JP2012209138A - Organic el element, manufacturing method for the organic el element, image display device, and manufacturing method for the image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element and an image display device with excellent printability and a high opening ratio.SOLUTION: An organic EL element includes a substrate 11, a first electrode 12 formed on the substrate 11 and including a pixel region, a partition wall 23 formed on the substrate 11 and sectioning the first electrode 12, a light-emitting layer formed on the pixel region and including at least an organic material, light-emitting medium layers 19 at least one layer of which is printed with a linear pattern, and a second electrode 17 formed on the light-emitting medium layer 19 and formed covering the light-emitting medium layer 19. The partition wall 23 includes a first partition wall 23A which is formed in parallel to the linear pattern of the light-emitting medium layer 19 and at least a part of which has an inverted tapered shape, and a second partition wall 23B which is formed orthogonal to the first partition wall 23A and has a tapered shape.

Description

  The present invention relates to an organic EL element and a manufacturing method thereof, and an image display device and a manufacturing method thereof.

  In recent years, development of organic electroluminescent elements (hereinafter referred to as organic EL elements), which are light emitting elements capable of high-luminance emission by direct current low voltage driving, has been promoted. The organic EL element has a simple structure having two opposing electrodes and an organic light emitting layer made of an organic material provided between the electrodes. In this organic EL element, by passing a current between the electrodes, charges are recombined in the organic light emitting layer to emit light, and the emitted light is extracted from the light transmissive electrode.

  In an organic EL device having such a structure, a structure in which both electrodes are directly disposed on both sides of the organic light emitting layer may be employed. However, luminance per unit current or luminous flux per unit power (hereinafter referred to as light emission). In order to increase the efficiency (referred to as efficiency), an injection layer, a transport layer or a block layer, or a structure in which each of the injection layer, the transport layer, and the block layer is arranged is often employed. Specifically, a hole injection layer, a hole transport layer, a hole block layer, or a structure in which each layer is provided between the anode and the light emitting layer can be given. Alternatively, an electron injection layer, an electron transport layer, an electron block layer, or a structure in which each layer is provided between a cathode and a light emitting layer can be given. In the organic EL element, the entire structure including the plurality of layers sandwiched between both electrodes is called a light emitting medium layer.

Depending on the organic material used for the organic light emitting layer, the organic EL element uses an organic EL element using a low molecular organic light emitting material (hereinafter referred to as a low molecular organic EL element) and a polymer organic light emitting material. And organic EL elements (hereinafter referred to as polymer organic EL elements).
In a method for forming a light emitting medium layer of a low molecular organic EL element, a thin film is generally formed using a dry coating method such as a vacuum evaporation method. In the method of forming such a low molecular organic EL element, when patterning of the light emitting medium layer is necessary, a layer having a pattern corresponding to the opening of the mask is formed using a metal mask or the like. However, such a patterning method has a problem that it is difficult to obtain a desired patterning accuracy due to the accuracy of a member such as a metal mask itself as the area of the substrate increases.

  In a method for forming a light emitting medium layer of a polymer organic EL element, for example, a coating liquid in which an organic light emitting material is dissolved in a solvent is prepared, and the coating liquid is applied on a substrate using a wet coating method, and a thin film Attempts have been made to form these. Known wet coating methods for forming a thin film include spin coating, bar coating, protruding coating, dip coating, nozzle printing, ink jet, and various printing methods. However, when these wet coating methods are used, it is difficult to pattern a thin film with high definition or to form a thin film by separately applying three colors of RGB. Therefore, in the method of forming a polymer organic EL element, it is considered most effective to form a thin film using a printing method capable of patterning while applying a plurality of materials separately.

  Furthermore, in an organic EL element, a glass substrate is often used as a substrate. For this reason, among various printing methods, a method of directly contacting a hard plate such as a metal printing plate with a substrate, such as a gravure printing method, is not suitable for a method of forming an organic EL element. On the other hand, an offset printing method using an elastic rubber blanket, a rubber plate having elasticity, or a relief printing method using a photosensitive resin plate are suitable for a method of forming a polymer organic EL element. Actually, as an attempt by these printing methods, a method by offset printing (Patent Document 1), a method by letterpress printing (Patent Document 2) and the like have been proposed.

  In the case of manufacturing an image display device that requires high-definition thin film patterning using a wet coating method, an image is displayed by forming a large number of display pixels vertically and horizontally and emitting light. For this purpose, a light emitting medium layer or the like is selectively disposed on a display pixel electrode (hereinafter referred to as a pixel electrode) to form an independent organic EL element for each pixel. At that time, in order to uniformly distribute the material to each pixel and to uniformly emit light, a method of providing partition walls that partition each pixel in advance is generally used. The pixel electrode is generally rectangular. The pixel shape for white display is desirably a square, but in order to perform full color display, three types of organic EL elements that emit red, green, and blue light must be arranged in each pixel. The partition wall is provided so as to partition the periphery of the pixel electrode.

  In addition to partitioning each pixel, the partition wall, particularly in the wet coating method, prevents the coating liquid from entering the adjacent pixels when it is formed by applying a coating liquid serving as a light emitting medium layer on the anode. It is necessary to. In order to prevent the coating liquid from entering the adjacent pixels, a method is known in which each pixel is defined by a partition wall and the coating liquid is applied in a region defined by the partition wall (Patent Document 3). ).

JP 2001-93668 A JP 2001-155858 A JP 2006-252988 A

  As described in Patent Document 3, a technique is generally used in which a polymer organic EL element is provided with a convex (forward taper) partition wall with a pixel electrode surface at the bottom and a taper on the substrate side. However, when a light emitting medium layer is formed by applying a coating liquid in a pixel region defined by such a forward tapered partition, there is a problem that the film thickness in the pixel region becomes non-uniform. That is, the coating liquid is attracted to the partition wall in the course of drying. As a result, the thickness of the central portion of the pixel region of the formed light emitting medium layer is reduced, and the surface of the light emitting medium layer becomes concave. If the surface becomes concave, the film thickness uniformity in the pixel region is impaired.

  When a current is passed through the organic EL element having such a non-uniform thickness of the light emitting medium layer, only the thin central portion emits light, and the vicinity of the thick partition does not emit light. Therefore, when the film thickness of the light emitting medium layer in the pixel is not uniform, a region emitting light with respect to the pixel region (hereinafter referred to as an aperture ratio) is reduced, and the light emission efficiency is lowered. As the ratio of the non-light emitting region, since the shape of the pixel electrode viewed from the film surface direction is generally rectangular as described above, the non-light emitting region is widely formed in the long side direction of the pixel region.

  Further, when the light emitting medium layer is formed by various printing methods including the nozzle printing method and the relief printing method, the structure of the printing machine is that the plate cylinder or the coating unit on which the printing plate is installed is moved horizontally with respect to the substrate to be printed. Two methods are used: a method of forming a film, or a method of forming a film by fixing a plate cylinder or a coating unit and moving a substrate to be printed. In the production of the organic EL element, it is inevitable to apply the coating liquid to the partition formed in the direction perpendicular to the printing direction. The above-mentioned various printing methods can achieve good printability by keeping the distance between the substrate to be formed and the coating unit (nozzle part or printing plate) constant, but if there are irregularities on the printing surface in the printing direction The printability will deteriorate.

  Therefore, the present invention has been made in view of the above-described problems, and an object thereof is to provide an organic EL element having a high aperture ratio and good printability, a manufacturing method thereof, an image display apparatus, and a manufacturing method thereof. And

  Therefore, the present invention provides an organic EL element that prints at least one layer of a light emitting medium layer in a line pattern, and at least a part of partition walls that partition the first electrode is formed in parallel with the line pattern. The substrate side is composed of a first partition wall having a tapered reverse taper shape and a second partition wall formed perpendicular to the first partition wall and having a taper forward tapered shape on the substrate side.

  In the present invention, “reverse taper” means a structure in which the width of the side surface portion is narrower than the width of the top portion of the partition wall parallel to the substrate horizontal plane, that is, the substrate side is tapered. For example, an example of a reverse taper shape is shown in FIGS. In FIG. 5a, the width at the top of the head is the widest, and the width becomes narrower according to the film thickness direction at the bottom. FIG. 5b shows that the width between the top and bottom film thicknesses is narrower than that of the top. Moreover, you may form a some unevenness | corrugation not only in a part like FIG.

  In the present invention, the “forward taper” means a structure in which the width of the bottom is wider than the width of the top of the partition wall parallel to the substrate horizontal plane, that is, the substrate side is tapered. For example, an example of a forward taper shape is shown in FIGS. In FIG. 5d, the width at the top of the head is the widest, and the width increases in the film thickness direction at the bottom. FIG. 5e shows a forward tapered shape with a curved top. Moreover, even if the top part is a polygon like FIG. 5f, the width | variety of the bottom part should just be expanded.

  In the organic EL element, a substrate, a first electrode formed on the substrate and having a pixel region, a partition formed on the substrate and partitioning the first electrode, and formed on the pixel region A light-emitting medium layer that includes at least a light-emitting layer made of an organic material, and at least one layer is printed in a line pattern, and a second electrode that is formed on the light-emitting medium layer and covers the light-emitting medium layer The partition includes a first partition formed in parallel with the line pattern and having a reverse taper shape at least in part, and a first taper shape formed perpendicular to the first partition. It is preferable to be constituted by two partition walls.

Moreover, it is preferable that the film thickness of the said 1st partition is 0.3 micrometer or more and 5.0 micrometers or less.
The thickness of the second partition wall is preferably 0.1 μm or more and 5.0 μm or less.
Moreover, it is preferable that the height of said 1st partition is higher than the height of said 2nd partition.
Moreover, it is preferable that the film thickness of the said light emitting medium layer is thinner than the total film thickness of said 2nd partition.
Further, it is preferable that the first electrode is a transparent electrode, and the light emitting medium layer is formed between the first electrode and the second electrode.

Further, it is preferable that the second electrode is a transparent electrode, and the light emitting medium layer is formed between the first electrode and the second electrode.
In the image display device, the organic EL element is preferably used as a display element.
In the method for manufacturing an organic EL element, a first electrode is formed on a substrate, a first electrode is formed on the substrate, a partition that partitions the first electrode is formed on the substrate, The pixel region includes at least a light emitting layer made of an organic material, and at least one layer is printed in a line pattern to form a light emitting medium layer, and a second electrode is formed on the light emitting medium layer so as to cover the light emitting medium layer. A method for manufacturing an organic EL element formed by film formation, wherein the diaphragm is parallel to the line pattern and has at least part of a reverse tapered shape in which the substrate side is tapered, and the first partition. It is preferable to form a second partition wall formed in a direction perpendicular to each other and having a forward taper shape with a taper on the substrate side.

  In the manufacturing method of an image display apparatus, it is preferable to form a display element using the manufacturing method of the said organic EL element.

  According to the present invention, the partition wall is formed in parallel with the line pattern of the issue medium layer, the first partition wall having an inversely tapered shape at least partially, and the forward taper formed orthogonal to the first partition wall. By being constituted by the second partition wall having a shape, it becomes possible to manufacture an organic EL element and an image display device having a high aperture ratio and good luminous efficiency.

It is a longitudinal cross-sectional view which shows one Embodiment of the image display apparatus using the organic EL element which concerns on this invention. It is a longitudinal cross-sectional view which shows other embodiment of the image display apparatus using the organic EL element which concerns on this invention. It is explanatory drawing of the organic EL element which concerns on this invention, Comprising: (a) is a longitudinal cross-sectional view which shows the laminated structure of a bottom emission type organic EL element, (b) shows the laminated structure of a top emission type organic EL element. It is a longitudinal cross-sectional view. It is explanatory drawing of the partition of the organic EL element which concerns on this invention, Comprising: (a) is a top view, (b) is bb sectional drawing of (a), (c) is cc sectional drawing of (a). It is. It is explanatory drawing of the partition of the organic EL element which concerns on this invention, Comprising: (a)-(c) is a longitudinal cross-sectional view of a 1st partition, (d)-(f) is a longitudinal cross-sectional view of a 2nd partition. 1 is a schematic configuration diagram of a relief printing apparatus according to the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.
FIG. 1 is a longitudinal sectional view showing an embodiment of an image display device using an organic EL element according to the present invention. This section corresponds to the section aa in FIG.

  A display device 50 using the organic EL element shown in FIG. 1 includes a substrate 11, a first electrode (anode, pixel electrode) 12, a first partition 23A, a second partition 23B, a hole transport layer 14, a light emitting layer 16, a first layer. A two-electrode (cathode) 17, a luminescent medium layer 19 (see FIG. 3 a), and a sealing body 28 are included. The first electrode 12 is provided on the substrate 11 for each pixel. A partition wall 23 including the first partition wall 23 </ b> A and the second partition wall 23 </ b> B partitions the pixels of the first electrode 12. The hole transport layer 14 is formed above the first electrode 12. The light emitting layer 16 is formed on the hole transport layer 14. The second electrode 17 is formed so as to cover the entire surface of the light emitting layer 16. The partition wall 23 includes a first partition wall 23A and a second partition wall 23B. The light emitting medium layer 19 includes a hole transport layer 14 and a light emitting layer 16. The sealing body 28 is in contact with the substrate 11 so as to cover the second electrode 17.

As the sealing body 28, a structure in which an inert gas is sealed in the sealing cap 26 using a sealing cap 26 that covers the organic EL element as shown in FIG. 1 is employed.
FIG. 2 is a longitudinal sectional view showing another embodiment of the image display device using the organic EL element according to the present invention. This section corresponds to the section aa in FIG.
The image display device 51 using the organic EL element shown in FIG. 2 includes an electrode, a light emitting medium layer, and a partition wall, like the image display device 50 shown in FIG. In the display device 51, the resin layer 21 is provided so as to cover the second electrode 17, and the sealing plate 29 is bonded to the substrate 11 via the resin layer 21. In the image display device 51, the resin layer 21 and the sealing plate 29 constitute the sealing body 28.

In FIG. 1 and FIG. 2, a switching element (thin film transistor) for controlling the amount of current flowing through each pixel is connected to the first electrode (not shown).
In the following description, a region where the light emitting medium layer 19 is sandwiched between the first electrode 12 and the second electrode 17 is referred to as a light emitting region or an organic EL element, and the entire array of organic EL elements including the partition walls 23 is displayed. This is called a region.

1 and 2, the luminescent medium layer 19 is a layer sandwiched between a first electrode (anode) 12 and a second electrode (cathode) 17. In the stacked structure shown in FIG. 3, the hole transport layer 14 and the light emitting layer 16 correspond to the light emitting medium layer 19. In addition to this, layers such as a hole injection layer, an electron transport layer, and an electron injection layer may be appropriately added.
For example, in the structure shown in FIG. 1, the luminescent medium layer 19 is configured by two layers of a hole transport layer 14 and a luminescent layer 16 that are sequentially stacked on the transparent electrode (anode) 12. The light emitting medium layer 19 may be constituted by two layers of the light emitting layer 16. Further, the light emitting medium layer 19 may be configured by three layers in which the hole injection layer, the hole transport layer 14 and the light emitting layer 16 are sequentially laminated. One layer may have the function of each of the plurality of layers. For example, in the light emitting medium layer 19, the light emitting layer 16 may have a hole transport function. Moreover, the light-emitting medium layer 19 may be composed of a hole injection layer and an electron transport layer, and may adopt a configuration that emits light at the interface between the hole injection layer and the electron transport layer. If the layer exists between the electrodes and moves a carrier (hole, electron) between the electrodes, this layer corresponds to the light emitting medium layer.

  The film thickness of the light emitting medium layer 19 is 10 nm or more and 1000 nm or less as a whole of the light emitting medium layer regardless of whether it is composed of the light emitting layer 16 single layer or a multilayer structure. When the thickness is less than 10 nm, when the arithmetic average roughness of the surface of the first electrode 12 (hereinafter referred to as surface roughness) is large, the film shape becomes non-uniform and a leak path is formed between the second electrode 17 and a short circuit occurs. It tends to happen. If it exceeds 1000 nm, the light emitting medium layer 19 itself has a high resistance, and it is difficult for current to flow, resulting in a decrease in luminance and light emission efficiency. Considering these facts, the thickness is preferably 50 to 500 nm.

  In the image display device using the organic EL element shown in FIGS. 1 and 2, each patterned electrode is patterned so as to correspond to the emission wavelengths of red (R), green (G), and blue (B). The light emitting layers 16R, 16G, and 16B thus formed are formed. Thus, an image display device capable of full color display is realized. As a structure other than such a display method, a dye conversion method using a blue light emitting layer and a dye conversion layer may be used. Moreover, you may employ | adopt the structure in which the color filter was provided corresponding to each of the some organic EL element which light-emits white.

3a and 3b are cross-sectional views showing a laminated portion of the organic EL element of the present invention, that is, a light emitting region.
FIG. 3 a shows a bottom emission type organic EL device, which shows a structure in which a first electrode 12, a light emitting medium layer 19, and a second electrode 17 are sequentially laminated on a substrate 11. In the structure of the light emitting medium layer 19 in which the first electrode 12, the light emitting medium layer 19, and the second electrode 17 are laminated in this order, in addition to the hole transport layer 14 and the light emitting layer 16, the interlayer 15 or other A light emitting medium layer may be disposed between each layer. The second electrode 17 is a light non-transparent electrode. By using a material having high reflectance such as metal as the material of the second electrode 17, the light emitted toward the second electrode 17 is reflected by the second electrode 17, and the first electrode which is a light transmissive electrode Through 12, emitted light can be emitted to the outside of the organic EL element. For this reason, light extraction efficiency can be improved.

  FIG. 3 b shows a top emission type organic EL device, in which a reflective layer 31, a first electrode 12, a hole transport layer 14, an interlayer 15, a light emitting layer 16, and a second electrode 17 are laminated on the substrate 11 in this order. Has been. In the structure of the light emitting medium layer 19 in which these layers are laminated in this order, other layers may be arranged between a plurality of layers. The second electrode 17 is a light transmissive electrode. The light emitted toward the first electrode 12 is transmitted through the first electrode 12, reflected by the reflective layer, and emitted to the outside of the organic EL element through the second electrode 17. On the other hand, the light emitted toward the second electrode 17 is similarly transmitted through the second electrode and emitted to the outside of the organic EL element.

In the following description, the present invention will be described by taking a bottom emission type organic EL element as an example. However, as a material for the reflective layer 31 and the first electrode 12 and the second electrode 17 which are light transmissive electrodes on the substrate 11. The structure of the present invention can also be applied to a top emission type using a transparent conductive film.
Hereinafter, specific materials and forming methods used in the organic EL element and the image display device according to the present invention will be described.

  The material of the substrate 11 is, for example, glass or quartz, polypropylene, polyethersulfone, polycarbonate, cycloolefin polymer, polyarylate, polyamide, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate, or the like, or top In the case of an emission type organic EL element, in addition to the above plastic film or sheet, metal oxides such as silicon oxide and aluminum oxide, metal fluorides such as aluminum fluoride and magnesium fluoride, silicon nitride A light transmissive substrate in which a single layer or a layer of a polymer resin film such as a metal nitride such as aluminum nitride, a metal oxynitride such as silicon oxynitride, an acrylic resin, an epoxy resin, a silicone resin, or a polyester resin, or aluminum Yasu Metal foil such Nresu, sheet, it is possible to use a plate, aluminum plastic film or sheet, copper, nickel, stainless steel or the like of the metal film non-light-transmitting substrate such as a laminate of. In addition, in this invention, it is not limited to said material, Another material may be used.

  When the display device 50 is a bottom emission type, emitted light generated in the light emitting medium layer 19 is extracted outside the display device 50 through an electrode adjacent to the substrate 11. On the other hand, in the case of the top emission type, the emitted light is extracted to the outside through an electrode facing the substrate 11. In the substrate 11 made of the above material, in order to prevent moisture and oxygen from entering the display device 50, a moisture-proof treatment is performed by a process of forming an inorganic film on the entire surface or one surface of the substrate 11 or a process of applying a resin. Or it is preferable that the hydrophobic process is performed previously. In particular, it is preferable that the moisture content, water vapor transmission rate, and gas transmission coefficient of the substrate 11 are small in order to avoid the intrusion of moisture into the light emitting medium layer 19.

  The first electrode 12 according to the present invention is formed on the substrate 11 and is formed by patterning as necessary. The first electrode 12 is a pixel electrode that is partitioned by a partition wall 23 and corresponds to each pixel (sub-pixel). When the display device 50 is used for a flat panel display or the like, a thin film transistor for controlling light emission by active matrix driving may be formed between the substrate 11 and the first electrode 12, and the thin film transistor and the first electrode 12 may be connected. .

  Examples of the material of the first electrode 12 include metal composite oxides such as ITO (indium tin composite oxide), IZO (indium zinc composite oxide), and AZO (zinc aluminum composite oxide), and metal materials such as gold and platinum. Alternatively, a fine particle dispersion film in which fine particles of these metal oxides or metal materials are dispersed in an epoxy resin or an acrylic resin is used. Further, as the structure of the first electrode 12, a single layer structure or a laminated structure is adopted. Alternatively, the first electrode 12 can be formed by a coating pyrolysis method in which an oxide is formed by thermal decomposition after a precursor such as indium octylate or indium acetone is applied on the substrate.

  When the first electrode 12 is an anode, it is preferable to select a material having a high work function such as ITO so that charge injection can be easily performed due to the characteristics of the organic EL element. In the active matrix driving organic EL display device, the material of the first electrode 12 is preferably a low-resistance material. For example, a material having a sheet resistance of 20Ω · sq or less is suitable as the material of the first electrode 12. It is possible to use. Since the emitted light passes through the first electrode 12 and is emitted from the substrate, the first electrode 12 preferably has a high transmittance. As the transmittance, the reflectance is preferably 70% or more as a total average in the visible light wavelength region, and if it is 80% or more, it can be suitably used as a reflective layer.

  Depending on the material, the first electrode 12 may be formed by a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, a dry coating method such as a sputtering method, an ink jet printing method, or a gravure printing method. An existing film formation method such as a wet coating method such as a screen printing method or a screen printing method can be used. In the present invention, the present invention is not limited to the above method, and other methods may be used. The extraction electrode 12 ′ formed around the substrate 11 and connected to the first electrode 12 can be formed in the same process and with the same material.

As a patterning method for the first electrode 12, an existing patterning method such as a mask vapor deposition method, a photolithography method, a wet etching method, or a dry etching method is used depending on the material or the film forming method. Moreover, you may activate the surface of the 1st electrode 12 using UV processing, a plasma processing, etc. as needed.
In the case of the top emission type, it is preferable to form the reflective layer 31 (see FIG. 3b) below the first electrode 12. As the material of the reflective layer, it is preferable to use a material having high reflectivity, and for example, Cr, Mo, Al, Ag, Ta, Cu, Ti, and Ni are employed. Further, as the structure of the reflective layer, a structure in which a protective film such as SiO, SiO2, or TiO2 is formed on a single film, a laminated film, an alloy film, or a film made of the above-described material is used. As a reflectance, it is preferable that it is 80% or more in the total average of visible light wavelength range, and if it is 90% or more, it can be used suitably as a reflection layer.

  As a method for forming the reflective layer, depending on the material, dry coating methods such as resistance heating vapor deposition, electron beam vapor deposition, reactive vapor deposition, ion plating, and sputtering, or ink jet printing, gravure printing, Existing film forming methods such as a wet coating method such as a screen printing method can be used. In the present invention, the present invention is not limited to the above method, and other methods may be used.

As a patterning method of the reflective layer, an existing patterning method such as a mask vapor deposition method, a photolithography method, a wet etching method, or a dry etching method can be used depending on the material or the film forming method.
As shown in FIG. 4A, the partition wall 23 according to the present invention is composed of two types of partition walls, a first partition wall 23A and a second partition wall 23B. A partition wall 23 is formed so as to partition the light emitting region corresponding to each pixel. The partition wall 23 functions as a partition member that partitions each of the plurality of pixels. When the light emitting medium layer is disposed in each pixel by the wet coating method, since the partition wall 23 is provided as described above, it is possible to prevent color mixing between adjacent pixels. Further, the partition wall 23 is provided with a two-layer structure of a first partition wall 23A having a reverse taper shape and a second partition wall 23B having a forward taper shape, and in the pixel region in the light emitting medium layer formed on the entire display region as will be described later. The film thickness uniformity is improved and the aperture ratio is improved.

  The partition wall 23 is preferably formed so as to cover the end of the first electrode 12. In general, in the active matrix driving organic EL display device 50, the first electrode 12 is formed in each pixel, and the pixel region of the first electrode 12 is exposed in order to enlarge the area of each pixel as much as possible. The area that has been increased. Therefore, the partition wall 23 is formed so as to cover the end portion of the first electrode 12. The most preferable planar shape of the partition wall 23 is a lattice shape. The partition wall 23 is disposed between the pixel electrodes 12 so as to separate the adjacent pixel electrodes 12. Moreover, you may make it function as a protective layer of the thin-film transistor (not shown) connected to the 1st electrode 12 of each pixel.

  Examples of the material constituting the first partition wall 23A include inorganic materials and photosensitive resin materials. Specific examples of the inorganic material for the first partition wall 23A include inorganic oxides such as silicon oxide, tin oxide, aluminum oxide, and titanium oxide, inorganic nitrides such as silicon nitride, titanium nitride, and molybdenum nitride, and silicon nitride oxide. Examples of such materials are inorganic nitride oxides, but are not limited thereto. Of these inorganic materials, silicon nitride, silicon oxide, and titanium oxide are particularly suitable. Further, in order to improve the display quality of the organic EL element, a light-shielding material is included in the above-mentioned inorganic material, or formed on a part or all of the partition walls such as the bottom, top, and side surfaces of the first partition 23A. You may do it.

  Specific examples of the photosensitive resin material include polyimide, acrylic resin, novolac resin, and fluorene materials. A resin in which two or more of these materials are mixed may be used. Either a positive type resist or a negative type resist using these materials is used. In addition, in this invention, it is not limited to said material, Another material may be used. In order to improve the display quality of the organic EL element, a light-shielding material is contained in the photosensitive resin material, or formed on a part or all of the partition walls such as the bottom, top, and side portions of the first partition 23A. May be.

  As a method for forming the first partition wall 23A, a known vacuum film forming method such as a dry coating method represented by a sputtering method, a plasma CVD method, or a resistance heating vapor deposition method is used for an inorganic material, and a spin coater or a bar coater is used for a photosensitive resin material. A known coating method such as a roll coater, a die coater or a gravure coater can be used. When an ink containing an inorganic material is used, after applying the ink, the solvent may be removed by a baking process such as air drying or heat drying to form an inorganic film serving as a base of the partition wall.

  In order to form the inverted taper structure constituting the first partition wall 23A, dry etching methods represented by reactive ion beam etching, reactive gas etching, reactive ion etching and the like can be used for inorganic materials. A photosensitive resin is applied on the inorganic film, exposed and developed to form a pattern, and the etching location is limited using the pattern as a mask. In addition, a wet etching method using a liquid chemical having a property of being dissolved by corrosion can be used. However, a dry etching method in which it is easy to selectively form a side shape by anisotropic etching can be preferably used rather than a wet etching method in which isotropic etching is dominant.

  In the photosensitive resin material, the photosensitive resin material is patterned by an exposure process using a mask, and the exposed photosensitive resin material is developed to form a pattern of the first partition wall 23A. Thus, as a process of forming the pattern of the first partition wall 23A, conventionally known exposure and development methods are used. In the firing step, the first partition wall 23A can be fired using a conventionally known method using an oven, a hot plate, or the like. Although the exposure wavelength varies depending on the type of photosensitive resin material, a negative photosensitive resin material can be suitably used to form an inversely tapered structure.

  The optimum film thickness of the first partition wall 23A varies depending on the type of the partition wall material, the film thickness of the second partition wall, and the film thickness of the light emitting medium layer, but is appropriately 0.3 μm or more and 5.0 μm or less. If the film thickness is less than 0.3 μm, the film thickness may be smaller than that of the light emitting medium layer, the first partition itself is covered, a current that does not contribute to light emission flows, and the light emission efficiency is likely to decrease. When the film thickness exceeds 5.0 μm, the counter electrode of the first electrode is easily disconnected due to the reverse taper shape. As a characteristic of the partition, it is necessary to have an insulating property. If the first barrier rib 23A does not have sufficient insulation, a current flows between the pixel electrodes 12 adjacent to each other through the first barrier rib 23A, resulting in a display defect. Depending on the thickness of the partition wall material, etc., there is a material having conductivity, so that it is preferably 0.5 μm or more and 3.0 μm or less in order to ensure insulation. Furthermore, if it is 1.0 micrometer or more, it can use suitably.

  Photosensitive resin materials and inorganic materials can be used as the material constituting the second partition wall 23B. Specific examples of the photosensitive resin material include polyimide, acrylic resin, novolac resin, and fluorene materials. A resin in which two or more of these materials are mixed may be used. Either a positive type resist or a negative type resist using these materials is used. In addition, in this invention, it is not limited to said material, Another material may be used. In addition, in order to improve the display quality of the organic EL element, a light-shielding material is included in the photosensitive resin material, or formed on a part or all of the partition walls such as the bottom, top, and side portions of the second partition 23B. May be.

  Specific examples of the inorganic material include inorganic oxides such as silicon oxide, tin oxide, aluminum oxide, and titanium oxide, inorganic nitrides such as silicon nitride, titanium nitride, and molybdenum nitride, and inorganic nitride oxides such as silicon nitride oxide. However, the present invention is not limited to these materials. Of these inorganic materials, silicon nitride, silicon oxide, and titanium oxide are particularly suitable. Further, in order to improve the display quality of the organic EL element, a light-shielding material is included in the above-mentioned inorganic material, or formed on a part or all of the partition walls such as the bottom, top, and side portions of the second partition 23B. May be.

  As a material constituting the second partition wall 23B, a forward tapered shape may be formed. As a method for forming the photosensitive resin material, a known coating method such as a spin coater, a bar coater, a roll coater, a die coater, or a gravure coater is used. Next, the photosensitive resin material is patterned by an exposure process using a mask, and the exposed photosensitive resin material is developed to form a pattern of the second partition wall 23B. Thus, conventionally well-known exposure and the development method are used as a process of forming the pattern of the 2nd partition 23B. In the firing step, the second partition wall 23B can be fired using a conventionally known method using an oven, a hot plate, or the like. A positive photosensitive resin material can be easily formed in a forward tapered shape and can be suitably used.

  For inorganic materials, dry etching methods represented by reactive ion beam etching, reactive gas etching, reactive ion etching, and the like can be used. A photosensitive resin material is coated on the inorganic film, exposed and developed to form a pattern, and the etching location is limited using the pattern as a mask. Thus, conventionally known coating methods, known exposure and development methods are used. In addition, a wet etching method using a liquid chemical having a property of being dissolved by corrosion can be used.

  When forming the second partition wall 23B, the first partition wall 23A having a generally reverse tapered shape is formed. When an inorganic material is used, after the film corresponding to the second partition wall is formed, surface polishing up to the top of the first partition wall is necessary. Therefore, the second partition wall forming method using a photosensitive resin material is used. It can be suitably used. In the present invention, the present invention is not limited to the above method, and a reverse-tapered partition may be formed after a forward-tapered partition corresponding to the second partition is formed.

  The optimum film thickness of the second partition wall 23B varies depending on the type of the partition wall material, the film thickness of the second partition wall, and the film thickness of the light emitting medium layer, but is suitably 0.1 μm or more and 5.0 μm or less. When the film thickness is less than 0.1 μm, the film thickness is smaller than that of the light emitting medium layer, the first partition itself is covered in the light emitting medium layer, a current that does not contribute to light emission flows, and the light emission efficiency is likely to decrease. When the film thickness exceeds 5.0 μm, the counter electrode of the second electrode is easily disconnected. As a characteristic of the partition, it is necessary to have an insulating property. When the second partition wall 23B does not have sufficient insulation, a current flows between pixel electrodes adjacent to each other through the first partition wall 23B, resulting in a display defect. Depending on the thickness of the partition wall material, etc., there is a conductive material. Therefore, 0.3 μm or more is necessary to ensure insulation, and 1.5 μm or less is preferable to obtain printability described later.

  The way in which the ink wets and spreads at the ends of the first electrode 12 and the partition wall 23 spreads in the horizontal direction if the angle of the partition wall edge is an obtuse angle with the pixel electrode surface as a horizontal plane, and in the vertical direction if the angle is acute. Since the wetting in the vertical direction is smaller than the wetting in the horizontal direction, the partition wall is made to have an inversely tapered shape, so that the light emitting medium layer formed in the partition wall is prevented from having a concave shape. Although it is possible to increase the aperture ratio by making all the partition walls around the first electrode 12 have the same inverse taper shape as the first partition wall 23A, there is an acute step in the direction orthogonal to the printing direction. The printability is lowered and the amount of coating liquid transferred to the substrate to be printed fluctuates. As a result, uniform light emission cannot be obtained.

  As described above, the printability deteriorates when irregularities are formed on the surface of the substrate to be printed in the printing direction. In particular, in a printing method in which a printing plate, which is a coating unit, and a substrate to be printed are brought close to each other, there is a possibility that the printing plate may be damaged if sharp irregularities exist on the printing surface. Therefore, printability can be ensured by forming a gentle curved surface without forming corners in the partition wall shape arranged in the printing direction. Further, if the second partition wall 23B is thick, the printability is lowered even if there are no sharp irregularities. Therefore, the film thickness of 1.5 μm or less can be preferably used.

  In order to clean the surface of the first electrode used as the anode and adjust the work function after forming the partition wall, UV treatment, plasma treatment, or the like may be performed as a substrate pretreatment step. In order to inject holes into the luminescent medium layer efficiently, it is preferable that the work function of the surface of the anode in contact with the luminescent medium layer is close to the work function of the luminescent medium layer. Therefore, the difference between the work function of the surface of the anode subjected to the surface treatment and the work function of the light emitting medium layer in contact with the anode is preferably 0.5 eV or less, and more preferably 0.2 eV or less. When ITO is used as the first electrode, the work function before the surface treatment is about 4.8 eV. On the other hand, when a hole transport layer or a hole injection layer is formed as a light emitting medium layer on the anode as described later, for example, the work function of molybdenum oxide is about 5.8 eV. Therefore, in the state before the surface treatment, the difference between the work function of the anode and the work function of the hole transport layer is too large, so that the hole injection barrier becomes high and holes are hardly injected. Therefore, the work function of the anode is increased by surface treatment, and the work function of the anode is brought close to the work function of the hole transport layer.

  As a light source for UV treatment, a low-pressure mercury lamp, a high-pressure mercury lamp, an excimer lamp, or the like is used. Any light source may be used in the present invention. When oxygen plasma treatment is used, the work function of the anode can be controlled as desired by adjusting the power, pressure, and plasma irradiation time. When oxygen plasma treatment is used, some etching effects are produced in the partition wall 23 simultaneously with the surface treatment of the anode depending on the material such as the photosensitive resin material. For this reason, in the surface treatment of the anode, it is necessary to adjust the treatment conditions in consideration of the etching effect in the partition wall 23. Since the surface of the surface-treated first electrode returns to its original state due to changes over time, the surface treatment of the anode is preferably performed immediately before the hole transport layer 14 is formed.

  Next, the hole injection layer is a layer having a function of injecting holes from the transparent electrode (anode), and the hole transport layer is a layer having a function of transporting holes to the light emitting layer. These layers may have both a hole injection function and a hole transport function. In this case, the functional layer is referred to by either one name or both names depending on the degree of these functions. In the present invention, a layer called a hole transport layer also includes a hole injection layer.

As a material constituting the hole transport layer, for example, a polymer material such as polyaniline, polythiophene, polyvinyl carbazole, a mixture of poly (3,4-ethylenedioxythiophene) and polystyrenesulfonic acid can be used. The polymer material can be used in a film forming process by a wet coating method. For this reason, it is preferable to use a polymer material when forming the hole injection layer or the hole transport layer. Such a polymer material is dispersed or dissolved in water or a solvent and used as a dispersion or solution. When an inorganic material is used as the hole transport material, Cu ₂ O, Cr ₂ O ₃ , Mn ₂ O ₃ , FeO _x (x ≧ 0.1), NiO, CoO, Bi ₂ O ₃ , SnO ₂ , ThO ₂ , Nb ₂ O ₅ , Pr ₂ O ₃ , Ag ₂ O, MoO ₂ , ZnO, TiO ₂ , V ₂ O ₅ , Nb ₂ O ₅ , Ta ₂ O ₅ , MoO ₃ , WO ₃ , MnO _2, etc. are used. be able to.

In order to efficiently inject holes from the hole transport layer 14 into the light emitting medium layer (for example, an interlayer or a light emitting layer) on the upper layer of the hole transport layer, 14 preferably has a work function equal to or higher than that of the anode (first electrode 12). Although appropriate physical properties of the hole transport layer 14 differ depending on the anode material selected, the hole transport layer 14 having a work function of 4.5 eV or more and 6.5 eV or less can be used. When the anode is ITO or IZO, a hole transport layer 14 having a work function of 5.0 eV or more and 6.0 eV or less can be preferably used. Further, in the bottom emission structure, since the emitted light is extracted through the first electrode 12, the extraction efficiency is lowered when the light transport property of the hole transport layer 14 is low. For this reason, in the visible light wavelength region, the average light transmittance of the hole transport layer 14 is preferably 75% or more, and more preferably 85% or more. In addition, it can be suitably used if the conductivity is 10 ⁻² to 10 ⁻⁶ S / cm.

  As a method for forming the hole transport layer 14, a printing method such as a spin coating method, a die coating method, a dipping method, a slit coating method, a nozzle printing method, or a relief printing method is adopted on the entire display region on the substrate 11. . When the hole transport layer 14 is formed, an ink (liquid material) in which the hole transport material is dissolved in water, an organic solvent, or a mixed solvent thereof is used. As the organic solvent, toluene, xylene, anisole, mesitylene, tetralin, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methanol, ethanol, isopropyl alcohol, ethyl acetate, butyl acetate and the like can be used. In addition, surfactants, antioxidants, viscosity modifiers, ultraviolet absorbers and the like may be added to the ink.

  When the hole transport layer 14 is a low molecular organic material or an inorganic material, it should be formed using a dry process such as a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, or a sputtering method. Can do. When the hole transport layer 14 is formed by a dry process, it can be suitably used by performing surface treatment such as plasma irradiation or UV irradiation as necessary in consideration of wettability to the upper layer.

  In order to improve luminous efficiency, it is preferable to provide an interlayer 15 as an electron blocking layer between the organic light emitting layer 16 and the hole transport layer 14. In the top emission type device structure, the interlayer 15 can be laminated on the hole transport layer 14 after the hole transport layer 14 is formed. Usually, the interlayer 15 is formed so as to cover the hole transport layer 14, but the interlayer 15 may be formed by patterning as necessary.

Examples of the material for the interlayer 15 include polyvinyl carbazole or derivatives thereof, polyarylene derivatives having an aromatic amine in the side chain or main chain, arylamine derivatives, polymers containing aromatic amines, etc. Is mentioned. These materials are low molecular weight organic materials, but these materials may be polymerized to increase the molecular weight. Further, the inorganic _{materials, Cu 2 O, Cr 2 O} 3, Mn 2 O 3, NiO, CoO, Pr 2 O 3, Ag 2 O, MoO 2, ZnO, TiO 2, V 2 O 5, Nb 2 O 5 , Ta ₂ O ₅ , MoO ₃ , WO ₃ , MnO _{2 and} other transition metal oxides and inorganic compounds containing one or more of these nitrides and sulfides. In addition, in this invention, it is not limited to said material, Another material may be used.

  In the case of a polymer organic material, the material of the interlayer 15 is dissolved in a solvent or stably dispersed and used as an interlayer coating liquid. As a solvent for dissolving or dispersing the interlayer material, toluene, xylene, acetone, anisole, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone or the like alone or a mixed solvent thereof may be used. Among them, aromatic organic solvents such as toluene, xylene, and anisole are preferably used from the viewpoint of solubility of the organic interlayer material. Moreover, surfactant, antioxidant, a viscosity modifier, a ultraviolet absorber, etc. may be added to organic interlayer ink as needed.

  As a material for these interlayers, it is preferable to select a material having a work function equal to or higher than that of the hole transport layer 14, and to select a material having a work function equal to or lower than that of the organic light emitting layer 16. More preferred. This is because an unnecessary injection barrier is not formed when carriers are injected from the hole transport layer 14 toward the organic light emitting layer 16. In addition, in order to obtain an effect of confining charges that could not contribute to light emission from the organic light emitting layer 16, it is preferable to employ a material having a band gap of 3.0 eV or more, and by adopting a material having a band gap of 3.5 eV or more. preferable.

As a method for forming the interlayer 15, a printing method such as a spin coating method, a die coating method, a dipping method, a slit coating method, a nozzle printing method, or a relief printing method is employed on the entire display region on the substrate 11. When the interlayer 15 is formed, a coating solution in which the interlayer material is dissolved in water, an organic solvent, or a mixed solvent thereof is used.
When the interlayer 15 is a low molecular organic material or an inorganic material, it can be formed using a dry process such as a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, or a sputtering method. . When the interlayer 15 is formed by a dry process, it can be suitably used by performing surface treatment such as plasma irradiation or UV irradiation as necessary in consideration of wettability to the upper layer.

  In the light emitting layer 16, electrons and holes injected by the voltage applied between the first electrode 12 and the second electrode 17 are recombined, and light emitted during the recombination is obtained. The emitted light passes through the translucent electrode and is emitted to the outside of the organic EL element. When the light emitting layers formed in each of the adjacent pixels are different, for example, in a display device for RGB full color display, each light emitting layer 16R, 16G, 16B is formed by patterning in each pixel region of the first electrode 12. Is done.

  Examples of the material of the light emitting layer 16 include a coumarin-based, perylene-based, pyran-based, anthrone-based, porphyrin-based, quinacdolin-based, N, N′-dialkyl-substituted quinacdolin-based, naphthalimide-based, N, N′-diaryl-substituted pyrrolopyrrole-based materials. A luminescent dye such as polystyrene, polymethyl methacrylate, polyvinyl carbazole or the like dissolved in a polymer can be used. Further, as the material of the light emitting layer 16, a dendrimer material, a high molecular organic material such as PPV, PAF, or polyparaphenylene can be used. The material of the light emitting layer 16 is preferably a material that is soluble in water or a solvent.

  In addition to the polymer materials described above, 9,10-diarylanthracene derivatives, pyrene, coronene, perylene, rubrene, 1,1,4,4-tetraphenylbutadiene, tris (8-quinolato) aluminum complex, tris (4-methyl) -8-quinolate) aluminum complex, bis (8-quinolate) zinc complex, tris (4-methyl-5-trifluoromethyl-8-quinolate) aluminum complex, tris (4-methyl-5-cyano-8-quinolate) Aluminum complex, bis (2-methyl-5-trifluoromethyl-8-quinolinolato) [4- (4-cyanophenyl) phenolate] aluminum complex, bis (2-methyl-5-cyano-8-quinolinolato) [4- (4-Cyanophenyl) phenolate] aluminum complex, tris (8-quino) Norato) scandium complex, bis [8- (para-tosyl) aminoquinoline] zinc complex and cadmium complex, 1,2,3,4-tetraphenylcyclopentadiene, poly-2,5-diheptyloxy-para-phenylene vinylene A low molecular weight light emitting material such as

  These materials for the light emitting layer are dissolved in a solvent or stably dispersed, and used as an organic light emitting coating solution. As the solvent for dissolving or dispersing the organic light-emitting material, toluene, xylene, acetone, anisole, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, or the like alone or a mixed solvent thereof is used. Among them, aromatic organic solvents such as toluene, xylene, and anisole are preferably used from the viewpoint of solubility of the organic light emitting material. Moreover, surfactant, antioxidant, a viscosity modifier, a ultraviolet absorber, etc. may be added to an organic light emitting coating liquid as needed.

  When the material of each light emitting layer 16 is a low molecular weight organic material, the light emitting layer 16 is formed using a dry process such as resistance heating vapor deposition, electron beam vapor deposition, reactive vapor deposition, or ion plating. Is also possible. When the material of each light emitting layer 16 is a material in which a polymer organic material or a low molecular organic material is dispersed in a polymer, a spin coating method, a die coating method, a dipping method, a slit coating method, a nozzle printing method, or a letterpress The light emitting layer 16 can be formed using a printing method such as a printing method.

The electron injection layer is a layer having a function of transporting electrons from the cathode. The electron transport layer is a layer having a function of transporting electrons to the light emitting layer. These layers may have both an electron transport function and an electron injection function. In this case, the functional layer is referred to by either one name or both names depending on the degree of these functions.
Examples of the material constituting such an electron injection layer or electron transport layer include nitro-substituted fluorenes such as 1,2,4-triazole derivatives (TAZ), diphenylxone derivatives, and the like.

  Next, the second electrode (counter electrode) 17 according to the present invention was formed on the light emitting medium layer 19 or the electron injection layer. In the active matrix drive organic EL display device, the second electrode is formed on the entire surface of the display region. As a specific material of the second electrode 17, a single metal such as Mg, Al, Yb or the like is used. Further, a compound such as a metal oxide, fluoride, nitride or the like having a low work function such as Li, Li oxide, LiF or the like is formed on the interface between the second electrode 17 and the light emitting medium layer 19 to have a stability. -You may employ | adopt the structure where Al or Cu with high electroconductivity was laminated | stacked on this compound. Further, in order to achieve both electron injection efficiency and stability, one or more metals such as Li, Mg, Ca, Sr, La, Ce, Er, Eu, Sc, Y, and Yb having a low work function, and stable Ag Alternatively, an alloy system with a metal element such as Al, Cu may be used. Specifically, an alloy such as MgAg, AlLi, or CuLi can be used. In addition, a transparent conductive film made of a metal composite oxide such as ITO (indium tin composite oxide), IZO (indium zinc composite oxide), or AZO (zinc aluminum composite oxide) can be used.

  In the organic EL display device having the top emission structure, the light emitted from the light emitting medium layer 19 passes through the second electrode 17. For this reason, the second electrode 17 needs to have optical transparency in the visible light wavelength region. For this reason, about the film thickness of a transparent conductive film, it is preferable to adjust a film thickness so that an average light transmittance of 80% or more is obtained in a visible light wavelength range. When a single metal such as Mg, Al, or Yb is used as the material for the second electrode 17, the film thickness is preferably 20 nm or less, and more preferably within 2 to 7 nm. Regarding the film thickness in the case of a metal film, it is preferable to adjust the film thickness so as to obtain an average light transmittance of 70% or more in the visible light wavelength region.

  As a method for forming the second electrode 17, it is also possible to use a dry process such as a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, or an ion plating method depending on the material. Alternatively, a printing method such as a spin coating method, a die coating method, a dipping method, a slit coating method, a nozzle printing method, or a relief printing method can be used. In the present invention, the present invention is not limited to the above method, and other methods may be used.

For example, the sealing body 28 is provided on the substrate 11 on which the first electrode 12, the partition wall 23, the light emitting medium layer 19, and the second electrode 17 are formed. Specifically, the sealing body 28 and the substrate 11 are bonded to each other at the peripheral portion of the substrate 11, and the sealing body 28 and the substrate 11 are sealed.
In the organic EL display device having the top emission structure, the light emitted from the light emitting medium layer passes through the sealing body 28 located on the side opposite to the substrate 11 and is taken out of the organic EL display device. For this reason, high light transmittance is required in the visible light wavelength region. It is preferable that an average light transmittance of 85% or more is obtained in the visible light wavelength region.

  A case where a sealing cap 26 such as a glass cap or a metal cap having a recess is used as the structure of the sealing body 28 will be described. In this case, the periphery of the sealing cap 26 and the periphery of the substrate 11 are arranged so that the first electrode 12, the partition wall 23, the light emitting medium layer 19, and the second electrode 17 are disposed in the space inside the sealing cap 26. The space between the sealing cap 26 and the substrate 11 is sealed. The sealing cap 26 and the substrate 11 are bonded using an adhesive. Further, a hygroscopic agent is formed in the recess and filled with an inert gas such as nitrogen gas. Accordingly, it is possible to prevent the deterioration of the organic EL element due to the intrusion of moisture, gas, etc. into the recess.

  Moreover, you may employ | adopt the structure where the sealing board 29 and the resin layer 21 were used as a sealing structure. In this case, a structure in which the resin layer 21 is provided between the substrate 11 on which the first electrode 12, the partition wall 23, the light emitting medium layer 19, and the second electrode 17 are formed and the sealing plate 29 is employed. As a method for forming this structure, there is a method in which the resin layer 21 is formed on the sealing plate 29 and the sealing plate 29 and the substrate 11 are bonded together while the resin layer 21 and the substrate 11 are opposed to each other.

As the material of the sealing body 28, a substrate having low moisture and oxygen permeability is used. Examples of the material include ceramics such as alumina, silicon nitride, and boron nitride, glass such as alkali-free glass and alkali glass, quartz, and moisture resistant film. Examples of moisture-resistant films include films formed by known dry coating methods such as CVD on both surfaces of a plastic substrate, known wet coating methods such as a roll coater method, films with low light transmittance, and water-absorbing properties. A film or a polymer film coated with a water-absorbing agent can be used. The moisture permeability of the moisture resistant film is preferably 1 × 10 ⁻⁶ g / m ² / day or less.

  Examples of the material of the resin layer 21 include a photo-curing adhesive resin made of an epoxy resin, an acrylic resin, a silicone resin, a thermosetting adhesive resin, a two-part curable adhesive resin, and ethylene ethyl acrylate (EEA). Examples thereof include acrylic resins such as polymers, vinyl resins such as ethylene vinyl acetate (EVA), thermoplastic resins such as polyamide and synthetic rubber, and thermoplastic adhesive resins such as acid-modified products of polyethylene and polypropylene. Examples of the method for forming the resin layer 21 on the sealing plate 29 include a solvent solution method, an extrusion lamination method, a melting / hot melt method, a calendar method, a nozzle coating method, a screen printing method, a vacuum laminating method, and a hot roll laminating. The law etc. can be mentioned. If necessary, a material having hygroscopicity or oxygen absorption can be included in the material of the resin layer 21 and formed on the surface. The thickness of the resin layer 21 formed on the sealing plate 29 is arbitrarily determined according to the size and shape of the organic EL element to be sealed, but is preferably about 2 to 500 μm.

  The step of bonding the substrate 11 on which the first electrode 12, the partition wall 23, the luminescent medium layer 19, and the second electrode 17 are bonded to the sealing body 28 is preferably performed in an inert gas atmosphere or in a vacuum. . When a two-layer structure comprising a sealing plate 29 and a resin layer 21 is adopted as the structure of the sealing body 28 and a thermoplastic resin is used as the material of the resin layer 21, the sealing body is used by using a heated roll. It is preferable to pressure-bond 28 to the substrate 11.

On the other hand, when a thermosetting adhesive resin is used as the material of the resin layer 21, it is preferable to perform heat curing at a curing temperature after the sealing body 28 is pressure-bonded to the substrate 11 using a heated roll.
Further, when a photocurable adhesive resin is used as the material of the resin layer 21, after the sealing body 28 is pressure-bonded to the substrate 11 using a roll, the resin is further irradiated by irradiating the photocurable adhesive resin with light. It can be cured. In the above method, the resin layer 21 is formed on the sealing plate 29, but it is also possible to form the resin layer 21 on the substrate 11 and bond the sealing plate 29 and the substrate 11 together.

  For example, a sealing body 28 made of a passivation film may be formed as a pre-process for sealing the organic EL element on the substrate 11 using the sealing plate 29 or instead of the above-described sealing process. . In this case, a passivation film made of an inorganic thin film such as a silicon nitride film, a silicon oxide film, or a silicon nitride oxide film is formed by using a dry process such as a resistance heating vapor deposition method, an electron beam vapor deposition method, or a CVD method. It is also possible to adopt a structure in which the passivation film and the above sealing structure are combined. The thickness of the passivation film is set to, for example, 0.5 μm to 5.0 μm. Although the film thickness suitable for the moisture permeability, water vapor light permeability, etc. of the passivation film is different, a film thickness of 1.0 μm to 3.0 μm is suitable. In the top emission type structure, it is necessary to adjust the film thickness by selecting the material type in the sealing structure in consideration of light transmittance in addition to the above characteristics. In the visible light wavelength region, the total average light transmittance is preferably 70% or more.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
Next, examples of the organic EL display device of the present invention described above will be described. In addition, this invention is not restrict | limited by the following Example. Here, examples of organic EL elements will be described with reference to Example 1 and Comparative Example 1.

[Example 1]
First, a glass substrate (translucent substrate) having a diagonal size of 2.2 inches was prepared. An ITO (indium-tin oxide) thin film was formed on the entire surface of the glass substrate by sputtering. Next, the ITO thin film was patterned using a photolithography method and an etching method using an acid solution. Thereby, pixel electrodes having a plurality of line patterns were formed. In the plurality of line patterns, the line width is 136 μm, and the interval between adjacent lines is 30 μm. On the glass substrate which is about 40 mm square, 192 ITO lines are formed.

Next, the first partition wall 23A was formed as follows. SiN was deposited using the CVD method so that the entire surface of the substrate was deposited. In the CVD method, SiH ₄ , NH ₃ , H ₂ gas having a purity of 99.9999 was used. The substrate in the chamber was heated by a hot plate, and the substrate surface was adjusted to 130 ° C. A film thickness of 1.5 μm was obtained by forming a film at a plasma power of 1.5 kW for 500 seconds. At this time, SiH ₄ , NH ₃ , and H ₂ were supplied at a ratio of 1: 2: 10 so that the degree of vacuum was 150 Pa. Since the formed SiN film was uneven due to the step between the ITO and the substrate surface, the surface was polished and the surface was flattened to 1.3 μm from the substrate surface.

  A body-type photosensitive resist (ZEP520A, manufactured by Nippon Zeon Co., Ltd.) was spin coated on the entire surface of the first partition wall subjected to the planarization treatment. As spin coating conditions, the film was rotated at 4000 rpm for 50 seconds, and then baked on a hot plate at 180 ° C. for 5 minutes to form a thin film. After the resist film was formed, exposure, development, and washing were performed, leaving only portions parallel to the long sides of the pixel electrode pattern, thereby forming a resist pattern.

  After forming the resist pattern, a reverse tapered shape of the first partition is formed by reactive ion etching. The reactive gas used fluorine and oxygen. A mixed gas of fluorine gas and oxygen gas is introduced into the chamber. Each flow rate was adjusted, the fluorine gas flow rate was set to 100 sccm, the oxygen gas flow rate was set to 400 sccm, and the pressure in the chamber was adjusted to 10 Pa. Moreover, high frequency power 700W of 13.56 MHz was applied from the high frequency power supply. The silicon nitride film other than the partition wall was removed by dry etching to form a first partition wall 23A having a reverse taper shape with a taper angle of 150 degrees from the substrate, a top portion of 37 μm, and a bottom portion of 34 μm. After dry etching, the resist was peeled off.

  Next, the second partition wall 23B was formed as follows. A positive photosensitive polyimide (Photo Nice, DL-1000 manufactured by Toray Industries, Inc.) was spin coated on the entire surface of the substrate. As conditions for spin coating, the glass substrate was rotated at 110 rpm for 5 seconds, and then the glass substrate was rotated at 450 rpm for 20 seconds. The film thickness of the positive photosensitive polyimide is 1.5 μm. A photomask that is orthogonal to the first partition wall 23A was prepared, and the photosensitive resin material applied to the entire surface of the substrate by photolithography was exposed to 200 mJ / cm 2 by an i-line stepper. After the exposure, development was performed, and baking was performed at 230 ° C. for 30 minutes using an oven to obtain a second partition wall 23B between the first partition walls 23A. The second partition wall thus formed had a forward taper shape angle of 50 degrees from the top, 21 μm at the top, 30 μm at the bottom, and 1.3 μm in film thickness.

Next, ultraviolet irradiation was performed as a surface treatment of ITO. The glass substrate on which the partition walls were formed was irradiated with ultraviolet rays for 3 minutes using a UV / O ₃ cleaning device. The work function of ITO before ultraviolet irradiation was 4.8 eV. The work function of ITO before ultraviolet irradiation was 5.3 eV.
Next, the hole transport layer 14 was formed. Molybdenum oxide was used as an inorganic material constituting the hole transport layer 14. An inorganic material was deposited to a thickness of 20 nm by sputtering so that the entire display region was deposited. In the sputtering method, argon, which is an inert gas, and oxygen, which is a reactive gas, are supplied into a chamber of a sputtering apparatus using a molybdenum metal target having a purity of 99.9%. In addition, molybdenum oxide was formed on the active matrix substrate 101 by using a reactive DC magnetron sputtering method. The power density of the target is 1.3 W / cm ² . The ratio of the mixed gas supplied into the chamber is 2 for argon and 1 for oxygen. The exhaust valve provided in the chamber was adjusted so that the degree of vacuum during sputtering was 0.3 Pa, and the amount of gas supplied to the chamber was adjusted. The film thickness of molybdenum oxide was controlled by adjusting the sputtering time. In the patterning process, a metal mask having an opening of 33 mm × 33 mm was used.

  Next, a polyphenylene vinylene derivative was employed as the organic light emitting material, and an organic light emitting ink in which this material was dissolved in toluene was prepared so that the concentration of this material was 1%. Using this ink, a light emitting layer was printed using a relief printing method so as to coincide with the direction in which the first partition and the pixel electrode are arranged. The film thickness of the light emitting layer dried after the printing process was 100 nm.

Next, a cathode layer line pattern made of Ca and Al was formed on the light emitting layer. Specifically, the cathode layer was formed by mask vapor deposition using resistance heating vapor deposition so that the line pattern of the cathode layer and the line pattern of the pixel electrode were orthogonal to each other.
Finally, in order to protect from external oxygen or moisture, the organic EL structure formed as described above was hermetically sealed using a glass cap and an adhesive to produce an organic EL display device.

In the periphery of the display area of the organic EL display device thus obtained, an anode-side extraction electrode connected to each pixel electrode and a cathode-side extraction electrode connected to the cathode layer are provided. ing. These extraction electrodes were connected to a power source, the organic EL display element was turned on and displayed, and the lighting state and the display state were confirmed.
When the organic EL element thus obtained was driven, a luminance of 750 cd / cm 2 was obtained at a driving voltage of 7 V, and the luminous efficiency was 12 cd / A. As a result of calculating the aperture ratio from the light emitting area of the image obtained by photographing the light emitting pixels and the designed pixel electrode area, it was 75%.

[Comparative Example 1]
First, as in Example 1, a glass substrate was prepared and a pixel electrode was formed.
Next, in Comparative Example 1, a positive photosensitive polyimide (Photo Nice, DL-1000 manufactured by Toray Industries, Inc.) was spin-coated on the entire surface of the substrate without forming the first tapered partition wall 23A. As conditions for spin coating, the glass substrate was rotated at 110 rpm for 5 seconds, and then the glass substrate was rotated at 450 rpm for 20 seconds. The film thickness of the positive photosensitive polyimide is 1.5 μm. Exposure and development were performed so as to obtain a pattern in which the first partition wall 23A and the second partition wall 23B of Example 1 were combined, and the partition wall 23 was obtained. The partition wall thus formed had a taper angle of 45 degrees with the substrate surface, a top portion of 15 μm, a bottom portion of 35 μm, and a film thickness of 1.3 μm.

Next, as in Example 1, a surface treatment of ITO, a hole transport layer, a light emitting layer, and a cathode layer were formed.
When the organic EL display device thus obtained was driven, a luminance of 500 cd / cm ² was obtained at a driving voltage of 7 V, and the light emission efficiency was 10 cd / A. As a result of calculating the aperture ratio from the light emitting area of the image obtained by photographing the light emitting pixels and the designed pixel electrode area, it was 55%.

Next, with reference to Example 2 and Comparative Example 2, an example of an organic EL display device which is an example of an active matrix driving type organic EL display device will be described.
[Example 2]
First, an active matrix substrate was prepared. In this active matrix substrate, an ITO thin film is formed as a first electrode (pixel electrode), and the ITO thin film is connected to a TFT inside the substrate. The size of the display area is 6 inches diagonal, and the number of pixels is 320 × 240.

  Next, a partition wall was formed so as to cover the end portion of the first electrode provided on the substrate and to partition each of the plurality of pixels. Two layers of a first partition and a second partition were formed in the same manner as in Example 1, and by this partition (first partition, second partition), the number of subpixels was 960 × 240 dots, 0.12 mm × 0. A pixel region having an area of 36 mm was defined. In order to drive the TFT, it is necessary to form an insulating layer on the TFT. However, the partition also functions as the insulating layer of the TFT.

In the same manner as in Example 1, UV / O ₃ cleaning was performed on the active matrix substrate on which the partition walls were formed.
A hole transport layer was formed on the active matrix substrate that had been subjected to UV / O ₃ cleaning in the same manner as in Example 1. The film thickness of molybdenum oxide was 30 nm.
Patterning was performed using a metal mask having an opening of 116 mm × 87 mm so that the entire display region on the active matrix substrate was formed.

Next, a polyvinyl carbazole derivative was employed as an interlayer material, and this material was dissolved in toluene so that the concentration of this material was 0.5%. As a result, an ink serving as an interlayer material was obtained.
Next, the substrate on which the pixel electrodes, the partition walls, and the hole transport layer were formed was set as the printing substrate 602 in the relief printing apparatus 600 shown in FIG.

The relief printing apparatus 600 includes an anilox roll 605, a doctor 606, a relief plate 607 formed of a photosensitive resin, and a plate cylinder 608. An ink layer 609 is applied to the surface of the anilox roll 605.
A pixel electrode surrounded by a partition wall is formed on the substrate to be printed 602, and a hole transport layer is formed on the pixel electrode.

  Using the ink, the interlayer was printed on the hole transport layer using a relief printing method so as to coincide with the direction in which the first partition and the pixel electrode were arranged. In such a relief printing method, 300 lines / inch anilox roll 605 and relief 607 were used. The film thickness of the interlayer after the ink was printed and the ink was dried was 20 nm.

Next, a polyphenylene vinylene derivative was adopted as the organic light emitting material of the organic light emitting layer, and this material was dissolved in toluene so that the concentration of this material was 1%. As a result, an organic light emitting ink as a material for the organic light emitting layer was obtained.
Next, the substrate 101 on which the pixel electrode 102, the partition wall 203, the hole transport layer 104, and the interlayer 105 were formed was set as the printing substrate 602 in the relief printing apparatus 600 shown in FIG.

On the printed substrate 602, an interlayer surrounded by a partition wall is formed.
Using the organic light emitting ink, the organic light emitting layer was printed on the interlayer using a relief printing method so as to match the line pattern of the interlayer 205. In such a relief printing method, an anilox roll 605 of 150 lines / inch and a relief 607 formed of a photosensitive resin were used. The film thickness of the organic light emitting layer after the ink was printed and the ink was dried was 80 nm.

  Next, a calcium film was formed as a second electrode (counter electrode) with a thickness of 5 nm on the organic light emitting layer by using a vacuum deposition method. In the calcium film forming process, a metal mask having an opening of 116 mm × 87 mm was used. Thereafter, an aluminum film was formed to a thickness of 200 nm on the calcium film using a vacuum deposition method. In the aluminum film forming step, a metal mask having an opening of 120 mm × 90 mm was used.

Then, the glass substrate by which the center part was processed into the concave shape was prepared as a sealing body. The sealing body and the active matrix substrate were joined so that the second electrode (cathode) was disposed in the recess of the sealing body. In addition, a hygroscopic agent was installed in the concave portion of the glass substrate (sealing body) in order to prevent deterioration due to the ingress of moisture or oxygen.
When the organic EL display device thus obtained was driven, a luminance of 700 cd / cm ² was obtained at a driving voltage of 7 V, and the light emission efficiency was 11 cd / A. As a result of calculating the aperture ratio from the light emitting area of the image obtained by photographing the light emitting pixels and the designed pixel electrode area, it was 75%.

[Comparative Example 2]
First, as in Example 2, an active matrix substrate was prepared. Next, partition walls were formed in the same manner as in Comparative Example 1. The film formation process and the sealing process of the light emitting medium layer were performed in the same manner as in Example 2.
When the organic EL display device thus obtained was driven, a luminance of 470 cd / cm ² was obtained at a driving voltage of 7 V, and the luminous efficiency was 8 cd / A. As a result of calculating the aperture ratio from the light emitting area of the image obtained by photographing the light emitting pixel and the designed pixel electrode area, it was 50%.

  As described above in detail, the present invention is an organic EL display device that can reduce or suppress leakage current in an organic EL display device in which a predetermined light-emitting medium layer is formed over the entire display area including the partition wall that separates pixels. It is useful for a display device and a manufacturing method thereof. Further, the present invention is useful for an organic EL element, an image display apparatus, and an image display apparatus manufacturing method in which leakage current is reduced and element characteristics are improved.

11 ... Substrate 12 ... First electrode (pixel electrode)
14 ... Hole transport layer / hole injection layer 15 ... interlayer 16 ... light emitting layer 17 ... second electrode (cathode)
DESCRIPTION OF SYMBOLS 19 ... Luminous medium layer 21 ... Resin layer 23 ... Partition 23A ... First partition 23B ... Second partition 26 ... Sealing cap 28 ... Sealing body 29 ... Sealing plate 31 ... reflective layer 50, 51 ... display device (organic EL element)
600 ... letterpress printing apparatus 601 ... stage 602 ... substrate to be printed 603 ... ink tank 604 ... ink chamber 605 ... anilox roll 606 ... doctor 607 ... letterpress 608 ... -Plate cylinder 609 ... Ink layer

Claims (10)

A substrate,
A first electrode formed on the substrate and having a pixel region;
A partition wall formed on the substrate and defining the first electrode;
A light emitting medium layer formed on the pixel region, including a light emitting layer made of at least an organic material, and at least one layer printed in a line pattern;
A second electrode formed on the luminescent medium layer and formed to cover the luminescent medium layer;
With
The partition is
A first partition that is formed in parallel with the line-shaped pattern, and the substrate side has a tapered reverse taper shape at least in part,
A second partition that is formed orthogonal to the first partition, and the substrate side has a tapered forward taper shape;
An organic EL device comprising: The organic EL device according to claim 1,
The thickness of the said 1st partition is 0.3 micrometer or more and 5.0 micrometers or less, The organic EL element characterized by the above-mentioned. The organic EL device according to claim 1,
The organic EL element, wherein the second partition wall has a thickness of 0.1 μm or more and 5.0 μm or less. The organic EL element according to claim 2, wherein
The organic EL element, wherein the height of the first partition is higher than the height of the second partition. The organic EL element according to any one of claims 1 to 4, wherein
The organic EL element, wherein the thickness of the light emitting medium layer is thinner than the total thickness of the second partition walls. The organic EL device according to claim 1,
The first electrode is a transparent electrode,
The organic EL element, wherein the light emitting medium layer is formed between the first electrode and the second electrode. The organic EL device according to claim 1,
The second electrode is a transparent electrode,
The organic EL element, wherein the light emitting medium layer is formed between the first electrode and the second electrode.   An image display apparatus comprising the organic EL element according to claim 1 as a display element. Forming a first electrode on the substrate;
Forming a first electrode on the substrate;
Forming partition walls for partitioning the first electrode on the substrate;
The pixel region includes a light emitting layer made of at least an organic material, and at least one layer is printed in a line pattern to form a light emitting medium layer,
A method for producing an organic EL element, wherein a second electrode is formed on the light emitting medium layer so as to cover the light emitting medium layer,
As the diaphragm,
A first partition wall which is parallel to the line pattern and has a reverse taper shape at least partially tapered on the substrate side;
A second partition that is formed orthogonal to the first partition, and the substrate side has a tapered forward taper shape;
A method for producing an organic EL element, comprising: forming an organic EL element.   A display element is formed using the manufacturing method of the organic EL element of Claim 9, The manufacturing method of the image display apparatus characterized by the above-mentioned.

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