JP2001093672A - Substrate for organic electroluminescence display element and the display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for an organic EL display element and the display element with partition walls, having a shape that prevents the shortening of distance between the cathode and the anode, capable of coping with further fining of the element. SOLUTION: In this substrate for an organic electroluminescence display element, at least plural transparent electrodes and plural electrically insulating partition walls, extending in the direction orthogonally crossing the extending direction of the transparent electrodes, are layered in the order on a transparent substrate. The section of the partition wall is in a shape of eaves overhanging the transparent substrate, and the side surface of the partition wall is covered with an organic layer and a cathode layer to a position higher than their respective thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for an organic electroluminescent display element and a display element for displaying information for industrial use and consumer use.

[0002]

2. Description of the Related Art An organic electroluminescence (hereinafter referred to as "organic EL") display device having the features of being thin and lightweight, having a high viewing angle, high-speed response, and self-luminous type is known as a CRT (Cathod Ray Tub).
e) and display elements replacing LCDs (Liquid Crystal Displays). The organic EL is a laminate of an anode layer, an organic layer, and a cathode layer. Holes and electrons injected from the anode and the cathode are recombined in the organic layer to emit fluorescence.

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 fluorescent light to the outside, a material that transmits visible light is used for the anode layer, generally, ITO (Indium Tin Oxide).
Is used.

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. .
Organic substances used here are generally heat-resistant, solvent-resistant,
A sputtering method or a vapor deposition method is used for forming a stacked body because the material often has poor water resistance and acid-alkali resistance, and high purity of a material is required to maintain electrical characteristics of the element.

[0005] In an organic EL display element, ITO as an anode layer is first provided on a substrate, and an organic layer and a cathode layer are sequentially laminated thereon. In order for an 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. For this purpose, a plurality of cathodes perpendicular to the anode must be formed. However, due to the above-mentioned various resistance problems of the organic layer material, a photolithography process using a solvent or an aqueous acid-alkali solution is employed in the method for forming the cathode. Can not do. It is also conceivable to apply a mask evaporation method using a metal mask to form the cathode.

However, when the method is used to increase the size and increase the definition, the pattern of the metal mask has a width of several tens μm.
Since the wire has a small thickness and tension is applied so as not to sag the metal mask, the metal mask gradually expands and deforms, and eventually the cathode formation is poor. Since a metal mask having a fine and high-precision pattern is expensive, an increase in manufacturing cost is unavoidable if the step of replacing the metal mask is performed before elongation deformation occurs.

A conventional technique for solving this problem will be described with reference to FIG. JP-A-5-258859 discloses that before the organic layer 301 and the cathode layer 302 are laminated, a partition wall 303 is formed on a substrate in advance, and the partition wall 303 is formed from a direction 305 substantially orthogonal to the partition wall extending direction and oblique to the substrate. A technique is described in which oblique deposition of an organic layer and a cathode layer is performed to separate both layers during deposition (see FIG. 4A). However, in this technique, when oblique deposition is performed on a substrate having a large area, a large difference appears in the substrate plane in the distance between the deposition source and the substrate, so the deposition source and the substrate must be considerably separated so that this difference can be ignored. A uniform film thickness cannot be obtained. Naturally, this requires a very large deposition apparatus. Furthermore, in this technology,
The separation width 307 is (width of partition) + (height of partition) × tan
(Evaporation angle θ). From this, it can be seen that simply reducing the width of the partition does not reduce the separation width. Furthermore, the partition walls are lowered for higher definition, and the deposition angle θ
When is small, the wraparound of the vapor deposition molecules cannot be ignored and the separation is likely to be incomplete.

Japanese Patent Application Laid-Open No. Hei 8-315981 discloses that before the organic layer 301 and the cathode layer 302 are laminated, a partition wall 304 is formed on the substrate in advance, and the side surface of the partition wall is overhanged. Thus, a technique for separating both layers at the time of 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 deposition molecules. For this reason, as the definition becomes higher, the partition walls become smaller similarly, and patterning becomes more difficult. Further, in both of the above technologies, in the separation of only the partition wall, the thickness of the organic layer is reduced at the cathode end 309, so that there is a high possibility of a short circuit between the anode and the cathode. To avoid this, it is conceivable to provide an insulating layer below the partition, but this increases the number of steps.

The root cause of these problems lies in the separation of the organic layer and the cathode layer on the substrate surface in the prior art. Therefore, the present invention solves the problem by separating a portion responsible for separation during vapor deposition from the substrate surface.

[0010]

SUMMARY OF THE INVENTION The present invention provides a substrate for an organic EL display device and an organic EL display device which can cope with high definition and which has a partition having a shape for preventing a short circuit between a cathode and an anode. Is provided.

[0011]

According to the first aspect of the present invention, at least a plurality of transparent electrodes and a plurality of electrically insulating partitions extending in a direction perpendicular to a direction in which the transparent electrodes extend are provided on the surface of the transparent substrate. An organic electroluminescence display element substrate, wherein the cross-sectional shape of the partition wall is a shape having an eave protruding toward the transparent substrate side in the sequentially laminated organic electroluminescence display element substrate. The invention according to a second aspect is based on the premise of the first aspect, wherein the partition has a substantially T-shaped cross-sectional shape. A third aspect of the present invention is based on the premise of the first aspect, wherein the partition has a substantially arrow-shaped cross-section in a direction away from the transparent substrate. It is. According to a fourth aspect of the present invention, there is provided an organic electroluminescent display device, wherein an organic layer and a cathode layer are formed on the substrate for an organic electroluminescent display device according to the first to third aspects. The invention according to claim 5 is based on the premise that the side wall of the partition 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. This is an organic electroluminescent display element characterized by the following.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the drawings. In FIG. 1A, a transparent substrate 101 is a substrate serving as a support member of the organic EL. Therefore, quartz, glass, or a plastic material having mechanical strength and insulating properties can be used for the transparent substrate.

A plurality of transparent electrodes 102 are provided on the surface of the transparent substrate. As a method for forming a transparent electrode, I
TO (Indium Tin Oxide), IZO (Indium Zinc Oxid
e) A transparent conductive material such as e) is deposited through a mask having a plurality of electrode patterns formed thereon, or the transparent conductive material is entirely deposited on a transparent substrate surface, and then photolithography using a resist is performed. Can be by law.

On the transparent substrate and the transparent electrode, a plurality of electrically insulating partitions extending in a direction perpendicular to the direction in which the transparent electrode extends are provided. This partition is used for patterning an organic layer described later.

The cross-sectional shape of the partition wall in the present invention has an eave at a portion that extends laterally above the upper part of the partition wall, and the eave protrudes toward the transparent substrate. The cross-sectional shape includes, for example, a substantially T-shape (a horizontal bar of T and a downward projection of an end portion are eaves), and a substantially arrow shape (a widened portion at the tip of the arrow is eaves). The following means can be employed for forming the eaves having the above-mentioned shape.

In the means A, the partition is made of two or more materials, and photolithography, vapor deposition, sputtering or the like is performed with each material. Means B is to mix a material that absorbs / blocks exposure light into the negative resist 103, and to change the exposure amount in the thickness direction of the resist,
This is to cure the resist film surface. Means C utilizes a surface insoluble layer found in a chemically amplified resist. The surface insolubilized layer is a layer in which the acid generated by exposure is deactivated by the basic gas in the atmosphere, and is exposed to the basic gas atmosphere in the case of a positive resist. Protecting the surface promotes its formation.

In the present invention, any of the three means can be employed, but means B and C having a small number of steps are preferred. Hereinafter, a method using the means B and the means C will be described with reference to FIGS.

A resist 103 is applied to a transparent substrate 101 on which a plurality of transparent electrodes 102 are patterned in advance.
Here, the resist may be colored or colorless. In the case of the means B,
A material that absorbs / blocks exposure light is mixed into a negative resist. As such a material, a light absorber, an organic pigment / dye, and an inorganic pigment / dye that can be used according to the exposure wavelength can be used. In the case of the means C, either a positive type or a negative type may be used. As a method for applying the resist, spin coating, roll coating, printing, or the like can be used. The applied resist 103 is dried under appropriate conditions. If the resist is a negative resist by means C, a surface protective film 104 is applied on the resist 103. As the surface protective film, a water-soluble substance such as polyvinyl alcohol and polyacrylic acid can be used.

The resist 103 is exposed using a photomask 105 having an appropriate pattern perpendicular to the transparent electrodes. In the case of the means B, the exposure light does not reach the substrate and only the surface of the resist film is cured. In the case of a positive resist by the means C, after exposure, it is left in an atmosphere for a predetermined time or exposed to an atmosphere in which a basic gas 107 is present for an appropriate time, so that the acid 108 generated by the exposure is deactivated and the surface hardly soluble layer is formed. 106
To form In the case of a negative resist by means C, diffusion of the basic gas 107 is suppressed by the surface protective film 104,
In addition, since the diffusion of the acid 108 is increased by moisture in the surface protective film 104, the hardening of the surface is promoted and the surface hardly soluble layer 10
6 are formed. After exposure, depending on the resist material,
Perform PEB (Post-Exposure Bake). PEB may not be required.

Thereafter, the resist 103 is developed. In the case of using a negative resist by the means C, the surface protective film 104 is required before development.
Is removed by washing with water, uniform development can be obtained. As the developer, a developer suitable for the resist material is selected. In the case of the means B, the surface of the resist 103 is hardened. In the case of the means C, the surface hardly-solubilized layer 106 is formed. Therefore, as shown in FIG. 1D, the partition pattern obtained by the development has the eaves 109, and the width thereof is wider than the pattern width of the photomask 105. After the development, the substrate is sufficiently washed with water and dried.

Thereafter, baking is performed at an appropriate temperature according to the resist. At this time, the eaves 109 protrude toward the transparent substrate side by being slightly softened by the heating conditions, and are substantially T-shaped (FIG. 2).
(See FIG. 2 (a)), and cured in a substantially arrow shape (see FIG. 2 (b)) to obtain the substrate for an organic EL display element of the present invention.

When an organic EL display element is produced using this substrate for an organic EL display element, an organic layer and a cathode layer are further provided.

Here, the organic layer includes a light emitting layer, a hole injection layer,
It may be composed of a hole transport layer, an electron injection layer, an electron transport layer, and the like. Some substances have multiple functions, for example, light emission and hole transport. The following substances can be used for forming the organic layer.

As the light emitting layer, for example, a fluorescent brightener such as benzothiazole, benzimidazole or benzoxazole, styrylbenzene compound, 12-phthaloperinone, 1,4-diphenyl-1,3-butadiene, 1,4,4-tetraphenyl-1,3-butadiene, naphthalimide derivative, perylene derivative, oxadiazole derivative, pyrazirine derivative, cyclopentadiene derivative, pyrrolopyrrole derivative, styrylamine derivative, coumarin-based compound, 9,10- Diarylanthracene derivative, salicylate, pyrene, coronene, perylene, rubrene, tetraphenylbutadiene, 9,10-bis (phenylethynyl) anthracene, 8-quinolinolate lithium, tris (8-quinolinolate) aluminum complex (hereinafter abbreviated as Alq) ), N, N ' -Diphenyl-N,
N'-bis (3-methylphenyl) -benzidine (hereinafter TP
D), tris (5,7-dichloro, 8-quinolinolate) aluminum complex, tris (5-chloro-8-quinolinolate) aluminum complex, bis (8-quinolinolate)
Zinc complex, tris (5-fluoro-8-quinolinolate) aluminum complex, tris (4-methyl-5-trifluoromethyl-8-quinolinolate) aluminum complex, tris (4-methyl-5-cyano-8-quinolinolate) aluminum Complex, bis [8- (paratosyl) aminoquinoline] zinc complex and cadmium complex, 1,2,3,4-tetraphenylcyclopentadiene, pentaphenylcyclopentadiene, poly-2,5-diheptyloxy-P-phenylenevinylene Or JP-A-4-31488, US Pat.
Fluorescent substances and N, N'-diaryl-substituted pyrrolopyrrole compounds referred to in JP-A-141671 and JP-A-4769292 can be used.

The substance that can be used in the present invention is not particularly limited to the above examples, and a substance having a further luminous performance can be selected.

As the hole injection layer, for example, a triazole derivative, an oxadiazole derivative, an imidazole derivative, a polyarylalkane derivative, a pyrazoline derivative,
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, porphyrins Compounds, aromatic tertiary amine compounds, styrylamine compounds, and aromatic dimethylidin compounds can be used.

Examples of the electron injecting layer include nitro-substituted fluorenone derivatives, anthraquinodimethane derivatives, diphenylquinone derivatives, thiopyrandioxide derivatives, heterocyclic tetracarboxylic anhydrides such as naphthaleneperylene, carbodiimide, and fluorenylidenemethane derivatives. ,
Anthrone derivatives and oxadiazole derivatives can be used.

For the formation of the cathode layer, MgAg, AlLi, CuLi or the like can be used in addition to aluminum.

Then, the organic layer 201 and the cathode layer 202 are deposited on the substrate from multiple directions 203. Specifically, it is conceivable to rotate the substrate during vapor deposition, tilt the substrate during vapor deposition, prepare a large number of vapor deposition sources without keeping the distance between the substrate and the vapor deposition source so large. 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 evaporated molecules can be completely prevented. If the deposit covers the side wall of the partition to a position higher than the thickness of the organic layer and the cathode layer, a short circuit between the cathode and the anode does not completely occur. Since each pixel is partitioned only by the width of the partition, the light emission 20
The organic EL display element of the present invention, which can take the maximum area for extracting 4 from the above, is obtained.

[0030]

<Example 1> Negative resist OMR-85
(Manufactured by Tokyo Ohka Kogyo) with carbon black at a weight ratio of 10
The mixture was added at 0: 3 and stirred well to obtain a negative resist.

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, a negative resist was applied to a film thickness of about 10 μm by spin coating.
m and dried at 70 ° C. for 30 minutes. Using a photomask having a stripe pattern with a width of 10 μm and a pitch of 105 μm orthogonal to the transparent electrode, the resist was adjusted to 100 mJ /
Exposure was in cm ² . Thereafter, the film was developed with an OMR developer (manufactured by Tokyo Ohka Kogyo), rinsed with an OMR rinse solution (manufactured by Tokyo Ohka Kogyo), and dried. Thereafter, it was baked at 200 ° C. for 1 hour.
Observation of the cross section of the resist with a scanning electron microscope revealed that an arrow-shaped partition wall having a width of 7 μm, a partition wall width of 5 μm in contact with the substrate, and a pitch of 105 μm was formed.

<Example 2> 390 g of an 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 0.5 g of hydroquinone and methyl ethyl were dissolved. The reaction was carried out at 100 to 150 ° C. for 2 hours in the presence of 3 g of ammonium iodide. Next, 279 g of head anhydride was added and reacted at 100 to 150 ° C. for 2 hours to obtain a water-soluble photopolymerizable oligomer.

The obtained water-soluble photopolymerizable oligomer 100
Phenol novolak type epoxy resin (manufactured by Toto Kasei Co., Ltd .: "YD
CN-602 ") 40 parts by weight, trimethylolpropane triacrylate (manufactured by Kyoeisha Yushi Co., Ltd .:" TMP-A ") as a photopolymerizable monomer, 20 parts by weight, and a photopolymerization initiator (manufactured by Ciba Geigy:" Irgacure- ") 65
1 ") 5 parts by weight, 0.5 parts by weight of diphenyliodonium hexafluoroantimonate as a photocuring catalyst precursor and 0.1 part by weight of hydroquinone as a polymerization inhibitor were mixed in 1000 parts by weight of butyl acetate.
A chemically amplified negative resist was obtained.

A chemically amplified negative resist was applied to a thickness of about 10 μm 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 by a spin coating method, and dried at 70 ° C. for 30 minutes. About 1 μm of polyvinyl alcohol was applied thereon, and dried 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 and a pitch of 105 μm orthogonal to the transparent electrode.
After washing with water to remove polyvinyl alcohol, TMAH
(Tetramethylammonium hydroxide) 2.
Developed with a 5% solution. Thereafter, it was baked at 200 ° C. for 1 hour. Observation of the cross section of the resist with a scanning electron microscope revealed that a T-shaped partition wall having a width of 7 μm, a width of the partition wall in contact with the substrate of 5 μm, and a pitch of 105 μm, with the upper end hanging down, was formed.

<Embodiment 3> Width 100 μm, Pitch 105
A chemically amplified positive resist AZ7200 (manufactured by Hoechst) having a thickness of about 10 μm was formed on a glass substrate having an ITO transparent electrode having a stripe pattern of μm by spin coating.
It was applied and dried at 90 ° C. for 30 minutes. The concentration is 10pp
m in an ammonia atmosphere for 10 minutes, and then a resist having a width of 10 μm orthogonal to the transparent electrode and a photomask having a stripe pattern with a pitch of 105 μm is removed.
mJ / cm ^{2 was} exposed. After the exposure, the film was developed with AZ300MIF. Then, it baked at 150 degreeC for 30 minutes. Observation of the cross section of the resist with a scanning electron microscope revealed that a T-shaped partition wall having a width of 6 μm on the upper side, a width of 4 μm of the partition wall in contact with the substrate, and a pitch of 105 μm was formed.

Example 4 Organic EL Obtained in Example 2
The display element substrate is fixed to a jig, and TPD,
ALq and aluminum were sequentially deposited as a cathode layer. Seven evaporation sources were prepared for each, and evaporation was performed from multiple directions to obtain an organic EL display element. After vapor deposition, the organic EL display element was sealed with a metal can. When the obtained organic EL display device was allowed to emit light, the anode and the cathode were not short-circuited and the pitch was 10
Pixels of 5 μm and 100 × 100 μm emitted light to the bottom edge of the partition.

[0037]

By depositing an organic layer and a cathode layer on the substrate for an organic EL display element 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 prevented. Since the separation width is determined only by the width of the partition wall in contact with the substrate, the separation width can be reduced to the limit. Thereby, it is 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 the definition is not so high, the light emitting area can be increased, that is, 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 manufacturing an organic EL substrate according to the present invention.

FIG. 2 is a sectional view of a partition wall according to the present invention.

FIG. 3 is an explanatory view of formation of a surface insolubilized layer.

FIG. 4 is an explanatory diagram of a conventional technique.

FIG. 5 is a sectional view of an organic EL display device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Insulating transparent substrate 102 Transparent electrode (anode layer) 103 Resist 104 Surface protective film 105 Photomask 106 Surface insoluble layer 107 Basic gas 108 Acid 109 Eaves 201, 301 Organic layer 202, 302 Cathode layer 203, 305 Deposition direction 204 Light emission 303, 304 Conventional partition wall 306 Deposition angle of oblique deposition 307, 308 Conventional separation width 309 Cathode end prone to short circuit between anode and cathode

Claims (5)

[Claims] 1. An organic electroluminescent display element substrate comprising a transparent substrate and at least a plurality of transparent electrodes and a plurality of electrically insulating partitions extending in a direction perpendicular to a direction in which the transparent electrodes extend, sequentially laminated on the surface of the transparent substrate. A substrate for an organic electroluminescence display element, wherein the partition has a cross-section having an eave protruding toward the transparent substrate. 2. A substrate for an organic electroluminescent display device according to claim 1, wherein the partition has a substantially T-shaped cross section. 3. The partition according to claim 1, wherein the partition has a substantially arrow-shaped cross section pointing away from the transparent substrate.
The substrate for an organic electroluminescence display element according to the above. 4. An organic electroluminescent display device comprising an organic electroluminescent display device substrate according to claim 1, wherein an organic layer and a cathode layer are formed on the substrate. 5. The organic electroluminescent display device 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 respective film thicknesses of the organic layer and the cathode layer. .