JP5569630B2 - Organic electroluminescence device, organic EL lighting, and organic EL display device - Google Patents

Description

  The present invention relates to an organic electroluminescent element, organic EL lighting, and an organic EL display device. More specifically, the present invention relates to a white light emitting organic electroluminescence device having a light emitting layer formed by a wet film forming method and a layer formed by a vacuum vapor deposition method, having a low driving voltage and white light emitting. The present invention relates to an organic electroluminescent element having high efficiency and excellent reproducibility, and an organic EL illumination and an organic EL display device using the organic electroluminescent element.

Since the launch of Kodak's stacked organic electroluminescence (EL) element, the development of organic EL displays has been actively carried out and is now in practical use. is there.
In such a stacked organic electroluminescent device, a plurality of organic layers (such as a light emitting layer, a hole injection layer, a hole transport layer, and an electron transport layer) are stacked between an anode and a cathode. Since such a stacked organic electroluminescent element is self-luminous, it has a wide viewing angle and high visibility, and since it is a thin film type, it has attracted attention from the viewpoint of space saving.

Another major feature of the organic electroluminescent device is that it is surface-emitting, unlike the light-emitting diodes and cold cathode tubes that have been put to practical use. Applications that utilize this feature include a backlight, illumination, a full-color display device using a color filter, and the like.
Since a white light source is suitable for use in these applications, a white light-emitting organic electroluminescent element is required.

Conventionally, as a method for obtaining this white light emitting organic electroluminescence device, for example, Patent Document 1 discloses a method of adding a plurality of red, green, and blue light emitting materials to a single layer. In this case, in order to form the light emitting layer by the vacuum deposition method, at least four kinds of materials of at least red, green, blue and the host material are deposited at the same time.
Patent Documents 2 to 4 disclose a method of laminating a plurality of light emitting layers containing different light emitting wavelengths and containing a single light emitting dopant.

Patent Document 5 discloses a method of combining one color of red, green, and blue and a color corresponding to the complementary color of one color as a method of obtaining white light emission.
In Patent Document 6, as a method for obtaining white light emission using two or more light emitting layers, a first light emitting layer formed by a wet film forming method using a polymer material as a charge transport material, and a low molecular material are provided. What has the 2nd light emitting layer formed by the dry-type film-forming method using is disclosed.

Patent Document 7 discloses that an organic electroluminescence element capable of obtaining white light emission by simultaneously emitting light from a plurality of guest materials using two light emitting layers and one of the two light emitting layers is formed by a coating method. The above-described device is disclosed in which the other layer is obtained by a vacuum deposition method. In addition, it is described that a phosphorescent compound is used as a guest compound in each of the two light emitting layers.

International Publication No. 2006-093007 Pamphlet JP 2003-187777 A JP 2004-63349 A JP 2006-287154 A JP 2001-52870 A JP 2008-159367 A JP 2010-034484 A

However, among the above-mentioned conventional techniques, as described above, the method of Patent Document 1 needs to deposit at least four types of red, green, blue and host materials at the same time, but the vacuum deposition method requires three types of materials. Since simultaneous vapor deposition is the limit and it is very difficult to control vapor deposition of four or more materials, there is a problem that reproducibility is poor.
The method of laminating a plurality of light-emitting layers having different emission wavelengths containing a single light-emitting dopant described in Patent Documents 2 to 4 is effective for obtaining high color rendering, but chromaticity changes are likely to occur. Also, since the light emitting layer thickness tends to increase, there is a problem that the drive voltage tends to increase.

In the method of combining any one color of red, green, and blue described in Patent Document 5 and a color corresponding to the complementary color of the one, when forming a layer by vacuum deposition, one of the light emission often becomes strong, It was difficult to adjust the chromaticity, and it was difficult to obtain an effective white light-emitting organic electroluminescent device.
In Patent Document 6, the first light emitting layer is formed by a wet film forming method using a polymer material, and the second light emitting layer is formed by a dry film forming method using a low molecular material. There were the following problems.

That is, the polymer material is relatively difficult to purify as compared to the low-molecular compound and has a relatively large amount of impurities because it is difficult to achieve high purity. Therefore, when a polymer compound is used as the light emitting layer material, these impurities serve as charge traps, and the drive voltage of the organic electroluminescent device increases; the light emission efficiency decreases; the drive life is short; Exists.
Further, from the viewpoint of improving the light emission efficiency and lowering the driving voltage, it is preferable that the light emitting units and the charge transport units are uniformly distributed in the light emitting layer. However, in order for these two units to be uniformly present in the molecule of the polymer compound, it is necessary to employ a special polymerization method such as alternating copolymerization or block copolymerization, and the load on the production process is high.

A light-emitting layer including a high-molecular charge transport material and a low-molecular light-emitting material is also known. However, in this case as well, it is very difficult to control the distance between charge transport units connected by polymer chains to a distance that facilitates charge transport or exciton movement in a polymer charge transport material.
In an organic electroluminescence device described in Patent Document 7 having two light emitting layers and capable of obtaining white light emission by simultaneously emitting a plurality of guest materials, the phosphor layer includes a phosphorescent compound as the light emitting layer material. Among the light emitting layers, one layer was formed by a coating method, and the other layer was formed by a vacuum deposition method, which had the following problems.

That is, when a phosphorescent compound is used as an object of vacuum deposition in forming the light emitting layer, there is a possibility that phosphorescent light emitting material molecules having large thermal energy collide with the already formed lower layer and the surface of the lower layer is roughened. The layer surface (interface) in which flatness is impaired promotes aggregation of the material contained in the layer, and the aggregate causes charge trap formation (details will be described later).
The present invention solves the above-mentioned conventional problems, and is a white light emitting organic electroluminescent device having two or more light emitting layers, having a low driving voltage, high white light emitting efficiency, and excellent reproducibility. It is an object to provide an organic electroluminescent element.

As a result of the present inventors diligently studying to solve the above-described problems, both the use of a low-molecular compound as the charge transport material and the light-emitting material of the light-emitting layer, and a certain element configuration, The inventors have found that the problem can be solved and have reached the present invention.
That is, the gist of the present invention is an organic electroluminescent device comprising an anode and a cathode, and a light emitting layer formed between the anode and the cathode.
The light emitting layer is composed of two or more layers each containing different light emitting materials,
The light-emitting layer is a layer formed by a wet film forming method in order from the anode side (hereinafter sometimes referred to as “coated light-emitting layer” or “first light-emitting layer”), a layer formed by a vacuum deposition method ( Hereinafter, it may be referred to as “evaporated light emitting layer” or “second light emitting layer”),
The layer formed by the wet film formation method is a layer containing a phosphorescent material and a charge transport material which are low molecular compounds,
The layer formed by the vacuum deposition method is a layer containing a fluorescent light-emitting material and a charge transport material which are low molecular compounds,
An organic electroluminescent element having an emission spectrum having a maximum emission wavelength in a 440 to 500 nm region, a 510 to 550 nm region, and a 580 to 630 nm region, and the organic electroluminescent device Including organic EL lighting and organic EL display devices.

According to the present invention, a white light-emitting organic electroluminescent device having a low driving voltage and high luminous efficiency is provided with good reproducibility.
The organic electroluminescent element of the present invention is used for a white light source (for example, a light source of a copying machine, a backlight light source of a liquid crystal display or instruments, a color filter display device), a display plate, or a marker lamp. Can be applied, and its technical value is high.

It is sectional drawing which shows typically an example of the structure of the organic electroluminescent element of this invention.

  Hereinafter, embodiments of the organic electroluminescent element, organic EL illumination, and organic EL display device of the present invention will be described in detail. The description of the constituent elements described below is an example (representative example) of the embodiment of the present invention. The present invention is not limited to these contents unless it exceeds the gist.

≪Organic electroluminescent element≫
The organic electroluminescent element of the present invention is an organic electroluminescent element comprising an anode and a cathode, and a luminescent layer formed between the anode and the cathode, wherein the luminescent layer contains two different luminescent materials. The light-emitting layer is composed of a layer formed by a wet film formation method (coated light-emitting layer) and a layer formed by a vacuum deposition method (vapor-deposited light-emitting layer) in this order from the anode side. Is a layer containing a phosphorescent light emitting material which is a low molecular compound and a charge transporting material, and the vapor deposition light emitting layer is a layer containing a fluorescent light emitting material and a charge transporting material which are low molecular compounds, and the organic electroluminescent element The emission spectrum has a maximum emission wavelength in the 440 to 500 nm region, the 510 to 550 nm region, and the 580 to 630 nm region.

That is, in the organic electroluminescent device of the present invention, the coated light emitting layer contains a low molecular weight charge transport material and a low molecular weight phosphorescent light emitting material, and the vapor deposition light emitting layer has a low molecular weight charge transport material and a low molecular weight fluorescent light emission. Contains material.
In the present invention, the use of the light emitting material and the charge transport material which are low molecular compounds is as follows.

That is, as described above, in a light-emitting layer including a high-molecular charge transport material and a low-molecular light-emitting material,
In a polymer charge transport material, it is very difficult to control the distance between charge transport units connected by polymer chains to a distance that facilitates charge transport or exciton migration.
In addition, the film density in wet film formation and vacuum deposition using a low molecular weight charge transport material is higher than the film density in wet film formation using a high molecular weight charge transport material, and the intermolecular density at the coating / deposition interface is high. Since adhesion becomes high, transfer of electric charge is facilitated, which is preferable in terms of voltage reduction.

For this reason, in the organic electroluminescent element of the present invention, all low molecular weight compounds are used as the light emitting layer material.
The organic electroluminescent device of the present invention preferably further has a hole transport layer between the anode and the light emitting layer in order to inject sufficient holes from the anode to the light emitting layer closest to the cathode.

[Low molecular compounds]
The light emitting layer of the organic electroluminescent element of the present invention is characterized by containing a light emitting material which is a low molecular compound and a charge transport material.
The molecular weight of the “low molecular weight compound” in the present invention is usually 10,000 or less, preferably 5000 or less, more preferably 4000 or less, still more preferably 3000 or less, and usually 100 or more, preferably 200 or more, more preferably 300 or more, More preferably, it is the range of 400 or more.
If the molecular weight of the luminescent material is too small, the heat resistance will be significantly reduced, gas generation will be caused, the film quality will be reduced when the film is formed, or the morphology of the organic electroluminescent element will be changed due to migration, etc. Sometimes come. On the other hand, if the molecular weight of the luminescent material is too large, it tends to be difficult to purify the organic compound, or it may take time to dissolve in the solvent.

When the molecular weight of the luminescent material is within the above range, the glass transition temperature, the melting point, the decomposition temperature, etc. are high, and the luminescent layer material and the formed luminescent layer have good heat resistance, resulting from recrystallization or molecular migration. It is preferable in that it does not easily cause deterioration in film quality, an increase in impurity concentration due to thermal decomposition of the material, etc., makes it difficult to reduce device performance, and facilitates purification.
When the light emitting layer of the organic electroluminescent element of the present invention contains a compound other than the light emitting material and the charge transporting material, the molecular weight of the compound is preferably 10,000 or less, more preferably 5000 or less, still more preferably 4000 or less, particularly The low molecular weight compound is preferably 3000 or less, preferably 100 or more, more preferably 200 or more, still more preferably 300 or more, and particularly preferably 400 or more.

[Maximum emission wavelength of emission spectrum]
The organic electroluminescent element of the present invention is characterized by having a maximum emission wavelength in a 440-500 nm region, a 510-550 nm region, and a 580-630 nm region in its emission spectrum.
As a method for obtaining such an organic electroluminescent device of the present invention, the light emitting material used for forming the light emitting layer has an emission spectrum of the organic electroluminescent device of 440 to 500 nm region, 510 to 550 nm region, and 580 to 630 nm region. In addition, there is a method of appropriately selecting and using each so as to have a maximum emission wavelength.

  Further, by applying a color filter, a polarizing plate, a retardation plate, a diffusion plate, a fluorescent conversion film, etc., it can be designed to have a maximum emission wavelength in each region. Use an appropriate selection of the light-emitting material used for the light-emitting layer so that the emission spectrum of the organic electroluminescent element has a maximum emission wavelength in each of the 440-500 nm region, the 510-550 nm region, and the 580-630 nm region. Is preferred.

[Measurement method of emission spectrum]
The emission spectrum of the organic electroluminescent element of the present invention can be measured using, for example, a spectroscope USB4000 (manufactured by Ocean Optics).
As long as the measurement equivalent to the above is possible, the emission spectrum measuring device is not limited to the above measuring device, and other measuring devices may be used, but the above measuring device may be used. preferable.

[Light emitting layer]
The light emitting layer in the present invention is a layer which is excited by recombination of holes injected from the anode and electrons injected from the cathode between the electrodes to which an electric field is applied, and becomes a main light emitting source. As described above, from the anode side, a phosphorescent light emitting material that is a low molecular compound and a coating light emitting layer containing a charge transport material, a fluorescent light emitting material that is a low molecular compound, and a vapor deposition light emitting layer containing a charge transport material are included.

  The film quality of the light emitting layer obtained by the light emitting layer having the coated light emitting layer and the vapor deposited light emitting layer in order from the anode becomes uniform. Moreover, when the phosphorescent light emitting material is contained in the coated light emitting layer, high efficiency can be obtained, and when the vapor deposited light emitting layer contains a fluorescent light emitting material, sufficient light emission intensity can be obtained, By laminating and forming a vapor-deposited light emitting layer containing a fluorescent light emitting material on a coated light emitting layer containing a phosphorescent light emitting material, an organic electroluminescent device having excellent luminous efficiency can be realized by the following mechanism.

  That is, first, as the first light-emitting layer, a composition containing a phosphorescent light-emitting material and a charge transport material is wet-formed. In general, the phosphorescent material is a complex containing a metal atom having a large atomic weight such as Ir or Pt. Since the chemical surface energy is low and stable when the compound containing a metal atom having a large atomic weight is not present on the outermost surface of the film, the phosphorescent material is hardly present on the outermost surface in the presence of a solvent. It is considered that a large amount of charge transport material is present in the extremely thin region on the outermost surface of the dried film.

It is considered that the region having a large amount of the charge transport material blocks energy transfer from the fluorescent light emitting material in the second light emitting layer provided thereon to the phosphorescent light emitting material in the first light emitting layer. As a result, it is considered that both the first and second light emitting layers emit light sufficiently, and an organic electroluminescent device having high luminous efficiency can be obtained.
When a phosphorescent light emitting material is used as the light emitting material of the second light emitting layer (deposited light emitting layer), the following problems may occur. Therefore, in the organic electroluminescent element of the present invention, the light emitting material of the vapor deposited light emitting layer is used. A fluorescent material is used.

  That is, as described above, since the phosphorescent material is a molecule having a large molecular weight including a metal atom having a large atomic weight, the molecule flying by vacuum deposition has a large thermal energy. When a phosphorescent material is vacuum-deposited as a light-emitting material for the second light-emitting layer formed on the first light-emitting layer, the surface of the first light-emitting layer may be roughened by collision of phosphorescent material molecules with large thermal energy. Conceivable. The layer surface (interface) with impaired flatness promotes aggregation of the material contained in the layer, and the aggregate causes charge trap formation.

  In addition, since the barrier function by the charge transport material on the surface of the first light emitting layer, which is a feature of the above-described element of the present invention, is impaired by the phosphorescent light emitting material molecules flying by vapor deposition, the triplet energy in the first light emitting layer is reduced. It moves to the second light emitting layer, the light emission of the first light emitting layer becomes insufficient, and the balance of the light emission color may be lost.

{Luminescent material}
<Fluorescent material>
Hereinafter, among the light emitting materials, the fluorescent light emitting material used in the vapor deposition light emitting layer will be described.
(1) 440-500 nm region (blue)
Examples of fluorescent light emitting materials (blue fluorescent dyes) having a maximum emission wavelength in the 440 to 500 nm region and giving blue light emission include naphthalene, chrysene, perylene, pyrene, anthracene, coumarin, and p-bis (2-phenylethenyl). Examples thereof include benzene, arylamine and derivatives thereof. Among these, anthracene, chrysene, pyrene, arylamine and derivatives thereof are preferable.

Of these, styrylamine compounds and arylamine compounds are preferable in terms of high blue color purity, high efficiency, and long life.
As the styrylamine compound, those represented by the following formula (A) are preferable in that holes are efficiently captured in the light emitting layer.

(In the formula, Ar ²² is a group selected from a biphenyl group, a terphenyl group, a stilbene group, and a distyrylaryl group, and Ar ²³ and Ar ²⁴ are each independently a hydrogen atom or a carbon number of 6 to 20 carbon atoms. Ar ²² , Ar ²³ and Ar ²⁴ may have a substituent, p is an integer of 1 to 4. Preferably, at least one of Ar ²³ or Ar ²⁴ is substituted with a styryl group. Has been.)
Here, examples of the aromatic group having 6 to 20 carbon atoms include aromatic hydrocarbon groups such as a phenyl group, a naphthyl group, an anthranyl group, a phenanthryl group, and a terphenyl group.
Moreover, as an arylamine compound, what is represented by a following formula (B) is preferable at the point which capture | acquires a hole efficiently in a light emitting layer.

(In the formula, Ar ²⁵ is a substituted or unsubstituted aryl group having 10 to 40 nuclear carbon atoms, and Ar ²⁶ and Ar ²⁷ are each independently a substituted or unsubstituted aryl group having 5 to 40 nuclear carbon atoms. Q is an integer from 1 to 4.)
Here, as the aryl group having 10 to 40 nuclear carbon atoms of Ar ²⁵ , for example, a naphthyl group, anthranyl group, phenanthryl group, pyrenyl group, chrysenyl group, coronyl group, biphenyl group, terphenyl group, diphenylanthranyl group, Examples thereof include a carbazolyl group, a benzoquinolyl group, a fluoranthenyl group, an acenaphthofluoranthenyl group, and a stilbene group.

Examples of the aryl group having 5 to 40 nuclear carbon atoms of Ar ²⁶ and Ar ²⁷ include a phenyl group, a naphthyl group, an anthranyl group, a phenanthryl group, a pyrenyl group, a chrycenyl group, a coronyl group, a biphenyl group, and a terphenyl group. , Pyrrolyl group, furanyl group, thiophenyl group, benzothiophenyl group, oxadiazolyl group, diphenylanthranyl group, indolyl group, carbazolyl group, pyridyl group, benzoquinolyl group, fluoranthenyl group, acenaphthofluoranthenyl group, stilbene group, etc. Can be mentioned.

When these aryl groups have a substituent, preferred substituents include alkyl groups having 1 to 6 carbon atoms (ethyl group, methyl group, i-propyl group, n-propyl group, s-butyl group, t-butyl group). Group, pentyl group, hexyl group, cyclopentyl group, cyclohexyl group, etc.), alkoxy group having 1 to 6 carbon atoms (ethoxy group, methoxy group, i-propoxy group, n-propoxy group, s-butoxy group, t-butoxy group) Pentoxy group, hexyloxy group, cyclopentoxy group, cyclohexyloxy group, etc.), an aryl group having 5 to 40 nuclear atoms, an amino group substituted with an aryl group having 5 to 40 nuclear atoms, and 5 to 5 nuclear atoms Examples include an ester group having 40 aryl groups, an ester group having an alkyl group having 1 to 6 carbon atoms, a cyano group, a nitro group, and a halogen atom.
Hereinafter, although the preferable specific example of the fluorescent light-emitting material which gives blue light emission in this invention is shown below, this invention is not limited to these.

One type of the fluorescent material that gives blue light may be used alone, or two or more types may be used in any combination and ratio.
(2) 510-550 nm region (green)
Examples of fluorescent light emitting materials (green fluorescent dyes) having a maximum emission wavelength in the 510 to 550 nm region and giving green light emission include aluminum complexes such as quinacridone, coumarin, Al (C ₉ H ₆ NO) ₃ and their derivatives. Is mentioned. One of these may be used alone, or two or more may be used in any combination and ratio.

(3) 580 to 630 nm region (red)
As a fluorescent light emitting material (red fluorescent dye) having a maximum emission wavelength in the 580 to 630 nm region and giving red light emission, for example, DCM (4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyrene) -4H-pyran) -based compounds, xanthene such as benzopyran, rhodamine, benzothioxanthene, azabenzothioxanthene, and derivatives thereof. One of these may be used alone, or two or more may be used in any combination and ratio.

<Phosphorescent material>
Next, among the light emitting materials, the phosphorescent light emitting material used in the coated light emitting layer will be described.
As the phosphorescent material, for example, a long-period type periodic table (hereinafter referred to as a long-period type periodic table when referred to as “periodic table” unless otherwise specified) is selected from the seventh to eleventh groups. A Werner complex or an organometallic complex containing a metal as a central metal.

Preferred examples of the metal selected from Groups 7 to 11 of the periodic table include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold. Among these, iridium or platinum is more preferable.
As the ligand of the complex, a ligand in which a (hetero) aryl group such as a (hetero) arylpyridine ligand or a (hetero) arylpyrazole ligand and a pyridine, pyrazole, phenanthroline, or the like is connected is preferable. A pyridine ligand and a phenylpyrazole ligand are preferable. Here, (hetero) aryl represents an aryl group or a heteroaryl group.

  Specific examples of the phosphorescent material include tris (2-phenylpyridine) iridium, tris (2-phenylpyridine) ruthenium, tris (2-phenylpyridine) palladium, bis (2-phenylpyridine) platinum, tris (2- Phenylpyridine) osmium, tris (2-phenylpyridine) rhenium, octaethyl platinum porphyrin, octaphenyl platinum porphyrin, octaethyl palladium porphyrin, octaphenyl palladium porphyrin, and the like.

In particular, the phosphorescent organometallic complex of the phosphorescent material preferably includes a compound represented by the following formula (III) or formula (IV).
ML _(q−j) L ′ _j (III)
(In the formula (III), M represents a metal, q represents a valence of the metal, L and L ′ represent a bidentate ligand, and j represents a number of 0, 1 or 2. )

(In formula (IV), M ⁷ represents a metal, T represents a carbon atom or a nitrogen atom. R ^{92 to} R ⁹⁵ each independently represents a substituent. However, when T is a nitrogen atom, R 7 ⁹⁴ and R ⁹⁵ are not.)
Hereinafter, the compound represented by formula (III) will be described first.
In formula (III), M represents an arbitrary metal, and specific examples of preferable ones include the metals described above as metals selected from Groups 7 to 11 of the periodic table.
In formula (III), bidentate ligand L represents a ligand having the following partial structure.

In the partial structure of L, the ring A1 represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent.
Examples of the aromatic hydrocarbon group include groups derived from 5- or 6-membered monocyclic rings or 2 to 5 condensed rings.
Specific examples include monovalent groups derived from a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, fluoranthene ring, fluorene ring, etc. Is mentioned.

Examples of the aromatic heterocyclic group include groups derived from a 5- or 6-membered monocyclic ring or a 2-4 condensed ring.
Specific examples include furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, Thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzoisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring , Sinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, monovalent group derived from an azulene ring, and the like.
In the partial structure of L, ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.

Examples of the nitrogen-containing aromatic heterocyclic group include groups derived from a 5- or 6-membered monocyclic ring or a 2-4 condensed ring.
Specific examples include pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, furopyrrole ring, thienofuran ring, benzoisoxazole ring. , Benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone Examples thereof include a monovalent group derived from a ring.

Examples of the substituent that each of ring A1 and ring A2 may have include a halogen atom; an alkyl group; an alkenyl group; an alkoxycarbonyl group; an alkoxy group; an aryloxy group; a dialkylamino group; Acyl group; haloalkyl group; cyano group; aromatic hydrocarbon group and the like.
In formula (III), bidentate ligand L ′ represents a ligand having the following partial structure. However, in the following formulae, “Ph” represents a phenyl group.

  Among these, as L ′, the following ligands are preferable from the viewpoint of the stability of the complex.

  More preferred examples of the compound represented by the formula (III) include compounds represented by the following formulas (IIIa), (IIIb), and (IIIc).

(In formula (IIIa), M ⁴ represents the same metal as M, w represents the valence of the metal, and ring A1 represents an aromatic hydrocarbon group which may have a substituent. Ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.

(In formula (IIIb), M ⁵ represents the same metal as M, w represents the valence of the metal, and ring A 1 represents an aromatic hydrocarbon group or aromatic group which may have a substituent. Represents a heterocyclic group, and ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.)

(In formula (IIIc), M ⁶ represents the same metal as M, w represents the valence of the metal, j represents 0, 1 or 2, and ring A1 and ring A1 ′ each represent Independently represents an optionally substituted aromatic hydrocarbon group or aromatic heterocyclic group, and ring A2 and ring A2 ′ are each independently a nitrogen-containing aromatic optionally having a substituent. Represents a heterocyclic group.)
In the above formulas (IIIa) to (IIIc), preferable examples of the ring A1 and the ring A1 ′ include phenyl group, biphenyl group, naphthyl group, anthryl group, thienyl group, furyl group, benzothienyl group, benzofuryl group, pyridyl group. Quinolyl group, isoquinolyl group, carbazolyl group and the like.

In the above formulas (IIIa) to (IIIc), preferred examples of ring A2 and ring A2 ′ include pyridyl group, pyrimidyl group, pyrazyl group, triazyl group, benzothiazole group, benzoxazole group, benzimidazole group, quinolyl group, An isoquinolyl group, a quinoxalyl group, a phenanthridyl group, and the like can be given.
Examples of the substituent that the compounds represented by the formulas (IIIa) to (IIIc) may have include a halogen atom; an alkyl group; an alkenyl group; an alkoxycarbonyl group; an alkoxy group; an aryloxy group; A diarylamino group; a carbazolyl group; an acyl group; a haloalkyl group; a cyano group, and the like.

These substituents may be connected to each other to form a ring. As a specific example, a substituent of the ring A1 and a substituent of the ring A2 are bonded, or a substituent of the ring A1 ′ and a substituent of the ring A2 ′ are bonded to each other. A condensed ring may be formed. Examples of such a condensed ring include a 7,8-benzoquinoline group.
Among these, as a substituent for ring A1, ring A1 ′, ring A2 and ring A2 ′, an alkyl group, alkoxy group, aromatic hydrocarbon group, cyano group, halogen atom, haloalkyl group, diarylamino group, carbazolyl are more preferable. Groups.

In addition, preferable examples of M ^{4 to} M ⁶ in the formulas (IIIa) to (IIIc) include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, or gold.
Among the organometallic complexes represented by the above formula (III), in particular, as the ligand L and / or L ′, a 2-arylpyridine-based ligand, that is, 2-arylpyridine, which has an optional substituent. The compound which has what was couple | bonded and the thing formed by arbitrary groups condensing to this is preferable.

The compounds described in International Publication No. 2005/019373 pamphlet can also be used as the light emitting material.
Next, the compound represented by formula (IV) will be described.
Wherein (IV), ^{M 7} represents a metal. Specific examples include the metals described above as the metal selected from Groups 7 to 11 of the periodic table. Among these, ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum or gold is preferable, and divalent metals such as platinum and palladium are particularly preferable.

In the formula (IV), R ⁹² and R ⁹³ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, a cyano group, an amino group, an acyl group, an alkoxycarbonyl group, a carboxyl group, Represents an alkoxy group, an alkylamino group, an aralkylamino group, a haloalkyl group, a hydroxyl group, an aryloxy group, an aromatic hydrocarbon group or an aromatic heterocyclic group;

Further, when T is carbon ^{atom, R 94} and ^{R 95} each independently ^represents a substituent represented by the same exemplary compounds and ^{R 92} and ^{R 93.} Also, if T is a nitrogen ^{atom, R 94} and ^{R 95} is not.
R ^{92 to} R ⁹⁵ may further have a substituent. When it has a substituent, there is no restriction | limiting in particular in the kind, Arbitrary groups can be made into a substituent.

Further, any two or more groups of R ^{92 to} R ⁹⁵ may be connected to each other to form a ring.
Below, the specific example of a phosphorescent luminescent material is shown for every wavelength area | region where the absorption maximum wavelength exists. Any of the following phosphorescent materials may be used alone, or two or more may be used in any combination and ratio.
(1) Specific example of phosphorescent light-emitting material (blue) having an absorption maximum wavelength in the range of 440 nm to 500 nm

(2) Specific example of phosphorescent material (green) having an absorption maximum wavelength in the 510 to 550 nm region

(3) Specific example of phosphorescent material (red) having absorption maximum wavelength in 580 to 630 nm region

{Coating luminescent layer}
In the organic electroluminescent element of the present invention, the first light emitting layer (the layer on the anode side of the light emitting layer) is used as the coated light emitting layer.
That is, as described above, phosphorescent materials generally have a large molecular weight. If the first light-emitting layer is formed by a vacuum deposition process, the phosphorescent light-emitting material molecules that have come from the vapor deposition have large thermal energy and are attached to the outermost surface of the layer at the final stage of the deposition process. After the molecules move on the surface of the layer, the molecules aggregate and stabilize. That is, it is considered that the aggregate of phosphorescent material molecules is present more in the outermost layer than in the inside of the light emitting layer. Since this aggregate serves as a trap for excitons and charges present in both the first light emitting layer and the second light emitting layer, it is considered that the driving voltage of the device is increased and the light emission efficiency is decreased. Therefore, the first light emitting layer is preferably a coated light emitting layer.

Note that the fluorescent light-emitting material generally has a molecular weight that is not as large as that of the phosphorescent light-emitting material. For this reason, the molecules of the fluorescent light emitting material that have come and adhered to the substrate by the vapor deposition process have relatively small thermal energy and do not move much even on the outermost surface of the layer (the probability of forming an aggregate is low). Conceivable.
In the present invention, the “wet film-forming method” refers to a spin coating method, a dip coating method, a die coating method, a bar coating method, a blade coating method, a roll coating method, a spray coating method, a capillary coating method, a nozzle printing method, and an inkjet method. , A method of forming a film using an ink containing a solvent, such as a screen printing method, a gravure printing method, a flexographic printing method, and an offset printing. The nozzle printing method, die coating method, roll coating method, spray coating method, ink jet method, gravure printing method or flexographic printing method are preferable in terms of ease of patterning, and the nozzle printing method and ink jet method in terms of obtaining uniform film quality. The method, the gravure printing method and the flexographic printing method are particularly preferable.
The coated light emitting layer is formed by the wet film forming method using the phosphorescent light emitting material, the low molecular weight charge transporting material, and a composition for forming a light emitting layer further containing a solvent.

<Solvent>
The solvent is not particularly limited as long as it is a solvent in which the phosphorescent material and the charge transporting material described below are dissolved well.
As the solubility of the solvent, the phosphorescent material and the charge transport material are each usually 0.01% by weight or more, preferably 0.05% by weight or more, more preferably 0.1% by weight or more, at room temperature and normal pressure. It is preferable to dissolve.
Although the specific example of a solvent is given to the following, as long as the effect of this invention is not impaired, it is not limited to these.

For example, alkanes such as n-decane, cyclohexane, ethylcyclohexane, decalin, and bicyclohexane; aromatic hydrocarbons such as toluene, xylene, methicylene, cyclohexylbenzene, and tetralin; halogenated fragrances such as chlorobenzene, dichlorobenzene, and trichlorobenzene Group hydrocarbons: 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethyl Aromatic ethers such as anisole and diphenyl ether; aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, ethyl benzoate, propyl benzoate and n-butyl benzoate; Alicyclic ketones such as Sanone, Cyclooctanone and Fencon; Alicyclic alcohols such as cyclohexanol and cyclooctanol; Aliphatic ketones such as methyl ethyl ketone and dibutyl ketone; Aliphatic alcohols such as butanol and hexanol; Ethylene And aliphatic ethers such as glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA).

Of these, alkanes and aromatic hydrocarbons are preferable.
One of these solvents may be used alone, or two or more thereof may be used in any combination and ratio.
In order to obtain a more uniform film, it is preferable that the solvent evaporates from the liquid film immediately after the film formation at an appropriate rate. For this reason, the boiling point of the solvent is usually 80 ° C. or higher, preferably 100 ° C. or higher, more preferably 120 ° C. or higher, and usually 270 ° C. or lower, preferably 250 ° C. or lower, more preferably 230 ° C. or lower.

  The amount of the solvent used is arbitrary as long as the effect of the present invention is not significantly impaired, but is preferably 10 parts by weight or more, more preferably 50 parts by weight or more, particularly preferably with respect to 100 parts by weight of the light emitting layer forming composition. Is 80 parts by weight or more, preferably 99.95 parts by weight or less, more preferably 99.9 parts by weight or less, and particularly preferably 99.8 parts by weight or less. When the content of the solvent in the composition for forming a light emitting layer is less than the lower limit, the viscosity becomes too high, and film forming workability may be lowered. On the other hand, when the above upper limit is exceeded, the thickness of the film obtained by removing the solvent after film formation cannot be obtained, so that film formation tends to be difficult. In addition, when mixing and using 2 or more types of solvents as a composition for light emitting layer formation, it is made for the sum total of these solvents to satisfy | fill this range.

<Light emitting material>
In the present invention, the coated light emitting layer is preferably a layer having a maximum light emitting wavelength in at least two of the 440 to 500 nm region, the 510 to 550 nm region, and the 580 to 630 nm region. In particular, of the blue light emitting material having the maximum emission wavelength in the 440 to 500 nm region, the green light emitting material having the maximum emission wavelength in the 510 to 550 nm region, and the red light emitting material having the maximum emission wavelength in the 580 to 630 nm region It is preferable to have two or more types, in particular, a green light emitting material having a maximum emission wavelength in the 510 to 550 nm region and a red light emitting material having a maximum emission wavelength in the 580 to 630 nm region.

As described above, the coated light-emitting layer contains a phosphorescent light-emitting material because high luminous efficiency can be obtained. In particular, the coated light-emitting layer contains, in particular, a red phosphorescent light-emitting material and / or a green phosphorescent light-emitting material. It is preferable.
This is because a layer containing a red light emitting material or a green light emitting material having a narrow energy gap is arranged on the anode side, so that a layer adjacent to the anode side of the light emitting layer from a blue light emitting material having a wide energy gap (for example, hole transport) By suppressing the transfer of energy to the layer.

  In the composition for forming a light emitting layer in the present invention, the light emitting material is usually 0.01% by weight or more, preferably 0.05% by weight or more, more preferably 0.1% by weight or more, and usually 20% by weight or less, preferably Is contained in an amount of 10% by weight or less, more preferably 5% by weight or less.

<Charge transport material>
The composition for forming a light emitting layer used in the present invention further contains a charge transport material. That is, the coated light emitting layer contains a charge transport material.
The charge transport material is a compound having a charge transport property such as a hole transport property and an electron transport property, and is a compound defined by a single molecular weight. The light emitting layer according to the present invention preferably contains a light emitting material as a dopant material and a charge transport material as a host material.
The charge transport material may be any low molecular weight compound conventionally used in the light emitting layer of an organic electroluminescent device, and a compound used as a host material for the light emitting layer is particularly preferable.

Specific examples of charge transport materials include aromatic amine compounds, phthalocyanine compounds, porphyrin compounds, oligothiophene compounds, polythiophene compounds, benzylphenyl compounds, compounds in which tertiary amines are linked by a fluorene group, hydrazone compounds Compounds, silazane compounds, silanamine compounds, phosphamine compounds, quinacridone compounds, anthracene compounds, pyrene compounds, carbazole compounds, pyridine compounds, styryl compounds, phenanthroline compounds, oxadiazole compounds, siloles Compounds and the like.
Further, charge transport materials are roughly classified into hole transport compounds and electron transport compounds.

(Hole transporting compound)
The coated light emitting layer may contain a hole transporting compound as a constituent material. Here, among hole transporting compounds, examples of low molecular weight hole transporting compounds are represented by, for example, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl. An aromatic diamine containing two or more tertiary amines and having two or more condensed aromatic rings substituted with nitrogen atoms (Japanese Patent Laid-Open No. 5-234681), 4,4 ′, 4 ″ -tris (1- Aromatic amine compounds having a starburst structure such as naphthylphenylamino) triphenylamine (Journal of Luminescence, 1997, Vol. 72-74, pp. 985), an aromatic amine compound comprising a tetramer of triphenylamine (Chemical Communications, 1996, pp. 2175), 2,2 ′, 7,7′-tetrakis- (diphenyla Roh) -9,9'-spirobifluorene, etc. spiro compounds of (Synthetic Metals, 1997 years, Vol.91, pp.209), and the like.
In addition, in a coating light emitting layer, only 1 type may be used for a hole transportable compound, and it may use 2 or more types together by arbitrary combinations and a ratio.

(Electron transporting compound)
The coated light emitting layer may contain an electron transporting compound as a constituent material. Here, among the electron transporting compounds, examples of low molecular weight electron transporting compounds include 2,5-bis (1-naphthyl) -1,3,4-oxadiazole (BND), 2,5, -Bis (6 '-(2', 2 "-bipyridyl))-1,1-dimethyl-3,4-diphenylsilole (PyPySPyPy), bathophenanthroline (BPhen), 2,9-dimethyl-4,7 -Diphenyl-1,10-phenanthroline (BCP, bathocuproin), 2- (4-biphenylyl) -5- (p-tertiarybutylphenyl) -1,3,4-oxadiazole (tBu-PBD), 4 , 4′-bis (9-carbazole) -biphenyl (CBP) and the like.

In addition, in a coating light emitting layer, only 1 type may be used for an electron transport compound, and it may use 2 or more types together by arbitrary combinations and a ratio.
Note that only one of the charge transport materials may be used, or two or more may be used in any combination and ratio. In particular, when two or more kinds are combined, it is preferable to use the hole transporting compound and the electron transporting compound in combination.

In particular, when the coating light emitting layer contains a red phosphorescent light emitting material and a green light emitting material, the charge transport material may be an aromatic amine compound, a compound in which a tertiary amine is linked by a fluorene group, a carbazole compound, or a pyridine compound. And silole compounds.
Specific examples of the charge transport material suitable for the present invention are given below, but the present invention is not limited to the following.

In the composition for forming a light emitting layer in the present invention, the charge transporting material is usually 0.1% by weight or more, preferably 0.5% by weight or more, more preferably 1% by weight or more, and usually 20% by weight or less, preferably It is contained at 10% by weight or less, more preferably 5% by weight or less.
In addition, the content ratio of the light emitting material to the charge transport material (light emitting material / charge transport material) in the composition for forming a light emitting layer is usually 0.01 or more, preferably 0.03 or more, and usually 0.5. Hereinafter, it is preferably 0.2 or less.

<Other ingredients>
Unless the effect of this invention is impaired remarkably, the composition for light emitting layer formation in this invention is application | coating of the component, leveling agent, antifoamer, thickener, etc. which are further derived from the positive hole transport layer and hole injection layer mentioned later. It may contain a property improving agent, a charge transporting aid such as an electron accepting compound and an electron donating compound, a binder resin and the like. In addition, these other components may use only 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

In addition, the content of these other components does not significantly inhibit the charge transfer of the formed thin film (coated light emitting layer), does not inhibit the light emission of the light emitting material, does not deteriorate the film quality of the thin film, The content in the coated light emitting layer is usually 5% by weight or less, preferably 1% by weight or less, more preferably 0.5% by weight or less, and particularly preferably 0% by weight (not contained).
From the viewpoint of the effect of the present invention, it is preferable that not only the light emitting material and the charge transport material contained in the composition for forming a light emitting layer, but also all materials contained in the coated light emitting layer are low molecular compounds.

{Vapor-deposited luminescent layer}
In the organic electroluminescent element of the present invention, the second light emitting layer (a layer formed from the anode side through the first light emitting layer among the light emitting layers) is used as the vapor deposition light emitting layer.
In the present invention, the “vacuum deposition method” refers to a method of forming a layer by evaporating a compound in a vacuum.

As the degree of vacuum, in order to facilitate the prevention of collision of the vacuum deposition machine of residual gas molecules, evaporated to lower the evaporation temperature of the vapor deposition material is usually 10 -2 ^Pa or less 10 ^-6, 10 ^{- 3} Pa or less and 10 ⁻⁵ or more are preferable.
In the present invention, the vapor-deposited light-emitting layer is a layer containing a fluorescent light-emitting material from the viewpoint of ease of vapor deposition. Moreover, it is preferable that a vapor deposition light emitting layer contains at least the blue light emitting material which has a maximum light emission wavelength especially in 440-500 nm area | region.

<Charge transport material>
The vapor deposition light emitting layer according to the present invention usually contains a charge transport material in addition to the light emitting material.
The charge transport material contained in the vapor-deposited light-emitting layer is not particularly limited as long as the effect of the present invention is not impaired, and a known low molecular weight material can be used.
In particular, when the vapor-deposited light-emitting layer contains a blue fluorescent light-emitting material, it is particularly preferable to use a compound represented by the following formula (3) as a charge transport material from the viewpoint of excellent durability.

(In Formula (3), Ar ^1A and Ar ^1B each independently represent an aromatic hydrocarbon group that may have a substituent, or an aromatic heterocyclic group that may have a substituent. .
In addition, the anthracene ring in formula (3) may have a substituent other than Ar ^1A and Ar ^1B . )
Ar ^1A and Ar ^1B each independently represent an aromatic hydrocarbon group that may have a substituent or an aromatic heterocyclic group that may have a substituent.

Examples of the aromatic hydrocarbon group of Ar ^1A and Ar ^1B include a benzene ring such as a benzene ring, a naphthalene ring, a phenanthrene ring, an anthracene ring, a pyrene ring, a chrysene ring, a naphthacene ring, and a benzophenanthrene ring. And a group derived from a condensed ring formed by condensation of ˜5.
Specific examples of the aromatic heterocyclic group for Ar ^1A and Ar ^1B include a furan ring, a benzofuran ring, a dibenzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, Carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring , Pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, azulene ring, etc.

As the substituent that the aromatic hydrocarbon group in Ar ^1A and Ar ^1B may have, an alkyl group, an aromatic hydrocarbon group, an aromatic heterocyclic group, an alkoxy group, a (hetero) aryloxy group, an alkylthio group , (Hetero) arylthio groups, cyano groups, dialkylamino groups, alkylarylamino groups, diarylamino groups, and the like. Among these, alkyl groups and aromatic hydrocarbon groups are compounds having stability of the compound. From the viewpoint, an aromatic hydrocarbon group is particularly preferable. The above “(hetero) aryl” refers to both “aryl” and “heteroaryl”. The “aryl group” refers to both “aromatic hydrocarbon group” and “aromatic heterocyclic group”.

As the alkyl group as a substituent that the aromatic hydrocarbon group in Ar ^1A and Ar ^1B may have, an alkyl group having 1 to 20 carbon atoms is preferable. For example, a methyl group, an ethyl group, a propyl group, an iso- Examples include propyl group, butyl group, iso-butyl group, sec-butyl group, tert-butyl group, hexyl group, octyl group, cyclohexyl group, decyl group, octadecyl group and the like. A methyl group, an ethyl group, an iso-propyl group, a sec-butyl group, and a tert-butyl group are preferable. Among these, a methyl group and an ethyl group are preferable from the viewpoint of availability of raw materials and low cost, and an iso-butyl group, a sec-butyl group, and a tert-butyl group are preferable because they have high solubility in nonpolar solvents. .

As an aromatic hydrocarbon group, a C6-C25 thing is preferable and the aromatic hydrocarbon group derived from a 6-membered monocyclic ring or a 2-5 condensed ring is preferable. Examples thereof include groups derived from a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, fluoranthene ring, and the like.
As the aromatic heterocyclic group, those having 3 to 20 carbon atoms are preferable, for example, furan ring, benzofuran ring, dibenzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, Indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzoisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring , Pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, azulene ring, etc. It is.

As an alkoxy group, a C1-C20 thing is preferable, for example, a methoxy group, an ethoxy group, an isopropyloxy group, a cyclohexyloxy group, an octadecyloxy group etc. are mentioned.
As the (hetero) aryloxy group, those having 3 to 20 carbon atoms are preferable, and examples thereof include a phenoxy group, a 1-naphthyloxy group, a 9-anthranyloxy group, and a 2-thienyloxy group.

As an alkylthio group, a C1-C20 thing is preferable, for example, a methylthio group, an ethylthio group, an isopropylthio group, a cyclohexylthio group etc. are mentioned.
As the (hetero) arylthio group, those having 3 to 20 carbon atoms are preferable, and examples thereof include a phenylthio group, a 1-naphthylthio group, a 9-anthranylthio group, and a 2-thienylthio group.

As the dialkylamino group, those having 2 to 29 carbon atoms are preferable, and examples thereof include a diethylamino group, a diisopropylamino group, and a methylethylamino group.
As the alkylarylamino group, those having 7 to 30 carbon atoms are preferable, and examples thereof include a methylphenylamino group.
As the diarylamino group, those having 12 to 30 carbon atoms are preferable, and examples thereof include a diphenylamino group and a phenylnaphthylamino group.

In addition, these substituents may further have a substituent, and examples of the substituent include the alkyl group, aryl group, alkoxy group, and diarylamino group described above. However, the case where the substituents are bonded to form a ring is excluded.
Although the preferable specific example of the charge transport material contained in a vapor deposition light emitting layer is shown below, this invention is not limited to these.

Any one of the charge transport materials may be used, or two or more may be used in any combination and ratio.
<Other ingredients>
The vapor deposition light emitting layer in this invention may contain the other component, unless the effect of this invention is impaired. The other components that may be included are the same as those described in the section <Other components> of the {Coated light emitting layer}.

<Component content>
In the vapor-deposited light emitting layer in the present invention, the light emitting material is usually 0.001% by weight or more, preferably 0.005% by weight or more, more preferably 0.01% by weight or more, and usually 30% by weight or less, preferably 20% by weight. % Or less, more preferably 15% by weight or less.
In the vapor-deposited light emitting layer in the present invention, the charge transport material is usually 0.001% by weight or more, usually 99.999% by weight or less, preferably 99.995% by weight or less, more preferably 99.99% by weight or less. contains.

The ratio of the content of the light-emitting material and the charge transport material in the vapor-deposited light-emitting layer (light-emitting material / charge transport material) is usually 0.01 or more, preferably 0.03 or more, and usually 0.5 or less, preferably Is 0.2 or less.
When the vapor-deposited luminescent layer in the present invention contains other components, the component does not significantly inhibit the charge transfer of the formed thin film (deposited luminescent layer), does not inhibit the luminescence of the luminescent material, and does not deteriorate the film quality of the thin film. In view of the above, it is usually 5% by weight or less, preferably 1% by weight or less, more preferably 0.5% by weight or less, and particularly preferably 0% by weight (not contained).

In addition, from the viewpoint of the effect of the present invention, it is preferable that not only the light emitting material and the charge transport material included in the vapor deposition light emitting layer, but also all the materials included in the light emitting layer are low molecular compounds.
{Middle layer}
In the organic electroluminescent device of the present invention, a vacuum is formed between the coated light emitting layer and the vapor deposited light emitting layer using a charge transport material for the purpose of suppressing energy transfer between the coated light emitting layer and the vapor deposited light emitting layer. You may use the nonluminous intermediate | middle layer laminated | stacked by the vapor deposition method. (It is preferable not to provide an intermediate layer from the viewpoint of driving voltage.)
The charge transport material used for the non-light emitting intermediate layer may be the same as or different from the charge transport material contained in the coated light emitting layer and / or the deposited light emitting layer. Preferably, the charge transporting material is the same as the charge transporting material contained in at least one of the two adjacent light emitting layers. From the viewpoint of the effect of the present invention, the charge transport material used for the intermediate layer is also preferably a low molecular compound.

The intermediate layer may be a hole relaxation layer described later.
{Film thickness}
In the light emitting layer according to the present invention, the thickness of the coated light emitting layer is preferably in the range of 2 to 100 nm, and in particular in the range of 3 to 60 nm, the driving voltage of the resulting element can be lowered. It is preferable in that it can be performed.

Moreover, it is preferable that the film thickness of a vapor deposition light emitting layer exists in the range of 2-100 nm, and it is preferable at the point which can make the drive voltage of the element obtained low especially in the range of 3-100 nm.
Moreover, when a light emitting layer contains an intermediate | middle layer, it is preferable that the film thickness of an intermediate | middle layer exists in the range of 1 nm-50 nm, and it is more preferable that it exists in the range of 3 nm-10 nm. It is thought that a large load is not given to the current-voltage characteristic of an element because it exists in this range.

The total film thickness of the light emitting layer according to the present invention (that is, the total film thickness including the intermediate layer when the coated light emitting layer, the deposited light emitting layer, and the intermediate layer are included) is in the range of 5 to 100 nm. In particular, the range of 10 to 80 nm is preferable in terms of the driving voltage of the resulting element and the stability of the emission color.
[Layer structure of organic electroluminescent element]
Below, the layer structure of the organic electroluminescent element of this invention, its general formation method, etc. are demonstrated with reference to FIG.

FIG. 1 is a schematic cross-sectional view showing a structural example of an organic electroluminescent element 10 of the present invention. In FIG. 1, 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a hole transport layer, 5 Represents a light-emitting layer, 6 represents a hole blocking layer, 7 represents an electron transport layer, 8 represents an electron injection layer, and 9 represents a cathode.
{substrate}
The substrate 1 serves as a support for the organic electroluminescent element, and a quartz or glass plate, a metal plate or a metal foil, a plastic film, a sheet, or the like is used. In particular, a glass plate or a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, polysulfone or the like is preferable. When using a synthetic resin substrate, it is necessary to pay attention to gas barrier properties. If the gas barrier property of the substrate is too small, the organic electroluminescent element may be deteriorated by the outside air that has passed through the substrate, which is not preferable. For this reason, a method of providing a gas barrier property by providing a dense silicon oxide film or the like on at least one surface of the synthetic resin substrate is also a preferable method.

{anode}
The anode 2 serves to inject holes into the layer on the light emitting layer 5 side.
This anode 2 is usually a metal such as aluminum, gold, silver, nickel, palladium, platinum, a metal oxide such as an oxide of indium and / or tin, a metal halide such as copper iodide, carbon black, or It is composed of a conductive polymer such as poly (3-methylthiophene), polypyrrole, or polyaniline.

  In general, the anode 2 is often formed by a sputtering method, a vacuum deposition method, or the like. In addition, when forming the anode 2 using fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, and conductive polymer fine powder, an appropriate binder resin solution It is also possible to form the anode 2 by dispersing it and applying it onto the substrate 1. Furthermore, in the case of a conductive polymer, a thin film can be directly formed on the substrate 1 by electrolytic polymerization, or the anode 2 can be formed by applying a conductive polymer on the substrate 1 (Appl. Phys. Lett. 60, 2711, 1992).

The anode 2 usually has a single-layer structure, but it can also have a laminated structure made of a plurality of materials if desired.
The thickness of the anode 2 varies depending on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more, and is usually 1000 nm or less, preferably about 500 nm or less. When it may be opaque, the thickness of the anode 2 is arbitrary, and the anode 2 may be the same as the substrate 1. Furthermore, it is also possible to laminate different conductive materials on the anode 2 described above.

  For the purpose of removing impurities adhering to the anode 2 and adjusting the ionization potential to improve the hole injection property, the surface of the anode 2 is treated with ultraviolet (UV) / ozone, or with oxygen plasma or argon plasma. It is preferable to do.

{Hole injection layer}
The hole injection layer 3 is a layer that transports holes from the anode 2 to the light emitting layer 5, and is usually formed on the anode 2.
The method for forming the hole injection layer 3 according to the present invention may be a vacuum deposition method or a wet film formation method, and is not particularly limited, but the hole injection layer 3 is formed by a wet film formation method from the viewpoint of reducing dark spots. It is preferable.
The thickness of the hole injection layer 3 is usually 5 nm or more, preferably 10 nm or more, and usually 100 nm.
It is 0 nm or less, preferably 500 nm or less.

<Formation of hole injection layer by wet film formation method>
When the hole injection layer 3 is formed by a wet film formation method, a material for forming the hole injection layer 3 is usually mixed with an appropriate solvent (a solvent for hole injection layer) to form a film-forming composition ( The composition for forming a hole injection layer) is prepared, and this composition for forming the hole injection layer 3 is applied onto a layer corresponding to the lower layer of the hole injection layer (usually the anode 2) by an appropriate technique. The hole injection layer 3 is formed by forming a film and drying.

(Hole transporting compound)
The composition for forming a hole injection layer usually contains a hole transporting compound and a solvent as constituent materials for the hole injection layer 3.
As long as the hole transporting compound is a compound having a hole transporting property that is usually used in the hole injection layer 3 of the organic electroluminescence device, the monomer may be a polymer compound or the like. Although it may be a low molecular compound such as, it is preferably a high molecular compound.

  The hole transporting compound is preferably a compound having an ionization potential of 4.5 eV to 6.0 eV from the viewpoint of a charge injection barrier from the anode 2 to the hole injection layer 3. Examples of hole transporting compounds include aromatic amine derivatives, phthalocyanine derivatives, porphyrin derivatives, oligothiophene derivatives, polythiophene derivatives, benzylphenyl derivatives, compounds in which tertiary amines are linked by a fluorene group, hydrazone derivatives, silazane derivatives, silanamines Derivatives, phosphamine derivatives, quinacridone derivatives, polyaniline derivatives, polypyrrole derivatives, polyphenylene vinylene derivatives, polythienylene vinylene derivatives, polyquinoline derivatives, polyquinoxaline derivatives, carbon and the like.

In the present invention, a derivative includes, for example, an aromatic amine derivative and includes an aromatic amine itself and a compound having an aromatic amine as a main skeleton. It may be a mer.
The hole transporting compound used as the material for the hole injection layer 3 may contain any one of these compounds alone, or may contain two or more. In the case of containing two or more kinds of hole transporting compounds, the combination is arbitrary, but one or more kinds of aromatic tertiary amine polymer compounds and one or two kinds of other hole transporting compounds. It is preferable to use the above in combination.

Among the above examples, an aromatic amine compound is preferable from the viewpoint of amorphousness and visible light transmittance, and an aromatic tertiary amine compound is particularly preferable. Here, the aromatic tertiary amine compound is a compound having an aromatic tertiary amine structure, and includes a compound having a group derived from an aromatic tertiary amine.
The type of the aromatic tertiary amine compound is not particularly limited, but from the viewpoint of uniform light emission due to the surface smoothing effect, a polymer compound having a weight average molecular weight of 1,000 or more and 1,000,000 or less (a polymerizable compound in which repeating units are linked) is further included. preferable. Preferable examples of the aromatic tertiary amine polymer compound include a polymer compound having a repeating unit represented by the following formula (I).

(In formula (I), Ar ¹ and Ar ² each independently represent an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. .Ar ³ to Ar ^5, the .Z ^b representing each independently, may have a which may have aromatic hydrocarbon group or a substituent substituted aromatic heterocyclic group, the following In addition, two groups bonded to the same N atom among Ar ^{1 to} Ar ⁵ may be bonded to each other to form a ring.

(In the above formulas, Ar ^{6 to} Ar ¹⁶ each independently represents an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. R ¹ and R ² each independently represents a hydrogen atom or an arbitrary substituent.))
As the aromatic hydrocarbon group and the aromatic heterocyclic group of Ar ^{1 to} Ar ¹⁶ , a benzene ring, a naphthalene ring, a phenanthrene ring, a thiophene from the viewpoint of the solubility, heat resistance, hole injection / transport property of the polymer compound A group derived from a ring or a pyridine ring is preferred, and a group derived from a benzene ring or a naphthalene ring is more preferred.

The aromatic hydrocarbon group and aromatic heterocyclic group of Ar ^{1 to} Ar ¹⁶ may further have a substituent. The molecular weight of the substituent is usually 400 or less, preferably about 250 or less. As the substituent, an alkyl group, an alkenyl group, an alkoxy group, an aromatic hydrocarbon group, an aromatic heterocyclic group and the like are preferable.
When R ¹ and R ² are optional substituents, examples of the substituent include an alkyl group, an alkenyl group, an alkoxy group, a silyl group, a siloxy group, an aromatic hydrocarbon group, and an aromatic heterocyclic group. .

Specific examples of the aromatic tertiary amine polymer compound having a repeating unit represented by the formula (I) include those described in International Publication No. 2005/089024.
In addition, as a hole transporting compound, a conductive polymer (PEDOT / PSS) obtained by polymerizing 3,4-ethylenedioxythiophene (3,4-ethylenedioxythiophene), which is a derivative of polythiophene, in high molecular weight polystyrene sulfonic acid. Is also preferred. Moreover, the end of this polymer may be capped with methacrylate or the like.

The hole transporting compound may be a crosslinkable compound described in the section {Hole transporting layer} below. The same applies to the film formation method when the crosslinkable compound is used.
The concentration of the hole transporting compound in the composition for forming a hole injection layer is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.01% by weight or more, preferably in terms of film thickness uniformity. Is 0.1% by weight or more, more preferably 0.5% by weight or more, and usually 70% by weight or less, preferably 60% by weight or less, more preferably 50% by weight or less. If this concentration is too high, film thickness unevenness may occur, and if it is too low, defects may occur in the formed hole injection layer.

(Electron-accepting compound)
The composition for forming a hole injection layer preferably contains an electron accepting compound as a constituent material of the hole injection layer 3.
The electron-accepting compound is preferably a compound having an oxidizing power and the ability to accept one electron from the above-described hole transporting compound, specifically, a compound having an electron affinity of 4 eV or more is preferable, and 5 eV or more. The compound which is the compound of these is further more preferable.

  Examples of such electron-accepting compounds include triarylboron compounds, metal halides, Lewis acids, organic acids, onium salts, salts of arylamines and metal halides, and salts of arylamines and Lewis acids. Examples thereof include one or more compounds selected from the group. More specifically, an onium salt substituted with an organic group such as 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) borate and triphenylsulfonium tetrafluoroborate (International Publication No. WO 2005/089024); High valent inorganic compounds such as iron (III) chloride (Japanese Patent Laid-Open No. 11-251067), ammonium peroxodisulfate; cyano compounds such as tetracyanoethylene, tris (pendafluorophenyl) borane (Japanese Patent Laid-Open No. 2003-31365) Aromatic boron compounds such as); fullerene derivatives; iodine; sulfonate ions such as polystyrene sulfonate ions, alkylbenzene sulfonate ions, camphor sulfonate ions, and the like.

These electron accepting compounds can improve the conductivity of the hole injection layer 3 by oxidizing the hole transporting compound.
The content of the electron-accepting compound in the hole-injecting layer 3 or the composition for forming a hole-injecting layer with respect to the hole-transporting compound is usually 0.1 mol% or more, preferably 1 mol% or more. However, it is usually 100 mol% or less, preferably 40 mol% or less.

(Other components)
As a material for the hole injection layer 3, other components may be further contained in addition to the above-described hole transporting compound and electron accepting compound as long as the effects of the present invention are not significantly impaired. Examples of other components include various light emitting materials, electron transporting compounds, binder resins, and coating property improving agents. In addition, only 1 type may be used for another component and it may use 2 or more types together by arbitrary combinations and a ratio.

(solvent)
At least one of the solvents of the composition for forming a hole injection layer used in the wet film formation method is preferably a compound that can dissolve the constituent material of the hole injection layer 3 described above. The boiling point of this solvent is usually 110 ° C. or higher, preferably 140 ° C. or higher, particularly 200 ° C. or higher, usually 400 ° C. or lower, and preferably 300 ° C. or lower. If the boiling point of the solvent is too low, the drying speed is too high and the film quality may be deteriorated. Further, if the boiling point of the solvent is too high, it is necessary to increase the temperature of the drying step, which may adversely affect other layers and the substrate.

Examples of the solvent include ether solvents, ester solvents, aromatic hydrocarbon solvents, amide solvents, and the like.
Examples of ether solvents include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA); 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole , Aromatic ethers such as phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole and 2,4-dimethylanisole.

Examples of the ester solvent include aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate.
Examples of the aromatic hydrocarbon solvent include toluene, xylene, cyclohexylbenzene, 3-isopropylpropylphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, cyclohexylbenzene, and methylnaphthalene. Can be mentioned.

Examples of the amide solvent include N, N-dimethylformamide, N, N-dimethylacetamide, and the like.
In addition, dimethyl sulfoxide and the like can also be used.
These solvent may use only 1 type and may use 2 or more types by arbitrary combinations and a ratio.

(Film formation method)
After preparing the composition for forming the hole injection layer, the composition is applied on the layer corresponding to the lower layer of the hole injection layer 3 (usually the anode 2) by a wet film forming method, and dried. Thus, the hole injection layer 3 is formed.
The temperature in the coating step is preferably 10 ° C. or higher, and preferably 50 ° C. or lower in order to prevent film loss due to the formation of crystals in the composition.

Although the relative humidity in an application | coating process is not limited unless the effect of this invention is impaired remarkably, it is 0.01 ppm or more normally, and usually 80% or less.
After coating, the film of the composition for forming a hole injection layer is usually dried by heating or the like. Examples of the heating means used in the heating step include a clean oven, a hot plate, infrared rays, a halogen heater, microwave irradiation and the like. Among them, a clean oven and a hot plate are preferable in order to uniformly apply heat to the entire film.

  The heating temperature in the heating step is preferably heated at a temperature equal to or higher than the boiling point of the solvent used in the composition for forming a hole injection layer as long as the effects of the present invention are not significantly impaired. In the case of a mixed solvent containing two or more types of solvents used in the hole injection layer, at least one type is preferably heated at a temperature equal to or higher than the boiling point of the solvent. In consideration of an increase in the boiling point of the solvent, the heating step is preferably performed at 120 ° C. or higher, preferably 410 ° C. or lower.

In the heating step, the heating time is not limited as long as the heating temperature is not lower than the boiling point of the solvent of the composition for forming a hole injection layer and sufficient insolubilization of the coating film does not occur. Is less than a minute. If the heating time is too long, the components of the other layers tend to diffuse, and if it is too short, the hole injection layer tends to be inhomogeneous. Heating may be performed in two steps.
<Formation of hole injection layer 3 by vacuum deposition>
When the hole injection layer 3 is formed by vacuum deposition, one or more of the constituent materials of the hole injection layer 3 (the aforementioned hole transporting compound, electron accepting compound, etc.) are placed in a vacuum vessel. Put in crucibles installed (in case of using two or more materials, put them in each crucible), evacuate the inside of the vacuum vessel to about 10 ⁻⁴ Pa with a suitable vacuum pump, and then heat the crucible (two types When using the above materials, heat each crucible) and control the evaporation amount to evaporate (when using two or more materials, control each evaporation amount independently) and face the crucible Then, the hole injection layer 3 is formed on the anode 2 of the substrate 1 placed on the substrate 1. In addition, when using 2 or more types of materials, the hole injection layer 3 can also be formed by putting those mixtures into a crucible, heating and evaporating.

The degree of vacuum at the time of vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 × 10 ⁻⁶ Torr (0.13 × 10 ⁻⁴ Pa) or more, usually 9.0 × 10 ⁻⁶ Torr. (12.0 × 10 ⁻⁴ Pa) or less. The deposition rate is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 Å / second or more and usually 5.0 Å / second or less. The film forming temperature at the time of vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 10 ° C. or higher, preferably 50 ° C. or lower.

{Hole transport layer}
The hole transport layer 4 can be formed on the hole injection layer 3 when the hole injection layer 3 is provided, and on the anode 2 when the hole injection layer 3 is not provided. The organic electroluminescent element of the present invention may have a configuration in which the hole transport layer 4 is omitted, but as described above, the organic electroluminescent element of the present invention preferably has a hole transport layer.

The formation method of the hole transport layer 4 may be a vacuum deposition method or a wet film formation method, and is not particularly limited. However, from the viewpoint of reducing dark spots, the hole transport layer 4 is preferably formed by a wet film formation method.
The material for forming the hole transport layer 4 is preferably a material having high hole transportability and capable of efficiently transporting injected holes. Therefore, it is preferable that the ionization potential is small, the transparency to visible light is high, the hole mobility is large, the stability is high, and impurities that become traps are not easily generated during manufacturing or use. In many cases, it is preferable not to quench the light emitted from the light emitting layer 5 or to form an exciplex with the light emitting layer 5 to reduce the efficiency because it is in contact with the light emitting layer 5.

  The material for the hole transport layer 4 may be any material that has been conventionally used as a constituent material for the hole transport layer 4. For example, the hole transport layer used for the hole injection layer 3 described above. What was illustrated as an ionic compound is mentioned. In addition, arylamine derivatives, fluorene derivatives, spiro derivatives, carbazole derivatives, pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, phthalocyanine derivatives, porphyrin derivatives, silole derivatives, oligothiophene derivatives, condensed polycyclic aromatics Group derivatives, metal complexes and the like.

In addition, for example, polyvinylcarbazole derivatives, polyarylamine derivatives, polyvinyltriphenylamine derivatives, polyfluorene derivatives, polyarylene derivatives, polyarylene ether sulfone derivatives containing tetraphenylbenzidine, polyarylene vinylene derivatives, polysiloxane derivatives, polythiophenes Derivatives, poly (p-phenylene vinylene) derivatives, and the like. These may be any of an alternating copolymer, a random polymer, a block polymer, or a graft copolymer. Further, it may be a polymer having a branched main chain and three or more terminal portions, or a so-called dendrimer.

Of these, polyarylamine derivatives and polyarylene derivatives are preferred.
The polyarylamine derivative is preferably a polymer containing a repeating unit represented by the following formula (II). In particular, the polymer is preferably composed of a repeating unit represented by the following formula (II). In this case, Ar ^a or Ar ^b may be different in each repeating unit.

(In formula (II), Ar ^a and Ar ^b each independently represent an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent.)
Examples of the aromatic hydrocarbon group optionally having a substituent for Ar ^a and Ar ^b include a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene A group derived from a 6-membered monocyclic ring or a 2-5 condensed ring, such as a ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, a fluorene ring, and a group formed by connecting these rings by two or more direct bonds. .

  Examples of the aromatic heterocyclic group which may have a substituent include a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, and a carbazole ring. , Pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzoisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine Ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, azulene ring, etc. ring Are those groups groups and the rings from 2-4 fused ring is linked by a direct bond or two or more rings.

From the viewpoints of solubility and heat resistance, Ar ^a and Ar ^b are each independently selected from the group consisting of a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, triphenylene ring, pyrene ring, thiophene ring, pyridine ring, and fluorene ring. A group derived from a selected ring or a group formed by linking two or more benzene rings (for example, a biphenyl group (biphenyl group) or a terphenylene group (terphenylene group)) is preferable.

Among these, a group derived from a benzene ring (phenyl group), a group formed by connecting two benzene rings (biphenyl group), and a group derived from a fluorene ring (fluorenyl group) are preferable.
Examples of the substituent that the aromatic hydrocarbon group and aromatic heterocyclic group in Ar ^a and Ar ^b may have include an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, and a dialkyl. Examples thereof include an amino group, a diarylamino group, an acyl group, a halogen atom, a haloalkyl group, an alkylthio group, an arylthio group, a silyl group, a siloxy group, a cyano group, an aromatic hydrocarbon ring group, and an aromatic heterocyclic group.

As the polyarylene derivative, an arylene group such as an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent exemplified as Ar ^a or Ar ^b in the formula (II) is used as ^a repeating unit. The polymer which has is mentioned.
As a polyarylene derivative, the polymer which has a repeating unit which consists of following formula (V-1) and / or following formula (V-2) is preferable.

(In formula (V-1), R ^a , R ^b , R ^c and R ^d are each independently an alkyl group, an alkoxy group, a phenylalkyl group, a phenylalkoxy group, a phenyl group, a phenoxy group, an alkylphenyl group, Represents an alkoxyphenyl group, an alkylcarbonyl group, an alkoxycarbonyl group, or a carboxy group, and t and s each independently represent an integer of 0 to 3. When t or s is 2 or more, they are contained in one molecule. A plurality of R ^a or R ^b may be the same or different, and adjacent R ^a or R ^b may form a ring.)

(In formula (V-2), R ^e and R ^f are each independently the same as R ^a , R ^b , R ^c or R ^d in formula (V-1). Independently, it represents an integer of 0 to 3. When r or u is 2 or more, a plurality of R ^e and R ^f contained in one molecule may be the same or different, and adjacent R ^e or R ^f may form a ring, and X represents an atom or a group of atoms constituting a 5-membered ring or a 6-membered ring.)
Specific examples of X are —O—, —BR—, —NR—, —SiR ₂ —, —PR—, —SR—, —CR ₂ — or a group formed by bonding thereof. R represents a hydrogen atom or an arbitrary organic group. The organic group in the present invention is a group containing at least one carbon atom.

  Moreover, as a polyarylene derivative, in addition to the repeating unit which consists of said Formula (V-1) and / or said Formula (V-2), it further has a repeating unit represented by following formula (V-3). Is preferred.

(In the formula (V-3), Ar ^{c to} Ar ^j each independently represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent. Independently represents 0 or 1.)
Specific examples of Ar ^{c to} Ar ^j are the same as Ar ^a and Ar ^b in the formula (II).
Specific examples of the above formulas (V-1) to (V-3) and specific examples of polyarylene derivatives include those described in JP-A-2008-98619.

In the case of forming the hole transport layer 4 by a wet film formation method, a composition for forming a hole transport layer is prepared in the same manner as the formation of the hole injection layer 3 and then heated and dried after the wet film formation. .
The composition for forming a hole transport layer contains a solvent in addition to the above hole transport compound. The solvent used is the same as that used for the composition for forming a hole injection layer. The film forming conditions, heat drying conditions, and the like are the same as in the case of forming the hole injection layer 3.

When the hole transport layer 4 is formed by the vacuum deposition method, the film forming conditions are the same as those for the hole injection layer 3.
The hole transport layer 4 may contain various light emitting materials, electron transport compounds, binder resins, coating property improving agents, and the like in addition to the hole transport compound.
The hole transport layer 4 may also be a layer formed by crosslinking a crosslinkable compound. The crosslinkable compound is a compound having a crosslinkable group, and forms a network polymer compound by crosslinking.

Examples of this crosslinkable group include groups derived from cyclic ethers such as oxetane and epoxy; groups derived from unsaturated double bonds such as vinyl, trifluorovinyl, styryl, acrylic, methacryloyl and cinnamoyl; benzo Examples include groups derived from cyclobutene.
The crosslinkable compound may be any of a monomer, an oligomer, and a polymer. The crosslinkable compound may have only 1 type, and may have 2 or more types by arbitrary combinations and ratios.

  As the crosslinkable compound, a hole transporting compound having a crosslinkable group is preferably used. Examples of the hole transporting compound include those exemplified above, and those having a crosslinkable group bonded to the main chain or side chain with respect to these hole transporting compounds. In particular, the crosslinkable group is preferably bonded to the main chain via a linking group such as an alkylene group. In particular, the hole transporting compound is preferably a polymer containing a repeating unit having a crosslinkable group, and the above formula (II) and formulas (V-1) to (V-3) are represented by a crosslinkable group. Is preferably a polymer having a repeating unit bonded directly or via a linking group.

  As the crosslinkable compound, a hole transporting compound having a crosslinkable group is preferably used. Examples of hole transporting compounds include nitrogen-containing aromatic compound derivatives such as pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, carbazole derivatives, phthalocyanine derivatives, porphyrin derivatives; triphenylamine derivatives Silole derivatives; oligothiophene derivatives, condensed polycyclic aromatic derivatives, metal complexes and the like. Among them, nitrogen-containing aromatic derivatives such as pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, carbazole derivatives; triphenylamine derivatives, silole derivatives, condensed polycyclic aromatic derivatives, metal complexes, etc. Particularly preferred are triphenylamine derivatives.

In order to form a hole transport layer 4 by crosslinking a crosslinkable compound, a composition for forming a hole transport layer in which a crosslinkable compound is dissolved or dispersed in a solvent is usually prepared and deposited by wet film formation. To crosslink.
The composition for forming a hole transport layer may contain an additive for promoting a crosslinking reaction in addition to the crosslinking compound. Examples of additives that accelerate the crosslinking reaction include polymerization initiators and polymerization accelerators such as alkylphenone compounds, acylphosphine oxide compounds, metallocene compounds, oxime ester compounds, azo compounds, onium salts; condensed polycyclic hydrocarbons, And photosensitizers such as porphyrin compounds and diaryl ketone compounds.

Further, it may contain a coating property improving agent such as a leveling agent and an antifoaming agent; an electron accepting compound; a binder resin;
In the composition for forming a hole transport layer, the crosslinkable compound is usually 0.01% by weight or more, preferably 0.05% by weight or more, more preferably 0.1% by weight or more, usually 50% by weight or less, preferably 20%. It is contained by weight% or less, more preferably 10% by weight or less.

After forming a composition for forming a hole transport layer containing a crosslinkable compound at such a concentration on the lower layer (usually the hole injection layer 3), the composition is crosslinkable by heating and / or irradiation with active energy such as light. Are crosslinked to form a network polymer compound.
Conditions such as temperature and humidity during film formation are the same as those during wet film formation of the hole injection layer.
The heating method after film formation is not particularly limited. As heating temperature conditions, it is 120 degreeC or more normally, Preferably it is 400 degrees C or less.

The heating time is usually 1 minute or longer, preferably 24 hours or shorter. The heating means is not particularly limited, and means such as placing a laminated body having a deposited layer on a hot plate or heating in an oven is used. For example, conditions such as heating on a hot plate at 120 ° C. or more for 1 minute or more can be used.
In the case of irradiation with active energy such as light, a method of irradiating directly using an ultraviolet / visible / infrared light source such as an ultra-high pressure mercury lamp, a high-pressure mercury lamp, a halogen lamp, an infrared lamp, or the above-mentioned light source is incorporated. Examples include a mask aligner and a method of irradiation using a conveyor type light irradiation device. In active energy irradiation other than light, for example, there is a method of irradiation using a so-called microwave oven that irradiates a microwave generated by a magnetron. As the irradiation time, it is preferable to set conditions necessary for reducing the solubility of the film, but irradiation is usually performed for 0.1 seconds or longer, preferably 10 hours or shorter.

Heating and irradiation of active energy such as light may be performed individually or in combination. When combined, the order of implementation is not particularly limited.
The film thickness of the hole transport layer 4 thus formed is usually 5 nm or more, preferably 10 nm or more, and usually 300 nm or less, preferably 100 nm or less.

{Light emitting layer}
When the hole injection layer 3 or the hole transport layer 4 is provided, the light emitting layer 5 is provided on the hole transport layer 4. The light emitting layer 5 is a layer that is excited by recombination of holes injected from the anode 2 and electrons injected from the cathode 9 between electrodes to which an electric field is applied, and becomes a main light emitting source.
For the light emitting layer 5, the above description of [light emitting layer] is applied.

{Hole relaxation layer}
Although not shown in FIG. 1, the organic electroluminescent element of the present invention may have a hole relaxation layer.
The hole relaxation layer is a layer formed adjacent to the cathode side of the light emitting layer, and is a layer that functions to relax the accumulation of holes at the interface between the light emitting layer and the hole relaxation layer. It also has a role of efficiently transporting electrons toward the light emitting layer.

The hole relaxation layer may be formed between the coated light emitting layer and the vapor deposited light emitting layer.
The ionization potential of the hole relaxation layer is usually 5.5 eV or more, preferably 5.6 eV or more, more preferably 5.7 eV or more, and usually 6.7 eV or less, preferably 6.4 eV or less, more preferably 6.0 eV or less. It is. If the value of the ionization potential is too large or too small, there is a possibility that holes are retained at the interface between the light emitting layer and the hole relaxation layer.

The thickness of the hole relaxation layer is arbitrary as long as the effect of the present invention is not significantly impaired, but is preferably 0.3 nm or more, more preferably 0.5 nm or more, preferably 100 nm or less, more preferably 50 nm or less. It is. If the thickness of the hole relaxation layer is too thin, defects may occur in the thin film, and if it is too thick, the driving voltage may be increased.
The hole relaxation layer is preferably formed by a vacuum deposition method, and examples of the vacuum deposition method include the methods described above.

  Although the electron transport layer is usually formed adjacent to the cathode side of the hole relaxation layer, the difference in ionization potential between the hole relaxation layer and the electron transport layer is arbitrary as long as the effect of the present invention is not significantly impaired. , Usually less than 0.5 eV, preferably less than 0.3 eV, more preferably less than 0.2 eV. If the difference in ionization potential is too large, holes may accumulate in the hole relaxation layer and cause deterioration.

In the present invention, an organic compound having a hole transporting unit and an electron transporting unit is used for the hole relaxation layer as a hole relaxation material. Here, the hole transporting unit (hole transporting unit) is a structure (unit) having excellent durability against holes and having hole transporting properties.
An electron transporting unit (electron transport unit) is a structure (unit) having excellent durability against electrons and having electron transport properties.

The hole mobility μH of the hole relaxation material in the present invention is usually 1 × 10 ⁻⁶ cm ⁻² / V · s or more, preferably 1 × 10 ⁻⁴ cm ^{−2 in the following} method for measuring the charge mobility. / V · s or more, more preferably 1 × 10 ⁻³ cm ⁻² / V · s or more.
The higher the hole mobility, the lower the drive voltage when the device is made. Therefore, the upper limit is not particularly limited, but it is usually 1 × 10 ⁻¹ cm ⁻² / V · s or less.

Further, the electron mobility μE of the hole relaxation material is usually 1 × 10 ⁻⁶ cm ⁻² / V · s or more, preferably 1 × 10 ⁻⁵ cm ⁻² / V · s by the following method for measuring the charge mobility. s, more preferably 1 × 10 ⁻⁴ cm ⁻² / V · s or more.
The higher the electron mobility, the lower the drive voltage when the device is used. Therefore, the upper limit is not particularly limited, but it is usually 1 × 10 ⁻¹ cm ⁻² / V · s or less.

Within the above range, the charge residence time in the layer is short, and the layer is not easily deteriorated by holes or electrons, which is preferable.
Further, the ratio (μE / μH) between the electron mobility and the hole mobility of the hole relaxation material is usually in the range of 100 to 0.1, preferably 50 to 0.5, more preferably 10 to 0.5. It is.
When this ratio (μE / μH) is within the above range, holes and electrons are unlikely to flow from the light emitting layer to other layers, so that deterioration of the elements due to holes and electrons is unlikely to occur, and the drive life of the resulting element Is preferable in terms of a long point.

The hole relaxation material used in the present invention is an organic compound having a structure in which one or more hole transport units and one or more electron transport units are combined in an arbitrary ratio.
The hole transport unit in the present invention is a structure (unit) having excellent durability against holes and having a hole transport property. More specifically, the unit has an ionization potential that facilitates extraction of holes from the light emitting layer and is stable to holes.

The ionization potential at which holes are easily extracted from the light emitting layer is usually 5.4 to 6.3 eV, preferably 5.5 to 6.2 eV, and more preferably 5.6 to 6.1 eV.
Further, being stable to holes means that the hole transport unit is not easily decomposed even in a radical state. This means that the radical cation is delocalized so that it is stabilized even in the radical state.

Examples of the structure of the unit having the above performance include a structure containing a hetero atom having an sp3 orbital, or an aromatic condensed ring having 4n carbon atoms.
More specifically, carbazole ring, phthalocyanine ring, naphthalocyanine structure, porphyrin structure, triarylamine structure, triarylphosphine structure, benzofuran ring, dibenzofuran ring, pyrene ring, phenylenediamine structure, pyrrole ring, benzidine structure, aniline structure , Diarylamine structure, imidazolidinone structure, pyrazole ring and the like.

Among these, a carbazole ring, a benzofuran ring, a dibenzofuran ring, a pyrene ring, and a triarylamine structure are preferable, a carbazole ring, a benzofuran ring, a dibenzofuran ring, and a pyrene ring are more preferable, and a carbazole ring and a pyrene ring are particularly preferable. And most preferably a carbazole ring.
The electron transport unit in the present invention is a structure (unit) having excellent durability against electrons and having electron transport characteristics. More specifically, it is a unit in which electrons easily enter the unit, and the entered electrons are easily stabilized. For example, a pyridine ring or the like has a slight electron deficiency due to a nitrogen atom, easily accepts an electron, and the electron entering the ring is delocalized to be stabilized on the pyridine ring.

Examples of the structure of the unit having the above performance include a single ring or a condensed ring containing a hetero atom composed of sp2 hybrid orbitals.
More specifically, quinoline ring, quinazoline ring, quinoxaline ring, phenanthroline ring, pyridine ring, pyrimidine ring, pyridazine ring, pyrazine ring, triazine ring, thiadiazole ring, benzothiadiazole ring, quinolinol metal complex, phenanthroline metal complex, hexaazane Examples include a triphenylene structure and a tetrasiabenzoquinoline structure.

Among these, preferably, a quinoline ring, a quinazoline ring, a quinoxaline ring, a phenanthroline ring, a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring, and a triazine ring, and among them, a quinoline ring, a quinazoline ring, A pyridine ring, a pyrimidine ring, a triazine ring, and a 1,10-phenanthroline ring are particularly preferable.
When the electron transport unit is a 6-membered monocyclic ring or condensed ring containing a nitrogen atom, the o-position and p-position are all substituted with aromatic rings with respect to the nitrogen atom. preferable.

This is because the o-position and p-position of the six-membered ring containing a nitrogen atom are active sites, and this is delocalized by substitution with an aromatic ring group. By becoming stable.
That is, the hole relaxation material in the present invention is excellent in durability against electrical redox.

In the case where the electron transport unit is a condensed ring, a part of the o-position and p-position of the nitrogen atom that does not form part of the condensed ring is substituted with an aromatic ring group. Good.
As the hole relaxation material, an organic compound having a combination of a ring derivative listed in the following group (a) (hole transport unit) and a ring derivative listed in the following group (b) (electron transport unit) is more preferable. .

(However, all the rings included in the group (b) are substituted with aromatic rings at the o-position and p-position with respect to the nitrogen atom.)
In the group (b), the aromatic ring group in which the hydrogen atoms on the carbon atoms at the 2, 4 and 6 positions in the same ring are substituted with respect to the nitrogen atom is not particularly limited. That is, it may be an aromatic hydrocarbon group or an aromatic heterocyclic group, but is preferably an aromatic hydrocarbon group from the viewpoint of excellent durability against electrical oxidation.
Examples of the hole relaxation material include a compound having a structure represented by the following general formula (1).

(In general formula (1),
A each independently represents a hole transport unit having 1 to 30 carbon atoms,
B each independently represents an electron transport unit having 1 to 30 carbon atoms,
Q represents an alkylene group having 1 to 10 carbon atoms, an alkenylene group having 2 to 10 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 30 carbon atoms,
These may have a substituent.

n and m represent an integer of 1 to 4, and l represents an integer of 0 to 3.
In the general formula (1), when l, m, and n are 2 or more, a plurality of Q, A, and B may be the same or different. )
Examples of the hole transport unit A and the electron transport unit B include those described above. Specific examples and preferred embodiments are also the same.

In formula (1), Q represents an alkylene group having 1 to 10 carbon atoms, an alkenylene group having 2 to 10 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 30 carbon atoms.
The alkylene group having 1 to 10 carbon atoms is preferably an alkylene group having 1 to 8 carbon atoms. Specific examples thereof include a methylene group, 1,2-ethylene group, 1,3-propylene group, 1,4 -Butylene group, 1,5-pentylene group, 1,8-octylene group and the like can be mentioned, and a methylene group and 1,2-ethylene group are preferable in that synthesis is simple.

  The alkenylene group having 2 to 10 carbon atoms is preferably an alkenylene group having 2 to 6 carbon atoms, and specific examples thereof include 1,2-vinylene group, 1,3-propenylene group, 1,2-propenylene. Group, 1,4-butenylene group and the like, and further, in terms of improving the stability of the compound by spreading the conjugate plane by improving the planarity of the molecule and delocalizing the charge more. A vinylene group is preferable.

Moreover, as a C6-C30 bivalent aromatic hydrocarbon group, the bivalent group formed by monocyclic, 2-5 condensed rings, or these two or more connected is mentioned. Here, the plurality is usually 2 to 8, preferably 2 to 5, in terms of high ring stability.
Specific examples of the divalent aromatic hydrocarbon group include divalent aromatics derived from benzene ring, naphthalene ring, phenanthrene ring, anthracene ring, triphenylene ring, chrysene ring, naphthacene ring, perylene ring, coronene ring and the like. A divalent group derived from a benzene ring, a naphthalene ring, an anthracene ring, or a triphenylene ring is preferable from the viewpoint of high stability of the ring.
The molecular weight of the hole relaxation material is usually 10,000 or less, preferably 5000 or less, more preferably 4000 or less, still more preferably 3000 or less, and usually 100 or more, preferably 200 or more, more preferably 300 or more, and still more preferably 400. It is the above range.

{Hole blocking layer}
A hole blocking layer 6 may be provided between the light emitting layer 5 and an electron injection layer 8 described later. The hole blocking layer 6 is a layer laminated on the light emitting layer 5 so as to be in contact with the interface of the light emitting layer 5 on the cathode 9 side. That is, the hole blocking layer 6 may be provided in place of the hole relaxation layer.
The hole blocking layer 6 has a role of blocking holes moving from the anode 2 from reaching the cathode 9 and a role of efficiently transporting electrons injected from the cathode 9 toward the light emitting layer 5. Have
The physical properties required for the material constituting the hole blocking layer 6 include high electron mobility, low hole mobility, a large energy gap (difference between HOMO and LUMO), and excited triplet level (T1). Is high. Examples of the material of the hole blocking layer 6 satisfying such conditions include, for example, bis (2-methyl-8-quinolinolato) (phenolato) aluminum, bis (2-methyl-8-quinolinolato) (triphenylsilanolato) aluminum. Mixed ligand complexes such as, metal complexes such as bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolato) aluminum binuclear metal complexes, distyrylbiphenyl derivatives, etc. Of styryl compounds (JP-A-11-242996), triazole derivatives such as 3- (4-biphenylyl) -4-phenyl-5 (4-tert-butylphenyl) -1,2,4-triazole 7-41759), phenanthroline derivatives such as bathocuproine (JP-A-10-79297), and the like. It is. Further, a compound having at least one pyridine ring substituted at positions 2, 4, and 6 described in International Publication No. 2005-022962 is also preferable as a material for the hole blocking layer 6.

In addition, the material of the hole-blocking layer 6 may use only 1 type, and may use 2 or more types together by arbitrary combinations and ratios.
There is no restriction | limiting in the formation method of the hole-blocking layer 6. FIG. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.
The thickness of the hole blocking layer 6 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less.

{Electron transport layer}
An electron transport layer 7 may be provided between the light emitting layer 5 and an electron injection layer 8 described later.
The electron transport layer 7 is provided for the purpose of further improving the light emission efficiency of the device, and efficiently transports electrons injected from the cathode 9 between the electrodes to which an electric field is applied in the direction of the light emitting layer 5. Formed from a compound capable of

  As an electron transporting compound used for the electron transport layer 7, usually, the electron injection efficiency from the cathode 9 or the electron injection layer 8 is high, and the injected electrons having high electron mobility are efficiently transported. The compound which can be used is used. Examples of the compound satisfying such conditions include metal complexes such as aluminum complexes of 8-hydroxyquinoline (Japanese Patent Laid-Open No. 59-194393), metal complexes of 10-hydroxybenzo [h] quinoline, oxadiazole derivatives , Distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (US Pat. No. 5,645,948), quinoxaline compounds ( JP-A-6-207169), phenanthroline derivative (JP-A-5-331459), 2-t-butyl-9,10-N, N'-dicyanoanthraquinonediimine, n-type hydrogenated amorphous silicon carbide , N-type zinc sulfide, n-type zinc Such as emissions of zinc, and the like.

In addition, the material of the electron carrying layer 7 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
There is no restriction | limiting in the formation method of the electron carrying layer 7. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.
The thickness of the electron transport layer 7 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 1 nm or more, preferably 5 nm or more, and usually 300 nm or less, preferably 100 nm or less.

{Electron injection layer}
The electron injection layer 8 plays a role of efficiently injecting electrons injected from the cathode 9 into the light emitting layer 5. In order to perform electron injection efficiently, the material for forming the electron injection layer 8 is preferably a metal having a low work function. Examples include alkali metals such as sodium and cesium, alkaline earth metals such as barium and calcium, and the film thickness is preferably from 0.1 nm to 5 nm.

  Furthermore, an organic electron transport compound represented by a metal complex such as a nitrogen-containing heterocyclic compound such as bathophenanthroline or an aluminum complex of 8-hydroxyquinoline is doped with an alkali metal such as sodium, potassium, cesium, lithium, or rubidium ( (As described in JP-A-10-270171, JP-A-2002-1000047, JP-A-2002-1000048, etc.), it is possible to improve the electron injection / transport properties and achieve excellent film quality. preferable. In this case, the film thickness is usually 5 nm or more, preferably 10 nm or more, and is usually 200 nm or less, preferably 100 nm or less.

In addition, the material of the electron injection layer 8 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
There is no restriction | limiting in the formation method of the electron injection layer 8. FIG. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.

{cathode}
The cathode 9 plays a role of injecting electrons into a layer on the light emitting layer 5 side (such as the electron injection layer 8 or the light emitting layer 5).
As the material of the cathode 9, the material used for the anode 2 can be used. However, a metal having a low work function is preferable for efficient electron injection. For example, tin, magnesium, indium, A suitable metal such as calcium, aluminum, silver, or an alloy thereof is used. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy.

In addition, the material of the cathode 9 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The film thickness of the cathode 9 is usually the same as that of the anode 2.
Further, for the purpose of protecting the cathode 9 made of a low work function metal, it is preferable to further stack a metal layer having a high work function and stable to the atmosphere because the stability of the device is increased. For this purpose, for example, metals such as aluminum, silver, copper, nickel, chromium, gold and platinum are used. In addition, these materials may be used only by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

{Other layers}
The organic electroluminescent element according to the present invention may have another configuration without departing from the gist thereof. For example, as long as the performance is not impaired, an arbitrary layer may be provided between the anode 2 and the cathode 9 in addition to the layers described above, and an arbitrary layer may be omitted. .

Examples of the layer that may be included in addition to the layers described above include an electron blocking layer.
The electron blocking layer is provided between the hole injection layer 3 or the hole transport layer 4 and the light emitting layer 5 and prevents electrons moving from the light emitting layer 5 from reaching the hole injection layer 3. Thus, the probability of recombination of holes and electrons in the light emitting layer 5 is increased, the excitons generated are confined in the light emitting layer 5, and the holes injected from the hole injection layer 3 are efficiently collected. There is a role to transport in the direction of. In particular, when a phosphorescent material or a blue light emitting material is used as the light emitting material, it is effective to provide an electron blocking layer.

  The characteristics required for the electron blocking layer include high hole transportability, a large energy gap (difference between HOMO and LUMO), and a high excited triplet level (T1). Furthermore, in the present invention, when the light emitting layer 5 is formed as an organic layer according to the present invention by a wet film formation method, the electron blocking layer is also required to be compatible with the wet film formation. Examples of the material used for such an electron blocking layer include a copolymer of dioctylfluorene and triphenylamine typified by F8-TFB (International Publication No. 2004/084260).

In addition, the material of an electron blocking layer may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
There is no restriction | limiting in the formation method of an electron blocking layer. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.
Further, at the interface between the cathode 9 and the light emitting layer 5 or the electron transport layer 7, for example, lithium fluoride (LiF), magnesium fluoride (MgF ₂ ), lithium oxide (Li ₂ O), cesium carbonate (II) (CsCO ₃ ). Inserting an ultrathin insulating film (0.1 to 5 nm) formed by the above method is also an effective method for improving the efficiency of the device (Applied Physics Letters, 1997, Vol. 70, pp. 152; (Kaihei 10-74586; IEEE Transactions on Electron Devices, 1997, Vol. 44, pp. 1245; SID 04 Digest, pp. 154, etc.).

Moreover, in the layer structure demonstrated above, it is also possible to laminate | stack components other than a board | substrate in reverse order. For example, in the case of the layer configuration of FIG. 1, the other components on the substrate 1 are the cathode 9, the electron injection layer 8, the electron transport layer 7, the hole blocking layer 6 or the hole relaxation layer, the light emitting layer 5, and the holes. The transport layer 4, the hole injection layer 3, and the anode 2 may be provided in this order.
Furthermore, it is also possible to constitute the organic electroluminescent element according to the present invention by laminating components other than the substrate between two substrates, at least one of which is transparent.

In addition, a structure in which a plurality of components (light emitting units) other than the substrate are stacked in a plurality of layers (a structure in which a plurality of light emitting units are stacked) may be employed. In that case, instead of the interface layer between the steps (between the light emitting units) (in the case where the anode is ITO and the cathode is Al, these two layers), for example, a charge made of vanadium pentoxide (V ₂ O ₅ ) or the like. When a generation layer (Carrier Generation Layer: CGL) is provided, a barrier between steps is reduced, which is more preferable from the viewpoint of light emission efficiency and driving voltage.

Furthermore, the organic electroluminescent device according to the present invention may be configured as a single organic electroluminescent device, or may be applied to a configuration in which a plurality of organic electroluminescent devices are arranged in an array. You may apply to the structure by which the cathode is arrange | positioned at XY matrix form.
Each layer described above may contain components other than those described as materials unless the effects of the present invention are significantly impaired.

≪Organic EL display device≫
The organic EL display device of the present invention uses the above-described organic electroluminescent element of the present invention. There is no restriction | limiting in particular about the model and structure of the organic electroluminescent display apparatus of this invention, It can assemble in accordance with a conventional method using the organic electroluminescent element of this invention.
For example, the method of the present invention is described in “Organic EL display” (O-BR> [M Corp., issued on August 20, 2004, by Shizushi Tokito, Chiba Adachi, Hideyuki Murata). An organic EL display device can be formed.

≪Organic EL lighting≫
The organic EL illumination of the present invention uses the above-described organic electroluminescent element of the present invention. There is no restriction | limiting in particular about the model and structure of the organic EL illumination of this invention, It can assemble in accordance with a conventional method using the organic electroluminescent element of this invention.

EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited to description of a following example, unless the summary is exceeded.
In addition, the maximum light emission wavelength of the light emitting material used in the following examples and comparative examples is about 1.0 × 10 ⁻⁵ M to 1.0 × 10 ⁻⁶ M of toluene (in the case of poor solubility) for each material. (Methylene chloride) solution was prepared, and the emission spectrum was measured using a spectrophotometer “F4500” manufactured by Hitachi, Ltd. using the solution. Table 1 below shows the maximum emission wavelength of each luminescent material.

[Example 1]
An organic electroluminescent device having the structure shown in FIG. 1 was produced except that the hole blocking layer 6 was omitted.
<Anode>
An indium tin oxide (ITO) transparent conductive film formed on a glass substrate with a thickness of 150 nm (sputtered film, sheet resistance of 15Ω) is patterned into a 2 mm wide stripe by ordinary photolithography technology. Anode 2 was formed. The substrate 1 on which the anode 2 was formed was cleaned in the order of ultrasonic cleaning with acetone, water with pure water, and ultrasonic cleaning with isopropyl alcohol, dried with nitrogen blow, and finally subjected to ultraviolet ozone cleaning and the like.

<Hole injection layer>
Next, the hole injection layer 3 was formed by a wet film formation method as follows.
As a composition for forming a hole injection layer, 2% by weight of a hole transporting polymer compound having a repeating structure of the following formula (P1) and 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) as an oxidizing agent ) A composition in which 0.8% by weight of borate was dissolved in ethyl benzoate was prepared, and this composition was formed on the ITO substrate by spin coating.

  As spin coating conditions, spinner rotation speed was 500 rpm, 2 seconds, and 1500 rpm, 30 seconds. Drying was performed by heating for 1 hour in a 230 ° C. clean oven to form a hole injection layer 3 having a thickness of 40 nm.

<Hole transport layer>
Next, a hole transport layer 4 was formed on the formed hole injection layer 3 as follows.
A composition for forming a hole transport layer containing a polymer compound (HT-1) having a repeating structure shown below (weight average molecular weight: 45000) as a crosslinkable compound and cyclohexylbenzene as a solvent was prepared. The concentration of the polymer compound (HT-1) in the composition for forming a hole transport layer was 1.0% by weight.

The composition for forming a hole transport layer was spin-coated on the hole injection layer 3 in two stages: spinner rotation speed 500 rpm, spinner rotation time 2 seconds, spinner rotation speed 1500 rpm, spinner rotation time 120 seconds. Thereafter, the polymer compound (HT-1) was cured by heating at 230 ° C. for 60 minutes to cause a crosslinking reaction.
By the above operation, a uniform thin film of the hole transport layer 4 having a thickness of 10 nm was formed.

<Coating light emitting layer>
Next, a coated light emitting layer was formed on the formed hole transport layer 4 as follows.
The following compounds (GH-1), (GH-2), (GD-1) and (RD-1) were mixed at a weight ratio of 25: 75: 10: 0.7, and this mixture 1.7. A composition in which wt% was dissolved in cyclohexylbenzene was prepared, and this composition was formed by spin coating on the hole transport layer 4 in a nitrogen atmosphere.

As spin coating conditions, spinner rotation speed was 500 rpm, 2 seconds, and 1500 rpm, 120 seconds. Then, the coating light emitting layer with a film thickness of 20 nm was formed by drying at 130 degreeC for 1 hour.
The compound (GD-1) is a green phosphorescent material having a maximum emission wavelength at 515 nm, and (RD-1) is a red phosphorescence material having a maximum emission wavelength at 616 nm.

<Vapor deposition light emitting layer>
Next, a deposited light emitting layer was formed on the formed coated light emitting layer by a vacuum deposition method.
The following compounds (BH-1) and (BD-1) were deposited by vacuum deposition at a weight ratio of 100: 5 to form a deposited light-emitting layer having a thickness of 30 nm.

The compound (BD-1) is a blue fluorescent light-emitting material having a maximum emission wavelength at 461 nm.
<Electron transport layer>
Next, a compound (ET-1) shown below as an electron transport layer 7 was formed on the deposited light emitting layer so as to have a film thickness of 20 nm by a vacuum deposition method.

<Electron injection layer / cathode>
Here, the element that has been vapor-deposited up to the electron transport layer 7 is once taken out from the vacuum vapor deposition apparatus into the atmosphere, and used as a cathode vapor deposition mask as a 2 mm width in a shape orthogonal to the ITO stripe as the anode 2. A striped shadow mask is closely attached to the device and placed in another vacuum deposition apparatus, and lithium fluoride (LiF) is formed as an electron injection layer 8 with a film thickness of 0. Aluminum was laminated to a thickness of 80.0 nm as the cathode 9 and 5 nm, respectively.

<Sealing>
Subsequently, in order to prevent the element from being deteriorated by moisture in the atmosphere during storage, a sealing process was performed by the method described below.
In a nitrogen glove box connected to a vacuum deposition apparatus, a photocurable resin was applied to the outer periphery of a 23 mm × 23 mm size glass plate with a width of about 1 mm, and a moisture getter sheet was installed in the center. On this, the board | substrate which complete | finished cathode formation was bonded together so that the vapor-deposited surface might oppose a desiccant sheet. Then, only the area | region where the photocurable resin was apply | coated was irradiated with ultraviolet light, and resin was hardened. Thereby, the organic electroluminescent element which has a light emission area part of 2 mm x 2 mm size was obtained.

[Comparative Example 1]
A device was prepared in the same manner as in Example 1 except that the light emitting layer was changed to one consisting of only two vapor-deposited light emitting layers as described below.
Due to the limitations of the vapor deposition apparatus, only ternary vapor deposition can be performed. Therefore, as the material of the light emitting layer, the compounds (GH-2), (GD-1) and (RD-1) described above are 100: 10: 0.7. Vapor deposition was performed at a weight ratio to form a film, and a vapor-deposited light-emitting layer having a thickness of 40 nm was formed on the hole transport layer 4.
Next, the above-mentioned compounds (BH-1) and (BD-1) were deposited by vacuum deposition at a weight ratio of 100: 5 to form a deposited light emitting layer having a thickness of 20 nm.

[Example 2]
In Example 1, the following compounds (GH-3) and (GH-4) and the above-mentioned compounds (GD-1) and (RD-1) were used as materials used for forming the coated light emitting layer. Implementation was performed except that the mixing ratio was changed to a ratio (weight ratio) of (GH-3) :( GH-4) :( GD-1) :( RD-1) = 25: 75: 7: 1.5. An organic electroluminescent element was prepared in the same manner as in Example 1.

[Example 3]
In Example 1, as a material used for forming the coating light emitting layer, the following compound (GH-5), the above compounds (GH-4) and (GD-1), and the following compound (RD-2) ), And the mixing ratio was (GH-5) :( GH-4) :( GD-1) :( RD-2) = 25: 75: 10: 1 (weight ratio). A composition in which 0.5% by weight was dissolved in cyclohexylbenzene was prepared, and this composition was spin-coated on the hole transport layer in a nitrogen atmosphere to form a coating light emitting layer having a thickness of 30 nm. An organic electroluminescent element was produced in the same manner as in Example 1 except that.

  The compound (RD-2) is a red phosphorescent material having a maximum emission wavelength at 596 nm.

[Example 4]
In Example 2, the organic electroluminescent element was produced similarly to Example 2 except having changed the compound (BD-1) of the luminescent material used with a vapor deposition light emitting layer into the compound (BD-2) shown below.

  The compound (BD-2) is a blue fluorescent light-emitting material having a maximum emission wavelength at 456 nm.

[Example 5]
In Example 1, the materials used in the coated light emitting layer are the following compounds (GH-6), (GH-7), (GD-2) and (RD-3), and the mixing ratio is (GH- 6) :( GH-7) :( GD-2) :( RD-3) = 25: 75: 10: 0.7 The ratio (weight ratio) was changed to form a coated light emitting layer in the same manner, and then In addition, except that a vapor-deposited light emitting layer was formed in the same manner as in Example 1, and further a hole relaxation layer having a film thickness of 5 nm was formed thereon by vacuum vapor deposition using the compound (GH-1). An organic electroluminescent element was prepared in the same manner as in Example 1.

  Note that the compound (GD-2) is a green phosphorescent material having a maximum emission wavelength at 518 nm, and the compound (RD-3) is a red phosphorescence material having a maximum emission wavelength at 629 nm.

[Example 6]
In Example 1, the polymer compound (HT-1) used in the hole transport layer was changed to the polymer compound (HT-2) (weight average molecular weight: 68000) having a repeating structure shown below. The compound (BH-1) used was changed to the compound (BH-2) shown below to form a vapor-deposited luminescent layer in the same manner, and then the compound (GH-1) was used thereon by vacuum vapor deposition. An organic electroluminescent element was prepared in the same manner as in Example 1 except that a 10 nm thick hole relaxation layer was formed.

[Example 7]
In Example 2, an organic electroluminescent element was formed in the same manner as in Example 2 except that an intermediate layer having a thickness of 5 nm was further formed on the coated light emitting layer by vacuum deposition using the compound (BH-2). It was created.

[Comparative Example 2]
In Example 1, the materials used for the vapor-deposited light-emitting layer were changed to the following compounds (BH-3) and (BD-3), and (BH-3) :( BD-3) = 100 by vacuum vapor deposition. An organic electroluminescent element was prepared in the same manner as in Example 1 except that vacuum deposition was performed at a weight ratio of 5: 5.

Note that the compound (BD-3) is a blue phosphorescent material having a maximum emission wavelength at 459 nm.
[Comparative Example 3]
In Comparative Example 2, a device was prepared in the same manner as in Comparative Example 1 except that the hole transport layer was not formed and the coating light emitting layer was laminated directly on the hole injection layer.

[Comparative Example 4]
In Example 1, the materials used for forming the coated light emitting layer are polyvinyl carbazole (PVK, weight average molecular weight: 440000) and the compounds (GD-1) and (RD-1), and PVK: (GD-1). ) :( RD-1) = 100: 10: 0.7 The mixture obtained by mixing (weight ratio) in a 1: 1 (volume ratio) mixed solvent of toluene: anisole has a concentration of 0.35. An organic electroluminescent element was prepared in the same manner as in Example 1 except that the composition obtained by dissolving at a weight percent was used. This PVK is a polymer charge transporting material.

[Example 8]
In Example 1, the compounds (GH-2), (GD-1) and (RD-1) were used as materials used for forming the coated light emitting layer, and (GH-2) :( GD-1) : (RD-1) = 100: 10: 0.7 (weight ratio), and a composition in which 3.3% by weight of this mixture was dissolved in cyclohexylbenzene was prepared. Then, an organic electroluminescent element was formed in the same manner as in Example 1 except that a film was formed by spin coating on the hole transport layer to form a coating light emitting layer having a thickness of 40 nm, and the film thickness of the deposited light emitting layer was 20 nm. It was created.

[Evaluation of device]
The emission spectra of the devices obtained in Examples 1 to 8 and Comparative Examples 1 to 4 were measured using a spectroscope USB4000 (manufactured by Ocean Optics), and the maximum emission wavelength was examined. In addition, CIE chromaticity when 8 V was applied as a driving voltage was measured. The results are shown in Tables 2 and 3.
Further, a current having a current density of 10 mA / cm ² was passed through each of the elements obtained in Examples 1 to 8 and Comparative Examples 1 to 4, and the driving voltage and power luminous efficiency at that time were measured. Further, a current having a current density of 250 mA / cm ² was passed, and the relative luminance after energization for 32 seconds with respect to the initial luminance was measured to evaluate durability. The results are shown in Tables 2 and 3.

  From the above results, it can be seen that the organic electroluminescent element of the present invention emits white light with high efficiency at a low voltage and has high durability.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Hole blocking layer 7 Electron transport layer 8 Electron injection layer 9 Cathode 10 Organic electroluminescent device

Claims (10)

It is seen containing an anode and a cathode, and a light emitting layer formed between the anode and the cathode, between the anode and the light emitting layer comprises a hole transport layer composed of a hole transporting material In an organic electroluminescent element,
The light emitting layer is composed of two or more layers each containing different light emitting materials,
The light emitting layer includes, in order from the anode side, a layer formed by a wet film forming method and a layer formed by a vacuum evaporation method,
The layer formed by the wet film-forming method is a layer containing a phosphorescent material that is a low molecular compound and a charge transport material that is a low molecular compound ,
The layer formed by the vacuum deposition method is a layer containing a fluorescent light emitting material that is a low molecular compound and a charge transport material that is a low molecular compound ,
The fluorescent light-emitting material is represented by the following formula (B):

(In the formula, Ar ²⁵ is a substituted or unsubstituted naphthyl group, anthranyl group, phenanthryl group, pyrenyl group, chrysenyl group, coronyl group, biphenyl group, terphenyl group, diphenylanthranyl group, carbazolyl group, benzoquinolyl group, fluoran group. A tenenyl group, an acenaphthofluoranthenyl group or a stilbene group, and Ar ²⁶ and Ar ²⁷ are each independently a substituted or unsubstituted phenyl group, naphthyl group, anthranyl group, phenanthryl group, pyrenyl group, chrysenyl group, coronyl group Group, biphenyl group, terphenyl group, pyrrolyl group, furanyl group, thiophenyl group, benzothiophenyl group, oxadiazolyl group, diphenylanthranyl group, indolyl group, carbazolyl group, pyridyl group, benzoquinolyl group, fluoranthenyl group, acetonyl group A shift fluoride benzofluoranthenyl group or a stilbene group.
Note that when Ar ²⁵ , Ar ^26, and Ar ²⁷ have a substituent, the substituent includes an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 5 to 40 nuclear atoms, a nucleus An amino group substituted with an aryl group having 5 to 40 atoms, an ester group having an aryl group having 5 to 40 nucleus atoms, an ester group having an alkyl group having 1 to 6 carbon atoms, a cyano group, a nitro group, a halogen atom Is at least one selected from the group of q is an integer of 1-4. )
The phosphorescent material is a compound represented by the following formula (III):
ML _(q−j) L ′ _j (III)
(In the formula (III), M represents a metal, q represents a valence of the metal, and L and / or L
'Represents a 2-arylpyridine ligand. j represents a number of 0, 1 or 2. )
The hole transporting material is a polyarylene derivative having poly arylamine derivative and / or a bridging group having a crosslinking group, organic electromechanical field light-emitting element. The organic electroluminescent device according to claim 1, wherein the phosphorescent material is selected from compounds represented by the following formulas (IIIa), (IIIb), and (IIIc).

(In formula (IIIa), M ⁴ Represents ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum or gold, w represents the valence of the metal, and ring A1 represents an optionally substituted phenyl group, biphenyl. Represents a group, naphthyl group, anthryl group, thienyl group, furyl group, benzothienyl group, benzofuryl group, pyridyl group, quinolyl group, isoquinolyl group or carbazolyl group, and ring A2 may have an optionally substituted pyridyl group Represents a pyrimidyl group, a pyrazyl group, a triazyl group, a benzothiazole group, a benzoxazole group, a benzimidazole group, a quinolyl group, an isoquinolyl group, a quinoxalyl group, or a phenanthridyl group.
  The substituents that ring A1 and ring A2 may have include a halogen atom, an alkyl group, an alkenyl group, an alkoxycarbonyl group, an alkoxy group, an aryloxy group, a dialkylamino group, a diarylamino group, a carbazolyl group, an acyl group, It is at least one selected from a haloalkyl group and a cyano group, and the substituents may be linked to each other to form a ring. )

(In formula (IIIb), M ⁵ Represents ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum or gold, w represents the valence of the metal, and ring A1 represents an optionally substituted phenyl group, biphenyl. Represents a group, naphthyl group, anthryl group, thienyl group, furyl group, benzothienyl group, benzofuryl group, pyridyl group, quinolyl group, isoquinolyl group or carbazolyl group, and ring A2 may have an optionally substituted pyridyl group Represents a pyrimidyl group, a pyrazyl group, a triazyl group, a benzothiazole group, a benzoxazole group, a benzimidazole group, a quinolyl group, an isoquinolyl group, a quinoxalyl group, or a phenanthridyl group.
  The substituents that ring A1 and ring A2 may have include a halogen atom, an alkyl group, an alkenyl group, an alkoxycarbonyl group, an alkoxy group, an aryloxy group, a dialkylamino group, a diarylamino group, a carbazolyl group, an acyl group, It is at least one selected from a haloalkyl group and a cyano group, and the substituents may be linked to each other to form a ring. )

(In formula (IIIc), M ⁶ Represents ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum or gold, w represents the valence of the metal, j is 0, 1 or
Or ring A1 and ring A1 ′ each independently represent an optionally substituted phenyl group, biphenyl group, naphthyl group, anthryl group, thienyl group, furyl group, benzothienyl group, benzofuryl group. Group, pyridyl group, quinolyl group, isoquinolyl group or carbazolyl group, and ring A2 and ring A2 ′ are each independently an optionally substituted pyridyl group, pyrimidyl group, pyrazyl group, triazyl group, benzoyl group It represents a thiazole group, a benzoxazole group, a benzimidazole group, a quinolyl group, an isoquinolyl group, a quinoxalyl group, or a phenanthridyl group.
  The substituent which ring A1, ring A1 ', ring A2 and ring A2' may have is a halogen atom, an alkyl group, an alkenyl group, an alkoxycarbonyl group, an alkoxy group, an aryloxy group, a dialkylamino group, a diarylamino And at least one selected from a group, a carbazolyl group, an acyl group, a haloalkyl group, and a cyano group, and the substituents may be linked to each other to form a ring. ) The organic electroluminescent element of Claim 1 or 2 whose polyarylamine derivative is a polymer containing the repeating unit represented by following formula (II).

(In the formula (II), Ar ^a And Ar ^b Each independently represents a group derived from a ring selected from the group consisting of a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a triphenylene ring, a pyrene ring, a thiophene ring, a pyridine ring, and a fluorene ring, or two or more benzene rings. A group formed by linking is represented. These rings are alkyl groups, alkenyl groups, alkynyl groups, alkoxy groups, aryloxy groups, alkoxycarbonyl groups, dialkylamino groups, diarylamino groups, acyl groups, halogen atoms, haloalkyl groups, alkylthio groups, arylthio groups, silyl groups. Group, siloxy group, cyano group, aromatic hydrocarbon ring group or aromatic heterocyclic group may be substituted. ) In the formula (II), Ar ^a And Ar ^b The organic electroluminescent element according to claim 3, wherein is a group derived from a benzene ring or a group derived from a fluorene ring.   The organic electroluminescent element of Claim 1 whose polyarylene derivative is a polymer which has a repeating unit which consists of following formula (V-1) and / or following formula (V-2).

(In formula (V-1), R ^a , R ^b , R ^c And R ^d Each independently represents an alkyl group, an alkoxy group, a phenylalkyl group, a phenylalkoxy group, a phenyl group, a phenoxy group, an alkylphenyl group, an alkoxyphenyl group, an alkylcarbonyl group, an alkoxycarbonyl group, or a carboxy group. t and s each independently represent an integer of 0 to 3. When t or s is 2 or more, a plurality of Rs contained in one molecule ^a Or R ^b May be the same or different, and adjacent R ^a Or R ^b A ring may be formed with each other. )

(In formula (V-2), R ^e And R ^f Are each independently R in the above formula (V-1). ^a , R ^b , R ^c Or R ^d It is synonymous with. r and u each independently represents an integer of 0 to 3. When r or u is 2 or more, a plurality of Rs contained in one molecule ^e And R ^f May be the same or different, and adjacent R ^e Or R ^f A ring may be formed with each other. X represents —O—, —BR—, —NR—, —SiR. ₂ -, -PR-, -SR-, -CR ₂ -Or a group formed by bonding them. R represents a hydrogen atom or an arbitrary organic group. An organic group is a group containing at least one carbon atom. )   Furthermore, the organic electroluminescent element of Claim 5 which has a repeating unit represented by a following formula (V-3).

(In the formula (V-3), Ar ^c ~ Ar ^j Are each independently a group derived from a ring selected from the group consisting of a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a triphenylene ring, a pyrene ring, a thiophene ring, a pyridine ring and a fluorene ring, or two or more benzene rings linked together. Represents a group formed by These rings are alkyl groups, alkenyl groups, alkynyl groups, alkoxy groups, aryloxy groups, alkoxycarbonyl groups, dialkylamino groups, diarylamino groups, acyl groups, halogen atoms, haloalkyl groups, alkylthio groups, arylthio groups, silyl groups. Group, siloxy group, cyano group, aromatic hydrocarbon ring group or aromatic heterocyclic group may be substituted. v and w each independently represent 0 or 1. ) The layer formed by the wet film formation method included in the light emitting layer is a layer having a maximum light emission wavelength in at least two of a 440 to 500 nm region, a 510 to 550 nm region, and a 580 to 630 nm region. The organic electroluminescent element as described in any one of Claims 1-6 . The layer formed by the wet film forming method included in the light emitting layer is a layer having a maximum light emission wavelength in a 510 to 550 nm region and a 580 to 630 nm region. Organic electroluminescent element. Organic EL illumination containing the organic electroluminescent element in any one of Claims 1-8 . The organic electroluminescence display containing the organic electroluminescent element as described in any one of Claims 1-8 .

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