JPH06124785A - Organic el element - Google Patents

Abstract

PURPOSE:To provide high light emitting efficiency, light emitting stability, the long service life and flexibility by setting a quantity of a foreign matter and a projecting material of not less than 1mum on an interface between a film and an electrode and a surface of the electrode not more than a specific value in the film. CONSTITUTION:The first electrode, an organic single layer part or an organic multilayer part having a light emitting material composed of an organic compound and the second electrode are arranged in order on a high polymer film. In the high polymer film, the total number of defects such as a foreign matter, a projecting material, a hole, and a pore of not less than 1mum on an interface between the high polymer film and the first electrode and a surface of the first electrode is set not more than 100 pieces in a conversion value per 1m<2>. Improvement in purity of a raw material of the high polymer film, improvement in the film creating environment (for example, use of a clean room), improvement in a film forming device (for example, improvement in flatness of a film forming part of the device), and purification by cleaning can be cited as the method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic EL (electroluminescence) element used as a display element, a light emitting element or the like.

[0002]

2. Description of the Related Art EL elements have high visibility because they are self-luminous, and because they are completely solid elements, they have excellent impact resistance. A variety of EL devices using the are being researched and developed.

By the way, as applications of EL elements, there are various applications such as thin film panels, belt shapes, cylindrical shapes, etc. for displaying lines, drawings, images, etc., and for producing EL elements used for such applications. It is convenient to use a thin and flexible polymer film as the substrate. For example, in Japanese Unexamined Patent Publication Nos. 2-251429 and 2-253593, an electrode made of a transparent conductive film is formed on a polymer film which is a substrate, and this electrode is used as one electrode and another electrode facing the other electrode. A flexible organic EL device obtained by providing a single or multiple layers including a light emitting layer made of an organic compound between one electrode is disclosed. The organic EL device described in this prior art document can be manufactured at a substrate temperature of about room temperature, and therefore has an advantage that problems such as substrate deformation due to high temperature do not occur.

[0004]

However, in the flexible organic EL element described in the above-mentioned prior art document, in order to observe light emission under a fluorescent lamp (in a bright place), an applied voltage of 10 V or more and 1 A / cm. ^It requires a current density of ² or more and the luminous efficiency is insufficient. Further, since the luminous efficiency is insufficient, the luminous stability is inferior, the device life is short, and there is a problem in practical use. Therefore, an object of the present invention is to provide a flexible organic EL device having high luminous efficiency, resulting in excellent luminous stability and long device life.

[0005]

As a result of studies to achieve the above object, a polymer film or a laminated film in which an organic or inorganic material film is laminated on the polymer film, and a film provided on these films are provided. In the support substrate for an organic EL device comprising the formed electrodes, the total number of defects such as foreign matter, protrusions, holes and holes of 1 μm or more in the film, the interface between the film and the electrode and the electrode surface is determined. It was found that a flexible organic EL device having a high luminous efficiency, excellent light emission stability, and a long device life can be obtained by setting the number of 100 or less converted per 1 m ² and the present invention completed.

Therefore, according to the present invention, a first electrode, an organic single-layer portion or an organic multi-layer portion having a light emitting material made of an organic compound, and a second electrode are sequentially provided on a polymer film. In an organic electroluminescence device in which at least one of the electrodes is transparent or semi-transparent, foreign matter, protrusions, or holes of 1 μm or more in the polymer film, the interface between the polymer film and the first electrode, and the surface of the first electrode , The total number of defects such as vacancies is 100 or less in terms of a converted value per 1 m ² (hereinafter, referred to as organic EL element (A)).

The present invention also provides a first electrode, an organic single-layer part or an organic multi-layer part having a light-emitting material composed of an organic compound, and a first electrode on a laminated film obtained by laminating an organic or inorganic material film on a polymer film. In an organic electroluminescence element, which comprises two electrodes in sequence, at least one of the two electrodes being transparent or semitransparent, in a laminated film, an interface between the laminated film and the first electrode, and a surface of the first electrode. Foreign matter of 1 μm or more, protrusions,
The gist is an organic EL element (hereinafter referred to as an organic EL element (B)) characterized in that the total number of defects such as holes and holes is 100 or less in terms of a converted value per 1 m ² .

First, the organic EL device (A) of the present invention will be described. The polymer film used as the substrate in the organic EL element (A) is not particularly limited as long as it can be formed into a film, but a material having high transparency and relatively high heat resistance is preferable. As a polymer film that satisfies such conditions,
Polyethylene terephthalate (PET), polycarbonate (PC), polyether sulfone (PES), polyether ether ketone (PEEK), polyvinyl fluoride (PFV), polyacrylate (PA), polypropylene (PP), polyethylene (PE), Amorphous polyolefins, fluororesins, etc. may be mentioned. In order to fully utilize the flexibility of these polymer films, the thickness of the polymer film is preferably 0.001 μm to 1 mm.

In the organic EL device (A) of the present invention,
The first electrode, the organic single layer portion or the organic single layer portion having a light emitting material made of an organic compound, and the second electrode are sequentially provided on the polymer film described in detail above.

That is, in the organic EL device (A) of the present invention, a light emitting material made of an organic compound is provided between the first electrode provided on the polymer film and the second electrode facing the first electrode. The organic single-layer part or the organic multi-layer part has is interposed. And, of the above two electrodes, one constitutes an anode and the other constitutes a cathode, and as the material of the former anode,
For example, a metal, an alloy, an electrically conductive compound having a high work function (4 eV or more), or a mixture thereof is preferably used. As a specific example, a metal such as Au, CuI, I
Dielectric transparent materials such as TO, SnO ₂ and ZnO can be mentioned. In particular, ITO is preferable in terms of productivity and controllability. Further, as the material of the cathode, a metal, an alloy, an electrically conductive compound, a mixture thereof or the like having a small work function (4 eV or less) is preferably used. As a specific example,
Examples include lithium, sodium, magnesium, copper, indium, sodium-potassium alloy, magnesium-copper mixture, and Al / Al ₂ O ₃ .

In particular, it is preferable to use a conductive film made of ITO as the material of the first electrode provided on the polymer film, and make the first electrode act as an anode.

In the organic EL device (A) of the present invention, it is essential that at least one of the above two electrodes is transparent or semitransparent in order to obtain translucency.
Since the conductive film made of ITO is transparent, it is preferable to provide the conductive film made of ITO as an anode on the polymer film also in this respect. The thickness of the electrode is 10nm-1
μm is preferable, and from the viewpoint of increasing the light transmittance, it is particularly preferably 10
It is preferable that the thickness is 200 nm.

In the organic EL device (A) of the present invention, the organic single layer portion or the organic multilayer portion interposed between the two electrodes has at least a light emitting layer made of an organic compound. A layer only, a light emitting layer and a hole injection layer, an electron injection layer and a light emitting layer, an electron injection layer, a light emitting layer and a hole injection layer, an adhesive layer and a light emitting layer And a hole injection layer (Japanese Patent Application No. 3-104284), a mixture of materials having these functions, or a polymer dispersed therein. In the case of a multi-layer structure, the order of forming the organic multi-layer portion may be reversed depending on the polarities of the electrodes.

As the materials of the generation layer, the hole injection layer and the electron injection layer, conventionally known materials are used. For example, as an organic compound that can be used as a material of the light emitting layer, a benzothiazole-based, benzimidazole-based, a benzoxazole-based fluorescent whitening agent, a metal chelated oxinoid compound, a styrylbenzene-based compound, a distyrylpyrazine derivative, an aromatic Group dimethylidene compounds and the like can be mentioned.

Examples of the material for the hole injection layer include triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives and oxazole derivatives. , Styrylanthracene derivative, fluorenone derivative, hydrazone derivative, stilbene derivative,
Specific conductive polymer oligomers such as silazane derivatives, polysilane compounds, aniline copolymers, and thiophene oligomers can be used.

Examples of materials for the electron injection layer include nitro-substituted fluorenone derivatives, anthraquinodimethane derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, and heterocyclic tetracarboxylic acid anhydrides such as naphthaleneperylene.
Examples thereof include carbodiimide, fluorenylidene methane derivative, anthraquinodimethane derivative, anthrone derivative, oxadiazole derivative, 8-quinolinol derivative and other specific electron transfer compounds.

Further, as a material for the adhesive layer constituting the organic multilayer portion described in Japanese Patent Application No. 3-104284, a metal complex of 8-quinolinol or its derivative, such as tris (8-quinolinol) aluminum, bis (8). -Quinolinol) magnesium, bis (benzo-8-quinolinol) zinc, bis (2-methyl-8-quinolinolate) aluminum oxide, tris (8-quinolinol) indium, tris (5-methyl-8-quinolinol) aluminum, 8- Lithium quinolinol, tris (5-chloro-8-quinolinol) gallium, bis (5-chloro-)
8-quinolinol) calcium, 5,7-dichloro-8
-Quinolinol aluminum, tris (5,7-dibromo-8-hydroxyquinolinol) aluminum and the like.

The method for producing the organic single layer portion or the organic multilayer portion is not particularly limited, and various physical or chemical thin film forming methods can be used. Specifically, vacuum deposition method, sublimation method, coating method, casting method, spin coating method, L
There is B method.

The organic EL device (A) of the present invention is preferably sealed with a sealing film composed of a polymer film, a vapor-deposited film or a polymer film and an adhesive layer (Japanese Patent Application No. 2-409017). Japanese Patent Application No. 3-26346
No. 7). Such sealing not only prevents deterioration of the organic single layer portion or the organic multilayer portion but also improves durability of the element against bending and bending.

In the organic EL device (A) of the present invention having the above structure, 1 μm in the polymer film, at the interface between the polymer film and the first electrode and on the surface of the first electrode.
The total number of defects such as foreign matter, protrusions, holes and holes is 1
It is limited to 100 or less in converted value per m ² . The reason is that, when the total number of the above-mentioned various defects exceeds 100 in terms of a converted value per 1 m ² , not only the luminous efficiency is low and the luminous stability is inferior, as exemplified by a comparative example described later. When deformed into a curved surface, etc., problems such as short-circuit (short circuit) will occur, but when it is 100 or less in terms of conversion value per 1 m ² , luminous efficiency and luminous stability are excellent, and even when deformed into a curved surface, performance is improved. Is not changed. It is particularly preferable that the total number of various defects is 70 or less in converted value per 1 m ² .

As a method of reducing the total number of the above various defects to 100 or less in terms of a converted value per 1 m ² , the purity of the polymer film raw material is improved, the film production environment is improved (for example, use of a clean room), the film forming apparatus. (For example, improving the flatness of the film molding portion of the apparatus), cleaning by cleaning, and the like, and one or more of these can be used appropriately.

It should be noted that the above-mentioned foreign matter of 1 μm or more, protrusions,
The total number of defects such as holes and holes can be measured by observing under a microscope, observing with an electron microscope, observing with a scanning tunneling microscope, measuring with a stylus type film thickness meter or surface roughness meter, monochromatic light. Or magnified projection of a substrate using a white light source,
There are evaluations based on the in-plane distribution of transmitted light, evaluations using an optical interferometer, and evaluations using a radiation thermometer. One of these can be used as the evaluation method, but 2
It is preferable to use one or more methods.

The organic EL device (A) of the present invention comprises a polymer film and an electrode provided on the polymer film as described above, and a foreign substance, a protrusion, a hole or a hole of 1 μm or more in a supporting substrate. By limiting the total number of such defects to 100 or less in terms of a converted value per 1 m ² , high luminous efficiency is obtained, and as a result, remarkable effects such as excellent luminous stability and long device life can be obtained.

Next, the organic EL device (B) of the present invention will be described. This organic EL element (B) is the organic EL element described above.
The element (A) is different from the element (A) only in that a laminated film in which an organic or inorganic material film is laminated on the polymer film is used instead of the polymer film, and other requirements are the same. Therefore, only the laminated film will be described.

In the organic EL device (B) of the present invention, the laminated film is a polymer film laminated with an organic or inorganic material film. The polymer film used here may be the same as the polymer film used in the organic EL device (A). The material for the organic or inorganic material film laminated on the polymer film may be any material as long as it can be laminated thinly on the polymer film in the order of μm.
Specific examples thereof include organic resins such as epoxy resin, polyester, urethane resin, melamine resin and polyacrylate, inorganic oxides such as SiO ₂ and Al ₂ O ₃ , S
Examples thereof include inorganic nitrides such as iN ₄ . Lamination of these organic or inorganic materials on the polymer film is performed by any method such as a coating method, a vapor deposition method and a sputtering method.

The thickness of the laminated film in the organic EL element (B) of the present invention is the same as the thickness of the polymer film in the organic EL element (A) in order to fully utilize the flexibility of the laminated film. It is preferably 0.001 μm to 1 mm.

Also in the organic EL element (B), the total number of defects such as foreign matter, protrusions, holes, and voids of 1 μm or more in the laminated film, the interface between the laminated film and the first electrode, and the surface of the first electrode is large. Since it is limited to 100 or less in terms of converted value per 1 m ^2, it is excellent in light emission efficiency and light emission stability like the organic EL element (A), and its performance does not change even when deformed into a curved surface. It is effective.

[0028]

The present invention will be described in more detail with reference to the following examples. Example 1 Commercial PE having a size of 25 mm × 75 mm and a thickness of 0.1 mm
IT (size 20 mm × 70 mm, thickness 200 nm) on an S (polyethersulfone) film (Sumilite FS-1300 manufactured by Sumitomo Bakelite Co., Ltd.) by vapor deposition.
An O film was formed. The obtained transparent supporting substrate made of the ITO film-deposited PES film was subjected to ultrasonic cleaning in a clean room for 5 minutes in isopropyl alcohol (hereinafter referred to as IPA) and further for 5 minutes in pure water, and then UV.
Ozone cleaning was performed for 10 minutes using an apparatus manufactured by Samco International Laboratories Inc. Olympus Microscope BH
About the transparent support substrate after cleaning using 3-MJL 1
The total number of defects such as foreign matter having a size of μm or more, protrusions, holes, and holes was measured, and the total number was 50 per 1 m ² in terms of conversion value.

A transparent supporting substrate made of this ITO vapor-deposited PES film is put on a commercially available vapor deposition apparatus (manufactured by Nippon Vacuum Technology Co., Ltd.).
Fixed to the base holder of N, N'N'-bis (3-methylphenyl) -N, N 'on a resistance heating boat made of molybdenum.
-Diphenyl [1,1'-biphenyl] -4,4'-diamine (hereinafter referred to as TPD) was put in 200 mg and 4,4'-bis (2,2'-diphenylvinyl) biphenyl (hereinafter DPVBi)
Was put into the vacuum chamber and the pressure in the vacuum chamber was reduced to 1 × 10 ⁻⁴ Pa. Then, the boat with TPD is heated at 215 to 220 ° C.
To TPD and vapor deposition rate 0.1-0.3nm / s
Was vapor-deposited on the transparent supporting substrate to form a hole injection layer having a film thickness of 60 nm. At this time, the temperature of the ITO-deposited PES film was room temperature. Without removing this from the vacuum chamber, the DPVB
i was used as a light emitting layer, and 40 nm was laminated and deposited. The vapor deposition conditions are a boat temperature of 240 ° C. and a vapor deposition rate of 0.1 to 0.3 nm /
s, ITO vapor deposition PES film temperature was room temperature. This was taken out of the vacuum chamber, a stainless steel mask was placed on the light emitting layer, and it was fixed again to the substrate holder. Next, in a molybdenum boat, tris (8-quinolinol) aluminum (hereinafter referred to as Alq ₃ ) 200 m
g and put in a vacuum chamber. Further, 1 g of a magnesium ribbon was placed in a resistance heating boat made of molybdenum, and 500 mg of a silver wire was placed in a tungsten basket and vapor-deposited. Then, the vacuum chamber was decompressed to 1 × 10 ⁻⁴ Pa, and the molybdenum boat containing Alq ₃ was heated to 230 ° C.
The Alq ₃ molybdenum boat at a deposition rate of the heated 0.01~0.03nm / s up to 20nm deposited as an adhesive layer. In addition, silver was added to the tungsten basket in an amount of 0.
The vapor deposition was performed at a vapor deposition rate of 1 nm / s, and at the same time, 1.
Deposition was performed at a deposition rate of 4 nm / s. Under the above conditions, a mixed metal electrode of magnesium and silver was vapor-deposited in a thickness of 150 nm to form a counter electrode.

In this way, ITO is formed on the PES film.
Film (transparent conductive film = anode), TPD film (hole injection layer),
An organic EL device in which a DPVBi layer (light emitting layer), an Alq ₃ layer (adhesive layer) and a mixed metal electrode of magnesium and silver (cathode) were sequentially provided was obtained.

When the obtained organic EL device was made to emit light in dry air, a brightness of 350 at 10 V and 15 mA / cm ² was obtained.
A uniform light emission of cd / cm ² was confirmed. Also this organic E
The L element was deformed into a cylindrical shape having a circumference of 7 cm and a cylindrical shape having a circumference of 2.5 cm, respectively, but each maintained the same performance as described above.

Example 2 A transparent support substrate (manufactured by Sumitomo Bakelite Co., Ltd.) in which ITO was formed on a laminated film using a PES film (film thickness 100 μm) as a base film was washed with IPA in the same manner as in Example 1. After sequentially performing cleaning with pure water and UV ozone cleaning, the total number of defects such as foreign matter of 1 μm or more, protrusions, holes and holes was measured in the same manner as in Example 1, and the total number was 1 m ² per 1 m ² . The converted value was 20 pieces.

Using this transparent support substrate, an organic EL device having the same structure as in Example 1 was prepared by the same method as in Example 1. When the obtained organic EL device was made to emit light in dry air, the brightness was 350 at 10 V and 12 mA / cm ^2.
A uniform light emission of cd / cm ² was observed. Also, as in Example 1, there was no change in performance even when deformed into a cylindrical shape.

Example 3 PET having a size of 25 mm × 75 mm and a thickness of 0.1 mm
(Polyethylene terephthalate) IT of size 20 mm x 70 mm and thickness 200 nm is formed on the film by vapor deposition.
An O film was formed. The obtained transparent support substrate made of the ITO film-deposited PET film was subjected to ultrasonic cleaning in IPA for 5 minutes and then in pure water for 5 minutes in the same manner as in Example 1, and then UV ozone cleaning for 10 minutes. I did. The total number of defects such as foreign matters, protrusions, holes, and holes having a size of 1 μm or more was measured on the transparent support substrate after washing in the same manner as in Example 1. As a result, the total number was 20 per 1 m ² in terms of conversion value. Met.

Example 1 was carried out using the transparent supporting substrate after washing.
Organic E having the same structure as in Example 1 in the same manner as
An L element was produced. The obtained organic EL device was caused to emit light in dry air. As a result, uniform light emission with a brightness of 350 cd / m ² was observed at 10 V and 11 mA / cm ² . Further, even when the organic EL device was deformed into a cylindrical shape as in Example 1, no deterioration in the above performance was observed.

Example 4 The organic EL device produced in Example 1 was replaced with Teflon AF1.
5 wt% of 600 (manufactured by DuPont) was dissolved, impregnated in Fluorinert FC-75 (manufactured by 3M), pulled up, and dried in air to form a protective film of about 200 μm.
When this device with a protective film was caused to emit light in the atmosphere, uniform light emission with a brightness of 350 cd / m ² was confirmed at 10 V and 15 mA / cm ² . Further, even if the material was deformed into a cylindrical shape as in Example 1, no deterioration in the above performance was observed.

Comparative Example 1 The transparent support substrate obtained by forming an ITO film on a PES film in the same manner as in Example 1 was not subjected to the IPA cleaning, pure water cleaning, and UV ozone cleaning performed in Example 1. To
In the same manner as in Example 1, foreign matter of 1 μm or more, protrusions,
As a result of measuring the total number of defects such as holes and holes, the total number was 150 in terms of conversion value per 1 m ² . Using this transparent support substrate, an organic EL device having the same configuration as that of Example 1 was manufactured by the same method as that of Example 1.
When the obtained organic EL device was caused to emit light in dry air, the luminance was 25 cd / cm at 10 V and 180 mA / cm ^2.
Two non-uniform emission were observed. When this organic EL device was deformed into a cylindrical shape in the same manner as in Example 1, a short circuit occurred.

[0038]

As described above, according to the present invention, the luminous efficiency and the luminous stability are excellent, and the property does not change even when deformed into various shapes. Therefore, the thin film is not limited to this. An organic EL device suitable as a display device having various shapes such as a panel, a belt, and a cylinder is provided.

Claims (5)

[Claims] 1. A first electrode, an organic single-layer part or an organic multi-layer part having a light-emitting material made of an organic compound, and a second electrode are sequentially provided on a polymer film, and at least one of the two electrodes is provided. In an organic electroluminescence device in which one electrode is transparent or semi-transparent, a foreign substance, a protrusion, a hole, or a pore of 1 μm or more in the polymer film, the interface between the polymer film and the first electrode, and the surface of the first electrode An organic EL element having a total number of defects such as 100 or less in terms of a converted value per 1 m ² . 2. A first electrode, an organic single layer part or an organic multi-layer part having a light emitting material composed of an organic compound, and a second electrode on a laminated film in which an organic or inorganic material film is laminated on a polymer film. An organic electroluminescent element in which at least one of the above-mentioned two electrodes is transparent or semi-transparent, 1 μm or more in the laminated film, at the interface between the laminated film and the first electrode and on the surface of the first electrode. Foreign matter, protrusions,
An organic EL device characterized in that the total number of defects such as holes and holes is 100 or less in terms of a converted value per 1 m ² . 3. The organic EL device according to claim 1, wherein the polymer film has transparency and flexibility and is made of a polymer film having a thickness of 0.001 μm to 1 mm. 4. The organic EL device according to claim 2, wherein the organic or inorganic material film laminated on the polymer film is made of an organic polymer material or an inorganic oxide or nitride. 5. The organic EL device according to claim 1, wherein the first electrode provided on the polymer film or the laminated film is a transparent conductive film made of ITO.