JP5697856B2 - ORGANIC ELECTROLUMINESCENT ELEMENT, WHITE ORGANIC ELECTROLUMINESCENT ELEMENT, DISPLAY DEVICE AND LIGHTING DEVICE - Google Patents

Description

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

  Conventionally, there is an electroluminescence display (ELD) as a light-emitting electronic display device. Examples of the constituent elements of ELD include inorganic electroluminescent elements and organic electroluminescent elements (hereinafter also 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 this exciton is deactivated, and can emit light at a voltage of several volts to several tens of volts. Therefore, it has a wide viewing angle, high visibility, and since it is a thin-film type completely solid element, it has attracted attention from the viewpoints of space saving and portability.

  As the development of organic EL elements for practical application, since Princeton University has reported on organic EL elements that use phosphorescence emission from excited triplets (for example, see Non-Patent Document 1), phosphorescence at room temperature has occurred. Research on the materials shown has become active (see, for example, Non-Patent Document 2 and Patent Document 1).

  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, many compounds have been studied for synthesis centering on heavy metal complexes such as iridium complexes (see, for example, Non-Patent Document 3).

  Although this is a very high potential method, the organic EL device using phosphorescence emission is greatly different from the organic EL device using fluorescence emission, and the method for controlling the position of the emission center, particularly the emission layer, is particularly different. An important technical issue in capturing the efficiency and lifetime of the device is how to recombine inside to stably emit light. Therefore, in recent years, a multilayer laminate comprising a hole transport layer (located on the anode side of the light emitting layer) and a carrier transport layer such as an electron transport layer (located on the cathode side of the light emitting layer) adjacent to the light emitting layer. A type element is well known (see, for example, Non-Patent Document 4).

  On the other hand, due to demands for large area, low cost, and high productivity, there is a great expectation for the wet process, and not only the organic layer but also de-evacuation in electrode film formation is strongly required. Examples of electrode film formation by a wet process include using PEDOT / PSS instead of the ITO anode, coating film formation of a low-melting metal paste (see, for example, Patent Document 2), and conductive paste material. A cathode forming method by coating film formation (for example, see Patent Document 3) has been reported.

  However, there are problems with damage to the organic layer during film formation, and further improvement techniques are indispensable.

US Pat. No. 6,097,147 JP 2005-285732 A JP 2005-514729 A

M.M. A. Baldo et al. , Nature, 395, 151-154 (1998) M.M. A. Baldo et al. , Nature, 403, 17, 750-753 (2000) S. Lamansky et al. , J .; Am. Chem. Soc. 123, 4304 (2001) Organic EL Handbook P-198 Realize Science Center, published in 2004

  The objective of this invention is providing the organic electroluminescent element excellent in luminous efficiency and the light emission lifetime, the display apparatus using this element, and an illuminating device.

The above object of the present invention can be achieved by the following configurations 1 to 8.
Specifically, according to the present invention, in Configuration 1, the cathode is formed through a film-forming process by a wet method using a conductive paste containing an organic solvent that is a branched saturated hydrocarbon having 6 to 10 carbon atoms. And the organic electroluminescent element whose low molecular weight compound is a compound which has a partial structure represented by following General formula (1) is provided.

  1. In a phosphorescent organic electroluminescent device having an organic layer sandwiched between an anode and a cathode, at least one of the organic layers is formed through a film forming process by a wet method adjacent to the cathode. A cathode which is an electron transport layer containing a low molecular weight compound and is formed through a film forming process by a wet method using a conductive paste containing an organic solvent which is at least a saturated hydrocarbon having 6 to 17 carbon atoms And an organic electroluminescence element.

  2. 2. The organic electroluminescence device according to 1 above, wherein the saturated hydrocarbon is a branched saturated hydrocarbon having 6 to 17 carbon atoms.

  3. 3. The organic electroluminescence device as described in 1 or 2 above, wherein the low molecular weight compound is a compound having a partial structure represented by the following general formula (1).

In the formulas, A is -O -, - S- or -N _{(R 1)} - _represents, A 11 _{to A 18} are each a nitrogen atom or -C _{(R 2)} - represents a. R ₁ and R ₂ each represent a bond, a hydrogen atom, or a substituent. However, -C _{(R 2)} - if a plurality, each of -C _{(R 2)} - may be the same or different. ]
4). The phosphorescent light-emitting layer adjacent to the electron transporting layer has at least a phosphorescent dopant and a light-emitting host, and the phosphorescent dopant is represented by the following general formula (2 4. The organic electroluminescence device according to any one of 1 to 3 above, wherein the organic electroluminescence device is a compound represented by

[Wherein, Q ₁ represents a 5-membered or 6-membered aromatic ring. Ar represents an aromatic hydrocarbon group or an aromatic heterocyclic group, and R ₃ and R ₄ represent a hydrogen atom or a substituent. k represents an integer of 2 or 3, and has m secondary ligands L so as to satisfy the valence of iridium. ]
5. Item 5. The phosphorescent light-emitting layer contains at least a phosphorescent dopant and a light-emitting host, and uses the compound represented by the general formula (1) as a light-emitting host. Organic electroluminescence element.

  6). A white organic electroluminescence device comprising the organic electroluminescence device according to any one of 1 to 5 above.

  7). 6. A display device comprising the organic electroluminescent element according to any one of 1 to 5 or the white organic electroluminescent element according to 6 above.

  8). 6. An illuminating device comprising the organic electroluminescent element according to any one of 1 to 5 or the white organic electroluminescent element according to 6 above.

  According to the present invention, it is possible to provide an organic electroluminescence element having high external extraction quantum efficiency, a long emission lifetime, and an improved rectification ratio, a white organic electroluminescence element including the element, a display device, and an illumination device. did it.

It is the schematic diagram which showed an example of the display apparatus comprised from an organic EL element. It is a schematic diagram of a display part. It is a schematic diagram of a pixel. It is a schematic diagram of a passive matrix type full color display device. It is the schematic of an illuminating device. It is sectional drawing of an illuminating device.

  The best mode for carrying out the present invention will be described in detail below, but the present invention is not limited thereto.

  The organic EL device of the present invention is a phosphorescent organic EL device having an organic layer sandwiched between an anode and a cathode, and contains a low molecular weight compound adjacent to the cathode as a constituent layer of the organic layer. A film is formed by a wet method using a conductive paste having an electron transport layer formed through a film forming process by a wet method, and the cathode containing an organic solvent in which the cathode is a saturated hydrocarbon having 6 to 17 carbon atoms. It is formed through the following process.

  Here, the wet method will be described in detail in the method of manufacturing the organic EL element.

<Low molecular compound>
The low molecular weight compound according to the present invention will be described.

In the general formula (1), the substituent represented by R ₁ or R ₂ is 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 (for example, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (for example, vinyl group, allyl group, 1-propenyl group, 2-butenyl group, 1,3-butadienyl group, 2-pentenyl group, isopropenyl group, etc.), alkynyl group (for example, ethynyl group, propargyl group, etc.), aromatic hydrocarbon group (aromatic hydrocarbon ring group, aromatic carbocyclic group, Also referred to as an aryl group, for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, xylyl group, naphthyl , Anthryl group, azulenyl group, acenaphthenyl group, fluorenyl group, phenanthryl group, indenyl group, pyrenyl group, etc.), aromatic heterocyclic group (for example, furyl group, thienyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group) , Triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, carbazolyl group, carbolinyl group, diazacarbazolyl group (one of the carbon atoms constituting the carboline ring of the carbolinyl group is replaced by a nitrogen atom) Phthalazinyl group etc.), heterocyclic group (eg pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group etc.), alkoxy group (eg methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyl) Oxy group, octyloxy Si group, dodecyloxy group, etc.), cycloalkoxy group (eg, 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.), cycloalkylthio group (for example, cyclopentylthio group, cyclohexylthio group, etc.), arylthio group (for example, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (For example, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (for example, phenyloxycarbonyl group) Bonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecyl) Aminosulfonyl 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 (example) For example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonyl) Amino group, propylcarbonylamino 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, cyclohexane Xylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethyl) Ureido group, pentylureido 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-pyridyls Finyl group etc.), alkylsulfonyl group (eg methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group etc.), arylsulfonyl group or heteroarylsulfonyl group (eg Phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, Anilino group, naphthylamino group, 2-pyridylamino group, etc.), halogen atom (eg fluorine atom, chlorine atom, bromine atom etc.), fluorinated hydrocarbon group (eg fluoromethyl group, trifluoromethyl group, pentaf) Oroethyl 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, etc. Is mentioned.

  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.

  Hereinafter, specific examples of the compound preferably used as the low molecular weight compound according to the present invention will be shown, but the present invention is not limited thereto.

  The low molecular weight compounds according to the present invention are disclosed in JP 2007-288035 A, Chem. Mater. 2008, 20, 5951, experimental chemistry course 5th edition (edited by the Chemical Society of Japan) and the like can be synthesized with reference to known methods.

《Conductive paste》
For the cathode (cathode, anode, organic layer, etc. will be described in detail later) constituting the organic EL device of the present invention, a conductive paste containing an organic solvent that is a saturated hydrocarbon having 6 to 17 carbon atoms is used. The film is formed by a wet method. The saturated hydrocarbon having 6 to 17 carbon atoms is more preferably a branched saturated hydrocarbon having 6 to 17 carbon atoms. More preferably, it is a branched saturated hydrocarbon having 6 to 10 carbon atoms. Further, the number of branches is preferably 2 or more, and more preferably 3 or more. In the present invention, the branched saturated hydrocarbon conforms to the branched saturated hydrocarbon described in IUPAC (International Union of Pure and Applied Chemistry) nomenclature (A-2.1). Represents the number of side chains. For example, the number of branches of methylpentane is 3, and the number of branches of 1,2,2,4-trimethylpentane is 3.

  Specific examples are illustrated below, but the present invention is not limited thereto. 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methylpentane, 3-methylpentane, 2,2-dimethylpentane, 2,3-dimethylpentane, 2,4-dimethylpentane, 3,3-dimethyl Pentane, 2-methylhexane, 3-methylhexane, 2,2,3-trimethylbutane, 2,2-dimethylhexane, 2,4-dimethylhexane, 2,5-dimethylhexane, 3,4-dimethylhexane, 2 -Methylheptane, 3-methylheptane, 4methylheptane, 2,2,3,3-tetramethylbutane, 2,2,4-trimethylpentane, deuterated 2,2,4-trimethylpentane, 2,3 4-trimethylpentane, 2,3-dimethylheptane 2-methyloctane, 2,2,4-trimethylhexane, 2-methylnonane, 3-methyl Nonane, 4- methylnonanoic, 4-ethyl-3,3-dimethyl heptane, 2,2,4,6,6 pentamethyl heptane, may be mentioned 5-methyl-6-propyl-nonane.

  The conductive paste according to the present invention preferably contains a conductive dispersion or a low melting point metal compound.

here,
(A) The conductive dispersion is preferably a metal nanoparticle dispersion. Here, the metal nanoparticle dispersion refers to a solution in which metal nanoparticles having an average particle diameter of 1 nm to 100 nm are suspended in a solvent.

  In the solution, a dispersion stabilizer, a protective agent and the like may be mixed in order to prevent re-aggregation of metal nanoparticles. In addition, the viscosity and the like can be adjusted by selecting the metal nanoparticle concentration and the type of solvent in accordance with the purpose of use and apparatus specifications.

  Examples of the metal species of the metal nanoparticles according to the present invention include Ag, Au, Cu, Pd, Sn, In, Co, Bi, Al, Zn, and the like.

  Regarding the production of Al nanoparticles, it is also possible to refer to the AIST press release “Technology for printing metal electrodes on plastic films at low temperatures” on September 24, 2008.

  (B) The low melting point metal compound refers to an alloy having a melting point of 100 ° C. or lower, and the low melting point alloy is classified into an alkali metal type and other types depending on the use and handling. Alkali metal is an alloy between alkali metals, and NaK is known. However, since it reacts violently with air and water, it is mainly used as a heat medium in a sealed state. In the present invention, various alloys mainly containing zinc, indium, gallium, tin, bismuth, lead, etc. other than alkali metal are preferred.

  For example, solder that is an alloy of tin, galinstan that is a gallium alloy (composition is gallium 68.5%, indium 21.5%, tin 10%), wood metal that is a bismuth alloy (composition is 50% bismuth, lead 26 0.7%, tin 13.3%, cadmium 10%) and the like, and the melting point can be changed by changing the composition ratio of the alloy.

In the present invention,
(C) The conductive paste preferably contains an alkali metal or alkaline earth metal compound.

  In the present invention, it is preferable to contain an alkali metal or alkaline earth metal compound at the interface between the electron transport layer and the adjacent cathode. In the embodiment, the cathode contains an alkali metal or alkaline earth metal compound. Alternatively, the electron transport layer preferably contains an alkali metal or alkaline earth metal compound.

<< Method for Manufacturing Organic EL Element >>
As an example of a method for producing an organic EL element, a method for producing an element comprising an anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode will be described.

  First, a desired electrode material, for example, a thin film made of a material for an anode is formed on a suitable substrate so as to have a thickness of 1 μm or less, preferably 10 nm to 200 nm, thereby producing an anode.

  Next, a thin film containing an organic compound such as a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, or an electron transport layer, which is an element material, is formed thereon.

  Here, as the wet method, there are a spin coating method, a casting method, a die coating method, a blade coating method, a roll coating method, an ink jet method, a printing method, a spray coating method, a curtain coating method, etc., but a precise thin film can be formed. In view of high productivity, a method having high suitability for a roll-to-roll method such as a die coating method, a roll coating method, an ink jet method, or a spray coating method is preferable. Different film forming methods may be applied for each layer.

  After the formation of these layers, a thin film made of a cathode material is formed thereon so as to have a thickness of 1 μm or less, preferably in the range of 50 to 200 nm, and a desired organic EL device can be obtained by providing a cathode. .

  Further, the order can be reversed, and the cathode, the electron transport layer, the hole blocking layer, the light emitting layer, the hole transport layer, the hole injection layer, and the anode can be formed in this order.

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

  The organic EL device of the present invention is preferably produced from the hole injection layer to the cathode consistently by a single evacuation, but may be taken out halfway and subjected to different film forming methods. At that time, it is necessary to consider that the work is performed in a dry inert gas atmosphere.

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

(I) Anode / light emitting layer unit / electron transport layer / cathode (ii) Anode / hole transport layer / light emitting layer unit / electron transport layer / cathode (iii) Anode / hole transport layer / light emitting layer unit / hole blocking Layer / electron transport layer / cathode (iv) anode / hole transport layer / light emitting layer unit / hole blocking layer / electron transport layer / cathode buffer layer / cathode (v) anode / anode buffer layer / hole transport layer / light emission Layer unit / hole blocking layer / electron transport layer / cathode buffer layer / cathode << 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 thickness of the light emitting layer is not particularly limited, but from the viewpoint of the uniformity of the film to be formed, the application of unnecessary high voltage during light emission, and the improvement of the stability of the emission color with respect to the drive current. It is preferable to adjust to the range of 2 nm-200 nm, More preferably, it adjusts to the range of 5 nm-100 nm.

  The light emitting layer of the organic EL device of the present invention preferably contains at least one kind of a light emitting host compound and a light emitting dopant as a guest material, and more preferably contains a light emitting host compound and three or more kinds of light emitting dopants. Hereinafter, a host compound (also referred to as a light emitting host) and a light emitting dopant (also referred to as a light emitting dopant compound) included in the light emitting layer will be described.

(Host compound)
The host compound according to 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.

  The compound represented by the general formula (1) according to the present invention is also preferably used as the host compound according to the present invention.

  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, thereby, arbitrary luminescent colors can be obtained.

  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.

  Hereinafter, although the specific example of the compound which may be used together as a host compound of the light emitting layer of the organic EL element of this invention is given, this invention is not limited to these.

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

  Since the organic EL device of the present invention is phosphorescent, it contains at least a phosphorescent dopant (also referred to as phosphorescent emitter, phosphorescent compound, phosphorescent compound, etc.) as the luminescent dopant according to the present invention. To do.

(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, and this energy is transferred to the phosphorescent dopant. Energy transfer type to obtain 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 the phosphorescent dopant 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 system). Compound) and rare earth complexes, and most preferred is an iridium compound.

  As the phosphorescent dopant according to the present invention, a compound represented by the general formula (2) is preferably used.

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

In the general formula (2), the 5-membered or 6-membered aromatic ring represented by Q ₁ includes a benzene ring, an oxazole ring, an isoxazole ring, a thiophene ring, a furan ring, a pyrrole ring, a pyridine ring, a pyridazine ring, and a pyrimidine. A ring, a pyrazine ring, a diazine ring, a triazine ring, an imidazole ring, a pyrazole ring, a triazole ring, and the like.

  The above ring may further form a condensed ring and may have a substituent.

In the general formula (2), the aromatic hydrocarbon group and aromatic heterocyclic group represented by Ar are the aromatic hydrocarbon groups mentioned as the substituent represented by R ₁ or R ₂ in the general formula (1). And aromatic heterocyclic groups.

In the general formula (2), examples of the substituent represented by R ₃ and R ₄ include the substituents exemplified as the substituent represented by R ₁ or R ₂ in the general formula (1).

  In the general formula (2), as the secondary ligand L, oxycarboxylic acid, oxyaldehyde and derivatives thereof (for example, salicylaldehyde, oxyacetophenato, etc.), dioxy compounds (for example, biphenolato, etc.), diketones ( For example, acetylacetonate, dibenzoylmethanato, diethylmalonate, ethylacetoacetate, etc.), oxyquinones (eg, pyromeconato, oxynaphthoquinato, oxyanthraquinato, etc.), tropolones (eg, troponato, hinokitiolato, etc.) , N-oxide compounds, aminocarboxylic acids and similar compounds (eg, glycinato, alaninato, anthranilate, picolinato, etc.), hydroxylamines (eg, aminophenolato, ethanolaminato, mercaptoethylaminato, etc.), oxines ( For example, 8-oxyquinolinato etc.), aldimines (eg salicylaldiminato etc.), oximes (eg benzoin oximato, salicylaldoximato etc.), oxyazo compounds (eg oxyazobenzonat, phenylazonaphtholato) ), Nitrosonaphthols (for example, β-nitroso-α-naphtholate, etc.), triazenes (for example, diazoaminobenzenato, etc.), biurets (for example, biuretate, polypeptide group, etc.), formazenes and dithizones ( For example, diphenylcarbazonate, diphenylthiocarbazonate, etc.), piguanides (for example, piguanidate, etc.), glyoximes (for example, dimethylglyoximato, etc.) and the like can be mentioned.

  Various known ligands may also be used, for example, “Photochemistry and Photophysics of Coordination Compounds” Springer-Verlag H. Published by Yersin in 1987, “Organometallic Chemistry-Fundamentals and Applications-” Liu Huabo Company, Akio Yamamoto, published in 1982, etc. (for example, halogen ligands (preferably chlorine ligands), Nitrogen heterocyclic ligands (for example, bipyridyl, phenanthroline, etc.) and diketone ligands).

  Hereinafter, although the specific example of a compound represented by General formula (2) based on this invention as a phosphorescent dopant is shown, this invention is not limited to these.

<< Charge injection layer: electron injection layer, hole injection layer >>
The charge injection layer according to the present invention is provided as necessary, and includes an electron injection layer and a hole injection layer, and as described above, between the anode and the light emitting layer or the hole transport layer, and the cathode and the light emitting layer or the electron transport layer. It may be present between.

  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 having a function of transporting electrons and a very small ability to transport holes. By blocking the holes, the probability of recombination of electrons and holes can be improved.

  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 according to 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) 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 transport layer according to the present invention is preferably 3 nm to 100 nm, and more preferably 5 nm to 30 nm.

<< Charge transport layer: electron transport layer, hole transport layer >>
Examples of the charge transport layer according to the present invention include an electron transport layer and a hole transport layer.

  Hereinafter, the electron transport layer and the hole transport layer according to the present invention will be described in detail.

《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. About the film thickness of a positive hole transport layer, it is preferable that it is the range of 5 nm-5 micrometers, More 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.

  Hereinafter, although the specific example of the compound preferably used for formation of the positive hole transport layer of the organic EL element of this invention is given, this invention is not limited to these.

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

  Conventionally, in the case of a single electron transport layer and a plurality of layers, an electron transport material (also serving as a hole blocking material) used for an electron transport layer adjacent to the light emitting layer on the cathode side is injected from the cathode. As long as it has a function of transferring electrons to the light-emitting layer, any material can be selected and used from among conventionally known compounds. For example, nitro-substituted fluorene derivatives, diphenylquinone derivatives Thiopyrandioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives and the like.

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

  The electron transport layer can be formed by thinning the electron transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method.

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

  Alternatively, an electron transport layer with high n property doped with impurities as a guest material can 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.

  Hereinafter, although the specific example of the compound (electron transport material) preferably used together for formation of the electron carrying layer of the white organic EL element of this invention is given, this invention is not limited to these.

"anode"
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such electrode materials include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ , and ZnO. Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming a transparent conductive film may be used.

  For the anode, these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when pattern accuracy is not 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, the range of 10 nm to 1000 nm is preferable, and the range of 10 nm to 200 nm is more preferable.

"cathode"
As the cathode, a material having a work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound and a mixture thereof as an electrode material is used.

Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like.

Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred.

  In the present invention, these electrode substances (also referred to as conductive materials) are used as a conductive paste to form a thin film by a wet method to produce a cathode.

  The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is preferably in the range of 10 nm to 5 μm, more preferably in the range of 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.

"substrate"
As a substrate (hereinafter also referred to as a base, a base material, a support substrate, a support, etc.) that can be used in the organic EL device according to the present invention, there is no particular limitation on the type of glass, plastic, etc., and it is transparent. Or opaque. When extracting light from the substrate side, the substrate is preferably transparent. Examples of the transparent substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable 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 measured by a method in accordance with JIS K 7129-1992 (25 ± 0.5 ° C., It is preferably a barrier film having a relative humidity (90 ± 2)% RH) of 0.01 g / (m ² · 24 h) or less, and further, oxygen permeation measured by a method according to JIS K 7126-1987. The film is preferably a high barrier 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.

  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, the sputtering method, the reactive sputtering method, the molecular beam epitaxy method, the cluster ion beam method, the ion plating method, the plasma polymerization method, the atmospheric pressure plasma weighting. A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, and the like can be used. However, an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.

  Examples of the opaque substrate include a metal plate such as aluminum and stainless steel, a film, an opaque resin substrate, a ceramic substrate, and the like.

  The external extraction efficiency at room temperature of light emission of the organic EL device according to 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 of the organic EL element 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 organic EL element can be thinned.

Furthermore, the polymer film, measured oxygen permeability by the method based on JIS K 7126-1987 is ^{1 × 10 -3 ml / m 2} / 24h or less, as measured by the method based on JIS K 7129-1992 water vapor transmission rate (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) is preferably that of ^{1 × 10 -3 g / (m} 2 / 24h) 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 possible to suitably form an inorganic or organic layer as a sealing film by covering the electrode and the organic layer on the outer side of the electrode facing the substrate with the organic layer interposed therebetween, and in contact with the substrate. 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 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, 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 for improving the light extraction efficiency, for example, a method of forming irregularities on the surface of the transparent substrate to prevent total reflection at the interface between the transparent substrate and the air (US Pat. No. 4,774,435), A method for improving efficiency by giving light condensing property to a substrate (Japanese Patent Laid-Open No. 63-314795), a method for forming a reflective surface on the side surface of an organic EL element (Japanese Patent Laid-Open No. 1-220394), a substrate A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the substrate and the light emitter (Japanese Patent Laid-Open No. 62-172691), and lowering the refractive index than the substrate between the substrate and the light emitter. A method of introducing a flat layer having a structure (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) No. 283751) .

  In the present invention, these methods can be used in combination with the organic EL device according to 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, A method of forming a diffraction grating between any layers of the transparent 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 organic EL device having further high 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, more 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 according to the present invention can be processed on the light extraction side of the substrate, for example, by providing a microlens array-like structure, or combined with a so-called condensing sheet, for example, in a specific direction, for example, the device light emitting surface. On the other hand, the brightness | luminance in a specific direction can be raised by condensing in a front direction.

  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.

<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 according to the present invention is a white element, white means that the chromaticity in the CIE1931 color system at 1000 cd / m ² is measured when the front luminance at 2 ° viewing angle is measured by the above method. , X = 0.33 ± 0.07 and Y = 0.33 ± 0.1.

<Display device>
The display device of the present invention will be described. The display device of the present invention comprises the organic EL element of the present invention.

  Although the display device of the present invention may be single color or multicolor, the multicolor display device will be described here. In the case of a multicolor display device, a shadow mask is provided only at the time of forming a light emitting layer, and a film can be formed on one surface by vapor deposition, casting, spin coating, ink jet, printing, or the like.

  In the case of patterning only the light emitting layer, the method is not limited. However, the vapor deposition method, the ink jet method, the spin coating method, and the printing method are preferable.

  The configuration of the organic EL element provided in the display device is selected from the above-described configuration examples of the organic EL element as necessary.

  Moreover, the manufacturing method of an organic EL element is as having shown to the one aspect | mode of manufacture of the organic EL element of said invention.

  In the case of applying a DC voltage to the obtained multicolor display device, light emission can be observed by applying a voltage of about 2V to 40V with the positive polarity of the anode and the negative polarity of the cathode. Further, even when a voltage is applied with the opposite polarity, no current flows and no light emission occurs. Further, when an AC voltage is applied, light is emitted only when the anode is in the + state and the cathode is in the-state. The alternating current waveform to be applied may be arbitrary.

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

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

  Light sources include home lighting, interior lighting, clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, light sources for optical sensors, etc. The present invention is not limited to these examples.

  Hereinafter, an example of a display device having the organic EL element of the present invention will be described with reference to the drawings.

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

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

  The control unit B is electrically connected to the display unit A, and sends a scanning signal and an image data signal to each of a plurality of pixels based on image information from the outside. The image information is sequentially emitted to scan the image and display the image information on the display unit A.

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

  The display unit A includes a wiring unit including a plurality of scanning lines 5 and data lines 6, a plurality of pixels 3 and the like on a substrate. The main members of the display unit A will be described below.

  In the figure, the light emitted from the pixel 3 is extracted in the direction of the white arrow (downward).

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

  When a scanning signal is applied from the scanning line 5, the pixel 3 receives an image data signal from the data line 6 and emits light according to the received image data.

  Full-color display is possible by appropriately arranging pixels in the red region, the green region, and the blue region on the same substrate.

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

  FIG. 3 is a schematic diagram of a pixel.

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

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

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

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

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

  Here, the light emission of the organic EL element 10 may be light emission of a plurality of gradations by a multi-value image data signal having a plurality of gradation potentials, or by turning on / off a predetermined light emission amount by a binary image data signal. Good. The potential of the capacitor 13 may be held continuously until the next scanning signal is applied, or may be discharged immediately before the next scanning signal is applied.

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

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

  When the scanning signal of the scanning line 5 is applied by sequential scanning, the pixels 3 connected to the applied scanning line 5 emit light according to the image data signal.

  In the passive matrix system, the pixel 3 has no active element, and the manufacturing cost can be reduced.

《Lighting device》
The lighting device of the present invention will be described. The illuminating device of this invention has the said organic EL element.

  The organic EL element of the present invention may be used as an organic EL element having a resonator structure. The purpose of use of the organic EL element having such a resonator structure is as follows. The light source of a machine, the light source of an optical communication processing machine, the light source of a photosensor, etc. are mentioned, However, It is not limited to these. Moreover, you may use for the said use by making a laser oscillation.

  Further, the organic EL element of the present invention may be used as a kind of lamp for illumination or exposure light source, a projection device for projecting an image, or a display for directly viewing a still image or a moving image. It may be used as a device (display).

  The driving method when used as a display device for moving image reproduction may be either a simple matrix (passive matrix) method or an active matrix method. Alternatively, a full-color display device can be manufactured by using two or more organic EL elements of the present invention having different emission colors.

  The organic EL material of the present invention can be applied to an organic EL element that emits substantially white light as a lighting device. A plurality of light emitting colors are simultaneously emitted by a plurality of light emitting materials to obtain white light emission by color mixing. The combination of a plurality of emission colors may include three emission maximum wavelengths of the three primary colors of blue, green, and blue, or two using the relationship of complementary colors such as blue and yellow, blue green and orange, etc. The thing containing the light emission maximum wavelength may be used.

  In addition, a combination of light emitting materials for obtaining a plurality of emission colors is a combination of a plurality of phosphorescent or fluorescent materials, a light emitting material that emits fluorescence or phosphorescence, and light from the light emitting material as excitation light. Any of those combined with a dye material that emits light may be used, but in the white organic EL device according to the present invention, only a combination of a plurality of light-emitting dopants may be mixed.

  It is only necessary to provide a mask only when forming a light emitting layer, a hole transport layer, an electron transport layer, etc., and simply arrange them separately by coating with the mask. Since other layers are common, patterning of the mask or the like is not necessary. In addition, for example, an electrode film can be formed by a vapor deposition method, a cast method, a spin coating method, an ink jet method, a printing method, or the like, and productivity is also improved.

  According to this method, unlike a white organic EL device in which light emitting elements of a plurality of colors are arranged in parallel in an array, the elements themselves are luminescent white.

  There is no restriction | limiting in particular as a luminescent material used for a light emitting layer, For example, if it is a backlight in a liquid crystal display element, the metal complex which concerns on this invention so that it may suit the wavelength range corresponding to CF (color filter) characteristic, Any one of known luminescent materials may be selected and combined to whiten.

<< One Embodiment of Lighting Device of the Present Invention >>
One aspect of the lighting device of the present invention that includes the organic EL element of the present invention will be described.

  The non-light emitting surface of the organic EL device of the present invention is covered with a glass case, a glass substrate having a thickness of 300 μm is used as a sealing substrate, and an epoxy-based photocurable adhesive (LUX TRACK manufactured by Toagosei Co., Ltd.) is used as a sealing material. LC0629B) is applied, and this is overlaid on the cathode and brought into close contact with the transparent support substrate, irradiated with UV light from the glass substrate side, cured and sealed, and an illumination device as shown in FIGS. Can be formed.

  FIG. 5 shows a schematic diagram of a lighting device, and the organic EL element 101 of the present invention is covered with a glass cover 102 (in addition, the sealing operation with the glass cover is to bring the organic EL element 101 into contact with the atmosphere. And a glove box under a nitrogen atmosphere (in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more).

  FIG. 6 shows a cross-sectional view of the lighting device. In FIG. 6, 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.

Example 1
(Preparation of thin film TD-1 for solvent resistance evaluation)
After patterning on a substrate (NH-Techno Glass NA-45) formed by depositing 100 nm of ITO (indium tin oxide) on a 100 mm × 100 mm × 1.1 mm glass substrate as an anode, this ITO transparent electrode was provided. The transparent support substrate was ultrasonically cleaned with isopropyl alcohol, and UV ozone cleaning was performed 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 forming a film by spin coating, the film was dried at 200 ° C. for 1 hour to provide a PEDOT / PSS layer having a thickness of 30 nm.

On this thin film, a solution in which 30 mg of ET-2 was dissolved in 3 ml of dehydrated toluene was formed by spin coating under conditions of 1000 rpm and 30 seconds. The film was dried by heating at 120 ° C. for 1 hour, an electron transport layer having a thickness of 50 nm was provided, and a solvent resistance evaluation element TD-1 was formed. After measuring the remaining film rate by the method described later, the vacuum tank was decompressed to 4 × 10 ⁻⁴ Pa after being attached to a vacuum deposition apparatus. Subsequently, lithium fluoride 0.5nm and silver 110nm were vapor-deposited as a cathode, the cathode was formed, and the rectification ratio was measured using this.

(Preparation of thin film TD-2-20 for solvent resistance evaluation)
TD-2 to 20 are exactly the same as TD-1 of Example 1 except that the materials of the hole transport (HT) layer, the light emitting layer, and the electron transport (ET) layer are changed to those shown in Table 1. Was made. The evaluation results are shown in Table 1.

(Evaluation method)
The solvent resistance was evaluated as follows. The glass substrate on which the above-mentioned thin film for solvent resistance evaluation was formed was set on a spin coater (MS-A100, manufactured by Mikasa Co., Ltd.), and 0.2 ml of an evaluation solvent described later was added to the above TD1 to 20 using a glass pipette. It was dripped on the thin film. Spin coating was performed at 23 ° C. in a dry nitrogen gas atmosphere at 1000 rpm for 30 seconds, and the solvent resistance was evaluated by measuring the remaining film ratio before and after and the rectification ratio.

  As a solvent for evaluation, ultrapure water, methanol, n-propanol, isopropyl alcohol, n-decanol, hexane, 2,2,4-trimethylpentane (isooctane), n-decane, n-tetradecane, n-heptadecane, 1 , 5-hexadiene, 1,6-octadiene, hexanal, acetone, methyl ethyl ketone, cyclohexanone, formic acid, acetic acid, ethyl acetate, diethyl ether, dimethoxyethane, triethylamine, acetonitrile, toluene, pyridine were used. Moreover, the remaining film ratio and the rectification ratio were measured as follows.

<Residual film ratio>
The absorption spectrum was measured in the range of 330 nm to 600 nm using an ultraviolet-visible near-infrared spectrophotometer (Spectrophotometer U-3300 manufactured by Hitachi High-Technology Corporation) in a dry nitrogen gas atmosphere at 23 ° C. The maximum absorbance A0 before spin coating and the maximum absorbance A after spin coating were measured. A / A0 was calculated from the measured value, and this was defined as the remaining film ratio.

<Rectification ratio>
Under an atmosphere of dry nitrogen gas at 23 ° C., the voltage + V (forward bias) when the elements TD1 to 20 manufactured in Example 1 were energized with 20 μA was measured. Next, the amount of current −I (A) at −V that becomes a reverse bias was measured.

Log {20 × 10 ⁻⁶ / −I} was calculated from the measured value, and an integer value obtained by rounding off the first decimal place was used as the rectification ratio.

  In any case of TD-1 to TD-20, methanol, n-propanol, isopropyl alcohol, n-decanol, 1,5-hexadiene, 1,6-octadiene, hexanal, acetone, methyl ethyl ketone, cyclohexanone, formic acid, When acetic acid, ethyl acetate, diethyl ether, dimethoxyethane, triethylamine, acetonitrile, toluene, pyridine are used, the organic layer is visually damaged (total dissolution of the organic layer, partial dissolution, streak, turbidity, etc.) It was found that the change was not possible as a main component contained in the conductive paste used in the organic EL element.

  Table 1 shows the evaluation results with ultrapure water, hexane, 2,2,4-trimethylpentane (isooctane), n-decane, n-tetradecane, and n-heptadecane, which were not visually changed.

  As a result of visual primary evaluation, ultrapure water and saturated hydrocarbons (hexane, 2,2,4-trimethylpentane (isooctane), n-decane, n-tetradecane, n-heptadecane) are good solvents. it is obvious. In more detailed secondary evaluation, it is clear that there is a clear difference between the remaining film rate and the rectification ratio. Due to the use of ultrapure water, a large decrease in the rectification ratio is observed, which is thought to be due to water entering the light emitting layer and inhibiting EL emission. Therefore, it turned out that it is not preferable as a solvent contained in the electrically conductive paste which uses the organic EL of this invention. Further, from the results of Table 1, a very good rectification ratio was observed when 2,2,4-trimethylpentane was used among the saturated hydrocarbons, and it was contained in the conductive paste used in the organic EL device of the present invention. It is clear that a branched saturated hydrocarbon is a preferred embodiment as the organic solvent.

Example 2
(Production of Organic EL Element 1-1 for Solvent Resistance Evaluation)
Poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS, manufactured by Bayer, Baytron P Al 4083) diluted to 70% with pure water is formed into a film by spin coating at 3000 rpm for 30 seconds. Then, it was dried at 200 ° C. for 1 hour to provide a hole transport layer having a thickness of 30 nm. On this hole transport layer, a solution obtained by dissolving 5 mg of HT-11 (Hole Transport Polymer ADS-254 manufactured by American Die Source) in 1 ml of dehydrated chlorobenzene was spin coated under a condition of 1500 rpm for 30 seconds. Was formed. Heat-dried at 160 ° C. for 1 hour to provide a second hole transport layer having a thickness of 20 nm. On this second hole transport layer, a solution prepared by dissolving 40 mg of HS-11 and 2 mg of PD-1 in 2.5 ml of dehydrated mesitylene on this second hole transport layer was subjected to a condition of 1000 rpm for 30 seconds. The film was formed by spin coating. Heat-dried at 150 degreeC for 1 hour, and provided the light emitting layer with a film thickness of 40 nm.

On this light emitting layer, a solution of 30 mg of HS-42 dissolved in 6 ml of dehydrated 1,1,1-3,3,3-hexafluoroisopropanol was formed by spin coating at 1000 rpm for 30 seconds. . Heat-dried at 120 ° C. for 1 hour to provide an electron transport layer having a thickness of 20 nm. After performing solvent resistance evaluation with a saturated hydrocarbon solvent, which will be described later, it was attached to a vacuum deposition apparatus and the vacuum chamber was depressurized to 4 × 10 ⁻⁴ Pa. Subsequently, 0.5 nm of lithium fluoride and 110 nm of silver were vapor-deposited as a cathode, the cathode was formed, and the organic EL element 1-1 for solvent resistance evaluation was produced. In addition, since evaluation used one sheet for each solvent (number of evaluation solvents: 9 types), nine sets of exactly the same organic EL element 1-1 were produced.

(Preparation of organic EL elements 1-2 to 10 for evaluating solvent resistance)
The organic EL element 1-2 is exactly the same as the organic EL element 1-1 except that the materials of the hole transport (HT) layer, the light emitting layer, and the electron transport (ET) layer are changed to those shown in Table 2. Nine to 10 sets were prepared.

(Evaluation method)
Evaluation of the solvent resistance with respect to the saturated hydrocarbon solvent was performed as follows. The organic EL elements 1-1 to 1-10 formed up to the electron transport layer were set in a spin coater (MS-A100 manufactured by Mikasa Corporation), and 0.2 ml of the saturated hydrocarbon solvent shown in Table 3 was added to glass. It was dripped on the electron carrying layer using the pipette. Spin coating was performed at 23 ° C. in a dry nitrogen gas atmosphere at 1000 rpm for 30 seconds, and solvent resistance was evaluated by measuring the rectification ratio before and after the evaluation. The rectification ratio was measured in the same manner as in Example 1, and the values are shown in Table 3.

  Although the results are shown in Table 3, the superiority of the branched saturated hydrocarbon solvent is clear compared with the rectification ratio of the linear saturated hydrocarbon solvent, and it is contained in the conductive paste used in the organic EL device of the present invention. It is clear that a branched saturated hydrocarbon is a preferred embodiment as the organic solvent. Moreover, the tendency for the rectification ratio to improve as the number of branches increased was observed, and it was found that a large number of branches is desirable even in branched saturated hydrocarbons.

Example 3
<Preparation of organic EL element 2-1>
In exactly the same manner as in the organic EL device 1-4 produced in Example 2, after providing an electron transport layer, 0.1 ml of a silver nanoparticle paste dispersion (MDot-SL / decane dispersion manufactured by Mitsuboshi Belting Ltd.) After applying and patterning using a doctor blade (manufactured by Imoto Seisakusho Co., Ltd.), baking was performed at 130 ° C. for 20 minutes under nitrogen to form a silver cathode having a thickness of 110 nm, thereby manufacturing an organic EL element 2-1.

<Preparation of organic EL elements 2-2 to 2-10>
Organic EL devices 2-2 to 2-10 were produced in exactly the same manner except that the silver nanoparticle paste dispersion liquid used in the organic EL device 2-1 was changed to that shown in Table 4.

<Preparation of silver nanoparticle paste dispersion>
The silver nanoparticle paste dispersion used in the organic EL elements 2-3 to 2-9 was vacuum-dried 20 g of a silver nanoparticle paste dispersion (MDot-SL / heptane dispersion manufactured by Mitsuboshi Belting), and then 14 g Each solvent shown in Table 4 was added and re-dispersed in an ultrasonic bath for 15 minutes.

  However, when n-pentane (5 carbon atoms) is used, the solvent has a low boiling point (35-36 ° C.), a short circuit occurs due to silver deposition during coating and film formation, and the organic EL element 2-9 cannot be measured. Met. From this, it was found that a solvent having 5 or less carbon atoms is not suitable for the use of the present invention.

<< Evaluation of Organic EL Elements 2-1 to 2-10 >>
When evaluating the obtained organic EL elements 2-1 to 2-10, 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 photo-curing adhesive (Lux Track LC0629B manufactured by Toagosei Co., Ltd.) is applied as a sealing material, and this is placed on the cathode so as to be in close contact with the transparent support substrate and irradiated with UV light from the glass substrate side. Then, after curing and sealing, an illumination device as shown in FIGS. 5 and 6 was formed, and external extraction quantum efficiency, rectification ratio, and light emission lifetime were evaluated. Moreover, the conditions in each evaluation item are shown below. The measurement of the rectification ratio is the same as in the first embodiment.

《External extraction quantum efficiency》
For the organic EL element, 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. For the measurement, a spectral radiance meter CS-1000 (manufactured by Konica Minolta) was used.

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

  Table 4 shows the obtained results. The rectification ratio shows an actual measurement value, and the external extraction quantum efficiency and the light emission lifetime were evaluated relative to 100 of the organic EL element 2-10.

  As shown in Table 4, the external extraction quantum efficiency of the elements using the hydrocarbon solvent as the dispersion medium (organic EL elements 2-1 to 2-8) is the organic EL element 2-11 in which the cathode is formed by comparative vapor deposition. It is clear that the device performance is inferior to that of the present invention, and the superiority of the present invention that enables vacuum removal is high.

  In particular, when a branched saturated hydrocarbon of the organic EL elements 2-3 to 2-8 is used as a dispersion solvent, the external extraction quantum efficiency, the rectification ratio, and the element lifetime are improved, and the solvent is very inert to the organic film. I knew that there was. Furthermore, in the organic EL elements 2-6 and 2-7 using a saturated hydrocarbon solvent having a high number of branches, not only the external extraction quantum efficiency and the element lifetime, which are basic performances of the organic EL element, but also a high rectification ratio is obtained. It can be seen that this is a very suitable solvent for the wet process.

Example 4
<Preparation of organic EL elements 3-1 to 3-24>
Organic EL elements 3-1 to 3-24 were produced in the same manner except that the compounds used in the production of the organic EL element 2-1 of Example 3 were changed to those shown in Table 5.

  In addition, as a comparative element, organic EL elements 3-1S to 3-3 were manufactured in exactly the same manner except that the cathode forming material of the organic EL elements 3-1 to 3-24 was a FlowMetal aqueous dispersion manufactured by Bando Chemical Co., Ltd. -24S was produced.

<Evaluation of organic EL elements 3-1 to 3-24>
In the same manner as in Example 2, the external extraction quantum efficiency, the rectification ratio, and the light emission lifetime were evaluated. Note that the rectification ratio indicates an actual measurement value, and the external extraction quantum efficiency and the light emission lifetime are relative to those of the organic EL elements 3-1S to 3-24S which are comparison elements of the organic EL elements 3-1 to 3-24. Evaluation was performed. The results are shown in Table 6.

  As is clear from the results shown in Table 6, the cathode formed using the conductive paste containing the saturated hydrocarbon of the present invention as an organic solvent is better than the comparative aqueous conductive paste in any case. The external extraction efficiency, the light emission life, and the rectification ratio are clear, and the effect is clear. In particular, when a branched saturated hydrocarbon solvent is used, an advantage is shown in terms of effect, and further, an improvement in the rectification ratio is recognized as the number of branches increases, and it is intended for use in an organic EL element. In the present invention, it can be said to be the most preferable embodiment. Moreover, when the organic EL elements 3-10 and 3-11 are compared with other elements of the present invention, it can be seen that the effect of the element using phosphorescence emission is high. Compared to organic EL devices using fluorescence, this is very precise for controlling the light emitting layer (contamination from other layers to the light emitting layer, disturbance of the light emitting layer interface, morphology around the light emitting dopant, etc.) This is thought to be due to the need for security. The present invention can be said to be a very suitable method for an organic EL element utilizing phosphorescence emission. This is a difference between the organic EL element 3-24 of the comparative example in which no layer is provided between the light emitting layer and the cathode and the organic EL element 3-23 of the present invention in which a layer is provided between the light emitting layer and the cathode. I can explain.

Example 5
<Production of full-color display device>
(Blue light emitting organic EL device)
The organic EL element 3-5 described in Example 4 was used.

(Green light-emitting organic EL device)
A green light-emitting organic EL element 3-5G was produced in the same manner as in the organic EL element 3-5 produced in Example 4, except that ID-4 was changed to PD-1.

(Red light emitting organic EL device)
A red light-emitting organic EL element 3-5R was produced in the same manner as in the organic EL element 3-5 produced in Example 4, except that ID-4 was changed to PD-10.

  The red, green and blue light-emitting organic EL elements are juxtaposed on the same substrate to produce an active matrix type full-color display device having the form shown in FIG. 1, and FIG. 2 shows the display of the produced display device. Only the schematic diagram of part A is shown.

  That is, a wiring portion including a plurality of scanning lines 5 and data lines 6 on the same substrate, and a plurality of juxtaposed pixels 3 (light emission color is a red region pixel, a green region pixel, a blue region pixel, etc.) The scanning lines 5 and the plurality of data lines 6 in the wiring portion are each made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a lattice shape and are connected to the pixels 3 at the orthogonal positions ( Details are not shown).

  The plurality of pixels 3 are driven by an active matrix system provided with an organic EL element corresponding to each emission color, a switching transistor as an active element, and a driving transistor, and a scanning signal is applied from a scanning line 5. Then, an image data signal is received from the data line 6 and light is emitted according to the received image data.

  In this way, a full color display device was produced by appropriately juxtaposing the red, green, and blue pixels.

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

Example 6
《Preparation of white light emitting lighting device》
A white light-emitting organic EL element 3-5W was produced in the same manner as in the production of the organic EL element 3-5 of Example 4, except that ID-4 was changed to PD-1, PD-10, and ID-4.

  Similarly, the obtained organic EL element 3-5W was covered with a glass case to form 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.

DESCRIPTION OF SYMBOLS 1 Display 3 Pixel 5 Scan line 6 Data line 7 Power supply line 10 Organic EL element 11 Switching transistor 12 Drive transistor 13 Capacitor A Display part B Control part 107 Glass substrate with a transparent electrode 106 Organic EL layer 105 Cathode 102 Glass cover 108 Nitrogen gas 109 Water catcher

Claims (6)

In a phosphorescent organic electroluminescence device having an organic layer sandwiched between an anode and a cathode,
At least one layer of the organic layer is an electron transport layer containing a low molecular weight compound formed through a wet film forming step adjacent to the cathode, and
The cathode is formed through a film forming step by a wet method using a conductive paste containing an organic solvent that is a branched saturated hydrocarbon having 6 to 10 carbon atoms ,
The said low molecular weight compound is a compound which has a partial structure represented by following General formula (1), The organic electroluminescent element characterized by the above-mentioned.

In the formulas, A is -O -, - S- or -N _{(R 1)} - _represents, A 11 _{to A 18} are each a nitrogen atom or -C _{(R 2)} - represents a. R ₁ and R ₂ each represent a bond, a hydrogen atom, or a substituent. However, -C _{(R 2)} - if a plurality, each of -C _{(R 2)} - may be the same or different. ] The phosphorescent light-emitting layer adjacent to the electron transporting layer has at least a phosphorescent dopant and a light-emitting host, and the phosphorescent dopant is represented by the following general formula (2 The organic electroluminescence device according to claim 1, wherein the organic electroluminescence device is a compound represented by the formula:

[Wherein, Q ₁ represents a 5-membered or 6-membered aromatic ring. Ar represents an aromatic hydrocarbon group or an aromatic heterocyclic group, and R ₃ and R ₄ represent a hydrogen atom or a substituent. k represents an integer of 2 or 3, and has m secondary ligands L so as to satisfy the valence of iridium. ] The phosphorescence-emitting light-emitting layer contains a light emitting host with at least phosphorescent dopant, and, to claim 2, characterized by using the above formula (1) compound as a light emitting host The organic electroluminescent element of description. White organic electroluminescent device characterized by comprising the organic electroluminescence device according to any one of claims 1-3. A display device comprising the organic electroluminescence element according to any one of claims 1 to 3 or the white organic electroluminescence element according to claim 4 . An illuminating device comprising the organic electroluminescent element according to any one of claims 1 to 3 or the white organic electroluminescent element according to claim 4 .

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