JP2001284059A - Transparent electrode, organic electroluminescence element, transparent electrode processing apparatus, and transparent electrode processing method - Google Patents

Abstract

(57) Abstract: Provided is a transparent electrode having an improved work function and a transparent electrode processing apparatus having an improved work function on the surface of the transparent electrode. SOLUTION: This invention provides a transparent electrode comprising a transparent substrate and a transparent conductive film provided on the transparent substrate, wherein the transparent conductive film is exposed to a gas containing active oxygen. In addition, a plasma generating apparatus that generates plasma in a first gas containing oxygen to generate a second gas containing active oxygen,
Gas is supplied from the outside to the inside of the plasma generator, and a processing tank to which a second gas is supplied from the plasma generator is provided. The processing tank is formed of a transparent substrate and a transparent conductive film provided on the transparent substrate. A transparent electrode processing apparatus is provided in which a transparent electrode is disposed and which performs an active oxygen treatment on the transparent electrode using the second gas supplied from the plasma generator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent electrode, a transparent electrode processing apparatus, a method for processing a transparent electrode, and an organic electroluminescent device using the same. More specifically, the present invention relates to a transparent electrode having an improved work function on the surface, The present invention relates to a transparent electrode processing apparatus and a transparent electrode processing method for improving a work function of a transparent electrode surface, and an organic electroluminescence element using the transparent electrode.

[0002]

2. Description of the Related Art At present, an organic electroluminescence element has been receiving attention. Organic electroluminescent elements emit surface light, emit light with high luminance even at a low applied voltage, can be made thinner and lighter, have high manufacturability of large-area light-emitting elements, and have a wide variety of light-emitting materials. Can be combined and used, so that full color display is highly feasible.

[0003] Organic electroluminescent elements are used as direction indicators for automobiles and bicycles, tail lamps, displays such as personal computers and family computers, backlights for liquid crystal display devices, light emitting elements for toys, and night indicator lights for road construction. It is expected to be used for

In an organic electroluminescence device,
Emitting light with high brightness for practical use in the above applications,
In addition, there is a demand for driving with a low applied voltage.

Conventionally, a single-layer organic electroluminescent device having a structure of anode / light-emitting layer / cathode has been known as an organic electroluminescent device. This organic electroluminescent element emits light according to the following principle. Electrons are injected into the light emitting layer from the cathode. Holes are injected into the light emitting layer from the anode. When the injected electrons and holes recombine in the light emitting layer, the organic electroluminescent element emits light.

In addition, organic electroluminescent devices having various structures have been developed. For example, anode /
An organic electroluminescent element having a multilayer laminated structure composed of a hole transport layer / a light emitting layer / an electron transport layer / a cathode is exemplified. Here, each layer of the hole transport layer / light emitting layer / electron transport layer is formed as a thin film.

[0007] The hole transport layer is a layer for transporting holes injected from the anode to the light emitting layer. The electron transport layer is a layer for transporting electrons injected from the cathode to the light emitting layer. The light emitting layer is provided between the hole transport layer and the electron transport layer. The luminescent layer contains a luminescent agent, and the luminescent layer has the luminescent agent dispersed in a low-molecular or high-molecular compound. This luminescent agent is preferably made of a fluorescent substance, and in particular, is preferably composed of a single fluorescent substance having high emission quantum efficiency. The luminescent material is arbitrarily selected from a dye for a dye laser, a fluorescent whitening agent, or a fluorescent substance that emits fluorescence when irradiated with ultraviolet light.

[0008] In addition, an organic electroluminescent device having a multilayer laminated structure and including at least one of a hole blocking layer, an electron injection layer, and a hole injection layer has been conventionally known.

Japanese Patent Application Laid-Open No. 3-137186 discloses an organic electroluminescent device having a multilayer laminated structure comprising an anode / a hole injection / transport layer / a light emitting layer / a hole blocking layer / a cathode. The hole blocking layer is provided between the light emitting layer and the cathode. When the organic electroluminescence element does not include the hole blocking layer, holes that do not contribute to light emission in the light emitting layer pass through the light emitting layer to reach the cathode. The hole blocking layer traps holes that do not contribute to light emission in the light emitting layer. As a result, the organic electroluminescence element including the hole blocking layer enables a large number of holes contributing to light emission to be confined in the light emitting layer, and high light emitting efficiency is obtained in the light emitting layer.

The electron injection layer is provided between the light emitting layer and the cathode or between the hole blocking layer and the cathode. The electron injection layer facilitates injection of electrons from the cathode into the light emitting layer. The hole injection layer is provided between the light emitting layer and the anode. The hole injection layer facilitates injection of holes from the anode into the light emitting layer.

In order to improve the efficiency of hole injection from the anode to the light emitting layer, it is desirable that the work function of the ITO film surface be high.

[0012] A conventional organic electroluminescent element is composed of ITO which is provided on a transparent insulating substrate as an anode.
(Indium tin oxide) film is often used. The work function of the conventionally used ITO film surface is 4.6 to 4.8 eV.

A conventional technique for increasing the work function of the ITO film surface is disclosed in Japanese Patent Application Laid-Open No. 8-167479. According to this conventional technique, first, an ITO thin film is formed on an insulating substrate in a nearly amorphous form by a sputtering method, an electron beam evaporation method, a plasma CVD method, or the like. Next, this I
The TO thin film is annealed at 100 to 150 ° C. under reduced pressure or in a non-oxidizing atmosphere. Thereafter, the ITO thin film is annealed at 100 to 500 ° C. in an oxidizing atmosphere or is irradiated with plasma. After the above treatment, the ITO thin film has a work function of 5.1 to 6.0.
Increased to eV.

The work function of the ITO thin film after the above treatment sharply decreases with the passage of time. For this reason, this ITO
In the case of forming an organic electroluminescence device using a thin film as an anode, when an ionization potential of a layer in contact with the anode is 5.5 eV or more, an injection barrier when holes are injected from the anode becomes high.

[0015]

SUMMARY OF THE INVENTION An object of the present invention is to provide a transparent electrode having an improved surface work function.

Another object of the present invention is to provide a transparent electrode processing apparatus and a transparent electrode processing method for improving the work function of the transparent electrode surface.

Still another object of the present invention is to provide an organic electroluminescent device which can be driven at a high luminance and at a low voltage.

It is another object of the present invention to provide an organic electroluminescence device capable of improving the efficiency of charge injection from an electrode to an organic layer provided in contact with the electrode.

[0019]

Means for solving the problem are described as follows. The technical matters corresponding to the claims in the expression are appended with numbers, symbols, etc. in parentheses (). The numbers, symbols, etc. clarify the correspondence / correspondence between the technical matters corresponding to the claims and at least one of the plural / forms of implementation.
It is not intended to show that the technical matters corresponding to the claims are limited to the technical matters of the embodiment.

According to the present invention, a transparent substrate (1) and a transparent conductive film (2) provided on the transparent substrate (1) are provided. A transparent electrode exposed to a gas (6) containing oxygen is provided.

In the above transparent electrode, the transparent conductive film (2) can be made of a conductive oxide.

In the above transparent electrode, the gas (6) is
It can contain active oxygen at a concentration of 1% or more.

In the above transparent electrode, the work function of the transparent conductive film (2) can be 5.5 eV or more.

According to the present invention, there is provided a transparent electrode (31) as an anode and an organic layer (32, 33) formed on the transparent electrode (31).
And the organic layer (32, 33) includes at least one light-emitting layer (32, 33), and a cathode (34) formed on the organic layer (32, 33). I will provide a.

In the above-mentioned organic electroluminescence device, the organic layer (32, 33) has a hole transport layer (3).
It is possible that the ionization potential of the hole transport material constituting the hole transport layer (32) is not less than 5.4 eV.

Further, according to the present invention, in order to solve the above-mentioned problems, a plasma generation apparatus for generating a plasma in a first gas containing oxygen to generate a second gas (6) containing active oxygen. (3) a processing tank (5) in which the first gas is supplied from the outside to the inside of the plasma generator (3), and a second gas (6) is supplied from the plasma generator (3); And a treatment tank (5) includes a transparent electrode (13a, 13a, 13b) formed of a transparent substrate and a transparent conductive film provided on the transparent substrate.
23a) is disposed, and a transparent electrode (13) is formed using the second gas (6) supplied from the plasma generator (3).
a) and a transparent electrode processing apparatus for performing an active oxygen processing.

In the above transparent electrode processing apparatus, the transparent conductive film can be made of a conductive oxide.

In the above transparent electrode processing apparatus, the first gas may have an oxygen concentration of 1% or more.

Further, in order to solve the above problems,
According to the present invention, in a transparent electrode processing apparatus having a plasma generator, generating plasma in a first gas containing oxygen to generate a second gas containing active oxygen inside the plasma generator. Discharging the second gas from the inside of the plasma generator, and exposing the transparent electrode to the discharged second gas,
Here, the transparent electrode provides a method for treating a transparent electrode composed of a transparent substrate and a transparent conductive film provided on the transparent substrate.

In the above-mentioned method for treating a transparent electrode, the transparent conductive film can be made of a conductive oxide.

In the above method for treating a transparent electrode, the first
Can have an oxygen concentration of 1% or more.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the transparent electrode according to the present invention will be described with reference to the drawings.

FIG. 1 shows a transparent electrode according to the present invention.
The transparent electrode according to the present invention includes a transparent substrate 1 and a transparent conductive film 2 provided on the transparent substrate 1.

The transparent substrate 1 is made of a transparent insulator such as glass.

The transparent conductive film 2 is made of a conductive oxide such as tin oxide, indium oxide and lead indium oxide (ITO).

The transparent conductive film 2 is formed on the transparent substrate 1 by a sputtering method using a conductive oxide. The transparent conductive film 2 is subjected to the following active oxygen treatment.

Next, the conductive film processing apparatus according to the present invention will be described.

FIG. 2 shows a conductive film processing apparatus according to the present invention. The conductive film processing apparatus according to the present invention includes a plasma generator 3, a tube 4, and an anodizing tank 5.

The plasma generator 3 has a supply port (not shown) for supplying a gas from the outside.

The tube 4 connects the plasma generator 3 and the anodizing tank 5. The tube 4 is made of a glass tube, a resin tube, or the like.

The anodizing tank 5 has a sample stage on which a sample is placed. This sample consists of the transparent electrode shown in FIG. This sample stage will be described later. Further, the anodizing bath 3 is selected from a shower head system and a radial flow system.

Next, a conductive film processing method using the conductive film processing apparatus according to the present invention will be described.

First, the sample is placed on the sample stage of the anodizing tank 5. Here, the sample is arranged so that the sample stage and the transparent substrate 1 face each other.

The plasma generator 3 is supplied with a gas containing oxygen from a supply port.

The plasma generator 3 performs a plasma generation process on the oxygen-containing gas. By this plasma generation processing, the plasma generator 3 generates a gas 6 containing active oxygen from the gas containing oxygen. Here, this plasma generation processing is performed by DC bipolar method, RF inductive coupling method, RF
The method is selected from a capacitive coupling method, an RF magnetron method, a microwave magnetic field method (ECR method), a microwave method (no magnetic field), and the like.

The gas 6 containing active oxygen is sent from the plasma generator 3 to the anodizing tank 5 through the tube 4.

This sample is exposed to a gas 6 containing active oxygen in an anodizing bath 5. The method of supplying the gas 6 containing active oxygen in the anodizing bath 5 is selected from a shower head method or a radial flow method.

FIG. 3 shows an anodizing tank 5a to which a gas 6 containing active oxygen is supplied by a shower head method. This anodized layer 5a has an inlet 11, an outlet 12, and a sample stage 13.

The inlet 11 is provided at the entire upper part of the anodizing tank 5a,
Or it has a shape that covers a part. Inlet upper part 11
a is connected to the tube 4. The inlet lower portion 11b has a plurality of holes through which the gas 6 containing active oxygen can pass.

At least one exhaust port 12 is provided below the anodized layer 5a. The exhaust port 12 performs exhaust at a predetermined back pressure. The exhaust port 12 is desirably provided at the peripheral edge of the anodized layer 5a.

The sample stage 13 is arranged below the anodized layer 5a. The sample 13a is arranged on the sample stage 13.

Next, a method of treating the sample 13a with active oxygen by using the anodizing bath 5a using the showerhead method will be described below.

First, since the exhaust port 12 is evacuated with a predetermined back pressure, the air pressure inside the anodized layer 5a decreases. In order to supplement this air pressure, the gas 6 containing active oxygen is supplied from the plasma generator 3 to the inlet 11 via the tube 4, and is supplied from the lower part 11b of the inlet to the inside of the anodized layer 5a.
Since the inlet lower portion 11b has a structure having a plurality of holes, the gas 6 is supplied into the anodized layer 5a in a shower shape through the plurality of holes. The sample 13a is exposed to the gas 6 supplied into the anodized layer 5a in a shower shape. As a result, the sample 13 a is subjected to the active oxygen treatment by the gas 6.

FIG. 4 shows an anodizing tank 5b using a radial flow method. This anodized layer 3b is
1, an exhaust port 22 and a sample table 23 are provided.

The inlet 21 is provided below the center of the anodizing tank 5b. The inlet 21 is connected to the pipe 4. The gas 6 containing active oxygen is supplied from the plasma generator 3 through the tube 4 and the inlet 21 to the inside of the anodized layer 3b.

At least one exhaust port 22 is provided at the lower peripheral portion of the anodizing tank 5b. Exhaust port 22
Performs exhaust at a predetermined back pressure.

The sample stage 23 is located below the anodized layer 5 b and between the inlet 21 and the outlet 22.
Further, a configuration in which the inlet 21 is provided at the center of the sample table 23 is also possible. The sample 23a is arranged on the sample stage 23. Here, the inlet 21 is connected to the anodized layer 5b.
It is desirable that the gas 6 containing active oxygen be supplied from a position below the height of the sample table 23 from the bottom.

Next, a method of treating the sample 23a with active oxygen using the anodizing bath 5b using the radial flow method will be described below.

First, since the exhaust port 22 is evacuated with a predetermined back pressure, the air pressure inside the anodized layer 5b decreases. To compensate for this air pressure, the gas 6 containing active oxygen is supplied from the plasma generator 3 through the tube 4 and the inlet 21 to the anodized layer 5.
b. The sample 23a is exposed to the gas 6 before the gas 6 is supplied from the inlet 21 and exhausted at the exhaust port 22. For this reason, the sample 23a is subjected to the active oxygen treatment by the gas 6.

Next, the organic electroluminescence device of the present invention will be described below with reference to the drawings.

FIG. 5 shows an organic electroluminescent device according to the present invention. The organic electroluminescence device according to the present invention includes an anode 31, a hole transport layer 32, an organic layer 33, and a cathode. The hole transport layer 32 is provided on the anode 31. The organic layer 33 is a hole transport layer 32
It is provided above. The cathode 34 is provided on the organic layer 33.

The anode 31 is made of the transparent electrode of the present invention shown in FIG. The anode 31 includes an insulating transparent substrate,
It consists of a conductive film formed on an insulating transparent substrate. The material of the conductive film in the present invention is selected from conductive oxides such as tin oxide, indium oxide, and lead indium oxide (ITO).

The hole transport layer 32 is made of a hole transport material. Here, the hole transporting material is selected from conventionally known hole transporting low molecules and hole transporting polymers. In particular, the hole transport material desirably has an ionization potential of 5.4 eV or more. Further, the hole transport layer 32 can also include a conventionally known binder polymer or fluorescent material.

The organic layer 33 is made of a conventionally known light emitting material. In addition, the organic layer 33 may include a conventionally known fluorescent dopant or a conventionally known binder polymer. Further, the organic layer 33 may be formed of a multilayer including a light emitting layer and at least one electron transport layer provided on the light emitting layer. Here, the electron transport layer is made of an electron transport material. The electron transporting material is selected from conventionally known electron transporting low molecules and electron transporting polymers. The electron transport layer can also include a conventionally known binder polymer. Alternatively, the organic layer 33 may be formed of an electron transporting light emitting layer formed from a conventionally known fluorescent material and electron transporting material. In addition, the organic layer 33 may be configured to include a conventionally known hole blocking layer or electron injection layer.

The cathode 34 is made of a conventionally used cathode material.

Next, a method for manufacturing an organic electroluminescence device according to the present invention will be described below.

The anode 31 is formed similarly to the transparent electrode of the present invention.

The hole transport layer 32 is formed on the anode 31 by a vapor deposition method or a wet method using a solution in which a hole transport material is dissolved in a solvent.

The organic layer 33 is formed on the hole transport layer 32 by a conventionally known vapor deposition method or a wet method using a solution in which a luminescent material is dissolved in a solvent. The organic layer 33 can also be formed using a conventionally known fluorescent dopant or a solution in which a conventionally known binder polymer is further dissolved.

Further, the organic layer 33 can be composed of a multilayer including a light emitting layer and an electron transport layer formed on the light emitting layer. In this case, the step of forming the organic layer 33 includes:
It comprises a step of forming a light emitting layer and a step of forming a layer such as an electron transport layer on the light emitting layer.

The light emitting layer is formed on the hole transport layer 32 by a wet method using a conventionally known solution in which a fluorescent material is dissolved in a solvent. Further, the light emitting layer can be formed by using a solution in which a conventionally known binder polymer is further dissolved.

The electron transporting layer is formed on the light emitting layer by a wet method using a solution in which an electron transporting material is dissolved in a solvent. The electron transport layer can also include a conventionally known binder polymer.

Alternatively, the organic layer 33 can be formed on the hole transport layer 32 by a known wet method using a solution in which a fluorescent material and an electron transport material are dissolved in a solvent. In addition, the step of forming the organic layer 33 may include a step of forming a hole blocking layer and a step of forming an electron injection layer which are conventionally known.

The cathode 34 is formed by a vapor deposition method using a conventionally used cathode material.

Next, examples of the method for treating the transparent electrode with active oxygen in the present invention will be described.

Example 1 A commercially available ITO substrate (manufactured by Asahi Glass, 20 Ω / cm ² ) is used as a transparent electrode. The gas sent to the plasma generator has an oxygen concentration of 10
0%. The plasma generation method of the plasma generation apparatus uses a microwave method (output 1,500 W, oscillation frequency 2,450 MHz). The anodizing bath uses a shower head system. The back pressure at the exhaust port of the anodizing tank is 30 Pa. Under the above conditions, the ITO substrate is subjected to active oxygen treatment at a flow rate of 100 cm ³ / min of gas sent from the plasma generator to the anodizing tank for a treatment time of 2 min.

The work function of the ITO substrate after the active oxygen treatment is measured using a Fermi level measuring device F-AC1 manufactured by Riken Keiki Co., Ltd. The measurement result showed a work function of 7.0 eV.

In Examples 2 to 6, ITO was applied under the same conditions as in Example 1 except for the oxygen concentration of the gas sent to the plasma generator.
Active oxygen treatment is performed on the substrate. Examples 2 to 6
Compared with the first embodiment, the partial pressure ratio between oxygen and argon of the gas is different. The work function of the ITO substrate after the active oxygen treatment in each example is measured using a Fermi level measuring device F-AC1 manufactured by Riken Keiki Co., Ltd. Table 1 shows the results of the active oxygen treatment. [Table 1] shows the mixture ratio of oxygen and argon of the gas sent to the plasma generator and the work function of the ITO substrate after the active oxygen treatment in Examples 2 to 6.

[0079]

[Table 1] According to Examples 1 to 6, when the oxygen concentration of the gas sent to the plasma generator is 1% or more, the IT
The work function of the O substrate shows 5.5 eV or more. From this,
The present invention improves the work function of the ITO substrate.

In Examples 7 to 9, the active oxygen treatment was performed on the ITO substrate under the same conditions as in Example 1 except that the flow rate of the gas sent from the plasma generator to the anodizing tank was changed. [Table 2] shows the flow rates of gases sent from the plasma generator to the anodizing tank in Examples 7 to 9,
4 shows a work function of an ITO substrate after active oxygen treatment.

[0081]

[Table 2] According to Examples 1 and 7 to 9, when the gas sent to the plasma generator has an oxygen concentration of 100%, the flow rate of the gas sent from the plasma generator to the anodizing tank is from 70 cm ³ / min to 300
If it is between cm ³ / min, the work function of the ITO substrate after the active oxygen treatment is higher than before the active oxygen treatment. In particular, the flow rate of gas sent from the plasma generator to the anodizing tank is 100 c.
At about m ³ / min, the ITO substrate after the active oxygen treatment has the highest work function.

A comparative example of a method for treating a conductive film with active oxygen is described below. This comparative example is a conventional technique disclosed in Japanese Patent Application Laid-Open No. 8-167479. In this comparative example, the conductive film is subjected to active oxygen treatment by directly exposing the conductive film surface to plasma. As the conductive film, a commercially available ITO substrate (manufactured by Asahi Glass, 20 Ω / cm ² ) is used.

FIG. 6 shows an active oxygen treatment apparatus used in this comparative example. This active oxygen treatment device is a barrel type device 4
It is one. This device 41 includes an inlet 42, an outlet 43, and a high-frequency electrode 44. Gas from the outside is sent from the inlet 42 into the device 41. The gas inside the device 41 is exhausted from the exhaust port 43 to the outside at a predetermined back pressure. The high-frequency electrode 44 is provided inside the device 41. The high-frequency electrode 44 has a cylindrical shape. The high-frequency electrode 44 is connected to an AC power supply 45 for applying a voltage. The sample 46 is placed on a sample stage (not shown) inside the high-frequency electrode 44.
Placed in

Next, the operation of the active oxygen processing apparatus used in this comparative example will be described.

When a voltage of a predetermined intensity is applied from the AC power supply 45, the device 41 generates plasma using the gas sent from the inlet 42. The sample 46 is subjected to active oxygen treatment using this plasma. here,
The amount of gas exhausted from the device 41 is controlled by the back pressure of the exhaust port 43.

In Comparative Examples 1 to 6, the ITO substrate was treated with active oxygen using a barrel-type apparatus 41 shown in FIG. The plasma generation method of the device 41 is an RF inductive coupling method in which the output of the AC power supply 45 is 100 W and the output frequency is 1.356 MHz. The gas sent from the inlet 42 to the device 41 is composed of oxygen and argon. In Comparative Examples 1 to 6, the partial pressure ratio between oxygen and argon in the gas is different. The device 41 is exhausted from the exhaust port 43 at a back pressure of 53.1 Pa.
Under the above conditions, the ITO substrate is subjected to the active oxygen treatment at a flow rate of the gas sent to the apparatus 41 of 100 cm ³ / min for a treatment time of 2 min. The work function of the ITO substrate after the active oxygen treatment in each comparative example was measured by a Fermi level measuring device manufactured by Riken Keiki Co., Ltd.
Measured using F-AC1. [Table 3] shows the results of the active oxygen treatment performed in Comparative Examples 1 to 6. [Table 3]
In Comparative Examples 1 to 6, the mixture ratio of oxygen and argon of the gas sent into the dry etcher and the work function of the ITO substrate after the active oxygen treatment are shown.

[0087]

[Table 3] According to Comparative Examples 1 to 6, the work function of the ITO substrate after the active oxygen treatment shows 5.5 eV or less regardless of the oxygen concentration of the gas sent to the plasma generator.

Example 10 is described below. 6.9 mg of poly-N-vinyl carbazole (hereinafter referred to as PVK) is added to 1 ml of dichloroethane.
A first solution is prepared. A hole transport layer having a thickness of 50 nm was formed on the ITO substrate (manufactured by Asahi Glass, 20 Ω / cm ² , work function 7 eV) subjected to the active oxygen treatment according to Example 1 by spin coating using the first solution. Is done. 2- (4
-Biphenyl) -5- (4-tert-butylphenyl)-
6.25mg of 1,3,4-oxadiazole (hereinafter PBD)
Then, a second solution is prepared by dissolving 60.25 mg of coumarin as a fluorescent substance and 6.25 mg of polystyrene as a binder in 1 ml of ethylbenzene. The organic layer is formed with a thickness of 50 nm on the hole transport layer by using a wet method using the second solution. The cathode is formed by depositing Mg and Al as cathode materials on an organic layer by a co-evaporation method. An organic electroluminescence element is formed by the above steps. In this organic electroluminescence device, the hole transport layer has an ionization potential of 5.9 eV, and the anode has a work function of 7 eV. This organic electroluminescent device exhibited a luminance of 150 cd / m ² at an applied voltage of 10 V. The applied voltage required for obtaining a luminance of 100 cd / m ² in this organic electroluminescence device was 9.2 V.

In Examples 11 to 16, an organic electroluminescent element is formed in the same steps as in Example 10 except for the material of the hole transport layer. [Table 4] shows the material of the hole transport layer, the ionization potential of the material (unit: eV), and the work function of the anode (unit: eV) in the organic electroluminescence devices formed in Examples 10 to 16.
And the luminance (unit: cd / m ² ) at an applied voltage of 10 V, and the luminance is 100 cd /
Indicates the applied voltage (unit: V) required to obtain m ² .

[0090]

[Table 4] Here, PTPDEK is represented by the chemical formula [Formula 1].

[0091]

Embedded image Here, PTPDEK2 is represented by the chemical formula [Formula 2].

[0092]

Embedded image Here, PTPDES is represented by the chemical formula [Formula 3].

[0093]

Embedded image Here, PTPDDES2 is represented by the chemical formula [Formula 4].

[0094]

Embedded image Here, PTPDBPA is represented by the chemical formula [Formula 5].

[0095]

Embedded image Here, PTPDMA is represented by the chemical formula [Formula 6].

[0096]

Embedded image Example 17 is shown below. In Example 17, an organic electroluminescence device composed of an anode / a bipolar light emitting layer / a cathode was formed.

First, an anode is formed. The method for forming the anode is the same as that in Example 10.

Next, a bipolar light emitting layer is formed. The material of the bipolar light emitting layer is a poly (fluorene-thiophene) copolymer represented by the chemical formula [Formula 7]. The ionization potential of this poly (fluorene-thiophene) copolymer is 5.8 eV.

[0099]

Embedded image A 100 nm-thick bipolar light-emitting layer is formed on the anode by spin coating using a solution of 10 mg of a poly (fluorene-thiophene) copolymer dissolved in a solvent.

Finally, a cathode is formed. A cathode is formed on the bipolar light emitting layer using an evaporation method using Ca as a cathode material.

The organic electroluminescent device formed in Example 17 had a luminance of 226 cd / m ² at an applied voltage of 10 V.
Flashed. The voltage applied to the organic electroluminescent device to emit light at a luminance of 100 cd / m ² was 9.1 V.

Embodiment 18 will be described below. Example 18
Except for the step of forming the bipolar light-emitting layer, an organic electroluminescent element is formed in the same steps as in Example 17. The steps of forming the bipolar light emitting layer are described below. The material of the bipolar light emitting layer is poly (2-methoxy, 5- (2 ′
-Ethyl-hexyloxy) -1,4-phenylenevinylene (MEH-PPV). The ionization potential of MEH-PPV is 5.2 eV. Here, MEH-P
PV is represented by the chemical formula [Formula 8].

[0103]

Embedded image A 100 nm-thick bipolar light emitting layer is formed on the hole injection layer by a spin coating method using a solution of MEH-PPV dissolved in a solvent.

The organic electroluminescent device formed in Example 18 had a luminance of 1,000 cd / m ² at an applied voltage of 5 V.
Flashed.

In Comparative Examples 7 to 13, an ITO substrate treated with active oxygen in Comparative Example 6 was used as an anode. Comparative Example 7
Steps 13 to 13 form an organic electroluminescent element in the same steps as in Example 10 except for the material of the hole transport layer. [Table 5] shows the materials of the hole transport layer and the ionization potential (unit: eV) of the materials in the organic electroluminescence devices formed in Comparative Examples 7 to 13.
The work function (unit: eV) of the anode, the luminance (unit: cd / m ² ) at an applied voltage of 10 V, and the applied voltage (unit: V) necessary to obtain a luminance of 100 cd / m ² are shown.

[0106]

[Table 5]

Comparative Example 14 is shown below. Comparative Example 14
An organic electroluminescence element comprising an anode / bipolar light emitting layer / cathode is formed.

First, an anode is formed. The method for forming the anode is the same as in Comparative Example 6.

Next, a bipolar light emitting layer is formed. The method for forming the bipolar light emitting layer is the same as that in Example 18, and
The bipolar light emitting layer is formed using a poly (fluorene-thiophene) copolymer.

Finally, a cathode is formed. The method for forming the cathode is the same as that in Example 17.

The organic electroluminescent device formed in Comparative Example 14 had a luminance of 125 cd / m ² at an applied voltage of 10 V.
Flashed. The voltage applied to the organic electroluminescent device to emit light at a luminance of 100 cd / m ² was 9.8 V.

Comparative Example 15 is shown below. Example 18
Except for the step of forming the bipolar light-emitting layer, an organic electroluminescent element is formed in the same steps as in Example 17. The formation process of the bipolar light emitting layer is the same as that of Example 18, and the bipolar light emitting layer is formed using MEH-PPV.

The organic electroluminescent device formed in Comparative Example 15 emitted light at a luminance of 960 cd / m ² at an applied voltage of 5 V. The voltage applied to emit light at a luminance of 1,000 cd / m ² in this organic electroluminescent device was 5.2 V.

[Table 4] and [Table 5] and Examples 17 and 1
8 and Comparative Examples 14 and 15, when the material of the lower layer was the same, when the voltage applied to the device was 10 V, the results of Examples 10 to 16 were
The organic electroluminescent device formed by the method of Example 1 exhibits higher luminance than the organic electroluminescent devices formed by Comparative Examples 7 to 13. At this time, the ionization potential of the lower layer material is 5.4 eV or more.

The organic electroluminescence device formed in Example 18 and the organic electroluminescence device formed in Comparative Example 15 show almost the same luminance when the voltage applied to the device is 5 V. In Example 18 and Comparative Example 15, the lower layer material of the organic electroluminescence element was the same. This lower layer material has an ionization potential of 5.2 eV.

From the above, when the ionization potential of the hole transport layer material is 5.4 eV or more, the luminance of the organic electroluminescent device of the present invention is improved as compared with the conventional one. In particular, the higher the ionization potential of the hole transport layer material, the more the brightness of the organic electroluminescent device is improved.

When the material of the lower layer is the same, the organic electroluminescent elements formed in Examples 10 to 17 obtain a luminance of 100 cd / m ² more than the organic electroluminescent elements formed in Comparative Examples 7 to 14. Required voltage is low.

The applied voltage required to obtain a luminance of 1,000 cd / m ² is substantially equal between the organic electroluminescent device formed in Example 18 and the organic electroluminescent device formed in Comparative Example 15.

From the above, when the ionization potential of the hole transport layer material is 5.4 eV or more, the organic electroluminescence device of the present invention is driven at a lower voltage than the organic electroluminescence device of the prior art. In particular, as the ionization potential of the hole transport layer material is higher, the organic electroluminescence device of the present invention is driven at a lower voltage.

[0120]

The present invention has the effect of improving the work function of the transparent electrode surface.

The present invention has the effect of improving the efficiency of injecting holes from the transparent electrode into the organic layer by using a transparent electrode having an improved work function on the surface in an organic electroluminescence device.

Further, the organic electroluminescence device of the present invention has the effect of driving with higher luminance and lower applied voltage than the conventional organic electroluminescence device using the same material.

[Brief description of the drawings]

FIG. 1 shows a transparent electrode according to the present invention.

FIG. 2 shows a transparent electrode processing apparatus according to the present invention.

FIG. 3 shows an anodizing tank for supplying active oxygen into the inside by a showerhead method.

FIG. 4 shows an anodizing tank for supplying active oxygen inside by a radial flow method.

FIG. 5 shows an organic electroluminescence device according to the present invention.

FIG. 6 shows a barrel-type dry etcher.

[Explanation of symbols]

 Reference Signs List 1 transparent substrate 2 transparent conductive film 3 plasma generator 4 tube 5, 5a, 5b anodizing tank 6 gas containing active oxygen 11, 21, 42 inlet 11a upper inlet 11b lower inlet 12, 22, 43 exhaust 13 , 23 Sample table 13a, 23a Sample 31 Anode 32 Hole transport layer 33 Organic layer 34 Cathode 41 Barrel type device 44 High frequency electrode 45 AC power supply

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Satoshi Ishii 1-10-1 Shinsayama, Sayama City, Saitama Prefecture Inside Honda Engineering Co., Ltd. (72) Inventor Akihiro Komatsuzaki 1-10-1 Shinsayama, Sayama City, Saitama Prefecture Within Da Engineering Co., Ltd. (72) Inventor Yoichi Shimada 1-10-1, Shinsayama, Sayama City, Saitama Prefecture Honda Engineering Co., Ltd. F term (reference) 3K007 AB00 AB02 AB03 AB06 CA01 CB01 DA00 DB03 EB00 FA00 FA01

Claims (12)

[Claims] 1. A transparent electrode, comprising: a transparent substrate; and a transparent conductive film provided on the transparent substrate, wherein the transparent conductive film is exposed to a gas containing active oxygen. 2. The transparent electrode according to claim 1, wherein the transparent conductive film is made of a conductive oxide. 3. The transparent electrode according to claim 1, wherein the gas contains active oxygen having a concentration of 1% or more. 4. The transparent electrode according to claim 1, wherein the work function of the transparent conductive film is 5.5 eV or more. 5. The transparent electrode according to claim 1 as an anode, an organic layer formed on the transparent electrode, wherein the organic layer is at least one light emitting layer. An organic electroluminescence device comprising: a cathode formed on the light emitting layer. 6. The organic electroluminescence device according to claim 5, wherein the organic layer includes a hole transport layer, and a hole transport material constituting the hole transport layer has an ionization potential of 5.4 eV or more. Organic electroluminescent element. 7. A plasma generating apparatus for generating plasma in a first gas containing oxygen to generate a second gas containing active oxygen, wherein the first gas is generated from outside by the plasma generating apparatus. And a processing tank to which the second gas is supplied from the plasma generator. The processing tank includes a transparent substrate and a transparent electrode formed of a transparent conductive film provided on the transparent substrate. A transparent electrode processing apparatus which is disposed and performs an active oxygen treatment on the transparent electrode using the second gas supplied from the plasma generator. 8. The transparent electrode processing apparatus according to claim 7, wherein the transparent conductive film is made of a conductive oxide. 9. The transparent electrode processing apparatus according to claim 7, wherein the first gas has an oxygen concentration of 1% or more. 10. A transparent electrode processing apparatus having a plasma generator, wherein a plasma is generated in a first gas containing oxygen inside the plasma generator to generate a second gas containing active oxygen. Discharging the second gas from the inside of the plasma generating device; and exposing a transparent electrode to the discharged second gas, wherein the transparent electrode includes a transparent substrate and the transparent substrate. A method for treating a transparent electrode, comprising a transparent conductive film provided thereon. 11. The method for processing a transparent electrode according to claim 10, wherein the transparent conductive film is made of a conductive oxide. 12. The method for processing a transparent electrode according to claim 10, wherein the first gas has an oxygen concentration of 1% or more.