JP4096403B2 - Method for manufacturing electroluminescent element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing an electroluminescent element, and more particularly to a method for manufacturing an electroluminescent element in which an electroluminescence (hereinafter referred to as EL) layer is sandwiched between electrodes.
[0002]
[Prior art]
In recent years, an electroluminescent element using an organic EL material has been developed for an electroluminescent element, and an electroluminescent element 1 having a structure as shown in FIG. 7 is considered. That is, in the electroluminescent element 1, a black matrix 8 is formed on a glass substrate 2 in a lattice pattern, color conversion films 6R and 6G are formed in a predetermined arrangement, and a protective film 9 is formed on the entire surface. The front electrode 3, the organic EL layer 4, and the back electrode 5 are formed on the top.
[0003]
[Problems to be solved by the invention]
In such an electroluminescent device, since the color conversion efficiency of the color conversion film 6R and the color conversion film 6G is different, the film thickness is controlled so as to emit light with uniform luminance. For example, by the incidence of blue light The thickness of the color conversion film 6R that emits red light is set to about 20 μm, and the thickness of the color conversion film 6G that emits red light by the incidence of blue light is set to about 10 μm. There was a difference in thickness between 6R and 6G. Further, since the dot portion of blue display does not have a color conversion film, a step is formed between the display portions of R, G, and B, and step coverage of the organic EL layer 4 is deteriorated. It is feared that the organic EL layer 4 is disconnected at the edge portion and the front electrode 3 and the back electrode 5 are short-circuited.
[0004]
An object of the present invention is to provide a method for manufacturing an electroluminescent element having a structure in which occurrence of a short circuit is small.
[0005]
[Means for Solving the Problems]
According to a first aspect of the present invention, in the method of manufacturing an electroluminescent element having the first color conversion film and the second color conversion film, the step of patterning the first color conversion film at a predetermined position on the transparent substrate; Forming a second color conversion film on the transparent substrate so as to completely cover the first color conversion film and having an opening at a predetermined position so that the upper portion is exposed in the opening; A step of forming a protective film so as to flatten the surface on the insulating film and the second color conversion film, a step of forming a front electrode film on the protective film, and the front electrode film The method includes a step of forming an organic EL layer thereon and a step of forming a back electrode on the organic EL layer .
[0006]
Therefore, in the first aspect of the invention, the insulating film having the opening in the second color conversion film relaxes the step between the first color conversion film and the second color conversion film, so that the step coverage of the front electrode or the like is reduced. Can be improved, and disconnection of these constituent films can be prevented.
[0007]
According to a second aspect of the present invention, in the electroluminescent element manufacturing method according to the first aspect, the first color conversion film and the insulating film are formed of a photosensitive resin material.
[0008]
The invention according to claim 3 is a method for manufacturing an electroluminescent element, comprising: forming a first insulating film having a first opening and a second opening on a transparent substrate ; and the first opening. Forming a first color conversion film so as to be flush with a surface of the first insulating film, and forming a second insulating film having a third opening formed on the second opening. Forming a second color conversion film in the second opening of the first insulating film so as to be flush with the surface of the second insulating film; and on the second insulating film And a step of forming a protective film on the second color conversion film, a step of forming a front electrode film on the protective film, a step of forming an organic EL layer on the front electrode film, and the organic EL And a step of forming a back electrode on the layer .
[0009]
Therefore, in the invention described in claim 3, since the color conversion film material has a low resolution, the processing dimension of the first insulating film using the photolithography method is finer than the processing dimension of the color conversion film material by photosensitivity. By forming the color conversion film in the opening of the first insulating film, the line width of the color conversion film can be finely formed. For this reason, it becomes possible to manufacture an electroluminescent element capable of high-definition display. In addition, the step difference between the first color conversion film and the second color conversion film can be reduced by the first insulating film and the second insulating film, so that the step coverage of the front electrode or the like can be improved.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the details of the method for producing an electroluminescent element according to the present invention will be described based on embodiments shown in the drawings.
[0011]
(Embodiment 1)
The first embodiment will be described with reference to FIGS. First, as shown in FIG. 1A, a black matrix 12 is formed on a glass substrate 11 in a lattice shape. After that, a negative photosensitive material that is excited by emission of blue light of a predetermined wavelength range and emits green light of a predetermined wavelength range is coated, and a development is performed after exposing the portion where the negative photosensitive material is left. Then, as shown in FIG. 1B, a color conversion film (hereinafter referred to as a green conversion film) 13 made of a negative photosensitive material is arranged in an opening 13 of the black matrix 12 in an arrangement corresponding to a predetermined color arrangement. And patterning so as to cover. The green conversion film 13 is formed to have an optimum thickness for emitting green light having good visibility and, for example, about 10 μm.
[0012]
Next, as shown in FIG. 1C, a flattening film 14 is formed on the entire display region by, for example, spin coating so that the green conversion film 13 is completely filled. The material of the planarizing film 14 is a well-known negative synthetic resin material having photosensitivity developed as a spacer material for a liquid crystal display panel, and the light transmittance after film formation is 90% or more. The synthetic resin material for forming the flattening film 14 is a material that can be formed to have a film thickness of about the gap of the liquid crystal display panel, and can be formed to a thickness of about several tens of μm.
[0013]
Thereafter, a synthetic resin, which will be described later, becomes a planarizing film 14 other than a portion where a color conversion film (hereinafter referred to as a red conversion film) 15A that is excited by emitting blue light and emits red light is hereinafter disposed at a predetermined position. After the material is exposed, it is developed to form an opening 14A as shown in FIG.
[0014]
Subsequently, as shown in FIG. 2B, the red conversion film material 15 for forming the red conversion film 15A on the opening 14A and the planarizing film 14 is made visible, including the depth of the opening 14A. The film is formed by spin coating so as to have an optimum thickness for emitting red light with good luminance, for example, a thickness of about 20 μm. Since the red conversion film 15 is made of a non-photosensitive material, patterning is performed by the following method. That is, by using a photolithography technique, patterning is performed so as to leave the resist mask 16 above the material of the red conversion film 15 corresponding to the opening 14A as shown in FIG. Part of the red color conversion film material 15 is removed by wet etching. As a result, as shown in FIG. 2C, a red conversion film 15A slightly protruding (about 2 to 3 μm) from the opening 14A of the planarization film 14 can be formed. The red conversion film 15 </ b> A and the green conversion film 13 are made of a material that can withstand the pre-bake and main-bake temperatures when the resist mask 16 is formed.
[0015]
Next, as shown in FIG. 3A, the entire display region is coated with a protective film 17 made of an acrylic synthetic resin. At this time, since the projecting dimension of the red conversion film 15A is very small, it can be covered with the protective film 17, and the surface of the protective film 17 can be formed flat. Thereafter, a transparent conductive material such as ITO (indium tin oxide) or In ₂ O ₃ (ZnO) _m (where 0 <m <3) (preferably with respect to the organic EL layer 20 described later) is formed on the protective film 17. The front electrode film 18 made of a conductive material having a high hole injection property is formed by vapor deposition or sputtering. Further, a resist mask 19 is patterned on the front electrode film 18 by using a photolithography technique. The resist mask 19 is formed so as to be parallel to each other at positions corresponding to the columns or rows of the openings of the black matrix 12 formed on the glass substrate 11. Then, wet etching or dry etching is performed using the resist mask 19 to form a front electrode 18A as shown in FIG.
[0016]
Thereafter, as shown in FIG. 3C, the organic EL layer 20 is formed over the entire display region, and MgIn or the like is formed on the organic EL layer 20 so as to correspond to the row or column of the front electrode 18A described above. A back electrode 21 such as AlLi is formed by vapor deposition using a metal mask. The organic EL layer 20 is composed of an electron transport layer composed of Aluminum-tris (8-hydroxyquinolinate), 96% by weight of 4,4′-Bis (2,2-diphenylvinylene) biphenyl and 4% in order from the front electrode film 18 side. Light-emitting layer composed of 4,4'-Bis ((2-carbazole) vinylene) biphenyl by weight%, N, N'-di (α-naphthyl) -N, N'-diphenyl-1,1'-biphenyl-4 , 4'-diamine, which consists of three layers of hole transport layer, and emits light in the blue wavelength region when current flows inside. In this way, an electroluminescent element 22 as shown in FIG. 3C can be manufactured.
[0017]
In the manufacturing method of the electroluminescent element of this embodiment, the level difference caused by the color conversion film having a large film thickness difference is relaxed by using the planarizing film 14 or the protective film 17, so that the front electrode 18 </ b> A, the organic EL layer 20, and When the back electrode 21 is formed, these step coverages can be improved to prevent the occurrence of step breaks.
[0018]
Although the present embodiment has been described above, in the present embodiment, the red conversion film 15A and the green conversion film 13 are formed in the openings of the black matrix 12, but predetermined color filters are formed in the respective openings of the black matrix 12. After that, the red conversion film 15A and the green conversion film 13 can be formed on necessary portions. The red, green, and blue color filters emit red and green light emitted from the color conversion film. It is also possible to improve the color purity of the blue light emitted from the organic EL layer 20 without passing through the color conversion film. In the present embodiment described above, the front electrode 18A is formed on the protective film 17. However, in order to improve the reliability of the element, a silicon oxide film or a silicon nitride film is formed on the protective film 17. Of course, the front electrode 18A may be formed later. In Embodiment 1 described above, the light emission color of the organic EL layer 20 is set to blue. However, the present invention is not limited to this, and each color conversion film is appropriately changed according to the light emission color of the organic EL layer 20. It may be a thing. Further, in the present embodiment, the organic EL layer 20 is used as the light emitting layer, but an inorganic EL layer may be used.
[0019]
(Embodiment 2)
Embodiment 2 of the manufacturing method of the electroluminescent element which concerns on this invention is demonstrated using Fig.4 (a)-FIG.6 (b). First, as shown in FIG. 4A, a black matrix 12 is formed on a glass substrate 11 in a lattice shape. After that, a negative photosensitive resin is formed by controlling the film thickness by spin coating, and then the portion of the opening of the black matrix 12 where no color conversion film is arranged according to the set color arrangement (blue light emitting portion) Only this is exposed to cure the resin in this portion, and as shown in FIG. 4B, the first planarizing film 14A is patterned. Here, the first planarization film 14 </ b> A does not need to cover the opening edge of the black matrix 12 facing the opening in which the color conversion film is arranged among the openings of the black matrix 12.
[0020]
Thereafter, a negative photosensitive green conversion film material is applied, and as shown in FIG. 4C, the green conversion film in the opening of the first planarization film 14A corresponding to the portion set as the green light emitting portion in advance. After the material is exposed and cured, the green conversion film 13 is formed by etching back so as to be flush with the surface of the first planarization film 14A. At this time, the pattern width W of the green conversion film 13 is determined by the photolithography accuracy of the first planarization film 14A. Further, the green conversion film 13 in the opening of the first planarizing film 14A corresponding to the portion set in advance as the red light emitting portion is removed by etching.
[0021]
Next, as shown in FIG. 5A, the second flattening film 14B is formed on the entire display area except for the opening of the first flattening film 14A corresponding to the portion previously set as the red light emitting portion. . Note that the depth of the recess formed by the first planarizing film 14A and the second planarizing film 14B is set to about 20 μm. Thereafter, the surface of the second planarizing film 14B is exposed by spin coating the red conversion film material 15 on the entire surface and performing etch back. At this time, the red conversion film 15A is formed only in the recess formed by the first planarization film 14A, the second planarization film 14B, and the opening of the black matrix 12, and the surface of the red conversion film 15A and the second The surface of the planarizing film 14B is flush with the surface.
[0022]
Next, after forming the protective film 17 as shown in FIG. 6A, as shown in FIG. 6B, the front electrode 18A, the organic EL layer 20, and the back electrode 21 are formed as in the first embodiment. Thus, the manufacture of the electroluminescent element 22 is completed.
[0023]
In the present embodiment, the width of the green conversion film 13 is determined by the width K of the opening formed in the first planarization film 14A, and the width of the red conversion film 15A is also the same as that of the first planarization film 14A and the second planarization film. Since it is determined by the width of the opening formed in the film 14B, the color conversion film can be formed with the accuracy of photolithography of the planarization film. Incidentally, when patterning a color conversion film, the color conversion film material containing a large amount of fluorescent material has low transmittance and low resolution, and therefore, when it is exposed and patterned, its dimensional accuracy is the same as that of a normal photolithographic photomask. Although it is about 100 μm larger than the minimum dimension used, as described above, in this embodiment, the first and second planarization films formed of a material having high transmittance and high resolution are miniaturized to the minimum dimension. Can be made possible. For this reason, it is possible to achieve high definition in the display of the electroluminescent element. Further, since the upper surface of the red conversion film 15A can be flush with the surface of the second planarization film 14B, the thickness of the protective film 17 formed thereon can be set thin, and the organic EL layer The distance between the 20 light emitting portions and the color conversion film can be shortened. For this reason, the influence of parallax can be reduced significantly.
[0024]
Although the second embodiment has been described above, the present invention is not limited to this, and various modifications accompanying the gist of the configuration are possible. For example, in the present embodiment, the front electrode 18A is provided on the protective film 17, but the front electrode 18A may be formed via a silicon oxide film or a silicon nitride film as in the first embodiment. Further, as described in the first embodiment, the color filter may be arranged on the glass substrate 11. In the second embodiment, the emission color of the organic EL layer 20 is set to blue as in the first embodiment. However, the present invention is not limited to this, and each color conversion is performed according to the emission color of the organic EL layer 20. The film is also changed as appropriate. Furthermore, in this embodiment, the organic EL layer 20 is used as the light emitting layer, but an inorganic EL layer may be used.
[0029]
【The invention's effect】
As is apparent from the above description, according to the present invention, an electroluminescent device having a flat structure in which each constituent layer is not stepped can be manufactured.
[Brief description of the drawings]
FIGS. 1A to 1C are process cross-sectional views illustrating Embodiment 1 of a method for manufacturing an electroluminescent element according to the present invention. FIGS.
FIGS. 2A to 2C are process cross-sectional views illustrating Embodiment 1. FIGS.
3A to 3C are process cross-sectional views illustrating Embodiment 1. FIG.
4A to 4C are process cross-sectional views illustrating Embodiment 2 of the method for manufacturing an electroluminescent element according to the present invention.
5A to 5C are process cross-sectional views illustrating Embodiment 2. FIG.
FIGS. 6A and 6B are process cross-sectional views illustrating Embodiment 2. FIGS.
FIG. 7 is a cross-sectional view of a conventional electroluminescent element that performs multicolor display.
[Explanation of symbols]
11 glass substrate 13 green conversion film 14 flattening film 14A first flattening film 14B second flattening film 15 red conversion film material 15A red conversion film 17 protective film 18A front electrode 20 organic EL layer 21 back electrode 22 electroluminescent element

Claims (4)

In a method for manufacturing an electroluminescent element having a first color conversion film and a second color conversion film,
Patterning the first color conversion film at a predetermined position on the transparent substrate;
On the transparent substrate, a step of completely covering the first color conversion film and forming an insulating film having an opening at a predetermined position;
Forming a second color conversion film in the opening so that an upper portion is exposed;
Forming a protective film on the insulating film and the second color conversion film so as to flatten the surface ;
Forming a front electrode film on the protective film;
Forming an organic EL layer on the front electrode film;
Forming a back electrode on the organic EL layer;
A method for manufacturing an electroluminescent element, comprising:   The method of manufacturing an electroluminescent element according to claim 1, wherein the first color conversion film and the insulating film are formed of a photosensitive resin material. Forming a first insulating film having a first opening and a second opening on a transparent substrate ;
Forming a first color conversion film in the first opening so as to be flush with the surface of the first insulating film ;
Forming a second insulating film having a third opening formed on the second opening;
Forming a second color conversion film in the second opening of the first insulating film so as to be flush with the surface of the second insulating film ;
Forming a protective film on the second insulating film and the second color conversion film;
Forming a front electrode film on the protective film;
Forming an organic EL layer on the front electrode film;
Forming a back electrode on the organic EL layer;
A method for manufacturing an electroluminescent element, comprising:   4. The method of manufacturing an electroluminescent element according to claim 3, wherein the first color conversion film and the first insulating film are formed of a photosensitive resin material.

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