JP2010245060A - Organic el device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL device capable of reducing a light-emitting wavelength of a blue color and extending a life. <P>SOLUTION: A luminous layer of the organic EL device is composed of a host including chrysene and a dopant including benzidine, thus increasing the energy gap of the dopant and lowering the affinity level of the dopant as compared with that of the host, and hence reducing the light-emitting wavelength of blue color and extending life in the organic EL device. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an organic EL element.

An organic electroluminescent device (organic EL device) that has an organic light emitting layer between an anode and a cathode, and emits light from exciton energy generated by recombination of holes and electrons injected into the organic light emitting layer It has been known.
Such an organic EL element is expected as a light emitting element excellent in luminous efficiency, image quality, power consumption, and thin design, taking advantage of the self-luminous element.

In utilizing a light emitting material in an organic EL device, a doping method is known in which a host material is doped with a dopant material.
In order to efficiently generate excitons from the injected energy and efficiently link the exciton energy to light emission, a configuration is adopted in which the exciton energy generated in the host is transferred to the dopant and light emission is obtained from the dopant. The
At this time, in order to perform intermolecular energy transfer from the host to the dopant, the energy gap Eg _{H of the} host needs to be larger than the energy gap Eg _{D of the} dopant.

However, in recent years, there is no combination of such a deep blue light-emitting dopant and an optimal host material while a deep blue light-emitting color with a shorter wavelength is required.
Patent Document 1 discloses a blue element using a host material having a wide energy gap and an arylamine-based dopant. However, since the combination is not appropriate, there is a disadvantage that the lifetime is extremely short. In addition, even if there are several types of dopant materials whose emission colors have been shortened, even if these are doped into a commonly used anthracene host material, energy transfer from the host to the dopant does not occur, and light emission from the dopant occurs. There was a problem that could not be obtained.

Japanese Patent Publication No. 2004-75567

  An object of the present invention is to solve such a problem, and is to provide an organic EL element capable of shortening the blue emission wavelength and extending the lifetime.

The inventors of the present invention have intensively studied to solve such problems, and have found that a dopant containing benzidine or chrysene can be applied as a dopant having a large energy gap capable of shortening the blue emission wavelength.
And in order to make such a dopant emit light, it has been found that if a host containing chrysene is used as a host having a higher affinity level and a larger energy gap than this dopant, the lifetime can be extended.

Here, the energy gap refers to the difference between the conduction level and the valence electron level, and can be defined by, for example, a value measured from the absorption edge of the absorption spectrum in benzene.
Specifically, the absorption spectrum is measured using a commercially available visible ultraviolet spectrophotometer, and the absorption spectrum is calculated from the wavelength at which the absorption spectrum starts to rise.
However, the value may be any value that can be defined as an energy gap without departing from the gist of the present invention, regardless of the above-mentioned rules.

The affinity level Af (electron affinity) refers to energy released or absorbed when one electron is given to a molecule of the material, and is defined as positive in the case of emission and negative in the case of absorption.
The affinity level Af is defined by the ionization potential Ip and the optical energy gap Eg as follows.
Af = Ip-Eg
Here, the ionization potential Ip means the energy required to remove and ionize electrons from the compound of each material. For example, in this application, measured by an ultraviolet photoelectron spectrometer (AC-3, Riken Instruments). Values can be used.
However, the value may be any value that can be defined as an affinity level without departing from the spirit of the present invention, regardless of the above-mentioned rules.

The present invention has been completed based on such findings.
That is, the organic EL device of the present invention is an organic EL device in which an organic thin film layer composed of one or more layers including at least a light emitting layer is sandwiched between a cathode and an anode. It consists of a host represented by the general formula (1) and a dopant represented by the following general formula (2).

In General formula (1), R < ¹ > -R < ¹² > represents a hydrogen atom or a substituent. However, at least one of R ^{1 to} R ¹² independently represents a substituted or unsubstituted aryl group having 6 to 60 nuclear carbon atoms.

In the general formula (2), Ar ^{1 to} Ar ⁴ each independently represents a substituted or unsubstituted aryl group having 6 to 14 nuclear carbon atoms.
L ₁ represents substituted or unsubstituted benzene, naphthalene, fluorene, or phenanthrene. p is an integer of 1 to 6 independently. When p is 2 or more, L ₁ may be the same or different. When p is 2 or more, L ₁ may be the same or different in the substitution position. s is 0 or 1.

  In the organic EL device of the present invention, the dopant may be represented by the following general formula (3) instead of the general formula (2).

In the general formula (3), Ar ^{5 to} Ar ⁸ each independently represents a substituted or unsubstituted phenyl group, naphthyl group, or phenanthrylene group. L ₂ and L ₃ each independently represent substituted or unsubstituted benzene, naphthalene, or phenanthrene.

  Furthermore, in the organic EL element of the present invention, the host is preferably represented by the following general formula (4).

In General formula (4), Ar < ⁹ >, Ar < ¹⁰ > represents the substituent in which a C5-C14 substituted or unsubstituted aryl group is comprised individually or in multiple combinations, respectively.

According to the inventions such as these, since the dopant containing benzidine or chrysene is applied as the dopant constituting the light emitting layer, and the inclusion of chrysene as the host is applied, the blue emission wavelength can be shortened and lengthened. An organic EL element capable of extending the life can be obtained.
In the present invention, the reason why the element lifetime is increased by the combination of the host material and the dopant material described in the claims is not necessarily clear, but is considered to be as follows.
Since the dopant material in the present invention is a blue light emitting material having a short wavelength, it has an arylamine in the structure.
As a result, the ionization potential is large and the energy gap is large, so that deep blue light emission with a shorter wavelength can be realized.
However, it is considered that the amine contained in the dopant does not have high resistance to electrons, and if the electron injection is directly performed at the time of driving the device, the molecule deteriorates and the lifetime is not reached.
In this regard, in the present invention, the affinity level of the host is set to be smaller than the affinity level of the dopant so that electrons are not easily injected directly into the dopant.
Thereby, deterioration of the dopant can be prevented to increase the element lifetime, and an element having a long lifetime can be realized while being able to emit light at a short wavelength.
Conventionally, it has been considered that a host material having an energy gap larger than that of the light emitting dopant may be selected as the host material of the light emitting dopant.
That is, it has been considered that a host material having a small affinity level and a large ionization potential as compared with a dopant may be selected.
Simply in such a configuration, when charge is injected into a host doped with a dopant, a proportion of the injected charge is injected directly into the dopant, not the host.
For example, considering the case of injecting electrons into the light emitting layer, electrons are also injected into a dopant having a higher affinity level than the host.
In particular, when the energy gap is wide for both the host and the dopant for shortening the wavelength, the gap from the electron transport layer to the host is large, and the dopant is more likely to inject electrons. .
For this reason, when a short-wavelength blue light-emitting dopant is simply doped into a wide-gap host, there arises a problem that the device lifetime becomes extremely short.
In this regard, in the present invention, the affinity level of the dopant is set to be smaller than the affinity level of the host, and a combination of the host and the dopant in which electrons are not easily injected directly into the dopant.
With such a configuration, an element having an epoch-making long life while realizing blue light emission with a shorter wavelength than the conventional one was realized.

In the present invention, the energy gap of the host of the light emitting layer is increased and the ionization potential Ip is also increased.
Then, the difference in Ip between the host material and the hole injecting / transporting layer becomes large, and it may be difficult to inject holes into the light emitting layer, and the driving voltage for obtaining sufficient luminance increases. There is a fear.
In such a case, it is preferable to relax the hole injection barrier by adding a charge injection auxiliary agent to the light emitting layer.
As such a charge injection auxiliary agent, a hole injection / transport material can be used.

  Hereinafter, embodiments of the present invention will be described.

[Configuration of organic EL element]
First, the element configuration of the organic EL element will be described.
As a typical element configuration of the organic EL element,
(1) Anode / light emitting layer / cathode (2) Anode / hole injection layer / light emitting layer / cathode (3) Anode / light emitting layer / electron injection layer / cathode (4) Anode / hole injection layer / light emitting layer / electron Injection layer / cathode (5) anode / organic semiconductor layer / light emitting layer / cathode (6) anode / organic semiconductor layer / electron barrier layer / light emitting layer / cathode (7) anode / organic semiconductor layer / light emitting layer / adhesion improving layer / Cathode (8) Anode / hole injection layer / hole transport layer / light emitting layer / electron injection layer / cathode (9) anode / insulating layer / light emitting layer / insulating layer / cathode (10) anode / inorganic semiconductor layer / insulating layer / Light emitting layer / insulating layer / cathode (11) anode / organic semiconductor layer / insulating layer / light emitting layer / insulating layer / cathode (12) anode / insulating layer / hole injection layer / hole transporting layer / light emitting layer / insulating layer / Cathode (13) Anode / insulating layer / hole injection layer / hole transport layer / light emitting layer / electron injection layer / cathode structure and the like.
The organic EL device of this embodiment includes at least an anode, a hole injection layer, a light emitting layer, an electron transport layer, and a cathode in this order.
Of these, the configuration of (8) is preferably used, but of course, it is not limited thereto.

(Translucent substrate)
The organic EL element is manufactured on a light-transmitting substrate. Here, the translucent substrate is a substrate that supports the organic EL element, and is preferably a smooth substrate having a light transmittance in the visible region of 400 to 700 nm of 50% or more.
Specifically, a glass plate, a polymer plate, etc. are mentioned.
Examples of the glass plate include soda lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz.
Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone.

(anode)
The anode of the organic EL element plays a role of injecting holes into the hole transport layer or the light emitting layer, and it is effective to have a work function of 4.5 eV or more. Specific examples of the anode material include indium tin oxide alloy (ITO), tin oxide (NESA), indium zinc oxide, gold, silver, platinum, copper, and the like. The anode is preferably a material having a small work function for the purpose of injecting electrons into the electron transport layer or the light emitting layer.
The anode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering.
Thus, when light emission from the light emitting layer is taken out from the anode, it is preferable that the transmittance of the anode for light emission is greater than 10%. The sheet resistance of the anode is preferably several hundred Ω / □ or less. Although the film thickness of the anode depends on the material, it is usually selected in the range of 10 nm to 1 μm, preferably 10 to 200 nm.

(Light emitting layer)
The light emitting layer of the organic EL element has the following functions.
That is,
(1) injection function; a function capable of injecting holes from the anode or hole injection layer when an electric field is applied, and a function of injecting electrons from the cathode or electron injection layer;
(2) Transport function; function to move injected charges (electrons and holes) by the force of electric field,
(3) Luminescent function; a function to provide a field for recombination of electrons and holes and connect this to light emission,
There is.
However, there may be a difference between the ease of hole injection and the ease of electron injection, and the transport capability represented by the mobility of holes and electrons may be large or small. It is preferable to move the charge.
As a method for forming the light emitting layer, for example, a known method such as an evaporation method, a spin coating method, or an LB method can be applied.
The light emitting layer is preferably a molecular deposited film.
Here, the molecular deposition film is a thin film formed by deposition from a material compound in a gas phase state or a film formed by solidification from a material compound in a solution state or a liquid phase state. Can be classified from a thin film (accumulated film) formed by the LB method according to a difference in an agglomerated structure and a higher-order structure and a functional difference resulting therefrom.
Further, as disclosed in JP-A-57-51781, a binder such as a resin and a material compound are dissolved in a solvent to form a solution, and then this is thinned by a spin coating method or the like. In addition, a light emitting layer can be formed.
Furthermore, the thickness of the light emitting layer is preferably 5 to 50 nm, more preferably 7 to 50 nm, and most preferably 10 to 50 nm. If the thickness is less than 5 nm, it is difficult to form a light emitting layer, and it may be difficult to adjust the chromaticity. If the thickness exceeds 50 nm, the driving voltage may increase.

In the organic EL device of the present embodiment, the light emitting layer is configured to include a host and a dopant.
And as a specific example of a host, the compound represented by the following general formula (5) is mentioned.

In General formula (5), R < ¹ > -R < ¹² > represents a hydrogen atom or a substituent. However, at least one of R ^{1 to} R ¹² independently represents a substituted or unsubstituted aryl group having 6 to 60 nuclear carbon atoms.

  Moreover, as a specific compound of General formula (5), the compound represented by the following General formula (6) is mentioned.

In the general formula (6), Ar ⁹ and Ar ¹⁰ each independently represent a substituent in which a substituted or unsubstituted aryl group having 5 to 14 carbon atoms is composed of one or more combinations.

  Furthermore, specific examples of the host include compounds represented by the following general formulas (7) to (11).

In the general formula (7), Ch represents a substituted or unsubstituted chrysene, and Ar ¹ and Ar ² are each independently composed of a substituted or unsubstituted aryl group having 5 to 14 nuclear carbon atoms, alone or in combination. The substituent to be used is shown. However, Ar ¹ ≠ Ar ² , and Ar ¹ and Ar ² do not include anthracene.

In the general formula (8), Ar ¹ and Ar ² each independently represent a substituent in which a substituted or unsubstituted aryl group having 5 to 14 nuclear carbon atoms is composed of a single or a plurality of combinations. However, Ar ¹ ≠ Ar ² , and Ar ¹ and Ar ² do not include anthracene. R ^{1 to} R ¹⁰ represent a hydrogen atom or a substituent.

In the general formula (9), Ar ³ is substituted or unsubstituted naphthalene, substituted or unsubstituted phenanthrene, and Ar ⁴ is a substituted or unsubstituted aryl group having 5 to 14 nuclear carbon atoms, alone or in combination. The constituent substituent is shown. R ^{1 to} R ¹¹ represent a hydrogen atom or a substituent. k is an integer of 1 to 4. When k is 2 or more, R ¹¹ may be the same or different.

In the general formula (10), Ar ⁴ and Ar ⁵ each independently represent a substituent in which a substituted or unsubstituted aryl group having 5 to 14 nuclear carbon atoms is composed of one or more combinations. However, Ar ⁴ ≠ Ar ⁵ , and Ar ⁴ and Ar ⁵ do not include anthracene. R ^{1 to} R ¹² represent a hydrogen atom or a substituent. k is an integer of 1 to 4. When k is 2 or more, R ¹¹ may be the same or different. l is an integer of 1-4. When l is 2 or more, R ¹² may be the same or different.

In the general formula (11), Ar ⁶ and Ar ⁷ each independently represent a substituent in which a substituted or unsubstituted aryl group having 5 to 14 nuclear carbon atoms is composed of a single or a plurality of combinations. However, Ar ⁶ ≠ Ar ⁷ and Ar ⁶ and Ar ⁷ do not include anthracene. R ^{21 to} R ³⁰ represent a hydrogen atom or a substituent.

Here, in the general formulas (7) and (8), Ar ¹ is preferably a substituted or unsubstituted naphthalene or a substituted or unsubstituted phenanthrene.
In the general formulas (8) to (11), at least one of R ^{1 to} R ¹⁰ or R ^{21 to} R ³⁰ is a substituted or unsubstituted aryl group having 5 to 14 nuclear carbon atoms. preferable.
Furthermore, in general formula (11), when at least one of R ^{21 to} R ³⁰ is a substituted or unsubstituted aryl group having 5 to 14 nuclear carbon atoms, R ²² and R ²⁷ are each independently 5 nuclear carbon atoms. The structure in which the substituted or unsubstituted aryl group of ˜14 is a substituent composed of a single or a plurality of combinations is preferable.

  In addition, other compounds represented by the general formulas (5) to (11) are shown below.

  Moreover, the compound represented by the following general formula (12) is mentioned as a specific example of a dopant.

In General Formula (12), Ar ^{1 to} Ar ⁴ each independently represents a substituted or unsubstituted aryl group having 6 to 14 nuclear carbon atoms. L ₁ represents substituted or unsubstituted benzene, naphthalene, fluorene, or phenanthrene. p is an integer of 1 to 6 independently. When p is 2 or more, L ₁ may be the same or different. When p is 2 or more, L ₁ may be the same or different in the substitution position. s is 0 or 1.

  Of the other compounds represented by the general formula (12), those having an affinity level of 2.4 eV are shown below.

  Among the other compounds represented by the general formula (12), those having an affinity level of 2.5 eV are shown below.

  In addition, as a dopant, you may use the compound represented by the following general formula (13) instead of the compound represented by the said general formula (12).

In the general formula (13), Ar ^{5 to} Ar ⁸ each independently represents a substituted or unsubstituted phenyl group, naphthyl group, or phenanthrylene group. L ₂ and L ₃ each independently represent substituted or unsubstituted benzene, naphthalene, or phenanthrene.

  Then, by configuring the light emitting layer to include a chrysene-containing host as described above and a benzidine or chrysene-containing dopant, the dopant energy gap is increased and the dopant affinity level is changed to the host affinity level. Lower than. Therefore, the blue light emission wavelength can be shortened and the life can be extended.

(Hole injection / transport layer (hole transport zone))
The hole injecting / transporting layer is a layer that assists hole injection into the light emitting layer and transports it to the light emitting region, and has a high hole mobility and a small ionization energy of usually 5.5 eV or less. As such a hole injecting / transporting layer, a material that transports holes to the light emitting layer with a lower electric field strength is preferable, and the mobility of holes is, for example, when an electric field of 10 ⁴ to 10 ⁶ V / cm is applied. , At least 10 ⁻⁴ cm ² / Vs is preferable.

Specific examples of the material for forming such a hole injection layer or a hole transport layer include, for example, triazole derivatives (see US Pat. No. 3,112,197, etc.), oxadiazole derivatives (US Pat. No. 3, 189,447, etc.), imidazole derivatives (see JP-B-37-16096, etc.), polyarylalkane derivatives (US Pat. Nos. 3,615,402, 3,820,989) No. 3,542,544, JP-B-45-555, JP-A-51-10983, JP-A-51-93224, JP-A-55-17105, JP-A-56-4148, No. 55-108667, No. 55-156953, No. 56-36656, etc.), pyrazoline derivatives and pyrazolone derivatives (US Pat. No. 3, 80,729, 4,278,746, JP-A-55-88064, 55-88065, 49-105537, 55-51086, 56 No.-80051, No. 56-88141, No. 57-45545, No. 54-112737, No. 55-74546, etc.), Phenylenediamine derivatives (US Pat. No. 3,615,404) , Japanese Patent Publication Nos. 51-10105, 46-3712, 47-25336, JP 54-53435, 54-110536, 54-1119925, etc.) Arylamine derivatives (US Pat. Nos. 3,567,450, 3,180,703, 3,240,597) 3,658,520, 4,232,103, 4,175,961, 4,012,376, JP-B-49-35702 No. 39-27577, JP-A-55-144250, JP-A-56-119132, JP-A-56-22437, West German Patent No. 1,110,518, etc.), amino-substituted chalcone Derivatives (see US Pat. No. 3,526,501, etc.), oxazole derivatives (disclosed in US Pat. No. 3,257,203, etc.), styryl anthracene derivatives (Japanese Patent Laid-Open No. 56-46234) ), Fluorenone derivatives (see Japanese Patent Laid-Open No. 54-110837), hydrazone derivatives (US Pat. No. 3,717,462, Japanese Patent Laid-Open No. 54-59143). No. 55-52063, No. 55-52064, No. 55-46760, No. 55-85495, No. 57-11350, No. 57-148799, JP-A-2-311591. Stilbene derivatives (Japanese Patent Laid-Open Nos. 61-210363, 61-228451, 61-14642, 61-72255, 62-47646, 62- 36674, 62-10652, 62-30255, 60-93455, 60-94462, 60-174749, 60-175052, etc.), silazane Derivatives (U.S. Pat. No. 4,950,950), polysilanes (JP-A-2-204996), aniline Copolymer (JP-A-2-282263), an electroconductive oligomer (particularly a thiophene oligomer) disclosed in JP-A-1-211399 and the like.
As the material for the hole injection layer or the hole transport layer, the above-mentioned materials can be used. Porphyrin compounds (disclosed in JP-A-63-295695 etc.), aromatic tertiary amine compounds And styrylamine compounds (US Pat. No. 4,127,412, JP-A-53-27033, 54-58445, 54-149634, 54-64299, 55- 79450 publication, 55-144250 publication, 56-119132 publication, 61-295558 publication, 61-98353 publication, 63-295695 publication etc.), aromatic tertiary amine compounds It can also be used. Further, for example, 4,4′-bis (N- (1-naphthyl) -N-phenylamino) biphenyl having two condensed aromatic rings described in US Pat. No. 5,061,569 in the molecule. 4,4 ′, 4 ″ -tris (N- (3-methylphenyl) -N-phenyl, in which three triphenylamine units described in JP-A-4-308688 are linked in a starburst type Amino) triphenylamine, etc. In addition, hexaazatriphenylene derivatives described in Patent Publication Nos. 3614405, 3571977 or U.S. Pat. No. 4,780,536 are also suitable as hole injecting materials. Further, in addition to the above-mentioned aromatic dimethylidin compounds shown as the material of the light emitting layer, inorganic compounds such as p-type Si and p-type SiC can be used. It can be used as a material for the hole injection layer or a hole transport layer.
This hole injection layer or hole transport layer may be composed of one or more layers made of the above-mentioned materials, or from a compound different from the hole injection layer or hole transport layer. It may be a laminate of a hole injection layer or a hole transport layer. Although the film thickness of a positive hole injection layer or a positive hole transport layer is not specifically limited, Preferably, it is 20-200 nm.

(Organic semiconductor layer)
The organic semiconductor layer is a layer that assists hole injection or electron injection into the light emitting layer, and preferably has a conductivity of 10 ⁻¹⁰ S / cm or more. As a material of such an organic semiconductor layer, a conductive oligomer such as a thiophene-containing oligomer or an arylamine oligomer described in JP-A-8-193191, a conductive dendrimer such as an arylamine dendrimer, or the like can be used. . Although the film thickness of an organic-semiconductor layer is not specifically limited, Preferably, it is 10-1,000 nm.

Electron injection / transport layer (electron transport zone)
An electron injection layer, an electron transport layer, or the like can be provided as the second organic layer between the cathode and the light emitting layer. The electron injection layer or the electron transport layer is a layer that assists the injection of electrons into the light emitting layer, and has a high electron mobility. The electron injection layer is provided to adjust the energy level, for example, to alleviate a sudden change in the energy level. As a material used for the electron injection layer or the electron transport layer, 8-hydroxyquinoline or a metal complex of a derivative thereof, an oxadiazole derivative, or a nitrogen-containing heterocyclic derivative is preferable. As a specific example of the metal complex of 8-hydroxyquinoline or a derivative thereof, a metal chelate oxinoid compound containing a chelate of oxine (generally 8-quinolinol or 8-hydroxyquinoline), for example, tris (8-quinolinol) aluminum is used. Can do. And as an oxadiazole derivative, the electron transfer compound represented by the following general formula is mentioned.

In the formula, Ar ¹⁷ , Ar ¹⁸ , Ar ¹⁹ , Ar ²¹ , Ar ²² and Ar ²⁵ each represent an aryl group with or without a substituent, and Ar ¹⁷ and Ar ¹⁸ , Ar ¹⁹ and Ar ²¹ , Ar ²² and Ar ²⁵ may be the same or different. Ar ²⁰ , Ar ²³ and Ar ²⁴ each represent an arylene group with or without a substituent, and Ar ²³ and Ar ²⁴ may be the same or different.

  Examples of the aryl group in the above formula include a phenyl group, a biphenyl group, an anthranyl group, a perylenyl group, and a pyrenyl group. Examples of the arylene group include a phenylene group, a naphthylene group, a biphenylene group, an anthranylene group, a peryleneylene group, and a pyrenylene group. And as a substituent to these, a C1-C10 alkyl group, a C1-C10 alkoxy group, a cyano group, etc. are mentioned. As this electron transfer compound, those having good thin film forming properties are preferably used. Specific examples of these electron transfer compounds include the following.

  Examples of the nitrogen-containing heterocyclic derivative include nitrogen-containing compounds that are not metal complexes composed of organic compounds having the following general formula.

In the formula, X represents a carbon atom or a nitrogen atom. Z ₁ and Z ₂ each independently represents an atomic group capable of forming a nitrogen-containing heterocycle.

  Preferably, the organic compound has a skeleton having a nitrogen-containing aromatic polycyclic group consisting of a 5-membered ring or a 6-membered ring, and in the case of a plurality of nitrogen atoms, having a bond position that is not adjacent. Further, in the case of such a nitrogen-containing aromatic polycyclic group having a plurality of nitrogen atoms, the nitrogen-containing aromatic polycyclic organic compound having a skeleton obtained by combining the above (101) and (102) or (101) and (103) .

  A nitrogen-containing heterocyclic derivative wherein a nitrogen-containing group (HAr) of the nitrogen-containing organic compound is selected from nitrogen-containing heterocyclic groups represented by the following general formula.

  In the formula, R is an aryl group having 6 to 40 carbon atoms, a heteroaryl group having 3 to 40 carbon atoms, an alkyl group having 1 to 20 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms, and n is 0 to 5 A plurality of R may be the same or different from each other when n is an integer of 2 or more.

  Furthermore, as a preferable specific compound, a nitrogen-containing heterocyclic derivative represented by the following general formula.

In the formula, HAr is a nitrogen-containing heterocycle having 3 to 40 carbon atoms which may have a substituent, and L is a single bond or an arylene group having 6 to 40 carbon atoms which may have a substituent. Or it is a C3-C40 heteroarylene group which may have a substituent, Ar < ¹ > is a C6-C40 bivalent aromatic hydrocarbon group which may have a substituent. , Ar ² is an aryl group having 6 to 40 carbon atoms which may have a substituent or a heteroaryl group having 3 to 40 carbon atoms which may have a substituent.

  A nitrogen-containing heterocyclic derivative wherein HAr is selected from the group consisting of:

  A nitrogen-containing heterocyclic derivative wherein L is selected from the group consisting of:

A nitrogen-containing heterocyclic derivative wherein Ar ² is selected from the group consisting of:

  A nitrogen-containing heterocyclic derivative in which Ar1 has an arylanthranyl group represented by the following.

  In the formula, each of R1 to R14 independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryloxy group having 6 to 40 carbon atoms, or a substituent. An aryl group having 6 to 40 carbon atoms or a heteroaryl group having 3 to 40 carbon atoms that may have, Ar3 may be an aryl group having 6 to 40 carbon atoms or a carbon number that may have a substituent. 3 to 40 heteroaryl groups.

  A nitrogen-containing heterocyclic derivative in which R 1 to R 8 are all hydrogen atoms in Ar 1.

  A nitrogen-containing heterocyclic derivative represented by the following formula is also suitable as an electron injecting (transporting) material.

In the formula, A1 to A3 are nitrogen atoms or carbon atoms, and R is an aryl group having 6 to 60 carbon atoms which may have a substituent, and 3 to 3 carbon atoms which may have a substituent. A heteroaryl group having 60 carbon atoms, an alkyl group having 1 to 20 carbon atoms, a haloalkyl group having 1 to 20 carbon atoms, and an alkoxy group having 1 to 20 carbon atoms, n is an integer of 0 to 5, and n is 2 or more. When it is an integer, several R may mutually be same or different.
Further, a plurality of adjacent R groups may be bonded to each other to form a substituted or unsubstituted carbocyclic aliphatic ring or a substituted or unsubstituted carbocyclic aromatic ring.
Ar1 is an optionally substituted aryl group having 6 to 60 carbon atoms and an optionally substituted heteroaryl group having 3 to 60 carbon atoms, and Ar2 is a hydrogen atom or carbon number. An alkyl group having 1 to 20 carbon atoms, a haloalkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryl group having 6 to 60 carbon atoms which may have a substituent, and a substituent; Or a heteroaryl group having 3 to 60 carbon atoms. However, either Ar1 or Ar2 is a C10-60 condensed ring group which may have a substituent, or a C3-60 heterocondensed ring group which may have a substituent. .
L1 and L2 each have a single bond, a condensed ring having 6 to 60 carbon atoms which may have a substituent, a hetero condensed ring having 3 to 60 carbon atoms which may have a substituent, or a substituent. It may be a fluorenylene group.

  In the formula, HAr is a nitrogen-containing heterocycle having 3 to 40 carbon atoms which may have a substituent, and L1 is a single bond or an arylene having 6 to 60 carbon atoms which may have a substituent. Group, a C3-C60 heteroarylene group which may have a substituent or a fluorenylene group which may have a substituent, and Ar1 may have a substituent. A divalent aromatic hydrocarbon group of ˜60, and Ar 2 is an aryl group having 6 to 60 carbon atoms which may have a substituent or an alkyl group having 3 to 60 carbon atoms which may have a substituent. A heteroaryl group;

  The following silacyclopentadiene derivatives are also suitable for the electron injection (transport) material.

In the formula, X and Y are each independently a saturated or unsaturated hydrocarbon group having 1 to 6 carbon atoms, alkoxy group, alkenyloxy group, alkynyloxy group, hydroxy group, substituted or unsubstituted aryl group, substituted Alternatively, it is an unsubstituted heterocyclic ring or a structure in which X and Y are bonded to form a saturated or unsaturated ring.
R1 to R4 are each independently hydrogen, halogen, substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, alkoxy group, aryloxy group, perfluoroalkyl group, perfluoroalkoxy group, amino group, alkylcarbonyl group. Arylcarbonyl group, alkoxycarbonyl group, aryloxycarbonyl group, azo group, alkylcarbonyloxy group, arylcarbonyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, sulfinyl group, sulfonyl group, sulfanyl group, silyl group, Carbamoyl group, aryl group, heterocyclic group, alkenyl group, alkynyl group, nitro group, formyl group, nitroso group, formyloxy group, isocyano group, cyanate group, isocyanate group, thiocyanate group, isothiocyanate When over preparative group or cyano group, or adjacent a structure substituted or the unsubstituted rings are fused.
However, when R1 and R4 are phenyl groups, X and Y are not alkyl groups and phenyl groups, but when R1 and R4 are thienyl groups, X and Y are monovalent hydrocarbon groups, R2 and R3 are An alkyl group, an aryl group, an alkenyl group or an aliphatic group in which R2 and R3 are combined to form a ring are not simultaneously filled, and when R1 and R4 are silyl groups, R2, R3, X and Y are Independently, in the case of a structure in which a benzene ring is condensed with R1 and R2 instead of a monovalent hydrocarbon group or hydrogen atom having 1 to 6 carbon atoms, X and Y are not an alkyl group or a phenyl group.

  A borane derivative represented by the following formula is also suitable as an electron injecting (transporting) material.

In the formula, R1 to R8 and Z2 each independently represent a hydrogen atom, a saturated or unsaturated hydrocarbon group, an aromatic group, a heterocyclic group, a substituted amino group, a substituted boryl group, an alkoxy group or an aryloxy group. , X, Y and Z1 each independently represents a saturated or unsaturated hydrocarbon group, aromatic group, heterocyclic group, substituted amino group, alkoxy group or aryloxy group, and the substituents of Z1 and Z2 are mutually May be bonded to each other to form a condensed ring, and n represents an integer of 1 to 3, and when n is 2 or more, Z1 may be different from Z2.
However, the case where n is 1, X, Y and R2 are methyl groups and R8 is a hydrogen atom or a substituted boryl group and the case where n is 3 and Z1 is a methyl group are not included.

  A gallium complex represented by the following formula is also suitable for the electron injection (transport) material.

  In the formula, Q1 and Q2 each independently represent a ligand represented by the following formula, and L represents a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted group Aryl group, substituted or unsubstituted heterocyclic group, -OR1 (R1 represents a hydrogen atom, substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted aryl group, substituted or unsubstituted A substituted heterocyclic group), or —O—Ga—Q3 (Q4) (Q3 and Q4 have the same meanings as Q1 and Q2).

  In the formula, Q1 to Q4 are residues represented by the following formula, and there are quinoline residues such as 8-hydroxyquinoline and 2-methyl-8-hydroxyquinoline, but not limited thereto.

  Rings A1 and A2 are substituted or unsubstituted aryl rings or heterocyclic structures bonded to each other.

  The metal complex has strong properties as an n-type semiconductor and has a high electron injection capability. Furthermore, since the generation energy at the time of complex formation is also low, the bond between the metal of the formed metal complex and the ligand is strengthened, and the fluorescence quantum efficiency as a light emitting material is also increased.

  Here, specific examples of the substituents of the rings A1 and A2 forming the ligand of the above formula include chlorine, bromine, iodine, fluorine halogen atom, methyl group, ethyl group, propyl group, butyl group. , Sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, stearyl group, trichloromethyl group and other substituted or unsubstituted alkyl groups, phenyl group, naphthyl group, 3-methylphenyl group 3-methoxyphenyl group, 3-fluorophenyl group, 3-trichloromethylphenyl group, 3-trifluoromethylphenyl group, 3-nitrophenyl group or other substituted or unsubstituted aryl group, methoxy group, n-butoxy group , Tert-butoxy group, trichloromethoxy group, trifluoroethoxy group, pentafluoropropoxy group, 2,2, , 3-tetrafluoropropoxy group, 1,1,1,3,3,3-hexafluoro-2-propoxy group, substituted or unsubstituted alkoxy group such as 6- (perfluoroethyl) hexyloxy group, phenoxy group P-nitrophenoxy group, p-tert-butylphenoxy group, 3-fluorophenoxy group, pentafluorophenyl group, 3-trifluoromethylphenoxy group and the like substituted or unsubstituted aryloxy group, methylthio group, ethylthio group, Substituted or unsubstituted alkylthio groups such as tert-butylthio group, hexylthio group, octylthio group, trifluoromethylthio group, phenylthio group, p-nitrophenylthio group, ptert-butylphenylthio group, 3-fluorophenylthio group, penta Fluorophenylthio group, 3-trif Substituted or unsubstituted arylthio groups such as olomethylphenylthio group, cyano group, nitro group, amino group, methylamino group, diethylamino group, ethylamino group, dimethylamino group, dipropylamino group, dibutylamino group, diphenylamino Mono- or di-substituted amino groups such as bis (acetoxymethyl) amino groups, bis (acetoxyethyl) amino groups, bisacetoxypropyl) amino groups, bis (acetoxybutyl) amino groups, etc., hydroxyl groups, siloxy groups, Carbamoyl groups such as acyl group, methylcarbamoyl group, dimethylcarbamoyl group, ethylcarbamoyl group, diethylcarbamoyl group, propylcarbamoyl group, butylcarbamoyl group, phenylcarbamoyl group, carboxylic acid group, sulfonic acid group, imide group, cyclopenta Cycloalkyl group such as phenyl group, cyclohexyl group, phenyl group, naphthyl group, biphenyl group, anthranyl group, aryl group such as phenanthryl group, fluorenyl group, pyrenyl group, pyridinyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, triazinyl group , Indolinyl group, quinolinyl group, acridinyl group, pyrrolidinyl group, dioxanyl group, piperidinyl group, morpholidinyl group, piperazinyl group, carbazolyl group, furanyl group, thiophenyl group, oxazolyl group, oxadiazolyl group, benzooxazolyl group, thiazolyl group , Heterocyclic groups such as thiadiazolyl group, benzothiazolyl group, triazolyl group, imidazolyl group, and benzoimidazolyl group. Moreover, the above substituents may combine to form a further 6-membered aryl ring or heterocyclic ring.

  In addition, the following compounds described in JP-A-9-3448 include organic compounds that satisfy the above-described element constituent conditions.

In the formula, each of R ^{1 to} R ⁴ independently represents a hydrogen atom, a substituted or unsubstituted aliphatic group, a substituted or unsubstituted aliphatic cyclic group, a substituted or unsubstituted carbocyclic aromatic ring group, A substituted or unsubstituted heterocyclic group is represented, and X ¹ and X ² each independently represents an oxygen atom, a sulfur atom or a dicyanomethylene group.

  The following compounds described in JP-A-2000-173774 include organic compounds that satisfy the above-described element constituent conditions.

However, in said general formula, R < ¹ >, R < ² >, R < ³ > and R < ⁴ > are mutually the same or different groups, Comprising: It is an aryl group represented by the following general formula.

However, in said general formula, R < ⁵ >, R < ⁶ >, R <^7> , R < ⁸ > and R < ⁹ > are mutually the same or different groups, Comprising: A hydrogen atom or those at least 1 is a saturated or unsaturated alkoxyl group, an alkyl group , An amino group or an alkylamino group.

  Further, it may be a polymer compound containing the nitrogen-containing heterocyclic group or nitrogen-containing heterocyclic derivative.

  Although the film thickness of an electron injection layer or an electron carrying layer is not specifically limited, Preferably, it is 1-100 nm.

It is preferable that the 1st light emitting layer or 1st organic layer which is an organic layer nearest to an anode contains the oxidizing agent. A preferred oxidizing agent contained in the first light emitting layer or the first organic layer is an electron withdrawing or electron acceptor. Preferred are Lewis acids, various quinone derivatives, dicyanoquinodimethane derivatives, and salts formed with aromatic amines and Lewis acids. Particularly preferred Lewis acids are iron chloride, antimony chloride, aluminum chloride and the like.
It is preferable that the light emitting layer or the second organic layer which is the organic layer closest to the cathode contains a reducing agent. Preferred reducing agents are alkali metals, alkaline earth metals, alkali metal oxides, alkaline earth oxides, rare earth oxides, alkali metal halides, alkaline earth halides, rare earth halides, alkali metals and aromatic compounds. It is a complex formed. Particularly preferred alkali metals are Cs, Li, Na and K.

  A preferred form of the organic EL element is an element containing a reducing dopant in an electron transporting region or an interface region between a cathode and an organic layer. Here, the reducing dopant is defined as a substance capable of reducing the electron transporting compound. Accordingly, various materials can be used as long as they have a certain reducibility, such as alkali metals, alkaline earth metals, rare earth metals, alkali metal oxides, alkali metal halides, alkaline earth metals. At least selected from the group consisting of oxides, alkaline earth metal halides, rare earth metal oxides or rare earth metal halides, alkali metal organic complexes, alkaline earth metal organic complexes, rare earth metal organic complexes One substance can be preferably used.

  More specifically, preferable reducing dopants include Li (work function: 2.9 eV), Na (work function: 2.36 eV), K (work function: 2.28 eV), Rb (work function: 2). .16 eV) and Cs (work function: 1.95 eV), at least one alkali metal selected from the group consisting of Ca (work function: 2.9 eV), Sr (work function: 2.0 to 2.5 eV) And at least one alkaline earth metal selected from the group consisting of Ba (work function: 2.52 eV), and those having a work function of 2.9 eV or less are particularly preferred. Among these, a more preferable reducing dopant is at least one alkali metal selected from the group consisting of K, Rb and Cs, more preferably Rb or Cs, and most preferably Cs. These alkali metals have particularly high reducing ability, and the addition of a relatively small amount to the electron injection region can improve the light emission luminance and extend the life of the organic EL element. Further, as a reducing dopant having a work function of 2.9 eV or less, a combination of two or more alkali metals is also preferable. Particularly, a combination containing Cs, such as Cs and Na, Cs and K, Cs and Rb, or Cs. And a combination of Na and K. By including Cs in combination, the reducing ability can be efficiently exhibited, and by adding to the electron injection region, the emission luminance and the life of the organic EL element can be improved.

An electron injection layer made of an insulator or a semiconductor may be further provided between the cathode and the organic layer. At this time, current leakage can be effectively prevented and the electron injection property can be improved. As such an insulator, it is preferable to use at least one metal compound selected from the group consisting of alkali metal chalcogenides, alkaline earth metal chalcogenides, alkali metal halides and alkaline earth metal halides. If the electron injection layer is composed of these alkali metal chalcogenides or the like, it is preferable in that the electron injection property can be further improved. Specifically, preferred alkali metal chalcogenides include, for example, Li2O, K2O, Na2S, Na2Se and Na2O, and preferred alkaline earth metal chalcogenides include, for example, CaO, BaO, SrO, BeO, BaS, and CaSe. Can be mentioned. Further, preferable alkali metal halides include, for example, LiF, NaF, KF, LiCl, KCl, and NaCl. Examples of preferable alkaline earth metal halides include fluorides such as CaF2, BaF2, SrF2, MgF2 and BeF2, and halides other than fluorides.
Further, as a semiconductor constituting the electron transport layer, an oxide containing at least one element of Ba, Ca, Sr, Yb, Al, Ga, In, Li, Na, Cd, Mg, Si, Ta, Sb, and Zn. , Nitrides or oxynitrides, or a combination of two or more. Moreover, it is preferable that the inorganic compound which comprises an electron carrying layer is a microcrystal or an amorphous insulating thin film. If the electron transport layer is composed of these insulating thin films, a more uniform thin film is formed, and pixel defects such as dark spots can be reduced. Examples of such inorganic compounds include the alkali metal chalcogenides, alkaline earth metal chalcogenides, alkali metal halides, and alkaline earth metal halides described above.

(cathode)
As the cathode, in order to inject electrons into the electron injecting / transporting layer or the light emitting layer, a material having a small work function (4 eV or less) metal, an alloy, an electrically conductive compound and a mixture thereof are used. Specific examples of such electrode materials include sodium, sodium / potassium alloy, magnesium, lithium, magnesium / silver alloy, aluminum / aluminum oxide, aluminum / lithium alloy, indium, and rare earth metals.
The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering.
Here, when light emitted from the light emitting layer is taken out from the cathode, it is preferable that the transmittance with respect to the light emitted from the cathode is larger than 10%.
The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually 10 nm to 1 μm, preferably 50 to 200 nm.

(Insulating layer)
Since an organic EL element applies an electric field to an ultrathin film, pixel defects are likely to occur due to leakage or short circuit. In order to prevent this, it is preferable to insert an insulating thin film layer between the pair of electrodes.
Examples of materials used for the insulating layer include aluminum oxide, lithium fluoride, lithium oxide, cesium fluoride, cesium oxide, magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride, aluminum nitride, titanium oxide, silicon oxide, and oxide. Examples include germanium, silicon nitride, boron nitride, molybdenum oxide, ruthenium oxide, and vanadium oxide.
A mixture or laminate of these may be used.

[Method for producing organic EL element]
Next, the manufacturing method of an organic EL element is demonstrated.

  An organic EL device can be produced by forming an anode, a light emitting layer, a hole injection layer as needed, and an electron injection layer as needed, and further forming a cathode by the materials and formation methods exemplified above. . Moreover, an organic EL element can also be produced from the cathode to the anode in the reverse order.

  Hereinafter, an example of manufacturing an organic EL element having a structure in which an anode / a hole injection layer / a light emitting layer / an electron injection layer / a cathode are sequentially provided on a translucent substrate will be described.

First, a thin film made of an anode material is formed on a suitable light-transmitting substrate by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably 10 to 200 nm.
Next, a hole injection layer is provided on the anode.
Formation of a positive hole injection layer can be performed by methods, such as a vacuum evaporation method, a spin coat method, a casting method, LB method. It is preferable to select appropriately in the thickness range of 5 nm to 5 μm.

  Next, the formation of the light emitting layer provided on the hole injection layer is performed by using a desired organic light emitting material to dry the organic light emitting material by a dry process typified by a vacuum deposition method, or a wet process such as a spin coating method or a cast method. It can be formed by thinning.

Next, an electron injection layer is provided on the light emitting layer.
An example is formation by a vacuum deposition method.

Finally, an organic EL element can be obtained by laminating a cathode.
The cathode is made of metal, and vapor deposition or sputtering can be used.
However, vacuum deposition is preferred to protect the underlying organic layer from damage during film formation.

The method for forming each layer of the organic EL element is not particularly limited.
Conventionally known methods such as vacuum deposition and spin coating can be used. That is, the organic thin film layer can be formed by vacuum deposition, molecular beam deposition (MBE), solution dipping in a solvent, spin It can be formed by a known method such as a coating method, a casting method, a bar coating method, a roll coating method, or an ink jet method.
The film thickness of each organic layer of the organic EL element is not particularly limited. Generally, if the film thickness is too thin, defects such as pinholes are likely to occur. Is preferably in the range of several nm to 1 μm.
When a direct current voltage is applied to the organic EL element, light emission can be observed by applying a voltage of 5 to 40 V with a positive polarity of the anode and a negative polarity of the cathode. Further, even when a voltage is applied with the opposite polarity, no current flows and no light emission occurs. Further, when alternating voltage is applied, uniform light emission is observed only when the anode has a positive polarity and the cathode has a negative polarity. The waveform of the alternating current to be applied may be arbitrary.

  Next, examples of the present invention will be described.

[Sample structure]
First, the configuration of the sample will be described.

Example 1
A 25 mm × 75 mm × 1.1 mm thick glass substrate with ITO transparent electrode (anode) (manufactured by Geomatic) was ultrasonically cleaned in isopropyl alcohol for 5 minutes, and then UV ozone cleaning was performed for 30 minutes. The glass substrate with a transparent electrode line after washing is mounted on a substrate holder of a vacuum deposition apparatus, and the following compound A- having a film thickness of 75 nm is firstly covered so as to cover the transparent electrode on the surface where the transparent electrode line is formed. 1 was deposited.
Furthermore, the following compound H-1 and the following compound D-1 were formed into a film thickness ratio of 40: 2 on this A-1 film | membrane with a film thickness of 40 nm, and it was set as the blue type light emitting layer. Compound H-1 functions as a host and D-1 functions as a dopant.
On this film, Alq having a thickness of 20 nm was deposited as an electron transport layer by vapor deposition. Thereafter, LiF was formed to a thickness of 1 nm. On the LiF film, metal Al was deposited to a thickness of 150 nm to form a metal cathode, thereby forming an organic EL device.

(Example 2)
In Example 1, an organic EL device was produced in the same manner using D-2 having the following structure instead of D-1.

Example 3
In Example 1, an organic EL device was prepared in the same manner using D-3 having the following structure instead of D-1.

Example 4
In Example 1, an organic EL device was prepared in the same manner using D-4 having the following structure instead of D-1.

(Example 5)
In Example 1, an organic EL device was produced in the same manner using D-5 having the following structure instead of D-1.

(Example 6)
In Example 1, an organic EL device was produced in the same manner using D-6 having the following structure instead of D-1.

(Example 7)
In Example 1, an organic EL device was produced in the same manner using D-7 having the following structure instead of D-1.

(Example 8)
In Example 1, an organic EL device was produced in the same manner using D-8 having the following structure instead of D-1.

Example 9
In Example 1, an organic EL device was produced in the same manner using D-9 having the following structure instead of D-1.

(Example 10)
In Example 1, an organic EL device was prepared in the same manner using H-2 having the following structure instead of H-1.

(Example 11)
In Example 1, an organic EL device was prepared in the same manner using H-3 having the following structure instead of H-1.

(Example 12)
In Example 1, an organic EL device was produced in the same manner using H-4 having the following structure instead of H-1.

(Example 13)
In Example 1, an organic EL device was produced in the same manner using H-5 having the following structure instead of H-1.

(Example 14)
In Example 1, an organic EL device was prepared in the same manner using H-6 having the following structure instead of H-1.

(Comparative Example 1)
In Example 1, an organic EL device was produced in the same manner using the compound (A) having the following structure instead of D-1.

(Comparative Example 2)
In Example 1, an organic EL device was produced in the same manner using the compound (B) having the following structure instead of D-1.

(Comparative Example 3)
In Example 1, an organic EL device was produced in the same manner using the compound (C) having the following structure instead of H-1.

〔Evaluation methods〕
Next, the evaluation method will be described.

About the organic EL element of Examples 1-14 mentioned above and Comparative Examples 1-3, the external quantum yield which is element performance at the time of a 10 mA / cm < ² > current density drive, emission wavelength, and half in initial luminance of 300 cd / m < ² >. Lifespan was measured. These results are shown in Table 1. Table 2 shows physical property values of the host material and the dopant material used in the examples.

〔Evaluation results〕
As shown in Table 1, it was confirmed that the external quantum yields were not significantly different between Examples 1-14 and Comparative Examples 1-2.
Moreover, about the light emission wavelength, it has confirmed that Examples 1-14 became a wavelength shorter than Comparative Examples 1-2.
Furthermore, about the lifetime, it has confirmed that Examples 1-14 became 2 times or more longer than Comparative Examples 1-2.
In Comparative Example 3, light emission from the dopant was not obtained because the energy gap of the host was smaller than the energy gap of the dopant.
That is, it has been confirmed that by using the light emitting layer having the configuration of the present invention, an organic EL element capable of shortening the blue light emission wavelength and extending the life can be obtained.

Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-75567) describes an organic EL element including a light-emitting layer using an oligoarylene derivative as a host and a material and an arylamine compound or a styrylamine compound as a dopant.
As oligoarylene derivatives, those having chrysene as a central skeleton are disclosed.
However, the dopant D1 (styrylamine compound) used in Examples 9 and 11 shown in this document is different from the dopant D1 (styrylamine compound) in which the central skeleton is composed of aryl linkages as in the present invention, and the emission wavelength of the dopant is sufficient. However, it cannot be said to have a short wavelength, and the lifetime cannot be sufficiently maintained.
Moreover, since the central skeleton is pyrene in the dopant D2 (arylamine compound) used in Example 10 and Example 12 of this document, the central skeleton is substituted or unsubstituted benzene, naphthalene, The emission wavelength is longer than that selected from fluorene and phenanthrene, and the object of the present invention is not achieved.
Therefore, as in the combination of the host and the dopant according to the present invention, the effect of a long life cannot be obtained while the light is emitted at a short wavelength.

  The present invention can be used for organic EL elements used in display devices and the like.

Claims (3)

An organic EL element in which an organic thin film layer composed of one or more layers including at least a light emitting layer is sandwiched between a cathode and an anode,
The said light emitting layer consists of the host represented by the following general formula (1), and the dopant represented by the following general formula (2). The organic EL element characterized by the above-mentioned.

In General formula (1), R < ¹ > -R < ¹² > represents a hydrogen atom or a substituent.
However, at least one of R ^{1 to} R ¹² independently represents a substituted or unsubstituted aryl group having 6 to 60 nuclear carbon atoms.

In the general formula (2), Ar ^{1 to} Ar ⁴ each independently represents a substituted or unsubstituted aryl group having 6 to 14 nuclear carbon atoms.
L ₁ represents substituted or unsubstituted benzene, naphthalene, fluorene, or phenanthrene.
p is an integer of 1 to 6 independently. When p is 2 or more, L ₁ may be the same or different.
When p is 2 or more, L ₁ may be the same or different in the substitution position.
s is 0 or 1. The organic EL device according to claim 1,
The said dopant is replaced with the said General formula (2), and is represented by the following general formula (3). The organic EL element characterized by the above-mentioned.

In the general formula (3), Ar ^{5 to} Ar ⁸ each independently represents a substituted or unsubstituted phenyl group, naphthyl group, or phenanthrylene group.
L ₂ and L ₃ each independently represent substituted or unsubstituted benzene, naphthalene, or phenanthrene. The organic EL device according to claim 1 or 2, wherein
The said host is represented by the following general formula (4). The organic EL element characterized by the above-mentioned.

In General formula (4), Ar < ⁹ >, Ar < ¹⁰ > represents the substituent in which a C5-C14 substituted or unsubstituted aryl group is comprised individually or in multiple combinations, respectively.