JP3807318B2 - Organic EL display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic EL display device that uses an organic electroluminescence material (hereinafter simply referred to as an organic EL material) and has light-emitting elements each having a light-emitting layer made of a thin film of an organic EL material arranged in a matrix.
[0002]
[Prior art]
In this type of organic EL display device, an organic EL layer is formed between a first electrode (anode) and a second electrode (cathode). In order to obtain a configuration in which the organic EL layer is arranged in a matrix, it is necessary to form the second electrode in parallel stripes intersecting (generally orthogonal) with the first electrode after the organic EL layer is formed. However, since the organic EL material is vulnerable to moisture, the second electrode cannot be formed by a photolithographic method, which is a wet process, and is generally formed by a vapor deposition method. At this time, in order to ensure the insulation between the second electrode and the first electrode and the insulation between the adjacent second electrodes, an electrode separation partition extending in parallel with the second electrode is provided.
[0003]
For example, Japanese Patent Laid-Open No. 10-106747 discloses an organic EL display device configured as shown in FIG. In this display device, a color filter 13 and a black matrix 14 are formed on the upper surface of a substrate 12 made of transparent glass. An overcoat layer 41 is formed on the upper surfaces of the color filter 13 and the black matrix 14. An anode 42 is formed in parallel on the upper surface. An insulating layer 43 is formed in a direction (perpendicular to the paper surface of FIG. 7) perpendicular to the anode 42 with respect to the upper surface of the anode 42. A reverse-tapered partition wall 44 is formed on the insulating layer 43. Then, an organic EL layer 45 is formed on the upper surface of the anode 42, and then a cathode 46 is formed on the upper surface of the organic EL layer 45. The cathode 46 is separated by the insulating layer 43 and the partition wall 44, so that the insulation between the cathode 46 and the anode 42 is maintained.
[0004]
[Problems to be solved by the invention]
However, in the conventional organic EL display device, the width dimension W1 of the insulating layer 43 from the base end portion of the partition wall 44 is the same as the width dimension W2 from the base end portion of the partition wall 44 itself. As a result, the following problems may occur. In other words, a gap may be formed between the edge of the insulating layer 43 and the edge of the organic EL layer 45 in the formation process of the organic EL layer 45 by vapor deposition. Then, in the step of forming the cathode 46 by vapor deposition, since the edge of the cathode 46 enters the gap, the anode 42 and the cathode 46 are short-circuited. FIG. 7 shows a state in which a short circuit has occurred. When a short circuit occurs, light is not emitted from the organic EL layer 45 when a voltage is applied to the anode 42 and the cathode 46, resulting in a defect in the image.
[0005]
The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide an organic EL display device capable of preventing a short circuit between a first electrode and a second electrode formed with an organic EL layer interposed therebetween. There is to do.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the invention includes a transparent substrate, a first electrode formed on one surface of the front Stories substrate in stripes, one surface of the first electrode according to claim 1 In contrast, an electrode separation partition made of an insulating material formed in a stripe shape so as to cross the first electrode, a thin-film light emitting layer made of an organic electroluminescent material formed between the electrode separation partitions, and the light emission A second electrode formed in parallel stripes so as to cover the layer, and each intersection of the first electrode and the second electrode, and the light emitting layer existing between each intersection In the organic EL display device in which the formed light emitting elements are formed in a matrix, the electrode separation partition includes a first partition made of an inorganic material having a skirt formed on the first electrode side, and a top of the first partition. The buttocks formed on the surface It is composed of a second partition wall made of an organic material, projecting dimension of the skirt portion of the first partition wall, a gist that is larger than the projecting dimension of the eaves portion of the second partition wall.
[0007]
According to the first aspect of the present invention, vapor deposition is performed such that the left and right edges of the light emitting layer overlap the upper surface of the skirt, and the second electrode is vapor deposited on the upper surface of the light emitting layer. Therefore, it is possible to reliably prevent the first electrode and the second electrode from being short-circuited. Even if the formation width of the light emitting layer is reduced and the edge of the second electrode hangs down on the upper surface of the skirt, the first electrode and the second electrode are isolated by the insulating skirt. Will not short circuit.
[0010]
Moreover , the electrode separation partition wall having a desired shape can be formed by using different materials for the first partition wall and the second partition wall .
[0013]
In addition , since the first partition is made of an inorganic material and the second partition is made of an organic material, the degree of freedom in forming the both partitions can be improved. Further, in the step of forming the light emitting layer and the second electrode, the bottom of the first partition is not etched by, for example, oxygen plasma, so that the anode and the cathode are prevented from being short-circuited and the frequency of occurrence of defective products is reduced. be able to.
[0014]
According to a third aspect of the invention, in the organic EL display device according to claim 1 or 2, wherein the first septum wall, silicon oxide, and summarized in that is formed by silicon nitride or magnesium oxide.
[0015]
According to a third aspect of the invention, it is possible to easily form the first septal wall by material easily available in ready-made manner.
According to a fourth aspect of the present invention, in the organic EL display device according to any one of the first to third aspects of the present invention, the height dimension from the first electrode of the collar portion of the electrode separation partition is that of the light emitting layer. The gist is that the film thickness dimension is set to be larger than the total film thickness dimension of the second electrode.
[0016]
According to the fourth aspect of the present invention, an insulation distance between the second electrode and the conductive metal layer remaining on the electrode separation partition is ensured, and a short circuit between the second electrodes through the metal layer is ensured. Can be prevented.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, a color filter 13 made of a pigment, a phosphor, or a synthetic resin in which these are dispersed on one surface (the upper surface in FIG. 2) of the transparent glass substrate 12 of the organic EL color display device 11, A black matrix 14 made of metallic chromium is formed. A transparent resin overcoat layer 15 is formed on the upper surfaces of the color filter 13 and the black matrix 14 so as to flatten the irregularities on the surfaces of the color filter 13 and the black matrix 14. A plurality of first electrodes (anodes) 16 are formed in parallel stripes on the upper surface of the overcoat layer 15. The first electrode 16 is made of ITO (indium tin oxide) or the like. A plurality of electrode separation partitions 17 made of an insulating material are formed on the upper surface of the overcoat layer 15 in parallel stripes orthogonal to the first electrodes 16. The electrode separation partition 17 includes a first partition 18 having a skirt portion 18a made of an inorganic material formed so as to be positioned on the first electrode 16 side, and the same inorganic material formed on the top surface of the first partition 18. It is comprised by the 2nd partition 19 which has the collar part 19a which consists of.
[0018]
An organic EL layer 20 as a light emitting layer made of an organic electroluminescence material (EL material) is formed at a predetermined position on each first electrode 16 so as to be positioned between each electrode separation partition wall 17. The EL layer 20 is formed in parallel stripes. On the upper surface of each organic EL layer 20, a second electrode (cathode) 21 is formed in substantially the same shape as the organic EL layer 20, and each second electrode 21 is also formed in parallel stripes.
[0019]
The organic EL layer 20 is composed of five layers in order from the first electrode 16 side: a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer. The organic EL layer 20 is not limited to five layers, and for example, may have a configuration without at least one of a hole injection layer and an electron injection layer. Moreover, the structure of a positive hole transport layer, a light emitting layer, and an electron carrying layer may be sufficient.
The organic EL layer 20 and the first electrode 16 and the second electrode 21 formed on both the front and back sides of the organic EL layer 20 constitute a light-emitting element 22 as one planar square pixel.
[0020]
The first electrode 16 and the second electrode 21 are each formed in a plurality of parallel stripes, and are arranged so as to cross each other (in this embodiment, orthogonal). For this reason, the light emitting elements 22 are arranged in a matrix on the color filter 13 at the intersections of the electrodes 16 and 21.
[0021]
The film thickness dimension of the organic EL layer 20 is usually about 0.1 to 0.2 microns, the film thickness dimension of the second electrode 21 is thinner than the organic EL layer 20, and the total of the organic EL layer 20 and the second electrode 21. The film thickness dimension t1 is at most 1 micron or less. On the other hand, the film thickness dimension of the first partition wall 18, that is, the height dimension t2 from the first electrode 16 to the second partition wall 19 is about 1 to 20 microns. In this embodiment, the height dimension t2 is set larger than the total film thickness dimension t1.
[0022]
Since the organic EL layer 20 and the second electrode 21 are generally formed by a vacuum deposition method, the same metal layer as the organic EL layer 20 and the second electrode 21 is also formed on the second partition wall 19 where they are unnecessary.
[0023]
As shown in FIG. 2, the skirt portion 18 a of the first partition wall 18 is formed in an arc shape that protrudes outward in the width direction as it approaches the first electrode 16. The projecting dimension w1 in the width direction of the skirt 18a toward the organic EL layer 20 is set to be larger than the projecting dimension w2 in the same direction of the flange part 19a of the second partition wall 19. The actual overhang dimension difference w1-w2 is set to, for example, 0.1 to 10 microns, preferably 0.1 to 2 microns. The cross section of the second partition wall 19 is formed in a flat trapezoidal shape (taper) having a width that increases toward the first electrode 16 side. The first partition wall 18 and the second partition wall 19 are formed of a negative photoresist as will be described later.
[0024]
Next, a method for manufacturing the organic EL color display device 11 configured as described above will be described.
First, as shown in FIG. 3A, a color filter 13 and a black matrix 14 are formed on the upper surface of a substrate 12 made of transparent glass. Thereafter, as shown in FIG. 3B, an overcoat layer 15 is formed on the entire upper surface of the color filter 13 and the black matrix 14. The overcoat layer 15 is formed, for example, by applying and curing a transparent negative photoresist solution that is not colored.
[0025]
Next, in the patterning step, a plurality of first electrodes 16 are formed on the overcoat layer 15 at locations corresponding to positions where the light emitting elements 22 are to be formed, as shown in FIG. Formed in stripes by vapor deposition.
[0026]
Next, the electrode separation partition 17 is formed in a stripe shape orthogonal to the first electrode 16 so as to leave a region for forming the light emitting element 22 at a predetermined position on the first electrode 16 by the partition formation step. This process is performed as follows. As shown in FIG. 3C, a silicon nitride film 31 to be the first partition 18 is formed on the entire upper surface of the overcoat layer 15 and the first electrode 16 by a plasma CVD method, a vacuum deposition method, or the like. Thereafter, a silicon oxide film 32 to be the second partition wall 19 is formed on the upper surface of the silicon nitride film 31 by a sputtering method, a vacuum evaporation method, or the like. Further, a resist mask 33 is formed by photolithography.
[0027]
In the next step, as shown in FIG. 4D, the unmasked portion of the silicon oxide film 32 is removed by dry etching using the resist mask 33 as a mask. At this time, by adjusting the etching direction, the flange of the second partition wall 19 is formed in a desired shape.
[0028]
In the next step, as shown in FIG. 4E, the silicon nitride film 31 is removed in an arc shape by dry etching or wet etching to form the first partition wall 18.
In the above process, an etching method and a material thereof are set so that the second partition wall 19 other than the first partition wall 18, the first electrode 16, and the overcoat layer 15 are not scraped.
As shown in FIG. 5F, the electrode separation partition wall 17 is formed by removing the remaining resist mask 33.
[0029]
Next, after the electrode separation partition 17 is well dried, as shown in FIG. 5G, the organic EL layer 20 is formed by the light emitting layer forming step (organic EL layer forming step). The organic EL layer 20 is formed by sequentially forming each layer constituting the organic EL layer 20 by vapor deposition. Since vapor deposition is performed without masking when forming the organic EL layer 20, the organic EL layer is also formed on the electrode separation partition 17 where it is not necessary to form the organic EL layer 20.
[0030]
Next, in the second electrode forming step, as shown in FIG. 5G, the parallel stripe-shaped second electrode 21 that covers the organic EL layer 20 and is orthogonal to the first electrode 16 is formed. The second electrode 21 is formed by evaporating Al (aluminum). Since the deposition of Al is performed without masking, an Al film is also formed on the electrode separation partition 17 that does not require the second electrode 21 to be in the state shown in FIG. Although the organic EL layer 20 and the second electrode 21 are also formed on the second partition wall 19, a portion functioning as a display unit in the organic EL layer 20 is a planar portion 23 positioned between the adjacent first partition walls 18. In addition, the portion corresponding to the second partition wall 19 does not require a display function.
[0031]
As shown in FIG. 5G, the electrode separation partition wall 17 and the second electrode 21 are sealed by a protective film 34 made of an inorganic material having an insulating property and a moisture-blocking property. The production of the display device 11 is finished. The protective film 34 is formed by a plasma CVD method.
[0032]
According to the organic EL color display device 11 configured as described above, when a voltage is applied between the specific first electrode 16 and the second electrode 21, only the pixel to which the voltage is applied is included in the light emitting element 22. Emits light. This light emission passes through the first electrode 16, the overcoat layer 15 and the color filter 13 as shown by the arrow in FIG.
[0033]
This embodiment has the following effects.
(1) The overhanging dimension w1 of the skirt part 18a of the first partition wall 18 is made larger than the overhanging dimension w2 of the flange part 19a of the second partition wall 19. Therefore, as shown in FIG. 2, vapor deposition is performed so that the left and right edges of the organic EL layer 20 overlap the upper surface of the skirt 18 a, and the second electrode 21 is vapor deposited on the upper surface of the organic EL layer 20. Therefore, it is possible to reliably prevent the first electrode 16 and the second electrode 21 from being short-circuited. Even if the formation width of the organic EL layer 20 is reduced and the edge of the second electrode 21 hangs down on the upper surface of the skirt 18a, the first electrode 16 and the second electrode 21 are separated by the insulating skirt 18a. Therefore, both electrodes 16 and 21 are not short-circuited.
[0034]
(2) The first partition wall 18 is formed of an inorganic material such as insulating silicon oxide, silicon nitride, or magnesium oxide. For this reason, in the formation process of the organic EL layer 20 and the second electrode, the skirt portion 18a is not etched by, for example, oxygen plasma, so that the frequency of occurrence of defective products can be reduced. If the partition wall 18 is made of an organic material, the skirt (insulating layer) may be etched by oxygen plasma and the first electrode 16 and the second electrode 21 may be short-circuited. However, etching is prevented by using an inorganic material. Is done. In addition, the above-mentioned inorganic material is an easily available material, and the first and second partition walls can be easily formed by an existing film forming method.
[0035]
(3) Since the electrode separation partition wall 17 includes the first partition wall 18 and the second partition wall 19, the electrode separation partition wall 17 having a desired shape can be formed by using different materials.
[0036]
(4) Since the first partition wall 18 and the second partition wall 19 are made of an inorganic material, the moisture content is lower than that of the organic material, and the intrusion of moisture into the organic EL layer 20 can be reduced.
[0037]
(5) The height dimension t2 from the first electrode 16 to the flange 19a of the second partition wall 19 is set larger than the total film thickness dimension t1 of the organic EL layer 20 and the second electrode 21. For this reason, an insulation distance between the second electrode 21 and the conductive metal layer remaining on the second partition wall 19 is secured, and a short circuit between the second electrodes 21 via the metal layer is surely prevented. be able to.
[0038]
(6) Since the first partition wall 18 and the second partition wall 19 are made of an inorganic material having a very low moisture impregnation rate, generation of moisture can be reduced as compared with an organic material. For this reason, the penetration | invasion of the water | moisture content to the organic EL layer 20 can be prevented, and the lifetime improvement can be achieved.
[0039]
The embodiment is not limited to the above, and may be configured as follows, for example.
The first partition wall 18 may be formed of an inorganic material, and the second partition wall 19 may be formed of an organic material. In this case, since the first partition is made of an inorganic material and the second partition is made of an organic material, the degree of freedom in forming the both partitions 18 and 19 can be improved.
[0040]
As shown in FIG. 6A, the cross-sectional shape of the second partition wall 19 may be formed in a reverse taper shape with a narrower width toward the first partition wall 18 side. In this alternative example, the first partition 18 may be formed of an inorganic material, and the second partition 19 may be formed of an organic material.
[0041]
As shown in FIG. 6B, the width of the upper end surface of the first partition wall 18 and the entire width of the flange portion 19a of the second partition wall 19 may be the same. In this alternative example, the first partition 18 may be formed of an inorganic material, and the second partition 19 may be formed of an organic material.
[0042]
(Circle) as shown in FIG.6 (c), you may form a 1st partition and a 2nd partition integrally with an inorganic material. In this case, the structure can be simplified, the manufacturing process can be reduced, and the work efficiency can be improved.
[0043]
The electrode separation partition wall 17 may be integrally formed of, for example, an insulating organic material.
〇 Photo resist or electron beam resist may be used as resist.
[0044]
The second electrode 21 is not limited to the configuration orthogonal to the first electrode 16 but may be any configuration that intersects.
The organic EL layer 20 is not necessarily limited to a four-layer structure.
[0045]
O Instead of forming the protective film 34 and sealing the light emitting element 22, it may be sealed with a metal or glass sealing cover or the like.
As a material for the overcoat layer 15, there are silicon oxide, silicon nitride, a laminated structure thereof, and the like in addition to those of the above embodiment.
[0046]
As a material of the first partition wall 18 and the second partition wall 19, there are silicon nitride, silicon oxide, magnesium oxide, or a laminated structure thereof other than those of the above-described embodiment.
In the above embodiment, when the overcoat layer 15 is made of a photoresist solution, the first partition wall 18 may be formed of silicon oxide and the second partition wall 19 may be formed of silicon nitride.
[0047]
O A display device using EL light emitting elements that emit colors of RGB (red, green, blue) without using color filters may be used.
The technical idea (invention) that can be grasped from the embodiment will be described below.
[0048]
(1) before SL that has a protective film for sealing is provided a light-emitting element.
(2) pre-Symbol protective film that is formed by a plasma CVD method.
[0049]
(3) eaves portion before Symbol second septum that is formed in a tapered shape which becomes wider as the first partition wall side.
[0050]
(4) eaves portion before Symbol second septum that is formed in a reverse tapered shape which becomes narrower as the first partition wall side width.
[0051]
(5) a patterning step of forming the first electrode in a stripe shape on one surface of the transparent substrate;
A partition wall forming step that is performed after the above-described step and forms an electrode separation partition wall made of an insulating material in a stripe shape in a state of crossing the first electrode with respect to one surface of the first electrode;
A light emitting layer forming step that is performed after the partition wall forming step and forms a light emitting layer made of an organic EL material in a thin film shape between the electrode separation barriers;
A method of manufacturing an organic EL display device including a step of forming a second electrode in parallel stripes so as to cover the light emitting layer, which is performed after the light emitting layer forming step.
In the partition forming step, a film to be an electrode separation partition is formed on the substrate, and then the film is etched to form a flange on the side opposite to the first electrode side of the electrode separation partition. An organic EL display device, characterized in that a skirt having a projecting dimension larger than the flange is formed on the first electrode side of the separation partition.
[0052]
(6) The method for manufacturing an organic EL display device according to (5), wherein the film is formed of an inorganic material.
(7) The method for manufacturing an organic EL display device according to (5) above, wherein the film is formed by laminating a first film formed of an inorganic material and a second film formed of an inorganic material. .
[0053]
(8) The method for manufacturing an organic EL display device according to (5), wherein the film is formed by laminating a first film formed of an inorganic material and a second film formed of an organic material. .
[0054]
(9) The manufacturing of the organic EL display device according to any one of the above technical thoughts (5) to (8), wherein the etching step includes a first etching step for forming a collar portion and a second etching step for forming a skirt portion. Method.
[0055]
The inventions described in the technical ideas (5) to (9) can appropriately manufacture the organic EL display device of the present invention.
[0056]
【The invention's effect】
As described above in detail, the present invention can prevent a short circuit between the first electrode and the second electrode formed with the organic EL layer interposed therebetween.
[Brief description of the drawings]
FIG. 1 is a schematic partial perspective view showing an embodiment of an organic EL display device.
FIG. 2 is an enlarged schematic cross-sectional view of a main part.
3A, 3B, and 3C are partial schematic views in a manufacturing process of an organic EL display device.
FIGS. 4D and 4E are partial schematic views in a manufacturing process of an organic EL display device.
5 (f) and 5 (g) are partial schematic diagrams in a manufacturing process of an organic EL display device.
FIGS. 6A, 6B, and 6C are schematic cross-sectional views of main parts showing another embodiment of the present invention.
FIG. 7 is a partial schematic cross-sectional view of a conventional organic EL display device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Organic EL color display device, 12 ... Board | substrate, 15 ... Overcoat layer, 16 ... 1st electrode, 17 ... Electrode separation partition, 18 ... 1st partition, 18a ... Bottom part, 19 ... 2nd partition, 19a ... 庇Part, 20 ... organic EL layer, 21 ... second electrode, 22 ... light emitting element, w1 ... projecting dimension of skirt part 18a, w2 ... projecting dimension of flange part 19a of second partition wall 19, t1 ... organic EL layer 20 and Total film thickness dimension of the two electrodes 21, t <b> 2... Height dimension from the first electrode 16 to the second partition wall 19.

Claims (4)

A substrate of transparent, a first electrode formed on one surface of the front Stories substrate in stripes, formed in stripes in a state of crossing the first electrodes with respect to one surface of the first electrode insulating An electrode separation partition made of a material, a thin-film light emitting layer made of an organic electroluminescence (EL) material formed between the electrode separation partitions, and formed in parallel stripes so as to cover the light emission layer An organic EL display device comprising: a second electrode; and a light emitting element formed by a crossing portion of each of the first electrode and the second electrode and the light emitting layer existing between the crossing portions formed in a matrix. In
The electrode separation partition includes a first partition made of an inorganic material having a skirt formed on the first electrode side, and a second partition made of an organic material having a flange formed on the top surface of the first partition. consists, the projecting dimension of the skirt portion of the first partition wall, the second partition wall organic EL display device is larger than the projecting dimension of the eaves portion of. The organic EL display device according to claim 1, wherein the second partition wall has a flat trapezoidal cross-sectional shape . The first partition wall, a silicon oxide, an organic EL display device according to claim 1 or 2 is formed of silicon nitride or magnesium oxide. Height from the first electrode of the visor portion of the electrode separating partitions is claim is set to be larger than the total thickness dimension of the thickness dimensions of the thickness dimension and a second electrode of the light emitting layer 1-3 The organic EL display device according to any one of the above.

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