JP2001217074A - Manufacturing method of organic EL element - Google Patents

Abstract

(57) Abstract: Provided is a method for manufacturing an organic EL device having a sufficient light emitting region by forming a hole injection layer or a hole transport layer as a layer having a function of a partition. SOLUTION: An anode 2 is formed on a surface of a transparent substrate 1 by a sputtering method and then formed by etching.
Next, a specific hole injection material was dissolved in toluene, and applied to the surface of the transparent substrate 1 on which the anode 2 was formed by spin coating to form a coating film 3. After that, ultraviolet rays are irradiated through a patterning mask 4 disposed above the coating film 3 to expose and cure only a predetermined portion of the coating film 3 and then developed with toluene. A hole injection layer 5 having a reverse taper shape and functioning as a partition having a thickness of 500 nm was formed. Next, a thickness 5 composed of a light emitting layer or the like
An organic EL thin film 6 having a thickness of 0 nm and a cathode 7 having a thickness of 150 nm made of an Mg-Ag alloy were formed in this order, and a sealing member (not shown) was joined to manufacture an organic EL device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a hole injection layer or a hole transport layer which can function as a partition wall.
Organic EL (electroluminescence) that can make the effective light emitting area sufficiently large and enables fine patterning
The present invention relates to a device manufacturing method.

[0002]

2. Description of the Related Art In the manufacture of an organic EL device, micro-patterning of a thin film for forming a light emitting layer and a cathode is performed due to low heat resistance, solvent resistance, moisture resistance, etc. of a light emitting material. Have difficulty. There is also a method of patterning using a vapor deposition mask, but due to poor adhesion between the surface to be vapor-deposited and the mask, the evaporated luminescent material or the like enters the lower surface of the mask, and fine patterning is not easy. On the other hand, when the mask is forcibly brought into close contact with the deposition surface, the thin film may be damaged by the contact of the mask, and the anode and the cathode may be short-circuited.

[0003] JP-A-5-275172 and the like disclose I
A method in which partitions are arranged in parallel on a substrate on which an anode made of TO is formed, and a luminescent material, a cathode material, and the like are deposited on the substrate in a direction perpendicular to the partitions and oblique to the substrate surface. Is disclosed. Japanese Patent Application Laid-Open No. 8-315981 discloses that a plurality of electrically insulating partitions having overhang portions are provided on a surface of a substrate on which a plurality of first display electrodes are formed in a direction perpendicular to the first display electrodes. In addition, an organic electroluminescent display panel in which a light emitting layer and the like and a second display electrode are formed on a surface of a first display electrode and a method of manufacturing the same are disclosed. However, according to the methods disclosed in these publications, it is necessary to separately form a partition wall different from the original element constituent member, and there is a problem that the process is complicated and an effective light emitting region is narrowed.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art. The partition is formed by a hole injection layer or a hole transport layer, which is an original element constituting member. It is an object of the present invention to provide a method of manufacturing an organic EL device which has a sufficient effective light emitting region and can easily manufacture a device having a fine pattern in a usual process.

[0005]

According to a first aspect of the present invention, there is provided a method for manufacturing an organic EL device having a dot matrix electrode configuration, wherein a hole injection layer and a hole injection layer are formed on a surface of a substrate on which an anode is formed. After forming any one of the hole transport layers in a strip shape in the cathode direction by a photolithography method, at least a light emitting layer and a cathode are sequentially formed on the upper surface of the hole injection layer or the hole transport layer. It is characterized by.

The above-mentioned “hole injection layer” or “hole transport layer” formed by photolithography is formed in a strip shape in the same direction as the cathode, functions as a partition, and has a light emitting layer and the like on its upper surface. A cathode is formed. When the hole injection layer is formed as a partition, a normal hole transport layer may be formed on the surface of the hole injection layer, or the hole transport layer may not be provided. When the hole transport layer is formed as a partition,
A normal hole injection layer may be formed in advance on the surface of the substrate on which the anode is formed, and a hole transport layer functioning as a partition may be formed on the surface, or the hole injection layer may not be provided.

On the surface of the substrate on which the anode has been formed, a hole injection layer or a hole transport layer which functions as a partition or a normal hole injection layer is formed, and is formed on the upper surface of the hole injection layer or the hole transport layer which functions as a partition. Is provided with a light emitting layer, and, if necessary, an electron transport layer and an electron injection layer, and an organic EL thin film composed of these organic layers is formed. Further, a cathode is provided on the upper surface of the organic EL thin film. In order for the hole injection layer or the hole transport layer to function as a partition and to reliably separate adjacent cathodes, the hole injection layer or the hole transport layer must be formed of an organic material other than these.
The thickness must exceed the total thickness of the L thin film and the cathode.

The thickness of each of the anode, the organic EL thin film, and the cathode is not particularly limited, but the thickness of the anode can be 150 to 300 nm and the thickness of the cathode can be 50 to 200 nm. In addition, the thickness of the organic EL thin film excluding the hole injection layer or the hole transport layer formed as a partition varies depending on the layer to be formed.
It can be 0 to 150 nm. When the thickness of the organic EL thin film excluding each layer formed as the cathode and the partition is within the above range, the thickness of the hole injection layer or the hole transport layer formed as the partition is formed as the cathode and the partition. Thickness exceeding the total thickness of the organic EL thin film excluding each layer, ie,
The thickness can exceed 70-350 nm.

In order to more reliably separate adjacent cathodes, it is preferable that the thickness be 100 to 150 nm or more than the total thickness of the cathode and the organic EL thin film excluding each layer functioning as a partition. The thickness of the hole injection layer or hole transport layer formed as above is more preferably 200 nm or more. On the other hand, since the hole injection layer or the hole transport layer itself also has resistance, if this layer is too thick, the light emission characteristics deteriorate, and it is necessary to apply a high voltage to obtain the same level of luminance. Therefore, the thickness of the hole injection layer or the hole transport layer formed as a partition is preferably 5 μm or less, more preferably 1 μm or less, and particularly preferably 0.5 μm or less.

The hole injecting material and the hole transporting material used to form the hole injecting layer or the hole transporting layer having a predetermined pattern and functioning as a partition can be formed by photolithography. There is no particular limitation as long as it exists. Examples of such a hole injection material and a hole transport material include an addition condensate of a tertiary amine compound represented by the general formulas (1), (2), (3) and (4) with a carbonyl compound. , Can be selected and used depending on their characteristics. The number average molecular weight of these addition condensates measured by the GPC method is 3,000 to 1,000,000, particularly 10
It is preferably from 000 to 1,000,000. Also,
In each formula, R ₁ is a hydrogen atom or an alkyl group such as a methyl group, an ethyl group, an isopropyl group and a tert-butyl group, an alkoxyl group such as a methoxy group and an ethoxy group, and an aryl group such as a tolyl group; n is a positive integer representing the degree of polymerization.

[0011]

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[0012]

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[0013]

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[0014]

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The specific hole injecting material and hole transporting material include triphenylamine-containing polyetherketone, poly [N- (p-phenylamino) phenylmethacrylamide], and poly (N- A polymer of a heterocyclic compound such as vinyl carbazole) can also be used.

These hole injecting materials and hole transporting materials are blended with other hole injecting materials and hole transporting materials as long as the formability by photolithography is not impaired.
They can be used together. Examples of such a hole injecting material and a hole transporting material include a low molecular weight organic compound that is not a polymer.As the hole injecting material, a copper phthalocyanine complex or the like can be used. For example, a triphenylamine derivative or the like can be used.

The hole injecting layer or the hole transporting layer, which functions as a partition, is formed by dissolving each material in an organic solvent such as toluene and chloroform, and forming a film to a predetermined thickness by a spin coating method, a doctor blade method or the like. The thin film to be formed can be formed by irradiating a thin film with ultraviolet rays or the like using a patterning mask, curing a required portion, and then developing the thin film with an organic solvent such as toluene. In addition, in the case of an addition condensate formed by introducing a diazonium salt into a substituent of a tertiary amine compound used for forming the addition condensate of the general formulas (1) to (4), film formation and exposure Thereafter, it can be formed by developing with an aqueous alkali solution.

By this exposure, ultraviolet light or the like is irradiated from the upper surface side of the thin film, so that the upper surface side of the thin film is hardened more easily than the anode side. A hole injection layer or a hole transport layer having a so-called reverse tapered cross-sectional shape in which the width in the vertical cross section decreases from the side to the anode side is formed. The degree of this inclination is as follows, when the ultraviolet absorber such as benzophenone is used for each material, and the total amount of each material and the ultraviolet absorber is 100% by mass.
It can be adjusted by adding about 0.01 to 0.1% by mass. The vertical cross section of the hole injection layer or the hole transport layer has no taper, that is, the width may be substantially the same on the upper surface side and the anode side, but in the forward taper where the anode side is wider, the subsequent It is difficult to form an organic layer such as a light emitting layer and a cathode by a normal vacuum deposition method or the like. The degree of curing by exposure and the curing speed can be adjusted by adjusting the amount of the ultraviolet absorber.

The "organic EL device" is composed of a substrate, an anode, an organic EL thin film, and a cathode sequentially laminated on the surface of the substrate, and an organic EL laminate formed and joined to an edge of the substrate. And a sealing member for sealing the laminate. As the substrate, in addition to glasses such as soda lime glass, synthetic resins such as polyethylene terephthalate, polyether sulfone, and polycarbonate, and transparent materials such as quartz can be used. Of these, a substrate made of glass is particularly frequently used.

The light emitting layer can be formed of a light emitting material such as an aluminum quinolium complex and a benzoquinolinol Be complex. Further, a doping agent such as a quinacridone derivative or a DCM derivative can be added to these light emitting materials. The electron transport layer can be formed of an aluminum quinolium complex, a hydroxyflavone Be complex, or the like, and the electron injection layer is a fluoride or oxide of an alkali metal such as LiF or a fluoride of an alkaline earth metal such as BaF _2. And the like.

The anode can be formed of a simple metal such as gold and nickel, and a metal compound such as ITO, CuI, SnO ₂ , and ZnO. Of these, ITO is particularly preferred from the viewpoints of productivity, stable conductivity, and the like. The cathode can be formed of an Mg-Ag alloy, sodium, a Na-K alloy, magnesium, lithium, aluminum, or the like. These anodes and cathodes are usually formed in stripes, respectively, and they are perpendicular to each other to form a dot matrix electrode.However, they do not necessarily have to be perpendicular to each other. It may be.

Each of these layers constituting the organic EL element comprises:
It can be formed by a vacuum evaporation method, and can also be formed by other various methods such as a spin coating method, a casting method, a sputtering method, and an LB method.

As the sealing member, a member made of a metal such as stainless steel, aluminum or an alloy thereof, a glass such as soda-lime glass or silicate glass, or a synthetic resin such as an acrylic resin or a styrene resin is used. Can be. The joining between the sealing member and the peripheral edge of the substrate can be performed using a thermosetting resin such as an epoxy resin or an acrylate resin, or a sealing resin such as a photocurable resin. Among these, it is preferable to use a sealing resin that forms a cured body through which moisture or the like hardly permeates in order to suppress a decrease in luminance or the like. Also, thermal stress applied to the element can be reduced,
A photocurable resin having a high curing rate is more preferable.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail by way of an embodiment with reference to FIGS. Example 1 An ITO film was formed on the surface of a transparent substrate 1 made of glass by a sputtering method, and a striped anode 2 was formed by etching. Thereafter, the polymer represented by the general formula (1) (R ₁ is a hydrogen atom) is dissolved in toluene, and this toluene solution is applied to the anode 2 by spin coating.
Was applied to the surface of the transparent substrate 1 on which was formed, dried, and toluene was removed to form a coating film 3 to obtain a laminate shown in FIG.

Next, as shown in FIG. 2, a patterning mask 4 is provided above the coating film 3, and ultraviolet light is irradiated through the mask to expose only a predetermined portion of the coating film 3.
After the curing, development was performed with toluene, and uncured materials were removed as necessary. In this manner, the hole injection layer 5 functioning as a 500-nm-thick partition wall having a vertical cross section and an inversely tapered shape in FIG. 3 was formed. Thereafter, on the upper surface of the hole injection layer 5, a 50 nm-thick organic EL thin film 6 (excluding the hole injection layer 5) composed of a light emitting layer and the like and a 150 nm thickness composed of an Mg-Ag alloy are formed by a vacuum evaporation method. Are formed in this order to form an organic EL laminate, thereby forming a composite comprising the transparent substrate 1 and the organic EL laminate shown in FIG. Next, a sealing member (not shown) was joined to the peripheral edge of the transparent substrate 1 with a sealing resin to seal the organic EL laminate, thereby manufacturing an organic EL element.

In this organic EL device, the total thickness of the organic EL thin film 6 and the cathode 7 is 200 nm, and the thickness of the hole injection layer 5 functioning as a partition is 500 nm. Therefore, the cathodes 7 formed in a stripe shape on the upper surface of the hole injection layer 5 are separated from each other as shown in FIG. 4 and sufficiently separated from the anode 2.
Short circuit is reliably prevented.

Example 2 By making the ultraviolet irradiation time longer than that in Example 1 and completely curing the coating film, the hole injection layer 5 having a vertical cross-section without taper and functioning as a partition was formed. , Except that the cathode material was deposited obliquely to form the cathode 7,
An organic EL device was manufactured in the same manner as in Example 1. In the organic EL device manufactured in this manner, the striped cathodes 7 formed on the upper surface and one side surface of the hole injection layer 5 are separated from each other as shown in FIG. Since they are separated from each other, a short circuit between the anode 2 and the cathode 7 is reliably prevented.

Embodiment 3 An insulating layer 8 is formed on the surface of the transparent substrate 1 on which the anode 2 is formed, and the insulating layer 8 is overlapped by a required width with the lower surface of each of the adjacent hole injection layers 5 functioning as partition walls. An organic EL device was manufactured in the same manner as in Example 1. This insulating layer 8 is formed as shown in FIG. 6, whereby the short circuit between the anode 2 and the cathode 7 is more reliably prevented. The insulating layer 8 is formed by applying a photoresist material to the surface of the transparent substrate 1 on which the anode 2 is formed by a spin coating method or the like, drying and forming a coating film, and then exposing, developing, washing, and heating. Formed.

COMPARATIVE EXAMPLE 1 A striped insulating layer 8 was formed on the surface of the transparent substrate 1 on which the anode 2 was formed at predetermined intervals in a direction perpendicular to the anode 2 in the same manner as in Example 3. In the center in the width direction,
As in the prior art, a partition 9 shown in FIG. 7 having a tapered cross section made of a polyimide resin is formed, and an organic EL thin film 6 (in this thin film,
When a hole injection layer and a hole transport layer are formed, these layers are included. ) And the cathode 7 were sequentially formed by a vacuum evaporation method to produce an organic EL device.

In the third embodiment, it is not necessary to consider the adhesion of the hole injection layer to the anode, etc., for the hole injection layer functioning as a partition, and the insulating layer is formed on the lower side of each hole injection layer as shown in FIG. Need only be formed in the vicinity of. Therefore, the distance between the hole injection layers is not particularly limited, and can be reduced to about 1 μm, and the width of the insulating layer is at most about 10 μm. On the other hand, when a partition is separately formed as in the conventional example of Comparative Example 1, an insulating layer is practically indispensable in order to prevent a short circuit between the anode and the cathode, and as shown in FIG. The partition must be formed at the center in the width direction, and the width of the partition is 10 μm due to the close contact between the insulating layer and the partition and the technical limitation of the photolithography method.
m or more, and the width of the insulating layer is at least 2
It must be 0 μm.

For these reasons, the organic EL of Example 3
In the device, the effective light emitting area can be made wider than that of the device of Comparative Example 1. Table 1 shows a comparison of the effective light emitting area ratios of the organic EL elements of a specific size manufactured as in Example 3 and Comparative Example 1.

[0032]

[Table 1]

According to the results shown in Table 1, the effective light emitting area ratio of the 5.2-inch and 5.7-inch organic EL devices in Example 3 was higher than that in Comparative Example 1 in both cases. About 10% larger than the organic E of the present invention.
In the L element, the effect that the effective light emitting region can be sufficiently widened is supported.

It should be noted that the present invention is not limited to the above embodiment, but may be variously modified within the scope of the present invention according to the purpose and application. For example, in the organic EL element of Example 2, the anode 2 and the cathode 7 are separated via the organic EL thin film 6, but in order to more reliably prevent a short circuit, the anode 2 is also used in this organic EL element. It is preferable that an insulating layer is formed on the surface of the formed transparent substrate 1 so as to overlap the lower surface of each of the hole injection layers 5 with a required width.

[0035]

According to the present invention, a hole injection layer or a hole transport layer, which is an elementary element, is made to function as a partition wall, thereby providing an organic light emitting device having a sufficient effective light emitting region and a fine pattern. An EL element can be easily manufactured by a usual process.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a longitudinal section of a laminate composed of a coating film on which a substrate, an anode and a hole injection layer are formed in Examples.

FIG. 2 is a schematic diagram showing a state in which a patterning mask is provided above to expose a coating film.

FIG. 3 is a schematic view showing a hole injection layer having a tapered vertical cross section formed by exposure and development.

FIG. 4 is a schematic view showing a vertical cross section of a laminate in which an organic EL thin film and a cathode except for the hole injection layer are formed on the upper surface of the hole injection layer.

FIG. 5 is a schematic diagram showing a longitudinal section of a composite in which a hole injection layer has a cross-sectional shape having no taper and a cathode is formed by vapor deposition from an oblique direction.

FIG. 6 is a schematic diagram showing a vertical cross section of a hole injection layer, an insulating layer, and the like functioning as a partition in the organic EL device of the present invention.

FIG. 7 is a schematic view showing a longitudinal section of a conventional partition wall, insulating layer, and the like separately formed as a member different from a constituent member of an organic EL element.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1; Transparent substrate, 2; Anode, 3; Coating, 4; Patterning mask, 5; Hole injection layer functioning as a partition, 6; Organic EL thin film, 7; Cathode, 8; Insulating layer, 9; Made of a polyimide resin.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Koji Muta 2-1-1 Toyota-cho, Kariya-shi, Aichi Prefecture Inside Toyota Industries Corporation (72) Inventor Ichiro Izumi 3-260 Toyota, Oguchi-machi, Oguchi-machi, Niwa-gun, Aichi Prefecture. Tokai Rika Co., Ltd. F term (reference) 3K007 AB18 BA06 BB01 CA01 CA02 CA05 CB01 CB03 DA00 DB03 EB00 FA01 FA02

Claims (1)

[Claims] In a method of manufacturing an organic EL device having a dot matrix electrode configuration, one of a hole injection layer and a hole transport layer is formed on a surface of a substrate on which an anode is formed by a photolithography method. A method for manufacturing an organic EL device, comprising: forming a strip in the direction of a cathode, and then sequentially forming at least a light emitting layer and a cathode on the upper surface of the hole injection layer or the hole transport layer.