JP2000173772A - Organic electroluminescent material and organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material, having high fluorescent quantum yield by making 9-aminoacridine or an acridone derivative contained as a light emitting material. SOLUTION: As an organic electroluminescent material, constituting a light emitting layer, 9-aminoacridine represented by formula I or an acridone derivative shown by formula II (X is a hydrogen group, an alkyl group, or an aryl group) is used as a luminescent material. Desirbly, 9-(10-methyl)-acridone or 9-(10-phenyl)-acridone is used. Preferably, a mixture additionally containing 9,9'-bianthoryl or P-quarter-phenyl is used as a matrix material, so that the film quality of the light-emitting layer can be improved. Using this organic electroluminescent material in the constitution of an element, an organic electroluminescent element having high light-emitting efficiency can be constituted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent material and an organic electroluminescent device using the same.

[0002]

2. Description of the Related Art Organic electroluminescent materials are:
Due to its features such as self-emission and high-speed response, it is expected to be applied to organic electroluminescence devices such as flat panel displays (for example, see Nikkei Electronics, 1996.1.29, pp. 99-103). ).

In such an organic electroluminescence device, it is necessary that the ratio of the amount of light emission (luminous efficiency) to the current injected into the device is large. Here, the luminous efficiency of the organic electroluminescence element is
It is proportional to the fluorescence quantum yield of a light emitting material molecule (also referred to as an organic electroluminescent material) included in the device. Therefore, in order to increase the luminous efficiency of the organic electroluminescence device, it is essential to use a luminescent material molecule having a high fluorescence quantum yield.

Conventionally, as a light emitting material molecule of an organic electroluminescence device, a material obtained by adding a small amount of a quinacridone derivative to 8-hydroxyquinoline aluminum,
There are reports on materials such as distyrylarylene derivatives. Also, the present inventors have disclosed in Japanese Patent Application No. 10-79453.
In the specification, an organic electroluminescent device using an anthracene derivative, a bianthryl derivative, a perylene derivative, or a tetracene derivative is proposed.

[0005]

However, the fluorescent quantum yield of the light-emitting material molecules used in the above-mentioned conventional organic electroluminescent device is not sufficient, and the light-emitting efficiency of the device is low. An object of the present invention is to provide an organic electroluminescent material having a large fluorescence quantum yield and an organic electroluminescent device having a large luminous efficiency using such a material.

[0006]

The object of the present invention is to provide a light-emitting material having a structural formula

[0007]

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This is achieved by an organic electroluminescent material characterized by containing 9-aminoacridine. In addition, the above-mentioned object, as a light emitting material,
Structural formula

[0009]

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The present invention is also achieved by an organic electroluminescent material characterized by containing a compound represented by the following formula: In the above organic electroluminescent material, the compound has a structural formula

[0011]

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9 (10-methyl) -acridone represented by the formula: In the above organic electroluminescent material, the compound has a structural formula

[0013]

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9 (10-phenyl) -acridone represented by the formula: In the above organic electroluminescent material, the light emitting material may have a structural formula

[0015]

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It may further include 9,9'-bianthryl. In the above organic electroluminescent material, the light emitting material may have a structural formula

[0017]

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The compound may further contain P-quarterphenyl represented by the formula: Further, the above object is also achieved by an organic electroluminescence element having an organic layer including a light emitting layer made of the above organic electroluminescence material, and a pair of electrode layers formed so as to sandwich the organic layer. Achieved.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An organic electroluminescence device according to the present invention typically comprises an anode electrode 12 formed on a substrate 10 and an anode electrode 12 as shown in FIG.
The hole transport layer 14 formed thereon, the light emitting layer 16 formed on the hole transport layer 14, the electron transport layer 18 formed on the light emitting layer 16, and the electron transport layer 18 formed on the electron transport layer 18 It is composed of a cathode electrode 20. Here, the hole transport layer 14,
The light emitting layer 16 and the electron transport layer 18 are formed of a resin layer.

Here, the organic electroluminescent material constituting the light emitting layer 16, which is a main feature of the present invention, has a structural formula

[0021]

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9-aminoacridine represented by the following formula:

[0023]

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The compound represented by the formula (1) can be applied. More specifically, the compound represented by the formula

[0025]

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9 (10H) -acridone represented by the structural formula

[0027]

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9 (10-methyl) -acridone represented by the following formula:

[0029]

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9 (10-phenyl) -acridone represented by the following formula can be applied. That is, as a result of intensive studies on the fluorescence quantum yields of various nitrogen-containing aromatic compounds by the present inventors, the above-mentioned 9-aminoacridine, 9
It has been found for the first time that (10H) -acridone, 9 (10-methyl) -acridone, and 9 (10-phenyl) -acridone have a particularly large fluorescence quantum yield as compared with other materials. By using such a light-emitting material as the light-emitting layer 16 of the organic electroluminescence element, an organic electroluminescence element having high luminous efficiency can be formed.

Also, the structural formula

[0032]

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9,9'-bianthryl represented by the following formula:

[0034]

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Using a compound such as P-quarterphenyl represented by the following formula as a matrix material,
The organic electroluminescent material may be composed of a mixture to which the compound shown in [Formula 17] is added. As the matrix material, it is preferable to use a material having a good film quality and a higher emission energy (shorter emission wavelength) than the above compound. By using a mixture added to such a matrix material, the film quality of the light emitting layer 16 can be improved, and highly efficient light emission can be obtained. The amount of the compound added to the matrix material is preferably such that the ratio to the total number of molecules present in the light emitting layer 16 is 0.01 to 80%, particularly 0.1 to 20%.

As the material of the substrate 10, for example, glass such as soda lime glass and borosilicate glass, and synthetic resin such as polycarbonate, acrylic and epoxy can be used. As a material of the electrode 12 for the anode, for example, a transparent electrode such as SnO ₂ , InO ₂ , and ITO or a translucent electrode made of gold or nickel can be used.

As the cathode electrode 20, for example, Mg,
A metal which easily emits electrons, such as Al, Ag, In, Li, and Na, and an alloy thereof can be used, and a film formed to a thickness of 30 nm or more by a vacuum evaporation method or a sputtering method is preferable. As a material of the hole transport layer 14, for example, a compound represented by the following structural formula can be applied.

[0038]

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[0039]

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[0040]

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[0041]

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[0042]

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[0043]

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[0044]

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[0045]

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As the material of the electron transport layer 18, for example, a compound represented by the following structural formula can be applied. Note that the electron transport layer 18 is not necessarily provided.

[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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[0053]

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[0054]

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[0055]

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[0056]

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[0057]

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[0058]

[Example 1] References (Yasuharu Nishikawa, Keizo Hiraki, "Fluorescence / phosphorescence analysis method", using an ethanol solution of anthracene as a standard material for fluorescence quantum yield (fluorescence quantum yield 0.31). According to the method of Kyoritsu Shuppan, 1984, pp. 76-80), the fluorescence quantum yield of 9-aminoacridine was measured.

First, a 3 × 10 ⁻⁷ M ethanol solution of anthracene and 9-aminoacridine was prepared. Next, these sample solutions were excited at a constant excitation wavelength and excitation light intensity, and a corrected fluorescence spectrum was obtained. In order to eliminate the influence of oxygen during the measurement, the fluorescence quantum yield was measured after the atmosphere was replaced with nitrogen.

The photon numbers per unit time of the total fluorescence obtained from the ethanol solution of anthracene and the ethanol solution of 9-aminoacridine are F ₁ and F ₂ , respectively, and the fluorescence quantum yields of both substances are φ _f1 and φ _f2 , respectively. If the molar extinction coefficients at the excitation wavelength are ε ₁ and ε ₂ , and the concentrations are c ₁ and c ₂ , respectively, φ _f1 / φ _f2 = (F ₁ × ε ₂ × c ₂ ) / (F ₂ × ε ₁ × c ₁ ). Thus, the fluorescence quantum yield of 9-aminoacridine was determined by determining φ _f2 from this formula and the above measurement results.

As a result, the fluorescence quantum yield of 9-aminoacridine was 0.94. [Example 2] In the same manner as in Example 1, 9 (10-H)
-The fluorescence quantum yield of acridone was measured. As a result, the fluorescence quantum yield of 9 (10-H) -acridone was 0.5.
97.

[Embodiment 3] In the same manner as in Embodiment 1, 9
The fluorescence quantum yield of (10-methyl) -acridone was measured. As a result, the fluorescence quantum yield of 9 (10-methyl) -acridone was 0.99.

[Embodiment 4] In the same manner as in Embodiment 1, 9
The fluorescence quantum yield of (10-phenyl) -acridone was measured. As a result, the fluorescence quantum yield of 9 (10-phenyl) -acridone was 0.96.

Comparative Example 1 The structural formula was obtained in the same manner as in Example 1.

[0065]

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The fluorescence quantum yield of acridine was measured. As a result, the fluorescence quantum yield of acridine was 0.01. Example 5 A glass substrate with an ITO electrode was washed with water, acetone, and isopropyl alcohol.

Next, a vacuum deposition apparatus (degree of vacuum: 1 × 10
^-6 Torr, substrate temperature: room temperature) to form a hole transport layer on the ITO electrode

[0068]

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Is 50 nm, 9-aminoacridine is 10 nm as a light-emitting layer, and the structural formula is

[0070]

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PBD shown by 50 nm, an Al--Li alloy (Li: 0.5% by weight) as an electrode layer was 50 nm,
Deposited sequentially. Thus, a laminated organic electroluminescence device using 9-aminoacridine was prepared. When a voltage was applied to this device using the ITO electrode as a positive electrode and the Al-Li electrode as a negative electrode, blue-green light emission was observed at an applied voltage of 5 V or more, and the emission luminance was 920 cd / m ² at an applied voltage of 10 V.

Example 6 A glass substrate with an ITO electrode was washed with water, acetone and isopropyl alcohol. Next, a vacuum deposition device (degree of vacuum: 1 × 10 ⁻⁶ To)
rr, substrate temperature: room temperature), TPD was 50 nm as a hole transport layer and 9 (10
H) -Acridone of 10 nm, PBD as electron transport layer
Is 50 nm, and an Al—Li alloy (Li: 0.
5% by weight) were sequentially deposited in a thickness of 50 nm.

In this way, a laminated organic electroluminescence device using 9 (10H) -acridone was prepared. When a voltage was applied to this device using the ITO electrode as the positive electrode and the Al-Li electrode as the negative electrode, blue-green light emission was observed at an applied voltage of 5 V or more, and the emission luminance was 1020 cd / m ² at an applied voltage of 10 V.

Example 7 A glass substrate with an ITO electrode was washed with water, acetone and isopropyl alcohol. Next, a vacuum deposition device (degree of vacuum: 1 × 10 ⁻⁶ To)
rr, substrate temperature: room temperature), TPD was 50 nm as a hole transport layer and 9 (10
-Methyl) -acridone 10 nm, PBD 50 nm as an electron transport layer, Al-Li alloy (L
i: 0.5% by weight).

Thus, a laminated organic electroluminescence device using 9 (10 methyl) -acridone was prepared. An Al-
When a voltage is applied using the Li electrode as a negative electrode, an applied voltage of 5 V
Thus, blue-green light emission was observed, and the light emission luminance was 1560 cd / m ² at an applied voltage of 10 V.

Example 8 A glass substrate with an ITO electrode was washed with water, acetone and isopropyl alcohol. Next, a vacuum deposition device (degree of vacuum: 1 × 10 ⁻⁶ To)
rr, substrate temperature: room temperature), TPD was 50 nm as a hole transport layer and 9 (10
-Phenyl) -acridone 10 nm, PBD 50 nm as an electron transport layer, and Al-Li alloy (L
i: 0.5% by weight).

Thus, a laminated organic electroluminescent device using 9 (10-phenyl) -acridone was prepared. This device is provided with A
When a voltage was applied using the l-Li electrode as a negative electrode, blue-green light emission was observed at an applied voltage of 5 V or more, and light emission luminance was 1660 cd / m ² at an applied voltage of 10 V.

Example 9 A glass substrate with an ITO electrode was washed with water, acetone and isopropyl alcohol. Next, a vacuum deposition device (degree of vacuum: 1 × 10 ⁻⁶ To)
rr, substrate temperature: room temperature), a layer in which TPD was 50 nm as a hole transport layer and 9-aminoacridine and 9,9′-bianthryl were co-deposited as a light-emitting layer on the ITO electrode (deposition ratio: 9-aminoacridine). 9, for one molecule
9′-bianthryl 99 molecule) was sequentially deposited in a thickness of 10 nm, an electron transport layer of 50 nm of PBD, and an electrode layer of 50 nm of an Al—Li alloy (Li: 0.5% by weight).

Thus, 9-aminoacridine and 9,
A laminated organic electroluminescence device using 9'-bianthryl was produced. When a voltage was applied to this device using the ITO electrode as a positive electrode and the Al-Li electrode as a negative electrode, blue light emission was observed at an applied voltage of 4 V or more, and the light emission luminance was 2030 cd / m ² at an applied voltage of 10 V.

Example 10 A glass substrate with an ITO electrode was washed with water, acetone and isopropyl alcohol. Next, a vacuum deposition device (degree of vacuum: 1 × 10 ⁻⁶ To)
rr, substrate temperature: room temperature), TPD was 50 nm as a hole transport layer and 9 (10
H) -Acridone and 9,9′-Bianthryl were simultaneously vapor-deposited (deposition ratio: 9 (10H) -acridone per molecule, 9,9′-Bianthryl 99 molecules) at 10 nm, and PBD at 50 nm as the electron transport layer. Al-
A 50 nm thick Li alloy (Li: 0.5% by weight) was sequentially deposited.

Thus, a laminated organic electroluminescent device using 9 (10H) -acridone and 9,9′-bianthryl was prepared. This element has ITO
When a voltage is applied using the electrode as a positive electrode and the Al-Li electrode as a negative electrode, blue light emission is observed at an applied voltage of 4 V or more,
The emission luminance is 2520 cd / m ^{2 at an} applied voltage of 10 V.
Met.

Example 11 A glass substrate with an ITO electrode was washed with water, acetone and isopropyl alcohol. Next, a vacuum deposition device (degree of vacuum: 1 × 10 ⁻⁶ To)
rr, substrate temperature: room temperature), TPD was 50 nm as a hole transport layer and 9 (10
-Methyl) -acridone and 9,9′-bianthryl were simultaneously vapor-deposited (deposition ratio: 9 (10-methyl) -acridone per molecule, 9,9′-bianthryl 99 molecules) at 10 nm as an electron transporting layer. PBD 50 nm, Al-Li alloy (Li: 0.5% by weight) 50 n as an electrode layer
m, sequentially deposited.

Thus, a laminated organic electroluminescent device using 9 (10-methyl) -acridone and 9,9′-bianthryl was prepared. This element has I
When a voltage is applied using the TO electrode as a positive electrode and the Al-Li electrode as a negative electrode, blue light emission is observed at an applied voltage of 4 V or more, and emission luminance is 2610 cd / at an applied voltage of 10 V.
m ² .

Example 12 A glass substrate with an ITO electrode was washed with water, acetone and isopropyl alcohol. Next, a vacuum deposition device (degree of vacuum: 1 × 10 ⁻⁶ To)
rr, substrate temperature: room temperature), TPD was 50 nm as a hole transport layer and 9 (10
-Phenyl) -acridone and 9,9′-bianthryl were simultaneously vapor-deposited (deposition ratio: 9 (10-phenyl) -acridone per molecule, 9,9′-bianthryl 99 molecules) as a 10 nm electron-transporting layer. 50 nm PBD,
As an electrode layer, an Al—Li alloy (Li: 0.5% by weight) was sequentially deposited in a thickness of 50 nm.

Thus, a laminated organic electroluminescent device using 9 (10-methyl) -acridone and 9,9′-bianthryl was prepared. This element has I
When a voltage is applied with the TO electrode as the positive electrode and the Al-Li electrode as the negative electrode, blue light emission is observed at an applied voltage of 4 V or more, and the emission luminance is 2200 cd /
m ² .

Comparative Example 2 A glass substrate with an ITO electrode was washed with water, acetone and isopropyl alcohol. Next, a vacuum deposition device (degree of vacuum: 1 × 10 ⁻⁶ To)
rr, substrate temperature: room temperature), a layer in which TPD was 50 nm as a hole transport layer and acridine and 9,9′-bianthryl were co-deposited as a light emitting layer on the ITO electrode (deposition ratio: 9 per molecule of acridine). , 9'-bianthryl 99 molecule) of 10 nm, and PBD of 50 as an electron transport layer.
An Al-Li alloy (Li: 0.5% by weight) was deposited 50 nm in order as an electrode layer.

Thus, a laminated organic electroluminescent device using acridine and 9,9′-bianthryl was prepared. When a voltage was applied to this device using the ITO electrode as a positive electrode and the Al-Li electrode as a negative electrode, blue light emission was observed at an applied voltage of 8 V or more, and an applied voltage of 10 V
And the emission luminance was 5.3 cd / m ² .

[0088]

As described above, according to the present invention, the luminescent material has the structural formula

[0089]

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9-aminoacridine represented by the structural formula

[0091]

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Since the organic electroluminescent material containing the compound represented by the formula (1) is formed, a light emitting material having a large fluorescence quantum yield can be formed. In addition, since an element is formed using such an organic electroluminescent material, an organic electroluminescent element having a large luminous efficiency can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an example of an organic electroluminescence device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Substrate 12 ... Anode electrode 14 ... Hole transport layer 16 ... Light emitting layer 18 ... Electron transport layer 20 ... Cathode electrode

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Matsuura Higashi 4-1-1, Kamidadanaka, Nakahara-ku, Kawasaki-shi, Kanagawa F-term in Fujitsu Limited (reference) 3K007 AB03 AB06 CA01 CB01 DA00 DB03 EB00 FA01 FA03

Claims (7)

[Claims] 1. A luminescent material having the structural formula: An organic electroluminescent material comprising 9-aminoacridine represented by the following formula: 2. A light-emitting material having the structural formula: An organic electroluminescent material comprising a compound represented by the formula: 3. The organic electroluminescent material according to claim 2, wherein the compound has a structural formula: An organic electroluminescent material, which is 9 (10-methyl) -acridone represented by the following formula: 4. The organic electroluminescent material according to claim 2, wherein the compound has a structural formula: An organic electroluminescent material, which is 9 (10-phenyl) -acridone represented by the following formula: 5. The organic electroluminescent material according to claim 1, wherein the light emitting material has a structural formula: An organic electroluminescent material further comprising 9,9′-bianthryl represented by the following formula: 6. The organic electroluminescent material according to claim 1, wherein the light emitting material has a structural formula: An organic electroluminescent material further comprising a P-quarterphenyl represented by the following formula: 7. An organic layer comprising an organic layer including a light emitting layer made of the organic electroluminescent material according to claim 1; and a pair of electrode layers formed to sandwich the organic layer. An organic electroluminescence device characterized by the following.