JP2008239948A - Material for organic electroluminescent element, composition for organic electroluminescent element, organic electroluminescent display and color display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescent element having an emitting layer including a blue-fluorescent compound forming a film by a wet film forming method. <P>SOLUTION: The material for organic electroluminescent element includes 1,7-diaryl-amino-naphthalene that has the structure represented by the chemical formula (1) (wherein Ar<SP>1</SP>to Ar<SP>4</SP>are each independently an aromatic hydrocarbon group which may have a substituent) and has solubility of more than 0.2 wt.% in toluene. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a material for an organic electroluminescent light emitting device and the like.

In recent years, organic electroluminescent devices using organic thin films instead of inorganic materials have been developed as thin film type electroluminescent devices. An organic electroluminescent device usually has a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and the like between an anode and a cathode, and materials suitable for these layers have been developed.
Examples of the method for forming each layer include a vacuum deposition method and a wet film forming method. According to the vacuum deposition method, a good quality thin film can be uniformly formed, easy to stack, and has few advantages such as less contamination of impurities.
On the other hand, since the wet film forming method does not require a vacuum process and can easily increase the area, for example, organic electroluminescence has been reported in which an organic thin film layer containing a distyrylarylene derivative is formed by a wet film forming method. (See Patent Document 1).

International Publication No. 03/037836 Pamphlet

By the way, red, green and blue fluorescent compounds are used in the organic electroluminescent device. Among these, the blue fluorescent compound is characterized in that the application is high because the photon of high energy is emitted compared to the red or green fluorescent compound, and the light emitting element in the light emitting state is easily exposed to a high temperature.
Moreover, there exists a problem that the fluorescent compound in a light emitting layer tends to raise | generate a phase change by post process processes, such as a sealing material heat-curing process performed after forming a light emitting layer. For this reason, a fluorescent compound having a high glass transition temperature (Tg) is usually used.
However, a fluorescent compound having a high glass transition temperature (Tg) has a rigid molecular structure and is not affected by a phase change caused by heating and is excellent in extending the life of the device. However, it is soluble in an organic solvent. There is a problem that is low. Therefore, it is difficult to obtain a light emitting layer coating solution used in the wet film forming method.

  The present invention has been made to solve the above-described problems. That is, an object of the present invention is to provide an organic electroluminescent light emitting device material having a light emitting layer containing a blue fluorescent compound that can be formed by a wet film forming method.

Thus, according to the present invention, there is provided an organic electroluminescent device material characterized by comprising a 1,7-diarylaminonaphthalene derivative.
Here, the 1,7-diarylaminonaphthalene derivative is preferably a compound having a structure represented by the following chemical formula (1).

(In the chemical formula (1), Ar ^{1 to} Ar ⁴ each independently represents an aromatic hydrocarbon group which may have a substituent.)

It is preferable that the 1,7-diarylaminonaphthalene derivative as the material for an organic electroluminescence device has a solubility in toluene of 0.2% by weight or more.
Moreover, it is preferable that the organic electroluminescent light emitting element material comprising a 1,7-diarylaminonaphthalene derivative is used for wet film formation.

  Next, according to the present invention, for an organic electroluminescent device characterized by comprising a material for an organic electroluminescent device comprising a 1,7-diarylaminonaphthalene derivative represented by the chemical formula (1) and a solvent. A composition is provided.

Furthermore, according to the present invention, there is provided an organic electroluminescent device having an anode and a cathode, and an organic layer provided between the anode and the cathode, wherein the organic layer is represented by chemical formula (1) 1, An organic electroluminescent light emitting device comprising an organic electroluminescent light emitting device material comprising a 7-diarylaminonaphthalene derivative is provided.
Here, the organic layer is preferably a light emitting layer.
The organic layer is preferably formed by a wet film forming method using a composition containing an organic electroluminescent device material and a predetermined solvent.

  Next, according to the present invention, there is provided an organic EL display having a transparent support substrate and an organic electroluminescent device laminated on the transparent support substrate, wherein the organic electroluminescent device is represented by the chemical formula (1). There is provided an organic EL display comprising an organic electroluminescence device having an organic layer containing an organic electroluminescence device material composed of a 1,7-diarylaminonaphthalene derivative.

Furthermore, according to the present invention, there is provided an organic electroluminescent light emitting device having a light emitting layer containing a light emitting compound between a pair of electrodes, the light emitting compound having a glass transition temperature (Tg) of 80 ° C. or higher and toluene. There is provided an organic electroluminescent device characterized in that it is composed of a 1,7-diarylaminonaphthalene derivative having a solubility in water of 0.2% by weight or more.
Here, the light emitting layer in the organic electroluminescent device is preferably formed by applying a coating solution containing a 1,7-diarylaminonaphthalene derivative and a predetermined organic solvent.

  In addition, the present invention includes a luminescent compound composed of a 1,7-diarylaminonaphthalene derivative having a glass transition temperature (Tg) of 80 ° C. or higher and a solubility in toluene of 0.2 wt% or higher. Provided is a color display device comprising an organic electroluminescent device having a light emitting layer.

  In the organic electroluminescent light emitting device of the present invention, the light emitting layer is formed by a wet film forming method.

  The best mode for carrying out the present invention (hereinafter, an embodiment of the present invention) will be described in detail below. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary. The drawings used are for explaining the present embodiment and do not represent the actual size.

(Organic electroluminescent device)
The organic electroluminescent light emitting device to which the present embodiment is applied has an organic layer such as a light emitting layer provided between at least a pair of electrodes (anode and cathode) and both electrodes on a substrate. The layer contains a 1,7-diarylaminonaphthalene derivative.
Next, each layer of the organic electroluminescence device will be described.

  FIG. 1 is a schematic cross-sectional view showing an example of the structure of an organic electroluminescence device to which the present embodiment is applied. In FIG. 1, 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a hole transport layer, 5 is a light emitting layer (organic light emitting layer), 6 is a hole blocking layer, 7 is an electron transport layer, 8 Represents an electron injection layer, and 9 represents a cathode.

[1] Substrate The substrate 1 serves as a support for the organic electroluminescent device, and a quartz or glass plate, a metal plate or a metal foil, a plastic film, a sheet, or the like is used. In particular, a glass plate or a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, polysulfone or the like is preferable. When using a synthetic resin substrate, it is necessary to pay attention to gas barrier properties. If the gas barrier property of the substrate is too small, the organic electroluminescent device may be deteriorated by the outside air that has passed through the substrate, which is not preferable. For this reason, a method of securing a gas barrier property by providing a dense silicon oxide film or the like on at least one surface of the synthetic resin substrate is also one of preferable methods.

[2] Anode An anode 2 is provided on the substrate 1. The anode 2 plays a role of hole injection into a layer on the light emitting layer side (hole injection layer 3 or light emitting layer 5 or the like).
This anode 2 is usually a metal such as aluminum, gold, silver, nickel, palladium, or platinum, a metal oxide such as an oxide of indium and / or tin, a metal halide such as copper iodide, carbon black, or It is composed of a conductive polymer such as poly (3-methylthiophene), polypyrrole, or polyaniline.

In general, the anode 2 is often formed by a sputtering method, a vacuum deposition method, or the like. In addition, when forming an anode using fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, and conductive polymer fine powder, an appropriate binder resin solution is used. The anode 2 can also be formed by dispersing and coating the substrate 1. Further, in the case of a conductive polymer, a thin film can be directly formed on the substrate 1 by electrolytic polymerization, or the anode 2 can be formed by applying a conductive polymer on the substrate 1 (Appl. Phys. Lett., 60, 2711, 1992).
The anode 2 usually has a single-layer structure, but it can also have a laminated structure made of a plurality of materials if desired.

  The thickness of the anode 2 varies depending on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more, and is usually 1000 nm or less, preferably about 500 nm or less. When it may be opaque, the thickness of the anode 2 is arbitrary, and the anode 2 may be the same as the substrate 1. Furthermore, it is also possible to laminate different conductive materials on the anode 2 described above.

  For the purpose of removing impurities adhering to the anode 2 and adjusting the ionization potential to improve the hole injection property, the anode surface is subjected to ultraviolet (UV) / ozone treatment or oxygen plasma or argon plasma treatment. That is preferred.

[3] Hole Injection Layer Since the hole injection layer 3 is a layer that transports holes from the anode 2 to the light emitting layer 5, the hole injection layer 3 preferably contains a hole transporting compound.
The hole injection layer 3 preferably contains a hole transporting compound, and more preferably contains a hole transporting compound and an electron accepting compound. The hole injection layer 3 preferably contains a cation radical compound, and more preferably contains a cation radical compound and a hole transporting compound.
Furthermore, the hole injection layer 3 may contain a binder resin that does not easily trap charges and a coating property improving agent as necessary.

(Hole transporting compound)
As the hole transporting compound, a compound having an ionization potential of 4.5 eV to 6.0 eV is preferable.
Examples of the hole transporting compound include aromatic amine compounds, phthalocyanine derivatives, porphyrin derivatives, oligothiophene derivatives, polythiophene derivatives, and the like. Of these, aromatic amine compounds are preferred from the viewpoints of amorphousness and visible light transmittance.

  An aromatic tertiary amine compound is particularly preferable. Here, the aromatic tertiary amine compound is a compound having an aromatic tertiary amine structure, and includes a compound having a group derived from an aromatic tertiary amine.

The kind of the aromatic tertiary amine compound is not particularly limited, but a polymer compound having a weight average molecular weight of 1,000 or more and 1,000,000 or less (polymerized hydrocarbon compound in which repeating units are linked) is more preferable from the viewpoint of the surface smoothing effect.
Preferable examples of the aromatic tertiary amine polymer compound include a polymer compound having a repeating unit represented by the following general formula (VII).

(In General Formula (VII), Ar ²¹ and Ar ²² each independently represents an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent. Ar ^{23 to} Ar ²⁵ each independently represents a divalent aromatic hydrocarbon group which may have a substituent, or a divalent aromatic heterocyclic group which may have a substituent. Y represents a linking group selected from the following group of linking groups, and among Ar ^{21 to} Ar ²⁵ , two groups bonded to the same N atom are bonded to each other to form a ring. May be.)

(In the above formulas, Ar ^{31 to} Ar ⁴¹ are each independently 1 derived from an aromatic hydrocarbon ring which may have a substituent, or an aromatic heterocyclic ring which may have a substituent. And R ⁵¹ and R ⁵² each independently represents a hydrogen atom or an arbitrary substituent.

As Ar ^{21 to} Ar ²⁵ and Ar ^{31 to} Ar ⁴¹ , any monovalent or divalent group derived from any aromatic hydrocarbon ring or aromatic heterocyclic ring is applicable. These may be the same or different from each other. Moreover, you may have arbitrary substituents.

The group derived from the aromatic hydrocarbon ring and / or aromatic heterocycle of Ar ^{21 to} Ar ⁴¹ may further have a substituent. The molecular weight of the substituent is usually 400 or less, preferably about 250 or less.

Ar ²¹ and Ar ²² are preferably monovalent groups derived from a benzene ring, a naphthalene ring, a phenanthrene ring, a thiophene ring, or a pyridine ring from the viewpoint of the solubility, heat resistance, and hole injection / transport properties of the polymer compound. More preferred are a phenyl group and a naphthyl group.

Ar ^{23 to} Ar ²⁵ are preferably divalent groups derived from a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring from the viewpoint of heat resistance and hole injection / transport properties including redox potential. A group, a biphenylene group, and a naphthylene group are more preferable.

  Specific examples of the aromatic tertiary amine polymer compound having a repeating unit represented by the general formula (VII) include those described in WO2005 / 089024.

The hole transporting compound used as the material for the hole injection layer 3 may contain any one of these compounds alone, or may contain two or more. In the case of containing two or more kinds of hole transporting compounds, the combination is arbitrary, but one or more kinds of aromatic tertiary amine polymer compounds and one or two kinds of other hole transporting compounds. It is preferable to use the above together.
These hole transporting compounds may be appropriately contained in the light emitting layer 5.

(Electron-accepting compound)
The electron-accepting compound is preferably a compound having an oxidizing power and the ability to accept one electron from the above-described hole transporting compound, specifically, a compound having an electron affinity of 4 eV or more is preferable, and 5 eV or more. The compound of is more preferable.

  Examples include onium salts substituted with organic groups such as 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) borate, iron (III) chloride (Japanese Patent Laid-Open No. 11-251067), ammonium peroxodisulfate, etc. High valent inorganic compounds, cyano compounds such as tetracyanoethylene, aromatic boron compounds such as tris (pentafluorophenyl) borane (Japanese Patent Laid-Open No. 2003-31365), fullerene derivatives, iodine and the like.

  Of the above compounds, onium salts substituted with organic groups and high valent inorganic compounds are preferred because of their strong oxidizing power, and organic groups are substituted because they are soluble in various solvents and applicable to wet coating. Preferred are onium salts, cyano compounds, and aromatic boron compounds.

  Specific examples of an onium salt substituted with an organic group, a cyano compound, and an aromatic boron compound suitable as an electron-accepting compound include those described in WO 2005/089024, and suitable examples thereof are also the same. Although the compound (A-2) represented by the following structural formula is mentioned, it is not limited to them at all.

(Cation radical compound)
The cation radical compound is an ionic compound composed of a cation radical which is a chemical species obtained by removing one electron from a hole transporting compound and a counter anion. However, when the cation radical is derived from a hole transporting polymer compound, the cation radical has a structure in which one electron is removed from the repeating unit of the polymer compound.

  The cation radical is preferably a chemical species obtained by removing one electron from the aforementioned compound in the hole transporting compound, and is preferably a chemical species obtained by removing one electron from a compound more preferable as the hole transporting compound. From the viewpoints of visible light transmittance, heat resistance, solubility, and the like.

  The cation radical compound can be generated by mixing the hole transporting compound and the electron accepting compound. That is, by mixing the hole transporting compound and the electron accepting compound, electron transfer occurs from the hole transporting compound to the electron accepting compound, and the cation radical and the counter anion of the hole transporting compound are included. A cation ion compound is formed.

  Cationic radical compounds derived from polymer compounds such as PEDOT / PSS (Adv. Mater., 2000, 12, 481) and emeraldine hydrochloride (J. Phys. Chem., 1990, 94, 7716) It is also produced by oxidative polymerization (dehydrogenation polymerization), that is, by oxidizing the monomer chemically or electrochemically with peroxodisulfate in an acidic solution. In the case of this oxidative polymerization (dehydrogenation polymerization), the monomer is oxidized to be polymerized, and the cation radical is formed by removing one electron from the repeating unit of the polymer with an anion derived from an acidic solution as a counter anion. Produces.

  The hole injection layer 3 is formed on the anode 2 by a wet film forming method or a vacuum deposition method.

  In the case of layer formation by a wet film-forming method, a predetermined amount of one or more of the aforementioned materials (hole transporting compound, electron accepting compound, cation radical compound) is not trapped as necessary. Add binder resin and coatability improver, dissolve in solvent, prepare coating solution, by wet film forming method such as spin coating, spray coating, dip coating, die coating, flexographic printing, screen printing, inkjet method etc. It is applied on the anode 2 and dried to form the hole injection layer 3.

  Here, the drying is preferably performed at 200 ° C. or higher, more preferably 210 ° C. or higher, particularly preferably 230 ° C. or higher, usually 350 ° C. or lower, preferably 280 ° C. or lower. When the drying temperature is excessively low, insolubilization to a solvent tends to be insufficient. When the drying temperature is excessively high, part of the hole injection layer material tends to decompose. The drying time is usually 30 minutes or longer, preferably 1 hour or longer, preferably 3 hours or shorter, more preferably 1 hour or shorter. When the drying time is excessively short, insolubilization to the solvent tends to be insufficient.

  As the solvent used for the layer formation by the wet film forming method, any solvent can be used as long as it can dissolve the above-mentioned materials (hole transporting compound, electron accepting compound, cation radical compound). Is not particularly limited, but generates a deactivated substance or deactivated substance that may deactivate each material (hole transporting compound, electron accepting compound, cation radical compound) used for the hole injection layer 3 What does not contain a thing is preferable. An ether solvent or an ester solvent is preferable.

In the case of forming a layer by vacuum deposition, one or more of the aforementioned materials (hole transporting compound, electron accepting compound, cation radical compound) are put in a crucible installed in a vacuum vessel ( When two or more materials are used, put them in each crucible), and after evacuating the inside of the vacuum vessel to about 10 ⁻⁴ Pa with an appropriate vacuum pump, heat the crucible (if using two or more materials, each The crucible is heated), the amount of evaporation is controlled and evaporated (when two or more materials are used, the amount of evaporation is controlled independently), and the substrate is placed on the anode 2 facing the crucible. A hole injection layer 3 is formed. When two or more kinds of materials are used, a mixture of them can be put in a crucible, heated and evaporated to be used for forming the hole injection layer 3.

  The film thickness of the hole injection layer 3 thus formed is usually in the range of 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less. The hole injection layer 3 may be omitted.

[4] Hole Transport Layer The hole transport layer 4 is provided on the hole injection layer 3. The material of the hole transport layer 4 needs to be a material that has a high hole injection efficiency from the anode 2 and can efficiently transport the injected holes. For this purpose, the ionization potential is low, the transparency to visible light is high, the hole mobility is high, the stability is high, and impurities that become traps are unlikely to be generated during manufacturing or use. Required. Further, in order to contact the light emitting layer 5, it is required not to quench the light emitted from the light emitting layer 5 or to form an exciplex with the light emitting layer 5 to reduce the efficiency. In addition to the above general requirements, when the application for in-vehicle display is considered, the element is further required to have heat resistance. Accordingly, a material having a glass transition temperature (Tg) of 85 ° C. or higher is desirable.

  Examples of such a hole transporting material include two or more condensed fragrances including two or more tertiary amines represented by 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl. Aromatics having a starburst structure such as aromatic diamines substituted with nitrogen atoms in the aromatic ring (Japanese Patent Laid-Open No. 5-234681), 4,4 ′, 4 ″ -tris (1-naphthylphenylamino) triphenylamine, etc. Amine compounds (J. Lumin., 72-74, 985, 1997), aromatic amine compounds consisting of tetramers of triphenylamine (Chem. Commun., 2175, 1996), 2, 2 ′ , 7,7'-Tetrakis- (diphenylamino) -9,9'-spirobifluorene, etc. (Synth. Metals, 91, 209, 1997) , 4,4'-N, such as a carbazole derivative such as N'- dicarbazole biphenyl. These compounds may be used individually by 1 type, and may be used in mixture of multiple types as needed.

  In addition to the above compounds, polyarylene ether sulfone (Polym. Adv. Tech.) Containing polyvinyl carbazole, polyvinyl triphenylamine (Japanese Patent Laid-Open No. 7-53953), and tetraphenylbenzidine as a material for the hole transport layer 4. 7, Vol. 33, 1996).

The hole transport layer 4 is a layer obtained by polymerizing a compound having a polymerizable group by irradiation with heat and / or active energy rays (ultraviolet rays, electron beams, infrared rays, microwaves, etc.). preferable.
Here, the “polymerizable group” refers to a group that reacts with the same or different groups of other molecules located in the vicinity by irradiation with heat and / or active energy rays to form a new chemical bond. Although it does not specifically limit as a polymeric group, For example, group containing an unsaturated double bond, cyclic ether, benzocyclobutane etc. is preferable.
Examples of the polymerizable compound include monomers, oligomers, and polymers having the above-described polymerizable group. Among them, monomers are preferable.

Specific examples of the polymerizable compound, for example, triarylamine derivatives, carbazole derivatives, fluorene derivatives, 2,4,6-triphenyl pyridine derivatives, C ₆₀ derivatives, oligothiophene derivatives, phthalocyanine derivatives, porphyrin derivatives, condensed polycyclic An aromatic derivative, a metal complex derivative, etc. are mentioned. Among these, a compound having a partial structure of triphenylamine and a polymerizable group is particularly preferable because of high electrochemical stability and charge transportability.

  The hole transport layer 4 may be formed by a normal coating method such as a spray method, a printing method, a spin coating method, a dip coating method, or a die coating method, a wet film forming method such as various printing methods such as an ink jet method or a screen printing method, or a vacuum. It can be formed by a dry film forming method such as a vapor deposition method.

  In the case of the coating method, an additive such as a binder resin or a coating property improving agent that does not trap holes is added to one or more of the hole transport materials, if necessary, and dissolved in a suitable solvent. A solution is prepared, applied onto the anode 2 by a method such as spin coating, and dried to form the hole transport layer 4. Examples of the binder resin include polycarbonate, polyarylate, and polyester. When the amount of the binder resin added is large, the hole mobility is lowered. Therefore, the smaller amount is desirable, and the content in the hole transport layer is usually preferably 50% by weight or less.

In the case of the vacuum deposition method, the hole transport material is put in a crucible installed in a vacuum vessel, the inside of the vacuum vessel is evacuated to about 10 ⁻⁴ Pa with a suitable vacuum pump, and then the crucible is heated, The hole transport material is evaporated and the hole transport layer 4 is formed on the substrate 1 on which the anode 2 or the hole injection layer 3 is formed, which is placed facing the crucible.

The thickness of the hole transport layer 4 is usually 5 nm or more, preferably 10 nm or more, and is usually 300 nm or less, preferably 100 nm or less. In order to uniformly form such a thin film, a vacuum deposition method is generally used.
The hole transport layer 4 is not necessarily provided, and a light emitting layer 5 described later may be directly formed on the hole injection layer 3.

[5] Light emitting layer (organic light emitting layer)
A light emitting layer 5 (organic light emitting layer) is provided on the hole transport layer 4. The light-emitting layer 5 contains a light-emitting compound, and includes holes injected from the anode 2 through the hole injection layer 3 and electrons injected from the cathode 9 through the electron injection layer 8 between the electrodes to which an electric field is applied. Excited by recombination and becomes the main light source. The light emitting layer 5 preferably contains a light emitting compound (dopant) and one or more host materials.

In this Embodiment, it is preferable that the light emitting layer 5 contains the organic electroluminescent light emitting element material which consists of a 1,7- diarylamino naphthalene derivative as a luminescent compound.
Here, the 1,7-diarylaminonaphthalene derivative is preferably a compound having a structure represented by the following chemical formula (1).

(In the chemical formula (1), Ar ^{1 to} Ar ⁴ each independently represents an aromatic hydrocarbon group which may have a substituent.)

In the chemical formula (1), examples of the aromatic hydrocarbon group which may have a substituent represented by Ar ^{1 to} Ar ⁴ include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, and tetracene. An aromatic hydrocarbon group derived from a ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, a fluoranthene ring, or the like can be given. Among these, a benzene ring, a naphthalene ring, a phenanthrene ring and the like are preferable.

  Examples of the substituent that the aromatic hydrocarbon group may have include, for example, carbon such as methyl group, ethyl group, n-propyl group, 2-propyl group, n-butyl group, isobutyl group, and tert-butyl group. A linear or branched alkyl group having 1 to 8 carbon atoms; an alkenyl group having 1 to 8 carbon atoms such as vinyl group, allyl group, 1-butenyl group; 1 to 8 carbon atoms such as ethynyl group and propargyl group An alkynyl group; an aralkyl group having 1 to 8 carbon atoms such as a benzyl group;

An amino group having at least one alkyl group having 1 to 8 carbon atoms in a substituent such as a methylamino group, a dimethylamino group, a diethylamino group or a dibenzylamino group; an aryl such as a phenylamino group, a diphenylamino group or a ditolylamino group; Amino groups; heteroarylamino groups such as pyridylamino groups, thienylamino groups, and dithienylamino groups; acylamino groups such as acetylamino groups and benzoylamino groups;

Alkoxy groups having 1 to 8 carbon atoms such as methoxy group, ethoxy group and butoxy group; aromatic hydrocarbon groups such as phenyloxy group, 1-naphthyloxy group, 2-naphthyloxy group, pyridyloxy group and thienyloxy group Or an aryloxy group having a heterocyclic group; an acyl group having 1 to 8 carbon atoms such as formyl group, acetyl group or benzoyl group; an alkoxycarbonyl group having 2 to 13 carbon atoms such as methoxycarbonyl group or ethoxycarbonyl group; An aryloxycarbonyl group having 2 to 13 carbon atoms, such as an acetoxy group;

An alkylthio group having 1 to 8 carbon atoms such as a methylthio group and an ethylthio group; an arylthio group having 1 to 8 carbon atoms such as a phenylthio group and a 1-naphthylthio group; a sulfonyl group such as a mesyl group and a tosyl group; Examples thereof include a silyl group such as a phenylsilyl group; a boryl group such as a dimesitylboryl group; a phosphino group such as a diphenylphosphino group.

These substituents may further have a substituent. Examples of such substituents include alkyl groups, diarylamino groups, aromatic hydrocarbon groups, and aromatic heterocyclic groups as described above.
Here, as the aromatic hydrocarbon group, for example, a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, fluoranthene ring and the like are derived. Group hydrocarbon group.

  The aromatic heterocyclic group includes furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring. , Pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, Aromatic heterocyclic groups derived from quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, perimidine ring, quinazoline ring, quinazolinone ring, azulene ring and the like can be mentioned.

  These substituents may further have a substituent. Furthermore, examples of the substituent that may be included include an alkyl group, a diarylamino group, an aromatic hydrocarbon group, and an aromatic heterocyclic group.

In the chemical formula (1), the aromatic hydrocarbon group which may have a substituent represented by Ar ^{1 to} Ar ⁴ is preferably further bonded to an aliphatic ring. Examples of such an aliphatic ring include a cyclobutane ring, a cyclopentane ring, and a cyclohexane ring. Among these, a cyclopentane ring is preferable.

In this embodiment, in the 1,7-diarylaminonaphthalene derivative having the structure represented by the chemical formula (1), the carbon atom at the 1-position (R ₁ ) and the 7-position (R ₇ ) of the naphthalene ring is used as a substituent. The arylamino group to be bonded is preferably one in which the alkyl substituent on the arylamino group has an alicyclic structure, or the alkyl substituent on the arylamino group has an aryl group and a cyclic structure. When the 1,7-diarylaminonaphthalene derivative has an arylamino group having such a structure, solubility in an organic solvent such as toluene is improved. Moreover, when it is used as a material for an organic electroluminescent light emitting device, a good blue emission color tone can be obtained.

Among the diarylaminonaphthalene derivatives, it is not clear why the 1,7-diarylaminonaphthalene derivative has good characteristics as a material for an organic electroluminescent device, but the 1-position (R ₁ ) and 7-position ( This is considered to be due to an asymmetric structure in which an arylamino group is bonded to a carbon atom of R ₇ ).

The glass transition temperature (Tg) of the 1,7-diarylaminonaphthalene derivative used in this embodiment is usually 80 ° C. or higher, preferably 100 ° C. or higher, more preferably 115 ° C. or higher, and still more preferably 130 ° C. ℃ or more. The solubility of the 1,7-diarylaminonaphthalene derivative in toluene is preferably 0.2% by weight or more, more preferably 0.6% by weight or more, and further preferably 1.5% by weight or more.
Here, the 1,7-diarylaminonaphthalene derivative emits blue light in an electric field in the light emitting layer 5 and is used alone or in combination as a dopant or a host. The glass transition temperature (Tg) of the 1,7-diarylaminonaphthalene derivative is measured by a differential scanning calorimeter. The solubility in toluene is at 25 ° C.
Moreover, the molecular weight of the 1,7-diarylaminonaphthalene derivative is preferably 400 to 1,000, more preferably 400 to 800.

  Specific examples of the 1,7-diarylaminonaphthalene derivative represented by the chemical formula (1) include the following compounds.

Furthermore, a specific example is illustrated below.
In the 1,7-diarylaminonaphthalene derivative represented by the following chemical formula (IA), as substituents R ₁ to R ₈ , carbon atoms at the 1-position (R ₁ ) and 7-position (R ₇ ) of the naphthalene ring are as follows: Table 1 shows compounds 1 to 12 in which an arylamino group is bonded as a substituent and the other carbon atom has a hydrogen atom, a methyl group, an ethyl group or a phenyl group.

Here, in Table 1, -H is a hydrogen atom, ME is a methyl group, ET is an ethyl group, and Ph represents a phenyl group.
The structures of AM1 to AM8 that are arylamino groups are as follows.

In this embodiment, the 1,7-diarylaminonaphthalene derivative exemplified as the light-emitting compound may further introduce a substituent as necessary.
In the present embodiment, the 1,7-diarylaminonaphthalene derivatives described above may be used alone or in combination of two or more 1,7-diarylaminonaphthalene derivatives.

  In the present embodiment, the light emitting layer 5 of the organic electroluminescent light emitting device is formed by applying a coating solution (composition for an organic electroluminescent light emitting device) containing the aforementioned 1,7-diarylaminonaphthalene derivative and a predetermined organic solvent by a wet film forming method. (Hereinafter referred to as “organic electroluminescent layer coating solution”) is applied on the hole injection layer 3 or the hole transport layer 4 formed on the anode 2 or the anode 2. If the hole transport layer 4 is not provided, it is formed by coating on the hole injection layer 3.

  When the light-emitting layer 5 is formed by a wet film forming method, a predetermined amount of one or two or more kinds of 1,7-diarylaminonaphthalene derivatives is added as necessary with a binder resin or a coating property improving agent that does not trap charges. An organic electroluminescent light emitting layer coating solution dissolved in a solvent is prepared, and this is applied onto the anode 2 by a wet film forming method such as spin coating, spray coating, dip coating, die coating, flexographic printing, screen printing, and inkjet method. And dried to form the light emitting layer 5.

(Other ingredients)
It is preferable that the organic electroluminescent light emitting layer coating solution further contains materials necessary for each layer in addition to the above-described materials for organic electroluminescent light emitting devices. Examples of such other components include charge transport materials.
As such a charge transport material, a compound in which an aromatic ring is condensed on a central skeleton, preferably 3 or more, more preferably 4 or more, and preferably 7 or less, more preferably 6 or less is preferable. Examples of the central skeleton include chrysene, naphthacene, anthracene, phenanthrene, pyrene, coronene, fluoranthene, and benzophenanthrene.

Furthermore, as other charge transport materials, for example, a condensed aromatic ring compound substituted with an arylamino group and / or a styryl derivative substituted with an arylamino group, a condensed aromatic ring represented by the formula (III) described later Compounds and the like.
As the condensed aromatic ring compound substituted with an arylamino group, compounds represented by the formulas (6) to (11) in International Publication No. 2006/070712 are preferable. In addition, as an aryl group having 5 to 40 nuclear carbon atoms in the formula (11), benzophenanthryl is also preferable in addition to the examples described in International Publication No. 2006/070712.

As the charge transport material, a condensed aromatic ring compound represented by the following formula (III) is also preferable.
Ar ¹⁰ -R (III)
Here, in the formula (III), Ar ¹⁰ is a substituted or unsubstituted aryl group having 5 to 40 nuclear carbon atoms. This aryl group preferably has a structure in which aromatic ring nuclei are condensed to 3 or more, more preferably 4 or more, preferably 7 or less, more preferably 6 or less. Specific examples of Ar ¹⁰ include, for example, chrysenyl group, naphthacenyl group, anthryl group, phenanthryl group, pyrenyl group, coronyl group, fluoranthenyl group, benzophenanthryl group, acenaphthofluoranthenyl group, fluorenyl group and the like. Can be mentioned.
In the formula (III), R is selected from a hydrogen atom, an alicyclic hydrocarbon group, or a group exemplified as a substituent for the aryl group of the formula (11) in WO 2006/070712. As the alicyclic hydrocarbon group, for example, an alicyclic hydrocarbon group having 5 to 8 carbon atoms is preferable, and specific examples include a cyclohexyl group and a cyclopentyl group. Further, among the groups exemplified as the substituent of the aryl group of the formula (11) in the pamphlet of International Publication No. 2006/070712, an alkyl group is preferable, and a tertiary carbon atom or a quaternary carbon atom is particularly preferable. An alkyl group is preferable, and an alkyl group having 4 to 15 carbon atoms is particularly preferable.

  The other charge transport material may be a host material or a dopant material. The content of the other charge transport material in the light emitting layer is preferably 0.1% to 98% by weight, more preferably 0.3% to 97% by weight, in total with the organic electroluminescent light emitting layer coating solution. It is preferably included.

  In addition to said compound etc., the organic electroluminescent light emitting layer coating solution may further contain other compounds as required. For example, you may contain the other solvent different from said solvent. Examples of such solvents include amides such as N, N-dimethylformamide and N, N-dimethylacetamide; dimethyl sulfoxide and the like. One of these may be used alone, or two or more may be used in any combination and ratio. Moreover, you may contain various additives, such as a leveling agent and an antifoamer, for the purpose of the improvement of film formability.

  When the light emitting layer 5 is formed by a wet film formation method, the film formation is usually 10 ° C. or higher, preferably 13 ° C. or higher, more preferably 16 ° C. or higher, usually 50 ° C. or lower, preferably 40 ° C. or lower, more preferably 30 ° C. It is done in the following. The relative humidity is usually 0.01% or more, preferably 0.05% or more, preferably 80% or less, more preferably 60% or less. Moreover, oxygen concentration is 0.01 ppm or more normally, More preferably, it is 0.05 ppm or more, Preferably it is 50% or less, More preferably, it is 25% or less.

  In the present embodiment, various solvents can be used as the solvent contained in the organic electroluminescent light emitting layer coating solution described above, and are not particularly limited.

  For example, aromatic hydrocarbons such as toluene, xylene, methicylene, cyclohexylbenzene and tetralin; halogenated aromatic hydrocarbons such as chlorobenzene, dichlorobenzene and trichlorobenzene; 1,2-dimethoxybenzene, 1,3-dimethoxybenzene and anisole , Phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole and other aromatic ethers; phenyl acetate, phenyl propionate, methyl benzoate, benzoic acid Aromatic esters such as ethyl, propyl benzoate and n-butyl benzoate; ketones having an alicyclic ring such as cyclohexanone and cyclooctanone; aliphatic ketones such as methyl ethyl ketone and dibutyl ketone; methyl ethyl ketone and cyclohexano Alcohol having an alicyclic ring such as ruthenium or cyclooctanol; Aliphatic alcohol such as butanol or hexanol; Aliphatic ether such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether or propylene glycol-1-monomethyl ether acetate (PGMEA); Ethyl acetate And aliphatic esters such as n-butyl acetate, ethyl lactate and n-butyl lactate.

  Among these, aromatic hydrocarbons such as toluene, xylene, methicylene, cyclohexylbenzene, and tetralin are preferred in terms of low water solubility and not easily denatured. This is preferable because it is easy to form a light emitting layer of an organic electroluminescent device having excellent film thickness uniformity.

Since organic electroluminescent light emitting elements use many materials such as cathodes that deteriorate significantly due to moisture, the presence of moisture in the organic electroluminescent light emitting layer coating solution leaves moisture in the dried film, There is a possibility of deteriorating the characteristics of the element, which is not preferable.
Examples of a method for reducing the amount of water in the organic electroluminescent layer coating solution include nitrogen gas sealing, use of a desiccant, dehydration of the solvent in advance, use of a solvent with low water solubility, and the like. In particular, it is preferable to use a solvent having low water solubility because the solution film can prevent whitening by absorbing moisture in the atmosphere during the wet film-forming process. From such a viewpoint, for example, it is preferable to contain 10% by weight or more of a solvent having a water solubility at 25 ° C. of 1% by weight or less, preferably 0.1% by weight or less.

Further, in order to prevent the film formation stability from being reduced by evaporation of the solvent during wet film formation, the boiling point is 100 ° C. or higher, preferably the boiling point is 150 ° C. or higher, more preferably the boiling point is 200 ° C. or higher. It is effective to use a solvent.
In order to obtain a more uniform film, it is necessary for the solvent to evaporate from the liquid film immediately after film formation at an appropriate rate. For this purpose, the boiling point is usually 80 ° C. or higher, preferably 100 ° C. or higher. It is effective to use a solvent having a boiling point of 120 ° C. or more, usually less than 270 ° C., preferably less than 250 ° C., more preferably less than 230 ° C. A solvent can also be used individually or in mixture of 2 or more types of solvents.
In order to obtain a more uniform film, vacuum drying, heat drying, optimization of time from film formation to drying treatment, and the like can be performed as necessary.

  In the present embodiment, in addition to the light emitting layer 5, when an organic layer such as the hole injection layer 3 and an electron injection layer 8 described later is provided, The total film thickness combined with the organic layer is usually 30 nm or more, preferably 50 nm or more, more preferably 100 nm or more, usually 1000 nm or less, preferably 500 nm or less, and more preferably 300 nm or less. In addition, when the conductivity of the hole injection layer 3 other than the light emitting layer 5 and the electron injection layer 8 described later is high, the amount of charge injected into the light emitting layer 5 increases. It is also possible to reduce the drive voltage while increasing the thickness to reduce the thickness of the light emitting layer 5 while maintaining the total thickness to some extent.

  Therefore, the film thickness of the light emitting layer 5 is usually 10 nm or more, preferably 20 nm or more, and usually 300 nm or less, preferably 200 nm or less. When the element of the present invention has only the light emitting layer 5 between the anode 2 and the cathode 9, the thickness of the light emitting layer 5 is usually 30 nm or more, preferably 50 nm or more, usually 500 nm or less, preferably 300 nm. It is as follows.

[6] Hole blocking layer The hole blocking layer 6 has a function of confining holes and electrons in the light emitting layer 5 and improving luminous efficiency. That is, the hole blocking layer 6 is generated by increasing the recombination probability with electrons in the light emitting layer 5 by blocking the holes moving from the light emitting layer 5 from reaching the electron transport layer 7. There is a role of confining excitons in the light emitting layer 5 and a role of efficiently transporting electrons injected from the electron transport layer 7 in the direction of the light emitting layer 5.

  The hole blocking layer 6 can prevent holes moving from the anode 2 from reaching the cathode 9 and can efficiently transport electrons injected from the cathode 9 toward the light emitting layer 5. The compound is laminated on the light emitting layer 5 so as to be in contact with the interface of the light emitting layer 5 on the cathode 9 side.

  The physical properties required for the material constituting the hole blocking layer 6 include high electron mobility, low hole mobility, a large energy gap (difference between HOMO and LUMO), and excited triplet level (T1). Is high.

  Examples of the material of the hole blocking layer 6 that satisfies such conditions include bis (2-methyl-8-quinolinolato) (phenolato) aluminum, bis (2-methyl-8-quinolinolato) (triphenylsilanolato) aluminum, and the like. Mixed ligand complexes, metal complexes such as bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolinato) aluminum binuclear metal complexes, styryls such as distyrylbiphenyl derivatives Compounds (JP-A-11-242996), triazole derivatives such as 3- (4-biphenylyl) -4-phenyl-5 (4-tert-butylphenyl) -1,2,4-triazole (JP-A-7- 41759) and phenanthroline derivatives such as bathocuproine (Japanese Patent Laid-Open No. 10-79297).

  Furthermore, a compound having at least one pyridine ring substituted at the 2,4,6-positions described in WO05 / 022962 is also preferable as the hole blocking material.

  The film thickness of the hole blocking layer 6 is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less. The hole blocking layer 6 can be formed by the same method as the hole injection layer 3, but usually a vacuum deposition method is used.

[7] Electron Transport Layer The electron transport layer 7 is provided between the light emitting layer 5 and the electron injection layer 8 for the purpose of further improving the light emission efficiency of the device.
The electron transport layer 7 is formed of a compound that can efficiently transport electrons injected from the cathode 9 between electrodes to which an electric field is applied in the direction of the light emitting layer 5. As the electron transporting compound used for the electron transport layer 7, the electron injection efficiency from the cathode 9 or the electron injection layer 8 is high, and the injected electrons can be efficiently transported with high electron mobility. It must be a compound.

  Materials satisfying such conditions include metal complexes such as aluminum complexes of 8-hydroxyquinoline (Japanese Patent Laid-Open No. 59-194393), metal complexes of 10-hydroxybenzo [h] quinoline, oxadiazole derivatives, di- Styryl biphenyl derivative, silole derivative, 3- or 5-hydroxyflavone metal complex, benzoxazole metal complex, benzothiazole metal complex, trisbenzimidazolylbenzene (US Pat. No. 5,645,948), quinoxaline compound No. 207169), phenanthroline derivatives (Japanese Patent Laid-Open No. 5-331459), 2-t-butyl-9,10-N, N′-dicyanoanthraquinonediimine, n-type hydrogenated amorphous silicon carbide, n-type sulfide Examples include zinc and n-type zinc selenide.

  The lower limit of the thickness of the electron transport layer 7 is usually 1 nm, preferably about 5 nm, and the upper limit is usually about 300 nm, preferably about 100 nm. The electron transport layer 7 is formed by laminating on the light emitting layer 5 by a wet film forming method or a vacuum deposition method in the same manner as the hole injection layer 3. Usually, a vacuum deposition method is used.

[8] Electron Injection Layer The electron injection layer 8 serves to efficiently inject electrons injected from the cathode 9 into the light emitting layer 5. In order to perform electron injection efficiently, the material for forming the electron injection layer 8 is preferably a metal having a low work function, and an alkali metal such as sodium or cesium, or an alkaline earth metal such as barium or calcium is used. The thickness of the electron injection layer 8 is preferably 0.1 nm to 5 nm.

Also, an ultrathin insulating film (0.1 to 5 nm) such as LiF, MgF ₂ , Li ₂ O, Cs ₂ CO ₃ may be inserted at the interface between the cathode 9 and the light emitting layer 5 or the electron transport layer 7 described later. This is an effective method for improving the efficiency of the device (Appl. Phys. Lett., 70, 152, 1997; Japanese Patent Laid-Open No. 10-74586; IEEE Trans. Electron. Devices, 44, 1245, 1997). Year; SID 04 Digest, page 154).

  Furthermore, an organic electron transport material represented by a metal complex such as a nitrogen-containing heterocyclic compound such as bathophenanthroline or an aluminum complex of 8-hydroxyquinoline is doped with an alkali metal such as sodium, potassium, cesium, lithium, rubidium ( As described in JP-A-10-270171, JP-A-2002-1000047, JP-A-2002-1000048, and the like, it is possible to improve electron injection / transport properties and achieve excellent film quality. preferable. The film thickness in this case is usually 5 nm or more, preferably 10 nm or more, and usually 200 nm or less, preferably 100 nm or less.

The electron injection layer 8 is formed by laminating on the light emitting layer 5 by the wet film forming method or the vacuum deposition method in the same manner as the light emitting layer 5. In the case of the vacuum vapor deposition method, the vapor deposition source is put in a crucible or metal boat installed in a vacuum vessel, and the inside of the vacuum vessel is evacuated to about 10 ⁻⁴ Pa with an appropriate vacuum pump, and then the crucible or metal boat is By heating and evaporating, the electron injection layer 8 is formed on the substrate placed facing the crucible or the metal boat.

The alkali metal is deposited using an alkali metal dispenser in which nichrome is filled with an alkali metal chromate and a reducing agent. By heating the dispenser in a vacuum container, the alkali metal chromate is reduced and the alkali metal is evaporated. In the case of co-evaporating the organic electron transport material and the alkali metal, the organic electron transport material is put in a crucible installed in a vacuum vessel, and the inside of the vacuum vessel is evacuated to about 10 ⁻⁴ Pa with a suitable vacuum pump. Each crucible and dispenser are simultaneously heated and evaporated to form an electron injection layer 8 on the substrate placed facing the crucible and dispenser. At this time, co-evaporation is uniformly performed in the film thickness direction of the electron injection layer 8, but there may be a concentration distribution in the film thickness direction. The electron injection layer 8 may be omitted.

[9] Cathode The cathode 9 plays a role of injecting electrons into a layer (such as the electron injection layer 8 or the light emitting layer 5) on the light emitting layer 5 side. The material used for the cathode 9 can be the material used for the anode 2, but a metal having a low work function is preferable for efficient electron injection, and tin, magnesium, indium, calcium, A suitable metal such as aluminum or silver or an alloy thereof is used. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy.

  The film thickness of the cathode 9 is usually the same as that of the anode 2. For the purpose of protecting the cathode made of a low work function metal, further laminating a metal layer having a high work function and stable to the atmosphere on the cathode increases the stability of the device. For this purpose, metals such as aluminum, silver, copper, nickel, chromium, gold, platinum are used.

[10] Other Constituent Layers Although the above description has focused on the element having the layer structure shown in FIG. 1, in the present embodiment, between the anode 2 and the cathode 9 and the light emitting layer 5 in the organic electroluminescent device. May have any layer as long as its performance is not impaired, and any layer other than the light emitting layer 5 may be omitted. For example, the electron transport layer 7 and the hole blocking layer 6 may be appropriately provided as necessary. 1) Only the electron transport layer 7 2) Only the hole blocking layer 6 3) Hole blocking layer 6 / electron There are usages such as stacking of the transport layer 7, 4) not using, and the like.

  For the same purpose as the hole blocking layer 6, it is also effective to provide an electron blocking layer (not shown) between the hole injection layer 3 and the light emitting layer 5. The electron blocking layer prevents electrons moving from the light emitting layer 5 from reaching the hole injection layer 3, thereby increasing the recombination probability with holes in the light emitting layer 5, and generating generated excitons. There is a role of confining in the light emitting layer 5 and a role of efficiently transporting holes injected from the hole injection layer 3 in the direction of the light emitting layer 5.

The characteristics required for the electron blocking layer include high hole transportability, a large energy gap (difference between HOMO and LUMO), and a high excited triplet level (T1). In the present embodiment, it is preferable that the light emitting layer 5 is formed by a wet film forming method, and in that case, it is preferable that the electron blocking layer is also formed by a wet film forming method because the device manufacturing becomes easy. .
For this reason, it is preferable that the electron blocking layer also has wet film formation compatibility. As a material used for such an electron blocking layer, for example, a copolymer of dioctylfluorene and triphenylamine typified by F8-TFB is used. (Described in WO 2004/084260).

Note that the structure opposite to that shown in FIG. 1, that is, the cathode 9, the electron injection layer 8, the light emitting layer 5, the hole injection layer 3, and the anode 2 can be laminated on the substrate 1 in this order. It is also possible to provide an organic electroluminescent device between two substrates, at least one of which is highly transparent.
Furthermore, a structure in which a plurality of layers shown in FIG. 1 are stacked (a structure in which a plurality of light emitting units are stacked) may be employed. In that case, instead of the interfacial layer (between the light emitting units) (when the anode is ITO and the cathode is Al, the two layers), for example, V ₂ O ₅ is used as the charge generation layer (CGL). This is more preferable from the viewpoint of light emission efficiency and driving voltage.

The organic electroluminescent light emitting device to which this embodiment is applied is applicable to any of a single device, an element having a structure arranged in an array, and a structure in which an anode and a cathode are arranged in an XY matrix. can do.
The organic electroluminescent light emitting device to which this embodiment is applied can be applied to color display applications having a large area, such as a color display module substrate, a color display display device, and a color display television.
Furthermore, the organic electroluminescent element to which this embodiment is applied can be used as an organic electroluminescent element in an organic EL display. In this case, the organic EL display is composed of a transparent support substrate and an organic electroluminescent element laminated on the transparent support substrate.

(Organic EL display)
Next, an organic EL display will be described.
The organic EL display to which the present embodiment is applied has at least a transparent support substrate and an organic electroluminescent element laminated on the transparent support substrate. As the organic electroluminescent element, the organic electroluminescent element material described above or By using an organic electroluminescent device comprising an organic layer formed using a composition for organic electroluminescent devices, for example, “Organic EL Display” (Ohm Co., Ltd., issued on August 20, 2004, Shizushi Tokito An organic EL display as described in Chiyaya Adachi and Hideyuki Murata) can be formed.

  Hereinafter, the present invention will be described in more detail based on examples. The present invention is not limited to the following examples without departing from the gist thereof. In addition, unless otherwise indicated, in the following description, a part refers to a weight part.

(Measurement of solubility of 1,7-diarylaminonaphthalene derivative in toluene)
1,7-diarylaminonaphthalene derivative (usually in the range of 3 mg to 10 mg) and toluene are put into a glass sample bottle having an internal volume of 2 mL to 10 mL, the lid of the glass sample bottle is closed, stirring, ultrasonic irradiation or Heat treatment to promote solute dissolution as much as possible. Next, the glass sample bottle was allowed to stand at 25 ° C. for 10 hours or more, and then the solubility was measured.

(Measurement of glass transition temperature (Tg) of 1,7-diarylaminonaphthalene derivative)
The glass transition temperature (Tg) of the 1,7-diarylaminonaphthalene derivative was measured with a differential scanning calorimeter (manufactured by SII Nanotechnology Inc .: DSC6220).

(Synthesis of 1,7-diarylaminonaphthalene derivative)
Two kinds of 1,7-diarylaminonaphthalene derivatives (DDD-1 and DDD-2) were synthesized using the following compound Am1, compound Am2, compound BR1, compound BR2, and compound BR3.

[Synthesis of Compound DDD-1]
1,7-dibromonaphthalene compound BR3 (2.85 g, 10 mmol, molecular weight 285.96), toluene 100 ml, compound Am1 (2.62 g.22 mmol, molecular weight 133.19), trisuterary butylphosphine (0 0.2 g) and tertiary butyl sodium (2.1 g) were stirred for 30 minutes while bubbling nitrogen, and then nitrogen tris (dibenzylideneacetone) dipadium (0) (0.18 g) was added. . The reaction solution was then heated to 80 ° C. and held for 3 hours.
Subsequently, the temperature of the reaction solution was returned to room temperature, 100 ml of demineralized water was added, liquid separation was performed, and the organic layer was evaporated. Then, using a developing solution (hexane / ethyl acetate = 90/10), a column (Wako Pure Chemical Industries, Ltd.) was used. Purification by company silica; Wakogel C-200) gave 2.05 g of 99% pure yellow solid compound Am2.

  Next, Compound Am2 (3.5 g, 10 mmol), Toluene 100 ml, Compound Am1 (2.62 g, 2.2 mmol), Tri-tertiary butylphosphine (0.2 g), 4-bromobiphenyl (Compound BR2) (5 .12 g, 22 mmol) and a solution containing tertiary butyl sodium (2.1 g) were stirred for 30 minutes while bubbling nitrogen, and then tris (dibenzylideneacetone) dipadium (0) (0.18 g) was added thereto. did. The reaction solution was then heated to 80 ° C. and held for 3 hours.

Subsequently, the temperature of the reaction solution was returned to room temperature, 100 ml of demineralized water was added, liquid separation was performed, and the organic layer was evaporated. Then, using a developing solution (hexane / ethyl acetate = 90/10), a column (Wako Pure Chemical Industries, Ltd.) was used. 1.9 g of a yellow solid (compound DDD-1) of a 1,7-diarylaminonaphthalene derivative having a purity of 99% was obtained by purification using silica manufactured by company (Wakogel C-200). The results of ¹ H-NMR measurement of compound DDD-1 are as follows. The chemical formula is shown below.
(Result of NMR measurement)
2.01 (m, 4H), 2.76 (m, 8H), 6.75-8 (m, 30H).

[Synthesis of Compound DDD-2]
In the synthesis of the compound DDD-1, the 2-bromonaphthalene (BR1) (455.1 g, 2.2 mmol) was used instead of 4-bromobiphenyl (compound BR2), and the other conditions were the compound DDD- The synthetic operation was carried out under the same conditions as in the synthesis of 1 to obtain 2.1 g of a yellow solid (compound DDD-2) of a 1,7-diarylaminonaphthalene derivative having a purity of 99%. The results of ¹ H-NMR measurement of compound DDD-1 are as follows. The chemical formula is shown below.
(Result of NMR measurement)
2.01 (m, 4H), 2.76 (m, 8H), 6.75-8 (m, 26H).

(Compound CCC-1)
Moreover, in order to perform a comparative experiment, as shown below, a compound CCC-1 in which an arylamino group was bonded as a substituent to the 2-position and 6-position carbon atoms of the naphthalene ring was synthesized.

Example 1
Using the above-described compound DDD-1, an organic electroluminescent device having a light emitting area portion of 2 mm × 2 mm in size was produced according to the following operation.
In addition, the solubility with respect to the solubility with respect to toluene of the compound DDD-1 is 5 weight%. Moreover, the glass transition temperature (Tg) of compound DDD-1 is 99 degreeC.

(Formation of anode)
An indium tin oxide (ITO) transparent conductive film was formed to a thickness of 150 nm on a glass substrate (sputtered film product, sheet resistance 15Ω). This transparent conductive film was patterned into a stripe having a width of 2 mm by an ordinary photolithography technique to form an anode.
The patterned ITO substrate was cleaned in the order of ultrasonic cleaning with acetone, water with pure water, and ultrasonic cleaning with isopropyl alcohol, and then dried with nitrogen blow to perform ultraviolet ozone cleaning.

(Formation of hole injection layer)
Subsequently, a hole injection layer was formed on the anode. As a material for the hole injection layer, a non-conjugated polymer compound (PB-1: weight average molecular weight 29,400, number average molecular weight 12,600) having an aromatic amino group having the structural formula shown below is used, and photoreaction is performed. It spin-coated on the anode with the initiator (A-1). Table 2 shows the spin coating conditions. Moreover, the use ratio of the non-conjugated polymer compound (PB-1) and the photoreaction initiator (A-1) was (PB-1) :( A-1) = 10: 4 (weight ratio). After spin coating, drying was performed at 260 ° C. for 180 minutes to form a uniform hole injection layer thin film having a thickness of 30 nm.

(Hole transport layer)
A hole transport layer was formed on the formed hole injection layer. A hole transport layer was formed by spin coating using the following compound (HT-1) as a material for the hole transport layer. Table 3 shows the spin coating conditions. After spin coating, drying was performed at 230 ° C. for 60 minutes to form a uniform hole transport layer thin film having a thickness of 20 nm.

(Light emitting layer)
Next, a light emitting layer was formed on the formed hole transport layer. As a material of the light emitting layer, a light emitting layer was formed by spin coating using a composition in which compound DDD-1 and a fluorescent light emitting dopant (D-1) shown below were dissolved in toluene under the following conditions. Table 4 shows the spin coating conditions. The ratio of compound DDD-1 to dopant (D-1) was (compound DDD-1) :( D-1) = 10: 1 (weight ratio). After spin coating, drying was performed at 100 ° C. for 60 minutes to form a uniform light emitting layer thin film having a thickness of 50 nm.

(Hole blocking layer / electron transport layer)
Subsequently, a hole blocking layer was formed on the formed light emitting layer, and an electron transport layer was further formed on the hole blocking layer. A hole blocking layer having a thickness of 10 nm was formed by vacuum deposition using HB-1 shown below as a material for the hole blocking layer. Next, an electron transport layer having a film thickness of 30 nm was formed by vacuum deposition using ET-1 shown below as a material for the electron transport layer.

(Electron injection layer / cathode)
Next, an electron injection layer was formed on the charge transport layer, and a cathode was further formed on the electron injection layer. As the electron injection layer, lithium fluoride (LIF) was used, and an electron injection layer having a film thickness of 0.5 nm was formed by a vacuum evaporation method in the same manner as the organic layer. Also, aluminum was used as the cathode material, and cathodes with a film thickness of 80 nm were stacked in a 2 mm-wide stripe shape that was orthogonal to the ITO stripe that was the anode.

Presence or absence of light emission as a light emitting element and emission color when a voltage of 7 V is applied to an organic electroluminescent light emitting element having a light emitting area portion of size 2 mm × 2 mm produced by using the compound DDD-1 Evaluated.
As a result, blue light emission was obtained from the organic electroluminescent device produced using Compound DDD-1. Furthermore, blue light emission was obtained also from the film | membrane (film thickness of 50 nm) of the compound DDD-1 formed on the glass substrate using the coating liquid containing the compound DDD-1.

(Example 2)
A film (film thickness 50 nm) of compound DDD-2 was formed on a glass substrate using the coating solution containing compound DDD-2 described above. Next, by applying a predetermined voltage to the film of the compound DDD-2, blue light emission was obtained.
Thereby, it is considered that an organic electroluminescent device can be obtained by using the compound DDD-2, similarly to the compound DDD-1 described above.
In addition, the solubility with respect to the solubility with respect to toluene of compound DDD-2 is 5 weight%. Moreover, the glass transition temperature (Tg) of compound DDD-2 is 84 degreeC.

(Reference Example 1)
By the same operation as in the example, an organic electroluminescent device having a light emitting area portion of 2 mm × 2 mm in size was produced using the compound CCC-1 described above. As a result, blue-green light emission was obtained from this organic electroluminescence device, but blue light emission was not obtained.
The solubility of compound CCC-1 in toluene was 2% by weight. Moreover, the glass transition temperature (Tg) of compound CCC-1 is 110 degreeC.

It is a cross-sectional schematic diagram which shows the structural example suitable for an organic electroluminescent light emitting element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Anode, 3 ... Hole injection layer, 4 ... Hole transport layer, 5 ... Light emitting layer, 6 ... Hole blocking layer, 7 ... Electron transport layer, 8 ... Electron injection layer, 9 ... Cathode

Claims (12)

  An organic electroluminescent light-emitting element material comprising a 1,7-diarylaminonaphthalene derivative. The organic electroluminescent light-emitting element material according to claim 1, wherein the 1,7-diarylaminonaphthalene derivative is a compound having a structure represented by the following chemical formula (1).

(In the chemical formula (1), Ar ^{1 to} Ar ⁴ each independently represents an aromatic hydrocarbon group which may have a substituent.)   The organic electroluminescent element material according to claim 1 or 2, wherein the 1,7-diarylaminonaphthalene derivative has a solubility in toluene of 0.2% by weight or more.   The material for an organic electroluminescence device according to any one of claims 1 to 3, which is used for wet film formation.   The composition for organic electroluminescent light emitting elements of any one of Claims 1 thru | or 4 and the solvent are contained, The composition for organic electroluminescent light emitting elements characterized by the above-mentioned. An organic electroluminescent device having an anode and a cathode, and an organic layer provided between the anode and the cathode,
The said organic layer contains the organic electroluminescent light emitting element material of any one of Claims 1 thru | or 4. The organic electroluminescent light emitting element characterized by the above-mentioned.   The organic electroluminescent device according to claim 6, wherein the organic layer is a light emitting layer.   The organic electroluminescent device according to claim 6 or 7, wherein the organic layer is formed by a wet film forming method using a composition containing the material for an organic electroluminescent device and a predetermined solvent. . An organic EL display having a transparent support substrate and an organic electroluminescent device laminated on the transparent support substrate,
The organic electroluminescent light emitting device according to any one of claims 6 to 8, wherein the organic electroluminescent light emitting device is the organic electroluminescent light emitting device. An organic electroluminescent light emitting device having a light emitting layer containing a light emitting compound between a pair of electrodes,
The luminescent compound is:
An organic electroluminescence device comprising a 1,7-diarylaminonaphthalene derivative having a glass transition temperature (Tg) of 80 ° C. or higher and a solubility in toluene of 0.2% by weight or higher. The light emitting layer is
The organic electroluminescent light emitting device according to claim 10, wherein the organic electroluminescent light emitting device is formed by applying a coating solution containing the 1,7-diarylaminonaphthalene derivative and a predetermined organic solvent.   A color display device comprising the organic electroluminescent device according to claim 10.

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