JP2009114370A - Organic electroluminescence element material, organic electroluminescence element, display device, and lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescence element with high external extraction quantum efficiency, low driver voltage, and a long luminous lifetime, and to provide an organic electroluminescence element, a lighting system, and a display device. <P>SOLUTION: The organic electroluminescence element material has a structure represented by a general formula (1) wherein Y<SB>1</SB>and Y<SB>2</SB>represent O, S or N-R<SB>0</SB>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  An organic electroluminescence element (hereinafter also simply referred to as an organic EL element) is an all-solid-state element composed of an organic material film having a thickness of only about 0.1 μm between electrodes, and emits light of 2 to 2. Since it can be achieved at a relatively low voltage of about 20 V, it is a technology expected as a next-generation flat display and illumination.

  Furthermore, the recently discovered organic electroluminescence device using phosphorescence emission can in principle achieve a luminous efficiency about 4 times that of the previous method using fluorescence emission. Research and development of light-emitting element layer configurations and electrodes are performed all over the world.

  In addition, the structure of the organic EL element is a simple structure in which an organic layer is sandwiched between a transparent electrode and a counter electrode, and the number of parts is overwhelmingly smaller than that of a liquid crystal display, which is a typical flat display. However, this is not always the case at present, and a large amount of water has been poured into the liquid crystal display in terms of performance and cost. In particular, in terms of cost, poor productivity is considered as a factor.

Most of the organic EL currently commercialized are manufactured by a so-called vapor deposition method in which a low molecular material is vapor deposited. In this vapor deposition method, an organic EL material can be used as a low-molecular compound that can be easily purified (a high-purity material can be easily obtained), and a laminated structure can be easily formed. Although it is excellent, on the other hand, since deposition is performed under a high vacuum condition of 10 ⁻⁴ Pa or less, restrictions are imposed on the film forming apparatus, and in practice it can only be applied to a substrate with a small area, and when multiple layers are laminated In this case, the film formation takes time and the throughput is low.

  In particular, it becomes a problem when applied to lighting applications or large-area electronic displays, and organic EL is one of the causes that are not practically used in such applications.

  On the other hand, a coating method for producing an organic compound layer by a process such as spin coating, inkjet, printing, spraying can produce a thin film at normal pressure, and is suitable for producing a uniform film over a large area.

  In the coating method, a necessary material (polymer material and / or low molecular weight material) is prepared as a solution or dispersion and applied as a thin film, so that a plurality of organic materials can be mixed precisely (for example, a dopant for a light emitting host material, etc. For example, it is easy to make adjustments, so that even if the element is enlarged, there is a feature that unevenness in light emission is difficult to occur, which is very advantageous in terms of manufacturing cost.

  Materials used for the coating method are largely high molecular and low molecular, but in general, high molecular materials are difficult to purify, and organic EL devices, in particular, have very small impurities that greatly reduce the light emission lifetime of the device. It is difficult to apply.

  Conventionally known low molecular weight host materials that can be used for the light emitting layer have been disclosed (for example, see Patent Document 1). Using these materials, a light emitting layer is formed by a coating method to improve device performance. As a result of evaluation and examination, there is a problem that the operating voltage is increased and the luminous efficiency is likely to be lowered as compared with an element produced by vapor deposition, and improvement is required.

  There is a report that an organic EL device containing a low molecular compound having a structure in which a carbazolyl skeleton is bonded by a single bond is preferable as a host compound of the light emitting layer in terms of improving efficiency and extending the life (for example, , Refer to Patent Document 2), the evaluation relating to the device fabrication is only by vacuum deposition, the details of the device fabrication by the coating method are not described, and there is no report on performance.

In the coating method, the solution or dispersion is prepared and applied as described above. However, when laminating, insolubility of the lower layer and insolubility when laminating the upper layer are also serious problems. Even in Patent Document 2, the evaluation of the laminate property is not described.
JP 2005-183303 A Japanese Patent No. 3139321

  An object of the present invention is to provide an organic electroluminescent element material having a high external extraction quantum efficiency, a low driving voltage, and a long emission lifetime, an organic electroluminescent element using the same, an illuminating device, and a display device. .

  The above object of the present invention can be achieved by the following constitution.

  1. An organic electroluminescence element material having a structure represented by the following general formula (1).

(Wherein Y ₁ and Y ₂ represent O, S or N—R ₀ , and R ₀ , R _{11 to} R ₁₈ and R _{21 to} R ₂₈ represent a hydrogen atom or a substituent. R _{11 to} R ₁₈ and At least one of R ₀ is used for linking with any of R _{31 to} R ₃₆ , and at least one of R _{21 to} R ₂₈ and R ₀ is used for bonding with R _{31 to} R ₃₆ , provided that R ₀ is In the case of binding to any of R _{31 to} R ₃₆ , R 0 represents a substituent, R _{31 to} R ₃₆ represent a hydrogen atom or a substituent, at least two of R _{31 to} R ₃₆ are used for connection, When R ₃₁ and R ₃₄ are used for connection, at least one of R ₃₂ , R ₃₃ , R ₃₅ and R ₃₆ has a substituent other than a hydrogen atom, n is an integer of 3 or more, and [] _n The combination of R _{11 to} R ₁₈ and R _{31 to} R ₃₆ in R may be different in each unit.)
2. 2. The organic electroluminescence element material according to 1, wherein the molecular weight is 900 to 3000.

3. 3. The organic electroluminescent element material as described in 1 or 2 above, wherein Y ₁ and Y ₂ in the general formula (1) are N—R ₀ .

4). 4. The organic electroluminescent element material as described in 3 above, wherein R ₀ is Ph.

5). 5. The organic electroluminescence element material according to any one of 1 to 4, wherein R ₃₁ and R ₃₃ in the general formula (1) are used for connection.

  6). 6. An organic electroluminescence device comprising at least one light emitting layer sandwiched between an anode and a cathode, wherein at least one of the light emitting layers contains the organic electroluminescence device material according to any one of 1 to 5 above. An organic electroluminescence device characterized by that.

  7. 7. The organic electroluminescence device according to 6 above, wherein the light emitting layer and at least one layer adjacent to the light emitting layer are formed by a wet method.

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

  9. 9. The organic electroluminescence device as described in 8 above, wherein the phosphorescent dopant is an Ir complex.

  10. 10. The organic electroluminescence device according to any one of 6 to 9, which emits white light.

  11. A display device comprising the organic electroluminescence element according to any one of 6 to 10 above.

  12 A lighting device comprising the organic electroluminescence element according to any one of 6 to 10 above.

  According to the present invention, it is possible to provide an organic electroluminescence element material having a high external extraction quantum efficiency, a low driving voltage, and a long emission lifetime, an organic electroluminescence element using the same, an illumination device, and a display device.

  Hereinafter, the present invention will be described in detail.

  In the organic electroluminescent element of this invention, it has the structure as described in any one of claims 6 to 10, so that the external extraction quantum efficiency is high, the driving voltage is low, and the emission lifetime is long. An element was obtained. Moreover, it succeeded also in obtaining the high-intensity display apparatus and illuminating device which comprised this organic electroluminescent element.

  Hereinafter, details of each component according to the present invention will be sequentially described.

  In general, when an organic EL device is manufactured by a wet method, a host compound and a dopant compound are used as materials used for the light emitting layer. Preferred examples of the layer structure are listed below.

(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 As described above, it is essential to stack an electron transport layer or a hole blocking layer on the top of the light-emitting layer. As the solvent resistance of the light emitting layer. The solvent resistance means that the lower layer does not dissolve when laminating, and here means that it does not dissolve in the solvent used when laminating the electron transport layer or the hole transport layer.

In the general formula (1), Y ₁ and Y ₂ are O, S or N—R ₀ , but Y ₁ and Y ₂ are preferably N—R ₀ .

In the general formula (1), examples of the substituent represented by R ₀ include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group). 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.) Etc.), aromatic hydrocarbon groups (also called aromatic carbocyclic groups, aryl groups, etc.), for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, xylyl group, naphthyl group, anthryl group, azulenyl group, acenaphthenyl group Group, fluorenyl group, phenanthryl group, indenyl group, pyrenyl group, biphenylyl group), 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.), alkoxy group (for example, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cyclo An alkoxy 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, ethyloxy) Carbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group, methylamino) Sulfonyl, dimethylaminosulfonyl, butylaminosulfonyl, hexylaminosulfonyl, cyclohexylaminosulfonyl, octylaminosulfonyl, dodecyla Nosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl 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, dodecylcarbonyl group) Oxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propyl) Rubonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl Group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthyl Aminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, Nylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl 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, butylsulfonyl group, cyclohexylsulfonyl group, 2 -Ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group (phenylsulfonyl group, naphthylsulfonyl group, 2-pyridyl) Sulfonyl 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-pyridylamino 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.), cyano group , Nitro group, hydroxy group, mercapto group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, etc.), phosphono group and the like.

  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.

Of these substituents, R ₀ is preferably an aromatic carbocyclic group, that is, an aryl group, and more preferably a phenyl group. R ₁₁ to R ₁₈ and _{R 21 ~R 28, R 31 ~R} 36 represents a hydrogen atom or a substituent. In any case, a hydrogen atom is preferable. In the case of a substituent, examples of the substituent shown in the section of R ₀ are given.

  In the general formula (1), n represents the number of repeating units and is an integer of 3 or more and 10 or less. Preferably they are 4 or more and 10 or less, More preferably, they are 4 or more and 8 or less. The molecule constituting the repeating unit is a linkage of a 3-ring condensed ring and a phenyl group as shown in the general formula (1), but the structure of the condensed ring portion and the phenyl portion is different in the structure of one molecule. The coupling position may be different in each unit.

  The molecular weight of the organic electroluminescent device material of the present invention is between 900 and 3000, preferably between 1000 and 2500. A compound having a molecular weight in such a range is generally called an oligomer. The reason why the oligomer is used for the organic electroluminescence device material of the present invention is that a mechanism of transporting charges through a bond between atom-atoms, that is, an atom-atom during charge transport, for example, molecular weight 900 It is advantageous in terms of charge transport as compared with low molecular weight compounds such as below, and is effective in lowering the voltage. Furthermore, since the oligomer is mainly constructed by a coupling reaction of a low-molecular compound, for example, since an impurity that can be contained at the time of polymer synthesis is not contained, the device can be highly efficient and have a long life.

  Hereinafter, although the specific example of a compound which has a structure represented by the said General formula (1) is given, this invention is not limited to this.

Synthesis of Exemplary Compound 1 90 ml of N, N-dimethylacetamide (dehydrated) was added to 13.4 g of carbazole, 25.0 g of 3-bromoiodobenzene, 13.4 g of potassium carbonate, and 6.2 g of copper (powder), under a nitrogen stream. The mixture was heated to reflux for 7 hours. The reaction mixture was cooled to room temperature, insolubles were filtered, 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 resulting mixture was purified by silica gel column chromatography to obtain 17 g of Intermediate 1. The yield was 57%. The structure of the obtained intermediate 1 was confirmed by a nuclear magnetic resonance spectrum and a mass spectrum.

Intermediate 1, 20 g, bis (pinacolato) diboron 18.9 g, potassium acetate 12.2 g, PdCl ₂ (dppf) · CH ₂ Cl ₂ ([1,1′-bis (diphenylphosphino) ferrocene] palladium (II) To 1.0 g of dichloride / dichloromethane complex), 300 ml of dimethyl sulfoxide was added, and the mixture was heated and stirred at 100 ° C. for 16 hours under a nitrogen stream. The reaction mixture was cooled to room temperature, insolubles were filtered, 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 resulting mixture was purified by silica gel column chromatography to obtain 20.6 g of intermediate 2. The yield was 90%. The structure of the obtained intermediate 2 was confirmed by nuclear magnetic resonance spectrum and mass spectrum.

Intermediate 2, 24.6 g, Intermediate 3, 13.7 g, Potassium carbonate 23.1 g, Pd (dba) ₂ (Bis (dibenzylideneacetone) palladium) 0.64 g, dppf (diphenylphosphinoferrocene) 0.62 g 1,2-dimethoxyethane (550 ml) and water (70 ml) were added thereto, and the mixture was heated to reflux for 5 hours. The reaction mixture was cooled to room temperature, insolubles were filtered, 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 mixture was purified by silica gel column chromatography to obtain 16.5 g of intermediate 4. The yield was 72%. The structure of the obtained intermediate 4 was confirmed by nuclear magnetic resonance spectrum and mass spectrum.

  To 0.29 g of palladium acetate, 2.1 g of a 50 mass% toluene solution of tert-butylphosphine and 10 ml of xylene (dehydrated) were added, and the mixture was stirred at room temperature for 1 hour in a nitrogen stream. Subsequently, Intermediate 4, 7.5 g, 1,3-diiodobenzene 2.9 g, sodium t-butoxide 2.1 g, and xylene (dehydrated) 120 ml were added, and the mixture was heated to reflux for 5 hours under a nitrogen stream. . After cooling the reaction solution to room temperature, insolubles were filtered, water was added, and the mixture was extracted with toluene. The organic layer was repeatedly washed with water and concentrated under reduced pressure. The resulting mixture was purified by silica gel column chromatography, and further recrystallized from toluene to obtain 5.7 g of Exemplified Compound 1. The yield was 73%. The obtained exemplary compound 1 was confirmed in structure by nuclear magnetic resonance spectrum and mass spectrum.

  Other compounds can be synthesized in the same manner.

<< Constitutional layer of organic EL element, organic compound layer >>
The constituent layers and organic compound layers of the organic EL device of the present invention will be described. 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 / 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 << organic compound layer (also referred to as organic layer) >>
The organic compound layer according to the present invention will be described.

  The organic EL device of the present invention preferably has a plurality of organic compound layers as a constituent layer. Examples of the organic compound layer include a hole transport layer, a light emitting layer, and a hole blocking layer in the above layer constitution. In addition, an organic compound layer according to the present invention is defined as long as it contains an organic compound contained in a constituent layer of an organic EL element, such as a hole injection layer or an electron injection layer. Is done.

  Furthermore, when an organic compound is used for the anode buffer layer, the cathode buffer layer, etc., the anode buffer layer, the cathode buffer layer, etc. each form an organic compound layer.

  The organic compound layer includes a layer containing “organic EL element material that can be used for a constituent layer of an organic EL element” or the like.

  In the organic EL device of the present invention, the blue light emitting layer preferably has an emission maximum wavelength of 430 to 480 nm, the green light emitting layer has an emission maximum wavelength of 510 to 550 nm, and the red light emitting layer has an emission maximum wavelength of 600 to 640 nm. A monochromatic light emitting layer in the range is preferable, and a display device using these is preferable.

  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.

<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 total film thickness of the light emitting layer is not particularly limited, but it is 2 nm to from the viewpoint of preventing the application of a high voltage unnecessary for the film homogeneity and light emission and improving the stability of the emission color with respect to the drive current. It is preferable to adjust to the range of 5 micrometers, More preferably, it adjusts to the range of 2-200 nm, Most preferably, it is the range of 10-20 nm.

  For the production of the light-emitting layer, a light-emitting dopant or a host compound, which will be described later, is formed 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. it can.

  The light emitting layer of the organic EL device of the present invention preferably contains a host compound and at least one kind of light emitting dopant (phosphorescent dopant, fluorescent dopant, etc.).

(Host compound)
The host compound used in the present invention will be described.

  Here, the host compound in the present invention is 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. Moreover, it is preferable that the mass ratio in the layer is 20% or more among the compounds contained in a light emitting layer.

  In the present invention, a compound having a structure represented by the general formula (1) is particularly preferably used as a host compound.

  In addition, as a host compound, a well-known host compound may be used together, and may be used in combination of multiple types. 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. Moreover, it becomes possible to mix different light emission by using multiple types of light emission dopants mentioned later, and, thereby, arbitrary luminescent colors can be obtained.

  A conventionally known host compound that may be used in combination is preferably a compound that has a hole transporting ability and an electron transporting ability, prevents the emission of light from becoming longer, and has a high Tg (glass transition temperature).

  Specific examples of conventionally 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. 2002-260861, No. 2002-280183, No. 2002-299060, No. 2002. -302516, 2002-305083, 2002-305084, 2002-308837, and the like.

(Luminescent dopant)
The light emitting dopant according to the present invention will be described.

  As the light emitting dopant according to the present invention, a fluorescent dopant or a phosphorescent light emitting dopant can be used. From the viewpoint of obtaining an organic EL element with higher luminous efficiency, the light emitting layer or light emitting unit of the organic EL element of the present invention. As the luminescent dopant used in the above, it is preferable to contain the above-mentioned host compound and at the same time a phosphorescent dopant.

(Phosphorescent dopant)
The phosphorescent dopant according to the present invention will be described.

  The phosphorescent dopant according to the present invention is a compound in which light emission from an excited triplet is observed. Specifically, it is a compound that emits phosphorescence at room temperature (25 ° C.) and has a phosphorescence quantum yield. The phosphorescence quantum yield is preferably 0.1 or more, although it is defined as a compound of 0.01 or more at 25 ° C.

  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 emitting dopant according to the present invention achieves the above phosphorescence quantum yield (0.01 or more) in any solvent. It only has to be done.

  There are two types of light emission of phosphorescent dopants 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. The energy transfer type is to obtain light emission from the phosphorescent dopant by transferring to the phosphorescent dopant, and the other is that the phosphorescent dopant becomes a carrier trap, and carrier recombination occurs on the phosphorescent dopant to cause phosphorescence. There is a carrier trap type in which light emission from a photoluminescent dopant can be obtained.

  In any of the above cases, it is a condition that the excited state energy of the phosphorescent dopant is lower than the excited state energy of the host compound.

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

  The phosphorescent dopant according to the present invention is preferably a complex compound containing a group 8-10 metal in the periodic table, more preferably an iridium compound (Ir complex), an osmium compound, or a platinum compound ( Platinum complex compounds) and rare earth complexes, most preferably iridium compounds (Ir complexes).

  Although the specific example of the compound used as a phosphorescent dopant below is shown, this invention is not limited to these. These compounds are described, for example, in Inorg. Chem. 40, 1704-1711, and the like.

  Although the specific example of the phosphorescence-emitting dopant which concerns on this invention is shown, this invention is not limited to this.

(Fluorescent dopant)
Fluorescent dopants include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, perylene dyes, stilbene dyes , Polythiophene dyes, or rare earth complex phosphors.

  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 driving 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 although it depends on the material, the film thickness is preferably in the range of 0.1 nm to 5 μm.

<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 an electron at the HOMO (highest occupied molecular orbital) level of the compound to the vacuum level, and can be obtained by the following method, for example.

  (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 *. This calculation value is effective because the correlation between the calculation value obtained by this method and the experimental value is high.

  (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 transporting layer according to the present invention is preferably 3 to 100 nm, and more preferably 5 to 30 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 5-200 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, and JP-A-2001-102175; 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 cathode side with respect to the light emitting layer is injected from the cathode. Any material may be used as long as it has a function of transferring electrons to the light-emitting layer, and any material can be selected from conventionally known compounds.

  Examples include nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide 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 transporting 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 5-200 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.

"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 substances 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 so high (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 to 1000 nm, preferably 10 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 5 μm, preferably 50 to 200 nm. In order to transmit the emitted light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the emission luminance is advantageously improved.

  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.

《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 Polyetherimide, polyether ketone imide, polyamide, fluorine resin, nylon, polymethyl methacrylate, acrylic or polyarylates, and cycloolefin resins such as ARTON (JSR Corp.) or APEL (manufactured by Mitsui Chemicals, Inc.).

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 more preferably oxygen permeability measured by a method according to JIS K 7126-1987. A high barrier property film having a degree 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 quantum 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 an 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. The water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) measured in (1) is preferably 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 adhesively cured from room temperature to 80 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 method, sputtering method, reactive sputtering method, molecular beam epitaxy method, 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, it is preferable to inject an inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil in the gas phase and the liquid phase. . A vacuum can also be used. 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, etc. used for the sealing can be used. It is preferable to use a film.

《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 only 15% to 20% of light generated in the light emitting layer can be extracted. It is generally said that there is no.

  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 extracted outside the device, or between the transparent electrode or light emitting layer and the transparent substrate. This is because the light undergoes total reflection between the light and the light, and the light is guided through the transparent electrode or the light emitting layer.

  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 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. Of these, light that cannot be emitted due to total reflection between layers, etc. is diffracted by introducing a diffraction grating into any layer or medium (inside a transparent substrate or transparent electrode), and the light is emitted outside. I want to take it 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. Therefore, 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.

《Condensing 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 device 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 to 100 μm. If it becomes smaller than this, the effect of diffraction will generate | occur | produce and color, and if too large, thickness will become thick and is not preferable.

  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 / electron injection layer / cathode Will be explained.

  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, an organic compound thin film of a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer and an electron injection layer is 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, film formation by a coating method such as a spin coating method, an ink jet method, or a printing method is preferable in the present invention.

  In particular, in the present invention, the layer containing the compound having the structure represented by the general formula (1) is preferably formed by the above coating method, and the layer is preferably a light emitting layer.

  Further, when the total number of layers (the constituent layers of the organic EL element) existing between the anode and the cathode is 100%, 50% or more of the total number of layers is preferably formed by a coating method. .

  For example, in the anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer / cathode mentioned as an example of the organic EL element, the hole injection layer In the case where the total number of layers / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer is 6, it is preferable that at least three layers are formed by a coating method.

  When the constituent layers of the organic EL device of the present invention are formed by coating, examples of the liquid medium for dissolving or dispersing various organic EL materials used for coating include ketones such as methyl ethyl ketone and cyclohexanone, and fatty acid esters such as ethyl acetate. , Halogenated hydrocarbons such as dichlorobenzene, aromatic hydrocarbons such as toluene, xylene, mesitylene and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin and dodecane, and organic solvents such as DMF and DMSO be able to.

  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 50 to 200 nm, and a cathode is provided. Thus, a desired organic EL element can be obtained.

  In addition, it is possible to reverse the production order, and produce the cathode, the electron injection layer, 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 to 40 V with the anode as + and the cathode as-polarity. 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. For example, lighting devices (home lighting, interior lighting), clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources of optical storage media, light sources of electrophotographic copying machines, light sources of optical communication processors, light Although the light source of a sensor etc. are mentioned, It is not limited to this, Especially, it can use effectively for the use as a backlight of a liquid crystal display device, and a light source for illumination.

  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. In the case of patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire layer of the element may be patterned. In the fabrication of the element, a conventionally known method is used. Can do.

  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.

When the organic EL element of the present invention is a white element, white means that the chromaticity in the CIE 1931 color system at 1000 cd / m ² is X = It is in the region of 0.33 ± 0.07, Y = 0.33 ± 0.1.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.

Example 1
<< Production of Organic EL Element 1-1 >>
After patterning on a substrate (NA-45 manufactured by NH Techno Glass Co., Ltd.) formed by depositing 100 nm of ITO (indium tin oxide) on a glass substrate of 100 mm × 100 mm × 1.1 mm as an anode, this ITO transparent electrode is provided. The transparent support substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.

  On this transparent support substrate, a solution obtained by diluting poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS, Bayer, Baytron P Al 4083) to 70% with pure water at 3000 rpm for 30 seconds. After the film formation by spin coating, the film was dried at 200 ° C. for 1 hour to provide a first hole transport layer having a thickness of 30 nm.

  This substrate was transferred to a nitrogen atmosphere, and a solution of 50 mg of Compound 1 dissolved in 10 ml of toluene was formed on the first hole transport layer by spin coating at 1000 rpm for 30 seconds. Ultraviolet light was irradiated for 180 seconds, photopolymerization and crosslinking were performed, and a second hole transport layer having a film thickness of about 25 nm was obtained.

  On this second hole transport layer, a solution prepared by dissolving 100 mg of comparative compound 1 (host compound) and 10 mg of FIr (pic) in 10 ml of toluene was formed by spin coating under conditions of 1000 rpm and 30 seconds. . It vacuum-dried at 60 degreeC for 1 hour, and was set as the light emitting layer with a film thickness of about 50 nm.

  Subsequently, this substrate was fixed to a substrate holder of a vacuum deposition apparatus, 200 mg of BAlq was put into a molybdenum resistance heating boat, and attached to the vacuum deposition apparatus.

The vacuum chamber was depressurized to 4 × 10 ⁻⁴ Pa, heated by energizing the heating boat containing BAlq, evaporated onto the light emitting layer at a deposition rate of 0.1 nm / second, and a film thickness of 30 nm. The electron transport layer was provided.

Next, the vacuum chamber was depressurized to 4 × 10 ⁻⁴ Pa, lithium fluoride 1.0 nm was deposited as a cathode buffer layer, and aluminum 110 nm was deposited as a cathode to form a cathode, and an organic EL device 1-1 was produced.

<< Production of Organic EL Elements 1-2 to 1-8 >>
Organic EL elements 1-2 to 1-8 were respectively prepared in the same manner as the organic EL element 1-1 except that the comparative compound 1 was replaced with the compounds shown in Table 1 in the preparation of the organic EL element 1-1.

<< Evaluation of Organic EL Elements 1-1 to 1-8 >>
When evaluating the obtained organic EL elements 1-1 to 1-8, the non-light-emitting surface of each organic EL element after production was covered with a glass case, and a glass substrate having a thickness of 300 μm was used as a sealing substrate. An epoxy-based photo-curing adhesive (Lux Track LC0629B manufactured by Toagosei Co., Ltd.) is applied as a sealing material in the periphery, and this is placed on the cathode to be in close contact with the transparent support substrate and irradiated with UV light from the glass substrate side. Then, it was cured and sealed, and an illumination device as shown in FIGS. 2 and 3 was formed and evaluated.

  FIG. 2 is a schematic view of the lighting device, and the organic EL element 201 is covered with a glass cover 202. Note that the sealing operation with the glass cover was performed in a glove box in a nitrogen atmosphere without bringing the organic EL element 201 into contact with the atmosphere (in a high purity nitrogen gas atmosphere having a purity of 99.999% or more).

  FIG. 3 is a cross-sectional view illustrating one embodiment of the lighting device of the present invention. In FIG. 3, reference numeral 205 denotes a cathode, 206 denotes an organic EL layer, and 207 denotes a glass substrate with a transparent electrode. The glass cover 202 is filled with nitrogen gas 208 and a water catching agent 209 is provided.

  Next, the external extraction quantum efficiency and emission lifetime were measured as follows.

(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 Co., Ltd.) was similarly used.

  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 driving 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.

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

(Drive voltage)
The voltage (V) when driven at a constant current of ^2.5 mA / cm ² was measured.

  From Table 1, it is clear that the organic EL device of the present invention exhibits a high external extraction quantum efficiency, a low driving voltage, and a long emission lifetime as compared with the comparative organic EL device.

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 (NA techno glass NA45) having a 100 nm ITO transparent electrode (102) formed on a glass substrate (101) as an anode, between the ITO transparent electrodes on this glass substrate A non-photosensitive polyimide partition wall (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), irradiated with ultraviolet light for 180 seconds, and dried at 60 ° C. for 10 minutes. A hole injection layer 104 having a thickness of 40 nm was produced by the treatment.

  On the hole injection layer, the following blue light emitting layer composition, green light emitting layer composition and red light emitting layer composition were similarly discharged and injected using an inkjet head, irradiated with ultraviolet light for 30 seconds, 60 Drying treatment was performed at a temperature of 10 ° C. for 10 minutes to form respective light emitting layers (105B, 105G, 105R). Finally, Al (106) was vacuum-deposited as a cathode so as to cover the light emitting layer (105), and an organic EL device was produced.

  It was found that the produced organic EL element exhibited 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)
Compound 1 20 parts by mass Cyclohexylbenzene 50 parts by mass Isopropylbiphenyl 50 parts by mass (Blue light emitting layer composition)
Exemplified Compound 11 0.7 parts by mass FIr (pic) 0.04 parts by mass Cyclohexylbenzene 50 parts by mass Isopropyl biphenyl 50 parts by mass (green light emitting layer composition)
Illustrative compound 11 0.7 parts by mass Ir-1 0.04 parts by mass Cyclohexylbenzene 50 parts by mass Isopropylbiphenyl 50 parts by mass (red light emitting layer composition)
Example Compound 11 0.7 parts by mass Ir-14 0.04 parts by mass Cyclohexylbenzene 50 parts by mass Isopropylbiphenyl 50 parts by mass Example 3
<< Production of White Organic EL Element 3-1 >>
In the organic EL device 1-3 of Example 1, the white light-emitting organic EL device 1-3W (in the same manner except that FIr (pic) used in the luminescent composition was changed to a mixture of Ir-9 and Ir-13. White).

  When evaluating the obtained organic EL element 1-3W, the non-light-emitting surface 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.

  In addition, it turned out that white light emission is obtained similarly even if it replaces with the other compound of illustration.

The schematic block diagram of an organic electroluminescent full color display apparatus is shown. It is the schematic of an illuminating device. It is sectional drawing of an illuminating device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Glass substrate 102 ITO transparent electrode 103 Partition 104 Hole injection layer 105B, 105G, 105R Light emitting layer 207 Glass substrate with a transparent electrode 206 Organic EL layer 205 Cathode 202 Glass cover 208 Nitrogen gas 209 Water capturing agent

Claims (12)

An organic electroluminescence element material having a structure represented by the following general formula (1).

(In the formula, Y ₁ and Y ₂ represent O, S or N—R ₀ , and R ₀ , R _{11 to} R ₁₈ and R _{21 to} R ₂₈ represent a hydrogen atom or a substituent. R _{11 to} R ₁₈ and At least one of R ₀ is used for linking with any of R _{31 to} R ₃₆ , and at least one of R _{21 to} R ₂₈ and R ₀ is used for bonding with R _{31 to} R ₃₆ , provided that R ₀ is In the case of binding to any of R _{31 to} R ₃₆ , R ₀ represents a substituent, R _{31 to} R ₃₆ each represents a hydrogen atom or a substituent, and at least two of R _{31 to} R ₃₆ are used for connection, When R ₃₁ and R ₃₄ are used for connection, at least one of R ₃₂ , R ₃₃ , R ₃₅ , and R ₃₆ has a substituent other than a hydrogen atom, n is an integer of 3 or more, and [] _n The combination of the bonds of R _{11 to} R ₁₈ and R _{31 to} R ₃₆ may be different in each unit.) 2. The organic electroluminescence device material according to claim 1, wherein the molecular weight is 900 to 3000. The organic electroluminescent element material according to claim ₁ , wherein Y ₁ and Y ₂ in the general formula (1) are N—R ₀ . The organic electroluminescent element material according to claim 3, wherein R ₀ is Ph. The organic electroluminescence element material according to claim 1, wherein R ₃₁ and R ₃₃ in the general formula (1) are used for connection. In the organic electroluminescent element containing the at least 1 layer of light emitting layer pinched | interposed by the anode and the cathode, at least 1 layer of this light emitting layer contains the organic electroluminescent element material of any one of Claims 1-5. An organic electroluminescence device characterized by comprising: The organic electroluminescence device according to claim 6, wherein the light emitting layer and at least one layer adjacent to the light emitting layer are formed by a wet method. The organic electroluminescent element according to claim 6 or 7, wherein the light emitting layer contains a phosphorescent dopant. The organic electroluminescence device according to claim 8, wherein the phosphorescent dopant is an Ir complex. The organic electroluminescence device according to claim 6, which emits white light. A display device comprising the organic electroluminescence element according to claim 6. An illuminating device comprising the organic electroluminescence element according to any one of claims 6 to 10.

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