JP5912224B2 - 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, an iridium complex that emits light from green to red in a light emitting layer, There has been proposed a white organic electroluminescent element that realizes high luminous efficiency at a low voltage by containing a doping material composed of a platinum complex or the like (Patent Document 1).

  However, this proposal can reduce the voltage by increasing the concentration of the doped material. However, if the concentration of the doped material is increased, green to red light is emitted more strongly. There was a problem that it was difficult to make adjustments.

  Accordingly, there is a strong demand for prompt development of a white organic electroluminescent device capable of achieving both low voltage, high luminous efficiency, and color balance adjustment.

JP 2001-319780 A

  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 capable of adjusting a low voltage, high luminous efficiency, and color balance.

Means for solving the problems are as follows. That is,
<1> A white organic electroluminescent device having at least a light emitting layer between an anode and a cathode, wherein the light emitting layer contains an iridium complex compound represented by the following structural formula (1). A white organic electroluminescent device characterized by the following.
However, the in the structural formula (1), A is, -C _{(R 4)} - or -N-, B stands, -C _{(R 7)} - or -N- _represent, R 1 to R ₇ is , Each independently a hydrogen atom, a cyano group, a hydroxy group, a nitro group, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a carbon number 7-20 arylalkyl group, C2-C20 alkylalkoxy group, C7-C20 arylalkoxy group, C6-C20 arylamino group, C1-C20 alkylamino group, carbon number Represents a dialkylamino group having 1 to 20 carbon atoms, a heterocyclic group having 2 to 20 carbon atoms, and R ₄ and R ₅ , R ₄ and R ₆ are connected to each other to form a saturated or unsaturated carbocycle, saturated or unsaturated A heterocycle may be formed. X represents a monovalent anionic bidentate ligand, m represents 2 or 3, n represents 0 or 1, and the sum of m and n is 3.
The white organic electroluminescent element of the present invention has at least a light emitting layer between an anode and a cathode. The light emitting layer contains an iridium complex compound represented by the structural formula (1). The iridium complex compound represented by the structural formula (1) has high blue emission intensity in the vicinity of 420 nm to 450 nm. This reinforces the intensity of blue and facilitates color balance adjustment.
<2> The white organic electroluminescent element according to <1>, wherein the light emitting layer further contains a light emitting material capable of emitting light.
<3> The white organic electroluminescent element according to <2>, wherein the light emitting material is at least one selected from a platinum complex light emitting material and an iridium complex light emitting material.
<4> The white organic electroluminescent element according to any one of <2> to <3>, wherein the content of the light emitting material is 0.01% by mass to 60% by mass with respect to the light emitting layer.
<5> The white organic electroluminescence device according to any one of <2> to <4>, wherein an emission peak wavelength of the light emitting material is 400 nm to 800 nm.
<6> The white organic electroluminescent element according to any one of <1> to <5>, wherein the content of the iridium complex compound in the light emitting layer is 1% by mass to 50% by mass.
<7> The white organic electroluminescence device according to any one of <1> to <6>, wherein the iridium complex compound emits light at a blue emission peak wavelength of 400 nm to 450 nm.
<8> The white organic electroluminescent element according to any one of <1> to <7>, wherein the light emitting layer further contains a host material.

  ADVANTAGE OF THE INVENTION According to this invention, the said various problems in the past can be solved, the said objective can be achieved, and the white organic electroluminescent element which can adjust a low voltage, high luminous efficiency, and a color balance can be provided. .

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 cathode, and a light emitting layer, and further comprises other layers as necessary.

<Light emitting layer>
The light emitting layer contains at least the iridium complex compound represented by the structural formula (1), and further contains a light emitting material, a host material, and other components as necessary.

-Iridium complex compound-
As said iridium complex compound, it is a compound represented by following Structural formula (1), may be used individually by 1 type, and may use 2 or more types together.

A in the structural formula (1) represents —C (R ₄ ) — or —N—. Among these, -C (R ₄ )-is preferable in terms of ease of synthesis of the complex.

B in the structural formula (1) represents —C (R ₇ ) — or —N—. Among these, —C (R ₇ ) — is preferable in terms of ease of synthesis of the complex.

R _{1 to} R ₇ in the structural formula (1) are each independently a hydrogen atom, a cyano group, a hydroxy group, a nitro group, a halogen atom, an alkyl group having 1 to 20 carbon atoms, or 1 to 1 carbon atoms. 20 alkoxy groups, aryl groups having 6-20 carbon atoms, arylalkyl groups having 7-20 carbon atoms, alkylalkoxy groups having 2-20 carbon atoms, arylalkoxy groups having 7-20 carbon atoms, carbon numbers Represents an arylamino group having 6 to 20 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, a dialkylamino group having 1 to 20 carbon atoms, and a heterocyclic group having 2 to 20 carbon atoms. Among these, it is preferable to contain a halogen atom, particularly a fluorine atom, from the viewpoint of shortening the wavelength. R ₄ and R ₅ , R ₄ and R ₆ may be connected to each other to form a saturated or unsaturated carbocyclic ring or a saturated or unsaturated heterocyclic ring.

X in the structural formula (1) represents a monovalent anionic bidentate ligand.
Examples of the monovalent anionic bidentate ligand include, but are not limited to, the following monovalent anionic bidentate ligands.

  M in the structural formula (1) represents 2 or 3. Among these, 2 is preferable because 3 can take only one kind of complex and various complexes can be obtained.

N in the structural formula (1) represents 0 or 1. Among these, 1 is preferable in that various complexes can be obtained by one different ligand.
The sum of m and n is preferably 3. Iridium tends to be trivalent and the ligand is 3 and is chemically stable. Therefore, when the sum is less than 3 or more than 3, it may be chemically unstable.
Since the sum of m and n is preferably 3, the structural formula (1) can be represented by the following structural formula (2) and the following structural formula (3).

  Specific examples of the iridium complex compound include, but are not limited to, the following materials.

The content (concentration) of the iridium complex compound is preferably 1% by mass to 50% by mass, more preferably 2% by mass to 20% by mass, and particularly preferably 3% by mass to 10% by mass in the light emitting layer. preferable.
When the content is less than 1% by mass, sufficient blue light emission may not be emitted, and when the content exceeds 50% by mass, concentration quenching becomes remarkable and sufficient luminous efficiency may not be obtained.

The emission peak wavelength of the iridium complex compound is not particularly limited as long as it is shorter than the emission peak wavelength of the light emitting material described later, but is preferably 400 nm to 450 nm, more preferably 410 nm to 440 nm, and particularly preferably 420 nm to 430 nm. preferable.
If the emission peak wavelength is less than 400 nm, it may enter the ultraviolet region and become shorter than visible light. If it exceeds 450 nm, it may not be sufficiently blue than the emission peak wavelength of the light emitting material described later. The peak wavelength can be measured with a photoluminescence measuring device.

-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 transporting 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.
When the electron affinity is less than 2.5 eV, durability may be inferior and driving stability may be lowered, and when it exceeds 3.5 eV, electrons may not easily move to the light emitting material in the light emitting layer. is there.

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.
When the ionization potential is less than 5.7 eV, durability may be inferior and driving stability may be lowered. When the ionization potential exceeds 7.5 eV, holes may not easily move to the light emitting material in the light emitting layer. There is.

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 a 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.

--Hole-transporting host material--
The electron affinity Ea of the hole transporting host material is preferably 1.0 eV to 3.0 eV, more preferably 1.5 eV to 2.8 eV, and particularly preferably 2.0 eV to 2.5 eV.
When the electron affinity is less than 1.0 eV, durability may be inferior and driving stability may be lowered. When it exceeds 3.0 eV, electrons may not easily move to the light emitting material in the light emitting layer. is there.

The ionization potential Ip of the hole transporting host material is preferably 5.0 eV to 7.0 eV, more preferably 5.2 eV to 6.5 eV, and particularly preferably 5.5 eV to 6.0 eV.
When the ionization potential is less than 5.0 eV, durability may be inferior and driving stability may be lowered. When the ionization potential exceeds 7.0 eV, holes may not easily move to the light emitting material in the light emitting layer. There is.

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, aromatic in the molecule Those having a 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.

-Luminescent material-
The light emitting material means a light emitting material excluding the iridium complex compound represented by the structural formula (1).

The light emitting material has an emission peak wavelength of preferably 450 nm to 800 nm, more preferably 460 nm to 750 nm, and particularly preferably 470 nm to 700 nm.
When the emission peak wavelength is less than 450 nm, it may be shorter than the iridium complex compound represented by the structural formula (1), and when it exceeds 800 nm, it may deviate from the visible region. The emission peak wavelength can be measured with a photoluminescence measuring device. The emission peak wavelength may be an emission peak wavelength due to associative emission.

The light emitting material is not particularly limited as long as the emission peak wavelength is 450 nm to 800 nm, and can be appropriately selected according to the purpose. Examples thereof include a complex containing a transition metal atom and a lanthanoid atom. 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 iridium and platinum are particularly preferable.

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,” published by Soukabo, 1982, etc. 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 cyclopentadienyl anion, benzene anion, and 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.

There is no restriction | limiting in particular as a luminescent material which is the said complex containing iridium, Although it can select suitably according to the objective, It represents with either of following General formula (1), (2) and (3) A compound is preferred.
However, in said general formula (1), (2) and (3), n represents the integer of 1-3. XY represents a bidentate ligand. Ring A represents a ring structure that may contain any of a nitrogen atom, a sulfur atom, and an oxygen atom. R ¹¹ represents a substituent, and m1 represents an integer of 0 to 6. When m1 is 2 or more, adjacent R ¹¹ may be bonded to form a ring which may contain any of a nitrogen atom, a sulfur atom and an oxygen atom, and the ring is further substituted with a substituent. May be. R ¹² represents a substituent, and m2 represents an integer of 0 to 4. When m2 is 2 or more, adjacent R ¹² may be bonded to form a ring which may contain any of a nitrogen atom, a sulfur atom and an oxygen atom, and the ring is further substituted with a substituent. May be. R ¹¹ and R ¹² may combine to form a ring that may contain any of a nitrogen atom, a sulfur atom, and an oxygen atom, and the ring may be further substituted with a substituent. .

  The ring A represents a ring structure that may contain any of a nitrogen atom, a sulfur atom, and an oxygen atom, and examples thereof include a 5-membered ring and a 6-membered ring. The ring may be substituted with a substituent.

XY represents a bidentate ligand, and a bidentate monoanionic ligand is preferably exemplified.
Examples of the bidentate monoanionic ligand include picolinate (pic), acetylacetonate (acac), dipivaloylmethanate (t-butyl acac), and the like.
Examples of ligands other than the above include the ligands described in pages 89 to 91 of Lamansky et al., International Publication No. 2002/15645 pamphlet.

The substituent in R ¹¹ and R ¹² is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a halogen atom, an alkoxy group, an amino group, an alkyl group, a cycloalkyl group, a nitrogen atom, and sulfur. The aryloxy group which may contain an atom, the nitrogen atom, and the aryloxy group which may contain a sulfur atom are represented, and these may be further substituted.
R ¹¹ and R ¹² may be bonded to each other adjacent to each other to form a ring that may contain a nitrogen atom, a sulfur atom, or an oxygen atom, and a 5-membered ring, a 6-membered ring, etc. are preferable. It is mentioned in. The ring may be further substituted with a substituent.

Specific examples of the compound represented by any one of the general formulas (1), (2), and (3) include, but are not limited to, the following compounds.

Other examples of the light emitting material include the following compounds.

The content (concentration) of the light emitting material is preferably 0.01% by mass to 60% by mass, more preferably 0.05% by mass to 50% by mass, and more preferably 0.1% by mass. Mass% to 40 mass% is particularly preferable.
If the content is less than 0.01% by mass, it may not be white because light is not sufficiently emitted. If it exceeds 60% by mass, concentration quenching may occur.

The thickness of the light emitting layer is preferably 1 nm to 100 nm, more preferably 3 nm to 50 nm, and particularly preferably 10 nm to 30 nm.
If the thickness is less than 1 nm, the light emitting layer may not be formed and the deterioration may be significant. If the thickness exceeds 100 nm, the voltage may increase extremely. The thickness can be measured with a spectrophotometer.

  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.).

<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 profilometer.

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 an 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 10 nm to 1,000 nm, more preferably 20 nm to 500 nm, and particularly preferably 50 nm to 100 nm.
If the thickness is less than 10 nm, it may be oxidized and deteriorated, and if it exceeds 1,000 nm, it may be deteriorated by obtaining radiant heat during film formation. The thickness can be measured with a stylus profilometer.

<Other layers>
As a white organic electroluminescent element of this invention, a hole transport layer, a hole injection layer, an electron transport layer, an electron injection layer, a board | substrate etc. are mentioned as said other layer.

-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-
The electron transport layer is a layer having a function of receiving electrons from the cathode or the cathode side and transporting the electrons to the anode side, and as described above, the triplet energy of the electron transport layer is more than the triplet energy of the adjacent layer on the cathode side. Is also preferably large.

The material for the electron transport layer is not particularly limited and may be appropriately selected depending on the purpose. For example, quinoline derivatives, oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, perylene derivatives, pyridine derivatives, pyrimidine derivatives, Examples include 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 include a vapor deposition method, a wet film formation method, an electron beam method, a sputtering method, a reactive sputtering method, an MBE (molecular beam epitaxy) method, a cluster ion beam method, an ion plating method, It can be suitably formed by the above-described methods such as 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 electron transport layer may have a single layer structure or a laminated structure.

-Electron injection layer-
The electron injection layer is a layer having a function of receiving electrons from the cathode or the cathode side and transporting them to the anode side.
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.
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 .

-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 the substrate 1, a hole injection layer 3, a hole transport layer 4, a light emitting layer 5, an electron transport layer 6, an electron injection layer 7, The cathode 8 is laminated in this order. The anode 2 and the cathode 8 are connected to each other via a power source.

Examples of the present invention will be described below, but the present invention is not limited to these examples. However, Examples 2 and 7 are read as reference 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 (E-200 manufactured by ALS). 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. The deposition temperature is 20 ° C. and the pressure is 1 × 10 ⁻⁴ Pa. The thickness of each layer below was measured using a quartz resonator.

First, ITO (Indium Tin Oxide) was sputtered to a thickness of 100 nm on a glass substrate as an anode.
On the anode (ITO), 4,4 ′, 4 ″ -tris (N, N- (2-naphthyl) -phenylamino) triphenylamine (2-TNATA) represented by the following structural formula, A hole injection layer doped with 0.3% by mass of F4-TCNQ represented by is formed by vacuum deposition so as to have a thickness of 120 nm.
Next, an NPD (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. '-Diamine) was formed by vacuum deposition so as to have a thickness of 7 nm.
On the positive hole transport layer, it formed by vacuum-depositing the compound A represented by the following structural formula as an electron block layer so that thickness might be set to 3 nm.
94.8% by mass of the compound B represented by the following structural formula as the host material, 5% by mass of the iridium complex compound A represented by the following structural formula with respect to the compound B, and represented by the following structural formula A light emitting layer doped with 0.1% by mass of the light emitting material A that emits green light and 0.1% by weight of the light emitting material B that emits red light represented by the following structural formula is vacuum-deposited so that the thickness is 30 nm. Was formed. When the emission peak wavelengths of the iridium complex compound A, the light emitting material A, and the light emitting material B were measured with a spectral radiance meter, the emission peak wavelength of the iridium complex compound A was 443 nm, and the emission peak wavelength of the light emitting material A was 530 nm. The emission peak wavelength of the luminescent material B was 622 nm.
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 light emitting layer with a thickness of It was formed by vacuum deposition so as to be 30 nm.
On the electron transport layer, lithium fluoride (LiF) was formed as an electron injection layer by vacuum deposition so as to have a thickness of 1 nm.
Next, a mask patterned as a cathode (a mask having a light emitting region of 2 mm × 2 mm) was placed on the electron injection layer, and metal aluminum was formed by vacuum evaporation 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 drive voltage, the external quantum efficiency, and the chromaticity deviation (Δ chromaticity) from pure white were evaluated as follows for the white organic electroluminescent device of Example 1 produced.

<Drive voltage>
Using a source measure unit type 2400 manufactured by KEITHLEY, the voltage at the time of direct current application was measured.

<Measurement of external quantum efficiency (EQE)>
A direct current was applied to the white organic electroluminescent element of Example 1 to emit light using a source measure unit 2400 type manufactured by KEITHLEY. The luminance at the time of light emission was measured using a luminance meter BM-8 manufactured by Topcon Corporation. The emission spectrum and emission wavelength were measured using an emission spectrum measurement system (ELS 1500) manufactured by Shimadzu Corporation. Based on these values, the external quantum efficiency was calculated by the brightness conversion method.

<Chromaticity deviation from pure white (Δ 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 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 deviation of chromaticity from pure white (Δ chromaticity) is calculated from the amount of deviation (Δx, Δy) of x value and y value from pure white (x = 0.33, y = 0.33). (Δy ² + Δx ² ) ^0.5 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 in Example 1 except that the iridium complex compound A was replaced with the iridium complex compound B represented by the following structural formula. It was 620 nm when the emission peak wavelength of the iridium complex compound B was measured with the emission spectrum measuring system.
In the same manner as in Example 1, the drive voltage, the external quantum efficiency, and the chromaticity deviation (Δ chromaticity) from pure white were evaluated.

(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 light emitting layer was produced as follows.
In the same manner as in Example 1, the drive voltage, the external quantum efficiency, and the chromaticity deviation (Δ chromaticity) from pure white were evaluated.
-Production of light emitting layer-
84.98% by mass of the compound B represented by the above structural formula as the host material, 5% by mass of the iridium complex compound A represented by the above structural formula with respect to the compound B, and represented by the following structural formula A light emitting layer doped with 10% by mass of the light emitting material C represented by the following structural formula that emits blue light and 0.02% by mass of the light emitting material B that emits red light represented by the above structural formula has a thickness of 30 nm. Formed by vacuum evaporation. Note that the emission peak wavelength of the luminescent material C was measured by an emission spectrum measurement system. As a result, it was light blue (474 nm) and green (502 nm) and red (590 nm) as sub-peaks.

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 in Example 1 except that the light emitting layer was produced as follows.
In the same manner as in Example 1, the drive voltage, the external quantum efficiency, and the chromaticity deviation (Δ chromaticity) from pure white were evaluated.
-Production of light emitting layer-
55% by mass of the compound B represented by the structural formula as a host material, 5% by mass of the iridium complex compound A represented by the structural formula with respect to the compound B, and light emission represented by the structural formula A light emitting layer doped with 40% by mass of Material C was formed by vacuum deposition so that the thickness was 50 nm.

(Example 5)
<Preparation of white organic electroluminescent element>
In Example 4, the white organic electroluminescent element of Example 5 was produced in the same manner as in Example 4 except that the luminescent material C represented by the structural formula was replaced with the luminescent material D represented by the following structural formula. did. In addition, it was 446 nm when the emission peak wavelength of the luminescent material D was measured with the emission spectrum measuring system.
In the same manner as in Example 1, the drive voltage, the external quantum efficiency, and the chromaticity deviation (Δ chromaticity) from pure white were evaluated.

(Example 6)
<Preparation of white organic electroluminescent element>
In Example 4, the white organic electroluminescent element of Example 6 was obtained in the same manner as in Example 4 except that Compound B represented by the structural formula described above as a host material was replaced with Compound C represented by the following structural formula. Was made.
In the same manner as in Example 1, the drive voltage, the external quantum efficiency, and the chromaticity deviation (Δ chromaticity) from pure white were evaluated.

(Example 7)
<Preparation of white organic electroluminescent element>
In Example 4, the white organic electroluminescent element of Example 7 was obtained in the same manner as in Example 4 except that the iridium complex compound A represented by the above structural formula was replaced with the iridium complex compound B represented by the above structural formula. Was made.
In the same manner as in Example 1, the drive voltage, the external quantum efficiency, and the chromaticity deviation (Δ chromaticity) from pure white were evaluated.

(Example 8)
<Preparation of white organic electroluminescent element>
In Example 1, the white organic electroluminescent element of Example 8 was produced in the same manner as in Example 1 except that the light emitting layer was produced as follows.
In the same manner as in Example 1, the drive voltage, the external quantum efficiency, and the chromaticity deviation (Δ chromaticity) from pure white were evaluated.
-Production of light emitting layer-
42% by mass of the compound B represented by the structural formula as a host material, 8% by mass of the iridium complex compound A represented by the structural formula with respect to the compound B, and light emission represented by the structural formula A light emitting layer doped with 50% by mass of Material C was formed by vacuum deposition so that the thickness was 30 nm.

(Comparative Example 1)
<Preparation of white organic electroluminescent element>
In Example 1, the white organic electroluminescent element of Comparative Example 1 was produced in the same manner as Example 1 except that the light emitting layer was produced as follows.
In the same manner as in Example 1, the drive voltage, the external quantum efficiency, and the chromaticity deviation (Δ chromaticity) from pure white were evaluated.
-Production of light emitting layer-
84.8% by mass of the compound B represented by the structural formula, which is a host material, and 15% by mass of the light-emitting material C represented by the structural formula with respect to the compound B, and the light emission represented by the structural formula A light emitting layer doped with 0.1% by mass of material A and 0.1% by mass of light emitting material B represented by the above structural formula was formed by vacuum deposition so that the thickness was 30 nm.

(Comparative Example 2)
<Preparation of white organic electroluminescent element>
In Example 1, the white organic electroluminescent element of Comparative Example 2 was prepared in the same manner as in Example 1 except that the iridium complex compound A represented by the above structural formula was replaced with the light emitting material D represented by the above structural formula. Produced.
In the same manner as in Example 1, the drive voltage, the external quantum efficiency, and the chromaticity deviation (Δ chromaticity) from pure white were evaluated.

About the white organic electroluminescent element produced in Examples 1-8 and Comparative Examples 1-2, the evaluation result of a drive voltage, external quantum efficiency, and chromaticity change, and element structure are shown in Tables 1-2.
(In the table, “wt%” represents mass%. Voltage, EQE (external quantum efficiency), and CIE chromaticity (x, y) are values at a current density of 11.6 mA / cm ^2. )

(In the table, “wt%” represents mass%. Voltage, EQE (external quantum efficiency), and CIE chromaticity (x, y) are values at a current density of 11.6 mA / cm ^2. )

  Examples 1-8 are compatible with low voltage, improvement in luminous efficiency, and adjustment of color balance as compared with Comparative Examples 1-2. This is presumably because the blue intensity was reinforced by the addition of an iridium complex compound having an emission peak wavelength of 400 nm to 450 nm.

  Since the white organic electroluminescent device of the present invention can adjust the voltage balance, low voltage, luminous efficiency, for example, display device, display, backlight, electrophotography, illumination light source, recording light source, exposure light source, reading light source. It is suitably used for signs, signs, interiors, optical communications, and the like.

DESCRIPTION OF SYMBOLS 10 White organic electroluminescent element 1 Board | substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Electron transport layer 7 Electron injection layer 8 Cathode

Claims (6)

A white organic electroluminescent device comprising at least a light emitting layer and a hole transport layer between an anode and a cathode,
The light emitting layer contains an iridium complex compound represented by the following structural formula (1) , and
The light emitting layer further contains at least one light emitting material capable of emitting light,
The luminescent material is any of the following general formula (1), general formula (2), and any of the following iridium complexes represented by general formula (3) or the following platinum complexes:
The white organic layer, wherein the hole transport layer contains at least N, N′-dinaphthyl-N, N′-diphenyl- [1,1′-biphenyl] -4,4′-diamine (NPD) Electroluminescent device.
However, in said structural formula (1), A represents -C (R < ₄ >)-or -N-, B represents -C (R < ₇ >)-or -N-,
R ₁ , R ₂ , R _{4 to} R ₇ are each independently a hydrogen atom, a cyano group, a hydroxy group, a nitro group, a halogen atom, an alkyl group having 1 to 20 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms. , An aryl group having 6 to 20 carbon atoms, an arylalkyl group having 7 to 20 carbon atoms, an alkylalkoxy group having 2 to 20 carbon atoms, an arylalkoxy group having 7 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, Represents an alkylamino group having 1 to 20 carbon atoms, a dialkylamino group having 1 to 20 carbon atoms, or a heterocyclic group having 2 to 20 carbon atoms, and R ₄ and R ₅ , R ₄ and R ₆ are connected to each other and saturated Or may form an unsaturated carbocyclic ring, a saturated or unsaturated heterocyclic ring,
R ₃ is a hydrogen atom, a cyano group, a hydroxy group, a nitro group, a halogen atom selected from a chlorine atom, a bromine atom and an iodine atom, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, carbon An aryl group having 6 to 20 carbon atoms, an arylalkyl group having 7 to 20 carbon atoms, an alkylalkoxy group having 2 to 20 carbon atoms, an arylalkoxy group having 7 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, and a carbon number An alkylamino group having 1 to 20 carbon atoms, a dialkylamino group having 1 to 20 carbon atoms, and a heterocyclic group having 2 to 20 carbon atoms,
X represents a monovalent anionic bidentate ligand selected from any of the following:
m represents 2 or 3, n represents 0 or 1, and the sum of m and n is 3.
However, in said general formula (1), (2) and (3), n represents the integer of 1-3. XY represents a bidentate ligand. Ring A represents a ring structure that may contain any of a nitrogen atom, a sulfur atom, and an oxygen atom. R ¹¹ represents a substituent, and m1 represents an integer of 0 to 6. When m1 is 2 or more, adjacent R ¹¹ may be bonded to form a ring which may contain any of a nitrogen atom, a sulfur atom and an oxygen atom, and the ring is further substituted with a substituent. May be. R ¹² represents a substituent, and m2 represents an integer of 0 to 4. When m2 is 2 or more, adjacent R ¹² may be bonded to form a ring which may contain any of a nitrogen atom, a sulfur atom and an oxygen atom, and the ring is further substituted with a substituent. May be. R ¹¹ and R ¹² may combine to form a ring that may contain any of a nitrogen atom, a sulfur atom, and an oxygen atom, and the ring may be further substituted with a substituent. .
The white organic electroluminescent element according to claim 1, wherein the content of the light emitting material is 0.01% by mass to 60% by mass with respect to the light emitting layer. The white organic electroluminescent element according to claim 1, wherein the emission peak wavelength of the luminescent material is 400 nm to 800 nm. The white organic electroluminescent element according to any one of claims 1 to 3, wherein a content of the iridium complex compound in the light emitting layer is 1% by mass to 50% by mass. The white organic electroluminescent element according to any one of claims 1 to 4, wherein the iridium complex compound emits light at a blue emission peak wavelength of 400 nm to 450 nm. The white organic electroluminescent element according to claim 1, wherein the light emitting layer further contains a host material.