JP2013171968A - Organic electroluminescent element, lighting system, display device, and method for manufacturing organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce drive voltage to improve luminous efficiency.SOLUTION: A display device (1) includes an organic EL element as a light emitting source. The organic EL element includes an anode, a cathode and a plurality of organic layers. The organic layers are disposed between the anode and the cathode, and include at least a light emitting layer, a hole transport layer and an electron transport layer. In the organic EL element, crystalline semiconductor nanoparticles having an average particle size of less than 10 nm are contained in at least one layer of the hole transport layer or the electron transport layer.

Description

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

An organic electroluminescence element (hereinafter also referred to as an organic EL element) has a structure in which a light emitting layer containing a light emitting compound is sandwiched between a cathode and an anode, and by applying an electric field, holes injected from the anode and The light-emitting element utilizes light emission (fluorescence / phosphorescence) when electrons injected from the cathode are recombined in the light-emitting layer to generate excitons (excitons) and the excitons are deactivated. Such an organic EL element is an all-solid-state element composed of an organic material film having a thickness of only a submicron between electrodes, and can emit light at a voltage of several volts to several tens of volts. Therefore, it is expected to be used for next-generation flat display and lighting.
In particular, organic EL devices that use phosphorescence emission are expected to be capable of realizing a luminous efficiency that is approximately four times as high as that of previous devices that use fluorescence emission, but a method for controlling the position of the emission center. In particular, how to stably perform light emission by recombination inside the light emitting layer is an important technical issue in capturing the power efficiency of the organic EL element.

In recent years, a multilayer stacked organic EL device having a hole transport layer (located on the anode side of the light emitting layer) and an electron transport layer (located on the cathode side of the light emitting layer) adjacent to the light emitting layer has been developed. Proposed. In such an organic EL device, the effect of facilitating injection and transport of charges to the light emitting layer in the hole transport layer and the electron transport layer, or the effect of maintaining the balance between the electron current and the hole current by blocking, the light energy It is trying to give effects such as suppressing the diffusion of excitons.
On the other hand, due to demands for an organic EL device with a large area, low cost, and high productivity, there is a great expectation for a wet method (also referred to as a wet process) as a method for forming an organic material film. Since the wet method can be formed at a low temperature as compared with the film formation in the vacuum process, it can reduce the damage of the lower organic layer and is also highly expected from the viewpoint of improving the luminous efficiency.
In response to these problems, specifically, for the purpose of improving the charge transport ability and charge injection ability, it is known that the hole injection transport layer contains metal oxide particles that can be formed by a wet method. However (see Patent Documents 1 and 2), the effect of improving the light emission efficiency is limited, and it is still not sufficient.

JP 2008-41894 A JP 2010-272892 A

  Accordingly, a main object of the present invention is to provide an organic EL element capable of reducing driving voltage and improving luminous efficiency, and another object of the present invention is an illumination device using such an organic EL element. Another object is to provide a display device and a manufacturing method thereof.

In order to solve the above problems, according to the present invention,
In an organic electroluminescent device comprising an anode, a cathode and a plurality of organic layers, wherein the organic layer is disposed between the anode and the cathode, and has at least a light emitting layer, a hole transport layer and an electron transport layer,
At least one of the hole transport layer or the electron transport layer contains crystalline semiconductor nanoparticles having an average particle diameter of less than 10 nm.

  According to the present invention, the drive voltage can be reduced and the light emission efficiency can be improved.

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 the display part of the display apparatus of FIG. It is a schematic diagram of the pixel of the display part of FIG. 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 the illuminating device of FIG.

Hereinafter, although the preferable form for implementing this invention is demonstrated in detail, this invention is not limited to these.
An organic EL device according to a preferred embodiment of the present invention includes an anode, a cathode, and a plurality of organic layers, the organic layer is disposed between the anode and the cathode, and at least a light emitting layer, a hole transport layer, and an electron transport layer have. In such an organic EL element, crystalline semiconductor nanoparticles having an average particle diameter of less than 10 nm are contained in at least one of a hole transport layer or an electron transport layer described later.
Hereinafter, first, crystalline semiconductor nanoparticles and a manufacturing method thereof will be described, and then a layer configuration of the organic EL element, description of each layer, a manufacturing method of the organic EL element, and the like will be described.

《Crystalline semiconductor nanoparticles》
The crystalline semiconductor nanoparticles according to the present invention are mainly characterized in that the average particle diameter is less than 10 nm and the crystallinity is high. The semiconductor nanoparticles are preferably made of a metal oxide, nitride, sulfide or halide, more preferably a metal oxide or metal halide, and most preferably a metal oxide.
Examples of metal atoms include group 3-5 metals (scandium, yttrium, titanium, zirconium, hafnium, vanadium, niobium), copper, cerium, indium, tin and gallium, aluminum, zinc, molybdenum, tungsten, rhenium, and the like. It is done.
Metal oxide nanoparticle materials include scandium oxide, yttrium oxide, titanium oxide, zirconium oxide, cerium oxide, hafnium oxide, vanadium oxide, niobium oxide, copper oxide, indium oxide, tin oxide, gallium oxide, aluminum oxide, zinc oxide Examples include molybdenum oxide, tungsten oxide, and rhenium oxide.

The semiconductor nanoparticles of the present invention can be contained in at least one of the electron transport layer and the hole transport layer among the constituent layers of the organic EL device described later, and are particularly preferably contained in the electron transport layer. Most preferably, it is contained in both the hole transport layer and the hole transport layer.
When the particles are included in the electron transport layer, the energy level of the conduction band of the semiconductor nanoparticles of the present invention is the LUMO level of the electron transport material constituting the electron transport layer, and the LUMO level of the host compound of the light emitting layer. From this viewpoint, scandium oxide, yttrium oxide, titanium oxide, zirconium oxide, cerium oxide, hafnium oxide, vanadium oxide, and niobium oxide are preferable, and yttrium oxide, zirconium oxide, and cerium oxide are more preferable.
When the particles are contained in the hole transport layer, the energy level of the valence band of the semiconductor nanoparticles of the present invention is the HOMO level of the hole transport material constituting the hole transport layer, and the host compound of the light emitting layer From this point of view, copper oxide, indium oxide, tin oxide, gallium oxide, aluminum oxide, zinc oxide molybdenum oxide, tungsten oxide, and rhenium oxide are preferable, and molybdenum oxide, tungsten oxide, oxide Rhenium is more preferred.

The particle diameter (average particle diameter) of the semiconductor nanoparticles of the present invention is less than 10 nm, and the preferable particle diameter is 0.5 nm to 9.9 nm, more preferably 1.0 nm to 9.0 nm, and particularly preferably. Is 3.0 nm to 8.0 nm. When the particle diameter is 10 nm or more, it becomes difficult to form a film having a uniform thickness, and the charge transfer concentrates on the thin film thickness part, and the part is quickly destroyed and becomes a black spot, causing deterioration of the lifetime of the organic EL element. .
As a method for measuring the average particle diameter, a known method can be used.
For example, the semiconductor nanoparticles are observed with a transmission electron microscope (TEM), and the number average particle size of the particle size distribution is determined therefrom, and the particle size distribution of the semiconductor nanoparticles is measured by a dynamic light scattering method. Examples of the method include obtaining the number average particle diameter.

The crystallinity of the semiconductor nanoparticles of the present invention is determined by identifying the crystal structure by powder X-ray diffraction (XRD) and calculating the crystallinity. “Crystallinity” in crystalline semiconductor nanoparticles means that the crystallinity is 50% or more, preferably 60% or more, and more preferably 70% or more. It is. The degree of crystallinity is calculated from the XRD measurement results by fitting the diffraction line part (peak) due to the crystalline substance and the scattered light part (halo) due to the amorphous substance, obtaining the integrated intensity of each component, and calculating by the following formula (A). The
X = Ic / (Ic + Ia) × 100 (A)
In formula (A), “X” represents the crystallinity, “Ic” represents the integrated intensity of the peak, and “Ia” represents the integrated intensity of the halo.
By improving the crystallinity, it is possible to obtain the effect of reducing the driving voltage, improving the light emission efficiency, and extending the lifetime. This mechanism is not clear, but is considered as follows. That is, it is generally considered that charge transfer inside the semiconductor is not good when the crystallinity is high, but by making the average particle diameter less than 10 nm, the surface area of the particle is dramatically increased, and charge transfer on the particle surface is prevented. Rather, the higher crystallinity is considered to be due to the formation of a regular and efficient conduction path on the particle surface and the improved charge transfer.

In the present invention, a more preferable result is obtained by modifying the particle surface of the semiconductor nanoparticles with an organic substance. This is presumably because the dispersion stability in the coating liquid during the production of the semiconductor nanoparticles is improved, and the nanoparticles can be uniformly distributed in the layer.
As the organic substance used for the modification, a compound having a group capable of chemically bonding to the particle surface can be used. For example, a bond via an N atom including an ether bond, an ester bond, an amino bond or an amide bond, or an S atom. Bond, P atom bond, metal-C- bond, metal-C = bond and metal- (C = O)-bond, phosphate ester bond, phosphite bond, phosphonate bond, Those that allow chemical bonds such as phosphinic acid bonds, phosphinic acid bonds, and phosphinic acid bonds to be formed.
Examples of the organic molecular residue of the organic substance used for the modification include a hydrocarbon group, and may be a linear or branched alkyl group that may be substituted, a linear or branched chain that may be substituted. An alkenyl group, an optionally substituted linear or branched alkynyl group, an optionally substituted saturated or unsaturated cyclic alkyl group, an optionally substituted aryl group, an optionally substituted Examples thereof include an aralkyl group and an optionally substituted saturated or unsaturated heterocyclic group.
In the present invention, the organic molecule residue part is most preferably one having a structure of a material having an electron transport property and a hole transport property, which will be described later, as a residue in order to facilitate the charge transfer smoothly. , Triphenylamine, fluorene, biphenyl, pyrene, anthracene, carbazole, azacarbazole, phenylpyridine, trithiophene, phenyloxadiazole, phenyltriazole, benzimidazole, phenyltriazine, benzodiathiazine, phenylquinoxaline, phenylenevinylene, phenyl Examples include siloles and combinations of these structures, and among them, azacarbazole and phenylpyridine are preferable.

The hydrocarbon as the organic molecular residue is not particularly limited, and those having 1 or 2 carbons can be used. From the viewpoint of taking advantage of the present invention, the number of carbons is 3 or more. Those which are long-chain hydrocarbons having a chain are preferred, and examples thereof include linear or branched chains having 3 to 20 carbon atoms or cyclic hydrocarbons. The hydrocarbon is an optionally substituted linear or branched alkyl group, an optionally substituted cyclic alkyl group, an optionally substituted aryl group, an optionally substituted aralkyl group, a substituted And a saturated or unsaturated heterocyclic group which may be used. Examples of the substituent include carboxy group, cyano group, nitro group, halogen, ester group, amide group, ketone group, formyl group, ether group, hydroxyl group, amino group, sulfonyl group, -O-, -NH-,- S- etc. are mentioned.
Examples of organic substances used in the modification of the present invention include alcohols, aldehydes, ketones, carboxylic acids, esters, amines, thiols, amides, oximes, phosgene, enamines, amino acids, peptides, and sugars. , Phosphoric acid ester, phosphorous acid ester, phosphonic acid ester, phosphonic acid ester, phosphinic acid ester, phosphinic acid ester, phosphine, phosphine oxide and the like.
Typical organic substances include, for example, pentanol, pentanal, pentanoic acid, pentanamide, pentanethiol, hexanol, hexanal, hexanoic acid, hexanamide, hexanethiol, heptanol, heptanal, heptanoic acid, heptanamide, heptanethiol, octanol , Octanal, octanoic acid, octatanamide, octanethiol, decanol, decanal, decanoic acid, decanamide, decanthiol, thiourea, selenourea and the like.

  The addition amount of the semiconductor nanoparticles of the present invention is preferably 5 to 90% by mass, more preferably 10 to 70% by mass, with respect to 100 parts by mass of all the constituent materials of the layer to which the particles are added. Most preferably, it is 15-50 mass%.

<< Method for producing crystalline semiconductor nanoparticles >>
The semiconductor nanoparticles of the present invention can be produced by hydrothermal reaction of the metal oxides, nitrides, sulfides or halides described above using subcritical or supercritical water as a medium.
The “subcritical or supercritical water” specifically refers to a water state at a temperature of 350 to 450 ° C. and a pressure of 20 to 40 MPa, preferably a temperature of 380 to 400 ° C. and a pressure of 25 ~ 30 MPa. In particular, the hydrothermal reaction condition at a temperature of 380 ° C. or higher is preferable because the hydrothermal reaction is accelerated as the density and dielectric constant of water decrease. The reaction medium contains water as a main component, but other media such as an aqueous mixed solvent including an organic solvent and a polar solvent can be used as appropriate.
As the reaction vessel used in the reaction of the present invention, an appropriate reaction vessel can be used as long as it can withstand a predetermined temperature and pressure.
Although the reaction can be carried out either batchwise or flow-wise, it is preferable to use a flow-type reaction device in that the mixing of the reaction liquid, reaction temperature, and time can be controlled more accurately, and the reaction time at that time is 1.0-6. It is preferably performed in 0 seconds.
In addition, in order to modify the surface of the semiconductor nanoparticles of the present invention with an organic substance, the semiconductor nanoparticles, a method in which the organic substance and a solvent are mixed and then heated are modified, or the organic substance is mixed with the raw material liquid during the hydrothermal reaction. Thus, there is a method of modifying semiconductor nanoparticles at the same time as manufacturing them.

<< Constituent layers of organic EL elements >>
The constituent layers of the organic EL element of the present invention will be described. In this invention, although the preferable specific example of the layer structure of an organic EL element is shown below, this invention is not limited to these.
(I) Anode / hole transport layer / light emitting layer / electron transport layer / cathode (ii) Anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode (iii) Anode / hole transport layer / Light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode (iv) anode / anode buffer layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode ( v) Anode / hole transport layer / anode buffer layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode (vi) Anode / anode buffer layer / hole transport layer / light emitting layer / electron transport layer / Cathode buffer layer / cathode When a plurality of light emitting layers are included, a non-light emitting intermediate layer may be provided between the light emitting layers. In addition, among the above layer structures, an organic layer including a light emitting layer excluding an anode and a cathode can be used as one light emitting unit, and a plurality of light emitting units can be stacked. The plurality of stacked light emitting units may have a non-light emitting intermediate layer between the light emitting units, and the intermediate layer may further include a charge generation layer.
The organic EL element of the present invention is preferably a white light emitting layer, and is preferably a lighting device using these.

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

<Light emitting layer>
The light emitting layer according to the present invention is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer, and the light emitting portion is in the layer of the light emitting layer. May be the interface between the light emitting layer and the adjacent layer.
The total film thickness of the light emitting layer is not particularly limited, but from the viewpoint of improving the uniformity of the film, preventing unnecessary application of high voltage during light emission, and improving the stability of the emission color with respect to the drive current. It is preferable to adjust in the range of 2 nm to 500 nm, more preferably in the range of 2 to 200 nm, and particularly preferably in the range of 5 to 100 nm.
For the production of the light emitting layer, a light emitting dopant or host compound described later is used, for example, a vacuum deposition method, a wet method (also referred to as a wet process, for example, 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, an LB method (a Langmuir-Blodgett method and the like can be used)) and the like can be formed.
The light emitting layer of the organic EL device of the present invention contains a light emitting dopant (phosphorescent dopant (also referred to as phosphorescent dopant, also referred to as phosphorescent dopant group) or fluorescent dopant) compound and a light emitting host compound. .

(1) Luminescent dopant compound As the luminescent dopant, a fluorescent dopant (also referred to as a fluorescent compound) or a phosphorescent dopant (also referred to as a phosphorescent emitter, a phosphorescent compound, a phosphorescent compound, or the like) is used. it can.
The phosphorescent dopant compound is a compound in which light emission from an excited triplet is observed. Specifically, the phosphorescent dopant compound is a compound that emits phosphorescence at room temperature (25 ° C.). Although defined as being a compound of 01 or more, a preferable phosphorescence quantum yield is 0.1 or more.
The phosphorescence quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of Experimental Chemistry Course 4 of the 4th edition.
Although the phosphorescence quantum yield in a solution can be measured using various solvents, the phosphorescence dopant according to the present invention achieves the phosphorescence quantum yield (0.01 or more) in any solvent. For example, WO 00/70655, JP 2002-280178, JP 2001-181616, JP 2002-280179, JP 2001-181617, JP 2002-280180. JP, JP 2001-247859, JP 2002-299060, JP 2001-313178, JP 2002-302671, JP 2001-345183, JP 2002-324679. WO 02/15645, JP 2002-332291 A, JP 2002-50 No. 84, JP-A No. 2002-332292, JP-A No. 2002-83684, JP-T No. 2002-540572, JP-A No. 2002-117978, JP-A No. 2002-338588, JP-A No. 2002-170684 JP, 2002-352960, WO 01/93642, JP 2002-50483, JP 2002-1000047, JP 2002-173684, JP 2002-359082, JP 2002-175844 A, JP 2002-363552 A, JP 2002-184582 A, JP 2003-7469 A, JP 2002-525808 A, JP 2003-7471 A, Special Table. JP 2002-525833 A, JP 2003-3136 A JP, JP 2002-226495, JP 2002-234894, JP 2002-235076, JP 2002-241751, JP 2001-319779, JP 2001-319780. JP-A 2002-62824, JP-A 2002-1000047, JP-A 2002-203679, JP-A 2002-343572, JP-A 2002-203678, and the like are used. be able to.
As fluorescent dopants, coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, perylene dyes, stilbene dyes , Polythiophene dyes, rare earth complex phosphors, and the like, and compounds having a high fluorescence quantum yield such as laser dyes.
The light emitting dopant may be used in combination of a plurality of types of compounds, or may be a combination of phosphorescent dopants having different structures or a combination of a phosphorescent dopant and a fluorescent dopant.

(2) Luminescent host compound (also referred to as luminescent host)
The host compound of the present invention has a mass ratio in the layer of 20% or more among the compounds contained in the light emitting layer, and has a phosphorescence quantum yield of phosphorescence of 0 at room temperature (25 ° C.). .1 is defined as a compound having a phosphorescence quantum yield of less than 0.01. Moreover, it is preferable that the mass ratio in the layer is 20% or more among the compounds contained in the light emitting layer.
There is no restriction | limiting in particular as a light emission host which can be used for this invention, The compound conventionally used with an organic EL element can be used.
Typically, a carbazole derivative, a triarylamine derivative, an aromatic derivative, a nitrogen-containing heterocyclic compound, a thiophene derivative, a furan derivative, an oligoarylene compound or the like having a basic skeleton, or a carboline derivative or a diazacarbazole derivative (here And the diazacarbazole derivative represents one in which at least one carbon atom of the hydrocarbon ring constituting the carboline ring of the carboline derivative is substituted with a nitrogen atom.
The light emitting host that can be used in the present invention is preferably a compound that has a hole transporting ability and an electron transporting ability, prevents the emission of light from becoming longer, and has a high Tg (glass transition temperature). The light emitting host more preferably has a Tg of 100 ° C. or higher.
By using a plurality of types of light-emitting hosts, the movement of charges can be adjusted, and the organic EL element can be made highly efficient.
In addition, the light emitting host used in the present invention may be a low molecular compound, a high molecular compound having a repeating unit, or a low molecular compound having a polymerizable group such as a vinyl group or an epoxy group (polymerizable light emitting host). Of course, one or more of such compounds may be used.

Specific examples of the known light-emitting host 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.

<< Injection layer: hole injection layer (anode buffer layer), electron injection layer (cathode buffer layer) >>
The injection layer is provided as necessary, and there are an electron injection layer and a hole injection layer, and as described above, it exists between the anode and the light emitting layer or the hole transport layer and between the cathode and the light emitting layer or the electron transport layer. May be.
An injection layer is a layer provided between an electrode and an organic layer in order to reduce drive voltage and improve light emission luminance. “Organic EL element and its forefront of industrialization (issued by NTT Corporation on November 30, 1998) 2), Chapter 2, “Electrode Materials” (pages 123 to 166), 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. Representative phthalocyanine buffer layer, oxide buffer layer typified by vanadium oxide, amorphous carbon buffer layer, polymer buffer layer using conductive polymer such as polyaniline (emeraldine) or polythiophene, tris (2-phenylpyridine) ) Orthometalated complex layers represented by iridium complexes and the like.
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, alkali metal compound buffer layer typified by lithium fluoride, sodium fluoride and potassium fluoride, alkaline earth metal compound buffer layer typified by magnesium fluoride, and aluminum oxide And an oxide buffer layer. 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 500 nm although it depends on the material.
In addition, the materials used for the anode buffer layer and the cathode buffer layer can be used in combination with other materials. For example, the materials can be mixed in the hole transport layer or the electron transport layer.

《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. In the present invention, a conventionally known hole transport material can be used. 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. It is particularly preferable to use 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, as well as 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-4-308 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 88 are linked in a starburst type ( MTDATA) and the like.
Furthermore, the following compound structures can be used as aromatic oligoamines.
Aromatic tertiary amine compounds and styrylamine compounds (US Pat. No. 4,127,412, JP-A-53-27033, 54-58445, 54-149634, 54- 64299, 55-79450, 55-144250, 56-119132, 61-295558, 61-98353, 63-295695), pyridine derivatives ( JP-A-2003-282270), porphyrin compounds (see JP-A-63-295965, etc.), aniline-based copolymers (see JP-A-2-282263, WO08 / 129947, etc.), phenylenediamine Derivatives (US Pat. No. 3,615,404, Japanese Patent Publication No. 51-10105, No. 4) -3712, JP same 47-25336, JP-Sho 54-53435, JP same 54-110536 and JP reference like JP same 54-119925).
Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.
In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material.
In addition, cyclometalated complexes and orthometalated complexes represented by copper phthalocyanine, tris (2-phenylpyridine) iridium complex, and the like can also be used as the hole transport material.
JP-A-11-251067, J. Org. Huang et. al. , Applied Physics Letters, 80 (2002), p. 139), so-called p-type hole transport materials 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 is formed by thinning the hole transport material by a known method such as a vacuum deposition method or a wet method (including spin coating method, casting method, ink jet method, printing method, LB method). Preferably, a wet method is used.
Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, about 5 nm-500 nm are preferable, More preferably, it is 5-200 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.
Alternatively, a hole transport layer having a high p property doped with impurities can be used. Examples thereof include JP-A-4-297076, JP-A-2000-196140, 2001-102175, J. Pat. Appl. Phys. 95, 5773 (2004), and the like.
In the present invention, it is preferable to use a hole transport layer having such a high p property because a device with lower power consumption can be produced.

《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer.
The electron transport layer can be provided with a single layer or a plurality of layers.
An electron transport material (including a hole blocking material and an electron injection material) used for the electron transport layer only needs to have a function of transmitting electrons injected from the cathode to the light emitting layer. Can be selected from any conventionally known compounds and used alone or in combination.
Examples of conventionally known materials used for the electron transport layer (hereinafter referred to as electron transport materials) include heterocyclic tetracarboxylic acid anhydrides such as nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, naphthalene perylene, And azacarbazole derivatives including carbodiimide, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives, carboline derivatives, and the like.
Here, the azacarbazole derivative refers to one in which one or more carbon atoms constituting the carbazole ring are replaced with nitrogen atoms.
Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, or a quinoxaline derivative having a quinoxaline ring known as an electron-withdrawing group can also be used as an electron transport material.
It is also possible to use a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain.
In addition, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), and the like, and the central metals of these metal complexes are In, Mg, Metal complexes replaced with Cu, Ca, Sn, Ga or Pb can also be used as the electron transport material.
In addition, metal-free or metal phthalocyanine, or those having the terminal substituted with an alkyl group or a sulfonic acid group can also be used as the electron transport material.
Further, similarly to the hole injection layer and the hole transport layer, inorganic semiconductors such as n-type-Si and n-type-SiC can also be used as the electron transport material.

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

  In the present invention, a more preferable result can be obtained by using a pyridine derivative represented by the following general formula (1). Although the mechanism of the effect is unknown, it is thought that the interaction between the pyridine ring and the surface of the semiconductor nanoparticle of the present invention has increased, and electron hopping can be performed more easily, and the electron transport efficiency has been improved.

In general formula (1), “R _{1 to} R ₅ ” represent a hydrogen atom or a substituent, and the substituents may be bonded to each other to form a ring.

  Although the specific example of a compound (electron transport material) represented by General formula (1) is given, this invention is not limited to these.

It is preferable that the addition amount of the compound represented by General formula (1) of this invention is 5-90 mass% with respect to 100 mass parts of all the structural substances of the layer which adds the said compound, and 10-70 mass%. Is more preferable, and 10 to 50% by mass is most preferable.
Although there is no restriction | limiting in particular about the film thickness of an electron carrying layer, Usually, about 5-500 nm, Preferably it is 80-300 nm from a viewpoint of utilizing the effect of this invention to the maximum and suppressing the influence of the plasmon effect on a metal surface. is there. The electron transport layer may have a single layer structure composed of one or more of the above materials, or may have a stacked structure in which a plurality of layers are stacked.
Further, an electron transport layer having a high n property doped with impurities can also be used. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

<Blocking layer: hole blocking layer, electron blocking layer>
The blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film as described above. For example, it is described in JP-A Nos. 11-204258, 11-204359, and “Organic EL elements and their forefront of industrialization” (issued by NTT, Inc. on November 30, 1998). There is a hole blocking (hole blocking) layer.
The hole blocking layer has a function of an electron transport layer in a broad sense, and is made of a hole blocking material that has a function of transporting electrons and has a remarkably small ability to transport holes. The probability of recombination of electrons and holes can be improved by blocking.
Moreover, the structure of the above-mentioned electron carrying layer can be used as a hole-blocking layer concerning this invention as needed.
The hole blocking layer of the organic EL device of the present invention is preferably provided adjacent to the light emitting layer.
The hole blocking layer contains carbazole derivatives, azacarbazole derivatives (where azacarbazole derivatives are those in which one or more carbon atoms constituting the carbazole ring are replaced by nitrogen atoms), pyridine derivatives, and the like. It is preferable to contain a nitrogen 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 electrons at the HOMO (highest occupied orbital) level of the compound to the vacuum level, and can be determined by, for example, the following method.
(1) Keyword using Gaussian 98 (Gaussian 98, Revision A.11.4, MJ Frisch, et al., Gaussian, Inc., Pittsburgh PA, 2002), which is molecular orbital calculation software manufactured by Gaussian, USA. As a value (eV unit converted value) calculated by performing structure 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 above-mentioned hole transport layer can be used as an electron blocking layer as needed.
The film thickness of the hole blocking layer and the electron blocking layer according to the present invention is preferably 3 to 100 nm, and more preferably 3 to 30 nm.

"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, it is usually selected in the range of 10 to 1000 nm, preferably 10 to 200 nm.

"cathode"
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used.
Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like.
Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred.
The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. Further, the sheet resistance as a cathode is preferably several hundred Ω / □ or less, and the film thickness is usually 10 to 5 μm, preferably 50 to 200 nm.
In order to transmit the emitted light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the light emission luminance is improved, which is convenient.
Moreover, after producing the said metal by the film thickness of 1 nm-20 nm to a cathode, the transparent or semi-transparent cathode can be produced by producing the electroconductive transparent material quoted by description of the anode on it, By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.

《Support substrate》
As a support substrate (hereinafter also referred to as a substrate, substrate, substrate, support, etc.) that can be used in the organic EL device of the present invention, there is no particular limitation on the type of glass, plastic, etc., and it is transparent. May be opaque. When extracting light from the support substrate side, the support substrate is preferably transparent.
Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable support substrate is a resin film capable of giving flexibility to the organic EL element.
Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, cellulose acetate propionate ( CAP), cellulose esters such as cellulose acetate phthalate, cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones Cycloolefin resins such as polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylate, Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Can be mentioned.
On the surface of the resin film, an inorganic film, an organic film, or a hybrid film of both may be formed. Water vapor permeability (25 ± 0.5 ° C.) measured by a method according to JIS K 7129-1992. , Relative humidity (90 ± 2)% RH) is preferably 0.01 g / (m ² · 24 h) or less, and further, oxygen measured by a method according to JIS K 7126-1987. A high barrier film having a permeability of 10 ⁻³ ml / (m ² · 24 h · MPa) or less and a water vapor permeability of 10 ⁻⁵ g / (m ² · 24 h) or less is preferable.
As a material for forming the barrier film, any material may be used as long as it has a function of suppressing entry of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like can be used.
Further, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and organic material layers. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times.
The method for forming the barrier film is not particularly limited. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma polymerization A plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.
Examples of the opaque support substrate include metal plates such as aluminum and stainless steel, films, opaque resin substrates, and ceramic substrates.
The external extraction efficiency at room temperature of light emission of the organic EL device of the present invention is preferably 1% or more, more preferably 5% or more.
Here, the external extraction quantum efficiency (%) = the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element × 100.
In addition, a hue improvement filter such as a color filter may be used in combination, or a color conversion filter that converts the emission color from the organic EL element into multiple colors using a phosphor. In the case of using a color conversion filter, the λmax of light emission of the organic EL element is preferably 480 nm or less.

<< Method for Manufacturing Organic EL Element >>
As an example of a method for producing an organic EL device, a device comprising an anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer (electron injection layer) / cathode Will be described.
First, a desired electrode material, for example, a thin film made of an anode material is formed on a suitable substrate so as to have a thickness of 1 μm or less, preferably 10 to 200 nm, and an anode is manufactured.

Next, thin films containing organic compounds such as a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, and a cathode buffer layer, which are element materials, are sequentially formed thereon.
These organic compound layers may be formed by a vapor deposition method or a wet method.
In the present embodiment, the crystalline semiconductor nanoparticles are included in at least one layer of the hole transport layer and the electron transport layer.
(I) a step of producing (preparing) crystalline semiconductor nanoparticles by hydrothermal reaction using water in a subcritical or supercritical state as a medium;
(Ii) a step of incorporating the crystalline semiconductor nanoparticles after production into at least one layer of a hole transport layer or an electron transport layer;
Each process is executed.
In particular, in the treatment (ii), a hole transport layer or an electron transport layer having crystalline semiconductor nanoparticles is formed by a wet method, and the crystalline semiconductor nanoparticles are mixed in a solution or a solvent constituting the layer, Such a mixture is formed into a film.

Wet methods include spin coating, casting, die coating, blade coating, roll coating, ink jet, printing, spray coating, curtain coating, and LB methods, but precise thin films 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, and a spray coating method is preferable.
Different film forming methods may be applied for each layer.
Examples of the liquid medium for dissolving or dispersing the organic EL material according to the present invention include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene, xylene, and mesitylene. Aromatic hydrocarbons such as cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, and organic solvents such as DMF and DMSO can be used.
Moreover, as a dispersion method, it can disperse | distribute by dispersion methods, such as an ultrasonic wave, high shear force dispersion | distribution, and media dispersion | distribution.

  After these organic compound layers are formed, a thin film made of a cathode material is formed on the organic compound layer so as to have a thickness of 1 μm or less, preferably in the range of 50 to 200 nm, and a cathode is provided to obtain a desired organic EL device. can get.

Further, the order can be reversed, and the cathode, cathode buffer layer, electron transport layer, hole blocking layer, light emitting layer, hole transport layer, hole injection layer, and 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 preferable to perform the work in a dry inert gas atmosphere.

<Sealing>
As a sealing means used for this invention, the method of adhere | attaching a sealing member, an electrode, and a support substrate with an adhesive agent can be mentioned, for example.
As a sealing member, it should just be arrange | positioned so that the display area | region of an organic EL element may be covered, and concave plate shape or flat plate shape may be sufficient. Further, transparency and electrical insulation are not particularly limited.
Specific examples include a glass plate, a polymer plate / film, and a metal plate / film. Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz.
Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone. Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum.
In the present invention, a polymer film and a metal film can be preferably used because the element can be thinned.
Furthermore, the polymer film has an oxygen permeability of 1 × 10 ⁻³ ml / (m ² · 24 h · MPa) or less measured by a method according to JIS K 7126-1987, and a method according to JIS K 7129-1992. It is preferable that the water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) measured in (1) is 1 × 10 ⁻³ g / (m ² · 24 h) or less.
For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.

Specific examples of the adhesive include photocuring and thermosetting adhesives having reactive vinyl groups such as acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. be able to. Moreover, heat | fever and chemical curing types (two-component mixing), such as an epoxy type, can be mentioned.
Furthermore, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.
In addition, since an organic EL element may deteriorate by heat processing, what can be adhesive-hardened from room temperature to 80 degreeC is preferable. A desiccant may be dispersed in the adhesive.
Application | coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print like screen printing.
In addition, it is also preferable that the electrode and the organic layer are coated on the outside of the electrode facing the support substrate with the organic layer interposed therebetween, and an inorganic or organic layer is formed in contact with the support substrate to form a sealing film. .
In this case, the material for forming the film may be any material that has a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can.
Furthermore, 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, ion plating, plasma polymerization, atmospheric pressure plasma A combination 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, etc.) and the like, and sulfates, metal halides and perchloric acids are preferably anhydrous salts.

《Protective film, protective plate》
In order to increase the mechanical strength of the element, a protective film or a protective plate may be provided on the outer side of the sealing film on the side facing the support substrate with the organic layer interposed therebetween or on the sealing film. In particular, when the sealing is performed by the sealing film, the mechanical strength is not necessarily high, and thus it is preferable to provide such a protective film and a protective plate.
As a material that can be used for this, the same glass plate, polymer plate / film, metal plate / film, etc. used for the sealing can be used, 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 of improving efficiency by providing a light collecting property to a substrate (Japanese Patent Laid-Open No. 63-314795), a method of forming a reflective surface on a side surface of an element (Japanese Patent Laid-Open No. 1-220394), and light emission from a substrate A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the bodies (Japanese Patent Laid-Open No. 62-172691), a flat having a lower refractive index between the substrate and the light emitter than the substrate A method of introducing a layer (Japanese Patent Laid-Open No. 2001-202827), a method of forming a diffraction grating between any one of a substrate, a transparent electrode layer and a light emitting layer (including between the substrate and the outside) (Japanese Patent Laid-Open No. 11-283951) Gazette).
In the present invention, these methods can be used in combination with the organic EL device of the present invention. However, a method of introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter, or a substrate, transparent A method of forming a diffraction grating between any layers of the electrode layer and the light emitting layer (including between the substrate and the outside) can be suitably used.
In the present invention, by combining these means, it is possible to obtain an element having higher luminance or durability.

When a medium having a low refractive index is formed between the transparent electrode and the transparent substrate with a thickness longer than the wavelength of light, the light extracted from the transparent electrode has a higher extraction efficiency to the outside as the refractive index of the medium is lower.
Examples of the low refractive index layer include aerogel, porous silica, magnesium fluoride, and a fluorine-based polymer. Since the refractive index of the transparent substrate is generally about 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less. Further, it is preferably 1.35 or less.
The thickness of the low refractive index medium is preferably at least twice the wavelength in the medium. This is because the effect of the low refractive index layer is diminished when the thickness of the low refractive index medium is about the wavelength of light and the electromagnetic wave that has exuded by evanescent enters the substrate.
The method of introducing a diffraction grating into an interface or any medium that causes total reflection is characterized by a high effect of improving light extraction efficiency. This method uses the property that the diffraction grating can change the direction of light to a specific direction different from refraction by so-called Bragg diffraction such as first-order diffraction and second-order diffraction. Light that cannot be emitted due to total internal reflection between layers is diffracted by introducing a diffraction grating in any layer or medium (in a transparent substrate or transparent electrode), and the light is removed. I want to take it out.
The introduced diffraction grating preferably has a two-dimensional periodic refractive index. This is because light emitted from the light-emitting layer is randomly generated in all directions, so in a general one-dimensional diffraction grating having a periodic refractive index distribution only in a certain direction, only light traveling in a specific direction is diffracted. Therefore, the light extraction efficiency does not increase so much.
However, by making the refractive index distribution a two-dimensional distribution, light traveling in all directions is diffracted, and light extraction efficiency is increased.
As described above, the position where the diffraction grating is introduced may be in any of the layers or in the medium (in the transparent substrate or in the transparent electrode), but is preferably in the vicinity of the organic light emitting layer where light is generated.
At this time, the period of the diffraction grating is preferably about 1/2 to 3 times the wavelength of light in the medium.
The arrangement of the diffraction grating is preferably two-dimensionally repeated such as a square lattice, a triangular lattice, or a honeycomb lattice.

<Condenser sheet>
The organic EL device of the present invention is processed on the light extraction side of the substrate so as to provide, for example, a microlens array structure, or combined with a so-called condensing sheet, for example, with respect to a specific direction, for example, the device light emitting surface. By condensing in the front direction, the luminance in a specific direction can be increased.
As an example of the microlens array, quadrangular pyramids having a side of 30 μm and an apex angle of 90 degrees are arranged two-dimensionally 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 a total CS-1000 (Konica Minolta Sensing Co., Ltd.) is applied to the CIE chromaticity coordinates.
When the organic EL element of the present invention is a white element, white means that the chromaticity in the CIE1931 color system at 1000 cd / m ² is X when the 2 ° viewing angle front luminance is measured by the above method. = 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 diagram showing an example of a display device composed of organic EL elements, and is a schematic diagram of a display such as a mobile phone that displays image information by light emission of the organic EL elements.
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, and the pixels for each scanning line respond to the image data signal by the scanning signal. 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, the combination of luminescent materials for obtaining multiple luminescent colors is a combination of multiple phosphorescent or fluorescent materials that emit light, fluorescent materials or phosphorescent materials, and light from the luminescent materials. Any combination with a dye material that emits light as light may be used, but in the white organic EL device according to the present invention, it is only necessary to mix and mix a plurality of light emitting dopants.
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 the illumination device.
The organic EL element 101 of the present invention is covered with a glass cover 102.
The sealing operation with the glass cover 102 is preferably performed in a glove box (in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more) in a nitrogen atmosphere without bringing the organic EL element 101 into contact with the atmosphere.
FIG. 6 shows a cross-sectional view of the lighting device.
As shown in FIG. 6, a transparent electrode (anode) 107, an organic EL layer 106, and a cathode 105 are laminated in this order on a glass substrate. The glass cover 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "%" is used in a present Example, unless otherwise indicated, "mass%" is represented.
The compounds used in this example are shown below.

[Example 1]
(Preparation of nanoparticle dispersion)
(1) Nanoparticle dispersion N-1
Ammonium molybdate was added to pure water to prepare an aqueous solution with a Mo concentration of 0.1 mol / l. 200 g of the aqueous solution, 40 g of palmitic acid, and 13 g of 2-dimethylaminoethanol were mixed to prepare a raw material solution. The reaction was carried out for 2.0 seconds at a temperature of 380 ° C. and a pressure of 30 MPa using a flow reactor shown in FIG. 1 of JP-A-2005-255450. The crystallinity was 55% by powder X-ray (XRD) analysis. The average particle diameter was 7.0 nm as observed with an electron microscope (TEM). 0.03 g of the obtained particle powder was dispersed in 30 g of toluene using an ultrasonic disperser to obtain a dispersion N-1.

(2) Nanoparticle dispersion liquid N-2
A molybdenum-containing nanoparticle dispersion was prepared in accordance with Synthesis Example 1 of JP2010-272892A. 0.8 g of n-hexadecylamine and 12.8 g of n-octyl ether were weighed, depressurized while stirring, and left at room temperature (24 ° C.) for 1 hour (hr) to remove low volatile components. The atmosphere was changed from under vacuum to atmospheric atmosphere, and 0.8 g of molybdenum hexacarbonyl was added. The mixture was placed in an argon gas atmosphere, heated to 280 ° C. with stirring, and reacted at that temperature for 1 hour (hr). The crystallinity was 15% by powder X-ray (XRD) analysis. The average particle diameter was 6.0 nm as observed with an electron microscope (TEM). 0.03 g of the obtained particle powder was dispersed in 30 g of toluene using an ultrasonic disperser to obtain a dispersion N-2.

(3) Nanoparticle dispersion N-3
Zirconium oxoacetate was added to pure water to prepare an aqueous solution with a Zr concentration of 0.1 mol / l. This was mixed with an equal volume of 0.1 mol / l potassium hydroxide aqueous solution to prepare a raw material solution, and reacted for 1.8 seconds at a temperature of 400 ° C. and a pressure of 30 MPa using the reactor used in the production of N-1. The crystallinity was 75% by powder X-ray (XRD) analysis. The average particle diameter was 6.8 nm as observed with an electron microscope (TEM). 0.03 g of the obtained particle powder was dispersed in 30 g of hexafluoroisopropanol (HFIP) using an ultrasonic disperser to obtain a dispersion N-3.

(4) Nanoparticle dispersion N-4
Dispersion N-4 was obtained in the same manner except that yttrium nitrate was used instead of zirconium oxoacetate in the preparation of nanoparticle dispersion N-3.
The crystallinity was 65% and the average particle size was 9.2 nm.
(5) Nanoparticle dispersion liquid N-5
Dispersion N-5 was obtained in the same manner except that cerium nitrate was used instead of zirconium oxoacetate in the production of nanoparticle dispersion N-3.
The crystallinity was 60%, and the average particle size was 5.6 nm.
(6) Nanoparticle dispersion N-6
A dispersion N-6 was obtained in the same manner except that hexanoic acid was further added to the raw material liquid in the production of the nanoparticle dispersion N-3.
The crystallinity was 75% and the average particle size was 7.3 nm.
(7) Nanoparticle dispersion liquid N-7
A dispersion N-7 was obtained in the same manner except that hexanal was further added to the raw material liquid in the production of the nanoparticle dispersion N-3.
The crystallinity was 75%, and the average particle size was 7.0 nm.
(8) Nanoparticle dispersion N-8
A dispersion N-8 was obtained in the same manner except that the compound S-1 was further added to the raw material liquid in the production of the nanoparticle dispersion N-3.
The crystallinity was 75%, and the average particle size was 8.5 nm.

(9) Nanoparticle dispersion liquid N-9
Zirconium oxoacetate was added to pure water to prepare an aqueous solution having a Zr concentration of 0.25 mol / l. 30 cc of this aqueous solution was introduced into an autoclave (Teflon (registered trademark) inner cylinder, 50 cc) and hydrothermally treated in an oven at 150 ° C. for 24 hours.
The crystallinity was 10% by powder X-ray (XRD) analysis. The average particle diameter was 3.0 nm as observed with an electron microscope (TEM). 0.03 g of the obtained particle powder was dispersed in 30 g of HFIP using an ultrasonic dispersing machine to obtain a dispersion N-9.

(10) Nanoparticle dispersion N-10
As nanoparticles, zirconium oxide particle powder (crystallinity: 80%) produced by a hydrolysis-firing method was used in a paint shaker. The average particle diameter was 15 nm by electron microscope (TEM) observation. 0.03 g of the zirconium oxide particle powder was mixed with 30 g of HFIP and zirconia beads having a diameter of 3 mm, and dispersed in a solvent while physically pulverizing to obtain a zirconium oxide dispersion. Further, the dispersion was dispersed with zirconia beads having a diameter of 0.3 mm for 24 hours, and the supernatant dispersion was filtered with a 0.2 μm filter to obtain dispersion N-10.

  The characteristics of the nanoparticle dispersions N-1 to N-10 are shown in Table 1.

[Production of organic EL elements]
(1) Organic EL element 1
A transparent substrate provided with this ITO transparent electrode after patterning was performed on a substrate (NH-Techno Glass NA-45) in which ITO (indium tin oxide) was formed to a thickness of 100 nm on a glass substrate of 100 mm × 100 mm × 1.1 mm as an anode. The support substrate was subjected to ultrasonic cleaning with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes. On this transparent support substrate, H.P. C. A solution obtained by diluting Stark's PEDOT-PSS (CLEVIOS P VP AI 4083) to 70% with pure water was formed by spin coating, and then dried at 200 ° C. for 1 hour to form a first hole having a thickness of 30 nm. A transport layer was provided.
Next, the glass substrate provided with the first hole transport layer described above was placed in a glove box in a nitrogen atmosphere, 20 mg of α-NPD was dissolved in 7 ml of toluene, and the nanoparticle dispersion N-1 prepared above was further dissolved. 5 ml of the mixed liquid was formed into a film by a spin coating method (1000 rpm, 30 seconds), and a second hole transport layer having a thickness of 30 nm was formed.
Next, each material described later was packed in a molybdenum or tungsten vapor deposition boat, and set together with the glass substrate provided with the first hole transport layer and the second hole transport layer described above in a vacuum vapor deposition apparatus. When the degree of vacuum became 1 × 10 ⁻⁴ Pa or less, the compound HS-2 was co-deposited at a deposition rate of 0.1 nm / second, and the compound DP-1 was co-deposited at a deposition rate of 0.02 nm / second. A light emitting layer having a thickness of 30 nm was provided.
Further, ET-2 was deposited at a deposition rate of 0.1 nm / second to provide an electron transport layer with a thickness of 80 nm, and then lithium fluoride with a thickness of 1 nm as an electron injection layer and aluminum with a thickness of 110 nm as a cathode. It vapor-deposited and the organic EL element 1 was produced.

(2) Organic EL element 2
An organic EL element 2 was produced in the same manner as the production of the organic EL element 1 except that the nanoparticle dispersion liquid N-1 was changed to the nanoparticle dispersion liquid N-2.

(3) Organic EL element 3
A transparent substrate provided with this ITO transparent electrode after patterning was performed on a substrate (NH-Techno Glass NA-45) in which ITO (indium tin oxide) was formed to a thickness of 100 nm on a glass substrate of 100 mm × 100 mm × 1.1 mm as an anode. The support substrate was subjected to ultrasonic cleaning with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes. On this transparent support substrate, H.P. C. A solution obtained by diluting Stark's PEDOT-PSS (CLEVIOS P VP AI 4083) to 70% with pure water was formed by spin coating, and then dried at 200 ° C. for 1 hour to form a first hole having a thickness of 30 nm. A transport layer was provided.
Subsequently, each material described later was packed in a molybdenum or tungsten vapor deposition boat and set together with the glass substrate provided with the first hole transport layer described above in a vacuum vapor deposition apparatus. When the degree of vacuum became 1 × 10 ⁻⁴ Pa or less, α-NPD was deposited at a deposition rate of 0.1 nm / second to provide a second hole transport layer having a thickness of 30 nm. Further, the compound HS-2 was co-deposited at a deposition rate of 0.1 nm / second and the compound DP-1 was deposited at a deposition rate of 0.02 nm / second to provide a light emitting layer having a thickness of 30 nm.
Return to atmospheric pressure in a nitrogen atmosphere, take out into a glove box in a nitrogen atmosphere, dissolve 20 mg of ET-2 in 10 ml of HFIP, and form an electron transport layer with a thickness of 80 nm by spin coating (1000 rpm, 30 seconds). did. This substrate was set again in a vacuum deposition apparatus, and 1 nm thick lithium fluoride was deposited as an electron injection layer, and 110 nm thick aluminum was deposited as a cathode to produce an organic EL element 3.

(4) Organic EL element 4
An organic EL element 4 was produced in the same manner as the organic EL element 3 except that ET-4 was used instead of ET-2 for the electron transport layer.
(5) Organic EL element 5
20 mg of ET-2 was dissolved in 7 ml of HFIP, and a mixed solution was prepared by adding 5 ml of the nanoparticle dispersion N-9 prepared above. Then, an electron transport layer having a film thickness of 80 nm was formed by spin coating (1000 rpm, 30 seconds) on the substrate on which the light-emitting layer of the organic EL element 3 was formed. Further, this substrate was set again in a vacuum deposition apparatus, and 1 nm-thick lithium fluoride was deposited as an electron injection layer, and 110 nm-thick aluminum was deposited as a cathode, thereby producing an organic EL element 5.

(6) Organic EL elements 6-12
Instead of the nanoparticle dispersion liquid N-9 used in the method for producing the organic EL element 5, as shown in Table 2, the nanoparticle dispersion liquids N-10 and N-3 to N-8 were used in exactly the same manner. Thus, organic EL elements 6 to 12 were produced.
(7) Organic EL elements 13-14
Organic EL elements 13 and 14 were produced in exactly the same manner except that the addition amount of the nanoparticle dispersion liquid N-3 used in the production method of the organic EL element 7 was changed to 30 ml and 80 ml, respectively.
(8) Organic EL elements 15-18
Except that the electron transport agent ET-2 used in the production method of the organic EL element 7 was changed to ET-4, ET-9, ET-10, and ET-14, the organic EL elements 15 to 18 were formed in exactly the same manner. Produced.
(9) Organic EL element 19
Organic EL element 19 was produced in exactly the same manner except that ET-2 of the electron transport agent used in the production method of organic EL element 10 was changed to ET-4.

(10) Organic EL element 20
A transparent substrate provided with this ITO transparent electrode after patterning was performed on a substrate (NH-Techno Glass NA-45) in which ITO (indium tin oxide) was formed to a thickness of 100 nm on a glass substrate of 100 mm × 100 mm × 1.1 mm as an anode. The support substrate was subjected to ultrasonic cleaning with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes. On this transparent support substrate, H.P. C. A solution obtained by diluting Stark's PEDOT-PSS (CLEVIOS P VP AI 4083) to 70% with pure water was formed by spin coating, and then dried at 200 ° C. for 1 hour to form a first hole having a thickness of 30 nm. A transport layer was provided.
Next, the glass substrate provided with the first hole transport layer described above was placed in a glove box in a nitrogen atmosphere, 20 mg of α-NPD was dissolved in 7 ml of toluene, and the nanoparticle dispersion N-1 prepared above was further dissolved. A second hole transport layer having a thickness of 30 nm was formed by spin coating (1000 rpm, 30 seconds) from the mixed solution containing 5 ml of the mixture.
Each material described later was packed in a molybdenum or tungsten vapor deposition boat and set together with the glass substrate provided with the first hole transport layer and the second hole transport layer described above in a vacuum deposition apparatus. When the degree of vacuum became 1 × 10 ⁻⁴ Pa or less, the compound HS-2 was co-deposited at a deposition rate of 0.1 nm / second, and the compound DP-1 was co-deposited at a deposition rate of 0.02 nm / second. A light emitting layer having a thickness of 30 nm was provided.
Return to atmospheric pressure under a nitrogen atmosphere, take out in a glove box under a nitrogen atmosphere, dissolve 20 mg of ET-2 in 7 ml HFIP, and then prepare a mixed solution containing 5 ml of the nanoparticle dispersion N-3 prepared above. Then, an electron transport layer having a thickness of 80 nm was formed by a spin coating method (1000 rpm, 30 seconds). This substrate was set again in a vacuum deposition apparatus, and 1 nm thick lithium fluoride was deposited as an electron injection layer, and 110 nm thick aluminum was deposited as a cathode to produce an organic EL element 20.

[Evaluation of organic EL elements 1-20]
When evaluating the obtained organic EL elements 1 to 20, the non-light emitting surface of each organic EL element after production is covered with a glass case, and a glass substrate having a thickness of 300 μm is used as a sealing substrate. As an epoxy-based photo-curing adhesive (Lux Track LC0629B manufactured by Toagosei Co., Ltd.), it is placed on the cathode and brought into close contact with the transparent support substrate, and UV light is irradiated from the glass substrate side to cure. The lighting device as shown in FIGS. 5 and 6 was manufactured and evaluated.
Evaluation items and evaluation methods are as follows.

(1) Driving voltage The light emission starting voltage was measured at a temperature of 23 ° C. in a dry nitrogen gas atmosphere.
The voltage at the start of light emission was expressed as a relative value obtained by measuring the voltage value when the luminance was 50 cd / m ² or more and setting the driving voltage of the organic EL element 3 to 100. A spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing) was used for the measurement of luminance. The results are shown in Table 2 below.

(2) Drive voltage change Under the condition of applying a constant current of ^2.5 mA / cm ² in a dry nitrogen gas atmosphere at a temperature of 23 ° C., the voltage value at which the luminance is the initial luminance is (DV0), and the luminance is 30 from the initial luminance. When the voltage value at the time of decrease by% is (DV70), (DV70) − (DV0) is represented as a drive voltage change, and the drive voltage change of the organic EL element 3 is represented as a relative value of 100. The results are shown in Table 2 below.

(3) Power efficiency Measure the external extraction quantum efficiency (%) when applying a ^2.5 mA / cm ² constant current in a dry nitrogen gas atmosphere at a temperature of 23 ° C., and set the power efficiency of the organic EL element 3 to 100 Expressed as a relative value. A spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing) was used for luminance measurement. Table 2 shows the results of the organic EL elements 1 to 20.

(4) Summary As shown in Table 2, when Samples 1 to 8 and Samples 2 to 7 of the organic EL element are compared, the results of the former sample are good. That is, in the former sample, the effect with respect to the change in the driving voltage was remarkable, and a large power efficiency gain was obtained particularly as a result of the reduction in the driving voltage. This indicates that the invention is very effective for energy saving, which is an advantage of the organic EL element.
From these results, it is useful to improve the luminous efficiency of the organic EL device by incorporating crystalline semiconductor nanoparticles having an average particle diameter of less than 10 nm with respect to at least one of the hole transport layer and the electron transport layer. I know that there is.
In particular, from comparison between Samples 1 and 7 and Sample 20, it is useful to incorporate semiconductor nanoparticles in both the hole transport layer and the electron transport layer.
Furthermore, it is useful to modify the semiconductor nanoparticles from the comparison between the samples 7 to 9 and the samples 10 to 12, and from the comparison between the sample 7 and the samples 15 to 18 and the comparison between the sample 10 and the sample 19, It can also be seen that it is useful to use a pyridine derivative as the electron transport agent.

[Example 2]
In this example, a full-color display device was produced using the organic EL element produced in Example 1, and its availability was confirmed.

(1) Blue light emitting organic EL element The organic EL element 7 produced in Example 1 was used.
(2) Green light-emitting organic EL device An organic EL device 7G manufactured in exactly the same manner as the organic EL device 7 manufactured in Example 1 except that DP-1 used in the light-emitting layer was changed to D-3 was manufactured. This was used.
(3) Red light emitting organic EL element An organic EL element 7R produced in the same manner as in the organic EL element 7 produced in Example 1 except that DP-1 used for the light emitting layer was changed to D-10 was manufactured. This was used.

(4) Production of Full Color Display Device The blue, green, and red light emitting organic EL elements produced above were arranged in parallel on the same substrate to produce an active matrix type full color display device having a form as shown in FIG.
In FIG. 2, only the schematic diagram of the display part A of the produced display device is shown.
As shown in FIG. 2, the display unit A includes a wiring unit including a plurality of scanning lines 5 and data lines 6 on the same substrate, and a plurality of juxtaposed pixels 3 (a light emitting color is a red region pixel, a green region pixel, Blue region pixels, etc.). Each of the scanning lines 5 and the plurality of data lines 6 in the wiring portion is made of a conductive material. 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 not shown).
The plurality of pixels 3 are driven by an active matrix system in which an organic EL element corresponding to each emission color, a switching transistor as an active element, and a driving transistor are provided. When a scanning signal is applied from the scanning line 5, an image data signal is received from the data line 6, and light is emitted in accordance with the received image data. Thus, a full color display device was produced by juxtaposing the red, green, and blue pixels 3 appropriately.
It was found that the produced organic EL element exhibited blue, green, and red light emission by applying a voltage to each electrode, and could be used as a full-color display device.

[Example 3]
In this example, a white light-emitting lighting device was manufactured using the organic EL element manufactured in Example 1, and its availability was confirmed.
Similarly, except that DP-1 used in the organic EL element 7 produced in Example 1 was changed to a ternary mixture of DP-1, D-3, and D-10, a white light-emitting organic EL element 7W was obtained. Produced. The obtained organic EL element 7W was covered with a glass case on a non-light-emitting surface to obtain a lighting device. Such an illuminating device can 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 102 Glass cover 105 Cathode 106 Organic EL layer 107 Transparent electrode (anode)
108 Nitrogen gas 109 Water catching agent

Claims (9)

In an organic electroluminescent device comprising an anode, a cathode and a plurality of organic layers, wherein the organic layer is disposed between the anode and the cathode, and has at least a light emitting layer, a hole transport layer and an electron transport layer,
At least one layer of the hole transport layer or the electron transport layer contains crystalline semiconductor nanoparticles having an average particle diameter of less than 10 nm. The organic electroluminescent device according to claim 1,
The organic semiconductor element, wherein the crystalline semiconductor nanoparticles are contained in the electron transport layer. The organic electroluminescent device according to claim 1,
The organic semiconductor element, wherein the crystalline semiconductor nanoparticles are contained in both the hole transport layer and the electron transport layer. In the organic electroluminescent element as described in any one of Claims 1-3,
The crystalline semiconductor nanoparticle is an organic electroluminescence device wherein the particle surface is modified with an organic substance. In the organic electroluminescent element as described in any one of Claims 1-4,
An organic electroluminescence device, wherein the electron transport layer contains a pyridine derivative represented by the general formula (1).

[In General Formula (1), “R _{1 to} R ₅ ” represent a hydrogen atom or a substituent, and the substituents may be bonded to each other to form a ring. ] In the organic electroluminescent element according to any one of claims 1 to 5,
An organic electroluminescence element which emits white light.   The illuminating device provided with the organic electroluminescent element as described in any one of Claims 1-6.   A display device comprising the organic electroluminescence element according to claim 1. In the manufacturing method of the organic electroluminescent element as described in any one of Claims 1-6,
A step of hydrothermal reaction using subcritical or supercritical water as a medium to produce the crystalline semiconductor nanoparticles;
Containing the crystalline semiconductor nanoparticles after production in at least one of the hole transport layer or the electron transport layer;
A method for producing an organic electroluminescence element, comprising:

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