JP2001126872A - Organic electroluminescent/element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electroluminescent device including a positive electrode, a negative electrode, and an organic luminescent film between the electrodes, which is easy to manufacture and is stabilized in its characteristic. SOLUTION: The organic electroluminescent device A comprises a positive electrode 2, a negative electrode 4, and an organic luminescent film 3 between the positive electrode 2 and the negative electrode 4. The light emission is performed by applying drive voltage including an alternative component from light emission drive power PW1 between both electrodes (the positive electrode 2 and the negative electrode 3) of an organic electroluminescent device being single layer typed organic luminescent film which is a single layer construction made of a mixture of at least organic luminescent material and organic charge transportation material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an organic electroluminescent device including an anode, a cathode, and an organic light emitting film between the anode and the cathode.

[0002]

2. Description of the Related Art An organic electroluminescent device usually includes an anode, a cathode, and an organic light emitting film between the anode and the cathode.
Light is emitted by applying a voltage between the two electrodes or by flowing a current. In this organic electroluminescent device, there are a case where a low molecular material is used as an organic material used for the organic light emitting film and a case where a high molecular material is used.

[0003]

Generally, in a low molecular weight organic electroluminescent device using a low molecular weight material, the device has a multi-layer structure in which a plurality of layers are laminated, and a function for emitting light from the device is provided. Attempts have been made to achieve higher performance by separating the layers, but the adoption of a multi-layer structure complicates element fabrication.

On the other hand, in a polymer-based organic electroluminescent device using a polymer-based material, simplification of the configuration has been attempted for facilitating the fabrication of the device, but at present, it is necessary for the device to emit light. It is inferior to the low molecular weight organic electroluminescent device in terms of stabilization of device characteristics such as driving voltage (current) and luminous efficiency. Therefore, the present invention provides an organic electroluminescent device including an anode, a cathode, and an organic light-emitting film between the anode and the cathode, in which the device fabrication is simple and easy, and the device characteristics are stabilized. The task is to provide.

[0005]

Means for Solving the Problems The inventor of the present invention has conducted various studies to solve the above-mentioned problems. As a result, at least an organic light-emitting material or an organic light-emitting material is used as an organic electroluminescent device having a simple structure which can be manufactured easily and easily. Attention is paid to an organic electroluminescent device including a single-layer organic light-emitting film having a single-layer structure composed of a mixture of a material and an organic charge transporting material, and a driving voltage including an AC component is applied to the organic electroluminescent device, or a driving current including an AC component is applied thereto. Thus, it has been found that injection or recombination of electrons or holes can be promoted in the single-layer organic light-emitting film, and the light-emitting characteristics of the device are stabilized for a long time.

The present invention is based on this finding,
In order to solve the above problems, the following first and second organic electroluminescent devices are provided. (1) First organic electroluminescent element Including an anode, a cathode, and an organic light emitting film between the anode and the cathode, the organic light emitting film is composed of at least an organic light emitting material or a mixture of an organic light emitting material and an organic charge transport material. An organic electroluminescent element, which is a single-layer organic light-emitting film having a layer structure and emits light by applying a drive voltage including an AC component from a light-emitting drive power supply between the two electrodes. (2) A second organic electroluminescent device comprising an anode, a cathode, and an organic light emitting film between the anode and the cathode, wherein the organic light emitting film is composed of at least an organic light emitting material or a mixture of an organic light emitting material and an organic charge transport material. A single-layer organic light-emitting film having a layer structure, having a buffer layer between the anode and the organic light-emitting film, between the two electrodes,
An organic electroluminescent device, which emits light by applying a drive voltage containing an AC component from a light emission drive power supply.

In the first and second organic electroluminescent devices according to the present invention, the organic light emitting film between the anode and the cathode has a single-layer structure comprising at least an organic light emitting material or a mixture of an organic light emitting material and an organic charge transport material. A single-layer organic light-emitting film,
The second organic electroluminescent device according to the present invention further includes a buffer layer between the anode and the organic light emitting film. In any case, as a light emission driving method, light emission can be driven by applying a drive voltage containing an AC component between the two electrodes from a light emission drive power supply, or flowing a drive current containing an AC component.

According to the first and second organic electroluminescent devices according to the present invention, since the organic light-emitting film is a single-layer organic light-emitting film having a single-layer structure, device fabrication is simple and easy. In addition, since a driving voltage containing an AC component is applied between the two electrodes for driving light emission of the element, or a driving current containing an AC component is passed, injection of electrons or holes in the single-layer organic light-emitting film, Recombination can be promoted, and the light emission characteristics of the element are stabilized for a long time.

Therefore, according to the first and second organic electroluminescent devices of the present invention, device fabrication is simple and easy, and device characteristics are stabilized. The formation of the single-layer organic light-emitting film is not particularly limited as long as the single-layer organic light-emitting film can be formed into a single-layer structure.
When an organic light emitting material and an organic charge transporting material are formed into a single-layered mixed vapor-deposited thin film on a substrate on which electrodes and the like are formed by a co-evaporation method using vacuum evaporation, or when formed by a printing method (for example, an organic light-emitting material) When a single layer ink jet printed thin film is formed on a substrate on which electrodes and the like are formed by an ink jet printing method) or when a mixture of an organic light emitting material and an organic charge transporting material is formed by dip coating. In the case of forming a single-layer coating thin film on a substrate on which electrodes and the like are formed by a method, or in the case of forming using a spacer (for example, a mixture of an organic light emitting material and an organic charge transporting material in which a spacer is dispersed is used. The flexible substrate is placed on the end of the substrate on which the electrodes, etc. are formed, and the flexible substrate is overlaid on the substrate. By, when formed into a coating film of a single layer structure of a thickness determined by the spacer), and the like. In any case, such film formation is simple and easy.

As the organic light-emitting material that can be used for forming the single-layer organic light-emitting film, known materials described later can be used, and a fluorescent dye may be employed. Examples of the organic charge transporting material that can be used for forming the single-layer organic light-emitting film include an organic hole transporting material for facilitating hole injection and transport, an organic hole injection transport material, and electron injection and transport. Organic electron transporting materials, organic electron injecting materials, and the like to facilitate the above.

The organic charge transporting material includes a charge transporting organic polymer material. Therefore, the single-layer organic light-emitting film may be, for example, a film made of a mixture of a charge-transporting organic polymer material and an organic light-emitting material, or a film of a charge-transporting organic polymer material, an organic light-emitting material, and a resin. It may be a film made of a mixture. In any case, the thickness of the single-layer type organic light-emitting film is not limited thereto, but may be 1 nm to 1000 nm.

In the second organic electroluminescent device according to the present invention, the buffer layer may be a layer made of an organic polymer material. Examples of a method for forming the buffer layer include a spin coating method, a dip coating method, and a printing method. The buffer layer is provided for various purposes, for example, to prevent electrons from passing through.

In the first and second organic electroluminescent devices according to the present invention, both the anode and the cathode may be transparent electrodes so that light emission can be seen, or one of them is a transparent electrode. You may. In any case, in the first and second organic electroluminescent devices according to the present invention, the drive voltage or the drive current including the AC component may be obtained by superimposing the AC component and the DC component. That is, a drive voltage in which an AC component and a DC component are superimposed may be applied between the two electrodes, or a drive current in which an AC component and a DC component are superimposed may flow between the two electrodes.

Further, the frequency of the drive voltage or drive current containing the AC component is not limited to the above.
10 Hz to 10 kHz can be exemplified.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 to FIG. 5 are diagrams respectively showing a schematic configuration of an example of an organic electroluminescent device according to the present invention and a state of a light emitting drive power supply for applying a drive voltage thereto. FIG. 6 is a graph of the waveform of the driving voltage applied to the organic electroluminescent device shown in FIGS. 1 and 5, and FIG.
5 is a graph of a waveform of a driving voltage applied to the organic electroluminescent device shown in FIG.

The organic electroluminescent device A shown in FIG. 1 has a transparent substrate 1, made of glass, on which an anode 2, an organic luminescent film 3, and a cathode 4, which are transparent electrodes, are laminated in this order. The organic light-emitting film 3 is a single-layer organic light-emitting film having a single-layer structure made of a mixture of an organic light-emitting material and an organic charge transporting material. It is a mixed vapor deposition thin film formed in a layer. Note that the cathode 4 may be a transparent electrode.

The anode 2 and the cathode 4 are connected to one ends of lead wires 2 'and 4', respectively, and the other ends of the lead wires 2 'and 4' are connected to a light emission drive power source PW1. . The power source PW1 is an AC drive voltage having a predetermined frequency and a predetermined peak voltage (here, frequency 100 Hz, peak voltage ± 8 V) between the anode 2 and the cathode 4 as shown in FIG.
A (peak-to-peak 16 V) AC drive voltage or an AC drive voltage with a frequency of 100 Hz and a peak voltage ± 14 V (peak-to-peak 28 V) can be applied.

The element A has a sealing member (not shown), and the organic light emitting film 3 is covered by the sealing member and is shielded from the outside air. The organic electroluminescent devices B and F shown in FIG. 2 are such that an anode 2 as a transparent electrode, an organic luminescent film 5 and a cathode 4 as a transparent electrode are formed on a transparent substrate 1 made of glass.
The layers are formed in this order. In the organic electroluminescent element B, the organic light-emitting film 5 is a single-layer organic light-emitting film having a single-layer structure made of an organic light-emitting material. In this case, the organic light-emitting material is an ink-jet printed thin film formed in a single layer by an ink-jet printing method. In the organic electroluminescent element F, the organic light-emitting film 5 is a single-layer organic light-emitting film having a single-layer structure composed of a mixed film of an organic light-emitting material, an organic charge-transporting material, and a resin. This is an ink-jet printed thin film formed on the substrate.

The anode 2 and the cathode 4 are connected to one ends of the lead wires 2 'and 4', respectively, and the other ends of the lead wires 2 'and 4' are connected to a light emitting drive power source PW2. . The power supply PW2 is a driving voltage (here, element B) in which a predetermined DC voltage is superimposed on an AC voltage having a predetermined frequency and a predetermined peak voltage between the anode 2 and the cathode 4 as shown in FIG.
Is a driving voltage in which a DC voltage having a voltage value of 6 V is superimposed on an AC voltage having a frequency of 200 Hz and a peak voltage of ± 15 V (peak-to-peak 30 V), and a frequency of 100 Hz and a peak voltage of ± 13 V (peak-to-peak) for the element F. Peak 2
6V) AC voltage with a DC voltage having a voltage value of 5 V superimposed on the AC voltage.

Each of the elements B and F has a sealing member (not shown), and the organic light emitting film 5 is covered by the sealing member and is shielded from the outside air. The organic electroluminescent device C shown in FIG. 3 is one in which an anode 2, an organic light emitting film 6, and a cathode 4, which are transparent electrodes, are laminated on a transparent substrate 1 made of glass in this order. The organic light-emitting film 6 is a single-layer organic light-emitting film having a single-layer structure composed of a mixture of an organic light-emitting material and an organic charge transport material. In this case, a mixture of the organic light-emitting material 7 and the organic hole injecting and transporting material 8 is applied by dip coating. Is a coated thin film formed as a single layer by

The anode 2 and the cathode 4 are connected to one ends of the lead wires 2 'and 4', respectively, and the other ends of the lead wires 2 'and 4' are connected to a light emitting drive power source PW3. . A power supply PW3 is an AC voltage having a predetermined frequency and a predetermined peak voltage (here, frequency 200 Hz, peak voltage ± 10 V) between the anode 2 and the cathode 4 as shown in FIG.
It is possible to apply a drive voltage in which a predetermined DC voltage (here, a DC voltage having a voltage value of 4 V) is superimposed on the AC voltage (20 V peak-to-peak).

The element C has a sealing member (not shown), and the organic light emitting film 6 is covered with the sealing member to be shielded from the outside air. The organic electroluminescent device D shown in FIG. 4 has a transparent substrate 1 made of glass, an anode 2 as a transparent electrode, an organic luminescent film 12, a cathode 4 as a transparent electrode, and a flexible transparent substrate 9 made of polyethersulfone. Are laminated in this order. The organic light-emitting film 12 is a single-layer organic light-emitting film having a single-layer structure made of a mixture of an organic light-emitting material and an organic charge transporting material. Is a coating thin film formed in a single layer with a thickness determined by the spacer 10.

The anode 2 and the cathode 4 are connected to one ends of the lead wires 2 'and 4', respectively, and the other ends of the lead wires 2 'and 4' are connected to a light emitting drive power source PW4. . The power supply PW4 is an AC voltage having a predetermined frequency and a predetermined peak voltage (here, frequency 200 Hz, peak voltage ± 16 V) between the anode 2 and the cathode 4 as shown in FIG.
A driving voltage in which a predetermined DC voltage (here, a DC voltage having a voltage value of 6 V) is superimposed on a (peak-to-peak 32 V AC voltage) can be applied.

The element D has a sealing member (not shown), and the organic light emitting film 12 is covered by the sealing member and is shielded from the outside air. The organic electroluminescent elements E and G shown in FIG. 5 are each formed by laminating an anode 2, a buffer layer 14, an organic luminescent film 3, and a cathode 4 which are transparent electrodes on a transparent substrate 1 made of glass in this order. . The buffer layer 14 is an organic film formed by a coating method. In the organic electroluminescent element E, the organic light-emitting film 3 is a single-layer organic light-emitting film having a single-layer structure composed of a mixture of an organic light-emitting material and an organic charge-transporting material. It is a mixed film formed by the attaching method. Note that the cathode 4 of the element E may be a transparent electrode. In the organic electroluminescent element G, the organic light-emitting film 3 is a single-layer organic light-emitting film having a single-layer structure including a mixed film of an organic light-emitting material, an organic charge-transport material, and a resin. This is a mixed film formed by dip coating with resin mixed.

The anode 2 and the cathode 4 are connected to one ends of the lead wires 2 'and 4', respectively, and the other ends of the lead wires 2 'and 4' are connected to the light emitting drive power supply PW1. . The power supply PW1 is an AC voltage having a predetermined frequency and a predetermined peak voltage as shown in FIG. 6 between the anode 2 and the cathode 4 (here, a frequency of 200 Hz, a peak voltage ± 15 V (30 V peak-to-peak) for the element E). And an AC driving voltage of 150 Hz and a peak voltage of ± 16 V (32 V peak-to-peak) can be applied to the element G.

Each of the elements E and G has a sealing member (not shown), and the organic light emitting film 3 is covered by the sealing member and is shielded from the outside air. In the devices A, E and G shown in FIGS. 1 and 5, the light emitting drive power source P is connected between the anode 2 and the cathode 4.
Light emission can be driven by applying an AC drive voltage from W1. Further, the elements B, F, C, D shown in FIGS.
Then, between the anode 2 and the cathode 4, the light emission drive power supplies PW2, PW2
3, light emission can be driven by applying a drive voltage in which a DC voltage is superimposed on an AC voltage from the PW4.

The organic electroluminescent device A shown in FIGS.
According to B, C, D, E, F, and G, the organic light emitting films 3, 5,
Since elements 6 and 12 are single-layer organic light-emitting films having a single-layer structure, element fabrication is simple and easy. In addition, for driving light emission of the element, light emission drive power supplies PW1 and PW1 are connected between the anode 2 and the cathode 4.
2. Since a drive voltage including an AC component is applied from PW3 and PW4, injection or recombination of electrons or holes can be promoted in the single-layer organic light-emitting films 3, 5, 6, and 12, and the light-emitting characteristics of the device can be improved. Stabilizes for a long time.

Therefore, the elements A, B, C, D, E, F, G
According to the method, the device can be easily and easily manufactured, and the device characteristics are stabilized. Here, “apply an AC drive voltage” is applied to the elements A, E, and G, and “apply a drive voltage obtained by superimposing a DC voltage on an AC voltage” is applied to the elements B, C, D, and F.
However, the same applies to the case where “the AC drive current is applied” to the elements A, E, and G, and “the drive current obtained by superimposing the DC current on the AC current” is applied to the elements B, C, D, and F. It is.

The transparent substrate 1 can be used not only for the organic electroluminescent devices shown in FIGS. 1 to 5, but also for the first and second organic electroluminescent devices of the present invention. The transparent substrate has an appropriate strength, is not particularly limited as long as it is transparent, without being adversely affected by heat at the time of manufacturing an organic electroluminescent device, at the time of film deposition, and the like. In addition to the glass substrate, transparent resins such as polyethylene, polypropylene, polyether sulfone, polyether ether ketone, polyethylene terephthalate, polycarbonate, and polyarylate can be used.

Although the anode 2 of the organic electroluminescent device shown in FIGS. 1 to 5 is a transparent electrode, the anode of the first and second organic electroluminescent devices of the present invention is generally transparent. It is recommended to use conductive materials, especially 4 eV
It is preferable to use a conductive substance having a work function larger than the degree. As an anode made of such a substance, aluminum, vanadium, iron, cobalt, nickel, copper, zinc, tungsten, silver, tin, gold and the like, in addition to a light-transmitting thin film electrode of a metal such as an alloy containing them, tin oxide, Examples of the electrode include transparent conductive metal oxides such as indium oxide, antimony oxide, zinc oxide, and zirconium oxide, and electrodes formed of a conductive compound such as a transparent conductive metal compound such as a solid solution or a mixture thereof.

When the anode is formed, any one of the above-described conductive materials is used on the substrate, and a method such as vacuum evaporation or sputtering, a sol-gel method, or a method in which such a material is dispersed in a resin or the like is used. What is necessary is just to form so that desired translucency and electroconductivity may be ensured using means, such as application | coating. The thickness of the anode is 1 in the case of metal in order to obtain translucency.
It is preferably about 30 nm to 30 nm, and in the case of a conductive metal compound, about 1 nm to 300 nm is preferable.

In forming a transparent electrode on a glass substrate, a transparent conductive film made of indium tin oxide (ITO) is provided on a glass substrate, and a transparent conductive film made by Corning Corporation, commonly called NESA glass. May be used on a glass substrate. Among the organic charge transporting materials that can be used for forming the single-layer organic light-emitting films of the first and second organic electroluminescent devices of the present invention, including the single-layer organic light-emitting films 3, 5, 6, and 12, As the hole transporting material or the organic hole injecting and transporting material, known materials can be used.

For example, N, N'-diphenyl-N, N'-
Bis (3-methylphenyl) -1,1'-diphenyl-
4,4'-diamine, N, N'-diphenyl-N, N '
-Bis (4-methylphenyl) -1,1'-diphenyl-4,4'-diamine, N, N'-diphenyl-N,
N'-bis (1-naphthyl) -1,1'-diphenyl-
4,4'-diamine, N, N'-diphenyl-N, N '
-Bis (2-naphthyl) -1,1'-diphenyl-4,
4'-diamine, N, N'-tetra (4-methylphenyl) -1,1'-bis (3-methylphenyl) -4
4'-diamine, N, N'-diphenyl-N, N'-bis (3-methylphenyl) -1,1'-bis (3-methylphenyl) -4,4'-diamine, N, N'- Bis (N-carbazolyl) -1,1′-diphenyl-4
4'-diamine, 4,4 ', 4 "-tris (N-carbazolyl) triphenylamine, N, N', N" -triphenyl-N, N ', N "-tris (3-methylphenyl)- 1,3,5-tri (4-aminophenyl) benzene, 4,4 ', 4 "-tris [N, N', N" -triphenyl-N, N ', N "-tris (3-methylphenyl )] Triphenylamine and the like.
Further, a charge transporting organic polymer such as polyvinyl carbazole, polyvinyl indole, polyvinyl pyrene, polyvinyl anthracene, polyvinyl triphenylamine, polycarbonate containing triphenylamine unit, polyarylate, polyether sulfone, or the like may be used. These may be used as a mixture of two or more.

The organic light-emitting materials that can be used for forming the single-layer organic light-emitting films of the first and second organic electroluminescent devices of the present invention, including the single-layer organic light-emitting films 3, 5, 6, and 12, are as follows. And known ones can be used. For example, epidolidine, 2,5-bis [5,7-di-t-pentyl-2-benzoxazolyl] thiophene, 2,2 ′-(1,4-
Phenylenedivinylene) bisbenzothiazole, 2,
2 '-(4,4'-biphenylene) bisbenzothiazole, 5-methyl-2- {2- [4- (5-methyl-2-
Benzoxazolyl) phenyl] vinyl} benzoxazole, 2,5-bis (5-methyl-2-benzoxazolyl) thiophene, anthracene, naphthalene, phenanthrene, pyrene, chrysene, perylene, perinone,
1,4-diphenylbutadiene, tetraphenylbutadiene, coumarin, acridine, stilbene, 2- (4-
Biphenyl) -6-phenylbenzoxazole, aluminum trisoxine, magnesium bisoxin,
Bis (benzo-8-quinolinol) zinc, bis (2-methyl-8-quinolinol) aluminum oxide, indium trisoxin, aluminum tris (5-methyloxin), lithium oxine, gallium trisoxin, calcium bis (5-chlorooxin) ), Polyzinc-bis (8-hydroxy-5-quinolinolyl) methane, dilithium epindridione, zinc bisoxin,
1,2-phthaloperinone, 1,2-naphthaloperinone,
Tris (8-hydroxyquinoline) aluminum complex,
Poly-2,5-nonyloxy-p-phenylenevinylene and the like can be mentioned. In addition, general fluorescent dyes such as fluorescent coumarin dyes, fluorescent perylene dyes, fluorescent pyran dyes, fluorescent thiopyran dyes, fluorescent polymethine dyes, fluorescent mecyanine dyes, fluorescent imidazole dyes and the like can also be used. Among them, particularly preferred are chelated oxinoid compounds. Note that a light-emitting substance (for example, a fluorescent dye such as rubrene or coumarin) doped with two or more light-emitting substances may be used.

The organic charge transporting materials that can be used for forming the single-layer organic light-emitting films of the first and second organic electroluminescent devices of the present invention, including the single-layer organic light-emitting films 3, 5, 6, and 12 As the organic electron transporting material, known materials can be used. For example, 2- (4-biphenylyl) -5-
(4-tert-butylphenyl) -1,3,4-oxadiazole, 2- (1-naphthyl) -5- (4-te
rt-butylphenyl) -1,3,4-oxadiazole, 1,4-bis {2- [5- (4-tert-butylphenyl) -1,3,4-oxadiazolyl]} benzene, 1,3 -Bis {2- [5- (4-tert-butylphenyl) -1,3,4-oxadiazolyl]} benzene, 4,4'-bis} 2- [5- (4-tert-butylphenyl) -1 , 3,4-oxadiazolyl] biphenyl, 2- (4-biphenylyl) -5- (4-te
rt-butylphenyl) -1,3,4-thiadiazole, 2- (1-naphthyl) -5- (4-tert-butylphenyl) -1,3,4-thiadiazole, 1,4-
Bis @ 2- [5- (4-tert-butylphenyl)-
1,3,4-thiadiazolyl] {benzene, 1,3-bis} 2- [5- (4-tert-butylphenyl)-
1,3,4-thiadiazolyl]｝ benzene, 4,4'-
Bis @ 2- [5- (4-tert-butylphenyl)-
1,3,4-thiadiazolyl]｝ biphenyl, 3- (4
-Biphenylyl) -4-phenyl-5- (4-ter
t-butylphenyl) -1,2,4-triazole, 3
-(1-Naphthyl) -4-phenyl-5- (4-ter
t-butylphenyl) -1,2,4-triazole,
1,4-bis @ 3- [4-phenyl-5- (4-ter
t-butylphenyl) -1,2,4-triazolyl]｝
Benzene, 1,3-bis @ 2- [1-phenyl-5-
(4-tert-butylphenyl) -1,3,4-triazolyl] {benzene, 4,4′-bis} 2- [1-phenyl-5- (4-tert-butylphenyl) -1,
3,4-Triazolyl] {biphenyl, 1,3,5-tris} 2- [5- (4-tert-butylphenyl)-
[1,3,4-oxadiazolyl]} benzene. These may be used as a mixture of two or more.

Among the organic charge transporting materials, examples of the organic electron injecting material include an organic metal complex of an alkali metal or an alkaline earth metal, an organic metal salt of an alkali metal or an alkaline earth metal, an alkali metal or an alkaline earth metal. A mixed film with an organic metal complex or an oxide or halide of an alkali metal or an alkaline earth metal can be exemplified. In the first and second organic electroluminescent devices of the present invention, when the single-layer organic light-emitting film is formed, a resin having a film-forming property by itself is provided to the light-emitting film so that the film can be easily formed. They may be mixed so that they can be produced. In this case, as a resin added to the light emitting film, for example, a general thermoplastic resin such as polysterene, polyacrylate, polycarbonate, polyester, or polyarylate is preferably used. Further, a resin for paint may be used.

In the second organic electroluminescent device of the present invention having a buffer layer between the single-layer organic light emitting film and the anode, a material usable for the buffer layer is, for example, phthalocyanine Examples include compounds, indanthrene compounds, polyaniline, polythiophene, polyethylene dioxythiophene, polyindole, polyfuran, and polyethylene dioxythiophene / polystyrene sulfonate compounds. In particular, when the single-layer type luminescent film is formed by a printing method, a polymer material that can form the buffer layer by a printing method is preferable.

In the first and second organic electroluminescent devices of the present invention, the method of forming the single-layer organic light-emitting film includes, for example, a method of forming the charge transport material and the light-emitting material by co-evaporation, and a method of forming a solvent. And a method of dissolving and applying the same. When applying by dissolving in a solvent, the resin may be mixed as described above. That is, an organic light-emitting film is made to have a film forming property by using a resin having a film forming property by itself,
They may be mixed so that they can be easily produced. Further, as the application method, various application methods such as an inkjet method, a roll coater method, a blade coater method, a spin coater method, a dip coating method, and a gravure printing method can be adopted.

The material for forming the cathode in the device according to the present invention, including the cathode 4, is preferably a material containing a metal having a work function smaller than 4 eV, such as magnesium,
Examples include calcium, titanium, yttrium, lithium, gadolinium, ytterbium, ruthenium, manganese, and alloys containing them. In the case of forming a cathode, these materials may be formed by a method such as vacuum evaporation and sputtering.

The thickness of the cathode is preferably about 10 nm to 500 nm from the viewpoints of conductivity and production stability. Also,
A translucent conductive material can be used for the cathode. In this case, it is preferable to use a conductive substance having a work function smaller than about 4 eV as the light-transmitting conductive substance. Examples of such materials include translucent thin films of metals such as magnesium, calcium, titanium, yttrium, lithium, gadolinium, ytterbium, ruthenium, manganese, and alloys containing them, as well as tin oxide, indium oxide, antimony oxide, and zinc oxide. And a conductive compound such as a transparent conductive metal compound such as a transparent conductive metal oxide such as zirconium oxide and a solid solution or a mixture thereof.

When the cathode is formed using a light-transmitting conductive material, any one of the above-described conductive materials is used, and a method such as vacuum evaporation or sputtering, a sol-gel method, or the like is used. What is necessary is just to form it so that desired translucency and electroconductivity may be ensured using means, such as dispersing and apply | coating in resin etc .. The thickness of the cathode using a light-transmitting conductive material is 0.1 nm to 3 nm in the case of metal in order to obtain light-transmitting properties.
It is preferably about 0 nm, and 1 in the case of a conductive metal compound.
about 300 nm is preferable.

Hereinafter, embodiments of the present invention will be described together with a manufacturing method thereof. In Example 1 or Example 4, the organic electroluminescent element A shown in FIG. 1 was used, in Example 2, the organic electroluminescent element B shown in FIG. 2 was used, and in Example 3, the organic electroluminescent element C shown in FIG. In Example 5, the organic electroluminescent device D shown in FIG. 4 was used. In Example 6, the organic electroluminescent device E shown in FIG.
In Example 7, the organic electroluminescent element F shown in FIG. 2 was manufactured, and in the practical example 8, the organic electroluminescent element G shown in FIG. 5 was manufactured, and the light emission luminance and the light emission state were evaluated. (Example 1) The organic electroluminescent device A shown in FIG. 1 was manufactured as follows.

That is, a commercially available glass substrate (manufactured by Nippon Sheet Glass) coated with an ITO (indium tin oxide) film 1
The ITO film was patterned by etching so that the upper ITO film had a width of 2 mm, and a transparent electrode anode 2 was formed on a glass substrate 1. The substrate 1 after this patterning was subjected to ultrasonic cleaning with a surfactant aqueous solution for 15 minutes, and the substrate 1 was irradiated with light of an excimer lamp having a wavelength of 172 nm for 5 minutes, and then its surface was cleaned with oxygen plasma for 10 minutes.

On the thus washed ITO substrate 1, N, N′-diphenyl-N, N ′ was formed as a single-layer organic light emitting film 3.
-Co-deposition of organic hole injection / transport material of bis (3-methylphenyl) -1,1'-diphenyl-4,4'-diamine and organic light emitting material of tris (8-hydroxyquinoline) aluminum complex by vacuum deposition The vapor deposition rate is controlled to 1Å / sec, and the volume ratio of the organic hole injecting / transporting material to the organic luminescent material is about 1: 1 by vacuum deposition to form a mixed vapor deposition thin film having a thickness of 60 nm. did.

Next, as the cathode 4, magnesium and silver were controlled to a deposition rate ratio of 10: 1 (magnesium: silver) by co-evaporation of resistance heating, and a 200 nm-thick film was formed using a film-forming mask having a width of 2 mm in the opening. A thin film was formed such that The device manufactured as described above is evacuated in advance, brought into a glove box purged with nitrogen, a pre-cleaned sealing glass substrate (not shown) is placed on the device, and the device is illustrated so as to cover a gap around the device. The omitted ultraviolet curable resin was applied, and then the ultraviolet curable resin was irradiated with UV (ultraviolet light) for 200 seconds to cure the resin, thereby producing an organic electroluminescent device A.

The device A thus obtained was supplied with a frequency of 100 Hz and a peak voltage of ± 8 V from the light-emitting drive power source PW1.
By continuously applying an AC (peak-to-peak) driving voltage of 16 V and causing the element A to emit light, the light emission luminance and the light emission state were evaluated.
Even after the lapse of 00 hours, the decrease in the emission luminance with respect to the initial luminance was very small, and no change in the emission state was observed. (Example 2) The organic electroluminescent device B shown in FIG. 2 was manufactured as follows.

That is, in the same manner as in Example 1, a commercially available glass substrate coated with an ITO film (manufactured by Nippon Sheet Glass) 1
The upper ITO film was patterned, and the substrate 1 after the patterning was washed. An organic light-emitting material, poly-2,5-nonyloxy-p, is formed thereon as a single-layer organic light-emitting film 5.
-A phenylenevinylene tetrahydrofuran solution was printed in a predetermined pattern by an inkjet printing method to form a 50 nm-thick single-layer thin film pattern.

Next, a thin film of ITO was formed as the transparent electrode cathode 4 by sputtering using a helical cathode target to a thickness of 150 nm. At this time, an ITO target having a composition ratio of indium oxide to tin oxide of 95 wt%: 5 wt% was used.
The device manufactured as described above was sealed in the same manner as in Example 1, and an organic electroluminescent device B was manufactured.

The device B thus obtained was supplied with a frequency of 200 Hz and a peak voltage of ± 15 V from the light emission drive power source PW2.
By applying a driving voltage obtained by superimposing a DC voltage having a voltage value of 6 V on an AC voltage having a peak-to-peak voltage of 30 V to continuously emit light from the element B, the light emission luminance and the light emission state were evaluated. Even after the elapse of 500 hours from the start, the decrease in the light emission luminance relative to the initial luminance was very small, and no change in the light emission state was observed. Example 3 The organic electroluminescent device C shown in FIG. 3 was manufactured as follows.

That is, the transparent glass substrate 1 previously cleaned
Indium-tin oxide was vacuum-deposited thereon to form a transparent electrode anode 2. Next, polyvinyl carbazole as an organic hole injecting / transporting material and tris (8-hydroxyquinoline) aluminum complex as an organic light emitting material are mixed, and a monolayer type organic light emitting film 6 is formed on the substrate 1 on which the anode 2 is formed.
The mixture was applied by a dip coating method using dichloromethane as a solvent to form a single-layer thin film having a thickness of 50 nm.

Subsequently, a thin film of the cathode 4 made of magnesium and silver was formed in the same manner as in Example 1, and the device was sealed. Thus, an organic electroluminescent device C was manufactured. The device C thus obtained is supplied with a frequency of 200H from the light emission drive power source PW3.
z, a driving voltage in which a DC voltage of 4 V was superimposed on an AC voltage having a peak voltage of ± 10 V (peak-to-peak 20 V) was applied to continuously emit light from the element C, and the light emission luminance and light emission state were evaluated. However, even after a lapse of 500 hours from the start of the application of the driving voltage, the decrease in the light emission luminance relative to the initial luminance was very small, and no change in the light emission state was observed. Example 4 The organic electroluminescent device A shown in FIG. 1 was manufactured as follows.

That is, in the same manner as in Example 1, a commercially available glass substrate coated with an ITO film (manufactured by Nippon Sheet Glass) 1
After patterning the above ITO film and cleaning the substrate 1 after the patterning, the single-layer type organic light emitting film 3 is formed thereon.
And N, N'-diphenyl-N, N'-bis (3-methylphenyl) -1,1'-diphenyl-4,4'-diamine as an organic hole injecting and transporting material and tris (8-hydroxyquinoline) aluminum The organic light-emitting material of the complex was vacuum-deposited by the co-evaporation method under the same conditions as in Example 1 to form a single-layer mixed vapor-deposited thin film.

Next, as the cathode 4 of the transparent electrode, a thin film of 3 nm was formed by co-evaporation of magnesium and silver by resistance heating. On top of that, ITO was sputtered by sputtering using a helical cathode target.
A thin film was formed to a thickness of nm. At this time, ITO
A target having a composition ratio of indium oxide to tin oxide of 95 wt%: 5 wt% was used.

The device manufactured as described above was sealed in the same manner as in Example 1 to obtain an organic electroluminescent device A. The device A obtained in this manner is provided with a light emission drive power source PW
The device A was caused to emit light by continuously applying an AC drive voltage having a frequency of 1 to 100 Hz and a peak voltage of ± 14 V (peak-to-peak 28 V), and the light emission luminance and light emission state were evaluated. Even after elapse of 500 hours from the start, the decrease in the light emission luminance with respect to the initial luminance was very small, and no change in the light emission state was observed. Example 5 An organic electroluminescent device D shown in FIG. 4 was manufactured as follows. That is, similarly to the first embodiment,
The ITO film on a commercially available glass substrate (manufactured by Nippon Sheet Glass Co., Ltd.) 1 coated with an ITO film was patterned, and the substrate 1 after the patterning was washed.

Next, polyvinyl carbazole as an organic hole injecting / transporting material and tris (8-
A hydroxyquinoline) aluminum complex was mixed and dissolved in dichloromethane in which silicate glass powder having a diameter of 0.1 μm was dispersed as a spacer 10 in advance to prepare a solution 11. FIG. 8 shows a part of the manufacturing process of the organic electroluminescent device shown in FIG.

As shown in FIG. 8, a suitable amount of this solution 11 is placed on the end of the glass substrate 1 on which the anode 2 has been formed, and a flexible film made of polycarbonate on which an ITO film has been previously formed as the cathode 4 of the transparent electrode. Pressure-sensitive member 13 that is superposed on transparent transparent substrate 9 and moves relative to substrates 1 and 9
An organic thin film having a single-layer structure with a thickness of 100 nm determined by the spacers 10 was formed by applying the pressure to the substrate 1 while applying pressure (here, a rubber roller made of silicon). Thus, a single-layer organic light-emitting film 12 was formed between the glass substrate 1 on which the anode 2 was formed and the flexible transparent substrate 9 on which the cathode 4 was formed.

Subsequently, the device was sealed in the same manner as in Example 1 to produce an organic electroluminescent device D. The device D obtained in this manner is supplied with a light emitting drive power source PW4 at a frequency of 20.
0 Hz, peak voltage ± 16 V (peak-to-peak 32
By applying a drive voltage obtained by superimposing a DC voltage having a voltage value of 6 V on the AC voltage V) and continuously emitting light from the element D, the light emission luminance and the light emission state were evaluated. , A good light emitting state was maintained even after 500 hours from the start of application of. (Example 6) The organic electroluminescent device E shown in FIG. 5 was manufactured as follows.

That is, in the same manner as in Example 1, a commercially available glass substrate coated with an ITO film (manufactured by Nippon Sheet Glass)
The upper ITO film was patterned, and the substrate 1 after the patterning was washed. Next, as the buffer layer 14,
An aqueous dispersion of a polyethylene dioxythiophene / polystyrene sulfonate compound (manufactured by Bayer: Baytron P) was applied on an ITO substrate by spin coating to a dry film thickness of 50 nm, and then dried.

As a single-layer organic light emitting film 3, polyvinyl carbazole as an organic hole injecting / transporting material and coumarin 6 as a light emitting material are dissolved in dichloromethane, and a thin film having a thickness of 60 nm is formed by a bar coater. Formed. Next, silver and magnesium were deposited as the cathode 4 by co-evaporation of resistance heating at an evaporation rate ratio of 10: 1 (magnesium:
(Silver) and a thin film was formed to a thickness of 200 nm.

The device manufactured as described above is evacuated in advance and brought into a nitrogen-purged glove box, and a pre-washed sealing glass substrate (not shown) is placed on the device and covers the peripheral gap. An ultraviolet curable resin (not shown) was applied as described above, and then the ultraviolet curable resin was irradiated with ultraviolet rays for 200 seconds to cure the resin, thereby producing an organic electroluminescent element E.

The device E thus obtained was supplied with a frequency of 200 Hz and a peak voltage of ± 15 V from the light-emitting drive power source PW1.
By continuously applying an AC (peak-to-peak) driving voltage of 30 V and causing the element E to emit light, the light emission luminance and the light emitting state were evaluated. No decrease in light emission luminance relative to the luminance was observed, and the light emission state was good. (Example 7) The organic electroluminescent device F shown in FIG. 2 was manufactured as follows.

That is, in the same manner as in Example 1, a commercially available ITO-coated glass substrate (Nippon Sheet Glass) 1
The upper ITO film was patterned, and the substrate 1 after the patterning was washed. Next, 90 parts of polyvinyl triphenylamine as an organic hole injecting and transporting material and coumarin 6 as a luminescent material were added as a single layer type organic luminescent film 5 thereon.
Parts, 0.5 parts of a fluorescent dye DCM, and 10 parts of a polycarbonate resin were dissolved in dichloromethane, and a thin film having a thickness of 60 nm was formed by an inkjet method.

Next, as the cathode 4, silver and magnesium were controlled by co-evaporation with resistance heating so that the evaporation rate ratio was 10: 1 (magnesium: silver), and a thin film was formed to have a thickness of 200 nm. The device manufactured as described above is evacuated in advance, brought into a glove box purged with nitrogen, and a pre-cleaned sealing glass substrate (not shown) is placed on the device and is illustrated so as to cover a gap around the device. Was applied, and then the ultraviolet curable resin was irradiated with ultraviolet light for 200 seconds to cure the resin, thereby producing an organic electroluminescent element F.

The device F thus obtained was supplied with a frequency of 100 Hz and a peak voltage of ± 13 V from the light emitting drive power supply PW2.
(Peak-to-Peak 26V) AC voltage is superimposed with a DC voltage having a voltage value of 5V continuously, and a driving voltage is continuously applied.
The light emission luminance and the light emission state were evaluated by causing the light emission. As a result, no decrease in the light emission luminance relative to the initial luminance was observed even after 500 hours from the start of the application of the driving voltage, and the light emission state was good. Example 8 An organic electroluminescent device G shown in FIG. 5 was manufactured as follows.

That is, in the same manner as in Example 1, an ITO film on a commercially available ITO film-coated glass substrate (manufactured by Nippon Sheet Glass) 1 was patterned, and the substrate 1 after the patterning was washed. Next, as a buffer layer 14, a THF (tetrahydrofuran) solution of bis (tetrafluoropropoxy) silicon-tetra (2,2 ', 2 ", 2"'-hexafluoroneopentyl) -phthalocyanine compound is dip-coated on the ITO substrate. It was applied by a method so as to have a dry film thickness of 30 nm, and then dried.

A single-layer organic light-emitting film 3 was formed thereon, and polyvinyl carbazole 10 as an organic hole injecting and transporting material was used.
0 parts, 1.5 parts of coumarin 6 as a light emitting material and a polystyrene resin were dissolved in dichloromethane, and a thin film was formed to have a thickness of 70 nm by dip coating. Next, as a cathode 4, silver and magnesium are co-deposited by resistance heating to have a deposition rate ratio of 10: 1 (magnesium: silver).
And a thin film was formed to have a thickness of 200 nm.

The device manufactured as described above is evacuated in advance and brought into a glove box purged with nitrogen. A pre-cleaned sealing glass substrate (not shown) is placed on the device, and the peripheral gap is covered. An ultraviolet curable resin (not shown) was applied as described above, and then the ultraviolet curable resin was irradiated with ultraviolet rays for 200 seconds to cure the resin, thereby producing an organic electroluminescent element E.

The device E thus obtained was supplied with a frequency of 150 Hz and a peak voltage of ± 16 V from the light-emitting drive power source PWl.
By continuously applying an AC (32 V peak-to-peak) drive voltage and causing the element G to emit light, its light emission luminance and light emission state were evaluated. The initial value was obtained even after 500 hours from the start of the drive voltage application. No decrease in light emission luminance relative to the luminance was observed, and the light emission state was good.

The organic electroluminescent device of the present invention achieves simplification of device production, stabilization of device light-emitting characteristics and long life, and a luminescent material, a luminescent auxiliary material, and a charge transport material used together. However, the present invention is not limited to a resin, an electrode material, and the like and an element manufacturing method.

[0070]

As described above, according to the present invention, there is provided an organic electroluminescent device including an anode, a cathode, and an organic light emitting film between the anode and the cathode, wherein the organic light emitting film has a single layer structure. It is possible to provide an organic electroluminescent device which is a light-emitting film, whose device is simple and easy to manufacture, and whose light-emitting characteristics are stabilized by applying a driving voltage including an AC component to both electrodes.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an example of an organic electroluminescent device according to the present invention and a state of a light emitting drive power supply for applying a drive voltage thereto.

FIG. 2 is a diagram showing a schematic configuration of another example of the organic electroluminescent device according to the present invention and a state of a light emitting drive power supply for applying a drive voltage thereto.

FIG. 3 is a diagram showing a schematic configuration of still another example of the organic electroluminescent device according to the present invention and a state of a light emitting drive power supply for applying a drive voltage thereto.

FIG. 4 is a diagram showing a schematic configuration of still another example of the organic electroluminescence device according to the present invention and a state of a light emission drive power supply for applying a drive voltage thereto.

FIG. 5 is a diagram showing a schematic configuration of still another example of the organic electroluminescent device according to the present invention and a state of a light emitting drive power supply for applying a drive voltage thereto.

FIG. 6 is a graph of a driving voltage waveform applied to the organic electroluminescent device shown in FIGS. 1 and 5;

FIG. 7 is a graph of a drive voltage waveform applied to the organic electroluminescent device shown in FIGS. 2 to 4;

FIG. 8 is a view showing a part of the manufacturing process of the organic electroluminescent device shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Anode 2 'Lead wire 3, 5, 6, 12 Single layer type organic light emitting film 4 Cathode 4' Lead wire 7 Organic light emitting material 8 Organic hole injection transport material 9 Flexible transparent substrate 10 Spacer 11 Spacer Mixed solution of dispersed organic hole injecting and transporting material and organic light emitting material 13 Pressurizing member 14 Buffer layer A, B, C, D, E, F, G Organic electroluminescent element PW1, PW2, PW3, PW4 Light emitting drive power supply

Continued on the front page (72) Inventor Keiichi Furukawa 2-13-13 Azuchicho, Chuo-ku, Osaka-shi Osaka International Building Minolta Co., Ltd. F-term (reference) 3K007 AB11 AB18 CA01 CB01 DA02 EB00 GA02

Claims (11)

[Claims] 1. A single layer having a single-layer structure comprising an anode, a cathode, and an organic light-emitting film between the anode and the cathode, wherein the organic light-emitting film comprises at least an organic light-emitting material or a mixture of an organic light-emitting material and an organic charge transport material. An organic electroluminescent element, wherein the organic electroluminescent element is a type organic light-emitting film, and emits light by applying a drive voltage containing an AC component from a light-emission drive power supply between the two electrodes. 2. A single layer having a single-layer structure including an anode, a cathode, and an organic light-emitting film between the anode and the cathode, wherein the organic light-emitting film comprises at least an organic light-emitting material or a mixture of an organic light-emitting material and an organic charge transport material. Type organic light-emitting film, which has a buffer layer between the anode and the organic light-emitting film, and emits light by applying a drive voltage containing an AC component from a light-emission drive power supply between the two electrodes. Characteristic organic electroluminescent device. 3. The organic electroluminescent device according to claim 1, wherein both the anode and the cathode are transparent electrodes. 4. The organic electroluminescent device according to claim 2, wherein said buffer layer is a layer made of an organic polymer material. 5. The organic electroluminescent device according to claim 1, wherein said single-layer organic light-emitting film is a film made of a mixture of a charge transporting organic polymer material and an organic light-emitting material. 6. The organic electroluminescent device according to claim 1, wherein the single-layer organic light-emitting film is a film made of a mixture of a charge-transporting organic polymer material, an organic light-emitting material, and a resin. 7. The organic electroluminescent device according to claim 1, wherein the single-layer organic light-emitting film is a film formed by a printing method. 8. The organic electroluminescent device according to claim 1, wherein said organic light emitting material is a fluorescent dye. 9. The organic electroluminescent device according to claim 1, further comprising a substrate, wherein the anode is formed on the substrate, and the substrate is a substrate made of glass or resin. 10. The organic electroluminescent device according to claim 2, wherein said buffer layer is a layer formed by a printing method. 11. The organic electroluminescent device according to claim 1, wherein the drive voltage including the AC component is obtained by superimposing an AC component and a DC component.