JP2006228936A - Organic electroluminescence element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescence element with high emission efficiency and high durability. <P>SOLUTION: The organic electroluminescence element sandwiches at least one organic layer comprising a light emitting layer between a pair of electrodes. The organic layer comprises a metal complex having a partial structure displayed by a following general formula (1). In the general formula (1), M<SP>1</SP>and M<SP>2</SP>show metal ions. Then, X<SP>1</SP>and X<SP>2</SP>show carbon atoms, nitrogen atoms, oxygen atoms, silica atoms, phosphorous atoms or sulfur atoms. R<SP>1</SP>and R<SP>2</SP>show substituents. If possible, they are mutually connected and they can form a ring. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic electroluminescence device, and more particularly, to a high luminance and high efficiency organic electroluminescence device using a specific metal complex compound.

  Organic electroluminescent elements (organic EL elements) have been actively researched and developed in recent years because they can emit light with high brightness when driven at a low voltage. In general, an organic EL element is composed of an organic layer including a light emitting layer and a pair of electrodes sandwiching the layer, and the electrons injected from the cathode and the holes injected from the anode are recombined in the light emitting layer. Utilizing light emission from the excited excitons.

In recent years, the use of phosphorescent light emitting materials has led to higher efficiency of devices. Known phosphorescent materials include iridium complexes and platinum complexes (for example, Patent Document 1 and Patent Document 2). However, durability is still inadequate, and problems such as reduction in driving voltage and further improvement in efficiency remain. Furthermore, when considering application to displays, blue, green, and red high-purity light emission is necessary. In particular, high-purity blue phosphorescent light-emitting elements are highly difficult to develop, and have sufficient performance so far. No element has been developed yet.
US Pat. No. 6,303,238 International Publication No. 00/057676 Pamphlet

  An object of the present invention is to provide an organic electroluminescent device having high luminous efficiency and high durability. Another object of the present invention is to provide a metal complex compound suitable for providing the organic electroluminescent device.

  This problem has been solved by using a specific metal complex in at least one organic layer of the organic electroluminescence device. In particular, the problem has been solved by the means described below.

[1] An organic electroluminescent device having at least one organic layer including a light emitting layer between a pair of electrodes, wherein the organic layer contains a metal complex having a partial structure represented by the following general formula (1) An organic electroluminescent element.

(In general formula (1), M ¹ and M ² each independently represent a metal ion. X ¹ and X ² each independently represent a carbon atom or a nitrogen atom. R ¹ and R ² are each independently substituted. Group may be combined with each other to form a ring if possible.)

[2] The organic electroluminescent element as described in [1], wherein the metal complex having a partial structure represented by the general formula (1) is represented by the following general formula (2).

(In General Formula (2), M ¹ and M ² each independently represent a metal ion. X ¹ and X ² each independently represent a carbon atom or a nitrogen atom. Q ² is necessary for forming an aromatic ring. Represents an atomic group.)
[3] The organic electroluminescent element as described in [1] or [2], wherein the metal complex having a partial structure represented by the general formula (1) is represented by the following general formula (3).

(In the general formula (3), M ³¹ , M ³² and M ³³ each independently represents a metal ion. X ³¹ , X ³² , X ³³ , X ³⁴ , X ³⁵ and X ³⁶ are each independently a carbon atom, or Represents a nitrogen atom, and Q ³¹ , Q ³² and Q ³³ each independently represents an atomic group necessary for forming an aromatic ring.
[4] The organic electric field according to [1] or [2], wherein the metal complex having a partial structure represented by the general formula (1) is a compound represented by the following general formula (4): Light emitting element.

(In the general formula (4), M ⁴¹ and M ⁴² each independently represent a metal ion. X ⁴¹ , X ⁴² , X ⁴³ and X ⁴⁴ each independently represent a carbon atom or a nitrogen atom. Q ⁴¹ and Q ⁴² independently represents an atomic group necessary for forming an aromatic ring, and Q ⁴³ and Q ⁴⁴ represent an atomic group necessary for forming a nitrogen-containing aromatic heterocycle.
[5] The metal ions M ¹ , M ² , M ³¹ , M ³² , M ³³ , M ⁴¹ and M ⁴² are metal ions belonging to Group 11 of the periodic table [1] to [4] The organic electroluminescent element according to any one of the above.
[6] The metal ions M ¹ , M ² , M ³¹ , M ³² , M ³³ , M ⁴¹ and M ⁴² are monovalent metal ions of Group 11 of the periodic table [1] to [5] The organic electroluminescent element according to any one of [5].
[7] Any one of [1] to [6], wherein the metal ions M ¹ , M ² , M ³¹ , M ³² , M ³³ , M ⁴¹ and M ⁴² are monovalent copper ions. The organic electroluminescent element of description.
[8] The light-emitting layer contains at least one metal complex according to [1] to [7] and at least one metal complex host material, [1] to [7] Organic electroluminescent device.
[9] Any one of [1] to [7], wherein the light emitting layer contains at least one metal complex according to [1] to [7] and at least one host material that is not a metal complex. The organic electroluminescent element of description.
[10] The organic electroluminescence according to any one of [1] to [9], wherein the organic electroluminescence has at least one hole injection layer, and the material constituting the hole injection layer is copper phthalocyanine element.
[11] The material having at least one hole transport layer, and the material constituting the hole transport layer is a material containing at least two triarylamine skeletons. ] The organic electroluminescent element in any one of.
[12] The organic material according to any one of [1] to [11], which has at least one electron transport layer, and a material constituting the electron transport layer is a compound that is not a metal complex Electroluminescent device.
[13] The organic material according to any one of [1] to [12], which has at least one electron transport layer, and a material constituting the electron transport layer is an aluminum complex or a gallium complex. Electroluminescent device.
[14] The organic electroluminescent element as described in any one of [1] to [13], which has at least one hole injection layer, hole transport layer, and electron transport layer in addition to the light emitting layer .
[15] The organic electroluminescent element as described in any one of [1] to [14], which has an electron blocking layer between the light emitting layer and the hole transport layer.
[16] The organic electroluminescent element as described in any one of [1] to [16], wherein a hole blocking layer is provided between the light emitting layer and the electron transport layer.
[17] The organic layer is formed by laminating a hole injection layer, a hole transport layer, an electron block layer, a light emitting layer, a hole block layer, and an electron transport layer in this order from the anode side. ] The organic electroluminescent element in any one of-[16].
[18] The organic electroluminescent element as described in any one of [1] to [17], wherein the light emitting layer is formed by a wet process.
[19] The organic electroluminescent element as described in any one of [1] to [18], wherein the light emitting layer is formed by a coating method.

  According to the present invention, it is possible to provide an organic electroluminescent device having high emission luminance, high external quantum efficiency, high durability, and excellent color purity. Furthermore, by using a metal complex compound having a specific structure, an organic electroluminescent device capable of emitting blue light with high color purity can be provided.

Hereinafter, the organic EL device of the present invention will be described in detail. The organic EL device of the present invention has at least one organic layer including a light emitting layer between a pair of electrodes. The organic EL device of the present invention is characterized in that the organic layer contains a binuclear metal complex having a specific structure.
In the organic EL device of the present invention, in addition to the light emitting layer, a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, a hole block layer, an electron block layer, an exciton block layer, a protective layer and the like are appropriately provided. It may be arranged. Each of these layers may have other functions.

  The function of the binuclear metal complex of the present invention is not limited and may be contained in any of the organic layers, but is preferably contained in the light emitting layer, and particularly as a light emitting material in the light emitting layer. It is preferable to contain.

  The binuclear metal complex of the present invention is a metal complex having a partial structure represented by the following general formula (1).

(In general formula (1), M ¹ and M ² each independently represent a metal ion. X ¹ and X ² each independently represent a carbon atom or a nitrogen atom. R ¹ and R ² are each independently substituted. Group may be combined with each other to form a ring if possible.)

The general formula (1) will be described. M ¹ and M ² represent metal ions. M ¹ and M ² may be the same or different, and are preferably the same metal ion. M ¹ and M ² are preferably transition metal ions, more preferably Group 10 (Ni, Pd, Pt), Group 11 (Cu, Ag, Au), Group 12 (Zn, Cd, Hg). ), More preferably group 10 and group 11 metal ions, still more preferably group 11 metal ions, and particularly preferably monovalent group 11 metal ions (Cu ^+). , Ag ⁺ , Au ⁺ ), and most preferably monovalent copper ions.

X ¹ and X ² represent a carbon atom or a nitrogen atom, and may be the same or different. The bond between X ¹ and X ² and M ¹ and M ² is drawn with a solid line, but the bond type is not limited. X ¹ and X ² are carbon atoms or nitrogen atoms. R ¹ and R ² represent a substituent that may be bonded to each other to form a ring. When R ¹ and R ² do not form a ring, the substituent represented by R ¹ or R ² is an alkyl group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and particularly preferably carbon atoms). Examples thereof include methyl, ethyl, iso-propyl, tert-butyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl and the like, and an alkenyl group (preferably. 2-30 carbon atoms, more preferably 2-20 carbon atoms, particularly preferably 2-10 carbon atoms, such as vinyl, allyl, 2-butenyl, 3-pentenyl, etc.), alkynyl groups (preferably It has 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include propargyl and 3-pentynyl. An aryl group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenyl, p-methylphenyl, naphthyl, anthranyl, etc.) An amino group (preferably having 0 to 30 carbon atoms, more preferably 0 to 20 carbon atoms, particularly preferably 0 to 10 carbon atoms, such as amino, methylamino, dimethylamino, diethylamino, dibenzylamino, Diphenylamino, ditolylamino, etc.), alkoxy groups (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 10 carbon atoms, such as methoxy, ethoxy, butoxy, 2 -Ethylhexyloxy and the like), an aryloxy group (preferably having 6 to 30 carbon atoms, more Preferably, it has 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyloxy, 1-naphthyloxy, 2-naphthyloxy and the like, and a heterocyclic oxy group (preferably having 1 carbon atom). To 30, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as pyridyloxy, pyrazyloxy, pyrimidyloxy, quinolyloxy, etc.), acyl groups (preferably 1 to 30 carbon atoms, More preferably, it is C1-C20, Most preferably, it is C1-C12, for example, acetyl, benzoyl, formyl, pivaloyl etc. are mentioned), an alkoxycarbonyl group (preferably C2-C30, more preferably). Having 2 to 20 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonyl, ethoxy Such as carbonyl, and the like. ), An aryloxycarbonyl group (preferably having a carbon number of 7 to 30, more preferably a carbon number of 7 to 20, particularly preferably a carbon number of 7 to 12, such as phenyloxycarbonyl), an acyloxy group (preferably Has 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include acetoxy and benzoyloxy.), An acylamino group (preferably 2 to 30 carbon atoms, More preferably, it has 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include acetylamino, benzoylamino and the like, and an alkoxycarbonylamino group (preferably 2 to 30 carbon atoms, more preferably carbon atoms). 2 to 20, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonylamino An aryloxycarbonylamino group (preferably having 7 to 30 carbon atoms, more preferably 7 to 20 carbon atoms, and particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonylamino). A sulfonylamino group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methanesulfonylamino and benzenesulfonylamino), a sulfamoyl group (Preferably having 0 to 30 carbon atoms, more preferably 0 to 20 carbon atoms, and particularly preferably 0 to 12 carbon atoms. Examples thereof include sulfamoyl, methylsulfamoyl, dimethylsulfamoyl, and phenylsulfamoyl. ), A carbamoyl group (preferably having 1 to 30 carbon atoms, more preferably A prime number of 1-20, particularly preferably a carbon number of 1-12, such as carbamoyl, methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl, etc., an alkylthio group (preferably having a carbon number of 1-30, more preferably a carbon number). 1 to 20, particularly preferably 1 to 12 carbon atoms, for example, methylthio, ethylthio, etc.), arylthio groups (preferably 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably carbon atoms). And a heterocyclic thio group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and particularly preferably 1 to 12 carbon atoms. Pyridylthio, 2-benzimidazolylthio, 2-benzoxazolylthio, 2-benzthiazolylthio Etc. ), A sulfonyl group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms such as mesyl and tosyl), a sulfinyl group (preferably carbon). 1 to 30, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methanesulfinyl, benzenesulfinyl, etc.), ureido group (preferably 1 to 30 carbon atoms, more Preferably it is C1-C20, Most preferably, it is C1-C12, for example, ureido, methylureido, phenylureido etc. are mentioned), phosphoric acid amide group (preferably C1-C30, more preferably It has 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms. Examples thereof include diethyl phosphoric acid amide and phenyl phosphoric acid amide. Hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group Group, heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, and examples of the hetero atom include a nitrogen atom, an oxygen atom, and a sulfur atom, specifically imidazolyl, pyridyl, Quinolyl, furyl, thienyl, piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, carbazolyl group, azepinyl group, etc.), silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 3 carbon atoms) 30, particularly preferably 3 to 24 carbon atoms, such as trimethylsilyl, And silyloxy groups (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, and particularly preferably 3 to 24 carbon atoms. For example, trimethylsilyloxy, triphenylsilyloxy, etc. And the like. These substituents may further have a substituent.
When R ¹ and R ² are bonded to each other to form a ring, examples of the ring formed include a pyrrole ring, a pyrazole ring, an imidazole ring, a triazole ring, an oxazole ring, a thiazole ring, a tetrazole ring, a benzene ring, and a pyridine ring. , Pyrimidine ring, pyrazine ring, pyridazine ring, triazine ring, tetrazine ring, oxadiazine ring, thiadiazine ring and the like. The ring formed by bonding R ¹ and R ² to each other may further have a substituent, and other rings may be condensed. As the substituent, those exemplified as the substituents represented by R ¹ and R ² in the general formula (1) can be applied.

R ¹ and R ² are preferably an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a heterocyclic oxy group, or a group in which R ¹ and R ² are combined to form a ring, and more preferably an alkyl group A group, an alkoxy group, or a group in which R ¹ and R ² are combined to form a ring, and more preferably a group in which R ¹ and R ² are combined to form a ring.
The ring formed by combining R ¹ and R ² is preferably a pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, benzene ring, pyridine ring, pyrimidine ring, or pyrazine ring, more preferably , Pyrazole ring, imidazole ring, triazole ring, benzene ring, pyridine ring, pyrimidine ring, or pyrazine ring, more preferably a pyrazole ring, imidazole ring, triazole ring, or pyridine ring, and particularly preferably a pyrazole ring. , An imidazole ring, or a pyridine ring.

  When there are a plurality of partial structures represented by the general formula (1), these partial structures may be equal to or different from each other.

Of the metal complexes having a partial structure represented by the general formula (1), a metal complex having a partial structure represented by the following general formula (2) is more preferable.

(In General Formula (2), M ¹ and M ² each independently represent a metal ion. X ¹ and X ² each independently represent a carbon atom or a nitrogen atom. Q ² is necessary for forming an aromatic ring. Represents an atomic group.)

The general formula (2) will be described. M ¹ , M ² , X ¹ and X ² are synonymous with those in the general formula (1), and preferred ranges are also the same. Q ² represents an atomic group necessary for forming an aromatic ring. Examples of the aromatic ring formed by Q ² include pyrrole ring, pyrazole ring, imidazole ring, triazole ring, oxazole ring, thiazole ring, tetrazole ring, benzene ring, pyridine ring, pyrimidine ring, pyrazine ring, pyridazine ring, triazine ring, A tetrazine ring, an oxadiazine ring, a thiadiazine ring, and the like. Preferred are a pyrrole ring, a pyrazole ring, an imidazole ring, a triazole ring, a tetrazole ring, a benzene ring, a pyridine ring, a pyrimidine ring, and a pyrazine ring, and more preferably a pyrazole ring. Ring, imidazole ring, triazole ring, benzene ring, pyridine ring, pyrimidine ring or pyrazine ring, more preferably pyrazole ring, imidazole ring, triazole ring or pyridine ring, particularly preferably pyrazole ring, imidazo. A Le ring or a pyridine ring. These rings may further have a substituent, and other rings may be condensed. As the substituent, those exemplified as the substituents represented by R ¹ and R ² in the general formula (1) can be applied.

  When there are a plurality of partial structures represented by the general formula (2), these partial structures may be equal to or different from each other.

  Of the metal complexes having a partial structure represented by the general formula (1), a metal complex represented by the following general formula (3) is more preferable.

(In the general formula (3), M ³¹ , M ³² and M ³³ each independently represents a metal ion. X ³¹ , X ³² , X ³³ , X ³⁴ , X ³⁵ and X ³⁶ are each independently a carbon atom, or Represents a nitrogen atom, Q ³¹ , Q ³² and Q ³³ each independently represents an atomic group necessary for forming an aromatic ring.

The metal complex represented by the general formula (3) will be described. M ³¹ , M ³² and M ³³ represent metal ions and have the same meanings as M ¹ and M ² . M ³¹ , M ³² and M ³³ may be the same or different, and are preferably the same metal ion.

X ³¹ , X ³² , X ³³ , X ³⁴ , X ³⁵ and X ³⁶ each independently represent a carbon atom or a nitrogen atom, and may be the same or different. X ³¹ , X ³² , X ³³ , X ³⁴ , X ³⁵ and X ³⁶ are preferably carbon atoms or nitrogen atoms.

Q ³¹ , Q ³² and Q ³³ represent an atomic group necessary for forming an aromatic ring. Examples of the aromatic ring formed by Q ³¹ , Q ³² and Q ³³ include pyrrole ring, pyrazole ring, imidazole ring, triazole ring, oxazole ring, thiazole ring, tetrazole ring, benzene ring, pyridine ring, pyrimidine ring, pyrazine ring, Examples include pyridazine ring, triazine ring, tetrazine ring, oxadiazine ring, thiadiazine ring, and preferably pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, benzene ring, pyridine ring, pyrimidine ring, or pyrazine ring. More preferably a pyrazole ring, an imidazole ring, a triazole ring, a benzene ring, a pyridine ring, a pyrimidine ring or a pyrazine ring, still more preferably a pyrazole ring, an imidazole ring, a triazole ring or a pyridine ring, particularly Preferably Pila Zole ring, imidazole ring, or pyridine ring. These rings may further have a substituent, and other rings may be condensed. As the substituent, those exemplified as the substituents represented by R ¹ and R ² in the general formula (1) can be applied.

  Of the metal complexes having a partial structure represented by the general formula (1), a metal complex represented by the following general formula (4) is preferable.

(In the general formula (4), M ⁴¹ and M ⁴² each independently represent a metal ion. X ⁴¹ , X ⁴² , X ⁴³ and X ⁴⁴ each independently represent a carbon atom or a nitrogen atom. Q ⁴¹ and Q ⁴² represents an atomic group necessary to independently form an aromatic ring, and Q ⁴³ and Q ⁴⁴ each independently represent an atomic group necessary to form a nitrogen-containing aromatic heterocycle.

The metal complex represented by the general formula (4) will be described. M ⁴¹ and M ⁴² represent metal ions and have the same meanings as M ¹ and M ² . M ⁴¹ and M ⁴² may be the same or different, and are preferably the same metal ion.

X ⁴¹ , X ⁴² , X ⁴³ and X ⁴⁴ represent a carbon atom or a nitrogen atom and may be the same or different. X ⁴¹ , X ⁴² , X ⁴³ and X ⁴⁴ are preferably carbon atoms or nitrogen atoms.

Q ⁴¹ and Q ⁴² represent an atomic group necessary for forming an aromatic ring. Examples of the aromatic ring formed by Q ⁴¹ and Q ⁴² include a pyrrole ring, pyrazole ring, imidazole ring, triazole ring, oxazole ring, thiazole ring, tetrazole ring, benzene ring, pyridine ring, pyrimidine ring, pyrazine ring, pyridazine ring, A triazine ring, a tetrazine ring, an oxadiazine ring, a thiadiazine ring, and the like, preferably a pyrrole ring, a pyrazole ring, an imidazole ring, a triazole ring, a tetrazole ring, a benzene ring, a pyridine ring, a pyrimidine ring, or a pyrazine ring. Preferred is a pyrazole ring, imidazole ring, triazole ring, benzene ring, pyridine ring, pyrimidine ring, or pyrazine ring, more preferred is a pyrazole ring, imidazole ring, triazole ring, or pyridine ring, and particularly preferred is a pyrazole ring. ring , An imidazole ring, or a pyridine ring. These rings may further have a substituent, and other rings may be condensed. As the substituent, those exemplified as the substituents represented by R ¹ and R ² in the general formula (1) can be applied.

Q ⁴³ and Q ⁴⁴ represent a group of atoms necessary for forming a nitrogen-containing aromatic heterocycle which is a nitrogen atom and coordinates to M ⁴¹ and M ⁴² , respectively. Examples of the nitrogen-containing aromatic heterocycle formed by Q ⁴³ and Q ⁴⁴ include a pyridine ring, pyrimidine ring, pyridazine ring, pyrazine ring, triazine ring, pyrazole ring, imidazole ring, oxazole ring, thiazole ring, oxadiazole ring, Examples include thiadiazole rings, triazole rings, and tetrazole rings. The nitrogen-containing aromatic heterocycle formed by Q ⁴³ and Q ⁴⁴ is preferably a pyridine ring, pyrimidine ring, pyridazine ring, pyrazine ring or imidazole ring, more preferably a pyridine ring, pyrimidine ring, pyrazine ring or imidazole. A ring, particularly preferably a pyridine ring. These rings may further have a substituent, and other rings may be condensed. As the substituent, those exemplified as the substituents represented by R ¹ and R ² in the general formula (1) can be applied.

  Although the specific example of the metal complex which has the partial structure represented by General formula (1) in this invention is enumerated below, this invention is not limited to these.

The content of the complex used in the present invention is preferably 0.1% by mass or more and 50% by mass or less, and preferably 0.2% by mass or more and 30% by mass or less with respect to the total mass of the layer when contained in the light emitting layer as a light emitting material. % By mass or less is more preferable, 0.3% by mass or more and 20% by mass or less is more preferable, and 0.5% by mass or more and 15% by mass or less is most preferable.
The metal complex in the present invention is preferably contained in the light emitting layer, more preferably contained in the light emitting layer as the light emitting material, and further preferably contained in the light emitting layer together with at least one kind of host material. Here, the host material is a material other than the light emitting material among the materials forming the light emitting layer, and functions to disperse the light emitting material and hold it in the layer, and receive holes from the anode, the hole transport layer, and the like. Function, function to receive electrons from cathode or electron transport layer, function to transport holes or electrons, function to provide recombination field of holes and electrons, energy of excitons generated by recombination It refers to a material having at least one function among a function of moving and a function of transporting holes or electrons to a light emitting material.

  The host material is preferably stable with respect to electrochemical oxidation or reduction (preferably oxidation and reduction) because a cation radical and / or an anion radical is generated in terms of its function. In addition, when recombination occurs on the host material, a singlet and triplet excited state of the host material is generated, and therefore, it is preferable that decomposition from a singlet and triplet excited state hardly occurs. In addition, since material decomposition and thin film destruction due to heat generated during driving are one of the major causes of deterioration of the device, the host material is also a material that is stable against heat and can remain amorphous up to high temperatures. Preferably there is.

  The host material in the present invention may be either a metal complex material or a material that is not a metal complex. As the metal complex host material, for example, metal complex hosts described in Japanese Patent Application Nos. 2003-422956, 2003-405549, 2003-405567, and the like are preferably used. As host materials that are not metal complexes, for example, host materials described in Japanese Patent Application Nos. 2003-425307 and 2004-7611 are preferably used.

  The organic electroluminescent element of the present invention preferably has at least one hole injection layer. Examples of the material contained in the hole injection layer include phthalocyanine complexes of various metals, porphyrin complexes of various metals, polyamine compounds, and the like, and copper phthalocyanine is most preferable.

  The element of the present invention preferably has at least one hole transport layer. The material contained in the hole transport layer is preferably a material containing at least two triarylamine skeletons.

  The organic electroluminescent element of the present invention contains an electron transport layer, and the compound contained in the electron transport layer may be either a metal complex compound or a compound that is not a metal complex. Although it does not specifically limit as a compound which is not a metal complex, A nitrogen-containing heterocyclic compound is preferable.

The nitrogen-containing heterocyclic compound is not particularly limited, but a 6-membered aromatic nitrogen-containing heterocyclic compound or a 5-membered aromatic nitrogen-containing heterocyclic compound is preferable, and pyridine, pyrazine, pyrimidine, triazine, quinoxaline, quinoline, Pyrrole, pyrazole, imidazole, oxazole, thiazole, oxadiazole, thiadiazole, and derivatives thereof (for example, tetraphenylpyridine, benzimidazole, imidazopyridine, etc.) are more preferable, imidazole derivatives are more preferable, and imidazopyridine derivatives are particularly preferable. .
As the electron transporting material of the present invention, for example, compounds described in JP-A No. 2002-319491 are preferably used. The metal complex contained in the electron transport layer is preferably a magnesium complex, a beryllium complex, a zinc complex, an aluminum complex, a gallium complex, or an indium complex, more preferably a zinc complex, an aluminum complex, or a gallium complex, and particularly preferably aluminum. A complex or a gallium complex.

  Although it does not specifically limit as a ligand in a complex, It is preferable to have a bidentate ligand, a bidentate ligand coordinated by oxygen-nitrogen, a bidentate ligand coordinated by oxygen-oxygen. More preferably, the ligand has a bidentate ligand coordinated with nitrogen-nitrogen, a bidentate ligand coordinated with oxygen-nitrogen, and a bidentate coordinated with nitrogen-nitrogen It is more preferable to have a child, and it is particularly preferable to have a bidentate ligand coordinated by oxygen-nitrogen. As the bidentate ligand coordinated by oxygen-nitrogen, 8-hydroxyquinoline is most preferable.

  The metal complex contained in the electron transport layer is preferably an aluminum complex or gallium complex of 8-hydroxyquinolinols.

  Next, the organic electroluminescent element containing the metal complex of the present invention will be described. The organic electroluminescent element of the present invention is not particularly limited, such as a system, a driving method, and a usage form. An organic EL (electroluminescence) element can be mentioned as a typical organic electroluminescent element.

  In the organic electroluminescent device of the present invention, it is preferable to have at least one hole injection layer, hole transport layer, and electron transport layer in addition to the light emitting layer, and further between the light emitting layer and the hole transport layer. It is more preferable to have an electron blocking layer, more preferable to have a hole blocking layer between the light emitting layer and the electron transporting layer, and the organic layer from the anode side to the hole injection layer, hole transporting. A device in which a layer, an electron block layer, a light emitting layer, a hole block layer, and an electron transport layer are laminated in this order is particularly preferable.

  The method of forming the organic (compound) layer of the present invention is not particularly limited, but resistance heating vapor deposition, electrophotography, electron beam, sputtering, molecular lamination, coating (spray coating, dip coating, impregnation) , Roll coat method, gravure coat method, reverse coat method, roll brush method, air knife coat method, curtain coat method, spin coat method, flow coat method, bar coat method, micro gravure coat method, air doctor coat, blade coat method Squeeze coating method, transfer roll coating method, kiss coating method, cast coating method, extrusion coating method, wire bar coating method, screen coating method, etc.), inkjet method, printing method, transfer method and the like are possible. Among these, the resistance heating vapor deposition method, the coating method, and the transfer method are preferable in consideration of the characteristics of the element, the ease of manufacture, the cost, and the like. When an organic electroluminescent element has a laminated structure of two or more layers, it can be manufactured by combining the above methods.

  In the case of the coating method, it can be dissolved or dispersed together with the resin component. Examples of the resin component include polyvinyl chloride, polycarbonate, polystyrene, polymethyl methacrylate, polyester, polysulfone, polyphenylene oxide, polybutadiene, and poly (N-vinylcarbazole). , Hydrocarbon resin, ketone resin, phenoxy resin, polyamide, ethyl cellulose, vinyl acetate, ABS resin, polyurethane, melamine resin, unsaturated polyester resin, alkyd resin, epoxy resin, silicon resin and the like.

  The organic electroluminescent element of the present invention includes at least a light emitting layer, but may additionally have a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, a protective layer, etc. as an organic layer, Each of these layers may have other functions. Details of each layer will be described below.

  The material of the hole injection layer and the hole transport layer has any one of the function of injecting holes from the anode, the function of transporting holes, and the function of blocking electrons injected from the cathode. As specific examples, in addition to the metal complex of the present invention, carbazole, imidazole, triazole, oxazole, oxadiazole, polyarylalkane, pyrazoline, pyrazolone, phenylenediamine, arylamine, amino-substituted chalcone, styrylanthracene, fluorenone, Hydrazone, stilbene, silazane, aromatic tertiary amine compound, styrylamine, aromatic dimethylidin compound, porphyrin compound, polysilane compound, poly (N-vinylcarbazole), aniline copolymer, thiophene oligomer, polythiophene, etc. Conductive polymer oligomer, Machine metal complexes, transition metal complexes, or derivatives of the above compounds.

  The film thicknesses of the hole injection layer and the hole transport layer are not particularly limited, but are usually preferably in the range of 1 nm to 5 μm, more preferably 5 nm to 1 μm, and still more preferably 10 nm to 500 nm. . The hole transport layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

  The material for the electron injection layer and the electron transport layer may be any material that has any one of the function of injecting electrons from the cathode, the function of transporting electrons, and the function of blocking holes injected from the anode. . Specific examples thereof include, in addition to the metal complex of the present invention, for example, triazole, triazine, oxazole, oxadiazole, fluorenone, anthraquinodimethane, anthrone, diphenylquinone, thiopyran dioxide, carbodiimide, fluorenylidenemethane, di- Various metal complexes typified by metal complexes of aromatic ring tetracarboxylic anhydrides such as styrylpyrazine, silole, naphthaleneperylene, phthalocyanine, 8-quinolinol derivatives and metal phthalocyanine, benzoxazole and benzothiazole ligands Or derivatives of the above compounds.

  Although the film thickness of an electron injection layer and an electron carrying layer is not specifically limited, The thing of the range of 1 nm-5 micrometers is preferable normally, More preferably, it is 5 nm-1 micrometer, More preferably, it is 10 nm-500 nm. The electron injection layer and the electron transport layer may have a single-layer structure made of one or more of the materials described above, or may have a multilayer structure made up of a plurality of layers having the same composition or different compositions.

  The material of the light emitting layer can receive holes from the anode, the hole injection layer, the hole transport layer, etc. when a voltage is applied, and can receive electrons from the cathode, the electron injection layer, the electron transport layer, etc. One of the function to move the injected charge, to provide a recombination field of holes and electrons, to generate excitons, to move excitation energy, and to emit light from excitons As long as it has a material used for the light emitting layer, in addition to the metal complex of the present invention, for example, benzoxazole, benzimidazole, benzothiazole, styrylbenzene, polyphenyl, diphenylbutadiene, tetraphenylbutadiene, naphthalimide, Coumarin, perylene, perinone, oxadiazole, aldazine, pyralidine, cyclopentadiene, Styryl anthracene, quinacridone, pyrrolopyridine, thiadiazolopyridine, styrylamine, aromatic dimethylidin compounds, polythiophene, polyphenylene, polyphenylene vinylene and other polymer compounds, carbazole, imidazole, triazole, oxazole, oxadiazole, polyarylalkane, pyrazoline , Pyrazolone, phenylenediamine, arylamine, amino-substituted chalcone, styrylanthracene, fluorenone, hydrazone, stilbene, silazane, aromatic tertiary amine compound, styrylamine, aromatic dimethylidin compound, porphyrin compound, polysilane compound, poly ( N-vinylcarbazole), aniline copolymers, thiophene oligomers, polythiophene and other conductive polymer oligomers , Organometallic complexes, transition metal complexes, triazole, triazine, oxazole, oxadiazole, fluorenone, anthraquinodimethane, anthrone, diphenylquinone, thiopyran dioxide, carbodiimide, fluorenylidenemethane, distyrylpyrazine, silole, naphthalene Various metal complexes represented by metal complexes of aromatic ring tetracarboxylic acid anhydrides such as perylene, phthalocyanines, 8-quinolinol derivatives, metal phthalocyanines, benzoxazoles and benzothiazoles, or derivatives of the above compounds Etc.

  The light emitting layer may be a single layer or a multilayer of two or more layers. When there are a plurality of light emitting layers, each layer may emit different light emission colors. Although the film thickness of a light emitting layer is not specifically limited, Usually, the thing of the range of 1 nm-5 micrometers is preferable, More preferably, it is 5 nm-1 micrometer, More preferably, it is 10 nm-500 nm.

As the material for the protective layer, any material may be used as long as it has a function of preventing the material that promotes device deterioration such as moisture and oxygen from entering the device. Specific examples thereof include metals such as In, Sn, Pb, Au, Cu, Ag, Al, Ti, and Ni, MgO, SiO, SiO ₂ , Al ₂ O ₃ , GeO, NiO, CaO, BaO, and Fe ₂ O. ₃ , metal oxides such as Y ₂ O ₃ and TiO ₂ , metal fluorides such as MgF ₂ , LiF, AlF ₃ and CaF ₂ , polyethylene, polypropylene, polymethyl methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychloro Trifluoroethylene, polydichlorodifluoroethylene, a copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene, a copolymer obtained by copolymerizing a monomer mixture containing tetrafluoroethylene and at least one comonomer, and a copolymer main chain A fluorine-containing copolymer having a cyclic structure, a water-absorbing substance having a water absorption rate of 1% or more, Examples include moisture-proof substances having a water content of 0.1% or less. There is no particular limitation on the method for forming the protective layer. For example, vacuum deposition, sputtering, reactive sputtering, MBE (molecular beam epitaxy), cluster ion beam, ion plating, plasma polymerization (high frequency excitation ions) Plating method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, coating method, ink jet method, printing method, transfer method, and electrophotographic method can be applied.

  The anode supplies holes to a hole injection layer, a hole transport layer, a light emitting layer, and the like, and a metal, an alloy, a metal oxide, an electrically conductive compound, or a mixture thereof can be used, preferably Is a material having a work function of 4 eV or more. Specific examples include conductive metal oxides such as tin oxide, zinc oxide, indium oxide and indium tin oxide (ITO), metals such as gold, silver, chromium and nickel, and these metals and conductive metal oxides. Inorganic conductive materials such as laminates, copper iodide and copper sulfide, organic conductive materials such as polyaniline, polythiophene, and polypyrrole, and mixtures and laminates of these with ITO, It is a conductive metal oxide, and ITO is particularly preferable from the viewpoints of productivity, high conductivity, transparency, and the like. Although the film thickness of the anode can be appropriately selected depending on the material, it is usually preferably in the range of 10 nm to 5 μm, more preferably 50 nm to 1 μm, still more preferably 100 nm to 500 nm.

  As the anode, a layer formed on a soda-lime glass, non-alkali glass, a transparent resin substrate or the like is usually used. When glass is used, it is preferable to use non-alkali glass as the material in order to reduce ions eluted from the glass. Moreover, when using soda-lime glass, it is preferable to use what gave barrier coatings, such as a silica. The thickness of the substrate is not particularly limited as long as it is sufficient to maintain the mechanical strength. However, when glass is used, the thickness is usually 0.2 mm or more, preferably 0.7 mm or more. Various methods are used for producing the anode depending on the material. For example, in the case of ITO, an electron beam method, a sputtering method, a resistance heating vapor deposition method, an ion plating method, a chemical reaction method (sol-gel method, etc.), a spray method, etc. A film is formed by a method such as dipping, thermal CVD, plasma CVD, or ITO dispersion coating. The anode can be subjected to cleaning and other treatments to lower the drive voltage of the element and increase the light emission efficiency. For example, in the case of ITO, UV-ozone treatment, plasma treatment, etc. are effective.

  The cathode supplies electrons to the electron injection layer, the electron transport layer, the light emitting layer, etc., and the adhesion, ionization potential, stability, etc. between the cathode and the adjacent layer such as the electron injection layer, electron transport layer, light emitting layer, etc. Selected in consideration of As a material for the cathode, a metal, an alloy, a metal oxide, an electrically conductive compound, or a mixture thereof can be used. Specific examples include alkali metals (for example, Li, Na, K, Cs, etc.) or fluorides thereof, Alkaline earth metal (eg, Mg, Ca, etc.) or fluorides thereof, gold, silver, lead, aluminum, sodium-potassium alloy, or a mixed metal thereof, lithium-aluminum alloy, or a mixed metal thereof, magnesium-silver alloy Or a mixed metal thereof, or a rare earth metal such as indium or ytterbium, preferably a material having a work function of 4 eV or less, more preferably aluminum, a lithium-aluminum alloy, or a mixed metal thereof, a magnesium-silver alloy Or a mixed metal thereof. The film thickness of the cathode can be appropriately selected depending on the material, but is usually preferably in the range of 10 nm to 5 μm, more preferably 50 nm to 1 μm, still more preferably 100 nm to 1 μm. A method such as an electron beam method, a sputtering method, a resistance heating vapor deposition method, or a coating method is used for producing the cathode, and a metal can be vapor-deposited alone or two or more components can be vapor-deposited simultaneously. Furthermore, a plurality of metals can be vapor-deposited simultaneously to form an alloy electrode, or a previously prepared alloy may be vapor-deposited. The sheet resistance of the anode and the cathode is preferably low, and is preferably several hundred Ω / □ or less.

  The organic electroluminescence device of the present invention can improve the light extraction efficiency by various known devices. For example, processing the substrate surface shape (for example, forming a fine uneven pattern), controlling the refractive index of the substrate / ITO layer / organic layer, controlling the film thickness of the substrate / ITO layer / organic layer, etc. Therefore, it is possible to improve the light extraction efficiency and the external quantum efficiency.

  The organic electroluminescent element of the present invention may be a so-called top emission type in which light emission is extracted from the anode side.

  The base material used in the organic electroluminescent device of the present invention is not particularly limited, but inorganic materials such as zirconia stabilized yttrium and glass, polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene, polycarbonate, poly High molecular weight materials such as ether sulfone, polyarylate, allyl diglycol carbonate, polyimide, polycycloolefin, norbornene resin, poly (chlorotrifluoroethylene), teflon, polytetrafluoroethylene-polyethylene copolymer may be used.

  The light emitting layer of the organic electroluminescent element of the present invention may have at least one laminated structure. The number of stacked layers is preferably 2 or more and 50 or less, more preferably 4 or more and 30 or less, and still more preferably 6 or more and 20 or less.

  The thickness of each layer constituting the stack is not particularly limited, but is preferably 0.2 nm or more and 20 nm or less, more preferably 0.4 nm or more and 15 nm or less, further preferably 0.5 nm or more and 10 nm or less, and particularly preferably 1 nm or more and 5 nm or less. .

  The light emitting layer of the organic electroluminescent element of the present invention may have a plurality of domain structures. The light emitting layer may have another domain structure. The diameter of each domain is preferably from 0.2 nm to 10 nm, more preferably from 0.3 nm to 5 nm, still more preferably from 0.5 nm to 3 nm, and particularly preferably from 0.7 nm to 2 nm.

[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these.

(Comparative Example 1)
The cleaned ITO substrate was placed in a vapor deposition apparatus, and a solution obtained by dissolving 40 mg of PVK, 12 mg of PBD, and 1 mg of perylene in 3 ml of 1,2-dichloroethane was spin-coated. The film thickness of the organic layer at this time was about 120 nm. A patterned mask (a mask having a light emission area of 4 mm × 5 mm) is placed on this organic thin film, lithium fluoride is deposited by 3 nm, and aluminum is deposited by 200 nm on this, and a cathode is attached. An electroluminescent element was produced. Using a source measure unit type 2400 manufactured by Toyo Technica, a DC constant voltage was applied to the organic EL element to emit light, and the luminance was measured using a luminance meter BM-8 manufactured by Topcon Corporation. As a result, blue light emission of λmax = 490 nm was obtained, and the external quantum efficiency of the device was 0.7%. When the device was driven after being stored at 85 ° C. for one week, the device did not emit light.

  An organic electroluminescent element of Example 1 was produced in the same manner as Comparative Example 1 except that the exemplified compound <2> of the present invention was used instead of perylene. When evaluated in the same manner as in Comparative Example 1, blue light emission of λmax = 450 nm was obtained, and the external quantum efficiency of the device was 1.4%. When it was driven after being stored at 85 ° C. for one week, there was no dark spot on the light emitting surface, and the external quantum efficiency of the device was 1.0%.

  From these results, it was found that the organic electroluminescent device of the present invention was superior in the color purity (especially blue), efficiency and durability of the device as compared with the conventional device.

  The light emitting device of the present invention can be suitably used in the fields of display devices, displays, backlights, electrophotography, illumination light sources, recording light sources, exposure light sources, reading light sources, signs, signboards, interiors, optical communications, and the like.

Claims (6)

An organic electroluminescent device having at least one organic layer including a light emitting layer between a pair of electrodes, wherein the organic layer contains a metal complex having a partial structure represented by the following general formula (1): Electroluminescent device.

(In general formula (1), M ¹ and M ² each independently represent a metal ion. X ¹ and X ² each independently represent a carbon atom or a nitrogen atom. R ¹ and R ² are each independently substituted. Group may be combined with each other to form a ring if possible.) The organic electroluminescent element according to claim 1, wherein the metal complex having a partial structure represented by the general formula (1) is represented by the following general formula (2).

(In General Formula (2), M ¹ and M ² each independently represent a metal ion. X ¹ and X ² each independently represent a carbon atom or a nitrogen atom. Q ² represents an atomic group forming an aromatic ring. Represents.) The organic electroluminescent element according to claim 1 or 2, wherein the metal complex having a partial structure represented by the general formula (1) is represented by the following general formula (3).

(In the general formula (3), M ³¹ , M ³² and M ³³ each independently represents a metal ion. X ³¹ , X ³² , X ³³ , X ³⁴ , X ³⁵ and X ³⁶ are each independently a carbon atom, or Represents a nitrogen atom, Q ³¹ , Q ³² and Q ³³ each independently represent an atomic group forming an aromatic ring. The organic electroluminescent element according to claim 1 or 2, wherein the metal complex having a partial structure represented by the general formula (1) is represented by the following general formula (4).

(In the general formula (4), M ⁴¹ and M ⁴² each independently represent a metal ion. X ⁴¹ , X ⁴² , X ⁴³ and X ⁴⁴ each independently represent a carbon atom or a nitrogen atom. Q ⁴¹ and Q ⁴² represents an atomic group that independently forms an aromatic ring, and Q ⁴³ and Q ⁴⁴ each independently represent an atomic group that forms a nitrogen-containing aromatic heterocycle. 5. The metal ion M ¹ , M ² , M ³¹ , M ³² , M ³³ , M ^41, and M ⁴² are ions of Group 11 metal of the periodic table. Organic electroluminescent device.   6. The organic electroluminescent device according to claim 1, wherein the light emitting layer contains at least one metal complex represented by the general formulas (1) to (4) and at least one host material. .