JP5572004B2 - White organic electroluminescence device - Google Patents

Description

  The present invention relates to an organic electroluminescent element that emits white light (hereinafter also referred to as “organic electroluminescence element” or “organic EL element”).

  Organic electroluminescent devices have features such as self-emission and high-speed response, and are expected to be applied to lighting, backlights of liquid crystal displays, etc. Since a two-layer type (laminated type) in which an electron-transporting organic thin film (electron transport layer) is laminated has been reported, it has attracted attention as a large-area light-emitting device that emits light at a low voltage of 10 V or less. The stacked organic electroluminescent element has a basic configuration of positive electrode / hole transport layer / light emitting layer / electron transport layer / negative electrode.

  By the way, when using an organic electroluminescent element as illumination, a backlight of a liquid crystal display, etc., white light is required. Since white light cannot be obtained by light emission of a single light emitting material, white light is obtained by mixing a plurality of light emitting materials. For example, two or three kinds of light emitting materials are combined into one organic material. A method of obtaining white light by emitting light simultaneously in an electroluminescent element is common.

  However, this method has a problem that chromaticity control is difficult, reproducibility is poor, and chromaticity changes are likely to occur. Moreover, there also existed a problem that luminous efficiency was bad and it was inferior to durability.

  In order to solve such a problem, an organic electroluminescence device having a tandem structure that has high luminous efficiency even at low voltage and can improve durability because of low voltage has been proposed. An organic electroluminescence device having a tandem structure including a plurality of units each having a light emitting layer that emits white light has been proposed (Patent Document 1).

  However, this proposal has a problem that although the luminous efficiency and durability are improved, the change in chromaticity cannot be sufficiently suppressed. In addition, there is a problem that the color fluctuates corresponding to the position of the observer with respect to the organic electroluminescent element (angle dependency of chromaticity).

  Accordingly, there is a strong demand for prompt development of a white organic electroluminescent device capable of achieving both luminous efficiency, durability, chromaticity change, and angular dependency of chromaticity.

Special table 2008-511100 gazette

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, an object of the present invention is to provide a white organic electroluminescent device that has excellent luminous efficiency and durability, and can suppress chromaticity change and angular dependency of chromaticity.

Means for solving the problems are as follows. That is,
<1> A white organic electroluminescent element having at least an intermediate layer between an anode and a cathode, and having a first unit having at least a first light emitting layer between the anode and the intermediate layer. And a second unit having at least a second light emitting layer between the intermediate layer and the cathode, wherein at least one of the first light emitting layer and the second light emitting layer is a single layer. A white organic electroluminescent element having a structure, wherein at least one of the first light-emitting layer and the second light-emitting layer includes at least a light-emitting material and an aggregate of the light-emitting material. is there.
<2> The white organic electroluminescent element according to <1>, wherein the total content of the light emitting material and the aggregate of the light emitting material in the light emitting layer containing the aggregate of the light emitting material is 30% by mass or more. It is.
<3> The white organic electroluminescent element according to any one of <1> to <2>, wherein the light emitting material is a platinum complex.
<4> The white organic electroluminescence device according to any one of <1> to <3>, wherein an emission peak wavelength of the luminescent material is 400 nm to 500 nm.
<5> The white organic electroluminescence device according to any one of <1> to <4>, wherein the aggregate has an emission peak wavelength of 500 nm to 700 nm.
<6> The white color according to any one of <1> to <5>, wherein the distance between the surface of the second light emitting layer on the cathode side and the surface of the cathode on the second light emitting layer side is 20 nm to 200 nm. It is an organic electroluminescent element.
<7> The white color according to any one of <1> to <6>, wherein the distance between the surface on the cathode side of the first light emitting layer and the surface on the second light emitting layer side of the cathode is 90 nm to 300 nm. It is an organic electroluminescent element.
<8> The white organic electroluminescent element according to any one of <1> to <7>, wherein the first light-emitting layer and the second light-emitting layer contain an aggregate of light-emitting materials.

  According to the present invention, the conventional problems can be solved, the object can be achieved, the light emission efficiency and the durability are excellent, and the chromaticity change and the angular dependency of the chromaticity are suppressed. It is possible to provide a white organic electroluminescent device that can be used.

FIG. 1 is a schematic view showing an example of the layer structure of the white organic electroluminescent element of the present invention.

(White organic electroluminescence device)
The white organic electroluminescent element of the present invention comprises an anode, a first unit, an intermediate layer, a second unit, and a cathode, and further comprises other layers as necessary. Do it.

<First unit, second unit>
The first unit includes a first light emitting layer, and further includes other organic layers as necessary.
The second unit includes a second light emitting layer, and further includes other organic layers as necessary.

<< first light-emitting layer, second light-emitting layer >>
As the first light emitting layer and the second light emitting layer, at least one of the first light emitting layer and the second light emitting layer contains the light emitting material, the aggregate, and the host material. It is preferable that the light emitting layer has a single layer structure in which one of the first light emitting layer and the second light emitting layer includes the light emitting material, the aggregate, and the host material. As long as the other light emitting layer can emit white light, any material may be used, and a single layer structure or a laminated structure may be used.

The first light-emitting layer and the second light-emitting layer may be configured, for example, such that the first light-emitting layer and the second light-emitting layer have a single layer structure, and the same light-emitting material and the light-emitting material are aggregated. The first light emitting layer has a single layer structure including a light emitting material and an aggregate of the light emitting material, and the second light emitting layer has a single layer structure, and the first light emitting layer has a single layer structure. A structure including a light emitting material different from the light emitting material contained in the layer and an aggregate of the light emitting material, the first light emitting layer has a single layer structure, and includes a light emitting material and an aggregate of the light emitting material, The second light emitting layer has a single layer or a stacked structure, and white light is obtained by mixing a plurality of light emitting materials. The first light emitting layer has a single layer or a stacked structure, and includes a plurality of light emitting materials. White light is obtained by mixing, and the second light emitting layer has a single layer structure, and includes a light emitting material and an aggregate of the light emitting material. Such as the formation and the like.
Among these, it is preferable that the first light-emitting layer and the second light-emitting layer have a single-layer structure and include the same light-emitting material and an aggregate of the light-emitting material in that chromaticity change can be suppressed.
In addition, since the effect of light interference becomes stronger near the cathode, it is preferable that the second light emitting layer near the cathode has a single layer structure and includes the same light emitting material and an aggregate of the light emitting material.

-Luminescent material and aggregate of the luminescent material-
Hereinafter, the first light-emitting layer and the second light-emitting layer (hereinafter, the first light-emitting layer and the second light-emitting layer are collectively referred to as “light-emitting layer”) will be described.
The aggregate means a state in which two luminescent materials (monomers) form an excited dimer (excimer). The light emitted from the aggregate exhibits broad light emission on a longer wavelength side than the light emitted from the light emitting material. The light emission of the aggregate can be discriminated by exciting a thin film in which a metal complex is dissolved in a solution at low and high concentrations or dispersed in a matrix with short wave light such as ultraviolet rays.

As a method for forming the aggregate, for example, when the host material and the light-emitting material are co-evaporated to form a light-emitting layer, the light-emitting material is deposited by doping 10% by mass or more of the light-emitting material. And a method of randomly generating aggregates in the light emitting layer by doping the light emitting material by 10 mass% or more with respect to the matrix by a method of randomly generating aggregates or a coating method. In addition, when the dope amount of the light emitting material is less than 10% by mass, the contact between the light emitting materials is reduced, and an aggregate may not be generated.
The dope amount of the light emitting material is preferably 10% by mass or more, and more preferably 30% by mass or more. By doping the light-emitting material with 30% by mass or more, the emission color can be more suitably brought close to white.

  The light-emitting layer contains a light-emitting material (monomer) and an aggregate of the light-emitting material so as to coexist so that light having an emission wavelength emitted from the light-emitting material and light having an emission wavelength emitted from the aggregate can be used. And produce white light.

As the light emitting material, the emission peak wavelength is preferably 400 nm to 500 nm, more preferably 420 nm to 490 nm, and particularly preferably 450 nm to 480 nm.
If the emission peak wavelength is less than 400 nm, it may be difficult to sufficiently emit blue or red light, and white may be difficult to obtain. If it exceeds 500 nm, blue may not be emitted and white may not be formed. . The emission peak wavelength can be measured by PL measurement (photoluminescence). In addition, when using the said luminescent material for said other light emitting layer, it is not limited to this.

The aggregate has an emission peak wavelength of preferably 500 nm to 700 nm, more preferably 520 nm to 650 nm, and particularly preferably 550 nm to 620 nm.
If the emission peak wavelength is less than 500 nm, the red light emission component may decrease and the white color temperature may increase, and if it exceeds 700 nm, the green light emission component decreases and the white color temperature decreases. There is. The emission peak wavelength can be measured by PL measurement (photoluminescence). In addition, when using the said aggregate for said other light emitting layer, it is not limited to this.

There is no restriction | limiting in particular as said luminescent material, According to the objective, it can select suitably, For example, the complex etc. which contain a transition metal atom and a lanthanoid atom are mentioned. These may be used alone or in combination of two or more.
Examples of the transition metal atom include ruthenium, rhodium, palladium, tungsten, rhenium, osmium, iridium, platinum, and the like. Among these, rhenium, iridium, and platinum are preferable, and platinum (platinum complex) is particularly preferable in that the luminous efficiency of the aggregate is high.

Examples of the lanthanoid atom include lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Among these, neodymium, europium, and gadolinium are particularly preferable.
Examples of the ligand of the complex include G.I. Wilkinson et al., Comprehensive Coordination Chemistry, Pergamon Press, 1987, H.C. Listed by Yersin, "Photochemistry and Photophysics of Coordination Compounds", published by Springer-Verlag, 1987, Akio Yamamoto, "Organic Metal Chemistry-Fundamentals and Applications-" It is done.
Examples of the ligand include a halogen ligand, an aromatic carbocyclic ligand, a nitrogen-containing heterocyclic ligand, a diketone ligand, a carboxylic acid ligand, an alcoholate ligand, and a carbon monoxide ligand. Examples thereof include ligands, isonitrile ligands, and cyano ligands. Among these, a nitrogen-containing heterocyclic ligand is particularly preferable.
As said halogen ligand, a chlorine ligand etc. are mentioned, for example.
Examples of the aromatic carbocyclic ligand include a cyclopentadienyl anion, a benzene anion, and a naphthyl anion.
Examples of the nitrogen-containing heterocyclic ligand include phenylpyridine, benzoquinoline, quinolinol, bipyridyl, phenanthroline, and the like.
Examples of the diketone ligand include acetylacetone.
Examples of the carboxylic acid ligand include an acetic acid ligand.
Examples of the alcoholate ligand include a phenolate 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, examples of the light emitting material include the following, but are not limited thereto.

The total content (concentration) of the light emitting material and the aggregate of the light emitting material is preferably 30% by mass or more, more preferably 35% by mass to 60% by mass, and more preferably 40% by mass in the mass of the light emitting layer. % To 50% by mass is particularly preferable.
When the total content is less than 30% by mass, the ratio of aggregates may be low and the white color temperature may be high. When the total content exceeds 60% by mass, non-luminescent components from the aggregates increase and the luminous efficiency is increased. May cause decline.

The content (concentration) of the light emitting material is preferably 15% by mass to 40% by mass, more preferably 18% by mass to 35% by mass, and more preferably 20% by mass to 30% by mass. Is particularly preferred.
When the content is less than 15% by mass, the aggregate ratio increases and the white color temperature may decrease. When the content exceeds 40% by mass, the aggregate ratio decreases and the white color temperature decreases. May be high. The content of the luminescent material can be calculated from the ratio of the peak specific to the non-aggregate and the peak specific to the aggregate in the Raman spectroscopy and the total content of the luminescent material.

The content (concentration) of the aggregate is preferably 15% by mass to 40% by mass, more preferably 18% by mass to 35% by mass, and more preferably 20% by mass to 30% by mass. Is particularly preferred.
When the content is less than 15% by mass, the ratio of aggregates may be low and the white color temperature may be high. When the content exceeds 40% by mass, the ratio of aggregates may be high and the white color temperature may be high. May decrease. The content of the aggregate can be calculated from the ratio of the peak specific to the non-aggregate and the peak specific to the aggregate in the Raman spectroscopy and the total content of the luminescent material.

-Host material-
There is no restriction | limiting in particular as said host material, According to the objective, it can select suitably, For example, an electron transport host material, a hole transport host material, etc. are mentioned.

--- Electron transport host material-
The electron affinity Ea of the electron transporting host material is preferably 2.5 eV to 3.5 eV, more preferably 2.6 eV to 3.2 eV, and particularly preferably 2.8 eV to 3.1 eV.
If the electron affinity is less than 2.5 eV, the durability may be inferior and drive stability may decrease, and if it exceeds 3.5 eV, the durability may decrease.

The ionization potential Ip of the electron transporting host material is preferably 5.7 eV to 7.5 eV, more preferably 5.8 eV to 7.0 eV, and particularly preferably 5.9 eV to 6.5 eV.
If the ionization potential is less than 5.7 eV, the durability may be inferior and drive stability may be reduced. If it exceeds 7.5 eV, the drive voltage may be increased.

The electron transporting host material is not particularly limited and may be appropriately selected depending on the intended purpose. For example, pyridine, pyrimidine, triazine, imidazole, pyrazole, triazole, oxazole, oxadiazole, fluorenone, anthraquinodi Examples include methane, anthrone, diphenylquinone, thiopyran dioxide, carbodiimide, fluorenylidenemethane, distyrylpyrazine, fluorine-substituted aromatic compounds, azole derivatives, azine derivatives, metal complexes, and the like.
Examples of the heterocyclic tetracarboxylic acid anhydride include naphthalene perylene.
Examples of the metal complex include phthalocyanine, 8-quinolinol derivative metal complexes, metal phthalocyanine, benzoxazole, and metal complexes having benzothiazole as a ligand.
Examples of the azole derivatives include benzimidazole derivatives and imidazopyridine derivatives.
Examples of the azine derivative include a pyridine derivative, a pyrimidine derivative, and a triazine derivative.
Among these, metal complexes, azole derivatives, and azine derivatives are preferable, and metal complex compounds are more preferable from the viewpoint of durability.

  The metal complex compound is preferably a metal complex having a ligand having at least one nitrogen atom, oxygen atom or sulfur atom coordinated to the metal.

  There is no restriction | limiting in particular as a metal ion contained in the said metal complex, According to the objective, it can select suitably, For example, beryllium ion, magnesium ion, aluminum ion, gallium ion, zinc ion, indium ion, tin ion , Platinum ions, palladium ions and the like. Among these, beryllium ion, aluminum ion, gallium ion, zinc ion, platinum ion and palladium ion are preferable, and aluminum ion, zinc ion and palladium ion are more preferable.

  Examples of the ligand contained in the metal complex include “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.

Examples of the ligand include azine ligand, hydroxyphenylazole ligand, alkoxy ligand, aryloxy ligand, heteroaryloxy ligand, alkylthio ligand, arylthio ligand, heteroary Examples include a ruthio ligand, a siloxy ligand, an aromatic hydrocarbon anion ligand, an aromatic heterocyclic anion ligand, and an indolenine anion ligand.
Examples of the azine ligand include a pyridine ligand, a bipyridyl ligand, and a terpyridine ligand.
Examples of the hydroxyphenylazole ligand include a hydroxyphenylbenzimidazole ligand, a hydroxyphenylbenzoxazole ligand, a hydroxyphenylimidazole ligand, and a hydroxyphenylimidazopyridine ligand.
As said alkoxy ligand, C1-C30 is preferable, C1-C20 is more preferable, C1-C10 is especially preferable, for example, methoxy, ethoxy, butoxy, 2-ethylhexyloxy etc. are mentioned. .
As said aryloxy ligand, C6-C30 is preferable, C6-C20 is more preferable, C6-C12 is especially preferable, For example, phenyloxy, 1-naphthyloxy, 2-naphthyloxy, Examples include 2,4,6-trimethylphenyloxy and 4-biphenyloxy.
As said heteroaryloxy ligand, C1-C30 is preferable, C1-C20 is more preferable, C1-C12 is especially preferable, For example, pyridyloxy, pyrazyloxy, pyrimidyloxy, quinolyloxy, etc. are mentioned. .
As said alkylthio ligand, C1-C30 is preferable, C1-C20 is more preferable, C1-C12 is especially preferable, For example, methylthio, ethylthio, etc. are mentioned.
As said arylthio ligand, C6-C30 is preferable, C6-C20 is more preferable, C6-C12 is especially preferable, For example, phenylthio etc. are mentioned.
As said heteroarylthio ligand, C1-C30 is preferable, C1-C20 is more preferable, C1-C12 is especially preferable, for example, pyridylthio, 2-benzimidazolylthio, 2- Examples include benzoxazolylthio and 2-benzthiazolylthio.
As said siloxy ligand, C1-C30 is preferable, C3-C25 is more preferable, C6-C20 is especially preferable, for example, a triphenylsiloxy group, a triethoxysiloxy group, a triisopropyl, for example Examples include a siloxy group.
As said aromatic hydrocarbon anion ligand, C6-C30 is preferable, for example, C6-C25 is more preferable, C6-C20 is especially preferable, For example, a phenyl anion, a naphthyl anion, an anthranyl anion Etc.
As said aromatic heterocyclic anion ligand, C1-C30 is preferable, C2-C25 is more preferable, C2-C20 is especially preferable, For example, a pyrrole anion, a pyrazole anion, a triazole anion, oxazole Anion, benzoxazole anion, thiazole anion, benzothiazole anion, thiophene anion, benzothiophene anion and the like can be mentioned.
Among these, azine ligand, hydroxyphenylazole ligand, aryloxy ligand, heteroaryloxy group, siloxy ligand, aromatic hydrocarbon anion ligand, aromatic heterocyclic anion ligand An azine ligand, a hydroxyphenylazole ligand, an aryloxy ligand, a siloxy ligand, an aromatic hydrocarbon anion ligand, and an aromatic heterocyclic anion ligand are more preferable.

  Examples of the electron transporting host material include various publications such as Japanese Patent Application Laid-Open Nos. 2002-235076, 2004-214179, 2004-221106, 2004-222165, 2004-221068, and 2004-327313. And an electron-transporting host material of the metal complex described in 1).

  Specific examples of such an electron transporting host material include, but are not limited to, the following, for example.

The content (concentration) of the electron transporting host material is preferably 40% by mass to 70% by mass, more preferably 45% by mass to 65% by mass, and more preferably 50% by mass to 60% by mass in the light emitting layer. Is particularly preferred.
When the content is less than 40% by mass, the driving voltage is increased and the light emission efficiency may be decreased. When the content is more than 70% by mass, the white color temperature may be increased.

--Hole-transporting host material--
The electron affinity Ea of the hole transporting host material is preferably 1.8 eV to 2.8 eV, more preferably 1.9 eV to 2.5 eV, and particularly preferably 2.0 eV to 2.4 eV.
When the electron affinity is less than 1.8 eV, the durability is inferior and the driving stability may be lowered, and when it exceeds 2.8 eV, the light emission efficiency may be lowered.

The ionization potential Ip of the hole transporting host material is preferably 5.0 eV to 6.0 eV, more preferably 5.2 eV to 5.8 eV, and particularly preferably 5.4 eV to 5.6 eV.
If the ionization potential is less than 5.0 eV, the durability may be inferior and drive stability may be reduced. If the ionization potential exceeds 6.0 eV, the drive voltage may be increased.

The hole transporting host material is not particularly limited and may be appropriately selected depending on the intended purpose. For example, anthracene, triphenylene, pyrrole, indole, carbazole, azaindole, azacarbazole, pyrazole, imidazole, polyaryl Alkane, pyrazoline, pyrazolone, phenylenediamine, arylamine, amino-substituted chalcone, styrylanthracene, fluorenone, hydrazone, stilbene, silazane, aromatic tertiary amine compound, styrylamine compound, aromatic dimethylidin compound, porphyrin compound, polysilane Compounds, poly (N-vinylcarbazole), aniline copolymers, thiophene oligomers, conductive polymer oligomers such as polythiophene, organic silanes, carbon films, and derivatives thereof Etc., and the like.
Among these, indole derivatives, carbazole derivatives, azaindole derivatives, azacarbazole derivatives, aromatic tertiary amine compounds, and thiophene derivatives are preferable, and indole skeleton, carbazole skeleton, azaindole skeleton, azacarbazole skeleton, or aromatic in the molecule Those having an aromatic group tertiary amine skeleton are more preferred, and compounds having a carbazole skeleton are particularly preferred.
In addition, as the hole transporting host material, a material obtained by substituting part or all of hydrogen of the hole transporting host material with deuterium may be used.

Specific examples of such a hole transporting host material include, but are not limited to, the following compounds.

The content of the hole transporting host material is preferably 40% by mass to 70% by mass, more preferably 45% by mass to 65% by mass, and particularly preferably 50% by mass to 60% by mass in the light emitting layer. preferable.
When the content is less than 40% by mass, the driving voltage is increased and the light emission efficiency may be decreased. When the content is more than 70% by mass, the white color temperature may be increased.

The thickness of the first light emitting layer is preferably 5 nm to 100 nm, more preferably 10 nm to 80 nm, and particularly preferably 20 nm to 60 nm.
If the thickness is less than 5 nm, the light emission efficiency may be reduced, and if it exceeds 100 nm, the drive voltage may be increased. The thickness can be measured with a stylus type surface shape measuring instrument (for example, Dektak 6M manufactured by ULVAC).

The thickness of the second light emitting layer is preferably 5 nm to 100 nm, more preferably 10 nm to 80 nm, and particularly preferably 20 nm to 60 nm.
If the thickness is less than 5 nm, the light emission efficiency may be reduced, and if it exceeds 100 nm, the drive voltage may be increased. The thickness can be measured with a stylus type surface shape measuring instrument (for example, Dektak 6M manufactured by ULVAC).

  There is no restriction | limiting in particular as a formation method of the said light emitting layer, According to the objective, it can select suitably, For example, resistance heating vapor deposition, vacuum evaporation, an electron beam, sputtering, a molecular lamination method, a coating method (spin coat method, cast) Method, dip coating method, etc.).

<< Other organic layers >>
Examples of the other organic layers include a hole transport layer, a hole injection layer, an electron transport layer, and an electron injection layer.
The other organic layers in the first unit and the second unit may be made of the same material or different materials.

-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. The hole injection layer and the hole transport layer may have a single layer structure or a multilayer structure composed of a plurality of layers having the same composition or different compositions.
The hole injecting material or hole transporting material used for these layers may be a low molecular compound, a high molecular compound, or an inorganic compound.
The hole injection material and the hole transport material are not particularly limited and may be appropriately selected depending on the purpose. For example, 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, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styryl Examples include amine compounds, aromatic dimethylidin compounds, phthalocyanine compounds, porphyrin compounds, thiophene derivatives, organosilane derivatives, carbon, molybdenum trioxide, and the like. These may be used individually by 1 type and may use 2 or more types together.

The hole injection layer and the hole transport layer may contain an electron accepting dopant.
The electron-accepting dopant may be an inorganic compound or an organic compound as long as it is electron-accepting and has the property of oxidizing an organic compound.
There is no restriction | limiting in particular as said inorganic compound, According to the objective, it can select suitably, For example, a metal halide, a metal oxide, etc. are mentioned.
Examples of the metal halide include ferric chloride, aluminum chloride, gallium chloride, indium chloride, and antimony pentachloride.
Examples of the metal oxide include vanadium pentoxide and molybdenum trioxide.
The organic compound is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a compound having a nitro group, a halogen, a cyano group, a trifluoromethyl group or the like as a substituent, a quinone compound, an acid anhydride Compounds, fullerenes and the like.
These electron-accepting dopants may be used alone or in combination of two or more.

  The amount of the electron-accepting dopant used varies depending on the type of material, but is preferably 0.01% by mass to 50% by mass with respect to the hole transport material or the hole injection material, and 0.05% by mass to 50% by mass. % Is more preferable, and 0.1% by mass to 30% by mass is particularly preferable.

  The thickness of the hole injection layer and the hole transport layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and particularly preferably 10 nm to 100 nm.

-Electron transport layer, electron injection layer-
The electron transport layer and the electron injection layer are layers having a function of receiving electrons from the cathode or the cathode side and transporting them to the anode side, and as described above, the triplet energy of the electron transport layer is the same as that of the cathode side adjacent layer. It is preferably larger than the triplet energy.

  The electron transport layer may have a single layer structure made of one or more materials, or may have a laminated structure. The electron injection layer may have a single layer structure made of one or more materials, or may have a multilayer structure made of a plurality of layers having the same composition or different compositions.

The materials for the electron transport layer and the electron injection layer are not particularly limited and may be appropriately selected depending on the intended purpose. For example, quinoline derivatives, oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, perylene derivatives, pyridine derivatives , Pyrimidine derivatives, quinoxaline derivatives, diphenylquinone derivatives, nitro-substituted fluorene derivatives, and the like.
Examples of the quinoline derivative include 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (basocuproin; BCP), BCP doped with Li, tris (8-quinolinolato) aluminum (Alq), and the like. Organic metal complexes having 8-quinolinol or a derivative thereof as a ligand, BAlq (bis- (2-methyl-8-quinolinolato) -4- (phenyl-phenolato) -aluminum (III)) and the like. Among these, BCP doped with Li and BAlq are particularly preferable.

  Examples of the method for forming the electron transport layer and the electron injection layer include vapor deposition, wet film formation, electron beam, sputtering, reactive sputtering, MBE (molecular beam epitaxy), cluster ion beam, ion It can be suitably formed by the above-described methods such as a plating method, a plasma polymerization method (high frequency excitation ion plating method), a molecular lamination method, an LB method, a printing method, and a transfer method.

  There is no restriction | limiting in particular as thickness of the said electron carrying layer, According to the objective, it can select suitably, For example, 1 nm-500 nm are preferable, and 10 nm-50 nm are more preferable. The thickness can be measured with a stylus type surface shape measuring instrument (for example, Dektak 6M manufactured by ULVAC).

  There is no restriction | limiting in particular as thickness of the said electron injection layer, According to the objective, it can select suitably, 0.1 nm-200 nm are preferable, 0.2 nm-100 nm are more preferable, 0.5 nm-50 nm are especially preferable . The thickness can be measured with a stylus type surface shape measuring instrument (for example, Dektak 6M manufactured by ULVAC).

The thickness of the electron transport layer and the electron injection layer is such that the distance between the surface of the second light emitting layer on the cathode side and the surface of the cathode on the second light emitting layer side is 20 nm to 200 nm. It is preferable to prepare such that 30 nm to 100 nm is more preferable, and 40 nm to 80 nm is particularly preferable.
If the distance is less than 20 nm, the light emission efficiency may be reduced, and if it exceeds 200 nm, the drive voltage may be increased.

The thickness of the first unit is preferably 30 nm to 300 nm, more preferably 50 nm to 200 nm, and particularly preferably 80 nm to 150 nm.
If the thickness is less than 30 nm, the light emission efficiency may decrease, and if it exceeds 300 nm, the drive voltage may increase. The thickness can be measured with a stylus type surface shape measuring instrument (for example, Dektak 6M manufactured by ULVAC).

The thickness of the second unit is preferably 30 nm to 300 nm, more preferably 50 nm to 200 nm, and particularly preferably 80 nm to 150 nm.
If the thickness is less than 30 nm, the light emission efficiency may decrease, and if it exceeds 300 nm, the drive voltage may increase. The thickness can be measured with a stylus type surface shape measuring instrument (for example, Dektak 6M manufactured by ULVAC).

<Intermediate layer>
The intermediate layer is provided between the anode and the cathode, and is provided between the first unit and the second unit.
The intermediate layer injects electrons into the first unit and injects holes into the second unit. That is, it functions as an electron injection layer for the first unit and as a hole injection layer for the second unit.

The intermediate layer may be formed by laminating the electron injection layer and the hole injection layer, and may be multi-layered as necessary.
As the intermediate layer, it is preferable to use the material used in the electron injection layer described above on the first unit side, and it is preferable to use the material of the hole injection layer described above on the second unit side.

The thickness of the intermediate layer on the first unit side is preferably 0.1 nm to 100 nm, more preferably 1 nm to 50 nm, and particularly preferably 5 nm to 20 nm.
If the thickness is less than 0.1 nm, electron injection into the first unit may be insufficient, and if it exceeds 100 nm, the drive voltage may increase. The thickness can be measured with a stylus type surface shape measuring instrument (for example, Dektak 6M manufactured by ULVAC).

The thickness of the intermediate layer on the second unit side is preferably 0.1 nm to 100 nm, more preferably 1 nm to 50 nm, and particularly preferably 5 nm to 20 nm.
When the thickness is less than 0.1 nm, hole injection into the second unit may be insufficient, and when it exceeds 100 nm, the drive voltage may increase. The thickness can be measured with a stylus type surface shape measuring instrument (for example, Dektak 6M manufactured by ULVAC).

The total thickness when there are a plurality of layers constituting the intermediate layer is preferably 1 nm to 100 nm, more preferably 5 nm to 50 nm, and particularly preferably 10 nm to 30 nm.
When the thickness is less than 1 nm, carrier injection into each unit may be insufficient, and when it exceeds 100 nm, the drive voltage may increase. The thickness can be measured with a stylus type surface shape measuring instrument (for example, Dektak 6M manufactured by ULVAC).

<Anode>
The anode is not particularly limited as long as it has a function as an electrode for supplying holes to the light emitting layer. In view of the properties of the white organic electroluminescent device of the present invention, at least one of the anode and the cathode is preferably transparent.
There is no restriction | limiting in particular about the shape, structure, size, etc. as said anode, According to the use and objective of a white organic electroluminescent element, it can select suitably from well-known electrode materials.
Examples of the material constituting the anode include conductive metal oxides, metals, mixtures or laminates of these metals and conductive metal oxides, inorganic conductive substances, organic conductive materials, and these and ITO. Examples include laminates.
Examples of the conductive metal oxide include tin oxide doped with antimony and fluorine (ATO, FTO), tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO). Can be mentioned.
Examples of the metal include gold, silver, chromium, and nickel.
Examples of the inorganic conductive substance include copper iodide and copper sulfide.
Examples of the organic conductive material include polyaniline, polythiophene, and polypyrrole.

There is no restriction | limiting in particular as a formation method of the said anode, According to a well-known method, it can carry out, for example, a wet system, a chemical system, a physical system, etc. are mentioned.
Examples of the wet method include a printing method and a coating method.
Examples of the chemical method include CVD and plasma CVD.
Examples of the physical method include a vacuum deposition method, a sputtering method, and an ion plating method.

  In addition, when patterning is performed when forming the anode, it may be performed by chemical etching such as photolithography, or may be performed by physical etching using a laser or the like. It may be performed by sputtering or the like, or may be performed by a lift-off method or a printing method.

  There is no restriction | limiting in particular as thickness of the said anode, Although it can select suitably by material, 10 nm-5 micrometers are preferable and 50 nm-10 micrometers are more preferable. The thickness can be measured with a stylus type surface shape measuring instrument (for example, Dektak 6M manufactured by ULVAC).

The resistance value of the anode is preferably 10 ³ Ω / □ or less, and more preferably 10 ² Ω / □ or less in order to reliably supply holes to the light emitting layer or the like.

<Cathode>
The cathode is not particularly limited as long as it has a function as an electrode for injecting electrons into the light emitting layer.
There is no restriction | limiting in particular about the shape, structure, size, etc. as said cathode, According to the use and objective of an organic electroluminescent element, it can select suitably from well-known electrode materials.
Examples of the material constituting the cathode include alkali metals, alkaline earth metals, rare earth metals, other metals, and alloys of these metals. These may be used alone, but from the viewpoint of achieving both stability and electron injection properties, it is preferable to use two or more in combination.
Examples of the alkali metal include lithium and sodium.
Examples of the alkaline earth metal include magnesium and calcium.
Examples of the other materials include gold, silver, lead, and aluminum.
Examples of the rare earth metal include indium and ytterbium.
Examples of the alloy include a sodium-potassium alloy, a lithium-aluminum alloy, and a magnesium-silver alloy.
Among these, an alkali metal and an alkaline earth metal are preferable from the viewpoint of electron injecting property, and a material containing aluminum is particularly preferable from the viewpoint of excellent storage stability. The material containing 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.)

There is no restriction | limiting in particular as a formation method of the said cathode, According to a well-known method, it can carry out, for example, a wet system, a chemical system, a physical system, etc. are mentioned.
Examples of the wet method include a printing method and a coating method.
Examples of the chemical method include CVD and plasma CVD.
Examples of the physical method include a vacuum deposition method, a sputtering method, and an ion plating method.

  In addition, when patterning is performed when forming the cathode, it may be performed by chemical etching such as photolithography, or may be performed by physical etching using a laser or the like. It may be performed by sputtering, or may be performed by a lift-off method or a printing method.

The thickness of the cathode is preferably 5 nm to 500 nm, more preferably 10 nm to 300 nm, and particularly preferably 30 nm to 150 nm.
When the thickness is less than 5 nm, the luminance at the central portion of the light emitting site may be reduced. The thickness can be measured with a stylus type surface shape measuring instrument (for example, Dektak 6M manufactured by ULVAC).

<Other layers>
Examples of the other layers include a substrate, an electronic block layer, and a protective layer.

-Board-
The white organic electroluminescent device of the present invention is preferably provided on the substrate, and may be provided in such a manner that the anode and the substrate are in direct contact with each other or an intermediate layer interposed. May be.
There is no restriction | limiting in particular as a material of the said board | substrate, According to the objective, it can select suitably, For example, an inorganic material, an organic material, etc. are mentioned.
Examples of the inorganic material include yttria stabilized zirconia (YSZ), alkali-free glass, soda lime glass, and the like.
Examples of the organic material include polyethylene terephthalate, polybutylene phthalate, polyethylene naphthalate, polystyrene, polycarbonate, polyethersulfone, polyarylate, polyimide, polycycloolefin, norbornene resin, and polychlorotrifluoroethylene.

There is no restriction | limiting in particular about the shape of the said 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 transparent or opaque, and if transparent, it may be colorless and transparent or colored and transparent.

The substrate may be provided with a moisture permeation preventing layer (gas barrier layer) on the front surface or the back surface.
Examples of the material of the moisture permeation preventing layer (gas barrier layer) include inorganic substances such as silicon nitride and silicon oxide.
The moisture permeation preventing layer (gas barrier layer) can be formed by, for example, a high frequency sputtering method.

-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, and is usually provided as an organic compound layer adjacent to the light emitting layer on the anode side.
As the compound constituting the electron blocking layer, for example, those mentioned as the hole transporting host material can be used. In addition, the electron blocking layer may have a single layer structure made of one or more of the materials described above, or may have a multilayer structure made of a plurality of layers having the same composition or different compositions.
The method for forming the electron blocking layer is not particularly limited and can be formed according to a known method. For example, a vapor deposition method, a dry film forming method such as a sputtering method, a wet coating method, a transfer method, a printing method, It can be suitably formed by an inkjet method or the like.
The thickness of the electron blocking layer is preferably 1 nm to 200 nm, more preferably 1 nm to 50 nm, and particularly preferably 3 nm to 10 nm.

-Protective layer-
The white organic electroluminescent element of the present invention may be entirely protected by a protective layer.
The material contained in the protective layer is not particularly limited as long as it has a function of suppressing the entry of elements that promote element deterioration such as moisture and oxygen into the element. For example, In, Sn, Pb, Au, Cu, Ag, Al, Ti, Ni, MgO, SiO, SiO ₂ , Al ₂ O ₃ , GeO, NiO, CaO, BaO, Fe ₂ O ₃ , Y ₂ O ₃ , TiO ₂ , SiNx, SiNxOy, MgF ₂ , LiF, AlF ₃ , CaF ₂ , polyethylene, polypropylene, polymethyl methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoro Copolymer of ethylene, chlorotrifluoroethylene and dichlorodifluoroethylene, A copolymer obtained by copolymerizing a monomer mixture containing fluoroethylene and at least one comonomer; a fluorinated copolymer having a cyclic structure in the copolymer main chain; a water-absorbing substance having a water absorption of 1% or more; Examples include a moisture-proof substance of 0.1% or less.

  There is no restriction | limiting in particular as a formation method of the said protective layer, According to the objective, it can select suitably, For example, a vacuum evaporation method, sputtering method, reactive sputtering method, MBE (molecular beam epitaxy) method, cluster ion beam Examples thereof include an ion plating method, a plasma polymerization method (high frequency excitation ion plating method), a plasma CVD method, a laser CVD method, a thermal CVD method, a gas source CVD method, a coating method, a printing method, and a transfer method.

-Sealing container-
As a white organic electroluminescent element of this invention, the whole may be sealed using the sealing container. Furthermore, a water absorbent or an inert liquid may be sealed in the space between the sealing container and the white organic electroluminescent element.
The moisture absorbent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, barium oxide, sodium oxide, potassium oxide, calcium oxide, sodium sulfate, calcium sulfate, magnesium sulfate, phosphorus pentoxide, chloride Examples thereof include calcium, magnesium chloride, copper chloride, cesium fluoride, niobium fluoride, calcium bromide, vanadium bromide, molecular sieve, zeolite, and magnesium oxide.
There is no restriction | limiting in particular as said inert liquid, According to the objective, it can select suitably, For example, paraffins, liquid paraffins, a fluorine-type solvent, a chlorine-type solvent, silicone oil etc. are mentioned.

-Resin sealing layer-
As the white organic electroluminescent device of the present invention, device performance deterioration due to oxygen or moisture from the atmosphere may be suppressed by sealing with a resin sealing layer.
The resin material for the resin sealing layer is not particularly limited and may be appropriately selected depending on the purpose. For example, acrylic resin, epoxy resin, fluorine resin, silicone resin, rubber resin, ester resin, etc. Is mentioned. Among these, an epoxy resin is particularly preferable from the viewpoint of moisture prevention function. Among the epoxy resins, a thermosetting epoxy resin or a photocurable epoxy resin is preferable.

  There is no restriction | limiting in particular as a formation method of the said resin sealing layer, According to the objective, it can select suitably, For example, the method of apply | coating a resin solution, the method of crimping | bonding or thermocompressing a resin sheet, vapor deposition, sputtering, etc. And a dry polymerization method.

(Layer structure of white organic electroluminescence device)
FIG. 1 is a schematic view showing an example of the layer structure of the white organic electroluminescent element of the present invention. As the white organic electroluminescent element 10, an anode 2 formed on a substrate 1, a first unit 3, an intermediate layer 4, a second unit 5, and a cathode 6 are laminated in this order. The anode 2 and the cathode 8 are connected to each other via a power source.
The first unit 3 is formed by laminating a hole injection layer 31, a hole transport layer 32, a first light emitting layer 33, and an electron transport layer 34 in this order from the anode 2 side.
The second unit 5 is formed by laminating a hole transport layer 51, a second light emitting layer 52, an electron transport layer 53, and an electron injection layer 54 in this order from the anode 2 side.

The electron transport layer 53 and the electron injection layer so that the distance d1 between the surface of the second light emitting layer 52 on the cathode 6 side and the surface of the cathode 6 on the second light emitting layer 52 side is 20 nm to 200 nm. It is preferable to adjust the thickness of 54, more preferably 30 nm to 100 nm, and particularly preferably 40 nm to 80 nm.
If the distance is less than 20 nm, the light emission efficiency may be reduced, and if it exceeds 200 nm, the drive voltage may be increased. The distance d1 can be measured by, for example, a stylus type surface shape measuring instrument (for example, Dektak 6M manufactured by ULVAC).

Further, the electron transport layer 34 and the intermediate layer are set so that the distance d2 between the surface of the first light emitting layer 33 on the cathode 6 side and the surface of the cathode 6 on the second light emitting layer 52 side is 90 nm to 300 nm. 4 and the thickness of the second unit 5 are preferably adjusted, more preferably 120 nm to 280 nm, and particularly preferably 140 nm to 250 nm.
If the distance is less than 90 nm, the light emission efficiency may decrease, and if it exceeds 300 nm, the drive voltage may increase. The distance d2 can be measured by, for example, a stylus type surface shape measuring instrument (for example, Dektak 6M manufactured by ULVAC).

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
<Preparation of white organic electroluminescent element>
A glass substrate having a thickness of 0.5 mm and a square of 2.5 cm was placed in a cleaning container, subjected to ultrasonic cleaning in 2-propanol, and then subjected to UV-ozone treatment for 30 minutes. The following layers were deposited on this glass substrate by a vacuum deposition method using a vacuum deposition apparatus (Small-ELVESS, manufactured by Tokki Co., Ltd.). In addition, all the vacuum evaporation methods in a following example and a comparative example are performed on the same conditions, and a vapor deposition rate is 0.2 nm / sec unless there is particular notice. The deposition rate was measured using a quartz resonator. Moreover, a pressure is 1 * 10 <^-4> Pa or less. The thickness of each layer below was measured using a quartz resonator.

-Fabrication of anode-
First, ITO (Indium Tin Oxide) was sputtered as a positive electrode on a glass substrate to a thickness of 70 nm.
On the anode (ITO), F4-TCNQ represented by the following structural formula was added to N, N′-di (4- (N, N′-diphenylamino) phenyl-N, N′-diphenylbenzidine (DNTPD). A hole injection layer doped with 1% by mass was formed by vacuum deposition so that the thickness was 40 nm.

-Production of first unit-
Next, N, N′-dinaphthyl-N, N′-diphenyl- [1,1′-biphenyl] -4,4′- represented by the following structural formula as a hole transport layer is formed on the hole injection layer. A diamine (NPD) was formed by vacuum deposition so as to have a thickness of 7 nm (referred to as a first hole transport layer).
Furthermore, HTL1 represented by the following structural formula was formed on the NPD by vacuum deposition so as to have a thickness of 3 nm (referred to as a second hole transport layer).
70 wt% of compound A represented by the following structural formula, which is a host material, and 30 wt% of light emitting material A represented by the following structural formula with respect to compound A, the thickness of the light emitting layer is 30 nm. A first light emitting layer was formed by vacuum evaporation. In addition, when the light emitting layer was vacuum-deposited, the aggregate A of the light emitting material A was formed in the light emitting layer. When the emission peak wavelength of the luminescent material A and the aggregate A was measured with an emission spectrum measurement system (manufactured by Shimadzu Corporation, ELS 1500), the emission peak wavelength of the luminescent material A was 470 nm, and the emission peak wavelength of the aggregate A was 626 nm. When the contents of the luminescent material A and the aggregate A were measured by Raman spectroscopy, the luminescent material A was 18% by mass and the aggregate A was 12% by mass.
Next, BAlq (bis- (2-methyl-8-quinolinolato) -4- (phenyl-phenolato) -aluminum (III)) represented by the following structural formula as an electron transport layer is formed on the first light-emitting layer. The film was formed by vacuum deposition so that the thickness was 10 nm.

-Production of intermediate layer-
On the electron transport layer, 2,9-dimethyl-4,7-diphenyl-phenanthroline (BCP) represented by the following structural formula and a layer doped with 1% by mass of lithium with respect to the BCP have a thickness of 15 nm. A first intermediate layer was formed by vacuum evaporation.
On the first intermediate layer, N, N′-di (4- (N, N′-diphenylamino) phenyl-N, N′-diphenylbenzidine (DNTPD) and 30 mass of MoO ₃ with respect to the DNTPD A second intermediate layer was formed by forming a% -doped layer by vacuum deposition so that the thickness was 15 nm.

-Production of second unit-
On the intermediate layer (layer containing DNTPD), N, N′-dinaphthyl-N, N′-diphenyl- [1,1′-biphenyl] -4, represented by the above structural formula as the first hole transport layer, 4′-diamine (NPD) was formed by vacuum deposition so as to have a thickness of 7 nm.
Further, HTL1 represented by the above structural formula was formed on the NPD as a second hole transport layer by vacuum deposition so as to have a thickness of 3 nm.
70 wt% of the compound A represented by the above structural formula as the host material and 30 wt% of the light emitting material A represented by the above structural formula with respect to the compound A so that the thickness is 30 nm. A second light emitting layer was formed by vacuum evaporation. In addition, when the light emitting layer was vacuum-deposited, the aggregate A of the light emitting material A was formed in the light emitting layer. When the contents of the luminescent material A and the aggregate A were measured by Raman spectroscopy, the luminescent material A was 17% by mass and the aggregate A was 13% by mass.
Next, BAlq (bis- (2-methyl-8-quinolinolato) -4- (phenyl-phenolato) -aluminum (III)) represented by the following structural formula as an electron transport layer is formed on the second light-emitting layer. The film was formed by vacuum deposition so as to have a thickness of 10 nm.
On the electron transport layer, a 2,9-dimethyl-4,7-diphenyl-phenanthroline (BCP) as an electron injection layer and a BCP layer doped with 1% by mass of lithium with respect to the BCP are vacuumed to a thickness of 20 nm. It was formed by vapor deposition.

-Production of cathode-
On the electron injection layer, a patterned mask (a mask having a light emitting area of 2 mm × 2 mm) was placed as a cathode, and metal aluminum was vacuum deposited so as to have a thickness of 100 nm.

  The laminate produced as described above 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 Nagase Ciba Co., Ltd.). The white organic electroluminescent element of Example 1 was produced as described above.

(Evaluation)
The white organic electroluminescence device produced in Example 1 was evaluated for the light emission efficiency, luminance half time, chromaticity, chromaticity change after half luminance, and chromaticity change from 60 ° oblique as follows.

<Measurement of luminous efficiency>
The light emission luminance of the white organic electroluminescence device driven at a constant current density (10 mA / cm ² ) is measured with a spectral radiance meter (SR-3, manufactured by Topcon), and the current light emission efficiency (cd / m ² ) is obtained. It was.

<Luminance half time>
The white organic electroluminescent device of Example 1 was driven at a constant current until the luminance was reduced by half at an initial luminance of 5,000 cd / m ² , and the luminance half-life (t ₅₀₀₀ ) was measured. From the luminance half-life of 5,000 cd / m ^2, a power law of 1.5 was assumed, and the luminance half-life of 1,000 cd / m ² was calculated from the following formula.
t ₁₀₀₀ = t ₅₀₀₀ × ( _5,000 cd / 1,000 cd) ^1.5

<Chromaticity>
A DC constant voltage was applied to the white organic electroluminescence device of Example 1 to emit light using a source measure unit 2400 type manufactured by Toyo Technica. The obtained emission spectrum was measured with an emission spectrum measurement system (ELS 1500) manufactured by Shimadzu Corporation, and the x value and the y value were calculated from the obtained spectrum using a CIE color system. The x value and the y value are values at a current density of 11.6 mA / cm ² .

<Chromaticity change after half brightness>
A white organic electroluminescence device having a luminance reduced by half was emitted by applying a direct current constant voltage to the white organic electroluminescence device of Example 1 using a source measure unit type 2400 manufactured by Toyo Technica. The obtained emission spectrum was measured with an emission spectrum measurement system (ELS 1500) manufactured by Shimadzu Corporation, and the x value and the y value were calculated from the obtained spectrum using a CIE color system.
The difference between the x value calculated by the evaluation of the chromaticity and the x value after the luminance was reduced by half, the y value calculated by the evaluation of the chromaticity and the y value after the luminance was reduced by half was calculated.

<Chromaticity change from 60 degrees diagonally>
The produced white organic electroluminescent element of Example 1 was placed upright, and a vertical angle of 60 degrees (drawing a perpendicular line from the substrate to the light emitting layer, viewing angle from this direction was 0 °, and the vertical line as a reference, The x value of the CIE color system obtained from the emission spectrum at 60 ° in the horizontal direction was obtained. The difference between this x value and the x value of the emission spectrum obtained at a viewing angle of 0 ° was calculated.

(Example 2)
<Preparation of white organic electroluminescent element>
In Example 1, the white organic electroluminescent element of Example 2 was produced in the same manner as Example 1 except that the first light emitting layer and the second light emitting layer were produced as follows.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.
-Production of first light emitting layer and second light emitting layer-
The thickness of the light-emitting layer doped with 60% by mass of the compound A represented by the above structural formula as the host material and 40% by mass of the light emitting material A represented by the above structural formula with respect to the compound A is 30 nm. Formed by vacuum evaporation. In addition, when the light emitting layer was vacuum-deposited, the aggregate A of the light emitting material A was formed in the light emitting layer. When the contents of the luminescent material A and the aggregate A were measured by Raman spectroscopy, the luminescent material A was 22% by mass and the aggregate A was 18% by mass.

(Example 3)
<Preparation of white organic electroluminescent element>
In Example 1, the white organic electroluminescent element of Example 3 was produced in the same manner as Example 1 except that the first light emitting layer and the second light emitting layer were produced as follows.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.
-Production of first light emitting layer and second light emitting layer-
The thickness of the light-emitting layer doped with 80% by mass of the compound A represented by the above structural formula as the host material and 20% by mass of the light emitting material A represented by the above structural formula with respect to the compound A is 30 nm. Formed by vacuum evaporation. In addition, when the light emitting layer was vacuum-deposited, the aggregate A of the light emitting material A was formed in the light emitting layer. When the contents of the luminescent material A and the aggregate A were measured by Raman spectroscopy, the luminescent material A was 13% by mass and the aggregate A was 7% by mass.

(Example 4)
<Preparation of white organic electroluminescent element>
In Example 1, the white organic electroluminescent element of Example 4 was produced in the same manner as Example 1 except that the first light emitting layer was produced as follows.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.
-Production of first light emitting layer-
On the hole transport layer, 85% by mass of the compound A represented by the above structural formula as a host material, 14% by mass of the light emitting material B represented by the following structural formula with respect to the compound A, and the following structure A layer doped with 1% by mass of the light-emitting material C represented by the formula was formed by vacuum vapor deposition so that the thickness was 10 nm. When the emission peak wavelengths of the luminescent material B and the luminescent material C were measured with an emission spectrum measuring system (manufactured by Shimadzu Corporation, ELS 1500), the luminescent material B had an emission peak wavelength of 530 nm, and the luminescent material C had an emission peak wavelength of 627 nm.
Further, on this layer, a layer in which 85% by mass of the compound A represented by the above structural formula as a host material and 15% by mass of the light emitting material A represented by the above structural formula with respect to the compound A is doped. A first light-emitting layer having a two-layer structure was formed by vacuum deposition so that the thickness was 30 nm.

(Example 5)
<Preparation of white organic electroluminescent element>
In Example 1, the white organic electroluminescent element of Example 5 was produced in the same manner as Example 1 except that the second light emitting layer was produced as follows.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.
-Production of second light emitting layer-
On the hole transport layer, 85% by mass of the compound A represented by the structural formula as a host material, 14% by mass of the light-emitting material B represented by the structural formula with respect to the compound A, and the structure A layer doped with 1% by mass of the light-emitting material C represented by the formula was formed by vacuum vapor deposition so that the thickness was 10 nm.
Further, on this layer, a layer in which 85% by mass of the compound A represented by the above structural formula as a host material and 15% by mass of the light emitting material A represented by the above structural formula with respect to the compound A is doped. A second light-emitting layer having a two-layer structure was formed by vacuum deposition so as to have a thickness of 30 nm.

(Example 6)
<Preparation of white organic electroluminescent element>
In Example 1, the compound A represented by the above structural formula as a host material in the first light emitting layer and the second light emitting layer is replaced by the compound B represented by the following structural formula, and represented by the above structural formula. A white organic electroluminescent element of Example 6 was produced in the same manner as in Example 1 except that the luminescent material A was replaced with the luminescent material D represented by the following structural formula. In addition, when the light emitting layer was vacuum-deposited, the aggregate D of the light emitting material D was formed in the light emitting layer. When the contents of the luminescent material D and the aggregate D were measured by Raman spectroscopy, the luminescent material D was 17% by mass and the aggregate D was 13% by mass.
When the emission peak wavelengths of the luminescent material D and the aggregate D were measured with an emission spectrum measurement system (manufactured by Shimadzu Corporation, ELS1500), the emission peak wavelength of the luminescent material D was 469 nm, and the emission peak wavelength of the aggregate D was It was 626 nm.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 7)
<Preparation of white organic electroluminescent element>
In Example 1, the compound A represented by the above structural formula as a host material in the first light emitting layer and the second light emitting layer is replaced by the compound C represented by the following structural formula, and represented by the above structural formula. A white organic electroluminescent element of Example 7 was produced in the same manner as in Example 1 except that the luminescent material A was replaced with the luminescent material E represented by the following structural formula. In addition, when the light emitting layer was vacuum-deposited, the aggregate E of the light emitting material E was formed in the light emitting layer. When the contents of the luminescent material E and the aggregate E were measured by Raman spectroscopy, the luminescent material E was 17% by mass and the aggregate E was 13% by mass. When the emission peak wavelength of the luminescent material E and the aggregate E was measured by an emission spectrum measurement system (manufactured by Shimadzu Corporation, ELS 1500), the emission peak wavelength of the luminescent material E was 468 nm, It was 618 nm.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 8)
<Preparation of white organic electroluminescent element>
In Example 1, the compound A represented by the above structural formula is replaced with the compound D represented by the following structural formula as a host material in the second light emitting layer, and the light emitting material A represented by the above structural formula is represented by the following structure. A white organic electroluminescent element of Example 8 was produced in the same manner as Example 1 except that the light emitting material F represented by the formula was used. In addition, when the light emitting layer was vacuum-deposited, the aggregate F of the light emitting material F was formed in the light emitting layer. When the contents of the luminescent material F and the aggregate F were measured by Raman spectroscopy, the luminescent material F was 17% by mass and the aggregate F was 13% by mass. When the emission peak wavelengths of the luminescent material F and the aggregate F were measured with an emission spectrum measurement system (manufactured by Shimadzu Corporation, ELS1500), the emission peak wavelength of the luminescent material F was 464 nm, and the emission peak wavelength of the aggregate F was It was 614 nm.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

Example 9
<Preparation of white organic electroluminescent element>
In Example 1, except that the light emitting material A represented by the above structural formula in the first light emitting layer was replaced with the light emitting material G represented by the following structural formula, Example 1 A white organic electroluminescent device was produced. In addition, when the light emitting layer was vacuum-deposited, the aggregate G of the light emitting material G was formed in the light emitting layer. When the contents of the luminescent material G and the aggregate G were measured by Raman spectroscopy, the luminescent material G was 17% by mass and the aggregate G was 13% by mass. When the emission peak wavelengths of the luminescent material G and the aggregate G were measured with an emission spectrum measurement system (manufactured by Shimadzu Corporation, ELS 1500), the luminescent material G had an emission peak wavelength of 478 nm, and the aggregate G had an emission peak wavelength of As in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after half luminance, and chromaticity change from 60 ° oblique were evaluated in the same manner as in Example 1.

(Example 10)
<Preparation of white organic electroluminescent element>
In Example 1, the same as Example 1 except that the light emitting material A represented by the above structural formula in the first light emitting layer and the second light emitting layer was replaced with the light emitting material H represented by the following structural formula. Thus, a white organic electroluminescent element of Example 10 was produced. In addition, when the light emitting layer was vacuum-deposited, the aggregate H of the light emitting material H was formed in the light emitting layer. When the contents of the luminescent material H and the aggregate H were measured by Raman spectroscopy, the luminescent material H was 18% by mass and the aggregate H was 12% by mass. When the emission peak wavelengths of the luminescent material H and the aggregate H were measured with an emission spectrum measurement system (ELS 1500, manufactured by Shimadzu Corporation), the luminescence peak wavelength of the luminescent material H was 508 nm, and the emission peak wavelength of the aggregate H was It was 655 nm.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 11)
<Preparation of white organic electroluminescent element>
In Example 1, the same as Example 1 except that the light emitting material A represented by the above structural formula in the first light emitting layer and the second light emitting layer was replaced with the light emitting material I represented by the following structural formula. Thus, a white organic electroluminescent element of Example 11 was produced. In addition, when the light emitting layer was vacuum-deposited, the aggregate I of the light emitting material I was formed in the light emitting layer. When the contents of the luminescent material I and the aggregate I were measured by Raman spectroscopy, the luminescent material I was 17% by mass and the aggregate I was 13% by mass. When the emission peak wavelength of the luminescent material I and the aggregate I was measured by an emission spectrum measurement system (manufactured by Shimadzu Corporation, ELS 1500), the emission peak wavelength of the luminescent material I was 505 nm, and the emission peak wavelength of the aggregate I was It was 651 nm.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 12)
<Preparation of white organic electroluminescent element>
In Example 1, the same as Example 1 except that the light emitting material A represented by the above structural formula in the first light emitting layer and the second light emitting layer was replaced with the light emitting material J represented by the following structural formula. Thus, a white organic electroluminescent element of Example 12 was produced. In addition, when the light emitting layer was vacuum-deposited, the aggregate J of the light emitting material J was formed in the light emitting layer. When the contents of the luminescent material J and the aggregate J were measured by Raman spectroscopy, the luminescent material J was 17% by mass and the aggregate J was 13% by mass. When the emission peak wavelengths of the luminescent material J and the aggregate J were measured with an emission spectrum measurement system (manufactured by Shimadzu Corporation, ELS 1500), the luminescence peak wavelength of the luminescent material J was 493 nm, and the emission peak wavelength of the aggregate J was It was 587 nm.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 13)
<Preparation of white organic electroluminescent element>
In Example 1, the same as Example 1 except that the light emitting material A represented by the above structural formula in the first light emitting layer and the second light emitting layer was replaced with the light emitting material K represented by the following structural formula. Thus, a white organic electroluminescent element of Example 13 was produced. In addition, when the light emitting layer was vacuum-deposited, the aggregate K of the light emitting material K was formed in the light emitting layer. When the contents of the luminescent material K and the aggregate K were measured by Raman spectroscopy, the luminescent material K was 17% by mass and the aggregate K was 13% by mass. When the emission peak wavelength of the luminescent material K and the aggregate K was measured with an emission spectrum measurement system (manufactured by Shimadzu Corporation, ELS 1500), the luminescence peak wavelength of the luminescent material K was 511 nm, and the emission peak wavelength of the aggregate K was It was 655 nm.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 14)
<Preparation of white organic electroluminescent element>
In Example 1, the thickness of the electron transport layer of the first unit was changed from 10 nm to 5 nm, and the thickness of the first hole transport layer of the second unit was changed from 7 nm to 2 nm. A white organic electroluminescent element of Example 14 was produced in the same manner as in Example 1 except that the thickness of each of the two intermediate layers was changed to 5 nm.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 15)
<Preparation of white organic electroluminescent element>
A white organic electroluminescent element of Example 15 was produced in the same manner as in Example 1 except that the thickness of the first hole transport layer of the second unit was changed from 7 nm to 227 nm in Example 1.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 16)
<Preparation of white organic electroluminescent element>
A white organic electroluminescent element of Example 16 was produced in the same manner as in Example 1 except that the thickness of the electron injection layer of the second unit was changed from 20 nm to 2 nm in Example 1.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 17)
<Preparation of white organic electroluminescent element>
In Example 1, the white organic electroluminescent element of Example 17 was produced in the same manner as in Example 1 except that the thickness of the electron injection layer of the second unit was changed from 20 nm to 10 nm.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 18)
<Preparation of white organic electroluminescent element>
In Example 1, the white organic electroluminescent element of Example 18 was produced in the same manner as Example 1 except that the thickness of the first light emitting layer was changed from 30 nm to 3 nm.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 19)
<Preparation of white organic electroluminescent element>
In Example 1, the white organic electroluminescent element of Example 19 was produced in the same manner as Example 1 except that the thickness of the first light emitting layer was changed from 30 nm to 110 nm.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 20)
<Preparation of white organic electroluminescent element>
A white organic electroluminescent device of Example 20 was produced in the same manner as in Example 1 except that the thickness of the second light emitting layer was changed from 30 nm to 3 nm in Example 1.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 21)
<Preparation of white organic electroluminescent element>
A white organic electroluminescent element of Example 21 was produced in the same manner as in Example 1 except that the thickness of the second light emitting layer was changed from 30 nm to 110 nm in Example 1.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 22)
<Preparation of white organic electroluminescent element>
In Example 1, the same procedure as in Example 1 was performed except that the light emitting material A represented by the above structural formula in the first light emitting layer and the second light emitting layer was replaced with the light emitting material L represented by the following structural formula. Thus, a white organic electroluminescent device of Example 22 was produced. In addition, when the light emitting layer was vacuum-deposited, the aggregate L of the light emitting material L was formed in the light emitting layer. When the contents of the luminescent material L and the aggregate L were measured by Raman spectroscopy, the luminescent material L was 18% by mass and the aggregate L was 12% by mass. When the emission peak wavelengths of the luminescent material L and the aggregate L were measured with an emission spectrum measurement system (manufactured by Shimadzu Corporation, ELS 1500), the emission peak wavelength of the luminescent material L was 392 nm, and the emission peak wavelength of the aggregate L was It was 496 nm.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 23)
<Preparation of white organic electroluminescent element>
In Example 1, the same procedure as in Example 1 was performed except that the light emitting material A represented by the above structural formula in the first light emitting layer and the second light emitting layer was replaced with the light emitting material M represented by the following structural formula. Thus, a white organic electroluminescent element of Example 23 was produced. In addition, when the light emitting layer was vacuum-deposited, the aggregate M of the light emitting material M was formed in the light emitting layer. When the contents of the luminescent material M and the aggregate M were measured by Raman spectroscopy, the luminescent material M was 16% by mass and the aggregate M was 14% by mass. When the emission peak wavelengths of the luminescent material M and the aggregate M were measured with an emission spectrum measurement system (manufactured by Shimadzu Corporation, ELS 1500), the luminescence peak wavelength of the luminescent material M was 492 nm, and the emission peak wavelength of the aggregate M was It was 703 nm.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 24)
<Preparation of white organic electroluminescent element>
In Example 1, Example 24 was performed in the same manner as in Example 1 except that the concentration of the light emitting material A represented by the above structural formula in the first light emitting layer and the second light emitting layer was changed to 50% by mass. A white organic electroluminescent element was prepared. In addition, when the light emitting layer was vacuum-deposited, the aggregate A of the light emitting material A was formed in the light emitting layer. When the contents of the luminescent material A and the aggregate A were measured by Raman spectroscopy, the luminescent material A was 27% by mass and the aggregate A was 23% by mass.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 25)
<Preparation of white organic electroluminescent element>
In Example 1, Example 25 was performed in the same manner as Example 1 except that the concentration of the light emitting material A represented by the above structural formula in the first light emitting layer and the second light emitting layer was changed to 60% by mass. A white organic electroluminescent element was prepared. In addition, when the light emitting layer was vacuum-deposited, the aggregate A of the light emitting material A was formed in the light emitting layer. When the contents of the luminescent material A and the aggregate A were measured by Raman spectroscopy, the luminescent material A was 30% by mass and the aggregate A was 30% by mass.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 26)
<Preparation of white organic electroluminescent element>
In Example 1, the same as Example 1 except that the light emitting material A represented by the above structural formula in the first light emitting layer and the second light emitting layer was replaced with the light emitting material N represented by the following structural formula. Thus, a white organic electroluminescent element of Example 26 was produced. In addition, when the light emitting layer was vacuum-deposited, the aggregate N of the light emitting material N was formed in the light emitting layer. When the contents of the luminescent material N and the aggregate N were measured by Raman spectroscopy, the luminescent material N was 17% by mass and the aggregate N was 13% by mass. When the emission peak wavelengths of the luminescent material N and the aggregate N were measured with an emission spectrum measurement system (manufactured by Shimadzu Corporation, ELS 1500), the luminescent material N had an emission peak wavelength of 458 nm, and the aggregate N had an emission peak wavelength of It was 622 nm.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 27)
<Preparation of white organic electroluminescent element>
In Example 1, the same as Example 1 except that the light emitting material A represented by the above structural formula in the first light emitting layer and the second light emitting layer was replaced with the light emitting material P represented by the following structural formula. Thus, a white organic electroluminescent element of Example 27 was produced. In addition, when the light emitting layer was vacuum-deposited, the aggregate P of the light emitting material P was formed in the light emitting layer. When the contents of the luminescent material P and the aggregate P were measured by Raman spectroscopy, the luminescent material P was 17% by mass and the aggregate P was 13% by mass. When the emission peak wavelength of the luminescent material P and the aggregate P was measured with an emission spectrum measurement system (ELS 1500, manufactured by Shimadzu Corporation), the emission peak wavelength of the luminescent material P was 465 nm, and the emission peak wavelength of the aggregate P was It was 639 nm.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 28)
<Preparation of white organic electroluminescent element>
In Example 1, the same as Example 1 except that the light emitting material A represented by the above structural formula in the first light emitting layer and the second light emitting layer was replaced with the light emitting material Q represented by the following structural formula. Thus, a white organic electroluminescent element of Example 28 was produced. In addition, when the light emitting layer was vacuum-deposited, the aggregate Q of the light emitting material Q was formed in the light emitting layer. When the contents of the luminescent material Q and the aggregate Q were measured by Raman spectroscopy, the luminescent material Q was 17% by mass and the aggregate Q was 13% by mass. When the emission peak wavelengths of the luminescent material Q and the aggregate Q were measured with an emission spectrum measurement system (manufactured by Shimadzu Corporation, ELS 1500), the emission peak wavelength of the luminescent material Q was 466 nm, and the emission peak wavelength of the aggregate Q was It was 633 nm.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 29)
<Preparation of white organic electroluminescent element>
In Example 1, Example 29 was performed in the same manner as in Example 1 except that the concentration of the luminescent material A represented by the structural formula in the first luminescent layer and the second luminescent layer was changed to 95% by mass. A white organic electroluminescent element was prepared. In addition, when the light emitting layer was vacuum-deposited, the aggregate A of the light emitting material A was formed in the light emitting layer. When the contents of the luminescent material A and the aggregate A were measured by Raman spectroscopy, the luminescent material A was 41% by mass and the aggregate A was 54% by mass.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 30)
<Preparation of white organic electroluminescent element>
In Example 1, Example 30 was performed in the same manner as in Example 1 except that the concentration of the luminescent material A represented by the structural formula in the first luminescent layer and the second luminescent layer was changed to 72% by mass. A white organic electroluminescent element was prepared. In addition, when the light emitting layer was vacuum-deposited, the aggregate A of the light emitting material A was formed in the light emitting layer. When the contents of the luminescent material A and the aggregate A were measured by Raman spectroscopy, the luminescent material A was 32% by mass and the aggregate A was 40% by mass.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 31)
<Preparation of white organic electroluminescent element>
In Example 2, the same procedure as in Example 1 except that the light emitting material A represented by the above structural formula in the first light emitting layer and the second light emitting layer was replaced with the light emitting material R represented by the following structural formula. Thus, a white organic electroluminescent element of Example 31 was produced. In addition, when the light emitting layer was vacuum-deposited, the aggregate R of the light emitting material R was formed in the light emitting layer. When the contents of the luminescent material R and the aggregate R were measured by Raman spectroscopy, the luminescent material R was 22% by mass and the aggregate R was 18% by mass. When the emission peak wavelength of the luminescent material R and the aggregate R was measured by an emission spectrum measurement system (manufactured by Shimadzu Corporation, ELS 1500), the emission peak wavelength of the luminescent material R was 478 nm, and the emission peak wavelength of the aggregate R was It was 619 nm.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 32)
<Preparation of white organic electroluminescent element>
In Example 2, the same as Example 1 except that the light emitting material A represented by the above structural formula in the first light emitting layer and the second light emitting layer was replaced with the light emitting material S represented by the following structural formula. Thus, a white organic electroluminescent element of Example 32 was produced. In addition, when the light emitting layer was vacuum-deposited, the aggregate S of the light emitting material S was formed in the light emitting layer. When the contents of the luminescent material S and the aggregate S were measured by Raman spectroscopy, the luminescent material S was 23% by mass and the aggregate S was 17% by mass. When the emission peak wavelength of the luminescent material S and the aggregate S was measured with an emission spectrum measurement system (ELS 1500, manufactured by Shimadzu Corporation), the emission peak wavelength of the luminescent material S was 462 nm, and the emission peak wavelength of the aggregate S was It was 620 nm.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Example 33)
<Preparation of white organic electroluminescent element>
In Example 2, the same procedure as in Example 1 except that the light emitting material A represented by the above structural formula in the first light emitting layer and the second light emitting layer was replaced with the light emitting material T represented by the following structural formula. Thus, a white organic electroluminescent element of Example 33 was produced. In addition, when the light emitting layer was vacuum-deposited, the aggregate T of the light emitting material T was formed in the light emitting layer. When the contents of the luminescent material T and the aggregate T were measured by Raman spectroscopy, the luminescent material T was 22% by mass and the aggregate T was 18% by mass. The emission peak wavelength of the luminescent material T and the aggregate T was measured with an emission spectrum measurement system (manufactured by Shimadzu Corporation, ELS1500). The emission peak wavelength of the luminescent material T was 460 nm, and It was 618 nm.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Comparative Example 1)
<Preparation of white organic electroluminescent element>
In Example 1, Comparative Example 1 was performed in the same manner as in Example 1 except that the second unit was not stacked and the electron injection layer and the cathode were formed on the electron transport layer of the first unit as follows. A white organic electroluminescent element was prepared.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.
-Preparation of electron injection layer and cathode-
On the electron transport layer, a 2,9-dimethyl-4,7-diphenyl-phenanthroline (BCP) as an electron injection layer and a BCP layer doped with 1% by mass of lithium with respect to the BCP are vacuumed to a thickness of 20 nm. It was formed by vapor deposition.
On the electron injection layer, a patterned mask (a mask having a light emitting area of 2 mm × 2 mm) was placed as a cathode, and metal aluminum was vacuum deposited so as to have a thickness of 100 nm.

(Comparative Example 2)
<Preparation of white organic electroluminescent element>
In Example 4, a white organic electroluminescent element of Comparative Example 2 was produced in the same manner as in Example 4 except that the second light emitting layer had the same laminated structure as the first light emitting layer.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Comparative Example 3)
<Preparation of white organic electroluminescent element>
In Example 1, the white color of Comparative Example 3 was the same as Example 1 except that the first light emitting layer and the second light emitting layer were doped with the light emitting material A represented by the above structural formula at a concentration of 9% by mass. An organic electroluminescent element was produced. In addition, when the light emitting layer was vacuum-deposited, the aggregate A of the light emitting material A was not formed in the light emitting layer.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Comparative Example 4)
<Preparation of white organic electroluminescent element>
In Example 1, the white organic material of Comparative Example 4 was prepared in the same manner as in Example 1 except that the concentration of the light emitting material A represented by the above structural formula was 100% by mass in the first light emitting layer and the second light emitting layer. An electroluminescent element was produced.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

(Comparative Example 5)
<Preparation of white organic electroluminescent element>
In Example 1, the light emitting material A represented by the above structural formula in the first light emitting layer has a concentration of 100% by mass, and the light emitting material A represented by the above structural formula in the second light emitting layer is doped by 10% by mass. A white organic electroluminescent element of Comparative Example 5 was produced in the same manner as Example 1 except that.
In the same manner as in Example 1, the luminous efficiency, luminance half time, chromaticity, chromaticity change after halving the luminance, and chromaticity change from 60 degrees oblique were evaluated.

  About white organic electroluminescent element produced in Examples 1-33 and Comparative Examples 1-5, luminous efficiency, luminance half time, chromaticity, chromaticity change after half luminance, chromaticity change from oblique 60 degrees, and element The configuration is shown in Tables 1 to 9.

(In the table, “wt%” represents mass%. CIE chromaticity (x, y) is a value at a current density of 11.6 mA / cm ^2. )
(In the table, “wt%” represents mass%. CIE chromaticity (x, y) is a value at a current density of 11.6 mA / cm ^2. )
(In the table, “wt%” represents mass%. CIE chromaticity (x, y) is a value at a current density of 11.6 mA / cm ^2. )
(In the table, “wt%” represents mass%. CIE chromaticity (x, y) is a value at a current density of 11.6 mA / cm ^2. The thickness of the electron transport layer of the first unit. In Example 14, the thickness is 5 nm, and Examples 15 to 17 are 10 nm The thickness of the electron injection layer of the second unit is 20 nm in Examples 14 and 15, and 2 nm in Example 16. (17 is 10 nm. Regarding the thickness of the first hole transport layer of the second unit, Example 15 is 227 nm, and Examples 14, 16, and 17 are 7 nm.)
(In the table, “wt%” represents mass%. CIE chromaticity (x, y) is a value at a current density of 11.6 mA / cm ^2. )
(In the table, “wt%” represents mass%. CIE chromaticity (x, y) is a value at a current density of 11.6 mA / cm ^2. )
(In the table, “wt%” represents mass%. CIE chromaticity (x, y) is a value at a current density of 11.6 mA / cm ^2. )
(In the table, “wt%” represents mass%. CIE chromaticity (x, y) is a value at a current density of 11.6 mA / cm ^2. )
(In the table, “wt%” represents mass%. CIE chromaticity (x value, y value) is a value at a current density of 11.6 mA / cm ^2. )

  From Tables 1 to 9, it can be seen that Examples 1 to 33 have improved luminous efficiency and luminance half-life (durability) compared to Comparative Examples 1 to 5. Moreover, it turns out that Examples 1-33 are suppressing the chromaticity change and the angle dependence of chromaticity compared with Comparative Examples 1-5.

  The white organic electroluminescent device of the present invention has excellent luminous efficiency and durability, and can suppress chromaticity change and angular dependency of chromaticity. For example, a display device, a display, and a backlight It is suitably used for electrophotography, illumination light source, recording light source, exposure light source, reading light source, sign, signboard, interior, optical communication and the like.

DESCRIPTION OF SYMBOLS 10 White organic electroluminescent element 1 Board | substrate 2 Anode 3 1st unit 31 Hole injection layer 32 Hole transport layer 33 1st light emitting layer 34 Electron transport layer 4 Intermediate | middle layer 5 2nd unit 51 Hole transport layer 52 1st 2 light emitting layers 53 electron transport layer 54 electron injection layer 6 cathode

Claims (8)

A white organic electroluminescent device having at least an intermediate layer between an anode and a cathode,
A first unit having at least a first light emitting layer between the anode and the intermediate layer;
A second unit having at least a second light emitting layer , an electron transport layer, and an electron injection layer between the intermediate layer and the cathode;
The electron transport layer is between the second light emitting layer and the electron injection layer, the electron injection layer is between the electron transport layer and the cathode;
At least one of the first light emitting layer and the second light emitting layer has a single layer structure,
At least one of the first light-emitting layer and the second light-emitting layer, at least seen containing a light emitting material, and aggregates of light emitting material, a
The white organic electroluminescent element, wherein at least one of the first light emitting layer and the second light emitting layer contains either a platinum complex or an iridium complex .   The white organic electroluminescent device according to claim 1, wherein the total content of the light emitting material and the aggregate of the light emitting material in the light emitting layer containing the aggregate of the light emitting material is 30% by mass or more.   The white organic electroluminescent element according to claim 1, wherein the light emitting material is a platinum complex.   The white organic electroluminescent element according to any one of claims 1 to 3, wherein an emission peak wavelength of the light emitting material is 400 nm to 500 nm.   The white organic electroluminescence device according to any one of claims 1 to 4, wherein the aggregate has an emission peak wavelength of 500 nm to 700 nm.   The white organic electroluminescent element according to any one of claims 1 to 5, wherein a distance between a surface of the second light emitting layer on the cathode side and a surface of the cathode on the second light emitting layer side is 20 nm to 200 nm.   The white organic electroluminescent element according to any one of claims 1 to 6, wherein a distance between a surface of the first light emitting layer on the cathode side and a surface of the cathode on the second light emitting layer side is 90 nm to 300 nm. The white organic electroluminescent element according to any one of claims 1 to 7, wherein the first light emitting layer and the second light emitting layer contain an aggregate of a light emitting material.