JPH11251070A - Manufacturing method of organic electroluminescent device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the adhesiveness of a film formation preventing layer made of a resist material by forming first electrodes in a substrate in a patter shape, and roughening substrate faces located between the first electrodes. SOLUTION: For patterning a first electrode layer 2 and for roughening a substrate 1, the gap portions of the first electrode layer 2 are roughened to form the first electrode layer 2 in advance, then the first electrode layer 2 is patterned, or the first electrode layer 2 is formed on the substrate 1, then the first electrode layer 2 is patterned and the substrate faces between electrodes are roughened. When the substrate 1 is roughened in advance, the substrate 1 is spin-coated with a liquid resist, it is pattern-exposed and developed to form a resist pattern, it is dipped in an acid solution for roughening, then the resist is removed to form the first electrode layer 2 at the upper section. A resist film is formed, a pattern exposure is applied to it, and the first electrode layer 2 is machined to manufacture a desired substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent device, and more particularly, to a thin film type light emitting device which emits light by applying an electric field to a light emitting layer made of an organic compound.

[0002]

2. Description of the Related Art In recent years, research and development of organic electroluminescent elements have been actively conducted, and studies on panel formation have been repeated. For example, (1) a method of forming a first electrode on a substrate Is formed, an organic light emitting layer is formed (in this case,
If necessary, a hole transport layer and the like are laminated. ),next,
A method of forming a second electrode cathode using a shadow mask by a vacuum deposition method or the like. (2) A method of forming a first electrode on a substrate in the same manner as in (1), pattern-depositing an organic film using a shadow mask, and exchanging the second electrode with a mask for a second electrode to pattern-deposit a second electrode. . (3) A method in which a wall (film formation preventing layer) for preventing film formation is prepared in advance on a substrate using a resist or the like, and the light emitting layer and the second electrode layer are patterned by vapor deposition or the like. (JP-A-5-275172).

In a patterning method using a shadow mask, it is necessary to accurately align the substrate and the mask with a precision of several μm in a chamber in a vacuum apparatus, and the operation is not easy. In addition, there is also a problem that a substance attached to a mask used for repeated vapor deposition becomes thicker and the pattern of the mask is narrowed. From this point of view, a method in which a wall is prepared in advance and an organic layer and an electrode are patterned by vapor deposition is a preferable method at present.

[0004]

In a method of performing patterning using a film formation preventing layer, a resist material is often used as a material for a wall. At present, these resist materials have a problem in adhesion to the substrate, but especially when producing narrow walls using dry film resist.
At present, peeling of the pattern occurs and the adhesion is insufficient.

[0005]

An organic electroluminescent device according to the present invention has a structure in which at least a first electrode, an organic layer, and a second electrode are laminated on a substrate, and the first electrode is disposed in a plane of the substrate. It is characterized in that it is formed in a pattern and the substrate surface located between the first electrodes is roughened.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing an organic electroluminescent device according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view schematically showing an example of an organic electroluminescent device manufactured by the present invention, wherein 1 is a substrate, 2 is a first electrode layer (anode), 3 is a film formation preventing layer, and 4 is a positive electrode. The hole transport layer, 5 represents an organic light emitting layer, and 6 represents a second electrode layer (cathode). The substrate 1 serves as a support for the organic electroluminescent device according to the present invention, and may be a quartz or glass plate, a metal plate or metal foil, a plastic film or sheet, or the like. Transparent synthetic resin substrates such as acrylate, polycarbonate and polysulfone are preferred.

A first electrode layer (anode) 2 is provided on a substrate 1. This anode is usually made of aluminum, gold, silver,
Metals such as nickel, palladium, and tellurium; metal oxides such as oxides of indium and / or tin; and copper iodide;
It is made of carbon black or a conductive polymer such as poly (3-methylthiophene). The formation of the first electrode layer as the anode is usually performed by a sputtering method, a vacuum evaporation method, or the like, but metal fine particles such as silver or copper iodide, carbon black, conductive metal oxide fine particles, When using fine particles of conductive polymer, etc., these are dispersed in an appropriate binder resin solution,
It can also be formed by coating on a substrate. Further, when a conductive polymer is used, a thin film can be formed directly on a substrate by electrolytic polymerization or can be formed by coating on a substrate (Appl. Phys. Lett., 6).
0, 2711, 1992). The first electrode layer (anode) 2 may have a laminated structure of two or more layers of different substances. The thickness of the first electrode layer (anode layer) 2 varies depending on the required transparency. If transparency is required, the visible light transmittance is 60% or more, preferably 80%.
It is desirable that the light be transmitted as described above. In this case, the thickness of the first electrode layer (anode) 2 is usually about 5 to 1000 nm, preferably about 10 to 500 nm.

First electrode layer (anode) 2 laminated on a substrate
Are formed in a pattern. The method of patterning the first electrode and roughening the substrate surface is as follows: (1) First, a portion to be a gap between the first electrodes is roughened, and after the first electrode is formed, the first electrode is patterned. (2) a method of forming a first electrode on a substrate and roughening the substrate surface between the electrodes simultaneously with the patterning of the first electrode, and (3) forming a first electrode on the substrate. There is a method of roughening the substrate surface between the electrodes after forming a film and performing pattern processing. As the method (1), for example, first, a liquid resist is spin-coated on a glass substrate, and after pattern exposure, development is performed to form a resist pattern. The resist used at this time may be a liquid resist, a dry film resist, or the like. As an example of a liquid resist, MCPR2000H
(Manufactured by Mitsubishi Chemical Corporation). Examples of the dry film resist include ALPHO (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and RISTON (Dupont MRC).
PHOTEC (manufactured by Hitachi Chemical Co., Ltd.),
SUNFORT (manufactured by Asahi Chemical Industry Co., Ltd.) and the like.

The glass surface of the substrate manufactured in this way is roughened.
Method of immersion in acid solution, method by sand blast,
A method by plasma etching in which a reactive gas is introduced can be used. The resist on the substrate thus produced is removed, and a first electrode is produced on the upper part. Further, a resist film is formed, pattern exposure is performed, the first electrode is processed, and a desired substrate is manufactured. As a method for processing the first electrode, the above-described method for roughening a glass substrate can be applied.

As a method (2), for example, a dry film resist is laminated on a first electrode formed on a glass substrate, and after pattern exposure, development is performed to form a resist pattern. Using this mask, patterning of the first electrode and processing of the substrate surface are performed. In the same manner as in the first method, a method of dipping in an acid solution, a method by sandblasting, and a reactive gas are introduced. A method by plasma etching or the like can be used. As the method (3), for example, a dry film resist is laminated on a first electrode formed on a glass substrate, and after pattern exposure, development is performed to form a resist pattern. Using this mask, the first electrode is processed by a method of dipping in an acid solution, a method by sandblasting, a method by plasma etching in which a reactive gas is introduced, or the like. Using this mask, the substrate is subjected to a surface roughening process using a method different from the first electrode processing method.
At this time, the mask may be formed again. A substrate having a roughened surface between the first electrode patterned in this way and the substrate between the first electrodes is manufactured. The roughness of the roughened portion of the substrate may be such that the adhesion of the film formation preventing layer formed thereon is improved, but the center line average roughness (JIS B 0
601) is preferably 3 nm or more and 300 nm or less.

On this substrate, a film formation preventing layer 3 is formed in a direction orthogonal to the first electrode. Examples of the film formation preventing layer include a method of forming an overhang shape using an image reversal resist, a dry film resist, or the like. Examples of the image reversal resist include AZ-5214 manufactured by Hoechst. As a material of the hole transport layer 4 formed separately on the anode layer 2 by the film formation preventing layer 3, the hole injection efficiency from the anode 2 is high and the injected holes are efficiently transported. It must be a material that can be used. For that purpose, it is required that the ionization potential is small, the hole mobility is large, the stability is further excellent, and impurities serving as traps are hardly generated during production or use.

Examples of such a hole transport compound include, for example, JP-A-59-194393 and US Pat.
175,960, U.S. Pat. No. 4,923,774 and U.S. Pat. No. 5,047,687;
N'-diphenyl-N, N '-(3-methylphenyl)
-1,1'-biphenyl-4,4'-diamine: 1,
1'-bis (4-di-p-tolylaminophenyl) cyclohexane: an aromatic amine compound such as 4,4'-bis (diphenylamino) quadrophenyl;
Examples include hydrazone compounds disclosed in 311591, silazane compounds and quinacridone compounds disclosed in U.S. Pat. No. 4,950,950. These compounds may be used alone or, if necessary, may be used as a mixture.

The hole transport layer 4 is formed by laminating the above organic hole transport material on the anode layer 2 mainly by a vacuum evaporation method. The organic hole transporting material is put into a crucible placed in a vacuum vessel, and the inside of the vacuum vessel is evacuated to a level of 10 ⁻⁶ Torr by a suitable vacuum pump, and then the crucible is heated to remove the hole transporting material. Evaporate to form a hole transport layer 4 on the anode layer 2 on the substrate 1 placed facing the crucible. The thickness of the hole transport layer 4 thus formed is
Usually, 10 to 300 nm, preferably 30 to 100 nm
It is. In order to form such a thin film uniformly, a vacuum evaporation method is often used.

As the material of the hole transport layer 4, an inorganic material can be used instead of an organic compound. The conditions required for the inorganic material are the same as those for the organic hole transport compound. Examples of the inorganic material used for the hole transport layer 4 include p-type hydrogenated amorphous silicon, p-type hydrogenated amorphous silicon carbide, p-type hydrogenated microcrystalline silicon carbide, p-type zinc sulfide, and p-type zinc sulfide. Zinc selenide and the like.
These inorganic hole transport layers are formed by CVD, plasma CVD.
It is formed by a method, a vacuum deposition method, a sputtering method, or the like. The thickness of the inorganic hole transport layer is usually 10
３００300 nm, preferably 30-100 nm.

The organic light emitting layer 5 formed on the hole transport layer 4 efficiently transports electrons from the second electrode layer (cathode) 6 between the electrodes to which an electric field is applied in the direction of the hole transport layer. Formed from compounds that can The compound used for the organic light emitting layer 5 needs to be a compound having a high electron injection efficiency from the second electrode layer (cathode) 6 and capable of efficiently transporting the injected electrons. For that purpose, it is required that the compound has a high electron affinity, a high electron mobility, and is excellent in stability, and hardly generates impurities serving as traps during production or use. Further, a role of emitting light at the time of recombination of holes and electrons is also required. Furthermore, providing a uniform thin film shape is also important from the viewpoint of device stability.

The material of the organic light emitting layer 5 is as follows.
Aromatic compounds such as tetraphenylbutadiene (JP-A-57-51781) and metal complexes such as aluminum complexes of 8-hydroxyquinoline (JP-A-59-194)
No. 393, U.S. Pat. No. 5,151,629, U.S. Pat. No. 5,141,671), cyclopentadiene derivative (JP-A-2-289675), perinone derivative (JP-A-2-289676), Oxadiazole derivatives (JP-A-2-216791), bisstyrylbenzene derivatives (JP-A-1-245087),
JP-A-2-222484), perylene derivatives (JP-A-2-189890, JP-A-3-791), coumarin compounds (JP-A-2-191694, 3-7)
No. 92), rare earth complexes (JP-A-1-256658).
4), distyrylpyrazine derivatives (JP-A-2-2527)
No. 93), p-phenylene compound (JP-A-3-33)
183), a thiadiazolopyridine derivative (JP-A-3-37292), a pyrrolopyridine derivative (JP-A-3-37293), a naphthyridine derivative (JP-A-3-203982), and the like. Particularly, a metal complex formed from 8-hydroxyquinoline and a derivative thereof is preferable. As the central metal of the metal complex, Al, Ga, In, Sc, Y, Zn, Be, M
g and Ca are preferred. These metal complexes may be used alone or as a mixture of two or more as needed.

The organic light emitting layer 5 is formed by using these materials in the same manner as the organic hole transporting layer 4, but is preferably formed by a vacuum evaporation method.
It is 10 to 200 nm, preferably 30 to 100 nm. In the organic light emitting layer, for the purpose of improving the luminous efficiency of the device and changing the luminescent color, for example, an aluminum complex of 8-hydroxyquinoline is used as a host material.
Doping with a fluorescent dye for laser such as coumarin (J.
Appl. Phys. 65, 3610, 1989.
Year). Also in the present invention, an organic phosphor such as a laser dye is added to the above organic light emitting layer in an amount of 10 ⁻³ to 10 mol%.
By doping, the light emitting characteristics of the device can be further improved. Also in the case of doping the organic light emitting layer with a fluorescent dye, the stability of the device is further improved by setting the substrate temperature in the range of 60 ° C. to 150 ° C.

On the organic light emitting layer 5, a second electrode layer (cathode) 6 is formed. The second electrode layer (cathode) 6 plays a role of injecting electrons into the organic light emitting layer 5. The material used as the second electrode layer (cathode) 6 is preferably a metal having a low work function, and generally, tin, magnesium, indium,
A suitable metal such as aluminum or silver or an alloy thereof is used. The second electrode layer (cathode) 6 may also have a laminated structure of two or more layers of different substances. The film thickness of the second electrode layer (cathode) 6 is generally the same as that of the anode layer 2. However, in the electroluminescent element, at least one of the first electrode layer (anode) 2 and the second electrode layer (cathode) 6 needs to have good transparency.
And one or both of the second electrode layer (cathode) 6 and 10 to 50
It is desired that a film having a thickness of about 0 nm has excellent transparency.
Note that the organic electroluminescent device shown in FIG. 1 is an embodiment of the organic electroluminescent device of the present invention, and the present invention is not limited to the illustrated one as long as it does not exceed the gist.

For example, as the layer configuration formed on the substrate, the following (1) to (6) can be adopted. (1) anode / organic hole transport layer / organic light emitting layer / cathode (2) anode / inorganic hole transport layer / organic light emitting layer / cathode (3) anode / organic light emitting layer / electron transport layer / cathode (4) anode / Organic hole transport layer / organic light emitting layer / electron transport layer / cathode (5) anode / organic hole transport layer / organic light emitting layer / interface layer /
Cathode (6) Anode / Organic hole transport layer / Organic light emitting layer / Electron transport layer / Interface layer / Cathode In the above layer configuration, the electron transport layer is for further improving the efficiency of the device, and the organic light emitting layer It is laminated on.
The compound used in the electron transport layer is required to be capable of easily injecting electrons from the cathode and having a higher electron transport ability. Such an electron transporting material includes an oxadiazole derivative (App) as shown in the following structural formula.
l. Phys. Lett. 55, 1489, 19
89; Jpn. J. Appl. Phys. , Volume 31,
1812, 1992) or a system in which they are dispersed in a resin such as PMMA (Appl. Phys. Lett., 61).
Vol., P. 2793, 1992), or n-type hydrogenated amorphous silicon carbide, n-type zinc sulfide, n-type zinc selenide, and the like. The thickness of the electron transport layer is usually 5 to 200
nm, preferably 10 to 100 nm.

[0020]

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[0021]

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In the above layer structure, the interface layer is for improving the stability of the device.
Aromatic diamine compounds (Japanese Patent Application No. 5-48075);
Quinacridone compounds (Japanese Patent Application No. 5-116204), naphthacene derivatives (Japanese Patent Application No. 5-116205), organic silicon compounds (Japanese Patent Application No. 5-116206), organic phosphorus compounds (Japanese Patent Application No. 5-116207), etc. Can be mentioned. The thickness of the organic interface layer is usually 2 to 100 n.
m, preferably 5 to 30 nm. Further, as the inorganic material, for example, lithium fluoride is 0.5 nm to 1.0 n
m, and aluminum was further evaporated thereon to reduce the voltage of the device.
Appl. Phys. Lett. 70 (2), 199
7) The result of similarly lowering the voltage of the element by vapor-depositing 0.6 to 1.2 nm of aluminum, exposing it to the atmosphere once, forming aluminum oxide by natural oxidation, and further vapor-depositing aluminum is also shown. It has been reported (p12
33, Appl. Phys. Lett. 70 (10),
1997).

Further, on the upper part of the aluminum cathode,
In order to reduce the resistance of the electrode, an electric resistance reducing layer can be provided. As the electric resistance reducing layer, a metal having an electric resistivity of 10 μΩ · cm or less is preferable, and examples thereof include metals such as gold, silver, and copper. The thickness of the electric resistance reducing layer is usually 20 nm to 10 μm, preferably 30 nm.
m to 2 μm. The structure opposite to that of FIG.
A first electrode layer (cathode) 2, an organic light emitting layer 5, a hole transport layer 4, and a second electrode layer (anode) 6 can be laminated on the substrate in this order, and the above (1) to (6) It is also possible to provide a layer configuration of such an organic electroluminescent device.

[0024]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Experimental Examples, Examples, Comparative Experimental Examples, and Comparative Examples. However, the present invention is limited by the following Examples unless it exceeds the gist thereof. It is not something to be done. First, an example of roughening a substrate will be described.

EXPERIMENTAL EXAMPLE 1 A Corning 7059 glass substrate was ultrasonically cleaned with acetone and isopropyl alcohol for 10 minutes, and then dried with dry nitrogen.
(Manufactured by Mitsubishi Chemical Corporation) is spin-coated at about 1 μm, pattern-exposed, and developed in a 2.38% aqueous solution of tetramethylammonium hydroxide (hereinafter abbreviated as TMAH) for 1 minute to form a pattern. The obtained resist film was obtained. The substrate was immersed in a 6N aqueous solution of hydrochloric acid (solution temperature: 50 ° C.) for 25 minutes, and the resist was stripped in an aqueous solution of 20% TMAH. The roughness of the part subjected to the surface roughening has a center line average roughness (hereinafter abbreviated as Ra) of 12 n.
m. The roughness of the part protected by the resist was 0.5 nm in Ra.

Example 2 ITO was applied to a Corning 7059 glass substrate by about 200 nm.
Prepare the substrate with acetone and isopropyl alcohol.
After ultrasonic cleaning for 0 minutes, MCPR2000H (Mitsubishi Chemical Co., Ltd.) as a positive resist is applied on a substrate dried with dry nitrogen.
Was spin-coated to a thickness of about 1 μm. The substrate was subjected to pattern exposure, and developed using a 2.38% TMAH aqueous solution. The substrate thus prepared was immersed in a 6N aqueous solution of hydrochloric acid (solution temperature: 50 ° C.) for 25 minutes to form a stripe-shaped ITO and an IT
The surface of the glass substrate on which O was etched was roughened.
After the treatment, the resist was stripped with an aqueous solution of TMAH 20%, and further washed with water. The surface roughness of the glass substrate without the surface treatment was 0.5 nm in Ra, whereas the surface roughness of the glass substrate after the treatment was 4.7 nm in Ra.

Example 3 ITO was applied to a Corning 1737 glass substrate at about 120 nm.
A dry film was laminated on the laminated substrate, and developed after pattern exposure. This substrate was processed by sandblasting. At this time, the processing conditions were as follows:
Spraying was performed for about 30 seconds using White Morundum WA # 2000 (average particle size 0.008 mm) as an abrasive. The substrate thus treated is subjected to ITO patterning and, at the same time, roughening the glass substrate surface between the ITO patterns. The roughness of the glass surface at this time was 146 nm in Ra. Next, an example of actual patterning will be described.

Example 4 A dry film resist (ALPHO15G251: manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was applied to the substrate prepared in Example 3.
(Thickness: 15 μm) was laminated twice to produce a 30 μm-thick resist. This substrate was subjected to pattern exposure and development to form a dry film pattern having a width of 30 μm and a pitch of 310 μm. The substrate was washed with ultrapure water, subjected to UV / ozone treatment, and then placed in a vacuum deposition apparatus. An oil equipped with a liquid nitrogen trap was used until the degree of vacuum in the apparatus became 2 × 10 ⁻⁶ Torr or less. After evacuating using a diffusion pump, the following structural formula (I-
Copper phthalocyanine shown in 1) was deposited on the substrate to a thickness of 20 nm. At this time, the deposition rate was 0.3 nm / sec.

[0029]

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Next, N, N'-diphenyl-N, N'- represented by the following structural formula (H-1) is used as an organic hole transport layer material.
(Α-naphthyl) -1,1′-biphenyl-4,4′-
Diamine was put in a ceramic crucible, and heated by a tantalum wire heater around the crucible to perform vapor deposition. The temperature of the crucible at this time was controlled in the range of 160 ° C to 170 ° C.
The degree of vacuum at the time of deposition is 2 × 10 ⁻⁶ Torr, and the deposition time is 3
An organic hole transport layer 3 having a thickness of 60 nm was obtained in 10 minutes.

[0031]

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Next, as the material of the organic light emitting layer, the above-mentioned organic hole transport was carried out by using aluminum 8-hydroxyquinoline complex represented by the following structural formula (E-1), Al (C ₉ H ₆ NO) ₃ . Evaporation was performed on the layer in the same manner. At this time, the temperature of the crucible was controlled in the range of 230 to 270 ° C. The degree of vacuum during the deposition is 2 × 10 ⁻⁶ Torr, and the deposition time is 3 minutes 30
Second, the film thickness was 75 nm.

[0033]

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Further, about 0.5 nm of magnesium fluoride was formed as an interface layer, and about 40 nm of aluminum was stacked as a cathode. Further, a 40 nm layer of copper was formed thereon as an electric resistance reducing layer. At this time, the degree of vacuum was 1.5 × 10 ⁻⁵ Torr. When a voltage of 10 V was applied with the ITO side of the element fabricated in this way as the positive electrode and the laminated cathode side of magnesium fluoride, aluminum and copper as the negative electrode, no light was emitted in the non-selected part and light emission was obtained only in the selected part. Was done.

Comparative Example 2 A pattern was formed on the substrate prepared in Comparative Example 1 with a dry film resist film in the same manner as in Example 4, and the pattern was peeled from the substrate. Example 4 was further applied to this substrate.
When the organic layer and the cathode layer were formed in the same manner as in the above, patterning of the element was not performed, and the element in the non-selected portion also emitted light.

[0036]

As described above in detail, according to the organic electroluminescent device of the present invention, in the fine processing using the film formation preventing layer of the organic electroluminescent device, the film is formed by roughening the substrate. The adhesion between the prevention layer and the substrate is increased, and a thin film formation prevention layer can be formed. This leads to an increase in the aperture ratio of the panel, and a brighter panel can be provided. Therefore, the organic electroluminescent device according to the present invention can be applied to a flat panel display (for example, for an OA computer or a wall-mounted television), a display board, a guide board, and a sign lamp, and its technical value is great.

[Brief description of the drawings]

FIG. 1 is a perspective view showing components of an organic electroluminescent device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 1st electrode layer (anode) 3 Film formation prevention layer 4 Hole transport layer 5 Organic light emitting layer 6 2nd electrode layer (cathode)

Claims (2)

[Claims] 1. A structure having at least a first electrode, an organic layer, and a second electrode laminated on a substrate, wherein the first electrodes are formed in a pattern on the surface of the substrate, and An organic electroluminescent device, characterized in that the surface of the substrate located at (1) is roughened. 2. The organic electroluminescent device according to claim 1, wherein the center line average roughness (Ra) of the roughened substrate surface is from 3 nm to 300 nm.