JP2013251282A - Material for forming charge transporting organic layer and manufacturing method thereof, and ink for forming charge transporting organic layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material for forming a charge transporting organic layer allowing layer-multiplication by a wet deposition method and achieving high luminance, high current efficiency and long life; and a manufacturing method thereof.SOLUTION: A material for forming a charge transporting organic layer is a reaction product of a charge transporting compound having two or more aldehyde groups with an organic transition metal complex, where the charge transporting compound is an arylamine derivative and the organic transition metal complex comprises at least one metal selected from the group consisting of chromium, rhenium, iron, cobalt, platinum, zinc and vanadium.

Description

  The present invention relates to a device having a charge transporting organic layer and a manufacturing method thereof.

  Devices having a charge transporting organic layer are organic electroluminescent elements (hereinafter referred to as organic EL elements), light emitting devices such as inorganic-organic hybrid light emitting elements, organic thin film solar cells, dye-sensitized solar cells, organic transistors, Expansion to a wide range of basic elements and applications such as organic light emitting diodes is expected.

For example, the organic EL element is a charge injection type self-luminous device that utilizes light emission generated when electrons and holes that have reached the light emitting layer recombine. The element structure of the organic EL element is currently a five-layer structure comprising an electron injection layer / electron transport layer / light emitting layer / hole transport layer / hole injection layer in order to obtain high light emission efficiency and a long driving life. Various multilayer structures have been proposed.
These layers other than the light emitting layer such as the electron injection layer, the electron transport layer, the hole transport layer, and the hole injection layer have the effect of facilitating the injection and transport of charges to the light emitting layer, or block the electron current and positive by blocking. It is said that there are effects such as maintaining the balance of the hole current and suppressing diffusion of light energy excitons.

  Such a light emitting layer, and a charge (hole, electron) transport layer, a charge injection layer, and the like formed as necessary adjacent to the light emitting layer are generally formed by a vacuum deposition method. However, in the case of a vapor phase film forming method such as vacuum deposition, there is a problem that a large-scale vapor deposition apparatus is required and the cost is high, and further, it is difficult to increase the area of the substrate. Therefore, the above light emitting layer or charge transporting layer is formed by a wet film formation method (spin coating method, printing method, ink jet method, etc.) in which an organic compound having light emitting property, charge transporting property, etc. is dissolved or dispersed in a solvent and applied to a substrate. Etc. have been proposed. The wet film-forming method that applies to the substrate using a solvent does not require a large-scale vapor deposition device compared to the vacuum vapor deposition method, can be expected to simplify the manufacturing process steps, and has the advantage that the substrate can have a large area. is there. However, in the case of multilayering by a wet film formation method, it is necessary to prevent the lower layer from being dissolved when the upper layer is formed. If the lower hole transport layer dissolves during the formation of the light emitting layer, the hole transport layer is mixed with the light emitting layer, and the device characteristics are deteriorated, for example, the light emission efficiency and luminance are reduced, and the device life is shortened. A problem occurs.

  Conventionally, lamination has been performed by a combination of materials having different solubility properties, such as using an aqueous dispersion of polythiophene-polysulfonic acid for the hole injection layer and an organic solvent solution for the light emitting layer. In addition, an attempt has been made to make a hole transporting layer under the light emitting layer contain a compound containing an epoxy group or an ethylenically unsaturated bond, and to make it insoluble in an organic solvent by curing after forming a coating film ( For example, Patent Document 1 and Patent Document 2). However, when curing using a compound containing an epoxy group or an ethylenically unsaturated bond, the hole transport material is damaged by adding a polymerization initiator or irradiating with light, and the device characteristics deteriorate. There was a problem to do.

  On the other hand, Patent Document 3 discloses a light-emitting element having a layer including a cluster in which an arylamine derivative and a metal oxide are co-evaporated. According to Patent Document 3, it is described that the drive voltage can be reduced by having a layer containing the co-deposited cluster. However, in the layer in which the arylamine derivative and the metal oxide are co-deposited, when the light emitting layer is laminated thereon by a wet film forming method, the hole transport layer is mixed with the light emitting layer, and the light emission efficiency and luminance are reduced. In addition, the device characteristics deteriorate, for example, the lifetime is shortened.

JP 2008-231419 A JP 2008-517135 A Japanese Patent No. 2006-253663

  The present invention has been made in view of the above problems, and provides a device capable of achieving high brightness, high current efficiency, and a long life while being multilayered by a wet film forming method, and a method for manufacturing the same. There is.

As a result of intensive studies to achieve the above-mentioned object, the present inventors made a reaction with a charge transporting compound having two or more aldehyde groups and an organic transition metal complex to make it insoluble in an organic solvent without uniform aggregation. It is possible to form a charge transporting organic layer, and the insolubilized charge transporting organic layer becomes a highly stable film that is not easily deteriorated and maintains good charge transporting properties, thereby improving device characteristics. The headline and the present invention have been completed.
That is, the charge transporting organic layer forming material of the present invention is a reaction product of a charge transporting compound having two or more aldehyde groups and an organic transition metal complex, and the charge transporting compound is an arylamine derivative. The organic transition metal complex contains at least one metal selected from the group consisting of chromium, rhenium, iron, cobalt, platinum, zinc, and vanadium.

Further, the method for producing a charge transporting organic layer forming material according to the present invention is for forming a charge transporting organic layer containing at least a charge transporting compound having at least two aldehyde groups, an organic transition metal complex, and an organic solvent. A step of preparing an ink;
Reaction between the charge transporting compound having at least two aldehyde groups and the organic transition metal complex by heating or light irradiation to produce a reaction between the charge transporting compound having two or more aldehyde groups and the organic transition metal complex A step of preparing a product,
The charge transporting compound is an arylamine derivative, and the organic transition metal complex contains at least one metal selected from the group consisting of chromium, rhenium, iron, cobalt, platinum, zinc, and vanadium. And

  According to the present invention, solvent resistance is imparted to a charge transporting organic layer by reacting it with a charge transporting organic layer having two or more aldehyde groups and an organic transition metal complex, and a multilayer formed by a wet film forming method. It is possible to provide a device that can achieve high brightness, high current efficiency, and long life, and a method for manufacturing the same.

  In the charge transporting organic layer forming material and the method for producing the charge transporting organic layer forming material of the present invention, the organic transition metal complex is made of chromium, rhenium, iron, cobalt, platinum, zinc, and vanadium. At least one metal selected from Among these, inclusion of cobalt is particularly preferable from the viewpoint of improving current efficiency, luminance, and device life.

According to the present invention, it is possible to form a charge transporting organic layer that is uniform and free of aggregation and has high solvent resistance by reacting a charge transporting compound having two or more aldehyde groups with an organic transition metal complex.
According to the present invention, since the charge transporting organic layer is a highly stable film that is hardly deteriorated and can maintain good charge transporting properties, it is possible to achieve high brightness, high current efficiency, and long life. It is possible to provide a device and a manufacturing method thereof.
In addition, according to the present invention, multilayering by a wet film forming method is possible, so that a large-scale vapor deposition apparatus is not required as compared with the vacuum vapor deposition method, and the manufacturing process steps are easy, and the material utilization efficiency is high. There are advantages that the cost is low and the area of the base material can be increased.

FIG. 1 is a conceptual cross-sectional view showing an example of a layer structure of a device according to the present invention. FIG. 2 is a conceptual cross-sectional view showing an example of the layer structure of the device according to the present invention. FIG. 3 is a conceptual cross-sectional view showing another example of the layer structure of the device according to the present invention. FIG. 4 is a conceptual cross-sectional view showing another example of the layer structure of the device according to the present invention. FIG. 5 is a conceptual cross-sectional view showing another example of the layer structure of the device according to the present invention. FIG. 6 is a conceptual cross-sectional view showing another example of the layer structure of the device according to the present invention. FIG. 7 is a Fourier transform infrared spectroscopic spectrum of a reaction product of a charge transporting compound having two or more aldehyde groups and an organic transition metal complex.

I. Device The device of the present invention is a device having two or more electrodes facing each other on a substrate and an organic layer disposed between the two electrodes,
At least one of the organic layers is a charge transporting organic layer containing a reaction product of a charge transporting compound having two or more aldehyde groups and an organic transition metal complex.

  The charge transporting compound having two or more aldehyde groups used in the present invention reacts uniformly without agglomeration due to the presence of the organic transition metal complex, as shown in the test examples described later. Insolubilizes in organic solvent. Therefore, in the present invention, by containing a reaction product of a charge transporting compound having two or more aldehyde groups and an organic transition metal complex, the charge transporting organic layer is uniform and free from aggregation and has high solvent resistance. Can be formed. Although the details of the reaction product are not yet elucidated, as shown in the test examples to be described later, in the reaction product, the aldehyde group has disappeared and some new aliphatic group has been generated, and 2 per molecule. It is presumed that the aldehyde group contained above forms some kind of cross-linking and hardens the charge transporting organic layer.

  Since the organic transition metal complex used in the present invention contains an organic component, it is highly compatible with a charge transporting compound containing an organic component used together, unlike a metal oxide. Therefore, it is estimated that the organic transition metal complex used in the present invention can uniformly react with the charge transporting compound without aggregating the charge transporting compound, and can cure the charge transporting organic layer. Is done. Because of these, the charge transporting organic layer according to the present invention is a highly stable film in which each component hardly aggregates, and can maintain good charge transporting properties. Therefore, high luminance, high current efficiency, and It is possible to provide a device that can achieve a long lifetime and a method for manufacturing the device.

  Many of the organic transition metal complexes used in the present invention have solvent solubility or high compatibility with the charge transporting compound used together. Therefore, the charge transporting organic layer of the present invention can be formed into a thin film by a wet film forming method. In addition, since the obtained charge transporting organic layer has high solvent resistance, a layer adjacent to the charge transporting organic layer (for example, a light emitting layer adjacent to the hole transporting layer) is formed by a wet film formation method. Can be stacked. In this case, there are merits that the manufacturing process steps are easy, the utilization efficiency of the material is high, the cost is low, and the substrate can have a large area.

Hereinafter, the layer structure of the device according to the present invention will be described.
A device according to the present invention is a device having two or more electrodes opposed to each other on a substrate and an organic layer disposed between the two electrodes, and at least one of the organic layers has a charge transporting property. It is an organic layer.
The device according to the present invention includes, for example, an organic thin film solar cell, a dye-sensitized solar cell, an organic transistor, an organic light emitting diode, and the like, in addition to a light emitting device such as an organic EL element and a quantum dot light emitting element.

Hereinafter, the layer structure of the device according to the present invention will be described.
FIG. 1 is a conceptual cross-sectional view showing a basic layer structure of a device according to the present invention. The basic layer structure of the device of the present invention comprises two electrodes (1 and 6) facing each other on a substrate 7, and at least a charge transporting organic layer 2 disposed between the two electrodes (1 and 6). It has an organic layer 3.
The board | substrate 7 is a support body for forming each layer which comprises a device, and does not necessarily need to be provided in the surface of the electrode 1, and should just be provided in the outermost surface of the device.

The charge transporting organic layer 2 is selected from the group consisting of a hole injection layer, a hole transport layer, an electron block layer, a light emitting layer, a hole block layer, an electron transport layer, and an electron injection layer in the device according to the present invention. And at least one of them. In the organic layer in the device according to the present invention, only one charge transporting organic layer may be included, or two or more layers such as a hole transporting layer and a light emitting layer may be included.
The organic layer 3 is a layer that exhibits various functions depending on the type of device by being transported by charges, and may be composed of a single layer or a multilayer. When an organic layer consists of a multilayer, the organic layer contains the layer used as the center of the function of a device, and the auxiliary layer of the said functional layer. For example, in the case of an organic EL element, a hole injection transport layer or a hole transport layer corresponds to an auxiliary layer, and a light emitting layer laminated on the surface of the hole transport layer corresponds to a functional layer.
The electrode 6 is provided in a place where the organic layer 3 including the charge transporting organic layer 2 exists between the electrode 6 and the opposing electrode 1. Moreover, you may have the 3rd electrode which is not shown in figure as needed. By applying an electric field between these electrodes, the function of the device can be expressed.

  FIG. 2 is a conceptual cross-sectional view showing an example of a layer structure of a light emitting device which is an embodiment of the device according to the present invention. The basic layer structure of the light emitting device of the present invention is that a hole transport layer 20, a light emitting layer 30, an electron transport layer 40, an electron injection layer 50, and an electrode 60 are laminated on the surface of the electrode 10 provided on the substrate 70. It has been done.

The hole transport layer 20 has a role of transporting holes injected from the electrode 10 to the light emitting layer 30 to the light emitting layer. A hole injection layer may be inserted between the hole transport layer and the electrode for the purpose of promoting the injection of holes.
The light emitting layer 30 has a role of light emission, and the contained light emitting material 100 emits light, and can also contain an organic fluorescent material or an organic phosphorescent material as the organic light emitting dopant 110 as shown in FIGS. It is. When a plurality of light emitting materials emit light, as shown in FIGS. 2 to 6, there may be electroluminescence light emission and / or photoluminescence (PL) light emission. This light emitting layer may be composed of a single layer or a multilayer (30 and 31) as shown in FIG. Further, as shown in FIG. 6, the hole transport layer may contain a light emitter.
The electron transport layer 40 has a role of transporting electrons injected from the electrode 60 to the light emitting layer 30 to the light emitting layer. A hole blocking layer that blocks penetration of holes can also be inserted between the electron transport layer and the light emitting layer. An electron blocking layer that blocks penetration of electrons can also be inserted between the hole transport layer and the light emitting layer. Further, an electron injection layer may be inserted between the electron transport layer and the electrode 60 for the purpose of promoting the electron injection layer.
The electrode 60 is provided at a place where the hole transport layer 20 and the light emitting layer 30 exist between the electrode 10 and the electrode 60 facing each other. Moreover, you may have the 3rd electrode which is not shown in figure as needed. By applying an electric field between these electrodes, the function of the device can be expressed.

The layer structure of the device of the present invention is not limited to the above-described examples, and has substantially the same structure as the technical idea described in the claims of the present invention, and has the same functions and effects. Anything that exhibits is included in the technical scope of the present invention.
Hereinafter, each layer of the device according to the present invention will be described in detail.

1. Organic layer (1) Charge transporting organic layer The charge transporting organic layer according to the present invention comprises a reaction product of a charge transporting compound having two or more aldehyde groups and an organic transition metal complex. .
In the reaction product of a charge transporting compound having two or more aldehyde groups and an organic transition metal complex, the aldehyde group of the hole transporting compound is lost due to the reaction, and some aliphatic group is newly generated, Those that form some form of cross-linking are included. The organic transition metal complex may also be an organic-transition metal oxide complex by reaction, and transition metal atoms and compounds of various valences, for example, transition metal carbides, sulfides, borides, depending on the processing conditions. , Selenides, halides and the like may be included.

As a charge transporting compound having two or more aldehyde groups, any compound having two or more aldehyde groups and having charge transporting properties can be used as appropriate. Here, charge transportability means that an overcurrent due to charge transport is observed by a known photocurrent method.
As the charge transporting compound, in addition to a low molecular weight compound, a high molecular weight compound is also preferably used. The charge transporting polymer compound refers to a polymer compound having charge transporting property and having a weight average molecular weight of 2000 or more according to polystyrene conversion value of gel permeation chromatography.

  By having two or more aldehyde groups in one molecule, the charge transporting compound can be crosslinked. One or more aldehyde groups may be contained in the repeating unit of the charge transporting polymer compound, and the upper limit of the number in one molecule is not particularly limited. It is appropriately adjusted depending on the curability of the charge transport layer and the stability of the coating film.

  In a charge transporting compound having two or more aldehyde groups, the aldehyde group has a structure directly bonded to an aromatic ring such as an aromatic hydrocarbon ring or a heterocyclic ring, so that the reaction product with the organic transition metal complex is uniform. Therefore, it is preferable from the viewpoint that a stable film that hardly aggregates can be formed, and that current efficiency, luminance, and element lifetime are improved. Further, in the charge transporting compound having two or more aldehyde groups, the position where the aldehyde group is substituted is not particularly limited, but is preferably substituted at a distant place so as to facilitate the crosslinking reaction, For example, a structure in which two or more aldehyde groups are bonded to different aromatic rings is preferable.

In the charge transporting organic layer of the present invention, since the charge transporting compound having two or more aldehyde groups is reacted in the presence of the organic transition metal complex, it is uniform even if the charge transporting compound is a low molecular weight compound. Since a stable film that hardly aggregates can be formed, a low-molecular charge-transporting compound can also be suitably used.
In the charge transporting organic layer of the present invention, in addition to the charge transporting compound having two or more aldehyde groups, it is also preferable to use a charge transporting polymer compound in combination for the purpose of supplementing the charge transporting property. .

  The specific charge transporting compound is selected from materials usually used for the layer to be the charge transporting organic layer specified in the present invention. For example, among charge transporting compounds used in a hole injection layer, a hole transport layer, an electron block layer, a light emitting layer, a hole block layer, an electron transport layer, or an electron injection layer as described later, an aldehyde group is used. Using a charge transportable compound that can be introduced, two or more aldehyde groups may be introduced to form a charge transportable compound having two or more aldehyde groups.

On the other hand, the organic transition metal complex used in the present invention is a coordination compound containing a transition metal existing between Group 3 to Group 11 in the periodic table, and includes a coordination compound containing an organic compound in addition to the transition metal. Contains a ligand.
Specific examples of the transition metal include molybdenum, chromium, tungsten, vanadium, rhenium, iron, cobalt, nickel, copper, titanium, platinum, zinc, silver, and the like.

  Among them, the transition metal of the organic transition metal complex used in the present invention includes at least one metal selected from the group consisting of molybdenum, chromium, tungsten, rhenium, iron, cobalt, platinum, zinc, and vanadium. From the viewpoints of high reactivity and improving current efficiency, luminance, and device lifetime. Among them, the organic transition metal complex used in the present invention particularly preferably contains molybdenum and / or cobalt.

The metal contained in the organic transition metal complex may be a single metal or two or more kinds. As an aspect in which two or more kinds of metals are contained, two or more kinds of metals or metal oxides may be contained in combination, or two or more kinds of metals may be contained as an alloy. Further, a different binuclear metal complex may be used.
The metal contained in the organic transition metal complex may contain a non-transition metal as long as it contains at least a transition metal.
By including two or more kinds of metals, a hole transporting layer having other functions such as complementing each other with reactivity and hole transporting properties, imparting photocatalytic properties, and controlling the refractive index and transmittance of a thin film. There is an advantage that it can be formed.

For example, the organic molybdenum complex includes a complex having an oxidation number of −2 to +6. Further, as the organic tungsten complex, there are complexes having an oxidation number of −2 to +6. Tungsten complexes tend to be polynuclear and have oxo ligands, and tend to resemble molybdenum complexes, and the coordination number may be 7 or more. Further, as the organic vanadium complex, there are complexes having an oxidation number of −3 to +5. Examples of the organic cobalt complex include complexes having an oxidation number of −1 to +4.
The type of the ligand is appropriately selected and is not particularly limited. However, a ligand containing an organic part (carbon atom) is used from the viewpoint of solvent solubility and adhesion with an adjacent organic layer. Moreover, it is preferable that a ligand decomposes | disassembles from a complex at comparatively low temperature (for example, 200 degrees C or less).

  Examples of the monodentate ligand include acyl, carbonyl, thiocyanate, isocyanate, cyanate, isocyanate, alkoxide, halogen atom and the like. Of these, carbonyl which is easily decomposed at a relatively low temperature is preferable. Examples of bidentate ligands include acetylacetonate and various carboxylic acids.

Specific examples of the structure containing an aromatic ring and / or a heterocyclic ring include benzene, triphenylamine, fluorene, biphenyl, pyrene, anthracene, carbazole, phenylpyridine, trithiophene, phenyloxadiazole, and phenyltriazole. , Benzimidazole, phenyltriazine, benzodiathiazine, phenylquinoxaline, phenylene vinylene, phenylsilole, and combinations of these structures.
Moreover, unless the effect of this invention is impaired, you may have a substituent in the structure containing an aromatic ring and / or a heterocyclic ring. Examples of the substituent include a linear or branched alkyl group having 1 to 20 carbon atoms, a halogen atom, an alkoxy group having 1 to 20 carbon atoms, a cyano group, and a nitro group. Among linear or branched alkyl groups having 1 to 20 carbon atoms, linear or branched alkyl groups having 1 to 12 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group , Sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group and the like are preferable.

  Moreover, as a ligand, a monodentate ligand or a bidentate ligand is preferable from the point that the reactivity of an organic transition metal complex becomes high. If the complex itself becomes too stable, the reactivity may be poor.

The oxidation number of 0 or less molybdenum complexes, e.g., metal carbonyl _{^{[Mo -II (CO) 5]}} 2-, [(CO) 5 Mo -I Mo -I (CO) 5] 2-, [Mo (CO) ₆ ] and the like.
Examples of the molybdenum (I) complex having an oxidation number of +1 include non-Werner type complexes containing diphosphane and η ⁵ -cyclopentadienide. Specifically, Mo ^I (η ⁶ -C ₆ H ₆ ) ₂ ] ⁺ , [MoCl (N ₂ ) (diphos) ₂ ] (diphos is a bidentate ligand (C ₆ H ₅ ) ₂ PCH ₂ CH ₂ P (C ₆ H ₅ ) ₂ ).

Examples of the molybdenum (II) complex having an oxidation number of +2 include Mo ₂ compounds in which molybdenum becomes a binuclear complex and exists in the state of (Mo ₂ ) ⁴⁺ ions. For example, [Mo ₂ (RCOO) ₄ ] And [Mo ₂ X ₂ L ₂ (RCOO) ₄ ]. Here, R in the RCOO is a hydrocarbon group which may have a substituent, and various carboxylic acids can be used. Examples of carboxylic acids include fatty acids such as formic acid, acetic acid, propionic acid, butyric acid, and valeric acid, halogenated alkyl carboxylic acids such as trifluoromethane carboxylic acid, benzoic acid, naphthalene carboxylic acid, anthracene carboxylic acid, and 2-phenylpropanoic acid. And hydrocarbon aromatic carboxylic acids such as cinnamic acid and fluorene carboxylic acid, and heterocyclic carboxylic acids such as furan carboxylic acid, thiophene carboxylic acid and pyridine carboxylic acid. Further, a carboxylic acid having a carboxyl group in a hole transporting compound (arylamine derivative, carbazole derivative, thiophene derivative, fluorene derivative, distyrylbenzene derivative, etc.) as described later may be used. Carboxylic acid has many choices, and is suitable for optimizing the interaction with the mixed hole transporting compound, optimizing the hole injection transport function, and optimizing the adhesion with the adjacent layer. It is a child. X is halogen or alkoxide, and chlorine, bromine, iodine, methoxide, ethoxide, isopropoxide, sec-butoxide, and tert-butoxide can be used. The L is a neutral ligand, it may be used triarylphosphine such as trialkylphosphine or triphenylphosphine, such as _{P (n-C 4 H 9} ) 3 or P _{(CH 3)} 3.
As the molybdenum (II) complex having an oxidation number of +2, other halogen complexes such as [Mo ^II ₂ X ₄ L ₄ ] and [Mo ^II X ₂ L ₄ ] can be used. For example, [Mo ^II Br _{4 (P (n-C 4 H} 9) 3) 4] and ^{_{[Mo II I 2 (diars)}} 2] (diars is diarsine _{(CH 3) 2 As-C} 6 H 4 -As (CH 3) 2) , etc. Is mentioned.

Examples of the molybdenum (III) complex having an oxidation number of +3 include [(RO) ₃ Mo≡Mo (OR) ₃ ] and [Mo (CN) ₇ (H ₂ O)] ⁴⁻ . R is a linear or branched alkyl group having 1 to 20 carbon atoms. Among linear or branched alkyl groups having 1 to 20 carbon atoms, linear or branched alkyl groups having 1 to 12 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group , Sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group and the like are preferable.
Examples of the molybdenum (IV) complex having an oxidation number of +4 include [Mo {N (CH ₃ ) ₂ } ₄ ], [Mo (CN) ₈ ] ⁴⁻ , and MoO ²⁺ having an oxo ligand. And a complex of Mo ₂ O ₂ ⁴⁺ double-crosslinked with O ²⁻ .

Examples of the molybdenum (V) complex having an oxidation number of +5 include [Mo (CN) ₈ ] ³⁻ and binuclear Mo ₂ O ₃ ^{4+ in} which ^Mo═O is bridged by O ²⁻ in the trans position. As an oxo complex, for example, an xanthogenic acid complex Mo ₂ O ₃ (S ₂ COC ₂ H ₅ ) ₄ , an oxo complex having a binuclear Mo ₂ O ₄ ^{2+ in} which ^Mo═O is double-bridged with O ²⁻ in the cis position. Examples thereof include a histidine complex [Mo ₂ O ₄ (L-histidine) ₂ ] · 3H ₂ O.
In addition, examples of the molybdenum (VI) complex having an oxidation number of +6 include MoO ₂ (acetylacetonate) ₂ ]. In the case of a complex having two or more nuclei, there is a mixed valence complex.

As the oxidation number of 0 or less tungsten complex include a metal carbonyl _{^{[W -II (CO) 5]}} 2-, [(CO) 5 W -I W -I (CO) 5] 2-, [W ( CO) ₆ ] and the like.
Examples of the tungsten (I) complex having an oxidation number of +1 include non-Werner type complexes containing diphosphane and η ⁵ -cyclopentadienide. Specifically, W ^I (η ⁶ -C ₆ H ₆ ) ₂ ] ⁺ , [WCl (N ₂ ) (diphos) ₂ ] (diphos is a bidentate ligand (C ₆ H ₅ ) ₂ PCH ₂ CH ₂ P (C ₆ H ₅ ) ₂ ).

The tungsten (II) complex having an oxidation number of +2 includes a W ₂ compound in which tungsten becomes a binuclear complex and exists in the state of (W ₂ ) ⁴⁺ ions. For example, [W ₂ (RCOO) ₄ ] And [W ₂ X ₂ L ₂ (RCOO) ₄ ]. Here, R in the RCOO may be the same as that described for the molybdenum complex. Other examples of the tungsten (II) complex having an oxidation number of +2 include halogen complexes such as [W ^II ₂ X ₄ L ₄ ] and [W ^II X ₂ L ₄ ]. For example, [W ^II Br _{4 (P (n-C 4 H} 9) 3) 4] and ^{_{[W II I 2 (diars)}} 2] (diars is diarsine _{(CH 3) 2 As-C} 6 H 4 -As (CH 3) 2) , etc. Is mentioned.

Examples of the tungsten (III) complex having an oxidation number of +3 include [(RO) ₃ W≡W (OR) ₃ ] and [W (CN) ₇ (H ₂ O)] ⁴⁻ . R is a linear or branched alkyl group having 1 to 20 carbon atoms.
Examples of the tungsten (IV) complex having an oxidation number of +4 include [W {N (CH ₃ ) ₂ } ₄ ], [W (CN) ₈ ] ⁴⁻ , and WO ²⁺ having an oxo ligand. And a complex of W ₂ O ₂ ⁴⁺ double-crosslinked with O ²⁻ .

Examples of the tungsten (V) complex having an oxidation number of +5 include [W (CN) ₈ ] ³⁻ and binuclear W ₂ O ₃ ^{4+ in} which ^W═O is bridged by O ²⁻ in the trans position. Examples of the oxo complex include xanthogenic acid complex W ₂ O ₃ (S ₂ COC ₂ H ₅ ) ₄ , and oxo complex having binuclear W ₂ O ₄ ^{2+ in} which ^W═O is double-bridged with O ²⁻ in the cis position. Examples thereof include a histidine complex [W ₂ O ₄ (L-histidine) ₂ ] · 3H ₂ O.
Examples of the tungsten (VI) complex having an oxidation number of +6 include WO ₂ (acetylacetonate) ₂ ]. In the case of a complex having two or more nuclei, there is a mixed valence complex.

Examples of vanadium complexes having an oxidation number of 0 or less include metal carbonyl [V ⁰ (CO) ₆ ], and examples of metal oxide complexes include V ^III O oxytriisopropoxide.
Examples of the vanadium (II) complex having an oxidation number of +2 include cyclopentadienyl complex [V ^II (η ⁵ -C ₅ H ₅ ) ₂ ].

Examples of the vanadium (III) complex having an oxidation number of +3 include [V ^III Cl ₃ {N (CH ₃ ) ₃ } ₂ ], and examples of the metal oxide complex include V ^III O acetylacetonate.
Vanadium (IV) complexes with an oxidation number of +4 include [VOCl ₂ {N (CH ₃ ) ₃ } ₂ ]), [VCl ₄ (diars)]), 8 (decahedral [VCl ₄ (diars) ₂ ] ) And the like.

Other cobalt complexes include cobalt complex (III) acetylacetonate, cobalt octacarbonyl _, bis (2,4-pentanedionato) cobalt (II), tris (2,4-pentandedionato) cobalt (III), Examples include dicobalt octacarbonyl, hexaamminecobalt (III) chloride, bis (2,4-pentanedionato) cobalt (II) dihydrate, and the like.
Other platinum complexes include platinum (II) acetylacetonate, bis (2,4-pentandionato) platinum (II), bis (tri-tert-butylphosphine) platinum (0), cis-diammineplatinum (II). ) Dichloride, dichloro (1,5-cyclooctadiene) platinum (II), tetrakis (triphenylphosphine) platinum (0) and the like.
In addition, examples of iron complexes include iron (II) acetylacetonate, tris (2,4-pentanedionato) iron (III), iron (II) acetate, iron (III) benzoylacetonate, iron pentacarbonyl, and the like. It is done.
In addition, examples of the zinc complex include zinc acetylacetonate hydrate, bis (2,4-pentanedionato) zinc (II), and the like.
Examples of chromium complexes include chromium (III) acetylacetonate, tris (2,4-pentandionato) chromium (III), tris (trifluoro-2,4-pentandionato) chromium (III), chromium picolinate ( III), chromium hexacarbonyl, bis (pentamethylcyclopentadienyl) chromium and the like.
Examples of the rhenium complex include pentacarbonylchlororhenium (I) and rhenium pentacarbonylbromide.

  In this application, it is preferable that a transition metal oxide is contained in the organic-transition metal complex which is a reaction product of an organic transition metal complex. By including transition metal oxides, the value of ionization potential is optimized, and the change due to oxidation from an unstable oxidation number +0 metal is suppressed in advance, so that the drive voltage and device lifetime are reduced. It becomes possible to improve. Among them, it is preferable that transition metal oxides having different oxidation numbers coexist in the organic-transition metal oxide composite. Since transition metal oxides having different oxidation numbers are always included together, the hole transportability is appropriately controlled by the balance of oxidation numbers, so that the device lifetime can be improved.

For example, the reaction product of a molybdenum complex or a tungsten complex is a composite having molybdenum oxidation numbers of +5 and +6 or a composite having tungsten oxidation numbers of +5 and +6, respectively. To preferred. Further, it is possible that the reaction product of the molybdenum complex or the reaction product of the tungsten complex exists in an anionic state of a complex having molybdenum oxidation numbers of +5 and +6 or tungsten oxidation numbers of +5 and +6, respectively. It is preferable from the point of improving.
When the molybdenum oxidation number is +5 and +6 or the tungsten oxidation number is +5 and +6, the oxidation number is +6 molybdenum or tungsten, and the oxidation number is +5 molybdenum or tungsten. Is preferably 10 mol or more from the viewpoint of improving the device life. On the other hand, in the case of a molybdenum oxide such as ordinary MoO ₃ , most of the molybdenum is Mo ^VI , and the composition formula is Mo _n O _3n . It becomes Mo _n O _3n-m due to oxygen vacancies at the time of vapor deposition or oxygen defects present on the particle surface caused by physical pulverization at the time of slurry formation, and Mo ^V may be present somewhat, but MoO ₃ Since the introduced Mo ^V is caused by oxygen defects, it is non-uniform and unstable.
In the case of vanadium, the oxidation number +5 is stable (V ₂ O ₅ ), and the oxidation number +4 is unstable (V ₂ O ₄ ). The reaction product of the vanadium complex is preferably present in the anion state of the complex having vanadium oxidation numbers of +5 and +4 from the viewpoint of reducing the driving voltage and improving the device lifetime.

In the charge transporting organic layer of the present invention, 1 to 500 parts by weight, preferably 10 to 200 parts by weight of an organic transition metal complex is used with respect to 100 parts by weight of the charge transporting compound having two or more aldehyde groups. It is preferable from the viewpoints of improving the charge transportability while imparting solvent resistance, and achieving a long life with high film stability.
In the charge transporting organic layer, if the amount of the organic transition metal complex is too small for the charge transporting compound having two or more aldehyde groups, the charge transporting property is improved while imparting solvent resistance, and The stability of the film is high and the effect of achieving a long life is difficult to obtain. On the other hand, if the amount of the organic transition metal complex is too large, it may be difficult to obtain the film stability effect unique to the present invention.

Further, in the hole transport layer of the present invention, in the case where a charge transporting compound having two or more aldehyde groups and another charge transporting compound different from the charge transporting compound are further used, the other charge transporting The content of the organic compound is 10 to 200 parts by weight with respect to 100 parts by weight of the charge transporting compound having two or more aldehyde groups, thereby improving the hole transportability while imparting solvent resistance. Moreover, it is preferable from the viewpoint that the stability of the film is high and a long life is achieved.
In the charge transporting organic layer, if the content of the other charge transporting compound is too large, it may be difficult to obtain the solvent resistance effect peculiar to the present invention.

  The reaction product of a charge transporting compound having two or more aldehyde groups and an organic transition metal complex contained in the charge transporting organic layer of the present invention will be described in detail in the device manufacturing method described later. A coating film for charge transporting organic layer is formed using a charge transporting organic layer forming ink containing a charge transporting compound having two or more groups, an organic transition metal complex, and preferably an organic solvent, and then heated to the coating film. It is preferable to generate | occur | produce by performing etc.

  In addition, the charge transporting organic layer of the present invention may appropriately contain other components depending on the function of the layer as long as the effects of the present invention are not impaired. Moreover, additives, such as binder resin and a coating property improving agent, may be included. Moreover, addition of a curable material is not prevented unless the effect of this invention is impaired. Examples of the binder resin include polycarbonate, polystyrene, polyarylate, and polyester. Moreover, you may contain the binder resin hardened | cured with a heat | fever or light. As a material that is cured by heat or light, a material having a curable functional group introduced into the molecule in the charge transporting compound, a curable resin, or the like can be used. Specifically, examples of the curable functional group include acrylic functional groups such as acryloyl group and methacryloyl group, vinylene group, epoxy group, and isocyanate group. The curable resin may be a thermosetting resin or a photocurable resin, and examples thereof include an epoxy resin, a phenol resin, a melamine resin, a polyester resin, a polyurethane resin, a silicon resin, and a silane coupling agent. be able to.

The specific charge transporting organic layer used in the present invention is selected from the group consisting of a hole injection layer, a hole transport layer, an electron block layer, a light emitting layer, a hole block layer, an electron transport layer, and an electron injection layer. It is preferable that it is at least one kind. Among these, the charge transporting organic layer is preferably a hole transport layer from the viewpoint of improving current efficiency, luminance, and device lifetime.
For example, when the specific charge transporting organic layer is a hole transporting layer, a reaction product of a hole transporting compound having two or more aldehyde groups and an organic transition metal complex is contained. When the specific charge transporting organic layer used in the present invention is a hole injection layer, an electron block layer, a light emitting layer, a hole block layer, an electron transport layer, or an electron injection layer, As in the case of the transport layer, a charge transport compound capable of introducing an aldehyde group used in each layer is appropriately used to form a charge transport compound having two or more aldehyde groups, and a reaction product with an organic transition metal complex is obtained. What is necessary is just to contain.
The layer that can be the specific charge transporting organic layer is specifically shown below. However, in the case where each layer does not become the specific charge transporting organic layer, the configuration illustrated below may not be used. It may be a layer.

(2) Hole transport layer As the hole transport compound, any compound having a hole transport property can be used as appropriate. Here, the hole transportability means that an overcurrent due to hole transport is observed by a known photocurrent method.
As the hole transporting compound, in addition to a low molecular compound, a high molecular compound is also preferably used. The hole transporting polymer compound refers to a polymer compound having a hole transporting property and having a weight average molecular weight of 2000 or more according to polystyrene conversion value of gel permeation chromatography.

  Examples of the hole transporting compound that can introduce two or more aldehyde groups are given below, but the position of the aldehyde group to be introduced two or more is not particularly limited, and is appropriately adjusted depending on the reactivity with the organic transition metal complex. The

The hole transporting compound is not particularly limited, and examples thereof include arylamine derivatives, anthracene derivatives, carbazole derivatives, thiophene derivatives, fluorene derivatives, distyrylbenzene derivatives, and spiro compounds. Specific examples of the arylamine derivative include N, N′-bis- (3-methylphenyl) -N, N′-bis- (phenyl) -benzidine (TPD), bis (N- (1-naphthyl-N— Phenyl) benzidine) (α-NPD), 4,4 ′, 4 ″ -tris (3-methylphenylphenylamino) triphenylamine (MTDATA), 4,4 ′, 4 ″ -tris (N- (2-naphthyl) ) -N-phenylamino) triphenylamine (2-TNATA) and the like, 4,4-N, N′-dicarbazole-biphenyl (CBP) and the like as the carbazole derivative, and N, N′-bis as the fluorene derivative As the distyrylbenzene derivative such as (3-methylphenyl) -N, N′-bis (phenyl) -9,9-dimethylfluorene (DMFL-TPD), 4- (di-p- 2,7-bis (N-naphthalen-1-yl-N-phenylamino) -9,9 is a spiro compound such as (lylamino) -4 ′-[(di-p-tolylamino) styryl] stilbene (DPAVB). -Spirobifluorene (Spiro-NPB), 2,2 ', 7,7'-tetrakis (N, N-diphenylamino) -9,9'-spirobifluorene (Spiro-TAD) and the like.
Examples of the hole transporting polymer compound include polymers containing repeating units of arylamine derivatives, anthracene derivatives, carbazole derivatives, thiophene derivatives, fluorene derivatives, distyrylbenzene derivatives, spiro compounds and the like.

  As a specific example of a polymer containing an arylamine derivative as a repeating unit, copoly [3,3′-hydroxy-tetraphenylbenzidine / diethylene glycol] carbonate (PC-TPD-DEG) as a non-conjugated polymer has the following structure: Poly [N, N′-bis (4-butylphenyl) -N, N′-bis (phenyl) -benzidine] can be exemplified as a conjugated polymer such as PTPDES and Et-PTPDK represented. Specific examples of the polymer containing anthracene derivatives in the repeating unit include poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- (9,10-anthracene)]. it can. Specific examples of the polymer containing carbazoles in the repeating unit include polyvinyl carbazole (PVK). Specific examples of the polymer containing thiophene derivatives in the repeating unit include poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- (bithiophene)]. Specific examples of the polymer containing a fluorene derivative as a repeating unit include poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- (4,4 ′-(N- (4-sec- Butylphenyl)) diphenylamine)] (TFB) and the like. Specific examples of the polymer containing a spiro compound as a repeating unit include poly [(9,9-dioctylfluorenyl-2,7-diyl) -alt-co- (9,9′-spiro-bifluorene-2, 7-diyl)] and the like. These hole transporting polymer compounds may be used alone or in combination of two or more.

  As the hole transporting polymer compound, among them, the compound represented by the following general formula (1) tends to improve the adhesion stability with the adjacent organic layer, and the HOMO energy value emits light from the anode substrate. It is also preferable from the point of being between the layer materials.

（式（１）において、Ａｒ_１〜Ａｒ_４は、相互に同一であっても異なっていてもよく、共役結合に関する炭素原子数が６個以上６０個以下からなる未置換もしくは置換の芳香族炭化水素基、または共役結合に関する炭素原子数が４個以上６０個以下からなる未置換もしくは置換の複素環基を示す。ｎは０〜１００００、ｍは０〜１００００であり、ｎ＋ｍ＝１０〜２００００である。また、２つの繰り返し単位の配列は任意である。）

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

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

In Ar _{1 to} Ar ₄ of the above general formula (1), specific examples of the aromatic hydrocarbon in the aromatic hydrocarbon group include benzene, fluorene, naphthalene, anthracene, combinations thereof, and derivatives thereof. Furthermore, a phenylene vinylene derivative, a styryl derivative, etc. are mentioned. Specific examples of the heterocyclic ring in the heterocyclic group include thiophene, pyridine, pyrrole, carbazole, combinations thereof, and derivatives thereof.

When Ar _{1 to} Ar _{4 in} the general formula (1) have a substituent, the substituent is a linear or branched alkyl group or alkenyl group having 1 to 12 carbon atoms, such as a methyl group, an ethyl group, or a propyl group. Group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, vinyl group, allyl group Etc.

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

  In the hole transport layer of the present invention, it is possible to further improve the current efficiency, luminance, and device lifetime by further containing a hole transport polymer compound different from the charge transport compound having two or more aldehyde groups. It is preferable from the point.

  The film thickness of the hole transport layer varies depending on the material used, and may be selected so that the driving voltage and current efficiency are appropriate. However, at least a thickness that does not cause pinholes is required. On the other hand, if the thickness is too large, the drive voltage of the device may increase, which is not preferable. Therefore, the film thickness of the hole transport layer is 1-1000 nm, preferably 2 nm-500 nm, more preferably 5 nm-200 nm.

  A light emitting layer dopant, which will be described later, may be added to the hole transport layer. In this case, the hole transport layer functions as a host material for the light emitting layer dopant and can also transport holes to a normal light emitting layer. The hole transport layer may be composed of two or more layers, and the first hole transport layer is formed only with the hole transport compound, and adjacent to the first hole transport layer, for example, the same You may form the 2nd positive hole transport layer which added the dopant to the positive hole transport compound.

(3) Light emitting layer The material used for the light emitting layer of the present invention is not particularly limited as long as it is a material usually used as a light emitting material. In addition to organic light emitting materials, inorganic light emitting materials such as quantum dots are used. It may be a material.
As the organic light emitting material, either a fluorescent material or a phosphorescent material can be used. Specifically, materials such as a dye-based light emitting material and a metal complex-based light emitting material can be given, and either a low molecular compound or a high molecular compound can be used.
When the light emitting layer is used as the charge transporting organic layer of the present invention, an organic light emitting material is suitably used as the charge transporting compound capable of introducing an aldehyde group.

[Specific examples of dye-based luminescent materials]
Examples of the dye-based luminescent material include arylamine derivatives, anthracene derivatives, oxadiazole derivatives, oxazole derivatives, oligothiophene derivatives, carbazole derivatives, cyclopentadiene derivatives, silole derivatives, distyrylbenzene derivatives, distyrylpyrazine derivatives, di Styrylarylene derivatives, silole derivatives, stilbene derivatives, spiro compounds, thiophene ring compounds, tetraphenylbutadiene derivatives, triazole derivatives, triphenylamine derivatives, trifumanylamine derivatives, pyrazoloquinoline derivatives, hydrazone derivatives, pyrazoline derivatives, pyridine ring compounds, Fluorene derivatives, phenanthroline derivatives, perinone derivatives, perylene derivatives, and the like can be given. These dimers, trimers, oligomers, and compounds of two or more derivatives can also be used.
These materials may be used alone or in combination of two or more.

[Specific examples of metal complex-based luminescent materials]
Examples of metal complex light emitting materials include aluminum quinolinol complex, benzoquinolinol beryllium complex, benzoxazole zinc complex, benzothiazole zinc complex, azomethylzinc complex, porphyrin zinc complex, europium complex, etc., or central metal such as Al, Zn, Be, etc. Alternatively, a metal complex having a rare earth metal such as Tb, Eu, or Dy and having a oxadiazole, thiadiazole, phenylpyridine, phenylbenzimidazole, quinoline structure, or the like as a ligand can be given.
These materials may be used alone or in combination of two or more.

[Specific examples of polymer light-emitting materials]
As the high molecular weight light emitting material, a material obtained by introducing the above low molecular weight material into the molecule as a straight chain, a side chain or a functional group, a polymer, a dendrimer, or the like can be used.
Examples thereof include polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyvinyl carbazole, polyfluorenone derivatives, polyfluorene derivatives, polyquinoxaline derivatives, and copolymers thereof.

[Specific examples of dopant]
A doping material may be added to the light emitting layer for the purpose of improving the light emission efficiency or changing the light emission wavelength. In the case of a polymer material, these may be included as a light emitting group in the molecular structure. Examples of such doping materials include perylene derivatives, coumarin derivatives, rubrene derivatives, quinacdrine derivatives, squalium derivatives, porphyrin derivatives, styryl dyes, tetracene derivatives, pyrazoline derivatives, decacyclene, phenoxazone, quinoxaline derivatives, carbazole derivatives, and fluorene derivatives. Can be mentioned. Moreover, the compound which introduce | transduced the spiro group into these can also be used.
These materials may be used alone or in combination of two or more.
As a phosphorescent dopant, an organometallic complex having heavy metal ions such as platinum and iridium as a center and exhibiting phosphorescence can be used. Specifically, Ir (ppy) ₃ , (ppy) ₂ Ir (acac), Ir (BQ) ₃ , (BQ) ₂ Ir (acac), Ir (THP) ₃ , (THP) ₂ Ir (acac), Ir (BO) ₃ , (BO) ₂ (acac), Ir (BT) ₃ , (BT) ₂ Ir (acac), Ir (BTP) ₃ , (BTP) ₂ Ir (acac), FIr6, PtOEP, or the like is used. be able to. These materials may be used alone or in combination of two or more.
In the light emitting layer of the present invention, a plurality of light emitting layer dopants may be added to one light emitting layer.

  On the other hand, when quantum dots are used as the light emitting material, quantum dots protected by a protective material and a binder component having a binding action for forming a light emitting layer are used. The binder component may be selected from organic binder materials such as a light emitting layer host material and a charge transport material that have been conventionally used in organic EL devices. Examples of the binder material of the light emitting layer used as the light emitting layer host material in the organic EL include the dye light emitting material, the metal complex light emitting material, and the polymer light emitting material. Examples of the charge transport material include the above hole transport compounds.

[Quantum dots]
Quantum dots are nanometer-sized fine particles of semiconductors that have specific optical and electrical properties due to the quantum confinement effect (quantum size effect) in which electrons and excitons are confined in small crystals of nanometer size. It exhibits properties and is also called a semiconductor nanoparticle or a semiconductor nanocrystal.
The quantum dot is a semiconductor nanometer-sized fine particle and is not particularly limited as long as it is a material that produces a quantum confinement effect (quantum size effect). For example, as described above, there are semiconductor fine particles whose emission color is regulated by their own particle size and semiconductor fine particles having a dopant.

  The quantum dot may be composed of one kind of semiconductor compound or may be composed of two or more kinds of semiconductor compounds, for example, a core made of a semiconductor compound and a shell made of a semiconductor compound different from the core. It may have a core-shell type structure. As a typical example, a core made of CdSe, a ZnS shell provided around the core, and a protective material (also referred to as a capping material) provided around the core can be exemplified. The quantum dots have different emission colors depending on their particle diameters. For example, in the case of quantum dots composed only of a core made of CdSe, the particle diameters are 2.3 nm, 3.0 nm, 3.8 nm, The peak wavelengths of the fluorescence spectrum at 4.6 nm are 528 nm, 570 nm, 592 nm, and 637 nm.

  Specifically, the core material of the quantum dot includes MgS, MgSe, MgTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS II-VI group semiconductor compounds such as HgSe and HgTe, III- such as AlN, AlP, AlAs, AlSb, GaAs, GaP, GaN, GaSb, InN, InAs, InP, InSb, TiN, TiP, TiAs and TiSb Examples thereof include semiconductor compounds such as Group V semiconductor compounds, Group IV semiconductors such as Si, Ge and Pb, or semiconductor crystals containing semiconductors. Alternatively, a semiconductor crystal including a semiconductor compound containing three or more elements such as InGaP can be used.

Furthermore, as a quantum dot composed of semiconductor fine particles having a dopant, a semiconductor crystal obtained by doping the semiconductor compound with a rare earth metal cation or a transition metal cation such as Eu ³⁺ , Tb ³⁺ , Ag ⁺ , or Cu ⁺ is used. It can also be used.

  Among these, semiconductor crystals such as CdS, CdSe, CdTe, InP, and InGaP are preferable from the viewpoints of ease of fabrication, controllability of the particle size for obtaining light emission in the visible range, and fluorescence quantum yield.

When a core-shell quantum dot is used, the semiconductor that constitutes the shell uses a material with a higher band gap than the semiconductor compound that forms the core so that excitons are confined in the core. Can be increased.
Examples of the core-shell structure (core / shell) having such a bandgap relationship include CdSe / ZnS, CdSe / ZnSe, CdSe / CdS, CdTe / CdS, InP / ZnS, Gap / ZnS, Si / ZnS, Examples include InN / GaN, InP / CdSSe, InP / ZnSeTe, InGaP / ZnSe, InGaP / ZnS, Si / AlP, InP / ZnSTe, InGaP / ZnSTe, and InGaP / ZnSSe.

  The size of the quantum dot may be appropriately controlled depending on the material constituting the quantum dot so that light having a desired wavelength can be obtained. As the particle size of the quantum dot decreases, the energy band gap increases. That is, as the crystal size decreases, the light emission of the quantum dots shifts to the blue side, that is, to the high energy side. Therefore, by changing the size of the quantum dot, the emission wavelength can be adjusted over the entire wavelength range of the ultraviolet region, the visible region, and the infrared region.

  In general, the particle size (diameter) of the quantum dots is preferably in the range of 0.5 to 20 nm, and particularly preferably in the range of 1 to 10 nm. The narrower the quantum dot size distribution, the clearer the emission color.

  The shape of the quantum dot is not particularly limited, and may be, for example, a spherical shape, a rod shape, a disk shape, or other shapes. When the particle dot is not spherical, the particle size of the quantum dot can be a true spherical value having the same volume.

  Information such as the particle size, shape, and dispersion state of the quantum dots can be obtained by a transmission electron microscope (TEM). The crystal structure and particle size of the quantum dots can be known by X-ray crystal diffraction (XRD). Furthermore, the information regarding the particle size and surface of a quantum dot can also be obtained by an ultraviolet-visible (UV-Vis) absorption spectrum.

[Quantum dot (QD) protective material]
In order to protect the quantum dots and disperse them in the binder component that is an organic compound, it is preferable to dispose a QD protective material on the surface of the quantum dots. The QD protective material for the protective material preferably has, as part of its chemical structure, a linking group capable of linking with QD and a charge transporting compound. In such a case, the compatibility of the binder component contained in the light emitting layer and the QD protective material is improved, the QD protected by the protective material is uniformly dispersed, and the charge transportability is not hindered. Is preferable from the viewpoint that a long driving life and good color purity can be achieved.

  The linking group capable of linking with QD is a group containing at least an oxygen atom (O) and a halogen atom, a group containing at least a nitrogen atom (N), or a group containing at least a sulfur atom (S). Specific examples include groups selected from the group consisting of the following chemical formulas (Y-1) to (Y-9).

In formulas (Y-1) to (Y-9), Z ₁ , Z ₂ and Z ₃ each independently represent a halogen atom or an alkoxy group, and a chlorine atom, a methoxy group or an ethoxy group is particularly preferable. These linking groups Y are usually linked to the surface of QD by linking to a reactive functional group (in many cases, a hydroxyl group) present on the surface of QD.

  In addition to the above hole transporting compound, the charge transporting compound can be appropriately selected from electron transporting compounds described later.

  As a QD protection method using the QD protective material, a QD dispersion liquid protected with a conventional protective material mainly composed of an alkyl chain such as TOPO contains a linking group capable of linking with QD and a charge transporting compound. From the point that QD can be efficiently protected by adding a QD protective material, stirring for a certain period of time, replacing the protective material mainly composed of the alkyl chain with a QD protective material containing the charge transporting compound, and protecting it. preferable. However, the method for preparing the QD light-emitting material is not limited to the above, and when the QD is crystal-grown in the liquid phase without substitution, the protective material is used as a dispersant to coordinate with the QD surface. , May be obtained by reaction.

The thickness of the light emitting layer is more preferably 0.1 to 1000 nm, particularly 10 to 100 nm because pinhole defects in the light emitting layer can be suppressed while suppressing the driving voltage.
The light emitting layer can be formed by a solution coating method or a transfer method using a light emitting material.

The light-emitting layer can be formed by a wet film formation method using a light-emitting material because the hole transport layer serving as a lower layer has high solvent resistance. The wet film forming method will be described in detail in the item of the device manufacturing method described later. The light emitting layer may be produced by a vapor deposition method or a transfer method. For example, in the case of the vacuum evaporation method, the material of the light emitting layer is put in a crucible installed in a vacuum vessel, and the inside of the vacuum vessel is evacuated to about 10 ⁻⁴ Pa by an appropriate vacuum pump, and then the crucible. Is heated to evaporate the material of the light-emitting layer, and a light-emitting layer is formed on the laminate of the substrate, the first electrode layer, and the hole transport layer placed facing the crucible. In the transfer method, for example, a light emitting layer previously formed on a film by a wet film forming method or a vapor deposition method is bonded onto a hole transport layer provided on the first electrode layer, and the light emitting layer is heated to form a hole transport layer. It is formed by transferring it upward.

  The light emitting layer used in the present invention may include both an organic light emitting layer and a light emitting layer containing the quantum dots. In such a case, for example, the organic light emitting layer has a blue light emitting material, and the light emitting layer containing quantum dots has a quantum dot emitting green light and a quantum dot emitting red light as a PL light emitting material. A white light-emitting element can be easily produced by adjusting the amount.

  In the light emitting layer of the present invention, one device may have a plurality of light emitting layers. The plurality of light emitting layers may be the same or different. In the case of having a plurality of light emitting layers, the light emitting layers may be adjacent to each other, or a hole transport layer, a hole block layer, an electron block layer, and / or an electron transport layer may be formed between the light emitting layers. Good.

(4) Hole injection layer As a hole injection layer, a conventionally well-known material can be used suitably. When the hole injection layer is used as the charge transporting organic layer of the present invention, examples of the charge transporting compound capable of introducing an aldehyde group include pyrrole derivatives, carbazole derivatives, indole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline. Derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives, phthalocyanine derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic Examples include, but are not limited to, group dimethylidin compounds, porphyrin compounds, and organic silane derivatives. These dimers, trimers, oligomers, and compounds of two or more derivatives can also be used.
Examples of the hole injecting polymer compound include, but are not limited to, a polymer containing the above derivative and the like in a repeating unit.

(5) Electron Blocking Layer Conventionally known materials can be appropriately used as the electron blocking layer. When the electron blocking layer is used as the charge transporting organic layer of the present invention, examples of the charge transporting compound capable of introducing an aldehyde group include arylamine derivatives, anthracene derivatives, carbazole derivatives, thiophene derivatives, fluorene derivatives, distyrylbenzene. Examples thereof include, but are not limited to, derivatives and spiro compounds. These dimers, trimers, oligomers, and compounds of two or more derivatives can also be used.
Examples of the electron block polymer compound include, but are not limited to, a polymer containing the above derivative and the like in a repeating unit.

(6) Hole blocking layer As a hole blocking layer, a conventionally well-known material can be used suitably. When the hole blocking layer is used as the charge transporting organic layer of the present invention, examples of the charge transporting compound capable of introducing an aldehyde group include arylamine derivatives, anthracene derivatives, oxadiazole derivatives, oxazole derivatives, oligothiophenes. Derivatives, carbazole derivatives, cyclopentadiene derivatives, silole derivatives, distyrylbenzene derivatives, distyrylpyrazine derivatives, distyrylarylene derivatives, silole derivatives, stilbene derivatives, spiro compounds, thiophene ring compounds, tetraphenylbutadiene derivatives, triazole derivatives, triphenyl Amine derivatives, trifumanylamine derivatives, pyrazoloquinoline derivatives, hydrazone derivatives, pyrazoline derivatives, pyridine derivatives, fluorene derivatives, phenanthroline derivatives, peri Emissions derivatives, perylene derivatives, and the like, but not limited thereto. These dimers, trimers, oligomers, and compounds of two or more derivatives can also be used.
Examples of the hole-blocking polymer compound include, but are not limited to, polymers containing the above derivatives and the like in repeating units.

(7) Electron Transport Layer As the electron transport layer, conventionally known materials can be used as appropriate. When the electron transport layer is used as the charge transport organic layer of the present invention, examples of the charge transport compound capable of introducing an aldehyde group include quinoline derivatives, perylene derivatives, bisstyryl derivatives, pyrazine derivatives, triazole derivatives, oxazole derivatives, Examples include, but are not limited to, oxadiazole derivatives and fluorenone derivatives. These dimers, trimers, oligomers, and compounds of two or more derivatives can also be used.
Examples of the electron transporting polymer compound include, but are not limited to, a polymer containing the above derivative and the like in a repeating unit.

  The aforementioned light emitting layer dopant may be added to the electron transport layer. In this case, the electron transport layer functions as a host material for the light emitting layer dopant and can also transport electrons to a normal light emitting layer. The electron transport layer may be composed of two or more layers. The first electron transport layer is formed only with the electron transport compound, and adjacent to the first electron transport layer, for example, the same electron transport property. You may form the 2nd electron carrying layer which added the dopant to the compound.

(8) Electron injection layer A conventionally well-known material can be used suitably as an electron injection layer. When the electron injection layer is used as the charge transporting organic layer of the present invention, the charge transporting compound capable of introducing an aldehyde group may have, for example, a property of reducing an organic compound with an electron donating property, A reducing organic compound containing an alkali metal such as Li, an alkaline earth metal such as Mg, or a rare earth metal can be given. Examples of the reducing organic compound include nitrogen-containing compounds, sulfur-containing compounds, and phosphorus-containing compounds, and specific examples include quinoline derivatives such as lithium quinoline (Liq), but are not limited thereto. Absent.
As the metal contained in the reducing organic compound, a metal having a work function of 4.2 eV or less can be preferably used. Specifically, Li, Na, K, Be, Mg, Ca, Sr, Ba, Y, Examples include Cs, La, Sm, Gd, and Yb.
Further, examples of the electron injecting polymer compound include polymers containing poly (9,9-bis () having repeating units such as alkali metals such as Li, alkaline earth metals such as Mg, or reducing organic compounds containing rare earth metals. 6'-diethanolaminohexyl) fluorene] and the like.

2. Substrate The substrate serves as a support for the device of the present invention. For example, the substrate may be a flexible material or a hard material. Specific examples of materials that can be used include glass, quartz, polyethylene, polypropylene, polyethylene terephthalate, polymethacrylate, polymethyl methacrylate, polymethyl acrylate, polyester, and polycarbonate.
Among these, when using a synthetic resin substrate, it is desirable to have a gas barrier property. Although the thickness of a board | substrate is not specifically limited, Usually, it is about 0.5-2.0 mm.

3. Electrodes The device of the present invention has two or more electrodes facing each other on a substrate.
In the device of the present invention, the electrode is preferably formed of a metal or a metal oxide. For example, platinum, gold, silver, nickel, chromium, copper, iron, tin, antimony lead, tantalum, indium, palladium, Tellurium, rhenium, iridium, aluminum, ruthenium, germanium, molybdenum, tungsten, tin oxide / antimony, indium tin oxide (ITO), fluorine-doped zinc oxide, zinc, carbon, graphite, glassy carbon, silver paste and carbon paste, lithium , Beryllium, sodium, magnesium, potassium, calcium, scandium, titanium, manganese, zirconium, gallium, niobium, sodium, sodium-potassium alloy, magnesium, lithium, aluminum, magnesium / copper mixture A magnesium / silver mixture, a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide mixture, a lithium / aluminum mixture, etc. are used, but usually metals such as aluminum, gold, silver, nickel, palladium, platinum, indium and And / or a metal oxide such as an oxide of tin.

Usually, the electrode is often formed on the substrate by a method such as a sputtering method or a vacuum deposition method, but can also be formed by a wet method such as a coating method or a dipping method. The thickness of the electrode varies depending on the transparency required for each electrode. When transparency is required, the light transmittance in the visible light wavelength region of the electrode is usually 60% or more, preferably 80% or more. In this case, the thickness is usually 10 to 1000 nm, Preferably, it is about 20 to 500 nm.
Moreover, you may have a metal layer further on the electrode. The metal layer refers to a layer containing a metal, and is formed from a metal or metal oxide used for the above-described normal electrode.

4). Others The device of the present invention may have a conventionally known configuration as appropriate according to the embodiment.
The organic thin-film solar cell, the dye-sensitized solar cell, the organic transistor, the organic light-emitting diode, etc. are not particularly limited as long as they have the charge transporting organic layer specified in the present invention, and are appropriately known. The configuration may be the same. Moreover, it is not restricted to the charge transporting compound illustrated above, In addition, two or more aldehyde groups are added to conventionally known charge transporting compounds used for organic thin film solar cells, dye-sensitized solar cells, organic transistors, and organic light emitting diodes. The charge transporting organic layer specified in the present invention may be formed by introducing the charge transporting compound having two or more aldehyde groups.

2. Device manufacturing method A device manufacturing method according to the present invention is a device manufacturing method comprising two or more electrodes facing each other on a substrate and an organic layer disposed between the two electrodes.
A step of preparing a charge transporting organic layer forming ink containing a charge transporting compound having two or more aldehyde groups and an organic transition metal complex;
Using the charge transporting organic layer forming ink to form a charge transporting organic layer coating film on any layer on the electrode;
A charge transporting organic layer is formed by reacting a charge transporting compound having two or more aldehyde groups in the coating film for charge transporting organic layer with the organic transition metal complex to produce a reaction product. And a step of performing.

  As described above, according to the present invention, the step of preparing the charge transporting organic layer forming ink, the step of forming the coating film for charge transporting organic layer, and the reaction product are generated to generate the charge transport. The step of forming a conductive organic layer can increase the solvent resistance of the charge transportable organic layer while forming the charge transportable organic layer by a wet film formation method. As a result, for example, a light emitting layer can be formed by a wet film forming method adjacent to the hole transport layer which is the charge transporting organic layer of the present invention, and multilayering by a wet film forming method is possible. is there. When multilayering is possible by a wet film forming method, a vapor deposition apparatus is not required for forming each layer, and coating can be performed separately without using mask vapor deposition or the like, resulting in high productivity. Furthermore, according to the production method of the present invention, a charge transporting organic layer having high solvent resistance can be obtained. Therefore, as described in the device of the present invention, a device with improved brightness, current efficiency, and element lifetime can be obtained. Can be obtained.

(1) Step of preparing charge transporting organic layer forming ink The charge transporting organic layer forming ink used in the present invention is a mixture of a charge transporting compound having at least two aldehyde groups and an organic transition metal complex. Prepared. Preferably, a charge transporting organic layer forming ink is prepared by dissolving or dispersing a charge transporting compound having at least two aldehyde groups and an organic transition metal complex in an organic solvent.
The charge transporting organic layer forming ink used in the present invention may further contain other compounds as necessary. The other compound is a component that may be contained in the above-described charge transporting organic layer, and is different from the charge transporting compound having two or more aldehyde groups, for example, Ingredients.

  As the organic solvent used in the ink, a charge transporting compound having two or more aldehyde groups, an organic transition metal complex, and other components contained as necessary can be dissolved or dispersed well, and the boiling point is from 50 ° C. to 50 ° C. What is 300 degreeC is used suitably. Examples of the organic solvent include chloroform solvents such as chloroform, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, chlorobenzene and o-dichlorobenzene, ether solvents such as tetrahydrofuran and dioxane, toluene, xylene and the like. Aromatic hydrocarbon solvents, cyclohexane, methylcyclohexane, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane and other aliphatic hydrocarbon solvents, acetone, methyl ethyl ketone, Ketone solvents such as cyclohexanone, ester solvents such as ethyl benzoate, butyl benzoate, ethyl acetate, butyl acetate, ethyl cellosolve acetate, ethylene glycol, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, ethylene glyco Polymethyl alcohol, dimethoxyethane, propylene glycol, diethoxymethane, triethylene glycol monoethyl ether, glycerin, polyhydric alcohols such as 1,2-hexanediol and derivatives thereof, methanol, ethanol, propanol, isopropanol, cyclohexanol, etc. Examples include alcohol solvents, sulfoxide solvents such as dimethyl sulfoxide, and amide solvents such as N-methyl-2-pyrrolidone and N, N-dimethylformamide. These organic solvents may be used alone or in combination. Among the solvents, it is preferable from the viewpoint of viscosity, film formability, and the like that one or more organic solvents having a melting point of 0 ° C. or lower and a boiling point of 100 ° C. or higher are included.

  In the ink for forming a charge transporting organic layer according to the present invention, the contents of the charge transporting compound having two or more aldehyde groups and the organic transition metal complex can be appropriately adjusted according to the purpose, and are particularly limited. However, for example, the organic transition metal complex is used in an amount of 1 to 500 parts by weight, preferably 10 to 200 parts by weight, based on 100 parts by weight of the charge transporting compound having two or more aldehyde groups. It is preferable from the viewpoint of improving the hole transportability while imparting, and having a high film stability and achieving a long life. The proportion of the organic solvent in the charge transporting organic layer forming ink is 1-1000 parts by weight, preferably 20-500 parts by weight, with respect to 1 part by weight of the solid content. In addition, solid content means all the components in the ink except a solvent.

(2) Step of forming a charge transporting organic layer coating film Method of forming a charge transporting organic layer coating film on any layer on the electrode using the charge transporting organic layer forming ink As a wet film forming method, for example, a liquid such as a dipping method, a spray coating method, a spin coating method, a blade coating method, a dip coating method, a casting method, a roll coating method, a bar coating method, a die coating method, or an ink jet method. Examples thereof include a dropping method.

(3) Step of forming charge transporting organic layer In this step, the charge transporting compound having two or more aldehyde groups in the coating film for charge transporting organic layer is reacted with the organic transition metal complex. By forming a reaction product, a charge transporting organic layer is formed from the coating film for charge transporting organic layer.
Examples of the method of reacting the charge transporting compound having two or more aldehyde groups in the coating film with the organic transition metal complex include heating, light irradiation, etc., but the deterioration of the charge transporting compound is prevented. Is preferably heated. In the drying step of removing the organic solvent from the coating film for charge transporting organic layer, the charge transporting compound having two or more aldehyde groups in the coating film may be reacted with the organic transition metal complex.

Examples of the heating means include a method of heating on a hot plate and a method of heating in an oven. As heating temperature, 50-250 degreeC is preferable.
In the case of light irradiation, examples of the light irradiation means include a method of exposing to ultraviolet rays.
Since there is a difference in the reactivity between the charge transporting compound having two or more aldehyde groups and the organic transition metal complex depending on the heating temperature and the amount of light irradiation, it is preferable to adjust appropriately.

  Conventionally known processes can be appropriately used for other processes in the device manufacturing method.

Hereinafter, the present invention will be described more specifically with reference to examples. These descriptions do not limit the present invention. In the examples, parts represent parts by weight unless otherwise specified. Moreover, the thickness of the layer or film | membrane is represented by the average film thickness.
The present invention will be described more specifically with reference to examples of organic EL elements. In addition, this invention is not limited to description of a following example.

<< Test Example 1 for Solvent Resistance of Charge Transporting Organic Layer >>
A comparative test regarding solvent resistance was performed using CBP represented by the following chemical formula, CBP having two aldehyde groups (CBP-ald), and molybdenum hexacarbonyl which is an organic molybdenum complex.

(Synthesis Example 1)
100 parts by weight of CBP (CBP-ald) having two aldehyde groups and 50 parts by weight of molybdenum hexacarbonyl are dissolved in cyclohexanone so that the solid content concentration is 1% by weight, and heated at 100 ° C. for 4 hours. Thus, a charge transporting organic layer forming ink 1 was prepared.

(Comparative Synthesis Example 1)
In Comparative Example 1, a comparative ink 1 for forming a charge transporting organic layer was prepared in the same manner as in Synthetic Example 1, except that CBP having no aldehyde group was used instead of CBP having two aldehyde groups (CBP-ald). Was prepared.
(Comparative Synthesis Example 2)
In Synthesis Example 1, a comparative ink 2 for forming a charge transporting organic layer was prepared without using molybdenum hexacarbonyl.
(Comparative Synthesis Example 3)
In Synthesis Example 1, instead of CBP having two aldehyde groups (CBP-ald), a comparative ink for forming a charge transporting organic layer using CBP having no aldehyde group and not using molybdenum hexacarbonyl 3 was prepared.

The ink of Synthesis Example 1 and Comparative Inks 1 to 3 of Comparative Synthesis Examples 1 to 3 were each spin-coated on a quartz substrate and heated at 200 ° C. for 60 minutes in a nitrogen atmosphere to form a thin film. Each formed thin film was observed for the presence or absence of aggregation. Moreover, about each formed thin film, it wiped off with toluene using the wiping implement ruby stick (flat cutting) H-20 (brand name; product made by Rib Du Corporation), and evaluated whether it was insolubilized in the organic solvent. . The results are shown in Table 1.
[Evaluation criteria for insolubilization]
○: Can not be wiped △: Can be partially wiped ×: Can be wiped completely

  From the results in Table 1, CBP having two or more aldehyde groups reacts with molybdenum hexacarbonyl, which is an organic transition metal complex, to form a uniform film without agglomeration, despite being a low-molecular compound. I found out that It was also found that CBP having two or more aldehyde groups is insolubilized in an organic solvent by reacting with molybdenum hexacarbonyl, which is an organic transition metal complex.

<< Test Example 2 for Solvent Resistance of Charge Transporting Organic Layer >>
CBP (CBP-ald) having two aldehyde groups represented by the above chemical formula, triphenylamine (TPA-ald) having two aldehyde groups represented by the following chemical formula, and molybdenum hexacarbonyl which is an organic molybdenum complex A hole transporting polymer compound (poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- (4,4 ′-(N- (4-sec-butylphenyl) ) Diphenylamine)] (TFB) or poly (N-vinylcarbazole) (PVK)) was subjected to a comparative test regarding solvent resistance.

(Synthesis Example 2)
100 parts by weight of poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- (4,4 ′-(N- (4-sec-butylphenyl)) diphenylamine)] (TFB); 80 parts by weight of CBP (CBP-ald) having two aldehyde groups and 40 parts by weight of molybdenum hexacarbonyl were dissolved in xylene so that the solid content concentration would be 1% by weight, and heated at 100 ° C. for 4 hours. Thus, a charge transporting organic layer forming ink 2 was prepared.

(Synthesis Example 3)
100 parts by weight of poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- (4,4 ′-(N- (4-sec-butylphenyl)) diphenylamine)] (TFB); 80 parts by weight of triphenylamine (TPA-ald) having two aldehyde groups and 40 parts by weight of molybdenum hexacarbonyl were dissolved in xylene so that the solid content concentration would be 1% by weight, and then at 100 ° C. for 4 hours. By heating, an ink 3 for forming a charge transporting organic layer was prepared.

(Comparative Synthesis Example 4)
In Synthesis Example 2, a comparative ink 4 for forming a charge transporting organic layer was prepared without using molybdenum hexacarbonyl.

(Comparative Synthesis Example 5)
In Comparative Synthesis Example 3, poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- (4,4 ′-(N- (4-sec-butylphenyl)) diphenylamine)] (TFB ) Was used instead of poly (N-vinylcarbazole) (PVK), and cyclopentanone was used instead of xylene to prepare a comparative ink 5 for forming a charge transporting organic layer.

Each of the inks of Synthesis Examples 2 to 3 and Comparative inks 4 to 5 of Comparative Synthesis Examples 4 to 5 were spin-coated on a quartz substrate and heated in a nitrogen atmosphere at 200 ° C. for 60 minutes to form a thin film.
Toluene was dropped on each formed thin film and allowed to stand for 10 seconds, and then each thin film was rinsed by spin coating at 1000 rpm for 10 seconds.
The thin film reduction rate before and after rinsing was evaluated using two methods: a film thickness difference with a desktop small probe microscope, and a spectral intensity difference in UV-Vis spectrum measurement. The results are shown in Table 2.

<Measurement conditions of desktop compact probe microscope>
Measure the film thickness before and after rinsing with a desktop small probe microscope (equipment: Nanopics, manufactured by SII NanoTechnology Co., Ltd.), determine the film thickness difference (film thickness before rinsing-film thickness after rinsing), and thin film Reduction rate [(film thickness difference / film thickness before rinsing) × 100] was calculated.

<Measurement conditions of UV-Vis spectrum>
The absorption spectrum of the thin film before and after rinsing was measured by UV-Vis spectrum measurement (apparatus: Shimadzu Corporation UV-3100PC), and the inks of Synthesis Examples 2 to 3 and Comparative Ink 4 of Comparative Synthesis Example 4 were measured. Difference in peak intensity seen at 390 nm derived from TFB (peak intensity before rinsing−peak intensity after rinsing), difference in peak intensity seen at 300 nm derived from PVK contained in Comparative Ink 5 of Comparative Synthesis Example 5 The thin film reduction rate [(peak intensity difference / peak intensity before rinsing) × 100] was calculated.

  Comparing the results of Synthesis Examples 2 and 3 with Comparative Synthesis Example 4, the thin film containing a reaction product of a charge transporting compound having two or more aldehyde groups and an organic transition metal complex has significantly improved solvent resistance. It was revealed that In addition, compared with Comparative Synthesis Example 5 using PVK, which has been considered to have high solvent resistance in toluene, a charge transporting compound having two or more aldehyde groups of Synthesis Examples 2 and 3 and an organic transition metal complex It has been clarified that the thin film containing the reaction product with the above has improved solvent resistance.

≪Fourier transform infrared spectroscopic measurement of reaction products≫
The Fourier transform infrared spectroscopic measurement of the reaction product of the charge transporting compound having two or more aldehyde groups and the organic transition metal complex was performed. Hole transport by dissolving 100 parts by weight of 4,4′-diformyltriphenylamine (TPA-ald) and 50 parts by weight of molybdenum hexacarbonyl in xylene so that the solid concentration is 1% by weight. A layer ink was formed, the ink was spin-coated on a quartz substrate, and heated at 200 ° C. for 60 minutes in a nitrogen atmosphere to form a thin film. The thin film was shaved with a cutter to prepare a sample, and the sample was subjected to FT-IR measurement (apparatus: manufactured by JASCO Corporation, FT / IR-600). The FT-IR measurement results are shown in FIG.

FIG. 6 also shows the result of FT-IR measurement of a thin film formed in the same manner using only 4,4′-diformyltriphenylamine (TPA-ald), and the benzene ring seen in the vicinity of 1500 cm ^−1. The change in the peak of the reaction product was observed by normalizing with the peak derived from the origin.
Looking at the peak of the reaction product in FIG. 6, a decrease in the aldehyde-derived C—H bending angle peak observed near 1390 cm ⁻¹ , a decrease in the aldehyde-derived C═O stretching peak observed near 1700 cm ⁻¹ , 2700 cm. A decrease in the aldehyde-derived C—H stretching peak observed in the vicinity of ⁻¹ is observed, and the reaction product is considered to have lost the aldehyde by the reaction. In addition, a peak derived from aliphatic C—H stretching is newly observed in the vicinity of 2900 cm ^{−1 in} the peak of the reaction product, and it is estimated that a new bond is formed.

≪Light-emitting device characteristics experiment 1≫
[Reference Example 1]
A transparent anode, hole injection layer, hole transport layer, light-emitting layer, hole blocking layer, electron transport layer, electron injection layer, and cathode are deposited and laminated in this order on a glass substrate, and finally sealed. Thus, an organic EL element was produced.

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

  Next, a PEDOT-PSS solution (Bytron P AI4083 manufactured by Bayer) was formed on the ITO substrate as a hole injection layer by spin coating so that the film thickness after drying was 30 nm. After application of the PEDOT-PSS solution, a hole injection layer was formed by drying at 200 ° C. for 30 minutes using a hot plate to evaporate the solvent. The formation and drying steps of the hole injection transport layer described above were all performed in the atmosphere.

  Next, the charge transporting organic layer forming ink 2 prepared in Synthesis Example 2 as a hole transport layer is formed on the prepared hole injection layer so that the film thickness after drying by spin coating is 20 nm. Formed. After the application of the charge transporting organic layer forming ink 2, it was dried at 200 ° C. for 60 minutes using a hot plate in order to evaporate the solvent, thereby forming a hole transporting layer. The formation of the hole transport layer by coating and the drying step were performed in a nitrogen-substituted glove box having a moisture concentration of 0.1 ppm or less and an oxygen concentration of 0.1 ppm or less.

  Next, on the hole transport layer, tris [2- (p-tolyl) pyridine)] iridium (III) (Ir (mppy) 3) is contained as a light emitting dopant as a light emitting layer, and 4,4 ′ A light emitting layer forming ink containing —N, N′-dicarbazole-biphenyl (CBP) as a host was formed by spin coating so as to have a film thickness of 30 nm. The ink for forming the light emitting layer was prepared by dissolving in toluene so that the weight ratio of CBP as a host and Ir (mppy) 3 as a dopant was 20: 1. The formation and drying steps by application of the light emitting layer were performed in a nitrogen-substituted glove box having a water concentration of 0.1 ppm or less and an oxygen concentration of 0.1 ppm or less.

A hole blocking layer was formed on the light emitting layer by vapor deposition. The hole blocking layer uses bis (2-methyl-8-quinolato) (p-phenylphenolate) aluminum complex (BAlq) as a forming material, and is formed in vacuum (pressure: 1 × 10 ⁻⁴ Pa) by resistance heating vapor deposition. ) To form a BAlq vapor-deposited film having a thickness of 15 nm.
An electron transport layer was deposited on the hole blocking layer. The electron transport layer was formed by vapor deposition of tris (8-quinolinolato) aluminum complex (Alq3) in a vacuum (pressure: 1 × 10 ⁻⁴ Pa) by resistance heating vapor deposition so that the film thickness of the Alq3 vapor deposition film becomes 15 nm. .

An electron injection layer and a cathode were successively deposited on the electron transport layer of the produced glass substrate with a transparent anode / hole injection transport layer / hole transport layer / light emitting layer / hole block layer / electron transport layer. The electron injection layer was formed of LiF (thickness: 0.5 nm), and the cathode was formed of Al (thickness: 100 nm) in order by resistance heating vapor deposition in vacuum (pressure: 1 × 10 ⁻⁴ Pa).
After forming the cathode, the organic EL element of Reference Example 1 was produced by sealing with a non-alkali glass and a UV curable epoxy adhesive in a glove box.

[Reference Example 2]
In Reference Example 1, instead of using the charge transporting organic layer forming ink 2 as the charge transporting organic layer forming ink, the charge transporting organic layer forming ink 3 obtained in Synthesis Example 3 was used to form holes. A device was fabricated in the same manner as in Reference Example 1 except that the transport layer was formed.

[Example 3]
A charge transporting organic layer forming ink 4 was prepared in the same manner as in Synthesis Example 3 except that cobalt (III) acetylacetonate was used instead of molybdenum hexacarbonyl in Synthesis Example 3.
In Reference Example 1, instead of using the charge transporting organic layer forming ink 2 as the charge transporting organic layer forming ink, the hole transporting layer using the charge transporting organic layer forming ink 4 obtained above was used. A device was fabricated in the same manner as in Reference Example 1 except that was formed.

[Example 4]
A charge transporting organic layer forming ink 5 was prepared in the same manner as in Synthesis Example 3 except that platinum (II) acetylacetonate was used instead of molybdenum hexacarbonyl in Synthesis Example 3.
In Reference Example 1, instead of using the charge transporting organic layer forming ink 2 as the charge transporting organic layer forming ink, the hole transporting layer using the charge transporting organic layer forming ink 5 obtained above was used. A device was fabricated in the same manner as in Reference Example 1 except that was formed.

[Example 5]
A charge transporting organic layer forming ink 6 was prepared in the same manner as in Synthesis Example 3 except that vanadium (V) oxytriisopropoxide was used instead of molybdenum hexacarbonyl in Synthesis Example 3.
In Reference Example 1, instead of using the charge transporting organic layer forming ink 2 as the charge transporting organic layer forming ink, the hole transporting layer using the charge transporting organic layer forming ink 6 obtained above was used. A device was fabricated in the same manner as in Reference Example 1 except that was formed.

[Example 6]
A charge transporting organic layer forming ink 7 was prepared in the same manner as in Synthesis Example 3, except that iron (II) acetylacetonate was used instead of molybdenum hexacarbonyl in Synthesis Example 3.
In Reference Example 1, instead of using the charge transporting organic layer forming ink 2 as the charge transporting organic layer forming ink, the hole transporting layer using the charge transporting organic layer forming ink 7 obtained above was used. A device was fabricated in the same manner as in Reference Example 1 except that was formed.

[Example 7]
A charge transporting organic layer forming ink 8 was prepared in the same manner as in Synthesis Example 3 except that zinc acetylacetonate hydrate was used instead of molybdenum hexacarbonyl in Synthesis Example 3.
In Reference Example 1, instead of using the charge transporting organic layer forming ink 2 as the charge transporting organic layer forming ink, the hole transporting layer using the charge transporting organic layer forming ink 8 obtained above was used. A device was fabricated in the same manner as in Reference Example 1 except that was formed.

[Example 8]
A charge transporting organic layer forming ink 9 was prepared in the same manner as in Synthesis Example 3, except that chromium (III) acetylacetonate was used instead of molybdenum hexacarbonyl in Synthesis Example 3.
In Reference Example 1, instead of using the charge transporting organic layer forming ink 2 as the charge transporting organic layer forming ink, the hole transporting layer using the charge transporting organic layer forming ink 9 obtained above was used. A device was fabricated in the same manner as in Reference Example 1 except that was formed.

[Example 9]
A charge transporting organic layer forming ink 10 was prepared in the same manner as in Synthesis Example 3 except that pentacarbonylchlororhenium (I) was used instead of molybdenum hexacarbonyl in Synthesis Example 3.
In Reference Example 1, instead of using the charge transporting organic layer forming ink 2 as the charge transporting organic layer forming ink, the hole transporting layer using the charge transporting organic layer forming ink 10 obtained above was used. A device was fabricated in the same manner as in Reference Example 1 except that was formed.

[Comparative Example 1]
In Example 1, instead of using the charge transporting organic layer forming ink 2 as the charge transporting organic layer forming ink, the charge transporting organic layer forming comparative ink 4 obtained in Comparative Synthesis Example 4 was used. A device was fabricated in the same manner as in Reference Example 1 except that a hole transport layer was formed.

[Comparative Example 2]
In Example 1, instead of using the charge transporting organic layer forming ink 2 as the charge transporting organic layer forming ink, the charge transporting organic layer forming comparative ink 5 obtained in Comparative Synthesis Example 5 was used. A device was fabricated in the same manner as in Reference Example 1 except that a hole transport layer was formed.

[Comparative Example 3]
A device was fabricated in the same manner as in Reference Example 1 except that the hole transport layer was not formed in Reference Example 1.

[Comparative Example 4]
In Reference Example 1, instead of using the charge transporting organic layer forming ink 2 as the hole transporting layer, α represented by the following chemical formula is disclosed in Patent Document 3 (Japanese Patent Laid-Open No. 2006-253663). vacuum by the MoO ₃ 30% doped with a resistance heating evaporation method NPD: film thickness was vapor deposited so as to 30nm in (pressure 1 × ¹⁰ -4 Pa). A device was fabricated in the same manner as in Reference Example 1 except that the hole transport layer was formed by vapor deposition.

Each element obtained in Reference Examples 1 and 2, Examples 3 to 9, and Comparative Examples 1 to 4 was driven at 10 mA / cm ² , and the emission luminance and spectrum were measured by a spectral radiometer SR-2 manufactured by Topcon Corporation. Was measured. The organic EL elements produced in the above examples and comparative examples all emitted green light derived from Ir (mppy) ₃ . Table 3 shows the measurement results. The current efficiency was calculated from the drive current and the luminance.
The lifetime characteristics of the organic EL element were evaluated by observing the luminance gradually decreasing with time by constant current driving. Here, the time (hr.) Until the holding ratio deteriorates to a luminance of 50% with respect to the initial brightness of 3000 cd / m ² is defined as the lifetime (LT50).

From the results of Table 3, the light emitting device of the example in which the hole transport layer contains a reaction product of a charge transporting compound having two or more aldehyde groups and an organic transition metal complex has two or more aldehyde groups. It was revealed that the luminance, current efficiency, and device lifetime were improved as compared with Comparative Example 1 that did not include the charge transporting compound. In the light emitting device of the example, it is presumed that high device characteristics were obtained because the elution of the hole transport layer into the light emitting layer could be prevented by improving the solvent resistance of the hole transport layer. Among them, the light-emitting elements of Examples 3 to 6 have higher brightness, improved current efficiency, and longer element life than the light-emitting element of Comparative Example 2 using PVK in which a light-emitting layer can be stacked with a difference in solubility. It was revealed that it improved.
Comparative Example 3 shows the highest current efficiency among the comparative examples, but since there is no hole transport layer, it deteriorates at the interface between the hole injection layer and the light emitting layer, and the element lifetime is It has become shorter. In the light emitting device of the example according to the present invention, it is presumed that the hole transport layer can prevent this interface deterioration and the device life is improved.

Further, it was found that results in elution when used in depositing the alpha-NPD and MoO ₃ as in Comparative Example 4 in the hole transport layer, a light-emitting layer when coating deposition. As a result, in the device of Comparative Example 4, the luminance was lowered because the hole transport layer was mixed in the light emitting layer. In addition, the voltage drop in the device of Comparative Example 4 is due to the fact that the hole transport layer became thinner due to elution of the hole transport layer, and that the hole transport material was mixed in the light emitting layer, so that the light emitting layer was corrected. It is presumed to be caused by the fact that it becomes easier to carry holes and excessive holes.

≪Light-emitting device characteristics experiment 2≫
In order to investigate the effect of the organic transition metal complex (molybdenum hexacarbonyl), device characteristics were compared with and without the organic transition metal complex (molybdenum hexacarbonyl). In order to eliminate and compare the influence of mixing of the hole transport material into the light emitting layer by the wet film forming method, the light emitting layer was formed by a vapor deposition method.
[Reference Example 10]
In Reference Example 2, the light emitting layer is not applied and formed, but in the vacuum (pressure) by the resistance heating vapor deposition method with the same composition (weight ratio of CBP as the host and Ir (mppy) 3 as the dopant is 20: 1). 1 × 10 ⁻⁴ Pa), and a device was fabricated in the same manner as in Reference Example 2 except that the film thickness was 30 nm.

[Comparative Example 5]
In Reference Example 10, instead of using the charge transporting organic layer forming ink 3 obtained in Synthesis Example 3 as the charge transporting organic layer forming ink, poly [(9,9-dioctylfluorenyl-2, 7-diyl) -co- (4,4 ′-(N- (4-sec-butylphenyl)) diphenylamine)] (TFB) and 0.5 parts by weight of TPA (TPA-ald) having two aldehyde groups A device was fabricated in the same manner as in Reference Example 10 except that 0.4 part by weight and 100 parts by weight of xylene were mixed and a hole transport layer was formed using the charge transportable organic layer forming comparative ink 6.

Each element obtained in Reference Example 10 and Comparative Example 5 was evaluated in the same manner as in Reference Example 1 in terms of voltage, luminance, current efficiency, and luminance half time when driven at 10 mA / cm ² . The results are shown in Table 4.

  From the results shown in Table 4, although there is no difference in current efficiency depending on the presence or absence of the organic transition metal complex, in Example 10, the device life was about 10 times longer. From these facts, when a reaction product of a charge transporting compound having two or more aldehyde groups and an organic transition metal complex is contained, the organic transition metal complex does not adversely affect the device, and the film stability of the hole transport layer is stabilized. It is presumed that the device life is improved by improving the performance. On the other hand, when the organic transition metal complex is not included, the reaction of TPA having two aldehyde groups does not occur or becomes insufficient, and TPA having two aldehyde groups in TFB becomes hole due to driving heat at the time of driving the element. It is presumed that the device life is shortened as a result of the tendency to aggregate in the transport layer or at the interface, resulting in poor film stability.

DESCRIPTION OF SYMBOLS 1 Electrode 2 Charge transportable organic layer 3 Organic layer 6 Electrode 7 Substrate 10 Electrode 20 Hole transport layer 30 Light emitting layer 31 Light emitting layer 40 Electron transport layer 50 Electron injection layer 60 Electrode 70 Substrate 100 Light emitting material 110 Organic light emitting dopant 120 EL light emission 130 PL light emission

Claims (4)

  It is a reaction product of a charge transporting compound having two or more aldehyde groups and an organic transition metal complex, the charge transporting compound is an arylamine derivative, and the organic transition metal complex is chromium, rhenium, iron, cobalt A material for forming a charge transporting organic layer, comprising at least one metal selected from the group consisting of platinum, zinc, and vanadium. Preparing a charge transporting organic layer forming ink comprising a charge transporting compound having at least two aldehyde groups, an organic transition metal complex, and an organic solvent;
Reaction between the charge transporting compound having at least two aldehyde groups and the organic transition metal complex by heating or light irradiation to produce a reaction between the charge transporting compound having two or more aldehyde groups and the organic transition metal complex A step of preparing a product,
The charge transporting compound is an arylamine derivative, and the organic transition metal complex includes at least one metal selected from the group consisting of chromium, rhenium, iron, cobalt, platinum, zinc, and vanadium. For producing a material for forming a conductive organic layer.   A charge-transporting organic material comprising a charge-transporting compound having at least two aldehyde groups, an organic transition metal complex, and an organic solvent, which is used for preparing the charge transporting organic layer forming material according to claim 1. Layer forming ink.   The ink for forming a charge transporting organic layer according to claim 3, further comprising a hole transporting polymer compound different from the charge transporting compound having two or more aldehyde groups.

Images