JPWO2008156105A1 - ORGANIC ELECTROLUMINESCENT ELEMENT MATERIAL, ORGANIC ELECTROLUMINESCENT ELEMENT, DISPLAY DEVICE AND LIGHTING DEVICE - Google Patents

Abstract

The present invention provides a novel organic EL element material, and by using the organic EL element material, an organic EL element that exhibits high luminous efficiency and has a long emission lifetime, an illumination device using the organic EL element, and A display device is provided.

Description

  The present invention relates to an organic electroluminescence element material, an organic electroluminescence element, a display device, and a lighting device.

  Conventionally, as a light-emitting electronic display device, there is an electroluminescence display (hereinafter referred to as ELD). Examples of the constituent elements of ELD include inorganic electroluminescent elements and organic electroluminescent elements (hereinafter also referred to 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. An organic EL device has a structure in which a light emitting layer containing a compound that emits light is sandwiched between a cathode and an anode, and injects electrons and holes into the light emitting layer and recombines them to generate excitons. This is an element that emits light by using light emission (fluorescence / phosphorescence) when this exciton is deactivated, and can emit light at a voltage of several volts to several tens of volts. Therefore, 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 and portability.

  However, in organic EL elements for practical use in the future, development of organic EL elements that emit light efficiently and with high luminance with lower power consumption is desired.

  In Japanese Patent No. 3093796, a small amount of phosphor is doped into a stilbene derivative, a distyrylarylene derivative or a tristyrylarylene derivative to achieve an improvement in light emission luminance and a longer device lifetime. Further, an element having an organic light-emitting layer in which an 8-hydroxyquinoline aluminum complex is used as a host compound and a small amount of phosphor is doped thereto (for example, JP-A 63-264692), and an 8-hydroxyquinoline aluminum complex is used as a host compound. For example, an element having an organic light emitting layer doped with a quinacridone dye (for example, JP-A-3-255190) is known.

  As described above, when light emission from excited singlet is used, the generation ratio of singlet excitons and triplet excitons is 1: 3, and thus the generation probability of luminescent excited species is 25%. Since the efficiency is about 20%, the limit of the external extraction quantum efficiency (ηext) is set to 5%.

  However, since Princeton University reported on an organic EL device using phosphorescence emission from an excited triplet (MA Baldo et al., Nature, 395, 151-154 (1998)), Research on materials that exhibit phosphorescence has become active. For example, M.M. A. Baldo et al. , Nature, 403, 17, 750-753 (2000), US Pat. No. 6,097,147, and the like.

  When the excited triplet is used, the upper limit of the internal quantum efficiency is 100%, so that in principle, the luminous efficiency is four times that of the excited singlet, and there is a possibility that almost the same performance as a cold cathode tube can be obtained. Therefore, it is attracting attention as a lighting application.

  For example, S.M. Lamansky et al. , J .; Am. Chem. Soc. , 123, 4304 (2001), etc., many compounds are being studied for synthesis centering on heavy metal complexes such as iridium complexes. In addition, the aforementioned M.I. A. Baldo et al. , Nature, 403, 17, 750-753 (2000), studies have been made using tris (2-phenylpyridine) iridium as a dopant.

In addition, M.M. E. Thompson et al., In The 10th International Works on Inorganic and Organic Electroluminescence (EL'00, Hamamatsu), used L ₂ Ir (acac), for example, (ppy) ₂ Ir (acac), e 0 g, Tetsuo Tsutsui, etc., again The 10th International Workshop on Inorganic and Organic Electroluminescence (EL'00, Hamamatsu) in, as a dopant tris (2-(p-tolyl) pyridine) iridium (Ir _{(ptpy) 3),} tris Investigations using (benzo [h] quinoline) iridium (Ir (bzq) ₃ ) or the like are being conducted (note that these metal complexes are generally called orthometalated iridium complexes).

  In addition, S. Lamansky et al. , J .; Am. Chem. Soc. , 123, 4304 (2001), etc., attempts have been made to form devices using various iridium complexes.

  Orthometalated complexes in which the central metal is platinum instead of iridium are also attracting attention. With regard to this type of complex, many examples in which a ligand is characterized are known (for example, JP 2002-332291 A, JP 2002-332292 A, JP 2002-338588 A, JP 2002-226495 A, JP 2002-234894 A, etc.).

  As host compounds of these phosphorescent dopants, carbazole derivatives represented by CBP and m-CP are well known. However, m-CP and derivatives thereof are known as blue light-emitting host compounds, but the efficiency and life are not fully satisfied (for example, see Patent Documents 1 and 2).

  In addition, a host compound is disclosed in which a plurality of carbazole skeletons are bonded to a linking group at different positions (see, for example, Patent Document 3).

  Further, a compound in which a plurality of carbazole skeletons are bonded to a dibenzofuran unit is known (for example, see Patent Document 4).

Although the efficiency and life are improved to some extent by using these, further improvement has been desired.
International Publication No. 03/80760 Pamphlet WO04 / 74399 pamphlet JP 2004-217557 A International Publication No. 06/128800 Pamphlet

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a novel organic EL element material, and by using the organic EL element material, it exhibits high luminous efficiency and has a luminous lifetime. An organic EL element having a long length, a lighting device using the organic EL element, and a display device are provided.

  The above object of the present invention has been achieved by the following constitution.

  1. An organic electroluminescent element material comprising a compound represented by the following general formula (1):

[In the formula, R represents an alkyl group, a cycloalkyl group having 5 or more carbon atoms or an aromatic hydrocarbon group, and R ₁ , R ₂ , R ₃ and R ₄ represent a halogen atom, an alkyl group and a carbon number, respectively. Represents a cycloalkyl group, an aromatic hydrocarbon group or an aromatic heterocyclic group having 5 or more. n1, n2, n3, and n4 each represents an integer of 0 to 2. X represents a divalent linking group selected from the group consisting of the following general formulas (2), (3), (4) and an alkylene group. n represents an integer of 1 or more. ]

[Wherein R ₅ , R ₆ , R ₇ and R ₈ each represent a halogen atom, an alkyl group, a cycloalkyl group having 5 or more carbon atoms, or an aromatic hydrocarbon group. n5, n6, n7, and n8 each represents an integer of 0 to 3. Y represents an oxygen atom or a sulfur atom. ]
2. 2. The organic electroluminescent element material according to 1, wherein X in the general formula (1) is a divalent linking group represented by the general formula (2) or (3).

  3. X in the general formula (1) is a divalent linking group represented by the general formula (3), and Y in the general formula (3) represents an oxygen atom. Or the organic electroluminescent element material of 2.

  4). R of said General formula (1) represents an aromatic hydrocarbon group, The organic electroluminescent element material of any one of said 1-3 characterized by the above-mentioned.

5). The substituent represented by R _{1 to} R ₈ represents an alkyl group or an aromatic hydrocarbon group, and n1 to n8 are 0 or 1, according to any one of the above 1 to 4, Organic electroluminescence element material.

6). In an organic electroluminescence device containing at least a light emitting layer sandwiched between an anode and a cathode,
This light emitting layer contains the organic electroluminescent element material of any one of said 1-5, The organic electroluminescent element characterized by the above-mentioned.

  7). 7. The organic electroluminescence device as described in 6 above, wherein the light emitting layer contains a phosphorescent metal complex.

  8). 8. The organic electroluminescence device as described in 7 above, wherein the phosphorescent metal complex is an Ir complex.

  9. A display device comprising the organic electroluminescence element according to any one of 6 to 8 above.

  10. It has an organic electroluminescent element of any one of said 6-8, The illuminating device characterized by the above-mentioned.

  According to the present invention, a novel organic EL element material is provided, and by using the organic EL element material, an organic EL element that exhibits high light emission efficiency and has a long emission lifetime, an illumination device using the organic EL element, and A display device could be provided.

The schematic block diagram of an organic electroluminescent full color display apparatus is shown. ¹ H-NMR (nuclear magnetic resonance) spectrum of Exemplified Compound 25 is shown.

Explanation of symbols

101 Glass substrate 102 ITO transparent electrode 103 Partition 104 Hole injection layer 105B, 105G, 105R Light emitting layer

  In the organic EL element material of the present invention, the organic EL element material useful for the organic EL element has been successfully molecularly designed by the configuration defined in any one of claims 1 to 5. In addition, by using the organic EL element material, it was possible to provide an organic EL element, a lighting device, and a display device that exhibit high light emission efficiency and have a long light emission lifetime.

<< Organic EL element material (Organic electroluminescence element material) >>
The organic EL element material of the present invention will be described.

  As described in claim 1, the organic EL device material of the present invention is characterized by containing a compound represented by the above general formula (1).

  The organic EL device material of the present invention containing the compound represented by the general formula (1) is preferably used for the light emitting layer of the organic EL device of the present invention, and particularly preferably used as a host compound in the light emitting layer. That is. The constituent layers and host compounds of the organic EL device of the present invention will be described in detail later.

<< Compound Represented by Formula (1) >>
The compound represented by the general formula (1) according to the present invention will be described.

In the general formula (1), examples of the halogen atom represented by R _{1 to} R ₄ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

In the general formula (1), the alkyl groups represented by R and R _{1 to} R ₄ are each a linear or branched alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, or a tert-butyl group. Pentyl group, hexyl group, octyl group, 2-ethylhexyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group and the like.

In the general formula (1), examples of the cycloalkyl group having 5 or more carbon atoms each represented by R and R _{1 to} R ₄ include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, Cyclodecyl group, cycloundecyl group, cyclododecyl group, methylcyclopentyl group, n-propylcyclopentyl group, isopropylcyclopentyl group, n-butylcyclopentyl group, isobutylcyclopentyl group, tert-butylcyclopentyl group, methylcyclohexyl group, n-propylcyclohexyl Group, isopropylcyclohexyl group, n-butylcyclohexyl group, isobutylcyclohexyl group, tert-butylcyclohexyl group, methylcycloheptyl group, n-propylcycloheptyl group, isopropylcyclohexyl group Tyl group, n-butylcycloheptyl group, isobutylcycloheptyl group, tert-butylcycloheptyl group, methylcyclooctyl group, n-propylcyclooctyl group, isopropylcyclooctyl group, n-butylcyclooctyl group, isobutylcyclooctyl group , Tert-butylcyclooctyl group and the like.

  Of these, a cyclohexyl group is preferred.

  In the general formula (1), examples of the aromatic hydrocarbon group represented by R (also referred to as an aryl group) include a phenyl group, a p-chlorophenyl group, a mesityl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group. , Azulenyl group, acenaphthenyl group, fluorenyl group, phenanthryl group, indenyl group, pyrenyl group, biphenylyl group and the like.

In the general formula (1), each group such as R, R _{1 to} R ₄ , an alkyl group, a cycloalkyl group having 5 or more carbon atoms, and an aromatic hydrocarbon group is represented by the general formula (1). in, _R, it may further have each a group represented by R 1 to R _4.

Furthermore, in the general formula (1), the alkyl group represented by R, R _{1 to} R ₄ , a cycloalkyl group having 5 or more carbon atoms, and the aromatic hydrocarbon group include the alkyl group and the cycloalkyl group. A preferred embodiment is that the atoms constituting the aromatic hydrocarbon group are composed of atoms selected from a group of atoms selected from the group consisting of carbon atoms and hydrogen atoms.

In the general formula (1), examples of the aromatic heterocyclic group represented by R ₁ , R ₂ , R ₃ , and R ₄ include a pyridyl group, a pyrimidinyl group, a furyl group, a pyrrolyl group, an imidazolyl group, and a benzimidazolyl group. , Pyrazolyl group, pyrazinyl group, triazolyl group (for example, 1,2,4-triazol-1-yl group, 1,2,3-triazol-1-yl group, etc.), oxazolyl group, benzoxazolyl group, thiazolyl Group, isoxazolyl group, isothiazolyl group, furazanyl group, thienyl group, quinolyl group, benzofuryl group, dibenzofuryl group, benzothienyl group, dibenzothienyl group, indolyl group, carbazolyl group, carbolinyl group, diazacarbazolyl group One of the carbon atoms constituting the carboline ring of the group is replaced with a nitrogen atom Quinoxalinyl group, pyridazinyl group, triazinyl group, quinazolinyl group, phthalazinyl group, and the like. These groups may be unsubstituted or may further have a substituent.

  In general formula (1), n1, n2, n3, and n4 each independently represents an integer of 0 to 2. Of these, 0 or 1 is preferred.

  In the general formula (1), X represents a divalent linking group selected from the group consisting of the following general formulas (2), (3), (4) and an alkylene group.

In X of the general formula (1), the halogen atom, alkyl group, cycloalkyl group having 5 or more carbon atoms, aromatic carbonization represented by R ₅ which the divalent linking group represented by the general formula (2) has A hydrogen group, a halogen atom, an alkyl group, a cycloalkyl group having 5 or more carbon atoms, or an aromatic hydrocarbon group, each represented by R ₆ and R ₇ of the divalent linking group represented by the general formula (3) The halogen atom, alkyl group, cycloalkyl group having 5 or more carbon atoms, and aromatic hydrocarbon group represented by R ₈ in the divalent linking group represented by the general formula (4) are each represented by the general formula ( in 1), R, each represented by a halogen atom in R ₁ to R _4, the alkyl group has a carbon number of 5 or more cycloalkyl groups, it is synonymous with an aromatic hydrocarbon group.

  Examples of the alkylene group represented by X in the general formula (1) include an ethylene group, a trimethylene group, a tetramethylene group, a propylene group, an ethylethylene group, a pentamethylene group, and a hexamethylene group.

These groups also have a halogen atom, an alkyl group, a cycloalkyl group having 5 or more carbon atoms or an aromatic hydrocarbon group represented by R, R _{1 to} R ₄ in the general formula (1). You may do it.

Further, in the above general formula (2) to _(4), the _{n 5, n 6, n 7} , n 8 each independently represents an integer of 0 to 3, preferably _{n 5, n 6, n 7} , n ₈ is 0 or 1.

  Furthermore, Y in the general formula (3) represents an oxygen atom or a sulfur atom, and an oxygen atom is preferred.

  Hereinafter, although the specific example of a compound represented by General formula (1) based on this invention is shown, this invention is not limited to these.

  Hereinafter, although an example of the synthesis | combination of the compound represented by General formula (1) based on this invention is shown, this invention is not limited to these.

  << Synthesis Example 1; Synthesis of Exemplified Compound 3 >>

(Synthesis of Intermediate 1)
Carbazole 33.4 g (200 mmol), 1,3-diiodobenzene 79.2 g (240 mmol), copper powder 0.64 g, potassium carbonate 55.3 g (400 mmol) was added to N, N-dimethylacetamide 500 ml, The mixture was heated and refluxed for 7 hours.

  After the reaction solution was cooled to room temperature, copper was filtered off, water was added, and the mixture was extracted with ethyl acetate. The organic layer was repeatedly washed with water and concentrated under reduced pressure.

  The obtained oily substance was purified by silica gel column chromatography to obtain 59.8 g of Intermediate 1. The yield was 81%.

  The structure of the obtained intermediate 1 was confirmed by a nuclear magnetic resonance spectrum and a mass spectrum.

(Synthesis of Exemplary Compound 3)
36.9 g of intermediate 1 (100 mmol), 28.7 g of intermediate 2 (100 mmol), tetrakistriphenylphosphine palladium 5.8 g, potassium carbonate 41.5 g (300 mmol), 1,2-dimethoxyethane 260 ml, water 165 ml In addition, the mixture was heated to reflux for 6 hours under a nitrogen stream. The reaction solution was cooled to room temperature, extracted with ethyl acetate, the organic layer was washed with water, and the solvent was distilled off under reduced pressure. The obtained candy-like substance was purified by silica gel column chromatography to obtain 43.6 g of Exemplified Compound 3. The yield was 90%.

  The structure of the exemplified compound was confirmed by nuclear magnetic resonance spectrum and mass spectrum.

  << Synthesis Example 2; Synthesis of Exemplified Compound 25 >>

(Synthesis of Intermediate 3)
Stirring was performed for 3 hours while heating 67.3 g (400 mmol) of dibenzofuran, 85.6 g (400 mmol) of potassium iodate, and 66.4 g (400 mmol) of potassium iodide in 80 ml of acetic acid at 80 to 90 ° C.

  The reaction solution was cooled to room temperature, poured into water, and the precipitated solid was collected by filtration, washed with water and dried to obtain 157.9 g of Intermediate 3. The yield was 94%.

  The structure of the obtained intermediate 3 was confirmed by a nuclear magnetic resonance spectrum and a mass spectrum.

(Synthesis of Intermediate 4)
100.8 g of intermediate 3 (240 mmol), 57.4 g of intermediate 2 (200 mmol), tetrakistriphenylphosphine palladium 10.6 g, potassium carbonate 83.0 g (600 mmol), 1,2-dimethoxyethane 950 ml, water 440 ml In addition, the mixture was heated to reflux for 6 hours under a nitrogen stream.

  The reaction solution was cooled to room temperature, extracted with ethyl acetate, the organic layer was washed with water, and the solvent was distilled off under reduced pressure. The obtained candy-like substance was purified by silica gel column chromatography to obtain 77.1 g of Exemplified Compound 4. The yield was 72%.

  The structure of the obtained intermediate 4 was confirmed by nuclear magnetic resonance spectrum and mass spectrum.

(Synthesis of Exemplified Compound 25)
Add 16.7 g (100 mmol) of carbazole, 53.5 g (100 mmol) of intermediate 4, 0.32 g of copper powder, and 280 ml of N, N-dimethylacetamide, 27.7 g (200 mmol) of potassium carbonate, and heat under nitrogen flow for 8 hours. Reflux was performed.

  After the reaction solution was cooled to room temperature, copper was filtered off, water was added, and the mixture was extracted with ethyl acetate. The organic layer was repeatedly washed with water and concentrated under reduced pressure.

  The obtained oily substance was purified by silica gel column chromatography to obtain 46.0 g of Exemplified Compound 25. The yield was 80%.

  The structure of the exemplified compound 25 was confirmed by a nuclear magnetic resonance spectrum and a mass spectrum.

A ¹ H-NMR (nuclear magnetic resonance) spectrum of Exemplified Compound 25 is shown in FIG.

The measurement conditions for ¹ H-NMR (nuclear magnetic resonance) are shown below.

POINT: 32768 POINT
SAMPO: 32768 POINT
FREQU: 7993.6Hz
FILTER: 4000Hz
DELAY: 50.0 μsec
DEADT: 71.9 μsec
INTVL: 125.1 μsec
TIMES: 8times
DUMMY: 0times
PD: 2.9007 sec
ACQTM: 4099.2769 msec
PREDL: 10.000 msec
INIWT: 0.5000msec
RESOL: 0.24Hz
PW1: 6.15 μsec
OBNUC: 1H
OBFRQ: 399.65MHz
OBSET: 134300.00Hz
RGAIN: 22
SCANS: 8times
SLVNT: CDCL3
SPINNING: 13Hz
TEMP: 24.2 ° C
Here, the constituent layers of the organic EL element of the present invention will be described. In this invention, although the preferable example of the laminated constitution of an organic EL element is shown below, this invention is not limited to these.

(I) Anode / light emitting layer / electron transport layer / cathode (ii) Anode / hole transport layer / light emitting layer / electron transport layer / cathode (iii) Anode / hole transport layer / light emitting layer / hole blocking layer / electron Transport layer / cathode (iv) Anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode (v) Anode / anode buffer layer / hole transport layer / light emitting layer / hole Blocking layer / electron transport layer / cathode buffer layer / cathode In the organic EL device of the present invention, the blue light emitting layer preferably has a light emission maximum wavelength of 430 nm to 480 nm, and the green light emitting layer has a light emission maximum wavelength of 510 nm to 550 nm, The red light emitting layer is preferably a monochromatic light emitting layer having a light emission maximum wavelength in the range of 600 nm to 640 nm, and is preferably a display device using these.

  Alternatively, a white light emitting layer may be formed by laminating at least three light emitting layers. Further, a non-light emitting intermediate layer may be provided between the light emitting layers.

  The organic EL element of the present invention is preferably a white light emitting layer, and is preferably a lighting device using these.

  Each layer which comprises the organic EL element of this invention is demonstrated.

"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, these electrode materials may be formed into a thin film 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 pattern accuracy is not required (about 100 μm or more) A pattern may be formed through a mask having a desired shape at the time of vapor deposition or sputtering of the electrode material.

  Or when using the substance which can be apply | coated like an organic electroconductivity compound, wet film-forming methods, such as a printing system and a coating system, can also be used.

  When light emission is extracted from the anode, it is desirable that the transmittance be 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, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. 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 5 μm, preferably 50 to 200 nm. In order to transmit the emitted 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.

  Moreover, after producing the said metal with a film thickness of 1-20 nm on a cathode, a transparent or semi-transparent cathode can be produced by producing the electroconductive transparent material quoted by description of the anode on it, By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.

  Next, an injection layer, a blocking layer, an electron transport layer, and the like 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, it 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. May be.

  An injection layer is a layer provided between an electrode and an organic layer in order to reduce drive voltage and improve light emission luminance. “Organic EL element and its forefront of industrialization (issued by NTT Corporation on November 30, 1998) 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.

  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. Specifically, strontium, aluminum, etc. Metal buffer layer represented by lithium, alkali metal compound buffer layer represented by lithium fluoride, alkaline earth metal compound buffer layer represented by magnesium fluoride, oxide buffer layer represented by aluminum oxide, etc. . The buffer layer (injection layer) is preferably a very thin film, and the film thickness is preferably in the range of 0.1 nm to 5 μm although it depends on the material.

<Blocking layer: hole blocking layer, electron blocking layer>
The blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film as described above. For example, it is described in JP-A Nos. 11-204258, 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.

  The hole blocking layer has a function of an electron transport layer in a broad sense, and is made of a hole blocking material that has a function of transporting electrons and has a remarkably small ability to transport holes. The probability of recombination of electrons and holes can be improved by blocking. Moreover, the structure of the electron carrying layer mentioned later can be used as a hole-blocking layer concerning this invention as needed.

  The hole blocking layer of the organic EL device of the present invention is preferably provided adjacent to the light emitting layer.

  In the present invention, when a plurality of light emitting layers having different light emission colors are provided, the light emitting layer having the shortest wavelength of light emission is preferably closest to the anode among all the light emitting layers. In this case, it is preferable to additionally provide a hole blocking layer between the shortest wave layer and the light emitting layer next to the anode next to the anode. Furthermore, it is preferable that 50% by mass or more of the compound contained in the hole blocking layer provided at the position has an ionization potential of 0.3 eV or more larger than the host compound of the shortest wave emitting layer.

  The ionization potential is defined by the energy required to emit electrons at the HOMO (highest occupied molecular orbital) level of the compound to the vacuum level, and can be determined by, for example, the following method.

  (1) Using Gaussian 98 (Gaussian 98, Revision A.11.4, MJ Frisch, et al, Gaussian, Inc., Pittsburgh PA, 2002.), a molecular orbital calculation software manufactured by Gaussian, USA. The ionization potential can be obtained as a value obtained by rounding off the second decimal place of the value (eV unit converted value) calculated by performing structural optimization using B3LYP / 6-31G *. The reason why this calculated value is effective is that there is a high correlation between the calculated value obtained by this method and the experimental value.

  (2) The ionization potential can also be obtained by a method of directly measuring by photoelectron spectroscopy. For example, a method known as ultraviolet photoelectron spectroscopy can be suitably used by using a low energy electron spectrometer “Model AC-1” manufactured by Riken Keiki Co., Ltd.

  On the other hand, the electron blocking layer has a function of a hole transport layer in a broad sense, and is made of a material that has a function of transporting holes and has an extremely small ability to transport electrons, and transports electrons while transporting holes. By blocking, the recombination probability of electrons and holes can be improved. Moreover, the structure of the positive hole transport layer mentioned later can be used as an electron blocking layer as needed. The film thickness of the hole blocking layer and the electron transport layer according to the present invention is preferably 3 nm to 100 nm, and more preferably 5 nm to 30 nm.

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

  The light emitting layer of the organic EL device of the present invention preferably contains a compound represented by the general formula (1) as a host compound. In the present invention, a known host compound may be used in combination.

  Here, in the present invention, the host compound means a phosphorescent quantum yield of phosphorescence emission at a room temperature (25 ° C.) having a mass ratio of 20% or more in the compound contained in the light emitting layer. Is defined as a compound of less than 0.1. The phosphorescence quantum yield is preferably less than 0.01.

  Further, a plurality of known host compounds may be used in combination. 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.

  In addition, by using the compounds represented by the general formulas (A) and (1) to (3) according to the present invention, it is possible to mix different light emission, thereby obtaining any light emission color. White light emission is possible by adjusting the kind of the luminescent metal complex and the doping amount, and it can be applied to illumination and backlight.

  As a known host compound that may be used in combination, a compound that has a hole transporting ability and an electron transporting ability, prevents the emission of light from being increased in wavelength, and has a high Tg (glass transition temperature) is preferable.

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

  JP 2001-257076 A, JP 2002-308855 A, JP 2001-313179 A, 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.

  In the present invention, in the case of having a plurality of light emitting layers, it is preferable that 50% by mass or more of the host compound in each layer is the same compound because it is easy to obtain a uniform film property over the entire organic layer. It is more preferable that the phosphorescence emission energy of the compound is 2.9 eV or more because it is advantageous in efficiently suppressing energy transfer from the dopant and obtaining high luminance.

  The phosphorescence emission energy as referred to in the present invention refers to the peak energy of the 0-0 band of phosphorescence emission by measuring the photoluminescence of a deposited film of 100 nm on a substrate with a host compound.

  The host compound used in the present invention preferably has a phosphorescence emission energy of 2.9 eV or more and a Tg of 90 ° C. or more. If the Tg is lower than 90 ° C., the deterioration of the element over time (decrease in luminance, deterioration of film properties) is large and the market needs as a light source cannot be satisfied. That is, in order to satisfy both luminance and durability, it is preferable that phosphorescence emission energy is 2.9 eV or more and Tg is 90 ° C. or more. Tg is more preferably 100 ° C. or higher.

  In the present invention, in the case of having a plurality of light emitting layers, 50% by mass or more of the host compound of the light emitting layer is the same compound having a phosphorescence emission energy of 2.9 eV or more and a Tg of 90 ° C. or more. It is preferable. Surprisingly, even if the Tg is 90 ° C or higher and the material is individually excellent in durability, when a different compound is used for each light emitting layer, the same compound is used for all the light emitting layers in terms of the storage characteristics of the entire device. It was found that there was a case where it deteriorated compared with the case where it was.

  Although the cause of this is not clearly understood, when 50% by mass or more of the host compounds in all the light emitting layers are the same, that is, when the host compounds in all the light emitting layers are substantially the same, uniform film surface properties are obtained. Although it is easy to obtain, when a different compound is used for each light emitting layer, each compound is stable, but non-uniformity is likely to occur at the layer interface or the like.

(Phosphorescent metal complex)
In the light emitting layer of the organic EL device of the present invention, the metal complex of the phosphorescent light emitting layer is preferably used as a so-called light emitting dopant, and among them, the Ir complex is preferable.

  A phosphorescent metal complex 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 a compound of this.

  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. The phosphorescence quantum yield in solution can be measured using various solvents, but the phosphorescent metal complex used in the present invention can be obtained if the phosphorescence quantum yield is achieved in any solvent. Good.

  There are two types of light emission of the phosphorescent metal complex in principle. One is the recombination of the carrier on the host compound to which the carrier is transported to generate an excited state of the host compound. An energy transfer type in which light emission from a phosphorescent metal complex is obtained by transferring to a light emitting metal complex, and the other is a phosphorescent metal complex that becomes a carrier trap. The carrier trap type in which recombination of carriers occurs on the complex and light emission from the phosphorescent metal complex is obtained, but in either case, the excited state energy of the phosphorescent metal complex is the host The condition is that it is lower than the energy of the excited state of the compound.

  Examples of the phosphorescent metal complex according to the present invention are shown below, but the present invention is not limited thereto.

  These compounds are described, for example, in Inorg. Chem. 40, 1704 to 1711, and the like.

  In the present invention, the phosphorescent maximum wavelength of the phosphorescent organometallic complex is not particularly limited, and in principle, a central metal, a ligand, a ligand substituent, and the like are selected. The emission wavelength obtained in (1) can be changed.

  The light emission color of the organic EL device of the present invention and the compound according to the present invention is shown in FIG. 4.16 on page 108 of “New Color Science Handbook” (edited by the Japan Color Society, University of Tokyo Press, 1985). It is determined by the color when the result measured with the total CS-1000 (manufactured by Konica Minolta Sensing) is applied to the CIE chromaticity coordinates.

The white element referred to in the present invention means that the chromaticity in the CIE1931 color system at 1000 Cd / m ² is X = 0.33 ± 0.07 when the front luminance at 2 ° C. viewing angle is measured by the above method. It is in the region of Y = 0.33 ± 0.07.

  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.

  In the present invention, the light emitting layer includes layers having different emission spectra in which the emission maximum wavelengths are in the ranges of 430 nm to 480 nm, 510 nm to 550 nm, and 600 nm to 640 nm, respectively, or a layer in which these are laminated.

  There is no restriction | limiting in particular as a lamination order of a light emitting layer, You may have a nonluminous intermediate | middle layer between each light emitting layer. In the present invention, it is preferable that at least one blue light emitting layer is provided at a position closest to the anode among all the light emitting layers.

  When four or more light emitting layers are provided, for example, blue / green / red / blue, blue / green / red / blue / green, blue / green / red / blue / green / red from the order close to the anode. As described above, it is preferable to sequentially stack blue, green, and red in order to improve luminance stability.

  The total film thickness of the light emitting layer is not particularly limited, but is usually 2 nm to 5 μm, preferably 2 to 200 nm. In the present invention, it is preferably in the range of 10 to 20 nm. If it is too thin, it is difficult to obtain film uniformity. If it is thicker than this, a high voltage is required to obtain light emission, which is not preferable. A film thickness of 20 nm or less is preferable because it has the effect of improving the stability of the emission color with respect to the driving current as well as the voltage surface.

  The film thickness of each light emitting layer is preferably selected in the range of 2 nm to 100 nm, and more preferably in the range of 2 nm to 20 nm.

  Although there is no restriction | limiting in particular about the film thickness relationship of each light emitting layer of blue, green, and red, It is preferable that the blue light emitting layer (the sum total when there are two or more layers) is the thickest among three light emitting layers.

  Moreover, in the range which maintains the said maximum wavelength, you may mix a several luminescent compound in each light emitting layer. For example, the blue light emitting layer may be used by mixing a blue light emitting compound having a maximum wavelength of 430 nm to 480 nm and a green light emitting compound having a maximum wavelength of 510 nm to 550 nm.

《Hole transport layer》
The hole transport layer is made of a hole transport 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 can be provided as a single layer or a plurality of layers.

  The hole transport material has any 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.

  The above-mentioned materials can be used as the hole transport material, 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 also two of those described in US Pat. No. 5,061,569. Having a condensed aromatic ring in the molecule, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-3086 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 8 are linked in a starburst type ( MTDATA) and the like.

  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.

  JP-A-11-251067, J. Org. Huang et. al. A so-called p-type hole transport material as described in a book (Applied Physics Letters 80 (2002), p. 139) can also be used. In the present invention, these materials are preferably used because a light-emitting element with higher efficiency can be obtained.

  The 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, a printing method including an ink jet method, or an LB method. it can.

  Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5 nm-200 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.

  Alternatively, a hole transport layer having a high p property doped with impurities can be used. Examples thereof include JP-A-4-297076, JP-A-2000-196140, 2001-102175, J. Pat. Appl. Phys. 95, 5773 (2004), and the like.

  In the present invention, it is preferable to use a hole transport layer having such a high p property because a device with lower power consumption can be produced.

《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 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, an electron transport material (also serving as a hole blocking material) used for an electron transport layer adjacent to the light emitting layer on the cathode side is injected from the cathode. As long as it has a function of transferring electrons to the light-emitting layer, any material can be selected and used from among conventionally known compounds. For example, nitro-substituted fluorene derivatives, diphenylquinone derivatives Thiopyrandioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives and the like. 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. 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), and the like, and the central metals of these metal complexes are In, Mg, Metal complexes replaced with Cu, Ca, Sn, Ga or Pb can also be used as the electron transport material.

  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 an inorganic semiconductor such as n-type-Si, n-type-SiC, etc. as in the case of the hole injection layer and hole transport layer Can also be used as an electron transporting material.

  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, a printing method including 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, 5 nm-about 5 micrometers, Preferably it is 5 nm-200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

  Further, an electron transport layer having a high n property doped with impurities can also be used. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

  In the present invention, it is preferable to use an electron transport layer having such a high n property because an element with lower power consumption can be manufactured.

《Support substrate》
As a support substrate (hereinafter also referred to as a substrate, substrate, substrate, support, etc.) that can be used in the organic EL device of the present invention, there is no particular limitation on the type of glass, plastic, etc., and it is transparent. May be opaque. When extracting light from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable support substrate is a resin film capable of giving flexibility to the organic EL element.

  Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate (CAP), Cellulose esters such as cellulose acetate phthalate (TAC) and cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones Cycloolefin resins such as polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylate, Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Can be mentioned.

On the surface of the resin film, an inorganic film, an organic film, or a hybrid film of both may be formed. Water vapor permeability (25 ± 0.5 ° C.) measured by a method according to JIS K 7129-1992. , Relative humidity (90 ± 2)% RH) is preferably 0.01 g / (m ² · 24 h) or less, and further, oxygen measured by a method according to JIS K 7126-1987. A high barrier film having a permeability of 10 ⁻³ ml / (m ² · 24 h · MPa) or less and a water vapor permeability of 10 ⁻⁵ g / (m ² · 24 h) or less is preferable.

  As a material for forming the barrier film, any material may be used as long as it has a function of suppressing entry of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like can be used. Further, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and organic material layers. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times.

  The method for forming the barrier film is not particularly limited. For example, the vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma weight A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, and the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.

  Examples of the opaque support substrate include metal plates such as aluminum and stainless steel, films, opaque resin substrates, and ceramic substrates.

  The external extraction efficiency at room temperature of light emission of the organic EL device of the present invention is preferably 1% or more, more preferably 5% 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.

  In addition, a hue improvement filter such as a color filter may be used in combination, or a color conversion filter that converts the emission color from the organic EL element into multiple colors using a phosphor. In the case of using a color conversion filter, the λmax of light emission of the organic EL element is preferably 480 nm or less.

<Sealing>
As a sealing means used for this invention, the method of adhere | attaching a sealing member, an electrode, and a support substrate with an adhesive agent can be mentioned, for example.

  As a sealing member, it should just be arrange | positioned so that the display area | region of an organic EL element may be covered, and concave plate shape or flat plate shape may be sufficient. Further, transparency and electrical insulation are not particularly limited.

  Specific examples include a glass plate, a polymer plate / film, and a metal plate / film. 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. Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum.

In the present invention, a polymer film and a metal film can be preferably used because the element can be thinned. Furthermore, the polymer film has a oxygen permeability measured by a method according to JIS K 7126-1987 of 1 × 10 ⁻³ ml / (m ² · 24 h · MPa) or less, and a method according to JIS K 7129-1992. It is preferable that the water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) measured in (1) is 1 × 10 ⁻³ g / (m ² · 24 h) or less.

  For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.

  Specific examples of the adhesive include photocuring and thermosetting adhesives having reactive vinyl groups such as acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. be able to.

  Moreover, heat | fever and chemical curing types (two-component mixing), such as an epoxy type, can be mentioned. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.

  In addition, since an organic EL element may deteriorate by heat processing, what can be adhesive-hardened from room temperature to 80 degreeC is preferable.

  A desiccant may be dispersed in the adhesive.

  Application | coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print like screen printing.

  In addition, it is also preferable that the electrode and the organic layer are coated on the outside of the electrode facing the support substrate with the organic layer interposed therebetween, and an inorganic or organic layer is formed in contact with the support substrate to form a sealing film. . In this case, the material for forming the film may be any material that has a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can.

  Further, in order to improve the brittleness of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of organic materials. The method for forming these films is not particularly limited. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster-ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma A polymerization method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.

  In the gap between the sealing member and the display area of the organic EL element, an inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil can be injected in the gas phase and liquid phase. preferable. A vacuum is also possible. Moreover, a hygroscopic compound can also be enclosed inside.

  Examples of the hygroscopic compound include metal oxides (for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide) and sulfates (for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate). Etc.), metal halides (eg calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide etc.), perchloric acids (eg perchloric acid) Barium, magnesium perchlorate, and the like), and anhydrous salts are preferably used in sulfates, metal halides, and perchloric acids.

《Protective film, protective plate》
In order to increase the mechanical strength of the element, a protective film or a protective plate may be provided on the outer side of the sealing film on the side facing the support substrate with the organic layer interposed therebetween or on the sealing film. In particular, when the sealing is performed by the sealing film, the mechanical strength is not necessarily high, and thus it is preferable to provide such a protective film and a protective plate.

  As a material that can be used for this, the same glass plate, polymer plate / film, metal plate / film, and the like used for the sealing can be used, but the polymer film is light and thin. Is preferably used.

《Light extraction》
The organic EL element emits light inside a layer having a refractive index higher than that of air (refractive index is about 1.7 to 2.1) and can extract only about 15% to 20% of the light generated in the light emitting layer. It is generally said.

  This is because light incident on the interface (interface between the transparent substrate and air) at an angle θ greater than the critical angle causes total reflection and cannot be taken out of the device, or between the transparent electrode or light emitting layer and the transparent substrate. This is because the light is totally reflected between the light and the light is guided through the transparent electrode or the light emitting layer, and as a result, the light escapes in the direction of the element side surface.

  As a method of improving the light extraction efficiency, for example, a method of forming irregularities on the surface of the transparent substrate and preventing total reflection at the transparent substrate and the air interface (US Pat. No. 4,774,435), A method of improving efficiency by providing a light collecting property to a substrate (Japanese Patent Laid-Open No. 63-314795), a method of forming a reflective surface on a side surface of an element (Japanese Patent Laid-Open No. 1-220394), and light emission from a substrate A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the bodies (Japanese Patent Laid-Open No. 62-172691), a flat having a lower refractive index between the substrate and the light emitter than the substrate A method of introducing a layer (Japanese Patent Laid-Open No. 2001-202827), a method of forming a diffraction grating between any one of a substrate, a transparent electrode layer and a light emitting layer (including between the substrate and the outside) (Japanese Patent Laid-Open No. 11-283951) Gazette).

  In the present invention, these methods can be used in combination with the organic EL device of the present invention. However, a method of introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter, or a substrate, transparent A method of forming a diffraction grating between any layers of the electrode layer and the light emitting layer (including between the substrate and the outside) can be suitably used.

  In the present invention, by combining these means, it is possible to obtain an element having higher luminance or durability.

  When a medium having a low refractive index is formed between the transparent electrode and the transparent substrate with a thickness longer than the wavelength of light, the light extracted from the transparent electrode has a higher extraction efficiency to the outside as the refractive index of the medium is lower.

  Examples of the low refractive index layer include aerogel, porous silica, magnesium fluoride, and a fluorine-based polymer.

  Since the refractive index of the transparent substrate is generally about 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less. Further, it is preferably 1.35 or less.

  The thickness of the low refractive index medium is preferably at least twice the wavelength in the medium. This is because the effect of the low refractive index layer is diminished when the thickness of the low refractive index medium is about the wavelength of light and the electromagnetic wave that has exuded by evanescent enters the substrate.

  The method of introducing a diffraction grating into an interface or any medium that causes total reflection is characterized by a high effect of improving light extraction efficiency.

  This method uses light generated from the light emitting layer by utilizing the property that the diffraction grating can change the direction of light to a specific direction different from refraction by so-called Bragg diffraction such as first-order diffraction and second-order diffraction. The light that cannot go out due to total reflection between layers, etc. is diffracted by introducing a diffraction grating in any layer or medium (in the transparent substrate or transparent electrode). It is intended to be taken out.

  The introduced diffraction grating desirably has a two-dimensional periodic refractive index. This is because light emitted from the light-emitting layer is randomly generated in all directions, so in a general one-dimensional diffraction grating having a periodic refractive index distribution only in a certain direction, only light traveling in a specific direction is diffracted. The light extraction efficiency does not increase so much. However, by making the refractive index distribution a two-dimensional distribution, light traveling in all directions is diffracted, and light extraction efficiency is increased.

  As described above, the position where the diffraction grating is introduced may be in any of the layers or in the medium (in the transparent substrate or in the transparent electrode), but is preferably in the vicinity of the organic light emitting layer where light is generated.

  At this time, the period of the diffraction grating is preferably about 1/2 to 3 times the wavelength of light in the medium.

  The arrangement of the diffraction grating is preferably two-dimensionally repeated, such as a square lattice, a triangular lattice, or a honeycomb lattice.

<Condenser sheet>
The organic EL device of the present invention is processed on the light extraction side of the substrate so as to provide, for example, a microlens array structure, or combined with a so-called condensing sheet, for example, with respect to a specific direction, for example, the light emitting surface By condensing in the front direction, the luminance in a specific direction can be increased.

  As an example of the microlens array, quadrangular pyramids having a side of 30 μm and an apex angle of 90 degrees are two-dimensionally arranged on the light extraction side of the substrate. One side is preferably 10 μm to 100 μm.

  As the condensing sheet, for example, a sheet that is put into practical use in an LED backlight of a liquid crystal display device can be used. As such a sheet, for example, a brightness enhancement film (BEF) manufactured by Sumitomo 3M Limited can be used. As the shape of the prism sheet, for example, the base material may be formed by forming a △ -shaped stripe having a vertex angle of 90 degrees and a pitch of 50 μm, or the vertex angle is rounded and the pitch is changed randomly. Other shapes may be used.

  Moreover, in order to control the light emission angle from a light emitting element, you may use together a light diffusing plate and a film with a condensing sheet. For example, a diffusion film (light-up) manufactured by Kimoto Co., Ltd. can be used.

<< 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 / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode will be described.

  First, a desired electrode material, for example, a thin film made of 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 to 200 nm, thereby producing an anode.

  Next, organic compound thin films such as a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, and an electron transport layer, which are organic EL element materials, are formed thereon.

  As a method for forming each of these layers, there are a vapor deposition method, a wet process (spin coating method, casting method, ink jet method, printing method) and the like as described above, but it is easy to obtain a homogeneous film and it is difficult to generate pinholes. In view of the above, in the present invention, film formation by a coating method such as a spin coating method, an ink jet method or a printing method is preferable, and an ink jet method is particularly preferable.

  In the present invention, in the formation of the light emitting layer, it is preferable to form a film by a coating method using a solution in which the organometallic complex according to the present invention is dissolved or dispersed, and the coating method is particularly preferably an ink jet method.

  Examples of the liquid medium for dissolving or dispersing the organometallic complex according to the present invention include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, DMF, DMSO, and the like. Organic solvents can be used. Moreover, as a dispersion method, it can disperse | distribute by dispersion methods, such as an ultrasonic wave, high shear force dispersion | distribution, and media dispersion | distribution.

  After these layers are formed, 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 film 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.

  Further, it is also possible to reverse the production order and produce the cathode, the electron transport layer, the hole blocking layer, the light emitting layer, the hole transport layer, the hole injection layer, and the anode in this order.

  When a DC voltage is applied to the multicolor display device thus obtained, light emission can be observed by applying a voltage of about 2 V to 40 V with the anode being + and the cathode being-. An alternating voltage may be applied. The alternating current waveform to be applied may be arbitrary.

<Application>
The organic EL element of the present invention can be used as a display device, a display, and various light emission sources. Examples of light sources include home lighting, interior lighting, clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, and light sources for optical sensors. However, the present invention is not limited to this, but it can be effectively used particularly as a backlight of a liquid crystal display device and an illumination light source.

  In the organic EL element of the present invention, patterning may be performed by a metal mask, an ink jet printing method, or the like as needed during film formation. When patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire element layer may be patterned.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these. The structures of the compounds used in the examples are shown below.

Example 1
<< Production of Organic EL Element 1-1 >>
Transparent support provided with this ITO transparent electrode after patterning on a substrate (NH45 manufactured by NH Techno Glass) made of ITO (indium tin oxide) with a thickness of 100 nm on a glass substrate of 100 mm × 100 mm × 1.1 mm as an anode The substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.

This transparent support substrate is fixed to a substrate holder of a commercially available vacuum deposition apparatus, while 200 mg of α-NPD is put into a molybdenum resistance heating boat, and 200 mg of CBP as a host compound is put into another molybdenum resistance heating boat. bathocuproin the manufacturing resistive heating boat (BCP) was placed 200mg, an Ir-12 was placed 100mg in a third resistive heating molybdenum boat, further Alq ₃ was placed 200mg in a third resistive heating molybdenum boat, was attached to a vacuum deposition apparatus.

Next, after reducing the vacuum chamber to 4 × 10 ⁻⁴ Pa, the heating boat containing α-NPD was heated by heating, and deposited on the transparent support substrate at a deposition rate of 0.1 nm / sec. The hole transport layer was provided.

  Further, the heating boat containing CBP and Ir-12 was energized and heated, and co-deposited on the hole transport layer at a deposition rate of 0.2 nm / second and 0.012 nm / second, respectively. A light emitting layer was provided. In addition, the substrate temperature at the time of vapor deposition was room temperature.

  Further, the heating boat containing BCP was energized and heated, and deposited on the light emitting layer at a deposition rate of 0.1 nm / second to provide a 10 nm thick hole blocking layer.

Further, the heating boat containing Alq ₃ is further heated by energization, and is deposited on the hole blocking layer at a deposition rate of 0.1 nm / second to further provide an electron transport layer having a thickness of 40 nm. It was. In addition, the substrate temperature at the time of vapor deposition was room temperature.

  Then, 0.5 nm of lithium fluoride and 110 nm of aluminum were vapor-deposited, the cathode was formed, and the organic EL element 1-1 was produced.

<< Production of Organic EL Elements 1-2 to 1-19 >>
In the production of the organic EL device 1-1, the organic EL devices 1-2 to 1-19 were prepared in the same manner except that the CBP used as the host compound of the light emitting layer was replaced with the compound shown in Table 1 to obtain a host compound. Each was produced.

<< Evaluation of Organic EL Elements 1-1 to 1-19 >>
The organic EL elements 1-1 to 1-19 produced as follows were evaluated, and the results are shown in Table 1.

(External 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 Konica Minolta Sensing) was used in the same manner.

  The measurement results of the external extraction quantum efficiency in Table 1 are expressed as relative values when the measurement value of the organic EL element 1-1 is 100.

(lifespan)
When driven at a constant current of ^2.5 mA / cm ² , the time required for the luminance to drop to half of the luminance immediately after the start of light emission (initial luminance) was measured, and this was calculated as the half-life time (τ 0.5). As an index of life. A spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing) was used for the measurement.

  The lifetime measurement results in Table 1 are expressed as relative values when the organic EL element 1-1 is taken as 100.

  From Table 1, it can be seen that the organic EL device of the present invention is excellent in external extraction quantum efficiency and has a long lifetime. Moreover, it turns out that the organic EL element material which concerns on this invention is compatible with higher efficiency and lifetime in a more preferable aspect (for example, a preferable substituent, the number of this substituent, etc.).

Example 2
<< Production of organic EL full-color display device >>
FIG. 1 shows a schematic configuration diagram of an organic EL full-color display device. After patterning at a pitch of 100 μm on a substrate (NH45 manufactured by NH Techno Glass Co., Ltd.) formed by forming a 100 nm ITO transparent electrode (102) on a glass substrate 101 as an anode, non-between the ITO transparent electrodes on this glass substrate. A photosensitive polyimide partition 103 (width 20 μm, thickness 2.0 μm) was formed by photolithography.

  A hole injection layer composition having the following composition is ejected and injected between polyimide partition walls on the ITO electrode using an inkjet head (manufactured by Epson Corporation; MJ800C), and a hole having a film thickness of 40 nm is obtained by drying at 200 ° C. for 10 minutes. An injection layer 104 was produced.

  The following blue light-emitting layer composition, green light-emitting layer composition, and red light-emitting layer composition are similarly ejected and injected onto the hole injection layer using an inkjet head, and the respective light-emitting layers (105B, 105G, 105R) are injected. ) Was formed. Finally, Al (106) was vacuum-deposited as a cathode so as to cover the light emitting layer 105, and an organic EL element was produced.

  It was found that the produced organic EL element showed blue, green, and red light emission by applying a voltage to each electrode, and could be used as a full-color display device.

(Hole injection layer composition)
PEDOT / PSS mixed water dispersion (1.0% by mass) 20 parts by mass Water 65 parts by mass Ethoxyethanol 10 parts by mass Glycerin 5 parts by mass PEDOT / PSS: Poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (Bayer) Made)
(Blue light emitting layer composition)
Illustrative compound (1) 0.7 parts by mass Ir-12 0.04 parts by mass Cyclohexylbenzene 50 parts by mass Isopropyl biphenyl 50 parts by mass (green light emitting layer composition)
Illustrative compound (1) 0.7 parts by mass Ir-1 0.04 parts by mass Cyclohexylbenzene 50 parts by mass Isopropyl biphenyl 50 parts by mass (red light emitting layer composition)
Exemplified Compound (1) 0.7 parts by mass Ir-9 0.04 parts by mass Cyclohexylbenzene 50 parts by mass Isopropylbiphenyl 50 parts by mass In addition to Exemplified Compound (1), Exemplified Compounds (3), (6), ( It was also found that organic EL devices fabricated using 17), (25), (331), and (36) can be similarly used as full-color display devices.

Example 3
<< Production of Organic EL Element 3-1 >>
Transparent support provided with this ITO transparent electrode after patterning on a substrate (NH45 manufactured by NH Techno Glass) made of ITO (indium tin oxide) with a thickness of 100 nm on a glass substrate of 100 mm × 100 mm × 1.1 mm as an anode The substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.

  This substrate was attached to a commercially available spin coater, spin-coated under a condition of 1000 rpm for 30 seconds (film thickness of about 40 nm) using a solution obtained by dissolving 60 mg of PVK in 10 ml of 1,2-dichloroethane, and vacuum-dried at 60 ° C. for 1 hour. And a hole transport layer.

  Next, spin coating was performed under the conditions of 1000 rpm and 30 seconds using a solution of Exemplified Compound (1) 60 mg, Ir-9, 3.0 mg, Ir-12, 3.0 mg in 6 ml of toluene (film thickness of about 40 nm) and vacuum dried at 60 ° C. for 1 hour to obtain a light emitting layer.

  Furthermore, using a solution of 20 mg of bathocuproine (BCP) in 6 ml of cyclohexane, spin-coated under a condition of 1000 rpm for 30 seconds (film thickness of about 10 nm) and vacuum-dried at 60 ° C. for 1 hour, which also serves as a hole blocking function An electron transport layer was provided.

Subsequently, this substrate was fixed to a substrate holder of a vacuum vapor deposition apparatus, 200 mg of Alq ₃ was placed in a molybdenum resistance heating boat, and attached to the vacuum vapor deposition apparatus. After reducing the pressure of the vacuum chamber to 4 × 10 ⁻⁴ Pa, the heating boat containing Alq ₃ was energized and heated, and deposited on the electron transport layer at a deposition rate of 0.1 nm / second to further form a film. An electron injection layer having a thickness of 40 nm was provided. In addition, the substrate temperature at the time of vapor deposition was room temperature.

  Then, 0.5 nm of lithium fluoride and 110 nm of aluminum were vapor-deposited, the cathode was formed, and the organic EL element 3-1 was produced.

  When this element was energized, almost white light was obtained, and it was found that it could be used as a lighting device. Even if the compound (1) is replaced with another compound (3), (17), (25), (28), (33), (36), (37) according to the present invention, the white It was found that luminescence was obtained.

Claims (10)

An organic electroluminescent device material comprising a compound represented by the following general formula (1).

[Wherein, R represents an alkyl group, a cycloalkyl group having 5 or more carbon atoms, or an aromatic hydrocarbon group, and R ₁ , R ₂ , R ₃ , and R ₄ represent a halogen atom, an alkyl group, and a carbon number, respectively. Represents a cycloalkyl group, an aromatic hydrocarbon group or an aromatic heterocyclic group having 5 or more. n1, n2, n3, and n4 each represents an integer of 0 to 2. X represents a divalent linking group selected from the group consisting of the following general formulas (2), (3), (4) and an alkylene group. n represents an integer of 1 or more. ]

[Wherein R ₅ , R ₆ , R ₇ and R ₈ each represent a halogen atom, an alkyl group, a cycloalkyl group having 5 or more carbon atoms, or an aromatic hydrocarbon group. n5, n6, n7, and n8 each represents an integer of 0 to 3. Y represents an oxygen atom or a sulfur atom. ] The organic electroluminescence device material according to claim 1, wherein X in the general formula (1) is a divalent linking group represented by the general formula (2) or (3). . X in the general formula (1) is a divalent linking group represented by the general formula (3), and Y in the general formula (3) represents an oxygen atom. The organic electroluminescent element material according to the first or second range. The organic electroluminescence element material according to any one of claims 1 to 3, wherein R in the general formula (1) represents an aromatic hydrocarbon group. The substituent represented by R _{1 to} R ₈ represents an alkyl group or an aromatic hydrocarbon group, and n1 to n8 are 0 or 1, any one of claims 1 to 4. 2. The organic electroluminescent element material according to item 1. In an organic electroluminescence device containing at least a light emitting layer sandwiched between an anode and a cathode,
6. The organic electroluminescent element, wherein the light emitting layer contains the organic electroluminescent element material according to any one of claims 1 to 5. The organic light-emitting device according to claim 6, wherein the light-emitting layer contains a phosphorescent metal complex. The organic electroluminescence device according to claim 7, wherein the phosphorescent metal complex is an Ir complex. A display device comprising the organic electroluminescent element according to any one of claims 6 to 8. An illuminating device comprising the organic electroluminescent element according to any one of claims 6 to 8.