer. Such a charge generation layer is considered to improve the light emission efficiency and the luminance because the charge injection and transport are promoted and the recombination probability in the light emitting layer is improved.
In addition, since at least one of the compound represented by the general formula (I) in (A) and the (B) specific transition metal-containing nanoparticle contains the specific transition metal, an organic material and It is considered that the lifetime is improved because the electrical resistance is high in comparison.
The compound represented by the general formula (I) in (A) and at least one of the specific transition metal-containing nanoparticles (B) together with a specific transition metal, a ligand, or a linking group Since the organic group is stably contained as a protective agent connected in step 1, the affinity with the amine compound and the affinity with the adjacent inorganic compound or organic compound layer are increased, and the adhesion with the adjacent layer is also improved. Excellent film with high stability.
As such a highly stable film, since a charge generation layer having an excellent charge generation function can be formed by a solution coating method, the organic EL element and the stack type organic EL element of the present invention have a manufacturing process. Although it is easy, the lifetime of the element can be improved, and the stack type organic EL element of the present invention can improve the power efficiency, the luminance, and the element life while the manufacturing process is easy.

  In the organic EL device of the present invention, the ligand of the compound represented by the specific general formula (I) in (A) and the protective agent for the specific transition metal-containing nanoparticles (B) described above, By selecting or modifying the type, it is easy to achieve multi-functionality such as imparting not only hydrophilicity and hydrophobicity but also functionality such as charge transportability or adhesion.

In addition, the organic EL device of the present invention can stably form a charge generation layer that could not be stably formed by a solution coating method by a solution coating method, so that a light emitting layer unit and a charge generation layer can be formed. Then, it can be formed only by the sequential coating process. Therefore, compared with a process including a vapor deposition process, there is an advantage that an organic EL element is simple and can be manufactured at a low cost.
The solution coating method that applies a solvent to a substrate does not require a large-scale vapor deposition device compared to a dry process including a vapor deposition process, can be expected to simplify the manufacturing process steps, have high material utilization efficiency, and cost. There is a merit that it is inexpensive and can increase the area of the substrate.

  The formation of a charge transfer complex means that, for example, when at least one of (A) and (B) is mixed into a solution of an amine compound by 1H NMR measurement, the amine compound has a concentration of 6 to 10 ppm. It is suggested by the observation of a phenomenon in which the shape and chemical shift value of the proton signal derived from the aromatic ring observed in the vicinity changes compared to before mixing at least one of (A) and (B). Is done.

Hereinafter, the layer structure of the organic EL element according to the present invention will be described.
FIG. 1 is a conceptual cross-sectional view showing the basic layer structure of an organic EL device according to the present invention. The basic layer structure of the first organic EL element of the present invention is arranged on the substrate 6 between the first electrode 1, the second electrode 5, and the first electrode 1 and the second electrode 5. One light-emitting unit 3 including the light-emitting layer 2 and a charge generation layer 4 disposed between the light-emitting unit and the second electrode are included.
In the case where there is one light emitting unit as shown in FIG. 1, the first electrode corresponds to an anode, and the charge generation layer is formed between a second electrode different from the anode and the light emitting unit. . The second electrode here may be a block electrode as well as a cathode.

FIG. 2 is a conceptual cross-sectional view showing another basic layer structure of the organic EL element according to the present invention. The basic layer configuration of the second organic EL element of the present invention is arranged on the substrate 6 between the first electrode 1, the second electrode 5, and the first electrode 1 and the second electrode 5. N light emitting units including a light emitting layer (light emitting unit 3-1 including light emitting layer 2-1, light emitting unit 3-2 including light emitting layer 2-2, light emitting unit 3-3 including light emitting layer 2-3,... Two or more light-emitting units including a light-emitting layer 2-n and two or more light-emitting units, adjacent to the light-emitting unit 3-1 and the light-emitting unit 3-2, adjacent to the charge generation layer 4-1. It has the charge generation layer 4-2 arrange | positioned between the light emission unit 3-2 and the light emission unit 3-3, ... charge generation layer 4- (n-1). In this example, n light emitting units are stacked, and n−1 charge generation layers are disposed between each adjacent light emitting unit.
In the present invention, the number n of the light emitting units is preferably 1 to 6, among which 1 to 4 is preferable, and 1 to 3 is more preferable.
The board | substrate 6 is a support body for forming each layer which comprises an organic EL element, and does not necessarily need to be provided in the surface of the electrode 1, and should just be provided in the outermost surface of the organic EL element.

In FIG. 2, for example, the first electrode 1 functions as an anode and the second electrode 5 functions as a cathode. In the organic EL device, when an electric field is applied between the anode and the cathode, holes are injected from the anode into the light emitting layer 2 and electrons are injected from the cathode into the light emitting layer, whereby the inside of the light emitting layer 2 is formed. The holes and electrons injected in step 1 are recombined to emit light outside the device. The charge generation layer in FIG. 2 generates charges (holes and electrons) when voltage is applied to the anode and the cathode, and injects electrons into the light emitting unit adjacent to the anode side with respect to the charge generation layer. It functions as a layer for injecting holes adjacent to the cathode side with respect to the charge generation layer.
In order to emit light to the outside of the element, all the layers existing on at least one surface of the light emitting layer need to be transparent to light having at least a part of wavelengths in the visible wavelength range.

The light emitting unit 3 of the organic EL element is a layer that includes at least a light emitting layer and exhibits various functions depending on the type of the organic EL element, and may be composed of a single layer or a multilayer. In the organic EL element of the present invention, the light emitting unit 3 includes some organic compound layer. When the light emitting unit is composed of multiple layers, the light emitting unit appropriately includes a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, and a known functional layer used for an EL element in addition to the light emitting layer. It may be included.
Hereinafter, each layer of the organic EL element according to the present invention will be described in detail.

(1) Charge generation layer The charge generation layer is a layer that generates holes and electrons when an electric field is formed, but the generation interface may be in the charge generation layer. It may be at the interface between the charge generation layer and another layer or in the vicinity thereof.
The charge generation layer in the organic EL device of the present invention comprises (A) at least one of the compound represented by the general formula (I) and its oxide, and (B) the specific transition metal-containing nanoparticles. And a layer containing an amine compound.
The charge generation layer in the organic EL device of the present invention may be composed of at least one of (A) and (B) and an amine compound, but may further contain other components. good.

The charge generation layer in the organic EL device of the present invention may be composed of one mixed layer containing at least one of (A) and (B) and the amine compound, A layer in which a layer containing at least one of (A) and (B) and a layer containing the amine compound are laminated may be used. Among them, the layer containing at least one of (A) and (B) and the layer containing the amine compound are laminated to improve the function as a charge generation layer and to improve luminous efficiency. From the viewpoint of improving brightness and life.
The reason why such a function is improved in the laminated layer is presumed that the film density of the specific transition metal contained in at least one of (A) and (B) is increased.
On the other hand, when the charge generation layer is composed of one mixed layer containing at least one of (A) and (B) and the amine compound, the process is saved and the productivity is reduced. improves.
In addition, the charge generation layer includes at least two layers as long as the layer containing at least one of (A) and (B) and the layer containing an amine compound are stacked adjacent to each other. It may be. For example, a layer containing at least one of (A) and (B), a mixed layer containing at least one of (A) and (B), and an amine compound were laminated. Examples include, but are not limited to, layers.

<(A) At least one compound represented by the following general formula (I) and its oxide>
The component (A) of the present invention includes at least one of a compound represented by the following general formula (I) and an oxide of a compound represented by the following general formula (I).
The compound represented by the following general formula (I) used in the present invention may be used in a mixture of two or more, instead of one kind alone.

(In General Formula (I), M is at least one of molybdenum, tungsten, and vanadium, and R ¹ and R ² may each independently have a substituent and include a hetero atom. And represents an aliphatic hydrocarbon group, an aromatic ring group, or a combination thereof, where n represents a positive number of 1 to 3, and m represents a positive number of 0 to 2.)

  The M is at least one of molybdenum, tungsten, and vanadium. Among them, molybdenum increases the reactivity of the compound represented by the general formula (I) and improves the charge generation function. To preferred.

R ¹ and R ² are each independently a linear, branched or cyclic saturated or unsaturated aliphatic hydrocarbon group which may have a substituent, a monocyclic or polycyclic aromatic ring group, or , And combinations thereof, and the hetero atom may contain an oxygen atom, a sulfur atom, a nitrogen atom, or the like.
Examples of the substituent that the aliphatic hydrocarbon group of R ¹ and R ² , the aromatic ring group, or a combination thereof may have include a halogen atom, an alkoxy group such as a methoxy group, and a cycloalkoxy group such as a cyclohexyloxy group An aryloxy group such as a phenoxy group, an alkylthio group such as a methylthio group, an arylthio group such as a phenylthio group, an acyl group such as an acetyl group, an acyloxy group such as an acetoxy group, a cyano group, and a nitro group.

R ¹ and R ² are alkyl groups such as methyl groups, cycloalkyl groups such as cyclopentyl groups, alkenyl groups such as vinyl groups, alkynyl groups such as ethynyl groups, aryl groups such as phenyl groups, and aromatic groups such as pyridyl groups. Examples include, but are not limited to, heterocyclic groups, aliphatic heterocyclic groups such as pyrrolidyl groups, arylalkyl groups such as benzyl groups, and alkylaryl groups such as 1,3,5-trimethylphenyl groups. .
The carbon number of each of R ¹ and R ² may be appropriately selected from the viewpoint of solubility in various solvents, but from the viewpoint of charge generation function, the carbon number is preferably 1-20.

Examples of the aliphatic hydrocarbon group having a substituent in R ¹ and R ² , an aromatic ring group, or a combination thereof include halogenated hydrocarbon groups such as a fluorinated hydrocarbon group such as a heptafluoropropyl group, Alkoxyalkyl groups such as methoxymethyl groups, alkoxyaryl groups such as methoxyphenyl groups, aryloxyalkyl groups such as phenoxymethyl groups, alkylthioalkyl groups such as methylthiomethyl groups, alkylthioaryl groups such as methylthiophenyl groups, phenylthiomethyl groups And arylthioalkyl groups such as acetylmethyl group, acylaryl groups such as acetylphenyl group, acyloxyalkyl groups such as acetoxypropyl group, acyloxyaryl groups such as acetoxyphenyl group, etc. But it is not limited thereto.

In the present invention, the total number of carbon atoms of R ¹ and R ² is preferably 5 or more from the viewpoint of improving the charge generation function. When the total number of carbon atoms of R ¹ and R ² is 5 or more, the solvent solubility is improved, the film can be stably formed by a solution coating method, and the compounds do not easily aggregate with each other in the coating film. It is presumed that the dispersibility and dispersion stability in the case are improved. In addition, when the total number of carbon atoms of R ¹ and R ² is 5 or more, affinity with the amine compound is improved, a charge transfer complex is efficiently formed, and charge generation ability is improved. Presumed.
Further, at least one of R ¹ and R ² preferably has 4 or more carbon atoms from the viewpoint of improving the lifetime of the organic EL device, and it becomes easy to form a charge generation layer by a solution coating method. preferable. The carbon number here includes the carbon number of the substituent.

Among them, at least one of the R ¹ and R ² preferably contains an aliphatic hydrocarbon group and has 4 or more carbon atoms. Specifically, at least one of the R ¹ and R ² is carbon 4 or more and a linear, branched or cyclic saturated or unsaturated aliphatic hydrocarbon group, alkoxyalkyl group, alkoxyaryl group, aryloxyalkyl group, alkylthioalkyl group, alkylthioaryl group, arylthioalkyl It is preferably at least one selected from the group consisting of a group, an acylalkyl group, an acylaryl group, an acyloxyalkyl group, and an acyloxyaryl group. When at least one of R ¹ and R ² has 4 or more carbon atoms and contains an aliphatic hydrocarbon group, the solvent solubility is improved and the compatibility with the amine compound is improved. Further, the charge generation layer can be easily formed by the solution coating method, and the charge generation function is improved, thereby improving the lifetime of the organic EL element.

In addition, since the ligand of the compound represented by the general formula (I) has two ketone groups, there is an advantage that it can be dissolved in a hydrophilic solvent. Also it is dissolved in a hydrophobic solvent by properly selecting R ¹ and R ^2. It is preferable to appropriately select R ¹ and R ² so that the charge generation layer is soluble in a solvent that does not dissolve the lower layer when the charge generation layer is formed by a coating method. In order to have solubility in the hydrophilic solvent, it is preferable that each carbon number of R ¹ and R ² is appropriately selected from 1 to 12, and further selected from 1 to 8 as appropriate. It is preferable.

The compound represented by the general formula (I) used in the present invention preferably includes a compound in which m is 1 and a compound in which m is 2. Among them, in the compound represented by the general formula (I), one or more selected from the compound in which m is 1 and the compound in which m is 2 is preferably 50% by mass or more, and more preferably 70% by mass. % Or more is preferable from the viewpoint of improving the charge generation function. In the compound represented by the general formula (I) used in the present invention, m is preferably 1 to 2.
N is preferably a positive number of 2 to 3. The compound represented by the general formula (I) preferably includes a compound in which n is 2.
Among them, in the compound represented by the general formula (I), at least one selected from a compound in which m is 1 and n is 2 and a compound in which m is 2 and n is 2 is 50% by mass or more. It is preferable that it is 70% by mass or more from the viewpoint of improving the charge generation function.

When the compound represented by the general formula (I) is not commercially available, it can be prepared as follows.
It is preferable to prepare by heating a mixture of a metal complex containing at least one of molybdenum, tungsten, and vanadium and a compound represented by the following general formula (II).

(In general formula (II), R ¹ and R ² are each independently the same as in general formula (I).)

  When a mixture of a metal complex containing at least one of molybdenum, tungsten, and vanadium and a compound represented by the following general formula (II) is prepared by heating, the reaction product contains the above general In addition to the compound represented by the formula (I), it is estimated that a dimer or multimer of the compound represented by the general formula (I) is included. However, as long as these dimers and multimers are also dissolved in the solvent, it is presumed to function in the same manner as the compound represented by the general formula (I). Therefore, these dimers and multimers are also included. It may be used as it is.

The metal complex containing at least one of molybdenum, tungsten, and vanadium used as a raw material is a coordination compound containing at least one metal of molybdenum, tungsten, and vanadium, and is at least one of molybdenum, tungsten, and vanadium. In addition to the seed metal, it contains a ligand. However, the molybdenum complex and tungsten metal complex used as raw materials include complexes having an oxidation number of −2 to +6. Vanadium complexes include complexes having an oxidation number of -3 to +5.
The type of the ligand is appropriately selected and is not particularly limited. However, from the viewpoint of compatibility with the compound represented by the general formula (II), it preferably contains a carbon atom, and further contains a carbon atom and an oxygen atom. It is preferable to include. Moreover, it is preferable that a ligand decomposes | disassembles from a complex at comparatively low temperature, such as 200 degrees C or less, for example.

Examples of the monodentate ligand include acyl, carbonyl, thiocyanate, isocyanate, cyanate, isocyanate, and halogen atom. Of these, carbonyl which is easily decomposed at a relatively low temperature is preferable.
Moreover, as a ligand, a monodentate ligand or a bidentate ligand is preferable from the point that the reactivity of a molybdenum complex becomes high. If the complex itself becomes too stable, the reactivity may be poor. As the molybdenum complex or tungsten complex used as a raw material, for example, a molybdenum complex or a tungsten complex that is a raw material of a reaction product described in paragraphs 0048 to 0059 of JP2010-272891A can be appropriately selected and used. Examples of vanadium complexes having an oxidation number of 0 or less include metal carbonyl [V- ^III (CO) ₅ ] ^-3 , [V- ^I (CO) ₆ ] ^- , [V (CO) ₆ ] and the like. . Examples of the vanadium complex having an oxidation number of 2 include [V ^II (H ₂ O) ₆ ] ²⁺ and cyclopentadienyl complex [V (η ⁵ -C ₅ H ₅ ) ₂ ]. Examples of the vanadium complex having an oxidation number of 3 include [V ^III (H ₂ O) ₆ ] ³⁺ , [V ^III Cl ₃ {N (CH ₃ ) ₃ } ₂ ] and the like. Examples of the vanadium complex having an oxidation number of 4 include [V ^IV Cl ₄ ] and [V ^IV OCl ₂ {N (CH ₃ ) ₃ } ₂ ]. Examples of the vanadium complex having an oxidation number of 5 include [V ^V OCl ₃ ], [V ^V F ₆ ] ^{− and the} like.
As a metal complex containing at least one of molybdenum, tungsten, and vanadium used as a raw material, hexacarbonyl molybdenum, hexacarbonyl tungsten, hexacarbonyl vanadium, and the like are preferably used from the viewpoint of reactivity.

Examples of the compound represented by the general formula (II) include any combination of the R ¹ and R ² .
The compound represented by the general formula (II) can be obtained commercially, or can be obtained by synthesis by, for example, a cross-coupling reaction using an acid chloride and a halogenated compound in the presence of a metal catalyst.
The compound represented by the general formula (II) is a raw material of the compound represented by the general formula (I), but preferably functions as a solvent for the specific metal complex. Among them, the compound represented by the general formula (II) preferably dissolves 1 mass% or more of the specific metal complex at 25 ° C., more preferably 5 mass% or more, and more preferably 10 mass% or more. It is even more preferable. In this case, in the step of obtaining the compound represented by the general formula (I), the reaction can be performed with no other solvent added or in a small amount, the reaction efficiency is increased, and the life of the device is improved.
The compound represented by the general formula (II) is preferably liquid at 25 ° C., but is not limited to being liquid at 25 ° C.
The compound represented by the general formula (II) preferably has a melting point of 150 ° C. or lower, more preferably 80 ° C. or lower, from the viewpoint that it can easily function as a solvent for the molybdenum complex during the synthesis reaction. Is preferred. Moreover, it is preferable that a viscosity is 20 mPa * s or less.

As described above, if the compound represented by the general formula (II) is a liquid at the reaction temperature and can sufficiently perform a solvent-free reaction, it is not necessary to add an organic solvent. When using a complex that is easily sublimated as the specific metal complex, it is preferable to add an organic solvent and react while refluxing from the viewpoint of improving the yield. When the compound represented by the general formula (II) is a powder and cannot be mixed with the specific metal complex, or even if the compound represented by the general formula (II) is liquid, the reaction efficiency is improved. In order to raise, an organic solvent may be added as necessary.
From the point of improving the reaction efficiency, when adding an organic solvent when heating the mixture, 1 to 5000 parts by mass of the organic solvent may be added to 100 parts by mass of the compound represented by the general formula (II). It is preferable to add 10 to 3000 parts by mass.

The content of the compound represented by the general formula (II) is preferably 200 parts by mass to 1000 parts by mass with respect to 100 parts by mass of the specific metal complex from the viewpoint of improving the reaction yield.
In particular, when the compound-containing solution represented by the general formula (I) after preparation is used as an ink for forming a charge generation layer as it is, the general formula (II) is used with respect to 1 mol of the specific metal complex. The content of the represented compound is preferably 3 to 6 mol from the viewpoint of improving the reaction yield and improving the lifetime of the device.

  The organic solvent other than the compound represented by the general formula (II) used in preparing the compound represented by the general formula (I) is a fragrance because it is a solvent that does not adversely affect the device performance. A group hydrocarbon solvent is preferably used, and examples thereof include toluene, xylene, anisole, mesitylene and the like.

Although heating temperature does not have a restriction | limiting in particular, Usually, it is about 100 to 200 degreeC, and it is preferable that it is 120 to 160 degreeC from the point which suppresses a side reaction. Since the reactivity of the specific metal complex used as a raw material and the interaction between the specific metal complexes differ depending on the heating temperature, it is preferable to adjust appropriately. Moreover, although there is no restriction | limiting in particular in the pressure at the time of heating, normal pressure-0.1 Mpa are desirable and normal pressure is further more desirable. The heating time may vary depending on the amount of synthesis, reaction temperature, etc., but cannot be generally specified, but is usually set in the range of 0.1 to 24 hours, preferably 1 to 10 hours.
Moreover, it is preferable that the said heating is performed in inert gas atmosphere from the point which suppresses a side reaction. The inert gas atmosphere can be adjusted, for example, by introducing an inert gas such as argon or nitrogen after exhausting to about 10 ⁻¹ Pa. The heating means may be appropriately selected according to the reaction scale, and is not particularly limited.

On the other hand, from the viewpoint of improving the charge generation function, it is also a preferable aspect that the charge generation layer contains an oxide of the compound represented by the general formula (I). The oxide of the compound represented by the general formula (I) can be obtained by means for oxidizing as described later. Among these, it is preferable to form a layer using the compound represented by the general formula (I) and then heat in the presence of oxygen to obtain an oxide of the compound represented by the general formula (I).
The oxide of the compound represented by the general formula (I) is preferably an organic-inorganic composite containing at least one transition metal of molybdenum, tungsten, and vanadium, an oxygen atom, and a carbon atom. . In the organic-inorganic composite, for example, when the transition metal contained is molybdenum, the charge generation function is to contain molybdenum having an oxidation number of +4, molybdenum having an oxidation number of +6, and a transition metal having a different oxidation number. It is preferable from the point.

<(B) Specific transition metal compound nanoparticles>
The specific transition metal compound nanoparticles used in the present invention are at least one transition metal compound selected from the group consisting of transition metal oxides, transition metal carbide oxides, transition metal nitride oxides, and transition metal sulfide oxides. And a transition metal-containing nanoparticle comprising a protective agent, wherein the transition metal is at least one of molybdenum, tungsten, and vanadium, and the transition metal-containing nanoparticle protects the surface on the particle surface And the protective agent includes a linking group that produces an action of linking to the transition metal compound and an organic group having 1 or more carbon atoms, and the linking group includes a hydroxyl group, a sulfonamide group, and the following general formula: It is a transition metal compound nanoparticle which is 1 or more types selected from the group which consists of a functional group shown by (1a)-(1o).
Here, the nanoparticle means a particle having a diameter of the order of nm (nanometer), that is, less than 1 μm.

(In the formula, Z ₁ , Z ₂ and Z ₃ each independently represent a halogen atom or an alkoxy group, and R represents a hydrogen atom or a methyl group.)

The transition metal compound-containing nanoparticles according to the present invention are different from particles formed simply by pulverizing a transition metal compound, and a protective agent having an organic group having 1 or more carbon atoms is connected to the surface of the nanoparticles by a linking group. ing. Since the organic group contained in the protective agent is arranged so as to cover the surface of the specific transition metal compound, the affinity with the organic solvent is increased, the organic solvent becomes dispersible, and the dispersion stability is also improved. It becomes a thing with high property.
Furthermore, in addition to the linking group, the protective agent is at least one selected from the group consisting of a hydroxyl group, a carbonyl group, a carboxyl group, an amino group, a thiol group, a silanol group, a sulfo group, a sulfonate, and an ammonium group. In the case of having a hydrophilic group, when the protective agent is linked to the specific transition metal compound by a linking group, the hydrophilic group contained in the protective agent is disposed on the organic group covering the surface of the specific transition metal compound. Therefore, the nanoparticle surface becomes hydrophilic, becomes dispersible in the hydrophilic solvent, and has high dispersion stability.
Thus, since the nanoparticle used for this invention containing a protective agent becomes a thing with very high dispersion stability in a solvent, it can form a thin film of nm order with high temporal stability and high uniformity.

  In the present invention, an embodiment in which the protective agent has the hydrophilic group in addition to the linking group is preferably used. This is because the light emitting layer, the electron injecting / transporting layer, and the like, which are lower layers when forming the charge generation layer by the solution coating method, tend to be easily dissolved in a hydrophobic solvent such as toluene, xylene, cyclohexanone. In the transition metal compound nanoparticles of (B), when the protective agent has the hydrophilic group in addition to the linking group, it can be stably dispersed in the hydrophilic solvent. The charge generation layer can be stably formed on the electron transport layer and the light emitting layer that are easily dissolved in the film by a solution coating method using a hydrophilic solvent. Further, the formed charge generation layer becomes hydrophilic. Therefore, even if an organic layer is formed adjacent to the hydrophilic charge generation layer by a solution coating method using a hydrophobic solvent, the charge generation layers are stably formed without re-dissolution. it can.

The hydrophilic solvent is a solvent that is compatible with water at a certain ratio. As the hydrophilic solvent, water or solubility in water (20 ° C.) is 5 g / L or more, and it can be used without any particular limitation. The hydrophilic solvent is preferably a solvent that can be mixed with water at an arbitrary ratio.
On the other hand, as a hydrophobic solvent, the solubility in water (20 ° C.) can be taken as a guideline to be less than 5 g / L.

In the present invention, since the transition metal of the transition metal compound is one or more metals selected from the group consisting of molybdenum, tungsten, and vanadium, the amine compound is highly reactive to the amine compound. It is easy to form a charge transfer complex, and has a high charge generation function.
The nanoparticles used in the present invention may have a single structure or a composite structure, and may have a core / shell structure, an alloy, an island structure, or the like. The transition metal compound contained in the nanoparticles is at least one selected from the group consisting of transition metal oxides, transition metal carbide oxides, transition metal nitride oxides, and transition metal sulfide oxides. In addition to these, borides, selenides, halides, complexes, and the like may be included.

By including at least one selected from the group consisting of transition metal oxides, transition metal carbide oxides, transition metal nitride oxides and transition metal sulfide oxides in the nanoparticles, the value of ionization potential can be optimized. By suppressing changes due to oxidation from an unstable oxidation number +0 metal in advance, it becomes possible to reduce the drive voltage and improve the element lifetime in the device.
Among these, it is preferable that transition metal compounds that are oxides having different oxidation numbers coexist in the nanoparticles. By including transition metal compounds with different oxidation numbers in combination, the charge transportability and charge injection properties are appropriately controlled by the balance of oxidation numbers, which can reduce drive voltage and improve device life. become. Note that transition metal atoms and compounds of various valences such as oxides and borides may be mixed in the nanoparticles depending on the processing conditions.

  In the transition metal carbide oxide, transition metal nitride oxide, and transition metal sulfide oxide, at least a part of the transition metal carbide, transition metal nitride, and transition metal sulfide only needs to be oxidized. Preferably, in each of transition metal carbide, transition metal nitride, and transition metal sulfide, the surface layer of about 1 nm is preferably oxidized.

The protective agent that adheres to the surface of the nanoparticle and protects the surface of the nanoparticle has an organic group having 1 or more carbon atoms in addition to the linking group linked to the nanoparticle.
The protective agent may be a low molecular compound or a high molecular compound, but is preferably a low molecular compound having a molecular weight of about 1000 or less from the viewpoint of solubility and dispersion stability.

  In the protective agent, the number of the linking groups may be any number as long as it is one or more in the molecule. However, when it is desired to obtain more uniform nanoparticles, it is preferable that different substituents are employed for the linking group and the hydrophilic group described later, and there is one linking group in one molecule of the protective agent.

  The organic group contained in the protective agent is an organic group having 1 or more carbon atoms, preferably 1 to 30 carbon atoms, preferably 2 or more carbon atoms, more preferably 2 to 30 carbon atoms, still more preferably. 2 to 25, particularly preferably 4 to 25 linear, branched or cyclic saturated or unsaturated aliphatic hydrocarbon group, 6 to 40 carbon atoms, more preferably 12 to 34, still more preferably 12 to 26 Aromatic hydrocarbon groups and heterocyclic groups, and combinations of these structures may be mentioned. The carbon number here does not include the carbon number of the substituent of the aliphatic hydrocarbon group, aromatic hydrocarbon group, and heterocyclic group.

Among them, as the organic group, the part directly bonded to the linking group does not have a bulky structure such as a cyclic structure, that is, an aliphatic hydrocarbon group, and the protective agent protects the surface through the linking group. It is preferable from the point that it can be protected densely without defects, and the presence of one or more carbon atoms in a linear structure can sufficiently maintain the distance between the transition metal compounds of the core of the nanoparticle. It is preferable from the point which can prevent mutual aggregation.
On the other hand, when the protective agent contains at least one of an aromatic hydrocarbon group and a heterocyclic group as an organic group, it has charge transporting properties, or due to improved adhesion with an adjacent amine compound, etc. The dispersion stability of the film can be improved.

Specific examples of the aromatic hydrocarbon and / or heterocyclic ring include benzene, triphenylamine, fluorene, biphenyl, pyrene, anthracene, carbazole, phenylpyridine, trithiophene, phenyloxadiazole, phenyltriazole, and benzimidazole. , Phenyltriazine, benzodiathiazine, phenylquinoxaline, phenylene vinylene, phenylsilole, and combinations of these structures.
Moreover, unless the effect of this invention is impaired, you may have a substituent in the structure containing an aromatic hydrocarbon and / or a heterocyclic ring. Examples of the substituent include a linear or branched alkyl group having 1 to 20 carbon atoms, a halogen atom, an alkoxy group having 1 to 20 carbon atoms, a cyano group, and a nitro group.

  When the protective agent contains both a hydrophilic group and a linking group, the linking group and the hydrophilic group may be the same type of substituent, but at least a substitution that functions as a linking group in one molecule. One group and one substituent that functions as a hydrophilic group are included. However, when the linking group and the hydrophilic group are the same, the protective agent has a plurality of linking groups, and there is a concern that the nanoparticles may be bonded and aggregated via the linking group. From the standpoint of maintenance, in the protective agent, the linking group and the hydrophilic group are preferably different from each other. In particular, it is more preferable that the protective agent includes one or more hydrophilic groups that are not easily bonded to the nanoparticles and one linking group that is easily bonded to the nanoparticles.

  When the protective agent includes both a hydrophilic group and a linking group, the hydrophilic group is selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, a thiol group, a sulfo group, a sulfonate, and an ammonium group. 1 or more selected from the group consisting of a hydroxyl group, a carboxyl group, a thiol group, a sulfo group, and a sulfonate salt. It is preferable that

Among them, the linking group preferably includes at least one of a thiol group and an amino group, and the hydrophilic group preferably includes at least one of a carboxyl group, a hydroxyl group, a sulfo group, and a sulfonate.
For example, a combination of a linking group such as a thiol group and a carboxyl group, an amino group and a carboxyl group, a thiol group and a hydroxyl group, a thiol group and a sulfonate, an amino group and a sulfonate, an amino group and a hydroxyl group, and a hydrophilic group is preferable. Used for.

Specific examples in the case where the protective agent is a low molecular weight compound containing both a hydrophilic group and a linking group are not limited thereto, but include thioglycolic acid, glycine, 4-hydroxythiophenol, 4 -Mercaptophenylacetic acid, sodium 3-mercapto-1-propanesulfonate, sodium 2-mercaptoethanesulfonate, 2-aminoethanesulfonic acid, 6-amino-1-hexanol, 12-amino-1-dodecanol, biphenyl -4,4'-dicarboxylic acid, benzidine, 4- (4-aminophenyl) benzonitrile, 4,4'-diformyltriphenylamine, tris (4-formylphenyl) amine, N, N, N ', N Examples include '-tetrakis (4-aminophenyl) benzidine.
In addition, when the protective agent is a low molecular compound having a molecular weight of 1000 or less, since the protective agent covering the nanoparticle surface is thin, the transition metal-containing compound surface approaches the adjacent layer compound and interacts with it. The transition metal-containing compound is preferable because it can be expected to have a merit that it easily contributes to the improvement of the charge injection property. Although it does not specifically limit as a minimum of the molecular weight of a protective agent, It can be set as a standard that it is 50 or more.

  When the protective agent is a polymer compound containing both a hydrophilic group and a linking group, a polymer compound containing two or more functional groups functioning as a linking group and a hydrophilic group is appropriately selected. Can be used. As the polymer compound, a polymer having a repeating unit is preferably used, and the weight average molecular weight is, for example, greater than 1000 and about 50000 or less. The weight average molecular weight in this invention says the polystyrene conversion value by GPC (gel permeation chromatography). Specific examples of the polymer compound used as the protective agent include, but are not limited to, polyvinylpyrrolidone, polyglycolide, poly (2-acrylamido-2-methyl-1-propanesulfonic acid), poly ( Acrylamide-acrylic acid) copolymer and the like.

  The protective agent preferably has a solubility (20 ° C.) in the solvent used of 10 g / L or more, more preferably 50 g / L or more, from the viewpoint that the nanoparticles can be dispersed in the solvent.

  In the specific transition metal compound nanoparticles of the present invention, the content ratio of the transition metal compound and the protective agent is appropriately selected depending on the application and is not particularly limited, but the protective agent is 10 parts per 100 parts by mass of the transition metal compound. It is preferable that it is -40 mass parts.

The average particle diameter of the specific transition metal compound nanoparticles used in the present invention is not particularly limited and may be, for example, 0.5 nm to 999 nm, and may be appropriately selected depending on the application. The average particle size is preferably 0.5 nm to 50 nm, and more preferably 0.5 nm to 20 nm. In the case of forming a thin film having a thickness of 20 nm or less, the thickness is further preferably 15 nm or less, particularly preferably in the range of 1 nm to 10 nm. This is because it is difficult to produce a product having a particle size that is too small. On the other hand, if the particle size is too large, the surface area per unit mass (specific surface area) may be small and the desired effect may not be obtained, and the surface roughness of the thin film may be large and shorts may occur frequently. Because.
Here, the average particle diameter is the number average particle diameter measured by the dynamic light scattering method. In the state dispersed in the charge generation layer, the average particle diameter is measured using a transmission electron microscope (TEM). A value obtained by selecting a region in which 20 or more nanoparticles are confirmed from the obtained image, measuring the particle diameter of all the nanoparticles in this region, and obtaining an average value. And

  The manufacturing method of the specific transition metal compound nanoparticle used for this invention will not be specifically limited if it is a method which can obtain the transition metal compound nanoparticle mentioned above. For example, a liquid phase method such as a reaction between a transition metal complex and the protective agent in an organic solvent can be used. For example, it can be appropriately prepared with reference to Japanese Patent Application Laid-Open No. 2011-119681, Table 2012/018082, and Japanese Patent Application Laid-Open No. 2012-069963.

<Amine compound>
The amine compound used in the present invention is a compound containing an amino group which is an electron donating group. Since the amine compound functions as an electron donating compound, it reacts with at least one of the compound represented by (A) the specific general formula (I) and the (B) specific transition metal-containing nanoparticles. Thus, it is presumed that a charge transfer complex is formed and a function as a charge generation layer is realized.

As the amine compound, in addition to a low molecular compound, a high molecular compound is also preferably used. In the charge generation layer of the present invention, for the purpose of forming a stable film by a solution coating method, the amine compound is a high-capacity compound capable of forming a stable coating film that is easily dissolved in an organic solvent and is difficult to aggregate. It is preferable to use molecular compounds. It is preferable to appropriately select and use an amine compound having a weight average molecular weight of 2000 or more.
As the amine compound, a known amine compound used as a hole transporting material or a charge transporting material can be appropriately selected and used.

The amine compound used in the present invention is preferably an aromatic amine compound, and various aromatic amine derivatives are preferably used. The aromatic amine compound is preferably a triarylamine derivative including a triphenylamine structure as a partial structure.
Specific examples of the aromatic amine compound include N, N′-bis- (3-methylphenyl) -N, N′-bis- (phenyl) -benzidine (TPD), bis (N- (1-naphthyl-N -Phenyl) benzidine) (α-NPD), 4,4 ', 4 "-tris (3-methylphenylphenylamino) triphenylamine (MTDATA), 4,4', 4" -tris (N- (2- Naphthyl) -N-phenylamino) triphenylamine (2-TNATA) and the like, but are not limited thereto, anthracene derivatives, carbazole derivatives, thiophene derivatives, fluorene derivatives, distyrylbenzene derivatives, spiro compounds Such an electron donating compound may be further included in the molecule.
Examples of the amine-based polymer compound include a polymer containing an aromatic amine derivative in a repeating unit. The polymer may be a copolymer further containing an electron-donating compound such as an anthracene derivative, carbazole derivative, thiophene derivative, fluorene derivative, distyrylbenzene derivative, and spiro compound in a repeating unit.

  As the amine-based polymer compound, among them, the compound represented by the following general formula (1) tends to improve the adhesion stability with the adjacent organic layer, and the HOMO energy value is a material for the anode substrate and the light emitting layer. It is also preferable from the point of being between.

(In Formula (1), Ar _{1 to} Ar ₄ may be the same or different from each other, and are unsubstituted or substituted aromatic carbonized carbon atoms having 6 to 60 carbon atoms related to the conjugated bond. A hydrogen group or an unsubstituted or substituted heterocyclic group having 4 or more and 60 or less carbon atoms with respect to a conjugated bond, wherein n is 1 to 10,000, m is 0 to 10,000, and n + m = 10 to 20,000. In addition, the arrangement of the two repeating units is arbitrary.)

The arrangement of the two repeating units is arbitrary, and for example, any of a random copolymer, an alternating copolymer, a periodic copolymer, and a block copolymer may be used.
The average of n is preferably 5 to 5000, and more preferably 10 to 3000. Moreover, it is preferable that the average of m is 5-5000, Furthermore, it is preferable that it is 10-3000. Moreover, it is preferable that the average of n + m is 10-10000, and it is more preferable that it is 20-6000.

In Ar _{1 to} Ar ₄ of the above general formula (1), specific examples of the aromatic hydrocarbon in the aromatic hydrocarbon group include benzene, fluorene, naphthalene, anthracene, combinations thereof, and derivatives thereof. Furthermore, a phenylene vinylene derivative, a styryl derivative, etc. are mentioned. Specific examples of the heterocyclic ring in the heterocyclic group include thiophene, pyridine, pyrrole, carbazole, combinations thereof, and derivatives thereof.
When Ar < ₁ > -Ar < ₄ > of the said General formula (1) has a substituent, it is preferable that the said substituent is a C1-C12 linear or branched alkyl group or alkenyl group.

  As the compound represented by the general formula (1), specifically, for example, poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- (4, represented by the following formula (2): 4 ′-(N- (4-sec-butylphenyl)) diphenylamine)] (TFB), poly [(9,9-dioctylfluorenyl-2,7-diyl) -alt represented by the following formula (3) -Co- (N, N'-bis {4-butylphenyl} -benzidine N, N '-{1,4-diphenylene})] is a preferred compound.

  When the charge generation layer of the present invention is composed of one mixed layer containing at least one of (A) and (B) and an amine compound, in the charge generation layer, The content of at least one of (A) and (B) is 10 to 90 parts by weight, more preferably 15 to 60 parts by weight, with respect to 100 parts by weight of the amine compound. This is preferable from the standpoint of enhancing the charge generation function and achieving a long life with high film stability. The mixed layer may contain other components as described later, but in the mixed layer, the total amount of at least one of (A) and (B) and an amine compound. However, it is preferable that it is 90 mass% or more with respect to the total solid of a mixed layer, it is preferable that it is 95 mass% or more, and it is still more preferable that it is 99 mass% or more. Here, solid content means components other than a solvent, and a liquid low molecular weight compound is also contained.

On the other hand, when the charge generation layer of the present invention is a layer in which a layer containing at least one of (A) and (B) and a layer containing an amine compound are laminated, the density of the material In the charge generation layer, the content of at least one of (A) and (B) is 100 parts by weight of the amine compound. From 1 to 500 parts by weight, more preferably from 5 to 300 parts by weight from the viewpoints of increasing the charge generation function and high film stability and achieving a long life.
When the charge generation layer of the present invention is a layer in which a layer containing at least one of (A) and (B) and a layer containing an amine compound are laminated, the (A) and In the layer containing at least one of (B), the total amount of at least one of (A) and (B) is preferably 90% by mass or more based on the total solid content of the layer. It is preferably 95% by mass or more, and more preferably 99% by mass or more. In the layer containing the amine compound, the total amount of the amine compound is preferably 90% by mass or more, more preferably 95% by mass or more, based on the total solid content of the layer. Furthermore, it is preferable that it is 99 mass% or more.
In the charge generation layer of the present invention, at least one of (A) and (B) and the amine compound may be used alone or in combination of two or more. It may be used.

When the component having a melting point or glass transition temperature of 200 ° C. or less is contained in at least one ligand (A) and (B), a protective agent, or an amine compound, the organic material described later In the method for producing an EL element, even after the charge generation layer precursor coating film is dried and the solvent is removed, at least one of the above (A) and (B) is obtained by heating the charge generation layer precursor coating film. When a ligand, a protective agent, or an amine-based compound melts, adhesion occurs in the charge generation layer precursor coating, and the charge generation layer precursor coating adheres to an adjacent layer during cooling, and the charge generation layer It is preferable because it can be formed.
As the component having a melting point or glass transition temperature of 200 ° C. or less contained in at least one kind of the ligand (A) and (B), the protective agent, or the amine compound, among them, a resin substrate or an organic layer It is preferable that the melting point or the glass transition temperature is 160 ° C. or less from the viewpoint of not greatly exceeding the glass transition temperature. On the other hand, as a component having a melting point or glass transition temperature of 200 ° C. or less contained in at least one kind of ligand (A) and (B), a protective agent, or an amine compound, it occurs when driving an organic EL panel. From the viewpoint of preventing remelting by heat, the melting point or glass transition temperature is preferably 18 ° C. or higher, more preferably 40 ° C. or higher. The glass transition temperature here is measured by DSC (Differential Scanning Calorimetry).
In addition, a component having a melting point or a glass transition temperature of 200 ° C. or less contained in at least one kind of the ligand (A) and (B), the protective agent, or the amine compound is a charge generation layer precursor coating to be melted. The solid content of the film is preferably about 10% by mass or more from the viewpoint of adhesion, preferably 80% by mass or less, and more preferably 70% by mass or less from the viewpoint of charge generation function. preferable.

  The charge generation layer of the present invention may contain other components as long as the effects of the present invention are not impaired. For example, a known electron donating compound different from amine compounds such as carbazole and thiophene may be appropriately selected and further added. In addition, additives such as various binder resins, curable resins, and coatability improvers may be included. Examples of the binder resin include polycarbonate, polystyrene, polyarylate, and polyester. Moreover, you may contain the binder resin hardened | cured with a heat | fever or light. As a material that is cured by heat or light, a material having a curable functional group introduced into the molecule in the charge transporting compound, a curable resin, or the like can be used. Specifically, examples of the curable functional group include acrylic functional groups such as acryloyl group and methacryloyl group, vinylene group, epoxy group, and isocyanate group. The curable resin may be a thermosetting resin or a photocurable resin, and examples thereof include an epoxy resin, a phenol resin, a melamine resin, a polyester resin, a polyurethane resin, a silicon resin, and a silane coupling agent. be able to.

The film thickness of the charge generation layer can be appropriately determined depending on the purpose and the adjacent layer, and the charge generation layer contains at least one of (A) and (B) and an amine compound. Even if the mixed layer is a layer in which a layer containing at least one of the above (A) and (B) and a layer containing an amine compound are laminated, Usually, it is 0.1 to 200 nm, preferably 1 nm to 150 nm. In particular, when a layer is further formed on the charge generation layer by a coating method, the problem that the solvent at the time of forming the upper layer of the charge generation layer penetrates through the charge generation layer and dissolves the lower layer of the charge generation layer is suppressed. In addition, when the film thickness is increased, the thickness is more preferably 20 nm to 150 nm.
When the charge generation layer of the present invention is a layer in which a layer containing at least one of (A) and (B) and a layer containing an amine compound are laminated, the (A) and The ratio of the film thickness of the layer containing at least one kind of (B) and the layer containing an amine compound is preferably 1: 0.1 to 1:50 from the viewpoint of the charge generation function.
When the charge generation layer is a layer in which a layer containing at least one of (A) and (B) and a layer containing an amine compound are laminated, at least one of the above (A) and (B) It is preferable from the viewpoint of the charge generation function that the layer containing one kind is disposed on the anode side, and the layer containing the amine compound is disposed on the cathode side. Generally, an amine compound has a higher vacuum level than at least one of the above (A) and (B), that is, LUMO, and can function as an electron block layer or a hole transport layer. ) And (B) are arranged on the anode side, it is easier to move electrons generated from the charge generation layer to the light emitting layer on the anode side, and contains an amine compound. This is because it is easier to move holes generated from the charge generation layer to the light emitting layer on the cathode side by disposing the layer to be disposed on the cathode side.

(2) Light-emitting unit The light-emitting unit used in the present invention includes at least a light-emitting layer, and any one of the layers is composed of an organic compound layer. When the light emitting unit is composed of multiple layers, the light emitting unit appropriately includes a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, and a known functional layer used for an EL element in addition to the light emitting layer. It may be included.
Although illustration is given for each layer, it is not limited thereto, and a known configuration can be adopted as appropriate.

<Light emitting layer>
The light emitting layer 5 is formed of a light emitting material. The light emitting material used for the light emitting layer of the present invention is not particularly limited as long as it is a general light emitting material used for an organic EL device, and any of a fluorescent material and a phosphorescent material can be used. Specifically, materials such as a dye-based luminescent material and a metal complex-based luminescent material can be given. As the light-emitting material, either a low molecular compound or a high molecular compound can be used. For example, it can be formed by the materials and methods described in paragraphs 0094 to 0100 of JP 2010-272891 A and paragraphs 0053 to 0060 of international publication 2012-132126.
Further, a dopant may be added to the organic light emitting layer for the purpose of improving the light emission efficiency and changing the light emission wavelength. As such a dopant, the general thing used for an organic light emitting layer can be mentioned.
The thickness of the light emitting layer is usually about 1 nm to 500 nm, preferably about 20 nm to 1000 nm.

<Hole injection transport layer, hole transport layer, and hole injection layer>
The hole injection transport layer, the hole transport layer, and the hole injection layer are appropriately formed between the light emitting layer and the electrode that is the anode. A hole transport layer may be further laminated on the hole injecting and transporting layer, and a light emitting layer may be laminated thereon, or a hole injecting and transporting layer may be further laminated on the hole injecting layer, A light emitting layer may be laminated, or a hole injection / transport layer may be laminated on the electrode, and a light emitting layer may be laminated thereon.
As materials used for the hole injection transport layer, the hole transport layer, and the hole injection layer, known materials may be appropriately selected and used. For example, the compounds described in paragraphs 0105 to 0106 of JP2011-119681A, Table 2012/018082, JP2012-069963, and WO2012-132126 can be appropriately selected and used.

The thicknesses of the hole injection layer, the hole injection transport layer, and the hole transport layer can be appropriately determined depending on the purpose and the adjacent layers, but are usually 0.1 nm to 1 μm, preferably 1 nm to 500 nm, and more preferably. Is 5 nm to 200 nm.
Furthermore, in consideration of the hole injection characteristics, the hole injection material and the hole transport material are selected so that the work function value of each layer increases stepwise from the anode side toward the light-emitting layer. It is preferable to make the energy barrier for hole injection as small as possible and complement the energy barrier for large hole injection between the electrode and the light emitting layer.

<Electron injection transport layer, electron transport layer, and electron injection layer>
The electron injecting and transporting layer, the electron transporting layer, and the electron injecting layer are appropriately formed between the light emitting layer and the electrode that is the cathode. An electron transport layer may be laminated on the light emitting layer, and an electron injection layer may be further laminated on the electron transport layer.
As materials used for the electron injecting and transporting layer, the electron transporting layer, and the electron injecting layer, known materials may be appropriately selected and used. Examples thereof include metal complexes such as bathocuproin, bathophenanthroline, phenanthroline derivatives, triazole derivatives, oxadiazole derivatives, pyridine derivatives, tris (8-quinolinolato) aluminum (Alq3), and polymer derivatives thereof. For example, an alkali metal salt layer of an 8-quinolinol derivative such as 8-quinolinolatolithium (Liq) is formed, and a layer obtained by vacuum-depositing aluminum, which is a typical heat-reducible metal, on the layer. This is one of the preferred configurations. At this time, since the aluminum metal undergoes an in-situ reduction reaction of alkali metal ions (Li + in Liq), the aluminum metal itself changes to an oxidized state to become an aluminum ion-containing compound. Further, the Li metal produced by reduction is converted into a ((Li + Alq →) Li ⁺ + Alq ⁻ (radical anion)) charge transfer complex by an oxidation-reduction reaction by transferring electrons with an electron transporting organic substance (eg, Alq) in the vicinity. Form.
In addition, the materials and methods described in Paragraphs 0031 to 0052 and 0098 to 0104 of International Publication No. 2012-132126 can be appropriately selected and used.
In addition, as a material containing an organic component used for the electron injection transport layer, the electron transport layer, and the electron injection layer, when the charge generation layer according to the present invention is formed by a solution coating method, the remaining film ratio is increased. Therefore, the molecular weight or the weight average molecular weight is preferably 500 or more.

When the organic EL element of the present invention includes two or more light emitting units, each light emitting unit may be the same or different. The layer configuration included in each light emitting unit may be different, and the materials included in each layer may be different.
Although the thickness of one light emission unit should just be adjusted suitably, it is preferable that it is 30-200 nm.

(3) Electrode The organic EL device of the present invention has a first electrode and a second electrode, and at least two electrodes facing each other on the substrate. In the organic EL device of the present invention, each of the first electrode and the second electrode is usually either an anode or a cathode. For example, in FIG. 2, the electrode 1 functions as an anode for injecting holes into the light emitting layer. The electrode 5 acts as a cathode for injecting electrons into the light emitting layer. However, when there is one light emitting unit as shown in FIG. 1, the first electrode is usually an anode, but since the charge generation layer can serve as a substitute for the second electrode, the second electrode is a blocking electrode. (Deactivated electrode) may be used.
The first electrode and the second electrode differ depending on which electrode is required to be transparent depending on the extraction direction of light emitted from the light emitting layer. For example, in FIG. 2, when light is extracted from the substrate 6 side, the electrode 1 must be formed of a transparent material, and when light is extracted from the electrode 5 side, the electrode 5 must be formed of a transparent material. is there.
In the organic EL device of the present invention, the electrode is preferably formed of a metal or a metal oxide, and a known material can be appropriately employed. Usually, it can be formed of a metal such as aluminum, gold, silver, nickel, palladium, or platinum, or a metal oxide such as ITO (indium tin oxide) or IZO (indium zinc oxide). In order to obtain a transparent electrode, it is preferably formed of an oxide of indium and / or tin.

Usually, the electrode is often formed on the substrate by a method such as a sputtering method or a vacuum deposition method, but can also be formed by a wet method such as a coating method or a dipping method. The thickness of the electrode varies depending on the transparency required for each electrode. When transparency is required, the light transmittance in the visible light wavelength region of the electrode is usually 60% or more, preferably 80% or more. In this case, the thickness is usually 10 to 1000 nm, Preferably, it is about 20 to 500 nm.
In the present invention, a metal layer may be further provided on the electrode in order to improve the adhesion stability with the charge injection material. The metal layer refers to a layer containing a metal, and is formed from a metal or metal oxide used for the above-described normal electrode.
In addition, materials and methods described in paragraphs 0062 to 0097 of International Publication No. 2012-132126 can be appropriately selected and used.

(4) Substrate The substrate serves as a support for the organic EL element of the present invention, and may be, for example, a flexible material or a hard material. Specific examples of materials that can be used include glass, quartz, polyethylene, polypropylene, polyethylene terephthalate, polymethacrylate, polymethyl methacrylate, polymethyl acrylate, polyester, and polycarbonate.
Among these, when using a synthetic resin substrate, it is desirable to have a gas barrier property. Although the thickness of a board | substrate is not specifically limited, Usually, it is about 0.005-5 mm.
When light emitted from the light emitting layer is extracted through the substrate 6 side, at least the substrate 6 needs to be made of a transparent material.
In addition, the materials and methods described in paragraph 0109 of International Publication No. 2012-132126 can be appropriately selected and used.

(5) Characteristics and applications of the organic EL element of the present invention The organic EL element of the present invention can include two or more light emitting units, and therefore, the organic EL element including one light emitting unit and the light extracted When compared at the same intensity, the device can be made to emit light with less power applied to each light emitting layer than an organic EL device including one light emitting unit, so that the life of the device can be extended. .
Moreover, even if the organic EL element of the present invention is an organic EL element including one light emitting unit, it has a charge generation layer, so there is no need to consider the energy barrier between the cathode and the electron injection layer, and charge generation Since it is only necessary to consider an electron injection / transport layer in which electrons generated from the layer move and an energy barrier on the light emitting layer side, the design for lowering the voltage is facilitated. As a result, improvement in device characteristics such as power efficiency and lifetime can be expected.

  In addition, since the organic EL element of the present invention can include two or more light emitting units, color mixing can be achieved by making the emission wavelengths of the light emitting layers included in the light emitting units that emit light simultaneously differ from each other. Thus, the color of light extracted from the organic EL element can be different from the color of light emitted from each light emitting layer. For example, by mixing the emission wavelengths of the respective light emitting layers included in each light emitting unit as two complementary colors, or mixing them as three RGB colors, the color of the extracted light can be white.

  The organic EL device of the present invention can be suitably used for a display device, a display, an electrophotography, a backlight, an illumination light source, a recording light source, an exposure light source, a reading light source, a sign, a signboard, an interior, or optical communication. The lighting device will be described later.

2. Manufacturing method of organic EL element The manufacturing method of the organic EL element of the present invention includes at least one light emitting unit including a first electrode, a second electrode, and a light emitting layer disposed between the first electrode and the second electrode. And a charge generation layer disposed between the light emitting unit and the second electrode when there is one light emitting unit, and between adjacent light emitting units when there are two or more light emitting units. A method for producing an organic electroluminescence device having
The charge generation layer is formed by a coating method using one or more inks containing at least one of the following (A ′) and (B) and an amine compound mixed or each of them. It is the manufacturing method of an organic electroluminescent element which has the process to do.

(A ′) a compound represented by the following general formula (I);

(In General Formula (I), M is at least one of molybdenum, tungsten, and vanadium, and R ¹ and R ² may each independently have a substituent and include a hetero atom. And represents an aliphatic hydrocarbon group, an aromatic ring group, or a combination thereof, where n represents a positive number of 1 to 3, and m represents a positive number of 0 to 2.)

(B) Transition metal-containing nanoparticles comprising at least one transition metal compound selected from the group consisting of transition metal oxides, transition metal carbide oxides, transition metal nitride oxides, and transition metal sulfide oxides, and a protective agent The transition metal is at least one of molybdenum, tungsten, and vanadium, and the transition metal-containing nanoparticles are formed by attaching a protective agent that protects the surface to the particle surface. A linking group capable of linking to a transition metal compound and an organic group having 2 or more carbon atoms, wherein the linking group includes a hydroxyl group, a sulfonamide group, and functional groups represented by the following general formulas (1a) to (1o) One or more transition metal compound nanoparticles selected from the group consisting of groups;

(In the formula, Z ₁ , Z ₂ and Z ₃ each independently represent a halogen atom or an alkoxy group, and R represents a hydrogen atom or a methyl group.)

  According to the method for producing an organic EL element of the present invention, the charge generation layer can be formed by a coating method. In the stack type organic EL device, if the charge generation layer can be formed only by the vapor deposition method, even if the light emitting unit such as the light emitting layer is formed by the solution coating method, the advantage of the solution coating method cannot be utilized after all. However, according to the present invention, a stable charge generation layer can be formed by a solution coating method. Therefore, the method for producing an organic EL element of the present invention is excellent in terms of increasing the area and productivity.

In the present invention, there is also provided an ink for forming a charge generation layer of an organic EL element, which contains at least one of (A ′) and (B).
The ink for forming a charge generation layer of the organic EL element is an ink containing at least one of (A ′) and (B) and an amine compound, or (A ′) and An ink set of an ink containing at least one of (B) and an ink containing an amine compound may be used.

  The (A ′), the (B), and the amine compound have been described in the (A), the (B), and the amine compound, and the description thereof is omitted here.

Examples of the step of forming the charge generation layer by a coating method using one or more inks containing at least one of (A ′) and (B) and an amine compound include, for example, The following processes are mentioned.
In the present invention, the first method for forming the charge generation layer by a coating method includes ink (α) containing at least one of (A ′) and (B), and ink containing an amine compound. And a charge generation layer formed by laminating a layer containing at least one of (A ′) and (B) and a layer containing an amine compound, using two types of inks. Process.
In the present invention, as a second method for forming the charge generation layer by a coating method, the ink (β) containing at least one of (A ′) and (B) and an amine compound is used. A step of forming a charge generation layer containing at least one of (A) and (B) and an amine compound by a coating method;

Also, an ink (α) containing at least one of (A ′) and (B), and an ink (β) containing at least one of (A ′) and (B) and an amine compound, A layer containing at least one of (A ′) and (B), a mixed layer of at least one of (A ′) and (B) and an amine compound, using two types of ink; May be a step of forming a charge generation layer on which is stacked by a coating method.
Further, an ink (β-1) containing at least one of (A ′) and (B) and an amine compound, at least one of (A ′) and (B), and an amine compound And (A ′) and (A) and (A) and (B), and two types of inks in which the ratio of at least one of (A ′) and (B) to the amine compound is different. It may be a step of forming a charge generation layer in which two layers of a mixed layer of at least one kind of B) and an amine compound are laminated by a coating method.
Further, a layer containing at least one of (A ′) and (B), a layer containing an amine compound, and a mixture of at least one of (A ′) and (B) and an amine compound. It may be a step of forming a charge generation layer in which three layers are laminated by a coating method.

Among them, the ink (α) containing at least one of the above (A ′) and (B), the ink containing the amine compound, and two inks are used, and the (A ′) and ( The step of forming a charge generation layer by laminating a layer containing at least one kind of B) and a layer containing an amine compound by a coating method improves the function as the charge generation layer, and the luminous efficiency, luminance From the viewpoint of improving the life.
On the other hand, when a mixed layer is formed using an ink containing at least one of (A ′) and (B) and an amine compound, at least one of (A ′) and (B). And the amine compound, the contact area between the amine compound and at least one of (A ′) and (B) is increased, the charge generation function is improved, and the coating process is omitted. From the viewpoint of high productivity.

  The ink containing an amine compound usually further contains a solvent for dissolving the amine compound. As the solvent, it is preferable to use a solvent capable of dissolving 0.1% by mass or more of the amine compound at 25 ° C., more preferable to use a solvent capable of dissolving 1% by mass or more, and to dissolve 5% by mass or more. Even more preferred. The solvent may be a mixed solvent.

  In the ink containing at least one of (A ′) and (B), as the ink containing (A ′), the compound represented by the general formula (II) as a raw material also functions as a solvent. Then, since the reaction solution can be used as it is, it does not have to contain any further solvent. The ink containing (A ′) may contain a solvent, and it is preferable to use a solvent that dissolves (A ′) at 0.1% by mass or more at 25 ° C. It is more preferable to use a solvent that dissolves 1% by mass or more, and even more preferable to dissolve 5% by mass or more. The solvent may be a mixed solvent.

  In the ink containing at least one of (A ′) and (B), the ink containing (A ′) contains 0.1% by mass or more of (A ′) in the total amount of the ink. Further, when the film thickness is increased, it is preferably contained in an amount of 0.6 to 20% by mass.

When the charge generation layer is formed using the ink containing (A ′), it is represented by the general formula (II) and at least one metal complex of molybdenum, tungsten, and vanadium as raw materials. A step of preparing the (A ′) by heating a mixture with the compound to form a charge generation layer by applying an ink containing the (A ′), It is preferable from the viewpoint of improving the life that all steps from the step of preparing ') to the step of forming the charge generation layer are performed in an inert gas atmosphere.
In this case, not only was it not affected by atmospheric oxygen and moisture during the preparation of (A ′), but also when the ink was prepared using the prepared (A ′). Even when the charge generation layer is formed using the ink containing (A ′), the prepared (A ′) is not affected by oxygen and moisture in the atmosphere, and the prepared (A ′) is in contact with water, It is presumed that the reaction product of oxygen and some reaction product in the system is prevented from being generated during the process and mixed into the hole injecting and transporting layer.
Note that the inert gas atmosphere refers to an atmosphere filled with an inert gas such as nitrogen, argon, helium, or neon. The oxygen concentration in the inert gas atmosphere can be 1 ppm or less, and the water concentration can be 1 ppm or less.

In the ink containing at least one of (A ′) and (B), the ink containing (B) is preferably dispersed in a solvent in which at least the (B) transition metal compound nanoparticles are well dispersed. Ink is used. The solvent used in the ink containing (B) is not particularly limited as long as the transition metal-containing nanoparticles and other components as required are dissolved or dispersed well. Considering the hydrophilicity and hydrophobicity of the protective agent, a solvent in which the protective agent is soluble is appropriately selected and used.
As the ink containing (B), it is preferable to contain 0.1% by mass or more of (B) in the total amount of ink. It is preferable to do.

When the charge generation layer is formed by a solution coating method, the light emitting layer or the electron transport layer, which is the lower layer, tends to dissolve in a hydrophobic solvent such as toluene, xylene, cyclohexanone, etc. It is preferable to form using a hydrophilic solvent.
For example, specific examples of the hydrophilic solvent include water, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, ethylene glycol, propylene glycol, butanediol, ethylhexanol, Benzyl alcohol, cyclohexanol, 12-amino-1-dodecanol, 2-methyl-2,4-pentanediol, diethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, etc. However, it is not limited to these.
If the lower layer of the charge generation layer does not dissolve even when a hydrophobic solvent is used when forming the charge generation layer, the charge generation layer may be formed using a hydrophobic solvent. Examples of the hydrophobic solvent and the low polarity solvent include toluene, xylene, mesitylene, dodecylbenzene, cyclohexanone, tetralin, mesitylene, anisole, methylene chloride, tetrahydrofuran, dichloroethane, chloroform, ethyl benzoate, butyl benzoate, acetonitrile, and the like. However, it is not limited to these.
Moreover, as long as the solvents are compatible with each other, the charge generation layer may be formed by appropriately selecting and using a mixed solvent of the hydrophilic solvent and the hydrophobic solvent.

As each solvent when laminating layers using two or more inks containing at least one of (A ′) and (B) and an amine compound, the ink is used. Thus, it is preferable to select and use a solvent that does not dissolve the lower layer serving as a base when the layers are stacked. Here, that the lower layer does not dissolve means that each lower layer does not completely dissolve (the remaining film ratio is 0%). If the lower layer is not completely dissolved, when two charge generation layers are stacked, one of the two layers may be hydrophilic, the other is hydrophobic, both are hydrophobic, and both are hydrophilic.
Among them, it is desirable to select a solvent that has a remaining film ratio of the lower layer of 10% or more, more preferably 30% or more, and still more preferably 50% or more.
Here, the remaining film ratio of the lower layer can be evaluated as follows.
First, a lower layer is formed on a quartz substrate (for example, 25 mm × 25 mm) with the material and thickness of the lower layer, and a test film is prepared. From the viewpoint of obtaining a more detailed residual film ratio, it is preferable that the test film is prepared as a test film for each layer as a lower layer, such as an electron injecting and transporting layer and a light emitting layer. For example, when the upper layer is applied by a spin coater, the solvent used for applying the upper layer to the test film is 1 mL for 25 mm × 25 mm, and the number of rotations at which a desired film thickness is obtained by a spin coater, Apply. The upper layer is dried under the conditions for drying to prepare a test film after application of the solution.
The remaining film ratio can be measured from the ratio of the absorbance (Abs) of the absorption maximum (λmax) of the organic EL material of each layer in the ultraviolet-visible absorption spectrum using an ultraviolet-visible spectrophotometer.
And
([Absorbance of absorption maximum of test film after application of solution] / [Absorbance of absorption maximum of test film before application of solution]) × 100 (%) = Residual film ratio (%) is calculated.
Normally, organic EL materials have absorption in the UV-visible absorption spectrum, so that the remaining film ratio can be calculated by the above method. However, when there is no absorption in the UV-visible absorption spectrum, an atomic force microscope ( The residual film ratio can be obtained by directly measuring the film thickness of the test film before and after application of the solution using an AFM) or a stylus type surface shape measuring instrument (for example, DEKTAK series, manufactured by SLOANA).

In the ink (β) containing at least one of (A ′) and (B) and an amine compound, both the at least one of (A ′) and (B) and the amine compound are favorable. Mixing in a solvent that dissolves or disperses facilitates formation of a charge transfer complex because at least one of (A ′) and (B) interacts with an amine compound in the solution, so that charge generation is facilitated. In addition, it is preferable in that a charge generation layer having excellent stability over time of the film can be formed.
The ink (β) preferably contains at least one of the above-mentioned (A ′) and (B) and the total amount of the amine compound in an amount of 0.1% by mass or more in the total amount of the ink, and is further thickened. In the case, it is preferable to contain 0.6-20 mass%.

  The charge generation layer of the present invention is formed by a solution coating method. In the charge generation layer of the present invention, one or two or more types of ink containing at least one of (A ′) and (B) and the amine compound in a mixed manner or each of the above-mentioned (A ') Since at least one of (B) and the amine compound have high affinity with the solvent, the ink should have high uniform stability by appropriately selecting the solvent. Can do. Therefore, according to the present invention, since the manufacturing process is easy and a highly stable and uniform film can be formed, a short circuit does not easily occur, so the yield is high and a charge transfer complex is formed to achieve a long life. It becomes possible.

  Here, the solution coating method refers to preparing one or two or more inks containing at least one of the above (A ′) and (B) and an amine compound, and the one or two or more inks. Is applied on a light emitting layer unit as a base and dried to form a charge generation layer. If necessary, the ink is dissolved or dispersed by adding other charge transporting compounds as described above and additives such as binder resins and coating property improving agents that do not trap holes and electrons. May be prepared.

  Examples of the solution coating method include immersion methods, spray coating methods, spin coating methods, blade coating methods, dip coating methods, casting methods, roll coating methods, bar coating methods, die coating methods, and liquid dropping methods such as inkjet methods. It is done. When it is desired to form a monomolecular film, a dipping method or a dip coating method is preferably used.

In particular, when manufacturing a stack type organic EL element, the following manufacturing method has high productivity and has fewer steps than a manufacturing method in which a stack type organic EL layer is applied and laminated on one substrate. As a result, it is preferable from the viewpoint of improving the yield. Further, according to the manufacturing method, there is a merit that a load for selecting a solvent that does not dissolve the lower layer is reduced. Further, even if the charge generation layer is a thin film, the upper layer is formed below the charge generation layer through the charge generation layer. The problem of dissolving the lower layer of the charge generation layer due to penetration of the solvent during formation does not occur.
That is, in the present invention, a preferable method for producing a stacked organic EL element is:
A step of preparing a first laminate including at least one light emitting unit including an anode and a light emitting layer on one surface side of the first substrate; and a light emitting unit including a cathode and a light emitting layer on the one surface side of the second substrate. Preparing a second laminate comprising at least one of the following:
A step of forming a charge generation layer precursor coating film by the following step (i), (ii), or (iii):
(I) forming a charge generation layer precursor coating film (M) on the light emitting unit side surface of the first laminate using an ink containing at least one of (A ′) and (B); Forming a charge generation layer precursor coating film (N) on the light emitting unit side surface of the second laminate using an ink containing an amine compound;
(Ii) The charge generation layer precursor coating film (N) and at least one of the above (A ′) and (B) are formed on the light emitting unit side surface of the second laminate using an ink containing an amine compound. A step of forming a charge generation layer precursor coating (M) in this order using an ink containing;
(Iii) Using an ink containing at least one of (A ′) and (B) and an amine compound on at least one light emitting unit side surface of the first laminate and the second laminate. The step of forming a charge generation layer precursor coating (MN) The light emitting unit side of the first laminate and the second laminate on which any one of the charge generation layer precursor coatings is formed face each other, and the charge And a step of attaching the first laminate and the second laminate via the generation layer precursor coating film and forming a charge generation layer.

A method for manufacturing the preferred stack type organic EL element will be described with reference to the drawings.
3 (A) to 3 (D) and FIGS. 4 (E) to (G) are process diagrams showing an example of a method for producing an organic EL element according to the present invention. The organic EL device manufacturing method according to the present invention includes at least one light emitting unit 13 including an anode 11 and a light emitting layer 12 on one surface side of the first substrate 10 as shown in FIG. First laminate 100 is prepared. On the other hand, as shown in FIG. 3B, a second stacked body 200 including at least one light emitting unit 23 including a cathode 21 and a light emitting layer 22 is prepared on one surface side of the second substrate 20. Next, as shown in FIG. 3C, a charge generation layer precursor is formed on the light emitting unit 13 side surface of the first laminate 100 using an ink containing at least one of (A ′) and (B). A coating film 14 (M) is formed. On the other hand, as shown in FIG. 3D, a charge generation layer precursor coating 24 (N) is formed on the surface of the second laminate 200 on the light emitting unit 23 side using an ink containing an amine compound. . Next, as shown in FIG. 4E, the light emitting unit 13 side of the first laminate 100 on which the charge generation layer precursor coating 14 (M) is formed, and the charge generation layer precursor coating 24 (N) The light emitting unit 23 side of the formed 2nd laminated body 200 is made to oppose, respectively. Next, as shown in FIG. 4 (F), the first laminated body 100 and the second laminated body 200 are attached via the charge generation layer precursor coating films 14 (M) and 24 (N), and FIG. As shown in (G), the charge generation layer 15 is formed.

  FIGS. 5A, 5B, and 5H and FIGS. 6I to 6K are process diagrams showing another example of the method for manufacturing an organic EL element according to the present invention. As shown in FIG. 5A, the method for manufacturing an organic EL element according to the present invention includes at least one light emitting unit 13 including an anode 11 and a light emitting layer 12 on one surface side of the first substrate 10. First laminate 100 is prepared. On the other hand, as shown in FIG. 5B, a second stacked body 200 including at least one light emitting unit 23 including a cathode 21 and a light emitting layer 22 is prepared on one surface side of the second substrate 20. Next, as shown in FIG. 5 (H), the charge generation layer precursor coating film 24 (N) is formed on the light emitting unit 23 side surface of the second laminate 200 using an ink containing an amine compound, and the ( A charge generation layer precursor coating film 14 (M) is formed in this order using an ink containing at least one of A ′) and (B). Next, as shown in FIG. 6 (I), the light emitting unit 13 side of the first laminate 100, the charge generation layer precursor coating 24 (N), and the charge generation layer precursor coating 14 (M) are formed in this order. The light emitting unit 23 side of the made second laminated body 200 is opposed to each other. Next, as shown in FIG. 6 (J), the first laminate 100 and the second laminate 200 are attached via the charge generation layer precursor coatings 14 (M) and 24 (N), and FIG. As shown in (K), the charge generation layer 15 is formed.

  FIGS. 7A, 7B, and 7L and FIGS. 8M to 8O are process diagrams showing another example of the method for manufacturing an organic EL element according to the present invention. The organic EL device manufacturing method according to the present invention includes at least one light emitting unit 13 including an anode 11 and a light emitting layer 12 on one surface side of the first substrate 10 as shown in FIG. First laminate 100 is prepared. On the other hand, as shown in FIG. 7B, a second stacked body 200 including at least one light emitting unit 23 including a cathode 21 and a light emitting layer 22 is prepared on one surface side of the second substrate 20. Next, as shown in FIG. 7 (L), an ink containing at least one of (A ′) and (B) and an amine compound is formed on the surface of the first laminate 100 on the light emitting unit 13 side. Used to form the charge generation layer precursor coating 14 (MN). Next, as shown in FIG. 8 (M), the light emitting unit 13 side of the first laminate 100 on which the charge generation layer precursor coating 14 (MN) is formed and the light emitting unit 23 side of the second laminate 200 are arranged. , Face each other. Next, as shown in FIG. 8 (N), the first laminate 100 and the second laminate 200 are attached via the charge generation layer precursor coating 14 (MN), and shown in FIG. 8 (O). Thus, the charge generation layer 15 is formed.

In the step of forming the charge generation layer, a charge generation layer precursor coating film is formed by a coating method using the various inks, and then heated and dried as necessary, and further heated as necessary. Then, a charge generation layer is formed.
In the stack type organic EL element, in the step of attaching the first laminate and the second laminate via the charge generation layer precursor coating and forming the charge generation layer 15, the charge generation layer precursor coating At the time of attaching the first laminate and the second laminate through the film, the solvent or volatile component is still attached in the state of remaining in the coating film and laminated, and then the solvent or volatilization in the coating film is performed. The components can be completely dried to form the charge generation layer.
Alternatively, when a component having a melting point or glass transition temperature of 200 ° C. or less is contained in at least one kind of the ligand (A ′) and (B), the protective agent, or the amine compound, It is preferable to form the charge generation layer by attaching and heating the first laminate and the second laminate through the charge generation layer precursor coating film. In this case, the first laminate and the second laminate may be laminated in a state where almost all the solvent or volatile component in the charge generation layer precursor coating is dried, and the charge generation layer precursor coating is heated. The melting point or glass transition temperature of 200 ° C. or less in the (A ′) and (B) at least one ligand or protective agent in the charge generation layer precursor coating film or amine compound is melted. Thus, the first laminate and the second laminate can be attached, and the charge generation layer can be formed after cooling. The temperature at which the charge generation layer precursor coating film is heated is such that the melting point or glass transition temperature in the at least one ligand or protective agent of (A ′) and (B) or an amine compound is 200 ° C. or less. What is necessary is just to select suitably so that it may become temperature higher than melting | fusing point or glass-transition temperature of the component. The upper limit of the heating temperature is preferably 220 ° C. or less from the viewpoint of decomposition of the organic material.

  In the method for producing an organic EL device of the present invention, at least one of the (A ′) compound represented by the general formula (I) and the (B) transition metal compound nanoparticles contained in the charge generation layer. In order to promote oxidation of the metal contained in one kind and oxidize it, an oxidation step may be further provided. By having the oxidation step, it is possible to appropriately change the charge generation function while maintaining the adhesion with the adjacent layers. In addition, it is possible to improve the film strength by including an oxidation step.

  In the method for manufacturing an organic EL element according to the present invention, the oxidation step includes preparing an ink containing at least one of (A ′) and (B) for forming the charge generation layer, and then generating the charge generation layer. It is preferable to carry out after the step of forming.

Examples of the means for oxidizing include a heating step, a light irradiation step, a step of applying active oxygen, and the like, and these may be used in combination as appropriate. Oxidation is preferably performed in the presence of oxygen in order to efficiently oxidize.
When using the heating step, examples of the heating means include a method of heating on a hot plate and a method of heating in an oven. As heating temperature, 50-250 degreeC is preferable. Depending on the heating temperature, there is a difference in the interaction of the (A ′) and (B) with at least one of the amine compounds and the interaction of at least one of the (A ′) and (B). It is preferable to adjust.

  In the case of using the light irradiation step, examples of the light irradiation means include a method of exposing ultraviolet rays. Depending on the amount of light irradiation, there is a difference in the interaction of the (A ′) and (B) with at least one of the amine compounds and the interaction of at least one of the (A ′) and (B). It is preferable to adjust appropriately.

In the case of using a process for reacting active oxygen, as a means for causing active oxygen to act, a method of generating active oxygen by using ultraviolet rays or a method of generating active oxygen by irradiating ultraviolet rays onto a photocatalyst such as titanium oxide is generated. The method of making it act is mentioned. Depending on the amount of active oxygen, there is a difference in the interaction of at least one of the amine compounds of (A ′) and (B) and the interaction of at least one of (A ′) and (B). It is preferable to adjust appropriately.
Among these means for oxidizing, it is more preferable to have a heating step in the presence of oxygen that does not require light irradiation because it is difficult to damage an already formed organic EL layer.

Each layer included in the light emitting unit may be formed by appropriately using a conventionally known method. For example, it can be formed by a solution coating method, a vapor deposition method or a transfer method. As the solution coating method, the same method as that for the charge generation layer described above can be used. The transfer method is formed, for example, by laminating a layer formed in advance on a film by a solution coating method or a vapor deposition method to a layer to be laminated, and appropriately transferring by heating or the like.
Moreover, a conventionally well-known process can be used suitably about the other process in the manufacturing method of an organic EL element.

3. Organic EL Lighting Device The lighting device according to the present invention will be described. The illumination device according to the present invention includes the organic electroluminescence element according to the present invention.
FIG. 9 is a conceptual cross-sectional view showing an example of a basic layer configuration of the organic EL lighting device according to the present invention. An example of the organic EL lighting device according to the present invention includes an anode 11 on a first substrate 10, a first light emitting unit 13 including a light emitting layer 12, and the following (A) on the first light emitting unit 13. And a charge generation layer 15 in which two layers containing at least one of (B) and an amine compound are arranged in this order, a light emitting unit 23 including a light emitting layer 22, a cathode 21, and a second layer. The substrate 20 is arranged in this order, and is sealed between the first substrate 10 and the second substrate 20 and in close contact with the periphery of the organic EL element using a sealing material 30. Usually, the sealed airtight space is filled with nitrogen gas, and a water capturing agent (not shown) is provided. The light extraction surface may be selected as appropriate for either the first substrate 10 or the second substrate 20.

  As another aspect of the lighting device according to the present invention, for example, the non-light emitting surface side of the organic EL element of the present invention is covered with a case, and the glass substrate on the light emitting surface side is used as a sealing substrate. Sealing is performed between the substrates and around the organic EL element using a sealing material such as a photo-curing adhesive as appropriate, and by appropriately irradiating UV light or the like from the glass substrate side to be cured. And the formed illuminating device is mentioned. The sealing operation is usually performed in a glove box under a nitrogen atmosphere (in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more) without bringing the organic EL element into contact with the air. Moreover, normally, the sealed case is filled with nitrogen gas and a water catching agent is provided.

  The organic EL lighting device according to the present invention may be used as a kind of lamp such as an illumination light source or an exposure light source, using a known configuration as appropriate. Furthermore, the organic EL lighting device according to the present invention is a projection device that projects an image using a known configuration as appropriate, or a light source device of a display device that displays a still image or a moving image directly. May be used as

  In the organic EL lighting device according to the present invention, the provided organic EL element may be used as an organic EL element having a resonator structure. When using an organic EL element having such a resonator structure, it is suitable for applications such as a light source of an optical storage medium, a light source of an electrophotographic copying machine, a light source of an optical communication processor, a light source of an optical sensor, etc. Applied.

  Hereinafter, the present invention will be described more specifically with reference to examples. These descriptions do not limit the present invention. In the examples, parts represent parts by weight unless otherwise specified. Moreover, the thickness of the layer or film | membrane is represented by the average film thickness.

[Synthesis Example 1]
(1) Preparation of the compound represented by the general formula (I) (A ′) Molybdenum hexacarbonyl (manufactured by Kanto Chemical) 0.99 g and dipivaloylmethane (manufactured by Tokyo Chemical Industry, hereinafter referred to as “acac-tBu”) 6.9 g was placed in a three-necked flask and heated to reflux for 5 hours with stirring at 140 ° C. under an argon gas atmosphere to obtain a reddish brown reaction solution. The obtained reaction liquid is put into a glass tube oven, depressurized by a vacuum pump, heated at 80 ° C. for 3 hours, unreacted dipivaloylmethane is removed, and 0.16 g of black solid reaction product 1 is obtained. It was.

<Analysis of Reaction Product 1>
About the black solid reaction product 1 obtained by the synthesis example 1, it measured by TOF-SIMS (TOFSIMS5 by ION-TOF) on the following conditions. The measurement results are shown in FIG.
The secondary ion detected by the measurement has a main peak with a molecular weight of 481. This is because MoO ₂ (acac-tBu) ₂ (in the compound represented by the general formula (I), R ¹ and R ² are t -Butyl group, m = 2, n = 2; molecular weight 497) It was considered to correspond to a mass number (molecular weight 481) in which one oxygen atom deviated.
(TOF-SIMS measurement conditions)
Primary ion species: Bi ^{3 ++}
Primary ion acceleration voltage: 25 kV
Primary ion current value: 0.2 pA
Frequency: 10kHz
Measurement area: 200 μm × 200 μm
Scan: 128pixel × 128pixel × 64scan
Charge correction: Electron irradiation

(2) Preparation of Ink 1 Containing Compound Represented by (A ′) General Formula (I) Black reaction product 1 was dissolved in 1-butanol at a concentration of 2% by mass, A ′) Ink 1 containing the compound represented by formula (I) was obtained. The solid content concentration of the ink was appropriately changed in each example.

[Synthesis Example 2]
(1) Preparation of (B) Transition Metal Compound Nanoparticles A molybdenum carbide-containing nanoparticle ink protected with 12-amino-1-dodecanol was prepared. In a 50 ml three-necked flask, 0.1 g of 12-amino-1-dodecanol (manufactured by Tokyo Chemical Industry Co., Ltd.), 12.8 g of 2-methyl-2,4-pentanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) The solution was weighed, decompressed with stirring, and allowed to stand at room temperature (24 ° C.) for 1.5 hours to remove low-volatile components. The vacuum atmosphere was changed to an atmospheric atmosphere, and 0.8 g of molybdenum hexacarbonyl (manufactured by Kanto Chemical Co., Inc.) was added. The mixture was placed in an argon gas atmosphere and heated to 180 ° C. with stirring, and the temperature was maintained for 2 hours. Thereafter, the mixture was cooled to room temperature (24 ° C.), and the molybdenum carbide nanoparticles protected with black 12-amino-1-dodecanol were dissolved in 2-methyl-2,4-pentanediol. An ink containing dispersed molybdenum carbide oxide-containing nanoparticles was obtained. Using nanoparticles obtained by removing the solvent from the ink, the crystal structure and the valence are measured in the same manner as in paragraphs 0186 to 0189 of International Publication No. 2012/018082, and the molybdenum carbide-containing nanoparticles are obtained. It was confirmed.
(2) Preparation of the ink 2 containing the transition metal compound nanoparticles (B) The ink containing molybdenum carbide-containing nanoparticles dispersed in the 2-methyl-2,4-pentanediol was used with an evaporator. Then, after removing 2-methyl-2,4-pentanediol, the molybdenum carbide-containing nanoparticles protected with 12-amino-1-dodecanol were obtained by drying. By dispersing the nanoparticles thus obtained in water, an ink 2 (solid content concentration 0.4% by mass) containing molybdenum carbide-containing nanoparticles dispersed in water was obtained.

[Example 1]
A light emitting unit including a hole injecting and transporting layer, a light emitting layer, and an electron injecting and transporting layer, a charge generation layer, an electron injecting block layer, and a second electrode (cathode) on a glass substrate on which a transparent anode is formed as a first electrode ) In order of film formation and lamination according to the following procedure, and finally sealing to produce an organic EL element. Except for the preparation of the glass substrate with a transparent anode, the work was performed in a glove box (oxygen concentration 1 ppm or less, moisture concentration 1 ppm or less) under a nitrogen atmosphere unless otherwise specified. The electron injection blocking layer is a layer for blocking electron injection from the second electrode.

  First, an indium tin oxide (ITO) thin film (thickness: 150 nm) was used as a transparent anode. A glass substrate with ITO (manufactured by Sanyo Vacuum Co., Ltd.) was patterned into a strip shape. The patterned ITO substrate was ultrasonically cleaned in the order of neutral detergent and ultrapure water, and then subjected to UV ozone treatment.

  Next, a PEDOT / PSS aqueous dispersion (CLEVIOUS PAI4083 manufactured by Heraeus Co., Ltd.) was applied onto the anode by spin coating on the atmosphere, heated in the atmosphere at 200 ° C. for 30 minutes using a hot plate, An injection transport layer was formed. The thickness after heating was 40 nm.

  Next, F8BT (poly [(9,9-di-n-octylfluorenyl-2,7-diyl) -alt- (benzo [2,1,3] thiadiazole) is formed on the hole injection transport layer. -4,8-diyl) Solid content concentration 1.2 mass% xylene solution) was applied by spin coating, and heated at 150 ° C. for 30 minutes using a hot plate to form a light emitting layer. The thickness after heating was 80 nm.

Next, 3TPYMB (tris [3- (3-pyridyl) mesityl] borane): Liq (8-hydroxyquinolinolato-lithium) = 1: 1 (solid content concentration 3 mass%, 1-butanol solution) was applied by spin coating, and heated at 150 ° C. for 30 minutes using a hot plate. The thickness after heating was 40 nm. The substrate is transported into a vacuum chamber, Liq is reduced by depositing Al with a thickness of 2 nm on the 3TPYMB: Liq layer in a vacuum of 1 × 10 ⁻⁴ Pa, and electron injection transport is performed. A layer was formed.

  Thereafter, the substrate was conveyed again into an inert atmosphere, and the ink 1 containing a compound represented by the general formula (I ′) prepared in Synthesis Example 1 (solid content concentration 0.5% by mass, 1-butanol solution) was applied by spin coating, and heated in the atmosphere at 180 ° C. for 30 minutes using a hot plate. The thickness after heating was 10 nm.

Poly ((9,9-dioctylfluorenyl-2,7-), which is an amine compound, is formed on the layer containing the compound (A) and at least one of its oxides represented by the general formula (I). Diyl) -co- (4,4 ′-(N-4-sec-butylphenyl)) diphenylamine)] (TFB) (solid content concentration 1% by mass, ethyl benzoate: cyclohexanol = 1: 2) (Volume ratio) solvent) was applied by spin coating, and heated at 150 ° C. for 30 minutes using a hot plate. The thickness after heating was 10 nm. Thus, a charge generation layer was formed in which the layer containing at least one of the compound represented by the general formula (I) and the oxide thereof and the layer containing an amine compound were laminated.
The substrate was transferred into a vacuum chamber, and NPD (naphthylphenyldiamine) was deposited as an electron injection block layer on the charge generation layer in a thickness of 50 nm in a vacuum of 1 × 10 ⁻⁴ Pa. Subsequently, gold was deposited in a thickness of 70 nm on the electron injection block layer as a second electrode.
Finally, sealing was carried out using a non-alkali glass and a UV curable epoxy adhesive in the glove box, and the organic EL device of Example 1 was produced.

<XPS Analysis of Layer Containing (A) in Example 1>
The compound represented by the general formula (I) prepared by the synthesis example 1 (A ′) after the formation of the coating film of the ink 1 containing the compound represented by the general formula (I) and heating in the air XPS measurement was performed on the oxide layer. For the measurement, an X-ray photoelectron spectrometer (Theta-Probe, Thermo Fisher Scientific Co., Ltd.) is used. X-ray source: Monochromated Al Kα (monochromatic X-ray) X-ray irradiation area (= measurement area): 400 μmφ , X-ray output: 100 W, lens mode: Standard, photoelectron capture angle: 53 ° (provided the sample normal is 0 °), charge neutralization: electron neutralization gun (+6 V, 0.05 mA), low acceleration Measurement was performed under Ar + ion irradiation conditions. The XPS spectrum is shown in FIG.
As a result, molybdenum containing molybdenum having oxidation numbers of +4 and +6 was contained, the composition of molybdenum atoms was 27%, the composition of oxygen atoms was 67.6%, and the composition of carbon atoms was 5.4%. . That is, the ratio of each atom was 2.5 oxygen atoms and 0.2 carbon atoms when the molybdenum atom was 1.0. The carbon atom was a carbon atom derived from a ligand of the compound represented by the general formula (I), and the oxidized layer was an organic-inorganic composite containing molybdenum, oxygen, and carbon atoms.

[Example 2]
In Example 1, the ink 1 (solid content concentration 0.5 mass%, 1-butanol solution) containing the compound represented by Formula (I) prepared in Synthesis Example 1 was spin-coated. It was applied in the same manner as in Example 1 except that it was heated in a glove box (under a nitrogen atmosphere) at 180 ° C. for 30 minutes using a hot plate.

<TOF-SIMS analysis of the layer containing (A) in Example 2>
About the layer containing said (A) of Example 2, it carried out similarly to the black solid reaction product 1 obtained by the synthesis example 1, and measured TOF-SIMS (TOFSIMS5 by ION-TOF).
The secondary ion detected by the measurement had a molecular weight of 481 as the main peak. This is because MoO ₂ (acac-tBu) ₂ (in the compound represented by the general formula (I), R ¹ and R ² are t-butyl groups, m = 2, n = 2; molecular weight 497) to oxygen atoms. Is considered to correspond to a mass number deviating from one (molecular weight 481).

[Example 3]
In Example 1, the ink 1 (solid content concentration 5 mass%, 1-butanol solution) containing the compound represented by Formula (I) prepared in Synthesis Example 1 was spin-coated. It apply | coated and heated at 180 degreeC for 30 minutes in air | atmosphere using the hotplate. Example 1 was repeated except that the thickness after heating was 30 nm.

[Comparative Example 1]
In Example 1, only a layer containing an amine compound (TFB thin film, thickness: 10 nm) was formed as a charge generation layer, and at least one of the compound represented by the general formula (I) and the oxide thereof was used. An organic EL device of Comparative Example 1 was produced in the same manner as in Example 1 except that the seed-containing layer was not formed.

[Example 4]
In Example 1, instead of using the ink 1 containing the compound represented by the general formula (I ′) prepared in Synthesis Example 1 as the charge generation layer, the (A ′) prepared in Synthesis Example 2 ( B) Using ink 2 containing transition metal compound nanoparticles, charge generation in which (B) layer containing transition metal compound nanoparticles (thickness after heating: 10 nm) and layer containing an amine compound were laminated An organic EL device of Example 4 was produced in the same manner as Example 1 except that the layer was formed.

[Example 5]
In Example 1, the organic EL element of Example 5 was produced in the same manner as in Example 1 except that the charge generation layer was formed as follows.
First, as the charge generation layer forming ink, the compound (A ′) prepared in Synthesis Example 1 represented by the general formula (I): an amine compound poly [(9,9-dioctylfluorenyl- 2,7-diyl) -co- (4,4 ′-(N-4-sec-butylphenyl)) diphenylamine)] (TFB) = 1: 2 (mass ratio) and the solid content concentration is 1 mass%. As described above, the ink containing the compound represented by the general formula (I) and the amine compound dissolved in a mixed solvent of ethyl benzoate: cyclohexanol solution = 1: 2 (mass ratio) 3 was obtained. The ink 3 was applied by spin coating, and heated at 150 ° C. for 30 minutes using a hot plate to form a charge generation layer. The thickness of the charge generation layer after heating was 10 nm.

[Comparative Example 2]
Copper phthalocyanine (CuPc, model number LT-E201, manufactured by Lumtec): Fullerene-C60 (model number LT-S903, manufactured by Lumtec) = 1: 1 (mass ratio) is added to toluene so that the solid content concentration becomes 1% by mass. By dissolving, a comparative ink 1 for forming a charge generation layer was obtained.
Example 1 is the same as Example 1 except that the charge generation layer was applied by spin coating using the charge generation layer forming comparative ink 1 and heated at 150 ° C. for 30 minutes using a hot plate. In the same manner, an organic EL device of Comparative Example 2 was produced.
As a result, since toluene, which is a hydrophobic solvent, was used for the charge generation layer, the lower electron injecting and transporting layer had a remaining film ratio of 0%, and the light emitting layer was also dissolved, and did not function as a charge generation layer.

[Comparative Example 3]
Copper phthalocyanine (CuPc, model number LT-E201, manufactured by Lumtec): Fullerene-C60 (model number LT-S903, manufactured by Lumtec) = 1: 1 (mass ratio), so that the solid content concentration becomes 1% by mass. The ink was dissolved in butanol solvent to obtain a comparative ink 2 for forming a charge generation layer. Copper phthalocyanine and fullerene-C60 did not dissolve in 1-butanol, which is a hydrophilic solvent, but became a dispersion.
Example 1 is the same as Example 1 except that the charge generation layer was applied by spin coating using the charge generation layer forming comparative ink 2 and heated at 150 ° C. for 30 minutes using a hot plate. In the same manner, an organic EL device of Comparative Example 3 was produced.
In Comparative Example 3, a uniform charge generation layer was not obtained.

<Result>
In FIG. 12, the current-application voltage (IV) characteristic curve of the organic EL element of Example 1 and Comparative Example 1 is shown. FIG. 13 shows luminance-applied voltage (LV) characteristic curves of the organic EL elements of Example 1 and Comparative Example 1. The current density, luminance, and voltage in FIGS. 12 and 13 are standardized.
From the graphs of FIGS. 12 and 13, the organic EL device of Example 1 including a layer containing at least one of the compound represented by the general formula (I) and the oxide thereof in the charge generation layer is as described above. (A) Compared with the organic EL element of Comparative Example 1 in which the layer containing at least one of the compound represented by the general formula (I) and its oxide is not included in the charge generation layer, current flows. In addition, it can be confirmed that light is emitted in FIG. 13 at the voltage at which the current rises in FIG. The organic EL elements of Example 1 and Comparative Example 1 have a structure in which NPD is stacked as the electron injection block layer and gold is stacked as the second electrode, and electrons are not injected from the gold electrode of the second electrode. Therefore, the light emission confirmed in the organic EL device of Example 1 of FIG. 13 is the layer containing at least one of the compound represented by the general formula (I) and the oxide thereof and the amine compound ( It is considered that the laminated structure of TFB) functions as a charge generation layer and originates from electrons derived from the charge generation layer.

  Examples 2 to 5 were also evaluated in the same manner as Example 1. As a result, in Examples 2 to 5 as compared with the organic EL device of Comparative Example 1, light emission was confirmed at a voltage at which a current flows and the current rises. A comparison between Examples 1 and 2 reveals that the brightness and current values are better in Example 1 in which the compound (A ′) represented by the general formula (I) is oxidized. It was. The brightness and current value in Example 3 are higher than those in Example 1 because the film thickness of the layer containing at least one of the compound represented by the general formula (A) and the oxide thereof is shown in (A). This is probably because the penetration of the solvent when applying the upper layer (a layer containing an amine compound) could be suppressed more than in Example 1 because it was thicker than Example 1. In Examples 4 and 5, light emission was confirmed at a voltage at which a current flows and the current rises in the same manner as in Example 1. Regarding the light emission, the layered structure of the transition metal nanoparticles of (B) and the amine compound function as a charge generation layer with respect to Example 4, and the Example 1 prepared with Synthesis Example 1 above with respect to Example 5 (A ′) It is considered that the mixed layer of the compound represented by the general formula (I) and the amine compound functions as a charge generation layer and originates from electrons derived from the charge generation layer.

  The organic EL devices prepared in Examples 1 to 5 were F8BT (poly [(9,9-di-n-octylfluorenyl-2,7-diyl) -alt- (benzo [2,1,3] The yellow-green color derived from thiadiazole-4,8-diyl) was measured with a spectroradiometer manufactured by Topcon Co., Ltd. The measurement results are shown in Table 1. In Table 1, the voltage of Example 1 was measured. The current density and the brightness when the value is 0.9 are compared with each other.

* 1 Current density: almost no flow ≒ 0, brightness: almost no light ≒ 0
* 2 Cannot be measured because the electron injecting and transporting layer and the light emitting layer are dissolved. * 3 The charge generation layer is not melted and a uniform charge generation layer cannot be obtained.

[Example 6]
In the same manner as in Example 1, a light emitting unit including a hole injecting and transporting layer, a light emitting layer, and an electron injecting and transporting layer is formed on a glass substrate on which a transparent anode is formed as a first electrode. A first laminate including at least one light emitting unit including an anode and a light emitting layer was prepared on one surface of the substrate. An ink containing the compound represented by the general formula (I) prepared in Synthesis Example 1 on the light emitting unit side surface of the first laminate when the first laminate is conveyed in an inert atmosphere. 1 (solid content concentration 0.5 mass%, 1-butanol solution) was applied by a spin coating method to form a charge generation layer precursor coating film (M). The solvent of the charge generation layer precursor coating film (M) was removed by drying under reduced pressure at 70 ° C. for 5 minutes in the air using a hot plate. The thickness of the charge generation layer precursor coating (M) after heating was 12 nm.

On the other hand, as described below, a second laminate including one cathode and a light emitting unit including a light emitting layer on one side of the second substrate was prepared. The glass substrate cleaned in the same manner as in Example 1 was transferred into a vacuum chamber, and 100 nm thick Al was deposited in a vacuum at a pressure of 1 × 10 ⁻⁴ Pa to form a cathode. Thereafter, the substrate is transferred into an inert atmosphere, lithium salicylate (0.75 mass%, 2-ethoxyethanol solution) is applied by spin coating, and heated at 180 ° C. for 30 minutes using a hot plate. Thus, an electron injection layer was formed. The thickness of the electron injection layer after heating was 10 nm. On the electron injection layer, polyfluorene (PFO) (1.2 mass%, toluene solvent) was applied by spin coating, and dried under reduced pressure at 80 ° C. for 30 minutes using a hot plate to form a blue light emitting layer. Formed. The thickness of the blue light emitting layer after heating was 60 nm.
On the light emitting unit side surface of the second laminate, poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- (4,4 ′-(N-4-sec) which is an amine compound. -Butylphenyl)) diphenylamine)]] (TFB) -containing ink (solid content concentration 1% by mass, ethyl benzoate: cyclohexanol = 1: 2 solvent) was applied by spin coating method, and charge generation layer precursor A coating film (N) was formed. The solvent of the charge generation layer precursor coating film (N) was removed by drying under reduced pressure at 80 ° C. for 30 minutes using a hot plate. The thickness of the charge generation layer precursor coating (N) after heating was 10 nm.

  Next, as shown in FIG. 4E, the light emitting unit 13 side of the first laminate 100 on which the charge generation layer precursor coating 14 (M) is formed, and the charge generation layer precursor coating 24 (N) The light emitting unit 23 side of the formed 2nd laminated body 200 was made to oppose, respectively. Next, heating is performed at 130 ° C. in the atmosphere, and the charge generation layer precursor coating films 14 (M) and 24 (N) are brought into close contact with each other as shown in FIG. While the two-layered structure 200 was attached, as shown in FIG. 4G, the charge generation layer 15 was formed, and a stack type organic EL device including two light emitting units of Example 6 was manufactured. This is because the ligand (dipivaloylmethane) contained in the compound represented by the general formula (I ′) in the charge generation layer precursor coating film 14 (M) becomes liquid at 130 ° C. I use that.

[Example 7]
In Example 6, for the charge generation layer precursor coating film (M), the ink 2 (solid) containing the transition metal compound nanoparticles prepared in Synthesis Example 2 on the light emitting unit side surface of the first laminate (solid) The organic EL device of Example 7 was applied in the same manner as in Example 6 except that the charge generation layer precursor coating film (M) was formed by spin coating using a partial concentration of 0.4% by mass, water solvent). Was made. This utilizes the fact that the protective agent (12-amino-1-dodecanol) contained in the (B) transition metal compound nanoparticles in the charge generation layer precursor coating 14 (M) becomes liquid at 130 ° C. doing.

[Example 8]
In the same manner as in Example 6, a first laminate and a second laminate were prepared.
On the light emitting unit side surface of the second laminate, poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- (4,4 ′-(N-4-sec) which is an amine compound. -Butylphenyl)) diphenylamine)]] (TFB) -containing ink (solid content concentration 1% by mass, ethyl benzoate: cyclohexanol = 1: 2 solvent) was applied by spin coating method, and charge generation layer precursor A coating film (N) was formed. The solvent of the charge generation layer precursor coating film (N) was removed by drying under reduced pressure at 80 ° C. for 30 minutes using a hot plate. The thickness after heating was 10 nm.
Subsequently, the spin coating method using the ink 1 (solid content concentration 0.5 mass%, 1-butanol solution) containing the compound represented by the formula (I) prepared in the synthesis example 1 (A ′). Was applied to form a charge generation layer precursor coating film (M). The solvent of the charge generation layer precursor coating film (M) was removed by drying under reduced pressure at 70 ° C. for 5 minutes in the air using a hot plate.
Next, as shown in FIG. 6 (I), the light emitting unit 13 side of the first laminate 100, the charge generation layer precursor coating 24 (N), and the charge generation layer precursor coating 14 (M) are formed in this order. The light emitting unit 23 side of the second laminated body 200 was made to face each other. Next, as shown in FIG. 6 (J), the first laminate 100 and the second laminate 200 are attached via the charge generation layer precursor coatings 14 (M) and 24 (N), and FIG. As shown in (K), a charge generation layer 15 was formed, and a stack type organic EL device including two light emitting units of Example 8 was produced. This is because the ligand (dipivaloylmethane) contained in the compound represented by the general formula (I ′) in the charge generation layer precursor coating film 14 (M) becomes liquid at 130 ° C. That you are using.

[Example 9]
In the same manner as in Example 6, a first laminate and a second laminate were prepared.
Compound (A ′) prepared in Synthesis Example 1 and represented by general formula (I): poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- ( 4,4 ′-(N-4-sec-butylphenyl)) diphenylamine)]] (TFB) = 1: 2 (mass ratio), ethyl benzoate: cyclohexanol solution so that the solid content concentration is 1 mass%. = 1: 2 (mass ratio) was dissolved in a mixed solvent to obtain an ink containing the compound (A ′) represented by the general formula (I) and an amine compound. The ink was applied onto the first laminate by spin coating, and dried under reduced pressure at 70 ° C. for 30 minutes using a hot plate to form a charge generation layer precursor coating 14 (MN). The thickness of the charge generation layer after heating was 10 nm.
Next, as shown in FIG. 8 (M), the light emitting unit 13 side of the first laminate 100 on which the charge generation layer precursor coating 14 (MN) is formed and the light emitting unit 23 side of the second laminate 200 are arranged. , Respectively. Next, as shown in FIG. 8 (N), the first laminate 100 and the second laminate 200 are attached via the charge generation layer precursor coating 14 (MN), and shown in FIG. 8 (O). As described above, a stack type organic EL device having the charge generation layer 15 and including two light emitting units of Example 9 was produced. This utilizes the fact that the ligand (dipivaloylmethane) contained in the compound represented by the general formula (I) (A ′) becomes liquid at 130 ° C.

<Result>
Regarding Examples 6 to 9, white light emission was confirmed in all cases. This represents that the yellow green color derived from F8BT, which is the light emitting layer of the first laminate, and the blue color derived from polyfluorene, which is the light emitting layer of the second laminate, emit light and are mixed. The yellow-green color derived from F8BT, which is the light emitting layer of the first laminated body, emits light by recombination of holes injected from the transparent anode (ITO) and electrons generated from the charge generating layer, while the light emitted from the second laminated body. The blue color derived from the polyfluorene layer is considered to emit light by recombination of holes generated from the charge generation layer and electrons injected from the cathode. Thus, in the present invention, it has been clarified that a stack type organic EL device can be obtained by efficiently obtaining a charge generation layer by a coating method with an easy manufacturing process.

DESCRIPTION OF SYMBOLS 1 1st electrode 2 Light emitting layer 3 Light emitting unit 4 Charge generation layer 5 Second electrode 6 Substrate 10 First substrate 11 Anode 12 Light emitting layer 13 Light emitting unit 14 (M) Charge generation layer precursor coating film 14 (MN) Charge generation layer precursor Coating film 15 Charge generation layer 20 Second substrate 21 Cathode 22 Light emitting layer 23 Light emitting unit 24 (N) Charge generation layer precursor coating film 30 Sealant 100 First laminate 200 Second laminate

Claims (9)

A first electrode, a second electrode, and at least one light-emitting unit including a light-emitting layer disposed between the first electrode and the second electrode; and when there is one light-emitting unit, the light-emitting unit and the second electrode A charge generation layer disposed between the adjacent light emitting units when the number of the light emitting units is two or more.
The charge generation layer is an organic electroluminescence device, which is a layer containing at least one of the following (A) and (B) and an amine compound.

(A) at least one compound represented by the following general formula (I) and an oxide thereof;
(In General Formula (I), M is at least one of molybdenum, tungsten, and vanadium, and R ¹ and R ² may each independently have a substituent and include a hetero atom. And represents an aliphatic hydrocarbon group, an aromatic ring group, or a combination thereof, where n represents a positive number of 1 to 3, and m represents a positive number of 0 to 2.)

(B) Transition metal-containing nanoparticles comprising at least one transition metal compound selected from the group consisting of transition metal oxides, transition metal carbide oxides, transition metal nitride oxides, and transition metal sulfide oxides, and a protective agent The transition metal is at least one of molybdenum, tungsten, and vanadium, and the transition metal-containing nanoparticles are formed by attaching a protective agent that protects the surface to the particle surface. A linking group capable of linking to a transition metal compound and an organic group having 1 or more carbon atoms. One or more transition metal compound nanoparticles selected from the group consisting of groups;
(In the formula, Z ₁ , Z ₂ and Z ₃ each independently represent a halogen atom or an alkoxy group, and R represents a hydrogen atom or a methyl group.)   The organic electroluminescence according to claim 1, wherein the charge generation layer is a layer in which a layer containing at least one of (A) and (B) and a layer containing the amine compound are laminated. element.   In the transition metal compound nanoparticle of (B), the protective agent includes, in addition to the linking group, a hydroxyl group, a carbonyl group, a carboxyl group, an amino group, a thiol group, a silanol group, a sulfo group, a sulfonate, and an ammonium group. The organic electroluminescent element of Claim 1 or 2 which has 1 or more types of hydrophilic groups selected from the group which consists of.   The organic electroluminescent illuminating device provided with the organic electroluminescent element as described in any one of the said Claims 1-3. A first electrode, a second electrode, and at least one light-emitting unit including a light-emitting layer disposed between the first electrode and the second electrode; and when there is one light-emitting unit, the light-emitting unit and the second electrode A method for producing an organic electroluminescent device having a charge generation layer disposed between electrodes and a charge generation layer disposed between adjacent light emitting units when the number of the light emitting units is two or more,
The charge generation layer is formed by a coating method using one or more inks containing at least one of the following (A ′) and (B) and an amine compound mixed or each of them. The manufacturing method of an organic electroluminescent element which has the process to do.

(A ′) a compound represented by the following general formula (I);
(In General Formula (I), M is at least one of molybdenum, tungsten, and vanadium, and R ¹ and R ² may each independently have a substituent and include a hetero atom. And represents an aliphatic hydrocarbon group, an aromatic ring group, or a combination thereof, where n represents a positive number of 1 to 3, and m represents a positive number of 0 to 2.)

(B) Transition metal-containing nanoparticles comprising at least one transition metal compound selected from the group consisting of transition metal oxides, transition metal carbide oxides, transition metal nitride oxides, and transition metal sulfide oxides, and a protective agent The transition metal is at least one of molybdenum, tungsten, and vanadium, and the transition metal-containing nanoparticles are formed by attaching a protective agent that protects the surface to the particle surface. A linking group capable of linking to a transition metal compound and an organic group having 1 or more carbon atoms. One or more transition metal compound nanoparticles selected from the group consisting of groups;
(In the formula, Z ₁ , Z ₂ and Z ₃ each independently represent a halogen atom or an alkoxy group, and R represents a hydrogen atom or a methyl group.)   Using the ink (α) containing at least one of (A ′) and (B) and the ink containing the amine compound, containing at least one of (A ′) and (B) The manufacturing method of the organic electroluminescent element of Claim 5 which has the process of forming the charge generation layer by which the layer to perform and the layer containing the said amine compound were laminated | stacked.   In the transition metal compound nanoparticle of (B), the protective agent includes, in addition to the linking group, a hydroxyl group, a carbonyl group, a carboxyl group, an amino group, a thiol group, a silanol group, a sulfo group, a sulfonate, and an ammonium group. The manufacturing method of the organic electroluminescent element of Claim 5 or 6 which has 1 or more types of hydrophilic groups selected from the group which consists of.   The manufacturing method of the organic electroluminescent element as described in any one of Claims 5-7 which has an oxidation process which oxidizes the metal contained in at least 1 sort (s) of said (A ') and (B). An ink for forming a charge generation layer of an organic electroluminescence element, comprising at least one of the following (A ′) and (B).

(A ′) a compound represented by the following general formula (I);
(In General Formula (I), M is at least one of molybdenum, tungsten, and vanadium, and R ¹ and R ² may each independently have a substituent and include a hetero atom. And represents an aliphatic hydrocarbon group, an aromatic ring group, or a combination thereof, where n represents a positive number of 1 to 3, and m represents a positive number of 0 to 2.)

(B) Transition metal-containing nanoparticles comprising at least one transition metal compound selected from the group consisting of transition metal oxides, transition metal carbide oxides, transition metal nitride oxides, and transition metal sulfide oxides, and a protective agent The transition metal is at least one of molybdenum, tungsten, and vanadium, and the transition metal-containing nanoparticles are formed by attaching a protective agent that protects the surface to the particle surface. A linking group capable of linking to a transition metal compound and an organic group having 1 or more carbon atoms. One or more transition metal compound nanoparticles selected from the group consisting of groups;
(In the formula, Z ₁ , Z ₂ and Z ₃ each independently represent a halogen atom or an alkoxy group, and R represents a hydrogen atom or a methyl group.)