JP2010267416A - Organic electroluminescent display device, method of manufacturing the same, and deposition method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for forming a luminescent layer superior in uniformity of thickness, even when recesses periodically exist on the bottom of a disposition region to dispose a functional liquid, in an organic EL display device having the luminescent layer formed by storing and drying the functional liquid. <P>SOLUTION: This organic electroluminescent display device includes a lower structure formed on a glass substrate 11 while containing a positive electrode 14 and having a plurality of contact holes 18, barrier plates 17 formed around the disposition region containing a plurality of the contact holes 18 on the lower structure, and one or more protrusions 30 formed between adjacent contact holes 18 on the disposition region. Furthermore, the luminescent layer is integrally formed in the portions excluded by the protrusions 30 on the disposition region by disposing and drying the functional liquid containing an organic material capable of electroluminescence, and an upper structure containing a negative electrode on the luminescent layer is formed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an organic electroluminescence (EL) display device, a manufacturing method thereof, and a film forming method, and particularly relates to an organic electroluminescence display device having a light emitting layer formed by applying and drying a functional liquid.

  An organic EL display device is a light-emitting display device that utilizes an electroluminescence phenomenon of an organic compound, and has been put into practical use as a small-sized display device used for a mobile phone or the like.

  An organic EL display device is configured by arranging on a substrate a plurality of organic EL elements that can be independently controlled for each pixel. A typical organic EL display device is manufactured by laminating a drive circuit, an anode, a light emitting functional layer, and a cathode on a substrate. In the light emitting functional layer, one or more of a plurality of functional layers such as an electron injection layer, an electron transport layer, a hole transport layer, and a hole injection layer are stacked together with a light emitting layer made of an organic compound.

  In such a configuration, charges are injected from the anode and the cathode into the light emitting layer through the hole transport layer and the like, and the injected charges are recombined in the light emitting layer to generate light emission. It is important that the light emitting layer is formed with a uniform film thickness. This is because if the thickness of the light-emitting layer is not uniform, the current distribution in the light-emitting surface will be non-uniform, resulting in uneven brightness, and a reduction in device life due to current concentration in a thin part. It is.

  The light emitting layer is formed, for example, by applying a functional liquid containing an organic compound to be the light emitting layer to a substrate and drying it. The functional film formed by storing and drying the functional liquid is not limited to the light emitting layer of the organic EL display device, but is used in various devices, and various types for forming a functional film having excellent thickness uniformity. Technologies are being considered.

  For example, Patent Document 1 forms a functional film by forming a partition on a substrate and storing and drying a functional liquid to be a functional film in a space (called a liquid receiving unit) partitioned by the partition for each pixel. A manufacturing method is disclosed. The functional liquid is disposed in the liquid receiving portion by, for example, an ink jet method.

  In this manufacturing method, paying attention to the drying speed of the functional liquid, a plurality of liquid receiving portions are formed in a dot shape up to an outer peripheral portion (called an ineffective region) of an effective region that is a region corresponding to a pixel effective as a display device. It is provided to store a larger amount of functional liquid in the liquid receiving part farther from the effective area. Thereby, the drying speed of the functional liquid in the vicinity of the boundary of the effective area is relaxed, and the drying speed of the functional liquid becomes uniform throughout the effective area. As a result, a functional film having excellent thickness uniformity over the entire effective region is formed.

JP 2007-103349 A

  In the conventional method for manufacturing a functional film using a liquid receiving unit divided for each pixel, the individual liquid receiving units are smaller as the pixels are miniaturized depending on the accuracy of the dimensions of the liquid receiving unit and the accuracy of the discharge amount of the functional liquid. As a result, the variation in the depth of the functional liquid stored in the liquid crystal increases, and as a result, the variation in the thickness of the functional film for each pixel increases.

  In order to solve this problem, the inventors disclosed in Japanese Patent Application No. 2008-000698, which is a related patent application, that a plurality of pixels that should emit light of the same color are arranged in a line, and one continuous pixel is provided for each pixel. The structure which provides a liquid receiving part is proposed. In such a configuration, a light emitting layer is formed by disposing and drying a functional liquid containing an organic material capable of electroluminescence in the liquid receiving portion. A partition wall extending in a line shape along a plurality of pixels may be referred to as a line bank because of its shape.

Hereinafter, typical configurations and problems of an organic EL display device having a line bank will be described.
FIG. 7 is a partial perspective view showing a typical example of a configuration in the middle of manufacture of an organic EL display device having a line bank. FIG. 7 is a schematic diagram for explanation, and the ratios of the sizes of the respective parts are drawn in a non-identical manner.

  The organic EL display device 9 shown in FIG. 7 has a lower structure in which a driving circuit layer 12, a planarizing layer 13, an anode 14, a pixel regulating layer 15, and a hole injection layer 16 are laminated in this order on a glass substrate 11. And a partition wall 17 formed on the lower structure.

  The partition wall 17 is provided in a line at a position that divides pixels that should emit light of different colors. Two adjacent partition walls 17 are connected outside the figure to form a liquid receiving portion having the lower structure as a bottom and the partition wall 17 as a dam.

  A functional liquid containing an organic material capable of electroluminescence is disposed in the liquid receiving portion by an ink jet method. Due to the fluidity of the functional liquid, the height of the liquid surface of the functional liquid is unified within the liquid receiving portion, so that the depth of the arranged functional liquid is unified for each pixel. As a result, variation in the finished thickness of the light emitting layer, which is a functional film, for each pixel is reduced.

  In this way, in the organic EL display device having a line bank, the finished thickness of the light emitting layer can be made uniform.

  However, the inventors have noticed that in the organic EL display device 9 configured as described above, the light emission luminance is increased in the vicinity of the contact hole 18 in the light emitting region 19. This phenomenon indicates that the light emitting layer 20 is thin in the vicinity of the contact hole 18 in the light emitting region 19.

  FIG. 8 is a CC ′ sectional view for explaining this phenomenon. The dotted line in FIG. 8 indicates the position of the upper surface of the light emitting layer 20 to be formed.

  As the functional liquid collected in the contact hole 18 is dried and loses its volume, the functional liquid on the light emitting region 19 flows into the contact hole 18. As a result, as shown in FIG. 8, it is considered that the finished thickness of the light emitting layer 20 is reduced in the vicinity of the contact hole 18 in the light emitting region 19.

  The phenomenon that the finished thickness of the functional film is reduced in the vicinity of the concave portion is not limited to the light emitting layer, but any functional film (for example, a color film) formed by storing and drying the functional liquid in the liquid receiving portion having the concave portion on the bottom surface. This is a problem common to filter membranes. Such a phenomenon is generally caused not only by the contact hole 18 but also by a recess provided irrespective of the pixel.

  The present invention has been made in view of the above circumstances, and an apparatus having a functional film formed by placing a functional liquid in a liquid receiving portion and drying, and in particular, an organic EL having a light emitting layer as such a functional film. In the display device, an object is to provide a technique capable of forming a functional film having excellent thickness uniformity even when the bottom surface of the liquid receiving portion has a recess.

  In order to solve the above-described problems, an organic EL display device of the present invention is formed on a substrate, includes a lower structure including one of an anode and a cathode and having a plurality of recesses, and the lower structure. And a partition formed around the arrangement area including the plurality of recesses, one or more protrusions formed between adjacent recesses on the arrangement area, and excluded by the protrusions on the arrangement area A light emitting layer that is integrally formed on the light emitting portion and includes an electroluminescent organic material, and an upper structure that is formed on the light emitting layer and includes the other of the anode and the cathode.

  According to such a configuration, when the light emitting layer is formed by disposing the functional liquid containing the organic material in the disposition region and drying, the projecting portion gets in the way and flows into the recess. The amount of the functional liquid can be reduced.

  As a result, a larger amount of the functional liquid remains outside the concave portion, so that the problem that the finished thickness of the light emitting layer becomes thin in the vicinity of the concave portion is alleviated, and the thickness uniformity is excellent. The light emitting layer can be formed.

  In addition, it is preferable that the protrusion is provided at a height of 500 nm or less from a portion for supplying a charge to the light emitting layer of the lower structure.

  According to such a configuration, the protrusion allows the flow of the functional liquid to the extent that the uniformity of the finished thickness of the light emitting layer is not impaired while obstructing the movement of the functional liquid into the recess. Therefore, it is effective for making the thickness of the light emitting layer uniform.

  A thin film transistor may be formed in the lower structure, and the thin film transistor may be connected to the one of the anode and the cathode in the recess.

Such a configuration is suitable for an active matrix organic EL display device.
The protrusion may be made of an insulator.

  According to such a configuration, since the cross-sectional area of the light emitting layer is reduced due to the protrusion that is an insulator, the current flowing between both sides of the protrusion of the light emitting layer is reduced. In the case where separate light emitting regions that are driven independently are provided on both sides of the protrusion, it is preferable to reduce the influence of the drive current of one light emitting region on the light emission of the other light emitting region.

  The present invention can be realized not only as such an organic EL display device but also as a device including a functional film, a method for manufacturing an organic EL display device, and a film forming method.

  An organic EL display device according to the present invention is formed on a substrate, includes a lower structure having one of an anode and a cathode and having a plurality of recesses, and an arrangement including the plurality of recesses on the lower structure Since the partition wall formed around the area and one or more protrusions formed between the adjacent recesses on the arrangement area, the functional liquid containing the organic material is arranged in the arrangement area and dried. Thus, when the light emitting layer is formed, the amount of the functional liquid flowing into the concave portion can be reduced because the protruding portion becomes an obstacle.

  As a result, a larger amount of the functional liquid remains outside the concave portion, so that the problem that the finished thickness of the light emitting layer becomes thin in the vicinity of the concave portion is alleviated, and the thickness uniformity is excellent. The light emitting layer can be formed.

The fragmentary perspective view which shows an example of a structure of the organic electroluminescence display in embodiment AA 'sectional view of an organic EL display device in an embodiment BB 'sectional view of an organic EL display device in an embodiment Manufacturing process diagram of organic EL display device in embodiment Partial perspective view showing another example of the shape of the protrusion Partial perspective view showing another example of the shape of the protrusion Partial perspective view showing an example of the configuration of a conventional organic EL display device CC 'sectional view of a conventional organic EL display device

  Hereinafter, an organic EL display device according to an embodiment of the present invention will be described in detail with reference to the drawings.

(Constitution)
FIG. 1 is a partial perspective view showing an example of a configuration in one stage of manufacture of an organic EL display device having a line bank according to an embodiment of the present invention. In addition, FIG. 1 is a schematic diagram for explanation, and the ratio of the sizes of the respective parts is drawn in a random manner.

  2 and 3 are an AA ′ sectional view and a BB ′ sectional view of the organic EL display device 1, respectively.

  The organic EL display device 1 includes a lower structure in which a driving circuit layer 12, a planarization layer 13, an anode 14, a pixel regulation layer 15, and a hole injection layer 16 are stacked in this order on a glass substrate 11, and a lower structure. A partition wall 17 and a protrusion 30 are provided on the body.

  The organic EL display device 1 is different from the organic EL display device 9 described in the section of the prior art in that a protrusion 30 is provided between adjacent contact holes 18.

  The anode 14 is divided for each pixel, and is connected to a driving thin film transistor (TFT) for each pixel provided in the driving circuit layer 12 in the contact hole 18.

  The pixel regulating layer 15 is an insulating film, and an opening is provided in a predetermined range on the anode 14. The pixel restricting layer 15 limits the light emitting region 19 in which light emission occurs to only a portion corresponding to the opening.

  Two adjacent partition walls 17 are connected outside the figure so as to surround an arrangement region including a plurality of contact holes 18, and form a liquid receiving portion having the lower structure as a bottom and the partition wall 17 as a dam.

  Thereafter, the functional liquid containing the organic material capable of electroluminescence is stored and dried in the arrangement region surrounded by the partition wall 17 on the lower structure, so that the portion excluded by the protrusion 30 on the arrangement region is removed. The light emitting layer is integrally formed. An upper structure including a cathode is formed on the light emitting layer.

  In the organic EL display device 1, the provision of the protrusion 30 makes it difficult for the functional liquid to flow into the contact hole 18 due to the protrusion 30 being in the way. As a result, the amount of the functional liquid flowing into the contact hole 18 is reduced, and the amount of the functional liquid remaining on the light emitting region 19 is increased.

  The dotted line in FIG. 2 indicates the position of the upper surface of the light emitting layer 20 formed when the protrusion 30 is present. Compared with the case where the protrusion 30 in FIG. 8 is not provided, the reduction in the thickness of the light emitting region 19 in the vicinity of the contact hole 18 is alleviated.

  Here, the protrusion 30 is preferably provided at a height of 500 nm or less from the hole injection layer 16 in the light emitting region 19. If the protrusion 30 has such a height, the protrusion 30 does not impair the uniformity of the finished thickness of the light emitting layer 20 while obstructing the movement of the functional liquid into the contact hole 18. Since the liquid flow is allowed, it is effective in making the thickness of the light emitting layer 20 uniform. The height of the protrusion is appropriately selected according to the aperture size of the pixel, the thickness of each layer constituting the light emitting layer, the material, and the like, and the height is an example of the embodiment.

  Further, the protrusion 30 can be moved back and forth in the liquid receiving portion at the initial liquid level where the functional liquid is disposed so as not to prevent the liquid level of the functional liquid from being unified in the liquid receiving portion. Provided in the shape.

(Production method)
Below, an example of the manufacturing method of the organic electroluminescence display 1 is demonstrated.

  4A to 4D are cross-sectional views illustrating the configuration of the organic EL display device 1 at several stages of manufacture. 4A, 4 </ b> B <b> 1, 4 </ b> C, and 4 </ b> D correspond to the AA ′ cross section of the organic EL display device 1. FIG. 4B2 corresponds to the BB ′ cross section of the organic EL display device 1.

  First, the drive circuit layer 12 is formed by depositing a semiconductor in a thin film on the surface of the glass substrate 11. A drive circuit including an element such as a TFT for each pixel is formed in the formed drive circuit layer 12.

  A planarizing layer 13 made of an insulating organic material is formed on the drive circuit layer 12. A contact hole 18 is formed in the formed planarization layer 13 by dry etching.

  The anode 14 is formed by depositing metal by sputtering. The formed anode 14 is divided for each pixel by dry etching. The anode 14 divided for each pixel is electrically connected to a TFT (not shown) for each pixel formed in the drive circuit layer 12 in the contact hole 18.

A pixel regulation layer 15 made of an insulating inorganic material such as SiO ₂ , SiN, SiON, Al ₂ O ₃ , or AlN or an insulating organic material such as polyimide resin is formed on the anode 14. An opening is provided in the formed pixel regulation layer 15 by dry etching.

Through the steps so far, the structure shown in FIG. 4A is formed.
Next, the hole injection layer 16 made of an organic material such as polythiophene-based PEDOT: PSS is formed by a method such as spin coating, inkjet, or nozzle coating. The hole injection layer 16 may be formed by depositing an inorganic material such as molybdenum oxide by sputtering.

  A photosensitive polyimide resin is applied onto the hole injection layer 16 by spin coating, and the partition wall 17 is formed by photolithography.

  The protrusion 30 is formed after the partition wall 17 is formed and before the functional liquid is disposed. The protrusion 30 is formed by applying a photosensitive polyimide resin by spin coating and performing a photolithography process. As shown in FIG. 1, the protrusion 30 is formed between adjacent contact holes 18.

Through the steps so far, the structures shown in FIGS. 4B1 and 4B2 are formed.
Next, polyphenylene vinylene (hereinafter referred to as PPV) which is an organic material capable of electroluminescence and a derivative thereof, or a functional liquid containing polyfluorene and a derivative thereof is arranged in an arrangement region surrounded by the partition wall 17 by an inkjet method or the like. Then, the light emitting layer 20 is formed by drying.

  As described above, since the functional liquid is difficult to flow into the contact hole 18 by being obstructed by the protrusion 30, the functional liquid remains in a large amount in the light emitting region 19, and as a result, light emission excellent in thickness uniformity. Layer 20 is formed.

Through the steps so far, the structure shown in FIG. 4C is formed.
Next, an electron transport layer 21 made of a transition metal oxide is formed by a dry process.

  Then, an ultra-thin film having high light transmittance using a metal having a small work function such as Ba or Al is formed, and a conductive film made of a light-transmitting material such as ITO or IZO is laminated thereon, thereby forming the cathode 22. Form.

Through the steps so far, the structure shown in FIG. 4D is formed.
Finally, sealing is completed using glass frit or the like.

(Other specific examples of protrusions)
First, the protrusion 30 moves back and forth in the liquid receiving portion at the initial liquid level where the functional liquid is arranged so as not to prevent the liquid level of the functional liquid from being unified in the liquid receiving portion. It was stated that it can be provided in a shape that can be made.

  5 and 6 are partial perspective views showing other specific examples of the shape of the protrusion 30 that satisfies such a condition.

  As shown in the organic EL display device 2 of FIG. 5, the protrusion 30 may be provided so as to cross the arrangement area at a height lower than the initial liquid level where the functional liquid is arranged.

  Further, as shown in the organic EL display device 3 of FIG. 6, the protrusion 30 may be provided integrally with the partition wall 17 and have a gap through which the functional liquid can come and go.

  5 and 6, a plurality of protrusions 30 are provided between adjacent contact holes 18, but one protrusion 30 may be provided between adjacent contact holes 18. That is, the period of the protrusion 30 and the period of the contact hole 18 may be the same.

  In that case, it is desirable to provide the protrusion 30 between the contact hole 18 and the light emitting region 19 of the same pixel in one pixel region.

  It is considered that most of the functional liquid on the light emitting region 19 flows into the contact hole 18 of the same pixel provided at a close position.

  Therefore, when one protrusion 30 is provided between adjacent contact holes 18, the protrusion 30 is formed between the contact hole 18 of the adjacent pixel and the light emitting region 19 at a position that divides the adjacent pixel area. It is advantageous to form the protrusion 30 between the contact hole 18 and the light emitting region 19 of the same pixel in one pixel region in order to make the finished thickness of the light emitting layer 20 uniform.

  In the example shown in FIG. 5, the protruding portion 30 completely surrounds the contact hole 18 together with the partition wall 17, but the protruding portion 30 is not necessarily required to interfere with the movement of the functional liquid into the contact hole 18. It is not necessary to completely enclose 18. Where and how large the protrusions 30 are arranged are matters to be designed according to characteristics such as the viscosity of the functional liquid.

  5 and 6, the contact hole 18 is drawn at the center of the width of the arrangement region, but the contact hole 18 is not necessarily arranged at the center of the width of the arrangement region.

  According to the organic EL display device described above, the functional liquid that flows into the contact hole 18 when the functional liquid including the organic material, which becomes the light-emitting layer 20, is disposed in the arrangement region due to the protrusion 30 interfering. The amount of can be reduced.

  Since a larger amount of the functional liquid remains outside the contact hole 18, the problem that the finished thickness of the light emitting layer 20 becomes thin in the vicinity of the contact hole 18 is alleviated, and light emission excellent in thickness uniformity is achieved. Layer 20 can be formed.

  As a result, unevenness in light emission luminance generated between adjacent contact holes 18 is reduced, and an organic EL display device capable of high-quality display is realized.

  Although the organic EL display device of the present invention has been described based on the embodiment, the present invention is not limited to this embodiment. Unless it deviates from the meaning of the present invention, those in which various modifications conceived by those skilled in the art have been made in the present embodiment are also included in the scope of the present invention.

  In the embodiment, the example in which the light emitting layer with excellent thickness uniformity is formed in the organic EL display device using the protrusions has been described. However, the protrusions of the present invention are not limited to the light emitting layer, and the bottom surface has a concave portion. It can be commonly applied to the formation of all functional films formed by storing a functional liquid in a certain liquid receiving portion and drying it.

  For example, when the hole transport layer is formed on the organic EL display device 1 of the embodiment, the protrusions as described above are useful for making the finished thickness of the hole transport layer uniform.

  The hole transport layer is a functional layer that is not shown in the organic EL display device 1, and is generally provided by a hole transport material between the hole injection layer 16 and the light emitting layer 20, and is used for hole injection. Holes are transported from the layer 16 to the light emitting layer 20.

  The material of the hole transport layer may be a high molecular material or a low molecular material as long as the material can be formed by disposing a functional liquid and drying it. When forming the light emitting layer 20 which is the upper layer, it is preferable that a crosslinking agent is included so that it is difficult to elute into the light emitting layer 20. As an example of the hole transporting material, a copolymer containing a fluorene moiety and a triarylamine moiety or a low molecular weight triarylamine derivative can be used. As an example of the crosslinking agent, dipentaerythritol hexaacrylate or the like can be used.

  The method for disposing the functional liquid to be the hole transport layer is not particularly limited, and a nozzle jet method represented by an ink jet method and a dispenser method can be used. In this case, in the ink jet method, a functional liquid, which is an organic film forming material that has been converted into an ink, is disposed on the hole injection layer 16 by being ejected from a nozzle.

  The formation of the hole transport layer by drying the disposed functional liquid is the same as the case where the light emitting layer 20 described in the embodiment is formed. In the case of the hole transport layer, as in the case of the light emitting layer 20, the functional liquid remains in the light emitting region 19 in a large amount because it is difficult for the functional liquid to flow into the contact hole 18 by being obstructed by the protrusion 30. As a result, a hole transport layer excellent in thickness uniformity is formed.

  In addition, the protrusions as described above, for example, when the fluorescent film of a PDP (Plasma Display Panel) display device is formed by disposing the functional liquid and drying, makes the finished thickness of the fluorescent film uniform. It contributes.

  The organic EL display device of the present invention can be used as any display device such as a mobile phone, a television, and a personal computer.

1, 2, 3, 9 Organic EL display device 11 Glass substrate 12 Drive circuit layer 13 Planarizing layer 14 Anode 15 Pixel regulating layer 16 Hole injection layer 17 Partition 18 Contact hole 19 Light emitting region 20 Light emitting layer 21 Electron transport layer 22 Cathode 30 Protrusion

Claims (7)

A lower structure formed on a substrate, including one of an anode and a cathode, and having a plurality of recesses;
A partition wall formed around an arrangement region including the plurality of recesses on the lower structure;
One or more protrusions formed between adjacent recesses on the placement region;
A light-emitting layer including an organic material capable of electroluminescence formed integrally with a portion of the arrangement region that is excluded from the protrusions;
An organic electroluminescence display device comprising: an upper structure formed on the light emitting layer and including the other of the anode and the cathode. 2. The organic electroluminescence display device according to claim 1, wherein the protrusion is provided at a height of 500 nm or less from a portion that supplies electric charges to the light emitting layer of the lower structure. A thin film transistor is formed in the lower structure,
2. The organic electroluminescence display device according to claim 1, wherein the thin film transistor is connected to the one of the anode and the cathode in the recess. The organic electroluminescence display device according to claim 1, wherein the protrusion is made of an insulator. A base having a plurality of recesses;
A partition formed around an arrangement region including the plurality of recesses on the base;
One or more protrusions formed between adjacent recesses on the placement region;
And a functional film integrally formed on a portion of the arrangement area that is excluded by the protrusion. Forming a lower structure including one of an anode and a cathode and having a plurality of recesses on a substrate;
Forming a partition wall around an arrangement region including the plurality of recesses on the lower structure;
Forming one or more protrusions between adjacent recesses on the placement region;
A step of integrally disposing a functional liquid containing an organic material capable of electroluminescence in a portion excluded by the protrusion on the arrangement region;
Drying the functional liquid to form a light emitting layer;
Forming an upper structure including the other of the anode and the cathode on the light emitting layer. A method for manufacturing an organic electroluminescence display device. Forming a base having a plurality of recesses;
Forming a partition around the arrangement region including the plurality of recesses on the base;
Forming one or more protrusions between adjacent recesses on the placement region;
A step of integrally disposing a functional liquid in a portion excluded by the protrusion on the arrangement region;
Forming a functional film by drying the functional liquid.

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