JP5586254B2 - Organic electroluminescent device, organic electroluminescent device manufacturing method, display device and lighting device - Google Patents

Description

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

  As devices using organic materials, researches on organic electroluminescent elements (hereinafter also referred to as organic EL elements), transistors using organic semiconductors, and the like have been actively conducted. In particular, the organic EL element is expected to develop as a lighting application as a solid light-emitting large-area full-color display element or an inexpensive large-area surface light source. In general, an organic electroluminescent element is composed of an organic layer including a light emitting layer and a pair of counter electrodes sandwiching the organic layer. When a voltage is applied to such an organic electroluminescence device, electrons are injected from the cathode and holes are injected from the anode into the organic layer. The electrons and holes recombine in the light emitting layer, and light is emitted by releasing energy as light when the energy level returns from the conduction band to the valence band.

  In the production of an organic electroluminescent device, as a method of forming a thin film which is an organic layer provided between a pair of electrodes, vacuum deposition is used as a vapor deposition method, spin coating method, printing method, ink jet method is used as a wet method. Yes.

The vapor deposition method is a method of forming a thin film on a substrate in a vacuum, and such an organic electroluminescent element (hereinafter also referred to as a vapor deposition type organic EL element) manufactured by using vapor deposition is used for a mobile phone, It has been put to practical use as a light emission source for displays such as televisions.
However, the vapor deposition process in the production of the vapor deposition type organic EL element has a large equipment cost for the vapor deposition apparatus and an energy cost when vapor depositing the material, and it is required to further reduce the production cost of the organic electroluminescent element. .

  In the wet method, it is possible to use high molecular organic compounds that are difficult to form in a dry process such as vapor deposition. The film formation method is simpler than vapor deposition, etc. Is not necessary, and there are advantages such as being suitable for durability such as bending resistance and film strength when used for flexible displays, etc., especially for large area and high definition. This is a technique suitable for a large screen organic EL display.

For example, Patent Documents 1 and 2 disclose an organic electroluminescent element (hereinafter, also referred to as a coating-type organic EL element) in which a layer constituting the organic EL element is manufactured using a coating method.
Patent Document 3 discloses an element in which at least one organic layer includes an organic layer formed by a wet process using two or more organic compounds including at least one organic compound subjected to sublimation purification. .
Patent Document 4 discloses a non-aqueous coating dispersion for an organic electroluminescence element that has good dispersion stability by incorporating a dispersion stabilizer in the coating dispersion. Furthermore, an organic EL device having a high external extraction quantum efficiency and a long emission lifetime, which is formed using the coating dispersion or the non-aqueous coating dispersion, is disclosed.

  However, the coating type organic EL element has a problem that the light emission efficiency and durability are low. Impurities are considered to be a cause of deterioration in luminous efficiency and element durability in the coating type EL element. For this reason, there are cases where the coating method is adopted for polymer materials that cannot be deposited by vapor deposition, but low molecular weight materials that can be deposited by vapor deposition have a vapor deposition method that provides higher device performance. In general, it was used to form a film.

JP 2004-160388 A JP 2007-42314 A JP 2008-66759 A JP 2007-165231 A

An object of the present invention is to solve the conventional problems and achieve the following objects.
That is, an object of the present invention is to provide an organic electroluminescent device that is excellent in luminous efficiency and durability, has a low driving voltage, and can reduce manufacturing costs.
Another object of the present invention is to provide a method for producing an organic electroluminescent device that can produce an organic electroluminescent device having excellent luminous efficiency and durability and low driving voltage at a low production cost.
Furthermore, an object of this invention is to provide the display apparatus and illuminating device which comprise the said organic electroluminescent element.

That is, the means for solving the above problems are as follows.
[1]
An organic electroluminescent device having a light emitting layer and at least one layer adjacent to the light emitting layer between a pair of electrodes,
An organic electroluminescent device, wherein the at least one layer adjacent to the light emitting layer is formed by a spray method using a liquid containing two or more low molecular weight compounds having a molecular weight of 1500 or less.
[2]
The organic electroluminescence device according to [1], wherein the at least one layer adjacent to the light emitting layer is a hole transport layer.
[3]
The two or more kinds of low molecular weight compounds having a molecular weight of 1500 or less are two kinds of compounds of a first low molecular weight compound and a second low molecular weight compound, and the mixing ratio is 20:80 to 80:20 in mass ratio. The organic electroluminescent element as described in [1] or [2], wherein
[4]
The organic electroluminescent element according to any one of [1] to [3], wherein the two or more kinds of low molecular compounds having a molecular weight of 1500 or less are two or more kinds of hole transport materials.
[5]
[4] The organic electroluminescence device as described in [4], wherein the difference in ionization potential between the two or more hole transport materials is 0.1 eV or more and 0.6 eV or less.
[6]
The organic electroluminescence device according to [4] or [5], wherein the two or more hole transport materials are arylamine derivatives or carbazole derivatives.
[7]
The organic electroluminescent element according to any one of [1] to [6], wherein the at least one layer adjacent to the light emitting layer is an electron transport layer.
[8]
The organic electroluminescence device according to [7], wherein the electron transport layer is formed of a liquid containing two or more kinds of electron transport materials.
[9]
The organic electroluminescence device as described in [8], wherein the difference in electron affinity between the two or more electron transport materials is 0.1 eV or more and 0.6 eV or less.
[10]
A method for producing an organic electroluminescent device comprising a light emitting layer and at least one layer adjacent to a light emitting layer between a pair of electrodes,
A method for producing an organic electroluminescence device, wherein a layer adjacent to at least one light emitting layer is formed by a spray method using a liquid containing two or more low molecular weight compounds having a molecular weight of 1500 or less.
[11]
Each of the said light emitting layer and the layer adjacent to the said light emitting layer is formed with the said spray method, The manufacturing method of the organic electroluminescent element as described in [10] characterized by the above-mentioned.
[12]
A display device comprising the organic electroluminescent element according to [1] to [9] or the organic electroluminescent element obtained from the method for producing an organic electroluminescent element according to any one of [10] or [11] .
[13]
The organic electroluminescent element according to any one of [1] to [9], or the organic electroluminescent element obtained from the method for producing an organic electroluminescent element according to any one of [10] or [11] Lighting device.

According to the present invention, the layer adjacent to the light emitting layer is formed by a spray method using a liquid containing two or more kinds of low molecular weight compounds having a molecular weight of 1500 or less, so that it has excellent thermal stability, light emitting efficiency and durability, and is driven. An organic electroluminescent device having a low voltage and capable of reducing manufacturing costs can be provided.
In addition, according to the present invention, it is possible to provide a method for manufacturing an organic electroluminescent element capable of manufacturing an organic electroluminescent element having excellent thermal stability, luminous efficiency and durability and low driving voltage at a low manufacturing cost.
Furthermore, according to this invention, the display apparatus and illuminating device which comprise the said organic electroluminescent element can be provided.

It is the schematic which shows an example of the layer structure of the organic EL element which concerns on this invention. It is the schematic which shows an example of the display apparatus which concerns on this invention. It is the schematic which shows an example of the illuminating device which concerns on this invention.

  Hereinafter, the organic EL device according to the embodiment of the present invention will be described in detail.

The organic EL device of the present invention is an organic electroluminescent device having a light emitting layer and at least one layer adjacent to the light emitting layer between a pair of electrodes,
The at least one layer adjacent to the light emitting layer is formed by a spray method using a liquid containing two or more kinds of low molecular compounds having a molecular weight of 1500 or less.

  Here, the low molecular weight compound in the present invention refers to a compound having an unsaturated bond (so-called polymerizable monomer) by cleaving the unsaturated bond using an initiator and growing the bond in a chain manner. It is not a so-called polymer or oligomer obtained, but a compound having a constant molecular weight of 1500 or less (a compound having substantially no molecular weight distribution). The molecular weight is usually 100 or more.

  Thereby, the material which forms the layer adjacent to a light emitting layer does not contain the impurity derived from compounds, such as a polymerization initiator, a polymerization terminator, and a chain transfer agent, which are used for polymer synthesis and oligomer synthesis. Thereby, it is considered that such an impurity can prevent the function of the layer from being deteriorated, so that an organic electroluminescence device excellent in luminous efficiency and durability can be obtained.

  The low molecular weight compound having a molecular weight of 1500 or less is more preferably purified by a known purification method. Thereby, it can avoid more reliably that an impurity degrades the function of each layer. Known purification methods include a sublimation purification method, a recrystallization purification method, a column purification method, and the like. In the case of a polymer or oligomer, when the repeating unit has an unintended structure due to reaction or the like, it is very difficult to purify such a polymer or oligomer by purification. It is preferably a molecular compound.

The number of low molecular compounds having a molecular weight of 1500 or less is 2 or more, preferably 2 to 4, more preferably 2 to 3, and still more preferably 2.
When there are two kinds of low molecular weight compounds having a molecular weight of 1500 or less, the mixing ratio of the first low molecular weight compound and the second low molecular weight compound is preferably 20:80 to 80:20, and 30:70 to 70: 30 is more preferable.

  Furthermore, the organic EL element of the present invention having the above configuration can reduce the driving voltage.

  Moreover, since the material constituting the layer is formed by spraying a solution in which a solvent is dissolved or dispersed in the solvent, it is not necessary to employ a vapor deposition process as described above, and the manufacturing cost of the organic EL element is reduced. it can.

  FIG. 1 shows an example of the configuration of an organic EL element according to the present invention. In the organic electroluminescent element 10 according to the present invention shown in FIG. 1, an organic layer is sandwiched between an anode 3 and a cathode 9 on a support substrate 2. More specifically, the organic layer includes, for example, a hole injection layer 4 on the anode, a hole transport layer 5 on the hole injection layer 4, a light emitting layer 6 on the hole transport layer 5, It consists of a hole blocking layer 7 on the light emitting layer 6 and an electron transporting layer 8 on the hole blocking layer 7.

  Although there is no restriction | limiting in particular in solid content with respect to the whole quantity of the said liquid, Usually, although it is 0.0001 mass%-10 mass%, when adoption of the spray method is considered, it is 0.0001 mass%-1 mass%. Preferably there is.

In addition, at least one layer adjacent to the light emitting layer is preferably a hole transport layer.
In particular, when the light emitting layer is provided directly on the hole transport layer and the electron transport layer is provided directly on the light emitting layer, the solvent of the liquid may be the same organic solvent. Preferably, this makes it possible to obtain an organic EL element excellent in luminous efficiency and durability, in particular, because the bonding at the interface between the layers becomes better.

  At least one of the light emitting layer and the layer adjacent to the light emitting layer is formed by applying the liquid by a spray method. Thereby, particularly when the lower layer of the layer formed by the spray method is another organic layer, the organic solvent of the liquid may be damaged by dissolving the other organic layer to an unintended degree. Since this can be reduced more reliably, it is possible to obtain an organic EL element that is more reliably excellent in luminous efficiency, durability, and color reproducibility. In addition, the spray method can easily reduce the amount of solvent used and can be easily dried as compared with other coating methods, and thus can further reduce the manufacturing cost. Furthermore, the spray method is suitable for forming a multilayer thin film because the layer can be formed without damaging the lower layer of the layer formed by the spray method.

In addition, the step of applying the liquid by the spray method is, in other words, the step of applying the aerosol to form a layer by injecting the aerosol in which the liquid particles are suspended in the gas (carrier gas) onto a predetermined surface. It is. The form of the aerosol is not particularly limited, but the particle size of the liquid particles is usually 0.01 to 100 μm, more preferably 0.01 to 10 μm. Examples of the gas include air, nitrogen, and argon.
Any known spray device can be used for the spray method.
The flow rate of the carrier gas of the aerosol is preferably 0.1 L / min to 100 L / min, and more preferably 0.1 L / min to 10 L / min.
The spraying time of the aerosol conforms to the thickness to be obtained from each layer and is not particularly limited.
The layer formed by the spray method is preferably dried for a certain period after the layer formation by the spray method is completed, particularly when another layer is provided on the layer. As a drying method, although depending on the kind of the organic solvent to be used, the temperature is preferably 20 to 200 ° C., and the drying time is preferably 1 minute to 10 hours. The drying is preferably vacuum drying.

In the present invention, at least one of the light-emitting layer and the layer adjacent to the light-emitting layer is applied by spraying the above liquid, but the application method of the other layers is not particularly limited. For example, it can be performed by spin coating, air knife coating, bar coating, blade coating, slide coating, curtain coating, spray method, casting method, dipping method, ink jet method and the like.
For example, when the hole transport layer is provided directly on the anode, the material for the anode is normally a material having high resistance to organic solvents as described later. With respect to the hole transport layer, any of the liquid coating methods exemplified above can be suitably used.

  However, in view of the advantages described above, for example, when adopting the spray method for the light-emitting layer and the electron transport layer, the spray method can also be used for the hole transport layer, so that the coating method can be unified. Cost can be reduced. Therefore, a form in which each of the light emitting layer and the layer adjacent to the light emitting layer is formed by applying the liquid by a spray method is more preferable, and each of the hole transport layer, the light emitting layer, and the electron transport layer is the liquid. The form formed by coating by a spray method is most preferable.

The layer configuration of the organic layer has been described with reference to FIG. 1 as described above, but is not particularly limited and can be appropriately selected according to the application and purpose of the organic EL element.
Moreover, there is no restriction | limiting in particular also about the shape of a organic layer, a magnitude | size, thickness, etc., According to the objective, it can select suitably.

  Specific examples of the layer structure of the organic EL element are given below, but the present invention is not limited to these structures.

(1) Anode / hole transport layer / light emitting layer / electron transport layer / cathode (2) Anode / hole transport layer / light emitting layer / block layer / electron transport layer / cathode (3) Anode / hole transport layer / light emission Layer / block layer / electron transport layer / electron injection layer / cathode (4) anode / hole injection layer / hole transport layer / light emitting layer / block layer / electron transport layer / cathode (5) anode / hole injection layer / Hole transport layer / light emitting layer / block layer / electron transport layer / electron injection layer / cathode

  As described above, in the present invention, the layer adjacent to the light emitting layer is formed by applying a liquid in which the material constituting the layer is dissolved or dispersed in a solvent. The transport layer is preferably formed by a coating method, the hole transport layer and the electron transport layer are more preferably formed by a coating method, and the light-emitting layer, the hole transport layer and the electron transport layer are formed by a coating method. More preferably, it is formed. A material constituting each layer in each of a plurality of continuous layers including a hole transport layer, a light emitting layer, and an electron transport layer (however, the plurality of layers constitute a part or all of the organic layer). Is more preferably formed by applying a solution dissolved or dispersed in a solvent. That is, another layer constituting the organic layer (a block layer in the case of the above layer configuration (2)) is provided between the hole transport layer and the light-emitting layer and / or between the light-emitting layer and the electron transport layer. The plurality of layers (in the case of the layer configuration (2), the hole transport layer, the light-emitting layer, the block layer, and the electron transport layer) may be interposed, and any of the layers is formed by a vapor deposition method. Compared with the case where it is formed, since the interface between each layer is good from one end surface to the other end surface of a plurality of layers, the organic EL that has excellent luminous efficiency and durability and can reduce the driving voltage A device tends to be obtained.

  Although it does not specifically limit as an organic layer, In addition to a light emitting layer, it has a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, a hole block layer, an electron block layer, an exciton block layer, etc. It may be. Each of these layers may have other functions.

The present invention is a method for producing an organic electroluminescent device having a light emitting layer and a layer adjacent to at least one light emitting layer between a pair of electrodes,
The present invention also relates to a method for manufacturing an organic electroluminescent element, wherein the layer adjacent to the at least one light emitting layer is formed by a spray method using a liquid containing two or more compounds having a molecular weight of 1500 or less.
Examples of the organic solvent include the organic solvents.
More preferably, at least one layer adjacent to the light emitting layer is formed by a spray method, and each of the light emitting layer and at least one layer adjacent to the light emitting layer is formed by a spray method. . The hole transport layer and the electron transport layer are more preferably formed by a spray method, and the light emitting layer, the hole transport layer and the electron transport layer are more preferably formed by a spray method. Preferably, at least one of a hole transport layer, the light emitting layer, and the electron transport layer is formed by applying the liquid by a spray method, and each of the hole transport layer, the light emitting layer, and the electron transport layer is formed by: More preferably, the liquid is formed by coating by a spray method.

In the production method of the present invention, a preferred embodiment of the step of applying the liquid by a spray method will be described.
The organic layer included in the organic electroluminescent element of the present invention can be formed by any of the methods described below. Thereby, in forming the organic layer by spray coating, impurities (hydrocarbon, amine, particles) in the carrier gas (inert gas) and impurities such as particles / oil in the pipe can be removed.

In the production method of the present invention, it is preferable to deposit an organic layer by depositing an aerosol obtained by mixing a carrier gas composed of an inert gas and a coating solution having an oxygen concentration of 100 ppm or less and a moisture content of 100 ppm or less on a substrate. Preferably, the inert gas is filtered.
As the inert gas, a known gas such as argon, nitrogen, or helium can be used, and argon or nitrogen is preferably used.
Moreover, it is preferable that the number of particles larger than 0.2 μm is less than one per 100 μm × 100 μm in the organic layer formed by depositing the aerosol on the substrate.
It is preferable to form a film in an atmosphere of an inert gas having an oxygen concentration of 100 ppm or less and a dew point of −30 ° C. or less. The organic layer formed by the above method is preferably dried or annealed in an inert gas atmosphere having an oxygen concentration of 100 ppm or less and a dew point of −30 ° C. or less. Furthermore, it is preferable to deposit an organic layer by depositing it on an insoluble organic layer with respect to the coating solution.

  Next, the element which comprises the organic EL element of this invention is demonstrated in detail.

(substrate)
The substrate used in the present invention is preferably a substrate that does not scatter or attenuate light emitted from the organic compound layer. Specific examples include zirconia-stabilized yttrium (YSZ), inorganic materials such as glass, polyesters such as polyethylene terephthalate, polybutylene phthalate, and polyethylene naphthalate, polystyrene, polycarbonate, polyethersulfone, polyarylate, polyimide, and polycycloolefin. , Norbornene resins, and organic materials such as poly (chlorotrifluoroethylene).
For example, when glass is used as the substrate, alkali-free glass is preferably used as the material in order to reduce ions eluted from the glass. Moreover, when using soda-lime glass, it is preferable to use what gave barrier coatings, such as a silica. In the case of an organic material, it is preferable that it is excellent in heat resistance, dimensional stability, solvent resistance, electrical insulation, and workability.

  There is no restriction | limiting in particular about the shape of a board | substrate, a structure, a magnitude | size, It can select suitably according to the use, purpose, etc. of a light emitting element. In general, the shape of the substrate is preferably a plate shape. The structure of the substrate may be a single layer structure, a laminated structure, may be formed of a single member, or may be formed of two or more members.

  The substrate may be colorless and transparent or colored and transparent, but is preferably colorless and transparent in that it does not scatter or attenuate light emitted from the organic light emitting layer.

The substrate can be provided with a moisture permeation preventing layer (gas barrier layer) on the front surface or the back surface. As a material for the moisture permeation preventive layer (gas barrier layer), inorganic materials such as silicon nitride and silicon oxide are preferably used. The moisture permeation preventing layer (gas barrier layer) can be formed by, for example, a high frequency sputtering method.
When a thermoplastic substrate is used, a hard coat layer, an undercoat layer, or the like may be further provided as necessary.

(anode)
The anode usually has a function as an electrode for supplying holes to the organic compound layer, and there is no particular limitation on the shape, structure, size, etc., depending on the use and purpose of the light-emitting element. , Can be appropriately selected from known electrode materials. The anode is usually provided as a transparent anode.

Suitable examples of the material for the anode include metals, alloys, metal oxides, conductive compounds, and mixtures thereof. Specific examples of the anode material include conductive metals such as tin oxide doped with antimony and fluorine (ATO, FTO), tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO). Metals such as oxides, gold, silver, chromium, nickel, and mixtures or laminates of these metals and conductive metal oxides, inorganic conductive materials such as copper iodide and copper sulfide, polyaniline, polythiophene, polypyrrole, etc. Organic conductive materials, and a laminate of these and ITO. Among these, conductive metal oxides are preferable, and ITO is particularly preferable from the viewpoints of productivity, high conductivity, transparency, and the like.

  The anode is composed of, for example, a wet method such as a printing method and a coating method, a physical method such as a vacuum deposition method, a sputtering method, and an ion plating method, and a chemical method such as a CVD and a plasma CVD method. It can be formed on the substrate according to a method appropriately selected in consideration of suitability with the material to be processed. For example, when ITO is selected as the anode material, the anode can be formed according to a direct current or high frequency sputtering method, a vacuum deposition method, an ion plating method, or the like.

  In the organic EL device of the present invention, the formation position of the anode is not particularly limited and can be appropriately selected according to the use and purpose of the light emitting device, but is preferably formed on the substrate. In this case, the anode may be formed on the entire one surface of the substrate, or may be formed on a part thereof.

  The patterning for forming the anode may be performed by chemical etching such as photolithography, or may be performed by physical etching such as laser, or vacuum deposition or sputtering with a mask overlapped. It may be performed by a lift-off method or a printing method.

  The thickness of the anode can be appropriately selected depending on the material constituting the anode and cannot be generally defined, but is usually about 10 nm to 50 μm, and preferably 50 nm to 20 μm.

The resistance value of the anode is preferably 10 ³ Ω / □ or less, and more preferably 10 ² Ω / □ or less. When the anode is transparent, it may be colorless and transparent or colored and transparent. In order to take out light emission from the transparent anode side, the transmittance is preferably 60% or more, and more preferably 70% or more.

  The transparent anode is described in detail in the book “New Development of Transparent Electrode Films” published by CMC (1999), supervised by Yutaka Sawada, and the matters described here can be applied to the present invention. In the case of using a plastic substrate having low heat resistance, a transparent anode formed using ITO or IZO at a low temperature of 150 ° C. or lower is preferable.

(cathode)
The cathode usually has a function as an electrode for injecting electrons into the organic compound layer, and there is no particular limitation on the shape, structure, size, etc., depending on the use and purpose of the light-emitting element, It can select suitably from well-known electrode materials.

  Examples of the material constituting the cathode include metals, alloys, metal oxides, electrically conductive compounds, and mixtures thereof. Specific examples include alkali metals (eg, Li, Na, K, Cs, etc.), alkaline earth metals (eg, Mg, Ca, etc.), gold, silver, lead, aluminum, sodium-potassium alloys, lithium-aluminum alloys, magnesium. -Rare earth metals such as silver alloys, indium and ytterbium. These may be used singly or in combination of two or more from the viewpoint of achieving both stability and electron injection.

  Among these, as a material constituting the cathode, an alkali metal or an alkaline earth metal is preferable from the viewpoint of electron injecting property, and a material mainly composed of aluminum is preferable from the viewpoint of excellent storage stability. The material mainly composed of aluminum is aluminum alone, an alloy of aluminum and 0.01% by mass to 10% by mass of alkali metal or alkaline earth metal, or a mixture thereof (for example, lithium-aluminum alloy, magnesium-aluminum alloy). Etc.).

  The cathode materials are described in detail in JP-A-2-15595 and JP-A-5-121172, and the materials described in these publications can also be applied in the present invention.

  There is no restriction | limiting in particular about the formation method of a cathode, According to a well-known method, it can carry out. For example, the cathode described above is configured from a wet method such as a printing method or a coating method, a physical method such as a vacuum deposition method, a sputtering method, or an ion plating method, or a chemical method such as CVD or plasma CVD method. It can be formed according to a method appropriately selected in consideration of suitability with the material. For example, when a metal or the like is selected as the cathode material, one or more of them can be simultaneously or sequentially performed according to a sputtering method or the like.

  Patterning when forming the cathode may be performed by chemical etching such as photolithography, physical etching by laser, or the like, or by vacuum deposition or sputtering with the mask overlaid. It may be performed by a lift-off method or a printing method.

In the present invention, the cathode formation position is not particularly limited, and may be formed on the entire organic compound layer or a part thereof.
Further, a dielectric layer made of an alkali metal or alkaline earth metal fluoride or oxide may be inserted between the cathode and the organic compound layer with a thickness of 0.1 nm to 5 nm. This dielectric layer can also be regarded as a kind of electron injection layer. The dielectric layer can be formed by, for example, a vacuum deposition method, a sputtering method, an ion plating method, or the like.

The thickness of the cathode can be appropriately selected depending on the material constituting the cathode and cannot be generally defined, but is usually about 10 nm to 5 μm, and preferably 50 nm to 1 μm.
Further, the cathode may be transparent or opaque. The transparent cathode can be formed by depositing a thin cathode material to a thickness of 1 nm to 10 nm and further laminating a transparent conductive material such as ITO or IZO.

(Organic layer)
The organic layer in the present invention will be described. The organic layer of the organic EL device of the present invention includes a hole transport layer, a light emitting layer, and an electron transport layer.
In addition, as layers other than the above-mentioned layers (hole transport layer, light emitting layer and electron transport layer) constituting the organic layer, as described above, each layer such as a block layer, a hole injection layer, and an electron injection layer Is mentioned.

(Light emitting layer)
The light-emitting layer receives holes from the anode, the hole injection layer, or the hole transport layer when an electric field is applied, receives electrons from the cathode, the electron injection layer, or the electron transport layer, and recombines holes and electrons. It is a layer which has the function to provide and to emit light.
The light emitting layer in the present invention is a thin film containing an amorphous organic semiconductor.
The light emitting layer may be composed of only a light emitting material, but preferably has a mixed layer of a host material and a light emitting material (also referred to as a light emitting dopant).
The light emitting material may be a fluorescent light emitting material or a phosphorescent light emitting material, but is preferably a phosphorescent light emitting material.
The host material is preferably a charge transport material. The host material may be one type or two or more types, and examples thereof include a configuration in which an electron transporting host material and a hole transporting host material are mixed. Furthermore, the light emitting layer may include a material that does not have charge transporting properties and does not emit light.

  The light emitting layer can contain two or more types of light emitting materials in order to improve color purity or to expand the light emission wavelength region. Further, the light emitting layer may be a single layer or two or more layers, and each layer may emit light in different emission colors.

<Phosphorescent material>
In general, examples of the phosphorescent material include complexes containing a transition metal atom or a lanthanoid atom.
For example, the transition metal atom is not particularly limited, but preferably includes ruthenium, rhodium, palladium, tungsten, rhenium, osmium, iridium, gold, silver, copper, and platinum, and more preferably rhenium, iridium. And platinum, more preferably iridium and platinum.
Examples of lanthanoid atoms include lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, erbium, thulium, ytterbium, and lutesium. Among these lanthanoid atoms, neodymium, europium, and gadolinium are preferable.

Examples of the ligand of the complex include G.I. Wilkinson et al., Comprehensive Coordination Chemistry, Pergamon Press, 1987, H.C. Examples include ligands described in Yersin's "Photochemistry and Photophysics of Coordination Compounds" published by Springer-Verlag 1987, Akio Yamamoto "Organic Metal Chemistry-Fundamentals and Applications-" .
The specific ligand is preferably a halogen ligand (preferably a chlorine ligand) or an aromatic carbocyclic ligand (for example, preferably 5 to 30 carbon atoms, more preferably 6 to 6 carbon atoms). 30, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as cyclopentadienyl anion, benzene anion, or naphthyl anion), nitrogen-containing heterocyclic ligand (for example, preferably Has 5 to 30 carbon atoms, more preferably 6 to 30 carbon atoms, still more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, phenylpyridine, benzoquinoline, quinolinol, bipyridyl, or phenanthroline. Etc.), diketone ligand (for example, acetylacetone), carboxylic acid ligand (for example, preferably 2 to 30 carbon atoms, more preferably 2-20 carbon atoms, more preferably 2-16 carbon atoms, such as an acetic acid ligand), an alcoholate ligand (for example, preferably 1-30 carbon atoms, more preferably 1-20 carbon atoms, still more preferably Has 6 to 20 carbon atoms, such as phenolate ligand), silyloxy ligand (for example, preferably 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, still more preferably 3 to 20 carbon atoms). , For example, trimethylsilyloxy ligand, dimethyl-tert-butylsilyloxy ligand, triphenylsilyloxy ligand, etc.), carbon monoxide ligand, isonitrile ligand, cyano ligand, phosphorus coordination (Preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, still more preferably 3 to 20 carbon atoms, and particularly preferably 6 to 20 carbon atoms. Fin ligands, etc.), thiolato ligands (preferably 1-30 carbon atoms, more preferably 1-20 carbon atoms, still more preferably 6-20 carbon atoms, such as phenylthiolato ligands), phos A fin oxide ligand (preferably having 3 to 30 carbon atoms, more preferably 8 to 30 carbon atoms, still more preferably 18 to 30 carbon atoms, such as a triphenylphosphine oxide ligand), more preferably , A nitrogen-containing heterocyclic ligand.
The complex may have one transition metal atom in the compound, or may be a so-called binuclear complex having two or more. Different metal atoms may be contained at the same time.

  Among these, specific examples of the light-emitting material include, for example, US6303238B1, US6097147, WO00 / 57676, WO00 / 70655, WO01 / 08230, WO01 / 39234A2, WO01 / 41512A1, WO02 / 02714A2, WO02 / 15645A1, and WO02 / 44189A1. , WO 05/19373 A2, JP 2001-247859, JP 2002-302671, JP 2002-117978, JP 2003-133074, JP 2002-235076, JP 2003-123982, JP 2002-170684, EP 12112257, Special JP 2002-226495, JP 2002-234894, JP 2001247478, JP 2001-298470, JP 2002-173 74, JP 2002-203678, JP 2002-203679, JP 2004-357799, JP 2006-256999, JP 2007-19462, JP 2007-84635, JP 2007-96259, and the like. Phosphorescent compounds and the like are mentioned. Among them, more preferable luminescent materials include Ir complex, Pt complex, Cu complex, Re complex, W complex, Rh complex, Ru complex, Pd complex, Os complex, Eu complex, Tb complex. , Gd complex, Dy complex, and Ce complex. Particularly preferred is an Ir complex, a Pt complex, or a Re complex, among which an Ir complex or a Pt complex containing at least one coordination mode of a metal-carbon bond, a metal-nitrogen bond, a metal-oxygen bond, and a metal-sulfur bond. Or Re complexes are preferred. Furthermore, from the viewpoints of luminous efficiency, driving durability, chromaticity, etc., an Ir complex, a Pt complex, or a Re complex containing a tridentate or higher polydentate ligand is particularly preferable.

<Fluorescent material>
As the fluorescent light-emitting material, generally, benzoxazole, benzimidazole, benzothiazole, styrylbenzene, diphenylbutadiene, tetraphenylbutadiene, naphthalimide, coumarin, pyran, perinone, oxadiazole, aldazine, pyralidine, cyclopentadiene, bis Styrylanthracene, quinacridone, pyrrolopyridine, thiadiazolopyridine, cyclopentadiene, styrylamine, aromatic dimethylidin compounds, condensed polycyclic aromatic compounds (such as anthracene, phenanthroline, pyrene, perylene, rubrene, or pentacene), 8-quinolinol Examples thereof include various metal complexes represented by metal complexes, pyromethene complexes and rare earth complexes, organosilanes, and derivatives thereof.

  Among these, specific examples of the light emitting material include specific compounds exemplified in paragraphs [0054] to [0064] of JP2009-16579A, and paragraphs [0059] to [0068] of JP2008-218972A. Specific examples of the compound and the light-emitting material 1 used in Examples described later can be given, but are not limited to these because they are appropriately selected.

  The light emitting material in the light emitting layer is contained in an amount of 0.1% by mass to 50% by mass with respect to the total mass of the compound generally forming the light emitting layer in the light emitting layer, but from the viewpoint of durability and external quantum efficiency. The content is preferably 1% by mass to 50% by mass, and more preferably 2% by mass to 40% by mass.

  Although the thickness of the light emitting layer is not particularly limited, it is usually preferably 2 nm to 500 nm, more preferably 3 nm to 200 nm, and more preferably 5 nm to 100 nm from the viewpoint of external quantum efficiency. More preferably.

<Host material>
As the host material used in the present invention, a hole-transporting host material excellent in hole-transporting property (sometimes referred to as a hole-transporting host) and an electron-transporting host material excellent in electron-transporting property (electron-transporting property) May be described as a host).

《Hole-transporting host》
Specific examples of the hole-transporting host used in the present invention include the following materials.
Pyrrole, indole, carbazole, azaindole, azacarbazole, triazole, oxazole, oxadiazole, pyrazole, imidazole, thiophene, polyarylalkane, pyrazoline, pyrazolone, phenylenediamine, arylamine, amino-substituted chalcone, styrylanthracene, fluorenone, hydrazone , Stilbene, silazane, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidin compounds, organic silanes, carbon films, and derivatives thereof.
Preferred are indole derivatives, carbazole derivatives, aromatic tertiary amine compounds, and thiophene derivatives, and more preferred are those having a carbazole group in the molecule.

《Electron transporting host》
The electron transporting host in the light emitting layer used in the present invention preferably has an electron affinity Ea of 2.5 eV or more and 3.5 eV or less from the viewpoint of improving durability and lowering driving voltage. More preferably, it is 0.4 eV or less, and further preferably 2.8 eV or more and 3.3 eV or less. Further, from the viewpoint of improving durability and reducing driving voltage, the ionization potential Ip is preferably 5.7 eV or more and 7.5 eV or less, more preferably 5.8 eV or more and 7.0 eV or less, and 5.9 eV or more. More preferably, it is 6.5 eV or less.

Specific examples of such an electron transporting host include the following materials.
Pyridine, pyrimidine, triazine, imidazole, pyrazole, triazole, oxazole, oxadiazol, fluorenone, anthraquinodimethane, anthrone, diphenylquinone, thiopyran dioxide, carbodiimide, fluorenylidenemethane, distyrylpyrazine, Fluorine-substituted aromatic compounds, heterocyclic tetracarboxylic anhydrides such as naphthaleneperylene, phthalocyanines, and derivatives thereof (which may form condensed rings with other rings), metal complexes and metals of 8-quinolinol derivatives Examples thereof include various metal complexes represented by metal complexes having phthalocyanine, benzoxazole or benzothiazol as a ligand.

Preferred examples of the electron transporting host include metal complexes, azole derivatives (benzimidazole derivatives, imidazopyridine derivatives, etc.), and azine derivatives (pyridine derivatives, pyrimidine derivatives, triazine derivatives, etc.). To metal complex compounds are preferred. The metal complex compound (A) is more preferably a metal complex having a ligand having at least one nitrogen atom, oxygen atom or sulfur atom coordinated to the metal.
The metal ion in the metal complex is not particularly limited, but is preferably beryllium ion, magnesium ion, aluminum ion, gallium ion, zinc ion, indium ion, tin ion, platinum ion, or palladium ion, more preferably beryllium ion, Aluminum ion, gallium ion, zinc ion, platinum ion, or palladium ion, and more preferably aluminum ion, zinc ion, or palladium ion.

  There are various known ligands contained in the metal complex. For example, “Photochemistry and Photophysics of Coordination Compounds”, Springer-Verlag, H.C. Examples include the ligands described in Yersin, published in 1987, “Organometallic Chemistry: Fundamentals and Applications”, Sakai Hanafusa, Yamamoto Akio, published in 1982, and the like.

The ligand is preferably a nitrogen-containing heterocyclic ligand (preferably having 1 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 3 to 15 carbon atoms, and a monodentate ligand. Alternatively, it may be a bidentate or higher ligand, preferably a bidentate or higher and a hexadentate or lower ligand, or a bidentate or higher and lower 6 or lower ligand and a monodentate mixed ligand. preferable.
Examples of the ligand include an azine ligand (for example, pyridine ligand, bipyridyl ligand, terpyridine ligand, etc.), a hydroxyphenylazole ligand (for example, hydroxyphenylbenzimidazole coordination). And a hydroxyphenyl benzoxazole ligand, a hydroxyphenyl imidazole ligand, a hydroxyphenylimidazopyridine ligand, etc.), an alkoxy ligand (preferably having 1 to 30 carbon atoms, more preferably 1 carbon atom). To 20, particularly preferably 1 to 10 carbon atoms, such as methoxy, ethoxy, butoxy, 2-ethylhexyloxy), aryloxy ligands (preferably 6 to 30 carbon atoms, more preferably 6-20 carbon atoms, particularly preferably 6-12 carbon atoms, for example phenyl Carboxymethyl, 1-naphthyloxy, 2-naphthyloxy, 2,4,6-trimethylphenyl oxy, and 4-biphenyloxy and the like.),

  Heteroaryloxy ligand (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include pyridyloxy, pyrazyloxy, pyrimidyloxy, and quinolyloxy. ), An alkylthio ligand (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio and ethylthio), arylthio ligands (Preferably 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio), heteroarylthio ligand (preferably 1 carbon atom) To 30, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as pyridylthio 2-benzimidazolylthio, 2-benzoxazolylthio, 2-benzthiazolylthio, etc.), siloxy ligands (preferably having 1 to 30 carbon atoms, more preferably 3 to 25 carbon atoms, Particularly preferably, it has 6 to 20 carbon atoms, and examples thereof include a triphenylsiloxy group, a triethoxysiloxy group, and a triisopropylsiloxy group.), An aromatic hydrocarbon anion ligand (preferably a carbon number of 6 to 6). 30, more preferably 6 to 25 carbon atoms, particularly preferably 6 to 20 carbon atoms, such as a phenyl anion, a naphthyl anion, an anthranyl anion, etc.), an aromatic heterocyclic anion ligand (preferably 1 to 30 carbon atoms, more preferably 2 to 25 carbon atoms, particularly preferably 2 to 20 carbon atoms. Anion, pyrazole anion, pyrazole anion, triazole anion, oxazole anion, benzoxazole anion, thiazole anion, benzothiazole anion, thiophene anion, benzothiophene anion, etc.), indolenine anion ligand, etc. Preferably it is a nitrogen-containing heterocyclic ligand, aryloxy ligand, heteroaryloxy group, or siloxy ligand, more preferably a nitrogen-containing heterocyclic ligand, aryloxy ligand, siloxy ligand , An aromatic hydrocarbon anion ligand, or an aromatic heterocyclic anion ligand.

  Examples of the metal complex electron transporting host are described in, for example, JP-A No. 2002-235076, JP-A No. 2004-214179, JP-A No. 2004-221106, JP-A No. 2004-221665, JP-A No. 2004-221068, JP-A No. 2004-327313, etc. The compound of this is mentioned.

  Further, the content of the host material in the present invention is not particularly limited, but from the viewpoint of light emission efficiency and driving voltage, it is 15% by mass or more and 95% by mass or less based on the total compound mass forming the light emitting layer. Preferably there is.

  The host material used in the present invention preferably has a glass transition point of 50 ° C. or higher and 150 ° C. or lower. More preferably, the glass transition point is 60 ° C. or higher and 150 ° C. or lower. If the glass transition point of the host material is less than 50 ° C., it is not preferable in terms of the heat resistance of the device, and if it exceeds 150 ° C., it is not preferable in that heat treatment after film formation becomes difficult.

  Among these, specific examples of the host material in the present invention include the specific compounds exemplified in paragraphs [0079] to [0083] of JP-A-2009-16579, and the host material 1 used in the examples described later. However, it is not limited to these.

(Hole injection layer, hole transport layer)
The hole injection layer and the hole transport layer are layers having a function of receiving holes from the anode or the anode side and transporting them to the cathode side.
In the present invention, at least one layer adjacent to the light emitting layer is preferably a hole transport layer, and two or more kinds of low molecular weight compounds having a molecular weight of 1500 or less are two or more kinds of hole transport materials. preferable. By mixing two or more kinds of compounds, it is possible to provide a coating type hole injection layer excellent in hole injection from the anode and hole injection into the light emitting layer. Further, by mixing two or more kinds of low molecular compounds, the thermal stability such as crystallization can be greatly increased, and the thermal stability of the device can be improved.
The difference in ionization potential between the two or more hole transport materials is preferably 0.1 eV or more and 0.6 eV or less, and more preferably 0.2 eV or more and 0.5 eV or less.
In the coating type element, a material such as PEDOT / PSS, an arylamine polymer, or a starburst amine type is generally used as the hole injection layer, but these have a low ionization potential. For this reason, the hole injection barrier from the anode such as ITO is small, but the hole injection barrier to the light emitting layer is large, which causes an increase in driving voltage and deterioration in durability. Although it is possible to provide a step layer between the hole injection layer and the light emitting layer to promote hole injection, two or more kinds of hole transports having a difference in ionization potential of 0.1 eV to 0.6 eV By using the material, the number of layers can be reduced and the cost can be further reduced.

Specifically, pyrrole derivatives, carbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styryl Anthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidin compounds, phthalocyanine compounds, porphyrin compounds, thiophene derivatives, organosilane derivatives, carbon, And the like.
In the present invention, the two or more hole transport materials preferably contain an arylamine derivative or a carbazole derivative, and preferably contain an arylamine derivative and a carbazole derivative. This is because these materials have a large hole transport property and are stable.

  An electron-accepting dopant can be contained in the hole injection layer or the hole transport layer of the organic EL device of the present invention. As the electron-accepting dopant introduced into the hole-injecting layer or the hole-transporting layer, an inorganic compound or an organic compound can be used as long as it has an electron-accepting property and oxidizes an organic compound.

  Specifically, examples of the inorganic compound include metal halides such as ferric chloride, aluminum chloride, gallium chloride, indium chloride, and antimony pentachloride, and metal oxides such as vanadium pentoxide and molybdenum trioxide.

In the case of an organic compound, a compound having a nitro group, halogen, cyano group, trifluoromethyl group or the like as a substituent, a quinone compound, an acid anhydride compound, fullerene, or the like can be preferably used.
In addition, JP-A-6-212153, JP-A-11-111463, JP-A-11-251067, JP-A-2000-196140, JP-A-2000-286054, JP-A-2000-315580, JP-A-2001-102175, JP-A-2001-2001. -160493, JP2002-252085, JP2002-56985, JP2003-157981, JP2003-217862, JP2003-229278, JP2004-342614, JP2005-72012, JP20051666667 The compounds described in JP-A-2005-209643 and the like can be preferably used.

  Among these, hexacyanobutadiene, hexacyanobenzene, tetracyanoethylene, tetracyanoquinodimethane, tetrafluorotetracyanoquinodimethane, p-fluoranyl, p-chloranil, p-bromanyl, p-benzoquinone, 2,6-dichlorobenzoquinone, 2 , 5-dichlorobenzoquinone, 1,2,4,5-tetracyanobenzene, 1,4-dicyanotetrafluorobenzene, 2,3-dichloro-5,6-dicyanobenzoquinone, p-dinitrobenzene, m-dinitrobenzene, o-dinitrobenzene, 1,4-naphthoquinone, 2,3-dichloronaphthoquinone, 1,3-dinitronaphthalene, 1,5-dinitronaphthalene, 9,10-anthraquinone, 1,3,6,8-tetranitrocarbazole, 2,4,7-trinitro-9- Luenone, 2,3,5,6-tetracyanopyridine, or fullerene C60 is preferred, and hexacyanobutadiene, hexacyanobenzene, tetracyanoethylene, tetracyanoquinodimethane, tetrafluorotetracyanoquinodimethane, p-fluoranyl, p- Chloranil, p-bromanyl, 2,6-dichlorobenzoquinone, 2,5-dichlorobenzoquinone, 2,3-dichloronaphthoquinone, 1,2,4,5-tetracyanobenzene, 2,3-dichloro-5,6-dicyano Benzoquinone or 2,3,5,6-tetracyanopyridine is more preferred, and tetrafluorotetracyanoquinodimethane is particularly preferred.

  These electron-accepting dopants may be used alone or in combination of two or more. Although the usage-amount of an electron-accepting dopant changes with kinds of material, it is preferable that it is 0.01 mass%-50 mass% with respect to hole transport layer material, and it is 0.05 mass%-20 mass%. It is further more preferable and it is especially preferable that it is 0.1 mass%-10 mass%.

The thicknesses of the hole injection layer and the hole transport layer are each preferably 500 nm or less from the viewpoint of lowering the driving voltage.
The thickness of the hole transport layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 100 nm. In addition, the thickness of the hole injection layer is preferably 0.1 nm to 200 nm, more preferably 0.5 nm to 100 nm, and still more preferably 1 nm to 100 nm.
The hole injection layer and the hole transport layer may have a single-layer structure composed of one or more of the materials described above, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions. .

(Electron injection layer, electron transport layer)
The electron injection layer and the electron transport layer are layers having a function of receiving electrons from the cathode or the cathode side and transporting them to the anode side.
In the present invention, it is preferable that at least one layer adjacent to the light emitting layer is an electron transport layer. Moreover, it is preferable that the electron carrying layer was formed with the liquid containing 2 or more types of electron carrying materials. By mixing two or more compounds, it is possible to provide a coating type electron injection layer excellent in electron injection from the cathode and electron injection into the light emitting layer.
The difference in electron affinity between two or more electron transport materials is preferably 0.1 eV or more and 0.6 eV or less, and more preferably 0.2 eV or more and 0.5 eV or less.
Specifically, pyridine derivatives, quinoline derivatives, pyrimidine derivatives, pyrazine derivatives, phthalazine derivatives, phenanthroline derivatives, triazine derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, fluorenone derivatives, anthraquinodimethane derivatives, anthrone Derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimide derivatives, fluorenylidenemethane derivatives, distyrylpyrazine derivatives, naphthalene, perylene and other aromatic ring tetracarboxylic acid anhydrides, phthalocyanine derivatives, 8-quinolinol derivative metal complexes, Metal phthalocyanines, various metal complexes represented by metal complexes with benzoxazole and benzothiazole as ligands, organosilane derivatives represented by siloles Body, or the like is preferably a layer containing.

  The electron injection layer or the electron transport layer of the organic EL device of the present invention can contain an electron donating dopant. The electron donating dopant introduced into the electron injecting layer or the electron transporting layer only needs to have an electron donating property and a property of reducing an organic compound, such as an alkali metal such as Li or an alkaline earth metal such as Mg. Transition metals including rare earth metals and reducing organic compounds are preferably used. As the metal, a metal having a work function of 4.2 eV or less can be preferably used. Specifically, Li, Na, K, Be, Mg, Ca, Sr, Ba, Y, Cs, La, Sm, Gd , And Yb. Examples of the reducing organic compound include nitrogen-containing compounds, sulfur-containing compounds, and phosphorus-containing compounds. In addition, materials described in JP-A-6-212153, JP-A-2000-196140, JP-A-2003-68468, JP-A-2003-229278, JP-A-2004-342614, and the like can be used.

  These electron donating dopants may be used alone or in combination of two or more. The amount of the electron donating dopant varies depending on the type of material, but is preferably 0.1% by mass to 99% by mass, and 1.0% by mass to 80% by mass with respect to the electron transport layer material. Is more preferable, and 2.0 mass% to 70 mass% is particularly preferable.

The thicknesses of the electron injection layer and the electron transport layer are each preferably 500 nm or less from the viewpoint of lowering the driving voltage.
The thickness of the electron transport layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 100 nm. In addition, the thickness of the electron injection layer is preferably 0.1 nm to 200 nm, more preferably 0.2 nm to 100 nm, and still more preferably 0.5 nm to 50 nm.
The electron injection layer and the electron transport layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

(Hole blocking layer)
The hole blocking layer is a layer having a function of preventing holes transported from the anode side to the light emitting layer from passing through to the cathode side. In the present invention, a hole blocking layer can be provided as an organic compound layer adjacent to the light emitting layer on the cathode side.
Examples of the compound constituting the hole blocking layer include aluminum complexes such as bis (2-methyl-8-quinolinolato) (phenolate) aluminum, triazole derivatives, 2,9-dimethyl-4,7-diphenyl-1,10. -Phenanthroline derivatives such as phenanthroline, and the like.
The thickness of the hole blocking layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 100 nm.
The hole blocking layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

(Electronic block layer)
The electron blocking layer is a layer having a function of preventing electrons transported from the cathode side to the light emitting layer from passing through to the anode side. In the present invention, an electron blocking layer can be provided as the organic compound layer adjacent to the light emitting layer on the anode side.
As examples of the compound constituting the electron blocking layer, for example, those mentioned as the hole transport material described above can be applied.
The thickness of the electron blocking layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and even more preferably 10 nm to 100 nm.
The hole blocking layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

(Purification of materials)
As the material constituting the organic layer of the organic electroluminescent element, it is preferable to use a purified material, and it is more preferable that at least one material is a material purified by a zone melt method. The zone melt method is difficult to purify by sublimation, easily decomposes, easily purifies a material having a high sublimation temperature, or a relatively high molecular weight. A material suitable for the wet film forming method has high amorphousness and is difficult to be purified by sublimation. When purification is performed by sublimation, device performance may be lowered.

A device with high performance can be realized by combining purification by the zone melt method and wet film formation. In particular, by combining with spray coating, a more durable and efficient device can be realized.
Further, at least one or more materials are materials purified by a zone melt method, and an organic electroluminescent element produced by a wet film forming method (preferably a spray coating method) is more preferable.
A material that can be efficiently subjected to zone melt purification can be formed cleanly (smoothly) without any disturbance at the interface of the formed layer. This is because zone melt purification has a lower purification temperature than sublimation purification. The coating process temperature is usually closer to that of zone melt purification. That is, a material that can efficiently perform zone melt purification can form a film with less disorder in the coating process. When there is little disorder of the arrangement of the film, it is expected to improve the light emission efficiency and durability of the produced organic electroluminescence device.
The Tg of the material is preferably in the range of 100 ° C to 400 ° C. The material is preferably a charge injection material, a charge transport material, a host material, or a light emitting material, and more preferably a carbazole derivative, an arylamine derivative, or a metal complex.

(Protective layer)
In the present invention, the entire organic EL element may be protected by a protective layer. As a material contained in the protective layer, any material may be used as long as it has a function of preventing materials that promote device deterioration such as moisture and oxygen from entering the device.
Specific examples thereof include metals such as In, Sn, Pb, Au, Cu, Ag, Al, Ti, and Ni, MgO, SiO, SiO ₂ , Al ₂ O ₃ , GeO, NiO, CaO, BaO, and Fe ₂ O. ₃ , metal oxides such as Y ₂ O ₃ , TiO ₂ , metal nitrides such as SiN _x , SiN _x O _y , metal fluorides such as MgF ₂ , LiF, AlF ₃ , CaF ₂ , polyethylene, polypropylene, polymethyl Monomer mixture containing methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene, tetrafluoroethylene and at least one comonomer Copolymer obtained by copolymerization, cyclic in the copolymer main chain Examples thereof include a fluorine-containing copolymer having a structure, a water-absorbing substance having a water absorption of 1% or more, and a moisture-proof substance having a water absorption of 0.1% or less.

  The method for forming the protective layer is not particularly limited, and for example, vacuum deposition, sputtering, reactive sputtering, MBE (molecular beam epitaxy), cluster ion beam, ion plating, plasma polymerization (high frequency) Excited ion plating method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, coating method, printing method, transfer method can be applied.

(Sealing)
Furthermore, the organic EL device of the present invention may be sealed using a sealing container. Further, a moisture absorbent or an inert liquid may be sealed in a space between the sealing container and the light emitting element. Although it does not specifically limit as a moisture absorber, For example, barium oxide, sodium oxide, potassium oxide, calcium oxide, sodium sulfate, calcium sulfate, magnesium sulfate, phosphorus pentoxide, calcium chloride, magnesium chloride, copper chloride Cesium fluoride, niobium fluoride, calcium bromide, vanadium bromide, molecular sieve, zeolite, and magnesium oxide. The inert liquid is not particularly limited, and examples thereof include paraffins, liquid paraffins, fluorinated solvents such as perfluoroalkane, perfluoroamine, and perfluoroether, chlorinated solvents, and silicone oils. Can be mentioned.

  Also, seal with inorganic sealing with silicon oxide, silicon dioxide, silicon nitride, silicon oxynitride, aluminum oxide, etc. or resin sealing with acrylic resin, epoxy resin, fluororesin, silicon resin, rubber resin, ester resin, etc. A method of stopping is also preferably used.

(Sealing adhesive)
The sealing adhesive used in the present invention has a function of preventing intrusion of moisture and oxygen from the end portion.
<Material>
As the material of the sealing adhesive, the same material as that used for the resin sealing layer can be used. Among these, epoxy adhesives are preferable from the viewpoint of moisture prevention, and among them, a photocurable adhesive or a thermosetting adhesive is preferable.

It is also preferable to add a filler to the above material.
The filler added to the sealant is preferably an inorganic material such as SiO ₂ , SiO (silicon oxide), SiON (silicon oxynitride) or SiN (silicon nitride). By adding the filler, the viscosity of the sealant is increased, the processing suitability is improved, and the moisture resistance is improved.

<Prescription of sealing adhesive>
-Polymer composition, density | concentration It does not specifically limit as a sealing adhesive agent, The said thing can be used.
For example, XNR5516 manufactured by Nagase Chemtech Co., Ltd. can be cited as a photo-curable epoxy adhesive.
-Thickness The coating thickness of the sealing adhesive is preferably 1 μm or more and 1 mm or less. If it is thinner than this, the sealing adhesive cannot be applied uniformly, which is not preferable. On the other hand, if it is thicker than this, the route through which moisture invades becomes wide, which is not preferable.
<Sealing method>
In the present invention, a functional element can be obtained by applying an arbitrary amount of the sealing adhesive with a dispenser or the like, and stacking and curing the second substrate after application.

(Drive)
The organic EL device of the present invention obtains light emission by applying a direct current (which may include an alternating current component if necessary) voltage (usually 2 to 15 volts) or a direct current between the anode and the cathode. be able to.
Regarding the driving method of the organic EL device of the present invention, each of JP-A-2-148687, JP-A-6-301355, JP-A-5-290080, JP-A-7-134558, JP-A-8-234658, and JP-A-8-2441047. The driving methods described in the publications, Japanese Patent No. 2784615, US Pat. Nos. 5,828,429 and 6023308, and the like can be applied.

  The light-emitting element of the present invention can improve the light extraction efficiency by various known devices. For example, by processing the substrate surface shape (for example, forming a fine concavo-convex pattern), controlling the refractive index of the substrate / ITO layer / organic layer, controlling the film thickness of the substrate / ITO layer / organic layer, etc. It is possible to improve light extraction efficiency and external quantum efficiency.

  The light-emitting element of the present invention may be a so-called top emission type in which light emission is extracted from the anode side.

The organic EL element in the present invention may have a resonator structure. For example, a multilayer mirror made of a plurality of laminated films having different refractive indexes, a transparent or translucent electrode, a light emitting layer, and a metal electrode are superimposed on a transparent substrate. The light generated in the light emitting layer resonates repeatedly with the multilayer mirror and the metal electrode as a reflection plate.
In another preferred embodiment, a transparent or translucent electrode and a metal electrode each function as a reflecting plate on a transparent substrate, and light generated in the light emitting layer repeats reflection and resonates between them. In order to form a resonant structure, the optical path length determined from the effective refractive index of the two reflectors and the refractive index and thickness of each layer between the reflectors is adjusted to an optimum value to obtain the desired resonant wavelength. Is done. The calculation formula in the case of the first embodiment is described in JP-A-9-180883. The calculation formula in the case of the second aspect is described in Japanese Patent Application Laid-Open No. 2004-127795.

For example, as described in “Monthly Display”, September 2000, pages 33 to 37, a method for making an organic EL display of a full color type includes three primary colors (blue (B) and green). (G), red light (R)), a three-color light emitting method in which organic EL elements that emit light corresponding to red (R) are arranged on a substrate, and white light emitted by a white light emitting organic EL element into three primary colors through a color filter. And a color conversion method in which blue light emission by an organic EL element for blue light emission is converted into red (R) and green (G) through a fluorescent dye layer are known.
Moreover, the planar light source of a desired luminescent color can be obtained by using combining the organic EL element of the different luminescent color obtained by the said method. For example, a white light-emitting light source that combines blue and yellow light-emitting elements, a white light-emitting light source that combines blue, green, and red light-emitting elements.

(application)
The organic EL device and manufacturing method of the present invention are used in a wide range of fields including digital still camera displays, mobile phone displays, personal digital assistants (PDAs), computer displays, automobile information displays, TV monitors, or general lighting. Applied.

(Display device)
Next, a display device according to an embodiment of the present invention will be described with reference to FIG.
FIG. 2 is a cross-sectional view schematically showing an example of the display device according to the embodiment of the present invention.
As shown in FIG. 2, the display device 20 according to the embodiment of the present invention includes a transparent substrate (support substrate) 2, an organic EL element 10, a sealing container 16, and the like.

The organic EL element 10 is configured by sequentially laminating an anode (first electrode) 3, an organic layer 11, and a cathode (second electrode) 9 on a substrate 2. A protective layer 12 is laminated on the cathode 9, and a sealing container 16 is provided on the protective layer 12 with an adhesive layer 14 interposed therebetween. In addition, a part of each electrode 3 and 9, a partition, an insulating layer, etc. are abbreviate | omitted.
Here, the adhesive layer 14 is preferably a layer made of the sealing adhesive described above.
Such a display device 20 displays light emitted from the organic EL element 10 with the surface opposite to the anode 3 of the substrate 2 as a display surface.

(Lighting device)
Next, an illumination device according to an embodiment of the present invention will be described with reference to FIG.
FIG. 3 is a cross-sectional view schematically showing an example of a lighting device according to an embodiment of the present invention.
As shown in FIG. 3, the illumination device 40 according to the embodiment of the present invention includes the organic EL element 10 and the light scattering member 30 described above. More specifically, the lighting device 40 is configured such that the substrate 2 of the organic EL element 10 and the light scattering member 30 are in contact with each other.
The light scattering member 30 is not particularly limited as long as it can scatter light. In FIG. 3, the light scattering member 30 is a member in which fine particles 32 are dispersed on a transparent substrate 31. As the transparent substrate 31, for example, a glass substrate can be preferably cited. As the fine particles 32, transparent resin fine particles can be preferably exemplified. As the glass substrate and the transparent resin fine particles, known ones can be used. In such an illuminating device 40, when light emitted from the organic EL element 10 is incident on the light incident surface 30A of the light scattering member 30, the incident light is scattered by the light scattering member 30, and the scattered light is emitted from the light emitting surface 30B. It is emitted as illumination light.

The present invention will be described more specifically with reference to the following examples. The materials, reagents, substance amounts and ratios, operations, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention is not limited to the following specific examples.
(Preparation of coating solution)
20% by mass of molecular sieves 4A / 8X previously dried under reduced pressure (200 ° C. × 1 hour, 0.1 atm) was added and left for 1 hour. A deoxygenation treatment by nitrogen bubbling was performed in a nitrogen-substituted glove box (dew point -68 degrees, oxygen concentration 10 ppm), and a filter (pore size 0.2 μm, PTFE membrane filter) treatment was performed to prepare a coating solution.
(Spray application machine)
A spray coating machine installed in a glove box (dew point −45 ° C., oxygen concentration 50 ppm) is supplied with nitrogen (purity 99.9%, dew point −40 ° C. or less) as a supply source, gas filter: SFB100-02 (SMC stock) Connected via company product name).

[Example 1]
A glass substrate (manufactured by Geomat Co., Ltd., surface resistance 10Ω / □, size: 0.5 mm thickness, 2.5 cm square) having a vapor deposition layer of indium tin oxide (abbreviated as ITO) is placed in a cleaning container, After ultrasonic cleaning with, UV-ozone treatment was performed for 30 minutes. The following layers were sequentially provided on the transparent anode by a spray method. In forming each layer, the aerosol carrier gas was nitrogen gas, and the amount of carrier gas was 1 L / min. Further, the particle diameter of the liquid particles in the aerosol was set to 1 μm.

(1) Hole transport layer (50 nm): The following hole transport material 1 and hole transport material 2 are formed by a spray method.
After applying a dichloromethane solution (solid content concentration: 1% by mass) of (mass ratio: 50/50) on the transparent anode in such an amount that the thickness of the resulting hole transport layer is 50 nm, 70 ° C., 1 hour Was vacuum dried. In addition, as the hole transport material 1 and the hole transport material 2, those purified by sublimation purification were used. Difference in ionization potential between hole transport material 1 and hole transport material 2: ΔIp = 0.4 eV.

(2) Light-emitting layer (40 nm): A xylene solution (solid content concentration: 0.6% by mass) containing the host material 1: CDBP and the light-emitting material 1: compound A at a mass ratio of 95: 5 is obtained by a spray method. After coating on the hole transport layer in such an amount that the resulting light emitting layer had a thickness of 40 nm, vacuum drying was performed at 100 ° C. for 1 hour. In addition, as the host material 1 and the light emitting material 1, those purified by sublimation purification were used.

(3) Electron transport layer (30 nm): The substrate was attached to a vacuum deposition apparatus without being exposed to the atmosphere. Further, a molybdenum resistance heating boat with BAlq placed therein is attached to a vacuum deposition apparatus, and after the vacuum chamber is depressurized to 4 × 10 ⁻⁴ Pa, the boat is energized and heated to heat PBD (2- (4- Biphenylyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole) is vapor-deposited on the light-emitting layer at a vapor deposition rate of 0.2 nm / second to form an electron transport layer having a thickness of 30 nm. Formed.

(4) Electron injection layer (1 nm): LiF was deposited on the electron transport layer in an amount such that the thickness of the resulting electron injection layer was 1 nm by vacuum evaporation.
(5) Cathode (100 nm): Aluminum (Al) was deposited on the electron injection layer in an amount such that the thickness of the obtained cathode was 100 nm by vacuum deposition.

  The prepared laminate was put in a glove box substituted with argon gas and sealed with a stainless steel sealing can and an ultraviolet curable adhesive (XNR5516 manufactured by Nagase Chemtech Co., Ltd.). 1 organic EL element was produced.

[Examples 2 and 3 and Comparative Examples 1 and 2]
In Example 1, the same procedure as in Example 1 was performed except that the mass ratio of the hole transport material 1 and the hole transport material 2 in the hole transport layer was changed to the ratio shown in Table 1. 2, 3 and the organic EL element of Comparative Examples 1-2 was formed.

[Comparative Example 3]
In Example 1, the organic EL element of the comparative example 3 was formed by performing the same procedure as Example 1 except having replaced the hole transport layer with the following hole transport layers.
(1) Hole transport layer (50 nm): The substrate was attached to a vacuum deposition apparatus without being exposed to the atmosphere. Moreover, the hole transport material 1 and the hole transport material 2 were installed in the molybdenum resistance heating boat, respectively. After depressurizing the vacuum chamber to 4 × 10 ⁻⁵ Pa, the boat is energized and heated to adjust the deposition rate so that the weight ratio of the hole transport material 1 and the hole transport material 2 is 50:50. The hole transport layer having a film thickness of 50 nm was formed by vapor deposition on the substrate.

[Comparative Example 4]
In Example 1, the organic EL element of the comparative example 3 was formed by performing the same procedure as Example 1 except having replaced the hole transport layer with the following hole transport layers.
(1) Hole transport layer (50 nm): A dichloromethane solution (solid content concentration: 1% by mass) of the following hole transport material 1 and hole transport material 2 (mass ratio: 50/50) by spin coating, After coating on the transparent anode in such an amount that the thickness of the resulting hole transport layer was 50 nm, vacuum drying was performed at 70 ° C. for 1 hour. In addition, as the hole transport material 1 and the hole transport material 2, those purified by sublimation purification were used.

(Evaluation of organic EL elements)
The obtained organic EL elements of Examples and Comparative Examples were evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1.

<Luminous efficiency>
A DC voltage was applied to the light emitting element using the source measure unit 2400 type manufactured by KEITHLEY, and the produced organic EL element was caused to emit light with a luminance of 1000 cd / m ² . The emission spectrum and the amount of light were measured using a luminance meter SR-3 manufactured by Topcon Corporation, and the external quantum efficiency was calculated from the emission spectrum, the amount of light and the current at the time of measurement.

<Drive voltage>
A DC voltage was applied to the light emitting element using the source measurement unit 2400 type manufactured by KEITHLEY, and the voltage reaching the light emission luminance of 1000 cd / m ² was evaluated as a driving voltage.

<Durability>
The produced organic EL device was subjected to a continuous drive test under a condition of initial luminance of 1000 cd / m ² by applying a DC voltage to the light emitting device using a KEITHLEY source measure unit 2400 type. For the endurance time to obtain 500 cd / m ^2, and the relative values were compared using Comparative Example 1 as a reference.

[Examples 4 to 6 and Comparative Examples 5 to 6]
In Example 1, the hole transporting material was changed to the hole transporting material 3 and the hole transporting material 4 listed in Table 2, and the same procedure as in Example 1 was performed except that the ratio in Table 2 was changed. The organic EL elements of Examples 4 to 6 and Comparative Example were formed. Difference in ionization potential between the hole transport material 3 and the hole transport material 4: ΔIp was 0.3 eV.
In addition, about brightness half time. Relative comparison was performed on the basis of Comparative Example 5.

[Comparative Example 7]
In Comparative Example 3, the same procedure as in Comparative Example 3 was performed except that the hole transporting material was changed to the hole transporting material 3 and the hole transporting material 4 shown in Table 2, so that the organic EL element of Comparative Example 7 was used. Formed.
[Comparative Example 8]
In Comparative Example 4, the same procedure as in Comparative Example 4 was performed except that the hole transporting material was changed to the hole transporting material 3 and the hole transporting material 4 shown in Table 2, so that the organic EL device of Comparative Example 8 was used. Formed.

Example 7
In Example 1, the same procedure as in Example 1 was performed except that the hole transport material 1 and the hole transport material 2 were replaced with the following hole transport material 1 and hole transport material 5, whereby An organic EL element was formed. Difference in ionization potential between hole transport material 1 and hole transport material 5: ΔIp was 0.2 eV.

Example 8
In Example 1, the same procedure as in Example 1 was performed except that the hole transport material 1 and the hole transport material 2 were replaced with the following hole transport material 1 and hole transport material 6, whereby Example 8 An organic EL element was formed. Difference in ionization potential between the hole transport material 1 and the hole transport material 6: ΔIp was 0.1 eV.

Example 9
In Example 1, the same procedure as in Example 1 was performed except that the hole transport material 1 and the hole transport material 2 were replaced with the following hole transport material 1 and hole transport material 7, whereby Example 9 An organic EL element was formed. Difference in ionization potential between hole transport material 1 and hole transport material 7: ΔIp was 0.6 eV.
In addition, about the brightness | luminance half time of (Examples 7-9), relative comparison was performed on the basis of the comparative example 1. FIG.

[Comparative Example 9]
In Example 1, the hole transport material 1 and the hole transport material 2 of the hole transport layer were changed to the following hole transport material 1 and hole transport material 8 (PTPDES 2: manufactured by Chemipro Kasei Co., Ltd., mass average molecular weight: 15,000). The organic EL element of Comparative Example 9 was formed by performing the same procedure as in Example 1 except that the change was made. Difference in ionization potential between hole transport material 1 and hole transport material 8: ΔIp was 0.1 eV.
In addition, about brightness half time. Relative comparison was performed using Comparative Example 1 as a reference.

[Comparative Example 10]
In Example 1, the hole transport material 1 and the hole transport material 2 of the hole transport layer were changed to the following hole transport material 2 and hole transport material 8 (PTPDES 2: manufactured by Chemipro Kasei Co., Ltd., mass average molecular weight: 15,000). The organic EL element of the comparative example 10 was formed by performing the same procedure as Example 1 except having changed. Difference in ionization potential between the hole transport material 2 and the hole transport material 8: ΔIp was 0.5 eV.
In addition, about brightness half time. Relative comparison was performed using Comparative Example 1 as a reference.

Example 10
In Example 1, except that the hole transport layer, the light emitting layer, and the electron transport layer were replaced with the following hole transport layer and electron transport layer, the same procedure as in Example 1 was performed, whereby An organic EL element was formed. Difference in electron affinity between the electron transport material 1 and the electron transport material 2: ΔEa was 0.4 eV.

(1) Hole transport layer (50 nm): An aqueous solution of a PEDOT-PSS solution ((polyethylenedioxythiophene-polystyrene sulfonic acid dope) / (Bayer's AI4083, mass average molecular weight: 100,000)) by a spray method. (Solid content concentration: 1% by mass) was applied onto the transparent anode in such an amount that the resulting hole transport layer had a thickness of 50 nm, and then vacuum dried at 150 ° C. for 5 hours.
(2) Light-emitting layer (40 nm): A xylene solution (solid content concentration: 1% by mass) containing the following host 2 and light-emitting material 2 at a mass ratio of 95: 5 is obtained by a spray method. After coating on the hole transport layer in such an amount, vacuum drying was performed at 100 ° C. for 1 hour. In addition, as the host material 1 and the light emitting material 1, those purified by sublimation purification were used.
(3) Electron transport layer (30 nm): an electron transport layer obtained by a toluene solution (solid content concentration: 1% by mass) containing the electron transport material 1 and the electron transport material 2 at a mass ratio of 50:50 by a spray method. After coating on the light emitting layer in such an amount that the thickness of the film became 30 nm, vacuum drying was performed at 100 ° C. for 1 hour. In addition, as the electron transport material 1 and the electron transport material 2, those purified by sublimation purification were used.

[Examples 11 and 12 and Comparative Examples 11 to 12]
In Example 10, the same procedure as in Example 10 was performed except that the mass ratio of the electron transport material 1 and the electron transport material 2 in the electron transport layer was changed to the ratio shown in Table 6, so that Examples 11 and 12 were performed. And the organic EL element of Comparative Examples 11-12 was formed.

[Comparative Example 13]
In Example 10, the organic EL element of the comparative example 13 was formed by performing the same procedure as Example 10 except having replaced the electron carrying layer with the following electron carrying layers.
(3) Electron transport layer (30 nm): The substrate was attached to a vacuum deposition apparatus without being exposed to the atmosphere. Moreover, the electron transport material 1 and the electron transport material 2 were installed in the resistance heating boat made from molybdenum, respectively. After depressurizing the vacuum chamber to 4 × 10 ⁻⁵ Pa, the boat is energized and heated to adjust the deposition rate so that the weight ratio of the electron transport material 1 and the electron transport material 2 is 50:50, It vapor-deposited on the board | substrate and formed the 30-nm-thick electron carrying layer.
[Comparative Example 14]
In Example 10, the organic EL element of the comparative example 14 was formed by performing the same procedure as Example 10 except having replaced the electron carrying layer with the following electron carrying layers.
(3) Electron transport layer (50 nm): Holes obtained from a toluene solution (solid content concentration: 1% by mass) of electron transport material 1 and electron transport material 2 (mass ratio: 50/50) by spin coating. After coating on light emission in such an amount that the thickness of the transport layer was 30 nm, vacuum drying was performed at 100 ° C. for 1 hour. In addition, the electron transport material 1 and the electron transport material 2 used what was refine | purified by sublimation refinement | purification.
In addition, about brightness half time. Relative comparison was performed using Comparative Example 11 as a reference.

Example 13
In Example 10, the same procedure as in Example 10 was performed, except that the electron transport material 1 and the electron transport material 2 of the electron transport layer were replaced with the electron transport material 2 and the electron transport material 3 of the following electron transport layer. The organic EL device of Example 13 was formed. Difference in electron affinity between the electron transport material 2 and the electron transport material 3: ΔEa was 0.2 eV.

Example 14
In Example 10, the same procedure as in Example 10 was performed except that the electron transport material 1 and the electron transport material 2 of the electron transport layer were replaced with the electron transport material 1 and the electron transport material 3 of the following electron transport layer. The organic EL element of Example 14 was formed. Difference in electron affinity between the electron transport material 1 and the electron transport material 3: ΔEa was 0.6 eV.

Example 15
In Example 10, the same procedure as in Example 10 was performed except that the electron transport material 1 and the electron transport material 2 of the electron transport layer were replaced with the electron transport material 3 and the electron transport material 4 of the following electron transport layer, The organic EL element of Example 15 was formed. Difference in electron affinity between the electron transport material 3 and the electron transport material 4: ΔEa was 0.1 eV.
In addition, about the brightness | luminance half time of (Examples 13-15). Relative comparison was performed using Comparative Example 11 as a reference.

[Comparative Example 15]
In Example 10, the same procedure as in Example 10 was performed, except that the electron transport material 1 and the electron transport material 2 of the electron transport layer were replaced with only the electron transport material 3 of the electron transport layer, whereby Comparative Example 12 An organic EL element was formed.

[Comparative Example 16]
In Example 10, the same procedure as in Example 10 was performed except that the electron transport material 1 and the electron transport material 2 in the electron transport layer were replaced with only the electron transport material 4 in the electron transport layer, whereby Comparative Example 13 An organic EL element was formed.
In addition, about the brightness | luminance half time of (Comparative Examples 15-16). Relative comparison was performed using Comparative Example 11 as a reference.

Example 16
(Thermal stability test)
The organic EL elements of Examples 1, 2, and 3 and the organic EL elements of Comparative Examples 1 and 2 were each heat-treated at 110 ° C. for 24 hours, and the light emission efficiency and driving voltage before and after that were evaluated. The results are shown in Table 9.

  In the EL elements of Examples 1 to 3, since the hole transport material 1 and the hole transport material 2 are mixed, even when heat treatment is performed at 110 ° C., both the external quantum efficiency and the driving voltage are small. On the other hand, in Comparative Example 1 and Comparative Example 2, the hole transport material 1 or the hole transport material 2 is used alone, and heat treatment is performed at a temperature higher than these Tg, so that the external quantum efficiency and the driving voltage are increased. Deteriorated significantly. (Tg (hole transport material 1): 95 ° C., Tg (hole transport material 2): 97 ° C.)

Example 201
(Purification by zone melt method)
10 g of the following compound 201-1 is put into a 10 mm diameter Pyrex (registered trademark) tube, and vacuum sealed at 10 Pa using an oil rotary pump.

Next, it refine | purified by making it descend | fall at the moving speed | rate of 1 cm / min and the melting zone of 4 cm by the descending zone melt method. The obtained compound was taken out under an inert atmosphere, stored in a light-shielded, inert atmosphere.
Similarly, compound 201-2 was purified by the zone melt method.

(Preparation of hole transport layer coating solution 201)
5 parts by mass of the compound 201-1 and 5 parts by mass of the compound 201-2 were dissolved in 990 parts by mass of xylene for electronic industry (manufactured by Kanto Chemical Co., Ltd.) to prepare a hole transport layer coating solution 201.

(Preparation of organic EL element 201)
A transparent support substrate was obtained by depositing ITO to a thickness of 150 nm on a 25 mm × 25 mm × 0.7 mm glass substrate. This transparent support substrate was etched and washed.
On this ITO glass substrate, a coating solution in which 2 parts by mass of PTPDES-2 (manufactured by Chemipro Kasei) and 98 parts by mass of cyclohexanone were spin-coated and dried to form a hole injection layer (film) Thickness about 40 nm).
On top of this, a film was formed by spray coating using the hole transport layer coating solution 201 to form a hole transport layer (film thickness of about 20 nm). Drying was performed under vacuum at 120 ° C. for 1 hour.
Next, a light emitting layer was formed thereon by a vacuum deposition method so that CBP as a host material and Ir (ppy) ₃ as a light emitting material were in a weight ratio of 95: 5.
Next, BAlq was vapor-deposited thereon with a film thickness of 40 nm by a vacuum vapor deposition method to form an electron injection layer. And 1 nm of lithium fluoride was vapor-deposited on this, and also metal aluminum was vapor-deposited 70 nm, and it was set as the cathode.
The produced laminate was put in a glove box substituted with argon gas, and sealed with a stainless steel sealing can and an ultraviolet curable adhesive (XNR5516HV, manufactured by CHIBA NAGASE Co., Ltd.).

[Comparative Example 201-1]
(Preparation of hole transport layer coating solution 201-1)
Compound 201-1 was mixed and dissolved in 10 parts by mass and 990 parts by mass of xylene for electronics industry (manufactured by Kanto Chemical Co., Ltd.) to prepare a hole transport layer coating solution 201-1.
(Preparation of comparative organic EL element 201-1)
An organic EL element 201-1 was produced in the same manner as in Example 201 except that the hole transport layer coating solution was changed to 201-1.

[Comparative Example 201-2]
(Preparation of hole transport layer coating solution 201-2)
Compound 202-1 was mixed and dissolved in 10 parts by mass and 990 parts by mass of xylene for electronics industry (manufactured by Kanto Chemical Co., Ltd.) to prepare a hole transport layer coating solution 201-1.
(Preparation of comparative organic EL element 201-2)
An organic EL element 201-2 was produced in the same manner as in Example 201 except that the hole transport layer coating solution was changed to 201-2.

(Element evaluation)
The obtained devices were evaluated for external quantum efficiency and device durability according to the above-described evaluation criteria. In addition, the evaluation result was shown by the relative value on the basis of the value of Comparative Example 201-2 in the following Table 10.

  It was confirmed that the external quantum efficiency and device durability were improved by using a hole transport layer obtained by mixing two kinds of compounds obtained by zone melt purification.

2 Substrate 3 Anode 4 Hole injection layer 5 Hole transport layer 6 Light emitting layer 7 Hole blocking layer 8 Electron transport layer 9 Cathode 10 Organic EL element 11 Sealing container 12 Protective layer 14 Adhesive layer 20 Display device 30 Light scattering member 30A Light entrance surface 30B Light exit surface 31 Transparent substrate 32 Fine particles 40 Illumination device

Claims (10)

An organic electroluminescent device having a light emitting layer and at least one layer adjacent to the light emitting layer between a pair of electrodes,
The at least one layer adjacent to the light emitting layer is formed by a spray method using a liquid containing two or more kinds of low molecular compounds having a molecular weight of 1500 or less ,
The two or more kinds of low molecular weight compounds having a molecular weight of 1500 or less are two or more kinds of hole transport materials,
The difference in ionization potential between the two or more hole transport materials is 0.1 eV or more and 0.6 eV or less,
2. The organic electroluminescence device according to claim 2, wherein the two or more hole transport materials are arylamine derivatives or carbazole derivatives .   The organic electroluminescence device according to claim 1, wherein the at least one layer adjacent to the light emitting layer is a hole transport layer.   The two or more kinds of low molecular weight compounds having a molecular weight of 1500 or less are two kinds of compounds of a first low molecular weight compound and a second low molecular weight compound, and the mixing ratio is 20:80 to 80:20 in mass ratio. The organic electroluminescent element according to claim 1, wherein the organic electroluminescent element is provided. The organic electroluminescent element according to claim 1, wherein the at least one layer adjacent to the light emitting layer is an electron transport layer. The organic electroluminescent element according to claim 4, wherein the electron transport layer is formed of a liquid containing two or more kinds of electron transport materials. The organic electroluminescence device according to claim 5, wherein a difference in electron affinity between the two or more electron transport materials is 0.1 eV or more and 0.6 eV or less. A method for producing an organic electroluminescent device comprising a light emitting layer and at least one layer adjacent to a light emitting layer between a pair of electrodes,
The layer adjacent to the at least one light emitting layer is formed by a spray method using a liquid containing two or more low molecular weight compounds having a molecular weight of 1500 or less,
The two or more kinds of low molecular weight compounds having a molecular weight of 1500 or less are two or more kinds of hole transport materials,
The difference in ionization potential between the two or more hole transport materials is 0.1 eV or more and 0.6 eV or less,
The method for producing an organic electroluminescent device, wherein the two or more hole transport materials are arylamine derivatives or carbazole derivatives. 8. The method of manufacturing an organic electroluminescent element according to claim 7, wherein each of the light emitting layer and the layer adjacent to the light emitting layer is formed by the spray method. A display device comprising the organic electroluminescent element according to claim 1 or the organic electroluminescent element obtained from the method for producing an organic electroluminescent element according to claim 7 or 8. The illuminating device which comprises the organic electroluminescent element in any one of Claims 1-6, or the organic electroluminescent element obtained from the manufacturing method of the organic electroluminescent element of Claim 7 or 8.

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