JP2010199296A - Organic electroluminescence element, organic el display and organic el lighting - Google Patents

Organic electroluminescence element, organic el display and organic el lighting Download PDF

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JP2010199296A
JP2010199296A JP2009042505A JP2009042505A JP2010199296A JP 2010199296 A JP2010199296 A JP 2010199296A JP 2009042505 A JP2009042505 A JP 2009042505A JP 2009042505 A JP2009042505 A JP 2009042505A JP 2010199296 A JP2010199296 A JP 2010199296A
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layer
light emitting
compound
ring
organic
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Koichiro Iida
Yanjun Li
Junji Mizukami
Kazutake Okabe
一毅 岡部
延軍 李
潤二 水上
宏一朗 飯田
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Mitsubishi Chemicals Corp
三菱化学株式会社
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    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09BORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
    • C09B57/00Other synthetic dyes of known constitution
    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09BORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
    • C09B1/00Dyes with anthracene nucleus not condensed with any other ring
    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09BORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
    • C09B11/00Diaryl- or thriarylmethane dyes

Abstract

An organic electroluminescence device having a light emitting layer formed by a wet film forming method and having a long driving life is provided.
An organic electroluminescent device having an anode, a light emitting layer, an electron transport layer and a cathode on a substrate, the light emitting layer being a layer formed by a wet film forming method, and having an anthracene ring as a partial structure An organic electroluminescent device comprising: an organic compound having an anthracene ring or a phenanthroline ring as a partial structure.
[Selection] Figure 1

Description

  The present invention relates to an organic electroluminescent element, an organic EL display using the organic electroluminescent element, and organic EL lighting, and more specifically, an organic electroluminescent element having a light emitting layer formed by a wet film forming method. In addition, the present invention relates to an organic electroluminescent element having an improved driving life, an organic EL display using the organic electroluminescent element, and organic EL illumination.

  In recent years, as a thin film type electroluminescent element, an organic electroluminescent element using an organic thin film has been developed instead of using an inorganic material. Organic electroluminescent devices are usually formed by providing a hole injection layer, a hole transport layer, an organic light emitting layer, an electron transport layer, etc. between the anode and the cathode, and materials suitable for each layer are being developed. . In addition, the light emission colors of organic electroluminescent elements are being developed in red, green, and blue, respectively.

  As a method for forming each constituent layer of the organic electroluminescent element, there are a vacuum vapor deposition method and a wet film formation method. Among these, the vacuum deposition method has a problem in terms of yield when manufacturing a medium- or large-sized full-color panel for a television or a monitor. Therefore, the wet film-forming method is suitable for these large area applications.

  However, in order to form an organic layer of an organic electroluminescent device, particularly a light emitting layer, by a wet film formation method, the material forming the organic layer is dissolved in a solvent, and is required as a component layer of the device even after the wet film formation. It is desirable to have high performance. However, many materials for wet film formation that have been developed in the past do not satisfy the conditions required for such a wet film formation method.

  For example, Patent Document 1 discloses an element manufactured by a wet film forming method using a material represented by the following formula.

  Patent Document 2 discloses an element manufactured by a wet film forming method using a material represented by the following formula.

However, even elements using these materials have problems such as not being able to obtain a sufficient lifetime.
For this reason, the improvement about the lifetime improvement of the organic electroluminescent element by a wet film-forming method is desired.

International Publication No. 2006/070712 Pamphlet JP 2004-224766 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an organic electroluminescent element having a long driving life in an organic electroluminescent element having a light emitting layer formed by a wet film forming method. .

  As a result of intensive studies by the present inventors, it has been found that the above problem can be solved by using a specific compound for the light emitting layer and the electron transport layer, and the present invention has been achieved.

  That is, the present invention is an organic electroluminescent device having an anode, a light emitting layer, an electron transport layer and a cathode on a substrate, the light emitting layer being a layer formed by a wet film forming method, and having a partial structure The organic electroluminescent element contains an organic compound having an anthracene ring, and the electron transport layer contains an organic compound having an anthracene ring and / or a phenanthroline ring as a partial structure.

  The present invention also resides in an organic EL display and organic EL illumination using the organic electroluminescent element.

  According to the present invention, there is provided an organic electroluminescent device having a light emitting layer formed by a wet film forming method, which has a drastically improved driving life compared to a conventional organic electroluminescent device. Is done.

  Accordingly, the organic electroluminescent device of the present invention is a flat panel display (for example, for OA computers and wall-mounted televisions), an in-vehicle display device, a mobile phone display, and a light source (for example, a copier). It can be applied to light sources, back light sources for liquid crystal displays and instruments), display boards, and sign lamps, and its technical value is high.

It is a schematic diagram of the cross section which shows embodiment of the organic electroluminescent element of this invention.

  Embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention does not exceed the gist thereof. Not specific to the content.

[Organic electroluminescence device]
The organic electroluminescent element of the present invention is an organic electroluminescent element having an anode, a light emitting layer, an electron transport layer and a cathode on a substrate, and the light emitting layer is a layer formed by a wet film formation method, An organic compound having an anthracene ring as a partial structure is contained, and the electron transport layer contains an organic compound having an anthracene ring and / or a phenanthroline ring as a partial structure.

  Below, the layer structure of the organic electroluminescent element of this invention, its general formation method, etc. are demonstrated with reference to FIG.

  FIG. 1 is a schematic cross-sectional view showing a structural example of an organic electroluminescent element 10 of the present invention. In FIG. 1, 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a hole transport layer, 5 Represents a light-emitting layer, 6 represents a hole blocking layer, 7 represents an electron transport layer, 8 represents an electron injection layer, and 9 represents a cathode.

  In the present invention, the wet film forming method is, for example, a spin coating method, a dip coating method, a die coating method, a bar coating method, a blade coating method, a roll coating method, a spray coating method, a capillary coating method, and an inkjet as described above. This method is a wet film formation method such as a printing method, a screen printing method, a gravure printing method, or a flexographic printing method. Among these film forming methods, a spin coating method, a spray coating method, and an ink jet method are preferable because they are suitable for the liquid property peculiar to the composition for an organic electroluminescence device used for the organic electroluminescence device.

{substrate}
The substrate 1 serves as a support for the organic electroluminescent element, 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 element may be deteriorated by the outside air that has passed through the substrate, which is not preferable. For this reason, a method of providing 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 a preferable method.

{anode}
The anode 2 serves to inject holes into the layer on the light emitting layer side.

  This anode 2 is usually a metal such as aluminum, gold, silver, nickel, palladium, 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 the anode 2 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 It is also possible to form the anode 2 by dispersing it and applying it onto the substrate 1. Furthermore, 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 surface of the anode 2 is treated with ultraviolet (UV) / ozone, or with oxygen plasma or argon plasma. It is preferable to do.

{Hole injection layer}
The hole injection layer 3 is a layer that transports holes from the anode 2 to the light emitting layer 5, and is usually formed on the anode 2.

  The method for forming the hole injection layer 3 according to the present invention may be a vacuum deposition method or a wet film formation method, and is not particularly limited, but the hole injection layer 3 is formed by a wet film formation method from the viewpoint of reducing dark spots. It is preferable.

  The thickness of the hole injection layer 3 is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less.

<Formation of hole injection layer by wet film formation method>
When forming the hole injection layer 3 by wet film formation, the material for forming the hole injection layer 3 is usually mixed with an appropriate solvent (hole injection layer solvent) to form a film-forming composition (positive A composition for forming a hole injection layer), and applying the composition for forming a hole injection layer on a layer (usually an anode) corresponding to the lower layer of the hole injection layer 3 by an appropriate technique. The hole injection layer 3 is formed by coating and drying.

(Hole transporting compound)
The composition for forming a hole injection layer usually contains a hole transporting compound and a solvent as constituent materials of the hole injection layer.

  The hole transporting compound is a compound having a hole transporting property that is usually used in a hole injection layer of an organic electroluminescence device, and may be a polymer compound or the like, a monomer or the like. Although it may be a low molecular weight compound, it is preferably a high molecular weight compound.

  The hole transporting compound is preferably a compound having an ionization potential of 4.5 eV to 6.0 eV from the viewpoint of a charge injection barrier from the anode 2 to the hole injection layer 3. Examples of hole transporting compounds include aromatic amine derivatives, phthalocyanine derivatives, porphyrin derivatives, oligothiophene derivatives, polythiophene derivatives, benzylphenyl derivatives, compounds in which tertiary amines are linked by a fluorene group, hydrazone derivatives, silazane derivatives, silanamines Derivatives, phosphamine derivatives, quinacridone derivatives, polyaniline derivatives, polypyrrole derivatives, polyphenylene vinylene derivatives, polythienylene vinylene derivatives, polyquinoline derivatives, polyquinoxaline derivatives, carbon and the like.

  In the present invention, a derivative includes, for example, an aromatic amine derivative, and includes an aromatic amine itself and a compound having an aromatic amine as a main skeleton. It may be a mer.

  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. When two or more hole transporting compounds are contained, the combination thereof is arbitrary, but one or more aromatic tertiary amine polymer compounds and one or two other hole transporting compounds are used. It is preferable to use the above in combination.

  Among the above examples, an aromatic amine compound is preferable from the viewpoint of amorphousness and visible light transmittance, and 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 type of the aromatic tertiary amine compound is not particularly limited, but from the viewpoint of uniform light emission due to the surface smoothing effect, a polymer compound having a weight average molecular weight of 1,000 or more and 1,000,000 or less (a polymerizable compound in which repeating units are linked) is further included. preferable. Preferable examples of the aromatic tertiary amine polymer compound include a polymer compound having a repeating unit represented by the following formula (I).

(In Formula (I), Ar 1 and Ar 2 each independently represent an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. Ar 3 to Ar 5 each independently represents an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. Represents a linking group selected from the group of linking groups, and among Ar 1 to Ar 5 , two groups bonded to the same N atom may be bonded to each other to form a ring.
(In said each formula, Ar < 6 > -Ar < 16 > represents each independently the aromatic hydrocarbon group which may have a substituent, or the aromatic heterocyclic group which may have a substituent. R 1 and R 2 each independently represents a hydrogen atom or an arbitrary substituent.))

As the aromatic hydrocarbon group and the aromatic heterocyclic group of Ar 1 to Ar 16 , a benzene ring, a naphthalene ring, a phenanthrene ring, a thiophene from the viewpoint of the solubility, heat resistance, hole injection / transport property of the polymer compound A group derived from a ring or a pyridine ring is preferred, and a group derived from a benzene ring or a naphthalene ring is more preferred.

The aromatic hydrocarbon group and aromatic heterocyclic group of Ar 1 to Ar 16 may further have a substituent. The molecular weight of the substituent is usually 400 or less, preferably about 250 or less. As the substituent, an alkyl group, an alkenyl group, an alkoxy group, an aromatic hydrocarbon group, an aromatic heterocyclic group and the like are preferable.

When R 1 and R 2 are optional substituents, examples of the substituent include an alkyl group, an alkenyl group, an alkoxy group, a silyl group, a siloxy group, an aromatic hydrocarbon group, and an aromatic heterocyclic group. .

  Specific examples of the aromatic tertiary amine polymer compound having a repeating unit represented by the formula (I) include those described in International Publication No. 2005/089024.

  The concentration of the hole transporting compound in the composition for forming a hole injection layer is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.01% by weight or more, preferably in terms of film thickness uniformity. Is 0.1% by weight or more, more preferably 0.5% by weight or more, and usually 70% by weight or less, preferably 60% by weight or less, more preferably 50% by weight or less. If this concentration is too high, film thickness unevenness may occur, and if it is too low, defects may occur in the formed hole injection layer.

(Electron-accepting compound)
The composition for forming a hole injection layer preferably contains an electron accepting compound as a constituent material of the hole injection layer.

  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 which is the compound of these is further more preferable.

  Examples of such electron-accepting compounds include triarylboron compounds, metal halides, Lewis acids, organic acids, onium salts, salts of arylamines and metal halides, and salts of arylamines and Lewis acids. Examples thereof include one or more compounds selected from the group. More specifically, an onium salt substituted with an organic group such as 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) borate, triphenylsulfonium tetrafluoroborate (International Publication No. WO 2005/089024); High-valent inorganic compounds such as iron (III) chloride (Japanese Patent Laid-Open No. 11-251067), ammonium peroxodisulfate; cyano compounds such as tetracyanoethylene, tris (pendafluorophenyl) borane (Japanese Patent Laid-Open No. 2003-31365) Aromatic boron compounds such as); fullerene derivatives; iodine; sulfonate ions such as polystyrene sulfonate ions, alkylbenzene sulfonate ions, camphor sulfonate ions, and the like.

  These electron accepting compounds can improve the conductivity of the hole injection layer by oxidizing the hole transporting compound.

  The content of the electron-accepting compound in the hole-injecting layer or the composition for forming a hole-injecting layer with respect to the hole-transporting compound is usually 0.1 mol% or more, preferably 1 mol% or more. However, it is usually 100 mol% or less, preferably 40 mol% or less.

(Other components)
As a material for the hole injection layer, other components may be further contained in addition to the above-described hole transporting compound and electron accepting compound as long as the effects of the present invention are not significantly impaired. Examples of other components include various light emitting materials, electron transporting compounds, binder resins, and coating property improving agents. In addition, only 1 type may be used for another component and it may use 2 or more types together by arbitrary combinations and a ratio.

(solvent)
At least one of the solvents of the composition for forming a hole injection layer used in the wet film formation method is preferably a compound that can dissolve the constituent material of the hole injection layer. The boiling point of this solvent is usually 110 ° C. or higher, preferably 140 ° C. or higher, particularly 200 ° C. or higher, usually 400 ° C. or lower, and preferably 300 ° C. or lower. If the boiling point of the solvent is too low, the drying speed is too high and the film quality may be deteriorated. Further, if the boiling point of the solvent is too high, it is necessary to increase the temperature of the drying step, which may adversely affect other layers and the substrate.

  Examples of the solvent include ether solvents, ester solvents, aromatic hydrocarbon solvents, amide solvents, and the like.

  Examples of ether solvents include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA); 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole , Phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, aromatic ethers such as 2,4-dimethylanisole, and the like.

  Examples of the ester solvent include aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate.

  As the aromatic hydrocarbon solvent, for example, toluene, xylene, cyclohexylbenzene, 3-isopropylpropylphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, cyclohexylbenzene, methylnaphthalene, etc. Can be mentioned.

  Examples of the amide solvent include N, N-dimethylformamide, N, N-dimethylacetamide, and the like.

  In addition, dimethyl sulfoxide and the like can also be used.

  These solvent may use only 1 type and may use 2 or more types by arbitrary combinations and a ratio.

(Film formation method)
After preparing the composition for forming the hole injection layer, the composition is applied on the layer corresponding to the lower layer of the hole injection layer 3 (usually the anode 2) by wet film formation, and dried. The hole injection layer 3 is formed.

  The temperature in the film forming step is preferably 10 ° C. or higher, and preferably 50 ° C. or lower, in order to prevent film loss due to the formation of crystals in the composition.

  Although the relative humidity in a film-forming process is not limited unless the effect of this invention is impaired remarkably, it is 0.01 ppm or more normally and 80% or less normally.

  After the film formation, the film of the composition for forming a hole injection layer is usually dried by heating or the like. Examples of the heating means used in the heating step include a clean oven, a hot plate, infrared rays, a halogen heater, microwave irradiation and the like. Among them, a clean oven and a hot plate are preferable in order to uniformly apply heat to the entire film.

  The heating temperature in the heating step is preferably heated at a temperature equal to or higher than the boiling point of the solvent used in the composition for forming a hole injection layer as long as the effects of the present invention are not significantly impaired. In the case of a mixed solvent containing two or more types of solvents used in the hole injection layer, at least one type is preferably heated at a temperature equal to or higher than the boiling point of the solvent. In consideration of an increase in the boiling point of the solvent, the heating step is preferably performed at 120 ° C. or higher, preferably 410 ° C. or lower.

  In the heating step, the heating time is not limited as long as the heating temperature is not lower than the boiling point of the solvent of the composition for forming a hole injection layer and sufficient insolubilization of the coating film does not occur. Is less than a minute. If the heating time is too long, the components of the other layers tend to diffuse, and if it is too short, the hole injection layer tends to be inhomogeneous. Heating may be performed in two steps.

(Preferred embodiment)
In the present invention, the hole injection layer is preferably a layer that does not contain sulfonic acids. The hole injection layer is preferably a layer containing ion pairs, and as described above, from the viewpoint of reducing dark spots, a layer formed by a wet film formation method is preferable.
If the hole injection layer is a layer containing sulfonic acids, the sulfonic acids are liberated over time, and the light emitting layer may be deteriorated. For this reason, PEDOT / PSS (polythiophene derivative 3,4-ethylenedioxythiophene (3,4-ethylenedioxythiophene), which is sometimes used as a hole injection layer material, is polymerized in high molecular weight polystyrene sulfonic acid. In order to avoid the use of sulfonic acids such as conductive polymers, it is preferable to form a layer not containing them.

  Further, it is preferable that the hole injection layer contains an ion pair because an effect of improving the hole injection property is achieved. The ion pair may be a hole transporting compound or an electron accepting compound, but is usually an electron accepting compound.

  Examples of ion pairs that can be used in the hole injection layer include onium salts substituted with organic groups such as 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) borate, and specific examples thereof. Include those described in International Publication No. 2005/089024.

  The content of these ion pairs in the hole injection layer varies depending on the type and molecular weight of the ion pair used, but is usually 0.1% by weight or more, particularly 1 to 40% by weight as the content in the hole injection layer. % Is preferable. If the content of ion pairs in the hole injection layer is too small, the above-mentioned effect due to the use of ion pairs cannot be obtained sufficiently, and if it is too large, the film formability may be lowered.

<Formation of hole injection layer by vacuum deposition>
When the hole injection layer 3 is formed by vacuum deposition, one or more of the constituent materials of the hole injection layer 3 (the aforementioned hole transporting compound, electron accepting compound, etc.) are placed in a vacuum container. Put in crucibles installed (in case of using two or more materials, put them in each crucible), evacuate the inside of the vacuum vessel to about 10 −4 Pa with a suitable vacuum pump, and then heat the crucible (two types When using the above materials, heat each crucible) and evaporate by controlling the amount of evaporation (when using two or more materials, evaporate by independently controlling the amount of evaporation) and face the crucible Then, the hole injection layer 3 is formed on the anode 2 of the substrate placed on the substrate. In addition, when using 2 or more types of materials, the hole injection layer 3 can also be formed by putting those mixtures into a crucible, heating and evaporating.

The degree of vacuum at the time of vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 × 10 −6 Torr (0.13 × 10 −4 Pa) or more, usually 9.0 × 10 −6 Torr. (12.0 × 10 −4 Pa) or less. The deposition rate is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 Å / second or more and usually 5.0 Å / second or less. The film forming temperature at the time of vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 10 ° C. or higher, preferably 50 ° C. or lower.

{Hole transport layer}
The hole transport layer 4 can be formed on the hole injection layer 3 when there is a hole injection layer and on the anode 2 when there is no hole injection layer 3. The organic electroluminescent device of the present invention may have a configuration in which the hole transport layer is omitted.

  The method for forming the hole transport layer 4 according to the present invention may be a vacuum deposition method or a wet film formation method, and is not particularly limited, but the hole transport layer 4 is formed by a wet film formation method from the viewpoint of reducing dark spots. It is preferable.

  The material for forming the hole transport layer 4 is preferably a material having high hole transportability and capable of efficiently transporting injected holes. Therefore, it is preferable that the ionization potential is small, the transparency to visible light is high, the hole mobility is large, the stability is high, and impurities that become traps are not easily generated during manufacturing or use. In many cases, it is preferable 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 because it is in contact with the light emitting layer 5.

  The material for the hole transport layer 4 may be any material conventionally used as a constituent material for the hole transport layer. For example, the hole transport property used for the hole injection layer 3 described above. What was illustrated as a compound is mentioned. In addition, arylamine derivatives, fluorene derivatives, spiro derivatives, carbazole derivatives, pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, phthalocyanine derivatives, porphyrin derivatives, silole derivatives, oligothiophene derivatives, condensed polycyclic aromatics Group derivatives, metal complexes and the like.

Also, for example, polyvinylcarbazole derivatives, polyarylamine derivatives, polyvinyltriphenylamine derivatives, polyfluorene derivatives, polyarylene derivatives, polyarylene ether sulfone derivatives containing tetraphenylbenzidine, polyarylene vinylene derivatives, polysiloxane derivatives, polythiophenes Derivatives, poly (p-phenylene vinylene) derivatives, and the like. These may be any of an alternating copolymer, a random polymer, a block polymer, or a graft copolymer. Further, it may be a polymer having a branched main chain and three or more terminal portions, or a so-called dendrimer.
Of these, polyarylamine derivatives and polyarylene derivatives are preferred.

The polyarylamine derivative is preferably a polymer containing a repeating unit represented by the following formula (II). In particular, a polymer composed of a repeating unit represented by the following formula (II) is preferable. In this case, Ar a or Ar b may be different in each repeating unit.

(In formula (II), Ar a and Ar b each independently represent an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent.)

  Examples of the aromatic hydrocarbon group which may have a substituent include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, and an acenaphthene. Examples thereof include a group derived from a 6-membered monocyclic ring or a 2-5 condensed ring, such as a ring, a fluoranthene ring, and a fluorene ring, and a group in which two or more of these rings are linked by a direct bond.

  Examples of the aromatic heterocyclic group which may have a substituent include a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, and a carbazole ring. , Pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzoisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine Ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, azulene ring, etc. Or a group and the rings of from 2-4 fused rings include groups formed by connecting a direct bond or two or more rings.

In view of solubility and heat resistance, Ar a and Ar b are each independently selected from the group consisting of a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, triphenylene ring, pyrene ring, thiophene ring, pyridine ring, and fluorene ring. A group derived from a selected ring or a group formed by linking two or more benzene rings (for example, a biphenyl group or a terphenyl group) is preferable.
Among these, a group derived from a benzene ring (phenyl group), a group formed by connecting two benzene rings (biphenyl group), and a group derived from a fluorene ring (fluorenyl group) are preferable.

Examples of the substituent that the aromatic hydrocarbon group and aromatic heterocyclic group in Ar a and Ar b may have include an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, and a dialkyl. Examples thereof include an amino group, a diarylamino group, an acyl group, a halogen atom, a haloalkyl group, an alkylthio group, an arylthio group, a silyl group, a siloxy group, a cyano group, an aromatic hydrocarbon ring group, and an aromatic heterocyclic group.

As the polyarylene derivative, an arylene group such as an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent exemplified as Ar a or Ar b in the formula (II) is used as its repeating unit. The polymer which has is mentioned.
As the polyarylene derivative, a polymer having a repeating unit composed of the following formula (III-1) and / or the following formula (III-2) is preferable.

(In formula (III-1), R a , R b , R c and R d are each independently an alkyl group, an alkoxy group, a phenylalkyl group, a phenylalkoxy group, a phenyl group, a phenoxy group, an alkylphenyl group, Represents an alkoxyphenyl group, an alkylcarbonyl group, an alkoxycarbonyl group, or a carboxy group, and t and s each independently represent an integer of 0 to 3. When t or s is 2 or more, they are contained in one molecule. A plurality of R a or R b may be the same or different, and adjacent R a or R b may form a ring.)

(In formula (III-2), Re and R f are independently the same as R a , R b , R c or R d in formula (III-1). R and u are each independently Represents an integer of 0 to 3. When r or u is 2 or more, a plurality of R e and R f contained in one molecule may be the same or different, and adjacent R e or R f may form a ring, and X represents an atom or a group of atoms constituting a 5-membered ring or a 6-membered ring.)

  Specific examples of X include an oxygen atom, a boron atom which may have a substituent, a nitrogen atom which may have a substituent, a silicon atom which may have a substituent, and a substituent. A phosphorus atom which may be substituted, a sulfur atom which may have a substituent, a carbon atom which may have a substituent, or a group formed by bonding these.

  Further, the polyarylene derivative has a repeating unit represented by the following formula (III-3) in addition to the repeating unit represented by the following formula (III-1) and / or the following formula (III-2). Is preferred.

(In formula (III-3), Ar c to Ar j each independently represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent. Independently represents 0 or 1.)

Specific examples of Ar c to Ar j are the same as Ar a and Ar b in the formula (II).

  Specific examples of the above formulas (III-1) to (III-3) and specific examples of polyarylene derivatives include those described in JP-A-2008-98619.

  In the case of forming the hole transport layer 4 by a wet film formation method, a composition for forming a hole transport layer is prepared in the same manner as the formation of the hole injection layer 3 and then heated and dried after the wet film formation. .

  The composition for forming a hole transport layer contains a solvent in addition to the above hole transport compound. The solvent used is the same as that used for the composition for forming a hole injection layer. The film forming conditions, heat drying conditions, and the like are the same as in the case of forming the hole injection layer 3.

  In the case where the hole transport layer is formed by the vacuum deposition method, the film forming conditions are the same as those in the case of forming the hole injection layer 3.

  The hole transport layer 4 may contain various light emitting materials, electron transport compounds, binder resins, coating property improving agents, and the like in addition to the hole transport compound.

  The hole transport layer 4 may also be a layer formed by crosslinking a crosslinkable compound. The crosslinkable compound is a compound having a crosslinkable group, and forms a network polymer compound by crosslinking.

  Examples of this crosslinkable group include groups derived from cyclic ethers such as oxetane and epoxy; groups derived from unsaturated double bonds such as vinyl, trifluorovinyl, styryl, acrylic, methacryloyl and cinnamoyl; benzo Examples include groups derived from cyclobutene.

The crosslinkable compound may be any of a monomer, an oligomer, and a polymer.
The crosslinkable compound may have only 1 type, and may have 2 or more types by arbitrary combinations and ratios.

  As the crosslinkable compound, a hole transporting compound having a crosslinkable group is preferably used. Examples of the hole transporting compound include those exemplified above, and those having a crosslinkable group bonded to the main chain or side chain with respect to these hole transporting compounds. In particular, the crosslinkable group is preferably bonded to the main chain via a linking group such as an alkylene group. In particular, the hole transporting compound is preferably a polymer containing a repeating unit having a crosslinkable group, and the above formula (II) and formulas (III-1) to (III-3) can be used as a crosslinkable group. Is preferably a polymer having a repeating unit bonded directly or via a linking group.

  As the crosslinkable compound, a hole transporting compound having a crosslinkable group is preferably used. Examples of hole transporting compounds include nitrogen-containing aromatic compound derivatives such as pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, carbazole derivatives, phthalocyanine derivatives, porphyrin derivatives; triphenylamine derivatives Silole derivatives; oligothiophene derivatives, condensed polycyclic aromatic derivatives, metal complexes and the like. Among them, nitrogen-containing aromatic derivatives such as pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, carbazole derivatives; triphenylamine derivatives, silole derivatives, condensed polycyclic aromatic derivatives, metal complexes, etc. Particularly preferred are triphenylamine derivatives.

  In order to form the hole transport layer 4 by crosslinking the crosslinkable compound, a composition for forming a hole transport layer in which the crosslinkable compound is dissolved or dispersed in a solvent is usually prepared and deposited by wet film formation. To crosslink.

The composition for forming a hole transport layer may contain an additive for promoting a crosslinking reaction in addition to the crosslinking compound. Examples of additives that accelerate the crosslinking reaction include polymerization initiators and polymerization accelerators such as alkylphenone compounds, acylphosphine oxide compounds, metallocene compounds, oxime ester compounds, azo compounds, onium salts; condensed polycyclic hydrocarbons, And photosensitizers such as porphyrin compounds and diaryl ketone compounds.
Further, it may contain a coating property improving agent such as a leveling agent and an antifoaming agent; an electron accepting compound; a binder resin;

  In the composition for forming a hole transport layer, the crosslinkable compound is usually 0.01% by weight or more, preferably 0.05% by weight or more, more preferably 0.1% by weight or more, usually 50% by weight or less, preferably 20%. It is contained in an amount of not more than wt%, more preferably not more than 10 wt%.

  After forming a composition for forming a hole transport layer containing a crosslinkable compound at such a concentration on the lower layer (usually the hole injection layer 3), the composition is crosslinked by heating and / or irradiation with electromagnetic energy such as light. Are crosslinked to form a network polymer compound.

Conditions such as temperature and humidity during film formation are the same as those during the wet film formation of the hole injection layer 3.
The heating method after film formation is not particularly limited. As heating temperature conditions, it is 120 degreeC or more normally, Preferably it is 400 degrees C or less.
The heating time is usually 1 minute or longer, preferably 24 hours or shorter. The heating means is not particularly limited, and means such as placing a laminated body having a deposited layer on a hot plate or heating in an oven is used. For example, conditions such as heating on a hot plate at 120 ° C. or more for 1 minute or more can be used.

  In the case of irradiation with electromagnetic energy such as light, a method of irradiating directly using an ultraviolet / visible / infrared light source such as an ultra-high pressure mercury lamp, a high-pressure mercury lamp, a halogen lamp, an infrared lamp, etc. Examples include a mask aligner and a method of irradiation using a conveyor type light irradiation device. In electromagnetic energy irradiation other than light, for example, there is a method of irradiation using a device that irradiates a microwave generated by a magnetron, a so-called microwave oven. As the irradiation time, it is preferable to set conditions necessary for reducing the solubility of the film, but irradiation is usually performed for 0.1 seconds or longer, preferably 10 hours or shorter.

  Heating and irradiation of electromagnetic energy such as light may be performed individually or in combination. When combined, the order of implementation is not particularly limited.

  The film thickness of the hole transport layer 4 thus formed is usually 5 nm or more, preferably 10 nm or more, and usually 300 nm or less, preferably 100 nm or less.

{Light emitting layer}
When the hole injection layer 3 or the hole transport layer 4 is provided, the light emitting layer 5 is provided on the hole transport layer 4. The light emitting layer 5 is a layer that is excited by recombination of holes injected from the anode 2 and electrons injected from the cathode 9 between electrodes to which an electric field is applied, and becomes a main light emitting source.

  The light emitting layer 5 contains at least a material having a light emitting property (light emitting material) as a constituent material, and preferably a compound having a hole transporting property (hole transporting compound) or an electron transport. A compound (electron transporting compound) having the following properties: A light emitting material may be used as a dopant material, and a hole transporting compound, an electron transporting compound, or the like may be used as a host material.

  The organic electroluminescent element of the present invention is a layer in which the light emitting layer 5 is formed by a wet film forming method, and contains an organic compound having an anthracene ring as a partial structure.

  Since the light emitting layer 5 is a layer formed by a wet film forming method, it is possible to cope with an increase in area of the organic electroluminescent element, and the light emitting layer 5 includes an organic compound having an anthracene ring as a partial structure. As a result, the light emission efficiency is high and the charge transport speed is increased. The organic compound having an anthracene ring as the partial structure is preferably a charge transporting compound contained as a host material in the light emitting layer 5 from the viewpoint of light emission efficiency.

  In order to form the light emitting layer 5 by the wet film formation method, a material used for the light emitting layer 5, that is, a light emitting material and a charge transporting material described later are dissolved in an appropriate solvent to prepare a composition for forming the light emitting layer. Then, wet film formation is performed using this.

  The solid content concentration of the light emitting material, charge transporting material, etc. in the composition for forming a light emitting layer is usually 0.01% by weight or more and usually 70% by weight or less. If this concentration is too large, film thickness unevenness may occur, and if it is too small, defects may occur in the film.

  After wet-deposition of the composition for forming a light emitting layer, the resulting coating film is dried and the solvent is removed to form a light emitting layer. Specifically, it is the same as the method described in the formation of the hole injection layer. The method of the wet film forming method is not limited as long as the effect of the present invention is not significantly impaired, and any of the methods described above can be used.

  The thickness of the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 3 nm or more, preferably 5 nm or more, and usually 200 nm or less, preferably 100 nm or less. If the thickness of the light emitting layer 5 is too thin, defects may occur in the film, and if it is too thick, the driving voltage may increase.

  Hereinafter, the light emitting material, the charge transporting material, the solvent and the like used for the preparation of the composition for forming the light emitting layer will be described.

<Light emitting material>
A light emitting material mainly refers to a component that emits light, and corresponds to a dopant component in an organic EL device. In the amount of light emitted from the light emitting layer (unit: cd / m 2 ), it is usually 10 to 100%, preferably 20 to 100%, more preferably 50 to 100%, and most preferably 80 to 100%. Is identified as luminescent material.

  In the present invention, the light emitting material is a low molecular compound having a molecular weight of usually 10,000 or less, preferably 5,000 or less, for example, 500 to 2,000, and has high solubility in adapting to the formation of a light emitting layer by a wet film forming method. It is preferable because purity is easily increased.

The light emitting material is particularly preferably a compound represented by the following formula (1) (hereinafter, this compound may be referred to as “aromatic amine compound (1)”). Among the aromatic amine compounds (1), Ar 35 is preferably a group derived from a chrysene ring.

(In formula (1), Ar 31 to Ar 35 each independently represents an aromatic hydrocarbon group which may have a substituent.)

In the above formula (1), examples of the aromatic hydrocarbon group represented by Ar 31 to Ar 35 include benzene rings, naphthalene rings, phenanthrene rings, anthracene rings, pyrene rings, chrysene rings, naphthacene rings, benzophenanthrene rings, and the like. Or the group derived from the condensed ring formed by condensing 2-6 pieces of a benzene ring is mentioned. Among these, in particular, Ar 31 , Ar 32 , Ar 33 , and Ar 34 are each independently preferably a group derived from a benzene ring, naphthalene ring, or phenanthrene ring, particularly a group derived from a benzene ring. Is preferred. In addition, Ar 35 is preferably a group derived from a chrysene ring or a pyrene ring, particularly preferably a group derived from a chrysene ring in terms of emission wavelength. When Ar 35 is a group derived from a chrysene ring, there are no particular restrictions on the bonding positions of —NAr 31 Ar 32 and —NAr 33 Ar 34 , but the 6-position, 12-position, 2-position, 5-position, 5-position and 11 The position is preferred, particularly the 6th and 12th positions. That is, the formula (1) is preferably represented by the following formula (1 ′).

(In formula (1 ′), Ar 31 to Ar 34 have the same meanings as in formula (1).)

The aromatic hydrocarbon group of Ar 31 to Ar 35 may further have a substituent. The molecular weight of the substituent is usually 400 or less, preferably about 250 or less. As the substituent, an alkyl group, an alkenyl group, an alkoxy group, an aromatic hydrocarbon group, an aromatic heterocyclic group and the like are preferable, and an alkyl group of a lipophilic substituent is particularly preferable.

When Ar 31 to Ar 34 have a substituent, the substitution position may be para-position, meta-position, meta-position and para-position di-substitution, or meta-position di-substitution with respect to the nitrogen atom substitution position. The para position is particularly preferable.

In addition, when Ar 35 has a substituent, the substitution position is preferably a benzene ring in which -NAr 31 Ar 32 and -NAr 33 Ar 34 are not substituted. In particular, when Ar 35 is a chrysene ring, it is preferable to have substituents at the 4-position and 10-position, and when Ar 35 is a pyrene ring, it has substituents at the 1, 3-position, 6-position and 8-position. It is preferable.

Examples of the aromatic amine compound (1) suitable for the present invention include the following compounds, but are not limited thereto. In the following exemplary formula, “Me” represents a methyl group, “Et” represents an ethyl group, “ t Bu” represents a t-butyl group, “ n Bu” represents an n-butyl group, and “Ph” represents Represents a phenyl group;

  One of these aromatic amine compounds (1) may be used alone, or two or more thereof may be mixed and used.

  The light emitting layer according to the present invention may contain other light emitting materials other than the aromatic amine compound (1) as a light emitting material.

  Other light emitting materials are not limited as long as they are usually used as light emitting materials for organic electroluminescent elements. For example, a fluorescent material or a phosphorescent material may be used, but a phosphorescent material is preferable from the viewpoint of internal quantum efficiency. In addition, a fluorescent material may be used for the blue light emitting material, and a phosphorescent light emitting material may be used for the green light emitting material and the red light emitting material.

  As the light emitting material, for the purpose of improving the solubility in a solvent, a material in which the symmetry or rigidity of the molecule is reduced or a lipophilic substituent such as an alkyl group is introduced is used. preferable.

  Hereinafter, examples of the fluorescent light emitting material among the light emitting materials will be described, but the fluorescent light emitting material is not limited to the following examples.

  Examples of the fluorescent light-emitting material (blue fluorescent dye) that emits blue light include naphthalene, chrysene, perylene, pyrene, anthracene, coumarin, p-bis (2-phenylethenyl) benzene, and derivatives thereof. Of these, anthracene, chrysene, pyrene, and derivatives thereof are preferable.

Examples of the fluorescent light-emitting material (green fluorescent dye) that gives green light emission include aluminum complexes such as quinacridone, coumarin, Al (C 9 H 6 NO) 3, and derivatives thereof.

  Examples of the fluorescent material that gives yellow light (yellow fluorescent dye) include rubrene, perimidone and derivatives thereof.

  Examples of fluorescent light-emitting materials (red fluorescent dyes) that emit red light include DCM (4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyrene) -4H-pyran) -based compounds, benzopyran, and rhodamine. , Xanthenes such as benzothioxanthene and azabenzothioxanthene, and derivatives thereof.

  As the phosphorescent material, for example, a long-period type periodic table (hereinafter referred to as a long-period type periodic table when referred to as “periodic table” unless otherwise specified) is selected from the seventh to eleventh groups. A Werner complex or an organometallic complex containing a metal as a central metal.

  Preferred examples of the metal selected from Groups 7 to 11 of the periodic table include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold. Among these, iridium or platinum is more preferable.

  As the ligand of the complex, a ligand in which a (hetero) aryl group such as a (hetero) arylpyridine ligand or a (hetero) arylpyrazole ligand and a pyridine, pyrazole, phenanthroline, or the like is connected is preferable. A pyridine ligand and a phenylpyrazole ligand are preferable. Here, (hetero) aryl represents an aryl group or a heteroaryl group.

  Specific examples of the phosphorescent material include tris (2-phenylpyridine) iridium, tris (2-phenylpyridine) ruthenium, tris (2-phenylpyridine) palladium, bis (2-phenylpyridine) platinum, tris (2- Phenylpyridine) osmium, tris (2-phenylpyridine) rhenium, octaethyl platinum porphyrin, octaphenyl platinum porphyrin, octaethyl palladium porphyrin, octaphenyl palladium porphyrin, and the like.

  In addition, as for the other luminescent material mentioned above, only 1 type may be used and 2 or more types may be used together by arbitrary combinations and ratios.

  The molecular weight of the compound used as the light emitting material including the above-mentioned aromatic amine compound (1) is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 10,000 or less, preferably 5000 or less, more preferably 4000. In the following, it is more preferably 3000 or less, and usually 100 or more, preferably 200 or more, more preferably 300 or more, and still more preferably 400 or more. If the molecular weight of the luminescent material is too small, the heat resistance will be significantly reduced, gas generation will be caused, the film quality will be reduced when the film is formed, or the morphology of the organic electroluminescent element will be changed due to migration, etc. Sometimes come. On the other hand, if the molecular weight of the luminescent material is too large, it tends to be difficult to purify the organic compound of the luminescent material, or it may take time to dissolve in the solvent.

<Charge transport material>
In the organic electroluminescent element, the light emitting material preferably emits light upon receiving electric charge or energy from a charge transporting host material. Therefore, the light emitting layer preferably contains a charge transporting material such as that used as the host material in addition to the light emitting material. Examples of the charge transporting material include a hole transporting compound (hole transporting material) and an electron transporting compound (electron transporting material).

  Here, examples of the charge transporting material include aromatic amine compounds, phthalocyanine compounds, porphyrin compounds, thiophene compounds, benzylphenyl compounds, fluorene compounds, hydrazone compounds, silazane compounds, and silanamine compounds. Phosphamine compounds, quinacridone compounds, triphenylene compounds, carbazole compounds, pyrene compounds, anthracene compounds, phenanthroline compounds, quinoline compounds, pyridine compounds, triazine compounds, oxadiazole compounds, imidazole compounds Etc.

  More specifically, two or more condensed aromatic rings containing two or more tertiary amines represented by 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl Aromatic amine compounds having a starburst structure such as aromatic amine compounds substituted with nitrogen atoms (Japanese Patent Laid-Open No. 5-234681), 4,4 ′, 4 ″ -tris (1-naphthylphenylamino) triphenylamine Compound (Journal of Luminescence, 1997, Vol. 72-74, pp. 985), an aromatic amine compound composed of a tetramer of triphenylamine (Chemical Communications, 1996, pp. 2175), 2, 2 ′ , 7,7'-tetrakis- (diphenylamino) -9,9'-spirobifluorene Orenic compounds (Synthetic Metals, 1997, Vol. 91, pp. 209), 2,5-bis (1-naphthyl) -1,3,4-oxadiazole (BND), 2,5-bis (6 '-(2', 2 "-bipyridyl))-1,1-dimethyl-3,4-diphenylsilole (PyPySPyPy), bathophenanthroline (BPhen), 2,9-dimethyl-4,7-diphenyl-1,10 -Phenanthroline (BCP, bathocuproine), 2- (4-biphenylyl) -5- (p-tertiarybutylphenyl) -1,3,4-oxadiazole (tBu-PBD), 4,4'-bis (9 -Carbazole) -biphenyl (CBP) and the like.

  In addition, examples of the charge transporting material include the hole transporting compound and the electron accepting compound exemplified as the constituent material of the hole injection layer 3 described above.

The molecular weight of the charge transporting material is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 10,000 or less, preferably 5000 or less, more preferably 4000 or less, still more preferably 3000 or less, and usually 100 or more, preferably Is 200 or more, more preferably 300 or more, and still more preferably 400 or more.
If the molecular weight of the charge transporting material is too small, the glass transition temperature, melting point, decomposition temperature, etc. are likely to be lowered as in the case of the luminescent material, the heat resistance of the formed luminescent layer is significantly reduced, and recrystallization or In some cases, the film quality is deteriorated due to molecular migration or the like, and the impurity concentration is increased due to thermal decomposition of the material.
On the other hand, if the molecular weight of the charge transporting material is too large, the solubility of the material in the solvent becomes too small depending on the type of the solvent used in the preparation of the composition for forming the light emitting layer, and for example, purification in the material manufacturing process becomes difficult. Problems such as high impurity concentration, which may reduce the luminous efficiency and durability of the organic electroluminescence device, or where a thin film is not formed during wet film formation, or the formed thin film becomes too thin In some cases, a desired function cannot be sufficiently obtained, such as generation of black spots or a short circuit in the finally obtained device.

  In the present invention, the light emitting layer may contain an organic compound having an anthracene ring as a partial structure as a charge transporting compound (hereinafter, this compound may be referred to as an “anthracene charge transporting compound”). preferable.

  The anthracene charge transporting compound used in the present invention has an anthracene ring, and preferably has a molecular weight within the above-mentioned preferred molecular weight range.

  Examples of the anthracene charge transporting compound used in the present invention include the following, but are not limited to those exemplified below.

  In the present invention, only one kind of charge transporting material such as an anthracene charge transporting compound may be used, or two or more kinds may be used in any combination and ratio.

(solvent)
The solvent used in the composition for forming a light emitting layer is not particularly limited as long as it is a solvent that dissolves solutes such as the above-described light emitting materials and charge transporting materials satisfactorily. Aromatic hydrocarbons such as chlorobenzene, dichlorobenzene, and trichlorobenzene; 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene Aromatic ethers such as 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole; phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, n-butyl benzoate, etc. Aromatic esters of cyclohexanone, chic Ketones having an alicyclic ring such as octanone; Aliphatic ketones such as methyl ethyl ketone and dibutyl ketone; Alcohols having an alicyclic ring such as methyl ethyl ketone, cyclohexanol and cyclooctanol; Aliphatic alcohols such as butanol and hexanol; Ethylene glycol dimethyl ether and ethylene glycol diethyl Aliphatic ethers such as ether and propylene glycol-1-monomethyl ether acetate (PGMEA); aliphatic esters such as ethyl acetate, n-butyl acetate, ethyl lactate and n-butyl lactate can be used. Of these, aromatic hydrocarbons such as toluene, xylene, methicylene, cyclohexylbenzene, tetralin and the like are preferable in that they have low water solubility and are not easily altered. These may use only 1 type and may use it as 2 or more types of mixed solvents.

  Since organic electroluminescent devices use many materials such as cathodes that deteriorate significantly due to moisture, the presence of moisture in the composition causes moisture to remain in the dried film, degrading the device characteristics. The possibility is considered and it is not preferable.

  Examples of the method for reducing the amount of water in the composition include dehydration of the solvent in advance by distillation or use of a desiccant, nitrogen gas sealing, 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, the composition for forming a light emitting layer contains, for example, a solvent having a water solubility at 25 ° C. of 1% by weight or less, preferably 0.1% by weight or less, of 10% by weight or more in the composition. It is preferable to do.

  Further, in order to reduce a decrease in film formation stability due to evaporation of the solvent from the composition during wet film formation, the boiling point is 100 ° C. or more, preferably 150 ° C. as the solvent of the composition for forming the light emitting layer. As described above, it is more effective to use a solvent having a boiling point of 200 ° C. or higher. In order to obtain a more uniform film, it is necessary for the solvent to evaporate from the liquid film immediately after the film formation at an appropriate rate. For this purpose, the boiling point is usually 80 ° C. or higher, preferably the boiling point is 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 that satisfies the above-mentioned conditions, ie, solute solubility, evaporation rate, and water solubility conditions, may be used alone. However, if a solvent that satisfies all the conditions cannot be selected, two or more solvents may be mixed. It can also be used.

<Other ingredients>
In the light emitting layer, in addition to the light emitting material and charge transporting material described above, coating property improving agents such as leveling agents, antifoaming agents, thickeners, etc., charge transporting aids such as electron accepting compounds and electron donating compounds In addition, a binder resin or the like may be contained. The content of these other components in the composition for forming the light-emitting layer is a viewpoint that the charge transfer of the thin film to be formed is not significantly inhibited, the light emission of the light-emitting material is not inhibited, and the film quality of the thin film is not deteriorated. Therefore, it is usually 50% by weight or less.

<Constituent component content in light emitting layer>
The content ratio of the light emitting material in the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.05% by weight or more and usually 35% by weight or less. If the amount of the light emitting material is too small, uneven light emission may occur. If the amount is too large, the light emission efficiency may be reduced. In addition, when using together 2 or more types of luminescent material, it is made for the total content of these to be contained in the said range.

  When the light emitting layer according to the present invention contains the above-mentioned aromatic amine compound (1) and other light emitting materials as the light emitting material, the effect of the present invention by using the aromatic amine compound (1) is ensured. In order to obtain it, it is preferable that 0.1% by weight or more, particularly 1% by weight or more of the light emitting material is the aromatic amine compound (1). However, if the amount is too large, the light emission efficiency and the life may be reduced. Therefore, the aromatic amine compound (1) in the light emitting material is preferably 50% by weight or less, particularly preferably 30% by weight or less.

  Moreover, when the light emitting layer 5 contains an electron transporting material, the content ratio of the electron transporting material in the light emitting layer 5 is arbitrary as long as the effects of the present invention are not significantly impaired. 65% by weight or less. If the amount of the electron transporting material in the light emitting layer is too small, it may be easily affected by a short circuit, and if it is too large, the film thickness may be uneven. In addition, when using together 2 or more types of electron transport materials in a light emitting layer, it is made for the total content of these to be contained in the said range.

  Further, when the light emitting layer 5 contains a hole transporting material, the ratio of the hole transporting material in the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.1% by weight or more, Usually 65% by weight or less. If the hole transporting material in the light emitting layer is too small, it may be easily affected by a short circuit, and if it is too large, film thickness unevenness may occur. In addition, when using together 2 or more types of hole transportable materials in a light emitting layer, it is made for the total content of these to be contained in the said range.

  The weight ratio of the light emitting material / charge transporting material in the light emitting layer is usually 0.1 / 99.9 or more, more preferably 0.5 / 99.5 or more, and further preferably 1/99. Or more, most preferably 2/98 or more, usually 50/50 or less, more preferably 40/60 or less, still more preferably 30/70 or less, and most preferably 20/80 or less. is there. If this ratio falls below the lower limit or exceeds the upper limit, the luminous efficiency may be significantly reduced.

  When the light emitting layer according to the present invention includes the above-described anthracene charge transporting compound and other charge transporting materials as the charge transporting material, the effect of the present invention by using the anthracene charge transporting compound is ensured. In order to obtain it, it is preferable that 50% by weight or more, particularly 70% by weight or more, especially 80% by weight or more of the charge transporting material is an anthracene type charge transporting compound.

{Hole blocking layer}
A hole blocking layer 6 may be provided between the light emitting layer 5 and an electron injection layer 8 described later. The hole blocking layer 6 is a layer 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 hole blocking layer 6 has a role of blocking holes moving from the anode 2 from reaching the cathode 9 and a role of efficiently transporting electrons injected from the cathode 9 toward the light emitting layer 5. Have

  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 for the hole blocking layer 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, distyrylbiphenyl derivatives, etc. Triazole derivatives such as styryl compounds (JP-A-11-242996), 3- (4-biphenylyl) -4-phenyl-5 (4-tert-butylphenyl) -1,2,4-triazole (JP-A-7 -41759), phenanthroline derivatives such as bathocuproine (JP-A-10-79297), and the like. That. Further, a compound having at least one pyridine ring substituted at positions 2, 4, and 6 described in International Publication No. 2005-022962 is also preferable as a material for the hole blocking layer 6.

  In addition, the material of the hole-blocking layer 6 may use only 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

  There is no restriction | limiting in the formation method of the hole-blocking layer 6. FIG. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.

  The thickness of the hole blocking layer 6 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less.

  A hole relaxation layer may be provided in place of the hole blocking layer.

{Electron transport layer}
An electron transport layer 7 may be provided between the light emitting layer 5 and an electron injection layer 8 described later.

  The electron transport layer 7 is provided for the purpose of further improving the light emission efficiency of the device, and efficiently transports electrons injected from the cathode 9 between the electrodes to which an electric field is applied in the direction of the light emitting layer 5. Formed from a compound capable of

  As an electron transport compound used for the electron transport layer 7, usually, the electron injection efficiency from the cathode 9 or the electron injection layer 8 is high, and the injected electrons are transported efficiently with high electron mobility. The compound which can be used is used. Examples of the compound 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 , Distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (US Pat. No. 5,645,948), quinoxaline compounds ( JP-A-6-207169), phenanthroline derivative (JP-A-5-331459), 2-t-butyl-9,10-N, N'-dicyanoanthraquinonediimine, n-type hydrogenated amorphous silicon carbide , N-type zinc sulfide, n-type zinc Such as emissions of zinc, and the like.

  In the present invention, the electron transport layer preferably contains an organic compound having an anthracene ring and / or a phenanthroline ring as a partial structure (hereinafter, such a compound is referred to as “aromatic polycyclic compound”). This produces an effect that electrons are efficiently injected into the light emitting layer.

  Examples of such aromatic polycyclic compounds include, but are not limited to, the following.

  Among these, as the aromatic polycyclic compound, those having both an anthracene ring and a phenanthroline ring are preferable in terms of durability and high electron mobility.

  In addition, although the material of the electron carrying layer 7 may use only 1 type and may use 2 or more types together by arbitrary combinations and a ratio, an electron carrying layer and the above-mentioned aromatic polycyclic compound and In the case of including other electron transport layer materials, the content of the aromatic polycyclic compound in the electron transport layer is 80 in order to effectively exhibit the effect of using the aromatic polycyclic compound. It is preferable that the content be not less than 90% by weight, particularly not less than 90% by weight, and it is preferable that the electron transport layer is substantially formed of only an aromatic polycyclic compound.

  There is no restriction | limiting in the formation method of the electron carrying layer 7. FIG. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.

  The thickness of the electron transport layer 7 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 1 nm or more, preferably 5 nm or more, and usually 300 nm or less, preferably 100 nm or less.

{Electron injection layer}
The electron injection layer 8 plays a role of efficiently injecting 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. Examples include alkali metals such as sodium and cesium, and alkaline earth metals such as barium and calcium. Examples include lithium fluoride (LiF), magnesium fluoride (MgF 2 ), lithium oxide (Li 2 O), cesium carbonate (II) (CsCO 3 ), and the like (Applied Physics Letters, 1997, Vol. 70, pp. 152; Japanese Patent Laid-Open No. 10-74586; see I Organic EL Display and Organic EL Lighting Transactions on Electron Devices, 1997, Vol. 44, pp. 1245; SID 04 Digest, pp. 154, etc.). The film thickness is usually preferably from 0.1 nm to 5 nm.

  Furthermore, an organic electron transport compound 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, or rubidium ( (As described in JP-A-10-270171, JP-A-2002-1000047, JP-A-2002-1000048, etc.), it is possible to improve the electron injection / transport properties and achieve excellent film quality. preferable. In this case, the film thickness is usually 5 nm or more, preferably 10 nm or more, and is usually 200 nm or less, preferably 100 nm or less.

  In addition, the material of the electron injection layer 8 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  There is no restriction | limiting in the formation method of the electron injection layer 8. FIG. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.

{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.

  As the material of the cathode 9, the material used for the anode 2 can be used. However, in order to perform electron injection efficiently, a metal having a low work function is preferable. For example, tin, magnesium, indium, A suitable metal such as calcium, aluminum, 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.

  In addition, the material of the cathode 9 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  The film thickness of the cathode 9 is usually the same as that of the anode 2.

  Further, for the purpose of protecting the cathode 9 made of a low work function metal, it is preferable to further stack a metal layer having a high work function and stable to the atmosphere because the stability of the device is increased. For this purpose, for example, metals such as aluminum, silver, copper, nickel, chromium, gold and platinum are used. In addition, these materials may be used only by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

{Other layers}
The organic electroluminescent element of the present invention may have another configuration without departing from the gist thereof. For example, as long as the performance is not impaired, an arbitrary layer may be provided between the anode 2 and the cathode 9 in addition to the layers described above, and an arbitrary layer may be omitted. .

Examples of the layer that may be included include an electron blocking layer.
The electron blocking layer is provided between the hole injection layer 3 or the hole transport layer 4 and the light emitting layer 5 and prevents electrons moving from the light emitting layer 5 from reaching the hole injection layer 3. Thus, the probability of recombination of holes and electrons in the light emitting layer 5 is increased, the excitons generated are confined in the light emitting layer 5, and the holes injected from the hole injection layer 3 are efficiently collected. There is a role to transport in the direction of. In particular, when a phosphorescent material or a blue light emitting material is used as the light emitting material, it is effective to provide an electron blocking layer.

  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). Furthermore, in the present invention, when the light emitting layer 5 is formed as an organic layer according to the present invention by a wet film formation method, the electron blocking layer is also required to be compatible with the wet film formation. Examples of the material used for such an electron blocking layer include a copolymer of dioctylfluorene and triphenylamine typified by F8-TFB (International Publication No. 2004/084260).

  In addition, the material of an electron blocking layer may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  There is no restriction | limiting in the formation method of an electron blocking layer. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.

  Moreover, in the layer structure demonstrated above, it is also possible to laminate | stack components other than a board | substrate in reverse order. For example, in the case of the layer configuration of FIG. 1, the other components on the substrate 1 are the cathode 9, the electron injection layer 8, the electron transport layer 7, the hole blocking layer 6, the light emitting layer 5, the hole transport layer 4, the positive layer. The hole injection layer 3 and the anode 2 may be provided in this order.

  Furthermore, it is also possible to constitute the organic electroluminescent element according to the present invention by laminating components other than the substrate between two substrates, at least one of which is transparent.

Further, a structure in which a plurality of components (light emitting units) other than the substrate are stacked in a plurality of layers (a structure in which a plurality of light emitting units are stacked) may be employed. In that case, (when the anode is ITO, the cathode is Al, these two layers) interfacial layer between the respective stages (between emission units) Alternatively, for example, a charge consisting of five vanadium oxide (V 2 O 5), etc. When a generation layer (Carrier Generation Layer: CGL) is provided, a barrier between steps is reduced, which is more preferable from the viewpoint of light emission efficiency and driving voltage.

  Furthermore, the organic electroluminescent device according to the present invention may be configured as a single organic electroluminescent device, or may be applied to a configuration in which a plurality of organic electroluminescent devices are arranged in an array. You may apply to the structure by which the cathode is arrange | positioned at XY matrix form.

  Each layer described above may contain components other than those described as materials unless the effects of the present invention are significantly impaired.

[Organic EL display and organic EL lighting]
The organic electroluminescent element of the present invention is used for organic EL displays and organic EL lighting. The organic electroluminescent device obtained by the present invention is described in, for example, “Organic EL Display” (Ohm, August 20, 2004, written by Shizushi Tokito, Chiba Adachi, and Hideyuki Murata). An organic EL display and organic EL illumination can be formed by the method.

  EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited to description of a following example, unless the summary is exceeded.

[Example 1]
The organic electroluminescent element shown in FIG. 1 was produced.

  An indium tin oxide (ITO) transparent conductive film deposited on a glass substrate 1 with a thickness of 120 nm (manufactured by Sanyo Vacuum Co., Ltd., sputtered film product) using ordinary photolithography technology and hydrochloric acid etching Then, the anode 2 was formed by patterning into stripes having a width of 2 mm. The patterned ITO substrate is cleaned in the order of ultrasonic cleaning with an aqueous surfactant solution, water cleaning with ultrapure water, ultrasonic cleaning with ultrapure water, and water cleaning with ultrapure water, followed by drying with compressed air, and finally UV irradiation. Ozone cleaning was performed.

  First, a hole-transporting polymer compound having a repeating structure represented by the following structural formula (P1) (weight average molecular weight: 87000, Mw / Mn: 1.8), an electron accepting that is an ion pair represented by the structural formula (A1) A composition for forming a hole injection layer was prepared, which contains an organic compound, 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) borate and ethyl benzoate as a solvent. Compound (P1) and compound (A1) were in a weight ratio of (P1) :( A1) = 10: 4, and the total concentration of compound (P1) and compound (A1) in the composition was 2.8% by weight. . This composition was wet-formed by spin coating on the anode 2 at a spinner rotation speed of 1500 rpm and a spinner rotation time of 30 seconds. After the film formation, the film was crosslinked by heating at 230 ° C. for 3 hours to form a uniform thin film of the hole injection layer 3 having a thickness of 30 nm.

  Next, a composition for forming a hole transport layer containing a compound represented by the following structural formula (H1) as a hole transporting compound and cyclohexylbenzene as a solvent was prepared. The concentration of the compound (H1) in the composition was 0.4% by weight. This composition was wet-formed by spin coating on the hole injection layer 3 in nitrogen at a spinner rotation speed of 1500 rpm and a spinner rotation time of 30 seconds. After film formation, the film was crosslinked by heating at 230 ° C. for 60 minutes in nitrogen to form a uniform thin film of the hole transport layer 4 having a thickness of 20 nm.

  Next, the following compound (A) having an anthracene ring as a partial structure as a charge transporting compound (host material), the following compound (D-1) as a light emitting material (dopant material), and cyclohexylbenzene as a solvent A forming composition was prepared. The compound (A) and the compound (D-1) in the composition have a weight ratio of (A) :( D-1) = 10: 1, and the compound (A) and the compound (D− The total concentration of 1) was 3.1% by weight.

  This composition was wet-formed by spin coating on the hole transport layer 4 at a spinner rotation speed of 1500 rpm and a spinner rotation time of 30 seconds. After the film formation, the film was dried by heating at 100 ° C. for 60 minutes to form a uniform thin film of the light emitting layer 5 having a thickness of 40 nm.

  On the obtained light emitting layer 5, the compound (HB-1) of the following structure was formed into a film thickness of 10 nm as the hole-blocking layer 6 by the vacuum evaporation method.

Next, a compound (ET-24) having the following structure having an anthracene ring and a phenanthroline ring as a partial structure was formed as an electron transport layer 7 on the hole blocking layer 6 so as to have a film thickness of 30 nm.

  Thereafter, by the vacuum evaporation method, the ITO stripe as the anode 2 is formed so that lithium fluoride (LiF) has a thickness of 0.5 nm as the electron injection layer 8 and aluminum as the cathode 9 has a thickness of 80 nm. The stripes were stacked in a 2 mm width with an orthogonal shape.

  As described above, an organic electroluminescent element having a light emitting area portion having a size of 2 mm × 2 mm was obtained.

It was confirmed that blue light emission having an EL peak wavelength of 470 nm was obtained from this device.
Table 1 summarizes the characteristics and driving life of the organic electroluminescent element obtained in this example and Comparative Example 1 described later.
The life ratio LT in Table 1 is the time required for the front luminance to drop to 70% of the initial luminance when the device was driven at a constant current at an initial front luminance of 2000 cd / m 2 under room temperature conditions. In this example, the result of Example 1 is compared as 1. The CIE chromaticity is a CIE chromaticity coordinate having a front luminance of 10 to 1000 cd / cm 2 .

[Comparative Example 1]
An organic electroluminescent element was produced in the same manner as in Example 1 except that the compound (ET-24) used for the electron transport layer was changed to the following compound (ET-1). The results are shown in Table 1.

[Reference Example 1]
An organic electroluminescent element was produced in the same manner as in Example 1 except that the light emitting layer was formed as follows.
Contains the following compounds (H-1) and (H-2) as charge transporting compounds (host materials), the following compounds (D-2) and (D-3) as light emitting materials (dopant materials), and cyclohexylbenzene as a solvent A composition for forming a light emitting layer was prepared. Each compound in the composition was (H-1) :( H-2) :( D-2) :( D-3) = 25: 75: 3: 7 by weight ratio, and the total concentration of these compounds Was 4.5% by weight. This composition was wet-formed by spin coating on the hole transport layer 4 at a spinner rotation speed of 1500 rpm and a spinner rotation time of 30 seconds. After the film formation, the film was dried by heating at 100 ° C. for 60 minutes, whereby a uniform thin film of the light emitting layer 5 having a film thickness of 60 nm was formed.

From this element, it was confirmed that red light emission having an EL peak wavelength of 629 nm was obtained.
Table 2 summarizes the characteristics and drive life of the organic electroluminescent elements obtained in Reference Example 1 and Reference Example 2 described later.
Table 2 life ratio LT in the elements, under room temperature conditions, when the constant current drive at an initial front brightness 2000 cd / m 2, and measures the time in which the front luminance required until drops to 70% of the initial luminance, It is a value compared with the result of Reference Example 1 as 1. The CIE chromaticity is a CIE chromaticity coordinate having a front luminance of 10 to 1000 cd / cm 2 .

[Reference Example 2]
An organic electroluminescent device was produced in the same manner as in Reference Example 1 except that the compound (ET-24) used in the electron transport layer was changed to the compound (ET-1). The results are shown in Table 2.

Tables 1 and 2 show the following.
Compared to Example 1 using an organic compound having an anthracene ring as a partial structure in the light emitting layer and using an organic compound having an anthracene ring and a phenanthroline ring in the electron transport layer, the organic compound having an anthracene ring as a partial structure in the light emitting layer However, Comparative Example 1 using an organic compound having neither an anthracene ring nor a phenanthroline ring in the electron transport layer has a short lifetime of 60%.
In addition, since there is no difference in device life between Reference Example 1 and Reference Example 2, using only an organic compound having an anthracene ring and a phenanthroline ring in the electron transport layer does not improve the device life, and improves the device life. Indicates that it is necessary to use an organic compound having an anthracene ring and / or a phenanthroline ring in the electron transport layer, and to use an organic compound having an anthracene ring as a partial structure in the light emitting layer.
From this result, the device lifetime can be improved by using an organic compound having an anthracene ring as a partial structure in the light emitting layer and using an organic compound having an anthracene ring and / or a phenanthroline ring as a partial structure in the electron transport layer. I understand.

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 10 Organic electroluminescent device

Claims (10)

  1. An organic electroluminescent device having an anode, a light emitting layer, an electron transport layer and a cathode on a substrate,
    The light emitting layer is a layer formed by a wet film formation method, and contains an organic compound having an anthracene ring as a partial structure,
    The electron transport layer contains an organic compound having an anthracene ring and / or a phenanthroline ring as a partial structure.
  2.   The organic electroluminescence device according to claim 1, wherein the electron transport layer contains an organic compound having an anthracene ring and a phenanthroline ring as a partial structure.
  3.   3. The organic electroluminescent element according to claim 1, wherein the light emitting layer contains a light emitting material, and the light emitting material is a low molecular compound.
  4. 4. The organic electroluminescent element according to claim 3, wherein the luminescent material is a compound represented by the following formula (1).
    (In formula (1), Ar 31 to Ar 35 each independently represents an aromatic hydrocarbon group which may have a substituent.)
  5. In the said Formula (1), Ar < 35 > is group derived from a chrysene ring, The organic electroluminescent element of Claim 4 characterized by the above-mentioned.
  6.   The hole injection layer is provided between the anode and the light emitting layer, and the hole injection layer is a layer that does not contain sulfonic acids. Organic electroluminescent device.
  7.   The organic electroluminescence device according to claim 6, wherein the hole injection layer is a layer containing an ion pair.
  8.   The organic electroluminescence device according to claim 6 or 7, wherein the hole injection layer is a layer formed by a wet film formation method.
  9.   An organic EL display using the organic electroluminescent element according to claim 1.
  10.   Organic EL lighting using the organic electroluminescent element according to any one of claims 1 to 8.
JP2009042505A 2009-02-25 2009-02-25 Organic electroluminescence element, organic el display and organic el lighting Pending JP2010199296A (en)

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