JP5817469B2 - Organic electroluminescence device - Google Patents

Description

  The present invention relates to an organic electroluminescence element.

  An organic electroluminescence element (hereinafter also referred to as an organic EL element) has a structure in which a light emitting layer containing a light emitting compound is sandwiched between a cathode and an anode, and by applying an electric field, holes injected from the anode and It is a light-emitting device that uses excitons (excitons) by recombining electrons injected from the cathode in the light-emitting layer and emits light (fluorescence / phosphorescence) when the excitons are deactivated. . An organic EL element is an all-solid-state element composed of an organic material film having a thickness of only a submicron between electrodes, and can emit light at a voltage of several volts to several tens of volts. Therefore, it is expected to be used for next-generation flat display and lighting.

  As for development of organic EL elements for practical use, Princeton University has reported organic EL elements that use phosphorescence emission from excited triplets (see, for example, Non-Patent Document 1), and since then phosphorescence at room temperature. Research on materials exhibiting the above has become active (see, for example, Patent Document 1 and Non-Patent Document 2).

  In addition, recently discovered organic EL devices that use phosphorescence can realize a luminous efficiency that is approximately four times that of previous devices that use fluorescence. Research and development of light-emitting element layer configurations and electrodes are performed all over the world. For example, many synthetic compounds have been studied focusing on heavy metal complexes such as iridium complexes (see Non-Patent Document 3, for example).

  As described above, the phosphorescence emission method is a method having a very high potential. However, an organic EL device using phosphorescence emission is greatly different from an organic EL device using fluorescence emission, and controls the position of the emission center. The method, particularly how to recombine within the light emitting layer and how to stably emit light, is an important technical issue in capturing the efficiency and lifetime of the device.

  Therefore, in recent years, a multi-layered element having a hole transport layer located on the anode side of the light emitting layer and an electron transport layer located on the cathode side of the light emitting layer in a form adjacent to the light emitting layer is well known. (For example, refer to Patent Document 2). In addition, a mixed layer using a phosphorescent compound as a dopant with respect to the host compound is often used for the light emitting layer.

  In addition, from the viewpoint of use in displays and illumination, organic EL elements also need chromaticity stability with respect to environmental temperature, such as when they emit light continuously for a long time, or under high temperature and high humidity. In particular, in the illumination light source application, there is a strict requirement for the stability of the emission color, and in order to put the organic electroluminescence element into practical use for the illumination light source, it is an important issue how to ensure the chromaticity stability. Yes.

  In recent years, Patent Documents 3 and 4 disclose metal complexes having specific ligands as blue phosphorescent compounds having high potential. Further, Patent Document 3 proposes a dibenzofuran or dibenzothiophene derivative as a host compound used with a blue phosphorescent compound. In Patent Document 4, a more general hole transport layer and electron transport material are combined. However, organic EL devices obtained using the metal complexes described in Patent Documents 3 and 4 are not yet sufficient in terms of luminous efficiency, lifetime, and chromaticity stability.

  For example, in Patent Document 5, a hole transport layer is laminated, and a carbazole derivative / dibenzofuran derivative / dibenzothiophene derivative / fluorene derivative of triphenylamine is used for the hole transport layer on the side close to the light-emitting layer. Techniques for providing efficient devices are disclosed.

  Patent Document 6 discloses a method for providing a highly efficient and long-life device by suppressing the amount of holes injected into the light emitting layer by defining the structure, mobility and HOMO level of the hole injection layer. Has been.

US Pat. No. 6,097,147 JP 2005-112765 A International Publication No. 2006/114966 US Patent Application Publication No. 2011/0057559 International Publication No. 2009/041635 JP 2005-291487 A

M.M. A. Baldo et al. , Nature, 395, 151-154 (1998) M.M. A. Baldo et al. , Nature, 403, 17, 750-753 (2000) S. Lamansky et al. , J .; Am. Chem. Soc. 123, 4304 (2001)

  However, the organic EL device fabricated based on the above-described conventional technology has performance in each characteristic such as luminous efficiency, luminous lifetime, driving voltage, voltage increase, high temperature storage property, and robustness (leakage occurrence frequency, dark spot occurrence frequency). Is insufficient, and white light-emitting elements are not sufficiently studied.

  An object of the present invention is to provide an organic electroluminescence device that has high luminous efficiency, long life, and low driving voltage, and suppresses voltage increase due to continuous driving.

In order to achieve the above object of the present invention, according to one aspect of the present invention,
An organic layer having a multi-layer structure is provided between the anode and the cathode. In the organic layer, a hole injection layer, a first hole transport layer, a second hole transport layer, a host compound are formed from the anode to the cathode. A light emitting layer containing a phosphorescent dopant compound is an organic electroluminescence device in which each layer is laminated in this order,
The phosphorescent dopant compound is represented by the following general formula (1-1),
The host compound is represented by the following general formula (1) ′,
The second hole transport material used for the second hole transport layer is represented by the following general formula (2):
The highest occupied molecular orbital HOMO (HT2) of the second hole transport material satisfies −5.03 eV ≦ HOMO (HT2) ≦ −4.96 eV,
The relationship between the excited triplet energy T1 (D) of the phosphorescent dopant compound and the excited triplet energy T1 (HT2) of the second hole transport material is T1 (HT2) -T1 (D). An organic electroluminescent device characterized by satisfying ≧ 0.27 eV is provided.

  In General Formula (1-1), Ar represents an aromatic hydrocarbon ring, an aromatic heterocyclic ring, a non-aromatic hydrocarbon ring, or a non-aromatic heterocyclic ring. R ₁ And R ₂ Are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group, heteroaryl group, non-aromatic hydrocarbon ring group Or a non-aromatic heterocyclic group, which may further have a substituent, R ₁ And R ₂ At least one of them is an alkyl group or cycloalkyl group having 2 or more carbon atoms.
  Ra, Rb and Rc are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group, heteroaryl group, non-aromatic Represents a hydrocarbon ring group or a non-aromatic heterocyclic group, and may further have a substituent. na and nc represent 1 or 2, and nb represents an integer of 1 to 4.
  L ′ is one or more of monoanionic bidentate ligands coordinated to M, M represents a transition metal atom of atomic number 40 or more and group 8 to 10 in the periodic table, m 'Represents an integer of 0 to 2, n' is at least 1, and m '+ n' is 2 or 3.

一般式（２）中、Ｘ及びＹはＯ、Ｓ又はＮ−Ｒ（Ｒは水素原子又は置換基を表す）を表し、Ａ１及びＡ２は水素原子又は置換基を表す。Ｌ _１ 及びＬ _２ は２価の連結基を表し、ｎは１以上の整数を表し、ｎ１及びｎ２は０以上の整数を表し、ｎ３及びｎ４は０又は１を表す。但し、ｎ１＋ｎ２≧２である。 In general formula (1) ′, X represents O or S. L is a single bond (L may not be present) or a divalent linking group and represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring. Ar ₁ represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring.

In General Formula (2), X and Y represent O, S, or N—R (R represents a hydrogen atom or a substituent), and A1 and A2 represent a hydrogen atom or a substituent. L ₁ and L ₂ represent a divalent linking group, n represents an integer of 1 or more, n1 and n2 represent an integer of 0 or more, and n3 and n4 represent 0 or 1. However, n1 + n2 ≧ 2.

  According to the present invention, it is possible to provide an organic electroluminescence device that has high luminous efficiency, long life, and low driving voltage, and suppresses voltage increase due to continuous driving.

It is the schematic diagram which showed an example of the display apparatus comprised from an organic EL element. It is a schematic diagram of the display part of the display apparatus of FIG. It is a schematic diagram of the pixel of the display apparatus of FIG. It is a schematic diagram of a passive matrix type full-color display device. It is the schematic of an illuminating device. It is a schematic diagram of an illuminating device.

  Hereinafter, although the form for implementing this invention is demonstrated in detail, this invention is not limited to these.

<< Constituent layers of organic EL elements >>
The constituent layers of the organic EL element of the present invention will be described. In this invention, although the preferable specific example of the layer structure of an organic EL element is shown below, this invention is not limited to these.

(I) Anode / light emitting layer / electron transport layer / cathode (ii) Anode / hole transport layer / light emitting layer / electron transport layer / cathode (iii) Anode / hole transport layer / light emitting layer / hole blocking layer / electron Transport layer / cathode (iv) Anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode (v) Anode / anode buffer layer / hole transport layer / light emitting layer / hole Blocking layer / electron transport layer / cathode buffer layer / cathode (vi) anode // hole transport layer / anode buffer layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode (vii) anode / anode Buffer layer / hole transport layer / light emitting layer / electron transport layer / cathode buffer layer / cathode

  When a plurality of light emitting layers are included, a non-light emitting intermediate layer may be provided between the light emitting layers. In addition, among the above layer structures, an organic layer including a light emitting layer excluding an anode and a cathode can be used as one light emitting unit, and a plurality of light emitting units can be stacked. The plurality of stacked light emitting units may have a non-light emitting intermediate layer between the light emitting units, and the intermediate layer may further include a charge generation layer.

  The organic EL element of the present invention is preferably a white light emitting layer, and is preferably a lighting device using these.

In the present invention, for the purpose of the present invention described above, a compound having a partial structure represented by the general formula (1) capable of obtaining high efficiency and long life is used as the phosphorescent dopant compound in the light emitting layer, and The compound represented by the general formula (1) ′ is used as a host compound in the light emitting layer, and further, a plurality of hole transport layers are used, and the second hole transport layer used adjacent to the light emitting layer is used. By using a material having a specific level as the two-hole transport material, the organic EL device can be further improved in efficiency, life and drive voltage. This is because the recombination probability is low because the hole trapping property of the compound having the partial structure represented by the general formula (1) is strong, and the emission efficiency is lowered and electrons flow into the hole transport layer. As a result, it is estimated that the lifetime is shortened. Therefore, in the present invention, by providing the second hole transport layer and controlling the HOMO value, the hole trapping property is relaxed and the light emitting region is widened, leading to higher efficiency and longer life. Conceivable.
Note that the HOMO and LUMO values and the excited triplet energy T1 of each material constituting the organic EL element are obtained as follows.

[HOMO and LUMO energy levels]
Using Gaussian 03 (Gaussian 03, Revision D02, MJ Frisch, et al, Gaussian, Inc., Wallingford CT, 2004.), a molecular orbital calculation software manufactured by Gaussian, USA. The electron transport material uses B3LYP / 6-31G * as a keyword, and the phosphorescent dopant compound uses B3LYP / LanL2DZ to calculate the LUMO by optimizing the structure of the target molecular structure (eV unit conversion) value). It is known that the correlation between the calculated value obtained by this method and the experimental value is high as a background to the effectiveness of this calculated value.

[Excitation triplet energy T1]
For the structure optimized when calculating the LUMO energy level, the TDDFT calculation is performed by performing TDDFT calculation using the functional and basis function conditions applied to the host compound and the dopant compound. The value was determined. The same applies to the hole transport material and the electron transport material.

  Hereinafter, each layer which comprises the organic EL element of this invention is demonstrated.

<Light emitting layer>
The light emitting layer according to the present invention is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer, and the light emitting portion is in the layer of the light emitting layer. May be the interface between the light emitting layer and the adjacent layer.

  The total film thickness of the light emitting layer is not particularly limited, but from the viewpoint of improving the uniformity of the film, preventing unnecessary application of high voltage during light emission, and improving the stability of the emission color with respect to the drive current. It is preferably adjusted to a range of 2 nm to 5 μm, more preferably adjusted to a range of 2 nm to 200 nm, and particularly preferably adjusted to a range of 5 nm to 100 nm.

  For the production of the light emitting layer, a light emitting dopant or host compound described later is used, for example, a vacuum deposition method, a wet method (also referred to as a wet process, for example, a spin coating method, a casting method, a die coating method, a blade coating method, a roll coating method, An ink-jet method, a printing method, a spray coating method, a curtain coating method, an LB method (a Langmuir-Blodgett method and the like can be used)) and the like can be formed.

  The light emitting layer of the organic EL device of the present invention contains a light emitting dopant (phosphorescent dopant (also referred to as phosphorescent dopant, also referred to as phosphorescent dopant group) or fluorescent dopant) compound and a host compound, and at least One luminescent dopant is a blue phosphorescent organometallic complex represented by general formula (1) described later, and the host compound is a compound represented by general formula (1) ′ described later.

(1) Luminescent dopant compound A luminescent dopant compound (also referred to as a luminescent dopant) will be described.
As the light-emitting dopant, a fluorescent dopant (also referred to as a fluorescent compound) or a phosphorescent dopant (also referred to as a phosphorescent dopant compound, a phosphorescent emitter, a phosphorescent compound, a phosphorescent compound, or the like) is used. it can.

(1.1) Phosphorescent dopant (also called phosphorescent dopant compound)
The phosphorescent dopant according to the present invention will be described.
The phosphorescent dopant compound according to the present invention is a compound in which light emission from an excited triplet is observed, specifically, a compound that emits phosphorescence at room temperature (25 ° C.), and has a phosphorescence quantum yield of 25. Although it is defined as a compound of 0.01 or more at ° C., a preferable phosphorescence quantum yield is 0.1 or more.

  The phosphorescence quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of Experimental Chemistry Course 4 of the 4th edition. Although the phosphorescence quantum yield in a solution can be measured using various solvents, the phosphorescence dopant according to the present invention achieves the phosphorescence quantum yield (0.01 or more) in any solvent. That's fine.

  There are two types of emission principles of the phosphorescent dopant. One is that recombination of carriers occurs on the host compound to which carriers are transported to generate an excited state of the luminescent host compound, and this energy is transferred to the phosphorescent dopant to obtain light emission from the phosphorescent dopant. Energy transfer type. The other is a carrier trap type in which a phosphorescent dopant serves as a carrier trap, carrier recombination occurs on the phosphorescent dopant, and light emission from the phosphorescent dopant compound is obtained. In any case, it is a condition that the excited state energy of the phosphorescent dopant is lower than the excited state energy of the host compound.

(1.1.1) A phosphorescent dopant compound having a partial structure represented by the general formula (1) In the present invention, a phosphorescent dopant compound having a partial structure represented by the following general formula (1) Is used.

In general formula (1), ring A and ring B represent a 5-membered or 6-membered aromatic hydrocarbon ring or aromatic heterocycle.
In the general formula (1), examples of the 5-membered or 6-membered aromatic hydrocarbon ring represented by the ring A and the ring B include a benzene ring.
In the general formula (1), examples of the 5-membered or 6-membered aromatic heterocycle represented by the ring A and the ring B include a furan ring, a thiophene ring, an oxazole ring, a pyrrole ring, a pyridine ring, a pyridazine ring, and a pyrimidine. A ring, a pyrazine ring, a triazine ring, an oxadiazole ring, a triazole ring, an imidazole ring, a pyrazole ring, a thiazole ring, and the like.
Preferably ring B is a benzene ring, more preferably ring A is a benzene ring.

In the general formula (1), Ar represents an aromatic hydrocarbon ring, an aromatic heterocyclic ring, a non-aromatic hydrocarbon ring or a non-aromatic heterocyclic ring.
In the general formula (1), examples of the aromatic hydrocarbon ring represented by Ar include a benzene ring, biphenyl ring, naphthalene ring, azulene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, naphthacene ring, and triphenylene. Ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring, naphthacene ring, pentacene ring, perylene ring, pentaphen ring, picene ring, pyrene Ring, pyranthrene ring, anthraanthrene ring and the like.
In the general formula (1), examples of the aromatic heterocycle represented by Ar include a silole ring, a furan ring, a thiophene ring, an oxazole ring, a pyrrole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, and a triazine ring. Oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, benzimidazole ring, benzthiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, thienothiophene ring, carbazole ring, aza A carbazole ring (representing any one or more of the carbon atoms constituting the carbazole ring replaced by a nitrogen atom), a dibenzosilole ring, a dibenzofuran ring, a dibenzothiophene ring, a benzothiophene ring or a dibenzofuran ring. Any one Ring substituted with nitrogen atom, benzodifuran ring, benzodithiophene ring, acridine ring, benzoquinoline ring, phenazine ring, phenanthridine ring, phenanthroline ring, cyclazine ring, quindrine ring, tepenidine ring, quinindrin ring, triphenodithia Gin ring, triphenodioxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, naphthofuran ring, naphthothiophene ring, naphthodifuran ring, naphthodithiophene ring, anthrafuran ring, anthradifuran ring, anthrathiophene ring, anthradithiophene Ring, thianthrene ring, phenoxathiin ring, dibenzocarbazole ring, indolocarbazole ring, dithienobenzene ring and the like.
In the general formula (1), examples of the non-aromatic hydrocarbon ring represented by Ar include cycloalkane (eg, cyclopentane ring, cyclohexane ring, etc.), cycloalkoxy group (eg, cyclopentyloxy group, cyclohexyloxy group). Etc.), a cycloalkylthio group (for example, a cyclopentylthio group, a cyclohexylthio group, etc.), a cyclohexylaminosulfonyl group, a tetrahydronaphthalene ring, a 9,10-dihydroanthracene ring, a biphenylene ring and the like.
In the general formula (1), examples of the non-aromatic heterocycle represented by Ar include an epoxy ring, an aziridine ring, a thiirane ring, an oxetane ring, an azetidine ring, a thietane ring, a tetrahydrofuran ring, a dioxolane ring, a pyrrolidine ring, and a pyrazolidine. Ring, imidazolidine ring, oxazolidine ring, tetrahydrothiophene ring, sulfolane ring, thiazolidine ring, ε-caprolactone ring, ε-caprolactam ring, piperidine ring, hexahydropyridazine ring, hexahydropyrimidine ring, piperazine ring, morpholine ring, tetrahydropyran Ring, 1,3-dioxane ring, 1,4-dioxane ring, trioxane ring, tetrahydrothiopyran ring, thiomorpholine ring, thiomorpholine-1,1-dioxide ring, pyranose ring, diazabicyclo [2,2,2]- Octane ring, Fe Examples thereof include a noxazine ring, a phenothiazine ring, an oxanthrene ring, a thioxanthene ring, and a phenoxathiin ring.

These rings represented by Ar in the general formula (1) may further have the following substituents, and the substituents may be bonded to each other to form a ring.
Examples of the substituent that the ring represented by Ar in the general formula (1) may have include an alkyl group (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a tert-butyl group, a pentyl group, Hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), alkenyl group (eg, vinyl group, allyl group, etc.), alkynyl group (eg, ethynyl group, propargyl group, etc.), non-aromatic carbonization Hydrogen ring group (for example, cycloalkyl group (for example, cyclopentyl group, cyclohexyl group, etc.), cycloalkoxy group (for example, cyclopentyloxy group, cyclohexyloxy group, etc.), cycloalkylthio group (for example, cyclopentylthio group, cyclohexylthio group, etc.) ), Tetrahydronaphthalene ring, 9,10-dihydroant Monovalent groups derived from sen rings, biphenylene rings, etc.), non-aromatic heterocyclic groups (eg, epoxy rings, aziridine rings, thiirane rings, oxetane rings, azetidine rings, thietane rings, tetrahydrofuran rings, dioxolane rings, pyrrolidines) Ring, pyrazolidine ring, imidazolidine ring, oxazolidine ring, tetrahydrothiophene ring, sulfolane ring, thiazolidine ring, ε-caprolactone ring, ε-caprolactam ring, piperidine ring, hexahydropyridazine ring, hexahydropyrimidine ring, piperazine ring, morpholine ring , Tetrahydropyran ring, 1,3-dioxane ring, 1,4-dioxane ring, trioxane ring, tetrahydrothiopyran ring, thiomorpholine ring, thiomorpholine-1,1-dioxide ring, pyranose ring, diazabicyclo [2,2, 2] -Octa Ring, phenoxazine ring, phenothiazine ring, oxanthrene ring, thioxanthene ring, monovalent group derived from phenoxathiin ring, etc.), aromatic hydrocarbon group (eg benzene ring, biphenyl ring, naphthalene ring, azulene ring) , Anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, naphthacene ring, triphenylene ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring , Naphthacene ring, pentacene ring, perylene ring, pentaphen ring, picene ring, pyrene ring, pyranthrene ring, monovalent group derived from anthraanthrene ring, etc.), aromatic heterocyclic group (for example, silole ring, furan ring) Thiophene ring, oxazole ring, pyrrole ring, pyridine ring, pyridazine ring, Limidine ring, pyrazine ring, triazine ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, benzimidazole ring, benzthiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, Thienothiophene ring, carbazole ring, azacarbazole ring (representing any one or more of the carbon atoms constituting the carbazole ring replaced by a nitrogen atom), dibenzosilole ring, dibenzofuran ring, dibenzothiophene ring, benzothiophene ring, A ring in which any one or more of the carbon atoms constituting the dibenzofuran ring are replaced by a nitrogen atom, a benzodifuran ring, a benzodithiophene ring, an acridine ring, a benzoquinoline ring, a phenazine ring, a phenanthridine ring, a phenanthroline ring, Cyclazine ring, kindrin ring, tepenidine ring, quinindrin ring, triphenodithiazine ring, triphenodioxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, naphthofuran ring, naphthothiophene ring, naphthodifuran ring, naphthodithiophene ring, anthra Monovalent group derived from furan ring, anthradifuran ring, anthrathiophene ring, anthradithiophene ring, thianthrene ring, phenoxathiin ring, dibenzocarbazole ring, indolocarbazole ring, dithienobenzene ring), alkoxy Group (for example, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), aryloxy group (for example, phenoxy group, naphthyloxy group, etc.), alkylthio group For example, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.), arylthio group (eg, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyl) Oxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group, methyl) Aminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, Silylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group) 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecyl) Carbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, Propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, Aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group Naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylurei group) Group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group) , Cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexyl) Sulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group or heteroarylsulfonyl group (for example, phenoxy group) Rusulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, Anilino group, naphthylamino group, 2-pyridylamino group, etc.), halogen atom (for example, fluorine atom, chlorine atom, bromine atom, fluorinated hydrocarbon group (for example, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, Pentafluorophenyl group, etc.), cyano group, nitro group, hydroxy group, mercapto group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, etc.), phosphono group, etc. .

  Ar in the general formula (1) is preferably an aromatic hydrocarbon ring or an aromatic heterocyclic ring, more preferably an aromatic hydrocarbon ring, and further preferably a benzene ring.

In the general formula (1), R ₁ and R ₂ are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl Represents a group, heteroaryl group, non-aromatic hydrocarbon ring group or non-aromatic heterocyclic group, and may further have a substituent, and at least one of R ₁ and R ₂ is alkyl having 2 or more carbon atoms Group or a cycloalkyl group.
In the general formula (1), the aryl group and heteroaryl group represented by R ₁ and R ₂ are derived from the aromatic hydrocarbon ring and aromatic heterocycle represented by Ar in the general formula (1). And a monovalent group.
In the general formula (1), the non-aromatic hydrocarbon ring group and the non-aromatic heterocyclic group represented by R ₁ and R ₂ are the non-aromatic carbon groups represented by Ar in the general formula (1). And monovalent groups derived from a hydrogen ring and a non-aromatic heterocyclic ring.
Preferably, both R ₁ and R ₂ are an alkyl group or a cycloalkyl group having 2 or more carbon atoms. Preferably, at least one of R ₁ and R ₂ is a branched alkyl group having 3 or more carbon atoms. More preferably, R ₁ and R ₂ are both branched alkyl groups having 3 or more carbon atoms.

In the general formula (1), Ra, Rb and Rc are each independently a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group, a silyl group, an arylalkyl group, an aryl group. Represents a heteroaryl group, a non-aromatic hydrocarbon ring group or a non-aromatic heterocyclic group, and may further have a substituent.
In the general formula (1), the aryl group and heteroaryl group represented by Ra, Rb and Rc are derived from the aromatic hydrocarbon ring and aromatic heterocycle represented by Ar in the general formula (1). And a monovalent group.
In the general formula (1), as the non-aromatic hydrocarbon ring group and non-aromatic heterocyclic group represented by Ra, Rb and Rc, the non-aromatic carbon represented by Ar in the above-mentioned general formula (1) And monovalent groups derived from a hydrogen ring and a non-aromatic heterocyclic ring.

  In General formula (1), na and nc represent 1 or 2, and nb represents the integer of 1-4.

(1.1.2) Phosphorescent dopant compound represented by general formula (1-1) The phosphorescent dopant compound having a partial structure represented by general formula (1) according to the present invention is described below. It is preferable to be represented by the general formula (1-1).

In the general formula (1-1), Ar, R ₁ , R ₂ , Ra, Rb, Rc, na, nb and nc are Ar, R ₁ , R ₂ , Ra, Rb, Rc in the general formula (1). , Na, nb and nc.

In the general formula (1-1), L ′ is one or more of monoanionic bidentate ligands coordinated to M.
In the general formula (1-1), specific examples of the monoanionic bidentate ligand coordinated to M represented by L ′ include a ligand of the following formula.

  In the above formula, Rd ′, Rd ″, and Rd ′ ″ represent a hydrogen atom or a substituent, and the substituents represented by Rd ′, Rd ″, and Rd ′ ″ include those in the above general formula (1). The thing similar to the ring represented by Ar is mentioned.

In General Formula (1-1), M represents a transition metal atom having an atomic number of 40 or more and a group 8 to 10 in the periodic table.
M in the general formula (1-1) is preferably Os, Ir or Pt, more preferably Ir.

In the general formula (1-1), m ′ represents an integer of 0 to 2, n ′ is at least 1, and m ′ + n ′ is 2 or 3.
Preferably, n ′ is 3 or 2, and m ′ is 0.

(1.1.3) Specific Example A phosphorescent dopant compound having a partial structure represented by the general formula (1) according to the present invention or a phosphorescent dopant compound represented by (1-1), It can be synthesized by referring to a known method described in International Publication No. 2006-121811, etc.

  Specific examples of the phosphorescent dopant compound that can be preferably used in the present invention will be given below, but the present invention is not limited thereto.

The phosphorescent dopant according to the present invention is a compound having the partial structure represented by the general formula (1) described above, but compounds described in the following patent publications may be used in combination.
For example, International Publication No. 00/70655, JP 2002-280178, JP 2001-181616, JP 2002-280179, JP 2001-181617, JP 2002-280180, JP 2001-247859 A, JP 2002-299060 A, JP 2001-313178 A, JP 2002-302671 A, JP 2001-345183 A, JP 2002-324679 A, International Publication. No. 02/15645, JP 2002-332291 A, JP 2002-50484 A, JP 2002-332292 A, JP 2002-83684 A, JP 2002-540572 A, JP 2002-2002 A. No. 117978, Japanese Patent Application Laid-Open No. 2002-33858 JP, JP-A-2002-170684, JP-A-2002-352960, WO01 / 93642, JP-A-2002-50483, JP-A-2002-1000047, JP-A-2002-173684. JP-A-2002-359082, JP-A-2002-175484, JP-A-2002-363552, JP-A-2002-184582, JP-A-2003-7469, JP-A-2002-525808, JP 2003-7471, JP 2002-525833, JP 2003-31366, JP 2002-226495, JP 2002-234894, JP 2002-2335076, JP 2002 No. 2411751, JP 2001-319779 A. JP, 2001-319780, 2002-62824, 2002-100474, 2002-203679, 2002-343572, 2002-203678, etc. It is.

(1.2) Fluorescent dopant (also called fluorescent compound)
As fluorescent dopants, coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, perylene dyes, stilbene dyes , Polythiophene dyes, rare earth complex phosphors, and the like, and compounds having a high fluorescence quantum yield such as laser dyes.

(1.3) Combined use with conventionally known light-emitting dopant compounds The light-emitting dopant according to the present invention may be used in combination with a plurality of types of compounds, and combinations of phosphorescent dopants having different structures or phosphorescent dopants. And a fluorescent dopant may be used in combination.
Specific examples of known phosphorescent dopant compounds that can be preferably used in the present invention are given below. Of course, the present invention is not limited to these.

(2) Luminescent host compound (also referred to as luminescent host)
In the present invention, the host compound has a mass ratio of 20% or more among the compounds contained in the light emitting layer, and a phosphorescence quantum yield of phosphorescence emission is 0 at room temperature (25 ° C.). Defined as less than 1 compound. The phosphorescence quantum yield is preferably less than 0.01. Moreover, it is preferable that the mass ratio in the layer is 20% or more among the compounds contained in a light emitting layer.

(2.1) Host Compound Represented by General Formula (1) ′ In the present invention, a compound represented by the following general formula (1) ′ is used as the host compound.

  In the general formula (1) ′, X represents O or S.

In the general formula (1) ′, L is a single bond (L may be omitted) or a divalent linking group and represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring.
In the general formula (1) ′, examples of the aromatic hydrocarbon ring which is a divalent linking group represented by L include substituted and unsubstituted phenylene groups.
In the general formula (1) ′, the aromatic heterocyclic ring which is a divalent linking group represented by L includes an indole ring, a benzimidazole ring, a benzthiazole ring, a benzoxazole ring, a quinoxaline ring, a quinazoline ring, and a phthalazine ring. , Thienothiophene ring, aromatic heterocycle formed by condensation of three or more rings (here, the condensed aromatic heterocycle formed by condensation of three or more rings was selected from N, O and S) It is preferably an aromatic heterocondensed ring containing a hetero atom as an element constituting a condensed ring, specifically, a carbazole ring, an azacarbazole ring (any one or more of the carbon atoms constituting the carbazole ring are A dibenzosilole ring, dibenzofuran ring, dibenzothiophene ring, benzothiophene ring or dibenzofuran ring. Rings in which any one or more of carbon atoms are replaced by nitrogen atoms, benzodifuran ring, benzodithiophene ring, acridine ring, benzoquinoline ring, phenazine ring, phenanthridine ring, phenanthroline ring, cyclazine ring, kindrin ring, tepenidine Ring, quinindrin ring, triphenodithiazine ring, triphenodioxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, naphthofuran ring, naphththiophene ring, naphthodifuran ring, naphthodithiophene ring, anthrafuran ring, anthradifuran ring , Anthrathiophene ring, anthradithiophene ring, thianthrene ring, phenoxathiin ring, dibenzocarbazole ring, indolocarbazole ring, dithienobenzene ring, etc.). E down rings are preferred.

In General Formula (1) ′, Ar ₁ represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring.
In the general formula (1) ′, examples of the aromatic hydrocarbon ring or aromatic heterocycle represented by Ar ₁ include those similar to Ar in the general formula (1).

(2.2) Host compound represented by general formula (5) The host compound represented by general formula (1) ′ according to the present invention is preferably represented by the following general formula (5).

In the general formula (5), X, L and Ar ₁ has the same meaning as X, L and Ar ₁ in the general formula (1) '.

(2.3) Host compounds represented by general formulas (6) to (9) The host compounds represented by general formula (1) ′ according to the present invention are represented by the following general formulas (6) to (9). It is preferred that

In the general formula (6) ~ (9), X and Ar ₁ has the same meaning as X and Ar ₁ in the general formula (1) '.

(2.4) Host compound represented by general formula (10) or (11) The host compound represented by general formula (1) ′ according to the present invention is represented by the following general formula (10) or (11). It is preferred that

  In the general formulas (10) and (11), X and L have the same meanings as X and L in the general formula (1) ′.

  The host compound preferably has a higher Tg (glass transition temperature) from the viewpoint of stability over time and production suitability at the time of device fabrication. Preferably, the Tg of the compound is 100 ° C. or higher, more preferably 120 ° C. or higher. Yes, more preferably 130 ° C or higher.

  The host compound represented by the general formula (1) ′ or (5) to (11) preferably has the lowest excited triplet energy (T1) higher than the blue phosphorescent organometallic complex used at the same time. More preferably, T1 of the host compound is 2.7 eV or more, further preferably 2.75 eV or more, and particularly preferably 2.8 eV or more.

  Here, the value of T1 of the host compound represented by the general formula (1) ′ or (5) to (11) is Gaussian 98 (Gaussian 98, Revision A.11. 4, MJ Frisch, et al, Gaussian, Inc., Pittsburgh PA, 2002.), and the structure optimization is performed using B3LYP / 6-31G * as a keyword. Defined as (eV unit converted value). This calculation value is effective because the correlation between the calculation value obtained by this method and the experimental value is high.

  Further, the host compound represented by the general formula (1) ′ or (5) to (11) preferably has a molecular weight of 500 or more and 2000 or less, and more preferably 700 or more and 1500 or less.

(2.5) Specific Examples Hereinafter, specific examples of the host compound represented by the general formula (1) ′ or (5) to (11) according to the present invention will be shown, but the present invention is not limited thereto.

  As the host compound, a conventionally known compound may be used in combination with the compound represented by the general formula (1) ′ or (5) to (11) according to the present invention. The compound that may be used in combination typically has a basic skeleton such as a carbazole derivative, triarylamine derivative, aromatic derivative, nitrogen-containing heterocyclic compound, thiophene derivative, furan derivative, oligoarylene compound, or A carboline derivative or a diazacarbazole derivative (herein, a diazacarbazole derivative represents one in which at least one carbon atom of a hydrocarbon ring constituting the carboline ring of the carboline derivative is substituted with a nitrogen atom). Can be mentioned.

  As the known light-emitting host that can be used in the present invention, a compound that has a hole transporting ability and an electron transporting ability, prevents the emission of light from becoming longer, and has a high Tg (glass transition temperature) is preferable. More preferably, Tg is 100 ° C. or higher.

By using a plurality of types of light-emitting hosts, the movement of charges can be adjusted, and the organic EL element can be made highly efficient.
Moreover, it becomes possible to mix different light emission by using multiple types of well-known compounds used as the said phosphorescence dopant, and, thereby, arbitrary luminescent colors can be obtained.

  In addition, the light emitting host used in the present invention may be a low molecular compound, a high molecular compound having a repeating unit, or a low molecular compound having a polymerizable group such as a vinyl group or an epoxy group (polymerizable light emitting host). Of course, one or a plurality of such compounds may be used.

Specific examples of the known light-emitting host include compounds described in the following documents.
JP-A-2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579, 2002-105445 gazette, 2002-343568 gazette, 2002-141173 gazette, 2002-352957 gazette, 2002-203683 gazette, 2002-363227 gazette, 2002-231453 gazette, No. 003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-286061, No. 2002-280183, No. 2002-299060, No. 2002. -302516, 2002-305083, 2002-305084, 2002-308837, and the like.

<< Injection layer: hole injection layer (anode buffer layer), electron injection layer (cathode buffer layer) >>
The injection layer is provided as necessary, and there are an electron injection layer and a hole injection layer, and as described above, it exists between the anode and the light emitting layer or the hole transport layer and between the cathode and the light emitting layer or the electron transport layer. May be.

  An injection layer is a layer provided between an electrode and an organic layer in order to reduce drive voltage and improve light emission luminance. “Organic EL element and its forefront of industrialization (issued by NTT Corporation on November 30, 1998) 2), Chapter 2, “Electrode Materials” (pages 123 to 166), and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).

  The details of the anode buffer layer (hole injection layer) are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069 and the like. As a specific example, copper phthalocyanine is used. Representative phthalocyanine buffer layer, oxide buffer layer typified by vanadium oxide, amorphous carbon buffer layer, polymer buffer layer using conductive polymer such as polyaniline (emeraldine) or polythiophene, tris (2-phenylpyridine) ) Orthometalated complex layers represented by iridium complexes and the like.

The details of the cathode buffer layer (electron injection layer) are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, strontium, aluminum, etc. Metal buffer layer typified by, alkali metal compound buffer layer typified by lithium fluoride, sodium fluoride and potassium fluoride, alkaline earth metal compound buffer layer typified by magnesium fluoride, and aluminum oxide And an oxide buffer layer. The buffer layer (injection layer) is preferably a very thin film, and the film thickness is preferably in the range of 0.1 nm to 5 μm although it depends on the material.
In addition, the materials used for the anode buffer layer and the cathode buffer layer can be used in combination with other materials. For example, the materials can be mixed in the hole transport layer or the electron transport layer.

《Hole transport layer》
The hole transport layer is made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. In the present invention, a plurality of hole transport layers are provided. The hole transport layer close to the anode side is the first hole transport layer (HT1), and the hole transport layer adjacent to the light emitting layer is the second hole transport layer. Let it be a layer (HT2).

  The hole transport material has any one of hole injection or transport and electron barrier properties, and may be either organic or inorganic. For example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples thereof include stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers.

  The above-mentioned materials can be used as the hole transport material, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.

  Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ', N'-tetraphenyl-4,4'-diaminophenyl; N, N'-diphenyl-N, N'- Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N ' − (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) quadriphenyl; N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino- (2-diphenylvinyl) benzene; 3-methoxy-4′-N, N-diphenylaminostilbenzene; N-phenylcarbazole, and also two of those described in US Pat. No. 5,061,569. Having a condensed aromatic ring in the molecule, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-3086 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 8 are linked in a starburst type ( MTDATA) and the like.

  Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material.

  In addition, cyclometalated complexes and orthometalated complexes represented by copper phthalocyanine, tris (2-phenylpyridine) iridium complex, and the like can also be used as the hole transport material.

  JP-A-11-251067, J. Org. Huang et. al. A so-called p-type hole transport material as described in a book (Applied Physics Letters 80 (2002), p. 139) can also be used. In the present invention, these materials are preferably used because a light-emitting element with higher efficiency can be obtained.

The hole transport layer can be formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. it can.
Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5 nm-200 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.

Alternatively, a hole transport layer having a high p property doped with impurities can be used. Examples thereof include JP-A-4-297076, JP-A-2000-196140, 2001-102175, J. Pat. Appl. Phys. 95, 5773 (2004), and the like.
In the present invention, it is preferable to use a hole transport layer having such a high p property because a device with lower power consumption can be produced.

  Hereinafter, although the specific example of the compound preferably used for formation of the positive hole injection layer of the organic EL element of this invention and a positive hole transport layer is given, this invention is not limited to these.

  Moreover, in this invention, it is preferable to use the compound represented by General formula (2) as a 2nd hole transport material used for a 2nd hole transport layer.

In General formula (2), X and Y represent O, S, or NR (R represents a hydrogen atom or a substituent). Here, examples of the substituent represented by R include a substituted or unsubstituted alkyl group, an aryl group, and an aromatic heterocyclic group, and specific examples thereof are represented by A ₁ and A ₂ in the general formula (2) described later. It is mentioned as a substituent represented.

In the general formula (2), _{A 1} and _{A 2} represents a hydrogen atom or a substituent.
In the general formula (2), examples of the substituent represented by A ₁ and A ₂ include an alkyl group (eg, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group). Octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), cycloalkyl group (eg, cyclopentyl group, cyclohexyl group etc.), alkenyl group (eg, vinyl group, allyl group etc.), alkynyl group (eg, Ethynyl group, propargyl group, etc.), aryl group (for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, xylyl group, naphthyl group, anthryl group, azulenyl group, acenaphthenyl group, fluorenyl group, phenanthryl group, indenyl group , Pyrenyl group, biphenylyl group, etc.), aromatic heterocyclic group (eg For example, furyl group, thienyl group, pyridyl group, pyridazyl group, pyrimidyl group, pyrazyl group, triazyl group, imidazolyl group, pyrazolyl group, thiazolyl group, benzoimidazolyl group, benzoxazolyl group, quinazolyl group, phthalazyl group, etc.), complex Ring groups (eg, pyrrolidyl, imidazolidyl, morpholyl, oxazolidyl, etc.), alkoxy groups (eg, methoxy, ethoxy, propyloxy, pentyloxy, hexyloxy, octyloxy, dodecyloxy, etc.) ), A cycloalkoxy group (eg, cyclopentyloxy group, cyclohexyloxy group, etc.), an aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), an alkylthio group (eg, methylthio group, ethylthio group, propylthio group, pentylthio group, F Xylthio group, octylthio group, dodecylthio group, etc.), cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.), arylthio group (eg, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (eg, methyloxycarbonyl group, etc.) , Ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group) , Methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl , Dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl) Group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, Dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group) Group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, Aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl Group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethyl) Ureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl) Group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, Cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group (for example, phenylsulfonyl group, naphthyl) Sulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino) Group, 2-pyridylamino group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom, etc.), fluorinated hydrocarbon group (eg, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl) Group), cyano group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, etc.), carbazolyl group, benzofuryl group, carbolinyl group, diarylamino group and the like. Here, the aryl of the diarylamino group has the same meaning as the aryl group described above as the substituent represented by A ₁ and A ₂ in the general formula (2).
These groups may further have a substituent.

In the general formula (2), _{L 1} and _{L 2} represents a divalent linking group.
In the general formula (2), the divalent linking group represented by L ₁ and L ₂ is an alkylene group (for example, an ethylene group, a trimethylene group, a tetramethylene group, a propylene group, an ethylethylene group, a pentamethylene group, Hexamethylene group, etc.), alkenylene group (for example, vinylene group, propenylene group, butenylene group, pentenylene group, 1-methylvinylene group, 1-methylpropenylene group, 2-methylpropenylene group, 1-methylpentenylene group) 3-methylpentenylene group, 1-ethylvinylene group, 1-ethylpropenylene group, 1-ethylbutenylene group, 3-ethylbutenylene group, etc.), alkynylene group (for example, ethynylene group, 1-propynylene group, 1-butynylene) Group, 1-pentynylene group, 1-hexynylene group, 2-butynylene group, 2-pentynylene 1-methylethynylene group, 3-methyl-1-propynylene group, 3-methyl-1-butynylene group, etc.), arylene group (for example, o-phenylene group, m-phenylene group, p-phenylene group, naphthalenediyl group, Anthracenediyl group, naphthacenediyl group, pyrenediyl group, naphthylnaphthalenediyl group, biphenyldiyl group (for example, [1,1′-biphenyl] -4,4′-diyl group, 3,3′-biphenyldiyl group, 3,6 -Biphenyldiyl group, etc.), terphenyldiyl group, quaterphenyldiyl group, kinkphenyldiyl group, sexiphenyldiyl group, septiphenyldiyl group, octylphenyldiyl group, nobiphenyldiyl group, deciphenyldiyl group, etc. ), Heteroarylene groups (eg, carbazole ring, carboline ring, diazacar Vazole ring (also called monoazacarboline ring, which shows a ring structure in which one of carbon atoms constituting carboline ring is replaced by nitrogen atom), triazole ring, pyrrole ring, pyridine ring, pyrazine ring, quinoxaline ring, thiophene ring Divalent groups derived from the group consisting of oxadiazole ring, dibenzofuran ring, dibenzothiophene ring and indole ring), divalent heterocyclic groups (eg pyrrolidine ring, imidazolidine ring, morpholine ring, oxazolidine ring) Etc.), and may be a chalcogen atom such as oxygen or sulfur.
Moreover, the group connected through a hetero atom, such as an alkylimino group, a dialkylsilanediyl group or a diarylgermandiyl group, may be used.

In addition, the linking group represented by L ₁ and L ₂ in the general formula (2) is preferably an arylene group, a heteroarylene group, a divalent heterocyclic group, an alkylene group, or the like, and more preferably an arylene group. And particularly preferably an m-phenylene group.

  In General formula (2), n represents an integer greater than or equal to 1, n1 and n2 represent an integer greater than or equal to 0, and n3 and n4 represent 0 or 1. However, n1 + n2 ≧ 2.

  Hereinafter, although the specific compound represented with General formula (2) based on this invention is enumerated, it is not limited to these.

  Further, the highest occupied molecular orbital HOMO (HT2) of the second hole transport material in the present invention is −5.4 eV <HOMO (HT2) <− 4.9 eV, and −5.1 eV <HOMO (HT2) <−. It is preferably 4.95 eV. The reason why the value of HOMO (HT2) is within the above range is that when it is −5.4 eV or less, hole injection into the light emitting layer is remarkably reduced, resulting in deterioration of efficiency, lifetime, and color stability. This is because the hole trapping property of the general formula (1) is strong when it is .9 eV or more, so that holes are likely to be accumulated at the light emitting layer / hole transporting layer interface, and the efficiency, lifetime, and color stability are similarly reduced. .

  Furthermore, the relationship between the excited triplet energy T1 (D) of the phosphorescent dopant compound in the present invention and the excited triplet energy T1 (HT2) of the second hole transport material is T1 (HT2) -T1 ( D)> 0.1 eV, preferably 0.1 eV <T1 (HT2) −T1 (D) <0.5 eV. When the value of T1 (HT2) -T1 (D) is within the above range, the energy transfer from the phosphorescent light emitting dopant to the hole transport material used for the second hole transport layer is less than 0.1 eV. This is because efficiency, life and color stability are deteriorated.

  Further, the relationship between the highest occupied molecular orbital HOMO (HT1) of the first hole transporting material used in the first hole transporting layer and the highest occupied molecular orbital HOMO (HT2) of the second hole transporting material is −0. .5eV <HOMO (HT2) -HOMO (HT1) <-0.1 eV, more preferably -0.4 eV <HOMO (HT2) -HOMO (HT1) <-0.1 eV. The value of HOMO (HT2) -HOMO (HT1) is within the above range. When the value is less than −0.5 eV, the hole transport ability from HT1 to HT2 decreases, and the amount of holes injected into the light emitting layer decreases. As a result, the efficiency, life, and color stability are lowered, and if it exceeds -0.1 eV, the amount of holes injected into the light emitting layer cannot be controlled, and the efficiency, life, and color stability are also lowered. This is because of the result.

《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer can be provided with a single layer or a plurality of layers.

  An electron transport material (including a hole blocking material and an electron injection material) used for the electron transport layer only needs to have a function of transmitting electrons injected from the cathode to the light emitting layer. Can be selected from any conventionally known compounds and used alone or in combination.

Examples of conventionally known materials used for the electron transport layer (hereinafter referred to as electron transport materials) include heterocyclic tetracarboxylic acid anhydrides such as nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, naphthalene perylene, And azacarbazole derivatives including carbodiimide, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives, carboline derivatives, and the like. Here, the azacarbazole derivative refers to one in which one or more carbon atoms constituting the carbazole ring are replaced with a nitrogen atom. Furthermore, in the oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron-withdrawing group can also be used as an electron transport material.
In addition, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  In addition, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), and the like, and the central metals of these metal complexes are In, Mg, Metal complexes replaced with Cu, Ca, Sn, Ga or Pb can also be used as the electron transport material.

  In addition, metal-free or metal phthalocyanine, or those having the terminal substituted with an alkyl group or a sulfonic acid group can also be used as the electron transport material.

  Further, similarly to the hole injection layer and the hole transport layer, inorganic semiconductors such as n-type-Si and n-type-SiC can also be used as the electron transport material.

  Although there is no restriction | limiting in particular about the film thickness of an electron carrying layer, Usually, about 5 nm-5000 nm, Preferably it is 5 nm-200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials, or may have a stacked structure in which a plurality of layers are stacked.

  Further, an electron transport layer having a high n property doped with impurities can also be used. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

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

  The electron transport material preferably used in the present invention is an azacarbazole derivative or an 8-quinolinol derivative, the azacarbazole derivative is represented by the following general formula (3), and the 8-quinolinol derivative is represented by the following general formula (4 ).

  In General Formula (3), R61 represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group, X1 to X8 represent N or —CR62, and R62 represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group. Represent.

  In general formula (4), A represents Li, Be, or Al.

  Hereinafter, although the specific example of a compound represented by General formula (3) is given, this invention is not limited to these.

  Hereinafter, although the specific example of a compound represented by General formula (4) is given, this invention is not limited to these.

<Blocking layer: hole blocking layer, electron blocking layer>
The blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film as described above. For example, it is described in JP-A Nos. 11-204258, 11-204359, and “Organic EL elements and their forefront of industrialization” (issued by NTT, Inc. on November 30, 1998). There is a hole blocking (hole blocking) layer.

The hole blocking layer has a function of an electron transport layer in a broad sense, and is made of a hole blocking material that has a function of transporting electrons and has a remarkably small ability to transport holes. The probability of recombination of electrons and holes can be improved by blocking.
Moreover, the structure of the above-mentioned electron carrying layer can be used as a hole-blocking layer concerning this invention as needed.

  The hole blocking layer of the organic EL device of the present invention is preferably provided adjacent to the light emitting layer.

  The hole blocking layer contains carbazole derivatives, azacarbazole derivatives (where azacarbazole derivatives are those in which one or more carbon atoms constituting the carbazole ring are replaced by nitrogen atoms), pyridine derivatives, and the like. It is preferable to contain a nitrogen compound.

  In the present invention, when a plurality of light emitting layers having different light emission colors are provided, the light emitting layer having the shortest wavelength of light emission is preferably closest to the anode among all the light emitting layers. In this case, it is preferable to additionally provide a hole blocking layer between the shortest wave layer and the light emitting layer next to the anode next to the anode.

  Furthermore, it is preferable that 50% by mass or more of the compound contained in the hole blocking layer provided at the position has an ionization potential of 0.3 eV or more larger than the host compound of the shortest wave emitting layer.

The ionization potential is defined by the energy required to emit electrons at the HOMO (highest occupied orbital) level of the compound to the vacuum level, and can be determined by, for example, the following method.
(1) Using Gaussian 98 (Gaussian 98, Revision A.11.4, MJ Frisch, et al, Gaussian, Inc., Pittsburgh PA, 2002.), a molecular orbital calculation software manufactured by Gaussian, USA As a value (eV unit converted value) calculated by performing structure optimization using B3LYP / 6-31G *. This calculation value is effective because the correlation between the calculation value obtained by this method and the experimental value is high.
(2) The ionization potential can also be obtained by a method of directly measuring by photoelectron spectroscopy. For example, a method known as ultraviolet photoelectron spectroscopy can be suitably used by using a low energy electron spectrometer “Model AC-1” manufactured by Riken Keiki Co., Ltd.

  On the other hand, the electron blocking layer has a function of a hole transport layer in a broad sense, and is made of a material that has a function of transporting holes and has an extremely small ability to transport electrons, and transports electrons while transporting holes. By blocking, the recombination probability of electrons and holes can be improved.

  Moreover, the structure of the above-mentioned hole transport layer can be used as an electron blocking layer as needed. The film thickness of the hole blocking layer and the electron blocking layer according to the present invention is preferably 3 nm to 100 nm, more preferably 3 nm to 30 nm.

"anode"
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such electrode materials include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ , and ZnO. Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming a transparent conductive film may be used.

For the anode, these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when pattern accuracy is not so high (about 100 μm or more) A pattern may be formed through a mask having a desired shape at the time of vapor deposition or sputtering of the electrode material.
Or when using the substance which can be apply | coated like an organic electroconductivity compound, wet film-forming methods, such as a printing system and a coating system, can also be used.

  When light emission is extracted from the anode, it is desirable that the transmittance be greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 nm to 1000 nm, preferably 10 nm to 200 nm.

"cathode"
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used.
Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like.
Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred.

  The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as a cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 nm to 200 nm.

  In order to transmit the emitted light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the light emission luminance is improved, which is convenient.

  Moreover, after producing the said metal by the film thickness of 1 nm-20 nm to a cathode, the transparent or semi-transparent cathode can be produced by producing the electroconductive transparent material quoted by description of the anode on it, By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.

《Support substrate》
As a support substrate (hereinafter also referred to as a substrate, substrate, substrate, support, etc.) that can be used in the organic EL device of the present invention, there is no particular limitation on the type of glass, plastic, etc., and it is transparent. May be opaque. When extracting light from the support substrate side, the support substrate is preferably transparent.
Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable support substrate is a resin film capable of giving flexibility to the organic EL element.

  Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate (CAP), Cellulose esters such as cellulose acetate phthalate (TAC) and cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones Cycloolefin resins such as polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylate, Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Can be mentioned.

On the surface of the resin film, an inorganic film, an organic film, or a hybrid film of both may be formed. Water vapor permeability (25 ± 0.5 ° C.) measured by a method according to JIS K 7129-1992. , Relative humidity (90 ± 2)% RH) is preferably 0.01 g / (m ² · 24 h) or less, and further, oxygen measured by a method according to JIS K 7126-1987. A high barrier film having a permeability of 10 ⁻³ ml / (m ² · 24 h · MPa) or less and a water vapor permeability of 10 ⁻⁵ g / (m ² · 24 h) or less is preferable.

As a material for forming the barrier film, any material may be used as long as it has a function of suppressing entry of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like can be used.
Further, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and organic material layers. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times.

  The method for forming the barrier film is not particularly limited. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma polymerization A plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.

  Examples of the opaque support substrate include metal plates such as aluminum and stainless steel, films, opaque resin substrates, and ceramic substrates.

The external extraction efficiency at room temperature of light emission of the organic EL device of the present invention is preferably 1% or more, more preferably 5% or more.
Here, external extraction quantum efficiency (%) = number of photons emitted to the outside of the organic EL element / number of electrons flowed to the organic EL element × 100.

  In addition, a hue improvement filter such as a color filter may be used in combination, or a color conversion filter that converts the emission color from the organic EL element into multiple colors using a phosphor. In the case of using a color conversion filter, the λmax of light emission of the organic EL element is preferably 480 nm or less.

<< Method for Manufacturing Organic EL Element >>
As an example of a method for producing an organic EL device, a device comprising an anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer (electron injection layer) / cathode Will be described.

  First, a desired electrode material, for example, a thin film made of a material for an anode is formed on a suitable substrate so as to have a thickness of 1 μm or less, preferably 10 nm to 200 nm, thereby producing an anode.

  Next, a thin film containing an organic compound such as a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, or a cathode buffer layer, which is an element material, is formed thereon.

  In the phosphorescent organic EL device of the present invention, at least the cathode and the electron transport layer adjacent to the cathode are applied and formed by a wet method.

  Wet methods include spin coating, casting, die coating, blade coating, roll coating, ink jet, printing, spray coating, curtain coating, and LB, but precise thin films can be formed. In view of high productivity, a method having high suitability for a roll-to-roll method such as a die coating method, a roll coating method, an ink jet method, or a spray coating method is preferable. Different film forming methods may be applied for each layer.

Examples of the liquid medium for dissolving or dispersing the organic EL material according to the present invention include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene, xylene, and mesitylene. Aromatic hydrocarbons such as cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, and organic solvents such as DMF and DMSO can be used.
Moreover, as a dispersion method, it can disperse | distribute by dispersion methods, such as an ultrasonic wave, high shear force dispersion | distribution, and media dispersion | distribution.

  After these layers are formed, a thin film made of a cathode material is formed thereon so as to have a thickness of 1 μm or less, preferably in the range of 50 nm to 200 nm, and a desired organic EL device is obtained by providing a cathode. .

  Further, the order can be reversed, and the cathode, cathode buffer layer, electron transport layer, hole blocking layer, light emitting layer, hole transport layer, hole injection layer, and anode can be formed in this order.

  When a DC voltage is applied to the multicolor display device thus obtained, light emission can be observed by applying a voltage of about 2 V to 40 V with the anode as + and the cathode as-. An alternating voltage may be applied. The alternating current waveform to be applied may be arbitrary.

  The organic EL device of the present invention is preferably produced from the hole injection layer to the cathode consistently by a single evacuation, but may be taken out halfway and subjected to different film forming methods. At that time, it is preferable to perform the work in a dry inert gas atmosphere.

<Sealing>
The organic EL device of the present invention is preferably sealed by sealing with a sealing material in order to seal the anode, the cathode, and the layer between the cathode and the anode from the outside air.

  As a sealing means used for this invention, the method of adhere | attaching a sealing member, an electrode, and a support substrate with an adhesive agent can be mentioned, for example.

  As a sealing member, it should just be arrange | positioned so that the display area | region of an organic EL element may be covered, and concave plate shape or flat plate shape may be sufficient. Further, transparency and electrical insulation are not particularly limited.

Specific examples include a glass plate, a polymer plate / film, and a metal plate / film. Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz.
Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone. Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum.

In the present invention, a polymer film and a metal film can be preferably used because the element can be thinned.
Furthermore, the polymer film has a oxygen permeability measured by a method according to JIS K 7126-1987 of 1 × 10 ⁻³ ml / (m ² · 24 h · MPa) or less, and a method according to JIS K 7129-1992. It is preferable that the water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) measured in (1) is 1 × 10 ⁻³ g / (m ² · 24 h) or less.

  For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.

Specific examples of the adhesive include photocuring and thermosetting adhesives having reactive vinyl groups such as acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. be able to. Moreover, heat | fever and chemical curing types (two-component mixing), such as an epoxy type, can be mentioned.
Furthermore, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.

  In addition, since an organic EL element may deteriorate by heat processing, what can be adhesive-hardened from room temperature to 80 degreeC is preferable. A desiccant may be dispersed in the adhesive. Application | coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print like screen printing.

In addition, it is also preferable that the electrode and the organic layer are coated on the outside of the electrode facing the support substrate with the organic layer interposed therebetween, and an inorganic or organic layer is formed in contact with the support substrate to form a sealing film. .
In this case, the material for forming the film may be any material that has a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can.
Further, in order to improve the brittleness of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of organic materials.
The method for forming these films is not particularly limited. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.

  In the gap between the sealing member and the display area of the organic EL element, an inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil can be injected in the gas phase and liquid phase. preferable. A vacuum is also possible. Moreover, a hygroscopic compound can also be enclosed inside.

  Examples of the hygroscopic compound include metal oxides (for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide) and sulfates (for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate). Etc.), metal halides (eg calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide etc.), perchloric acids (eg perchloric acid) Barium, magnesium perchlorate, etc.) and the like, and sulfates, metal halides and perchloric acids are preferably anhydrous salts.

《Protective film, protective plate》
In order to increase the mechanical strength of the element, a protective film or a protective plate may be provided on the outer side of the sealing film on the side facing the support substrate with the organic layer interposed therebetween or on the sealing film. In particular, when the sealing is performed by the sealing film, the mechanical strength is not necessarily high, and thus it is preferable to provide such a protective film and a protective plate.
As a material that can be used for this, the same glass plate, polymer plate / film, metal plate / film, and the like used for the sealing can be used, but the polymer film is light and thin. Is preferably used.

《Light extraction》
The organic EL element emits light inside a layer having a refractive index higher than that of air (refractive index is about 1.7 to 2.1) and can extract only about 15% to 20% of the light generated in the light emitting layer. It is generally said. This is because light incident on the interface (interface between the transparent substrate and air) at an angle θ greater than the critical angle causes total reflection and cannot be taken out of the device, or between the transparent electrode or light emitting layer and the transparent substrate. This is because the light is totally reflected between the light and the light is guided through the transparent electrode or the light emitting layer, and as a result, the light escapes in the direction of the element side surface.

  As a method for improving the light extraction efficiency, for example, a method of forming irregularities on the surface of the transparent substrate to prevent total reflection at the interface between the transparent substrate and the air (US Pat. No. 4,774,435), A method of improving efficiency by providing a light collecting property to a substrate (Japanese Patent Laid-Open No. 63-314795), a method of forming a reflective surface on a side surface of an element (Japanese Patent Laid-Open No. 1-220394), and light emission from a substrate A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the bodies (Japanese Patent Laid-Open No. 62-172691), a flat having a lower refractive index between the substrate and the light emitter than the substrate A method of introducing a layer (Japanese Patent Laid-Open No. 2001-202827), a method of forming a diffraction grating between any one of a substrate, a transparent electrode layer and a light emitting layer (including between the substrate and the outside) (Japanese Patent Laid-Open No. 11-283951) Gazette).

  In the present invention, these methods can be used in combination with the organic EL device of the present invention. However, a method of introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter, or a substrate, transparent A method of forming a diffraction grating between any layers of the electrode layer and the light emitting layer (including between the substrate and the outside) can be suitably used.

  In the present invention, by combining these means, it is possible to obtain an element having higher luminance or durability.

When a medium having a low refractive index is formed between the transparent electrode and the transparent substrate with a thickness longer than the wavelength of light, the light extracted from the transparent electrode has a higher extraction efficiency to the outside as the refractive index of the medium is lower.
Examples of the low refractive index layer include aerogel, porous silica, magnesium fluoride, and a fluorine-based polymer. Since the refractive index of the transparent substrate is generally about 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less. Further, it is preferably 1.35 or less.

  The thickness of the low refractive index medium is preferably at least twice the wavelength in the medium. This is because the effect of the low refractive index layer is diminished when the thickness of the low refractive index medium is about the wavelength of light and the electromagnetic wave that has exuded by evanescent enters the substrate.

  The method of introducing a diffraction grating into an interface or any medium that causes total reflection is characterized by a high effect of improving light extraction efficiency. This method uses the property that the diffraction grating can change the direction of light to a specific direction different from refraction by so-called Bragg diffraction such as first-order diffraction and second-order diffraction. Light that cannot be emitted due to total internal reflection between layers is diffracted by introducing a diffraction grating in any layer or medium (in a transparent substrate or transparent electrode), and the light is removed. I want to take it out.

The introduced diffraction grating preferably has a two-dimensional periodic refractive index. This is because light emitted from the light-emitting layer is randomly generated in all directions, so in a general one-dimensional diffraction grating having a periodic refractive index distribution only in a certain direction, only light traveling in a specific direction is diffracted. Therefore, the light extraction efficiency does not increase so much.
However, by making the refractive index distribution a two-dimensional distribution, light traveling in all directions is diffracted, and light extraction efficiency is increased.

As described above, the position where the diffraction grating is introduced may be in any of the layers or in the medium (in the transparent substrate or in the transparent electrode), but is preferably in the vicinity of the organic light emitting layer where light is generated.
At this time, the period of the diffraction grating is preferably about 1/2 to 3 times the wavelength of light in the medium.

  The arrangement of the diffraction grating is preferably two-dimensionally repeated such as a square lattice, a triangular lattice, or a honeycomb lattice.

<Condenser sheet>
The organic EL element of the present invention is processed on the light extraction side of the substrate, for example, so as to provide a microlens array-like structure, or in combination with a so-called condensing sheet, so that the organic EL element can be directed to a specific direction, By condensing in the front direction, the luminance in a specific direction can be increased.

  As an example of the microlens array, quadrangular pyramids having a side of 30 μm and an apex angle of 90 degrees are arranged two-dimensionally on the light extraction side of the substrate. One side is preferably 10 μm to 100 μm. If it becomes smaller than this, the effect of diffraction will generate | occur | produce and color, and if too large, thickness will become thick and is not preferable.

  As the condensing sheet, for example, a sheet that is put into practical use in an LED backlight of a liquid crystal display device can be used. As such a sheet, for example, a brightness enhancement film (BEF) manufactured by Sumitomo 3M Limited can be used.

  As the shape of the prism sheet, for example, the base material may be formed by forming a △ -shaped stripe having a vertex angle of 90 degrees and a pitch of 50 μm, or the vertex angle is rounded and the pitch is changed randomly. Other shapes may be used.

  Moreover, in order to control the light emission angle from a light emitting element, you may use together a light diffusing plate and a film with a condensing sheet. For example, a diffusion film (light-up) manufactured by Kimoto Co., Ltd. can be used.

<Application>
The organic EL element of the present invention can be used as a display device, a display, and various light emission sources. For example, lighting devices (home lighting, interior lighting), clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources of optical storage media, light sources of electrophotographic copying machines, light sources of optical communication processors, light Although the light source of a sensor etc. are mentioned, It is not limited to this, Especially, it can use effectively for the use as a backlight of a liquid crystal display device, and a light source for illumination.

  In the organic EL element of the present invention, patterning may be performed by a metal mask, an ink jet printing method, or the like as needed during film formation. In the case of patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire layer of the element may be patterned. In the fabrication of the element, a conventionally known method is used. Can do.

  The light emission color of the organic EL device of the present invention and the compound according to the present invention is shown in FIG. 4.16 on page 108 of “New Color Science Handbook” (edited by the Japan Color Society, University of Tokyo Press, 1985). It is determined by the color when the result measured with a total CS-1000 (Konica Minolta Sensing Co., Ltd.) is applied to the CIE chromaticity coordinates.

When the organic EL element of the present invention is a white element, white means that the chromaticity in the CIE1931 color system at 1000 cd / m ² is X when the 2 ° viewing angle front luminance is measured by the above method. = 0.33 ± 0.07 and Y = 0.33 ± 0.1.

<Display device>
The display device of the present invention will be described. The display device of the present invention comprises the organic EL element of the present invention.
Although the display device of the present invention may be single color or multicolor, the multicolor display device will be described here.

In the case of a multicolor display device, a shadow mask is provided only at the time of forming a light emitting layer, and a film can be formed on one surface by vapor deposition, casting, spin coating, ink jet, printing, or the like.
In the case of patterning only the light emitting layer, the method is not limited. However, the vapor deposition method, the ink jet method, the spin coating method, and the printing method are preferable.

The configuration of the organic EL element provided in the display device is selected from the above-described configuration examples of the organic EL element as necessary.
Moreover, the manufacturing method of an organic EL element is as having shown to the one aspect | mode of manufacture of the organic EL element of said invention.

  In the case of applying a DC voltage to the obtained multicolor display device, light emission can be observed by applying a voltage of about 2V to 40V with the positive polarity of the anode and the negative polarity of the cathode. Further, even when a voltage is applied with the opposite polarity, no current flows and no light emission occurs. Further, when an AC voltage is applied, light is emitted only when the anode is in the + state and the cathode is in the-state. The alternating current waveform to be applied may be arbitrary.

  The multicolor display device can be used as a display device, a display, and various light emission sources. In a display device or display, full-color display is possible by using three types of organic EL elements of blue, red, and green light emission.

  Examples of the display device and display include a television, a personal computer, a mobile device, an AV device, a character broadcast display, and an information display in an automobile. In particular, it may be used as a display device for reproducing still images and moving images, and the driving method when used as a display device for reproducing moving images may be either a simple matrix (passive matrix) method or an active matrix method.

  Light sources include home lighting, interior lighting, clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, light sources for optical sensors, etc. The present invention is not limited to these examples.

  Hereinafter, an example of a display device having the organic EL element of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view showing an example of a display device composed of organic EL elements. It is a schematic diagram of a display such as a mobile phone that displays image information by light emission of an organic EL element.
The display 1 includes a display unit A having a plurality of pixels, a control unit B that performs image scanning of the display unit A based on image information, and the like.
The control unit B is electrically connected to the display unit A, and sends a scanning signal and an image data signal to each of a plurality of pixels based on image information from the outside, and the pixels for each scanning line respond to the image data signal by the scanning signal. The image information is sequentially emitted to scan the image and display the image information on the display unit A.

FIG. 2 is a schematic diagram of the display unit A.
The display unit A includes a wiring unit including a plurality of scanning lines 5 and data lines 6, a plurality of pixels 3 and the like on a substrate. The main members of the display unit A will be described below.
In the figure, the light emitted from the pixel 3 is extracted in the direction of the white arrow (downward).
The scanning line 5 and the plurality of data lines 6 in the wiring portion are each made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a grid pattern and are connected to the pixels 3 at the orthogonal positions (details are illustrated). Not)
When a scanning signal is applied from the scanning line 5, the pixel 3 receives an image data signal from the data line 6 and emits light according to the received image data.
Full-color display is possible by appropriately arranging pixels in the red region, the green region, and the blue region on the same substrate.

Next, the light emission process of the pixel will be described.
FIG. 3 is a schematic diagram of a pixel.
The pixel includes an organic EL element 10, a switching transistor 11, a driving transistor 12, a capacitor 13, and the like. A full color display can be performed by using red, green, and blue light emitting organic EL elements as the organic EL elements 10 in a plurality of pixels, and juxtaposing them on the same substrate.

  In FIG. 3, an image data signal is applied from the control unit B to the drain of the switching transistor 11 through the data line 6. When a scanning signal is applied from the control unit B to the gate of the switching transistor 11 via the scanning line 5, the driving of the switching transistor 11 is turned on, and the image data signal applied to the drain is supplied to the capacitor 13 and the driving transistor 12. Is transmitted to the gate.

  By transmitting the image data signal, the capacitor 13 is charged according to the potential of the image data signal, and the drive transistor 12 is turned on. The drive transistor 12 has a drain connected to the power supply line 7 and a source connected to the electrode of the organic EL element 10. The power supply line 7 connects the organic EL element 10 to the potential of the image data signal applied to the gate. Current is supplied.

When the scanning signal is moved to the next scanning line 5 by the sequential scanning of the control unit B, the driving of the switching transistor 11 is turned off.
However, since the capacitor 13 holds the charged potential of the image data signal even when the driving of the switching transistor 11 is turned off, the driving of the driving transistor 12 is kept on and the next scanning signal is applied. Until then, the light emission of the organic EL element 10 continues.
When the scanning signal is next applied by sequential scanning, the driving transistor 12 is driven according to the potential of the next image data signal synchronized with the scanning signal, and the organic EL element 10 emits light.
That is, the organic EL element 10 emits light by the switching transistor 11 and the drive transistor 12 that are active elements for the organic EL elements 10 of the plurality of pixels, and the organic EL elements 10 of the plurality of pixels 3 emit light. It is carried out. Such a light emitting method is called an active matrix method.

Here, the light emission of the organic EL element 10 may be light emission of a plurality of gradations by a multi-value image data signal having a plurality of gradation potentials, or by turning on / off a predetermined light emission amount by a binary image data signal. Good. The potential of the capacitor 13 may be held continuously until the next scanning signal is applied, or may be discharged immediately before the next scanning signal is applied.
In the present invention, not only the active matrix method described above, but also a passive matrix light emission drive in which the organic EL element emits light according to the data signal only when the scanning signal is scanned.

FIG. 4 is a schematic diagram of a passive matrix display device. In FIG. 4, a plurality of scanning lines 5 and a plurality of image data lines 6 are provided in a lattice shape so as to face each other with the pixel 3 interposed therebetween.
When the scanning signal of the scanning line 5 is applied by sequential scanning, the pixels 3 connected to the applied scanning line 5 emit light according to the image data signal.
In the passive matrix system, the pixel 3 has no active element, and the manufacturing cost can be reduced.

《Lighting device》
The lighting device of the present invention will be described. The illumination device of the present invention has the organic EL element.
The organic EL element of the present invention may be used as an organic EL element having a resonator structure. The purpose of use of the organic EL element having such a resonator structure is as follows. The light source of a machine, the light source of an optical communication processing machine, the light source of a photosensor, etc. are mentioned, However It is not limited to these. Moreover, you may use for the said use by making a laser oscillation.
Further, the organic EL element of the present invention may be used as a kind of lamp for illumination or exposure light source, a projection device for projecting an image, or a display for directly viewing a still image or a moving image. It may be used as a device (display).
The driving method when used as a display device for moving image reproduction may be either a simple matrix (passive matrix) method or an active matrix method. Alternatively, a full-color display device can be manufactured by using two or more organic EL elements of the present invention having different emission colors.

The organic EL material of the present invention can be applied to an organic EL element that emits substantially white light as a lighting device. A plurality of light emitting colors are simultaneously emitted by a plurality of light emitting materials to obtain white light emission by color mixing.
The combination of a plurality of emission colors may include three emission maximum wavelengths of the three primary colors of blue, green, and blue, or two using the relationship of complementary colors such as blue and yellow, blue green and orange, etc. The thing containing the light emission maximum wavelength may be used.
In addition, the combination of luminescent materials for obtaining multiple luminescent colors is a combination of multiple phosphorescent or fluorescent materials that emit light, fluorescent materials or phosphorescent materials, and light from the luminescent materials. Any combination with a dye material that emits light as light may be used, but in the white organic EL device according to the present invention, it is only necessary to mix and mix a plurality of light emitting dopants.

It is only necessary to provide a mask only when forming a light emitting layer, a hole transport layer, an electron transport layer, etc., and simply arrange them separately by coating with the mask. Since other layers are common, patterning of the mask or the like is not necessary. In addition, for example, an electrode film can be formed by a vapor deposition method, a cast method, a spin coating method, an ink jet method, a printing method, or the like, and productivity is also improved.
According to this method, unlike a white organic EL device in which light emitting elements of a plurality of colors are arranged in parallel in an array, the elements themselves are luminescent white.
There is no restriction | limiting in particular as a luminescent material used for a light emitting layer, For example, if it is a backlight in a liquid crystal display element, the metal complex which concerns on this invention so that it may suit the wavelength range corresponding to CF (color filter) characteristic, Any one of known luminescent materials may be selected and combined to whiten.

<< One Embodiment of Lighting Device of the Present Invention >>
One aspect of the lighting device of the present invention that includes the organic EL element of the present invention will be described.
The non-light emitting surface of the organic EL device of the present invention is covered with a glass case, a glass substrate having a thickness of 300 μm is used as a sealing substrate, and an epoxy-based photocurable adhesive (LUX TRACK manufactured by Toagosei Co., Ltd.) is used as a sealing material. LC0629B) is applied, and this is overlaid on the cathode and brought into close contact with the transparent support substrate, irradiated with UV light from the glass substrate side, cured and sealed, and an illumination device as shown in FIGS. Can be formed.
FIG. 5 shows a schematic diagram of a lighting device, and the organic EL element 101 of the present invention is covered with a glass cover 102 (in the sealing operation with the glass cover, the organic EL element 101 is brought into contact with the atmosphere. And a glove box under a nitrogen atmosphere (in an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more).
FIG. 6 is a cross-sectional view of the lighting device. In FIG. 6, reference numeral 105 denotes a cathode, 106 denotes an organic EL layer, and 107 denotes a glass substrate with a transparent electrode (anode).
The glass cover 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.
Moreover, the structure of the compound used for an Example is shown below.

<< Production of Organic EL Element 1-1 >>
A transparent substrate provided with this ITO transparent electrode after patterning on a substrate (NA45 manufactured by NH Techno Glass Co., Ltd.) on which a 100 nm ITO (indium tin oxide) film was formed as an anode on a 100 mm × 100 mm × 1.1 mm glass substrate The supporting substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes.

  This transparent support substrate is fixed to a substrate holder of a commercially available vacuum evaporation apparatus, while 200 mg of HT-30 is put in a molybdenum resistance heating boat, and 200 mg of HT-2 is put in another molybdenum resistance heating boat. Compound (45) is put into a resistance heating boat, 200 mg of H1 is put into another resistance heating boat made of molybdenum, 200 mg of DP-1 is put into another resistance heating boat made of molybdenum, and compound 3- is put into another resistance heating boat made of molybdenum. 200 mg of 7 was placed and attached to a vacuum deposition apparatus.

Next, the pressure in the vacuum chamber was reduced to 4 × 10 ⁻⁴ Pa, and the heating boat containing HT-30 was energized and heated, and deposited on the transparent support substrate at a deposition rate of 0.1 nm / sec. The hole injection layer was provided.

  Further, the heating boat containing HT-2 is energized and heated, and is deposited on the hole injection layer at a deposition rate of 0.1 nm / second to provide a first hole transport layer (HT1) having a thickness of 20 nm. Subsequently, the heating boat containing the compound (45) is energized and heated, and deposited on the first hole transporting layer at a deposition rate of 0.1 nm / second to form a second hole transporting layer having a thickness of 20 nm. (HT2) was provided.

  Further, the heating boat containing H1 and DP-1 was energized and heated, and co-deposited on the second hole transport layer at a deposition rate of 0.1 nm / second and 0.025 nm / second, respectively. A light emitting layer was provided.

  Furthermore, it supplied with electricity to the said heating boat containing the compound 3-7, it heated, and it vapor-deposited on the said light emitting layer with the vapor deposition rate of 0.1 nm / second, and provided the electron carrying layer (ET) with a film thickness of 20 nm.

  Subsequently, potassium fluoride was vapor-deposited to provide a cathode buffer layer having a thickness of 0.5 nm, and aluminum was further vapor-deposited to provide a cathode having a thickness of 110 nm to produce an organic EL element 1-1.

<< Production of Organic EL Elements 1-2 to 1-29 >>
In the production of the organic EL device 1-1, HT-2, compound (45), DP-1, H1, and compound 3-7 were changed to the compounds shown in Table 1.
Other than that produced the organic EL element 1-2 to 1-29 similarly.
Table 1 shows the values of the highest occupied molecular orbitals HOMO of the first and second hole transport materials, and | HOMO (HT2) −HOMO (HT1) | = ΔHOMO, and the second hole transport material. And the excited triplet energy value T1 of the blue light emitting dopant of the light emitting layer, and | T1 (HT2) −T1 (D) | = ΔT1.

<< Evaluation of Organic EL Elements 1-1 to 1-29 >>
When evaluating the obtained organic EL elements 1-1 to 1-29, the non-light-emitting surface of each organic EL element after production is covered with a glass cover, and the glass cover and the glass substrate on which the organic EL element is produced are prepared. An epoxy-based photo-curing adhesive (Luxtrac LC0629B manufactured by Toagosei Co., Ltd.) is applied as a sealant around the glass cover side that comes into contact with the transparent support substrate so as to overlap the cathode side, and the glass substrate side. The portion excluding the organic EL element was irradiated with UV light to be cured and sealed to form an illumination device as shown in FIGS. 5 and 6, and the illumination device was evaluated as a sample.

  The following evaluation was performed on each sample thus produced. The evaluation results are shown in Table 1.

(1) External extraction quantum efficiency (EQE)
By causing the organic EL device to emit light at room temperature (about 23 ° C. to 25 ° C.) and a constant current of ^2.5 mA / cm ² , and measuring the light emission luminance (L) [cd / m ² ] immediately after the start of light emission, The external extraction quantum efficiency (η) was calculated.
Here, CS-1000 (manufactured by Konica Minolta Sensing) was used for measurement of light emission luminance.
The external extraction quantum efficiency is expressed as a relative value where the organic EL element 1-4 is 100.

(2) Luminescence Lifetime The organic EL element was continuously lit under a constant current condition of ^2.5 mA / cm ² at room temperature, and the time (τ1 / 2) required to reach half the initial luminance was measured. In addition, the light emission lifetime was represented by the relative value which sets the organic EL element 1-4 to 100.

(3) Chromaticity stability The chromaticity fluctuation range is obtained by calculating the maximum fluctuation distance ΔE of CIE1931, x, y value at the front luminance of 1000 cd / m ² of the sample before and after the light emission lifetime measurement by the following formula: The result of 1-4 was set to 100 as a relative value. A smaller value means less fluctuation and better chromaticity stability. For the measurement of the front luminance, a spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing) was used.
ΔE = (Δx ² + Δy ² ) ^1/2

  As is clear from Table 1, the organic EL device in which the dopant compound of the present invention and a specific hole transport layer are laminated is superior in efficiency, life and chromaticity stability as compared with the organic EL device of the comparative example. it is obvious. An effect can be obtained when the compound represented by the general formula (1) is used, and -5.4 <HOMO (HT2) <-4.9 and T1 (HT2) -T1 (D)> 0.1. I understand. In addition, the effect is remarkable when the materials represented by the general formulas (5) to (11) are used.

<< Preparation of Organic EL Element 2-1 >>
A transparent substrate provided with this ITO transparent electrode after patterning on a substrate (NA45 manufactured by NH Techno Glass Co., Ltd.) on which a 100 nm ITO (indium tin oxide) film was formed as an anode on a 100 mm × 100 mm × 1.1 mm glass substrate The supporting substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes.

  This transparent support substrate is fixed to a substrate holder of a commercially available vacuum evaporation apparatus, while 200 mg of HT-30 is put in a molybdenum resistance heating boat, and 200 mg of HT-2 is put in another molybdenum resistance heating boat. Compound (45) is put into a resistance heating boat, 200 mg of H1 is put into another resistance heating boat made of molybdenum, 200 mg of DP-1 is put into another resistance heating boat made of molybdenum, and cGD-1 is put into another resistance heating boat made of molybdenum. 200 mg, 200 mg of cRD-1 was put into another molybdenum resistance heating boat, 200 mg of compound 3-7 was put into another resistance heating boat made of molybdenum, and attached to a vacuum deposition apparatus.

Then, after reducing the vacuum chamber to 4 × 10 ⁻⁴ Pa, the heating boat containing HT-30 is heated by heating, and deposited on the transparent support substrate at a deposition rate of 0.1 nm / second. A 10 nm hole injection layer was provided.

  Further, the heating boat containing HT-2 was energized and heated, and was deposited on the hole injection layer at a deposition rate of 0.1 nm / second to provide a first hole transport layer having a thickness of 20 nm. The heating boat containing the compound (45) was heated by energization, and was deposited on the first hole transport layer at a deposition rate of 0.1 nm / second to provide a second hole transport layer having a thickness of 20 nm. .

  Further, the heating boat containing H1, DP-1, cGD-1, and cRD-1 was energized and heated, and the deposition rates were 0.1 nm / second, 0.025 nm / second, 0.0007 nm / second, and. A light-emitting layer having a film thickness of 60 nm was formed by co-evaporation on the hole transport layer at 0002 nm / second.

  Furthermore, it supplied with electricity to the said heating boat containing the compound 3-7, it heated, and it vapor-deposited on the said light emitting layer with the vapor deposition rate of 0.1 nm / sec, and provided the electron carrying layer with a film thickness of 20 nm.

  Subsequently, potassium fluoride was vapor-deposited to provide a cathode buffer layer having a thickness of 0.5 nm, and aluminum was further vapor-deposited to provide a cathode having a thickness of 110 nm to produce an organic EL element 2-1.

<< Production of Organic EL Elements 2-2 to 2-29 >>
In production of the organic EL device 2-1, HT-2, compound (45), DP-1, H1, and compound 3-7 were changed to the compounds shown in Table 2.
Other than that produced the organic EL element 2-2 to 2-15 similarly.
Table 2 shows the values of the highest occupied molecular orbitals HOMO of the first and second hole transport materials, and | HOMO (HT2) −HOMO (HT1) | = ΔHOMO, and the second hole transport material. And the excited triplet energy value T1 of the blue light emitting dopant of the light emitting layer, and | T1 (HT2) −T1 (D) | = ΔT1.

<< Evaluation of Organic EL Elements 2-1 to 2-29 >>
When evaluating the obtained organic EL elements 2-1 to 2-29, these organic EL elements were sealed in the same manner as the organic EL elements 1-1 to 1-29 of Example 1, and FIG. A lighting device as shown in FIG.
Each sample thus prepared was evaluated for external extraction quantum efficiency, light emission lifetime, and chromaticity stability in the same manner as in Example 1. The external extraction quantum efficiency, the light emission lifetime, and the chromaticity stability are expressed as relative values with each characteristic value of the organic EL element 2-1 being 100.
The evaluation results are shown in Table 2.

  As is clear from Table 2, it is clear that the organic EL device of the present invention is superior in efficiency, lifetime and chromaticity stability as compared with the organic EL device of the comparative example. Even when the white element is used, it can be seen that the same effect as in Example 1 can be obtained.

<< Production of Organic EL Element 3-1 >>
A transparent substrate provided with this ITO transparent electrode after patterning on a substrate (NA45 manufactured by NH Techno Glass Co., Ltd.) on which a 100 nm ITO (indium tin oxide) film was formed as an anode on a 100 mm × 100 mm × 1.1 mm glass substrate The supporting substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes.

  This transparent support substrate is fixed to a substrate holder of a commercially available vacuum evaporation apparatus, while 200 mg of HT-30 is put in a molybdenum resistance heating boat, and 200 mg of HT-2 is put in another molybdenum resistance heating boat. 200 mg of compound (45) is put in a resistance heating boat, 200 mg of H1 is put in another resistance heating boat made of molybdenum, 200 mg of DP-1 is put in another resistance heating boat made of molybdenum, and HS2 is put in another resistance heating boat made of molybdenum. Put 200 mg of cGD-1 in another molybdenum resistance heating boat, put 200 mg of cRD-1 in another molybdenum resistance heating boat, put 200 mg of compound 4-1 in another molybdenum resistance heating boat, vacuum Attached to the vapor deposition apparatus.

Next, after reducing the vacuum chamber to 4 × 10 ⁻⁴ Pa, the heating boat containing HT-30 was heated by energization, and deposited on a transparent support substrate at a deposition rate of 0.1 nm / second. A hole injection layer was provided.

  Further, the heating boat containing HT-2 was energized and heated, and was deposited on the hole injection layer at a deposition rate of 0.1 nm / second to provide a first hole transport layer having a thickness of 20 nm. The heating boat containing the compound (45) was heated by energization, and was deposited on the first hole transport layer at a deposition rate of 0.1 nm / second to provide a second hole transport layer having a thickness of 20 nm. .

  Further, the heating boat containing H1 and DP-1 was energized and heated, and co-deposited on the first hole transport layer at a deposition rate of 0.1 nm / second and 0.02 nm / second, respectively. A first light emitting layer is provided, and then the heating boat containing HS2, cGD-1, and cRD-1 is energized and heated, and the deposition rates are 0.1 nm / second, 0.012 nm / second, and 0.002 nm / second, respectively. Second, a second light emitting layer having a thickness of 30 nm was provided by co-evaporation on the first light emitting layer.

  Furthermore, it supplied with electricity to the said heating boat containing the compound 4-1, and heated, and it vapor-deposited on the said 2nd light emitting layer with the vapor deposition rate of 0.1 nm / sec, and provided the electron carrying layer with a film thickness of 25 nm.

  Subsequently, potassium fluoride was vapor-deposited to provide a cathode buffer layer having a thickness of 0.5 nm, and aluminum was further vapor-deposited to provide a cathode having a thickness of 110 nm to produce an organic EL element 3-1.

<< Preparation of organic EL elements 3-2-3-29 >>
In the production of the organic EL element 3-1, HT-2, compound (45), DP-1, H1, and compound 3-7 were changed to the compounds shown in Table 3.
Other than that produced the organic EL element 3-2-3-8 similarly.
Table 3 shows the values of the highest occupied molecular orbitals HOMO of the first and second hole transport materials, and | HOMO (HT2) −HOMO (HT1) | = ΔHOMO, and the second hole transport material. And the excited triplet energy value T1 of the blue light emitting dopant of the first light emitting layer (EML1) and | T1 (HT2) −T1 (D) | = ΔT1. Table 3 also shows the excited triplet energy value T1 of the host compound of the first light emitting layer (EML1).

<< Evaluation of Organic EL Elements 3-1 to 3-29 >>
When evaluating the obtained organic EL elements 3-1 to 3-29, these organic EL elements were sealed in the same manner as the organic EL elements 1-1 to 1-29 of Example 1, and FIG. A lighting device as shown in FIG.
Each sample thus prepared was evaluated for external extraction quantum efficiency, light emission lifetime, and chromaticity stability in the same manner as in Example 1. The external extraction quantum efficiency, the light emission lifetime, and the chromaticity stability are expressed as relative values with each characteristic value of the organic EL element 3-1 being 100.
The evaluation results are shown in Table 3.

  As is clear from Table 3, it is clear that the organic EL device of the present invention is superior in efficiency, lifetime and chromaticity stability as compared with the organic EL device of the comparative example. It can be seen that the same effect as in Example 1 can be obtained even when the light emitting layer has two layers, and the same host or different hosts are used for the light emitting layer.

DESCRIPTION OF SYMBOLS 1 Display 3 Pixel 5 Scan line 6 Data line 7 Power supply line 10 Organic EL element 11 Switching transistor 12 Drive transistor 13 Capacitor 101 Organic EL element 102 Glass cover 105 Cathode 106 Organic EL layer 107 Glass substrate 108 with a transparent electrode Nitrogen gas 109 Water capturing Agent A Display unit B Control unit

Claims (13)

An organic layer having a multi-layer structure is provided between the anode and the cathode. In the organic layer, a hole injection layer, a first hole transport layer, a second hole transport layer, a host compound are formed from the anode to the cathode. A light emitting layer containing a phosphorescent dopant compound is an organic electroluminescence device in which each layer is laminated in this order,
The phosphorescent dopant compound is represented by the following general formula (1-1),
The host compound is represented by the following general formula (1) ′,
The second hole transport material used for the second hole transport layer is represented by the following general formula (2):
The highest occupied molecular orbital HOMO (HT2) of the second hole transport material satisfies −5.03 eV ≦ HOMO (HT2) ≦ −4.96 eV,
The relationship between the excited triplet energy T1 (D) of the phosphorescent dopant compound and the excited triplet energy T1 (HT2) of the second hole transport material is T1 (HT2) -T1 (D). An organic electroluminescence device satisfying ≧ 0.27 eV.

[In general formula (1-1), Ar represents an aromatic hydrocarbon ring, an aromatic heterocyclic ring, a non-aromatic hydrocarbon ring or a non-aromatic heterocyclic ring. R ₁ and R ₂ are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group, heteroaryl group, non-aromatic It represents an aromatic hydrocarbon ring group or a non-aromatic heterocyclic group, and may further have a substituent, and at least one of R ₁ and R ₂ is an alkyl group or a cycloalkyl group having 2 or more carbon atoms.
Ra, Rb and Rc are each independently a hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkynyl group, alkoxy group, amino group, silyl group, arylalkyl group, aryl group, heteroaryl group, non-aromatic Represents a hydrocarbon ring group or a non-aromatic heterocyclic group, and may further have a substituent. na and nc represent 1 or 2, and nb represents an integer of 1 to 4.
L ′ is one or more of monoanionic bidentate ligands coordinated to M, M represents a transition metal atom of atomic number 40 or more and group 8 to 10 in the periodic table, m 'Represents an integer of 0 to 2, n' is at least 1, and m '+ n' is 2 or 3. ]

[In General Formula (1) ′, X represents O or S. L is a single bond (L may not be present) or a divalent linking group and represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring. Ar ₁ represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring. ]

[In General Formula (2), X and Y represent O, S, or NR (R represents a hydrogen atom or a substituent), and A1 and A2 represent a hydrogen atom or a substituent. L ₁ and L ₂ represent a divalent linking group, n represents an integer of 1 or more, n1 and n2 represent an integer of 0 or more, and n3 and n4 represent 0 or 1. However, n1 + n2 ≧ 2. ] The organic electroluminescence device according to claim 1, wherein the host compound is represented by the following general formula (5).

[In General Formula (5), X represents O or S. L is a single bond (L may not be present) or a divalent linking group and represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring. Ar ₁ represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring. ] The organic electroluminescence device according to claim 1, wherein the host compound is represented by any one of the following general formulas (6) to (9).

[In General Formulas (6) to (9), X represents O or S. Ar ₁ represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring. ] The organic electroluminescence device according to claim 1, wherein the host compound is represented by the general formula (10) or (11).

[In General Formulas (10) and (11), X represents O or S. L is a single bond (L may not be present) or a divalent linking group and represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring. ]   The relationship between the highest occupied molecular orbital HOMO (HT1) of the first hole transporting material used in the first hole transporting layer and the highest occupied molecular orbital HOMO (HT2) of the second hole transporting material is −0. 5 eV <HOMO (HT2) −HOMO (HT1) <− 0.1 eV is satisfied, The organic electroluminescent element according to any one of claims 1 to 4 characterized by the above-mentioned. An electron transport layer is provided between the light emitting layer and the cathode;
6. The organic electroluminescence device according to claim 1, wherein the electron transport material used for the electron transport layer is an azacarbazole derivative or an 8-quinolinol derivative. The organic electro according to claim 1, wherein R ₁ and R ₂ in the general formula (1-1) are both an alkyl group or a cycloalkyl group having 2 or more carbon atoms. Luminescence element. The organic electroluminescence according to claim 1, wherein at least one of R ₁ and R ₂ in the general formula (1-1) is a branched alkyl group having 3 or more carbon atoms. element. 9. The organic electroluminescence device according to claim 1, wherein R ₁ and R ₂ in the general formula (1-1) are both branched alkyl groups having 3 or more carbon atoms.   Ar in said general formula (1-1) is a benzene ring, The organic electroluminescent element as described in any one of Claims 1-9 characterized by the above-mentioned.   The organic electroluminescence device according to any one of claims 1 to 10, wherein X in the general formula (1) 'is an oxygen atom.   X in the said General formula (2) is NR, Y is O, S, or NR, The organic electroluminescent element as described in any one of Claims 1-11 characterized by the above-mentioned.   The organic electroluminescent element according to claim 1, wherein the emission color is white.

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