JP2002299061A - Organic electroluminescence element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electroluminescence element that has a simple multilayered lamination structure. SOLUTION: An organic substance constituting a luminescent layer 40, is soluble in a solvent having a solubility parameter, which lies outside of the solubility range of an organic substance constituting a first organic layer 20 formed in lamination on an anodic layer 10 side of the luminescent layer 40, and an organic substance, constituting a second organic layer 60 formed in lamination on a cathode layer 70 side of the luminescent layer 40, is made soluble in a solvent with the solubility parameter outside a solubility range of the organic substance constituting the luminescent layer 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescence device capable of emitting light with high luminance.

[0002]

2. Description of the Related Art Conventionally, there is known an organic electroluminescent device formed of a multilayer laminated structure having a light emitting layer containing a substance emitting phosphorescence and having improved luminous efficiency, from US Pat. No. 6,097,147.

In this method, a so-called dry method is employed, in which a luminescent substance is deposited at the time of laminating a multi-layer thin film, so that the manufacturing process becomes complicated.
Poor production efficiency.

[0004]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide an organic electroluminescence device having a simple multilayered structure.

[0005]

In order to solve the above-mentioned problems, the present invention provides an anode layer and a cathode layer, both a light-emitting layer having a host agent and a dopant emitting phosphorescence, First and second layers laminated between the layers via the light emitting layer
An organic electroluminescence device comprising both organic layers, wherein one of the electrode layers is formed on a substrate,
The organic substance constituting the light emitting layer is soluble in a solvent having a solubility parameter outside the solubility range with respect to the organic substance constituting the first organic layer formed by laminating the light emitting layer on the substrate side. An organic material constituting a second organic layer formed by laminating the light emitting layer on the side opposite to the substrate,
It was made soluble in a solvent having a solubility parameter outside the solubility range for the organic substance constituting the light emitting layer.

Here, the solubility parameter SP of the liquid having the molar evaporation heat ΔH and the molar volume V at the absolute temperature T is defined as SP = {(ΔH-RT) / V} ^1/2 . Here, in the above formula, SP is a solubility parameter (unit: (cal / cm ³ ) ^1/2 ), ΔH is molar heat of vaporization (unit: cal / mol), and R is a gas constant (unit: cal / mol / mol). (Mol · K)), T is the absolute temperature (unit: K), and V is the molar volume (unit: cm ³⁾
/ Mol).

In the present invention, the organic substance constituting the light emitting layer is
The organic material constituting the first organic layer is dissolved in a solvent having a solubility parameter outside the solubility range, and the organic material constituting the second organic layer is dissolved in the organic material constituting the light emitting layer. Dissolved in a solvent with parameters,
An organic electroluminescence element is formed as a multilayer laminated structure. At this time, since the organic substance constituting the first organic layer has a very low solubility in the solvent used for dissolving the organic substance constituting the light emitting layer, the first organic layer and the light emitting layer are mutually separated. When stacked adjacently, a thin film layer can be formed without dissolving and mixing the organic substances constituting each thin film layer.
Further, since the organic substance constituting the light emitting layer has a very low solubility in the solvent used for dissolving the organic substance constituting the second organic layer, the light emitting layer and the second organic layer are adjacent to each other. When the layers are stacked, the thin film layers can be formed without dissolving and mixing the organic substances constituting each thin film layer. That is, the light emitting layer or the first
In addition, a simple thin film can be formed by a wet method using a solvent that dissolves an organic substance constituting each thin film layer of both the second organic layer and the second organic layer.

[0008] In this case, it is desirable that the organic substance constituting the first organic layer is composed of at least one of a hole injecting substance, a hole transporting substance, and an electron blocking substance.

Further, in this case, it is preferable that the organic substance constituting the second organic layer is composed of at least one of an electron injecting substance, an electron transporting substance, and a hole blocking substance.

In this case, the organic material constituting the first organic layer is 8.9 (cal / c) at room temperature.
m ³ ) is insoluble in a solvent having a solubility parameter of less than ^1/2 , and the organic substance constituting the light emitting layer is at least 8.4 (cal / cm ³ ) ^{1/2 and} 8.9 (cal / cm) at room temperature.
³⁾ 8.4 at room temperature is soluble in a solvent having a solubility parameter of less than ^1/2 (cal / cm ³⁾ is insoluble in a solvent having a solubility parameter of less than ^1/2, the second organic layer Is 7.0 at room temperature.
(Cal / cm ³ ) ^1/2 or more and 8.4 (cal / cm ³ ) ^1/2
It is desirable to be configured to be soluble in solvents having a solubility parameter of less than.

In this case, the organic material constituting the first organic layer is 8.9 (cal / cm ³ ) at room temperature.
Insoluble in a solvent having a solubility parameter of less than ^1/2, the organic material constituting the light emitting layer is at room temperature at 7.
0 (cal / cm ³ ) ^1/2 or more and 8.9 (cal / cm ³ )
The second organic layer is soluble in a solvent having a solubility parameter of less than ^1/2 and insoluble in a solvent having a solubility parameter of 11.5 (cal / cm ³ ) ^1/2 or more at room temperature. Organic matter at room temperature
(Cal / cm ³ ) ^1/2 or more and 13.0 (cal / cm ³ )
It is also possible to configure so as to be soluble in a solvent having a solubility parameter of ^1/2 or less.

Further, the organic substance constituting the first organic layer is insoluble in a solvent having a solubility parameter of more than 10.0 (cal / cm ³ ) ^1/2 at room temperature, and the organic substance constituting the light emitting layer Is 10.0 (c) at room temperature.
al / cm ³ ) ^1/2 and 11.5 (cal / c
m ³⁾ 11.5 at room temperature with a soluble in a solvent having a solubility parameter of less than ^1/2 (cal / cm ^{3) 1/2}
The organic substance that is insoluble in the solvent having the above-mentioned solubility parameter and that constitutes the second organic layer is 1 at room temperature.
1.5 (cal / cm ³ ) ^1/2 or more 13.0 (cal / c)
m ³ ) It is also possible to make the composition soluble in a solvent having a solubility parameter of ^1/2 or less.

In these cases, the dopant is preferably a compound represented by the chemical formula [1] or [2].

[0014]

FIG. 1 (a) shows a basic structure of an organic electroluminescent device having a multilayer structure for the purpose of improving luminous efficiency. The element structure of the organic electroluminescent element is such that a hole transport layer 20, an electron block layer 30, a light emitting layer 40 are provided between the two electrode layers of the anode layer 10 and the cathode layer 70, on the anode layer 10 formed on the substrate. The light emitting layer 40 has a multilayer stacked structure in which thin film layers of a hole blocking layer 50 and an electron transporting layer 60 are sequentially stacked. The light emitting layer 40 includes a light emitting layer dopant 41 and a light emitting layer host agent 42.

In each of the element structures shown in FIGS. 1A to 1D, the anode layer 10 is made of a transparent conductive material formed on a transparent insulating support such as a glass substrate. Examples of the material include conductive oxides such as tin oxide, indium oxide, and indium tin oxide (ITO); metals such as gold, silver, and chromium; inorganic conductive substances such as copper iodide and copper sulfide; polythiophene; and polypyrrole. And a conductive polymer such as polyaniline.

When the cathode layer 70 is formed of a transparent material, the anode layer 10 may be formed of an opaque material.

In each of the element structures shown in FIGS. 1A to 1D, the cathode layer 70 includes lithium, sodium, potassium, rubidium, cesium, magnesium,
A simple substance or an alloy of calcium, strontium, barium, boron, aluminum, copper, silver, gold and the like can be used. Further, these can be used in a laminated state.
It can also be formed by a wet method using tetrahydroaluminate. In this case, examples of the tetrahydroaluminate used for the cathode layer 70 include lithium aluminum hydride, aluminum potassium hydride, aluminum magnesium hydride, and calcium aluminum hydride. Among them, lithium aluminum hydride is particularly excellent in the electron injection property to the electron transport layer.

The hole transporting layer 20 is a layer for transporting holes injected from the anode, and is an organic layer containing a hole transporting organic substance. As an example of the hole transport layer organic material,

[0019]

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Poly (N-vinylcarbazole) (hereinafter also referred to as PVK) shown in Chemical Formula 3;

[0021]

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A poly (para-phenylenevinylene) represented by the following formula:

[0023]

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(In the chemical formula [Chemical Formula 5], R is a substituent composed of C, H, O, and N) It is preferable to use a polymer such as a polycarbazole compound having [Chemical Formula 5] as a repeating unit. Or,

[0025]

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N, N'-diphenyl- represented by the formula
N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine (hereinafter also referred to as TPD),

[0027]

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Carbazole biphenyl (hereinafter, also referred to as CBP) shown in [Formula 7],

[0029]

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The N, N'-diphenyl- represented by the formula
N, N'-bis (1-naphthyl) -1,1'-biphenyl-4,4'-diamine (hereinafter also referred to as NPD)

[0031]

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4,4′-bis (10-phenothiazinyl) biphenyl represented by the following formula:

[0033]

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Copper phthalocyanine shown in Chemical Formula 10 and the like can be mentioned.

Further, the electron blocking layer 30 is formed of the cathode layer 70.
The electrons injected into the light emitting layer 40 from the anode layer 10
It is a layer for blocking electrons in order to prevent the electrons from passing through, and is made of an electron blocking substance. Examples of the electron blocking substance include [Chemical Formula 3], [Chemical Formula 4],
Compounds represented by the following formulas 6 to 9;

[0036]

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2,4,6-triphenyl-1,3,5-triazole represented by the following formula:

[0038]

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Fluorene shown in Chemical formula 12 can be used.

The light emitting layer 40 has a dopant 41 and a host agent 42, and a binder polymer can be added to uniformly disperse the dopant 41 and the host agent 42. The host agent 42 is formed by the holes and electrons injected from the anode layer 10 and the cathode layer 70, respectively.
A substance that is activated when recombining at 0 and acts as an exciton,

[0041]

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The 1,3,5-tri (5-
(4-tert-butylphenyl) -1,3,4-oxadiazole)) phenyl (hereinafter also referred to as OXD-1),

[0043]

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(Wherein R is C, H, O, N
Represents a substituent composed of And polyfluorene compounds having [Formula 14] as a repeating unit.

On the other hand, the dopant 41 of the light emitting layer 40 is a substance which emits phosphorescence by the excitation energy of the host agent which is an exciton.

[0046]

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A tri (2phenylpyridine) iridium complex (hereinafter also referred to as Ir (ppy) ₃ ) shown in [Formula 15],

[0048]

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[0049]

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[0050]

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[0051]

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[0052]

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[0053]

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(In the chemical formula [Chemical Formula 21], acac is

[0055]

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The functional group represented by Chemical Formula 22 is shown. following
The same applies to the chemical formulas shown in [Formula 23] to [Formula 27]. )

[0057]

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[0058]

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[0059]

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[0060]

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[0061]

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An iridium complex compound represented by any one of the following chemical formulas 16 to 21 and 22 to 27:

[0063]

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2, 3, 7, 8, 12,
13, 17, 18-octaethyl-21H, 23H-platinum (II) porphine (hereinafter also referred to as PtOEP) and the like.

Examples of the binder polymer that can be added to the light emitting layer 40 include cis and tran of polystyrene, polyvinyl biphenyl, polyvinyl phenanthrene, polyvinyl anthracene, polyvinyl perylene, poly (ethylene-co-vinyl acetate), and polybutadiene.
s, poly (2-vinylnaphthalene), polyvinylpyrrolidone, polystyrene, poly (methyl methacrylate),
Poly (vinyl acetate), poly (2-vinylpyridine-co-styrene), polyacenaphthylene, poly (acrylonitrile-co-butadiene), poly (benzyl methacrylate), poly (vinyltoluene), poly (styrene-co-styrene) Acrylonitrile), poly (4-vinylbiphenyl), polyethylene glycol and the like.

The hole blocking layer 50 is formed on the anode layer 10
The holes injected into the light emitting layer 40 from the cathode layer 70
This is a layer for blocking holes in order to prevent the holes from passing through, and is made of a hole-blocking substance. As the hole blocking substance, for example,

[0067]

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2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,
3,4-oxadiazole, (hereinafter also referred to as PBD),

[0069]

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The bathocuproin (hereinafter referred to as B)
Also called CP. ), OXD-1 shown in [formula 13], [formula 2]
PBD shown in 9],

[0071]

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Tris (8-hydroxyquinolinato) aluminum (hereinafter also referred to as Alq3) shown in [Chemical Formula 31],

[0073]

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3- (4-biphenylyl) -5- (4-tert-butylphenyl) -4-phenyl-1,2,4-triazole (hereinafter also referred to as TAZ) shown in [Formula 32].

[0075]

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The 4,4′-bis (1,1) shown in [Formula 33]
-Diphenylethenyl) biphenyl (hereinafter referred to as DPVBi
Also called. ),

[0077]

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The 2,5-bis (1-naphthyl) -1.3.4-oxadiazole represented by the formula
Also called. )

[0079]

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4,4′-bis (1,1-bis (4-methylphenyl) ethenyl) biphenyl (hereinafter also referred to as DTVBi) shown in [Formula 35].

[0081]

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The 2,5-bis (4-
Biphenylyl) -1,3,4-oxadiazole (hereinafter also referred to as BBD),

[0083]

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[0084]

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An oxadiazole polymer compound as shown in [Formula 37] or [Formula 38],

[0086]

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[0087]

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Examples of the compound include triazole-based polymer compounds represented by the following [Formula 39] and [Formula 40].

The electron transporting layer 60 is a layer for transporting electrons injected from the cathode layer 70 and contains an electron transporting agent. The electron transport agent is composed of an electron transport polymer,
Further, a configuration containing an electron transporting small molecule is possible.

Here, as an example of the electron transporting small molecule,
PBD shown in [Chemical formula 29], Alq3 shown in [Chemical formula 31],
TAZ shown in [Formula 32], DPVB shown in [Formula 33]
i, BND shown in [Formula 34], DTV shown in [Formula 35]
Bi, BBD shown in [Formula 36], and the like.

Examples of the electron-transporting polymer include oxadiazole-based polymer compounds represented by [Chemical Formula 37] and [Chemical Formula 38], and [Chemical Formula 39] and [Chemical Formula 40]. Triazole polymer compound,

[0092]

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(In the chemical formula [Formula 41], R is C, H, O, N
Represents a substituent composed of A) a polyfluorene compound having [Formula 41] as a repeating unit.

In order to further improve the luminous efficiency and simplify the structure, the basic structure of the organic electroluminescence device shown in FIG.
(E) are possible.

The device structure of the organic electroluminescence device shown in FIG. 1B shows the first embodiment of the organic electroluminescence device of the present invention. FIG.
Although the electron block layer 30 and the hole block layer 50 in FIG. 1A are omitted, in FIG.
The emission efficiency can be maintained by giving an electron blocking effect to 0 and a hole blocking effect to the electron transport layer 60.

The element structure of the organic electroluminescence element shown in FIG. 1C is the same as the element structure shown in FIG.
Are omitted, and an electron injection layer 61 made of an electron injecting substance is added between the cathode layer 70 and the electron transport layer 60.

As the electron injecting substance, for example,
0] metal copper phthalocyanine such as copper phthalocyanine,

[0098]

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Poly (3,4) ethylenedioxythiophene / polystyrenesulfonate (hereinafter also referred to as PEDT / PSS) represented by the following formula:

The element structure of the organic electroluminescence element shown in FIG. 1D is different from the element structure shown in FIG. 1A in that the electron block layer 30 and the hole block layer 50 are omitted, and the anode layer 10 A hole injection layer 21 composed of a hole injection substance is added between the hole injection layer 21 and the hole transport layer 20.

As the hole injecting substance, for example, lithium fluoride, lithium oxide,

[0102]

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[0103] Lithium 8-hydroxyquinolinate (hereinafter also referred to as Liq) represented by the following formula (43) is exemplified.

The element structure of the organic electroluminescence element shown in FIG. 1E is obtained by omitting the electron block layer 30 and the electron transport layer 60 from the element structure shown in FIG. 1A.

Next, a method for manufacturing an organic electroluminescent device will be described with reference to FIG. 1B as a first embodiment of the present invention.

First, an anode layer 10 is formed on a transparent insulating support serving as a substrate, for example, a glass substrate by an evaporation method or a sputtering method.

Next, a first solution is prepared by dissolving or dispersing a hole transporting polymer or a hole transporting low molecule in a solvent. Here, the binder polymer can be further dissolved or dispersed in the first solution. Then, the hole transport layer 20 is formed on the anode layer 10 by a wet method using the first solution.

Further, the dopant 4 constituting the light emitting layer 40
A second solution in which 1 and the host agent 42 are dissolved or dispersed in a solvent is prepared. Here, the binder polymer can be further dissolved or dispersed in the second solution. Then, the light emitting layer 40 is formed on the hole transport layer 20 by a wet method using the second solution.

Thereafter, a third solution is prepared by dissolving or dispersing the electron transporting polymer or the electron transporting low molecule in the solvent. Here, the binder polymer can be further dissolved or dispersed in the third solution. The electron transport layer 6 is formed on the light emitting layer 40 by a wet method using the third solution.
0 is formed.

The solubility parameter of the solvent used in the second solution is determined by the material (hole transporting polymer or hole transporting low molecular weight) contained in the hole transporting layer 20 at the deposition temperature of the light emitting layer 40. , Etc.) outside the solubility range. The light emitting layer 40 formed by a wet method using such a solvent.
Does not dissolve organic matter contained in the lower hole transport layer 20.

For example, when the organic substance contained in the hole transport layer 20 is a hole transporting polymer, ie, PVK shown in [Chemical Formula 3], the solubility parameter indicating the solubility range of this PVK is 8. 9 (cal / cm ³ ) ^1/2 or more 10.0 (c
al / cm ³ ) ^1/2 or less. Therefore, when the solvent used for the second solution is outside the range of the solubility parameter, the light emitting layer 40 can be formed without dissolving the PVK contained in the hole transport layer 20. Examples of such solvents include xylene (solubility parameter 8.8 (cal / cm ³ ) ^1/2 ), ethylbenzene (solubility parameter 8.7 (cal / cm ³ ) ^1/2 ), 2-
Nitropropane (solubility parameter 10.1 (cal
/ Cm ³ ) ^1/2 ), cyclohexane (having a solubility parameter of 8.2 (cal / cm ³ ) ^1/2 ), and the like.

The solubility parameter of the solvent used in the third solution depends on the substance (dopant 41, host agent 42, binder polymer, etc.) contained in the light emitting layer 40 at the film formation temperature of the electron transport layer 60. Has a value outside the solubility range. In the formation of the electron transport layer 60 by a wet method using such a solvent, an organic substance contained in the lower light emitting layer 40 is not dissolved.

For example, the dopant 4 contained in the light emitting layer 40
1 is OXD-1 shown in [Chemical Formula 12], and the host agent 42 is
An Ir (ppy) ₃ shown in Chemical Formula 15], when using poly (4-vinyl biphenyl) as the binder polymer, the solubility parameter indicating a soluble range of organic materials constituting the light-emitting layer, at room temperature for 8 0.7 (cal / cm ³ )
^{It is 1/2} or more and 11.1 (cal / cm ³ ) ^1/2 or less. Therefore, if a solvent outside the range of the solubility parameter is used as the solvent used for the third solution, the light emitting layer 40
The electron transport layer 60 can be formed without dissolving the organic substances contained in the organic compound. As an example of such a solvent, n-
Nonane (solubility parameter 7.64 (cal / cm ³ ))
^1/2 ), 1-decene (solubility parameter 7.85 (cal)
^{/ Cm 3) 1/2)} , methylcyclohexane (solubility parameter ^{8.13 (cal / cm 3) 1/2} ), cyclohexane (solubility parameter ^{8.20 (cal / cm 3) 1/2} ),
1-chloropropane (solubility parameter 8.30 (ca
1 / cm ³ ) ^1/2 ), acetonitrile (solubility parameter 11.8 (cal / cm ³ ) ^1/2 ), and the like.

At this time, the solvent used in the first to third solutions is evaporated by natural drying, so that the hole transport layer 20, the light emitting layer 40, and the electron transport layer 60 are formed. In this case, there is no need to perform treatments such as polymerization and curing by heating and irradiation of ultraviolet rays, and therefore, the manufacturing process is simple and the production efficiency can be improved.

The wet method used in the present invention includes, for example, ordinary coating methods such as a casting method, a blade coating method, a dip coating method, a spin coating method, a spray coating method, a roll coating method, and an ink jet coating method. .

Finally, a cathode is formed on the light emitting layer 40 by using a vapor deposition method or the like, so that the organic electroluminescence device of the present invention is obtained.

The solubility parameter SP is defined as SP = {(ΔH-RT) / V} ^1/2 at a molar evaporation heat ΔH and an absolute temperature T of a liquid having a molar volume V. Here, in the above formula, SP is a solubility parameter (unit: (cal / cm ³ ) ^1/2 ), ΔH is molar heat of vaporization (unit: cal / mol), and R is a gas constant (unit: cal / mol / mol). (Mol · K)), T is the absolute temperature (unit: K), and V is the molar volume (unit: cm ³⁾
/ Mol).

FIG. 1C shows a second embodiment of the organic electroluminescence device of the present invention. During the manufacturing process of the device structure shown in FIG. After the light emitting layer 40 and the electron transport layer 60 are sequentially formed, an electron injectable substance such as lithium fluoride is formed on the electron transport layer 60 by an evaporation method to form the electron injection layer 61, and then the electron injection layer 61 is formed. It is obtained through a manufacturing process for forming a cathode on the layer 61 in the same manner as in FIG. 1B.

FIG. 1D shows a third embodiment of the organic electroluminescence device of the present invention. During the manufacturing process of the device structure shown in FIG. Before the formation, a hole injecting substance such as copper phthalocyanine represented by the following formula [Chemical Formula 10] is formed on the anode layer 10 by a vapor deposition method to form the hole injecting layer 21. In the same manner as in FIG.
0, a light-emitting layer 40, an electron transport layer 60, and a cathode layer 70 in that order.

FIG. 1E shows a fourth embodiment of the organic electroluminescence device of the present invention. In the manufacturing process of the device structure shown in FIG. 1B, an electron transport layer 60 is formed. Instead, a hole blocking material such as PBD is formed on the light emitting layer 40 by a wet method to form the hole blocking layer 50, and then the cathode layer 70 is formed.

[0121]

EXAMPLE [Experiment 1] A test piece was prepared by laminating a thin film having a predetermined thickness on a substrate, and the dissolution range in a solvent having a predetermined solubility parameter was measured.

Materials 6 of thin film layers such as a hole transport layer, an electron block layer, a light emitting layer, a hole block layer, an electron transport layer, and an electron injection layer which constitute the organic electroluminescence element.
mg is dissolved in 1 ml of a soluble solvent to make a solution. Using this solution, the number of revolutions and the time were adjusted on a commercially available ITO substrate (manufactured by Asahi Glass Co., Ltd .: 20Ω / □) subjected to oxygen plasma treatment so that the film thickness became 50 nm by spin coating. A substrate with a thin film is prepared and used as a test piece.

[0123]

[Table 1]

Solvents having the solubility parameters shown in [Table 1] were prepared in ascending order of these solubility parameter values.
As shown in (a) and FIG. 2 (b), test pieces 3 were placed in beakers 2 filled with the solvents 1 for 10 times each.
Then, as shown in FIG. 2C, the test piece 3 is taken out, and it is visually confirmed whether or not the thin film is dissolved.

[0125] Of the solubility parameters of the solvent in which the thin film dissolves, the minimum value and the maximum value are defined as the dissolution range of the test piece.

Example 1 PVK6 having a polystyrene equivalent weight average molecular weight (hereinafter referred to as “molecular weight”) of 1,100,000 measured by gel permeation chromatography.
mg was dissolved in 1 ml of 1,2 dichloroethane to prepare solution 1.

2.5 mg of OXD-1 and Ir (pp
y) 0.17 mg as ₃ ) 2.5 mg of polyvinyl biphenyl having a molecular weight of 100,000 as a binder polymer in xylene (solubility parameter 8.8 (cal / c)
m ³ ) ^1/2 ) was dissolved in 1 ml to prepare solution 2.

2.5 mg as PBD and binder polymer
2.5mg of polystyrene (molecular weight 10,000)
With cyclohexane (solubility parameter 8.2 (cal /
cm ^Three)^1/2) Was dissolved in 1 ml of the solvent to prepare solution 3.
Was.

The solution 1 was placed on an oxygen plasma-treated ITO substrate (commercially available ITO, manufactured by Asahi Glass Co., Ltd .: 20Ω / □ or less).
Was spin coated at 1500 rpm for 1 second to form a 50 nm hole transport layer. The dissolution range of the hole transport layer according to [Experiment 1] is 8.9 to 10.0 (cal / c).
m ³ ) ^1/2 .

Further, the solution 2 was placed on the hole transport layer at a rotation speed of 1
2,000 rpm for 1 second by spin coating for 20
nm was obtained. The dissolution range of the light emitting layer according to [Experiment 1] was 8.7 to 11.1 (cal / cm ³ ) ^1/2 . Further, the solution 3 was spin-coated at 1,000 rpm for 1 second on the light emitting layer to obtain a 50 nm electron transport layer.

A cathode was formed by co-evaporating aluminum and lithium at a degree of vacuum of 10 ⁻³ Pa at a vapor deposition rate of 1 nm / sec so that the lithium content was 1%.

In the thus obtained device structure shown in FIG. 1B, 480 cd at 9 V and 1 mA / cm ² was obtained.
/ M ² of green light was obtained.

[Example 2] In the same manner as in [Example 1], except that the solvent of the solution 2 of [Example 1] was changed to the solvent shown in the following table, FIG.
The device structure shown in FIG.
Light emission with luminous efficiency as shown in Table 2 was obtained.

[0134]

[Table 2]

[Example 3] In the same manner as in [Example 1], except that the solvent of the solution 3 of [Example 1] was changed to the solvent shown in the following table, FIG.
The device structure shown in FIG.
Light emission with luminous efficiency as shown in Table 3 was obtained.

[0136]

[Table 3]

[Example 4] Ir (ppy) ₃ as a solute of solution 2 of [Example 1] was prepared in the same manner as in [Example 1] except that a dopant shown in [Table 4] shown below was used. When the device structure shown in FIG. 1 (b) was prepared, light emission having the luminous efficiency shown in [Table 4] below was obtained.

[0138]

[Table 4]

[Example 5] In [Example 1], lithium fluoride was vacuum-deposited as an electron injection layer between the electron transport layer and the cathode by a vacuum degree of 10 ^-3 Pa at a rate of 0.1 nm / sec.
1c was formed under the same conditions as in [Example 1] except that the film was formed to 5 nm and the cathode was changed to aluminum.

At this time, 8.7 V, 1 mA / cm ² and 52
Green light emission of 0 cd / m ² was obtained.

[Embodiment 6] In Embodiment 1, the IT
As a hole injection layer between the O anode and the hole transport layer, copper phthalocyanine is vacuum-deposited at a degree of vacuum of 10 ^-3 Pa at a rate of ^0.1-3 Pa.
Example 1 except that a 5 nm film was formed at 1 nm / sec.
An element structure shown in FIG. 1D was prepared under the same conditions as described above.

At this time, 8.4 V, 1 mA / cm ² and 52
Green light emission of 0 cd / m ² was obtained.

Example 7 In the molecular structure of a polyfluorene compound having a repeating unit represented by Chemical Formula 41, R is a linear alkyl group (—C _n H _{2n + 1} ) and the molecular weight is 1,
When the dissolution range was measured in accordance with [Experiment 1] when the concentration was set at 1,000,000, the results shown in [Table 5] shown below were obtained.

[0144]

[Table 5]

From this, it is understood that the dissolving range can be varied by the length of the straight chain in R.

Thus, the PVK molecular weight is 1,100,000.
Is dissolved in 1 ml of 1,2 dichloroethane,
Solution 1 was prepared.

2.5 mg of OXD-1 and Ir (pp
y) 0.17 mg as ₃ and 2.5 mg of polyvinyl biphenyl (molecular weight 115,000) as a binder polymer
Was dissolved in 1 ml of xylene to prepare a solution 2.

In Chemical Formula 41, a molecular weight of 1 having a repeating unit in which R is a linear alkyl group (—C _n H _{2n + 1} )
5 mg of a polymer of 1,000,000 in 1 ml of cyclohexane
To prepare a solution 3.

Solution 1 was placed on an oxygen-treated plasma ITO substrate (commercially available ITO, manufactured by Asahi Glass Co., Ltd .: 20 Ω / □ or less).
Was spin-coated at 1,000 rpm for 1 second to obtain a 50 nm hole transport layer.

The solution 2 was put on the hole transport layer at a rotation speed of 1000 r.
A 20 nm light emitting layer was obtained by spin coating at pm for 1 second. The dissolution range of the light emitting layer according to [Experiment 1] was 8.6 to 11.1 (cal / cm ³ ) ^1/2 .

Further, the solution 3 was put on the light emitting layer at a rotation speed of 100.
50 nm by spin coating at 0 rpm for 1 second
Was obtained.

Finally, aluminum and lithium were co-deposited with a vacuum deposition apparatus at a deposition rate of 1 nm / sec so that the lithium content was 1% at a degree of vacuum of 10 ⁻³ Pa to form a cathode.

In the thus obtained device structure shown in FIG. 1B, light emission having luminous efficiency as shown in Table 6 below was obtained.

[0154]

[Table 6]

[Example 8] In Example 7, the solution was used.
Having a molecular weight of 50,000 as the second binder polymer
PVK, solution using trichlorethylene as solvent
Example 3 except that ethylbenzene was used as the solvent in Example 3.
7] was fabricated under the same conditions as in [7].
Was. At this time, the dissolution range of the light emitting layer according to [Experiment 1] is 8.
9 to 10.6 (cal / cm ^Three)^1/2Met.

In the device structure thus obtained, light emission having the luminous efficiency shown in the following [Table 7] was obtained.

[0157]

[Table 7]

A comparison between [Table 6] and [Table 7] shows that, in [Table 7] in which ethylbenzene was used as the solvent of the solution 3, PVK (molecular weight: 50,000) in which the binder polymer of the light emitting layer was insoluble in ethylbenzene was used. 1mA
It is considered that the luminance at / cm ² decreased.

[Example 9] When R in the molecular structure represented by Chemical Formula 41 is -C ₁₀ H ₂₁ and the molecular weight of the polymer having the repeating unit of Chemical Formula 41 is varied, Experiment 1]
When the dissolution range was measured by the method described above, the results shown in the following [Table 8] were obtained.

[0160]

[Table 8]

From this, it is understood that the dissolution range can be changed by changing the molecular weight of the above polymer.

Thus, the element structure shown in FIG. 1B was prepared under the same conditions as in [Example 7].
The luminescence of the luminous efficiency shown in the following was obtained.

[0163]

[Table 9]

Example 10 R of the formula [Chem. 41] is a straight-chain-
And C ₁₀ H _21, as 10,000 molecular weight of the polymer having repeating units of the general formula 41] investigated the difference in performance due to the solvent. R an alkyl group of straight chain molecular structure represented by Formula 41] In Example 7 a _{(-C n H 2n + 1)} -
The device structure of FIG. 1B was prepared under the same conditions as in [Example 7] except that C ₁₀ H ₂₁ was used and the solvent was replaced.
The luminescence with the luminous efficiency shown in the following [Table 10] was obtained.

[0165]

[Table 10]

A comparison between [Table 6] and [Table 10] shows that even if the solvent is changed, if the solvent in the insoluble range of the lower light emitting layer is used, the variation in luminance at 1 mA / cm ² is 1
It turns out that it is within 0%.

Example 11 R in the molecular structure of a polycarbazole compound having a repeating unit represented by the following formula:
Is a linear alkyl group (—C _n H _{2n + 1} ) and the molecular weight is 1,000,000. When the dissolution range is measured according to [Experiment 1], the results are shown in Table 11 below. The results shown were obtained.

[0168]

[Table 11]

This shows that the dissolution range can be varied by the length of the straight chain in R.

Therefore, 6 mg of a polymer having a molecular weight of 100,000 and having a repeating unit in which R is a straight-chain alkyl group (—C _n H _{2n + 1} ) in Chemical Formula 5, was added to trichloromethane 1
The solution was dissolved in ml to prepare solution 1.

2.5 mg of OXD-1 and Ir (pp
y) 0.17 mg as ₃ 2.5 mg of polyvinyl biphenyl having a molecular weight of 100,000 as a binder polymer
Was dissolved in 1 ml of xylene to prepare a solution 2.

[0172] 2.5 mg of PBD and 2.5 mg of polystyrene (molecular weight 10,000) as a binder polymer were added to cyclohexane (solubility parameter 8.2 (cal / c).
m ³⁾ was dissolved in a solvent 1ml of ^1/2) to prepare a solution 3.

The solution 1 was placed on an oxygen-treated plasma ITO substrate (commercially available ITO, manufactured by Asahi Glass Co., Ltd .: 20Ω / □ or less).
Was spin coated at 1500 rpm for 1 second to form a 50 nm hole transport layer. Further, the solution 2 was spin-coated on the hole transport layer at a rotation speed of 1000 rpm for 1 second to obtain a 20 nm light-emitting layer.

Further, the solution 3 was put on the light emitting layer at a rotation speed of 100.
50 nm by spin coating at 0 rpm for 1 second
Was obtained.

Aluminum and lithium were co-deposited with a vacuum deposition apparatus at a degree of vacuum of 10 ⁻³ Pa at a deposition rate of 1 nm / sec so that the lithium content was 1% to form a cathode.

With the device structure shown in FIG. 1 (e), light emission with luminous efficiency as shown in the following [Table 12] was obtained.

[0177]

[Table 12]

Example 12 An element structure shown in FIG. 1E was prepared under the same conditions as in Example 11 except that the solvent of the solution 2 in Example 11 was changed to trichloromethane.

At this time, in all the devices, since the lower layer was dissolved when the upper layer was formed, the emission unevenness was so large that measurement was impossible.

Example 13 An element structure shown in FIG. 1E was prepared under the same conditions as in Example 11 except that the solvent of the solution 2 in Example 11 was changed to α-bromonaphthalene. However, luminescence with luminous efficiency as shown in the following [Table 13] was obtained.

[0181]

[Table 13]

When n = 11 to 12, the element could not be formed because the lower layer was dissolved during the formation of the upper layer.

[Example 14] When R in the molecular structure represented by Chemical Formula 5 is -C ₈ H ₁₇ and the molecular weight of the polymer having the repeating unit of Chemical Formula 5 is changed, When the dissolution range was measured by [Experiment 1], the results shown in the following [Table 14] were obtained.

[0184]

[Table 14]

This indicates that the dissolution range can be changed depending on the molecular weight of the polymer.

A solution 1 was prepared by dissolving 6 mg of a polymer having each molecular weight shown in [Table 14] with 1 ml of 1,2-dichloroethane when R in the chemical formula 5 was linear C ₈ H _17. did.

2.5 mg of OXD-1 and Ir (pp
y) 0.17 mg as ₃ 2.5 mg of polyvinyl biphenyl having a molecular weight of 100,000 as a binder polymer
Was dissolved in 1 ml of ethylbenzene to prepare solution 2.

2.5 mg of PBD and 2.5 mg of polystyrene (molecular weight 10,000) as a binder polymer were added to cyclohexane (solubility parameter 8.2 (cal / cm 2)).
³⁾ was dissolved in a solvent 1ml of ^1/2) to prepare a solution 3.

The solution 1 was placed on an oxygen-treated plasma ITO substrate (commercially available ITO, manufactured by Asahi Glass Co., Ltd .: 20Ω / □ or less).
Was spin coated at 1500 rpm for 1 second to form a 50 nm hole transport layer.

Further, the solution 2 was placed on the hole transport layer at a rotation speed of 1
2,000 rpm for 1 second by spin coating for 20
nm was obtained.

Further, the solution 3 was put on the light emitting layer at a rotation speed of 100.
50 nm by spin coating at 0 rpm for 1 second
Was obtained.

A cathode was formed by co-evaporating aluminum and lithium at a degree of vacuum of 10 ⁻³ Pa at a deposition rate of 1 nm / sec so that the lithium content was 1%.

With the device structure shown in FIG. 1E, light emission having luminous efficiency as shown in the following [Table 15] was obtained.

[0194]

[Table 15]

When the molecular weight was 10,000, the element could not be prepared because the lower layer was dissolved during the formation of the upper layer.

From the results of [Example 11] to [Example 14], it is understood that by adjusting the dissolving range of the hole transport layer, the selection range of the solvent for forming the upper light emitting layer is expanded.

Example 15 When R in the molecular structure represented by Chemical Formula 14 is a linear alkyl group (—C _n H _{2n + 1} ) and the molecular weight is 100,000, the solubility range is
When the measurement was performed according to [Experiment 1], the following [Table 1]
6] was obtained.

[0198]

[Table 16]

This indicates that the dissolution range can be varied depending on the length of the straight chain in R.

Here, PV having a molecular weight of 1,100,000
Dissolve 6 mg of K with 1 ml of 1,2 dichloroethane,
Solution 1 was prepared.

R in the molecular structure of the polyfluorene having [Chemical Formula 14] as a repeating unit is represented by a linear alkyl group (-C
_n H _{2n + 1)} and the polymer having a molecular weight 100,000 5 mg
And 0.17 mg of Ir (ppy) ₃ was dissolved in 1 ml of ethylbenzene to prepare a solution 2.

A solution 3 was prepared by dissolving 2.5 mg of PBD and 2.5 ml of polystyrene having a molecular weight of 50,000 as a binder polymer in 1 ml of cyclohexane.

The solution 1 was placed on an oxygen-treated ITO substrate (commercially available ITO, manufactured by Asahi Glass Co., Ltd .: 20Ω / □ or less).
Was spin coated at 1500 rpm for 1 second to form a 50 nm hole transport layer. According to [Experiment 1], the dissolution range of the hole transport layer was 8.9 to 10.0 (ca).
1 / cm ³ ) ^1/2 .

Further, the solution 2 was placed on the hole transport layer at a rotation speed of 1
2,000 rpm for 1 second by spin coating for 20
nm was obtained.

Further, the solution 3 was put on the light emitting layer at a rotation speed of 100.
50 nm by spin coating at 0 rpm for 1 second
Was obtained.

Finally, aluminum and lithium were co-deposited at a deposition rate of 1 nm / sec so that the lithium content was 1% to form a cathode.

With the device structure shown in FIG. 1B, light emission having luminous efficiency as shown in the following [Table 17] was obtained.

[0208]

[Table 17]

When N ≦ 8, the light emitting layer was dissolved during the formation of the electron transporting layer, so that no device could be prepared.

[Example 16] [0210] Except that the solvent of solution 3 in [Example 15] was changed to α-bromonaphthalene,
When the device structure shown in FIG. 1B was prepared under the same conditions as in [Example 15], light emission with luminous efficiency as shown in [Table 18] below was obtained.

[0211]

[Table 18]

[0212] When N was 12 to 15, the light emitting layer was dissolved during the formation of the electron transport layer, so that no device could be prepared.

Example 17 When R in the molecular structure represented by Chemical Formula 14 is -C ₈ H ₁₇ and the molecular weight of the polymer having the repeating unit of Chemical Formula 14 is varied, When the dissolution range was measured by Experiment 1], the following [Table 19] was obtained.
Were obtained.

[0214]

[Table 19]

This indicates that the range of dissolution can be changed depending on the molecular weight of the polymer.

Here, [Formula 14] in [Example 15]
The R of the molecular structure represented in the -C ₈ H _17, [Chemical Formula 14]
By varying the molecular weight of the polymer having repeating units of
When the device structure shown in FIG. 1B was prepared under the same conditions as in [Example 15], light emission having the luminous efficiency shown in [Table 20] below was obtained.

[0219]

[Table 20]

[0218] In Example 18 when the R alkyl group of straight chain molecular structure of poly carbazole compound having a repeating unit represented (-C _n H _{2n + 1)} in the Chemical Formula 5, dissolved scope Was measured according to [Experiment 1], and the results shown in [Table 21] below were obtained.

[0219]

[Table 21]

This indicates that the range of dissolution can be varied depending on the length of the straight chain in R.

Here, PV having a molecular weight of 1,100,000
Dissolve 6 mg of K with 1 ml of 1,2 dichloroethane,
Solution 1 was prepared.

In the chemical formula 5, R is a linear alkyl group (—C _n H
_{2n + 1} ), 5 mg of a polymer having a molecular weight of 10,000 and Ir
Solution 2 was prepared by dissolving 0.17 mg of (ppy) ₃ in 1 ml of xylene.

A solution 3 was prepared by dissolving 2.5 mg of PBD and 2.5 ml of polystyrene having a molecular weight of 50,000 as a binder polymer in 1 ml of cyclohexane.

The solution 1 was placed on an oxygen-treated plasma ITO substrate (commercially available ITO, manufactured by Asahi Glass Co., Ltd .: 20 Ω / □ or less).
Was spin coated at 1500 rpm for 1 second to form a 50 nm hole transport layer. The dissolution range of the hole transport layer is 8.9 to 10.0 (cal / cm ³ ) ^1/2.
Met.

Further, the solution 2 was placed on the hole transport layer at a rotation speed of 1
2,000 rpm for 1 second by spin coating for 20
nm was obtained.

Further, the solution 3 was put on the light emitting layer at a rotation speed of 100.
50 nm by spin coating at 0 rpm for 1 second
Finally, aluminum and lithium were deposited at a deposition rate of 1 nm / sec so that the lithium content was 1%.
A cathode was formed by co-evaporation at a rate of c.

With the device structure shown in FIG. 1B obtained in this way, light emission having the luminous efficiency shown in the following [Table 22] was obtained.

[0228]

[Table 22]

When N = 15, the light emitting layer was dissolved during the formation of the electron transport layer, so that no device could be prepared.

Example 19 An element structure shown in FIG. 1B was prepared under the same conditions as in Example 18 except that the solvent of the solution 3 in Example 18 was changed to nitroethane. Light emission with luminous efficiency as shown in the following [Table 23] was obtained.

[0231]

[Table 23]

When N ≧ 8, the light emitting layer was dissolved during the formation of the electron transporting layer, so that no device could be prepared.

[0233] [Example 20] -C ₈ H ₁₇ and R in Formula 5]
When the molecular weight of the polymer having the repeating unit of the formula [Chem. 5] was varied, the dissolution range was measured by [Experiment 1], and the results shown in [Table 24] below were obtained.

[0234]

[Table 24]

This shows that the dissolution range can be changed depending on the molecular weight of the polymer.

Here, by changing the molecular weight of the above polymer,
When the device structure shown in FIG. 1B was prepared under the same conditions as in [Example 18], light emission with luminous efficiency as shown in [Table 25] below could be obtained.

[0237]

[Table 25]

The molecular weight is from 100,000 to 1,000,000.
In the range of 00, solution 2 could not be prepared.

[Example 21] [Example 18]
And -C ₁₂ H ₂₅ and R a straight of Formula 5], a polymer 5mg of molecular weight 10,000 to repeating unit the Formula 5], I
1 (b) was prepared in the same manner as in [Example 18] except that 0.17 mg of r (ppy) ₃ was dissolved in 1 ml of a solvent shown in [Table 25] below to prepare Solution 2. As a result, light emission with luminous efficiency as shown in the following [Table 26] was obtained.

[0240]

[Table 26]

Even if the solvent is changed, the variation in luminance at 1 mA / cm ² is 10 out of the melting range of the hole transport layer.
%.

[0242]

As is apparent from the above description, according to the present invention, the thin film layer material constituting the organic electroluminescence device can be formed into a multilayer in a solution state, that is, by a wet method. The formation of the element structure of the element is simplified.

[Brief description of the drawings]

FIG. 1 (a) to (e) Element structure of an organic electroluminescence element

FIG. 2 (a) to (c) Procedures for measuring solubility parameters in the dissolution range of a sample piece

[Explanation of symbols]

 Reference Signs List 10 anode layer 20 hole transport layer (first organic layer) 40 light emitting layer 41 doping agent 42 host agent 60 electron transport layer (second organic layer) 70 cathode layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K007 AB02 AB03 AB04 AB18 CA01 CB01 DA01 DB03 EB00 FA01

Claims (8)

[Claims] 1. A light emitting layer having both an anode layer and a cathode layer, a light emitting layer having a host agent and a dopant emitting phosphorescence, and first and second layers laminated between the two electrode layers with the light emitting layer interposed therebetween. An organic electroluminescent device comprising a second organic layer and one of the electrode layers formed on a substrate, wherein an organic substance constituting the light emitting layer is formed by laminating on the substrate side of the light emitting layer. A second organic layer which is soluble in a solvent having a solubility parameter outside the solubility range for the organic substance constituting the first organic layer to be formed, and which is formed by laminating the light emitting layer on the side opposite to the substrate. An organic electroluminescent device, wherein an organic material constituting the organic layer is soluble in a solvent having a solubility parameter outside the solubility range for the organic material constituting the light emitting layer. 2. The organic substance constituting the first organic layer comprises at least one of a hole injecting substance, a hole transporting substance, and an electron blocking substance. Organic electroluminescence element. 3. The organic compound according to claim 1, wherein the organic substance constituting the second organic layer is at least one of an electron injecting substance, an electron transporting substance, and a hole blocking substance. The organic electroluminescent device according to the above. 4. The organic substance constituting the first organic layer is insoluble in a solvent having a solubility parameter of less than 8.9 (cal / cm ³ ) ^1/2 at room temperature, and is a substance constituting the light emitting layer. Is 8.4 (cal / cm ³ ) ^1/2 at room temperature
It is soluble in a solvent having a solubility parameter of less than 8.9 (cal / cm ³ ) ^{1/2 and} 8.4 at room temperature.
The organic material constituting the second organic layer, which is insoluble in a solvent having a solubility parameter of less than (cal / cm ³ ) ^1/2 , is 7.0 (cal / cm ³ ) ^1/2 or more at room temperature.
The organic electroluminescent device according to any one of claims 1 to 3, wherein the organic electroluminescent device is soluble in a solvent having a solubility parameter of less than 4 (cal / cm ³ ) ^1/2 . 5. The organic substance constituting the first organic layer is insoluble in a solvent having a solubility parameter of less than 8.9 (cal / cm ³ ) ^1/2 at room temperature, and is a substance constituting the light emitting layer. Is 7.0 (cal / cm ³ ) ^1/2 at room temperature
It is soluble in a solvent having a solubility parameter of less than 8.9 (cal / cm ³ ) ^1/2 and at room temperature.
Insoluble in a solvent having a solubility parameter of 5 (cal / cm ³ ) ^1/2 or more, the organic substance constituting the second organic layer is 11.5 (cal / cm ³ ) ^1/2 or more at room temperature. The organic electroluminescent device according to any one of claims 1 to 3, wherein the organic electroluminescent device is soluble in a solvent having a solubility parameter of 0.0 (cal / cm ³ ) ^1/2 or less. 6. The organic substance constituting the first organic layer is insoluble in a solvent having a solubility parameter of more than 10.0 (cal / cm ³ ) ^1/2 at room temperature, and comprises an organic substance constituting the light emitting layer. Is 10.0 (cal /
cm ³ ) greater than ^1/2 and 11.5 (cal / cm ³ )
The second organic layer is soluble in a solvent having a solubility parameter of less than ^1/2 and insoluble in a solvent having a solubility parameter of 11.5 (cal / cm ³ ) ^1/2 or more at room temperature. Organics are 11.5 at room temperature.
(Cal / cm ³ ) ^1/2 or more and 13.0 (cal / cm ³ )
^4. The organic electroluminescent device according to claim 1, wherein the organic electroluminescent device is soluble in a solvent having a solubility parameter of ^1/2 or less. 7. The molecular structure of the dopant is as follows: (In the chemical formula [Formula 1], Ar is an aryl group, X ₁₂ and X ₁₃
Each independently represents an arbitrary substituent, and an aromatic ring may be condensed between Ar and X _12, and n is an integer of 1 or more and 3 or less. ).
7. The organic electroluminescent device according to any one of items 1 to 6, wherein 8. The molecular structure of the dopant is as follows: (In the chemical formula [Chemical formula 2], R1 to R8 each independently represent hydrogen or an arbitrary substituent, and / or an aromatic ring is condensed in adjacent Rn (n is an integer of 1 to 8). The organic electroluminescent device according to any one of claims 1 to 6, wherein the organic electroluminescent device is represented by the following formula: