TWI538560B - Organic electroluminescence element - Google Patents

Description

Organic electroluminescent element

The present invention relates to an organic electroluminescence device (hereinafter sometimes referred to as "organic electroluminescence device" or "organic EL device").

The organic electroluminescence element has characteristics such as self-luminescence, high-speed response, etc., and is expected to be applied to a flat panel display, etc., in particular, an organic thin film (hole transport layer) and electron transport for transporting holes are reported. Since a two-layer type (layered type) organic electroluminescence device in which an organic thin film (electron transport layer) is laminated, an organic electroluminescence device has been attracting attention as a large-area light-emitting device that emits light at a low voltage of 10 V or less. . The laminated organic electroluminescent device has a positive electrode/hole transport layer/light emitting layer/electron transport layer/negative electrode as a basic structure, and the light emitting layer may also be the above hole transport layer or the case of the above two layer type. The above electron transport layer has this function.

For such an organic electroluminescence device, various studies are being conducted in order to achieve high luminous efficiency. For example, in Patent Document 1, a condensed aromatic ring compound having a pyrene skeleton or an anthracene skeleton has been widely proposed as a host material constituting a phosphorescent material in combination with a phosphorescent dopant.

However, the proposed fused aromatic ring compound has a small triplet energy, and neither the disclosure nor the suggestion regarding the use of such a compound having a small triplet energy for the cathode side adjacent layer of the light-emitting layer. The reason for this is that the cathode side adjacent layer of the light-emitting layer is also referred to as an excitation suppressing layer, and the light-emitting efficiency is improved. In terms of the surface, it is preferable that the energy generated in the light-emitting layer is larger (the triplet energy of the adjacent layer on the cathode side is larger) (refer to Patent Document 2).

Here, FIG. 1A is a view showing the relationship between the triplet energy of the light-emitting layer 6 and the cathode-side adjacent layer 7, and the triplet energy (T1) of the cathode-side adjacent layer 7 is smaller than the triplet energy of the light-emitting material of the light-emitting layer 6 (T1). Therefore, energy is easily moved from the light-emitting layer 6 to the cathode-side adjacent layer 7, and the light-emitting efficiency of the light-emitting layer 6 is lowered. On the other hand, in FIG. 1B, since the triplet energy (T1) of the light-emitting material of the light-emitting layer 6 is equal to or higher than the triplet energy (T1) of the cathode-side adjacent layer 7, the energy is not easily self-luminous. When the cathode side adjacent layer 7 is moved, the light-emitting efficiency of the light-emitting layer 6 is improved.

On the other hand, when a cathode-side adjacent layer having a triplet energy larger than the triplet energy of the light-emitting layer of the light-emitting layer is used, the light-emitting efficiency of the light-emitting layer can be improved, but the driving durability is deteriorated.

Therefore, it is desirable to provide an organic electroluminescence device capable of realizing improvement in luminous efficiency and improvement in driving durability at high luminance and high current density as soon as possible.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2009-16693

[Patent Document 2] Japanese Patent No. 3992929

An object of the present invention is to provide an organic electroluminescence device which can improve luminous efficiency and drive durability at high luminance and high current density.

In order to solve the problem, the inventors of the present invention have conducted intensive studies and found that the electron-transporting layer adjacent to the cathode side adjacent to the cathode side of the light-emitting layer and the cathode side adjacent to the cathode-side adjacent layer In the organic electroluminescence device of the organic layer, when the triplet energy of the cathode-side adjacent layer is smaller than the triplet energy of the light-emitting layer of the light-emitting layer, the electron injectability may be improved and the light in the light-emitting layer may be improved. The distribution becomes flat, and an organic electroluminescence element having high luminous efficiency at high luminance and high current density and excellent driving durability is unexpectedly obtained.

The present invention is based on the above findings of the present inventors, and a method for solving the above problems is as follows. which is,

<1> An organic electroluminescence device comprising: an organic layer having at least one light-emitting layer between the anode and the cathode, and a cathode-side adjacent layer adjacent to a cathode side of the light-emitting layer, the cathode The triplet energy of the side adjacent layer is smaller than the triplet energy of the light emitting material of the light emitting layer.

The organic electroluminescence device according to the above aspect, wherein the organic layer further includes an electron transport layer adjacent to the cathode side of the cathode-side adjacent layer, and the triplet energy of the cathode-side adjacent layer is smaller than the electron transport layer. Triplet energy.

The organic electroluminescence device according to the above <1>, wherein the cathode-side adjacent layer contains a condensed aromatic ring compound.

The organic electroluminescence device of the above-mentioned <1>, wherein the cathode-side adjacent layer contains a compound having an anthracene derivative skeleton represented by the following formula (II), and has the following formula (I) At least one of the compounds of the anthracene derivative skeleton represented,

In the above formula (I), Ar ¹ and Ar ² are each independently a group derived from a substituted or unsubstituted aromatic ring having 6 to 20 carbon atoms. The above aromatic ring may be substituted with one or two or more substituents. The above substituent is selected from substituted or unsubstituted aryl group having 6 to 50 carbon atoms, substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, substituted or unsubstituted carbon number 3~ 50 cycloalkyl, substituted or unsubstituted alkoxy group having 1 to 50 carbon atoms, substituted or unsubstituted aralkyl group having 6 to 50 carbon atoms, substituted or unsubstituted nuclear atom a 5 to 50 aryloxy group, a substituted or unsubstituted arylthio group having 5 to 50 nucleus groups, a substituted or unsubstituted alkoxycarbonyl group having 1 to 50 carbon atoms, substituted or unsubstituted Substituted fluorenyl, carboxyl, halogen, cyano, nitro and hydroxy groups. When the aromatic ring is substituted with two or more substituents, the substituents may be the same or different, and adjacent substituents may be bonded to each other to form a saturated or unsaturated cyclic structure.

R ¹ to R ⁸ are a hydrogen atom, a substituted or unsubstituted aryl group having 6 to 50 carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 50 nuclear atoms, substituted or not Substituted alkyl group having 1 to 50 carbon atoms, substituted or unsubstituted cycloalkyl group having 3 to 50 carbon atoms, substituted or unsubstituted alkoxy group having 1 to 50 carbon atoms, substituted or not Substituted arylalkyl group having 6 to 50 carbon atoms, substituted or unsubstituted aryloxy group having 5 to 50 nuclear atoms, substituted or unsubstituted arylthio group having 5 to 50 nuclear atoms, A substituted or unsubstituted alkoxycarbonyl group having 1 to 50 carbon atoms, a substituted or unsubstituted alkylene group, a carboxyl group, a halogen atom, a cyano group, a nitro group and a hydroxyl group. Further, adjacent substituents may be bonded to each other to form a saturated or unsaturated cyclic structure.

In the above formula (II), Ar ^1a and Ar ^2a each represent a substituted or unsubstituted aromatic ring group having 6 to 50 carbon atoms.

L is a substituted or unsubstituted phenyl, substituted or unsubstituted anthranyl group, a substituted or unsubstituted fluorenyl group or a substituted or unsubstituted stilbene ring. Dibenzosilolylene.

m is an integer of 0 to 2, nb is an integer of 1 to 4, s is an integer of 0 to 2, and t is an integer of 0 to 4.

Further, L or Ar ^{1a is} bonded to any one of the 1st to the 5th positions of the oxime, and L or Ar ^{2a is} bonded to any of the 6th to the 10th positions of the oxime.

However, when nb+t is an even number, Ar ^1a , Ar ^2a , and L satisfy the following (1) or (2).

(1) Ar ^1a ≠Ar ^2a (where ≠ denotes a base of a different structure)

(2) When Ar ^1a =Ar ^2a

(2-1) m≠s and / or nb≠t, or

(2-2) When m=s and nb=t,

(2-2-1) L or 芘 are respectively bonded to different bonding positions on Ar ^1a and Ar ^2a , or

(2-2-2) pyrene in L or Ar ^1a and bonded to the same bonding position when, L or Ar ^1a and Ar ^2a to Ar ^2a on the position of the substituent is a pyrene and 6, or 2 The situation with 7 digits does not exist.

The organic electroluminescence device according to the above <1>, wherein the cathode-side adjacent layer has a thickness of 1 nm to 10 nm.

[Effects of the Invention]

According to the present invention, the prior art can be solved, and an organic electroluminescence element capable of achieving high luminous efficiency and improved driving durability can be provided.

The above and other objects, features and advantages of the present invention will become more <RTIgt;

(Organic Electroluminescent Element)

The organic electroluminescence device of the present invention has an organic layer having at least one light-emitting layer between the anode and the cathode, and a cathode-side adjacent layer adjacent to the cathode side of the light-emitting layer, and having the adjacent layer on the cathode side The electron transport layer adjacent to the cathode side has further layers as needed.

The present invention is characterized in that the triplet energy of the cathode side adjacent layer is smaller than the triplet energy of the light emitting material of the light emitting layer. If the triplet energy of the cathode side adjacent layer is greater than the triplet energy of the light emitting material of the light emitting layer, although it is advantageous to prevent exciton diffusion, the electron affinity of the material having a large triplet energy when transmitting electrons (electron affinity) The energy level is sometimes high, and sometimes it becomes a barrier to the charge from the electron transport layer to the light-emitting layer. Furthermore, since the triplet energy of the host material of the light-emitting layer is greater than the triplet energy of the light-emitting layer of the light-emitting layer, the magnitude relationship of the triplet energy of the adjacent layer on the cathode side is performed by the triplet energy of the light-emitting layer of the light-emitting layer. The comparison is enough.

Further, the triplet energy of the cathode side adjacent layer is preferably smaller than the triplet energy of the electron transport layer. When the triplet energy of the cathode side adjacent layer is larger than the triplet energy of the electron transport layer, excitons may be consumed in the electron transport layer when the excitons from the light emitting layer diffuse and fly over the adjacent layer. And the efficiency is declining.

Therefore, among the cathode side adjacent layer, the light-emitting material of the light-emitting layer, and the electron transport layer, the triplet energy of the cathode-side adjacent layer becomes the smallest value.

Here, in the organic electroluminescence device, the triplet energy of the cathode side adjacent layer, the light emitting material of the light emitting layer, and the electron transport layer may be (1) the state of the organic electroluminescence device is maintained, and the oblique cutting technique is used. After the electroluminescent element is obliquely cut, the triplet energy is estimated based on the difference of the mixed PL spectra of the layers using a photoluminescence (PL) method; or (2) by performing a time-of-flight secondary ion After the surface analysis by mass spectrometry (Time of fight-Secondary Ion Mass Spectrometry, TOF-SIMS), the molecular formula is identified, and the molecule is synthesized and a triplet energy is obtained from a single film.

<Light Emitting Layer>

The material, the shape, the structure, the size, and the like of the light-emitting layer are not particularly limited, and may be appropriately selected depending on the purpose. For example, the shape may be a film or a sheet, and the planar shape may be a square or a circle. For example, the above-mentioned structure may be a single layer structure or a laminated structure, and the above-described size may be appropriately selected depending on the use or the like.

As the material of the above-mentioned light-emitting layer, a phosphorescent light-emitting material and a host compound are suitable from the viewpoint of obtaining light emission (phosphorescence) from triplet excitons.

Furthermore, the light-emitting layer may contain two or more kinds of phosphorescent materials to increase the color purity or to expand the range of the light-emitting wavelength.

- Phosphorescent material -

The phosphorescent material is not particularly limited and may be appropriately selected depending on the intended purpose, and examples thereof include a transition metal atom and a lanthanoid atom.

Examples of the transition metal atom include ruthenium, rhodium, palladium, tungsten (tungstate), rhenium, osmium, iridium, and platinum. Among these, ruthenium, rhodium, and platinum are preferred, and rhodium and platinum are particularly preferred.

Examples of the above lanthanoid atom include lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, and dysprosium. ), holmium, Erbium, thulium, ytterbium, lutecium, and the like. Among them, the best ones are 钕, 铕, 釓.

Examples of the ligand of the above complex compound include: Comprehensive Coordination Chemistry by G. Wilkinson et al. (issued by Pergamon Press, 1987), and "Photochemistry and Photophysics of Coordination Compounds" by H. Yersin, Springer-Verlag, 1987. The ligands described in "Organic Metal Chemistry - Basics and Applications -" (Shanghuafang Company, issued in 1982) by Yamamoto Akira.

Specific ligands include a halogen ligand (preferably a chlorine ligand), an aromatic carbocyclic ligand (for example, a cyclopentadiene anion, a benzene anion or a naphthyl anion), and the like. A nitrogen heterocyclic ligand (for example, phenyl pyridine, benzoquinoline, quinolinol, bipyridyl, or phenanthroline), diketone coordination a group (e.g., acetamidine or the like), a carboxylic acid ligand (e.g., an acetate ligand, etc.), an alcoholate ligand (e.g., a phenolate ligand, etc.), a carbon monoxide ligand, an isonitrile group ( Isonitrile) a ligand, a cyano ligand, and the like. Among these, a nitrogen-containing heterocyclic ligand is particularly preferred.

The above complex compound may contain one transition metal atom in the compound, or may be a polynuclear complex containing two or more transition metal atoms. It can also contain different kinds of metal atoms. Among these, examples of the phosphorescent material include the following compounds, but are not limited thereto.

The phosphorescent material to be used as the complex compound containing ruthenium is not particularly limited, and may be appropriately selected according to the purpose, and is preferably any one of the following general formula (2), general formula (3), and general formula (4). The compound represented.

In the above formula (2), formula (3) and formula (4), n represents an integer of 1 to 3. XY represents a double tooth ligand. Ring A represents a ring structure which may contain any one 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 each other to form a ring which may contain any one of a nitrogen atom, a sulfur atom and an oxygen atom, and the ring may be further substituted with a substituent. 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 each other to form a ring which may contain any one of a nitrogen atom, a sulfur atom and an oxygen atom, and the ring may be further substituted with a substituent. Further, R ¹¹ and R ¹² may be bonded to each other to form a ring which may contain any one of a nitrogen atom, a sulfur atom and an oxygen atom, and the ring may be further substituted with a substituent.

The ring A is a ring structure which may contain any one of a nitrogen atom, a sulfur atom and an oxygen atom, and a 5-membered ring, a 6-membered ring or the like can be suitably used. This ring may be substituted with a substituent.

X-Y represents a bidentate ligand, and a monoanionic ligand of a double tooth or the like can be suitably exemplified.

Examples of the monoanionic ligand of the above-mentioned double teeth include picolinate (pic), acetylacetonate (acac), and di(trimethylacetyl) methanide (dipivaloylmethanate). Tributylacac) and the like.

The ligands other than the above are exemplified by the ligands described on pages 89 to 91 of the Handbook No. 2002/15645 of Lamansky et al.

The substituent of the above R ¹¹ and R ¹² is not particularly limited and may be appropriately selected depending on the purpose, and examples thereof include a halogen atom, an alkoxy group, an amine group, an alkyl group, a cycloalkyl group, and an aryl group which may contain a nitrogen atom or a sulfur atom. An aryloxy group which may contain a nitrogen atom or a sulfur atom, and these groups may be further substituted.

The groups adjacent to each other in the above R ¹¹ and R ¹² may be bonded to each other to form a ring which may contain a nitrogen atom, a sulfur atom or an oxygen atom, and a 5-membered ring or a 6-membered ring may be suitably used. This ring may be further substituted with a substituent.

Specific examples of the specific compound represented by any one of the above formula (2), formula (3) and formula (4) include, but are not limited to, the following compounds.

Other examples of the above phosphorescent material include the following compounds.

The content of the above phosphorescent material is preferably from 0.5 wt% to 30 wt%, more preferably from 0.5 wt% to 20 wt%, even more preferably from 3 wt% to 30 wt%, more preferably from 3 wt% to 20 wt%. %~10 wt%.

When the content is less than 0.5% by weight, the light-emitting efficiency may be small. When the content is more than 30% by weight, the light-emitting efficiency may be lowered due to the association of the phosphorescent material itself.

- host compound -

As the host compound, a hole transporting host compound having excellent hole transport properties and an electron transporting host compound having excellent electron transport properties can be used.

-- hole transporting host compound --

The above-mentioned hole transporting host compound is not particularly limited and may be appropriately selected depending on the purpose, and examples thereof include pyrrole, indole, carbazole, azaindole, and aza. Azacarbazole, pyrazole, imidazole, polyaryl aryl alkane, pyrazoline, pyrazolone, phenylene diamine, Arylamine, amine-substituted chalcone, styryl anthracene, fluorenone, hydrazone, stilbene, silazane, aromatic three a sulfhydryl compound, a styrylamine compound, an aromatic dimethylidyne compound, a porphyrin compound, a polydecane compound, a poly(N-vinylcarbazole), an aniline copolymer, A conductive polymer oligomer such as thiophene oligomer or polythiophene, an organic decane, a carbon film, or a derivative of these compounds.

Among these compounds, preferred are an anthracene derivative, a carbazole derivative, an azaindole derivative, an azacarbazole derivative, an aromatic tertiary amine compound, a thiophene derivative, and more preferably have a ruthenium in the molecule. A compound having an anthracene skeleton, a carbazole skeleton, an azaindole skeleton, an azacarbazole skeleton, or an aromatic tertiary amine skeleton is particularly preferably a compound having a carbazole skeleton.

Further, in the present invention, a host material in which a part or all of hydrogen of the above-mentioned host compound is substituted with hydrazine may be used (Japanese Patent Application No. 2008-126130, Japanese Patent Application Publication No. 2004-515506).

Specific examples of the specific compound of the hole transporting host compound include the following compounds, but are not limited thereto.

The content of the above-mentioned hole transporting host compound is preferably from 10% by weight to 99.9% by weight, more preferably from 20% by weight to 99.5% by weight, even more preferably from 30% by weight to 99% by weight, based on the total weight of the compound forming the above-mentioned light-emitting layer. .

--Electronic transport host compound --

The electron transporting host compound is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include pyridine, pyrimidine, triazine, imidazole, pyrazole, triazole, and oxazole. ), oxadiazole, anthrone, anthraquinone dimethane, anthrone, diphenylquinone, thiopyran dioxide, carbodiimide ), fluorenylidene methane, distyryl pyrazine, fluorine-substituted aromatic compound, naphthalene perylene, heterocyclic tetracarboxylic anhydride, phthalocyanine or the like a derivative of a compound (which can form a fused ring with other rings), a metal complex of an 8-hydroxyquinoline derivative, a metal phthalocyanine, a metal complex with a benzoxazole or a benzothiazole as a ligand Various metal complexes represented, etc.

Examples of the electron transporting host compound include a metal complex, an azole derivative (benzimidazole derivative, imidazopyridine derivative, etc.), and a azine derivative (pyridine derivative, pyrimidine derivative, triazine derivative). and many more. Among them, in the present invention, a metal complex compound is preferred in terms of durability. More preferably, the above metal complex compound has a coordination with a metal containing at least one nitrogen atom or an oxygen atom or a sulfur atom. A metal complex of a base.

The metal ion in the metal complex is not particularly limited, and is preferably cerium ion, magnesium ion, aluminum ion, gallium ion, zinc ion, indium ion, tin ion, platinum ion or palladium ion, more preferably cerium ion or aluminum. Ions, gallium ions, zinc ions, platinum ions or palladium ions, and thus preferably aluminum ions, zinc ions or palladium ions.

Various known ligands are known as the ligand contained in the metal complex, and examples thereof include "Photochemistry and Photophysics of Coordination Compounds" (Springer-Verlag, Inc., H. Yesin, issued in 1987). "Organic Metal Chemistry - Basics and Applications -" (Shanghuafang Company, Yamamoto Akio, issued in 1982) and other ligands.

The above ligand is, for example, a nitrogen-containing heterocyclic ligand (preferably having a carbon number of 1 to 30, more preferably a carbon number of 2 to 20, particularly preferably a carbon number of 3 to 15, and may be a single-dentate ligand). It may be a ligand of 2 or more teeth. It is preferably a ligand of 2 or more teeth and 6 or less teeth. Further, a mixed ligand of 2 or more teeth and 6 or less teeth and a single tooth are also preferable.

Examples of the ligand include a azine ligand (for example, a pyridine ligand, a bipyridine ligand, a terpyridine ligand, etc.), and a hydroxyphenylazole ligand (for example, hydroxyphenyl phenylhydrazine) Imidazole ligand, hydroxyphenylbenzoxazole ligand, hydroxyphenylimidazole ligand, hydroxyphenylimidazolium pyridine ligand, etc.), alkoxy ligand (preferably carbon number 1 to 30) More preferably, it has a carbon number of 1 to 20, particularly preferably a carbon number of 1 to 10, and examples thereof include a methoxy group, an ethoxy group, a butoxy group, a 2-ethylhexyloxy group, etc.), and an aryloxy group. (preferably, the carbon number is 6 to 30, more preferably the carbon number is 6 to 20, and particularly preferably the carbon number is 6 to 12, and examples thereof include a phenoxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, and 2,4. , 6-trimethylphenoxy, 4-biphenyloxy, etc.), heteroaryloxy ligand (preferably having a carbon number of 1 to 30, more preferably a carbon number of 1 to 20, particularly preferably a carbon number) Examples of the examples 1 to 12 include a pyridyloxy group, a pyrazinyloxy group, a pyrimidinyloxy group, and a quinolyloxy group, and an alkylthio group (preferably having a carbon number of 1 to 30, more preferably a carbon number of 1 to 1). 20, particularly preferably a carbon number of 1 to 12, for example, a methylthio group, an ethylthio group, etc.), an arylthio group (preferably a carbon number of 6 to 30, more preferably a carbon number of 6 to 20, particularly preferably a carbon number of 6 to 12, for example, a phenylthio group or the like, a heteroarylthio group (preferably having a carbon number of 1 to 30, more preferably carbon) The number is from 1 to 20, particularly preferably from 1 to 12, and examples thereof include a pyridylthio group, a 2-phenylimidazoliumthio group, a 2-benzoxazolethio group, a 2-benzoquinazolylthio group, and the like, and an alkoxy group. The base group (preferably having a carbon number of 1 to 30, more preferably 3 to 25 carbon atoms, particularly preferably 6 to 20 carbon atoms), and examples thereof include a triphenylalkoxy group and a triethoxy alkoxy group. A trivalent alkoxy group or the like, an aromatic hydrocarbon anion ligand (preferably having a carbon number of 6 to 30, more preferably a carbon number of 6 to 25, particularly preferably a carbon number of 6 to 20), and examples thereof include a phenyl group. An anion, a naphthyl anion, a mercapto anion or the like) or an aromatic heterocyclic anion ligand (preferably having a carbon number of from 1 to 30, more preferably a carbon number of from 2 to 25, particularly preferably a carbon number of from 2 to 20, for example, List pyrrole anion, pyrazole anion, pyrazole anion, triazole anion, oxazole anion, benzoxazole anion, thiazole anion, benzothiazole anion, thiophene anion, benzoquinone anion, etc.), indolenine Anionic ligand Preferred as a nitrogen-containing heterocyclic ligand, an aryloxy ligand, a heteroaryloxy group or an alkoxy ligand, more preferably a nitrogen-containing heterocyclic ligand, an aryloxy ligand, or an alkane An oxy ligand, an aromatic hydrocarbon anionic ligand or an aromatic heterocyclic anion ligand.

The above-mentioned metal complex electron-transporting host compound is exemplified by, for example, JP-A-2002-235076, JP-A-2004-214179, JP-A-2004-221062, and JP-A-2004-221065 The compound described in Japanese Laid-Open Patent Publication No. 2004-221313, and the like.

Specific examples of such an electron transporting host compound include, but are not limited to, the following materials.

The content of the electron transporting host compound is preferably from 10% by weight to 99.9% by weight, more preferably from 20% by weight to 99.5% by weight, even more preferably from 30% by weight to the total weight of the compound forming the light-emitting layer. 99 wt%.

The light-emitting layer is a layer having a function of receiving a hole from an anode, a hole injection layer or a hole transport layer when an electric field is applied, and receiving electrons from a cathode, an electron injection layer or an electron transport layer to provide a hole and an electron. The light is combined with the place.

The light-emitting layer is not particularly limited and may be formed according to a known method, and may be, for example, a dry film forming method such as a vapor deposition method or a sputtering method, a wet coating method, a transfer method, a printing method, or an ink jet method. It is formed as appropriate.

The thickness of the light-emitting layer is not particularly limited, and may be appropriately selected depending on the purpose, and is preferably 2 nm to 500 nm, and more preferably 3 nm to 200 nm, and more preferably 10 nm to 200 nm from the viewpoint of light-emitting efficiency. In addition, the light-emitting layer may be one layer or two or more layers.

<Cathode side adjacent layer>

The cathode-side adjacent layer is an organic layer adjacent to the cathode side of the light-emitting layer, and functions as a hole blocking layer that prevents the hole transmitted from the anode side to the light-emitting layer from passing to the cathode side.

The triplet energy of the cathode side adjacent layer is smaller than the triplet energy of the light emitting material of the light emitting layer as described above.

The cathode side adjacent layer preferably contains a fused aromatic ring compound.

The condensed aromatic ring compound is not particularly limited and may be appropriately selected according to the purpose, and is preferably a compound containing an anthracene derivative skeleton represented by the following formula (II), and having the following formula (I) At least one of the compounds of the anthracene derivative skeleton represented.

In the above formula (I), Ar ¹ and Ar ² are each independently a group derived from a substituted or unsubstituted aromatic ring having 6 to 20 carbon atoms. The above aromatic ring may be substituted with one or two or more substituents. The above substituent is selected from substituted or unsubstituted aryl group having 6 to 50 carbon atoms, substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, substituted or unsubstituted carbon number 3~ 50 cycloalkyl, substituted or unsubstituted alkoxy group having 1 to 50 carbon atoms, substituted or unsubstituted aralkyl group having 6 to 50 carbon atoms, substituted or unsubstituted nuclear atom a 5 to 50 aryloxy group, a substituted or unsubstituted arylthio group having 5 to 50 nucleus groups, a substituted or unsubstituted alkoxycarbonyl group having 1 to 50 carbon atoms, substituted or unsubstituted Substituted fluorenyl, carboxyl, halogen, cyano, nitro and hydroxy groups. When the aromatic ring is substituted with two or more substituents, the substituents may be the same or different, and adjacent substituents may be bonded to each other to form a saturated or unsaturated cyclic structure.

R ¹ to R ⁸ are a hydrogen atom, a substituted or unsubstituted aryl group having 6 to 50 carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 50 nuclear atoms, substituted or not Substituted alkyl group having 1 to 50 carbon atoms, substituted or unsubstituted cycloalkyl group having 3 to 50 carbon atoms, substituted or unsubstituted alkoxy group having 1 to 50 carbon atoms, substituted or not Substituted arylalkyl group having 6 to 50 carbon atoms, substituted or unsubstituted aryloxy group having 5 to 50 carbon atoms, substituted or unsubstituted arylthio group having 5 to 50 nuclear atoms, A substituted or unsubstituted alkoxycarbonyl group having 1 to 50 carbon atoms, a substituted or unsubstituted alkylene group, a carboxyl group, a halogen atom, a cyano group, a nitro group and a hydroxyl group. Further, adjacent substituents may be bonded to each other to form a saturated or unsaturated cyclic structure.

In the above formula (II), Ar ^1a and Ar ^2a each represent a substituted or unsubstituted aromatic ring group having 6 to 50 carbon atoms.

L is a substituted or unsubstituted phenyl, substituted or unsubstituted anthranyl group, a substituted or unsubstituted fluorenyl group or a substituted or unsubstituted stilbene ring. Dienyl.

m is an integer of 0 to 2, nb is an integer of 1 to 4, s is an integer of 0 to 2, and t is an integer of 0 to 4.

Further, L or Ar ^{1a is} bonded to any one of the 1st to the 5th positions of the oxime, and L or Ar ^{2a is} bonded to any of the 6th to the 10th positions of the oxime.

However, when nb+t is an even number, Ar ^1a , Ar ^2a , and L satisfy the following (1) or (2).

(1) Ar ^1a ≠Ar ^2a (where ≠ denotes a base of a different structure)

(2) When Ar ^1a =Ar ^2a

(2-1) m≠s and / or nb≠t, or

(2-2) When m=s and nb=t,

(2-2-1) L or 芘 are respectively bonded to different bonding positions on Ar ^1a and Ar ^2a ,

(2-2-2) pyrene in L or Ar ^1a and bonded to the same bonding position when, L or Ar ^1a and Ar ^2a to Ar ^2a on the position of the substituent is a pyrene and 6, or 2 The situation with 7 digits does not exist.

Specific examples of the compound having the anthracene derivative skeleton represented by the following formula (II) are listed below, but the present invention is not limited to these compounds.

Specific examples of the compound having the anthracene derivative skeleton represented by the above formula (I) are listed below, but the present invention is not limited to these compounds.

The cathode side adjacent layer is not particularly limited, and can be formed according to a known method. For example, a dry film forming method such as a vapor deposition method or a sputtering method, a wet coating method, a transfer method, a printing method, or a spray method can be used. It is suitably formed by an ink method or the like.

The thickness of the cathode side adjacent layer is preferably from 1 nm to 10 nm, more preferably from 2 nm to 5 nm. When the thickness is less than 1 nm, the cathode-side adjacent layer may not be formed, and the effect of high efficiency or high durability may be insufficient. When the thickness exceeds 10 nm, when the electron mobility of the adjacent layer on the cathode side is high, Sometimes the organic electroluminescent element is increased in voltage.

<Electronic Transport Layer>

The electron transporting layer is a layer having a function of accepting electrons from the cathode or the cathode side and transmitting to the anode side. As described above, the triplet energy of the electron transporting layer is preferably larger than the triplet energy of the adjacent layer on the cathode side.

The material of the above electron transporting layer is not particularly limited and may be appropriately selected depending on the purpose, and examples thereof include 2,9-dimethyl-4,7-diphenyl-1,10-morpho represented by the following structural formula. a porphyrin (Bathocuproine, BCP), a material in which Li is doped with BCP, or 8-hydroxyquinoline such as tris(8-hydroxyquinoline)aluminum (Alq) represented by the following structural formula or An organometallic complex of a derivative as a ligand, BAlq (bis-(2-methyl-8-hydroxyquinoline)-4-(phenylphenolated) aluminum (III) represented by the following structural formula, Quinoline derivatives such as Bis-(2-methyl-8-quinolinolato)-4-(phenyl-phenolate)-aluminium(III)), oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, anthracene derivatives A pyridine derivative, a pyrimidine derivative, a quinoxaline derivative, a diphenyl hydrazine derivative, a nitro-substituted hydrazine derivative, or the like. Among these materials, a material in which Li is doped in BCP, BAlq is particularly preferred.

The electron transport layer may be, for example, an evaporation method, a wet film formation method, an electron beam method, a sputtering method, a reactive sputtering method, a molecular beam epitaxy (MBE) method, or a cluster ion beam (cluster). Ion beam method, ion plating method, plasma polymerization method (high frequency excited ion plating method), molecular layering method, Langmuir-Blodgett (LB) method, printing method, The above method such as a transfer method is suitably formed.

The thickness of the electron transport layer is not particularly limited and may be appropriately selected depending on the purpose, and is, for example, preferably 1 nm to 500 nm, more preferably 10 nm to 50 nm.

The electron transport layer may have a single layer structure or a laminate structure.

The organic electroluminescence device of the present invention has an organic layer having at least one light-emitting layer between the anode and the cathode, and a cathode-side adjacent layer adjacent to the cathode side of the light-emitting layer, and may have an adjacent layer on the cathode side. The electron transport layer adjacent to the cathode side may further have other layers as needed.

The other layer is not particularly limited and may be appropriately selected depending on the purpose, and examples thereof include an electron injection layer, a hole injection layer, a hole transport layer, and an electron block layer.

-Electronic injection layer -

The above electron injecting layer is a layer having a function of accepting electrons from the cathode or the cathode side and transporting it to the anode side.

The electron injecting layer may be a single layer structure formed of one or two or more materials, or may be a multilayer structure composed of a plurality of layers of the same composition or different types.

The thickness of the electron injecting layer is not particularly limited and may be appropriately selected depending on the purpose, and is preferably 0.1 nm to 200 nm, more preferably 0.2 nm to 100 nm, and still more preferably 0.5 nm to 50 nm.

- Hole injection layer, hole transmission layer -

The hole injection layer and the hole transport layer are layers having a function of receiving a hole from the anode or the anode side and transporting it to the cathode side. The hole injection layer and the hole transport layer may have a single layer structure, or may have a multilayer structure composed of a plurality of layers of the same composition or different species.

The hole injecting material or the hole transporting material used in the layers may be a low molecular compound or a high molecular compound.

The hole injection material or the hole transport material is not particularly limited and may be appropriately selected depending on the purpose, and examples thereof include a pyrrole derivative, a carbazole derivative, a triazole derivative, an oxazole derivative, and an oxadiazole derivative. Imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amine-substituted chalcone derivatives, styrylpurine derivatives , anthrone derivative, anthracene derivative, stilbene derivative, decazane derivative, aromatic tertiary amine compound, styrylamine compound, aromatic secondary methyl compound, phthalocyanine compound, hydrazine A porphyrin compound, a thiophene derivative, an organic decane derivative, carbon or the like. These materials may be used alone or in combination of two or more.

The hole injection layer and the hole transport layer may contain an electron-accepting dopant.

The electron-accepting dopant can be used as long as it has an electron-donating property of oxidizing an organic compound.

The inorganic compound is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include a metal halide such as ferric chloride, aluminum chloride, gallium chloride, indium chloride, and antimony pentachloride; vanadium pentoxide and trioxide. A metal oxide such as molybdenum or the like.

The organic compound is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include a compound having a substituent such as a nitro group, a halogen group, a cyano group or a trifluoromethyl group; an anthraquinone compound, an acid anhydride compound, and fullerene; (fullerene) and so on. These compounds may be used alone or in combination of two or more.

The amount of the electron-accepting dopant to be used is not particularly limited and varies depending on the type of the material, and is preferably 0.01 wt% to 50 wt%, more preferably 0.01 to 50% by weight, based on the material of the hole transport layer or the hole injecting material. 0.05 wt% to 30 wt%, and more preferably 0.1 wt% to 30 wt%.

The hole injection layer and the hole transport layer are not particularly limited, and can be formed by a known method, for example, a dry film forming method such as a vapor deposition method or a sputtering method, a wet coating method, or a transfer method. A printing method, an inkjet method, or the like is suitably formed.

The thickness of the hole injection layer and the hole transport layer is preferably from 1 nm to 500 nm, more preferably from 5 nm to 250 nm, and even more preferably from 10 nm to 200 nm.

-Electronic barrier layer -

The electron blocking layer is a layer having a function of preventing electrons transmitted from the cathode side to the light-emitting layer from passing to the anode side, and is usually provided as an organic layer adjacent to the anode side of the light-emitting layer.

As the compound constituting the above electron blocking layer, for example, a material exemplified as the above-mentioned hole transporting material can be used. Further, the electron blocking layer may have a single layer structure formed of one or two or more kinds of the above materials, or may have a multilayer structure composed of a plurality of layers of the same composition or different kinds.

The electron blocking layer is not particularly limited, and can be formed by a known method, for example, a dry film forming method such as a vapor deposition method or a sputtering method, a wet coating method, a transfer method, a printing method, or an ink jet method. The method is suitably formed.

The thickness of the electron blocking layer is preferably from 1 nm to 200 nm, more preferably from 1 nm to 50 nm, and even more preferably from 3 nm to 10 nm.

<electrode>

The organic electroluminescent device of the present invention has a pair of electrodes, that is, an anode and a cathode. In terms of the properties of the above organic electroluminescent device, it is preferred that at least one of the anode and the cathode be transparent. In general, the anode may have a function as an electrode for supplying a hole to the organic layer, and the cathode may have a function as an electrode for injecting electrons into the organic layer.

The shape, structure, size, and the like of the above electrode are not particularly limited, and can be appropriately selected from known electrode materials in accordance with the use and purpose of the organic electroluminescence device.

The material constituting the above electrode may, for example, be a metal, an alloy, a metal oxide, a conductive compound or a mixture of these materials.

-anode-

Examples of the material constituting the anode include conductivity of tin oxide (ATO, FTO) doped with antimony or fluorine, tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and zinc indium oxide (IZO). a metal oxide; a metal such as gold, silver, chromium, or nickel; a mixture or laminate of the metal and a conductive metal oxide; an inorganic conductive material such as copper iodide or copper sulfide; polyaniline, polythiophene, and poly An organic conductive material such as pyrrole or a laminate of these materials and ITO. Among these materials, a conductive metal oxide is preferable, and ITO is particularly preferable in terms of productivity, high conductivity, transparency, and the like.

-cathode-

Examples of the material constituting the cathode include an alkali metal (for example, Li, Na, K, Cs, etc.), an alkaline earth metal (for example, Mg, Ca, etc.), gold, silver, lead, aluminum, a sodium-potassium alloy, and a lithium-aluminum alloy. , rare earth metals such as magnesium-silver alloys, indium, and antimony. These materials may be used singly, and two or more types may be used in combination as long as they have both stability and electron injectability.

Among these materials, in terms of electron injectability, an alkali metal or an alkaline earth metal is preferable, and in terms of excellent storage stability, a material mainly composed of aluminum is particularly preferable.

The above-mentioned material mainly composed of aluminum refers to an alloy of aluminum alone, aluminum and 0.01 wt% to 10 wt% of an alkali metal or an alkaline earth metal or a mixture of such metals (for example, lithium-aluminum alloy, magnesium-aluminum alloy, etc.). .

The method for forming the electrode is not particularly limited, and may be carried out according to a known method, and examples thereof include a wet method such as a printing method and a coating method, and a physical method such as a vacuum deposition method, a sputtering method, and an ion plating method. Chemical methods such as chemical vapor deposition (CVD), plasma CVD, and the like. These methods can be formed on the substrate in accordance with a method which is appropriately selected in consideration of the suitability of the material constituting the electrode. For example, when ITO is selected as the material of the anode, it can be formed by a direct current or high frequency sputtering method, a vacuum evaporation method, an ion plating method, or the like. When a metal or the like is selected as the material of the cathode, one or two or more kinds thereof may be formed simultaneously or sequentially in accordance with a sputtering method or the like.

Further, in the case of patterning when the electrode is formed, it may be performed by chemical etching using photolithography or the like, or by physical etching using laser or the like, or may be overlapped. The mask is performed by vacuum vapor deposition, sputtering, or the like, and may be performed by a lift-off method or a printing method.

<Substrate>

The organic electroluminescence device of the present invention is preferably provided on a substrate, and may be provided in such a manner that the electrode is in direct contact with the substrate, or may be provided in a state in which the intermediate layer is interposed.

The material of the substrate is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include inorganic materials such as yttria-stabilized zirconia (YSZ) and glass (alkali-free glass, soda lime glass, etc.); Polyesters such as ethylene terephthalate, polybutylene phthalate, polyethylene naphthalate, etc.; polystyrene, polycarbonate, polyether sulfone, poly Organic materials such as polyarylate, polyimine, polycycloolefin, norbornene resin, poly(chlorotrifluoroethylene), and the like.

The shape, structure, size, and the like of the substrate are not particularly limited, and may be appropriately selected depending on the use, purpose, and the like of the organic electroluminescence device. Generally, the shape of the substrate is preferably a plate shape. The structure of the substrate may be a single layer structure or a laminated structure, and may be formed of a single member or may be formed of two or more members. The substrate may be transparent or opaque, and in the case of transparency, it may be colorless and transparent or colored and transparent.

For the above substrate, a moisture-proof layer (gas barrier layer) may be provided on the front or back surface thereof.

The material of the moisture-proof layer (gas barrier layer) may, for example, be an inorganic material such as tantalum nitride or cerium oxide.

The moisture-proof layer (gas barrier layer) can be formed, for example, by a high-frequency sputtering method or the like.

-The protective layer-

The organic electroluminescent element as a whole can also be 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 deterioration of a component such as moisture or oxygen, and may be appropriately selected depending on the purpose, and examples thereof include In, Sn, and Pb. Metals such as Au, Cu, Ag, Al, Ti, Ni; metals such as MgO, SiO, SiO ₂ , Al ₂ O ₃ , GeO, NiO, CaO, BaO, Fe ₂ O ₃ , Y ₂ O ₃ , TiO ₂ Oxide; metal nitride of SiNx, SiNxOy, etc.; metal fluoride of MgF ₂ , LiF, AlF ₃ , CaF _{2 ,} etc.; polyethylene, polypropylene, polymethyl methacrylate, polyimine, polyurea, poly a copolymer of tetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, chlorotrifluoroethylene and dichlorodifluoroethylene, copolymerization of a monomer mixture containing tetrafluoroethylene and at least one comonomer The copolymer, a fluorine-containing copolymer having a cyclic structure in a copolymerization main chain, a water-absorbent substance having a water absorption ratio of 1% or more, a moisture-proof substance having a water absorption ratio of 0.1% or less, and the like.

The method for forming the protective layer is not particularly limited, and may be appropriately selected depending on the purpose, and examples thereof include a vacuum deposition method, a sputtering method, a reactive sputtering method, an MBE (molecular beam epitaxy) method, and a cluster ion beam method. Ion plating method, plasma polymerization method (high-frequency excitation ion plating method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, coating method, printing method, transfer method, and the like.

- sealed container -

The organic electroluminescence device of the present invention can also be used to seal the entire device using a sealed container. Further, a moisture absorbent or an inactive liquid may be enclosed in a space between the sealed container and the organic electroluminescent element.

The moisture absorbent is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include cerium oxide, sodium oxide, potassium oxide, calcium oxide, sodium sulfate, calcium sulfate, magnesium sulfate, phosphorus pentoxide, and chlorine. Calcium, magnesium chloride, copper chloride, barium fluoride, barium fluoride, calcium bromide, vanadium bromide, molecular sieve, zeolite, magnesium oxide, and the like.

The above-mentioned inert liquid is not particularly limited and may be appropriately selected depending on the intended purpose, and examples thereof include paraffin, liquid paraffin, perfluoroalkane, perfluoroalkane, perfluoroether, and the like. It is a solvent, a silicone oil, or the like.

- resin sealing layer -

The organic electroluminescence device of the present invention preferably suppresses deterioration of element performance due to oxygen or moisture from the atmosphere by sealing with a resin sealing layer.

The resin material of the resin sealing layer is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include an acrylic resin, an epoxy resin, a fluorine resin, a polyoxyn resin, a rubber resin, and an ester resin. Among these resins, an epoxy resin is particularly preferable in terms of preventing the function of moisture. Among the above epoxy resins, a thermosetting epoxy resin or a photocurable epoxy resin is preferred.

The method for producing the resin sealing layer is not particularly limited, and may be appropriately selected depending on the purpose, and examples thereof include a method of applying a resin solution, a method of pressure-bonding or thermocompression bonding a resin sheet, and vapor deposition or sputtering. Dry polymerization method, etc.

-Sealing Adhesive -

The above sealing adhesive has a function of preventing moisture or oxygen from infiltrating from the end.

The material of the above-mentioned sealing adhesive can be the same as that used for the above-mentioned resin sealing layer. Among these materials, in terms of preventing penetration of moisture, an epoxy-based adhesive is preferable, and a photo-curing adhesive or a thermosetting adhesive is particularly preferable.

A filler may also be added to the above sealing adhesive. The filler is preferably an inorganic material such as SiO ₂ , SiO (yttria), SiON (niobium oxynitride) or SiN (tantalum nitride). By adding the filler, the viscosity of the sealing adhesive is improved, the processing suitability is improved, and the moisture resistance is improved.

The above sealing adhesive may also contain a desiccant. Examples of the desiccant include cerium oxide, calcium oxide, cerium oxide, and the like. The amount of the desiccant added is preferably from 0.01% by weight to 20% by weight, more preferably from 0.05% by weight to 15% by weight, based on the above-mentioned sealing adhesive. When the amount added is less than 0.01% by weight, the effect of adding the desiccant is weak, and when the amount added is more than 20% by weight, it may be difficult to uniformly disperse the desiccant in the sealing adhesive.

In the present invention, the sealing adhesive containing the desiccant may be applied in an arbitrary amount by a dispenser or the like, and after coating, the second substrate may be superposed and cured to be sealed.

2 is a schematic view showing an example of a layer configuration of an organic electroluminescence device of the present invention. The organic electroluminescent element 11 has an anode 2 (for example, an ITO electrode) to be formed on the glass substrate 1, a hole injection layer 3, a hole transport layer 4, an electron blocking layer 5, a light-emitting layer 6, and a cathode side adjacent layer (electrical The hole barrier layer 7 is formed of a layer in which the electron transport layer 8, the electron injection layer 9, and the cathode 10 (for example, an Al-Li electrode) are sequentially laminated. Further, the anode 2 (for example, an ITO electrode) and the cathode 10 (for example, an Al-Li electrode) are connected to each other via a power source.

-drive-

The organic electroluminescence device of the present invention can emit light by applying a direct current (and optionally an alternating component) voltage (usually 2 V (volts) to 15 V) or a direct current between the anode and the cathode.

The organic electroluminescent device of the present invention can be applied to an active matrix by a Thin Film Transistor (TFT). As the active layer of the thin film transistor, amorphous germanium, high temperature polycrystalline germanium, low temperature polycrystalline germanium, microcrystalline germanium, an oxide semiconductor, an organic semiconductor, a carbon nanotube or the like can be applied.

The organic electroluminescence device of the present invention is, for example, a thin film transistor described in the specification of WO2005/088726, Japanese Patent Laid-Open No. Hei. No. 2006-165529, and U.S. Patent Application Publication No. 2008/0237598 A1.

The organic electroluminescence device of the present invention is not particularly limited, and the light extraction efficiency can be improved by various known methods. For example, the surface of the substrate can be processed (for example, a fine concavo-convex pattern is formed), the refractive index of the substrate, the ITO layer, and the organic layer can be controlled, and the thickness of the substrate, the ITO layer, and the organic layer can be controlled to improve the light extraction efficiency. External quantum efficiency is improved.

The light extraction method of the organic electroluminescence device of the present invention may be a top emission method or a bottom emission method.

The organic electroluminescent device of the present invention may have a resonator structure. For example, a multilayer film mirror having a plurality of laminated films having different refractive indices, a transparent or semi-transparent electrode, a light-emitting layer, and a metal electrode may be superposed on a transparent substrate. The light generated in the light-emitting layer resonates and reflects the multilayer film mirror and the metal electrode as a reflecting plate.

In another preferred embodiment, the transparent or semi-transparent electrode and the metal electrode function as a reflecting plate on the transparent substrate, and light generated in the light-emitting layer reverberates and resonates therebetween.

In order to form a resonant structure, the optical path length determined by the effective refractive index of the two reflecting plates and the refractive index and thickness of each layer between the reflecting plates is adjusted to a value optimum for obtaining a desired resonant wavelength. The calculation formula of the case of the first aspect is described in Japanese Laid-Open Patent Publication No. Hei 9-180883. The calculation formula of the case of the second aspect is described in Japanese Laid-Open Patent Publication No. 2004-127795.

-use-

The organic electroluminescence device of the present invention is not particularly limited and may be appropriately selected according to the purpose, and may be suitably used for a display element, a display, a backlight, an electrophotographic photograph, an illumination source, a recording light source, an exposure light source, Read light sources, logos, billboards, interiors, optical communications, and more.

Regarding the method of making the above-described organic electroluminescence display into a full-color type, as described in the "Monthly Display" (September 2000 issue), pages 33 to 37, three primary colors (blue) which are respectively emitted and colored are known. The organic electroluminescence device of the light corresponding to the color (B), the green (G), and the red (R) is disposed on the substrate by the three-color luminescence method, and the white luminescence of the organic electroluminescence device for the white luminescence is passed through the color filter. A white method in which three colors are divided into a color filter, and a blue light emission of an organic electroluminescence element for blue light emission is converted into red (R) and green (G) color conversion methods by a fluorescent pigment layer. . Further, a planar light source of a desired luminescent color can also be obtained by using a plurality of organic electroluminescent elements of different luminescent colors obtained by the above method in combination. For example, a white light-emitting source in which blue and yellow light-emitting elements are combined, and a white light-emitting source in which blue, green, and red light-emitting elements are combined may be mentioned.

[Example]

Hereinafter, examples of the invention will be described, but the invention is not limited by the examples.

(Example 1)

-Production of organic electroluminescent elements -

Indium Tin Oxide (ITO) was provided as an anode on a 0.5 mm thick, 2.5 cm square glass substrate by sputtering at a thickness of 100 nm. Next, the ITO-attached glass substrate was placed in a cleaning container, ultrasonically washed in 2-propanol, and subjected to ultraviolet (ultraviolet, UV)-ozone treatment for 30 minutes. The following layers were deposited on the ITO-attached glass substrate by vacuum deposition.

In addition, the vapor deposition rate in the following examples and comparative examples is 0.1 nm/s unless otherwise specified. The vapor deposition rate was measured using a crystal oscillator. In addition, the thickness of each of the following layers was measured using a crystal oscillator.

First, on the anode (ITO), 4,4',4"-tris(N,N-(2-naphthalene) represented by the following structural formula is formed by vacuum evaporation so as to have a thickness of 120 nm. The base)-phenylamino)triphenylamine (2-TNATA) was doped with 0.3 wt% of a hole injection layer of F4-TCNQ represented by the following structural formula.

Then, on the hole injection layer, NPD (N, N'-dinaphthyl-N, which is represented by the following structural formula as a hole transport layer, is formed by a vacuum deposition method so as to have a thickness of 7 nm. N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine).

Then, a compound represented by the following structural formula as an electron blocking layer was formed on the hole transport layer by a vacuum deposition method so as to have a thickness of 3 nm.

Next, a compound A represented by the following structural formula as a host material and a lower concentration of 15 wt% as a phosphorescent luminescent material with respect to the compound A were formed by vacuum deposition at a thickness of 30 nm. The light-emitting layer of the compound B represented by the structural formula.

Then, on the light-emitting layer, a compound C represented by the following structural formula as a cathode-side adjacent layer was formed by a vacuum deposition method to a thickness of 3 nm (tbppy(1,3,6,8-tetra(( 4-biphenyl)芘)).

Then, on the cathode-side adjacent layer, bis-(2-methyl-8-hydroxyquinoline) represented by the following structural formula as an electron transport layer was formed by vacuum evaporation so as to have a thickness of 30 nm. 4-(phenylphenolated) aluminum (III) (Bis-(2-methyl-8-quinolinolato)-4-(phenyl-phenolate)-alum inium (III), BAlq).

Next, lithium fluoride (LiF) as an electron injection layer was formed on the electron transport layer by a vacuum deposition method so as to have a thickness of 1 nm.

Then, a patterned mask (a mask having a light-emitting area of 2 mm × 2 mm) was provided on the electron injecting layer, and a metal aluminum as a cathode was formed by vacuum evaporation so as to have a thickness of 100 nm.

The laminate produced by the above operation was placed in an argon-substituted glove box, and a stainless steel sealed can and an ultraviolet curing adhesive (XNR5516HV, manufactured by Nagase Ciba Co., Ltd.) were used. Sealed. The organic electroluminescence element of Example 1 was produced by the above operation.

(Example 2)

-Production of organic electroluminescent elements -

In the example 1, an organic electroluminescent device was produced in the same manner as in Example 1 except that the compound C represented by the above structural formula was replaced with the compound D represented by the following structural formula as the cathode-side adjacent layer.

(Example 3)

-Production of organic electroluminescent elements -

In Example 1, except that the compound C represented by the above structural formula was replaced by the compound E (4,4'-bis(2,2-diphenylvinyl)phenylanthracene (DPVDPAN) represented by the following structural formula. An organic electroluminescence device was produced in the same manner as in Example 1 except that the cathode side adjacent layer was used.

(Example 4)

In Example 1, an organic electroluminescence device was produced in the same manner as in Example 1 except that the thickness of the cathode-side adjacent layer was changed from 3 nm to 10 nm.

(Example 5)

In Example 1, except that BAlq represented by the above structural formula was changed to a material in which 1 wt% of Li was incorporated in BCP represented by the following structural formula as an electron transport layer, organic electricity was produced in the same manner as in Example 1. Photoluminescent element.

(Comparative Example 1)

-Production of organic electroluminescent elements -

In Example 1, an organic electroluminescence device was produced in the same manner as in Example 1 except that the cathode side adjacent layer was not provided.

(Comparative Example 2)

-Production of organic electroluminescent elements -

In the example 1, an organic electroluminescence device was produced in the same manner as in Example 1 except that the compound C represented by the above structural formula was replaced by the compound F represented by the following structural formula as the cathode-side adjacent layer.

(Comparative Example 3)

-Production of organic electroluminescent elements -

In Example 1, an organic electroluminescence device was produced in the same manner as in Example 1 except that the cathode side adjacent layer was not provided and BAlq was replaced with BCP+Li.

Then, the triplet energy of the luminescent material, the cathode side adjacent layer, and the electron transport layer of the produced Examples 1 to 5 and Comparative Examples 1 to 3 was measured as follows. The results are shown in Table 1.

<Measurement of triplet energy>

The triplet energy is obtained by using a spectrofluorometer F7000 manufactured by Hitachi, Ltd., and the luminescence lifetime is longer than that of fluorescence, and is obtained from a photoluminescence (PL) spectrum after shielding excitation light.

Next, with respect to the produced Examples 1 to 5 and Comparative Examples 1 to 3, external quantum efficiency, driving voltage, and driving durability (brightness half-life) were measured as follows. The results are shown in Table 2.

<Measurement of External Quantum Efficiency>

A source of power measurement unit 2400 manufactured by KEITHLEY Co., Ltd. was used, and a direct current having a current density of 25 mA/cm ^{2 was} passed to each element to emit light. The luminance and luminescence spectrum of the spectrometer SR-3 manufactured by Topcon Corporation were measured. Based on these measurement results, the external quantum efficiency was calculated by the luminescence spectral conversion algorithm.

<drive voltage>

The driving voltage at the time when the DC current was energized was measured using a power measuring unit Model 2400 manufactured by KEITHLEY.

<Drive durability (brightness half-life)>

The driving durability was constant current driving at an initial luminance of 2,000 cd/m ² , and the luminance half-life of Comparative Example 1 and Comparative Example 3 was set to 100, and the same phosphorescent luminescent material was used for the luminescent layer. The luminance half-life of the organic electroluminescent element.

From the results of Tables 1 and 2, it is found that Examples 1 to 5 can achieve higher luminous efficiency and drive durability than Comparative Examples 1 to 3.

Here, in Examples 1 to 5 and Comparative Examples 1 to 3, the compound B (phosphorescent blue light-emitting material, triplet energy: 63 kcal/mol) represented by the above structural formula was used for the light-emitting layer. When the compound G (phosphorescent green light-emitting material, triplet energy: 58 kcal/mol) represented by the following structural formula is used in the light-emitting layer instead of the phosphorescent blue light-emitting material, the light-emitting material and the cathode side are adjacent to each other. The triplet energy of the layer and the electron transport layer also has the same size relationship. Therefore, it is shown that even when the compound G (phosphorescent green light-emitting material) represented by the following structural formula is used, although the light-emitting wavelength of the light-emitting material is shorter in green and the triplet energy itself becomes smaller, the Pt complex is the same. The same effect can be obtained by the cathode side adjacent layer.

[Industrial availability]

The organic electroluminescence device of the present invention can achieve high luminous efficiency and improved driving durability, and thus can be suitably used, for example, for display elements, displays, backlights, electronic photographs, illumination sources, recording light sources, exposure light sources, and reading. Light source, logo, billboard, interior trim, optical communication, etc.

While the present invention has been described in its preferred embodiments, the present invention is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

1. . . Substrate

2. . . anode

3. . . Hole injection layer

4. . . Hole transport layer

5. . . Electronic barrier

6. . . Luminous layer

7. . . Cathode side adjacent layer (hole blocking layer)

8. . . Electronic transport layer

9. . . Electron injection layer

10. . . cathode

11. . . Organic electroluminescent element

T1. . . Triplet energy

1A is a view showing a relationship between triplet energy of a light-emitting layer and a cathode-side adjacent layer, and shows a state in which a triplet energy of a cathode-side adjacent layer is smaller than a triplet energy of a light-emitting layer of a light-emitting layer.

1B is a view showing a relationship between the triplet energy of the light-emitting layer and the cathode-side adjacent layer, and shows a state in which the triplet energy of the light-emitting layer of the light-emitting layer is equal to or higher than the triplet energy of the cathode-side adjacent layer.

2 is a schematic view showing an example of a layer configuration of an organic electroluminescence device of the present invention.

1. . . Substrate

2. . . anode

3. . . Hole injection layer

4. . . Hole transport layer

5. . . Electronic barrier

6. . . Luminous layer

7. . . Cathode side adjacent layer (hole blocking layer)

8. . . Electronic transport layer

9. . . Electron injection layer

10. . . cathode

11. . . Organic electroluminescent element

Claims (4)

An organic electroluminescence device having an organic layer having at least one light-emitting layer and a cathode-side adjacent layer adjacent to a cathode side of the light-emitting layer between an anode and a cathode, and a triplet state of the cathode-side adjacent layer a triplet energy having a lower energy than the luminescent material of the light-emitting layer; wherein the cathode-side adjacent layer contains a compound having an anthracene derivative skeleton represented by the following formula (II), and having a structure represented by the following formula (I) At least one of a compound of a hydrazine derivative skeleton, In the above formula (I), Ar ¹ and Ar ² are each independently a group derived from a substituted or unsubstituted aromatic ring having 6 to 20 carbon atoms; the aromatic ring may be passed through 1 or Substituted with two or more substituents; the above substituents are selected from substituted or unsubstituted aryl groups having 6 to 50 carbon atoms, substituted or unsubstituted alkyl groups having 1 to 50 carbon atoms, substituted or Unsubstituted cycloalkyl group having 3 to 50 carbon atoms, substituted or unsubstituted alkoxy group having 1 to 50 carbon atoms, substituted or unsubstituted aralkyl group having 6 to 50 carbon atoms, Substituted or unsubstituted aryloxy group having 5 to 50 nuclear atoms, substituted or unsubstituted arylthio group having 5 to 50 nuclear atoms, substituted or unsubstituted alkoxy having 1 to 50 carbon atoms a carbonyl group, a substituted or unsubstituted decyl group, a carboxyl group, a halogen atom, a cyano group, a nitro group and a hydroxyl group; when the aromatic ring is substituted with two or more substituents, the substituents may be the same or different. adjacent substituents may be bonded to each other to each other to form a saturated or unsaturated cyclic structure; R ¹ ~ R ⁸ is a hydrogen atom, a substituted or unsubstituted 6 to 50 nuclear carbon atoms of a substituted or unsubstituted heteroaryl group having 5 to 50 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted ring having 3 to 50 carbon atoms Alkyl, substituted or unsubstituted alkoxy group having 1 to 50 carbon atoms, substituted or unsubstituted aralkyl group having 6 to 50 carbon atoms, substituted or unsubstituted nuclear atom number 5 to 50 An aryloxy group, a substituted or unsubstituted arylthio group having 5 to 50 nucleus groups, a substituted or unsubstituted alkoxycarbonyl group having 1 to 50 carbon atoms, a substituted or unsubstituted decyl group a carboxyl group, a halogen atom, a cyano group, a nitro group and a hydroxyl group; in addition, adjacent substituents may be bonded to each other to form a saturated or unsaturated cyclic structure; Wherein, in the above formula (II), Ar ^1a and Ar ^2a each represent a substituted or unsubstituted aromatic ring group having a core number of 6 to 50; and L is a substituted or unsubstituted phenyl group, respectively. Substituted or unsubstituted anthranyl group, substituted or unsubstituted hydrazine group or substituted or unsubstituted dibenzosilolylene group; m is 0-2 Integer, nb is an integer from 1 to 4, s is an integer from 0 to 2, and t is an integer from 0 to 4. In addition, L or Ar ^{1a is} bonded to any of the 1 to 5 positions of 芘, L or Ar ^2a Bonding to any of 6 to 10 positions of 芘; wherein, when nb+t is an even number, Ar ^1a , Ar ^2a , L satisfy the following (1) or (2): (1) Ar ^1a ≠Ar ^2a (here, ≠ denotes a base of a different structure) (2) When Ar ^1a = Ar ^2a (2-1) m≠s and/or nb≠t, or (2-2) m=s and nb=t, ( 2-2-1) L or 芘 respectively bond different bonding positions on Ar ^1a and Ar ^2a , or (2-2-2) at the same bonding position where L or ytterbium is bonded to Ar ^1a and Ar ^2a In the case where the substitution positions of L or Ar ^1a and Ar ^2a on the oxime are 1 position and 6 positions, or 2 positions and 7 positions, it does not exist. The organic electroluminescent device according to claim 1, wherein the organic layer further comprises an electron transport layer adjacent to a cathode side of the cathode side adjacent layer, and a triplet energy of the cathode side adjacent layer is smaller than the electron The triplet energy of the transport layer. The organic electroluminescence device according to claim 1, wherein the cathode side adjacent layer contains a fused aromatic ring compound. The organic electroluminescence device according to claim 1, wherein the cathode side adjacent layer has a thickness of 1 nm to 10 nm.