JP2013197323A - Organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element which has high efficiency and a long service life and is driven at a low voltage.SOLUTION: A light-emitting layer contains a blue phosphorescent dopant having an emission maximum wavelength of 480 nm or less. A host and a hole-blocking layer comprise a compound of general formula (1), and an electron transport layer comprises a compound of general formula (2).

Description

  The present invention relates to an organic electroluminescence element.

  An organic electroluminescence element (organic EL element) has a configuration in which a light emitting layer containing a compound that emits light is sandwiched between a cathode and an anode. By applying an electric field, holes injected from the anode and the cathode are injected. This is a light emitting device utilizing excitons (excitons) by recombining the electrons in the light emitting layer and utilizing light emission (fluorescence / phosphorescence) when the excitons are deactivated. Since it is an all-solid-state device 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, It is expected to be used for next generation flat display and lighting.

As for the development of organic EL elements for practical use, Princeton University has reported organic EL elements that use phosphorescence emission from excited triplets (for example, see Non-Patent Document 1), and phosphorescence at room temperature. Research on materials exhibiting the above has become active (see, for example, Patent Document 1 and Non-Patent Document 2).
When excited triplets are used, the upper limit of internal quantum efficiency is 100%, so in principle the luminous efficiency is four times that of excited singlets, and the performance is almost the same as that of cold cathode tubes. It can be applied to and attracts attention.

On the other hand, it has been proposed to provide a hole blocking layer that restricts the movement of holes from the light emitting layer between the light emitting layer and the cathode in order to improve the light emission luminance and the issuance life of the organic EL element. With this hole blocking layer, holes can be efficiently accumulated in the light emitting layer, and the recombination probability with electrons can be improved, so that high efficiency of light emission can be achieved.
In the organic EL element, as a technique related to a hole blocking layer using a phosphorescent light emitting material (phosphorescent dopant), for example, a technique using a triphenylene derivative in the hole blocking layer, or a specific carbazole derivative as a host compound in the light emitting layer And a technique using a styryl derivative, a triazole derivative, a phenanthroline derivative or the like in the hole blocking layer is disclosed (for example, see Patent Documents 2 and 3).

  Using these techniques, efficiency and lifetime are improved to some extent, but when blue phosphorescent dopants are used, the exciton produced by the blue phosphorescent dopants because the blue phosphorescent dopant has a high triplet energy. Leaked to other layers and extinguished, resulting in a decrease in efficiency and life, and the performance was insufficient.

  In addition, a technique is disclosed in which an anthracene derivative is used for the hole blocking layer and a triplet energy difference between the light emitting material and the hole blocking material and a triplet energy difference between the hole blocking material and the electron transport material are defined (patent) Reference 4). This document also describes a configuration using a blue phosphorescent dopant containing platinum, but the efficiency and lifetime are not yet satisfactory, and the drive voltage is still high, so further improvement has been desired.

US Pat. No. 6,097,147 JP 2005-259472 A JP 2009-267340 A JP 2011-119721 A

M.M. A. Baldo et al. , Nature, 395, 151-154 (1998) M.M. A. Baldo et al. , Nature, 403, 17, 750-753 (2000)

  Accordingly, a main object of the present invention is to provide an organic electroluminescent device using a blue phosphorescent dopant and having high efficiency, long life, and low voltage driving.

  As a result of intensive studies to achieve the above object, the present inventors have found that in an organic electroluminescence device having at least a light emitting layer, a hole blocking layer, and an electron transporting layer, the host compound contained in the light emitting layer and the host compound. By using a compound having the same specific structure as the hole blocking layer and using a compound having a specific structure in which the absolute value of the LUMO energy level is defined for the electron transport layer, the object of the present invention can be achieved. Is found.

So, according to the present invention,
In an organic electroluminescence device having at least a light emitting layer, a hole blocking layer, and an electron transport layer between an anode and a cathode,
The light emitting layer has a host compound and a blue phosphorescent dopant having an emission maximum wavelength of 480 nm or less,
The host compound of the light emitting layer and the constituent material of the hole blocking layer are composed of a compound represented by the general formula (1),
There is provided an organic electroluminescence device characterized in that the constituent material of the electron transport layer is composed of a compound represented by the general formula (2), and the LUMO energy level has an absolute value of 1.20 eV or more. The

  In the formula (1), “X” represents NR ′, O, S, CR′R ″ or SiR′R ″, R ′ and R ″ each represents a hydrogen atom or a substituent, and “Ar” represents an aromatic Represents a ring, and n represents an integer of 0 to 8.

In formula (2), “E _{1 to} E ₁₆ ” each represents C (R) or N, and at least one of “E _{1 to} E ₁₆ ” is N. R represents a hydrogen atom or a substituent.

  ADVANTAGE OF THE INVENTION According to this invention, the organic electroluminescent element which is a high efficiency, long life, and low voltage drive using a blue phosphorescence dopant can be provided.

It is a perspective view which shows schematic structure of an illuminating device. It is sectional drawing which shows schematic structure of an illuminating device.

Hereinafter, although preferable embodiment of this invention is described, this invention is not limited to these. In the present invention, “to” means that the numerical values described before and after are included as the lower limit value and the upper limit value.
In the present invention, the absolute value of the LUMO energy level is calculated by Gaussian 03 (Gaussian 03, Revision D02, MJ Frisch, et al, Gaussian, Inc., Wallingford, software for molecular orbital calculation manufactured by Gaussian, USA. CT, 2004.), B3LYP / 6-31G * as a keyword, and a value calculated by optimizing the structure of the target molecular structure (eV unit converted 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.

<< 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 / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode (ii) Anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / Electron injection layer / cathode (iii) Anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / first electron transport layer / second electron transport layer / electron injection layer / cathode (iv) Anode / Hole injection layer / hole transport layer / first light emitting layer / second light emitting layer / hole blocking layer / first electron transport layer / second electron transport layer / electron injection layer / cathode

<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 within the layer of the light emitting layer. May be the interface between the light emitting layer and the adjacent layer.

(1) Host compound The host compound contained in the light emitting layer of the organic EL device of the present invention is preferably a compound having a phosphorescence quantum yield of phosphorescence emission at room temperature (25 ° C) of less than 0.1. More preferred is a compound having a phosphorescence quantum yield of less than 0.01.

The light-emitting host compound used in the present invention is not particularly limited in terms of structure, but typically, a carbazole derivative, a triarylamine derivative, an aromatic borane derivative, a nitrogen-containing heterocyclic compound, a thiophene derivative, a furan derivative, Those having a basic skeleton such as an oligoarylene compound, or a carboline derivative or a diazacarbazole derivative (here, a diazacarbazole derivative is a compound in which at least one carbon atom of a hydrocarbon ring constituting a carboline ring of a carboline derivative is nitrogen Represents an atom substituted with an atom.) And the like.
As the host compound, one type of compound may be used alone, or a plurality of types of compounds may be used in combination.

  As a luminescent host compound used for the light emitting layer concerning this invention, the compound represented by following General formula (1) is preferable.

  In the formula (1), “X” represents NR ′, O, S, CR′R ″ or SiR′R ″, R ′ and R ″ each represents a hydrogen atom or a substituent, and “Ar” represents an aromatic Represents a ring, and n represents an integer of 0 to 8.

In the general formula (1), the substituents represented by R ′ and R ″ in “X” are each 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.), cycloalkyl group (for example, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (for example, vinyl group, allyl group, 1-propenyl group, etc.) , 2-butenyl group, 1,3-butadienyl group, 2-pentenyl group, isopropenyl group, etc.), alkynyl group (for example, ethynyl group, propargyl group, etc.), aromatic hydrocarbon group (aromatic carbocyclic group, aryl) For example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, xylyl group, Til group, anthryl group, azulenyl group, acenaphthenyl group, fluorenyl group, phenanthryl group, indenyl group, pyrenyl group, biphenylyl group, etc.), aromatic heterocyclic group (for example, furyl group, thienyl group, pyridyl group, pyridazinyl group, pyrimidinyl) Group, pyrazinyl group, triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, carbazolyl group, carbolinyl group, diazacarbazolyl group (one of the carbon atoms constituting the carboline ring of the carbolinyl group is nitrogen Phthalazinyl group, etc.), heterocyclic group (eg, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxy group (eg, methoxy group, ethoxy group, propyloxy group, pentyl) Oxy group, f Siloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (eg, cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), alkylthio group (eg, methylthio group) Group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.), cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.), arylthio group (eg, phenylthio group, naphthylthio group, etc.) , Alkoxycarbonyl groups (for example, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxy Carbonyl group (for example, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group) Octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexyl) Carbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, Lysylcarbonyl group etc.), acyloxy group (eg acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group etc.), amide group (eg methylcarbonylamino) Group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthyl Carbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylamino group) Carbonyl 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, ethylureido 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, phenyl Sulfinyl 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.), aryl A sulfonyl group or heteroarylsulfonyl group (for example, phenylsulfonyl 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, etc.), 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 and the like.
These substituents may be further substituted with the above substituents. In addition, a plurality of these substituents may be bonded to each other to form a ring.

  In the general formula (1), preferred “X” is NR ′ or O, and R ′ is particularly preferably an aromatic hydrocarbon group or an aromatic heterocyclic group.

In the general formula (1), examples of the aromatic ring represented by “Ar” include an aromatic hydrocarbon ring and an aromatic heterocyclic ring. The aromatic ring may be a single ring or a condensed ring, and may be unsubstituted or may have a substituent as described later.
In the general formula (1), the aromatic hydrocarbon ring represented by “Ar” includes a 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, anthraanthrene ring and the like. These rings may further have a substituent.
In the general formula (1), examples of the aromatic heterocycle represented by “Ar” include a furan ring, dibenzofuran ring, thiophene ring, oxazole ring, pyrrole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, Triazine ring, benzimidazole ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, indazole ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, cinnoline ring , Quinoline ring, isoquinoline ring, phthalazine ring, naphthyridine ring, carbazole ring, carboline ring, diazacarbazole ring (indicates a ring in which one of the carbon atoms of the hydrocarbon ring constituting the carboline ring is further substituted with a nitrogen atom) Etc. These rings may further have a substituent.
Among the above, in the general formula (1), the aromatic ring represented by “Ar” is preferably a carbazole ring, carboline ring, dibenzofuran ring, or benzene ring, and particularly preferably used is a carbazole ring. A carboline ring and a benzene ring. Among these, a benzene ring having a substituent is preferable, and a benzene ring having a carbazolyl group is particularly preferable.
In the general formula (1), the aromatic ring represented by “Ar” is preferably a condensed ring having 3 or more rings, as shown below, and is an aromatic carbonization in which 3 or more rings are condensed. Specific examples of the hydrogen condensed ring include naphthacene ring, anthracene ring, tetracene ring, pentacene ring, hexacene ring, phenanthrene ring, pyrene ring, benzopyrene ring, benzoazulene ring, chrysene ring, benzochrysene ring, acenaphthene ring, acenaphthylene ring , Triphenylene ring, coronene ring, benzocoronene ring, hexabenzocoronene ring, fluorene ring, benzofluorene ring, fluoranthene ring, perylene ring, naphthoperylene ring, pentabenzoperylene ring, benzoperylene ring, pentaphen ring, picene ring, pyranthrene ring, coronene Ring, naphtho-colonene ring, ovalene ring, anne Raantoren ring and the like. In addition, these rings may further have a substituent.
Specific examples of the aromatic heterocycle condensed with three or more rings include an acridine ring, a benzoquinoline ring, a carbazole ring, a carboline ring, a phenazine ring, a phenanthridine ring, a phenanthroline ring, a carboline ring, a cyclazine ring, Kindin ring, tepenidine ring, quinindrin ring, triphenodithiazine ring, triphenodioxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, diazacarbazole ring (any one of the carbon atoms constituting the carboline ring is a nitrogen atom Phenanthroline ring, dibenzofuran ring, dibenzothiophene ring, naphthofuran ring, naphthothiophene ring, benzodifuran ring, benzodithiophene ring, naphthodifuran ring, naphthodithiophene ring, anthrafuran ring, anthradifuran ring, A Tiger thiophene ring, anthradithiophene ring, thianthrene ring, phenoxathiin ring, such as thio fan Tren ring (naphthaldehyde thiophene ring), and the like. In addition, these rings may further have a substituent.
Here, in the general formula (1), the substituent that the aromatic ring represented by “Ar” may have is the same as the substituent represented by R ′ and R ″.

  In the general formula (1), n represents an integer of 0 to 8, preferably 0 to 2, and particularly preferably 1 or 2 when “X” is O or S. .

  Specific examples of the luminescent host compound represented by the general formula (1) are shown below, but are not limited thereto.

The host compound 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 (evaporation polymerizable light emitting host). .
As the host compound, a compound that has a hole transporting ability and an electron transporting ability, prevents the emission of light from being increased in wavelength, and has a high Tg (glass transition temperature) is preferable.
In the present invention, at least two light emitting layers are provided. The host compound may be different for each light emitting layer, but the same compound can provide excellent driving life characteristics and chromaticity stability. To preferred.
In addition, it is preferable that the host compound has a lowest excited triplet energy (T1) larger than 2.7 eV because higher luminous efficiency can be obtained. The lowest excited triplet energy as used in the present invention refers to the peak energy of an emission band corresponding to the transition between the lowest vibrational bands of a phosphorescence emission spectrum observed at a liquid nitrogen temperature after dissolving a host compound in a solvent.
In the present invention, a compound having a glass transition point of 90 ° C. or higher is preferable, and a compound having a glass transition temperature of 130 ° C. or higher is preferable because excellent driving life characteristics can be obtained.
Here, the glass transition point (Tg) is a value obtained by a method based on JIS-K-7121 using DSC (Differential Scanning Colorimetry).
In the organic EL device of the present invention, since the host material is responsible for carrier transport, a material having carrier transport capability is preferable. Carrier mobility is used as a physical property representing carrier transport ability, but the carrier mobility of an organic material generally depends on the electric field strength. Since a material having a high electric field strength dependency easily breaks the balance of hole and electron injection / transport, it is preferable to use a material having a low electric field strength dependency of mobility for the intermediate layer material and the host material.

(2) Phosphorescent dopant The phosphorescent dopant according to the present invention is a compound in which light emission from an excited triplet is observed. Specifically, the phosphorescent dopant is a compound that emits phosphorescence at room temperature (25 ° C.). Although the photon yield is defined as a compound having a photon yield of 0.01 or more at 25 ° C., the preferred phosphorescence quantum yield is 0.1 or more.
The phosphorescence quantum yield can be measured by the method described in Spectra 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 light emission of the phosphorescent dopant in principle. One is the recombination of carriers on the light emitting host to which carriers are transported to generate an excited state of the light emitting host, and this energy is transferred to the phosphorescent dopant. Energy transfer type to obtain light emission from the phosphorescent dopant, the other is that the phosphorescent dopant becomes a carrier trap, carrier recombination occurs on the phosphorescent dopant, and light emission from the phosphorescent dopant is obtained Although it is a carrier trap type, 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 light emitting host.

  In the present invention, the blue phosphorescent dopant having an emission maximum wavelength of less than 480 nm preferably has at least one partial structure selected from general formulas (3) to (5).

  In formula (3), “Ra” represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group, “Rb” and “Rc” each represents a hydrogen atom or a substituent, and “A1” represents an aromatic group. It represents a residue necessary for forming a ring or an aromatic heterocycle, and “M” represents Ir or Pt.

In the formula (4), “Ra” represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group, and “Rb”, “Rc”, “Rb ₁ ” and “Rc ₁ ” are each a hydrogen atom or a substituent. Represents a group, “A1” represents a residue necessary to form an aromatic ring or an aromatic heterocycle, and “M” represents Ir or Pt.

  In formula (5), “Ra” represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group, “Rb” and “Rc” each represents a hydrogen atom or a substituent, and “A1” represents an aromatic group. It represents a residue necessary for forming a ring or an aromatic heterocycle, and “M” represents Ir or Pt.

  In the general formulas (3) to (5), “Ra” represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group, and the aliphatic group represented by “Ra” includes an alkyl group (for example, Methyl group, ethyl group, propyl group, butyl group, pentyl group, isopentyl group, 2-ethyl-hexyl group, octyl group, undecyl group, dodecyl group, tetradecyl group), cycloalkyl group (for example, cyclopentyl group, cyclohexyl group) Examples of the aromatic group include a phenyl group, tolyl group, azulenyl group, anthranyl group, phenanthryl group, pyrenyl group, chrysenyl group, naphthacenyl group, o-terphenyl group, m-terphenyl group, p- Examples include terphenyl group, acenaphthenyl group, coronenyl group, fluorenyl group, perylenyl group, and the like. Each of which may have a substituent. Examples of the heterocyclic group include pyrrolyl, indolyl, furyl, thienyl, imidazolyl, pyrazolyl, indolizinyl, quinolinyl, carbazolyl, indolinyl, thiazolyl, pyridyl, pyridazinyl, thiadiazinyl, An oxadiazolyl group, a benzoquinolinyl group, a thiadiazolyl group, a pyrrolothiazolyl group, a pyrrolopyridazinyl group, a tetrazolyl group, an oxazolyl group, a chromanyl group, and the like can be mentioned, and these groups each may have a substituent.

In the general formulas (3) to (5), examples of the substituent represented by “Rb”, “Rc”, “Rb ₁ ”, “Rc ₁ ” include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group) Group, tert-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), cycloalkyl group (for example, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (for example, vinyl Group, allyl group, etc.), alkynyl group (eg, ethynyl group, propargyl group, etc.), aryl group (eg, phenyl group, naphthyl group, etc.), aromatic heterocyclic group (eg, furyl group, thienyl group, pyridyl group, etc.) Pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, imidazolyl, pyrazolyl, thiazolyl Group, quinazolinyl group, phthalazinyl group, etc.), heterocyclic group (eg, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxyl group (eg, methoxy group, ethoxy group, propyloxy group, pentyloxy group, Hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxyl group (eg, cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), alkylthio group (eg, Methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.), cycloalkylthio group (for example, cyclopentylthio group, cyclohexylthio group, etc.), arylthio group (for example, Phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxy) Carbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecyl) Aminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, Til 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, dimethylcarbonyl) Amino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octyl Carbonylamino 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, -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) Group), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group (phenylsulfonyl 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 etc.), fluorinated hydrocarbon group (for example, Fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group, etc.), cyano group, nitro group, hydroxyl group, mercapto group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group) , Phenyldiethylsilyl group, etc.). These substituents may be further substituted with the above substituents.

  In the general formulas (3) to (5), “A1” represents a residue necessary for forming an aromatic ring or an aromatic heterocyclic ring, and examples of the aromatic ring include a benzene ring, a biphenyl ring, a 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, fluoran Tren ring, naphthacene ring, pentacene ring, perylene ring, pentaphen ring, picene ring, pyrene ring, pyranthrene ring, anthraanthrene ring, and the like. As the aromatic heterocyclic ring, furan ring, thiophene ring, pyridine ring, Pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, benzimidazole ring, oxadiazole ring, triazol Ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, carbazole ring, carboline ring, diazacarbazole ring (composing carboline ring) And a hydrocarbon ring in which one of the carbon atoms of the hydrocarbon ring is further substituted with a nitrogen atom).

The structures of the general formulas (3) to (5) are partial structures, and a ligand corresponding to the valence of the central metal is necessary for the structure itself to be a light-emitting dopant of a completed structure.
Specifically, halogen (for example, fluorine atom, chlorine atom, bromine atom or iodine atom), aryl group (for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, xylyl group, biphenyl group, naphthyl group) , Anthryl group, phenanthryl group, etc.), alkyl group (for example, methyl group, ethyl group, isopropyl group, hydroxyethyl group, methoxymethyl group, trifluoromethyl group, t-butyl group, etc.), alkyloxy group, aryloxy group , Alkylthio group, arylthio group, aromatic heterocyclic group (for example, furyl group, thienyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, carbazolyl group , Carbolinyl group, phthalazinyl group ), The general formula (3) to such (5) include partial structure excluding the metal.
In the general formulas (3) to (5), “M” represents Ir or Pt, and Ir is particularly preferable.
A tris body having a completed structure with three identical partial structures represented by the general formulas (3) to (5) is preferable.

  Hereinafter, although the compound which has the partial structure of General formula (3)-(5) of the phosphorescence dopant concerning this invention is illustrated, it is not limited to these.

In addition, the light emitting material of the present invention can be applied to an organic EL element that emits substantially white light as a lighting device. In the present invention, in order to obtain white light emission, the light emitting layer is preferably composed of at least two layers, and a plurality of light emitting colors can be simultaneously emitted by a plurality of light emitting materials of the light emitting layer 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 emission maximum wavelengths utilizing the relationship between complementary colors such as blue and yellow. You may have done.

  Although the specific example of the compound used as a multicolor phosphorescence dopant other than blue is shown below, it is not limited to these. These compounds are described, for example, in Inorg. Chem. 40, 1704-1711, and the like.

《Hole blocking layer》
The hole blocking layer has a function of an electron transport layer in a broad sense, and is made of a material that has a function of transporting electrons and has a very small ability to transport holes, and blocks holes while transporting electrons. By doing so, the recombination probability of electrons and holes can be improved.

  In the present invention, in order to obtain white light emission, a light emitting layer having a plurality of light emitting layers having different emission colors and having a blue phosphorescent dopant having an emission maximum wavelength of 480 nm or less is the most cathode among all the light emitting layers. In such a case, a hole blocking layer is provided adjacent to the cathode side of the light emitting layer having a blue phosphorescent dopant having an emission maximum wavelength of 480 nm or less.

The hole blocking layer in the present invention is characterized by comprising a compound represented by the same general formula (1) as the host compound.
The host compound and the hole blocking layer may be the same or different within the range of the general formula (1), but are preferably the same.
In addition, the thickness of the hole blocking layer according to the present invention is preferably 1 nm to 10 nm.

《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons, and is characterized by being a compound represented by the general formula (2) in the present invention.
Furthermore, the absolute value of the energy level of LUMO (lowest unoccupied molecular orbital) is preferably 1.20 eV or more, more preferably 1.3 eV to 1.6 eV.
As described above, the absolute value of the energy level of LUMO is Gaussian 03, a molecular orbital calculation software manufactured by Gaussian, USA, and B3LYP / 6-31G * is used as a keyword. The value is calculated by performing optimization.

In formula (2), “E _{1 to} E ₁₆ ” each represents C (R) or N, and at least one of “E _{1 to} E ₁₆ ” is N. R represents a hydrogen atom or a substituent.

In the general formula (2), the substituent represented by R is an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group). 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.), Aromatic hydrocarbon group (also called aromatic carbocyclic group, aryl group, etc., for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, xylyl group, naphthyl group, anthryl group, azulenyl group, acenaphthenyl group, fluorenyl group Group, phenanthryl group, indenyl group, pyrenyl group, biphenyl Group), aromatic heterocyclic group (for example, furyl group, thienyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, carbazolyl group, carbolinyl group) , A diazacarbazolyl group (indicating that one of the carbon atoms constituting the carboline ring of the carbolinyl group is replaced by a nitrogen atom), a phthalazinyl group, etc.), a heterocyclic group (eg, pyrrolidyl group, imidazolidyl group) , Morpholyl group, oxazolidyl group, etc.), alkoxy group (for example, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (for example, cyclopentyloxy group) Group, cyclohexylo Si group etc.), aryloxy group (eg phenoxy group, naphthyloxy group etc.), alkylthio group (eg methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio 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, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxy) Carbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group) Group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2- Pyridylaminosulfonyl group, etc.), acyl groups (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, octyl group) Rucarbonyloxy group, dodecylcarbonyloxy 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-ethylhexyla Nocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido 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) Group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (for example, methylsulfonyl group, Acetylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group or heteroarylsulfonyl group (for example, phenylsulfonyl 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, piperidyl group ( Piperidinyl group), 2,2,6,6-tetramethylpiperidinyl group, etc.), halogen atom (eg fluorine atom, chlorine atom, bromine atom etc.), fluorinated hydrocarbon group (eg fluoromethyl group) The trifle Romethyl 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.) ), Phosphate group (for example, dihexyl phosphoryl group), phosphite group (for example, diphenylphosphinyl group), phosphono group and the like.
These substituents may be further substituted with the above substituents. In addition, a plurality of these substituents may be bonded to each other to form a ring.

  Specific examples of the compound represented by the general formula (2) and the absolute value of the LUMO energy level of each compound are shown below, but are not limited thereto.

  In the present invention, the electron transport layer is composed of two layers, a first electron transport layer and a second electron transport layer, and the first electron transport layer is disposed adjacent to the hole blocking layer, Is preferably composed of a compound represented by the general formula (2).

  The compound used in the second electron transport layer can be selected from any conventionally known compounds. For example, nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimides, Examples include oleylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives, and the like. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, or a quinoxaline derivative having a quinoxaline ring known as an electron-withdrawing group can also be used as an electron transport material. 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, 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 metal of these metal complexes is 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.
In addition, the distyrylpyrazine derivative exemplified as the material of the light emitting layer can also be used as an electron transport material, and an inorganic semiconductor such as n-type-Si, n-type-SiC, etc. as in the case of the hole injection layer and hole transport layer Can also be used as an electron transporting material.

  Further, an electron transport layer having a high n property doped with impurities may be used for the second electron transport layer. 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.

In the present invention, it is preferable to use an electron transport layer having such a high n property because an element with lower power consumption can be manufactured.
The film thickness of the first electron transport layer is preferably 1 nm to 10 nm.
The film thickness of the second electron transport layer is preferably 5 nm to 200 nm.

  In the present invention, the compound LUMO (HB) of the hole blocking layer, the LUMO (ET-1) of the compound of the first electron transport layer, the LUMO (ET-2) of the compound of the second electron transport layer, It is preferable to satisfy the conditional expressions (i) and (ii) in order to reduce the injection barrier at the layer interface when transporting electrons.

0 ≦ | LUMO (ET-1) | − | LUMO (HB) | <0.4 (i)
0 ≦ | LUMO (ET-2) |-| LUMO (ET-1) | <0.4 (ii)

《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.
The hole transport layer can be provided as a single layer or a plurality of layers.

The hole transport material has any one of hole injection or transport and electron barrier properties, and may be either organic or inorganic.
Examples of hole transport materials include 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, 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 ' Di (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 described in US Pat. No. 5,061,569 Having a condensed aromatic ring of, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-3 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 8688 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 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, it is preferable to use these materials because a light-emitting element with higher efficiency can be obtained.

Although there is no restriction | limiting in particular about the layer thickness of a positive hole transport layer, Usually, 5 nm-about 5 micrometers, Preferably it is the range of 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.A. 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.

《Electron blocking layer》
The electron blocking layer has the function of a hole transport layer in a broad sense, and is made of a material that has a function of transporting holes but has a very small ability to transport electrons, and blocks electrons while transporting holes. By doing so, the probability of recombination 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 thickness of the electron blocking layer according to the present invention is preferably 3 nm to 100 nm, and more preferably 5 nm to 30 nm.

<< Injection layer: hole injection layer, electron injection layer >>

An injection layer is a layer provided between an electrode and an organic compound layer in order to lower drive voltage and improve light emission luminance. “The organic EL element and its forefront of industrialization (November 30, 1998, NTS Corporation) Issue) ”, Chapter 2,“ Electrode Materials ”(pages 123 to 166) in detail, and has a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer). .
The injection layer is provided as necessary, and may be present 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 as described above.

The details of the 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, a phthalocyanine buffer represented by copper phthalocyanine And an oxide buffer layer typified by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene.
The details of the electron injection layer are also described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like, and specifically, metals represented by strontium, aluminum and the like. Examples thereof include a buffer layer, an alkali metal compound buffer layer typified by lithium fluoride, an alkaline earth metal compound buffer layer typified by magnesium fluoride, and an oxide buffer layer typified by aluminum oxide.
The 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.

"anode"
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound and 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 to 1000 nm, preferably 10 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, a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function value than this from the point of durability against electron injection and oxidation, 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 the 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 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.
After producing the above metal with a film thickness of 1 to 20 nm on the cathode, a transparent or semi-transparent cathode can be produced by producing the conductive transparent material mentioned in the description of the anode thereon. By application, 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.
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, polysulfone , Polyetherimide, polyether ketone imide, polyamide, fluorine resin, nylon, polymethyl methacrylate, acrylic or polyarylates, and cycloolefin resins such as ARTON (manufactured by JSR) or APEL (manufactured by Mitsui Chemicals).

An inorganic or organic film or a hybrid film of both may be formed on the surface of the resin film, and a barrier film having a water vapor permeability of 0.01 g / m ² / day · atm or less is preferable. Further, it is preferably a high barrier film having an oxygen permeability of 10 ⁻³ g / m ² / day or less and a water vapor permeability of 10 ⁻⁵ g / m ² / day or less.
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, the vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma weight A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, and 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, ceramic substrates, and the like.

The external extraction quantum 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 sent 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 may be used in combination. 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.

<Sealing>
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.
Further, the polymer film oxygen permeability measured by the method based on JIS K 7126-1987 is ^{1 × 10 -3 ml / m 2} / 24h or less, as measured by the method based on JIS K 7129-1992, water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)%) is preferably that of ^{1 × 10 -3 g / (m} 2 / 24h) 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 liquid mixing), such as an epoxy type, can be mentioned. Moreover, 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 infiltration 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 method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma A polymerization 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 can also be used. Moreover, a hygroscopic compound can also be enclosed inside.
Examples of the hygroscopic compound include metal oxides (eg, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide), sulfates (eg, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate). Etc.), metal halides (for example, calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide, etc.), perchloric acids (for example, perchloric acid) Barium, magnesium perchlorate, etc.), and anhydrous salts are preferably used in sulfates, metal halides and perchloric acids.

《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, etc. used for the sealing can be used. It is preferable to use a film.

《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 side surface direction of the element.

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 desirably 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 device 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 combined with a so-called condensing sheet, for example, with respect to a specific direction, for example, the device light emitting surface. 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 two-dimensionally arranged on the light extraction side of the substrate. One side is preferably 10 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, Sumitomo 3M brightness enhancement film (BEF) can be used. As the shape of the prism sheet, for example, the base material may be formed with 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.

<< Method for producing organic EL element >>
As an example of the method for producing the organic EL device of the present invention, a method for producing an organic EL device comprising an anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode will be described.

  First, a desired electrode material, for example, a thin film made of an anode material is formed on a suitable support substrate by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably 10 nm to 200 nm. Make it.

Next, an organic compound thin film of a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, and an electron transport layer, which are organic EL element materials, is formed thereon.
As a method of thinning the organic compound thin film, a vapor deposition method, a wet process (spin coating method, casting method, ink jet method, printing method, LB method (Langmuir-Blodget method), spray method, printing method, slot type coater. However, the vacuum deposition method, spin coating method, ink jet method, printing method, and slot type coater method are particularly preferred from the standpoint that a homogeneous film can be easily obtained and pinholes are hardly formed. Further, different film forming methods may be applied for each layer, but the light emitting layer of the present invention preferably has at least two layers in order to obtain white light emission, and in that case, the film may be formed by a wet process. Since it is difficult, film formation by a vacuum evaporation method is preferable.
When a vapor deposition method is employed for film formation, the vapor deposition conditions vary depending on the type of compound used, but generally a boat heating temperature of 50 ° C. to 450 ° C., a vacuum degree of 10 ⁻⁶ Pa to 10 ⁻² Pa, and a vapor deposition rate of 0. It is desirable to select appropriately within the range of 01 nm / second to 50 nm / second, substrate temperature −50 ° C. to 300 ° C., film thickness (layer thickness) 0.1 nm to 5 μm, preferably 5 nm to 200 nm.
In the hole blocking layer, it is desirable to appropriately select the film thickness in the range of 1 nm to 10 nm.
Moreover, when an electron carrying layer consists of a 1st electron carrying layer and a 2nd electron carrying layer, it is desirable to select suitably in the range of 1 nm-10 nm as a film thickness of a 1st electron carrying layer.

  After these layers are formed, a thin film made of a cathode material is formed thereon by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably in the range of 50 nm to 200 nm, and a cathode is provided. Thus, a desired organic EL element can be obtained.

The organic EL device is preferably manufactured from the hole injection layer to the cathode consistently by one vacuum drawing, but may be taken out halfway and subjected to different film forming methods. At that time, it is necessary to consider that the work is performed in a dry inert gas atmosphere.
Further, it is also possible to reverse the production order and produce the cathode, the electron injection layer, the electron transport layer, the hole blocking layer, the light emitting layer, the hole transport layer, the hole injection layer, and the anode 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.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

(1) Preparation of sample (1.1) Preparation of organic EL element 101 As an anode, patterning was performed on a support substrate in which ITO (indium tin oxide) was formed to a thickness of 110 nm on a glass substrate having a thickness of 0.7 mm. Then, the transparent support substrate with the ITO transparent electrode was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes. Fixed to the substrate holder of the apparatus.

Each of the deposition crucibles in the vacuum deposition apparatus was filled with the constituent material of each layer in an optimum amount for device fabrication. The evaporation crucible used was made of a resistance heating material made of molybdenum or tungsten.
Next, after reducing the vacuum to 1 × 10 ⁻⁴ Pa, the deposition crucible containing Compound HT-1 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. Next, Compound HT-2 was deposited at a deposition rate of 0.1 nm / sec to provide a 20 nm hole transport layer.
Next, the green phosphorescent dopant compound Ir-1d, the red phosphorescent dopant Ir-14d, and the host compound 1-6 are vapor-deposited so that Ir-1d has a concentration of 14% by mass and Ir-14d has a concentration of 1.8% by mass. Co-evaporation was performed so that the thickness was 10 nm at a speed of 0.1 nm / second, and a first phosphorescent layer of yellow phosphorescence having an emission maximum wavelength of 622 nm was formed. Next, the host compound 1-6 and the blue phosphorescent dopant compound D-66 were co-deposited so that the dopant compound D-66 had a concentration of 15% by mass and a thickness of 20 nm at a deposition rate of 0.1 nm / second. A second phosphorescent layer of blue phosphorescence having an emission maximum wavelength of 470 nm was formed.
Subsequently, it heated by supplying with electricity to the heating board containing BAlq, and it vapor-deposited on the light emitting layer with the vapor deposition rate of 0.1 nm / second, and formed the 5-nm-thick hole blocking layer.
Thereafter, Alq ₃ was deposited to a thickness of 35 nm to form an electron transport layer (first electron transport layer), and LiF was further formed to a thickness of 1 nm. Furthermore, aluminum 110nm was vapor-deposited and the cathode was formed.

  Next, the non-light-emitting surface of the element was covered with a glass case, and an “organic EL element 101” having the configuration shown in FIGS. 1 and 2 was produced.

FIG. 1 shows a schematic diagram of an organic EL element.
The organic EL element 101 is covered with a glass cover 120. The sealing operation with the glass cover 120 was performed in a glove box (in an atmosphere of high-purity nitrogen gas with a purity of 99.999% or more) in a nitrogen atmosphere without bringing the organic EL element 101 into contact with the atmosphere.
FIG. 2 shows a cross-sectional view of the organic EL element.
As shown in FIG. 2, a cathode 121 and an organic EL layer 122 are formed on a glass substrate 123 with a transparent electrode. The glass cover 120 is filled with nitrogen gas 124 and a water catching agent 125 is provided.

(1.2) Preparation of organic EL elements 102 to 113 In preparation of organic EL element 101, as described in Table 1, the compounds of blue phosphorescent dopant, hole blocking layer, and first electron transport layer were changed. did.
Other than that produced the organic EL elements 102-113 similarly to the production of the organic EL element 101.

(1.3) Production of Organic EL Element 114 In the organic EL element 109, the first electron transport layer was deposited so that the film thickness of ET-5 was 5 nm, and then Alq ₃ was deposited to a film thickness of 30 nm. An organic EL element 114 was produced in the same manner except that the two-electron transport layer was formed.

(1.4) Preparation of organic EL elements 115 to 118 In the organic EL element 114, as described in Table 1, the film thicknesses of the hole blocking layer, the first electron transport layer, and the second electron transport layer were changed. did.
Other than that produced the organic EL elements 115-118 similarly to the production of the organic EL element 114.

(2) Evaluation of sample The organic EL elements 101 to 118 obtained as described above were evaluated for external extraction quantum efficiency, light emission lifetime, and driving voltage as follows.
The evaluation results are shown in Table 1. In Table 1, the LUMO energy level of the first electron transport layer is expressed as an absolute value.

(2.1) External extraction quantum efficiency and driving voltage The external extraction quantum efficiency (%) and driving voltage when a constant current of ^2.5 mA / cm ² was applied to the produced organic EL element were measured. A spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing) was used for the measurement. The external extraction quantum efficiency and the driving voltage are expressed as relative values with the measured value of the organic EL element 101 as 100.

(2.2) Luminescence Life The produced organic EL element is continuously driven by applying a current with a front luminance of 4000 cd / m ² until the front luminance reaches the initial half value (2000 cd / m ² ). The time required was obtained and this was defined as the light emission lifetime. The light emission lifetime was expressed as a relative value with the measured value of the organic EL element 101 as 100.

As is clear from the results in Table 1, the organic EL elements 107 to 110 and 114 to 118 of the present invention are compared with the organic EL elements 101 to 106 and 111 to 113 of the comparative example, and the external extraction quantum efficiency and the light emission lifetime. And the driving voltage were excellent.
From this, the light emitting layer has a host compound and a blue phosphorescent dopant having an emission maximum wavelength of 480 nm or less, the host compound and the hole blocking layer are made of a compound represented by the general formula (1), and The transport layer is made of the compound represented by the general formula (2) and the absolute value of the LUMO energy level is 1.20 eV or more, which is high efficiency, long life, and low voltage drive. It turns out that it is useful for providing an organic EL element.

101 Organic EL element 120 Glass cover 121 Cathode 122 Organic EL layer 123 Glass substrate with transparent electrode 124 Nitrogen gas 125 Water replenisher

Claims (7)

In an organic electroluminescence device having at least a light emitting layer, a hole blocking layer, and an electron transport layer between an anode and a cathode,
The light emitting layer has a host compound and a blue phosphorescent dopant having an emission maximum wavelength of 480 nm or less,
The host compound of the light emitting layer and the constituent material of the hole blocking layer are composed of a compound represented by the general formula (1),
An organic electroluminescence device characterized in that the constituent material of the electron transport layer is made of a compound represented by the general formula (2), and the LUMO energy level has an absolute value of 1.20 eV or more.

[In the formula (1), “X” represents NR ′, O, S, CR′R ″ or SiR′R ″, R ′ and R ″ each represents a hydrogen atom or a substituent, and “Ar” represents Represents an aromatic ring, and n represents an integer of 0 to 8. ]

[In Formula (2), “E _{1 to} E ₁₆ ” each represents C (R) or N, and at least one of “E _{1 to} E ₁₆ ” is N. R represents a hydrogen atom or a substituent. ] The organic electroluminescent device according to claim 1,
The organic phosphor element, wherein the blue phosphorescent dopant has at least one partial structure selected from the general formulas (3) to (5).

[In formula (3), “Ra” represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group, “Rb” and “Rc” each represents a hydrogen atom or a substituent, and “A1” represents an aromatic Represents a residue necessary to form an aromatic ring or an aromatic heterocyclic ring, and “M” represents Ir or Pt. ]

[In the formula (4), “Ra” represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group, and “Rb”, “Rc”, “Rb ₁ ” and “Rc ₁ ” are each a hydrogen atom or Represents a substituent, “A1” represents a residue necessary to form an aromatic ring or an aromatic heterocycle, and “M” represents Ir or Pt. ]

[In the formula (5), “Ra” represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group, “Rb” and “Rc” each represents a hydrogen atom or a substituent, and “A1” represents an aromatic Represents a residue necessary to form an aromatic ring or an aromatic heterocyclic ring, and “M” represents Ir or Pt. ] The organic electroluminescent element according to claim 1 or 2,
The electron transport layer is composed of two layers, a first electron transport layer and a second electron transport layer, and the first electron transport layer is disposed adjacent to the hole blocking layer,
The organic electroluminescence device, wherein the first electron transport layer is made of a compound represented by the general formula (2). In the organic electroluminescent element according to claim 3,
An organic electroluminescence element, wherein the first electron transport layer has a thickness of 1 nm to 10 nm. In the organic electroluminescent element as described in any one of Claims 1-4,
An organic electroluminescence device, wherein the hole blocking layer has a thickness of 1 nm to 10 nm. In the organic electroluminescent element according to any one of claims 1 to 5,
The light emitting layer is composed of at least two layers having different emission colors, and the light emitting layer located closest to the cathode has the host compound represented by the general formula (1) and the blue phosphorescent dopant. An organic electroluminescence element. In the organic electroluminescent element according to any one of claims 1 to 6,
An organic electroluminescence device which emits white light by additive color mixing.

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