JP2000182780A - Organic electric field light emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a long-life and highly reliable element with excellent color conversion efficiency by using at least one compound selected from straight silicone resin compounds and modified silicone resin compounds for a protective layer for the light emitting element. SOLUTION: A fluorescent pigment layer is formed by arranging a red pigment layer 3, a green pigment layer 4, or a blue pigment layer 5 on a base such as a glass board 6. On the fluorescent pigment layer, protective layers 1, 2, a positive electrode 7, a positive hole injection layer 8, a positive hole carrying layer 9, an organic light emitting layer 10, an electron injection layer 11, and a negative electrode 12 are arranged in this order. As the protective layers 1, 2, a mechanically strong transparent silicone resin having a film thickness of about 1-20 μm and a gas barrier characteristic is laminated on a color conversion filter consisting of the respective pigment layers 3, 4, 5. The silicone resin is cured at about 150 deg.C or less, and the silicone resin layer may be formed into a single layer. In this case, the protective layers 1, 2 have the same composition. On the protective layers 1, 2, a film of an insulative inorganic oxide such as silicon oxide or aluminum oxide may be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective layer of an organic electroluminescent device (also referred to as an organic EL (electroluminescence) device), and more particularly to an organic electroluminescent device using a protective layer compatible with a fluorescent dye layer.

[0002]

^2. Description of the Related Art Tang et al. Have reported a stacked EL device capable of obtaining a high luminance of 1000 cd / m ² or more at an applied voltage of 10 V (Appl. Phys. Lett., 51, 913 (1987)). Research for practical use has been actively conducted. The organic EL element is a thin-film self-luminous element,
It has excellent features such as low driving voltage, high resolution, and high viewing angle, and is expected to be applied to flat panel displays. Green monochrome organic EL already installed in vehicles
The display has been commercialized since November 1997, and in the future, in order to respond to the diversifying needs of society, commercialization of a multicolor display and a full-color display organic EL display is desired. As a method of multicolor display of an organic EL element (described in Functional Materials, February 1998, Vol. 18, No. 2, p96),
Three primary color organic EL elements are sequentially patterned and arranged on a plane, and three primary colors (red,
(Green, blue) color filters, a blue organic EL element with a color conversion filter using a fluorescent dye, color conversion of blue light to longer wavelength fluorescence (green, red) and three primary colors (Japanese Patent Application Laid-Open No. 5-258860)
Described in Japanese Patent Application Laid-Open Publication No. 2000-216, etc.).

When the organic EL elements of the three primary colors are sequentially patterned and arranged on a plane, the patterning of each organic EL layer is performed by photolithography, so that the luminous efficiency of the element itself is greatly reduced by the repeated development process. I do. Further, it is considered that mass production is difficult because the process becomes very complicated.

In a color filter system using a white organic EL element, white light is cut by a color filter to display one of the three primary colors, so that the luminous efficiency is limited to one third, which is disadvantageous. At present, a white organic EL device capable of stably obtaining sufficient luminance has not yet been obtained.

A method of installing a color conversion filter using a fluorescent dye to convert blue light into longer-wavelength fluorescent light (green and red) to emit light of three primary colors involves absorbing light in the emission range of the organic EL element. In addition, a color conversion method using a phosphor that emits fluorescent light in a visible light region as a filter has been disclosed (Japanese Unexamined Patent Application Publication No. Hei.
152897, JP-A-5-258860). In a color conversion method in which a fluorescent dye layer is installed, the conversion efficiency is determined by the product of the light absorption efficiency and the fluorescence efficiency of the phosphor.If a phosphor with high light absorption efficiency and fluorescence efficiency is used, the conversion efficiency will increase. Very high primary color emission is possible. Thus, a three-primary-color display method using a color conversion filter with a fluorescent dye layer is expected to be the most advantageous and close to practical use.

When manufacturing an organic EL device using a color conversion filter, it is important to note that an anode which is a transparent electrode,
This is the distance between the organic light emitting layer and the color conversion filter formed by the cathode laminate. As the distance becomes longer, the light emission of the adjacent pixels is more likely to leak, so that the viewing angle characteristics deteriorate. Therefore, the shorter the distance between the laminate and the color conversion filter, the better the viewing angle characteristics. Therefore, it is desirable to form the laminate directly on the upper surface of the color conversion filter.

[0007] However, known fluorescent dyes used in color conversion filters (Japanese Patent Application Laid-Open Nos. 8-78158 and 8-222369).
JP-A-8-279394, JP-A-8-286033, JP-A-9-106888, JP-A-9-208944, JP-A-9-245511, JP-A-9-330793 , JP10
-12379), rhodamines,
Pyridine-based, oxazine-based, coumarin-based dyes, and the like often cause a change in fluorescence wavelength and quenching due to the influence of ultraviolet light, heat, or an organic solvent. Therefore, when the laminate is to be formed directly on the upper surface of the color conversion filter,
The fluorescent dye layer is exposed to plasma generated during a sputtering step for forming a transparent electrode, a stripping solution used for patterning the transparent electrode, and the like, and the color conversion filter loses its function.

Further, when a color conversion filter is used, it is necessary to make the thickness of the fluorescent dye layer of each of the three primary colors different in order to obtain a desired color tone due to the difference in conversion performance of the phosphor corresponding to each color. There is a step in the fluorescent dye layer as a color conversion filter. If the laminate is formed directly on the fluorescent dye layer having a step, there is also a problem that disconnection of the electrode and unevenness of the thickness of the organic light emitting layer occur, and stable light emission of the organic EL layer cannot be obtained.

As described above, it is very difficult to form the laminate directly on the upper surface of the fluorescent dye layer which is a color conversion filter, and it is necessary to provide a protective layer between the color conversion filter and the transparent electrode. Required.

The characteristics required for the protective layer include the following. (1) Pattern erosion of the fluorescent dye layer and inactivation of the function do not occur. (2) The step of each of the fluorescent dye layers of RGB can be filled, and the film can be formed as thin as possible (1 to 20 μm) in order to maintain good viewing angle characteristics. (3) Good light transmittance. (4) Good heat resistance. (5) Good surface smoothness. (6) Good adhesion to the substrate, the fluorescent dye layer, and the transparent electrode. (7) It has excellent chemical resistance. (8) It has excellent moisture resistance. (9) No degassing of residual monomers and solvents. (10) Have mechanical strength. (11) Protecting the fluorescent dye layer from heat and light exposed in a post-process.

One of the conventional protection methods is to provide a phosphor protective layer and an adhesive layer between a fluorescent dye layer and an insulating inorganic oxide layer (described in JP-A-8-279394). In this method, an acrylate-based or methacrylate-based photocurable resin having a reactive vinyl group is used as a protective layer and an adhesive layer.

It is also known to use a high-temperature curable resin such as a polyimide resin used for a protective layer of a color filter for a liquid crystal display as a protective layer of a color conversion filter (Japanese Patent Laid-Open No. 1-229203). Described).

A method of coating a SiO ₂ -based inorganic coating agent using a sol-gel method is also known (described in Monthly Display, 1997, Vol. 3, No. 7, p119). The obtained SiO ₂ -based inorganic coating has advantages such as excellent heat resistance, weather resistance, solvent resistance, and high hardness.

[0014]

However, when the above-mentioned photo-curable resin is used, the phosphor used in the color conversion filter is liable to deteriorate in characteristics due to light.
In particular, irradiation with ultraviolet light significantly deteriorates color conversion characteristics. For this reason, to protect the fluorescent dye layer, a photocurable resin,
In particular, it is not desirable to use an ultraviolet curable resin.

When a high-temperature curing type resin is used as a protective layer of a color conversion filter, it is necessary to cure the resin at a high temperature of 200 ° C. or more, so that the characteristics of the phosphor deteriorate. In addition, organic polymer-based resins generally have low hardness and cannot withstand pressure bonding of 30 kg / cm ² at a high temperature of 150 ° C. or more, such as in a sealing process or a connecting process of an extraction electrode. .

Further, organic polymer-based resins such as photo-curable resins and thermosetting resins have poor adhesion to glass substrates, electrically insulating inorganic oxide layers, transparent electrodes and the like. Therefore, delamination is likely to occur during the element manufacturing process or during light emission driving, which is a major factor in shortening the life of the organic EL element.

The method of coating a SiO ₂ -based inorganic coating agent using the sol-gel method has the above-mentioned excellent properties, but can coat only a submicron-order film. When a fluorescent dye layer of several tens μm is coated, the step cannot be filled. Therefore, the color conversion filter cannot be uniformly and smoothly protected. In the case where a thick film is formed by increasing the viscosity or by overcoating, the film is weakened by stress and breaks such as cracks occur.

Further, this method requires baking at 240 ° C. or more for complete curing, and at such a high temperature, there is a problem that the characteristics of the phosphor are deactivated. Not suitable.

As described above, a UV-curable resin, a high-temperature-curable resin, or a SiO ₂ -based inorganic coating agent, which has been used as a protective layer of a color conversion filter, is used for a color conversion filter using a phosphor in an organic EL device. There are many problems in using it as a protective layer, and at present it has not been solved.

The present invention has been made in view of the above points, and has as its object to form a film without exposing the fluorescent dye layer to ultraviolet irradiation, high-temperature heating, etc., to have excellent thermal stability, and to be applied to a substrate or a transparent electrode. Providing a highly reliable organic electroluminescent device with high color conversion efficiency and long device life, using a protective layer with high adhesion and sufficient hardness to withstand pressure bonding during the sealing process and electrode connection process Is to do.

[0021]

According to the present invention, a fluorescent dye layer as a color conversion filter, a protective layer, an anode as a transparent electrode, an organic light emitting layer, and a cathode are provided on a transparent substrate according to the present invention. Are sequentially arranged, and the protective layer is achieved by using at least one selected from a compound of a straight silicone resin or a modified silicone resin.

In the above invention, the protective layer is made of a silicone resin which cures at 150 ° C. or lower, the protective layer is formed by laminating different silicone resins, the protective layer is made by adding an ultraviolet absorber, or Layer thickness is 1
It is effective that the thickness is 20 μm.

The protective layer formed by using a silicone resin which is sterically cross-linked by a -Si-O-Si- bond has excellent heat resistance, weather resistance, solvent resistance and high hardness.
The Si—O bond forming the skeleton of the silicone resin is about 20 times smaller than the C—C bond forming the skeleton of a general organic compound.
kcal / mol also has a large binding energy, and therefore has much higher heat resistance than general organic resins.
It also has excellent water repellency, moisture resistance, and water resistance, as it has very little tendency to decompose and degrade the coating film, such as discoloration and chalking, as compared with organic resins. Silicone resin is indium tin oxide (ITO), which is a glass substrate, insulating inorganic oxide layer, and transparent electrode, compared to organic resin.
Adhesion with the like is also good.

Generally, an organic polymer resin has poor adhesion to an inorganic oxide layer such as a base glass substrate or an upper transparent electrode. This is considered to be due to a large difference in the coefficient of linear expansion from an inorganic oxide layer such as a glass substrate or a transparent electrode, or a chemical bond at the interface. Delamination easily occurs between an inorganic oxide layer such as a glass substrate or a transparent electrode having a small linear expansion coefficient and an organic polymer resin having a large linear expansion coefficient and a large temperature dependency.

On the other hand, since the silicone resin has a thermal expansion coefficient intermediate between that of the organic polymer resin and the inorganic oxide layer, the fluorescent dye which is a glass substrate, a transparent electrode or an organic polymer resin layer is used. It is easy to adhere to both of the layers, and has an effect of suppressing delamination. Further, since both have a similar structure, it is presumed that the adhesion is high due to hydrogen bonding on the surface and the like. In addition, the thin film thickness and insufficient leveling property at the time of film formation, which have been regarded as problems, can be improved by combining silica sol and alumina sol.

Using a siloxane having a silanol group at the end and an ester siloxane, using an acid, an alkali or an organometallic compound as a catalyst, hydrolyzing at room temperature, and then performing condensation curing to obtain a silicone resin having a low curing temperature. I have. Such silicone resins have already been applied for coating industrial plastics and plastic lenses. There are also room-temperature-curing and low-temperature-curing silicone resins with a curing temperature of about 130 ° C, which do not require the heat curing of 300 ° C or higher, which was conventionally required for firing.
Silicone News Silicone Review Vol.24-39
(1998)]. The use of a silicone resin that cures at a low temperature without going through a curing process such as irradiation with ultraviolet light makes it possible to maintain the color conversion characteristics of the fluorescent dye layer to be protected.

As described above, when a silicone resin is used, heat resistance, weather resistance, solvent resistance, high hardness, water repellency, moisture resistance, water resistance, and indium serving as a glass substrate, an insulating inorganic oxide layer, and a transparent electrode are used. Adhesion with tin oxide (ITO), etc.
It is possible to form an excellent protective layer that satisfies all of the items such as leveling properties, low-temperature curing, and retention of the color conversion characteristics of the phosphor layer.

A silicone resin that cures at 150 ° C. or less does not thermally affect the fluorescent dye layer. If an ultraviolet absorber is added to the silicone resin, the fluorescent dye layer will not be exposed to ultraviolet light even if plasma sputtering or ultraviolet irradiation is performed in a process after device fabrication.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Straight silicone resins and modified silicone resins will be described below. Straight silicone resins are those whose active ingredient consists of silicone only. Like other silicone products, straight silicone resins have a main chain of -Si-O-Si- bonds, and aromatic groups such as alkyl groups such as methyl groups and phenyl groups. It has a group in the side chain. After curing, it has the advantages of forming a three-dimensional crosslinked structure with a very high crosslinking density and forming a hard film.

The straight silicone resin is obtained by dehydration-condensation polymerization of a silane compound or a silanol compound of the following general formula, which incorporates a large number of trifunctional units and tetrafunctional units as constituent units, and has a branched structure.

[0031]

Embedded image X _n Si (OR) _4-n wherein X represents a methyl group and / or a phenyl group;
R represents a hydrogen atom, an alkyl group, an aryl group, or an aryl group which may have a substituent. n is an integer of 1 to 3,
Preferably, n = 2 to 3. Generally, as n increases, the number of crosslinked sites increases and the hardness also increases. Methylsilicone is a solution in which a water-alcohol hydrophilic polysiloxane having a large amount of silanol groups obtained by hydrolyzing CH ₃ Si (OR) ₃ silane, silica sol, and alumina sol form an extremely hard film. It is used as a hard coating agent for hardening the surface of plastics. In the case of a phenyl silicone, the film strength is superior to that of a methyl silicone.

Specific examples of the above straight silicone resin include KP-85, KP-64 and X-12-220.
6, X-12-2396, X-12-2397 (manufactured by Shin-Etsu Chemical Co., Ltd.), SH804, SH805, SH
806A, SH840, SR2400 (manufactured by Dow Corning Toray Silicone Co., Ltd.) and the like, but are not limited thereto.

The modified silicone resin is generally obtained by block copolymerization of a silicone cross-linked product and an organic resin and polycondensation via an ether bond. In a modified resin such as an alkyd resin, a polyester resin or an epoxy resin, an --OH group is contained. , −
It is a block copolymer of a resin having a COOH group and a -O- group and a silicone resin having various molecular weights and having a relatively large number of alkoxy groups such as silanol groups and methoxy groups. In addition, by using a silane compound having a structure generally referred to as a silane coupling agent represented by the following general formula, organic-inorganic hybridization can be easily performed.

[0034]

## STR2 ## _{Y n Si (OR) 4-} n wherein Y is an acrylic group, a mercapto group, an azide group, an amino group, an epoxy group, a group capable of reacting with an organic resin such as a methacryloxy group, Si-OR groups With this, it becomes possible to bond with the silicone resin. R represents a hydrogen atom, an alkyl group, an aryl group, or an aryl group which may have a substituent. n represents an integer of 1 to 3, preferably 2 to 3.

As examples of these silane compounds, for example, SH6020, SZ6030, SH6040, SZ6
075 (manufactured by Dow Corning Toray Silicone Co., Ltd.) can also be used, but is not limited thereto.

The modified silicone resin is an organic-inorganic material having the excellent heat resistance and environmental stability of the silicone resin and the properties of the organic resin such as flexibility, adhesion, water resistance, film forming properties, and electrical insulation. Known as a hybrid material, specifically, imide-modified silicone described in JP-A-4-190962 and JP-A-6-19216, and silicone-modified polyester resin described in JP-A-8-279394 are exemplified. Are known. Further, it can be copolymerized with acrylic resin, epoxy resin, alkyd resin, polyester resin, urethane and the like.

Specific examples of the above modified silicone resin include SR2107, SR2115 and SR2145 (manufactured by Dow Corning Toray Silicone Co., Ltd.), but are not limited thereto.

Further, by adding an ultraviolet absorber to the silicone resin, a fluorescent light is generated by plasma sputtering generated in a film forming step of a transparent electrode performed in a later process, or ultraviolet irradiation of a resist used in patterning the transparent electrode. This prevents the dye layer from being damaged and the color conversion characteristics from being deteriorated. A specific example of the ultraviolet absorber is represented by a chemical formula (I-1).
To the chemical formula (I-5), but the invention is not limited thereto, and those having a benzophenone skeleton or a benzotriazole skeleton in the molecule can be used even if the substituent is changed. Two or more ultraviolet absorbers may be used in combination.

[0039]

Embedded image

[0040]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing a manufacturing process in which red, green, and blue fluorescent dye layers are formed on a substrate for an organic electroluminescent device according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a manufacturing process of the organic electroluminescent device according to the embodiment of the present invention in which a protective layer is provided on a fluorescent dye layer. FIG. 3 is a schematic cross-sectional view showing a manufacturing process in which a hole injection layer, a hole transport layer, an organic light emitting layer, an electron injection layer, and a cathode are sequentially stacked on a protective layer for an organic electroluminescent device according to an embodiment of the present invention. is there.

The fluorescent dye layer is formed by disposing a red dye layer 3, a green dye layer 4, or a blue dye layer 5 on a substrate 6 such as a glass substrate. There is no particular limitation on the method of forming each fluorescent dye layer, and for example, photolithography, micellar electrolysis, screen printing, inkjet printing, and the like can be used.

The protective layers 1 and 2 are transparent and have a thickness of 1 to 20 μm on a color conversion filter comprising fluorescent dye layers 3, 4 and 5.
A silicone resin having gas barrier properties and mechanical strength (pencil hardness test: 3H or more) is laminated. This silicone resin can be cured at a temperature of 150 ° C. or less. The silicone resin layer may be a single layer. In the case of a single layer, the protective layer 1 and the protective layer 2 have the same composition. The protective layers 1 and 2 can be easily formed on the fluorescent dye layer by using a spin coater, a dipping method, a roll coating method, a screen printing method, or the like. An insulating inorganic oxide layer such as silicon oxide or aluminum oxide may be formed on the protective layers 1 and 2 by plasma sputtering.

On the protective layers 1 and 2, an anode 7 as a transparent electrode, a hole injection layer 8, a hole transport layer 9, an organic light emitting layer 10, an electron injection layer 11, and a cathode 12 are sequentially laminated. The anode is indium tin oxide (ITO), the hole injection layer is copper phthalocyanine (CuPc), and the hole transport layer is 4,4'-bis [
N- (1-naphthyl) -N-phenylamino] biphenyl (α-NPD) and 4,4′-bis (2,2-diphenylvinyl) biphenyl (DPVB) for the organic light emitting layer
i) Although aluminum chelate (Alq) was used for the electron injection layer, the invention is not limited to these. Example 1 [Fluorescent dye layer formation] A color filter blue material (manufactured by Fuji Hunt Electronics Technology: Color Mosaic CB-7001) was applied on a glass transparent substrate by spin coating, and patterning was carried out by photolithography. mm line width, 0.33mm pitch, film thickness 3
A blue conversion layer 5 having a μm line pattern was obtained. Next, an alkali-soluble negative resist in which coumarin 6 (manufactured by Aldrich) is dispersed is applied by spin coating, patterned by photolithography, and heated at 150 ° C. to have a line width of 0.1 mm and a pitch of 0.33 mm. , Film thickness 8 μm
The green conversion layer 4 having the line pattern was obtained. Further, an alkali-soluble negative resist in which Rhodamine 6G (manufactured by Aldrich) is dispersed is applied by spin coating, patterned by photolithography, and heated at 100 ° C. to have a line width of 0.1 mm and a pitch of 0.33 mm. , Film thickness 10μ
A red conversion layer 3 having a line pattern of m was obtained.

[Preparation of Protective Layer] As a coating solution for the protective layer,
Using a commercially available KP85 (manufactured by Shin-Etsu Chemical Co., Ltd.), apply it on the line pattern of the fluorescent dye layer with a spin coater, leave it at room temperature for 1 hour, and place it in a 120 ° C. oven for 60 hours.
After heating and drying for minutes, the protective layers 1 and 2 were formed.

[Formation of Anode, Organic Layer, Cathode]
On top of this, 6 layers of anode 7 / hole injection layer 8 / hole transport layer 9 / organic light emitting layer 10 / electron injection layer 11 / cathode 12 were sequentially laminated.
First, the anode 7 as a transparent electrode was entirely formed by a sputtering method. Patterning is performed by applying a resist agent (OFPR-800, manufactured by Tokyo Ohka Co., Ltd.) on ITO and then positioning a mask capable of obtaining a line pattern of 0.096 mm line and 0.11 mm pitch with the pattern of the underlying fluorescent dye layer, and then 200 m thick.
Exposure was performed at J / cm ² (365 nm wavelength), and the above-mentioned ITO line pattern was obtained using a developing solution (NMD-3 manufactured by Tokyo Ohka). Next, the substrate was mounted in a resistance heating evaporation apparatus, and a hole injection layer 8, a hole transport layer 9, an organic light emitting layer 10, an electron injection layer 11,
Were sequentially formed. Table 1 shows the structural formulas of the compounds used for each organic layer.

[0047]

[Table 1] During film formation, the pressure in the vacuum chamber was reduced to 1 × 10 ⁻⁴ Pa.
The hole injection layer 8 is made of copper phthalocyanine (CuPc) of 100.
nm. The hole transport layer 9 is made of 4,4'-bis [N-
(1-Naphthyl) -N-phenylamino] biphenyl (α-NPD) was laminated in a thickness of 20 nm. The organic light emitting layer 10 was formed by laminating 4,4′-bis (2,2-diphenylvinyl) biphenyl (DPVBi) to a thickness of 30 nm. Electron injection layer 11
Was formed by laminating aluminum chelate (Alq) to a thickness of 20 nm.

Next, the substrate was taken out of the vacuum chamber, and was newly mounted in a resistance heating evaporation apparatus. As a cathode 12, Mg / Ag (weight ratio of 10: 1) was formed to a thickness of 200 nm in a direction perpendicular to the anode.

Finally, sealing was performed using a glass plate and a UV-curable sealant. Example 2 An element was produced in the same manner as in Example 1 except that KP-64 (manufactured by Shin-Etsu Chemical Co., Ltd.) was applied and formed by a spin coater and heated at 130 ° C. for 30 minutes to form a protective layer. Example 3 As a coating solution for the protective layer, 100 parts by weight of X-40-2269 (manufactured by Shin-Etsu Chemical Co., Ltd.) was added to a curing catalyst CAT-AC.
A liquid was prepared by adding 5 parts by weight (manufactured by Shin-Etsu Chemical Co., Ltd.), coated with a spin coater, and then heated in an oven at 120 ° C. for 60 minutes to form a protective layer. Produced. Example 4 Example 1 was repeated except that the coating liquid for the protective layer was changed to SR2405 (manufactured by Dow Corning Toray Silicone Co., Ltd.) and applied by a spin coater and cured at room temperature for 24 hours to form a protective layer. A device was produced in the same manner as described above. Example 5 The same procedure as in Example 1 was carried out, except that 1% by weight of an ultraviolet absorber represented by the chemical formula (I-2) was added, applied by a spin coater, and cured at 120 ° C. for 1 hour to form a protective layer. An element was manufactured. Example 6 The same procedure as in Example 1 was carried out except that the ultraviolet absorbent represented by the chemical formula (I-3) was added at 1% by weight, applied by a spin coater, and cured at 120 ° C. for 1 hour to form a protective layer. An element was manufactured. Comparative Example 1 Polyfunctional urethane acrylate-based photocurable resin (EM-90, manufactured by Arakawa Chemical Industries) 95 on the pattern of the fluorescent dye layer
A solution prepared by adding 5 parts by weight of a polymerization initiator (Circa Special Chemical: Irgacure 184) and dissolving the same was applied, exposed at a light amount of 1500 mJ / cm ² (365 nm wavelength), and further heated at 80 ° C. A device was produced in the same manner as in Example 1 except that a protective layer was formed by heating. Comparative Example 2 A methacrylate-based oligomer photocurable resin 3112 (manufactured by ThreeBond) was applied on the pattern of the fluorescent dye layer, exposed at a light amount of 1500 mJ / cm ² (365 nm wavelength), and baked at 80 ° C. An element was manufactured in the same manner as in Example 1 except that a protective layer was formed. Example 1
6 and 8 devices obtained in Comparative Examples 1 and 2 were evaluated.
The results are shown in Table 2.

[0050]

[Table 2] The following describes each evaluation item.

[Evaluation 1: Protective Layer Thickness] The height from the substrate surface to the protective layer surface was defined as the protective layer thickness. By using the protective layer of the present invention, a protective layer having a thickness of about 3 to 5 μm could be formed.

[Evaluation 2: Smoothness] The level difference on the surface of the protective layer formed on the fluorescent dye layer was measured using a surface roughness meter (D
EKTAK IIA). According to the protective layer according to the present invention, the average roughness (Ra) of the protective layer after film formation is ± 1 μm
Below, no pattern failure such as disconnection or short circuit of the transparent electrode was observed.

[Evaluation 3: Empitz Hardness] The Empitz hardness was measured by an Empitz hardness test based on JIS standards. In the present invention, it was found that all had a hardness of 3H or more.

[Evaluation 4: Peeling Test] The adhesion of the protective layer formed on each of the glass substrate and the transparent electrode was evaluated by a 1 mm cross hatch peeling test method based on the JIS standard. Those with nine or more points were rated as ○. The adhesion of the protective layer of the present invention was good.

[Evaluation 5: Device Life] FIG. 4 is a diagram showing a change with time of the maximum diameter of the dark spot in the organic light emitting layer of the organic electroluminescent device according to the embodiment of the present invention. The device was stored in the air, and the growth of dark spots inside the organic light emitting layer was observed with an optical microscope. The device was stable when the driving time was 10,000 hours and the diameter of the dark spot was stable at 20 μm or less.

The protective layer of the present invention blocks the components inherent to the organic electroluminescent element, such as the moisture and monomer inherent in the protective layer and the moisture and monomer generated from the phosphor and the like due to the heat generated when the element is driven, and grows the dark spot. It was confirmed that there was an effect on the suppression of odor.

[Evaluation 6: Retention Ratio of Color Conversion Characteristics of Organic EL Device] The color conversion efficiency of the fluorescent dye layer before film formation of the device was evaluated by the characteristic retention ratio after formation of the transparent electrode. When the silicone resin of the present invention was used for the protective layer, the property retention was 9%.
It can be seen that the devices of Examples 5 and 6 to which 0% or more of the ultraviolet absorber was added exhibited a high value of 95% or more.

[0058]

According to the present invention, there is provided an organic device comprising a fluorescent substrate, which is a color conversion filter, a protective layer, an anode, which is a transparent electrode, an organic light emitting layer, and a cathode. In the electroluminescent device, since the protective layer uses at least one selected from a compound of a straight silicone resin or a modified silicone resin, the protective layer can be formed without exposing the fluorescent dye layer to ultraviolet irradiation or high-temperature heating. ,
It has good adhesion to the substrate and the transparent electrode such as the anode and the organic polymer fluorescent dye layer, and has excellent thermal stability.
Furthermore, it has a hardness enough to withstand pressure bonding in the sealing process and the electrode connecting process, so that a fluorescent dye layer with little deterioration in color conversion characteristics can be obtained, the production yield of the device is good, and the life of the organic light emitting layer is long. And a highly reliable organic electroluminescent device can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a manufacturing process in which red, green, and blue fluorescent dye layers are formed on a substrate for an organic electroluminescent device according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a manufacturing process in which a protective layer is provided on a fluorescent dye layer in the organic electroluminescent device according to the embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view showing a manufacturing process in which a hole injection layer, a hole transport layer, an organic light emitting layer, an electron injection layer, and a cathode are sequentially laminated on a protective layer in the organic electroluminescent device according to the embodiment of the present invention.

FIG. 4 is a diagram showing a change over time of a maximum diameter of a dark spot in an organic light emitting layer in the organic electroluminescent device according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Protective layer 2 Protective layer 3 Red dye layer 4 Green dye layer 5 Blue dye layer 6 Glass substrate 7 Anode 8 Hole injection layer 9 Hole transport layer 10 Organic light emitting layer 11 Electron injection layer 12 Cathode

Continued on the front page F term (reference) 2H048 BA45 BA48 BB02 BB14 BB28 BB34 BB37 BB41 3K007 AB04 AB11 AB15 AB18 BB02 BB06 CB01 DA01 DB03 EB00 FA01 FA02

Claims (5)

[Claims] An organic electroluminescent element comprising a fluorescent dye layer serving as a color conversion filter, a protective layer, an anode serving as a transparent electrode, an organic light emitting layer, and a cathode arranged in this order on a transparent substrate. An organic electroluminescent device, wherein the protective layer uses at least one selected from the group consisting of a straight silicone resin and a modified silicone resin. 2. The organic electroluminescent device according to claim 1, wherein the protective layer uses a silicone resin which cures at 150 ° C. or lower. 3. The organic electroluminescent device according to claim 1, wherein the protective layer is formed by laminating different silicone resins. 4. The organic electroluminescent device according to claim 1, wherein the protective layer contains an ultraviolet absorber. 5. The organic electroluminescent device according to claim 1, wherein the protective layer has a thickness of 1 to 20 μm.