JP2002319488A - Organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electroluminescent element having a multilayer structure. SOLUTION: An organic matter constituting a hole block layer 50 is to be soluble to solvent having solubility parameter outside the dissolving range against an organic matter constituting a light-emitting layer 40 to be laminated on a positive electrode 10 side of the hole block layer 50.

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, since a so-called dry method is employed, in which a luminescent substance is deposited during the formation of a multilayer thin film, the manufacturing process is complicated and the production efficiency is poor.

[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]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an anode layer and a cathode layer, a light emitting layer having a host agent and a dopant emitting phosphorescence, An organic layer laminated to the light emitting layer between the layers,
In an organic electroluminescence device in which one of the electrode layers is formed on a substrate, an organic substance constituting the organic layer is out of a dissolving range with respect to an organic substance constituting the light emitting layer laminated on the substrate side of the organic layer. Was dissolved in a solvent having a solubility parameter of

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 organic layer is
The organic electroluminescent element is formed as a multilayer laminate structure by dissolving in a solvent having a solubility parameter outside the solubility range for the organic substance constituting the light emitting layer. At this time, 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 organic layer, when the light emitting layer and the organic layer are laminated adjacent to each other, The thin film layer can be formed without dissolving and mixing the organic substances constituting each thin film layer. That is, 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 the light emitting layer and the organic layer.

In this case, it is desirable that the organic material constituting the 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 substance constituting the light emitting layer is insoluble in a solvent having a solubility parameter of less than 8.9 (cal / cm ³ ) ^1/2 at room temperature, and the organic substance constituting the organic layer is not dissolved. Is 7.0 (ca) at room temperature
It is desirable that the composition be configured to be soluble in a solvent having a solubility parameter of 1 / cm ³ ) ^1/2 or more and less than 8.9 (cal / cm ³ ) ^1/2 .

The organic substance constituting the light emitting layer is insoluble in a solvent having a solubility parameter of 8.3 (cal / cm ³ ) ^1/2 or less at room temperature, and the organic substance constituting the organic layer is not dissolved at room temperature. 7.0 (cal / cm ³ )
It is also possible to constitute so as to be soluble in a solvent having a solubility parameter of ^1/2 or more and 8.3 (cal / cm ³ ) ^1/2 or less.

The organic substance constituting the light-emitting layer may be
11.5 (cal / cm ^Three)^1/2Above 13.0
(Cal / cm^Three)^1/2Has the following solubility parameters
The organic matter that is insoluble in the solvent and constitutes the organic layer is
11.5 (cal / cm^Three)^1/2Above 13.0
(Cal / cm^Three)^1/2Has the following solubility parameters
It is also possible to configure so as to be soluble in a solvent.

In these cases, it is preferable to use a compound represented by the chemical formula [Chemical Formula 1] or [Chemical Formula 2] as the dopant.

[0013]

FIG. 1 shows a basic structure of an organic electroluminescence device having a multilayered device structure for the purpose of improving luminous efficiency. The element structure of the organic electroluminescence element is such that a hole transport layer 20, an electron block layer 30, a hole transport layer 20, and an anode layer 10 formed on a substrate (not shown) The light emitting layer 40, the hole blocking layer 50, and the electron transport layer 60 have a multilayer laminated structure in which thin film layers are sequentially stacked. The light emitting layer 40 has a light emitting layer dopant 41 and a light emitting layer host ing.

In each element structure shown in FIGS. 1 to 4, the anode layer 10 is made of a transparent conductive material formed on a transparent insulating support such as a glass substrate. Conductive oxides such as tin oxide, indium oxide, indium tin oxide (ITO), or gold,
Metals such as silver and chromium, inorganic conductive substances such as copper iodide and copper sulfide, and conductive polymers such as polythiophene, polypyrrole, and polyaniline can be used.

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 device structures shown in FIGS. 1 to 4, the cathode layer 70 has lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, boron, aluminum, copper, silver, A simple substance such as gold or an alloy can be used. Further, these can be used in a laminated state. Also,
It can also be formed wet with 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 transport 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,

[0018]

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

[0020]

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

[0022]

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(In the chemical formula [Chemical Formula 5], R is a substituent composed of C, H, O, and N). Or,

[0024]

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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),

[0026]

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

[0028]

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N, N'-diphenyl-
N, N'-bis (1-naphthyl) -1,1'-biphenyl-4,4'-diamine (hereinafter also referred to as NPD)

[0030]

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

[0032]

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Copper phthalocyanine shown in Chemical Formula 10 is exemplified.

Further, the electron block 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;

[0035]

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

[0037]

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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,

[0040]

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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)

[0042]

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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.

[0045]

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

[0047]

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

[0054]

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

[0056]

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[0057]

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[0058]

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[0059]

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[0060]

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An iridium complex compound represented by any one of Chemical Formulas 16 to 21 and Chemical Formulas 23 to 27,

[0062]

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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 polystyrene, polyvinyl biphenyl, polyvinyl phenanthrene, polyvinyl anthracene, polyvinyl perylene, poly (ethylene-co-vinyl acetate), and cis and tran of 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,

[0066]

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

[0068]

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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],

[0070]

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

[0072]

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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].

[0074]

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The 4,4'-bis (1,1
-Diphenylethenyl) biphenyl (hereinafter referred to as DPVBi
Also called. ),

[0076]

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

[0078]

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4,4′-bis (1,1-bis (4-methylphenyl) ethenyl) biphenyl (hereinafter also referred to as DTVBi) represented by the following formula:

[0080]

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

[0082]

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[0083]

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

[0085]

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[0086]

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

[0091]

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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.

For further improving the luminous efficiency and simplifying the structure, the element structure shown in FIGS. 2 to 5 can be obtained by modifying the basic structure of the organic electroluminescence element shown in FIG.

The element structure of the organic electroluminescence element shown in FIG. 2 shows the first embodiment of the organic electroluminescence element of the present invention. Although the hole transport layer 20, the electron block layer 30, and the electron transport layer 60 of FIG. 1 are omitted, in FIG. 2, the light emitting layer 40 has a hole transport effect and an electron block effect, Layer 50
Has an electron transport effect to maintain luminous efficiency.

The device structure of the organic electroluminescence device shown in FIG. 3 is different from the device structure shown in FIG.
The electron block layer 30 and the electron transport layer 60 are omitted.

The element structure of the organic electroluminescence element shown in FIG. 4 is such that the electron block layer 30 and the hole block layer 50 are omitted from the element structure shown in FIG.

Next, a method for manufacturing an organic electroluminescence device will be described with reference to FIG. 2 as a first embodiment of the present invention.

First, an anode layer 10 is formed on a transparent insulating support serving as a substrate (not shown), for example, a glass substrate by an evaporation method or a sputtering method.

Next, the dopant 41 constituting the light emitting layer 40
And a host agent 42 dissolved or dispersed in a solvent to form a first solution. Here, the binder polymer can be further dissolved or dispersed in the first solution. Then, the light emitting layer 40 is formed on the anode layer 10 by a wet method using the first solution.

Further, a second solution is prepared by dissolving or dispersing the hole blocking substance in a solvent. Here, the binder polymer can be further dissolved or dispersed in the second solution. The hole blocking layer 50 is formed on the light emitting layer 40 by a wet method using the second solution.

The solubility parameter of the solvent used for the second solution is determined by the temperature at which the hole blocking layer 50 is formed.
The substances (doping agent 41, host agent 4
2 and a binder polymer). In the formation of the hole blocking layer 50 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
Ir (ppy) shown in [Formula 15]_ThreeAnd binder high
When using poly (4-vinylbiphenyl) as a
Solubility indicating the solubility range of the organic substances constituting these light-emitting layers
The parameters were 8.7 (cal / cm) at room temperature.^Three)
^1/2Above 11.1 (cal / cm^Three)^1/2It is as follows. I
Therefore, as a solvent used for the second solution, this solubility
If a solvent outside the parameter range is used, the light emitting layer 40
Blocking layer 5 without dissolving organic matter contained in
0 can be formed. Examples of such solvents
n-nonane (solubility parameter 7.64 (cal / cm
^Three)^1/2), 1-decene (solubility parameter 7.85 (ca)
l / cm ^Three)^1/2), Methylcyclohexane (solubility para
Meter 8.13 (cal / cm^Three)^1/2), Cyclohexa
(Solubility parameter 8.20 (cal / c
m^Three)^1/2), 1-chloropropane (solubility parameter
8.30 (cal / cm^Three)^1/2), Acetonitrile (solvent
Resolution parameter 11.8 (cal / cm^Three)^1/2)etc
No.

At this time, the solvent used for the first and second solutions is evaporated by natural drying, so that the light emitting layer 40 and the hole blocking layer 50 are formed. in this case,
There is no need to carry out treatments such as polymerization and curing by heating and irradiation of ultraviolet rays. Therefore, the production process is simple and the production efficiency can be improved.

The wet method used in the present invention includes 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, the cathode layer 70 is formed on the hole blocking layer 50 by using a vapor deposition method or the like, and the organic electroluminescent 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. 3 shows a second embodiment of the organic electroluminescence device of the present invention. In the manufacturing process of the device structure shown in FIG. 2, the anode layer 10 is formed before the light emitting layer 40 is formed. After a hole transporting substance such as PVK is formed thereon by a wet method to form a hole transporting layer 20, FIG.
Light emitting layer 40, hole blocking layer 50, and cathode layer 70
Are sequentially obtained.

FIG. 4 shows a third embodiment of the organic electroluminescence device of the present invention. In the manufacturing process of the device structure shown in FIG. 2, the anode layer 10 is formed before the light emitting layer 40 is formed. After a hole transporting substance such as PVK is formed thereon by a wet method to form a hole transporting layer 20, FIG.
A light emitting layer 40 is formed in the same manner as described above, and an electron transporting polymer such as a polyfluorene compound or an electron transporting low molecule such as a polycarbazole compound is formed on the light emitting layer 40 by a wet method. Is formed, a cathode layer 70 is formed on the electron transport layer 60 in the same manner as in FIG.

[0109]

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 for the thin film layers such as the hole transport layer, the electron block layer, the light emitting layer, the hole block layer, the electron transport layer, and the 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.

[0111]

[Table 1]

Solvents having the solubility parameters shown in Table 1 were prepared in ascending order of these solubility parameter values.
As shown in FIG. 5A and FIG. 5B, test pieces 3 were placed in beakers 2 filled with the solvent 1 for 10 times, respectively.
Then, as shown in FIG. 5C, the test piece 3 is taken out, and it is visually confirmed whether or not the thin film is dissolved.

[0113] Of the solubility parameters of the solvent in which the thin film dissolves, the minimum value and the maximum value are defined as the test piece dissolution range.

Example 1 PVK having a polystyrene equivalent weight average molecular weight (hereinafter referred to as molecular weight) of 1,100,000 as measured by gel permeation chromatography.
And 0.5mg as 6mg and Ir (ppy) ₃ was dissolved in 1,2 dichloroethane 1ml as to prepare a solution 1.

2.5 mg of PBD, 0.17 mg of an iridium complex compound represented by the following formula, and 2.5 of polystyrene (molecular weight 10,000) as a binder polymer.
mg with cyclohexane (solubility parameter 8.2 (c
al / cm ³ ) ^1/2 ) was dissolved in 1 ml to prepare solution 2.

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 1000 rpm for 1 second to form a 50 nm light emitting layer. The dissolution range of this light emitting layer was 8.9 to 10.0 (cal / cm ³ ) ^1/2 .

Further, the solution 2 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%.

At this time, 160 c at 9 V and 1 mA / cm ²
A green light emission of d / m ² was obtained.

[Comparative Example 1] 6 mg of PVK having a molecular weight of 1,100,000 and 0.5 mg of Ir (ppy) ₃ were mixed for 1 m.
Solution 1 was prepared by dissolving with 1 of 1,2 dichloroethane.

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

Further, the degree of vacuum was set to 10 ⁻³ by a vacuum evaporation apparatus.
PBD 50n at a deposition rate of 1 nm / sec with Pa
m to form a hole blocking layer, and finally deposit aluminum and lithium at a deposition rate of 1% so that the lithium content is 1%.
A cathode was formed by co-evaporation at a speed of nm / sec to form an element structure shown in FIG.

At this time, 170 c at 9 V, 1 mA / cm ²
A green light emission of d / m ² was obtained.

A comparison between [Example 1] and [Comparative Example 1] shows that the formation of the hole blocking layer is performed by wet spin coating.
It can be seen that the performance is only slightly lower than when formed by vapor deposition.

Example 2 An element structure shown in FIG. 2 was prepared in the same manner as in [Example 1] except that the solvent of the solution 2 of [Example 1] was changed to the solvent of [Table 2] shown below. And light emission with luminous efficiency as shown in [Table 2] was obtained.

[0126]

[Table 2]

Example 3 A solution 1 was prepared by dissolving 6 mg of PVK having a molecular weight of 1,100,000 with 1 ml of 1,2-dichloroethane.

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

2.5 mg as PBD, 0.17 mg as an iridium complex compound represented by the following formula, and 2.5 as polystyrene (molecular weight 10,000) as a binder polymer.
mg with cyclohexane (solubility parameter 8.2 (c
Al / cm ³ ) ^1/2 ) was dissolved in 1 ml of a solvent to prepare a solution 3.

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. The dissolution range of this hole transport layer was 8.9 to 10.0 (cal / 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. The dissolution range of this light emitting layer is 8.7 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.

A cathode was formed by co-depositing aluminum and lithium at a degree of vacuum of 10 ⁻³ Pa and a deposition rate of 1 nm / sec so that the lithium content was 1% using a vacuum deposition apparatus to form a cathode. It was created.

At this time, 480 c at 9 V and 1 mA / cm ²
A green light emission of d / m ² was obtained.

Example 4 An element structure shown in FIG. 3 was prepared in the same manner as in [Example 3] except that the solvent of the solution 3 of [Example 3] was changed to the solvent shown in the following table. The luminescence with the luminous efficiency shown in (1) was obtained.

[0136]

[Table 3]

[Example 5] In the same manner as in [Example 3] except that the dopant in the light emitting layer was changed to Ir (ppy) ₃ in [Example 3] and the dopants shown in [Table 4] below were used. When the device structure shown in Table 4 was prepared, light emission having the luminous efficiency shown in Table 4 below was obtained.

[0138]

[Table 4]

Example 6 In Example 3, lithium fluoride was vacuum-deposited at a degree of vacuum of 10 ⁻³ Pa and a speed of 0.1 nm / sec as an electron injection layer between the hole blocking layer and the cathode. An element structure shown in FIG. 3 was formed in the same manner as in [Example 3] except that a film was formed to a thickness of 5 nm and the cathode was changed to aluminum.

At this time, 8.7 V, 1 mA / cm ² and 52
It emitted green light of 0 cd / m ² .

[Example 7] Copper phthalocyanine was vacuum-deposited as a hole injection layer between the ITO anode and the hole transport layer of [Example 3] at a degree of vacuum of 10 ^-3 Pa and a speed of 0.1 n.
An element structure shown in FIG. 3 was prepared in the same manner as in [Example 3] except that a film was formed to a thickness of 5 nm at m / sec.

At this time, 8.4 V, 1 mA / cm ² and 52
It emitted green light of 0 cd / m ² .

[0143] [Example 8] and molecular weight R alkyl straight polyfluorene compound represented by Formula _{41] (-C n H 2n +} 1) is dissolved in solubility parameter when 1,000,000 [Table 5] below shows the measurement results of the dissolution range when the range was measured according to [Experiment 1].

[0144]

[Table 5]

It can be seen that the range of dissolution can be adjusted by the length of the alkyl group attached to R.

At this time, the dissolution range was 8.4 (cal / cm).
³ ) When the ^{ratio is} less than ^1/2 or 11.5 (cal / cm ³ ) ^1/2 or more, the range of selection of the material of the light emitting layer located below is widened.

Then, PVK (molecular weight 1,100,00
6 mg was dissolved in 1 ml of 1,2 dichloroethane as 0) to prepare a solution 1.

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.

R of the polyfluorene compound represented by the formula
Was dissolved polymer 5mg of molecular weight 1,000,000 having repeating units and an alkyl straight chain (-C _n H _{2n + 1)} in cyclohexane 1 ml, was prepared a solution 3.

The solution 1 was placed on the oxygen-treated ITO substrate (commercially available ITO, manufactured by Asahi Glass Co., Ltd .: 20Ω / □ 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 is 8.6-11.
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.

[0153] Finally, aluminum and lithium in vacuum 10 ^-3 Pa by a vacuum deposition apparatus, lithium to form a cathode were co-deposited at a rate of deposition rate of 1 nm / sec to be 1 percent 4 After creating the element structure shown,
The luminescence with the luminous efficiency shown in the following [Table 6] was obtained.

[0154]

[Table 6]

Example 9 The procedure of Example 8 was repeated except that the binder polymer of solution 2 was changed to PVK (molecular weight: 50,000), the solvent was changed to trichloroethylene, and the solvent of solution 3 was changed to ethylbenzene. An element structure shown in FIG. 4 was prepared in the same manner as in [Example 8].

At this time, the dissolution range of the light emitting layer was 8.9 to 1
0.6 (cal / cm ³ ) ^1/2 , and light emission having the luminous efficiency shown in the following [Table 7] was obtained.

[0157]

[Table 7]

The solvent of solution 3 was changed to ethylbenzene, and the binder polymer of the light emitting layer was changed to PVK insoluble in ethylbenzene.
(Molecular weight: 50,000), resulting in 1 mA / c
The luminance at m ² decreased.

Example 10 Polyfur represented by Chemical Formula 41
The R of the orene compound is represented by a linear -C_TenH _{twenty one}Each molecule when
The solubility range in the solubility parameter was set to [Experiment 1].
Table 8 below shows the results of the measurement of the dissolution range when measuring the length.
Show.

[0160]

[Table 8]

It can be seen that the dissolution range can be adjusted by the molecular weight.

Using these materials, an element structure shown in FIG. 4 was prepared in the same manner as in [Example 8].
The luminescence of the luminous efficiency shown in the following was obtained.

[0163]

[Table 9]

[Example 11] Polyfur represented by the formula [41]
The R of the orene compound is represented by a linear -C_TenH _{twenty one}(Molecular weight 10,0
00), the difference in performance depending on the solvent was investigated. Element production
The formation method is the same as that of the polymerization used for the electron transport layer in [Example 8].
FIG. 4 shows the same procedure as in [Example 8] except that the body and solvent were changed.
When the device structure was fabricated, the light emission shown in [Table 10] below was obtained.
Efficient light emission was obtained.

[0165]

[Table 10]

Even if the solvent changes, if the solvent in the insoluble range of the lower layer is used, the luminance variation at 1 mA / cm ² is 10
%.

Example 12 The solubility range of a polymer having a molecular weight of 100,000 in which R in the polyfluorene compound represented by Chemical Formula 14 is linear alkyl (—C _n H _{2n + 1} ) is shown in [Experiment 1]. As a result, the measurement results shown in the following [Table 11] were obtained.

[0168]

[Table 11]

It can be seen that the dissolution range can be adjusted by the length of the alkyl group attached to R. At this time, the dissolution range was 8.9 (cal).
/ Cm ³ ) When adjusted to less than ^1/2 , the material selection range of the lower hole transport layer is widened.

Further, if the solvent is adjusted so as to be insoluble in a solvent of less than 8.4 (cal / cm ³ ) ^1/2 or more than 10 (cal / cm ³ ) ^1/2 , the selection range of the solvent in forming the upper layer is reduced. Become wider.

Here, PV having a molecular weight of 1,100,000
Dissolve 6 mg of K in 1 ml of dichloroethane to obtain solution 1.
It was created.

A compound having a molecular weight of 10 wherein R is a straight-chain alkyl (—C _n H _{2n + 1} ) of the polyfluorene compound represented by the following formula:
A solution 2 was prepared by dissolving 5 mg of a 0000 polymer and 0.17 mg of Ir (ppy) _{3 in} 1 ml of ethylbenzene.

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. 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. At this time, luminescence with luminous efficiency shown in the following [Table 12] was obtained.

[0177]

[Table 12]

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 13] [Example 12] except that the solvent of the solution 3 of [Example 12] was changed to α-bromonaphthalene.
When the element structure shown in FIG.
Light emission having the luminous efficiency shown in Table 13 was obtained.

[0180]

[Table 13]

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

[0182] measure dissolution range in the solubility parameter in the molecular weight when the R of Example 14 polyfluorene compound represented by Chemical Formula 14] was -C ₈ H _{1 7} straight accordance Experiment 1 As a result, the measurement results shown in the following [Table 4] were obtained.

[0183]

[Table 14]

It can be seen that the dissolution range can be adjusted by the molecular weight.

Here, an element structure shown in FIG. 4 was prepared in the same manner as in [Example 12] using the polymer having the adjusted molecular weight. Obtained.

[0186]

[Table 15]

[Example 15] The molecular weight of the polyfluorene compound represented by the formula [Chemical Formula 14], where R is a straight-chain -C ₉ H ₁₉ , is 10
[Example 1] Except that 5 mg of a 0000 polymer and 0.17 mg of Ir (ppy) ₃ were dissolved in 1 ml of each of the solvents shown in [Table 16] below and the solution 2 of [Example 12] was used.
When the device structure shown in FIG. 4 was prepared in the same manner as in [2], light emission with luminous efficiency shown in [Table 16] below was obtained.

[0188]

[Table 16]

Even if the solvent changes, the variation in luminance at 1 mA / cm ² is within 10%.

Example 16 When the dissolution range of the polycarbazole compound shown in [Chemical Formula 5] in which R was a straight-chain alkyl (—C _n H _{2n + 1} ) was measured according to [Experiment 1], The measurement results shown in the following [Table 17] were obtained.

[0191]

[Table 17]

It can be seen that the range of dissolution can be adjusted by the length of the alkyl group attached to R.

At this time, the dissolution range was 8.9 (cal / cm).
³ ) Adjusting to less than ^1/2 widens the material selection range of the lower hole transport layer.

If the solvent is adjusted so as to be insoluble in a solvent of less than 8.4 (cal / cm ³ ) ^1/2 or more than 10 (cal / cm ³ ) ^1/2 , the selection range of the solvent at the time of forming the upper layer is reduced. Become wider.

Here, PV having a molecular weight of 1,100,000
Dissolve 6 mg of K in 1 ml of dichloroethane to obtain solution 1.
It was created.

R of the polycarbazole compound represented by the following formula
Alkyl straight (-C _n H _{2n + 1)} and the molecular weight 10,
A solution 2 was prepared by dissolving 5 mg of 000 polymer and 0.17 mg of Ir (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 .: 20Ω / □ or less).
Was spin coated at 1500 rpm for 1 second to form a 50 nm hole transport layer. The dissolution range of this hole transport layer was 8.9 to 10.0 (cal / 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
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. At this time,
Light emission with the luminous efficiency shown in [Table 18] was obtained.

[0201]

[Table 18]

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

Example 17 An element structure shown in FIG. 4 was prepared in the same manner as in [Example 16] except that the solvent of solution 3 in [Example 16] was changed to nitroethane.
The luminescence of the luminous efficiency shown in the following was obtained.

[0204]

[Table 19]

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 18] The dissolution range at each molecular weight when R of the polycarbazole compound shown in [Chemical Formula 5] is -C ₈ H ₁₇ was measured according to [Experiment 1]. The measurement results shown in [Table 20] were obtained.

[0207]

[Table 20]

It can be seen that the dissolution range can be adjusted by the molecular weight.

Here, an element structure shown in FIG. 4 was prepared in the same manner as in [Example 16] using the polymer adjusted to each of the above-mentioned molecular weights. was gotten.

[0210]

[Table 21]

Solution 2 could not be prepared with a molecular weight of 100,000 to 1,000,000.

Example 19 Polycarba represented by Chemical Formula 5
R of the sol compound is represented by a linear -C₁₂H _{twenty five}Molecular weight 1
5 mg as a 000 polymer and Ir (ppy)_ThreeWhen
0.17 mg to 1 ml each of the solvents shown in the following [Table 22].
Example 1 except that the solution dissolved in
6], the device structure shown in FIG.
22].

[0213]

[Table 22]

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

[0215]

As is clear from the above description, according to the present invention, the light-emitting layer constituting the organic electroluminescence element and the organic layer laminated on the light-emitting layer are in a solution state, that is, simply by a wet method. An organic electroluminescence element having an element structure capable of forming a multilayer stack is obtained.

[Brief description of the drawings]

FIG. 1 shows an element structure of an organic electroluminescence element.

FIG. 2 shows a first embodiment of an element structure of the present invention.

FIG. 3 shows a second embodiment of the device structure of the present invention.

FIG. 4 shows a third embodiment of the device structure of the present invention.

FIG. 5 (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 40 light emitting layer 41 doping agent 42 host agent 50 hole blocking layer (organic layer) 70 cathode layer

Claims (7)

[Claims] 1. An electrode layer comprising both an anode layer and a cathode layer, a light emitting layer having a host agent and a dopant emitting phosphorescence, and an organic layer laminated between the two electrode layers on the light emitting layer. In an organic electroluminescence device in which one of the electrode layers is formed on a substrate, an organic substance constituting the organic layer dissolves in an organic substance constituting the light emitting layer laminated on the substrate side of the organic layer. An organic electroluminescent device characterized by being soluble in a solvent having a solubility parameter outside the range. 2. The organic electroluminescent device according to claim 1, wherein the organic material constituting the organic layer comprises at least one of an electron injecting substance, an electron transporting substance, and a hole blocking substance. element. 3. The organic substance forming the light emitting layer is insoluble in a solvent having a solubility parameter of less than 8.9 (cal / cm ³ ) ^1/2 at room temperature, and the organic substance forming the organic layer is at room temperature. ^3. It is soluble in a solvent having a solubility parameter of 7.0 (cal / cm ³ ) ^1/2 or more and less than 8.9 (cal / cm ³ ) ^1/2. Organic electroluminescence device. 4. The organic substance constituting the light emitting layer is insoluble in a solvent having a solubility parameter of 8.3 (cal / cm ³ ) ^1/2 or less at room temperature, and the organic substance constituting the organic layer is at room temperature. ^3. It is soluble in a solvent having a solubility parameter of 7.0 (cal / cm ³ ) ^1/2 or more and 8.3 (cal / cm ³ ) ^1/2 or less. Organic electroluminescence device. 5. The organic material constituting the light emitting layer is 11.5 (cal / cm ³ ) ^1/2 or more and 13.0 (ca) at room temperature.
1 / cm ³ ) ^1/2 , which is insoluble in a solvent having a solubility parameter of at most 11.5 (cal / cm ³ ) ^1/2 at room temperature and 13.0 (ca) at room temperature.
The organic electroluminescent device according to claim 1, wherein the organic electroluminescent device is soluble in a solvent having a solubility parameter of 1 / cm ³ ) ^1/2 or less. 6. 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. ).
6. The organic electroluminescent device according to any one of items 1 to 5, 7. 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 or more and 8 or less) The organic electroluminescent device according to claim 1, wherein the organic electroluminescent device is represented by the following formula: