JPH0822891A - Organic electroluminescent element and its manufacture - Google Patents

Abstract

PURPOSE:To provide an organic electroluminescent element which has an excellent emission characteristic that undergoes little aged deterioration by sealing an anode, a Hall transport layer, an emitter layer and a cathode with a thermoplastic high polymer film. CONSTITUTION:Nylon 6 or the like is used as a thermoplastic high polymer film 6 to prevent impurities from the atmosphere from entering a Hall transport layer 3 and an emitter layer 4. In a vacuum where the Hall transport layer 3, the emitter layer 4 and a cathode 5 are formed, the thermoplastic high polymer film is also formed at the same time by evaporation method. An ITO- equipped glass substrate 1 is etched by aqua regia to form an anode 2 of ITO2. After a specific process, the Hall transport layer 3 about 500Angstrom thick is formed over the anode 2 by vacuum evaporation. The emitter layer 4 about 500Angstrom thick is formed over the Hall transport layer 3 with trisaluminum as an evaporation source, and the cathode 5 is formed with Mg and Ag as evaporation sources. Finally, the layers are sealed by the thermoplastic high polymer film 6 with nylon 11 and Rilsan-BM as evaporation sources.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescence element used for a backlight of a liquid crystal display, a display, a light source for optical communication, etc., and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, a light emitting element utilizing the electroluminescence of a solid fluorescent substance has been widely used. There are inorganic and organic solid fluorescent substances, but inorganic materials are used for the backlight of liquid crystal displays. Organic materials have also been studied for a long time. The organic material can obtain various emission wavelengths including blue emission by changing the light emitting material and the layer structure. The organic electroluminescent device proposed by Tang et al. In 1987 operates at direct current.
A high brightness of 1000 cd / m ² or more was realized at a low voltage of 0 V or less. Furthermore, much research is being conducted toward the practical application of organic electroluminescent devices (C.W.
Tang and S. A. Vanslyke: App
l. Lett. , 51 (1987) 913).

A conventional organic electroluminescence device will be described below. FIG. 2 is a sectional view of a conventional organic electroluminescence device. In FIG. 2, 1
Is a glass substrate, and 2 is an anode made of a transparent electrode such as ITO (indium tin oxide), SnO: Sb, ZnO: Al. No. 3 has a high hole mobility, good film-forming property, and is transparent, and the porphine and tetraphenylporphine copper described in JP-A-4-129191, JP-A-4-255692 and JP-A-4-132189 are used. ,
Porphyrin compounds such as phthalocyanine, copper phthalocyanine, titanium phthalocyanine oxide, 1,1-
Bis {4- (di-P-tolylamino) phenyl} cyclohexane, 4,4 ′, 4 ″ -trimethyltriphenylamine, N, N, N ′, N′-tetrakis (P-tolyl) -P-phenylenediamine , 1- (N, N-di-P
-Tolylamino) naphthalene, 4,4'-bis (dimethylamino) -2,2'-dimethyltriphenylmethane,
N, N, N ', N'-tetraphenyl-4,4'-diaminobiphenyl, N, N'-diphenyl-N, N'-di-m-tolyl-4, N, N-diphenyl-N, N Aromatic tertiary amines such as'-bis (3-methylphenyl) -1,1'-4,4'-diamine, 4'-diaminobiphenyl, N-phenylcarbazole, 4-di-P-tolylaminostilbene, 4- (di-P-tolylamino) -4'-
[4- (di-P-tolylamino) styryl] stilbene and other stilbene compounds, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives,
Phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, silazane derivatives, polysilane-based aniline-based copolymers, polymer oligomers, styrylamine compounds, aromatic dimethylidyne-based compounds , A hole transporting layer such as poly-3-methylthiophene.

Reference numeral 4 denotes a light emitting layer made of a phosphor having fluorescence in the visible region and having a good film-forming property. The substances used for the light emitting layer 4 include the following.

According to Japanese Patent Laid-Open No. 4-255692,
Examples thereof include benzothiazole-based, benzimidazole-based, and benzoxazole-based optical brighteners, metal chelated oxinoid compounds, and styrylbenzene-based compounds. A typical example is 2,5-bis (5,7
-Di-t-pentyl-2-benzoxazolyl) -1,
3,4-thiadiazole, 4,4'-bis (5,7-bentyl-2-benzoxazolyl) stilbene, 4,
4'-bis [5,7-di- (2-methyl-2-butyl)
2-benzoxazolyl] stilbene, 2,5-bis (5,7-di-t-bentyl-2-benzoxazolyl) thiophene, 2,5-bis ([5-α, α-dimethylbenzyl ] -2-benzoxazolyl) thiophene,
2,5-bis [5,7-di- (2-methyl-2-butyl) -2-benzoxazolyl] -3,4-diphenylthiophene, 2,5-bis (5-methyl-2-benzo) Oxazolyl) thiophene, 4,4′-bis (2-benzoxazolyl) biphenyl, 5-methyl-2- [2-
[4- (5-Methyl-2-benzoxazolyl) phenyl] vinyl] benzoxazolyl, 2- [2- (4
-Chlorophenyl) vinyl] naphtho [1,2-d] oxazole and other benzoxazoles, 2,2 '-(p
-Phenylenedivinylene) -benzothiazoles such as benzothiazole such as bisbenzothiazole, 2-
Examples include fluorescent whitening agents such as [2- [4- (2-benzimidazolyl) phenyl] vinyl] benzimidazole and 2- [2- (4-carboxyphenyl) vinyl] benzimidazole. Examples of the metal chelated oxinoid include tris (8-
Quinolinol) aluminum, bis (8-quinolinol) magnesium, bis (benzo [f] -8-quinolinol) zinc, bis (2-methyl-8-quinolinolate)
Aluminum oxide, tris (8-quinolinol) indium, tris (5-methyl-8-quinolinol) aluminum, 8-quinolinol lithium, tris (5-
Chloro-8-quinolinol) gallium, bis (5-chloro-8-quinolinol) calcium, poly [zinc (I
I) -bis (8-hydroxy-5-quinolinonyl) methane] and other 8-hydroxycinoline-based metal complexes, and dilithium epindridione. Examples of the styrylbenzene compound include 1,4-bis (2-methylstyryl) benzene, 1,4- (3-methylstyryl) benzene, 1,4-bis- (4-methylstyryl) benzene, distyrylbenzene, 1,4-bis (2-ethylstyryl) benzene, 1,4-bis (3-ethylstyryl) benzene, 1,4-bis (2-methylstyryl) 2
-Methylbenzene, 1,4-bis (2-methylstyryl) -2-ethylbenzene and the like can be mentioned. Furthermore, the compound represented by the following formula can also be mentioned.

[0006]

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[0007]

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[0008]

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[0009]

[Chemical 4]

[0010]

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[0011]

[Chemical 6]

[0012]

[Chemical 7]

[0013]

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[0014]

[Chemical 9]

[0015]

[Chemical 10]

[0016]

[Chemical 11]

[0017]

[Chemical 12]

[0018]

[Chemical 13]

[0019]

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[0020]

[Chemical 15]

[0021]

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[0022]

[Chemical 17]

[0023]

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[0024]

[Chemical 19]

[0025]

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[0026]

[Chemical 21]

[0027]

[Chemical formula 22]

[0028]

[Chemical formula 23]

[0029]

[Chemical formula 24]

Distilpyrazine derivatives are also used as the light emitting material, and typical examples thereof are 2,5-bis (4-methylstyryl) pyrazine, 2,5-bis (4-ethylstyryl) pyrazine, 2,5. 5-bis [2- (1-naphthyl) vinyl] pyrazine, 2,5-bis (4-methoxystyryl) pyrazine, 2,5-bis [2- (4-biphenyl) vinyl] pyrazine, 2,5-bis Examples include [2- (1-pyrenyl) vinyl] pyrazine. In addition, there are compounds of the following formula.

[0031]

[Chemical 25]

Further, naphthalimide derivatives, perylene derivatives, oxadiazole derivatives, aldazine derivatives,
Examples thereof include a hirazilin derivative, a cyclopentadiene derivative, a styrylamine derivative, or a coumarin-based compound. Typical examples thereof include the following compounds.

[0033]

[Chemical formula 26]

[0034]

[Chemical 27]

[0035]

[Chemical 28]

In addition to these, aromatic dimethylidene compounds can be mentioned, and typical examples thereof include those of the following chemical formulas.

[0037]

[Chemical 29]

[0038]

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[0039]

[Chemical 31]

[0040]

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[0041]

[Chemical 33]

[0042]

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[0043]

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[0044]

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[0045]

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[0046]

[Chemical 38]

[0047]

[Chemical Formula 39]

[0048]

[Chemical 40]

Further, examples of the light emitting material include compounds represented by the following general formula.

[0050]

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Here, X and Y represent a fluorescent substance having an electroluminescence device function, and may be the same or different. Q represents a divalent group that cuts the conjugated system. Specifically, it is a divalent group obtained by removing one H atom from a straight-chain alkane, for example, the following chemical formula.

[0052]

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[0053]

[Chemical 43]

Specific examples of the compound represented by the general formula (I) include those represented by the following chemical formulas.

[0055]

[Chemical 44]

[0056]

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[0057]

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[0058]

[Chemical 47]

[0059]

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[0060]

[Chemical 49]

[0061]

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[0062]

[Chemical 51]

[0063]

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[0064]

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[0065]

[Chemical 54]

According to Japanese Patent Laid-Open No. 4-132189,
Examples of the material of the light emitting layer 4 include anthracene, salicylate, pyrene, coronene and the like.

Reference numeral 5 is a cathode made of a metal such as Al, In or MgAg. Further, the anode 2, the hole transport layer 3, the light emitting layer 4, and the cathode 5 are formed by vacuum vapor deposition or sputtering by Al ₂ O ₃ or S.
It may be sealed with an iO ₂ film or with a thermosetting polymer film by coating and then thermosetting.

[0068]

However, the above-mentioned conventional structure has the following problems.

(1) Inorganic electroluminescent devices require a high voltage for light emission (100 V or more), and when used in displays, it was difficult to color them.

(2) Compared with the inorganic electroluminescence element, the organic electroluminescence element causes oxygen and moisture in the atmosphere to enter the hole transport layer and the light emitting layer, resulting in a decrease in emission intensity and an increase in non-emission area. Lack of durability.

[0071] (3) as Al ₂ O ₃ and the anode of SiO ₂ film, a hole transport layer, luminescent layer, be sealed to the cathode, is possible to eliminate pinholes Al ₂ O ₃ or SiO ₂ film itself completely Since it is difficult, pinholes and the like are generated in the hole transport layer and the light emitting layer.

(4) Even if the anode, hole transport layer, light emitting layer and cathode are sealed with a thermosetting polymer film, an organic solvent must be used for coating and curing or a heating process must be performed. The hole transport layer and the light emitting layer are melted by the organic solvent, and the hole transport layer and the light emitting layer are deteriorated and deteriorated by heating.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an organic electroluminescent device having excellent light emitting characteristics and less deterioration with the aging change of the light emitting characteristics, and a manufacturing method thereof.

[0074]

In order to achieve this object, in the organic electroluminescence device according to claim 1 of the present invention, an anode, a hole transport layer, a light emitting layer and a cathode are sealed with a thermoplastic polymer film. It has the structure. The method for manufacturing an organic electroluminescence device according to claim 2 has a structure in which the hole transport layer, the light emitting layer, the cathode, and the thermoplastic polymer film are formed under vacuum in a consistent manner by a vapor deposition method. .

Here, as the thermoplastic polymer film, polyamides such as nylon 6, nylon 66, nylon 11 and nylon 12, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinylidene chloride, fluororesin, polymethylmethacrylate are used. , Polyester, polycarbonate, polyphenylene oxide, polyaddition type thermoplastic polyurethane, ring-opening polymerization type polyacetal and the like.

[0076]

With this structure, the thermoplastic polymer film prevents impurities from entering the hole transport layer and the light emitting layer from the atmosphere, so that an organic electroluminescent device whose light emitting property does not deteriorate with time is obtained. You can By this manufacturing method, since the thermoplastic polymer film is simultaneously formed in the vacuum for forming the hole transport layer, the light emitting layer and the cathode, it is possible to prevent impurities from entering the hole transport layer and the light emitting layer, and It is possible to obtain an organic electroluminescence element in which the light emission characteristics do not deteriorate even after a lapse of time.

[0077]

An embodiment of the present invention will be described below with reference to the drawings.

(Example 1) FIG. 1 is a sectional view of an organic electroluminescence device according to an example of the present invention. In FIG. 1, 1 is a glass substrate, 2 is an anode, 3 is a hole transport layer, 4 is a light emitting layer, 5 is a cathode, and 6 is a thermoplastic polymer film.

A commercially available glass substrate with ITO (P110E-H-PX, manufactured by Nippon Sheet Glass) 1 was etched with aqua regia to form an anode 2 of ITO ₂ . This glass substrate 1 was ultrasonically cleaned in an aqueous solution containing a detergent (white 7-L, UAI Kasei Co., Ltd.) for 1 hour, then in ion-exchanged water for 1 hour, and further in acetone for 30 hours. Minute ultrasonic cleaning was performed. The glass substrate 1 is ultrasonically cleaned in ethanol for 1 hour, then immersed in boiling ethanol for 5 minutes, and then naturally dried. The glass substrate 1 was set in the chamber of a resistance heating vacuum vapor deposition apparatus, and the pressure in the chamber was reduced to 1 × 10 ⁻⁶ Torr or less. N, N '
-Diphenyl-N, N'-bis (3-methylphenyl)
Using -1,1'-diphenyl-4,4'-diamine as a vapor deposition source, vacuum deposition was performed on the cathode 2 at a vapor deposition rate of 3Å / s to form a hole transport layer 3 having a thickness of about 500Å. On this hole transport layer 3, tris (8-hydroxyquinoline) aluminum is used as a vapor deposition source and the vapor deposition rate is 2Å / s.
Thus, a light emitting layer 4 having a thickness of about 500Å was formed. On this light emitting layer 4, using Mg and Ag as vapor deposition sources, the ratio of the vapor deposition rates of Mg and Ag is 10: 1, the vapor deposition rate is about 5Å / s,
The cathode 5 was formed by co-evaporation to a thickness of about 2500Å. The glass substrate 1, the anode 2, the hole transport layer 3, the light emitting layer 4,
Nylon 11 (Toray Industries, Inc., Rilsan-BM) is used as the cathode 5.
The deposition rate is 150Å using the pellets of N 0) as the deposition source.
/ S, a thermoplastic polymer film 6 having a thickness of about 4 mm was formed.

When a direct current of 10 V was applied to this organic electroluminescence element, it emitted green light and had an average luminance of 1200 cd / m ² . The organic electroluminescence device had an emission luminance decay rate of 5% after being left in the atmosphere for 90 days, and almost the initial luminance could be secured.

As is clear from these results, the organic electroluminescence device according to the first embodiment of the present invention has an excellent effect in that the light emission luminance is less deteriorated over time.

Example 2 In the same manner as in Example 1, the glass substrate 1, the anode 2, the hole transport layer 3, the light emitting layer 4, and the cathode 5 were used.
Was molded. A thermoplastic polymer film 6 having a thickness of 4 μm was formed on the glass substrate 1, the anode 2, the hole transport layer 3, the light emitting layer 4, and the cathode 5 using a polyethylene pellet as a vapor deposition source at a vapor deposition rate of 10 Å / s. .

When a direct current of 10 V was applied to this organic electroluminescence device, it emitted green light and had an average luminance of 1200 cd / m ² . The decay rate of the emission luminance after leaving this organic electroluminescence element in the atmosphere for 90 days was 12%, and almost the initial luminance could be secured.

As is clear from these results, the organic electroluminescence device according to the second embodiment of the present invention has an excellent effect in that the light emission luminance is less deteriorated over time.

Comparative Example 1 A glass substrate 1, an anode 2, a hole transport layer 3, a light emitting layer 4 and a cathode 5 were prepared in the same manner as in Example 1.
Was molded. This organic electroluminescence element was taken out from the resistance heating vacuum vapor deposition apparatus and left in the atmosphere for about 1 hour. A thermoplastic polymer film 6 was formed on this organic electroluminescence element by the same method as in Example 1.

When a direct current of 10 V was applied to this organic electroluminescence device, it emitted green light and had an average luminance of 1100 cd / m ² on the light emitting surface. The decay rate of the emission luminance after leaving the organic electroluminescence device in the atmosphere for 30 days was 50%.

Comparative Example 2 A glass substrate 1, an anode 2, a hole transport layer 3, a light emitting layer 4 and a cathode 5 were prepared in the same manner as in Example 1.
Was molded.

When a direct current of 10 V was applied to this organic electroluminescence device, it emitted green light and had an average luminance of 1100 cd / m ² on the light emitting surface. The organic electroluminescent element had an emission luminance decay rate of 50% after being left in the atmosphere for 2 days, and a non-light emitting portion (black spot) was also spread over the entire light emitting portion.

[0089]

As described above, according to the present invention, the anode, the hole transport layer, the light emitting layer, and the cathode are sealed with the thermoplastic polymer film, so that they have excellent light emitting characteristics, and the light emitting characteristics change with time. It is possible to realize an excellent organic electroluminescence device with extremely little deterioration. Further, in the method for manufacturing an organic electroluminescent element in the example of the present invention, since the thermoplastic polymer film is deposited in the same vacuum as the hole transport layer, the light emitting layer and the cathode, it has excellent light emitting characteristics, It is possible to realize an excellent method for manufacturing an organic electroluminescence device, which is extremely less deteriorated with time.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an organic electroluminescence device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a conventional organic electroluminescence device.

[Explanation of symbols]

 1 Glass Substrate 2 Anode 3 Hole Transport Layer 4 Light Emitting Layer 5 Cathode 6 Thermoplastic Polymer Film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location H05B 33/10 (72) Inventor Megumi Sakagami 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. A thermoplastic polymer film as an anode, a hole transport layer,
An organic electroluminescence device having a light emitting layer and a cathode sealed. 2. A method for producing an organic electroluminescence device, which comprises consistently forming a hole transport layer, a light emitting layer, a cathode and a thermoplastic polymer film by a vapor deposition method under a vacuum condition.