JP6503699B2 - Organic electroluminescent device, method of manufacturing the same, and organic electroluminescent lighting device - Google Patents

Description

  The present invention relates to an organic electroluminescent device (hereinafter, also referred to as an organic EL device), a method for producing the same, and an organic electroluminescent lighting device (hereinafter, also referred to as an organic EL lighting device).

  The organic EL element is a charge injection type self-luminous organic EL element utilizing light emission generated when electrons and holes reaching the light emitting layer recombine.

The organic EL device 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 in This organic layer had a two-layer structure consisting of the light emitting layer and the hole injection layer in the initial organic EL element, but at present, in order to obtain high luminous efficiency and long drive life, the electron injection layer, electron Various multilayer structures have been proposed, such as a five-layer structure consisting of a transport layer, a light emitting layer, a hole transport layer, and a hole injection layer.
The 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 have an effect of facilitating injection and transport of charges to the light emitting layer, or blocking by electron current and positive current It is said to have the effect of maintaining the balance of the hole current and the effect of suppressing the diffusion of light energy excitons.

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

  As a technology for high efficiency, high brightness, and long life, a stack type (also referred to as multi-photon type) organic EL element in which two or more light emitting units including an organic light emitting layer are stacked is proposed (for example, patent Literature 1). According to the stack-type organic EL element, when a voltage is applied between two electrodes, the light emitting layers emit light at the same time as if they were connected in series, and the light from each light emitting layer is added up. It is possible to emit light with higher luminance than that of the conventional organic electroluminescent device when a constant current is applied, and it is possible to improve the trade-off between the lifetime and the light emission luminance as described above. In the stack type organic EL element, since it is not possible to obtain an organic EL element having high characteristics simply by laminating the light emitting units including the organic light emitting layer, the light emitting units may be positive in a conductive layer or an electric field. A hole and a charge generation layer that generates electrons are provided.

On the other hand, methods of manufacturing an organic EL element are roughly classified into two methods: film formation by vapor deposition under vacuum (dry process) and coating film formation using a solution (solution coating method) An excellent solution coating method is attracting attention in terms of high productivity and the like. Even in the case of using an organic EL element as a lighting device, a large area of the organic EL element is required.
However, the charge generation layer is currently formed by a dry process. For example, in Patent Document 2, as a charge generation layer, 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 are formed by vacuum deposition. doing. For example, in Patent Document 3, a charge generation layer is formed by laminating a mixed layer of a phenanthroline derivative and an alkaline earth metal element and hexanitrile azatriphenylene (HATCN6). Further, in Patent Document 4, a laminate including 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 transport material, and a hole transport material as a p-type doped layer. And molybdenum oxide are both formed by vapor deposition. Further, Patent Document 5 describes that as a charge generation layer, copper phthalocyanine and C60 may be dissolved or dispersed in a solvent, and film formation may be performed by a coating method, but as shown in a comparative example described later In practice, a coating that functions as a charge generation layer can not be formed, and in the example of Patent Document 5, a charge generation layer using C60 is formed by a deposition method. Patent Document 6, performs a co-deposition of MoO ₃ and Li, followed by depositing MoO _3, further MoO ₃ and alpha-NPD (4,4'-bis [N- (naphthyl) -N- phenyl - amino Co-evaporation with biphenyl) to form a charge generation layer.

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

As described above, in the past, although there was an idea of forming a charge generation layer by a solution coating method, it was actually difficult to stably form a film.
In order for the charge generation layer formed by the application method to function as a charge generation layer, first, the charge generation layer itself formed by the application method should have film forming property to be a uniform film and stability of a thin film. is necessary. In addition, in order to form the charge generation layer by the coating method, it is necessary to suppress the dissolution of the electron injecting and transporting layer, the light emitting layer and the like which become the lower layer at the time of forming the charge generation layer. Even in the case of having a metal layer such as an aluminum layer provided for reduction such as an electron injecting and transporting layer, the solvent penetrates to reach the electron injecting and transporting layer or the like in the lower layer for a thin film of about 2 nm. obtain. When the charge generation layer itself is a thin film, when a 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 arises. The film forming property of the charge generation layer when formed by the application method and the stability of the thin film including the adjacent layer are important because they are greatly related to the life characteristics of the device. As described above, there are difficulties in forming the charge generation layer by the solution coating method which can not be overcome simply by the fact that the material is soluble in certain solvents.
On the other hand, if the charge generation layer can only be formed as a thin film by the vapor deposition method, even if the light emitting layer is formed separately by the solution application method such as the ink jet method, eventually the advantage of the solution application method can not be utilized there were. It is also desired that the charge generation layer be produced by a solution coating method which is excellent in terms of large area, high productivity, and the like.

  The present invention has been made in view of the above problems, and an object thereof is to provide an organic EL element capable of achieving long life while being capable of forming a charge generation layer by a solution coating method and having an easy manufacturing process. An object of the present invention is to provide a manufacturing method and an organic EL lighting device using the organic EL element.

As a result of intensive studies to achieve the above object, the present inventors have found that, by using a specific organometallic complex or a specific transition metal-containing nanoparticle, it is possible to use the solution coating method with the adjacent inorganic layer While being able to form a highly stable film excellent in adhesion, it has been found that the film functions well as a charge generation layer, and the present invention has been completed.
That is, the organic electroluminescent device of the present invention is
At least one light emitting unit including a light emitting layer disposed between the first electrode, the second electrode, the first electrode and the second electrode, and the light emitting unit and the second when the light emitting unit is one. And a charge generation layer disposed between the light emitting unit and the electrode, wherein the light emitting unit is disposed between two or more adjacent 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 of a compound represented by the following general formula (I) and an oxide thereof;

(In the 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 may contain a hetero atom And 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 nanoparticle is formed by attaching a protective agent for protecting the surface to the particle surface, and the protective agent is linking groups and the number of carbon atoms resulting action for coupling with the transition metal compound comprises a one or more organic groups, the linking group is a hydroxyl group, a sulfonamido group, and the following general formula (1-a) ~ (1 -o) A transition metal compound nanoparticle which is one or more selected from the group consisting of a functional group represented by:

(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.)

In the method of manufacturing an organic electroluminescent device according to the present invention, at least one light emitting unit including a light emitting layer disposed between a first electrode, a second electrode, and the first electrode and the second electrode, and An organic charge generating layer disposed between the light emitting unit and the second electrode in the case of one light emitting unit, and between the adjacent light emitting units in the case of two or more light emitting units A method of manufacturing an electroluminescent device, comprising
(A ′) at least one of the compound represented by the general formula (I) and at least one of the above (B), and an amine compound, using one or more inks which are mixed or each contained The method further comprises the 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 the charge generation layer and improving the luminous efficiency, the luminance and the life.

  Further, in the method of producing an organic EL device of the present invention, the ink (α) containing at least one of the (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 a function as a charge generation layer It is preferable from the point of improving and improving luminous efficiency, luminance and life.

  In the organic EL device and the method of manufacturing an organic EL device according to the present invention, in the transition metal compound nanoparticle of (B), the protective agent is, in addition to the linking group, a hydroxyl group, a carbonyl group, a carboxyl group, It is preferable to have at least one hydrophilic group selected from the group consisting of an amino group, a thiol group, a silanol group, a sulfo group, a sulfonate and an ammonium group. The charge generation layer can be stably formed into a film by a solution coating method using a hydrophilic solvent on the electron transport layer or light emitting layer which is easily dissolved in a hydrophobic solvent, and on the hydrophilic charge generation layer. Even if the organic layers are formed adjacent to each other by a solution coating method using a hydrophobic solvent, the films can be stably formed.

  Further, in the method of manufacturing an organic EL element of the present invention, having the oxidation step of oxidizing the metal contained in at least one of the (A ′) and (B) improves the luminous efficiency, the brightness and the life. It is preferable from the point of

  In the present invention, there is also provided an organic electroluminescent lighting device (hereinafter also referred to as an organic EL lighting device) comprising the organic electroluminescent device according to the present invention.

  In the present invention, there is also provided an ink for forming a charge generation layer of an organic electroluminescent device, which contains at least one of the above (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 capable of achieving a long life while having an easy manufacturing process, a method of manufacturing the same, and an organic EL using the organic EL element A lighting device can be provided.

It is a cross-sectional conceptual diagram which shows the basic layer structure of the 1st organic EL element which concerns on this 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 drawing which shows an example of the manufacturing method of the organic EL element which concerns on this invention. It is a partial process drawing which shows an example of the manufacturing method of the organic EL element which concerns on this invention. It is a partial process drawing which shows an example of another manufacturing method of the organic EL element based on this invention. It is a partial process drawing which shows an example of another manufacturing method of the organic EL element based on this invention. It is a partial process drawing which shows an example of another manufacturing method of the organic EL element based on this invention. It is a partial process drawing which shows an example of another manufacturing method of the organic EL element based on this invention. It is a cross-sectional conceptual diagram which shows the structure of an example of the organic electroluminescent illuminating device based on this invention. It is a TOF-SIMS measurement result of the reaction product 1 obtained by the 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 current-application voltage characteristic curve of Example 1 and Comparative Example 1 is shown. The luminance-application voltage characteristic curve of Example 1 and Comparative Example 1 is shown.

1. Organic EL Device The organic EL device according to the present invention comprises at least one light emitting unit including a light emitting layer disposed between a first electrode, a second electrode, the first electrode and the second electrode, and the light emitting unit In one case, the charge generation layer is disposed between the light emitting unit and the second electrode, and in the case of two or more light emitting units, disposed between the adjacent 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 of a compound represented by the following general formula (I) and an oxide thereof;

(In the 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 may contain a hetero atom And 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 nanoparticle is formed by attaching a protective agent for protecting the surface to the particle surface, and the protective agent is linking groups and the number of carbon atoms resulting action for coupling with the transition metal compound comprises a one or more organic groups, the linking group is a hydroxyl group, a sulfonamido group, and the following general formula (1-a) ~ (1 -o) A transition metal compound nanoparticle which is one or more selected from the group consisting of a functional group represented by:

(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 compound represented by the specific general formula (I) in the above (A) is an organometallic complex of a specific metal having a specific ligand, unlike the case where a transition metal oxide of an inorganic compound is used, It is soluble in solvents. In addition, since the (B) specific transition metal-containing nanoparticle contains an organic portion as a protective agent for protecting the particle surface in the nanoparticles, it is dispersed in a solvent unlike the case of using a transition metal oxide of an inorganic compound. Have sex.
In the organic EL device of the present invention, the charge generation layer comprises at least one of a compound represented by the specific general formula (I) in the (A) and at least one of the (B) specific transition metal-containing nanoparticles; Since the layer is a layer containing a base compound, each component is stably dissolved and dispersed in a solvent, so that film formation is possible by a solution coating method, and the manufacturing process is easy. In particular, at least one of the compound represented by the specific general formula (I) in the above (A) and the specific transition metal-containing nanoparticle of the above (B) can be selected by appropriately selecting a ligand and a protecting agent. The solvent to be dissolved, such as hydrophilicity or hydrophobicity, can be appropriately changed. Therefore, according to the material such as the electron injecting and transporting layer to be the lower layer and the light emitting layer, the material can be dissolved in a solvent which does not dissolve the lower layer, and the residual film rate of the lower layer can be increased. In addition, at least one of the compound represented by the specific general formula (I) in the above (A) and the specific transition metal-containing nanoparticle of the above (B) can increase the solvent solubility or dispersibility, respectively. Since the solid content concentration of the ink can be increased, a relatively thick film thickness of about 5 to 150 nm, more preferably about 20 to 150 nm, is preferably formed as the total film thickness of the charge generation layer. It is possible. Thus, when a layer is further formed on the charge generation layer by a coating method, the solvent for 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 It is also possible to suppress the problem of trapping the charge generated in the charge generation layer as the residual solvent becomes a residual solvent, and the charge generation function is not impaired.

The transition metal contained in at least one of the compound represented by the specific general formula (I) in the above (A) and the specific transition metal-containing nanoparticle in the above (B) is at least one of molybdenum, tungsten and vanadium. Since they are species, all have high reactivity and easily form a charge transfer complex with an amine compound, they have an excellent charge generation function. If the layer containing at least one of the above (A) and (B) is a sea-island structure or a spot-like 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) can form a relatively thick and uniform layer, a charge transfer complex is easily formed between the layers even when laminated with an amine compound layer. Such charge generation layer is considered to promote the injection and transport of charge and to improve the recombination probability in the light emitting layer, thereby improving the light emission efficiency and the luminance.
In addition, at least one of the compound represented by the specific general formula (I) and the (B) specific transition metal-containing nanoparticle in the (A) contains the above-mentioned specific transition metal; Since the electrical resistance is relatively high, the life is considered to be improved.
Both the compound represented by the specific general formula (I) in the above (A) and at least one of the (B) specific transition metal-containing nanoparticles together with the specific transition metal, a ligand, or a linking group As a protective agent linked by the above, since the organic group is stably contained, the affinity to the amine compound and the affinity to the adjacent inorganic compound or organic compound layer become high, and also the adhesion to the adjacent layer It is an excellent, highly stable film.
Since a charge generation layer having an excellent charge generation function can be formed by a solution coating method as such a highly stable film, the organic EL element of the present invention and the stack type organic EL element have a manufacturing process While being easy, the lifetime of the device can be improved, and the stack type organic EL device of the present invention can improve the power efficiency, the brightness and the device 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 formula (I) in the above (A) and the protective agent for the (B) specific transition metal-containing nanoparticle, By selecting or modifying the type, it is easy to achieve multifunctionality such as imparting not only hydrophilicity and hydrophobicity but also functionality such as charge transportability or adhesion.

Further, in the organic EL device of the present invention, since the charge generation layer which could not be stably formed by the solution application method can be stably formed by the solution application method, the light emitting layer unit and the charge generation layer And, it is possible to form by only the application process in sequence. Therefore, as compared with the process including the vapor deposition process, there is an advantage that the organic EL element can be manufactured at a low cost.
The solution coating method of applying a solvent to a substrate does not require a large deposition apparatus as compared with the dry process including a deposition process, can simplify the manufacturing process, has high material utilization efficiency, and costs It is inexpensive and has the merit of being able to increase the area of the substrate

  The formation of the charge transfer complex is, for example, 6 to 10 ppm of the amine compound when at least one of the (A) and (B) is mixed with the solution of the amine compound by 1 H NMR measurement. It is suggested by the phenomenon that the shape and chemical shift value of the proton signal derived from the aromatic ring observed in the vicinity change compared with before mixing at least one of the above (A) and (B) Be done.

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

FIG. 2 is a cross-sectional conceptual view showing another basic layer configuration 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 disposed 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 (a light emitting unit 3-1 including a light emitting layer 2-1, a light emitting unit 3-2 including a light emitting layer 2-2, a light emitting unit 3-3 including a light emitting layer 2-3) A light emitting unit 3-n) including a light emitting layer 2-n, two or more light emitting units, and a charge generation layer 4-1 disposed between the adjacent light emitting unit 3-1 and the light emitting unit 3-2, adjacent Charge generation layer 4-2 disposed between light emitting unit 3-2 and light emitting unit 3-3,..., Charge generating layer 4- (n-1). In this example, n light emitting units are stacked, and the charge generation layer is disposed between each adjacent light emitting unit and n-1 is stacked.
In the present invention, the number n of light emitting units is preferably 1 to 6, more preferably 1 to 4, and still more preferably 1 to 3.
The substrate 6 is a support for forming the layers constituting the organic EL element, and is not necessarily provided on the surface of the electrode 1 and may be provided on 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 to the light emitting layer 2 and electrons are injected from the cathode to the light emitting layer to form the inside of the light emitting layer 2 And the function of recombining the injected holes and electrons and emitting light to the outside of the device. The charge generation layer in FIG. 2 generates charges (holes and electrons) when a voltage is applied to the anode and the cathode, and injects the electrons to 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 device, all layers present on at least one surface of the light emitting layer need to be transparent to light of at least a part of the visible wavelength range.

In addition, 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 a single layer or a multilayer. In the organic EL device 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 includes, in addition to the light emitting layer, a hole injecting layer, a hole transporting layer, an electron injecting layer, an electron transporting layer, and further well-known functional layers used for EL elements. You may include it.
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, or It may be at or near the interface between the charge generation layer and the other layer.
The charge generation layer in the organic EL device of the present invention comprises at least one of a compound represented by the above-mentioned (A) specific general formula (I) and an oxide thereof, and a (B) a specific transition metal-containing nanoparticle And at least one of the above, and an amine compound.
The charge generation layer in the organic EL device of the present invention may be composed only 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 the (A) and the (B) and the amine compound, or It may be a layer in which a layer containing at least one of (A) and (B) and a layer containing the amine compound are laminated. Among them, the layer as a layer including at least one of the above (A) and (B) and the layer including the above amine compound is laminated to improve the function as the charge generation layer, and the luminous efficiency From the viewpoint of improving the brightness and life.
The reason why such a function is improved in the laminated layer is presumed to be that the film density of the specific transition metal contained in at least one of the (A) and the (B) becomes higher.
On the other hand, when using a charge generation layer comprising one mixed layer containing at least one of the (A) and the (B) and the amine compound as the charge generation layer, the process is saved and the productivity is improved. improves.
The charge generation layer may be formed of two or more layers if the layer containing at least one of (A) and (B) and the layer containing an amine compound are laminated at least adjacent to each other. You may For example, a layer containing at least one of (A) and (B), and a mixed layer containing at least one of (A) and (B) and an amine compound are laminated. Layers include but are not limited to these.

<(A) at least one of a compound represented by the following general formula (I) and an oxide thereof>
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 compounds represented by the following general formula (I) used in the present invention may be used alone or in combination of two or more.

(In the 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 may contain a hetero atom And 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 is a point at which the reactivity of the compound represented by the general formula (I) is increased and the charge generation function is improved. It is preferable from

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

As R ¹ and R ² , an alkyl group such as methyl group, a cycloalkyl group such as cyclopentyl group, an alkenyl group such as vinyl group, an alkynyl group such as ethynyl group, an aryl group such as phenyl group, an aromatic group such as pyridyl group The heterocyclic group, aliphatic heterocyclic group such as pyrrolidinyl group, arylalkyl group such as benzyl group, alkyl aryl group such as 1,3,5-trimethylphenyl group, etc. may be mentioned, but it is not limited thereto. .
The number of carbon atoms of each of R ¹ and R ² may be appropriately selected from the viewpoint of solubility in various solvents, but the number of carbon atoms is preferably 1 to 20 from the viewpoint of charge generation function.

In addition, as an aliphatic hydrocarbon group having a substituent in R ¹ and R ² , an aromatic ring group, or a combination thereof, for example, a halogenated hydrocarbon group such as a fluorinated hydrocarbon group such as a heptafluoropropyl group, Alkoxyalkyl groups such as methoxymethyl group, alkoxyaryl groups such as methoxyphenyl group, aryloxyalkyl groups such as phenoxymethyl group, alkylthioalkyl groups such as methylthiomethyl group, alkylthio aryl groups such as methylthiophenyl group, phenylthiomethyl group And arylthio alkyl groups, acyl alkyl groups such as acetylmethyl group, acyl aryl groups such as acetyl phenyl group, acyloxy alkyl groups such as acetoxypropyl group, and acyloxy aryl groups such as acetoxyphenyl group. But it is not limited thereto.

In the present invention, it is preferable that the total of the carbon numbers of R ¹ and R ² is 5 or more from the viewpoint of improving the charge generation function. When the total carbon number of R ¹ and R ² is 5 or more, the solvent solubility is improved, a film can be stably formed by a solution coating method, and the compounds are difficult to be aggregated in the coating film. It is presumed that the dispersion and dispersion stability of the In addition, when the total carbon number of R ¹ and R ² is 5 or more, the affinity with the amine compound is also improved, the charge transfer complex is formed efficiently, and the charge generation ability is improved. Presumed.
Further, it is preferable that at least one of R ¹ and R ² has 4 or more carbon atoms from the viewpoint of improving the life of the organic EL element, and the formation of the charge generation layer by the solution coating method becomes easy. preferable. The number of carbon atoms here also includes the number of carbon atoms of the substituent.

Among them, at least one of R ¹ and R ² contains an aliphatic hydrocarbon group and preferably has 4 or more carbon atoms, and specifically, at least one of R ¹ and R ² is carbon And a linear, branched or cyclic, saturated or unsaturated aliphatic hydrocarbon group, an alkoxyalkyl group, an alkoxyaryl group, an aryloxyalkyl group, an alkylthioalkyl group, an alkylthioaryl group, an arylthioalkyl It is preferable that it is 1 or more types selected from the group which consists of a group, an acyl alkyl group, an acyl aryl group, an acyloxy alkyl group, and an acyl oxy aryl group. When at least one of R ¹ and R ² has these carbon atoms of 4 or more and contains an aliphatic hydrocarbon group, improvement in solvent solubility and compatibility with an amine compound are improved. The formation of the charge generation layer by the solution coating method is facilitated, and the charge generation function is improved, and the lifetime of the organic EL element is improved.

In addition, since the ligand of the compound represented by the said General formula (I) has two ketone groups, there exists a merit that it can also melt | dissolve also 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 as to have solubility in a solvent that does not dissolve the lower layer when forming the charge generation layer by a coating method. For example, an alcohol such as 1-butanol etc. In order to have solubility in the hydrophilic solvent to be mixed, it is preferable that each carbon number of R ¹ and R ² be appropriately selected from 1 to 12, and further appropriately selected from 1 to 8. Is preferred.

The compounds represented by the above general formula (I) used in the present invention preferably include 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 a compound in which m is 1 and a compound in which m is 2 is preferably 50% by mass or more, and further 70% % Or more is preferable from the viewpoint of improving the charge generation function. It is preferable that m is 1-2 in the compound represented by the said general formula (I) used by this invention.
In addition, n is preferably a positive number of 2 to 3, among others. It is preferred that the compound represented by the general formula (I) contains a compound in which n is 2.
Among them, in the compound represented by the general formula (I), one or more 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 The content is preferably 70% by mass or more from the viewpoint of improving the charge generation function.

The compounds represented by the above general formula (I) can be prepared as follows if they are not commercially available.
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 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 described above includes In addition to the compound represented by the formula (I), it is presumed that dimers and multimers of the compound represented by the general formula (I) are included. However, as long as these dimers and multimers are also dissolved in the solvent, these dimers and multimers are also included because they are presumed to function in the same manner as the compound represented by the general formula (I). You may use it 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 a coordination compound containing at least one of molybdenum, tungsten and vanadium. In addition to the metal of the species, it contains a ligand. However, examples of the molybdenum complex and the tungsten metal complex used as a raw material include complexes having an oxidation number of -2 to +6. Moreover, as a vanadium complex, there exist an oxidation number from -3 to +5.
The type of ligand is appropriately selected and is not particularly limited, but from the viewpoint of compatibility with the compound represented by the general formula (II), it is preferable to contain a carbon atom, and further a carbon atom and an oxygen atom It is preferable to include. The ligand is preferably one that decomposes from the complex at a relatively low temperature such as 200 ° C. or less.

Examples of monodentate ligands include acyl, carbonyl, thiocyanate, isocyanate, cyanate, isocyanate, halogen atom and the like. Among them, carbonyl which is easily decomposed at relatively low temperature is preferable.
Moreover, as a ligand, a monodentate ligand or a bidentate ligand is preferable from the point which 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 the raw material, for example, a molybdenum complex or a tungsten complex which is a raw material of the reaction product described in paragraphs 0048 to 0059 of JP-A-2010-272891 can be appropriately selected and used. Further, as the vanadium complex having an oxidation number of 0 or less, for example, metal carbonyl [V- ^III (CO) ₅ ] ^-3 , [V- ^I (CO) ₆ ] ^- , [V (CO) ₆ ] and the like can be mentioned. . Examples of the vanadium complex having an oxidation number of 2 include [V ^II (H ₂ O) ₆ ] ²⁺ , cyclopentadienyl complex [V (η ⁵ -C ₅ H ₅ ) ₂ ] and the like. 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.

As a compound represented by said general formula (II), arbitrary combinations of said R < ¹ >, R < ² > are mentioned.
The compounds represented by the above general formula (II) are commercially available and, for example, can be obtained synthetically by 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 the specific metal complex at 1% by mass or more at 25 ° C., more preferably 5% by mass or more, and 10% by mass or more Is even more preferred. In this case, in the step of obtaining the compound represented by the general formula (I), the reaction can be performed by adding unnecessary or small amounts of other solvents, the reaction efficiency becomes high, and the lifetime of the device is improved.
The compound represented by the general formula (II) is preferably a liquid at 25 ° C., but is not limited to a liquid at 25 ° C.
The compound represented by the general formula (II) preferably has a melting point of 150 ° C. or less, more preferably 80 ° C. or less, from the viewpoint of facilitating the 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, the organic solvent may not be added as long as the compound represented by the general formula (II) is liquid at the reaction temperature and sufficient for solvent-free reaction. When using the complex which is easy to sublimate as said specific metal complex, it is preferable to react by adding and refluxing an organic solvent from the point which a yield improves. When the compound represented by the general formula (II) is a powder and can not be mixed with the specific metal complex, or when the compound represented by the general formula (II) is liquid An organic solvent may be added as needed to raise the level.
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) Preferably, 10 to 3000 parts by mass is further added.

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.
Among them, when the compound-containing solution represented by the general formula (I) after preparation is used as an ink for charge generation layer formation as it is, the general formula (II) corresponds to 1 mol of the specific metal complex It is preferable that the content of the compound to be represented is 3 mol to 6 mol from the viewpoint of improving the reaction yield and the lifetime of the device.

  As an organic solvent other than the compound represented by the above general formula (II) used when preparing the compound represented by the above general formula (I), since it is a solvent which hardly exerts an adverse effect on the device performance It is preferable to use a group hydrocarbon-based solvent, and examples thereof include toluene, xylene, anisole, mesitylene and the like.

The heating temperature is not particularly limited, but is usually about 100 ° C. to 200 ° C., and preferably 120 ° C. to 160 ° C. from the viewpoint of suppressing the side reaction. Since the differences in the reactivity of the specific metal complex used as the raw material and the interaction between the specific metal complexes occur depending on the heating temperature, it is preferable to adjust as appropriate. Moreover, the pressure at the time of heating is not particularly limited, but normal pressure to 0.1 MPa is desirable, and normal pressure is more desirable. The heating time may vary depending on the amount of synthesis, the reaction temperature and the like, so it can not be generally defined, but is usually set in the range of 0.1 hour to 24 hours, preferably 1 hour to 10 hours.
Moreover, it is preferable that the said heating is performed under inert gas atmosphere from the point which suppresses a side reaction. The inert gas atmosphere can be adjusted by, for example, evacuating to about 10 ⁻¹ Pa and then introducing an inert gas such as argon or nitrogen. The heating means may be appropriately selected according to the reaction scale, and is not particularly limited.

On the other hand, it is also a preferable embodiment that the charge generation layer contains the oxide of the compound represented by the general formula (I) from the viewpoint of improving the charge generation function. The oxide of the compound represented by the above general formula (I) can be obtained by means of oxidation as described later. Above all, it is preferable to obtain an oxide of the compound represented by the general formula (I) by heating in the presence of oxygen after forming a layer using 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, it is possible that the charge generation function includes that the molybdenum having an oxidation number of +4, the molybdenum having an oxidation number of +6, and a transition metal having a different oxidation number. It is preferable from the point of view.

<(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 carbon oxides, transition metal nitride oxides, and transition metal sulfide oxides. A transition metal-containing nanoparticle comprising: and a protective agent, wherein the transition metal is at least one of molybdenum, tungsten, and vanadium, wherein the transition metal-containing nanoparticle protects the surface of the particle on the surface. Is attached, and the protective agent includes a linking group which produces an effect of linking with the transition metal compound and an organic group having one or more carbon atoms, the linking group is a hydroxyl group, a sulfonamide group, and It is a transition metal compound nanoparticle which is one or more types selected from the group which consists of a functional group shown by ( 1-a )-( 1-o ).
Here, the nanoparticles mean particles having a diameter of nm (nanometer) order, 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 the particles formed simply by pulverizing the transition metal compound, and a protective agent having an organic group having one or more carbon atoms is linked by a linking group on the nanoparticle surface ing. Since the organic group contained in the protective agent is disposed to cover the surface of the specific transition metal compound, the affinity with the organic solvent is high, the organic solvent has dispersibility, and the dispersion is stable. It will be highly sexual.
Furthermore, 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 addition to the linking group. In the case of having a hydrophilic group, when the protecting agent is linked to the specific transition metal compound by the linking group, the hydrophilic group contained in the protecting agent is disposed on the organic group covering the surface of the specific transition metal compound As a result, the surface of the nanoparticles becomes hydrophilic, and they have dispersibility in a hydrophilic solvent, and the dispersion stability is high.
Thus, since the nanoparticles used in the present invention containing the protective agent have very high dispersion stability in the solvent, it is possible to form a thin film of nm order with high stability over time and 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 among others. This is because the light emitting layer, the electron injecting and transporting layer, etc., which become the lower layer 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 and the like. 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, so that it is possible to use a hydrophobic solvent The charge generation layer can be stably formed on the electron transport layer or the light emitting layer which is easily dissolved by the solution coating method using a hydrophilic solvent. In addition, the formed charge generation layer is 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 rate. As a hydrophilic solvent, it can be used without particular limitation, as a standard that the solubility (20 ° C.) in water or water is 5 g / L or more. The hydrophilic solvent is preferably a solvent that can be mixed with water in any proportion.
On the other hand, as a hydrophobic solvent, it can be a standard that the solubility (20 ° C.) in water is less than 5 g / L.

In the present invention, since the transition metal of the transition metal compound is at least one metal selected from the group consisting of molybdenum, tungsten, and vanadium, it is highly reactive to amine compounds, and amine compounds The charge transfer complex is easily formed, and the charge generation function is high.
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 carbon oxides, transition metal nitride oxides, and transition metal sulfide oxides. Other than these, borides, selenides, halides, complexes and the like may be contained.

When the nanoparticles contain 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, the value of ionization potential is optimized. By suppressing the change due to the oxidation from the unstable oxidation number +0 metal in advance, it is possible to reduce the driving voltage in the device and improve the device life.
Among them, it is preferable that the transition metal compound which is an oxide having a different oxidation number be contained in the nanoparticles. By coexistence and inclusion of transition metal compounds having different oxidation numbers, the charge transportability and the charge injection property are appropriately controlled by the balance of the oxidation numbers, so that it is possible to reduce the drive voltage and improve the device life. become. In the nanoparticles, transition metal atoms and compounds of various valences such as oxides and borides may be mixed according to the processing conditions.

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

The protective agent attached to the surface of the nanoparticle to protect the surface of the nanoparticle has an organic group having one or more carbon atoms in addition to the linking group linked to the nanoparticle.
The protective agent may be a low molecular weight compound or a high molecular weight compound, but is preferably a low molecular weight 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 linking groups may be one or more in the molecule. However, when it is desired to obtain more uniform nanoparticles, it is preferable that the linking group and the hydrophilic group described later adopt different substituents, and that 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, preferably 2 or more carbon atoms, more preferably 2 to 30, still more preferably 2 to 25, particularly preferably 4 to 25 linear, branched or cyclic, saturated or unsaturated aliphatic hydrocarbon group, having 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 are included. In addition, carbon number of an aliphatic hydrocarbon group, an aromatic hydrocarbon group, and the substituent of a heterocyclic group is not included here as carbon number.

Among them, as the organic group, the protective agent protects the surface through the linking group that the organic bond does not have a bulky structure such as a cyclic structure at the part directly bonded to the linking group, that is, an aliphatic hydrocarbon group. When it is densely protected without defects, it is preferable that the linear structure has one or more carbon atoms, and the distance between transition metal compounds in the core of the nanoparticle can be sufficiently maintained. It is preferable from the point which can prevent aggregation of each other.
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 transportability, improves adhesion with an adjacent amine compound, and the like. And the dispersion stability of the film can be improved.

Specific examples of the aromatic hydrocarbon and / or heterocycle include, for example, benzene, triphenylamine, fluorene, biphenyl, pyrene, anthracene, carbazole, phenylpyridine, trithiophene, phenyloxadiazole, phenyltriazole, benzimidazole , Phenyl triazine, benzodiathiazine, phenyl quinoxaline, phenylene vinylene, phenyl silole, combinations of these structures, and the like.
In addition, as long as the effects of the present invention are not impaired, the structure containing an aromatic hydrocarbon and / or a heterocyclic ring may have a substituent. As a substituent, a C1-C20 linear or branched alkyl group, a halogen atom, a C1-C20 alkoxy group, a cyano group, a nitro group etc. are mentioned, for example.

  In the case where the protective agent contains both a hydrophilic group and a linking group, the linking group and the hydrophilic group may be the same kind of substituent, but at least at least a substitution that serves as a linking group in one molecule. One group and one substituent that performs the function of a hydrophilic group are included. However, when the linking group and the hydrophilic group are the same, the protecting agent has a plurality of linking groups, and there is a concern that the nanoparticles may be bound and aggregated via the linking group, so that the stable dispersibility can be obtained. From the viewpoint of maintaining, in the protective agent, it is preferable that the linking group and the hydrophilic group be different. In particular, it is more preferable that the protective agent contains one or more hydrophilic groups that are difficult to bind to nanoparticles and one linking group that is easy to bind to nanoparticles.

  When the protective agent contains both a hydrophilic group and a linking group, among them, 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. At least one member selected from the group consisting of hydroxyl group, carboxyl group, thiol group, sulfo group and sulfonate from the viewpoint of relatively weak ability to link with transition metal compounds. Is preferred.

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 and a hydrophilic 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, etc. Used for

Specific examples of the protective agent which is a low molecular weight compound containing both a hydrophilic group and a linking group include, but are not limited to, 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 '-Tetrakis (4-aminophenyl) benzidine etc. are mentioned.
When the protective agent is a low molecular weight compound having a molecular weight of 1000 or less, the thickness of the protective agent covering the nanoparticle surface is small, so the transition metal-containing compound surface approaches and interacts with the adjacent layer compound. It is preferable because it can be expected that the transition metal-containing compound can easily contribute to the improvement of the charge injection property. The lower limit of the molecular weight of the protective agent is not particularly limited, but may be 50 or more as a standard.

  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 in one molecule is appropriately selected It can be used. As the polymer compound, a polymer having a repeating unit is suitably used, and the weight average molecular weight is, for example, more than 1000 and about 50000 or less. The weight average molecular weight in the present invention refers to a 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, polyvinyl pyrrolidone, polyglycolide, poly (2-acrylamido-2-methyl-1-propanesulfonic acid), poly ( Acrylamide-acrylic acid) copolymer etc. are mentioned.

  The protective agent preferably has a solubility (20 ° C.) in the solvent to be used of 10 g / L or more, more preferably 50 g / L or more, in order to make the nanoparticles dispersible in the solvent.

  In the specific transition metal compound nanoparticles of the present invention, the content ratio of the transition metal compound to the protective agent is appropriately selected depending on the application, and is not particularly limited, but 10 parts of the protective agent is based on 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. When a thin film of 20 nm or less is formed, the thickness is more preferably 15 nm or less, and particularly preferably in the range of 1 nm to 10 nm. If the particle size is too small, production is difficult. On the other hand, if the particle size is too large, the surface area (specific surface area) per unit mass may be small, the desired effect may not be obtained, and the surface roughness of the thin film may be further increased to cause frequent shorts. It is from.
Here, the average particle size is a number average particle size measured by a dynamic light scattering method, but in the state of being dispersed in the charge generation layer, the average particle size is measured using a transmission electron microscope (TEM) From the obtained image, select a region where it is confirmed that 20 or more nanoparticles are present, measure the particle size of all nanoparticles in this region, and obtain the value obtained by calculating the average value I assume.

  The method for producing the specific transition metal compound nanoparticles used in the present invention is not particularly limited as long as it can obtain the above-mentioned transition metal compound nanoparticles. For example, a liquid phase method in which a transition metal complex and the above protective agent are reacted in an organic solvent can be mentioned. For example, it can prepare suitably with reference to Unexamined-Japanese-Patent No. 2011-119681, re-table 2012/018082, and Unexamined-Japanese-Patent No. 2012-069963.

<Amine compounds>
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) specific general formula (I) and the (B) specific transition metal-containing nanoparticle. It is presumed that the charge transfer complex is formed to realize the function as a charge generation layer.

As the said amine compound, a high molecular compound other than a low molecular weight compound is used suitably. In the charge generation layer of the present invention, for the purpose of forming a stable film by a solution coating method, as an amine compound, it is possible to form a stable coating film which is easily dissolved in an organic solvent and in which the compound is hardly aggregated Preferably, molecular compounds are used. 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.

As an amine compound used by this invention, it is preferable that it is an aromatic amine compound, and it is preferable to use various aromatic amine derivatives. Among the aromatic amine compounds, triarylamine derivatives containing a triphenylamine structure as a partial structure are particularly preferable.
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- Non-limiting examples include anthracene derivative, carbazole derivative, thiophene derivative, fluorene derivative, distyrylbenzene derivative, spiro compound, including, but not limited to, naphthyl) -N-phenylamino) triphenylamine (2-TNATA) and the like. And the like may further be included in the molecule.
Moreover, as an amine type polymer compound, the polymer which contains an aromatic amine derivative in a repeating unit can be mentioned, for example. The polymer may be a copolymer further containing an electron donor compound such as an anthracene derivative, a carbazole derivative, a thiophene derivative, a fluorene derivative, a distyryl benzene derivative, and a spiro compound as a repeating unit.

  Among the amine-based polymer compounds, the compound represented by the following general formula (1) is likely to have good adhesion stability with the adjacent organic layer, and the HOMO energy value of the anode substrate and the light emitting layer material It is also preferred in that it is between

(In Formula (1), Ar _{1 to} Ar ₄ may be the same as or different from each other, and are unsubstituted or substituted aromatic carbon atoms having 6 to 60 carbon atoms relating to a conjugated bond) A hydrogen group or an unsubstituted or substituted heterocyclic group having 4 to 60 carbon atoms relating to a conjugated bond, n is 1 to 10000, m is 0 to 10000, and n + m is 10 to 20000; Also, the arrangement of two repeating units is optional.)

In addition, the arrangement of the two repeating units is optional, and may be, for example, any of a random copolymer, an alternating copolymer, a periodic copolymer, and a block copolymer.
The average of n is preferably 5 to 5,000, and more preferably 10 to 3,000. The average of m is preferably 5 to 5,000, and more preferably 10 to 3,000. The average of n + m is preferably 10 to 10,000, and more preferably 20 to 6,000.

Specific examples of the aromatic hydrocarbon in the aromatic hydrocarbon group in Ar _{1 to} Ar ₄ in the general formula (1) include benzene, fluorene, naphthalene, anthracene, combinations thereof, and derivatives thereof. Further, phenylene vinylene derivatives, styryl derivatives and the like can be mentioned. Specific examples of the heterocyclic ring in the heterocyclic group include thiophene, pyridine, pyrrole, carbazole, and combinations thereof, and derivatives thereof.
When Ar _{1 to} Ar _{4 in} the general formula (1) have a substituent, the substituent is preferably a linear or branched alkyl group having 1 to 12 carbon atoms or an alkenyl group.

  Specific examples of the compound represented by the above general formula (1) include 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 mentioned as a suitable compound.

  In the case where the charge generation layer of the present invention comprises one mixed layer containing at least one of the (A) and the (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, further 15 to 60 parts by weight with respect to 100 parts by weight of the amine compound, It is preferable from the viewpoint of enhancing the charge generation function and achieving high stability of the film and long life. The mixed layer may contain other components as described later, but the total amount of at least one of (A) and (B) and an amine compound in the mixed layer. However, it is preferable that it is 90 mass% or more with respect to the total solid of a mixed layer, It is further more preferable that it is 95 mass% or more, It is 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 the layer containing at least one of the above (A) and (B) and the layer containing an amine compound are laminated, the density of the material is The content of at least one of (A) and (B) in the charge generation layer may be selected appropriately with respect to 100 parts by weight of the amine compound in the charge generation layer. 1 to 500 parts by weight, and further preferably 5 to 300 parts by weight is preferable from the viewpoint of enhancing the charge generation function and achieving high stability of the film and long life.
In the case where the charge generation layer of the present invention 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, the above (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, and further, The content 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 an amine compound may be used alone or in combination of two or more. It may be used.

When a component having a melting point or a glass transition temperature of 200 ° C. or less is contained in at least one of the ligands (A) and (B), a protecting agent, or an amine compound, the organic matter described later In the method of manufacturing an EL device, even after the charge generation layer precursor coating film is dried to remove the solvent, the charge generation layer precursor coating film is heated to at least one of (A) and (B). The ligand, protective agent, or amine compound melts to cause adhesion of the charge generation layer precursor coating, and when the charge generation layer precursor coating adheres to the adjacent layer upon cooling, the charge generation layer is formed. It is preferable from the point which can form.
Among the components (A) and (B) of at least one of the ligand and protecting agent, and the component having a melting point or glass transition temperature of 200 ° C. or less contained in the amine compound, among them, a resin substrate and an organic layer The melting point or the glass transition temperature is preferably 160 ° C. or less in order to prevent the glass transition temperature of the above from largely exceeding the glass transition temperature. On the other hand, at least one of the ligands (A) and (B), a protecting agent, or a component having a melting point or a glass transition temperature of 200 ° C. or less contained in the amine compound is generated when the organic EL panel is driven. The melting point or glass transition temperature is preferably 18 ° C. or more, more preferably 40 ° C. or more, from the viewpoint of preventing remelting by heat. In addition, the glass transition temperature here is measured by DSC (Differential Scanning Calorimetry, differential scanning calorimetry).
The component having a melting point or a glass transition temperature of 200 ° C. or less contained in at least one of the ligands (A) and (B) or a protecting agent, or an amine compound, has a charge generating 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, and preferably 80% by mass or less, and further 70% by mass or less from the viewpoint of the 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, known electron donor compounds different from amine compounds such as carbazole and thiophene may be appropriately selected and 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, polyester and the like. Moreover, you may contain the binder resin hardened | cured by a heat | fever, light, etc. As a material to be cured by heat or light, a charge transport compound having a curable functional group introduced in the molecule, or a curable resin 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, isocyanate group and the like. 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 silicone resin, and a silane coupling agent. be able to.

The thickness of the charge generation layer can be appropriately determined depending on the purpose and the adjacent layer, but the charge generation layer contains at least one of the (A) and the (B), and an amine compound. Even if it is a mixed layer, even if it 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, the total film thickness is It is usually 0.1 to 200 nm, preferably 1 to 150 nm. Among other things, when forming a layer on the charge generation layer by the application method, the problem of the dissolution of the lower layer of the charge generation layer through the charge generation layer through the charge generation layer is suppressed. In the case of thick film formation, it is more preferable that the thickness be 20 nm to 150 nm.
In the case where the charge generation layer of the present invention 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, the above (A) and The ratio of the film thickness of the layer containing at least one of (B) to 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 the (A) and (B) and a layer containing an amine compound are laminated, at least the (A) and (B) It is preferable from the viewpoint of 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, the amine compound has a higher vacuum level than at least one of (A) and (B), that is, it has a higher LUMO and can function as an electron block layer or a hole transport layer. When the layer containing at least one of (B) and (B) is disposed on the anode side, it becomes easier to move electrons generated from the charge generation layer to the light emitting layer on the anode side, and contains an amine compound. It is because it becomes easier to move the holes generated from the charge generation layer to the light emitting layer on the cathode side by arranging the layer 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 layer is formed of an organic compound layer. When the light emitting unit is composed of multiple layers, the light emitting unit includes, in addition to the light emitting layer, a hole injecting layer, a hole transporting layer, an electron injecting layer, an electron transporting layer, and further well-known functional layers used for EL elements. You may include it.
Although an example is given about each layer, it is not limited to these and a publicly known composition can be adopted suitably.

<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 element, and any of a fluorescent material and a phosphorescent material can be used. Specifically, materials such as dye-based light emitting materials and metal complex-based light emitting materials can be mentioned. In addition, as the light emitting material, any of low molecular weight compounds and high molecular weight compounds can be used. For example, it can form with the material and method as described in stage 0094-0100 of Unexamined-Japanese-Patent No. 2010-272891, and stage 0053-0060 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 or changing the light emission wavelength. As such a dopant, the general thing used for an organic light emitting layer can be mentioned.
The film thickness of the light emitting layer is usually 1 nm to 500 nm, preferably about 20 nm to 1000 nm.

<Hole Injection and Transport Layer, Hole Transport Layer, and Hole Injection Layer>
The hole injecting and transporting layer, the hole transporting layer, and the hole injecting layer are appropriately formed between the light emitting layer and the electrode which is an anode. A hole transport layer may be further stacked on the hole injection transport layer, and a light emitting layer may be stacked thereon, or a hole injection transport layer may be further stacked on the hole injection layer. A light emitting layer may be laminated, or a hole injecting and transporting layer may be laminated on the electrode and the light emitting layer may be laminated thereon.
As materials used for the hole injecting and transporting layer, the hole transporting layer, and the hole injecting layer, known materials may be appropriately selected and used. For example, the compounds described in paragraphs [0105] to [0106] of JP-A-2011-119681, Re-table 2012/018082, JP-A-2012-069963, International Publication 2012-132126 can be appropriately selected and used.

The thickness of each 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 layer, but is 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, a hole injection material and a hole transport material are selected such that the work function value of each layer increases stepwise from the anode side toward the light emitting layer, and It is preferable to minimize the hole injection energy barrier and to complement the large hole injection energy barrier 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 which is a cathode. An electron transport layer may be stacked on the light emitting layer, and an electron injection layer may be further stacked 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. For example, metal salts such as vasocuproin, bathophenanthroline, phenanthroline derivatives, triazole derivatives, oxadiazole derivatives, pyridine derivatives, tris (8-quinolinolato) aluminum (Alq3), and polymer derivatives of these can be mentioned. For example, a layer of an alkali metal salt of an 8-quinolinol derivative such as 8-quinolinolatolithium (Liq) is formed, and a layer formed by vacuum-depositing an appropriate amount of aluminum which is a typical heat reducing metal on the layer is formed. Is one of the preferred configurations. At this time, since the aluminum metal reacts in situ with an alkali metal ion (Li + in Liq), it changes to an oxidation state to become an aluminum ion-containing compound. Further reduced Li metal generated from the electron-transporting organic material present in the vicinity (e.g., Alq) by an oxidation-reduction reaction by electron transfer ^- a charge transfer complex of ((Li + Alq →) Li + + Alq ( radical anions)) Form.
In addition, materials and methods described in paragraphs 0031 to 0052 and 0098 to 0104 of International Publication 2012-132126 can be appropriately selected and used.
In addition, as a material containing an organic component used for an electron injection transport layer, an electron transport layer, and an electron injection layer, when forming the charge generation layer concerning this invention by the solution apply | coating method, the point which makes a residual film rate high. Therefore, the molecular weight or 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 contained in each light emitting unit may be different, and the material contained in each layer may be different.
The thickness of one light emitting unit may be appropriately adjusted, but is preferably 30 to 200 nm.

(3) Electrode The organic EL element of the present invention has a first electrode and a second electrode, and at least two electrodes facing each other on a substrate. In the organic EL element of the present invention, the first electrode and the second electrode are usually either an anode or a cathode, and in FIG. 2, for example, the electrode 1 acts 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, as shown in FIG. 1, in the case of one light emitting unit, the first electrode is usually an anode, but the second electrode may be a blocking electrode because the charge generation layer can serve in place of the second electrode. It may be a (non-activated electrode).
The first electrode and the second electrode differ depending on which electrode is required to be transparent depending on the extraction direction of the light emitted from the light emitting layer. For example, in FIG. 2, when light is taken out from the substrate 6 side, the electrode 1 needs to be formed of a transparent material, and when light is taken out from the electrode 5 side, the electrode 5 needs to be formed of a transparent material is there.
In the organic EL element of the present invention, the electrode is preferably formed of a metal or a metal oxide, and a known material can be appropriately adopted. Usually, it can be formed of metal such as aluminum, gold, silver, nickel, palladium, platinum or the like, metal oxide such as ITO (indium tin oxide), IZO (indium zinc oxide) or the like. In order to make it a transparent electrode, it is preferable to form with the oxide of indium and / or tin.

The electrode is usually formed on a substrate by a sputtering method, a vacuum evaporation method or the like in many cases, but can also be formed by a wet method such as a coating method or a dip method. The thickness of the electrodes varies depending on the transparency required for each electrode. When transparency is required, it is desirable that the light transmittance of the electrode in the visible light wavelength region is usually 60% or more, preferably 80% or more, and in this case, the thickness is usually 10 to 1000 nm, Preferably it is about 20-500 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 is a layer containing a metal, and is formed of the metal or metal oxide generally used for the electrode as described above.
In addition, the materials and methods described in paragraphs 0062 to 0097 of International Publication 2012-132126 can be appropriately selected and used.

(4) Substrate The substrate is a support of the organic EL element of the present invention, and may be, for example, a flexible material or a hard material. Specific examples of the material that can be used include glass, quartz, polyethylene, polypropylene, polyethylene terephthalate, polymethacrylate, polymethylmethacrylate, polymethylacrylate, polyester, polycarbonate and the like.
Among these, when using a synthetic resin substrate, it is desirable to have gas barrier properties. The thickness of the substrate is not particularly limited, but is usually about 0.005 to 5 mm.
In the case where light emitted from the light emitting layer is transmitted through the substrate 6 side and taken out, at least the substrate 6 needs to be a transparent material.
In addition, materials and methods described in paragraph 0109 of International Publication No. 2012-132126 can be appropriately selected and used.

(5) Characteristics of the Organic EL Element of the Present Invention, Applications Since the organic EL element of the present invention can include two or more light emitting units, the organic EL element including one light emitting unit and light emitted Compared with the organic EL device including one light emitting unit, when the intensity is made the same, light emission can be performed in a state in which the power applied to each light emitting layer is reduced, and therefore, the lifetime of the device can be prolonged. .
Further, even if the organic EL device of the present invention is an organic EL device including one light emitting unit, since it has the charge generation layer, it is not necessary to consider the energy barrier between the cathode and the electron injection layer. Since it is sufficient to consider the electron injection transport layer where electrons generated from the layer move and the energy barrier on the light emitting layer side, the design of voltage reduction is facilitated. As a result, improvement in device characteristics such as power efficiency and life 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 light emission wavelengths of the respective light emitting layers contained in the respective light emitting units emitting light different from each other. Thus, it is possible to make the color of the light extracted from the organic EL element different from the color of the light emitted from each light emitting layer. For example, the color of the light taken out can be made white by mixing the light emission wavelengths of the light emitting layers included in each light emitting unit as two colors in a complementary color relationship or mixing them as three colors of RGB.

  The organic EL element of the present invention can be suitably used for display elements, displays, electrophotography, backlights, illumination light sources, recording light sources, exposure light sources, reading light sources, signs, signs, interiors, optical communication and the like. The lighting device will be described later.

2. Method of Manufacturing Organic EL Device A method of manufacturing an organic EL device according to the present invention comprises 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 generating layer disposed between the light emitting unit and the second electrode when the light emitting unit is one, and disposed between adjacent light emitting units when the light emitting units are two or more. A method of manufacturing an organic electroluminescent device having
The charge generating 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 in a mixture or respectively. A process for producing an organic electroluminescent device.

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

(In the 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 may contain a hetero atom And 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 nanoparticle is formed by attaching a protective agent for protecting the surface to the particle surface, and the protective agent is The linking group that produces the action of linking to the transition metal compound and the organic group having 2 or more carbon atoms, and the linking group is a hydroxyl group, a sulfonamide group, and the following general formulas ( 1-a ) to ( 1-o ) A transition metal compound nanoparticle which is one or more selected from the group consisting of a functional group represented by:

(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 of manufacturing an organic EL element of the present invention, the charge generation layer can be formed by a coating method. If the charge generation layer can only be formed as a thin film by a deposition method in a stack type organic EL element, even if a light emitting unit such as a light emitting layer is formed by a solution coating method, eventually the advantage of the solution coating method can not be utilized. However, according to the present invention, a stable charge generation layer can be formed by a solution coating method. Therefore, the manufacturing method of the organic EL element of the present invention is excellent in the point of large area-ization, high productivity, etc.

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

  In addition, since said (A '), said (B), and said amine compound were demonstrated in said (A), said (B), and said amine compound, description here is abbreviate | omitted.

As the step of forming the charge generation layer by a coating method using one or two or more inks containing at least one of (A ′) and (B) and an amine compound, for example, The following steps may be mentioned.
In the present invention, as a first method of forming the charge generation layer by a coating method, an ink (α) containing at least one of the above (A ′) and (B), and an ink containing an amine compound And forming a charge generation layer in which a layer containing at least one of the above (A ′) and (B) and a layer containing an amine compound are laminated by using two kinds of inks. It has a process.
As the second method of forming the charge generation layer by the coating method in the present invention, the ink (β) containing at least one of the (A ′) and (B) and an amine compound is used. A step of forming a charge generation layer containing a mixture of at least one of (A) and (B) and an amine compound by a coating method.

Further, an ink (α) containing at least one of the above (A ′) and (B), and an ink (β) containing at least one of the above (A ′) and (B) and an amine compound A layer containing at least one of (A ′) and (B), and a mixed layer of at least one of (A ′) and (B) and an amine compound, using two types of ink It may be a step of forming a charge generation layer in which the first and second layers are stacked by a coating method.
Also, an ink (β-1) containing at least one of the above (A ′) and (B) and an amine compound, at least one of the above (A ′) and (B), and an amine compound (A ′) and (A ′) and (B), respectively, using two inks having different ratios of at least one of the (A ′) and (B) to an amine compound; It may be a step of forming a charge generation layer in which two mixed layers of at least one 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, an ink (α) containing at least one of the (A ′) and (B), an ink containing the amine compound, and two inks are used to form the (A ′) and (A) The step of forming the charge generation layer in which the layer containing at least one of B) and the layer containing the amine compound are stacked by the coating method improves the function as the charge generation layer, and the luminous efficiency and the luminance are enhanced. , From the point of improving the life.
On the other hand, when a mixed layer is formed using an ink containing at least one of the above (A ′) and (B) and an amine compound, at least one of the above (A ′) and (B) In the step of mixing the amine compound and the amine compound, the contact area between at least one of the (A ′) and (B) and the amine compound is increased, the charge generation function is improved, and the coating step 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, a solvent capable of dissolving 0.1% by mass or more of the amine compound at 25 ° C. is preferably used, more preferably a solvent capable of dissolving 1% by mass or more, and 5% by mass or more Even more preferable. 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 as an ink, it does not have to contain an additional solvent. In addition, the ink containing (A ′) may contain a solvent, and as the solvent, it is preferable to use a solvent which dissolves (A ′) at 0.1% by mass or more at 25 ° C. It is further preferable to use a solvent that dissolves by 1% by mass or more, and it is even more preferable to dissolve by 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. Furthermore, in the case of thickening, it is preferable to contain 0.6 to 20% by mass.

When the charge generation layer is formed using the ink containing (A ′), it is represented by a metal complex of at least one of molybdenum, tungsten, and vanadium as raw materials and the general formula (II) (A ') by heating a mixture with a compound to prepare the (A'), and applying the ink containing the (A ') to form a charge generation layer; It is preferable from the viewpoint of improving the life that all the steps from the step of preparing ') to the step of forming the charge generating layer are performed under an inert gas atmosphere.
In this case, the ink is prepared not only by the influence of atmospheric oxygen and moisture during the preparation of (A ′) but also when preparing the ink using the prepared (A ′). Even when the charge generation layer is formed using the ink containing (A ′), the prepared (A ′) is not in contact with water without being affected by oxygen and moisture in the air, It is presumed that the reaction product of oxygen and some of the system is generated during the process and mixed in the hole injecting and transporting layer.
The inert gas atmosphere refers to, for example, 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 dispersed in a solvent in which at least the (B) transition metal compound nanoparticles are well dispersed. Use ink. The solvent used for the ink containing (B) is not particularly limited as long as the transition metal-containing nanoparticles and, if necessary, other components are favorably dissolved or dispersed. In consideration of the hydrophilicity, hydrophobicity and the like of the protective agent, a solvent having the solubility of the protective agent is appropriately selected and used.
As the ink containing (B), it is preferable to contain 0.1 mass% or more of (B) in the total amount of the ink, and in the case of thickening the film, 0.6 to 20 mass% is contained. It is preferable to do.

Since the light emitting layer, the electron transport layer, etc., which become the lower layer 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 etc. It is preferable to form using a hydrophilic solvent.
For example, as a hydrophilic solvent, as a specific example, 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. But not limited thereto.
The charge generation layer may be formed using a hydrophobic solvent, as long as the lower layer of the charge generation layer does not dissolve even when using a hydrophobic solvent when forming the charge generation layer. Examples of hydrophobic solvents and low polar solvents include toluene, xylene, mesitylene, dodecylbenzene, cyclohexanone, tetralin, mesitylene, anisole, methylene chloride, tetrahydrofuran, dichloroethane, chloroform, ethyl benzoate, butyl benzoate, acetonitrile and the like. Although it is possible, it is not limited to these.
In addition, the charge generation layer may be formed by appropriately selecting and using a mixed solvent of the hydrophilic solvent and the hydrophobic solvent as long as the solvents are mutually compatible.

As each solvent in the case of laminating and forming a layer using two or more types of ink containing at least one of the above (A ′) and (B) and an amine compound, the ink is used It is preferable to appropriately select and use a solvent which does not dissolve the lower layer which becomes the base when laminating the organic layers. Here, the fact that the lower layer is not dissolved means that each layer in the lower layer is not completely dissolved (remaining film rate is 0%). When the lower layer is not completely dissolved, when two charge generation layers are laminated, one of the two layers may be hydrophilic, the other may be hydrophobic, both may be hydrophobic, and both may be hydrophilic.
Among them, it is desirable to select a solvent such that the residual film ratio of the lower layer is 10% or more, more preferably 30% or more, and still more preferably 50% or more.
Here, the residual film rate of the lower layer can be evaluated as follows.
First, a layer to be the lower layer is formed on a quartz substrate (for example, 25 mm × 25 mm) by the material and thickness of the layer to be the lower layer, and a test film is formed. From the viewpoint of obtaining a more detailed residual film rate, it is preferable to form a test film for each of the lower layers, such as an electron injecting and transporting layer and a light emitting layer, as the test film. For example, in the case where 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 rotation speed is to obtain a desired film thickness by the spin coater. Apply The upper layer is dried under conditions to dry to form a test film after solution application.
The residual 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 solution application] / [Absorbance of absorption maximum of test film before solution application]) × 100 (%) = residual film ratio (%), residual film ratio is calculated.
In addition, although it is possible to calculate the residual film ratio by the above method because the organic EL material normally has absorption in the ultraviolet-visible absorption spectrum, in the case where it does not have absorption in the ultraviolet-visible absorption spectrum, atomic force microscope ( The residual film ratio can be determined by directly measuring the film thickness of the test film before and after application of the solution using AFM) or a stylus surface shape measuring instrument (for example, DEKTAK series, manufactured by SLOANA).

In the ink (β) containing at least one of the above (A ′) and (B) and the amine compound, both of at least one of the above (A ′) and (B) and the amine compound are good. As mixing in a solvent which dissolves or disperses causes the amine compound to interact with at least one of (A ′) and (B) in the solution to easily form a charge transfer complex, charge generation property And it is preferable from the point which can form the charge generation layer excellent in the aging stability of a film | membrane.
The ink (β) preferably contains a total amount of at least one of the above (A ′) and (B) and an amine compound in an amount of at least 0.1 mass% in the total amount of the ink, and further thickens In the case, it is preferable to contain 0.6 to 20% by 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 more inks each containing at least one of the (A ′) and (B) and the amine compound in a mixture or respectively contain Since at least one of (1) and (B) and the amine compound have high affinity to the solvent, it is possible to obtain an ink having high uniform stability by appropriately selecting the solvent. Can. Therefore, according to the present invention, since the manufacturing process is easy and a uniform film having high stability can be formed, short-circuit does not easily occur, the yield is high, and a charge transfer complex is formed to achieve long life. It becomes possible.

  Here, with the solution coating method, one or more inks containing at least one of the (A ′) and (B) and an amine compound are prepared, and the one or more inks The ink of the invention is applied onto the light emitting layer unit as a base and dried to form a charge generating layer. The ink may be added with other charge transportable compounds as described above, and additives such as binder resins that do not trap holes and electrons, or coatability improvers, and dissolved or dispersed. It may be prepared.

  As the solution coating method, for example, a liquid dropping method such as immersion method, spray coating method, spin coating method, blade coating method, dip coating method, casting method, roll coating method, bar coating method, die coating method, ink jet method etc. may be mentioned. Be When it is desired to form a monomolecular film, a dipping method or dip coating method is suitably used.

In particular, in the case of manufacturing a stack-type organic EL element, the following manufacturing method has high productivity, and the number of processes is small compared to the manufacturing method of coating and stacking the stack-type organic EL layer on one substrate. It is preferable from the point that a yield improves as a result. In addition, according to the manufacturing method, there is an advantage that the load for selecting a solvent which does not dissolve the lower layer is reduced. Furthermore, even if the charge generation layer is thin, the charge generation layer is formed over the lower layer through the charge generation layer. There is no problem that the solvent at the time of formation penetrates and dissolves the lower layer of the charge generation layer.
That is, the method for producing a stack-type organic EL device preferred in the present invention is
Preparing a first laminate having at least one light emitting unit including an anode and a light emitting layer on one side of the first substrate, and a light emitting unit including a cathode and a light emitting layer on one side of the second substrate Providing a second laminate, comprising at least one
Forming a charge generating 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) On the light emitting unit side surface of the second laminate, an ink containing an amine compound is used to form a charge generation layer precursor coating film (N) and at least one of (A ′) and (B) 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 the surface on the light emitting unit side of at least one of the first laminate and the second laminate And a step of forming a charge generation layer precursor coating film (MN), with the light emitting unit sides of the first laminate and the second laminate having the charge generation layer precursor coating film formed thereon facing each other. And depositing a first laminate and a second laminate through the generation layer precursor coating film and forming a charge generation layer.

The manufacturing method of the said preferable stack type organic EL element is demonstrated using drawing.
FIGS. 3A to 3D and 4E to 4G are process diagrams showing an example of a method of manufacturing an organic EL element according to the present invention. In the method of manufacturing an organic EL device according to the present invention, as shown in FIG. 3A, at least one light emitting unit 13 including the anode 11 and the light emitting layer 12 is provided on one surface side of the first substrate 10. The first laminate 100 is prepared. On the other hand, as shown to FIG. 3 (B), the 2nd laminated body 200 provided with at least one light emission unit 23 including the cathode 21 and the light emitting layer 22 on one surface side of the 2nd board | substrate 20 is prepared. Next, as shown in FIG. 3C, a charge generation layer precursor is formed using an ink containing at least one of (A ′) and (B) on the surface of the first laminate 100 on the light emitting unit 13 side. The coating film 14 (M) is formed. On the other hand, as shown in FIG. 3D, a 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. . Then, 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 sides of the formed second stacked body 200 are opposed to each other. Next, as shown in FIG. 4F, the first laminate 100 and the second laminate 200 are attached via the charge generation layer precursor coatings 14 (M) and 24 (N), as shown in FIG. As shown in (G), the charge generation layer 15 is formed.

  FIGS. 5 (A), (B), and (H) and FIGS. 6 (I) to (K) are process diagrams showing another example of the method for manufacturing an organic EL element according to the present invention. In the method of manufacturing an organic EL device according to the present invention, as shown in FIG. 5A, at least one light emitting unit 13 including the anode 11 and the light emitting layer 12 is provided on one side of the first substrate 10 The first laminate 100 is prepared. On the other hand, as shown to FIG. 5 (B), the 2nd laminated body 200 equipped with at least one light emission unit 23 including the cathode 21 and the light emitting layer 22 on one surface side of the 2nd board | substrate 20 is prepared. Next, as shown in FIG. 5H, on the surface of the second laminate 200 on the light emitting unit 23 side, an ink containing an amine compound is used to form a charge generation layer precursor coating 24 (N), A charge generation layer precursor coating 14 (M) is formed in this order using an ink containing at least one of A ') and (B). Next, as shown in FIG. 6I, the light emitting unit 13 side of the first laminate 100, and 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 sides of the second stacked body 200 are made to face each other. Then, as shown in FIG. 6J, the first laminate 100 and the second laminate 200 are attached via the charge generation layer precursor coatings 14 (M) and 24 (N), and As shown in (K), the charge generation layer 15 is formed.

  FIGS. 7 (A), (B), and (L) and FIGS. 8 (M) to (O) are process diagrams showing another example of the method for manufacturing an organic EL element according to the present invention. In the method of manufacturing an organic EL device according to the present invention, as shown in FIG. 7A, at least one light emitting unit 13 including an anode 11 and a light emitting layer 12 is provided on one surface side of the first substrate 10. The first laminate 100 is prepared. On the other hand, as shown to FIG. 7 (B), the 2nd laminated body 200 equipped with at least one light emission unit 23 containing the cathode 21 and the light emitting layer 22 on one surface side of the 2nd board | substrate 20 is prepared. Then, as shown in FIG. 7 (L), an ink containing at least one of (A ′) and (B) and an amine compound on the surface of the first laminate 100 on the light emitting unit 13 side. Used to form charge generation layer precursor coating 14 (MN). Next, as shown in FIG. 8M, the light emitting unit 13 side of the first laminate 100 on which the charge generation layer precursor coating film 14 (MN) is formed and the light emitting unit 23 side of the second laminate 200 are Let each face each other. Next, as shown in FIG. 8N, the first laminate 100 and the second laminate 200 are attached via the charge generation layer precursor coating film 14 (MN), and are shown in FIG. 8O. As a result, the charge generation layer 15 is formed.

In the step of forming the charge generation layer, after forming a charge generation layer precursor coating film by a coating method using the various inks, the film is heated, dried if necessary, and further heated if necessary. , Form a charge generation layer.
In the step of forming the charge generation layer 15 while depositing the first laminate and the second laminate through the charge generation layer precursor coating in the stack type organic EL device, the charge generation layer precursor coating At the time of depositing the first laminate and the second laminate through the adhesive layer, the solvent or volatile component is still deposited in the coating in a state where the solvent or volatile component is partially left, and then laminated. The components can be completely dried to form the charge generating layer.
Alternatively, in the case where a component having a melting point or a glass transition temperature of 200 ° C. or less is contained in at least one of the ligands (A ′) and (B), a protecting agent, or an amine compound, Preferably, the first laminate and the second laminate are attached via the charge generation layer precursor coating film and heated to form a charge generation layer. In this case, the first laminate and the second laminate may be laminated in a state in which almost all the solvent or volatile component in the charge generation layer precursor coating film is dried, and the charge generation layer precursor coating film is heated A component having a melting point or a glass transition temperature of 200 ° C. or less in at least one of the ligands (A ′) and (B) in the charge generation layer precursor coating, a protecting agent, or an amine compound The first laminate and the second laminate can be deposited, and the charge generation layer can be formed after cooling. The heating temperature of the charge generation layer precursor coating is a melting point or glass transition temperature of 200 ° C. or less in at least one of the ligands (A ′) and (B), a protective agent, or an amine compound. The temperature may be appropriately selected so as to be higher than the melting point or the glass transition temperature of the component of The upper limit of the heating temperature is preferably 220 ° C. or less from the viewpoint of decomposition of the organic material.

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

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

As a means to oxidize, for example, a heating step, a light irradiation step, a step of reacting active oxygen, etc. may be mentioned, and these may be used in combination as appropriate. The oxidation is preferably carried out in the presence of oxygen in order to conduct oxidation efficiently.
When using a heating process, the method of heating on a hot plate, the method of heating in oven, etc. are mentioned as a heating means. As heating temperature, 50-250 degreeC is preferable. Since the interaction with the at least one amine compound of (A ′) and (B) and the interaction between at least one of (A ′) and (B) differ depending on the heating temperature, it is possible to It is preferable to adjust.

  When using a light irradiation process, the method etc. of exposing an ultraviolet-ray as a light irradiation means are mentioned. The difference between the interaction with at least one of the (A ′) and (B) and the interaction between at least one of the (A ′) and (B) depends on the light irradiation amount. It is preferable to adjust appropriately.

In the case of using a process in which active oxygen acts, as a method of causing active oxygen, a method of causing active oxygen to act by ultraviolet light or activating active oxygen by irradiating ultraviolet light to a photocatalyst such as titanium oxide There is a method of causing it to act. Depending on the amount of active oxygen, there is a difference in the interaction of the (A ′) and (B) with the at least one amine compound or the interaction of the (A ′) and the (B), It is preferable to adjust appropriately.
Among these means for forming oxides, it is more preferable to have a heating step in the presence of oxygen which does not require light irradiation, from the viewpoint that it is difficult to damage the organic EL layer already formed.

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 or a vapor deposition method or a transfer method. The solution coating method can be the same method as the charge generation layer described above. The transfer method is formed, for example, by laminating a layer previously formed on a film by a solution application method or a vapor deposition method to a layer to be laminated, and transferring the layer by heating or the like as appropriate.
In addition, as other steps in the method of manufacturing an organic EL element, conventionally known steps can be appropriately used.

3. Organic EL Lighting Device A lighting device according to the present invention will be described. A lighting device according to the present invention comprises the organic electroluminescent device according to the present invention.
FIG. 9 is a schematic cross-sectional view showing an example of the basic layer configuration of the organic EL lighting device according to the present invention. One example of the organic EL lighting device according to the present invention is the first light emitting unit 13 including the anode 11, the light emitting layer 12 on the first substrate 10, and the following (A) on the first light emitting unit 13: And a layer containing at least one of (B) and a layer containing an amine compound in this order: a charge generation layer 15, a light emitting unit 23 including a light emitting layer 22, a cathode 21, and a second layer The substrate 20 and the substrate 20 are disposed in this order, and are sealed in close contact with the first substrate 10 and the second substrate 20 and around the organic EL element using the sealing material 30. Usually, nitrogen gas is filled in the sealed enclosed space and a water collecting agent (not shown) is provided. The light extraction surface may be appropriately selected from any of the first substrate 10 and 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. A seal material such as a photo-curable adhesive is appropriately adhered to the periphery of the organic EL element between the substrates, and UV light or the like is appropriately irradiated from the glass substrate side to cure and seal. And formed lighting devices. The above-mentioned sealing operation is usually performed in a glove box (under an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more) under a nitrogen atmosphere without bringing the organic EL element into contact with the atmosphere. In addition, nitrogen gas is usually filled in the sealed case and a water collecting 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 or an exposure light source, using a known configuration as appropriate. Furthermore, the organic EL lighting device according to the present invention is a light source device of a projection device of a type that projects an image using a known configuration as appropriate, or a display device (display) of a type of directly viewing still images and moving images. It may be used as

  In the organic EL lighting device according to the present invention, the organic EL element provided may be used as an organic EL element having a resonator structure. When an organic EL element having such a resonator structure is used, for example, 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 processing machine, a light source of an optical sensor Applied.

  Hereinafter, the present invention will be more specifically described by way of examples. These descriptions do not limit the present invention. In the examples, parts are by weight unless otherwise specified. Also, the thickness of the layer or film is represented by the average film thickness.

Synthesis Example 1
(1) Preparation of Compound Represented by Formula (A ′) Formula (I) 0.99 g of molybdenum hexacarbonyl (manufactured by Kanto Chemical Co., Ltd.) and dipivaloyl methane (manufactured by Tokyo Kasei Kogyo Co., Ltd., hereinafter referred to as “acac-tBu”) 6.9 g was added to a three-necked flask, and the mixture was heated under reflux at 140 ° C. for 5 hours while stirring under an argon gas atmosphere to obtain a reddish brown reaction liquid. The obtained reaction solution is put in a glass tube oven, the pressure is reduced by a vacuum pump, and heating is carried out at 80 ° C. for 3 hours to remove unreacted dipivaloylmethane, and 0.16 g of reaction product 1 of black solid is obtained. The

<Analysis of reaction product 1>
The reaction product 1 of the black solid obtained in Synthesis Example 1 was measured by TOF-SIMS (TOFSIMS 5 manufactured by ION-TOF) under the following conditions. The measurement results are shown in FIG.
The secondary ion detected by the measurement has a main peak having a molecular weight of 481, which corresponds to MoO ₂ (acac-tBu) ₂ (in the compound represented by the above general formula (I), R ¹ and R ² are t -It was thought that it corresponded to the mass number (molecular weight 481) which one oxygen atom deviated from-butyl group, m = 2, n = 2; molecular weight 497).
(TOF-SIMS measurement conditions)
Primary ion species: Bi ^{3 ++}
Primary ion acceleration voltage: 25kV
Primary ion current value: 0.2 pA
Frequency: 10kHz
Measurement area: 200 μm × 200 μm
Scan: 128 pixels × 128 pixels × 64 scan
Charge correction: Electron irradiation

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

Synthesis Example 2
(1) Preparation of (B) Transition Metal Compound Nanoparticles A molybdenum carbide oxide-containing nanoparticle ink protected with 12-amino-1-dodecanol was prepared. 0.1 g of 12-amino-1-dodecanol (manufactured by Tokyo Chemical Industry Co., Ltd.) and 12.8 g of 2-methyl-2,4-pentanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) in a 50 ml three-necked flask The reaction mixture was weighed, depressurized with stirring, and left at room temperature (24.degree. C.) for 1.5 hours to remove low volatile components. The atmosphere was changed from the vacuum to the atmosphere, and 0.8 g of molybdenum hexacarbonyl (manufactured by Kanto Chemical Co., Ltd.) was added. The mixture was brought to an argon gas atmosphere and heated to 180 ° C. with stirring, and the temperature was maintained for 2 hours. The mixture is then cooled to room temperature (24 ° C.) and the black 12-amino-1-dodecanol protected molybdenum oxide nanoparticles are incorporated into 2-methyl-2,4-pentanediol. An ink was obtained containing dispersed molybdenum carbide oxide-containing nanoparticles. Using the nanoparticles from which the solvent has been removed from the ink, the measurement of the crystal structure and the measurement of the valence are performed in the same manner as in paragraphs 0186 to 0189 of WO 2012/018082 to obtain molybdenum carbide oxide-containing nanoparticles. It was confirmed.
(2) Preparation of Ink 2 Containing Transition Metal Compound Nanoparticles of (B) The Ink Containing Molybdenum Carbide Oxide-Containing Nanoparticles Dispersed in 2-Methyl-2,4-Pentanediol Using an Evaporator After removing 2-methyl-2,4-pentanediol, it was dried to obtain a 12-amino-1-dodecanol-protected molybdenum oxide-containing oxide-containing nanoparticle. By dispersing the nanoparticles thus obtained in water, an ink 2 (solid content concentration: 0.4% by mass) containing the molybdenum carbide oxide-containing nanoparticles dispersed in water was obtained.

Example 1
Light emitting unit including a hole injecting and transporting layer, a light emitting layer, and an electron injecting and transporting layer on a glass substrate on which a transparent anode is formed as a first electrode, and a charge generation layer, an electron injection blocking layer, a second electrode (cathode Film formation was carried out according to the following procedure in the order of 2.), it laminated, finally it sealed, and produced an organic EL element. The operation was carried out in a glove box under a nitrogen atmosphere (oxygen concentration: 1 ppm or less, water concentration: 1 ppm or less) unless otherwise specified, except for the preparation of the transparent anode-attached glass substrate. The electron injection block layer is a layer for blocking electron injection from the second electrode.

  First, a thin film (thickness: 150 nm) of indium tin oxide (ITO) was used as a transparent anode. An ITO-attached glass substrate (manufactured by Three Volume Vacuum Co., Ltd.) was patterned in a strip shape. The patterned ITO substrate was subjected to ultrasonic cleaning in the order of a neutral detergent and ultrapure water, and subjected to UV ozone treatment.

  Next, a PEDOT / PSS aqueous dispersion (CLEVIOUS P AI4083 manufactured by Heraeus Co., Ltd.) is applied on the anode by spin coating on the air, heated at 200 ° C. for 30 minutes in the air using a hot plate, An injection transport layer was formed. The thickness after heating was 40 nm.

  Next, on the hole injecting and transporting layer, F8BT (poly [(9,9-di-n-octylfluorenyl-2,7-diyl) -alto- (benzo [2,1,3] thiadiazole) -4,8- Diyl) Solid content concentration 1.2 mass% xylene solution) was applied by a spin coat method, and it heated at 150 ° C for 30 minutes using a hot plate, and formed a luminous layer. The thickness after heating was 80 nm.

Next, 3TPYMB (tris [3- (3-pyridyl) mesityl] borane): Liq (8-hydroxyquinolinolato-lithium) = 1: 1 (solid concentration 3% by mass) on the prepared light emitting layer, A 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, and Liq is reduced by depositing Al with a thickness of 2 nm on the 3TPYMB: Liq layer in vacuum at a pressure of 1 × 10 ⁻⁴ Pa to reduce Liq and carry out electron injection transport. A layer was formed.

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

On the layer containing at least one of the compound (A) represented by the general formula (I) and the oxide thereof, poly [(9,9-dioctylfluorenyl-2,7- which is an amine compound] Ink containing 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 a layer containing at least one of the compound represented by the general formula (I) and the oxide thereof and a layer containing an amine compound were laminated.
The substrate was transferred into a vacuum chamber, and NPD (naphthylphenyldiamine) was deposited to a thickness of 50 nm as an electron injection block layer on the charge generation layer under vacuum at a pressure of 1 × 10 ^-4 Pa. Subsequently, gold was deposited to a thickness of 70 nm on the electron injection block layer as a second electrode.
Finally, the inside of the glove box was sealed using a non-alkali glass and a UV curable epoxy adhesive to prepare an organic EL element of Example 1.

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

Example 2
In Example 1, the ink 1 (solid content concentration 0.5 mass%, 1-butanol solution) containing the compound represented by the above (A ′) general formula (I) prepared in the above synthesis example 1 is spin coated The procedure of Example 1 was repeated except that the solution was applied by a method and heated at 180 ° C. for 30 minutes in a glove box (under a nitrogen atmosphere) using a hot plate.

<TOF-SIMS Analysis of Layer Containing (A) of Example 2>
About the layer containing said (A) of Example 2, it carried out similarly to reaction product 1 of the black solid obtained by the synthesis example 1, and performed TOF-SIMS (TOFSIMS5 made by ION-TOF company) measurement.
The secondary ion detected by the measurement detected a molecular weight of 481 as a main peak. This is because the oxygen atom is represented by 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; Was considered to correspond to a mass number with one deviation (molecular weight 481).

[Example 3]
In Example 1, Ink 1 (solid content concentration: 5% by mass, 1-butanol solution) containing the compound represented by the above (A ′) general formula (I) prepared in the above Synthesis Example 1 is applied by spin coating It apply | coated and heated at 180 degreeC in air | atmosphere for 30 minutes using the hotplate. The same as Example 1 except that the thickness after heating was set to 30 nm.

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

Example 4
In Example 1, instead of using Ink 1 containing the compound represented by Formula (A ′) represented by Formula (I) prepared in Synthesis Example 1 as the charge generation layer, the above prepared in Synthesis Example 2 ( B) Charge generation using the ink 2 containing transition metal compound nanoparticles, wherein the layer containing the (B) transition metal compound nanoparticles (thickness after heating: 10 nm) and the layer containing an amine compound are laminated An organic EL device of Example 4 was produced in the same manner as in Example 1 except that a layer was formed.

[Example 5]
An organic EL device 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 ink for forming a charge generation layer, the compound represented by the above (A ′) general formula (I) prepared in the above Synthesis Example 1: poly [(9,9-dioctylfluorenyl- which is an amine compound When 2,7-diyl) -co- (4,4 '-(N-4-sec-butylphenyl)) diphenylamine)] (TFB) = 1: 2 (mass ratio), the solid content concentration is 1 mass%. As described above, an ink containing the compound represented by the above-mentioned (A ') general formula (I) and an amine compound, dissolved in a mixed solvent of ethyl benzoate: cyclohexanol solution = 1: 2 (mass ratio) I got three. 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) to toluene so that the solid content concentration is 1 mass% It was made to melt | dissolve and the comparative ink 1 for charge generation layer formation was obtained.
Example 1 Example 1 except that the charge generation layer was applied by spin coating using the above-described Comparative Ink 1 for forming a charge generation layer, and heated at 150 ° C. for 30 minutes using a hot plate. The organic EL device of Comparative Example 2 was produced in the same manner as in the above.
As a result, since toluene, which is a hydrophobic solvent, was used for the charge generation layer, the electron injection transport layer in the lower layer further dissolved the light emitting layer to a residual film ratio of 0%, 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 as to obtain a solid content concentration of 1 mass%. It was dissolved in a butanol solvent to obtain 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, and became a dispersion.
Example 1 except that the charge generation layer was applied by spin coating using the above-described comparative ink 2 for forming a charge generation layer, and heated at 150 ° C. for 30 minutes using a hot plate. The organic EL device of Comparative Example 3 was produced in the same manner as in the above.
In Comparative Example 3, a uniform charge generation layer was not obtained.

<Result>
The current-applied voltage (I-V) characteristic curve of the organic EL elements of Example 1 and Comparative Example 1 is shown in FIG. Moreover, the luminance-application voltage (LV) characteristic curve of the organic EL element of Example 1 and Comparative Example 1 is shown in FIG. In addition, the current density, the brightness | luminance, and the voltage of FIG. 12, 13 are normalized and represented.
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 above (A) and the oxide thereof in the charge generation layer is Compared with the organic EL device of Comparative Example 1 in which the charge generation layer does not contain the layer containing at least one of the compound represented by the general formula (I) and the oxide thereof, the current flows. In addition, it can be confirmed that light is emitted in FIG. 13 at a 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 as an electron injection block layer and gold as a second electrode are stacked, 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 includes the layer containing at least one of the compound represented by the above (A) general formula (I) and the oxide thereof and It is considered that the laminated structure of TFB) functions as a charge generation layer and is attributed to the electrons derived from the charge generation layer.

  The same evaluation as in Example 1 was performed for Examples 2 to 5. As a result, compared with the organic EL element of Comparative Example 1, even in Examples 2 to 5, it was possible to confirm light emission at a voltage at which the current flows and at which the current rises. Comparison of Examples 1 and 2 reveals that Example 1 in which the compound represented by the above-mentioned (A ′) general formula (I) is oxidized is better in luminance and current value. The The luminance and the current value of Example 3 are higher than those of Example 1 because the film thickness of the layer containing at least one of the compound represented by the above-mentioned (A) general formula (I) and the oxide thereof Since it is thicker than Example 1, it is thought that the penetration of the solvent at the time of apply | coating the upper layer (layer containing an amine-type compound) was able to be suppressed from Example 1 compared with. Also in the fourth and fifth embodiments, as in the first embodiment, the light emission was confirmed by the voltage at which the current flows and the current rises. As for these luminescences, the laminated structure of the layer containing the transition metal nanoparticles of the above (B) and the amine compound function as the charge generation layer in Example 4 and the above prepared in Synthesis Example 1 in Example 5 (A ′) The mixed layer of the compound represented by the general formula (I) and the amine compound functions as a charge generation layer, and is considered to be caused by the electrons derived from the charge generation layer.

  The organic EL devices produced in the above Examples 1 to 5 are F8BT (poly [(9,9-di-n-octylfluorenyl-2,7-diyl) -alto- (benzo [2,1,3]). The yellow-green light emitted from thiadiazole-4,8-diyl was measured using a spectroradiometer manufactured by Topcon Co., Ltd. The measurement results are shown in Table 1. In Table 1, the voltage of Example 1 was used. The current density and the luminance were respectively set to 1 when 0.9 was set to 0.9.

* 1 Current density: Almost no flow 0 0, Brightness: Almost no light ≒ 0
* 2 Impossible to measure because the electron injection transport layer and the light emitting layer were dissolved. * 3 The charge generation layer did not melt and a uniform charge generation layer could not be obtained.

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

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

  Then, 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 second stacked body 200 was opposed to each other. Then, the charge generation layer precursor coating films 14 (M) and 24 (N) are brought into close contact with each other by heating at 130 ° C. in the atmosphere, as shown in FIG. As shown in FIG. 4G, a charge generation layer 15 was formed while depositing the two-layered structure 200, and a stack type organic EL device including two light emitting units of Example 6 was produced. This is because the ligand (dipivaloylmethane) contained in the compound represented by the above-mentioned (A ′) general formula (I) in the charge generation layer precursor coating film 14 (M) becomes liquid at 130 ° C. I use the thing.

[Example 7]
In Example 6, regarding the charge generation layer precursor coating film (M), Ink 2 containing the (B) transition metal compound nanoparticles prepared in the above Synthesis Example 2 on the light emitting unit side surface of the first laminate (solid The organic EL device of Example 7 is carried out in the same manner as in Example 6, except that the charge generation layer precursor coating film (M) is formed by spin coating using a component concentration of 0.4% by mass and a water solvent). Was produced. 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 film 14 (M) becomes liquid at 130 ° C. doing.

[Example 8]
The first laminate and the second laminate were prepared in the same manner as in Example 6.
On the surface on the light emitting unit side of the second laminate, an amine compound poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- (4,4 '-(N-4-sec)] -Butylphenyl)) diphenylamine)] (TFB) The ink (solid content concentration 1% by mass, ethyl benzoate: cyclohexanol = 1: 2 solvent) is applied by spin coating to use as a precursor for charge generation layer A coating (N) was formed. The solvent of the charge generation layer precursor coating (N) was removed by vacuum drying at 80 ° C. for 30 minutes using a hot plate. The thickness after heating was 10 nm.
Subsequently, a spin coating method is performed using Ink 1 (solid content concentration: 0.5% by mass, 1-butanol solution) containing the compound represented by the (A ′) general formula (I) prepared in the above Synthesis Example 1 To form a charge generation layer precursor coating (M). The solvent of the charge generation layer precursor coating (M) was removed by drying under reduced pressure at 70 ° C. for 5 minutes in air using a hot plate.
Next, as shown in FIG. 6I, the light emitting unit 13 side of the first laminate 100, and 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 stacked body 200 was made to face each other. Then, as shown in FIG. 6J, the first laminate 100 and the second laminate 200 are attached via the charge generation layer precursor coatings 14 (M) and 24 (N), and As shown in (K), the 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 above-mentioned (A ′) general formula (I) in the charge generation layer precursor coating film 14 (M) becomes liquid at 130 ° C. I use the thing.

[Example 9]
The first laminate and the second laminate were prepared in the same manner as in Example 6.
Compound represented by the above-mentioned (A ') general formula (I) prepared in the above-mentioned Synthesis Example 1: amine compound [poly (9,9-dioctylfluorenyl-2,7-diyl) -co- ( Ethyl benzoate: cyclohexanol solution so that the solid content concentration becomes 1 mass% with 4,4 ′-(N-4-sec-butylphenyl)) diphenylamine)] (TFB) = 1: 2 (mass ratio) It was dissolved in a mixed solvent of = 1: 2 (mass ratio) to obtain an ink containing the compound represented by the above (A ′) 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. 8M, the light emitting unit 13 side of the first laminate 100 on which the charge generation layer precursor coating film 14 (MN) is formed and the light emitting unit 23 side of the second laminate 200 are , Let each other face. Next, as shown in FIG. 8N, the first laminate 100 and the second laminate 200 are attached via the charge generation layer precursor coating film 14 (MN), and are shown in FIG. 8O. Thus, the charge generation layer 15 was formed, and a stack type organic EL device 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 above (A ′) general formula (I) becomes liquid at 130 ° C.

<Result>
In each of Examples 6 to 9, luminescence of a white color was confirmed. This indicates 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, respectively emit light and mix. The yellow-green color derived from F8BT, which is the light emitting layer of the first laminate, emits light due to the recombination of the holes injected from the transparent anode (ITO) and the electrons generated from the charge generation layer, while the light emission of the second laminate The blue color derived from polyfluorene, which is a layer, is considered to be emitted by the recombination of holes generated from the charge generation layer and electrons injected from the cathode. As described above, in the present invention, it was revealed that the charge generation layer can be efficiently obtained by the coating method in which the manufacturing process is easy, and the stack type organic EL device can be obtained.

DESCRIPTION OF SYMBOLS 1 first 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 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 Seal material 100 First laminate 200 Second laminate

Claims (4)

At least one light emitting unit including a light emitting layer disposed between the first electrode, the second electrode, the first electrode and the second electrode, and the light emitting unit and the second when the light emitting unit is one. What is claimed is: 1. A method of manufacturing an organic electroluminescent device, comprising: a charge generation layer disposed between an electrode and the light emitting unit, in the case where two or more light emitting units are adjacent to each other.
The charge generating 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 in a mixture or respectively. the step of possess,
The one or more inks contain a hydrophilic solvent, and the hydrophilic solvent is 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 A method for producing an organic electroluminescent device , which is at least one selected from the group consisting of ether and propylene glycol monomethyl ether acetate .

(A ') a compound represented by the following general formula (I);
(In the 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 may contain a hetero atom And 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 nanoparticle is formed by attaching a protective agent for protecting the surface to the particle surface, and the protective agent is The linking group which produces an action of linking to the transition metal compound and the organic group having one or more carbon atoms, and the linking group is a hydroxyl group, a sulfonamide group, and the following general formulas ( 1-a ) to ( 1-o ) in Ri der least one selected from the group consisting of functional groups represented, the protective agent, in addition to, a hydroxyl group, a carbonyl group of the linking group, a carboxyl group, an amino group, a thiol group, silanol group, scan A transition metal compound nanoparticle having one or more hydrophilic groups selected from the group consisting of a rufo group, a sulfonate and an ammonium group ;
(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 ink (α) containing at least one of the above (A ′) and (B) and the ink containing the above amine compound are used to contain at least one of the above (A ′) and (B) layer and a layer containing the amine compound has a step of forming a charge generating layer which are laminated, a method of manufacturing an organic electroluminescent device according to claim 1. The manufacturing method of the organic electroluminescent element of Claim 1 or 2 which has an oxidation process of oxidizing the metal contained in at least 1 sort (s) of said (A ') and (B). At least one following (A '), contains a hydrophilic solvent, the hydrophilic solvent is 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 A charge generation layer forming material for an organic electroluminescent device, which is at least one selected from the group consisting of monomethyl ether and propylene glycol monomethyl ether acetate The

(A ') a compound represented by the following general formula (I);
(In the 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 may contain a hetero atom And 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).