JP2008207520A - Organic thin film, method for producing the same, electronic device, organic luminescence element, display device and lightening equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an organic thin film comprising a process step of forming a film using a reaction solution containing a polymer of a polymerizable monomer, to provide an organic EL element having a long luminescence life and high efficacy of taking out quantum using the method, and to provide an electronic device and an organic EL element containing the organic thin film, and further to provide a display device and a lightning equipment comprising the organic EL element. <P>SOLUTION: The method for an organic thin film comprises a process step of giving energy to a reactive monomer to give a reaction solution containing a polymer of the reactive monomer and then forming a film using the reaction solution. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an organic thin film, a method for producing an organic thin film, an electronic device, 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 also 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.

  On the other hand, an organic EL element has a configuration 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 to recombine excitons. This is an element that emits light by utilizing the emission of light (fluorescence / phosphorescence) when the exciton (exciton) is deactivated, and can emit light at a voltage of several volts to several tens of volts. Since it is a self-luminous type, it has a wide viewing angle, high visibility, and since it is a thin-film type complete solid-state device, it has attracted attention from the viewpoints of space saving and portability.

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

  For example, Japanese Patent No. 3093796 discloses a technique for doping a stilbene derivative, a distyrylarylene derivative or a tristyrylarylene derivative with a small amount of a phosphor to improve emission luminance and extend the lifetime of the device. Japanese Patent Laid-Open No. 63-264692 discloses 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 therein. For example, an element having an organic light emitting layer in which an 8-hydroxyquinoline aluminum complex is used as a host compound and doped with a quinacridone dye is known.

  In the technique disclosed in the above-mentioned patent document, when the emission from the excited singlet is used, the generation ratio of the singlet exciton and the triplet exciton is 1: 3, so the generation probability of the luminescent excited species is 25%. Since the light extraction efficiency is about 20%, the limit of the external extraction quantum efficiency (ηext) is set to 5%.

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

  In addition, recently discovered organic EL devices that use phosphorescence can realize a luminous efficiency that is approximately four times that of previous devices that use fluorescence. Research and development of light-emitting element layer configurations and electrodes are performed all over the world.

  For example, S.M. Lamansky et al. , J .; Am. Chem. Soc. , 123, 4304 (2001), a number of compounds are being studied for synthesis centering on heavy metal complexes such as iridium complexes.

  In addition, the organic EL element is an all-solid element composed of an organic material film having a thickness of only about 0.1 μm between the electrodes, and the light emission can be achieved with a relatively low voltage of about 2V to 20V. Therefore, it is a technology that is expected as a next-generation flat display and illumination.

  Furthermore, the recently discovered organic EL using phosphorescence emission can realize a light emission efficiency of about 4 times in principle compared to that using previous fluorescence emission. Research and development of device layer configurations and electrodes are performed all over the world.

  In addition, the structure of the organic EL element is a simple one 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. Although the cost should be kept low, this is not always the case at present, and a large amount of water is drained from 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 organic EL currently commercialized are manufactured by a so-called vapor deposition method in which a low molecular material is vapor deposited to form a film. 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. Are better.

However, since vapor 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 be applied only to a substrate with a small area. It takes a long time and has a low throughput.

  In particular, it is 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 for such applications.

  On the other hand, coating methods that produce organic compound layers by processes such as spin coating, ink jet, printing, and spraying are suitable for producing thin films at normal pressure and for producing uniform films over a large area. As one of means for enabling the above, a method using a solution containing an organic EL material has been proposed.

  However, in order to achieve high luminous efficiency and long life at the same time, it is desirable to stack a plurality of functional layers. In order to stack a plurality of layers using the coating method, the lower layer must be insoluble in the upper coating solution, but for very thin films of the order of several tens of nm, a slightly soluble solvent is required. Even if it exists, the problem that a part of lower layer film | membrane melt | dissolves or an interface will be disturb | confused by a solvent arises.

  Such contamination to the upper layer of the lower layer material and disturbance of the interface cause a decrease in the light emission efficiency of the device and a deterioration in the device life, and therefore need to be improved. To solve these problems, for example, a polymer material is used. It has been proposed to use.

  However, in general, polymer materials are difficult to purify, and in particular, organic electroluminescence devices are difficult to apply because very few impurities can cause a significant decrease in the light emission lifetime of the device.

  In addition, for example, there is a technique of increasing the molecular weight after forming a constituent layer of an organic electroluminescence element, and a technique of adding a material having two or more vinyl groups to a plurality of layers is disclosed. , A method of performing irradiation with ultraviolet rays or heat at the time of forming an organic layer before laminating the cathode (see, for example, Patent Document 1), and a production method of causing a Diels-Alder reaction between two molecules in the same layer to crosslink (For example, refer to Patent Document 2).

All of the above techniques are methods for completing the polymerization reaction at the time of film formation or immediately after film formation (before attaching the cathode), but are still insufficient from the practical viewpoint of improving the durability of the organic EL device. Therefore, there is a demand for further technology for improving the durability of elements.
JP 2001-297882 A JP 2003-86371 A

  An object of the present invention is to provide a method for producing an organic thin film having a step of forming a film using a reaction solution containing a polymer of a reactive monomer, and using the production method, the external extraction quantum efficiency is high, and the emission lifetime The organic EL element is provided, and an electronic device including the organic thin film, the organic EL element, a display device including the organic EL element, and a lighting device are provided.

  The above object of the present invention has been achieved by the following constitutions 1 to 13.

  1. A method for producing an organic thin film, comprising the steps of: applying energy to a reactive monomer, preparing a reaction solution containing a polymer of the reactive monomer, and forming a film using the reaction solution.

  2. 2. The method for producing an organic thin film according to 1 above, wherein the energy application is performed by light irradiation.

  3. 2. The method for producing an organic thin film according to 1 above, wherein the energy application is performed by heat treatment.

  4). 4. The method for producing an organic thin film according to any one of 1 to 3, wherein the reaction solution does not contain a polymerization initiator.

  5. 5. The method for producing an organic thin film according to any one of 1 to 4, wherein a water content of the reaction solution is 100 ppm or less.

  6). 6. The method for producing an organic thin film according to any one of 1 to 5, wherein the amount of dissolved oxygen in the reaction solution is 100 ppm or less.

  7. An organic thin film produced by the method for producing an organic thin film according to any one of 1 to 6 above.

  8). 8. An electronic device formed using the organic thin film as described in 7 above.

  9. 8. An organic electroluminescence element formed using the organic thin film as described in 7 above.

  10. 10. The organic electroluminescence device as described in 9 above, which contains a phosphorescent compound.

  11. 11. The organic electroluminescence device as described in 9 or 10 above, which emits white light.

  12 A display device comprising the organic electroluminescence element according to any one of 9 to 11 above.

  13. The illuminating device provided with the organic electroluminescent element of any one of said 9-11.

  According to the present invention, a method for producing an organic thin film having a step of forming a film using a reaction solution containing a polymer of a reactive monomer, and using the production method, the external extraction quantum efficiency is high and the emission lifetime is long. An organic EL element was provided, and an electronic device including the organic thin film, an organic EL element, a display device including the organic EL element, and a lighting device could be provided.

  In the manufacturing method of the organic thin film of this invention, it has the process formed into a film using the reaction solution containing the polymer of a reactive monomer by having the structure of any one of Claims 1-6. An organic thin film manufacturing method could be provided.

  Using the manufacturing method, an electronic device including an organic thin film, an organic EL element, a display device including the organic EL element, and a lighting device can be provided.

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

<< Method for producing organic thin film >>
The manufacturing method of the organic thin film of this invention is demonstrated.

  As a result of various studies on the above-mentioned problems, the present inventors have focused attention on the film formation process of the constituent layers of the organic EL element.

  As a method for producing a conventionally known organic EL element, a method for producing an organic thin film by a vacuum vapor deposition method is generally used. However, the conventional vacuum vapor deposition method requires a high vacuum and can be produced. The size of the material is limited, and at the same time, a step for putting in and out the member is required, which is not suitable for continuous production.

  On the other hand, as a means for enabling continuous production, a method using a solution of an EL material has been proposed, and a low molecular material or a high molecular material can be used as an EL (electroluminescence) material. Yes.

  However, as described in the background art, in the application using a low molecular material, mixing of the lower layer and the upper layer cannot be suppressed at the time of forming the laminated film, and it is difficult to obtain a high-performance EL element. In the case of a polymer material, although a laminated film can be formed, it is difficult to remove a catalyst or the like during polymer production, and these are said to be one factor that degrades the lifetime of the EL element.

(Reaction solution: solution containing polymer of reactive monomer)
Therefore, the present inventors used a reactive monomer in the step of synthesizing an organic EL element material (also simply referred to as EL material), and applied energy before film formation (preferably immediately before film formation). It has been found that a high-purity polymer can be obtained by forming a monomer polymer (also referred to as a polymer, or a homopolymer or a copolymer).

(Energy provision means)
Examples of the energy application means according to the present invention include application means such as light irradiation (ultraviolet light, infrared light, visible light, electron beam irradiation, neutron beam irradiation, α-ray irradiation, X-ray irradiation, etc.) and heat treatment. Of these, ultraviolet irradiation and heat treatment are preferably used.

  The heat treatment is preferably in the range of 50 ° C. to 200 ° C., and the heating time is preferably in the range of 1 second to 30 minutes from the viewpoint of increasing production efficiency.

  Moreover, as a light source used for an ultraviolet-ray process, the spot light source LIGHTNINGCURE LC8 (made by Hamamatsu Photonics) is mentioned, for example.

(High purity polymer)
In the present invention, "high purity" is used for polymer synthesis such as conventionally known polymerization initiators, chain transfer agents, polymerization accelerators, polymerization reaction terminators, polymerization retarders, etc. It means that the reaction solution does not contain various additives.

  Here, “not containing various additives” means that the content of the additive in the reaction solution is 0.01% by mass or less, preferably 0.01% by mass or less. .

  The content of the additive in the reaction solution can be measured using a commercially available LC-MS (liquid chromatograph-mass spectrometer).

(Water content in the reaction solution)
The water content of the reaction solution according to the present invention is preferably 100 ppm or less, and more preferably 50 ppm or less.

  Here, the water content of the reaction solution can be analyzed by a commercially available Karl Fischer moisture meter.

(Amount of dissolved oxygen in the reaction solution)
The amount of dissolved oxygen in the reaction solution according to the present invention is preferably 100 ppm or less, and more preferably 50 ppm or less.

  Here, the amount of dissolved oxygen in the reaction solution can be analyzed by a commercially available dissolved oxygen meter.

(Reactive monomer)
The reactive monomer according to the present invention will be described.

  The reactive monomer according to the present invention is an organic EL element material having a polymerization reactive group, and a compound in which a polymerization reactive group is introduced into a material forming a constituent layer of an organic EL element described later can be used.

  Here, the polymerization reactive group may be any group capable of causing a radical polymerization reaction, an ionic polymerization reaction, a condensation polymerization reaction, etc., for example, a vinyl group, a vinyloxy group, an acryloyl group, a methacryloyl group, a mercapto group. , Hydroxy group, carboxy group, cyanate group, isocyanate group, thiocyanate group, isothiocyanate group, group derived from oxirane (ethylene oxide) (epoxy group), group derived from trimethylene oxide (oxetane), etc. it can.

  Hereinafter, although the specific example of a reactive monomer is shown, this invention is not limited to these.

  In the specific examples of the reactive monomer, compounds 1-1 to 1-26 are preferably used as host compounds having a polymerizable reactive group, and compounds 2-1 to 2-33 are polymerizable reactions. It is preferably used as a light-emitting dopant having a group (also simply referred to as a dopant).

  Compounds 3-1 to 21-21 are preferably used as an electron transport material having a polymerizable reactive group, and compounds 4-1 to 4-20 are preferably used as a hole transport material having a polymerizable reactive group. .

  The reactive monomer may further have a substituent, and examples of the substituent include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group). Octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (eg, vinyl group, allyl group, etc.), alkynyl group (eg, Ethynyl group, propargyl group etc.), aryl group (eg phenyl group, naphthyl group etc.), aromatic heterocyclic group (eg furyl group, thienyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group, Imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, carbazolyl group, A ruborinyl group, a diazacarbazolyl group (indicating that one of the carbon atoms constituting the carboline ring of the carbolinyl group is replaced by a nitrogen atom), a phthalazinyl group), a heterocyclic group (for example, a 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.), cycloalkoxy group (for example, Cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), alkylthio group (eg, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group) Etc.), Shiku An alkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.), an arylthio group (eg, phenylthio group, naphthylthio group, etc.), an alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyl) Oxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butyl) Aminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl Group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecyl) Carbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group) ), An amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group). 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, naphthylaminocarbonyl group, 2-pyridylamino Carbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido) 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, dodecyl) Sulfonyl group, etc.), arylsulfonyl group or heteroarylsulfonyl group (for example, phenylsulfonyl group, naphthylsulfonyl group, 2-pyridyl group) 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.). 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.

<Organic thin film>
By using the obtained reaction solution containing a high-purity, reactive monomer polymer as it is in the film-forming process, various additives used in the conventional polymerization reaction (the conventionally known polymerization start used in the polymerization reaction) An organic thin film using a high-purity polymer that does not contain an agent, a chain transfer agent, a polymerization accelerator, a polymerization reaction terminator, a polymerization retarder, and the like.

  The organic thin film of the present invention thus obtained can be suitably used for the organic EL element of the present invention, the electronic device of the present invention, and the like.

《Electronic device》
The electronic device of the present invention will be described.

  The electronic device of the present invention can be formed into various electronic devices using the organic thin film of the present invention. Among them, elements involving light are preferably used.

  Examples of elements that involve light include liquid crystal display elements, electrophotography using organic photoreceptor thin films, organic photovoltaic cells, photochemical hole burning (PHB) recording elements, organic electroluminescence elements (organic EL elements), Langmuir / Blodgets. Various optical functional elements using the (LB) film may be mentioned, and an organic EL element is particularly preferable.

  Hereinafter, the organic EL element, which is a preferred embodiment among the electronic devices of the present invention, will be described in more detail.

<< Organic EL element >>
The organic EL device of the present invention having an organic thin film obtained by the method for producing an organic thin film of the present invention will be described.

  According to the method for producing an organic thin film of the present invention, it is possible to form an organic thin film (either a single layer film or a laminated film) using a high-purity low molecule as a starting material. Therefore, it is possible to improve the light emission efficiency of the organic EL device, improve the device life, and the like.

<< Constituent layers of organic EL elements >>
The constituent layers of the organic EL element of the present invention will be described. In this invention, although the preferable specific example of the layer structure 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.

<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 from the viewpoint of improving the uniformity of the film, preventing unnecessary application of high voltage during light emission, and improving the stability of the emission color with respect to the drive current. It is preferable to adjust in the range of 2 nm to 5 μm, more preferably in the range of 2 nm to 200 nm, and particularly preferably in the range of 10 nm to 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 and 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 light emitting host compound and at least one kind of light emitting dopant (such as a phosphorescent dopant (also referred to as a phosphorescent dopant) or a fluorescent dopant).

(Host compound (also called luminescent host))
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.

  As the host compound, known host compounds may be used alone or in combination of two or more. 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 can thereby obtain arbitrary luminescent colors.

  The light emitting host used in the present invention may be a conventionally known low molecular compound or a high molecular compound having a repeating unit, and a low molecular compound having a polymerizable group such as a vinyl group or an epoxy group (deposition polymerization property). Light emitting host).

  As the 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 becoming longer, and has a high Tg (glass transition temperature) is preferable.

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

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

(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 (also referred to as a fluorescent compound) or a phosphorescent dopant (also referred to as a phosphorescent emitter, a phosphorescent compound, a phosphorescent compound, or the like) can be used. From the viewpoint of obtaining an organic EL device with high luminous efficiency, the light emitting dopant used in the light emitting layer or the light emitting unit of the organic EL device of the present invention (sometimes simply referred to as a light emitting material) contains the above host compound. At the same time, it is preferable to contain 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, the phosphorescent dopant is a compound that emits phosphorescence at room temperature (25 ° C.) and has a phosphorescence quantum yield of 25. Although it is defined as a compound of 0.01 or more at ° C., a preferable phosphorescence quantum yield is 0.1 or more.

  The phosphorescence quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of Experimental Chemistry Course 4 of the 4th edition. Although the phosphorescence quantum yield in a solution can be measured using various solvents, the phosphorescence dopant according to the present invention achieves the phosphorescence quantum yield (0.01 or more) in any solvent. That's fine.

  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, and this energy is transferred to the phosphorescent dopant. The energy transfer type that obtains light emission from the phosphorescent dopant, and the other is that the phosphorescent dopant becomes a carrier trap, carrier recombination occurs on the phosphorescent dopant, and light emission from the phosphorescent dopant is obtained. Although it is a trap type, in any case, the excited state energy of the phosphorescent dopant is required to be 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 of elements, more preferably an iridium compound, an osmium compound, or a platinum compound (platinum complex compound). Rare earth complexes, most preferably iridium compounds.

  Although the specific example of the compound used as a phosphorescence 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.

(Fluorescent dopant (also called fluorescent compound))
Fluorescent dopants (fluorescent compounds) include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, perylene dyes Examples thereof include dyes, stilbene dyes, polythiophene dyes, and rare earth complex phosphors.

  Next, an injection layer, a blocking layer, an electron transport layer and the like used as the constituent layers 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 typified by lithium, alkali metal compound buffer layer typified by lithium fluoride, alkaline earth metal compound buffer layer typified by magnesium fluoride, oxide buffer layer typified 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.

  The hole blocking layer preferably contains the azacarbazole derivative mentioned as the host compound.

  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) Keywords using Gaussian 98 (Gaussian 98, Revision A.11.4, MJ Frisch, et al, Gaussian, Inc., Pittsburgh PA, 2002.), which is 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 transport layer according to the present invention is preferably 3 nm to 100 nm, and more preferably 5 nm 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 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 cathode side with respect to the light emitting layer is injected from the cathode. As long as it has a function of transferring electrons to the light-emitting layer, any material selected from conventionally known compounds can be selected and used. 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.

  Also, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum, Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), etc., and the central metals of these metal complexes are In, Mg, Cu , Ca, Sn, Ga, or Pb can also be used as an 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 similarly to the hole injection layer and the hole transport layer, inorganic semiconductors such as n-type-Si and n-type-SiC 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.

"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 nm to 1000 nm, preferably 10 nm to 200 nm.

"cathode"
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Suitable are a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, a lithium / aluminum mixture, aluminum and the like.

  The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering.

  The sheet resistance as a 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 nm 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 light emission luminance is improved, which is convenient.

  Moreover, after producing the said metal by the film thickness of 1 nm-20 nm to a cathode, the 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 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 intrusion 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 an oxygen permeability of 1 × 10 ⁻³ ml / (m ² · 24 h · MPa) or less measured by a method according to JIS K 7126-1987, 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. Therefore, 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 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. Light that cannot be emitted due to total internal reflection between layers is diffracted by introducing a diffraction grating in any layer or medium (in a transparent substrate or transparent electrode), and the light is removed. 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.

<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 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 μm 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 / electron transport layer / electron injection 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 so as to have a film thickness of 1 μm or less, preferably 10 nm to 200 nm, to form an anode.

  Next, an organic compound thin film of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a hole blocking layer, which are organic EL element materials, 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.

  Examples of the liquid medium for dissolving or dispersing the organic EL material 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, toluene, xylene, and mesitylene. Aromatic hydrocarbons such as cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, and organic solvents such as DMF and DMSO 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 1 μm or less, preferably by a method such as vapor deposition or sputtering so that the film thickness is in the range of 50 nm to 200 nm. By providing, a desired organic EL element can be obtained.

  In addition, it is also possible to reverse the production order and produce the cathode, the electron injection layer, the electron transport 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 positive polarity of the anode and the negative polarity of the cathode. 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.

Further, when the organic EL element of the present invention is a white element, white means that the chromaticity in the CIE1931 color system at 1000 Cd / m ² is X when the 2-degree viewing angle front luminance is measured by the above method. = 0.33 ± 0.07 and Y = 0.33 ± 0.1.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these. In addition, the compound used for an Example is shown below.

Example 1
For preparing the organic EL elements, the following coating solutions 1-1 to 1-5 were prepared, and then each organic EL element was manufactured using the coating solution.

<< Preparation of Coating Solutions 1-1 to 1-5 >>: Polymer Formation by Light Irradiation Under a nitrogen atmosphere, CBP (600 mg) and Ir-1 (30 mg) were dissolved in 60 ml of dehydrated dichloroethane, and ultraviolet light was stirred with a high-pressure mercury lamp. The coating solution 1-1 was prepared by irradiating light for 120 seconds.

  Next, coating solutions 1-2 to 1-5 were respectively prepared in the same manner as in the preparation of the coating solution 1-1 except that the compounds used in the light emitting layer were changed as shown in Table 1.

  When a part of the obtained coating solutions 1-2 to 1-5 was analyzed by a commercially available LC-MS (liquid chromatograph-mass spectrometer), it was possible to confirm the formation of a polymer of the contained monomer. However, the composition of the coating solution 1-1 was not changed before and after irradiation with ultraviolet light.

  Further, the water content and dissolved oxygen content of these coating solutions were measured and found to be 10 ppm or less, respectively.

<< 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 substrate was attached to a commercially available spin coater, and 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, After forming a film by spin coating in 30 seconds, the film was dried at 200 ° C. for 1 hour to provide a 30 nm-thick hole transport layer.

  After completion of the drying process, the substrate is again attached to the spin coater, and an organic thin film (film thickness: 40 nm) is formed by spin coating under the condition of 1000 rpm for 30 seconds using the coating solution 1-1, followed by vacuum drying at 60 ° C. for 1 hour. Thus, a light emitting layer was obtained.

Next, this substrate is fixed to a substrate holder of a vacuum deposition apparatus, 200 mg of bathocuproine (BCP) is put into a molybdenum resistance heating boat, and 200 mg of Alq ₃ is put into another resistance heating boat made of molybdenum. Attached.

After the pressure in the vacuum chamber is reduced to 4 × 10 ⁻⁴ Pa, the heating boat containing BCP is energized and heated, and is deposited on the light emitting layer at a deposition rate of 0.1 nm / second, and further a positive film having a thickness of 10 nm. A hole blocking layer was provided.

Subsequently, the heating boat containing Alq ₃ was energized and heated, and deposited on the hole blocking layer at a deposition rate of 0.1 nm / second to provide an electron transport layer having a thickness of 40 nm. 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 1-5 >>
In the production of the organic EL element 1-1, the organic EL elements 1-2 to 1-5 were prepared in the same manner except that the coating solution 1-1 was replaced with the coating solutions 1-2 to 1-5 to form an organic thin film. Each was produced.

<< Evaluation of Organic EL Elements 1-1 to 1-5 >>
The organic EL elements 1-1 to 1-5 were evaluated as follows.

  When evaluating the obtained organic EL elements 1-1 to 1-15, the non-light-emitting surface of each organic EL element after production is covered with a glass case, and a glass substrate having a thickness of 300 μm is 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. 1 and 2 was formed and evaluated.

  FIG. 1 shows a schematic diagram of a lighting device, in which an organic EL element 101 is covered with a glass cover 102 (in addition, sealing with a glass cover is performed in a nitrogen atmosphere without bringing the organic EL element 101 into contact with the atmosphere. (In a high purity nitrogen gas atmosphere with a purity of 99.999% or more).

  FIG. 2 shows a cross-sectional view of the lighting device. In FIG. 2, 105 denotes a cathode, 106 denotes an organic EL layer, and 107 denotes a glass substrate with a transparent electrode. The glass cover 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided.

《External extraction quantum efficiency》
For each of the organic EL elements 1-1 to 1-5, the external extraction quantum efficiency (%) was measured when a constant current of ^2.5 mA / cm ² was applied at 23 ° C. in a dry nitrogen gas atmosphere. Table 1 shows. For the measurement, a spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing) was used.

  In addition, the measurement result of the external extraction quantum efficiency of Table 1 was expressed as a relative value when the measurement value of the organic EL element 1-1 was set to 100.

<Luminescent life>
When driven at a constant current of 2.5 mA / cm ^2, the luminance is to measure the time required to drop to half of the emission immediately after the start of the luminance (initial luminance), as the half-life time (tau ^{0. 5)} It was used as an index of life. A spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing) was used for the measurement.

  In addition, the measurement result of the light emission lifetime shown in Table 1 was represented by the relative value when the measured value of the organic EL element 1-1 was set to 100.

  The obtained results are shown in Table 1.

  From Table 1, it is clear that the organic EL device of the present invention has a longer life than the comparative organic EL device.

Example 2
<< Preparation of Coating Solutions 2-1 to 2-3 >>: Polymer Formation by Heat Treatment In a nitrogen atmosphere, Exemplified Compound 4-1 (600 mg) is dissolved in 60 ml of dehydrated xylene and heated at 130 ° C. for 30 minutes to form a coating solution. 2-1.

  Subsequently, Exemplified Compound 1-21 (600 mg) and Exemplified Compound 2-25 (30 mg) were dissolved in 60 ml of dehydrated xylene under a nitrogen atmosphere and heated at 130 ° C. for 30 minutes to prepare a coating solution 2-2.

  Further, Exemplified Compound 3-14 (600 mg) was dissolved in 60 ml of dehydrated xylene under a nitrogen atmosphere and heated at 130 ° C. for 30 minutes to prepare a coating solution 2-3.

  A part of each of the prepared coating solutions 2-1 to 2-3 was analyzed by a commercially available LC-MS (liquid chromatograph-mass spectrometer) in the same manner as described in Example 1 to determine the weight of the contained monomer. Formation of coalescence could be confirmed. Further, the water content and dissolved oxygen content of these coating solutions were measured and found to be 10 ppm or less, respectively.

<< Preparation of the organic EL element 2-1 >>: Blue light emitting element Patterned on a substrate (NA45 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 Then, the transparent support substrate provided with the ITO transparent electrode 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, and 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, After forming a film by spin coating in 30 seconds, the film was dried at 200 ° C. for 1 hour to provide a hole injection layer having a thickness of 30 nm.

  After completion of the drying treatment, the substrate is again attached to the spin coater, and a hole transport layer is provided as an organic thin film by spin coating under the condition of 1000 rpm for 30 seconds using the coating solution 2-1, followed by coating solution 2- 2 is used to form a light emitting layer as an organic thin film by spin coating under conditions of 1000 rpm for 30 seconds, and further, holes are formed by spin coating under conditions of 1000 rpm for 30 seconds using coating solution 2-3. A blocking layer was provided.

Subsequently, this substrate was fixed to a substrate holder of a vacuum deposition apparatus, 200 mg of Alq ₃ was placed in a molybdenum resistance heating boat, and attached to the vacuum deposition apparatus.

After reducing the vacuum chamber to 4 × 10 ⁻⁴ Pa, the heating boat containing Alq ₃ was energized and heated, and deposited on the hole blocking layer at a deposition rate of 0.1 nm / sec. An electron transport 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 2-1 was produced.

  When this element was energized, blue light emission was obtained, indicating that it could be used as an organic EL display device.

Example 3
<< Preparation of Organic EL Element 3-1 >> Preparation of White Lighting Device In preparation of organic EL element 1-4 of Example 1, Illustrated Compound 2-19 (30 mg) was replaced with Ir-1 (9 mg), Ir-9 ( 9 mg) and Ir-14 (12 mg) were used in the same manner to form an organic thin film (light-emitting layer) to produce an organic EL device 3-1.

  When this element was energized, almost white light was obtained, and it was found that it could be used as a lighting device.

It is the schematic of an illuminating device. It is sectional drawing of an illuminating device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Organic EL element 102 Glass cover 105 Cathode 106 Organic EL layer 107 Glass substrate with a transparent electrode 108 Nitrogen gas 109 Water catching agent

Claims (13)

A method for producing an organic thin film, comprising the steps of: applying energy to a reactive monomer, preparing a reaction solution containing a polymer of the reactive monomer, and forming a film using the reaction solution. The method for producing an organic thin film according to claim 1, wherein the energy application is performed by light irradiation. The method for producing an organic thin film according to claim 1, wherein the energy application is performed by heat treatment. The method for producing an organic thin film according to any one of claims 1 to 3, wherein the reaction solution contains no polymerization initiator. The method for producing an organic thin film according to any one of claims 1 to 4, wherein the water content of the reaction solution is 100 ppm or less. The method for producing an organic thin film according to any one of claims 1 to 5, wherein the amount of dissolved oxygen in the reaction solution is 100 ppm or less. The organic thin film manufactured by the manufacturing method of the organic thin film of any one of Claims 1-6. An electronic device formed using the organic thin film according to claim 7. An organic electroluminescence element formed using the organic thin film according to claim 7. The organic electroluminescent device according to claim 9, comprising a phosphorescent compound. The organic electroluminescence device according to claim 9, which emits white light. A display device comprising the organic electroluminescence element according to claim 9. The illuminating device provided with the organic electroluminescent element of any one of Claims 9-11.

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