JP5998989B2 - Organic electroluminescence element, display device and lighting device - Google Patents

Description

  The present invention relates to an organic electroluminescence element, a display device, and a lighting device. More specifically, the present invention relates to an organic electroluminescence element, a display device, and a lighting device that have improved luminous efficiency and durability.

An organic electroluminescence device (hereinafter also referred to as “organic EL device”) is an organic thin film layer (single layer portion or multilayer portion) having a thickness of only about 0.1 μm containing an organic light-emitting substance between an anode and a cathode. ) Is a thin film type all solid state device.
When a relatively low voltage of about 2 to 20 V is applied to such an organic EL element, electrons are injected from the cathode and holes are injected from the anode into the organic thin film layer. The electrons and holes recombine in the light-emitting layer (organic light-emitting substance-containing layer) to generate excitons (excitons), and emission (fluorescence / phosphorescence) is obtained when the excitons are deactivated. Is a technology that is expected as the next generation flat display and lighting.

  In addition, recently discovered organic EL devices that use phosphorescence can realize a luminous efficiency that is approximately four times that of previous methods that use fluorescence. Research and development of light-emitting element layer configurations and electrodes are performed all over the world.

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

Therefore, in recent years, multilayer stacked devices having a hole transporting layer located on the anode side of the light emitting layer and an electron transporting layer located on the cathode side of the light emitting layer in a form adjacent to the light emitting layer are well known. It has been. For the light emitting layer, a mixed layer using a phosphorescent compound as a light emitting dopant and a host compound is often used. As this phosphorescent compound, organometallic complexes, especially organic iridium complexes, have been widely used.
In recent years, research aimed at developing a new phosphorescent material using a highly versatile metal from the viewpoint of rarity has been promoted. For example, a pincer-type palladium complex is known (for example, Non-Patent Document 1). reference.).
However, the pincer-type palladium complex has insufficient luminescence intensity at room temperature and stability over time. Therefore, the light emission efficiency and durability of the organic EL element containing such a pincer type palladium complex were not sufficient.

Michinori Akaiwa, Takaki Kanbara, Hiroki Fukumoto, and Takakazu Yamamoto, `` Luminescent Palladium Complexes Containing Thioamide-Based SCS Pincer Ligands '', J. Organomet. Chem., 690, 2005, p4192-4196

  The present invention has been made in view of the above-described problems and situations, and a problem to be solved is to provide an organic electroluminescence element, a display device, and a lighting device that have improved luminous efficiency and durability.

In order to solve the above-mentioned problems, the present inventor made the organic EL element contain a palladium complex represented by the following general formula ( 2 ) in the process of studying the cause of the above-mentioned problem, thereby adding organic compounds. The present inventors have found that the luminous efficiency and durability of an EL element can be improved, and have reached the present invention.
That is, the said subject which concerns on this invention is solved by the following means.
1. An organic electroluminescence element having at least an anode, a cathode, and a light emitting layer, wherein the light emitting layer contains a palladium complex having a structure represented by the following general formula ( 2 ) .

〔式中、Ｐｄは、配位数が６、かつ４価のパラジウム原子を表す。環Ａは、Ｙ_１と炭素原子とともに形成される芳香族環又は非芳香族環を表し、さらにハロゲン原子、ニトロ基、置換若しくは無置換のアリール基、置換若しくは無置換のヘテロアリール基、ジ置換アミノ基又は炭素原子数１〜２０の直鎖状若しくは分岐鎖状のアルキル基を有していてもよい。これらの置換基は、互いに結合して環を形成してもよい。Ｙ_１は、炭素原子又は窒素原子を表す。Ｘ_１〜Ｘ_４は、Ｐｄに配位したカルベン炭素原子とともに５員の芳香族複素環又は非芳香族複素環を形成する原子群であり、それぞれ、炭素原子、Ｃ−Ｒ_１、窒素原子、Ｎ−Ｒ_１、酸素原子又は硫黄原子を表し、少なくとも一つは窒素原子又はＮ−Ｒ_１を表す。Ｒ_１は、水素原子又は置換基を表す。Ｌ_１は、Ｐｄに配位する２座配位子を表す。ｐ及びｑは、１以上の整数を表し、ｐ＋ｑ＝３の関係式を満たす。ｑが２のとき、二つのＬ_１は互いに異なっている。〕

[Wherein, Pd represents a tetravalent palladium atom having a coordination number of 6; Ring A represents an aromatic ring or a non-aromatic ring formed with Y ₁ and a carbon atom, and further represents a halogen atom, a nitro group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, or a disubstituted ring You may have an amino group or a C1-C20 linear or branched alkyl group. These substituents may be bonded to each other to form a ring. Y ₁ represents a carbon atom or a nitrogen atom. X _{1 to} X ₄ are atomic groups that form a 5-membered aromatic heterocyclic ring or a non-aromatic heterocyclic ring together with a carbene carbon atom coordinated to Pd, and are each a carbon atom, C—R ₁ , a nitrogen atom, N—R ₁ represents an oxygen atom or a sulfur atom, and at least one represents a nitrogen atom or N—R ₁ . R ₁ represents a hydrogen atom or a substituent. L ₁ represents a bidentate ligand coordinated to Pd. p and q represent an integer of 1 or more and satisfy the relational expression of p + q = 3. When q is 2, the two L ₁ are different from each other. ]

2 . 2. The organic electroluminescence device according to item 1, wherein the ring A in the general formula (2) represents a 5-membered or 6-membered aromatic ring or non-aromatic ring.

〔式中、Ｐｄは配位数が６、かつ４価のパラジウム原子を表す。Ｙ_２〜Ｙ_６はＰｄに配位した炭素原子とともに６員の芳香族環又は非芳香族環を形成する原子群であり、炭素原子、Ｃ−Ｒ_２又は窒素原子を表す。Ｘ_５及びＸ_６はカルベン炭素原子、窒素原子とともに５員の芳香族複素環又は非芳香族複素環を形成する原子群であり、Ｃ−Ｒ_３又は窒素原子を表す。Ｒ_２及びＲ_３は水素原子又は置換基を表し、Ｒ_４は置換基を表す。Ｌ_１は、Ｐｄに配位する２座配位子を表す。ｐ及びｑは、１以上の整数を表し、ｐ＋ｑ＝３の関係式を満たす。ｑが２のとき、二つのＬ_１は互いに異なっている。〕 3 . Palladium complexes having the structure represented by the general formula (2) is organic according to paragraph 1 or 2, characterized in that a palladium complex having the structure represented by the following general formula (3) Electroluminescence element.

[In the formula, Pd represents a coordination number of 6 and a tetravalent palladium atom. Y _{2 to} Y ₆ are an atomic group forming a 6-membered aromatic ring or a non-aromatic ring together with a carbon atom coordinated to Pd, and represent a carbon atom, C—R ₂ or a nitrogen atom. X ₅ and X ₆ are an atomic group forming a 5-membered aromatic heterocycle or a non-aromatic heterocycle together with a carbene carbon atom and a nitrogen atom, and represent C—R ₃ or a nitrogen atom. R ₂ and R ₃ represent a hydrogen atom or a substituent, and R ₄ represents a substituent. L ₁ represents a bidentate ligand coordinated to Pd. p and q represent an integer of 1 or more and satisfy the relational expression of p + q = 3. When q is 2, the two L ₁ are different from each other. ]

〔式中、Ｐｄは、配位数が６、かつ４価のパラジウム原子を表す。Ｘ_７及びＸ_８はカルベン炭素原子、窒素原子とともに５員の芳香族複素環又は非芳香族複素環を形成する原子群であり、Ｃ−Ｒ_３又は窒素原子を表す。Ｒ_３及びＲ_６〜Ｒ_９は水素原子又は置換基を表し、Ｒ_５は置換基を表す。Ｌ_１は、Ｐｄに配位する２座配位子を表す。ｐ及びｑは、１以上の整数を表し、ｐ＋ｑ＝３の関係式を満たす。ｑが２のとき、二つのＬ_１は互いに異なっている。〕 4 . Palladium complexes having the structure represented by the general formula (3) The organic electroluminescent device according to paragraph 3, characterized in that a palladium complex having the structure represented by the following general formula (4).

[Wherein, Pd represents a tetravalent palladium atom having a coordination number of 6; X ₇ and X ₈ are an atomic group forming a 5-membered aromatic heterocyclic ring or a non-aromatic heterocyclic ring together with a carbene carbon atom and a nitrogen atom, and represent C—R ₃ or a nitrogen atom. R ₃ and R _{6 to} R ₉ represent a hydrogen atom or a substituent, and R ₅ represents a substituent. L ₁ represents a bidentate ligand coordinated to Pd. p and q represent an integer of 1 or more and satisfy the relational expression of p + q = 3. When q is 2, the two L ₁ are different from each other. ]

5 . The organic electroluminescence element according to any one of items 1 to 4 , wherein the organic electroluminescence element has a plurality of light emitting layers.

6 . The organic electroluminescent element according to any one of items 1 to 5, wherein the organic electroluminescent element contains two or more types of light emitting elements and the emission color is white.

7 . A display device comprising the organic electroluminescence element according to any one of items 1 to 6 .

8 . An organic electroluminescence element according to any one of items 1 to 6 is provided.

By the means of the present invention, an organic electroluminescence element, a display device, and a lighting device with improved luminous efficiency and durability can be provided.
The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.
Unlike the usual palladium (II) complex or palladium (0) complex, a palladium (IV) complex is used by including the palladium complex represented by the general formula ( 2 ) in the light emitting layer of the organic EL element. Therefore, it is presumed that the geometric change around the palladium atom in the ground state and the excited state is suppressed, and the non-radiative deactivation that is usually large is suppressed. As a result, the light emission efficiency and durability of the organic electroluminescent element containing the palladium complex represented by the general formula ( 2 ), and the display device and the lighting device including the organic electroluminescent element can be improved.

Schematic diagram showing an example of a display device composed of organic EL elements Schematic diagram of the display unit of the display device of FIG. Schematic diagram of a pixel of the display device of FIG. Schematic diagram of passive matrix type full color display device Schematic diagram showing an example of a lighting device Sectional drawing which shows an example of an illuminating device

  The organic electroluminescent element of the present invention is an organic electroluminescent element having at least an anode, a cathode, and a light emitting layer, and the light emitting layer contains a palladium complex having a structure represented by the general formula (1). It is characterized by that. This feature is a technical feature common to the inventions according to claims 1 to 9.

  As an embodiment of the present invention, a palladium complex having a structure represented by the general formula (1) is a palladium complex having a structure represented by the general formula (2) from the viewpoint of manifesting the effects of the present invention. It is preferable that the chemical and physical stability of the complex can be obtained. The stability of this complex is thought to have a significant impact on the stability over time in thin films and devices.

  In addition, ring A in the general formula (2) is more preferably a 5-membered or 6-membered aromatic ring or non-aromatic ring from the viewpoint of further increasing the chemical and physical stability of the complex.

  Further, the palladium complex having the structure represented by the general formula (2) is a palladium complex having the structure represented by the general formula (3), so that the chemical bond with the central metal becomes strong, This is preferable from the viewpoint of increasing the chemical and physical stability of the complex.

  Furthermore, the palladium complex having the structure represented by the general formula (3) is a palladium complex having the structure represented by the general formula (4), so that the chemical and physical stability of the complex is improved. More preferable in terms of increase.

  In addition, it is preferable that the organic electroluminescent element has a plurality of light emitting layers in that it can provide a long-life organic EL element in which a change in emission color with time is suppressed.

  It is preferable that the organic electroluminescence element contains two or more kinds of light-emitting elements and the emission color is white in that it can be provided in a display device, a lighting device, or the like.

  The organic EL element of the present invention can be suitably included in a display device and a lighting device. As a result, a display device and a lighting device with improved luminous efficiency and durability can be obtained.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

[Organic electroluminescence device]
The organic EL device of the present invention is an organic electroluminescence device having a light emitting layer and an electron transport layer adjacent to the cathode side of the light emitting layer between an anode and a cathode, and is represented by the following general formula (1). It contains the palladium complex which has a structure.

<Palladium complex having a structure represented by the general formula (1)>

[Wherein, Pd represents a tetravalent palladium atom having a coordination number of 6; Ring A represents an aromatic ring or a non-aromatic ring having a carbon atom that forms a covalent bond with Pd, and further a halogen atom, a nitro group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, It may have a disubstituted amino group or a linear or branched alkyl group having 1 to 20 carbon atoms. Ring B represents an aromatic ring or a non-aromatic ring having Q (carbon atom, nitrogen atom or phosphorus atom) which forms a coordination bond with Pd, and further a halogen atom, a nitro group, a substituted or unsubstituted aryl group , A substituted or unsubstituted heteroaryl group, a disubstituted amino group, or a linear or branched alkyl group having 1 to 20 carbon atoms. In addition, a new ring structure may be formed by combining a substituent of ring A and a substituent of ring B. L _a , L _b and L _c each represent a monodentate or bidentate ligand, and any one ligand is linked to ring A or ring B to form a tridentate ligand. It may be formed. However, m represents 1 or 2, and n represents 0 or 1. ]

In the general formula (1), Pd represents a coordination number of 6 and a tetravalent palladium atom.
Ring A represents an aromatic ring or a non-aromatic ring having a carbon atom that forms a covalent bond with Pd.
Examples of the aromatic ring represented by ring A include a benzene ring, naphthalene ring, anthracene ring, fluorene ring, pyrene ring, phenanthrene ring, chrysene ring, fluoranthene ring, triphenylene ring, cyclopentene ring, cyclohexene ring, and cyclohexadiene ring. , Norbornene ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, quinoline ring, isoquinoline ring, acridine ring, naphthyridine ring, quinoxaline ring, quinazoline ring, cinnoline ring, phthalazine ring, phenanthrene ring, phenazine ring, thiazole ring, thiophene Ring, furan ring, pyrrole ring, imidazole ring, thiazole ring, benzothiophene ring, benzofuran ring, indole ring, dibenzothiophene ring, dibenzofuran ring, carbazole ring, biphenyl ring, azulene ring, naphthase Ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, pentacene ring, perylene ring, pentaphen ring, picene ring, pyranthrene ring, anthraanthrene ring, oxazole ring, triazine A ring, a benzimidazole ring, an oxadiazole ring, a triazole ring, a pyrazole ring, a benzothiazole ring, a benzoxazole ring, a carboline ring, or a diazacarbazole ring.

  Among these, preferably, a benzene ring, naphthalene ring, fluorene ring, phenanthrene ring, triphenylene ring, cyclopentene ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, quinoline ring, isoquinoline ring, quinoxaline ring, thiophene ring, A benzothiophene ring, a dibenzofuran ring or a carbazole ring; More preferably, they are a benzene ring, a fluorene ring, a pyridine ring, a thiophene ring, a dibenzofuran ring or a carbazole ring. More preferably, they are a benzene ring, a fluorene ring, a thiophene ring or a carbazole ring.

  In the general formula (1), examples of the non-aromatic ring represented by the ring A include various rings included in the compound described later.

Ring A is a halogen atom, a nitro group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, a disubstituted amino group, or a linear or branched alkyl group having 1 to 20 carbon atoms. You may have.
Ring A may have one of these substituents, or may have two or more of these substituents, or two of these substituents. You may have more than one kind.

The halogen atom is preferably a fluorine atom, a chlorine atom, or a bromine atom.
In the case of producing an organic EL element by a vacuum deposition method, a fluorine atom is particularly preferable.

  Examples of the aryl group include a phenyl group, a naphthyl group, an antonyl group, a fluorenyl group, a pyrenyl group, a phenanthrenyl group, a chrycenyl group, a fluoranthenyl group, and a triphenylenyl group. A phenyl group, a naphthyl group, an antonyl group, a fluorenyl group, a pyrenyl group, a phenanthrenyl group, a chrycenyl group, a fluoranthenyl group, or a triphenylenyl group is preferable. More preferably, they are a phenyl group, a fluorenyl group, a phenanthrenyl group or a triphenylenyl group. Particularly preferred is a phenyl group.

Moreover, the substituent enumerated as an aryl group may have a substituent further.
Specific examples include alkyl groups such as methyl group, tertiary butyl group and trifluoromethyl group, halogen atoms such as fluorine atom and chlorine atom, substituted amino groups such as diphenylamino group and ditertiary butylamino group, and the like. .

  Examples of the heteroaryl group include pyridyl, pyrazinyl, pyrimidyl, pyridazinyl, triazinyl, quinolinyl, isoquinolinyl, phenanthridinyl, acridinyl, naphthyridinyl, quinoxalinyl, quinazolinyl, and cinnolinyl groups. , Phthalazinyl group, carbazolyl group, phenanthroyl group, thiazolyl group, isothiazolyl group, imidazolyl group, pyrazolyl group, oxazolyl group, isoxazolyl group, benzothiazolyl group, benzoisothiazolyl group, benzoimidazolyl group, benzopyrazolyl group, benzoxazolyl group, Examples thereof include a benzoisoxazolyl group. Preferred are pyridyl group, pyrazinyl group, pyrimidyl group, triazinyl group, quinolinyl group, isoquinolinyl group, thiazolyl group, imidazolyl group, pyrazolyl group or oxazolyl group. More preferably, it is a pyridyl group or an imidazolyl group.

Moreover, the substituent enumerated as a heteroaryl group may have a substituent further.
Specifically, the same substituent as the substituent which the aryl group may further have is exemplified.

  The di-substituted amino group is preferably a dimethylamino group, a diphenylamino group, or a ditolylamino group from the viewpoint of conductivity or viewpoint. Particularly preferred is a diphenylamino group.

Examples of the alkyl group include a methyl group, an ethyl group, a normal propyl group, an isopropyl group, a normal butyl group, a tertiary butyl group, an octyl group, and a cyclohexyl group.
In the case where the alkyl group has 2 or more carbon atoms, one of the alkyl groups or two or more methylene groups (—CH ₂ —) that are not adjacent to each other are —O—, —S—, —CO—. May be substituted.
Examples of the alkyl group in which the methylene group is substituted with -O-, -S-, -CO- include a methoxy group, an ethoxy group, and a methylsulfanyl group.
In addition, some or all of the hydrogen atoms in the alkyl group may be substituted with fluorine atoms. Examples of the alkyl group substituted with a fluorine atom include a trifluoromethyl group.

  Among the alkyl groups listed above (including those in which a methylene group is substituted with —O—, etc., and those in which some or all of the hydrogen atoms are substituted with fluorine atoms), preferably a methyl group, An ethyl group, a tertiary butyl group, a trifluoromethyl group, a methoxy group or a methylsulfanyl group. More preferably, they are a methyl group, a tertiary butyl group, a trifluoromethyl group, or a methoxy group.

  In the general formula (1), ring B represents an aromatic ring or a non-aromatic ring having Q that forms a coordinate bond with Pd. Here, examples of Q include a carbon atom, a nitrogen atom, or a phosphorus atom. Preferably, it is a nitrogen atom.

  Examples of the aromatic ring represented by ring B include pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, triazine ring, quinoline ring, isoquinoline ring, phenanthridine ring, acridine ring, naphthyridine ring, quinoxaline ring, and quinazoline. Ring, cinnoline ring, phthalazine ring, phenanthroline ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, oxazole ring, isoxazole ring, benzothiazole ring, benzoisothiazole ring, benzimidazole ring, benzopyrazole ring, benzoxazole Examples thereof include, but are not limited to, a ring, a benzoisoxazole ring, and an oxazole ring. Among these, preferably a pyridine ring, pyrazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, quinoxaline ring, phenanthroline ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, oxazole ring or isoxazole It is a ring. More preferred are a pyridine ring, a thiazole ring, an iasothiazole ring, an imidazole ring, a pyrazole ring, an indole ring, or a triazole ring.

  In the general formula (1), examples of the non-aromatic ring represented by the ring B include various rings included in the compound described later.

Ring B is a halogen atom, a nitro group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, a disubstituted amino group, or a linear or branched alkyl group having 1 to 20 carbon atoms. You may have.
Here, specific examples of the halogen atom, aryl group, heteroaryl group, disubstituted amino group, and alkyl group include the halogen atom, aryl group, heteroaryl group, disubstituted amino group, and alkyl group that the ring A may have. This is the same as the specific example.
Specific examples of the substituent that the aryl group and the heteroaryl group may further have are the same as the specific examples of the substituent that the aryl group that the ring A may further have. .
Ring B may have any one of these substituents, may have any two or more of these substituents, or two of these substituents. You may have more than one kind.

On the other hand, a new ring structure may be formed by combining the substituent of ring A and the substituent of ring B.
Hereinafter, a partial structure including a ligand including a new ring structure formed by combining a substituent that ring A has and a substituent that ring B has is shown. However, these are merely representative examples, and the present invention is not limited thereto.

In the general formula (1), L _a , L _b and L _c each represent a monodentate or bidentate ligand.
L _a is preferably a monovalent bidentate ligand. Here, the atom that forms a coordinate bond with the palladium atom is not particularly limited, but is preferably a nitrogen atom, a phosphorus atom, a carbon atom, an oxygen atom, or a sulfur atom. The atom that forms a covalent bond with the palladium atom is not particularly limited, but is preferably a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, or a phosphorus atom.

Further, _{L a} is preferably a ligand represented by the B000 of the formula. In addition, the ligand B000 shown by the following formula is described in a state where it is bonded to a palladium atom.

Hereinafter, specific examples of the ligand is L _a. However, these are merely representative examples, and the present invention is not limited thereto. In addition, the ligand shown below is described in the state couple | bonded with the palladium atom.

〔Ｒ_１０１〜Ｒ_１２８は、それぞれ一般式（１）における、環Ａが有してもよい置換基と同様の置換基を表す。〕

[R _{101 to} R ₁₂₈ each represent a substituent similar to the substituent that the ring A may have in the general formula (1). ]

In the general formula (1), L _b preferably represents a divalent bidentate ligand. Here, the atom that forms a covalent bond with the palladium atom is not particularly limited, but is preferably a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, or a phosphorus atom.

L _b is preferably a bidentate ligand having a carbon atom and an oxygen atom that form a covalent bond with a palladium atom.

Hereinafter, specific examples of the ligand is L _b. However, these are merely representative examples, and the present invention is not limited thereto. In addition, the ligand shown below is described in the state couple | bonded with the palladium atom.

〔Ｒ_１２９〜Ｒ_１５６は、それぞれ一般式（１）における、環Ａが有してもよい置換基と同様の置換基を表す。〕

[R _{129 to} R ₁₅₆ each represent a substituent similar to the substituent that the ring A may have in the general formula (1). ]

In the general formula (1), L _c preferably represents a monodentate (monodentate) ligand.
Examples of monodentate ligands include minus monovalent anionic monodentate ligands. Specifically, it represents a monodentate ligand that forms a covalent bond with a palladium atom. The coordination atom of the ligand is preferably a carbon atom, a hydrogen atom, an oxygen atom, a fluorine atom or a chlorine atom.

Further, any one of the ligands L _a , L _b and L _c may be linked to ring A or ring B to form a tridentate ligand. However, m represents 1 or 2, and n represents 0 or 1.

<Palladium complex having a structure represented by the general formula (2)>
The palladium complex having a structure represented by the general formula (1) is preferably a compound having a structure represented by the following general formula (2).

[Wherein, Pd represents a tetravalent palladium atom having a coordination number of 6; Ring A represents an aromatic ring or a non-aromatic ring formed with Y ₁ and a carbon atom, and further represents a halogen atom, a nitro group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, or a disubstituted ring You may have an amino group or a C1-C20 linear or branched alkyl group. These substituents may be bonded to each other to form a ring. Y ₁ represents a carbon atom or a nitrogen atom. X _{1 to} X ₄ are atomic groups that form a 5-membered aromatic heterocyclic ring or a non-aromatic heterocyclic ring together with a carbene carbon atom coordinated to Pd, and are each a carbon atom, C—R ₁ , a nitrogen atom, N—R ₁ represents an oxygen atom or a sulfur atom, and at least one represents a nitrogen atom or N—R ₁ . R ₁ represents a hydrogen atom or a substituent. L ₁ represents a bidentate ligand coordinated to Pd. (P and q represents an integer of 1 or more, when .q satisfying p + q = 3 the relation is 2, the two _{L 1} are different from each other.)]

In the general formula (2), Pd represents a tetravalent palladium atom having a coordination number of 6 and.
Ring A represents an aromatic ring or a non-aromatic ring formed together with Y ₁ and a carbon atom, and is particularly preferably a 5-membered or 6-membered aromatic ring or a non-aromatic ring.

  In the general formula (2), examples of the aromatic ring represented by ring A include a benzene ring, naphthalene ring, biphenyl 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, fluoranthene ring, pentacene ring, perylene ring, pentaphen ring, picene ring, pyranthrene ring, and anthraanthrene ring And aromatic hydrocarbon rings such as

  In addition, furan ring, thiophene ring, oxazole 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, Benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, carbazole ring, carboline ring, and diazacarbazole ring (one of the carbon atoms of the hydrocarbon ring constituting the carboline ring is further substituted with a nitrogen atom) Aromatic heterocycles such as Among these, a thiophene ring, a pyridine ring, a carbazole ring, a carboline ring, and a diazacarbazole ring are preferable.

  In the general formula (2), examples of the non-aromatic ring represented by the ring A include various rings included in the compounds described later.

Ring A is a halogen atom, a nitro group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, a disubstituted amino group, or a linear or branched alkyl group having 1 to 20 carbon atoms. You may have.
Ring A may have one of these substituents, or may have two or more of these substituents, or two of these substituents. You may have more than one kind.
The halogen atom, aryl group, heteroaryl group, disubstituted amino group, and alkyl group are the same as those described for the ring A in the general formula (1).

  Moreover, said substituent substituted by the ring A may have a substituent further. In addition, the aromatic ring or the non-aromatic ring may be further substituted with an aromatic ring hydrocarbon group, an aromatic heterocyclic group, or the like to form a condensed ring structure.

In the general formula (2), Y ₁ represents a carbon atom or a nitrogen atom.

In the general formula (2), X _{1 to} X ₄ are atomic groups that form a 5-membered aromatic heterocyclic ring or a non-aromatic heterocyclic ring together with a carbene carbon atom coordinated to Pd, C—R _{1 represents} a nitrogen atom, N—R ₁ , an oxygen atom or a sulfur atom, and at least one represents a nitrogen atom or N—R ₁ .
Examples of the 5-membered aromatic heterocycle include pyrazole ring, imidazole ring, thiazole ring, oxazole ring, isoxazole ring, indole ring, triazole ring, benzimidazole ring, benzopyrazole ring, benzothiazole ring, benzoxazole ring, and Examples thereof include a benzoisoxazole ring. Among these, an imidazole ring, a thiazole ring, an oxazole ring, and a triazole ring are preferable.
Examples of the 5-membered non-aromatic heterocyclic ring include various rings contained in the compounds described later.

R ₁ represents a hydrogen atom or a substituent, and examples of the substituent include a substituent substituted on the 5-membered or 6-membered aromatic ring or non-aromatic ring represented by the ring A.

In the general formula (2), L ₁ represents a bidentate ligand coordinated to Pd. The bidentate ligand will be described later.
In General formula (2), p and q represent an integer greater than or equal to 1, and satisfy | fill the relational expression of p + q = 3. When q is 2, the two L ₁ are different from each other.

<Compound having a structure represented by the general formula (3)>
The compound having a structure represented by the general formula (2) is preferably a compound having a structure represented by the following general formula (3).

[In the formula, Pd represents a coordination number of 6 and a tetravalent palladium atom. Y _{2 to} Y ₆ are an atomic group forming a 6-membered aromatic ring or a non-aromatic ring together with a carbon atom coordinated to Pd, and represent a carbon atom, C—R ₂ or a nitrogen atom. X ₅ and X ₆ are an atomic group forming a 5-membered aromatic heterocycle or a non-aromatic heterocycle together with a carbene carbon atom and a nitrogen atom, and represent C—R ₃ or a nitrogen atom. R ₂ and R ₃ represent a hydrogen atom or a substituent, and R ₄ represents a substituent. L ₁ represents a bidentate ligand coordinated to Pd. p and q represent an integer of 1 or more and satisfy the relational expression of p + q = 3. When q is 2, the two L ₁ are different from each other. ]

In the general formula (3), Pd represents a coordination number of 6 and a tetravalent palladium atom.
Y ₂ to Y ₆ is a group of atoms forming an aromatic or non-aromatic ring of 6 members together with carbon atoms coordinated to Pd, represents a carbon atom, C-R ₂ or a nitrogen atom.
Examples of the 6-membered aromatic ring include a benzene ring, naphthalene ring, biphenyl ring, azulene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, naphthacene ring, triphenylene ring, o-terphenyl ring, and m-terphenyl ring. Aromatic hydrocarbon rings such as rings, p-terphenyl rings, acenaphthene rings, coronene rings, fluorene rings, fluoranthene rings, pentacene rings, perylene rings, pentaphen rings, picene rings, pyrene rings, pyranthrene rings, and anthraanthrene rings Is mentioned.

  In addition, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, benzimidazole ring, indole ring, benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, carbazole ring, carboline ring, and diaza Aromatic heterocycles such as a carbazole ring (representing a ring in which one of the carbon atoms of the hydrocarbon ring constituting the carboline ring is further substituted with a nitrogen atom) can be mentioned. Among these, a pyridine ring, a triazine ring, a carbazole ring, a carboline ring, and a diazacarbazole ring are preferable.

  Examples of the 6-membered non-aromatic ring include various rings included in the compounds described later.

  In addition, these aromatic rings may have a substituent, and examples of the substituent include substituents substituted on the 5-membered or 6-membered aromatic ring or non-aromatic ring represented by the ring A. Can be mentioned.

In the general formula (3), X ₅ and X _6, carbene carbon atom is an atom group forming a 5-membered aromatic heterocyclic ring or non-aromatic heterocyclic ring together with the nitrogen atom, a C-R ₃ or a nitrogen atom Represent.
Examples of the 5-membered aromatic heterocycle include an imidazole ring, a benzimidazole ring, and a triazole ring. Among these, an imidazole ring is preferable.
Examples of the 5-membered non-aromatic heterocyclic ring include various rings included in the compounds described later.

  These aromatic heterocycles may have a substituent, and examples of the substituent include a substituent substituted on the 5-membered or 6-membered aromatic ring or non-aromatic ring represented by the ring A. .

R ₂ and R ₃ represent a hydrogen atom or a substituent, and R ₄ represents a substituent. Examples of the substituent represented by R ₂ , R ₃ and R ₄ include a substituent that substitutes for the 5-membered or 6-membered aromatic ring or non-aromatic ring represented by the ring A in the general formula (2). Can be mentioned.

In the general formula (3), L ₁ represents a bidentate ligand coordinated to Pd. The bidentate ligand will be described later.
In General formula (3), p and q represent an integer greater than or equal to 1, and satisfy | fill the relational expression of p + q = 3. When q is 2, the two L ₁ are different from each other.

<Compound having a structure represented by the general formula (4)>
The compound having a structure represented by the general formula (3) is preferably a compound having a structure represented by the following general formula (4).

[Wherein, Pd represents a tetravalent palladium atom having a coordination number of 6; X ₇ and X ₈ are an atomic group forming a 5-membered aromatic heterocyclic ring or a non-aromatic heterocyclic ring together with a carbene carbon atom and a nitrogen atom, and represent C—R ₃ or a nitrogen atom. R ₃ and R _{6 to} R ₉ represent a hydrogen atom or a substituent, and R ₅ represents a substituent. L ₁ represents a bidentate ligand coordinated to Pd. p and q represent an integer of 1 or more and satisfy the relational expression of p + q = 3. When q is 2, the two L ₁ are different from each other. ]

In the general formula (4), Pd represents a coordination number of 6 and a tetravalent palladium atom.
X ₇ and X ₈ are an atomic group forming a 5-membered aromatic heterocyclic ring or a non-aromatic heterocyclic ring together with a carbene carbon atom and a nitrogen atom, and represent C—R ₃ or a nitrogen atom.
Examples of the 5-membered aromatic heterocycle include an imidazole ring, a benzimidazole ring, and a triazole ring. Among these, an imidazole ring is preferable.
Examples of the 5-membered non-aromatic heterocyclic ring include various rings included in the compounds described later.
R ₃ and R _{6 to} R ₉ represent a hydrogen atom or a substituent, and R ₅ represents a substituent.
Examples of the substituent represented by R ₃ , R _{5 to} R ₉ and the substituent substituted on X ₇ and X ₈ include a 5-membered or 6-membered aromatic represented by the ring A in the general formula (2). Examples of the substituent include a ring or a non-aromatic ring.

In the general formula (4), L ₁ represents a bidentate ligand coordinated to Pd. The bidentate ligand will be described later.
In General formula (4), p and q represent an integer greater than or equal to 1, and satisfy | fill the relational expression of p + q = 3. When q is 2, the two L ₁ are different from each other.

<Description of bidentate ligand>
In the general formulas (2) to (4), as the bidentate ligand represented by L ₁ , conventionally known ones can be used. By selecting a bidentate ligand, it is possible to optimize the emission wavelength and improve the emission quantum efficiency. Alternatively, the interaction between the complexes can be suppressed by the steric effect of the bidentate ligand, whereby the light emission efficiency when an organic EL element is obtained can be improved.

  The bidentate ligand may be one or two, and in the case of two, they are the same as each other, and the valence and coordination number between the palladium atom of the central metal are Satisfactory, i.e., a coordination number of 6 and a tetravalent palladium complex must be formed.

  When there are a plurality of vacant coordination sites, a bidentate ligand is more preferable in order to obtain stabilization of the complex itself by a chelate effect.

Conventionally known ligands used for metal complexes include, for example, “Photochemistry and Photophysics of Coordination Compounds” Springer-Verlag H. Published by Yersin in 1987, “Organometallic Chemistry-Fundamentals and Applications-” Liu Huabo Company, Akio Yamamoto, published in 1982, etc. (for example, halogen ligands (preferably chlorine ligands), Nitrogen heterocyclic ligands (for example, bipyridyl, phenanthroline, etc.) and diketone ligands).
Furthermore, substituted or unsubstituted phenylpyridine, phenylpyrazole, phenylimidazole, phenyltriazole, phenyltetrazole, pyrazabol, picolinic acid, carbene, and the like can be used in combination as preferable ligands.

  Hereinafter, the bidentate ligand according to the present invention that can constitute a coordination number of 6 and a tetravalent palladium complex will be described.

(Minus monovalent anionic bidentate ligand)
The minus monovalent anionic bidentate ligand represents a bidentate ligand that forms a covalent bond and a coordinate bond with a palladium atom. The coordination atom of the ligand is preferably a carbon atom, an oxygen atom, a sulfur atom, a nitrogen atom, or a phosphorus atom.

(Minus divalent anionic bidentate ligand)
The minus divalent anionic bidentate ligand represents a bidentate ligand that forms a covalent bond with a palladium atom. As a coordination atom of the ligand, a combination of a carbon atom and a nitrogen atom is preferable, and a phenylpyridine ligand, a phenylimidazole ligand, and a benzoquinoline ligand are preferable.

The coordination number 6 and tetravalent palladium complex according to the present invention is preferably a neutral complex (nonionic). This is because a neutral metal complex is easily sublimated because there is no ionic interaction between the complexes, and is advantageous for sublimation purification of the metal complex and vacuum deposition for producing an organic EL device.
Specific examples of the coordination number 6 and tetravalent palladium complex according to the present invention are illustrated below.

(Exemplary compounds)

These coordination number 6 and tetravalent palladium complexes can be synthesized by known methods for producing organometallic complexes, including known methods for producing palladium complexes.

[Configuration of organic EL element]
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.
(1) Anode / light emitting layer // cathode (2) Anode / light emitting layer / electron transport layer / cathode (3) Anode / hole transport layer / light emitting layer / cathode (4) Anode / hole transport layer / light emitting layer / Electron transport layer / cathode (5) anode / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode (6) anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / cathode (7) Anode / hole injection layer / hole transport layer / (electron blocking layer /) light emitting layer / (hole blocking layer /) electron transport layer / electron injection layer / cathode Among the above, the configuration of (7) is Although used preferably, it is not limited to this.
The light emitting layer according to the present invention is composed of a single layer or a plurality of layers, and when there are a plurality of light emitting layers, a non-light emitting intermediate layer may be provided between the light emitting layers.
If necessary, a hole blocking layer (also referred to as a hole barrier layer) or an electron injection layer (also referred to as a cathode buffer layer) may be provided between the light emitting layer and the cathode. Further, an electron blocking layer (also referred to as an electron barrier layer) or a hole injection layer (also referred to as an anode buffer layer) may be provided between the light emitting layer and the anode.

The electron transport layer according to the present invention is a layer 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. Moreover, you may be comprised by multiple layers.
The hole transport layer according to the present invention is a layer 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. Moreover, you may be comprised by multiple layers.
In the above-described typical element configuration, the layer excluding the anode and the cathode is also referred to as “organic layer”.

<Tandem structure>
The organic EL element according to the present invention may be an element having a so-called tandem structure in which a plurality of light emitting units including at least one light emitting layer are stacked.
As typical element configurations of the tandem structure, for example, the following configurations can be given.
Anode / first light emitting unit / intermediate layer / second light emitting unit / intermediate layer / third light emitting unit / cathode Here, the first light emitting unit, the second light emitting unit and the third light emitting unit are all the same, May be different. Two light emitting units may be the same, and the remaining one may be different.
The plurality of light emitting units may be laminated directly or via an intermediate layer, and the intermediate layer is generally an intermediate electrode, an intermediate conductive layer, a charge generation layer, an electron extraction layer, a connection layer, A known material structure can be used as long as it is also called an intermediate insulating layer and has a function of supplying electrons to the anode-side adjacent layer and holes to the cathode-side adjacent layer.

Examples of materials used for the intermediate layer include ITO (indium tin oxide), IZO (indium zinc oxide), ZnO ₂ , TiN, ZrN, HfN, TiOx, VOx, CuI, InN, GaN, and CuAlO _2. , CuGaO ₂ , SrCu ₂ O ₂ , LaB ₆ , RuO ₂ , Al, etc., conductive inorganic compound layers, Au / Bi ₂ O _3, etc., two-layer films, SnO ₂ / Ag / SnO ₂ , ZnO / Ag / ZnO, Bi ₂ O ₃ / Au / Bi ₂ O ₃ , TiO ₂ / TiN / TiO ₂ , TiO ₂ / ZrN / TiO _{2 and} other multilayer films, C _{60 and} other fullerenes, conductive organic layers such as oligothiophene , Conductive organic compound layers such as metal phthalocyanines, metal-free phthalocyanines, metal porphyrins, metal-free porphyrins, etc. The present invention is not limited to these.

Examples of a preferable configuration in the light emitting unit include those obtained by removing the anode and the cathode from the configurations (1) to (7) described in the above representative element configurations, but the present invention is not limited thereto. Not.
Specific examples of the tandem organic EL element include, for example, US Pat. No. 6,337,492, US Pat. No. 7,420,203, US Pat. No. 7,473,923, US Pat. No. 6,872,472, US Pat. No. 6,107,734, US Pat. No. 6,337,492, International JP 2005/009087, JP 2006-228712, JP 2006-24791, JP 2006-49393, JP 2006-49394, JP 2006-49396, JP 2011. No. -96679, JP 2005-340187, JP 47114424, JP 34096681, JP 3884564, JP 431169, JP 2010-192719, JP 2009-076929, JP Open 2008-0784 No. 4, JP 2007-059848 A, JP 2003-272860 A, JP 2003-045676 A, International Publication No. 2005/094130, and the like. The present invention is not limited to these.

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 provides a field in which electrons and holes injected from an electrode or an adjacent layer are recombined to emit light via excitons, and the light emitting portion is a layer of the light emitting layer. Even within, it may be the interface between the light emitting layer and the adjacent layer.
If the light emitting layer which concerns on this invention contains the palladium complex which has a structure represented by General formula (1) mentioned above as a light emitting dopant in this light emitting layer, there will be no restriction | limiting in particular in the structure.

The total thickness of the light emitting layer is not particularly limited, but it is possible to prevent the uniformity of the film to be formed, the application of an unnecessary high voltage during light emission, and the improvement of the stability of the emission color with respect to the driving current. Therefore, it is preferable to adjust within the range of 2 nm to 5 μm. More preferably, it adjusts in the range of 2-500 nm, More preferably, it adjusts in the range of 5-200 nm.
The film thickness of each light emitting layer of the present invention is preferably adjusted within the range of 2 nm to 1 μm, more preferably adjusted within the range of 2 to 200 nm, and further preferably within the range of 3 to 150 nm. Adjusted to
The light-emitting layer according to the present invention contains a light-emitting dopant (a light-emitting dopant compound, a dopant compound, also simply referred to as a dopant) and a host compound (a matrix material, a light-emitting host compound, also simply referred to as a host). preferable.

(1) Luminescent dopant As the luminescent dopant, a fluorescent luminescent dopant (also referred to as a fluorescent dopant or a fluorescent compound) and a phosphorescent dopant (also referred to as a phosphorescent dopant or a phosphorescent compound) are preferably used.
A coordination number of 6 and a tetravalent palladium complex according to the present invention is a phosphorescent dopant, and in the present invention, at least one light emitting layer has a coordination number of 6 according to the present invention, and Contains a tetravalent palladium complex.

The concentration of the light-emitting dopant in the light-emitting layer can be arbitrarily determined based on the specific dopant used and the requirements of the device, and is contained at a uniform concentration in the film thickness direction of the light-emitting layer. It may also have an arbitrary concentration distribution.
In addition, the light-emitting dopant according to the present invention may be used in combination of plural kinds other than the tetravalent palladium complex having a coordination number of 6 according to the present invention. A luminescent dopant and a phosphorescent dopant may be used in combination. Thereby, arbitrary luminescent colors can be obtained.

  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 (manufactured by Konica Minolta Optics Co., Ltd.) is applied to the CIE chromaticity coordinates.

In the present invention, it is also preferable that the light emitting layer of one layer or a plurality of layers contains a plurality of light emitting dopants having different emission colors and emits white light.
There are no particular limitations on the combination of light-emitting dopants that exhibit white, and examples include blue and orange, and a combination of blue, green, and red.
The white color in the organic EL device of the present invention means that the chromaticity in the CIE 1931 color system at 1000 cd / m ² is x = 0.39 ± 0.09 when the 2 ° viewing angle front luminance is measured by the method described above. Y = 0.38 ± 0.08.

(1.1) Fluorescent Luminescent Dopant The fluorescent luminescent dopant in the present invention (hereinafter also referred to as “fluorescent dopant”) is a compound capable of emitting light from an excited singlet, and light emission from the excited singlet is observed. It is not particularly limited as long as it is done.
Examples of the fluorescent dopant include anthracene derivatives, pyrene derivatives, chrysene derivatives, fluoranthene derivatives, perylene derivatives, fluorene derivatives, arylacetylene derivatives, styrylarylene derivatives, styrylamine derivatives, arylamine derivatives, boron complexes, coumarin derivatives, pyran derivatives, Examples include cyanine derivatives, croconium derivatives, squalium derivatives, oxobenzanthracene derivatives, fluorescein derivatives, rhodamine derivatives, pyrylium derivatives, perylene derivatives, polythiophene derivatives, and rare earth complex compounds.
In recent years, light-emitting dopants using delayed fluorescence have been developed, and these may be used.
Specific examples of the luminescent dopant using delayed fluorescence include, for example, the compounds described in International Publication No. 2011/156793, Japanese Patent Application Laid-Open No. 2011-213643, Japanese Patent Application Laid-Open No. 2010-93181, and the like. Is not limited to these.

(1.2) Phosphorescent dopant The phosphorescent dopant in the present invention (hereinafter also referred to as “phosphorescent dopant”) is a compound in which light emission from an excited triplet is observed. Specifically, The phosphorescence emission compound at room temperature (25 ° C) is defined as a compound having a phosphorescence quantum yield of 0.01 or more at 25 ° C, but a preferable phosphorescence quantum yield is 0.1 or more. is there.
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 above phosphorescence quantum yield (0.01 or more) in any solvent. Just do it.

There are two types of emission of phosphorescent dopants in principle. One is the recombination of carriers on the host compound to which carriers are transported, generating an excited state of the host compound, and this energy is used as the phosphorescent dopant. It is an energy transfer type that emits light from a phosphorescent dopant by being moved.
The other is a carrier trap type in which the phosphorescent dopant becomes a carrier trap, and recombination of carriers occurs on the phosphorescent dopant, and light emission from the phosphorescent dopant 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.
The phosphorescent dopant can be appropriately selected from known ones used for the light-emitting layer of the organic EL device, in addition to the coordination number 6 and tetravalent palladium complex according to the present invention.

Specific examples of known phosphorescent dopants that can be used in the present invention include compounds described in the following documents.
Nature 395, 151 (1998), Appl. Phys. Lett. 78, 1622 (2001), Adv. Mater. 19, 739 (2007), Chern. Mater. 17, 3532 (2005), Adv. Mater. 17, 1059 (2005), International Publication No. 2009/100991, International Publication No. 2008/101842, International Publication No. 2003/040257, United States Patent Publication No. 2006835469, United States Patent Publication No. 2006060202194, United States Patent Publication No. 20070087321. No., US Patent Publication No. 20050244673, Inorg. Chern. 40, 1704 (2001), Chern. Mater. 16, 2480 (2004), Adv. Mater. 16, 2003 (2004), Angew. Chern. lnt. Ed. 2006, 45, 7800, Appl. Phys. Lett. 86, 153505 (2005), Chern. Lett. 34, 592 (2005), Chern. Commun. 2906 (2005), Inorg. Chern. 42, 1248 (2003), International Publication No. 2009/050290, International Publication No. 2002/015645, International Publication No. 2009/000673, United States Patent Publication No. 20020034656, United States Patent No. 7332232, United States Patent Publication No. 20090108737. US Patent Publication No. 20090039776, US Patent No. 6921915, US Patent No. 6,687,266, US Patent Publication No. 20070190359, US Patent Publication No. 2006060008670, US Patent Publication No. 20090165846, US Patent Publication No. 20080015355, US Patent No. 7250226, U.S. Pat. No. 7,396,598, U.S. Patent Publication No. 20060263635, U.S. Patent Publication No. 200301368657, U.S. Pat. Publication No. 2003015. 802, U.S. Patent No. 7,090,928, Angew. Chern. lnt. Ed. 47, 1 (2008), Chern. Mater. 18, 5119 (2006), Inorg. Chern. 46, 4308 (2007), Organometallics 23, 3745 (2004), Appl. Phys. Lett. 74, 1361 (1999), International Publication No. 2002/002714, International Publication No. 2006/009024, International Publication No. 2006/056418, International Publication No. 2005/019373, International Publication No. 2005/123873, International Publication No. 2005/123873, International Publication No. 2007/004380, International Publication No. 2006/082742, United States Patent Publication No. 20060251923, United States Patent Publication No. 20050260441, United States Patent No. 7393599, United States Patent No. 7534505, United States Patent No. No. 7445855, U.S. Patent Publication No. 20070190359, U.S. Patent Publication No. 200802977033, U.S. Pat. No. 7,338,722, U.S. Patent Publication No. 20020134984, U.S. Pat. No. 7,279,704, U.S. Pat. No. 2006098120, U.S. Patent Publication No. 2006103874, International Publication No. 2005/076380, International Publication No. 2010/032663, International Publication No. 2008/140115, International Publication No. 2007/052431, International Publication No. 2011/134013. No., International Publication No. 2011/157339, International Publication No. 2010/086089, International Publication No. 2009/113646, International Publication No. 2012/020327, International Publication No. 2011/051404, International Publication No. 2011/004639, JP2012-069737, JP2009-114086, JP2003-81988, JP2002-302671, JP2002-363552, and the like.

  Among them, a preferable phosphorescent dopant includes an organometallic complex having Ir as a central metal. More preferably, a complex containing at least one coordination mode of a metal-carbon bond, a metal-nitrogen bond, a metal-oxygen bond, or a metal-sulfur bond is preferable.

(2) Host compound The host compound in the present invention is a compound mainly responsible for charge injection and transport or energy in the light-emitting layer, and its own light emission is not substantially observed in the organic EL device.
Preferably, it is a compound having a phosphorescence quantum yield of phosphorescence emission of less than 0.1 at room temperature (25 ° C.), more preferably a compound having a phosphorescence quantum yield of 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.
Moreover, it is preferable that the excited state energy of a host compound is higher than the excited state energy of the light emission dopant contained in the same layer.
A host compound may be used independently or may be used in combination of multiple types. By using a plurality of types of host compounds, it is possible to adjust charge transfer or energy transfer, and to increase the efficiency of the organic EL element.

There is no restriction | limiting in particular as a host compound which can be used by this invention, The compound conventionally used with an organic EL element can be used. It may be a low molecular compound or a high molecular compound having a repeating unit, or a compound having a reactive group such as a vinyl group or an epoxy group.
As a known host compound, while having a hole transporting ability or an electron transporting ability, the emission of light is prevented from being increased in wavelength, and the organic EL element is stable against heat generation during driving at a high temperature or during element driving. From the viewpoint of operation, it is preferable to have a high glass transition temperature (Tg). Preferably, Tg is 90 ° C. or higher, more preferably 120 ° C. or higher.
Here, the glass transition point (Tg) is a value obtained by a method based on JIS-K-7121 using DSC (Differential Scanning Colorimetry).

Specific examples of known host compounds used in the organic EL device of the present invention include compounds described in the following documents, but the present invention is not limited thereto.
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.

<Electron transport layer>
In the present invention, the electron transport layer is made of a material having a function of transporting electrons, and may have a function of transmitting electrons injected from the cathode to the light emitting layer.
The total film thickness of the electron transport layer of the present invention is not particularly limited, but is usually in the range of 2 nm to 5 μm, more preferably in the range of 2 to 500 nm, and still more preferably in the range of 5 to 200 nm. Is within.
Also, in the organic EL element, when light generated in the light emitting layer is extracted from the electrode, the light extracted directly from the light emitting layer interferes with the light extracted after being reflected by the electrode from which the light is extracted and the electrode located at the counter electrode. It is known to cause. When light is reflected by the cathode, this interference effect can be efficiently utilized by appropriately adjusting the total film thickness of the electron transport layer within a range of several nm to several μm.

On the other hand, when the thickness of the electron transport layer is increased, the voltage is likely to increase. Therefore, particularly when the thickness is large, the electron mobility of the electron transport layer is preferably 10 ⁻⁵ cm ² / Vs or more. .
The material used for the electron transport layer (hereinafter referred to as an electron transport material) may be any of electron injecting or transporting properties and hole blocking properties, and can be selected from conventionally known compounds. Can be selected and used.
For example, nitrogen-containing aromatic heterocyclic derivatives (carbazole derivatives, azacarbazole derivatives (one or more carbon atoms constituting the carbazole ring are substituted with nitrogen atoms), pyridine derivatives, pyrimidine derivatives, pyrazine derivatives, pyridazine derivatives, Triazine derivatives, quinoline derivatives, quinoxaline derivatives, phenanthroline derivatives, azatriphenylene derivatives, oxazole derivatives, thiazole derivatives, oxadiazole derivatives, thiadiazole derivatives, triazole derivatives, benzimidazole derivatives, benzoxazole derivatives, benzthiazole derivatives, etc.), dibenzofuran derivatives, And dibenzothiophene derivatives, silole derivatives, aromatic hydrocarbon ring derivatives (naphthalene derivatives, anthracene derivatives, triphenylene, etc.).

In addition, a metal complex having a quinolinol skeleton or a dibenzoquinolinol skeleton as a ligand, for example, 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 their metal complexes A metal complex in which the central metal is replaced with In, Mg, 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 terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably 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 the hole transport layer. Can also be used as an electron transporting material.
Further, 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 the electron transport layer according to the present invention, the electron transport layer may be doped with a doping material as a guest material to form an electron transport layer having a high n property (electron rich).
Examples of the doping material include n-type dopants such as metal complexes and metal compounds such as metal halides.
Specific examples of the electron transport layer having such a structure include, for example, JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J. Pat. Appl. Phys. , 95, 5773 (2004) and the like.

Specific examples of known preferable electron transport materials used in the organic EL device of the present invention include compounds described in the following documents, but the present invention is not limited thereto.
U.S. Pat.No. 6,528,187, U.S. Pat.No. 7,230,107, U.S. Patent Publication No. 20050025993, U.S. Pat. Publication No. 2004036077, U.S. Pat. Publication No. 200901115316, U.S. Pat. Publication No. 20090101870, U.S. Pat. 2003/060956, International Publication No. 2008/132805, Appl. Phys. Lett. 75, 4 (1999), Appl. Phys. Lett. 79, 449 (2001), Appl. Phys. Lett. 81, 162 (2002), Appl. Phys. Lett. 81, 162 (2002), Appl. Phys. Lett. 79, 156 (2001), U.S. Patent No. 7964293, U.S. Patent Publication No. 2009030202, International Publication No. 2004/080975, International Publication No. 2004/063159, International Publication No. 2005/085387, International Publication No. 2006/067931. No., International Publication No. 2007/085652, International Publication No. 2008/114690, International Publication No. 2009/066942, International Publication No. 2009/066779, International Publication No. 2009/054253, International Publication No. 2011-086935, WO2010 / 150593, WO2010 / 047707, EP23111826, JP2010-251675A, JP2009-209133A, JP2009-124114A, JP2008-2. 7810, JP-A-2006-156445, JP-A-2005-340122, JP-A-2003-45662, JP-A-2003-31367, JP-A-2003-282270, International Publication No. 2012/115034. No., etc.

More preferable electron transport materials in the present invention include pyridine derivatives, pyrimidine derivatives, pyrazine derivatives, triazine derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, carbazole derivatives, azacarbazole derivatives, and benzimidazole derivatives.
The electron transport material may be used alone or in combination of two or more.

<Hole blocking layer>
The hole blocking layer is a layer having a function of an electron transport layer in a broad sense. Preferably, it is made of a material that has a function of transporting electrons and has a small ability to transport holes. By blocking holes while transporting electrons, the recombination probability of electrons and holes can be improved. .
Moreover, the structure of the electron carrying layer mentioned above can be used as a hole-blocking layer concerning this invention as needed.
The hole blocking layer provided in the organic EL device of the present invention is preferably provided adjacent to the cathode side of the light emitting layer.
The thickness of the hole blocking layer according to the present invention is preferably in the range of 3 to 100 nm, and more preferably in the range of 5 to 30 nm.
As the material used for the hole blocking layer, the material used for the above-described electron transport layer is preferably used, and the material used as the above-described host compound is also preferably used for the hole blocking layer.

<Electron injection layer>
The electron injection layer (also referred to as “cathode buffer layer”) according to the present invention is a layer provided between the cathode and the light emitting layer in order to lower the driving voltage and improve the light emission luminance. It is described in detail in Chapter 2 “Electrode Materials” (pages 123 to 166) of the second edition of “The Forefront of Industrialization” (issued by NTT Corporation on November 30, 1998).
In the present invention, the electron injection layer may be provided as necessary, and may be present between the cathode and the light emitting layer or between the cathode and the electron transport layer as described above.
The electron injection layer is preferably a very thin film, and the film thickness is preferably in the range of 0.1 to 5 nm although it depends on the material. Moreover, the nonuniform film | membrane in which a constituent material exists intermittently may be sufficient.

The details of the electron injection layer are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specific examples of materials preferably used for the electron injection layer are as follows. , Metals typified by strontium and aluminum, alkali metal compounds typified by lithium fluoride, sodium fluoride, potassium fluoride, etc., alkaline earth metal compounds typified by magnesium fluoride, calcium fluoride, etc., oxidation Examples thereof include metal oxides typified by aluminum, metal complexes typified by lithium 8-hydroxyquinolate (Liq), and the like. Further, the above-described electron transport material can also be used.
Moreover, the material used for said electron injection layer may be used independently, and may be used in combination of multiple types.

<Hole transport layer>
In the present invention, the hole transport layer is made of a material having a function of transporting holes and may have a function of transmitting holes injected from the anode to the light emitting layer.
Although there is no restriction | limiting in particular about the total film thickness of the positive hole transport layer of this invention, Usually, it exists in the range of 5 nm-5 micrometers, More preferably, it exists in the range of 2-500 nm, More preferably, it is 5-200 nm. Within range.

As a material used for the hole transport layer (hereinafter referred to as a hole transport material), any material that has either a hole injection property or a transport property or an electron barrier property may be used. Any one can be selected and used.
For example, porphyrin derivatives, phthalocyanine derivatives, oxazole derivatives, oxadiazole derivatives, triazole derivatives, imidazole derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, hydrazone derivatives, stilbene derivatives, polyarylalkane derivatives, triarylamine derivatives, carbazole derivatives , Indolocarbazole derivatives, isoindole derivatives, acene derivatives such as anthracene and naphthalene, fluorene derivatives, fluorenone derivatives, and polyvinyl carbazole, polymer materials or oligomers with aromatic amines introduced into the main chain or side chain, polysilane, conductive And polymer (for example, PEDOT: PSS, aniline copolymer, polyaniline, polythiophene, etc.).

Examples of the triarylamine derivative include a benzidine type typified by α-NPD, a starburst type typified by MTDATA, and a compound having fluorene or anthracene in the triarylamine linking core part.
In addition, hexaazatriphenylene derivatives such as those described in JP-A-2003-519432 and JP-A-2006-135145 can also be used as a hole transport material.
Furthermore, a hole transport layer having a high p property doped with impurities can also 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.
JP-A-11-251067, J. Org. Huang et. al. It is also possible to use so-called p-type hole transport materials and inorganic compounds such as p-type-Si and p-type-SiC as described in the literature (Applied Physics Letters 80 (2002), p. 139). . Further, ortho-metalated organometallic complexes having Ir or Pt as the central metal as typified by Ir (ppy) ₃ are also preferably used.

  Although the above-mentioned materials can be used as the hole transport material, a triarylamine derivative, a carbazole derivative, an indolocarbazole derivative, an azatriphenylene derivative, an organometallic complex, or an aromatic amine is introduced into the main chain or side chain. The polymer materials or oligomers used are preferably used.

Specific examples of known preferred hole transport materials used in the organic EL device of the present invention include the compounds described in the following documents in addition to the documents listed above, but the present invention is not limited thereto. Not.
For example, Appl. Phys. Lett. 69, 2160 (1996), J. MoI. Lumin. 72-74, 985 (1997), Appl. Phys. Lett. 78, 673 (2001), Appl. Phys. Lett. 90, 183503 (2007), Appl. Phys. Lett. 90, 183503 (2007), Appl. Phys. Lett. 51, 913 (1987), Synth. Met. 87, 171 (1997), Synth. Met. 91, 209 (1997), Synth. Met. 111, 421 (2000), SID Symposium Digest, 37, 923 (2006), J. Am. Mater. Chern. 3, 319 (1993), Adv. Mater. 6, 677 (1994), Chern. Mater. 15, 3148 (2003), U.S. Patent Publication No. 20030162053, U.S. Patent Publication No. 200201558242, U.S. Patent Publication No. 20060240279, U.S. Patent Publication No. 20080220265, U.S. Patent No. 5061569, International Publication No. 2007/002683, International Publication Number. Publication No. 2009/018009, EP650955, U.S. Patent Publication No. 20080124572, U.S. Publication No. 200707078938, U.S. Publication No. 20080106190, U.S. Publication No. 20080018221, International Publication No. 2012/115034, Special Table 2003-519432 And JP-A-2006-135145.
The hole transport materials may be used alone or in combination of two or more.

<Electron blocking layer>
The electron blocking layer is a layer having a function of a hole transport layer in a broad sense. Preferably, it is made of a material that has a function of transporting holes and has a small ability to transport electrons. By blocking electrons while transporting holes, the recombination probability of electrons and holes can be improved. .
Moreover, the structure of the positive hole transport layer mentioned above can be used as an electron blocking layer according to the present invention, if necessary.
The electron blocking layer provided in the organic EL device of the present invention is preferably provided adjacent to the anode side of the light emitting layer.
The film thickness of the electron blocking layer according to the present invention is preferably in the range of 3 to 100 nm, more preferably in the range of 5 to 30 nm.
As the material used for the electron blocking layer, the material used for the above-described hole transport layer is preferably used, and the material used as the above-described host compound is also preferably used for the electron blocking layer.

<Hole injection layer>
The hole injection layer (also referred to as “anode buffer layer”) according to the present invention is a layer provided between the anode and the light emitting layer in order to lower the driving voltage and improve the light emission luminance. 2 and Chapter 2 “Electrode Materials” (pages 123 to 166) of the 2nd edition of “The Forefront of Industrialization” (issued by NTT Corporation on November 30, 1998).
In the present invention, the hole injection layer may be provided as necessary, and may be present between the anode and the light emitting layer or between the anode and the hole transport layer as described above.
The details of the hole injection layer are also described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069, etc. Examples of the material used for the hole injection layer include: Examples thereof include materials used for the above-described hole transport layer.
Among them, phthalocyanine derivatives typified by copper phthalocyanine, hexaazatriphenylene derivatives as described in JP-T-2003-519432, JP-A-2006-135145, etc., metal oxides typified by vanadium oxide, amorphous carbon Preferred are conductive polymers such as polyaniline (emeraldine) and polythiophene, orthometalated complexes represented by tris (2-phenylpyridine) iridium complex, and triarylamine derivatives.
In the present invention, the hole injection layer is provided as necessary, and the above-described orthometalated complexes represented by tris (2-phenylpyridine) iridium complex, triarylamine derivatives and the like are preferable.
The materials used for the hole injection layer described above may be used alone or in combination of two or more.

<Other compounds>
The organic layer in the present invention described above may further contain other compounds.
Examples of other compounds include halogen elements and halogenated compounds such as bromine, iodine and chlorine, alkali metals and alkaline earth metals such as Pd, Ca, and Na, transition metal compounds, complexes, and salts.
The content of the compound can be arbitrarily determined, but is preferably 1000 ppm or less, more preferably 500 ppm or less, and further preferably 50 ppm or less with respect to the total mass% of the contained layer. .
However, it is not within this range depending on the purpose of improving the transportability of electrons and holes or the purpose of favoring the exciton energy transfer.

<Method for forming organic layer>
The method for forming the organic layer (hole injection layer, hole transport layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer, etc.) of the present invention is not particularly limited, and conventionally known, for example, vacuum deposition A formation method using a method, a wet method (also referred to as a wet process) or the like can be used.
Examples of the wet method include spin coating, casting, ink jet, printing, die coating, blade coating, roll coating, spray coating, curtain coating, and LB (Langmuir-Blodgett). From the viewpoint of obtaining a homogeneous thin film easily and high productivity, a method with high roll-to-roll method suitability such as a die coating method, a roll coating method, an ink jet method and a spray coating method is preferable.

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.

Further, a different film forming method may be applied for each layer. When employing a vapor deposition method for film formation, the vapor deposition conditions vary depending on the type of compound used, etc., but generally within a boat heating temperature range of 50 to 450 ° C. and a degree of vacuum of 10 ⁻⁶ to 10 ⁻² Pa. It is desirable to appropriately select the deposition rate within the range of 0.01 to 50 nm / second, the substrate temperature within the range of −50 to 300 ° C., the thickness within the range of 0.1 nm to 5 μm, and preferably within the range of 5 to 200 nm. .
The organic layer of the present invention is preferably formed 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. In that case, it is preferable to perform the work in a dry inert gas atmosphere.

<Anode>
As the anode in the organic EL element, those having a work function (4 eV or more, preferably 4.5 V or more) of a metal, an alloy, an electrically conductive compound and a mixture thereof as an electrode material are 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, a thin film may be formed by depositing these electrode materials 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 required (about 100 μm or more) ), A pattern may be formed through a mask having a desired shape when the electrode material is deposited or sputtered.

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 is greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less.
The film thickness of the anode depends on the material, but is usually selected within the range of 10 nm to 1 μm, preferably within the range of 10 to 200 nm.

<Cathode>
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, aluminum, 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 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 in the range of 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 emission luminance is advantageously improved.
Moreover, after producing the said metal with the film thickness in the range of 1-20 nm in a cathode, the transparent or semi-transparent cathode can be produced by producing the electroconductive transparent material mentioned by description of an anode on it. By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.

<Support substrate>
The 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 is not particularly limited in the type of glass, plastic, etc., and 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 (TAC), cellulose acetate butyrate, cellulose acetate propionate ( CAP), cellulose esters such as cellulose acetate phthalate, 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.

An inorganic film, an organic film, or a hybrid film of both may be formed on the surface of the resin film, and the water vapor permeability (25 ± 0.5 ° C.) measured by a method according to JIS K 7129-1992. , Relative humidity (90 ± 2)% RH) is preferably a barrier film having 1 × 10 ⁻² g / (m ² · 24 h) or less, and further measured by a method based on JIS K 7126-1987. Is a high barrier film having an oxygen permeability of 1 × 10 ⁻³ ml / (m ² · 24 h · atm) or less and a water vapor permeability of 1 × 10 ⁻⁵ g / (m ² · 24 h) or less. It 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.
Furthermore, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and layers made of organic materials. 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 quantum efficiency at room temperature of light emission of the organic EL device of the present invention is preferably 1% or more, and more preferably 5% or more.
Here, the external extraction quantum efficiency (%) = the number of photons emitted to the outside of the organic EL element / the 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.

<Sealing>
Examples of the sealing means used for sealing the organic EL element of the present invention include a method of bonding a sealing member, an electrode, and a support substrate with an adhesive.
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 it may be concave plate shape or flat plate shape. Moreover, 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 organic EL 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-component 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, the thing which can be adhesively cured 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.
Furthermore, 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. There are no particular limitations on the method of forming these films. 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 can also be used. 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, and the like), 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 the sealing film. In particular, when 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, but the polymer film is light and thin. Is preferably used.

<Light extraction improvement technology>
An organic EL element emits light inside a layer having a refractive index higher than that of air (within a refractive index of about 1.6 to 2.1), and is about 15% to 20% of light generated in the light emitting layer. It is generally said that it can only be taken out.
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 element, or between the transparent electrode or light emitting layer and the transparent substrate. This is because 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 side surface of the device.
As a technique 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 transparent substrate and the air interface (for example, US Pat. No. 4,774,435), A method for improving efficiency by providing light condensing property (for example, JP-A-63-314795), a method for forming a reflective surface on a side surface of an element (for example, JP-A-1-220394), a substrate, etc. A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the substrate and the light emitter (for example, Japanese Patent Application Laid-Open No. 62-172691), lower refraction than the substrate between the substrate and the light emitter A method of introducing a flat layer having a refractive index (for example, Japanese Patent Application Laid-Open No. 2001-202827), and a method of forming a diffraction grating between any one of the substrate, the transparent electrode layer and the light emitting layer (including between the substrate and the outside) ( JP-A-11 No. 283,751 Publication), and the like.

In the present invention, these methods can be used in combination with the organic EL device of the present invention, but a method of introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter, or the substrate, A method of forming a diffraction grating between any layers of the transparent 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 low refractive index medium 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. Become.

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 in the range of about 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less. Furthermore, it is preferable that it is 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 exuded by evanescent enters the substrate.
The method of introducing a diffraction grating into an interface that causes total reflection or in any medium 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 or second-order diffraction. The light that cannot be emitted due to total internal reflection between layers is diffracted by introducing a diffraction grating into any layer or medium (in the transparent substrate or transparent electrode). , Trying to extract light 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. 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.
The position where the diffraction grating is introduced may be in any of the layers or in the medium (in the transparent substrate or 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 within a range of about 1/2 to 3 times the wavelength of light in the medium.
The arrangement of the diffraction gratings is preferably two-dimensionally repeated, such as a square lattice, a triangular lattice, or a honeycomb lattice.

<Condensing sheet>
The organic electroluminescence device of the present invention is processed in such a manner that a structure on a microlens array is provided on the light extraction side of a support substrate (substrate) or is combined with a so-called condensing sheet, for example, in a specific direction, for example, the device Condensing light in the front direction with respect to the light emitting surface can increase the luminance in a specific direction.
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 within a range of 10 to 100 μm. If the thickness is smaller than this, a diffraction effect is generated and coloring occurs, and if it is too large, the thickness increases, which 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 an organic EL element, you may use a light-diffusion plate and a film together with a condensing sheet. For example, a diffusion film (light-up) manufactured by Kimoto Co., Ltd. can be used.

[Display device]
The organic EL element of the present invention 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. Alternatively, a single emission color, for example, white emission, can be changed to BGR using a color filter to achieve full color.
Furthermore, it is possible to convert the organic EL light emission color into another color by using a color conversion filter, and in this case, it is preferable that λmax of the organic EL light emission is 480 nm or less.

  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. .

  Moreover, you may use as an organic EL element which gave the organic EL element of this invention the resonator structure. Examples of the purpose of use of the organic EL element having such a resonator structure include a light source of an optical storage medium, a light source of an electrophotographic copying machine, a light source of an optical communication processing machine, and a light source of an optical sensor. It is not limited. Moreover, you may use for the said use by making a laser oscillation.

  An example of a display device composed of organic EL elements will be described below with reference to the drawings.

  FIG. 1 is a schematic diagram illustrating an example of a display device including 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 the plurality of pixels based on image information from the outside. The pixels for each scanning line are converted into image data signals by the scanning signal. In response to this, light is sequentially emitted and image scanning is performed to display 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. FIG. 2 shows a case where the light L emitted from the pixel 3 is extracted in the direction of the white arrow (downward).

  The scanning lines 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 orthogonal positions (details are shown in FIG. Not shown).

  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 that emit light on the same substrate.

  Next, the light emission process of the pixel will be described.

  FIG. 3 is a schematic diagram of a pixel circuit.

  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 of 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, and the power supply line 7 connects to the organic EL element 10 according 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 if 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 element 10 of each of the plurality of pixels, and the light emission of the organic EL element 10 of each of the plurality of pixels 3. 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 on / off of a predetermined light emission amount by a binary image data signal. But you can.

  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 pixel 3 connected to the applied scanning line 5 emits 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.

  A combination of light emitting materials for obtaining a plurality of emission colors includes a combination of a plurality of phosphorescent or fluorescent materials (dopants), a light emitting material that emits fluorescence or phosphorescence, and the light emitting material. However, in the white organic EL device according to the present invention, a method of combining a plurality of dopants is preferable.

  As a layer structure of the organic EL element for obtaining a plurality of emission colors, a method of having a plurality of dopants exist in one emission layer, a plurality of emission layers, and different emission wavelengths in each emission layer Examples thereof include a method in which a dopant is present, and a method in which minute pixels emitting light having different wavelengths are formed in a matrix.

  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 at the time of film formation, if necessary. When patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire element layer may be patterned.

  The light emitting material used for the light emitting layer is not particularly limited. For example, in the case of a backlight in a liquid crystal display element, the platinum complex according to the present invention is adapted so as to conform to the wavelength range corresponding to the CF (color filter) characteristics, Moreover, what is necessary is just to select and combine arbitrary things from well-known luminescent materials, and to whiten.

[Lighting device]
The lighting device of the present invention includes home lighting, interior lighting, clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources of optical storage media, exposure light sources of electrophotographic copying machines, light sources of optical communication processors, and optical sensors. However, it is not limited to these.

  One aspect of the lighting device of the present invention including 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 300 μm thick glass substrate is used as a sealing substrate, and an epoxy photocurable adhesive (LUX The track 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, sealed, and illuminated as shown in FIGS. A device can be formed.

  FIG. 5 shows a schematic diagram of the lighting device.

  As shown in FIG. 5, the organic EL element 101 is covered with a glass cover 102.

  The sealing operation with the glass cover 102 is preferably performed in a glove box (in an atmosphere of high purity nitrogen gas having a purity of 99.999% or more) in a nitrogen atmosphere without bringing the organic EL element 101 into contact with the atmosphere.

  FIG. 6 shows a cross-sectional view of the lighting device.

  As shown in FIG. 6, the lighting device mainly includes a cathode 105, an organic EL layer 106, and a glass substrate 107 with a transparent electrode, and these members are covered with a glass cover 102.

  The glass cover 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided.

  As described above, the organic EL element of the present invention is not only the display device and the display, but also various light emitting sources, lighting devices, household lighting, interior lighting, as a kind of lamp such as an exposure light source, and liquid crystal. It is also useful for display devices such as backlights for display devices.

  In addition, backlights such as clocks, signboard advertisements, traffic lights, light sources such as optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processing machines, light sources for optical sensors, etc. There are a wide range of uses such as household appliances.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
In addition, the compound used in the following Examples 1 and 2 is shown.

[Example 1]
In order to confirm the usefulness of the palladium (IV) complex of the present invention, a thin film was formed by the following method, and the light emission intensity (quantum yield) and the temporal stability of the light emission intensity were examined.

<Manufacture of thin film-28>
A quartz substrate of 30 mm × 30 mm × 1.1 mm was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, subjected to UV ozone cleaning for 5 minutes, and then attached to a commercially available spin coater. Separately, a palladium complex of the present invention, Pd-245 and 5mg of polymethyl methacrylate 3.6 mg; dissolving (manufactured by Aldrich weight average molecular weight Mw120000) in 1mL tetrahydrofuran (THF), about 5 × 10 in terms of Pd ^{- A 3} mol / L solution was prepared. This solution was formed on the above-mentioned quartz substrate by spin coating under conditions of 1500 rpm and 30 seconds, and further dried under vacuum at 25 ° C. for 1 hour to obtain “thin film-28”.

<Manufacture of thin films 01-27, 29 and 30>
In the manufacture of the “thin film-28”, “thin films-01 to 27, 29, and 30” were obtained by using palladium complexes (Pd complexes) shown in Table 1 instead of Pd-245.

<Evaluation of palladium complex>
About "thin film -01-30" obtained above, each evaluation was performed according to the following method.
(1) Quantum yield According to a conventional method, the quantum yield of the obtained thin film was calculated using a spectrofluorimeter (F-4500 type, manufactured by Hitachi High-Tech).

(2) Stability over time In the glove box, the thin film obtained above was emitted using a spot light source (LC-8 manufactured by Hamamatsu Photonics), and a spectral radiance meter (CS-1000 manufactured by Konica Minolta Optics) was used. Used for luminance monitoring.
The light source intensity was adjusted so that the initial luminance was 100,000 cd / cm ² and irradiation was performed for 60 minutes. The ratio of luminance after 60 minutes to initial luminance (% display) was defined as stability over time. That is, if the luminance after 60 minutes is 100,000 cd / cm ² and there is no decrease in luminance, then 100,000 (after 60 minutes) / 100,000 (initial) × 10 = 100%.

  In Table 1, the quantum yield and the stability over time of “Thin Film-30” are shown as relative values with respect to 100. The results are shown in Table 1. The larger the number, the better the stability over time.

From the results shown in Table 1, the palladium (IV) complex of the present invention ("thin film-01 to 29"), compared with the palladium (II) complex ("thin film-30") whose luminescence was confirmed , “−01 to 10” are reference examples. It is clear that) is excellent in light-emitting property. This is presumed that the geometric change around the palladium atom in the ground state and the excited state was suppressed, and the non-radiative deactivation, which is usually considered to be large, was suppressed. With regard to the stability over time, the stability improvement of the palladium (IV) complex is clear, and in particular, the stability improvement is observed with the complex containing a carbene species in the ligand structure.

[Example 2]
As shown below, “organic EL elements 1-1 to 1-4” were prepared using a palladium complex as a light-emitting dopant.

<Preparation of Organic EL Element 1-1>
Patterning was performed on a substrate (NA-45, manufactured by AvanStrate Co., Ltd.) in which ITO (Indium Tin Oxide) was formed to a thickness of 100 nm on a glass substrate of 100 mm × 100 mm × 1.1 mm as an anode. Thereafter, the transparent support substrate provided 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.
On this transparent support substrate, poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS (HT-1), Baytron P Al4083, Baytron P Al4083) was diluted to 70% with pure water. A thin film was formed by spin coating using the solution, and then dried at 200 ° C. for 1 hour to provide a first hole transport layer having a thickness of 30 nm.
Next, 20 mg of 1,3-bis (carbazol-9-yl) benzene (mCP) and 1 mg of Pd-131 as a palladium complex of the present invention are dissolved in 2 mL of toluene, and a thin film is formed by spin coating. did. Heat-dried at 80 degreeC for 1 hour, and provided the light emitting layer with a film thickness of 40 nm.
Next, the substrate on which the light emitting layer was formed was attached to a vacuum deposition apparatus. After the pressure in the vacuum chamber was reduced to 4 × 10 ⁻⁴ Pa, tris (8-quinolinolato) aluminum (Alq ₃ ) as an electron transport material was deposited by 20 nm to provide an electron transport layer.
Subsequently, lithium fluoride is vapor-deposited to form a 1.0-nm-thick cathode buffer layer, and aluminum is further vapor-deposited to form a 110-nm-thick cathode, thereby producing “organic EL element 1-1”. did.

<Preparation of organic EL elements 1-2 to 1-4>
In the production of the “organic EL element 1-1”, a Pd complex described in Table 2 was used instead of the light-emitting dopant Pd-131 in the light-emitting layer of the “organic EL element 1-1”. Elements 1-2 to 1-4 "were fabricated.

<Evaluation of organic EL element>
Each evaluation was performed according to the following method about "organic EL element 1-1 to 1-4" produced as mentioned above.
(1) Evaluation of luminous efficiency For each organic EL element, an external extraction quantum efficiency (%) was measured when a constant current of ^2.5 mA / cm ² was applied at a room temperature of 23 ° C. in a dry nitrogen gas atmosphere. It was used as an index of luminous efficiency. For the measurement, a spectral radiance meter CS-1000 (manufactured by Konica Minolta Optics) was used.
The luminous efficiency was expressed as a relative value when the measured value of the external extraction quantum efficiency of the organic EL element 1-4 was 100. It represents that it is excellent in luminous efficiency, so that a numerical value is large.

(2) Evaluation of durability (half life) Each organic EL element was driven at a constant current under a constant environmental condition of 50 ° C. with a current giving an initial luminance of 1000 cd / m ^2, and 1/2 of the initial luminance (500 cd) / M ² ) The time required to reach (m ² ) (half life at high temperature storage) was determined and used as a measure of durability.
Durability was calculated | required by the relative value which set the half life of the organic EL element 1-4 to 100. The larger the value, the longer the device life and the better the durability.

From the results shown in Table 2, “organic EL elements 1-1 to 1-3” containing the palladium (IV) complex of the present invention (where “organic EL element 1-1” is used as a reference example) are shown . It is recognized that the light emitting efficiency and the durability are excellent as compared with “organic EL element 1-4” containing a palladium (II) complex.

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 A Display part B Control part 102 Glass cover 105 Cathode 106 Organic EL layer 107 Glass substrate with a transparent electrode

Claims (8)

An organic electroluminescence element having at least an anode, a cathode, and a light emitting layer, wherein the light emitting layer contains a palladium complex having a structure represented by the following general formula ( 2 ) .

[Wherein, Pd represents a tetravalent palladium atom having a coordination number of 6; Ring A represents an aromatic ring or a non-aromatic ring formed with Y ₁ and a carbon atom, and further represents a halogen atom, a nitro group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, or a disubstituted ring You may have an amino group or a C1-C20 linear or branched alkyl group. These substituents may be bonded to each other to form a ring. Y ₁ represents a carbon atom or a nitrogen atom. X _{1 to} X ₄ are atomic groups that form a 5-membered aromatic heterocyclic ring or a non-aromatic heterocyclic ring together with a carbene carbon atom coordinated to Pd, and are each a carbon atom, C—R ₁ , a nitrogen atom, N—R ₁ represents an oxygen atom or a sulfur atom, and at least one represents a nitrogen atom or N—R ₁ . R ₁ represents a hydrogen atom or a substituent. L ₁ represents a bidentate ligand coordinated to Pd. p and q represent an integer of 1 or more and satisfy the relational expression of p + q = 3. When q is 2, the two L ₁ are different from each other. ] The organic electroluminescent device according to claim 1 , wherein the ring A in the general formula (2) represents a 5-membered or 6-membered aromatic ring or non-aromatic ring. The organic complex according to claim 1 or 2 , wherein the palladium complex having a structure represented by the general formula (2) is a palladium complex having a structure represented by the following general formula (3). Electroluminescence element.

[In the formula, Pd represents a coordination number of 6 and a tetravalent palladium atom. Y _{2 to} Y ₆ are an atomic group forming a 6-membered aromatic ring or a non-aromatic ring together with a carbon atom coordinated to Pd, and represent a carbon atom, C—R ₂ or a nitrogen atom. X ₅ and X ₆ are an atomic group forming a 5-membered aromatic heterocycle or a non-aromatic heterocycle together with a carbene carbon atom and a nitrogen atom, and represent C—R ₃ or a nitrogen atom. R ₂ and R ₃ represent a hydrogen atom or a substituent, and R ₄ represents a substituent. L ₁ represents a bidentate ligand coordinated to Pd. p and q represent an integer of 1 or more and satisfy the relational expression of p + q = 3. When q is 2, the two L ₁ are different from each other. ] The organic electroluminescent device according to claim 3 , wherein the palladium complex having a structure represented by the general formula (3) is a palladium complex having a structure represented by the following general formula (4).

[Wherein, Pd represents a tetravalent palladium atom having a coordination number of 6; X ₇ and X ₈ are an atomic group forming a 5-membered aromatic heterocyclic ring or a non-aromatic heterocyclic ring together with a carbene carbon atom and a nitrogen atom, and represent C—R ₃ or a nitrogen atom. R ₃ and R _{6 to} R ₉ represent a hydrogen atom or a substituent, and R ₅ represents a substituent. L ₁ represents a bidentate ligand coordinated to Pd. p and q represent an integer of 1 or more and satisfy the relational expression of p + q = 3. When q is 2, the two L ₁ are different from each other. ] The organic electroluminescence element according to any one of claims 1 to 4 , wherein the organic electroluminescence element has a plurality of light emitting layers. The organic electroluminescence element according to any one of claims 1 to 5, wherein the organic electroluminescence element contains two or more kinds of light emitting elements and the emission color is white. A display device comprising the organic electroluminescence element according to any one of claims 1 to 6 . The organic electroluminescent element as described in any one of Claim 1- Claim 6 is comprised, The illuminating device characterized by the above-mentioned.

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