WO2009122973A1

WO2009122973A1 - Method of manufacturing organic electro luminescence element, organic electro luminescence element, and display device

Info

Publication number: WO2009122973A1
Application number: PCT/JP2009/055861
Authority: WO
Inventors: 行一六原
Original assignee: 住友化学株式会社
Priority date: 2008-03-31
Filing date: 2009-03-24
Publication date: 2009-10-08
Also published as: TW200952543A; JP2009266805A

Abstract

A method of manufacturing an organic EL element which comprises a cathode, an anode, and an organic light-emitting layer positioned between the cathode and anode. The method is characterized by preparing a substrate provided with partition walls arranged opposing one another nearly in parallel, and provided with the anode; and including an organic light-emitting layer forming process wherein, by use of a letterpress printing plate provided with convex portions provided opposing one another nearly in parallel corresponding to concave portions between the partition walls, an organic light-emitting ink containing organic light-emitting material and a solvent is continuously supplied to the concave portions along the longitudinal direction of the partition walls, thereby forming the organic light-emitting layer. Using the method of manufacturing allows providing the organic EL element which avoids color mixture in the organic color-emitting layer formed in pixel areas by preventing printing deviation when applying the organic light-emitting ink to the pixel areas demarcated by the insulating partition walls by a letterpress printing method without degrading efficiency in manufacturing, and allows providing a display device including the organic EL element.

Description

Organic electroluminescent element manufacturing method, organic electroluminescent element, and display device

The present invention relates to a method for producing an organic electroluminescence element (hereinafter sometimes referred to as an organic EL element), an organic EL element obtained by using the production method, and a display device including the organic EL element. . More specifically, the present invention prevents printing misalignment when an organic light emitting ink is applied to a plurality of pixel areas defined by insulating partition walls by a relief printing method, and the organic light emitting layer formed in the pixel area The present invention relates to a method for producing an organic EL element that does not cause color mixing, an organic EL element obtained by using the production method, and a display device including the organic EL element.

As is well known, an organic EL element has, as a basic structure, a first electrode (one electrode of an anode and a cathode) and a second electrode (the other electrode of an anode and a cathode), and these And an organic light emitting layer provided between the electrodes. In such a structure, the organic light emitting layer emits light by passing a current between electrodes facing each other across the organic light emitting layer.

Usually, a display device using organic EL elements uses a display panel in which a large number of organic EL elements each functioning as one pixel are arranged in a matrix. In such a display panel, in order to secure a large number of pixels, the first electrode is formed in a fine stripe pattern, and a large number of pixel regions are formed on the patterned first electrode. A grid-like partition is formed. The partition walls are formed by forming a photoresist film on the first electrode pattern and patterning the photoresist film using a photolithography technique. The first electrode is exposed in a region surrounded by the partition wall, and this region becomes a pixel region. That is, the pixel regions are arranged in a matrix at predetermined intervals in the row direction and the column direction.

In the conventional technology, an organic light-emitting ink containing an organic light-emitting material and a solvent is supplied into each partition using a relief printing plate having a plurality of convex portions arranged in a matrix corresponding to the arrangement of pixel regions. Thus, an organic light emitting layer is formed (see, for example, Patent Document 1).

JP 2006-286243 A

As described in Patent Document 1, a method of attaching various inks to each pixel region using a relief printing method is a method suitable for efficiently producing an organic EL element. According to the results, it was found that there are problems to be solved as follows.

When printing on a pixel area defined by a partition using a relief printing plate, it is necessary to accurately align the plurality of convex portions provided on the relief printing plate and the plurality of pixel areas, respectively. The tolerance is small, and the plate cylinder direction of the relief printing plate, the positional accuracy in the circumferential direction, and the angular accuracy in the feeding direction of the substrate are strict, making it difficult to manufacture efficiently.

The present invention has been made in view of the above-described conventional circumstances, and the problem is that an organic light-emitting ink is applied to a plurality of pixel regions defined by insulating partition walls by a relief printing method without reducing manufacturing efficiency. Manufacturing method of organic EL element which prevents printing misalignment at the time of application and does not cause color mixing in organic light emitting layer formed in pixel region, organic EL element obtained using the manufacturing method, and organic EL element An object of the present invention is to provide a display device including an element.

In order to solve the above-mentioned problems, the present invention provides a method for manufacturing an organic electroluminescence element adopting the following configuration, an organic electroluminescence element obtained by using the manufacturing method, and a display device including the organic electroluminescence element I will provide a.

[1] A method of manufacturing an organic electroluminescence device having a cathode, an anode, and an organic light emitting layer positioned between the cathode and the anode, and a plurality of partition walls disposed substantially parallel to each other, A substrate provided with the anode, and using a relief printing plate having a plurality of convex portions disposed in a substantially parallel relationship corresponding to the concave portions between the partition walls, an organic light emitting material and An organic light-emitting layer forming step of forming the organic light-emitting layer by continuously supplying an organic light-emitting ink containing a solvent to the recess along the longitudinal direction of the partition wall. Production method.

[2] In the substrate, a plurality of pixel regions in which pixels are formed are set along the partition between the partition walls, and the height from the substrate is lower than the partition between adjacent pixel regions. The method for producing an organic electroluminescent element according to the above [1], wherein an electrical insulating layer is disposed.

[3] The relief printing plate is cylindrical or columnar, and the plurality of protrusions are arranged so that a longitudinal direction of the plurality of protrusions coincides with a circumferential direction. The manufacturing method of the organic electroluminescent element as described in said [1] or [2].

[4] An organic electroluminescence device obtained by using the production method according to any one of [1] to [3] above.

[5] A display device comprising the organic electroluminescence element according to [4] above.

In the method for producing an organic EL element according to the present invention, the organic light-emitting ink is continuously applied along the longitudinal direction of the partition wall (hereinafter, “the longitudinal direction of the partition wall” may be referred to as “the extending direction of the partition wall”). Since the organic light emitting layer is formed by supplying (coating), the alignment accuracy in the direction in which the partition wall extends can be relaxed, and the production efficiency can be improved while maintaining high-precision printing.

Therefore, according to the present invention, it is possible to produce an organic EL element by preventing printing misalignment when applying organic light emitting ink by the relief printing method without reducing the production efficiency, and formed in the pixel region. An organic EL element that does not cause color mixing in the organic light emitting layer and a display device having the organic EL element can be efficiently manufactured.

FIG. 1 is a plan view of a substrate on which a partition wall is formed. FIG. 2 is a cross-sectional configuration diagram of the substrate as seen from the section line II-II in FIG. FIG. 3 is a perspective view showing the structure of the relief printing plate used in the present invention and the positional relationship with the substrate during printing of the organic light emitting layer using the relief printing plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Anode 13a Partition 13b Electrical insulation layer 14 Pixel area 15 Concave part 20 Letterpress printing plate 21 Convex part of letterpress printing plate

Hereinafter, the structure of the organic EL element targeted by the method of the present invention will be described, and then the method for manufacturing the organic EL element according to the present invention will be described in more detail. Note that the scale of each member in the drawings shown in the following description may differ from the actual scale. Moreover, although members, such as an electrode lead wire, also exist in an organic EL element, description and illustration are abbreviate | omitted since it is not directly related as description of this invention. In the following description, one of the substrate thickness directions may be referred to as “upper” or “upper”, and the other of the substrate thickness directions may be referred to as “lower” or “lower”. This vertical relationship is set for convenience of explanation, and is not necessarily applied to a process of actually manufacturing an organic EL element and a situation in which it is used.

(substrate)
The substrate used for the organic EL element may be any substrate that does not change when the electrode is formed and the organic layer is formed. For example, glass, plastic, polymer film, silicon substrate, or a laminate of these is used. It is done. Further, a plastic, a polymer film or the like that has been subjected to a low water permeability treatment may be used. A commercially available substrate can be used as the substrate, or it may be manufactured by a known method.

(Electrode and organic light emitting layer)
As a basic structure of the organic EL element, at least an anode, a cathode, and an organic light emitting layer (hereinafter, “organic light emitting layer” may be simply referred to as “light emitting layer”) positioned between the anode and the cathode. Are stacked. Further, at least one of the anode and the cathode is made of a transparent electrode having optical transparency. For the light emitting layer, a low molecular weight and / or high molecular weight organic light emitting material is used. In the present specification, the term “transparent” means a property showing light transmittance and means that all or a part of light incident on a predetermined member is transmitted.

In the organic EL element, a plurality of light emitting layers may be provided between the anode and the cathode, or layers other than the light emitting layer may be provided. Hereinafter, a layer provided between the cathode and the light-emitting layer may be referred to as a cathode-side interlayer, and a layer provided between the anode and the light-emitting layer may be referred to as an anode-side interlayer.

Examples of the anode-side interlayer provided between the anode and the light emitting layer include a hole injection layer, a hole transport layer, and an electron block layer.

The hole injection layer is a layer having a function of improving the efficiency of hole injection from the cathode, and the hole transport layer is a positive hole from the hole injection layer or a layer closer to the anode (hole transport layer). This layer has a function of improving hole injection. When the hole injection layer or the hole transport layer has a function of blocking electron transport, these layers may be referred to as an electron block layer. Having the function of blocking electron transport makes it possible, for example, to manufacture an element that allows only electron current to flow and to confirm the blocking effect by reducing the current value.

The electron injection layer is a layer having a function of improving electron injection efficiency from the cathode, and the electron transport layer has a function of improving electron injection from the electron injection layer or a layer closer to the cathode (electron transport layer). It is a layer having. When the electron injection layer or the electron transport layer has a function of blocking hole transport, these layers may be referred to as a hole blocking layer. Having the function of blocking hole transport makes it possible, for example, to produce an element that allows only hole current to flow, and confirm the blocking effect by reducing the current value.

The layered structure of each layer provided between the anode and the cathode as described above includes a hole transport layer provided between the anode and the light emitting layer, and an electron transport layer provided between the cathode and the light emitting layer. And a structure in which an electron transport layer is provided between the cathode and the light emitting layer and a hole transport layer is provided between the anode and the light emitting layer. For example, the following laminated structures a) to d) are specifically exemplified.
a) Anode / light emitting layer / cathode b) Anode / hole transport layer / light emitting layer / cathode c) Anode / light emitting layer / electron transport layer / cathode d) Anode / hole transport layer / light emitting layer / electron transport layer / cathode (Here, / indicates that each layer is laminated adjacently. The same applies hereinafter.)

In the above configuration, as described above, the light emitting layer is a layer having a function of emitting light, the hole transporting layer is a layer having a function of transporting holes, and the electron transporting layer is a function of transporting electrons. It is a layer which has. Note that the electron transport layer and the hole transport layer may be collectively referred to as a charge transport layer. Two or more light emitting layers, hole transport layers, and electron transport layers may be used independently. Further, among the charge transport layers provided adjacent to the electrodes, those having a function of improving the charge injection efficiency from the electrodes and having the effect of lowering the driving voltage of the element are particularly charge injection layers (hole injection layers). , Sometimes referred to as an electron injection layer).

Further, in order to improve the adhesion with the electrode and the charge injection from the electrode, the charge injection layer or an insulating layer having a thickness of 2 nm or less may be provided adjacent to the electrode, and the adhesion at the interface is improved. In order to prevent mixing, a thin buffer layer may be inserted at the interface between the charge transport layer and the light emitting layer. The order and number of layers to be laminated and the thickness of each layer can be set as appropriate in consideration of light emission efficiency and element lifetime.

Moreover, as an organic EL element provided with a charge injection layer (electron injection layer, hole injection layer), an organic EL element provided with a charge injection layer adjacent to the cathode, and a charge injection layer provided adjacent to the anode. An organic EL element is mentioned. For example, the following structures e) to p) are specifically mentioned.
e) Anode / charge injection layer / light emitting layer / cathode f) Anode / light emitting layer / charge injection layer / cathode g) Anode / charge injection layer / light emitting layer / charge injection layer / cathode h) Anode / charge injection layer / hole Transport layer / light emitting layer / cathode i) anode / hole transport layer / light emitting layer / charge injection layer / cathode j) anode / charge injection layer / hole transport layer / light emitting layer / charge injection layer / cathode k) anode / charge Injection layer / light emitting layer / charge transport layer / cathode l) anode / light emitting layer / electron transport layer / charge injection layer / cathode m) anode / charge injection layer / light emitting layer / electron transport layer / charge injection layer / cathode n) anode / Charge injection layer / hole transport layer / light emitting layer / charge transport layer / cathode o) anode / hole transport layer / light emitting layer / electron transport layer / charge injection layer / cathode p) anode / charge injection layer / hole transport Layer / light emitting layer / electron transport layer / charge injection layer / cathode

(anode)
For the anode, for example, a metal oxide, metal sulfide or metal thin film having high electrical conductivity can be used as a transparent electrode, and among them, those having a high transmittance can be suitably used. These are appropriately selected and used depending on the organic layer to be used. Specifically, indium oxide, zinc oxide, tin oxide, indium tin oxide (abbreviated as ITO), indium zinc oxide (abbreviated as IZO), gold, platinum, silver, copper, and the like A thin film is used, and among these, ITO, IZO, and tin oxide are preferable.

Also, an organic transparent conductive film such as polyaniline or a derivative thereof, polythiophene or a derivative thereof may be used as the anode. In addition, a thin film made of a mixture containing at least one selected from the group consisting of materials used for the organic transparent conductive film, metal oxides, metal sulfides, metals, and carbon materials such as carbon nanotubes is used as an anode. It may be used.

Furthermore, a material that reflects light may be used for the anode, and such a material is preferably a metal, metal oxide, or metal sulfide having a work function of 3.0 eV or more.

Examples of methods for producing the anode include a vacuum deposition method, a sputtering method, an ion plating method, and a plating method.

The thickness of the anode can be appropriately selected in consideration of light transmittance and electrical conductivity, and is, for example, 5 nm to 10 μm, preferably 10 nm to 1 μm, and more preferably 20 nm to 500 nm. .

(Anode side interlayer)
As described above, an anode-side interlayer such as a hole injection layer and a hole transport layer is laminated between the anode and the light emitting layer as necessary.

(Hole injection layer)
As described above, the hole injection layer is provided between the anode and the hole transport layer or between the anode and the light emitting layer. As a material for forming the hole injection layer, a known material can be appropriately used, and there is no particular limitation. For example, phenylamine, starburst amine, phthalocyanine, hydrazone derivative, carbazole derivative, triazole derivative, imidazole derivative, oxadiazole derivative having amino group, vanadium oxide, tantalum oxide, tungsten oxide, molybdenum oxide, ruthenium oxide And oxides such as aluminum oxide, amorphous carbon, polyaniline, polythiophene derivatives, and the like.

The thickness of such a hole injection layer is preferably about 5 to 300 nm. If the thickness is less than 5 nm, the production tends to be difficult. On the other hand, if the thickness exceeds 300 nm, the driving voltage and the voltage applied to the hole injection layer tend to increase.

(Hole transport layer)
The material constituting the hole transport layer is not particularly limited. For example, N, N′-diphenyl-N, N′-di (3-methylphenyl) 4,4′-diaminobiphenyl (TPD), 4 , 4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPB), etc., polyvinyl carbazole or derivatives thereof, polysilane or derivatives thereof, aromatic amines in the side chain or main chain Polysiloxane derivatives having pyrazole, pyrazoline derivatives, arylamine derivatives, stilbene derivatives, triphenyldiamine derivatives, polyaniline or derivatives thereof, polythiophene or derivatives thereof, polyarylamine or derivatives thereof, polypyrrole or derivatives thereof, poly (p-phenylene vinylene) Or its derivatives, or poly (2,5-thienylene vinylene) or a derivative thereof.

Among these, as the hole transport material used for the hole transport layer, polyvinyl carbazole or a derivative thereof, polysilane or a derivative thereof, a polysiloxane derivative having an aromatic amine compound group in a side chain or a main chain, polyaniline or a derivative thereof, Polymeric hole transport materials such as polythiophene or derivatives thereof, polyarylamine or derivatives thereof, poly (p-phenylene vinylene) or derivatives thereof, or poly (2,5-thienylene vinylene) or derivatives thereof are preferred, and more preferred Is polyvinyl carbazole or a derivative thereof, polysilane or a derivative thereof, and a polysiloxane derivative having an aromatic amine in the side chain or main chain. In the case of a low-molecular hole transport material, it is preferably used by being dispersed in a polymer binder.

The thickness of the hole transport layer is not particularly limited, but may be appropriately changed according to the intended design, and is preferably about 1 to 1000 nm. If the thickness is less than the lower limit, production tends to be difficult or the effect of hole transport is not sufficiently obtained. On the other hand, if the thickness exceeds the upper limit, the driving voltage and the hole transport layer are increased. There is a tendency that the voltage applied to is increased. Therefore, as described above, the thickness of the hole transport layer is preferably 1 to 1000 nm, more preferably 2 nm to 500 nm, and still more preferably 5 nm to 200 nm.

(Organic light emitting layer)
The organic light emitting layer usually contains organic substances (low molecular compounds and high molecular compounds) that mainly emit fluorescence or phosphorescence. Further, a dopant material may be further included. Examples of the material for forming the organic light emitting layer that may be used in the present invention include the following dye materials, metal complex materials, polymer materials, and dopant materials.

Examples of the dye material include cyclopentamine derivatives, tetraphenylbutadiene derivative compounds, triphenylamine derivatives, oxadiazole derivatives, quinacridone derivatives, coumarin derivatives, pyrazoloquinoline derivatives, distyrylbenzene derivatives, distyrylarylene derivatives. Pyrrole derivatives, thiophene ring compounds, pyridine ring compounds, perinone derivatives, perylene derivatives, oligothiophene derivatives, oxadiazole dimers, pyrazoline dimers, and the like.

Examples of the metal complex materials include metal complexes having light emission from triplet excited states such as iridium complexes and platinum complexes, aluminum quinolinol complexes, benzoquinolinol beryllium complexes, benzoxazolyl zinc complexes, benzothiazole zinc complexes, Examples thereof include metal complexes such as azomethyl zinc complex, porphyrin zinc complex, and europium complex. These metal complexes have Al, Zn, Be, Ir, Pt or the like as a central metal, or rare earth metals such as Tb, Eu, or Dy, and oxadiazole, thiadiazole, phenylpyridine, or phenylbenzimidazole as a ligand. And a metal complex having a quinoline structure and the like.

Examples of the polymer material include a polyparaphenylene vinylene derivative, a polythiophene derivative, a polyparaphenylene derivative, a polysilane derivative, a polyacetylene derivative, a polyfluorene derivative, a polyvinylcarbazole derivative, and the above-described dye bodies and metal complex light emitting materials. And the like.

Examples of materials that emit blue light among the organic light emitting layer forming materials include distyrylarylene derivatives, oxadiazole derivatives, and polymers thereof, polyvinylcarbazole derivatives, polyparaphenylene derivatives, polyfluorene derivatives, and the like. . Of these, polymer materials such as polyvinyl carbazole derivatives, polyparaphenylene derivatives, and polyfluorene derivatives are preferred.

In addition, examples of the material that emits green light among the organic light emitting layer forming materials include quinacridone derivatives, coumarin derivatives, and polymers thereof, polyparaphenylene vinylene derivatives, polyfluorene derivatives, and the like. Of these, polymer materials such as polyparaphenylene vinylene derivatives and polyfluorene derivatives are preferred.

In addition, examples of the material that emits red light among the above light emitting layer forming materials include coumarin derivatives, thiophene ring compounds, and polymers thereof, polyparaphenylene vinylene derivatives, polythiophene derivatives, polyfluorene derivatives, and the like. Among these, polymer materials such as polyparaphenylene vinylene derivatives, polythiophene derivatives, and polyfluorene derivatives are preferable.

A dopant may be added to the organic light emitting layer for the purpose of improving the light emission efficiency or changing the light emission wavelength. Examples of such dopants include perylene derivatives, coumarin derivatives, rubrene derivatives, quinacridone derivatives, squalium derivatives, porphyrin derivatives, styryl dyes, tetracene derivatives, pyrazolone derivatives, decacyclene, phenoxazone, and the like.
The thickness of the organic light emitting layer is usually 2 nm to 200 nm.

(Cathode side interlayer)
As described above, a cathode-side interlayer such as an electron injection layer and an electron transport layer is laminated between the light emitting layer and a cathode described later, if necessary.

(Electron transport layer)
As the material for forming the electron transport layer, known materials can be used. For example, oxadiazole derivatives, anthraquinodimethane or derivatives thereof, benzoquinone or derivatives thereof, naphthoquinone or derivatives thereof, anthraquinones or derivatives thereof, tetracyanoanthra Quinodimethane or derivatives thereof, fluorenone derivatives, diphenyldicyanoethylene or derivatives thereof, diphenoquinone derivatives, or metal complexes of 8-hydroxyquinoline or derivatives thereof, polyquinoline or derivatives thereof, polyquinoxaline or derivatives thereof, polyfluorene or derivatives thereof, etc. Can be mentioned.

Of these, oxadiazole derivatives, benzoquinone or derivatives thereof, anthraquinones or derivatives thereof, or metal complexes of 8-hydroxyquinoline or derivatives thereof, polyquinoline or derivatives thereof, polyquinoxaline or derivatives thereof, polyfluorene or derivatives thereof are preferred, 2- (4-biphenylyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole, benzoquinone, anthraquinone, tris (8-quinolinol) aluminum, and polyquinoline are more preferable.

(Electron injection layer)
As described above, the electron injection layer is provided between the electron transport layer and the cathode, or between the light emitting layer and the cathode. Depending on the type of the light emitting layer, the electron injection layer may be an alkali metal or alkaline earth metal, an alloy containing one or more of the above metals, an oxide, halide and carbonate of the metal, or a mixture of the substances. Etc.

Examples of the alkali metal or its oxide, halide, carbonate include lithium, sodium, potassium, rubidium, cesium, lithium oxide, lithium fluoride, sodium oxide, sodium fluoride, potassium oxide, potassium fluoride, oxide Examples include rubidium, rubidium fluoride, cesium oxide, cesium fluoride, and lithium carbonate.

Examples of the alkaline earth metals or oxides, halides and carbonates thereof include magnesium, calcium, barium, strontium, magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride, calcium fluoride, barium oxide, fluorine. Barium fluoride, strontium oxide, strontium fluoride, magnesium carbonate and the like.

Furthermore, a metal, a metal oxide, an organometallic compound doped with a metal salt, an organometallic complex compound, or a mixture thereof can also be used as a material for the electron injection layer.

This electron injection layer may have a stacked structure in which two or more layers are stacked. Specifically, Li / Ca etc. are mentioned. This electron injection layer is formed by vapor deposition, sputtering, printing, or the like.
The thickness of the electron injection layer is preferably about 1 nm to 1 μm.

(cathode)
As a material for the cathode, a material having a small work function and easy electron injection into the light emitting layer and / or a material having a high electric conductivity and / or a material having a high visible light reflectance are preferable. Specific examples of such cathode materials include metals, metal oxides, alloys, graphite or graphite intercalation compounds, and inorganic semiconductors such as zinc oxide (ZnO).

As the metal, alkali metal, alkaline earth metal, transition metal, periodic table group 13 metal, or the like can be used. Specific examples of these metals include lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten, tin, and aluminum. , Scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, ytterbium, and the like.

Examples of the alloy include an alloy containing at least one of the above metals, and specifically, a magnesium-silver alloy, a magnesium-indium alloy, a magnesium-aluminum alloy, an indium-silver alloy, a lithium-aluminum alloy, a lithium- Examples include a magnesium alloy, a lithium-indium alloy, and a calcium-aluminum alloy.

The cathode is a transparent electrode as necessary. Examples of the material include conductive oxides such as indium oxide, zinc oxide, tin oxide, ITO, and IZO; polyaniline or a derivative thereof, polythiophene or a derivative thereof. And conductive organic substances such as

The cathode may have a laminated structure of two or more layers. Moreover, an electron injection layer may be used as a cathode.

The thickness of the cathode may be appropriately selected in consideration of electric conductivity and durability, and is, for example, 10 nm to 10 μm, preferably 20 nm to 1 μm, and more preferably 50 nm to 500 nm.

(Upper sealing film)
After the cathode is formed as described above, an upper sealing film for sealing the light emitting function part is formed in order to protect the light emitting function part having the anode-light emitting layer-cathode as a basic structure. . This upper sealing film usually has at least one inorganic layer and at least one organic layer. The number of stacked layers is determined as necessary. Basically, inorganic layers and organic layers are alternately stacked.

Even if the light emitting function part is encapsulated by the substrate and the upper sealing film, the plastic substrate has higher gas and liquid permeability than the glass substrate, and light emitting substances such as the organic light emitting layer are easily oxidized. Deteriorated easily by contact with water. Therefore, when a plastic substrate is used as the substrate, a lower sealing film having a high barrier property against gas and liquid is laminated on the plastic substrate, and then the light emitting function part is laminated on the lower sealing film. . The lower sealing film is usually formed with the same configuration and the same material as the upper sealing film.

[Method of manufacturing organic EL element]
Hereinafter, the manufacturing method of the organic EL element of embodiment of this invention is demonstrated in detail.

(Anode formation process)
A substrate made of any of the aforementioned substrate materials is prepared. When a plastic substrate having high gas and liquid permeability is used, a lower sealing film is formed on the substrate as necessary.

Next, an anode is patterned on the prepared substrate using any of the anode materials described above. A plurality of anodes are formed, for example, on the substrate, and are formed in a pattern, for example, in the form of vertical stripes (or horizontal stripes) as viewed from the thickness direction of the substrate, substantially parallel to each other. Hereinafter, a pattern in which a plurality of members are arranged in a vertical stripe shape (or a horizontal stripe shape) so as to be substantially parallel to each other may be referred to as a “stripe shape”. The anode pattern is not limited to the stripe shape, and for example, the anode may be provided electrically independently for each pixel. For example, the anode may be provided discretely in a matrix shape. When this anode is used as a transparent electrode, as described above, a transparent electrode material such as ITO, IZO, tin oxide, zinc oxide, indium oxide, and zinc aluminum composite oxide is used. For example, in the case of using ITO, the electrode pattern is formed as a uniform deposited film on the substrate by a sputtering method, and then patterned into a line shape by photolithography.

(Partition forming process)
FIG. 1 is a plan view of a substrate on which a partition wall is formed, and FIG. 2 is a cross-sectional view of the substrate as seen from the section line II-II in FIG. First, the anode 2 is formed on the substrate 1, and a plurality of partition walls 13a arranged in a stripe shape are formed on the electrode. As described above, a plurality of anodes 2 are striped so that the longitudinal direction thereof coincides with the longitudinal direction of the partition wall 13a (hereinafter, the “longitudinal direction of the partition wall” may be referred to as “the extending direction of the partition wall 13a”). In the present embodiment, a plurality of anodes 2 are arranged in stripes, and partition walls 13a are arranged so as to overlap the gaps between the anodes 2 when viewed from one side in the thickness direction of the substrate 1. The Further, a plurality of pixel regions 14 in which pixels are formed may be set along the partition wall 13a between the partition walls 13a.

An electrical insulating layer 13b having a height from the substrate 1 lower than that of the partition wall 13a may be provided between the pixel regions 14 adjacent to each other in the longitudinal direction of the partition wall 13a. In the present embodiment, on the substrate 1 on which the anode 2 is formed, the electrical insulating layers 13b are provided in a lattice shape. Specifically, the pixels adjacent to the longitudinal direction of the partition wall 13a when viewed from one side in the thickness direction of the substrate. A grid-like electrical insulating layer 13b is provided which is composed of horizontal stripes extending between the regions 14 and vertical stripes extending between the anodes.

This electric insulating layer 13b is usually formed with an insulating film having a thickness of 0.1 to 0.2 μm made of an inorganic insulating material such as SiO ₂ or SiN by a known method such as plasma CVD or sputtering, as will be described later. And then formed by performing photography and etching. Alternatively, an insulating film is formed using an organic material such as an acrylic resin-based, novolak resin-based, polyimide resin-based positive or negative photosensitive material (photoresist composition), and photography and etching are performed on the insulating film. The electrical insulating layer 13b may be formed by performing the above.

The region where the insulating film has been removed by the above patterning is a region corresponding to the pixel region 14, and the film remaining without being removed becomes the electrical insulating layer 13b. The partition wall 13a is provided on the electrical insulating layer 13b. In the case where the electric insulating layer 13b is not provided, the anode 2 is exposed in a stripe shape between the partition walls 13a, and this stripe-shaped region becomes the pixel region 14.

In the case where the electrical insulating layer 13b is formed of an organic material, the electrical insulating layer 13b can be made ink repellent simultaneously with the partition wall 13a by performing a process of selectively making the surface of a member made of an organic material ink repellent. There is an advantage that you can. For example, by performing CF ₄ plasma treatment, the surfaces of the partition walls 13a and the electrical insulating layer 13b made of an organic material are changed to ink repellency. Even when the CF ₄ plasma treatment is performed, the surface of the anode 2 made of an inorganic material maintains lyophilicity with respect to the organic light emitting ink.

When the surface of the electrical insulating layer 13b has ink repellency, the organic light emitting ink is repelled from the electrical insulating layer 13b even when the organic light emitting ink adheres to the electrical insulating layer 13b when the organic light emitting ink is applied to each pixel region. The organic light emitting ink can be prevented from remaining in the electrical insulating layer 13b.

The main role of the partition wall 13a is to insulate adjacent pixels separated by the partition wall 13a and prevent color mixing between adjacent pixels. Therefore, the height dimension is set high. On the other hand, the role of the electrical insulating layer 13b is to provide insulation between a plurality of pixels of the same color arranged along the partition wall 13a, and has no role in preventing color mixing. Therefore, the partition wall 13a may be formed somewhat thicker than the total thickness of the laminated films such as the interlayer and the organic light emitting layer formed on the pixel region 14. From this standard, the height of the partition wall 13a is preferably set to 2 to 3 μm. The height dimension of the electrical insulating layer 13b is preferably set to 0.1 to 0.2 μm in the case of an electrical insulating layer made of an inorganic material, and 1 μm to 2 μm in the case of an electrical insulating layer made of an organic material. Note that the electrical insulating layer 13b can be omitted depending on the electrical conductivity of the organic material.

In the embodiment in which the electrical insulating layer 13b is provided, the electrical insulating layer 13b is formed before the partition wall 13a is formed. In the case of forming the electrical insulating layer 13b using an inorganic material, first, an insulating film having a thickness of 0.1 to 0.2 μm made of an inorganic insulating material such as SiO ₂ or SiN by a known method such as a plasma CVD method or a sputtering method. Form. Next, the plurality of pixel regions are removed from the insulating film by photolithography and etching, and patterning is performed in a lattice shape, thereby forming the electrical insulating layer 13b. In the case where the electrical insulating layer 13b is formed using an organic material, for example, the above-described photosensitive material (photoresist composition) is used to form the electrical insulating layer 13b patterned in a lattice shape by photolithography. For the purpose of improving the display quality of the organic EL element, a light shielding material may be contained in the photosensitive material.

The manufacturing method of the partition wall 13a having the above structure is not particularly limited, but for example, it can be manufactured as follows.

First, a photoresist layer having a thickness of 2 to 3 μm is formed on the grid-like electrical insulating layer 13b, and this photoresist layer is exposed through a stripe-shaped mask, so that a plurality of anodes 2 arranged in the stripe shape are formed. Development is performed so that the resist layer remains only in between, and heat curing is performed. The resist layer patterned in the stripe form constitutes the partition wall 13a.

The photosensitive material (photoresist composition) can be applied by a coating method using a spin coater, bar coater, roll coater, die coater, gravure coater, slit coater or the like.

The insulating photosensitive material forming the partition wall 13a may be either a positive resist or a negative resist. It is important that the partition wall 13a is insulative. If the partition wall 13a is not insulative, current may flow between the anodes 2 defined by the partition wall, which may cause display defects. .

As the insulating photosensitive material for constituting the partition wall 13a, specifically, polyimide-based, acrylic resin-based, and novolak resin-based photosensitive compounds (photosensitive materials) can be used. This photosensitive material may contain a light-shielding material for the purpose of improving the display quality of the organic EL element.

The partition wall 13a is subjected to an ink repellency treatment as necessary.
In order to impart ink repellency to the surface of the partition wall 13a, an ink repellant substance may be added to the photosensitive material for forming the partition wall. Alternatively, after the partition wall 13a is formed, the surface of the partition wall may be coated with an ink repellent material to impart ink repellency to the partition wall surface. This ink repellency is preferably repellant both for the ink for an interlayer described later and for the ink for an organic light emitting layer.

As a material used when an ink repellent material is added to the photosensitive material, a silicone compound or a fluorine-containing compound is used. These ink repellent compounds exhibit ink repellency in both organic light-emitting ink (coating liquid) used for forming an organic light-emitting layer, which will be described later, and organic material ink (coating liquid) for an interlayer such as a hole transport layer. Therefore, it is preferable.

As a method of forming an ink repellent film on the surface of the partition wall after forming the partition wall 13a, for example, a method of applying a coating liquid containing an ink repellent component to the partition wall surface, vaporizing the ink repellent component, and Examples thereof include a deposition method and a method of modifying the surface by substituting a functional group of the organic material on the partition wall surface with fluorine. Specifically, as the deposition method by the latter vapor phase method, there is a method of imparting ink repellency to the partition wall surface by converting CF ₄ gas into plasma using a vacuum plasma apparatus and causing a fluorine component to act on the partition wall surface. Can be mentioned.

In the case where the electrical insulating layer 13b is made of an organic material, as described above, the CF ₄ gas is converted into plasma using a vacuum plasma apparatus and the fluorine component is allowed to act on the partition surface. Ink repellency can be simultaneously imparted to 13a and the electrical insulating layer 13b.

In the step of preparing a substrate provided with a plurality of partition walls arranged substantially parallel to each other and the anode, the partition wall and the anode are formed as described above. May be obtained from the market.

(Anode-side interlayer formation process)
After the barrier ribs are formed, an organic material layer (anode-side interlayer) such as the above-described hole transport layer is formed as necessary.

The film formation method for the anode-side interlayer is not particularly limited, but for low molecular weight materials, a method by film formation from a mixed solution with a polymer binder is exemplified. In the case of a polymer material, a method by film formation from a solution is exemplified.

The solvent used for film formation from a solution is not particularly limited as long as it dissolves the above-mentioned anode side interlayer material. Examples of such solvents include chlorine solvents such as chloroform, methylene chloride and dichloroethane; ether solvents such as tetrahydrofuran; aromatic hydrocarbon solvents such as toluene and xylene; ketone solvents such as acetone and methyl ethyl ketone; ethyl acetate and acetic acid. Examples include ester solvents such as butyl and ethyl cellosolve acetate.

As the film formation method from the above solution, it is preferable to use a relief printing method. Of these, the flexographic printing method is preferred. As the relief printing plate used in this case, as shown in FIG. 3, it is preferable to use a relief printing plate having a plurality of projections arranged in parallel with each other so as to correspond to the recesses between the partition walls. . Specifically, the relief printing plate has a width corresponding to the width between the plurality of partition walls 13a, and is arranged in stripes at intervals corresponding to the intervals at which the plurality of partition walls 13a are disposed. It is preferable to use a relief printing plate 20 having a plurality of convex portions 21. That is, the plurality of convex portions 21 arranged in a stripe shape are arranged corresponding to the concave portions 15 (FIG. 2) arranged in a stripe shape defined by the partition walls 13a and the substrate 1 (anode). The relief printing plate 20 is preferably cylindrical or columnar, and the plurality of convex portions 21 are preferably arranged along the circumferential direction.

As the polymer binder to be mixed, those not extremely disturbing charge transport are preferable, and those that do not strongly absorb visible light are suitably used. Examples of such a polymer binder include polycarbonate, polyacrylate, polymethyl acrylate, polymethyl methacrylate, polystyrene, polyvinyl chloride, polysiloxane, and the like.

(Organic light emitting layer formation process)
After the above-described surface treatment process is completed, an organic light emitting layer forming process is performed. The organic light emitting layer forming step is characterized by the same relief printing as in the case of the anode side interlayer forming step, in which relief printing is provided with a plurality of convex portions disposed substantially parallel to each other corresponding to the concave portions between the partition walls. The object is to apply an organic light-emitting ink containing an organic light-emitting material by a relief printing method using a plate. As the relief printing plate used in that case, as shown in FIG. 3, each of the plurality of partition walls 13a has a width corresponding to the width between the plurality of partition walls 13a (the width of the recess 15). The use of the relief printing plate 20 having a plurality of convex portions 21 arranged in stripes at intervals corresponding to the intervals, respectively. Furthermore, the relief printing plate 20 is preferably cylindrical or columnar, and the plurality of convex portions 21 are preferably arranged so that the longitudinal direction of the convex portions coincides with the circumferential direction.

In the case of manufacturing a multi-color organic EL element, each concave groove defined by the partition wall 13a is coated with the same color organic light-emitting ink attached to the convex portion 21 corresponding to the groove. The Therefore, even when performing multicolor printing, according to the above configuration, if the alignment of the convex portion 21 of the relief printing plate 20 with respect to the concave portion between the partition walls 13a is made accurate, the alignment accuracy in the printing direction is moderate, The application of the organic light-emitting ink of each color is performed accurately.

The organic light emitting ink is prepared by dissolving or stably dispersing an organic light emitting material in a solvent. Examples of the solvent for dissolving or dispersing the organic light emitting material include toluene, xylene, acetone, anisole, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, or a mixed solvent thereof. Among these, aromatic organic solvents such as toluene, xylene, and anisole are preferable because they have good solubility of the organic light emitting material.

In addition, you may add surfactant, antioxidant, a viscosity modifier, a ultraviolet absorber, etc. to organic luminescent ink as needed.

(Cathode-side interlayer formation process)
After the formation of the organic light emitting layer, a cathode-side interlayer such as an electron transport layer or an electron injection layer is formed as necessary.
The method for forming the cathode side interlayer is not particularly limited in the case of the electron transport layer. As the low molecular electron transport material, for example, a vacuum deposition method from powder or a film formation method from a solution or a molten state can be mentioned. Moreover, in the polymer electron transport material, for example, a method by film formation from a solution or a molten state can be mentioned. In film formation from a solution or a molten state, a polymer binder may be used in combination. As a method for forming an electron transport layer from a solution, a film formation method similar to the method for forming a hole transport layer from a solution described above can be used.
In the case of an electron injection layer, it is formed using a vapor deposition method, a sputtering method, a printing method, or the like.

(Cathode formation process)
The cathode is formed by using any of the materials described above by a vacuum deposition method, a sputtering method, a CVD method, an ion plating method, a laser ablation method, a laminating method for press-bonding a metal thin film, or the like.

After forming the cathode as described above, an upper sealing film is formed in order to protect the light emitting function part having the anode-light emitting layer-cathode as a basic structure. The upper sealing film is composed of at least one inorganic layer and at least one organic layer as necessary. The number of these layers is determined as necessary. Basically, the inorganic layers and the organic layers are alternately stacked.

Hereinafter, examples of the present invention will be shown. However, the examples shown below are preferable examples for explaining the present invention and do not limit the present invention.

Example 1
(Preparation of substrate and formation of first electrode)
First, an ITO thin film was formed on a transparent glass plate of 200 mm (vertical) × 200 mm (horizontal) × 0.7 mm (thickness), and further patterned to form a striped anode. The repetition interval (pitch) of the anode was 80 μm, and the interval (space width) between the anodes was 10 μm with respect to the anode width (line width) of 70 μm (line / space = 70 μm / 10 μm). The thickness of the anode was 150 nm. The pixel region where the pixel is formed when viewed from one side in the thickness direction of the substrate is set in an island shape on the ITO thin film extending in one direction with a predetermined interval in the one direction.

(Formation of electrical insulation layer)
Next, an insulating film made of SiO ₂ is formed by plasma CVD, and then the insulating film in a region corresponding to a plurality of rectangular pixel regions having a width of 50 μm and a length of 150 μm is selectively removed by photography and etching. Then, an electrical insulating layer was formed.

(Formation of partition walls)
Next, on the entire surface of the substrate, a positive photoresist (trade name “OFPR-800”, manufactured by Tokyo Ohka Kogyo Co., Ltd.) is used to form the shape shown in FIGS. 1 and 2 by conventional photolithography. A partition wall 13a was formed. The formed partition wall 13a had a width dimension of 30 μm and a height dimension of 2 μm. Further, the adjacent dimension between the partition walls 13a was set to 75 μm.

Next, the partition wall 13a was subjected to an ink repellency treatment using a vacuum plasma apparatus (trade name “RIE-200L” manufactured by Samco International Co., Ltd.) using CF ₄ gas.

(Letterpress printing plate)
A flexographic printing plate (material: polyester resin) having the structure shown in FIG. 3 was prepared corresponding to the partition. The convex portion 21 of the relief printing plate 20 had a height dimension of 100 μm, a width dimension of 30 μm, and a pitch width of 75 μm, and was formed in stripes in the circumferential direction perpendicular to the axial direction Y of the plate cylinder.

(Formation of anode side interlayer)
Next, a suspension of poly (3,4-ethylenedioxythiophene) / polystyrene sulfonic acid (manufactured by Bayer, trade name “BaytronP AI4083”) is prepared, and this suspension is filtered through a 0.2 μm membrane filter. did. This filtrate was applied to the pixel region using the relief printing plate. Subsequently, the coating layer was heat-treated at 200 ° C. for 20 minutes to form an 80 nm-thick hole injection layer.

(Formation of organic light emitting layer)
As organic light emitting materials, polymer light emitting materials of three colors of red, green, and blue (trade names “RP158 (red)”, “GP1300 (green)”, “BP361 (blue)” manufactured by Summation Co., Ltd.)) are respectively used as solvents ( An organic light emitting ink of 3 colors (concentration: 1% by weight) dissolved in anisole / cyclohexylbenzene = a mixed solvent having a weight ratio of 1/1) was prepared.

Using the flexographic printing plate having the stripe-shaped convex portion having the above structure, red organic light-emitting ink was printed on the corresponding pixel region on the substrate and dried to form a red organic light-emitting layer. Similarly, a green organic light emitting ink and a blue organic light emitting ink were sequentially printed and dried to form a green organic light emitting layer and a blue organic light emitting layer. The thickness of the organic light emitting layer of each color was almost the same dimension of 100 nm.

For printing at this time, “Angstromer SDR-0023 (trade name), plate drum diameter: 80 mm” manufactured by Nissha Printing Co., Ltd. was used as a printing machine. The printing speed was 50 mm / second. Printing was performed in a state in which the plate and the substrate were in contact with each other with a printing push amount of 0 μm, and the plate was pressed from that position by 50 μm (print push amount = 50 μm).

When the shape of the organic light emitting layer formed in each pixel region was observed with an optical microscope (manufactured by Nikon Corporation, trade name “Optiphoto 88”, objective lens magnification: 50 ×), each organic light emitting layer was separated from the pixel region. It was confirmed that the film was formed in the pixel region without deviation.

(Formation of cathode)
Next, on the organic light emitting layer, calcium was vapor-deposited with a thickness of 100 mm as a cathode, and aluminum was vapor-deposited with a thickness of 2000 mm as an oxidation protective layer. Thus, an organic EL element having a bottom emission structure was produced.

When the organic EL device obtained as described above was caused to emit light, no blur was observed in the multicolor emission, and a clear multicolor display was obtained.

(Example 2)
An organic EL device was produced in the same manner as in Example 1 except for the following two points. (1) An electrically insulating layer is formed using a positive photoresist. (2) The plasma treatment using CF ₄ gas was not performed.
In Example 2, a grid-like electrical insulating layer was formed by conventional photolithography using a positive photoresist (trade name “OFPR-800” manufactured by Tokyo Ohka Kogyo Co., Ltd.).
Further, since the plasma treatment using CF ₄ gas is omitted, the ink repellency treatment is not performed on the partition wall 13a as in the first embodiment.

(Comparative example)
Using a printing plate and printing conditions similar to those in the first embodiment, using a substrate provided with partitions formed in a grid and a relief printing plate having projections corresponding to pixel regions defined by the partitions. The organic light emitting ink was printed and dried to form an organic light emitting layer. Other than that was carried out similarly to the said Example 1, and manufactured the organic EL element. The dimension of the formed partition was 2 μm in height, and the dimension of the opening formed in the partition was 50 μm in width and 150 μm in length.

When the manufactured organic EL device was allowed to emit light, there was bleeding (mixed color) in color development, and display unevenness occurred.

As described above, according to the present invention, it is possible to produce an organic EL element by preventing printing misalignment when applying an organic light-emitting ink by a relief printing method without reducing the production efficiency. An organic EL element in which color mixture does not occur in the organic light emitting layer formed on the substrate and a display device having the organic EL element can be efficiently produced.

Claims

A method for producing an organic electroluminescent device comprising a cathode, an anode, and an organic light emitting layer located between the cathode and the anode,
Preparing a substrate provided with a plurality of partition walls arranged substantially parallel to each other and the anode;
Using a relief printing plate having a plurality of convex portions disposed substantially parallel and corresponding to the concave portions between the partition walls, an organic light emitting ink containing an organic light emitting material and a solvent is used in the longitudinal direction of the partition walls. A method for producing an organic electroluminescent element, comprising: an organic light emitting layer forming step of forming the organic light emitting layer by continuously supplying the concave portion along the concave portion.
In the substrate, a plurality of pixel regions in which pixels are formed between the partition walls are set along the partition walls, and between the adjacent pixel regions, an electrical insulating layer whose height from the substrate is lower than the partition walls The organic electroluminescent element manufacturing method according to claim 1, wherein:
2. The convex printing plate according to claim 1, wherein the relief printing plate has a cylindrical shape or a columnar shape, and the plurality of convex portions are arranged so that a longitudinal direction of the plurality of convex portions coincides with a circumferential direction. The manufacturing method of the organic electroluminescent element of description.
An organic electroluminescence device obtained by using the manufacturing method according to claim 1.
A display device comprising the organic electroluminescence element according to claim 4.