JP4959923B2 - Organic electroluminescence element, lighting device, display device - Google Patents

Description

  The present invention relates to an organic electroluminescence element and a compound that is a material of an illumination device, a display device, and an organic electroluminescence element using the same.

  Conventionally, there is an electroluminescence display (ELD) as a light-emitting electronic display device. Examples of the constituent elements of ELD include inorganic electroluminescent elements and organic electroluminescent elements (hereinafter also abbreviated as organic EL elements). Inorganic electroluminescent elements have been used as planar light sources, but an alternating high voltage is required to drive the light emitting elements.

  On the other hand, an organic electroluminescence device has a structure in which a light emitting layer containing a light emitting compound is sandwiched between a cathode and an anode, and excitons (exciton) are injected by injecting electrons and holes into the light emitting layer and recombining them. ), Which emits light by utilizing the emission of light (fluorescence / phosphorescence) when the exciton is deactivated, and can emit light at a voltage of several volts to several tens of volts. Since it is a type, it has a wide viewing angle, high visibility, and since it is a thin-film type completely solid element, it has attracted attention from the viewpoints of space saving, portability, and the like.

  For the development of organic EL elements for practical application in the future, organic EL elements that emit light with high power and efficiency with low power consumption are desired, such as stilbene derivatives, distyrylarylene derivatives, or tristyryl. A technique for doping an arylene derivative with a small amount of a phosphor to improve emission luminance and extend the lifetime of the device (see, for example, Patent Document 1), and 8-hydroxyquinoline aluminum complex as a host compound. A device having an organic light-emitting layer doped with a phosphor (for example, see Patent Document 2), a device having an organic light-emitting layer doped with a quinacridone-based dye as an 8-hydroxyquinoline aluminum complex as a host compound (for example, Patent Document 3) is known.

In the technique disclosed in the above document, when light emission from an excited singlet is used, the generation ratio of singlet excitons and triplet excitons is 1: 3. Since the light extraction efficiency is about 20%, the limit of the external extraction quantum efficiency (η _ext ) is set to 5%.

  On the other hand, since the University of Princeton has reported on organic EL devices that use phosphorescence from excited triplets (see, for example, Non-Patent Document 1), research on materials that exhibit phosphorescence at room temperature has become active. (For example, refer nonpatent literature 2 and patent literature 4.).

  When excited triplets are used, the upper limit of internal quantum efficiency is 100%, so in principle the luminous efficiency is four times that of excited singlets, and the performance is almost the same as that of cold cathode tubes. It can be applied to and attracts attention.

  On the other hand, it has been proposed to provide a hole blocking layer that restricts the movement of holes from the light emitting layer between the light emitting layer and the cathode in order to improve the light emission luminance and the light emission lifetime of the organic EL element. By efficiently accumulating holes in the light emitting layer by this hole blocking layer, it is possible to improve the recombination probability with electrons and achieve high efficiency of light emission. It has been reported that the use of a phenanthroline derivative or a triazole derivative alone as a hole blocking material is effective (see Patent Documents 5 and 6). In addition, a long-life organic EL element is realized by using a specific aluminum complex for the hole blocking layer (see Patent Document 7).

  As described above, with the introduction of the hole blocking layer, in the organic EL element using the phosphorescent compound, the internal quantum efficiency in green is almost 100% and the lifetime is 20,000 hours (see Non-Patent Document 3). There is still room for improvement in terms of luminance.

  In addition, when a blue to blue-green phosphorescent compound is used as a dopant, there is an example in which a carbazole derivative such as CBP is used as a host compound, but the external extraction quantum efficiency is 6%, which is an insufficient result. Yes (see Non-Patent Document 4), there remains room for improvement. For blue, light emission from fluorescent compounds is used, but a linking group is introduced into the biaryl moiety in the middle of the carbazole derivative molecule to produce an organic EL device with excellent blue color purity and long life. (For example, see Patent Document 8). Further, in addition to the above compound, when a specific pentacoordinate metal complex is used for the hole blocking layer and a phosphorescent compound is used as a dopant, a longer lifetime is achieved (for example, patents). Reference 9).

Furthermore, other organic EL elements using carbazole derivatives have been produced (for example, Patent Documents 10 to 21). However, the carbazole derivatives described in the above patents have not yet reached luminous efficiency and heat resistance that can withstand practical use. In the organic EL element for practical use in the future, it is desired to develop an organic EL element that emits light efficiently and with high luminance with low power consumption and has a longer lifetime.
Japanese Patent No. 3093796 Japanese Unexamined Patent Publication No. 63-264692 JP-A-3-255190 US Pat. No. 6,097,147 JP-A-8-109373 JP-A-10-233284 JP 2001-284056 A JP 2000-21572 A Japanese Patent Laid-Open No. 2002-8860 JP 2002-203663 A JP-A-8-3547 Japanese Patent Laid-Open No. 8-143861 JP-A-8-143862 Japanese Patent Laid-Open No. 9-249876 Japanese Patent Laid-Open No. 11-144866 JP-A-11-144867 JP-A-8-60144 Japanese Patent Laid-Open No. 2002-8860 Japanese Patent Laid-Open No. 2003-77664 International Publication No. 03/50201 Pamphlet JP 2003-231692 A M.M. A. Baldo et al. , Nature, 395, 151-154 (1998) M.M. A. Baldo et al. , Nature, 403, 17, 750-753 (2000) 62nd Japan Society of Applied Physics Academic Lecture Proceedings 12-a-M7, Pioneer Technical Information Magazine, Vol. 11, No. 1 62nd Japan Society of Applied Physics Academic Lecture Proceedings 12-a-M8

  The present invention provides an organic electroluminescence element that exhibits high luminance and luminous efficiency, has a long lifetime, and is excellent in heat resistance under high temperature storage conditions, and an illumination device and a display device using the same. It is.

The above object of the present invention is achieved by the following configurations 1 to 10 .

1. In an organic electroluminescence device having at least a light emitting layer and a hole blocking layer adjacent to the light emitting layer,
The light-emitting layer, molecular weight is not more than 500 1700 or less and at least one contains a compound represented by the following general formula (11), and, the hole blocking layer, a carboline skeleton mosquito Ruborin derivatives An organic electroluminescence device comprising at least one derivative selected from the group consisting of derivatives in which at least one carbon atom to be formed is substituted with a nitrogen atom.

[Wherein, J represents a methyl group which may have a substituent, an ethyl group which may have a substituent, or an aryl group which may have a substituent, and R ₁ represents hydrogen. Represents an atom, a methyl group, an ethyl group, an isopropyl group, a cyclohexyl group or a benzyl group, Ar represents a phenylene group which may have a substituent or a biphenyldiyl group which may have a substituent, and R ₄ and R ₇ each represents a hydrogen atom, a methyl group, a methoxy group, or a phenyl group that may substitute a methyl group, and R ₂ , R ₃ , R ₅ , R ₆ , R ₈ , R ₉ are each Represents a hydrogen atom, and n represents an integer of 1 to 6. ]
2. 2. The organic electroluminescent device according to 1 above, wherein Ar in the general formula (11) is a phenylene group which may have a substituent.

3. 3. The organic electroluminescence device as described in 1 or 2 above, wherein R ₁ in the general formula (11) is a hydrogen atom.
4). At least one at least one carbon atom of at least one derivative selected from the derivatives substituted at the nitrogen atom, selected from B-14 and B-29 below to form a carboline skeleton before asked Ruborin derivatives the organic electroluminescent device according to any one of claims 1 to 3, characterized in that.

5. 5. The organic electroluminescence device according to any one of 1 to 4 , wherein the light emitting layer contains a phosphorescent compound.

6). 6. The organic electroluminescence device as described in 5 above, wherein the phosphorescent compound is osmium, iridium, rhodium or a platinum complex compound.

7). 7. The organic electroluminescence device according to any one of 1 to 6 , which emits white light.

8). A display device comprising the organic electroluminescence element according to any one of 1 to 7 above.

9. 8. An illuminating device comprising the organic electroluminescent element according to any one of 1 to 7 above.

10. 10. A display device comprising the illumination device according to 9 and a liquid crystal element as display means.

  INDUSTRIAL APPLICABILITY According to the present invention, an organic electroluminescence element exhibiting high light emission luminance and light emission efficiency and having a long lifetime, a display device using the same, a lighting device, and an organic electroluminescence device in which deterioration of luminance characteristics under high temperature storage is suppressed. A luminescence element, a display device using the element, and a lighting device can be provided.

  Hereinafter, the present invention will be described in detail.

  As a result of intensive studies, the present inventors have included in the light emitting layer a compound having a partial structure represented by the general formula (1) or the general formula (1a) and having a molecular weight of 1700 or less, and Selected from the group consisting of styryl derivatives, boron derivatives, carboline derivatives, and derivatives in which at least one carbon atom forming the carboline skeleton of the carboline derivative is substituted with a nitrogen atom in the hole blocking layer adjacent to the light emitting layer. It has been found that an organic electroluminescence device containing at least one kind of derivative exhibits high light emission luminance and high light emission efficiency and can have a long lifetime.

  Furthermore, an organic electroluminescence device containing a compound having a partial structure represented by the general formula (1) or the general formula (1a) and having a molecular weight of 500 or more and 1700 or less in a light emitting layer is It has been found that the degradation of the luminance characteristics of the image is significantly improved.

<< Compound having a partial structure represented by the general formula (1) >>
In the general formula (1), R ₁ represents a hydrogen atom, an alkyl group, or a cycloalkyl group. From the viewpoint of improving the light emission luminance and high light emission efficiency of the organic electroluminescent device (hereinafter referred to as organic EL device) of the present invention, a hydrogen atom is most preferable.

In the general formula (1), examples of the alkyl group represented by R ₁ include methyl, ethyl, propyl, isopropyl, tert-butyl, pentyl, hexyl, octyl, dodecyl, and tridecyl. Group, tetradecyl group, pentadecyl group, trifluoromethyl group, pentafluoromethyl group, trifluoromethylmethyl group and the like. The alkyl group may be substituted with an aryl group (for example, a phenyl group, a tolyl group, a xylyl group, a biphenyl group, a naphthyl group, an anthryl group, a phenanthryl group, etc.), and is bonded to an adjacent carbon atom. You may form a ring with group.

In the general formula (1), examples of the cycloalkyl group represented by R ₁ include a cyclopentyl group and a cyclohexyl group. The cycloalkyl group may be substituted with an aryl group in the same manner as the alkyl group described above, and may form a ring with a group bonded to an adjacent carbon atom.

In the general formula (1), examples of the arylene group represented by Ar include a phenylene group (eg, o-phenylene group, m-phenylene group, p-phenylene group), naphthalenediyl group, anthracenediyl group, and naphthacenediyl. Group, pyrenediyl group, anthracenediyl group, phenanthrene diyl group, naphthylnaphthalenediyl group, biphenyldiyl group (for example, [1,1′-biphenyl] -4,4′-diyl group, 3,3′-biphenyldiyl group, 3,6-biphenyldiyl group, etc.), terphenyldiyl group, quaterphenyldiyl group, kinkphenyldiyl group, sexiphenyldiyl group, septiphenyldiyl group, octiphenyldiyl group, nobiphenyldiyl group, deciphenyl A diyl group etc. are mentioned. The arylene group may further have a substituent represented by R _{2 to} R ₉ described later.

In the general formula (1), examples of the heteroarylene group represented by Ar include carbazole ring, triazole ring, pyrrole ring, pyridine ring, pyrazine ring, quinoxaline ring, thiophene ring, oxadiazole ring, dibenzofuran ring, dibenzo Examples include a divalent group derived from a group consisting of a thiophene ring and an indole ring, and the heteroarylene group may have a substituent represented by R _{2 to} R ₉ , which will be described later. Good.

  Among these, the most preferable group represented by Ar is a phenylene group.

In the general formula (1), R _{2 to} R ₉ each independently represent a hydrogen atom or a substituent, and may be the same or different. R ₂ and R ₃ , R ₃ and R ₄ , R ₄ and R ₅ , R ₆ and R ₇ , R ₇ and R ₈ , R ₈ and R ₉ are bonded to each other to form an aromatic ring. Also good.

In the general formula (1), examples of the substituent represented by R _{2 to} R ₉ include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, octyl group). Group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (eg, vinyl group, allyl group, etc.), alkynyl group (eg, ethynyl group) , Propargyl group, etc.), aryl group (for example, phenyl group, naphthyl group, etc.), aromatic heterocyclic group (for example, furyl group, thienyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group, imidazolyl group) , Pyrazolyl group, thiazolyl group, quinazolinyl group, phthalazinyl group, etc.), heterocyclic group For example, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxyl group (eg, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cyclo An alkoxyl group (eg, cyclopentyloxy group, cyclohexyloxy group, etc.), an aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), an alkylthio group (eg, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, Octylthio group, dodecylthio group, etc.), cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.), arylthio group (eg, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (eg, , Methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group ( For example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group , 2-pyridylaminosulfonyl group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, Chlohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy) Group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexyl group) Carbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, Phthalylcarbonylamino group, etc.), carbamoyl groups (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexyl) Aminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido) Group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ester Tylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group) Group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group (phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group etc.), amino group (for example, amino group, Ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pi Zircino group, etc.), halogen atoms (eg fluorine atom, chlorine atom, bromine atom etc.), fluorinated hydrocarbon groups (eg fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group etc.), And cyano group, nitro group, hydroxy group, mercapto group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, etc.).

  These substituents may be further substituted with the above substituents. In addition, a plurality of these substituents may be bonded to each other to form a ring.

<< Compound having a partial structure represented by the general formula (1a) >>
In the general formula (1a), the arylene group or heteroarylene group defined by Ar has the same meaning as the arylene group or heteroarylene group defined by Ar in the general formula (1).

In formula (1a), each substituent represented by R ₂ to R ₉ have the same meanings as R ₂ to R ₉ in the general formula (1).

In the general formula (1a), examples of the 3- to 8-membered saturated hydrocarbon ring formed by Z include a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, and a cyclooctane ring. Can be mentioned. The saturated hydrocarbon ring may be unsubstituted or may further have a substituent. Further, examples of the substituent group, such as substituents represented by R ₂ to R ₉ in the general formula (1).

<< Compound Represented by Formula (6) >>
In the present invention, among the compounds having a partial structure represented by the general formula (1), a compound represented by the following general formula (6) is preferable.

In the general formula (6), R ₁ to R ₉ have the same meanings as the R ₁ to R ₉ in the general formula (1). n represents an integer of 1 to 6. When n = 1, J represents an aryl group (for example, a phenyl group, a tolyl group, a xylyl group, a biphenyl group, a naphthyl group, an anthryl group, a phenanthryl group, etc.), preferably a substituted or unsubstituted 4- (N— Represents a carbazolyl) phenyl group.

  When n = 2 to 6, J represents an n-valent linking group, and has a direct bond, an oxygen atom, a sulfur atom, an aliphatic hydrocarbon group which may have a substituent, or a substituent. It is selected from an aliphatic heterocyclic group that may be substituted, an aromatic hydrocarbon group that may have a substituent, and an aromatic heterocyclic ring that may have a substituent.

  The partial structures represented by the general formula (1) included in the general formula (6) may be different from each other or the same.

  Specific examples of the compound according to the present invention are shown below, but are not limited thereto.

  A synthesis method of H-1 will be described as an example of the synthesis of the above compound.

  << Synthesis of H-1 >>

4.0 g of 4,4′-diaminodiphenylmethane, 13.0 g of 2,2′-dibromobiphenyl, 0.7 g of bis (dibenzylideneacetone) palladium, 1.2 ml of tri-tert-butylphosphine, sodium-tert-butoxide 7 g was dispersed in 70 ml of anhydrous toluene and stirred at reflux temperature for 4 hours under a nitrogen atmosphere. The resulting reaction mixture is allowed to cool and then toluene and water are added to separate the organic layer. The organic layer is washed with dilute hydrochloric acid, water and saturated brine, concentrated, purified by silica gel column chromatography, and compound 1 1.7 g of colorless needle crystals of was obtained. The structure was confirmed by ¹ H-NMR spectrum and mass spectrometry spectrum.

Data for Compound H-1:
Shape: colorless crystals Melting point: 200 ° C
Mass spectrum: MS (FAB) m / z 498 (M ⁺ )
¹ H-NMR (400 MHz, CDCl ₃ ):
δ / ppm: 4.24 (s, 2H), 7.29 (td, J = 6.5, 1.2 Hz, 4H), 7.41 (td, J = 7.8, 1.2 Hz, 4H) 7.45 (d, J = 6.5 Hz, 4H), 7.51 (d, J = 8.3 Hz, 4H), 7.56 (d, J = 8.3 Hz, 4H), 8.15 ( d, J = 7.8 Hz, 4H)
Further, FIG. 8 shows a chart of absorption, fluorescence and excitation spectrum of Compound H-1 measured in tetrahydrofuran.

  The molecular weight of the compound according to the present invention is 1700 or less, preferably 500 to 1700. Thereby, it is long-lived, shows high light emission luminance and high light emission efficiency, and can suppress deterioration of luminance characteristics during storage at high temperatures.

  Next, although the preferable specific example of the layer structure of the organic EL element of this invention is shown below, this invention is not limited to these.

I: Anode / light emitting layer / cathode
II: Anode / light-emitting layer / electron transport layer / cathode
III: Anode / anode buffer layer / light emitting layer / cathode
IV: anode / anode buffer layer / light emitting layer / hole blocking layer / electron transport layer / cathode V: anode / hole transport layer / light emitting layer / electron transport layer / cathode
VI: Anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode
VII: Anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode
VIII: Anode / anode buffer layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode << Anode >>
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such electrode materials include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ and ZnO. Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming a transparent conductive film may be used. For the anode, a thin film may be formed by depositing these electrode materials by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when the pattern accuracy is not required (100 μm or more) Degree), a pattern may be formed through a mask having a desired shape when the electrode material is deposited or sputtered. When light emission is extracted from the anode, it is desirable that the transmittance is greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 nm to 1000 nm, preferably 10 nm to 200 nm.

"cathode"
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Suitable are a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, a lithium / aluminum mixture, aluminum and the like. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 1000 nm, preferably 50 nm to 200 nm. In order to transmit light, if either the anode or the cathode of the organic EL element is transparent or translucent, the light emission luminance is improved, which is convenient.

  Next, an injection layer, a hole transport layer, an electron transport layer, etc. used as a constituent layer of the organic EL element of the present invention will be described.

<< Injection layer: electron injection layer, hole injection layer >>
The injection layer is provided as necessary, and there are an electron injection layer and a hole injection layer, and as described above, exists between the anode and the light emitting layer or the hole transport layer, and between the cathode and the light emitting layer or the electron transport layer. You may let them.

  An injection layer is a layer provided between an electrode and an organic layer in order to lower drive voltage or improve light emission luminance. “Organic EL element and its forefront of industrialization (issued on November 30, 1998 by NTS Corporation) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).

  The details of the anode buffer layer (hole injection layer) are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069 and the like. As a specific example, copper phthalocyanine is used. Examples thereof include a phthalocyanine buffer layer represented by an oxide, an oxide buffer layer represented by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene. Among these, those using polydioxythiophenes are preferable, and thereby, an organic EL device that exhibits higher light emission luminance and light emission efficiency and has a longer lifetime can be obtained. The anode buffer layer is preferably provided between the anode and the light emitting layer and adjacent to the cathode and the light emitting layer. Thereby, it can be set as the organic EL element which shows much higher light-emitting luminance and luminous efficiency, and is further long-life.

  The details of the cathode buffer layer (electron injection layer) are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specific examples thereof include strontium and aluminum. A metal buffer layer, an alkali metal compound buffer layer typified by lithium fluoride, an alkaline earth metal compound buffer layer typified by magnesium fluoride, and an oxide buffer layer typified by aluminum oxide.

  The buffer layer (injection layer) is preferably a very thin film, and although it depends on the material, the film thickness is preferably in the range of 0.1 nm to 100 nm.

  As described above, the blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film. For example, it is described in JP-A Nos. 11-204258 and 11-204359, and “Organic EL elements and their forefront of industrialization” (issued by NTT, Inc. on November 30, 1998). There is a hole blocking (hole blocking) layer.

<Blocking layer: hole blocking layer, electron blocking layer>
The hole blocking layer is an electron transport layer in a broad sense, and is made of a material that has a function of transporting electrons and has a very small ability to transport holes. By blocking holes while transporting electrons, And the recombination probability of holes can be improved.

  The hole blocking layer has a role of blocking the holes moving from the hole transport layer from reaching the cathode and a compound that can efficiently transport the electrons injected from the cathode toward the light emitting layer. It is formed. The physical properties required of the material constituting the hole blocking layer are higher than the ionization potential of the light emitting layer in order to have high electron mobility and low hole mobility and to efficiently confine holes in the light emitting layer. It is preferable to have a value of ionization potential or a band gap larger than that of the light emitting layer.

  In the organic electroluminescence device of the present invention, it is preferable to provide a hole blocking layer adjacent to the light emitting layer. Thereby, the light emission luminance and the light emission efficiency can be further improved.

  In the present invention, the hole blocking layer is selected from a styryl derivative, a boron derivative, a carboline derivative, and a derivative group consisting of derivatives in which at least one carbon atom forming the carboline skeleton of the carboline derivative is substituted with a nitrogen atom. By containing at least one kind of derivative, emission luminance and emission efficiency can be further improved.

  In the organic electroluminescence device of the present invention, the hole blocking layer preferably contains at least one of the compounds represented by the general formulas (2) to (10). Luminous efficiency can be improved.

<< Compound Represented by Formula (2) >>
The compound represented by the general formula (2) will be described.

In the general formula (2), examples of the alkyl group represented by R ₁ and R ₂ include a methyl group, an ethyl group, a propyl group, an isopropyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, and dodecyl. Group, tridecyl group, tetradecyl group, pentadecyl group, trifluoromethyl group, pentafluoromethyl group, trifluoromethylmethyl group and the like.

In the general formula (2), examples of the alkoxyl group represented by R ₁ and R ₂ include a methoxy group, an ethoxy group, a butoxy group, a propyloxy group, a pentyloxy group, a hexyloxy group, an octyloxy group, and a dodecyloxy group. Groups and the like.

In the general formula (2), examples of the aryl group represented by R ₁ and R ₂ include a phenyl group, a tolyl group, a xylyl group, a biphenyl group, a naphthyl group, an anthryl group, and a phenanthryl group.

In the general formula (2), the alkyl group, alkoxyl group, and aryl group represented by R ₁ and R ₂ further have a substituent represented by R _{2 to} R ₉ in the general formula (1). Also good.

In the general formula (2), examples of the heterocyclic group represented by R ₃ and R ₄ include a furyl group, a thienyl group, a pyridyl group, a pyridazinyl group, a pyrimidinyl group, a pyrazinyl group, a triazinyl group, an imidazolyl group, and a pyrazolyl group. , Thiazolyl group, quinazolinyl group, phthalazinyl group, pyrrolidyl group, imidazolidyl group, quinoxalinyl group, morpholyl group, oxazolidyl group and the like.

In general formula (2), the aryl group represented by R ₃ and R ₄ has the same meaning as the aryl group represented by R ₁ and R ₂ in general formula (2).

In the general formula (2), the arylene group represented by Ar ₁₁ has the same meaning as the arylene group represented by Ar in the general formula (1).

<< Compound Represented by Formula (3) >>
The compound represented by the general formula (3) will be described.

In the general formula (3), examples of the aryl group represented by Ar ₁ include a phenyl group, a tolyl group, a xylyl group, a biphenyl group, a naphthyl group, an anthryl group, and a phenanthryl group.

In the general formula (3), examples of the aromatic heterocyclic group represented by Ar ₁ include a furyl group, a thienyl group, a pyridyl group, a pyridazinyl group, a pyrimidinyl group, a pyrazinyl group, a triazinyl group, an imidazolyl group, a pyrazolyl group, A thiazolyl group, a quinazolinyl group, a phthalazinyl group, etc. are mentioned.

In the general formula (3), each of the aryl group and aromatic heterocyclic group represented by Ar ₁ further has a substituent represented by R _{2 to} R ₉ in the general formula (1). You may do it.

<< Compounds Represented by General Formulas (4) to (8) >>
The compounds represented by each of the general formulas (4) to (8) will be described.

In the compounds represented by the general formula (4) to the general formula (8), the substituents represented by R ₁ and R ₂ may be R _{2 to} R ₉ in the general formula (1). It is synonymous with the substituent represented.

In the general formula (8), examples of the 6-membered aromatic heterocyclic ring each containing at least one nitrogen atom represented by Z ₁ , Z ₂ , Z ₃ , and Z ₄ include a pyridine ring and a pyridazine ring. , Pyrimidine ring, pyrazine ring and the like. Further, each of the 6-membered aromatic heterocycles each containing at least one nitrogen atom represented by Z ₁ , Z ₂ , Z ₃ and Z ₄ is further represented by R _{2 to} R ₉ in the general formula (1). You may have a substituent represented by these.

<< Compounds Represented by General Formulas (9) to (10) >>
In the general formula (9), examples of the 6-membered aromatic heterocyclic ring each containing at least one nitrogen atom represented by Z ₁ and Z ₂ include a pyridine ring, a pyridazine ring, a pyrimidine ring, and a pyrazine ring. Etc.

In the general formula (9), the arylene groups represented by Ar ₁ and Ar ₂ include o-phenylene group, m-phenylene group, p-phenylene group, naphthalenediyl group, anthracenediyl group, naphthacenediyl group, and pyrenediyl group. Group, naphthylnaphthalenediyl group, biphenyldiyl group (for example, 3,3′-biphenyldiyl group, 3,6-biphenyldiyl group, etc.), terphenyldiyl group, quaterphenyldiyl group, kinkphenyldiyl group, sexi Examples thereof include a phenyldiyl group, a septiphenyldiyl group, an octylphenyldiyl group, a nobiphenyldiyl group, and a deciphenyldiyl group. The arylene group may further have a substituent represented by R _{2 to} R ₉ in the general formula (1).

In the general formula (9), the divalent aromatic heterocyclic groups represented by Ar ₁ and Ar ₂ are furan ring, thiophene ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, benzo Imidazole ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, carbazole ring, carboline ring, And divalent groups derived from a ring in which the carbon atom of the hydrocarbon ring constituting the carboline ring is further substituted with a nitrogen atom. Furthermore, the aromatic heterocyclic group may have a substituent represented by R ₁₀₁ .

In the general formula (9), the divalent linking group represented by L has the same meaning as the divalent linking group represented by L ₁ in the general formula (10), but is preferably an alkylene group. , —O—, —S— and the like, are divalent groups containing a chalcogen atom, most preferably an alkylene group.

In the general formula (10), in Ar _1, Ar _2, the arylene group represented by each, in the general formula (9), is synonymous with the arylene group represented by each of Ar _1, Ar _2.

In the general formula (10), an aromatic heterocyclic group represented by each of Ar _1, Ar _2, in the general formula (9), the divalent aromatic heterocyclic ring represented by each of Ar _1, Ar ₂ Synonymous with group.

In the general formula (10), examples of the 6-membered aromatic heterocycle each containing at least one nitrogen atom represented by Z ₁ , Z ₂ , Z ₃ , and Z ₄ include a pyridine ring and a pyridazine ring. , Pyrimidine ring, pyrazine ring and the like.

In the general formula (10), the divalent linking group represented by L has the same meaning as the divalent linking group represented by L ₁ in the general formula (10), but is preferably an alkylene group. , —O—, —S— and the like, are divalent groups containing a chalcogen atom, most preferably an alkylene group.

  Specific examples of the compounds represented by the general formulas (2) to (10) according to the present invention are shown below, but the present invention is not limited thereto.

  Although the synthesis example of the compound of General formula (2)-(10) based on this invention is shown below, this invention is not limited to these.

  << Synthesis of Exemplary Compound 144 >>

  0.16 g of palladium acetate and 0.58 g of tri-tert-butylphosphine are dissolved in 10 ml of anhydrous toluene, 25 mg of sodium borohydride is added and stirred for 10 minutes at room temperature, then 2.00 g of δ-carboline, intermediate a3 20 g and 1.37 g of sodium tert-butoxide were dispersed in 50 ml of anhydrous xylene and stirred at reflux temperature for 10 hours under a nitrogen atmosphere. After allowing to cool, chloroform and water are added to separate the organic layer. The organic layer is washed with water and saturated brine and then concentrated under reduced pressure. The resulting residue is recrystallized from acetic acid to give colorless colorless compound of Exemplified Compound 144. 1.5 g of crystals were obtained.

The structure of exemplary compound 144 was confirmed by ¹ H-NMR spectrum and mass spectrometry spectrum. The spectrum data of the exemplary compound 144 are as follows.

MS (FAB) m / z: 647 (M ^{+ 1} )
¹ H-NMR (400 MHz, CDCl ₃ ) δ / ppm 1.80 (S, 12H), 7.27 (S, 4H), 7.34 (dd, J = 4.9 Hz, J = 8.3 Hz, 2H ), 7.3-7.4 (m, 2H), 7.4-7.5 (m, 12H), 7.76 (dd, J = 1.3 Hz, J = 8.3 Hz, 2H), 8 .45 (d, J = 7.8 Hz, 2H), 8.63 (dd, J = 1.3 Hz, J = 4.9 Hz, 2H)
<< Synthesis of Exemplary Compound 143 >>

  Add 4,5'-dichloro-3,3'-bipyridyl 0.85 g, diamine b 0.59 g, dibenzylideneacetone palladium 44 mg, imidazolium salt 36 mg, sodium tert-butoxide 1.09 g to dimethoxyethane 5 ml, 80 The mixture was stirred at 24 ° C. for 24 hours. After allowing to cool, chloroform and water were added to separate the organic layer, and the organic layer was washed with water and saturated brine and then concentrated under reduced pressure. The obtained residue was recrystallized from ethyl acetate to give Example Compound 143. 0.3 g of colorless crystals was obtained.

The structure of the exemplary compound 143 was confirmed by ¹ H-NMR spectrum and mass spectrometry spectrum. The spectrum data of the exemplary compound 143 are shown below.

MS (FAB) m / z 639 (M ^{+ 1} )
¹ H-NMR (400 MHz, CDCl ₃ ): δ / ppm 7.46 (d, J = 5.7 Hz, 4H), 7.6-7.7 (m, 4H), 7.8-7.9 ( m, 4H), 8.67 (d, J = 5.7 Hz, 4H), 9.51 (S, 4H)
<< Synthesis of Exemplary Compound 145 >>
In the synthesis of Exemplary Compound 143, the same procedure was performed except that 3- (2-chlorophenyl) -4-chloropyridine was used, in which one pyridine ring of 4,4′-dichloro-3,3′-bipyridyl was changed to benzene. Example compound 145 was synthesized.

The structure of exemplary compound 145 was confirmed by ¹ H-NMR spectrum and mass spectrometry spectrum. The spectrum data of the exemplary compound 145 are shown below.

MS (FAB) m / z 637 (M ^{+ 1} )
¹ H-NMR (400 MHz, CDCl ₃ ) δ / ppm 7.3-7.4 (m, 2H), 7.6-7.7 (m, 4H), 7.7-7.8 (m, 4H) ) 7.8-7.9 (m, 4H), 8.06 (d, J = 5.3 Hz, 2H), 8.23 (d, J = 7.8 Hz, 2H), 8.56 (d, J = 5.3 Hz, 2H), 8.96 (S, 2H)
In addition to the above synthesis examples, carboline derivatives of these organic EL device materials, derivatives in which at least one carbon atom forming the carboline skeleton of the carboline derivative is substituted with a nitrogen atom, and chloroplasts thereof are: J. et al. Chem. Soc. Perkin Trans. 1, 1505-1510 (1999), Pol. J. et al. Chem. , 54, 1585 (1980), (Tetrahedron Lett. 41 (2000), 481-484). Introduction of the synthesized azacarbazole ring or its chloroplast to the core or linking group of an aromatic ring, a heterocyclic ring, an alkyl group, etc. is known such as Ullman coupling, coupling using Pd catalyst, Suzuki coupling, etc. This method can be used.

  Examples of other compounds include exemplified compounds described in JP-A Nos. 2003-31367 and 2003-31368.

  On the other hand, the electron blocking layer is a hole transport layer in a broad sense, made of a material that has a function of transporting holes and has a very small ability to transport electrons, and blocks electrons while transporting holes. Thus, the probability of recombination of electrons and holes can be improved.

<Light emitting layer>
The light-emitting layer according to the present invention contains a light-emitting material, and is a layer that emits light by recombination of electrons and holes injected from an electrode, an electron transport layer, or a hole transport layer, and the light-emitting portion is a light-emitting layer The interface between the light emitting layer and the adjacent layer may be used.

  In the present invention, the light emitting layer contains a light emitting material and a compound (host compound) having a partial structure represented by the above general formula (1) and having a molecular weight of 1700 or less. As a result, high light emission luminance and high light emission efficiency are exhibited, and a long life is achieved.

  In the present invention, a phosphorescent compound is preferably used as the light emitting material. Thereby, high light emission luminance and light emission efficiency can be obtained. A phosphorescent compound is a compound in which light emission from an excited triplet is observed, is a compound that emits phosphorescence at room temperature (25 ° C.), and has a phosphorescence quantum yield of 0.01 or more at 25 ° C. It is. The phosphorescence quantum yield is preferably 0.1 or more.

  The phosphorescence quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of Experimental Chemistry Course 4 of the 4th edition. Although the phosphorescence quantum yield in a solution can be measured using various solvents, the phosphorescence quantum yield used in the present invention only needs to achieve the above phosphorescence quantum yield in any solvent.

  There are two types of light emission of phosphorescent compounds in principle. One is the recombination of carriers on the host compound to which carriers are transported to generate an excited state of the host compound, and this energy is phosphorescent. Energy transfer type to obtain light emission from the phosphorescent compound by transferring to the compound, the other is that the phosphorescent compound becomes a carrier trap, carrier recombination occurs on the phosphorescent compound, and from the phosphorescent compound In any case, the excited state energy of the phosphorescent compound is lower than the excited state energy of the host compound.

  The phosphorescent compound can be appropriately selected from known compounds used for the light emitting layer of the organic EL device.

  In the present invention, the phosphorescent compound is preferably an osmium, iridium, rhodium, or platinum complex compound, whereby the luminance and luminous efficiency can be further improved.

  Specific examples of the phosphorescent compound used in the present invention are shown below, but are not limited thereto. These compounds are described, for example, in Inorg. Chem. 40, 1704-1711, and the like.

  In the present invention, the phosphorescent maximum wavelength of the phosphorescent compound is not particularly limited. In principle, the phosphorescent compound can be obtained by selecting a central metal, a ligand, a ligand substituent, and the like. However, it is preferable that the phosphorescent compound has a phosphorescent maximum wavelength of 380 to 480 nm. Such a blue phosphorescent organic EL element or a white phosphorescent organic EL element can be an organic electroluminescent element having higher emission luminance and a longer half-life.

  In addition, by using a plurality of phosphorescent compounds, it is possible to mix different light emission, thereby obtaining an arbitrary emission color. White light emission is possible by adjusting the kind of phosphorescent compound and the amount of doping, and can also be applied to lighting devices and backlights.

  In addition to the host compound having a partial structure represented by the general formula (1) and a molecular weight of 1700 or less, a plurality of known host compounds may be used in combination in the light emitting layer. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient. As these known host compounds, compounds having a hole transporting ability and an electron transporting ability, preventing the emission of longer wavelengths, and having a high Tg (glass transition temperature) are preferable.

  Specific examples of known host compounds include compounds described in the following documents.

  JP-A-2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579, 2002-105445 gazette, 2002-343568 gazette, 2002-141173 gazette, 2002-352957 gazette, 2002-203683 gazette, 2002-363227 gazette, 2002-231453 gazette, No. 003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-286061, No. 2002-280183, No. 2002-299060, No. 2002. -302516, 2002-305083, 2002-305084, 2002-308837, and the like.

  Moreover, the light emitting layer may contain the host compound which has a fluorescence maximum wavelength further as a host compound. In this case, the energy transfer from the other host compound and the phosphorescent compound to the fluorescent compound allows electroluminescence as an organic EL element to be emitted from the other host compound having a fluorescence maximum wavelength. A host compound having a fluorescence maximum wavelength is preferably a compound having a high fluorescence quantum yield in a solution state. Here, the fluorescence quantum yield is preferably 10% or more, particularly preferably 30% or more. Specific host compounds having a maximum fluorescence wavelength include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, and pyrylium dyes. Perylene dyes, stilbene dyes, polythiophene dyes, and the like. The fluorescence quantum yield can be measured by the method described in 362 (1992, Maruzen) of Spectroscopic II of the Fourth Edition Experimental Chemistry Course 7.

  The color emitted in this specification is the spectral radiance meter CS-1000 (Minolta) in FIG. 4.16 on page 108 of “New Color Science Handbook” (Edited by the Japan Society for Color Science, University of Tokyo Press, 1985). It is determined by the color when the measured result is applied to the CIE chromaticity coordinates.

  The light emitting layer can be formed by forming the above compound by a known thinning method such as a vacuum deposition method, a spin coating method, a casting method, an LB method, or an ink jet method, but preferably by a spin coating method. is there. Although the film thickness as a light emitting layer does not have a restriction | limiting in particular, Usually, 5 nm-5 micrometers, Preferably it is chosen in the range of 5 nm-200 nm. The light emitting layer may have a single layer structure in which these phosphorescent compounds and host compounds are composed of one or more kinds, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions. Good.

《Hole transport layer》
The hole transport layer is made of a material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer and the electron transport layer can be provided as a single layer or a plurality of layers.

  The hole transport material is not particularly limited, and is conventionally used as a hole charge injection / transport material in an optical transmission material or a well-known material used for a hole injection layer or a hole transport layer of an EL element. Any one can be selected and used.

  The hole transport material has one of hole injection or transport and electron barrier properties, and may be either organic or inorganic. For example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples thereof include stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers.

  As the hole transport material, those described above can be used, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.

  Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl; N, N′-diphenyl-N, N′— Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N′-diphenyl-N, N ′ − (4-methoxyphenyl) -4,4′-diaminobiphenyl; N, N, N ′, N′-tetraphenyl-4,4′-diaminodiphenyl ether; 4,4′-bis (diphenylamino) quadriphenyl; N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 ′-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino- (2-diphenylvinyl) benzene; 3-methoxy-4′-N, N-diphenylaminostilbenzene; N-phenylcarbazole, and two more described in US Pat. No. 5,061,569 Having a condensed aromatic ring of, for example, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-30 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 688 are linked in a starburst type (MTDATA).

  Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material.

  In the present invention, the hole transport material of the hole transport layer preferably has a fluorescence maximum wavelength at 415 nm or less. That is, the hole transport material is preferably a compound that has a hole transport ability, prevents the emission of light from becoming longer, and has a high Tg.

  This hole transport layer can be formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, an ink jet method, or an LB method. Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, it is about 5-5000 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.

《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer used in the present invention can be provided as a single layer or a plurality of layers.

  Conventionally, in the case of a single electron transport layer and a plurality of layers, this electron transport layer is used as an electron transport material (also serving as a hole blocking material) used for the electron transport layer adjacent to the cathode side with respect to the light emitting layer. Examples of materials (hereinafter referred to as electron transport materials) used in the following are nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyrandioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadi And azole derivatives. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as an electron transport material.

  Further, the electron transport layer only needs to have a function of transmitting electrons injected from the cathode to the light emitting layer, and any material can be selected from conventionally known compounds. .

  Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  In addition, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum, Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), etc., and the central metals of these metal complexes are In, Mg, Cu Metal complexes replaced with Ca, Sn, Ga, or Pb can also be used as electron transport materials. In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transport material. In addition, the distyrylpyrazine derivative exemplified as the material of the light emitting layer can also be used as an electron transport material, and similarly to the hole injection layer and the hole transport layer, inorganic such as n-type-Si and n-type-SiC. A semiconductor can also be used as an electron transport material.

  It is preferable that the preferable compound used for an electron carrying layer has a fluorescence maximum wavelength in 415 nm or less. That is, the compound used for the electron transport layer is preferably a compound that has an electron transport ability, prevents emission of longer wavelengths, and has a high Tg.

  The electron transport layer can be formed by thinning the electron transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, an ink jet method, or an LB method. Although there is no restriction | limiting in particular about the film thickness of an electron carrying layer, Usually, it is about 5-5000 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

<< Substrate (also referred to as substrate, substrate, support, etc.) >>
The substrate that can be used in the organic EL device of the present invention is not particularly limited in the type of glass, plastic, and the like, and is not particularly limited as long as it is transparent. , Quartz, and a light-transmitting resin film. A particularly preferable substrate is a resin film that can give flexibility to the organic EL element.

  Examples of the resin film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), and cellulose. Examples include films made of triacetate (TAC), cellulose acetate propionate (CAP), and the like.

  An inorganic or organic coating or a hybrid coating of both may be formed on the surface of the resin film.

  The external extraction efficiency at room temperature of light emission of the organic electroluminescence device of the present invention is preferably 1% or more, more preferably 2% or more. Here, the external extraction quantum efficiency (%) = the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element × 100.

  Further, a hue improving filter such as a color filter may be used in combination.

  The multicolor display device of the present invention comprises at least two kinds of organic EL elements having different light emission maximum wavelengths, and a preferred example for producing the organic EL elements will be described.

<< Method for producing organic EL element >>
As an example of the method for producing the organic EL device of the present invention, a method for producing an organic EL device comprising an anode / anode buffer layer / light emitting layer / hole blocking layer / electron transport layer / cathode will be described.

  First, a layer made of a desired electrode material, for example, an anode material is formed on a suitable substrate by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably 10 nm to 200 nm. Make it. Next, an organic compound thin film of an anode buffer layer, a light emitting layer, a hole blocking layer, and an electron transport layer, which are element materials, is formed thereon.

As described above, there are spin coating methods, casting methods, ink jet methods, vapor deposition methods, printing methods, and the like as methods for thinning the organic compound thin films, but it is easy to obtain a uniform film and pinholes are not easily generated. In view of the above, the vacuum deposition method or the spin coating method is particularly preferable. Further, different film forming methods may be applied for each layer. When a vapor deposition method is employed for film formation, the vapor deposition conditions vary depending on the type of compound used, but generally a boat heating temperature of 50 to 450 ° C., a vacuum degree of 10 ⁻⁶ Pa to 10 ⁻² Pa, a vapor deposition rate of 0. It is desirable to select appropriately within the range of 01 nm to 50 nm / second, substrate temperature of −50 ° C. to 300 ° C., and film thickness of 0.1 nm to 5 μm.

  After the formation of these layers, a thin film made of a cathode material is formed thereon by a method such as vapor deposition or sputtering so as to have a thickness of 1 μm or less, preferably in the range of 50 nm to 200 nm, and a cathode is provided. Thus, a desired organic EL element can be obtained. The organic EL element is preferably produced from the hole injection layer to the cathode consistently by a single evacuation, but may be taken out halfway and subjected to different film forming methods. At that time, it is necessary to consider that the work is performed in a dry inert gas atmosphere.

  In the display device of the present invention, a shadow mask is provided only at the time of forming a light emitting layer, and the other layers are common, and a layer can be formed on one surface by a vapor deposition method, a cast method, a spin coating method, an ink jet method, a printing method, or the like.

  It is also possible to make each layer by reversing the production order.

  When a DC voltage is applied to the display device thus obtained, light emission can be observed by applying a voltage of about 2 to 40 V with the positive polarity of the anode and the 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 an AC voltage is applied, light is emitted only when the anode is in the + state and the cathode is in the-state. The alternating current waveform to be applied may be arbitrary.

  The display device of the present invention uses the organic EL element of the present invention and can be used as a display device, a display, or various light sources. In a display device or display, full-color display is possible by using three types of organic EL elements of blue, red, and green light emission.

  Examples of the display device and display include a television, a personal computer, a mobile device, an AV device, a character broadcast display, and an information display in an automobile. In particular, it may be used as a display device for reproducing still images and moving images, and the driving method when used as a display device for reproducing moving images may be either a simple matrix (passive matrix) method or an active matrix method.

  The lighting device of the present invention uses the organic EL element of the present invention, and is used for home lighting, interior lighting, clock backlight, billboard advertisement, traffic light, light source of optical storage medium, light source of electrophotographic copying machine, optical communication Examples include, but are not limited to, a light source for a processing machine and a light source for an optical sensor. It can also be used as a backlight for liquid crystal display devices and the like.

  Further, the organic EL element according to the present invention may be used as an organic EL element having a resonator structure.

  Examples of the purpose of use of the organic EL element having such a resonator structure include a light source of an optical storage medium, a light source of an electrophotographic copying machine, a light source of an optical communication processing machine, and a light source of an optical sensor. It is not limited. Moreover, you may use for the said use by making a laser oscillation.

  As described above, the organic EL element of the present invention may be used as one kind of lamp for illumination or exposure light source, or a projection device for projecting an image, or directly viewing a still image or a moving image. It may be used as a type of display device (display). When used as a display device for reproducing moving images, the driving method may be either a simple matrix (passive matrix) method or an active matrix method. Alternatively, a full-color display device can be manufactured by using three or more organic EL elements of the present invention having different emission colors. Alternatively, it is possible to make one color emission color, for example, white emission, into BGR by using a color filter to achieve full color. Furthermore, it is possible to convert the emission color of the organic EL to another color by using a color conversion filter, and in this case, λmax of the organic EL emission is preferably 480 nm or less.

  An example of a display device composed of the organic EL element of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic diagram illustrating an example of a display device including organic EL elements. It is a schematic diagram of a display such as a mobile phone that displays image information by light emission of an organic EL element.

  The display 1 includes a display unit A having a plurality of pixels, a control unit B that performs image scanning of the display unit A based on image information, and the like.

  The control unit B is electrically connected to the display unit A, and sends a scanning signal and an image data signal to each of the plurality of pixels based on image information from the outside. The pixels for each scanning line are converted into image data signals by the scanning signal. In response to this, light is sequentially emitted and image scanning is performed to display image information on the display unit A.

  FIG. 2 is a schematic diagram of the display unit A.

  The display unit A includes a wiring unit including a plurality of scanning lines 5 and data lines 6, a plurality of pixels 3 and the like on a substrate. The main members of the display unit A will be described below. FIG. 2 shows a case where the light emitted from the pixel 3 is extracted in the direction of the white arrow (downward).

  The scanning lines 5 and the plurality of data lines 6 in the wiring portion are each made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a grid pattern and are connected to the pixels 3 at orthogonal positions (details are shown in FIG. Not shown).

  When a scanning signal is applied from the scanning line 5, the pixel 3 receives an image data signal from the data line 6 and emits light according to the received image data. Full color display is possible by appropriately arranging pixels in the red region, the green region, and the blue region that emit light on the same substrate.

  Next, the light emission process of the pixel will be described.

  FIG. 3 is a schematic diagram of a pixel.

  The pixel includes an organic EL element 10, a switching transistor 11, a driving transistor 12, a capacitor 13, and the like. A full color display can be performed by using red, green, and blue light emitting organic EL elements as the organic EL elements 10 in a plurality of pixels, and juxtaposing them on the same substrate.

  In FIG. 3, an image data signal is applied from the control unit B to the drain of the switching transistor 11 through the data line 6. When a scanning signal is applied from the control unit B to the gate of the switching transistor 11 via the scanning line 5, the driving of the switching transistor 11 is turned on, and the image data signal applied to the drain is supplied to the capacitor 13 and the driving transistor 12. Is transmitted to the gate.

  By transmitting the image data signal, the capacitor 13 is charged according to the potential of the image data signal, and the drive of the drive transistor 12 is turned on. The drive transistor 12 has a drain connected to the power supply line 7 and a source connected to the electrode of the organic EL element 10, and the power supply line 7 connects to the organic EL element 10 according to the potential of the image data signal applied to the gate. Current is supplied.

  When the scanning signal is moved to the next scanning line 5 by the sequential scanning of the control unit B, the driving of the switching transistor 11 is turned off. However, even if the driving of the switching transistor 11 is turned off, the capacitor 13 maintains the potential of the charged image data signal, so that the driving of the driving transistor 12 is kept on and the next scanning signal is applied. Until then, the light emission of the organic EL element 10 continues. When the scanning signal is next applied by sequential scanning, the driving transistor 12 is driven according to the potential of the next image data signal synchronized with the scanning signal, and the organic EL element 10 emits light.

  That is, the organic EL element 10 emits light by the switching transistor 11 and the drive transistor 12 that are active elements for the organic EL element 10 of each of the plurality of pixels, and the light emission of the organic EL element 10 of each of the plurality of pixels 3. It is carried out. Such a light emitting method is called an active matrix method.

  Here, the light emission of the organic EL element 10 may be light emission of a plurality of gradations by a multi-value image data signal having a plurality of gradation potentials, or on / off of a predetermined light emission amount by a binary image data signal. But you can.

  The potential of the capacitor 13 may be held continuously until the next scanning signal is applied, or may be discharged immediately before the next scanning signal is applied.

  In the present invention, not only the active matrix method described above, but also a passive matrix light emission drive in which the organic EL element emits light according to the data signal only when the scanning signal is scanned.

  FIG. 4 is a schematic view of a passive matrix display device. In FIG. 4, a plurality of scanning lines 5 and a plurality of image data lines 6 are provided in a lattice shape so as to face each other with the pixel 3 interposed therebetween.

  When the scanning signal of the scanning line 5 is applied by sequential scanning, the pixels 3 connected to the applied scanning line 5 emit light according to the image data signal. In the passive matrix system, the pixel 3 has no active element, and the manufacturing cost can be reduced.

Example 1
<< Production and Evaluation of Organic EL Elements 1-1 to 1-29 >>
After patterning on a substrate (made by NH Techno Glass Co., Ltd .: NA-45) with a 150 nm ITO film on glass as the anode, the transparent support substrate provided with this ITO transparent electrode was ultrasonically cleaned with iso-propyl alcohol And dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes.

This transparent support substrate is fixed to a substrate holder of a commercially available vacuum deposition apparatus. On the other hand, α-NPD, CBP, Ir-1, BC, and Alq ₃ are placed in five molybdenum resistance heating boats, respectively. Installed.

Next, after the vacuum chamber was depressurized to 4 × 10 ⁻⁴ Pa, α-NPD was deposited on the transparent support substrate to a thickness of 20 nm to provide a hole injection / transport layer. Further, the heating boat containing CBP and the boat containing Ir-1 were energized independently to adjust the deposition rate of CBP and Ir-1 to 100: 7, so that the film thickness was 30 nm. The light emitting layer was provided by vapor deposition.

Next, BC was vapor-deposited to provide a 10 nm thick hole blocking layer. Furthermore, Alq ₃ was deposited to provide an electron transport layer having a thickness of 40 nm.

Next, the vacuum chamber is opened, a rectangular hole mask made of stainless steel is placed on the electron injection layer, and then the vacuum chamber is decompressed to 4 × 10 ⁻⁴ Pa, lithium fluoride 0.5 nm and aluminum 110 nm. The organic EL element 1-1 was produced by forming a cathode by vapor deposition.

  In the production of the organic EL element 1-1, the organic EL element 1-2 was prepared in the same manner as the organic EL element 1-1 except that the CBP used in the light emitting layer was changed to the compounds shown in Table 1. ˜1-29 was produced.

  The produced organic EL elements 1-1 to 1-29 were transferred to a glove box under nitrogen atmosphere (a glove box substituted with high-purity nitrogen gas with a purity of 99.999% or more) without being brought into contact with the air. The sealing structure as shown in (a) and (b) was adopted. In addition, barium oxide 25 which is a water catching agent is a glass sealing can 24 made of high-purity barium oxide powder manufactured by Aldrich with a fluororesin semi-permeable membrane (Microtex S-NTF8031Q manufactured by Nitto Denko) with an adhesive. The material pasted on was prepared and used in advance. An ultraviolet curable adhesive 27 was used for adhering the sealing can and the organic EL element, and an element having a sealing structure was produced by adhering and sealing both by irradiating an ultraviolet lamp. In the figure, 21 is a glass substrate provided with a transparent electrode, 22 is an organic EL layer comprising the hole injection / transport layer, light emitting layer, hole blocking layer, electron transport layer, cathode buffer layer and the like, and 23 is a cathode.

  Each of the obtained organic EL elements 1-1 to 1-29 was evaluated as follows.

<Emission brightness>
The produced organic EL device was measured for light emission luminance (L) [cd / m ² ] when a current of ^2.5 mA / cm ² was supplied at a temperature of 23 ° C. in a dry nitrogen gas atmosphere. Here, CS-1000 (manufactured by Minolta) was used for measurement of emission luminance and the like.

《External extraction quantum efficiency》
About the produced organic EL element, the external extraction quantum efficiency (%) when a ^2.5 mA / cm ² constant current was applied in a dry nitrogen gas atmosphere at 23 ° C. was measured. For the measurement, a spectral radiance meter CS-1000 (manufactured by Minolta) was used in the same manner.

《Half life》
When driving at a constant current of ^2.5 mA / cm ^{2 in} a dry nitrogen gas atmosphere at 23 ° C., the time required for the luminance to drop to half of the luminance immediately after the start of light emission (initial luminance) was measured. Was used as an index of life as half-life time (τ0.5). For the measurement, a spectral radiance meter CS-1000 (manufactured by Minolta) was used.

"Heat-resistant"
With respect to the produced organic EL element, the luminance (L) when a current of ^2.5 mA / cm ² was supplied at 23 degrees in a dry nitrogen gas atmosphere was measured, and this was set as the initial luminance (L0). Next, the device was stored in an 85 ° C. constant temperature bath for 500 hours. Then, after leaving it to 23 degrees, the luminance (L500) after the lapse of 500 hours was measured, and the luminance reduction rate was obtained from the following equation.

Luminance reduction rate (%) = [{(L0) − (L500)} / (L0)] × 100
In describing the evaluation results in Table 1, the light emission luminance, the external extraction quantum efficiency, and the light emission lifetime were expressed as relative values when each characteristic value of the organic EL element 1-1 was 100. The obtained results are shown in Table 1.

  From Table 1, it is clear that the organic EL device of the present invention is superior in all of the emission luminance, the external extraction quantum efficiency, and the emission lifetime as compared with the comparison. It was also found from the heat resistance test that the luminance characteristics under high temperature storage were also excellent.

  Further, except that Ir-1 which is a phosphorescent compound is changed to Ir-12, the organic EL elements 1-1B to 1-29B are similarly changed, and the same except that Ir-1 is changed to Ir-9. Thus, organic EL elements 1-1R to 1-29R were produced. In each of the organic EL elements, the same effect as that obtained when Ir-1 was used was obtained. Note that blue light emission was obtained from the element using Ir-12, and red light emission was obtained from the element using Ir-9.

Example 2
<< Production and Evaluation of Organic EL Elements 2-1 to 2-14 >>
In the production of the organic EL device 1-1 described in Example 1, the organic EL device was similarly prepared except that the CBP used for the light emitting layer and the BC used for the hole blocking layer were changed to the compounds shown in Table 2. Elements 2-1 to 2-14 were produced.

  Each of the obtained organic EL elements 2-1 to 2-14 was evaluated in the same manner as in Example 1 for evaluating the light emission luminance and the time to reduce the luminance by half, and Table 2 shows the obtained results.

  In addition, each evaluation result of Table 2 was represented by the relative value when the light-emitting luminance, the external extraction quantum efficiency, and the half life of the organic EL element 2-1 were set to 100, respectively.

  From Table 2, compared with the organic EL element 2-1 using the comparative compound, the organic EL elements 2-3 to 2-14 using the compound according to the present invention have any one of emission luminance, external extraction efficiency, and half-life. It is clear that this is also excellent.

  Further, except that Ir-1 which is a phosphorescent compound is changed to Ir-12, the organic EL elements 2-1B to 2-12B are similarly changed, and the same except that Ir-1 is changed to Ir-9. Thus, organic EL elements 2-1R to 2-12R were produced. Also in each of these organic EL elements, the courage EL element of the present invention has the same effect as when Ir-1 is used. Note that blue light emission was obtained from the element using Ir-12, and red light emission was obtained from the element using Ir-9.

Example 3
《Full color display device》
(Blue light emitting organic EL device)
The organic EL element 1-13B produced in Example 1 was used.

(Green light-emitting organic EL device)
The organic EL element 1-13 produced in Example 1 was used.

(Red light emitting organic EL device)
The organic EL element 1-13R produced in Example 1 was used.

  The red, green and blue light-emitting organic EL elements are juxtaposed on the same substrate to produce an active matrix type full-color display device having the form shown in FIG. 1, and FIG. 2 shows the display of the produced display device. Only the schematic diagram of part A is shown. That is, a wiring portion including a plurality of scanning lines 5 and data lines 6 on the same substrate, and a plurality of juxtaposed pixels 3 (light emission color is a red region pixel, a green region pixel, a blue region pixel, etc.) The scanning lines 5 and the plurality of data lines 6 in the wiring portion are each made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a lattice shape and are connected to the pixels 3 at the orthogonal positions ( Details are not shown). The plurality of pixels 3 are driven by an active matrix system provided with an organic EL element corresponding to each emission color, a switching transistor as an active element, and a driving transistor, and a scanning signal is applied from a scanning line 5. Then, an image data signal is received from the data line 6 and light is emitted according to the received image data. In this way, a full color display device was produced by appropriately juxtaposing the red, green, and blue pixels.

  It was confirmed that by driving the full-color display device, a full-color moving image display having a high light emission efficiency and a long light emission life can be obtained.

Example 4: (Example of lighting device, using white organic EL element)
In the organic EL element 2-9 produced in Example 2, it is the same as the organic EL element 1-9 except that Ir-1 used in the light emitting layer was changed to a mixture of Ir-1, Ir-9, and Ir-12 The organic EL device 2-9W produced by the method was used. The non-light emitting surface of the organic EL element 2-9W was covered with a glass case to obtain a lighting device. The illuminating device could be used as a thin illuminating device that emits white light with high luminous efficiency and long emission life. FIG. 6 is a schematic view of the lighting device, and FIG. 7 is a cross-sectional view of the lighting device. The organic EL element 101 is covered with a glass cover 102 and connected with a power line (anode) 103 and a power line (cathode) 104. 105 is a cathode and 106 is an organic EL layer. The glass cover 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided.

It is the schematic diagram which showed an example of the display apparatus comprised from an organic EL element. It is a schematic diagram of a display part. It is a schematic diagram of a pixel. It is a schematic diagram of a passive matrix type full-color display device. It is a schematic diagram of the organic EL element which has a sealing structure. It is the schematic of an illuminating device. It is sectional drawing of an illuminating device. It is a chart of the spectrum of the compound of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Display 3 Pixel 5 Scan line 6 Data line 7 Power supply line 10, 101 Organic EL element 11 Switching transistor 12 Drive transistor 13 Capacitor A Display part B Control part 21, 107 Glass substrate 22 with transparent electrode 22, 106 Organic EL layer 23, 105 Cathode 24 Glass sealing can 25, 109 Water catching agent 27 UV curable adhesive 102 Glass cover 103 Power line (anode)
104 Power line (cathode)
108 nitrogen gas

Claims (10)

In an organic electroluminescence device having at least a light emitting layer and a hole blocking layer adjacent to the light emitting layer,
The light-emitting layer, molecular weight is not more than 500 1700 or less and at least one contains a compound represented by the following general formula (11), and, the hole blocking layer, a carboline skeleton mosquito Ruborin derivatives An organic electroluminescence device comprising at least one derivative selected from the group consisting of derivatives in which at least one carbon atom to be formed is substituted with a nitrogen atom.

Wherein, J represents a substituent methyl group which may have a may have a ethyl which may have a substituent group or a substituted aryl group, R ₁ is hydrogen Represents an atom, a methyl group, an ethyl group, an isopropyl group, a cyclohexyl group or a benzyl group, Ar represents a phenylene group which may have a substituent or a biphenyldiyl group which may have a substituent, and R ₄ and R ₇ each represents a hydrogen atom, a methyl group, a methoxy group, or a phenyl group that may substitute a methyl group, and R ₂ , R ₃ , R ₅ , R ₆ , R ₈ , R ₉ are each Represents a hydrogen atom, and n represents an integer of 1 to 6. ] 2. The organic electroluminescence device according to claim 1, wherein Ar in the general formula (11) is a phenylene group which may have a substituent. The organic electroluminescence device according to claim ₁ , wherein R ₁ in the general formula (11) is a hydrogen atom. At least one at least one carbon atom of at least one derivative selected from the derivatives substituted at the nitrogen atom, selected from B-14 and B-29 below to form a carboline skeleton before asked Ruborin derivatives the organic electroluminescent device according to any one of claims 1 to 3, characterized in that.

The organic light-emitting device according to claim 1, wherein the light-emitting layer contains a phosphorescent compound. 6. The organic electroluminescence device according to claim 5, wherein the phosphorescent compound is osmium, iridium, rhodium, or a platinum complex compound. The organic electroluminescent element according to claim 1, which emits white light. A display device comprising the organic electroluminescence element according to claim 1. The illuminating device provided with the organic electroluminescent element of any one of Claims 1-7. A display device comprising the illumination device according to claim 9 and a liquid crystal element as a display unit.

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