JPH10289785A - Organic electroluminescent element and manufacture therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a structure and array fine luminous segments of red, green and blue by applying the constitution that a hole and/or an electron transport substance, and an organic luminous substance are doped into a matrix of a photosetting resin, as the luminous layer of an organic electroluminescent element with an anode, a luminous layer and a cathode on a transparent substrate. SOLUTION: A hole transport substance and/or an electron transport substance, and an organic luminous substance are doped into card polymer preferably shown by one of formulas I, II and III, a derivative or a mixture thereof and become a luminous layer. As a result, the photolithography pattern of an organic EL element is formed and a matrix thus prepared has thermal stability and a good thin film-forming characteristic, thereby reducing the appearance of pin holes at an electrode forming process. ITO or the like is used for the transparent electrode of an anode with a prescribed pattern formed, or preferably a double-structured thin film of an alloy thin film of Mg, Ag, AlLi or the like, and/or Mg and then Al is used for the back plate of a cathode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescence device.

[0002]

2. Description of the Related Art In recent years, electroluminescent elements (hereinafter abbreviated as EL elements) have characteristics such as high visibility due to self-emission and excellent impact resistance because they are completely solid elements. It is attracting attention as a light emitting element in the light emitting device. Further, since it is a thin-film surface emitting device capable of emitting light of each of R (red), G (green), and B (blue), application to a full-color flat panel display is expected.

This EL element includes an inorganic EL element using an inorganic compound as a light emitting material and an organic EL element using an organic compound.
Since there is a device and the operating voltage of the organic EL device can be greatly reduced, research on practical use thereof is being actively promoted.

The basic structure of an organic EL device is a structure in which an anode / light-emitting layer / cathode is formed on a transparent substrate, and there is a structure in which a hole injection layer or an electron injection layer is appropriately provided in this basic structure. . For example, anode / hole injection layer / light emitting layer / cathode,
It has a structure of anode / hole injection layer / light emitting layer / electron injection layer / cathode, etc., in which the hole injection layer has a function of transmitting holes injected from the anode to the light emitting layer, and the electron injection layer has a function of the cathode. It has a function of transmitting injected electrons to the light emitting layer. By interposing the hole injection layer between the light emitting layer and the anode, many holes are injected into the light emitting layer at a lower operating voltage, and electrons injected from the cathode or the electron injection layer into the light emitting layer. This is based on the fact that electrons are accumulated at the interface within the light emitting layer due to the barrier of electrons existing at the interface between the light emitting layer and the hole injection layer, thereby increasing the luminous efficiency ("Applied Physics Letters", Vol. 51, No. 913). Page (1987)).

There are various types of organic EL devices having a basic structure (anode / light-emitting layer / cathode).

For example, (1) a device comprising a light emitting layer in which a hole transporting material, an electron transporting material, and a light emitting material which emits light in response to recombination of holes and electrons are mixed. Is polyvinyl carbazole (PVK), and the following chemical formula is used as an electron transport material.

[0007]

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[0008] It has been disclosed that the oxadiazole derivative called PBD represented by the formula (1) uses a coumarin derivative as a luminescent substance to realize high-luminance green light emission ("Applied Physics", vol. 61, p. 1044). (1992
Year)).

(2) A device comprising a light emitting layer in which a hole transporting material, an electron transporting material, and a fluorescent material are doped into a matrix material that does not transport holes or electrons. It has been disclosed that high-intensity green light emission was realized by using an aluminum-oxine complex as an electron transport substance, a coumarin derivative as a light-emitting substance, and polymethylene methacrylate (PMMA) as a matrix ("Applied Physics"). -Letters, Vol. 61, p. 761 (1992)).

However, these devices use organic LEDs (E
L) Since photolithography patterning of the film is difficult, it is difficult to arrange fine RGB light emitting segments for full colorization. There is also room for improvement in heat resistance (durability).

[0011] For this reason, a full-color display using an organic EL element has been described using a white light-emitting organic EL device and a color filter (see “Shingaku Giho,” Vol. 94, 53).
No. 5, page 1 (1995)) and those using a blue organic EL element and a wavelength tunable element (“IEICE Tech.
No. 35, p. 13 (1995)).

However, since a filter or a wavelength conversion element is used, there are problems that the system becomes complicated and the luminous utilization efficiency (the ratio of using the luminescence of the luminous element as panel luminance) is poor.

Although a method using a microresonator structure has been proposed ("Applied Physics Letters", Vol. 63, p. 594 (1993)), the cost of the process for manufacturing a microresonator is added. The color shifts depending on the viewing angle.

[0014]

As described above, it has been difficult to perform photolithography patterning of an organic LED (EL) film in conventional organic electroluminescence device manufacturing, and therefore, it has been difficult to obtain fine RGB It was difficult to arrange the luminescent segments.

[0015]

As a result of various studies, the present inventors have found that a certain cardo polymer, namely, a compound of formula I

[0016]

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Or chemical formula II

[0018]

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Or chemical formula III

[0020]

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The compound represented by the formula (I), a derivative thereof or a mixture thereof is a compound having a hole transporting substance, an electron transporting substance,
And doping (molecular dispersion) of organic luminescent materials,
In addition, it was discovered that the material could be photolithographically patterned.

Utilizing this, in an organic EL device having an anode / light emitting layer / cathode structure on a transparent substrate, a hole transporting material and / or an electron transporting material and an organic light emitting material are used as a light emitting layer in a matrix. By doping the compound represented by the above-mentioned chemical formula I, the chemical formula II or the chemical formula III, a derivative thereof, or a mixture thereof, photolithographic patterning of an organic LED (EL) film becomes possible, The inventors have found that an arrangement of RGB light-emitting segments can be realized, and have reached the invention. This matrix also
Since it is thermally stable, a uniform and dense film having excellent thin film properties can be formed, and pinholes are not easily generated during electrode formation, heat resistance (long life) can be expected.

Further, for the purpose of improving the durability, it is possible to seal with a resin in order to block moisture or oxygen, or to deposit a thin film of germanium dioxide.

That is, the present invention, which is a means for solving the above problems, provides (1) an organic electroluminescent device having a transparent electrode / light emitting layer / back electrode structure on a transparent substrate, wherein the light emitting layer comprises a hole transporting substance and / or Alternatively, the present invention is attained by an organic electroluminescence device comprising a phase in which an electron transporting substance and an organic light emitting substance are doped (molecularly dispersed) in a photocurable resin.

Further, the present invention provides (2) a transparent substrate,
In an organic electroluminescence device having a structure of a transparent electrode / a light emitting layer / a back electrode, the light emitting layer has a hole transporting substance and / or an electron transporting substance and an organic light emitting substance represented by the above chemical formula I or II or III. The present invention is also achieved by an organic electroluminescence device comprising a phase doped (molecularly dispersed) in a compound, a derivative thereof, or a mixture thereof.

Further, the present invention provides (3) a method in which a hole transporting material and / or an electron transporting material and an organic luminescent material are formed on a transparent substrate on which a transparent electrode is formed in a predetermined pattern;
Alternatively, a compound represented by Formula II or Formula III or a derivative thereof or a mixture thereof is dissolved and mixed with a solvent, and the solution is applied and dried to form a thin film, which is then exposed using a mask having a predetermined pattern. Immersion in a non-cured material-soluble solvent such as dichloroethane to remove the non-cured material to form a light emitting layer, and then further on the light emitting layer,
The present invention is also achieved by a method for manufacturing an organic electroluminescent element, wherein a back electrode is formed and, if necessary, the back electrode is patterned by an etching method.

Furthermore, the present invention provides (4) a method for solving the problems described in the above (2), wherein
The present invention is also achieved by an organic electroluminescence device characterized by using an alloy thin film of MgAg, AlLi or the like and / or a thin film having a two-layer structure of Mg and then Al.

The present invention provides (5) a method for solving the problems described in (1) and (2) above, wherein DCM1 and / or Nile Red are used as the red light-emitting material as the organic light-emitting material, and coumarin is used as the green light-emitting material. 6, at least one member selected from the group consisting of coumarin 7, and an aluminum-oxine complex;
The present invention is also achieved by an organic electroluminescence device using PB (1,1,4,4-tetraphenyl-1,3-butadiene).

[0029]

Next, the present invention will be described in detail.

As the transparent substrate, a substrate made of glass or transparent resin (for example, polyether sulfone, polyarylate) can be used.

The electrode on the substrate side must be a transparent electrode, for example, Indium Tin Oxide
(ITO) can be used.

As the light emitting layer, a hole transporting material and / or an electron transporting material and an organic light emitting material are combined with the above-mentioned chemical formula I or II or III as a matrix.
Or a compound thereof, a derivative thereof, or a mixture thereof. The hole transporting substance, the electron transporting substance, and the organic luminescent substance are not particularly limited as long as they are molecularly dispersed in a matrix and are stable. In particular,
The hole transporting materials include triphenylenediamine derivatives (TPD) and PVK, the electron transporting materials include aluminum oxine complex (Alq) and oxadiazole derivatives, and the organic luminescent materials include the following for R (red): Chemical formula

[0033]

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DCM1, phenoxazone, Nile Red, etc. represented by the following formulas were used for coumarin 6 and coumarin 7 for G (green).
For B (blue), compounds such as oxadiazole derivatives, tetraphenylcyclopentadiene, tetraphenylbutadiene, Zn (oxz) ₂ ; oxz = oxazole can be used. The amount of the organic light emitting substance varies greatly depending on the light emitting substance, but is generally 0.000% of the total solid content.
It is between 1% and 60% by weight. Generally, it is preferably around 1% by weight.

As the back electrode, an alloy thin film such as MgAg and AlLi, a thin film having a two-layer structure of Mg and then Al, and a thin film such as Al can be used.

The above-mentioned organic EL device can be manufactured basically in the following steps.

(1) First, ITO transparent electrodes are formed on the transparent substrate in a streak shape at a predetermined pitch. The pitch is determined by the size of the panel used. For example, if it is 20 inches, it is about 200 μm.

(2) Next, the chemical formula I or the chemical formula
A compound represented by Formula II or Formula III, a derivative thereof, or a mixture thereof is prepared. This and an organic light emitting substance, a hole transporting substance and an electron transporting substance are dissolved and mixed in a solvent to prepare a light emitting layer forming solution. As a solvent, chloroform, dichloroethane, n-methylpropane, N
-Methylpyrrolidone and the like can be used.

Using the solution, a substrate on which a transparent electrode such as ITO is formed is applied and dried to form a light emitting layer. Various film forming methods such as a spin coating method and a dipping method can be applied to the film forming method.

(3) Next, the substrate on which the light emitting layer is formed is exposed and exposed using a mask having a predetermined pattern.
Develop with chloroform, dichloroethane, n-methylpropane, etc. (solvents that dissolve non-cured products). 365 nm is suitable as light for exposure, but a shorter wavelength may be used.

(4) Finally, a back electrode is formed in a predetermined pattern. For example, for a simple matrix, IT
It is formed so as to cross the O transparent electrode. The back electrode is
Generally, an evaporation method is used, but it is not necessary to limit to this. The formed electrode film is arranged in a predetermined pattern by edging to form an element. The patterning accuracy is about ± 5 μm. 1 and 2 show a schematic cross-sectional view and a perspective view of a basic structure of an organic EL element (panel).

(5) In consideration of durability and handleability, it is appropriately sealed with resin, germanium dioxide or the like.

[0043]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following is a description of a specific simple example.

Example 1 To 320 g of 1,2-dichloroethane; 2 g of the compound represented by the above formula I; and Irgacure 907 (a radical polymerization initiator manufactured by Ciba-Geigy Co .; need not be added); 0.1 g; , TPD; 0.9 g, Alq (aluminum / oxine complex); 1.2 g, and mixed with stirring to dissolve.

Next, the glass substrate on which the ITO transparent electrode was formed was washed, the above solution was applied on the entire surface by spin coating, and dried at 80 ° C. for 30 seconds to form a film of 1000 °. Next, a disc-shaped mask having a diameter of 10 mm was set at the center of the coated substrate, and exposed to ultraviolet light of 200 to 1000 mj. Then, the coated substrate was immersed in 1,2-dichloroethane, and a light emitting layer was formed only at the center. Was formed.

Next, only the central portion has a diameter of 5 m similar to that of the light emitting layer.
A disk-shaped mask having a diameter of 5 mm was formed on the center of a disk-shaped mask having a thickness of 5 mm.

The dimensional accuracy of the disk-shaped electrode and the light emitting layer formed at the center was 5 μm or less.

When a voltage of 15 V DC was applied to the fabricated device, clear green light emission was observed.

Example 2 An element was prepared under the same conditions as in Example 1 except that 0.16 g of coumarin 6 was further added as a solution for the light emitting layer.

An element having the same dimensional accuracy as that of Example 1 was obtained, emitted a slightly bright green light, and similar results were obtained for other light emitting characteristics.

Example 3 A device was prepared under the same conditions as in Example 2 except that DCM1 was used instead of coumarin 6 as a luminescent agent as a luminescent layer solution.

An element having the same dimensional accuracy as that of Example 1 was obtained, and similar results were obtained in red and other light emission characteristics.

Example 4 An element was prepared under the same conditions as in Example 2 except that tetraphenylbutadiene was used instead of coumarin 6 as a luminescent agent as a luminescent layer solution.

An element having the same dimensional accuracy as that of Example 1 was obtained, and a similar result was obtained in blue light emission characteristics.

[0055]

As described above, by using the compound represented by the above formula I, II or III or a derivative thereof or a mixture thereof as the matrix material of the light emitting layer, it has a simple structure and a fine structure. An organic EL device capable of realizing an RGB light-emitting segment arrangement was realized.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a basic structure of an organic EL device (panel) of the present invention.

FIG. 2 is a schematic perspective view showing a basic structure of an organic EL element (panel) of the present invention.

[Explanation of symbols]

 1: back electrode, 2: light emitting layer, 3: transparent electrode (ITO), 4: glass substrate.

Claims (5)

[Claims] 1. An organic electroluminescence device having a transparent electrode / light-emitting layer / back electrode structure on a transparent substrate, wherein the light-emitting layer comprises a light-emitting material comprising a hole transport material and / or an electron transport material and an organic light-emitting material. Doping of curable resin (molecular dispersion)
An organic electroluminescence device comprising a phase that has been formed. 2. An organic electroluminescent device having a transparent electrode / light-emitting layer / back electrode structure on a transparent substrate, wherein the light-emitting layer has a chemical formula of a hole transport material and / or an electron transport material and an organic light-emitting material. I Or chemical formula II Or Formula III: An organic electroluminescence device comprising a phase doped (molecularly dispersed) in a compound shown in (1) or a derivative thereof or a mixture thereof. 3. A hole transporting substance and / or an electron transporting substance and an organic luminescent substance on a transparent substrate on which a transparent electrode is formed in a predetermined pattern.
The compound shown in I or a derivative thereof or a mixture thereof is dissolved and mixed with a solvent, and the solution is applied and dried to form a thin film, which is then exposed using a mask having a predetermined pattern. A luminescent layer is formed by immersing the cured product in a solvent in which the cured product is soluble to remove the non-cured material, and then a back electrode is further formed on the luminescent layer, and if necessary, the back electrode is patterned by an etching method. Of manufacturing an organic electroluminescent device. 4. The back electrode according to claim 2, wherein
An organic electroluminescence device characterized by using a thin film of an alloy such as MgAg and AlLi and / or a thin film of Mg followed by Al. 5. The method according to claim 1, wherein at least one selected from the group consisting of DCM1 and / or Nile Red as a red light emitting material and coumarin 6, coumarin 7, and an aluminum oxine complex as a green light emitting material. TPB (1,1,4,4-
An organic electroluminescent device characterized by using tetraphenyl-1,3-butadiene).