JP4310866B2 - Substrate for organic electroluminescence display element and display element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic electroluminescence display element substrate and a display element for displaying information for industrial use and consumer use.
[0002]
[Prior art]
Organic electroluminescence (hereinafter referred to as organic EL) display elements that are thin and lightweight, have a high viewing angle, high-speed response, and self-luminous type are attracting attention as alternatives to CRT (Cathod Ray Tube) and LCD (Liquid Crystal Display). Yes. The organic EL is a laminate of an anode layer, an organic layer, and a cathode layer, and holes and electrons injected from the anode and the cathode recombine in the organic layer to emit fluorescence.
[0003]
A metal oxide is used for the anode and a metal is used for the cathode so that holes and electrons are injected into the organic layer. At this time, in order to extract the fluorescence to the outside, a material that transmits visible light is used for the anode layer, and generally ITO (Indium Tin Oxide) is used.
[0004]
The organic layer may be provided with a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer so as to sandwich a light emitting layer that emits fluorescence by recombination of holes and electrons. The organic materials used here are generally inferior in heat resistance, solvent resistance, water resistance, and acid / alkali resistance, and high purity of the material is necessary to maintain the electrical characteristics of the device. Adopts sputtering or vapor deposition.
[0005]
In the organic EL display element, first, ITO as an anode layer is provided on a substrate, and an organic layer and a cathode layer are sequentially laminated thereon. In order for the organic EL display element to display various information, it must have a matrix electrode structure in which a plurality of anodes and a plurality of cathodes are arranged orthogonally. Therefore, it is necessary to form a plurality of cathodes orthogonal to the anode. However, due to various problems of the durability of the organic layer materials described above, a photolithography process using a solvent or an acid-alkaline aqueous solution is adopted for the cathode formation method. I can't. Application of mask vapor deposition using a metal mask for the formation of the cathode is also conceivable.
[0006]
However, when this method is used for large size and high definition, the pattern of the metal mask becomes a thin line with a width of about several tens of μm, and tension is given so that the metal mask does not sag. It becomes a formation defect. Since a metal mask having a fine and highly accurate pattern is expensive, an increase in manufacturing cost is unavoidable if the metal mask is replaced before elongating deformation.
[0007]
The prior art for this problem will be described with reference to FIG.
In JP-A-5-258859, before the organic layer 301 and the cathode layer 302 are laminated, a partition wall 303 is formed on the substrate in advance, and the direction from the direction 305 that is substantially orthogonal to the partition extension direction and oblique to the substrate. A technique is described in which oblique deposition of the organic layer and the cathode layer is performed to separate both layers during deposition (see FIG. 4A). However, with this technique, when oblique deposition is performed on a large-area substrate, there is a large difference in the distance between the deposition source and the substrate within the surface of the substrate. Therefore, the deposition source and the substrate must be separated so that this difference can be ignored. A uniform film thickness cannot be obtained. Of course, this requires a very large vapor deposition apparatus. Further, in this technique, the separation width 307 can be expressed as (partition wall width) + (partition wall height) × tan (deposition angle θ). From this, it can be seen that simply reducing the width of the partition wall does not reduce the separation width. Further, if the partition walls are made low for high definition and the vapor deposition angle θ is made small, the wraparound of vapor deposition molecules cannot be ignored and the possibility of incomplete separation is high.
[0008]
Further, in JP-A-8-315981, before laminating the organic layer 301 and the cathode layer 302, a partition wall 304 is formed in advance on the substrate, and the side surface of this partition wall is overhanged. A technique for separating both layers during vapor deposition is described (see FIG. 4B). In this technique, the separation width 308 is the width of the upper part of the partition wall 304, but the overhang shape and angle are determined separately in consideration of the wraparound of vapor deposition molecules. Therefore, the higher the definition, the smaller the partition wall becomes and the more difficult patterning becomes. In both of the above techniques, the separation of only the barrier ribs increases the possibility of a short circuit between the anode and the cathode because the film thickness of the organic layer decreases at the cathode end 309. In order to avoid this, it is conceivable to provide an insulating layer under the partition wall, but this increases the number of processes.
[0009]
The fundamental cause of these problems is that in the prior art, the organic layer and the cathode layer are separated on the substrate surface. Therefore, the present invention has solved the problem by separating the part responsible for separation during vapor deposition from the substrate surface.
[0010]
[Problems to be solved by the invention]
The present invention provides a substrate for an organic EL display element and an organic EL display element that have a partition shape that can cope with the progress of higher definition and prevent a short circuit between the cathode and the anode.
[0011]
[Means for Solving the Problems]
The invention according to claim 1 is for an organic electroluminescence display element in which at least a plurality of transparent electrodes and a plurality of electrically insulating partition walls extending in a direction orthogonal to the extending direction of the transparent electrodes are sequentially laminated on the surface of the transparent substrate. In the substrate, the cross-sectional shape of the partition wall is a shape having eaves protruding to the transparent substrate side.
A second aspect of the invention is an organic electroluminescence display element substrate, characterized in that the cross-sectional shape of the partition wall is substantially T-shaped on the basis of the first aspect of the invention.
The invention according to claim 3 is based on the invention according to claim 1, and is a substrate for an organic electroluminescence display element characterized in that the cross-sectional shape of the partition wall is a substantially arrow type facing away from the transparent substrate. It is.
The invention described in claim 4 is an organic electroluminescence display element characterized in that an organic layer and a cathode layer are formed on the substrate for organic electroluminescence display element described in claims 1-3.
The invention according to claim 5 is based on the invention according to claim 4, and the side surface of the partition wall is covered with the organic layer and the cathode layer to a position higher than the respective film thicknesses of the organic layer and the cathode layer. An organic electroluminescence display element is characterized.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail with reference to the drawings.
In FIG. 1A, a transparent substrate 101 is a substrate that serves as a support member for organic EL. Therefore, quartz, glass, or a plastic material having mechanical strength and insulation can be used for the transparent substrate.
[0013]
A plurality of transparent electrodes 102 are provided on the surface of the transparent substrate. The transparent electrode can be formed by vapor-depositing a transparent conductive material such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide) through a mask on which a plurality of electrode patterns are formed. After the conductive material is vapor-deposited on the surface of the transparent substrate, a photolithography method using a resist can be used.
[0014]
Then, on the transparent substrate and the transparent electrode, a plurality of electrically insulating partition walls extending in a direction orthogonal to the extending direction of the transparent electrode are provided. This partition is used for patterning the organic layer described later.
[0015]
The cross-sectional shape of the partition wall in the present invention has an eaves portion extending laterally above the upper partition wall, and the eaves project toward the transparent substrate. The cross-sectional shape includes, for example, a substantially T-shape (a horizontal bar of T and a downward protrusion of the end portion), and a substantially arrow shape (a broadened portion of the tip of the arrow is elongated). The following means can be used to form the eaves having the shape.
[0016]
In the means A, the partition wall is composed of two or more materials, and photolithography, vapor deposition, sputtering, etc. are performed with each material. Means B is a method in which a negative resist 103 is mixed with a material that absorbs / shields exposure light, and the exposure amount is changed in the film thickness direction of the resist to cure the resist film surface. Means C uses a surface sparingly soluble layer found in chemically amplified resists. The poorly surface-solubilized layer is generated when the acid generated by exposure is deactivated by the basic gas in the atmosphere, and in a positive resist, it is exposed to a basic gas atmosphere. Protecting the surface promotes its formation.
[0017]
In the present invention, any of the three types of means can be adopted, but means B and C having a small number of steps are preferable. Hereinafter, the method using the means B and the means C will be described with reference to FIGS.
[0018]
A resist 103 is applied to a transparent substrate 101 on which a plurality of transparent electrodes 102 are previously patterned. Here, the resist may be colored or colorless. In the case of means B, a material that absorbs / shields exposure light is mixed into the negative resist. As such a material, a light absorber, an organic pigment / dye, or an inorganic pigment / dye matched to the exposure wavelength can be used. In the case of means C, any of positive and negative types may be used. As a resist coating method, spin coating, roll coating, printing, or the like can be used. The applied resist 103 is dried under appropriate conditions. If the means C is a negative resist, a surface protective film 104 is applied on the resist 103. As the surface protective film, a water-soluble substance such as polyvinyl alcohol or polyacrylic acid can be used.
[0019]
The resist 103 is exposed using a photomask 105 having an appropriate pattern orthogonal to the transparent electrode. In the case of means B, the exposure light does not reach the substrate, and only the resist film surface is cured. In the case of a positive resist by means C, the acid 108 generated by exposure is deactivated by leaving it in the atmosphere for a predetermined time after exposure or by exposing it to an atmosphere in which the basic gas 107 exists for a suitable time. 106 is formed. In the case of a negative resist in means C, the diffusion of the basic gas 107 is suppressed by the surface protective film 104, and the diffusion of the acid 108 is increased by the moisture in the surface protective film 104. A surface hardly soluble layer 106 is formed. After exposure, PEB (Post-Exposure Bake) is performed depending on the resist material. In some cases, PEB is unnecessary.
[0020]
Thereafter, the resist 103 is developed. In the case of a negative resist by means C, uniform development can be obtained by removing the surface protective film 104 with water before development. A developing solution that is suitable for the resist material is selected. In the case of means B, the surface of the resist 103 is cured. In the case of means C, a surface hardly soluble layer 106 is formed. Therefore, as shown in FIG. 1D, the partition wall pattern obtained by development has the eaves 109, and the width thereof is wider than the pattern width of the photomask 105. After development, wash thoroughly with water and dry.
[0021]
Thereafter, baking is performed at an appropriate temperature according to the resist. At this time, the eaves 109 protrudes to the transparent substrate side by being slightly softened under heating conditions, and has a shape such as a substantially T shape (see FIG. 2A) and a substantially arrow shape (see FIG. 2B). Curing is performed to obtain the organic EL display element substrate of the present invention.
[0022]
When an organic EL display element is produced using this organic EL display element substrate, an organic layer and a cathode layer are further provided.
[0023]
Here, the organic layer may be composed of a light emitting layer, a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, and the like. Some materials have multiple functions, such as light emission, hole transport, and so on. The following materials can be used for forming the organic layer.
[0024]
Examples of the light emitting layer include fluorescent brighteners such as benzothiazole, benzimidazole, and benzoxazole, styrylbenzene compounds, 12-phthaloperinone, 1,4-diphenyl-1,3-butadiene, 1,1,4. , 4-tetraphenyl-1,3-butadiene, naphthalimide derivatives, perylene derivatives, oxadiazole derivatives, pyrazirine derivatives, cyclopentadiene derivatives, pyrrolopyrrole derivatives, styrylamine derivatives, coumarin compounds, 9,10-diarylanthracene derivatives , Salicylate, pyrene, coronene, perylene, rubrene, tetraphenylbutadiene, 9,10-bis (phenylethynyl) anthracene, 8-quinolinolatolithium, tris (8-quinolinolato) aluminum complex (hereinafter abbreviated as Alq), N , N'-Difeni -N, N'-bis (3-methylphenyl) -benzidine (hereinafter abbreviated as TPD), tris (5,7-dichloro, 8-quinolinolato) aluminum complex, tris (5-chloro-8-quinolinolato) aluminum complex, Bis (8-quinolinolato) zinc complex, Tris (5-fluoro-8-quinolinolato) aluminum complex, Tris (4-methyl-5-trifluoromethyl-8-quinolinolato) aluminum complex, Tris (4-methyl-5-cyano -8-quinolinolato) aluminum complex, bis [8- (paratosyl) aminoquinoline] zinc complex and cadmium complex, 1,2,3,4-tetraphenylcyclopentadiene, pentaphenylcyclopentadiene, poly-2,5-diheptyl Oxy-P-phenylene vinylene, or Japanese Patent Application Laid-Open No. 4-31488, US Pat. Nos. 5,141,671 and 4,769,292 Has been that the fluorescent substance and N, N'-diaryl-substituted pyrrolopyrrole compounds and the like can be used.
[0025]
In addition, the substance which can be used for this invention is not specifically limited to the said example, The substance which has further luminous performance can be selected.
[0026]
Examples of the hole injection layer include triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, Fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, polysilanes, aniline copolymers, conductive polymer oligomers, porphyrin compounds, aromatic tertiary amine compounds, styrylamine compounds, and aromatic dimethylidin compounds can be used.
[0027]
Examples of electron injection layers include nitro-substituted fluorenone derivatives, anthraquinodimethane derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, heterocyclic tetracarboxylic anhydrides such as naphthaleneperylene, carbodiimides, fluorenylidenemethane derivatives, anthrone derivatives Oxadiazole derivatives can be used.
[0028]
For forming the cathode layer, MgAg, AlLi, CuLi or the like can be used in addition to aluminum.
[0029]
Then, the organic layer 201 and the cathode layer 202 are deposited from multiple directions 203 on the substrate. Specifically, it is conceivable to prepare a large number of vapor deposition sources that rotate the substrate during vapor deposition, tilt the substrate during vapor deposition, and do not separate the distance between the substrate and the vapor deposition source. By vapor deposition from multiple directions 203, the organic layer 201 and the cathode layer 202 are laminated as shown in FIG. Since the eaves protrude from the transparent substrate, patterning is possible, and unnecessary wraparound of vapor deposition molecules can be completely prevented. If the deposited material covers the side surfaces of the partition walls to a position higher than the film thickness of the organic layer and the cathode layer, the short circuit between the cathode and anode does not occur completely. Then, since each pixel is partitioned only by the width of the partition wall, the organic EL display element of the present invention that can take the maximum area for taking out the light emission 204 is obtained.
[0030]
【Example】
<Example 1>
Carbon black was added to the negative resist OMR-85 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) at a weight ratio of 100: 3 and stirred well to obtain a negative resist.
[0031]
A negative resist was applied by spin coating on a glass substrate having an ITO transparent electrode having a stripe pattern with a width of 100 μm and a pitch of 105 μm, and dried at 70 ° C. for 30 minutes. The resist was exposed at 100 mJ / cm ² using a photomask having a stripe pattern with a width of 10 μm orthogonal to the transparent electrode and a pitch of 105 μm. Thereafter, the film was developed with an OMR developer (manufactured by Tokyo Ohka Kogyo), rinsed with an OMR rinse (manufactured by Tokyo Ohka Kogyo), and dried. Then, it baked at 200 degreeC for 1 hour. When the resist cross section was observed with a scanning electron microscope, an arrow-shaped partition wall having an eave width of 7 μm, a partition wall width of 5 μm, and a pitch of 105 μm could be formed.
[0032]
<Example 2>
390 g of epoxy resin (manufactured by Toto Kasei Co., Ltd .: “YDPN-601”) and 108 g of acrylic acid were dissolved in 750 g of 1,6-hexanediol acrylate, and in the presence of 0.5 g of hydroquinone and 3 g of methylethylammonium iodide. It was made to react at 100-150 degreeC for 2 hours. Subsequently, 279 g of anhydrous head acid was added and reacted at 100 to 150 ° C. for 2 hours to obtain a water-soluble photopolymerizable oligomer.
[0033]
100 parts by weight of the obtained water-soluble photopolymerizable oligomer, 40 parts by weight of a phenol novolac epoxy resin (manufactured by Toto Kasei Co., Ltd .: “YDCN-602”) as a water-insoluble photopolymerizable oligomer, and trimethyl as a photopolymerizable monomer 20 parts by weight of methylolpropane triacrylate (manufactured by Kyoeisha Yushi Co., Ltd .: “TMP-A”), 5 parts by weight as a photopolymerization initiator (manufactured by Ciba Geigy: “Irgacure-651”), diphenyl as a photocuring catalyst precursor A chemically amplified negative resist was obtained by mixing 0.5 parts by weight of iodonium hexafluoroantimonate and 0.1 parts by weight of hydroquinone as a polymerization inhibitor in 1000 parts by weight of butyl cellosolve.
[0034]
A chemically amplified negative resist was applied to a thickness of about 10 μm by spin coating on a glass substrate having an ITO transparent electrode having a stripe pattern with a width of 100 μm and a pitch of 105 μm, and dried at 70 ° C. for 30 minutes. On top of that, about 1 μm of polyvinyl alcohol was applied and left to dry at room temperature. The resist was exposed at 100 mJ / cm ² using a photomask having a stripe pattern with a width of 10 μm orthogonal to the transparent electrode and a pitch of 105 μm. After washing with water to remove polyvinyl alcohol, development was performed with a 2.5% solution of TMAH (tetramethylammonium hydroxide). Then, it baked at 200 degreeC for 1 hour. When the resist cross section was observed with a scanning electron microscope, a T-shaped partition wall having a width of 7 μm on the upper side where the end of the upper side drooped, a width of 5 μm for the partition wall contacting the substrate, and a pitch of 105 μm could be formed.
[0035]
<Example 3>
A chemically amplified positive resist AZ7200 (manufactured by Hoechst) was applied to a glass substrate having an ITO transparent electrode having a stripe pattern with a width of 100 μm and a pitch of 105 μm by spin coating, and dried at 90 ° C. for 30 minutes. This was left in an ammonia atmosphere having a concentration of 10 ppm for 10 minutes, and then the resist was exposed to 100 mJ / cm ² using a photomask having a stripe pattern with a width of 10 μm perpendicular to the transparent electrode and a pitch of 105 μm. After exposure, the film was developed with AZ300MIF. Then, it baked at 150 degreeC for 30 minutes. When the resist cross section was observed with a scanning electron microscope, a T-shaped partition wall having an upper side width of 6 μm, a partition wall width of 4 μm in contact with the substrate, and a pitch of 105 μm was formed.
[0036]
<Example 4>
The organic EL display element substrate obtained in Example 2 was fixed to a jig, and TPD and ALq as an organic layer and aluminum as a cathode layer were sequentially deposited. Seven evaporation sources were prepared for each, and the organic EL display element was obtained by vapor deposition from multiple directions. After vapor deposition, the organic EL display element was sealed with a metal can. When the obtained organic EL display element was made to emit light, the anode and cathode were not short-circuited, and a pixel of 100 × 100 μm with a pitch of 105 μm emitted light to the bottom edge of the partition wall.
[0037]
【The invention's effect】
If the organic layer and the cathode layer are deposited on the organic EL display element substrate according to the present invention, the organic layer and the cathode layer can be reliably separated, and a short circuit between the anode and the cathode can be surely prevented. Furthermore, since the separation width is determined only by the width where the partition wall is in contact with the substrate, the separation width can be reduced to the limit. Thereby, it becomes possible to cope with further higher definition of the organic EL display element. In addition, by narrowing the non-display portion in the display element even if it is not so high definition, it becomes possible to increase the light emitting area, so that the so-called aperture ratio can be increased. An element can be obtained.
[0038]
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a method for producing an organic EL substrate according to the present invention.
FIG. 2 is a cross-sectional view of a partition wall according to the present invention.
FIG. 3 is an explanatory diagram of formation of a surface hardly soluble layer.
FIG. 4 is an explanatory diagram of the prior art.
FIG. 5 is a cross-sectional view of an organic EL display device according to the present invention.
[Explanation of symbols]
101 Insulating transparent substrate 102 Transparent electrode (anode layer)
103 resist 104 surface protective film 105 photomask 106 surface hardly soluble layer 107 basic gas 108 acid 109 eaves 201, 301 organic layer 202, 302 cathode layer 203, 305 vapor deposition direction 204 light emission 303, 304 partition wall 306 according to prior art oblique deposition Deposition angle of 307, 308 Separation width 309 according to the prior art Cathode end which tends to cause short circuit between anode and cathode

Claims (5)

In the substrate for an organic electroluminescence display element in which at least a plurality of transparent electrodes and a plurality of electrically insulating partition walls extending in a direction orthogonal to the extending direction of the transparent electrodes are sequentially laminated on the surface of the transparent substrate, the cross-sectional shape of the partition walls is A substrate for an organic electroluminescence display element, wherein the substrate has an eaves protruding toward the transparent substrate. 2. The organic electroluminescence display element substrate according to claim 1, wherein the partition wall has a substantially T-shaped cross section. 2. The organic electroluminescence display element substrate according to claim 1, wherein a cross-sectional shape of the partition wall is substantially an arrow shape facing a direction away from the transparent substrate. An organic electroluminescence display element, wherein an organic layer and a cathode layer are formed on the organic electroluminescence display element substrate according to any one of claims 1 to 3. 5. The organic electroluminescence display element according to claim 4, wherein the side surfaces of the partition walls are covered with the organic layer and the cathode layer up to positions higher than the film thicknesses of the organic layer and the cathode layer.

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