JP2000068049A - Electroluminescent device and method of manufacturing the same - Google Patents

Abstract

(57) [Problem] To provide an electroluminescent element having a long luminescent life by suppressing generation and growth of a dark spot. SOLUTION: An anode electrode 2, a hole transport layer 4, and an electron transport layer 5 are formed on a transparent substrate 1 as a cathode electrode 6 to form an electroluminescent portion, and an organic protective film 7 covering the entire electroluminescent portion and an inorganic protective film. A film 8 is formed. The rear substrate 9 and the transparent substrate 1 are opposed to each other, and the two substrates 9 and 10 are bonded together via a UV adhesive 10 made of a UV curable resin, and UV irradiation is performed to cure the UV adhesive 10. Because of photo-curing, generation of gas can be suppressed, and curing can be performed in an extremely short time. Therefore, generation and growth of dark spots can be prevented without deteriorating the electron transport layer 5 and the back electrode 6 by the uncured resin. Can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroluminescent device using an organic EL (electroluminescence) material and a method for manufacturing the same.

[0002]

2. Description of the Related Art An electroluminescent device using an organic EL material for a light emitting layer emits light by itself and has good visibility, and since it is a solid device, it has excellent shock resistance and realizes a DC low voltage drive device. Attracting attention. An electroluminescent element using such an organic EL material lacks long-term storage reliability (lifetime) as compared with an inorganic thin film element (organic dispersion type inorganic EL element), for example, a ZnS: Mn-based inorganic thin film element. Had a problem that hindered the practical use of However, in recent years, research on the improvement of the organic material forming the organic thin film layer, the improvement of the cathode metal material, and the passivation (gas barrier film) have been advanced, and the improvement in the environmental reliability test has been improved. As an electroluminescent device using an organic EL material layer as a light emitting layer, a two-layer structure (a hole transport layer and a light emitting layer) is developed, and the light emitting efficiency is improved by doping the light emitting layer with a laser dye. In addition, it has been reported that the half life of the device when it is driven also exceeds 10,000 hours.

[0003]

However, the measurement of the half-life of such an electroluminescent device is mostly performed in a nitrogen atmosphere, an inert gas atmosphere, or a normal temperature environment under vacuum. The lack of reliability in use has been pointed out. One of the major problems in such an electroluminescent device is the growth of dark spots, which are non-light emitting regions. This dark spot is
In the encapsulation process, growth is promoted by giving a thermal history of, for example, 100 ° C. or more, or growth is promoted by the influence of gas emitted from the adhesive resin. Further, in such an electroluminescent device, an existing adhesive resin (sealing resin) is used.
Problems such as low gas barrier properties have been pointed out.

An object of the present invention is to provide an electroluminescent device in which generation and growth of dark spots are suppressed, and a method for manufacturing the same.

[0005]

According to the first aspect of the present invention,
An electroluminescent element in which a front electrode, an electroluminescent layer, and a back electrode are sequentially stacked on a front substrate, wherein at least a protective film is formed so as to cover the electroluminescent layer and the back electrode. A rear substrate facing the front substrate is disposed above, and a space between the front substrate and the rear substrate is filled with a photo-curable resin cured and filled.

Accordingly, in the first aspect of the present invention, since at least the electroluminescent layer and the back electrode are covered with the protective film, deterioration of the electroluminescent layer due to oxygen, moisture, etc., oxidation of the back electrode, and the like are suppressed. be able to. In addition, since it is sealed with a photocurable resin, the entire photocurable resin can be immediately cured by light irradiation. Therefore, the time during which the resin in the uncured portion is present can be extremely short, and the effect of the uncured resin on the electroluminescent layer and the back electrode can be minimized. Further, since the photocurable resin does not generate gas with curing, deterioration of the electroluminescent layer and the back electrode can be suppressed.

According to a second aspect of the present invention, in the electroluminescent device according to the first aspect, the protective film is made of an organic material.

According to a third aspect of the present invention, there is provided a method of manufacturing an electroluminescent device, comprising the steps of sequentially laminating a front electrode, an electroluminescent layer, and a back electrode on a front substrate; A step of forming a protective film covering the light emitting layer and the back electrode, and bonding the front substrate and the back substrate via a photocurable resin, the front electrode, the electroluminescent layer, the back electrode, and the protective film It is characterized by comprising a step of sealing in the photocurable resin, and a step of irradiating the photocurable resin with light to cure the resin. According to the third aspect of the present invention, since the stress caused by bonding the front substrate and the rear substrate is alleviated by the photocurable resin, it is possible to prevent the rear electrode from breaking through the electroluminescent layer and short-circuiting with the front electrode.

According to a fourth aspect of the present invention, there is provided a method for manufacturing an electroluminescent device according to the third aspect, wherein the photocurable resin comprises:
It is characterized in that it is applied to the back substrate.

According to a fifth aspect of the present invention, there is provided the method for manufacturing an electroluminescent device according to the fourth aspect, wherein the back substrate and the front substrate are bonded in a vacuum state and then in a vacuum state or a nitrogen gas atmosphere. Alternatively, light irradiation is performed in an inert gas atmosphere.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of an electroluminescent device according to the present invention and a method for manufacturing the same will be described below based on embodiments shown in the drawings.

First, as shown in FIG. 1, a plurality of anode electrodes 2 are formed on a transparent substrate 1 in parallel. Here, as a material of the transparent substrate 1, a plastic such as polyester, polyacrylate, polycarbonate, polysulfone, or polyetherketone, or a transparent material such as glass is used. The material of the anode electrode 2 is aluminum (Al), gold (Au), silver (Ag), magnesium (Mg), nickel (Ni), zinc-vanadium (Zn).
V), indium (In), tin (Sn) or the like, a compound or a mixture thereof, or a conductive adhesive containing a metal filler. The anode electrode 2 is preferably formed by sputtering, ion plating, or vacuum deposition, but may be formed by printing using a spin coater, a gravure coater, a knife coater, or the like, screen printing, flexographic printing, or the like. The light transmittance of the anode electrode 2 is 80
% Is preferably set.

Next, as shown in FIG. 2, in the present embodiment, an interlayer insulating film 3 having an opening 3A for exposing the surface of the anode electrode 2 to be joined to a hole transport layer 4 described later is formed on the anode electrode 2. It is formed on the transparent substrate 1 including the electrodes 2. This interlayer insulating film 3 can be formed into a pattern using photolithography and etching after depositing, for example, SiO ₂ over the entire surface of the substrate by CVD.

Thereafter, as shown in FIG. 3, a hole transport layer 4 and an electron transport layer 5 are sequentially laminated at least over the entire light emitting region. As the hole transport layer 4, for example, a carbazole polymer and a TPD: triphenyl compound are co-deposited to form a 10 to 1000 nm (preferably 100 to 7 nm).
(00 nm). Further, as the electron transporting layer 5, a metal complex compound formed from a metal and an organic ligand, preferably, Alq3 (tris (8-quinolinolate))
Aluminum complex), Znq2 (bis (8-quinolinolate) zinc complex), Bebq2 (bis (8-quinolinolate))
Beryllium complex), Zn-BTZ (2- (o-hydroxyphenyl) benzothiazole zinc), perylene derivative or the like at 10 to 1000 nm (preferably 100 to 700 nm).
(nm).

Next, as shown in FIG. 4, a plurality of cathode electrodes 6 are formed on the electron transport layer 5 along a direction intersecting the anode electrode 2. The cathode electrode 6 is made of a metal having a low work function capable of efficiently injecting electrons into the electron transport layer 5, preferably, Mg, Sn, In, Ag, Li, or Al.
And the like, or an alloy thereof.

Thereafter, as shown in FIG. 5, an organic protective film 7 made of a paraxylene resin is formed so as to cover the entire electron transport layer 5 including the cathode electrode 6 and the hole transport layer 4. As a method for forming the organic protective film 7, a CVD method or a vapor deposition method can be used.
It is formed to have a thickness of 0000 nm. Thereafter, as shown in FIG. 6, an inorganic protective film 8 formed by introducing SiO ₂ into cerium dioxide (CeO ₂ ) so as to cover the organic protective film 7.
Is formed so as to have a thickness of 0.1 nm to 10000 nm. In addition, as a method for forming the inorganic protective film 8, a vapor deposition method, a sputtering method, and an ion plating method can be used. In order to form the inorganic protective film 8, after the cathode electrode 6 is formed, the organic protective film 7 is formed and the film is continuously formed without breaking the vacuum, or in an N ₂ atmosphere or an inert gas. It is transported in a state where it is load-locked, and formed again in a vacuum.

Next, as shown in FIG. 7, a rear substrate 9 is prepared, and a UV adhesive 10 made of a UV-curable epoxy resin using a cationic curing catalyst is applied to the surface of the rear substrate 9. The thickness at which the UV adhesive 10 is applied is set to such a thickness that the electroluminescent portion can be embedded in the UV adhesive 10. Then, under a reduced pressure (preferably 100 Torr or less), the transparent substrate 1 and the back substrate 9 are interposed via the UV adhesive 10.
Are bonded to form a structure as shown in FIG. Immediately after such bonding, the UV adhesive 10 is irradiated with ultraviolet light in a vacuum, in a nitrogen gas atmosphere, or in an inert gas inert atmosphere to cure the UV adhesive 10 and form the protective film 12. In addition, you may heat at the time of hardening. In the present embodiment, the integrated amount of ultraviolet light is set to 100000 mj / cm ² or less. By manufacturing the electroluminescent device 11 as shown in FIG. 8 in this manner, the stress caused by bonding the transparent substrate 1 and the back substrate 9 is alleviated by the UV adhesive 10, so that the cathode electrode 6 has holes. A short circuit with the anode electrode 2 by breaking through the transport layer 4 and the electron transport layer 5 can be prevented.

This UV adhesive 10 is made of U
V-cured epoxy resin, the components of which are epoxy resin,
They are an insulating filler, a cationic photopolymerization initiator, a coupling agent, and a sensitizer.

As the epoxy resin, bisphenol A
Form, bisphenol F form, bisphenol AD form, bisphenol S form, xylenol form, phenol novolak form, cresol novolak form, polyfunctional form, tetraphenylolmethane form, polyethylene glycol form, polypropylene glycol form, hexanediol form, trimethylolpropane Form, propylene oxide bisphenol A form, hydrogenated bisphenol A form, or a mixture thereof, and preferably, bisphenol A form, bisphenol F form, bisphenol AD form, and bisphenol S form.

As the insulating filler, polyethylene,
Various acrylates such as polypropylene, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, polycarbonate, polymethyl methacrylate, and polyvinyl butyral, polyvinyl formal, polyimide, polyamide, polyester, polyvinyl chloride-polyphenol-formalin Resin, phenolic resin, xylene resin, furan resin, diallyl phthalate resin, phenoxy resin, silicone resin, titanium oxide, silicon dioxide, calcium carbonate,
There are calcium phosphate, aluminum oxide, diantimony trioxide, silica and the like, and preferably, ultrafine anhydrous silica: # 130, 200, 30 manufactured by Nippon Aerosil Co., Ltd.
0, 380, OX50, TT600, MOX80, 17
0, hydrophobic R-972, silicone-treated R-202, 8
05 and 812.

As the cationic photopolymerization initiator, an allyldiazonium salt represented by the general formula (Ar-N ₂ + X-) (Ar is benzene having a nitro group, a methoxy group, a morpholino group, or chlorine as a substituent or benzene alone) Yes,
X- represents PF _6- , AsF _6- , SbF _6- , SbCl
_{6 -, BF 4 -, SnCl} 6 -, FeCl 4 -, BiCl 5
-. ), Diaryliodonium salts represented by the general formulas (Ar ₂ I + X−) and (Ar ₃ S + X−), and triarylsulfonium salts (Ar is a nitro group,
Methoxy, t- butyl group, a methyl group, a chlorine group, a benzene or benzene alone with acetamide group as a substituent, X- _{is, PF 6 -, AsF 6 -} , BF 4 -, Sb
_{F 6 -, ClO 4 -,} CF 3 SO 4 -, FSO 3 -, F 2 PO
₂ -, _{preferably, PF 6 -, AsF 6 -} , BF 4 -, Sb
F _6- and a salt of Ar).

As coupling agents, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-
(2-aminoethyl) aminopropylmethyldimethoxysilane, aminosilane, γ-methacryloxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane
Hydrochloride, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane, γ-anilinopropyltrimethoxysilane, vinyltrimethoxysilane, octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium chloride, γ-chloropropylmethyldimethoxysilane, γ-mercaptopropylmethyldimethoxysilane,
γ-glycidoxypropylmethyldimethoxysilane, γ
Silane coupling agents such as ureidopropyltriethoxysilane and γ-methacryloxypropylmethyldimethoxysilane, among which γ- (2-aminoethyl) aminopropyltrimethoxysilane and γ-
(2-aminoethyl) aminopropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-
Anilinopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane are more preferred.

Examples of the sensitizer include xanthene dyes such as erythrosine and eosin, acridine orange, acridine yellow, benzoflavin, setoflavin, phosphine R, perylene, anthracene, phenothiazine, thioxanthone, chlorothioxanthone, benzophenone, fluorenone, and anthraquinone. is there.

Next, a detailed configuration of an example of the electroluminescent device 11 of the present embodiment will be described below. (Example) Anode electrode 2 ITO (8Ω / □) Hole transport layer 4 Triphenyldiamine derivative (TPD), thickness 50 nm Electron transport layer 5 Alq3: Tris (8-hydroxyquinoline aluminum, thickness 50 nm Cathode electrode 6 MgIn , 400 nm thick UV adhesive 10 components ○ Epoxy (bisphenol A) 60 parts made from Yuka Shell (epoxy equivalent 190) 40 parts 1001 made from Yuka Shell (epoxy equivalent 470) 40 parts of the above epoxy to base 100 parts The following: ○ Photo cationic polymerization initiator methoxyphenyliodonium hexafluoroantimonate 0.5 part ○ Inorganic filler (silica) 10 parts R-927 (silica powder) manufactured by Nippon Aerosil Co., Ltd. ○ Silane coupling agent Dow Corning Toray Toray Γ- (2-aminoethyl) aminopro Prepared in Example 1-5 Le trimethoxysilane 0.1 parts configured as described above, operated at room temperature (25
℃, humidity 65%), high temperature and high humidity operation (40 ° C, humidity 95%)
%) And the results of measuring the growth (diameter of the black spot) of black spots (dark spots) over time in an environment of high-temperature operation (60 ° C.) are shown in FIGS. 9 to 11. At this time, the current density was set to ^2.5 mA / cm ² , the duty ratio was set to 1/2, the pulse drive was set to 1 kHz, and the light emitting area was set to 2 mm □.

As shown in FIG. 9 to FIG.
It can be seen that the maximum diameter of the dark spot is suppressed to 95 μm or less even after 1000 hours in any of the normal temperature operation, the high temperature / humidity operation, and the high temperature operation. Thus, the deterioration of the organic layer and the back electrode 6 due to the sealing with the UV adhesive 10 was effectively suppressed, and the growth of dark spots was able to be suppressed. that's all,
The present invention described in the embodiment is not limited to this, and various changes accompanying the gist of the configuration are possible. For example, in the above-described embodiment, a case has been described in which the hole transport layer 4 and the electron transport layer 5 are stacked as the organic layer, but a light emitting layer may be interposed between them.

As is apparent from the above description, according to the present invention, the generation and growth of dark spots can be suppressed, and an electroluminescent device having a long light-emitting life can be realized.

[Brief description of the drawings]

FIG. 1 is a process sectional view showing an embodiment of a method for manufacturing an electroluminescent device according to the present invention.

FIG. 2 is a process cross-sectional view of the embodiment.

FIG. 3 is a process sectional view of the embodiment.

FIG. 4 is a process sectional view of the embodiment.

FIG. 5 is a process sectional view of the embodiment.

FIG. 6 is a process sectional view of the embodiment.

FIG. 7 is a process sectional view of the embodiment.

FIG. 8 is a sectional view showing the electroluminescent device of the embodiment.

FIG. 9 is a graph showing a measurement result of dark spot growth in the example.

FIG. 10 is a graph showing a measurement result of dark spot growth in the example.

FIG. 11 is a graph showing a measurement result of dark spot black spot growth of an example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 transparent substrate (front substrate) 2 anode electrode (front electrode) 4 hole transport layer 5 electron transport layer 6 cathode electrode (back electrode) 7 organic protective film 9 rear substrate 10 UV adhesive (photocurable resin) 11 electroluminescence Element 12 Protective film

Continued on the front page (72) Inventor Ichiro Kono 5F, 2951 Ishikawa-cho, Hachioji-shi, Tokyo Casio Computer Co., Ltd. F-term in Hachioji Laboratory (reference) 3K007 AB00 BB00 CA01 CA05 CB01 DA00 DB00 DB03 EB00 FA01

Claims (5)

[Claims] 1. An electroluminescent device in which a front electrode, an electroluminescent layer, and a back electrode are sequentially stacked on a front substrate, wherein a protective film is formed so as to cover at least the electroluminescent layer and the back electrode. An electric field, wherein a rear substrate opposed to the front substrate is disposed above the protective film, and a space between the front substrate and the rear substrate is cured and filled with a photocurable resin. Light emitting element. 2. The electroluminescent device according to claim 1, wherein said protective film is made of an organic material. A step of sequentially laminating a front electrode, an electroluminescent layer and a back electrode on the front substrate; a step of forming a protective film covering at least the electroluminescent layer and the back electrode on the front substrate; Laminating the front substrate and the rear substrate via a curable resin, sealing the front electrode, the electroluminescent layer, the back electrode, and the protective film in the photocurable resin; Curing the resin by irradiating the resin with light;
A method for manufacturing an electroluminescent device, comprising: 4. The method according to claim 3, wherein the photocurable resin is applied to the rear substrate. 5. The method according to claim 4, wherein after the back substrate and the front substrate are bonded in a vacuum state, light irradiation is performed in a vacuum state, a nitrogen gas atmosphere, or an inert gas atmosphere. A method for manufacturing an electroluminescent device.