JP2013211227A - Organic el display device and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an organic EL display device in which at least one layer composing the luminescent medium layer of an organic EL element can be formed with uniform thickness when it is formed by printing method.SOLUTION: In the organic EL display device including a substrate 11, a plurality of organic EL elements formed on the substrate 11, first barrier ribs 23A for sectioning a first electrode 12 formed on the substrate 11 out of two electrodes of the organic EL element, and second barrier ribs 23B formed on the first barrier ribs 23A, when forming at least one layer composing a luminescent medium layer 19 of an organic EL element by printing method, the second barrier ribs 23B are formed on the first barrier ribs 23A so that a recess is formed in the top of each second barrier rib 23B, and then at least one layer composing the luminescent medium layer 19 of the organic EL element is formed by printing method.

Description

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

  In recent years, an organic electroluminescent element (hereinafter referred to as an organic EL element), which is a light emitting element capable of high luminance emission by direct current low voltage driving, has been developed. 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 element having such a structure, a structure in which both electrodes are directly disposed on both sides of the organic light emitting layer may be adopted. However, luminance per unit current or luminous flux per unit power (hereinafter referred to as luminous efficiency). In many cases, 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 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 used was 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. It is roughly classified into 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, in such a patterning method, a member such as a metal mask itself increases as the area of the substrate increases due to thermal expansion of the metal mask due to radiant heat caused by heating to sublimate the low-molecular organic light-emitting material. However, it is difficult to obtain a desired patterning accuracy due to the above accuracy.

  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, and inkjet. 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 (see Patent Document 1), a method by letterpress printing (see Patent Document 2), and the like have been proposed.

  When an image display device that needs to pattern a thin film with high definition is manufactured by a wet coating method, an image is displayed by forming a 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 the 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 emit light uniformly, 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.

  When forming a luminescent medium layer by a printing method, it is important to make the layer thickness and layer shape of the luminescent medium layer on each pixel uniform. Since the organic EL element is a current injection type light emitting element as described above, uniform light emission can be obtained when a constant current flows for each pixel. In order to obtain a constant current, it is necessary to make the resistance of the light emitting medium layer sandwiched between the pixel electrode and the counter electrode in the pixel uniform. When a current is passed through an organic EL element having a light emitting medium layer with a non-uniform layer thickness, only the thin central portion emits light, and no light is emitted in the vicinity of the thick partition wall. Therefore, when the layer thickness of the light emitting medium layer in the pixel is not uniform, a region emitting light to the pixel region (hereinafter referred to as an aperture ratio) is reduced, and the light emission efficiency is lowered.

  In this way, studies have been made to make the layer thickness and layer shape of the light emitting medium layer on each pixel uniform. For example, in order to reduce the region where the layer thickness increases as the ink wets on the side wall of the partition wall, a method of making the layer thickness uniform by providing spaces at the four corners of the partition wall (see Patent Document 3) or an organic light emitting medium material A method of controlling the drying state after printing by mixing at least two types of solvents to be dissolved (see Patent Document 4), and a layer thickness non-uniformity caused by the drying speed between the outer peripheral part of the display area and the central part of the display area In order to improve the uniformity, there is a method of printing on the outer peripheral portion (see Patent Document 5).

JP 2001-93668 A JP 2001-155858 A Japanese Patent No. 4815761 Japanese Patent No. 4616596 JP 2002-222695 A

  However, if the area of the display pixel portion is widened by the method described in Patent Document 3, it may be an obstacle to high definition and large size of the organic EL display device. Moreover, in the method as described in Patent Document 4, the type of organic solvent is limited, and it is difficult to apply to various printing methods. Further, in the method described in Patent Document 5, it is difficult to obtain an effective effect in the case of an organic solvent having a high drying speed.

  In actual printing, when printing is performed on a pixel adjacent to a pixel to which the organic light emitting medium layer has been applied once, for example, on the left side of the A line where film formation is performed by a relief printing method as shown in FIG. There are already printed B lines. In this case, even under the condition that a uniform layer thickness can be obtained in the B line, as shown in FIG. 1B, the solvent vapor from the B line causes a non-uniform layer thickness in the A line. These phenomena also occur in a solvent having a high drying rate such as xylene. In all of the various printing methods, the coating liquid cannot be printed unless it is in a wet or half-wet (semi-dry) state at the time of transfer. This is because volatile vapor is generated.

In order to solve the above problem, there is a method of resetting the state of adjacent pixels on the printing line by drying the solvent contained in the light emitting medium layer after each printing after printing one line or a part of each RGB line. Although it is conceivable, it takes time to heat up, heat, and release heat due to the drying process, and it is difficult to apply because it increases tact time and decreases productivity.
In order to prevent the inflow of solvent volatile vapor from adjacent pixels, the present inventors have confirmed that printing can be performed without being affected by the solvent volatile vapor by covering the coated area with a protective mask. In addition, since the film is formed in a state close to room temperature, such as in the air or in a nitrogen atmosphere, it is possible to easily use a thin metal substrate that is difficult to apply because it is distorted by radiant heat in the dry process as a protective mask. It was confirmed that Here, in order to apply the protective mask to a printing method for printing a high-definition pattern such as an image display device, it is necessary to align the pattern of the protective mask by a method different from the dry process.

In order to perform alignment, it is necessary to provide a protective mask and / or a substrate to be printed with a function for facilitating alignment, but the thickness of the protective mask itself has the possibility of contacting printing parts such as a printing plate. In order to make it low, it is necessary to make it as thin as possible, and it is difficult to provide a complicated alignment part.
An object of the present invention is to provide a method for producing an organic EL display device which can be formed with a uniform layer thickness when at least one layer constituting a light emitting medium layer of an organic EL element is formed by a printing method. Another object of the present invention is to provide an organic EL display device capable of suppressing variations in layer thickness in the light emitting medium layer of the organic EL element.

  In order to solve the above problems, the invention of claim 1 is formed on a substrate, a plurality of organic EL elements formed on the substrate, and two electrodes of the organic EL element. An organic EL display comprising: a first partition partitioning the first electrode; and a second partition formed on the first partition, wherein at least one layer constituting the light emitting medium layer of the organic EL element is in a line shape The apparatus is characterized in that a concave portion parallel to the line-shaped layer of the light emitting medium layer is formed at the top of the second partition wall.

A second aspect of the present invention is the organic EL display device according to the first aspect, wherein the height of the first partition is larger than the thickness of the first electrode.
A third aspect of the present invention is the organic EL display device according to the first or second aspect, wherein the height of the first partition is 0.3 μm or more and 5.0 μm or less.
A fourth aspect of the present invention is the organic EL display device according to any one of the first to third aspects, wherein the first partition is made of an inorganic material.

A fifth aspect of the present invention is the organic EL display device according to any one of the first to fourth aspects, wherein the height of the second partition wall is 0.3 μm or more and 5.0 μm or less. To do.
The invention of claim 6 is the organic EL display device according to any one of claims 1 to 5, wherein the line width of the second partition wall is narrower than the line width of the first partition wall. To do.
A seventh aspect of the present invention is the organic EL display device according to any one of the first to sixth aspects, wherein the depth of the concave portion is not less than 0.3 μm and not more than 3.0 μm.

An eighth aspect of the invention is the organic EL display device according to any one of the first to seventh aspects, wherein the concave portion has an arc shape.
A ninth aspect of the invention is the organic EL display device according to any one of the first to eighth aspects, wherein the second partition is made of a photosensitive resin.
A tenth aspect of the invention is the organic EL display device according to any one of the first to ninth aspects, wherein the first electrode is formed of a transparent electrode material.

The invention of claim 11 is the organic EL display device according to any one of claims 1 to 10, wherein the first layer is sandwiched between the two electrodes of the organic EL element with the light emitting medium layer interposed therebetween. The second electrode facing the electrode is formed of a transparent electrode material.
The invention of claim 12 defines a substrate, a plurality of organic EL elements formed on the substrate, and a first electrode formed on the substrate among the two electrodes of the organic EL element. A method of manufacturing an organic EL display device comprising one partition and a second partition formed on the first partition, wherein the second partition is formed such that a recess is formed at the top of the second partition. Is formed on the first partition, and at least one layer constituting the light emitting medium layer of the organic EL element is formed by a printing method.

The invention of claim 13 is the method of manufacturing an organic EL display device according to claim 12, wherein the first partition is formed on the first electrode at a height larger than the thickness of the first electrode. The second partition is formed on the first partition.
The invention of claim 14 is the method of manufacturing an organic EL display device according to claim 12 or 13, wherein the first partition is formed on the first electrode at a height of 0.3 μm or more and 5.0 μm or less. It is characterized by forming.

A fifteenth aspect of the invention is a method of manufacturing an organic EL display device according to any one of the twelfth to fourteenth aspects, wherein the second partition is formed on the first partition by 0.3 μm to 5.0 μm. It is formed with the following height.
The invention of claim 16 is the method of manufacturing an organic EL display device according to any one of claims 12 to 15, wherein the line width of the second partition is made smaller than the line width of the first partition. The second partition is formed on the first partition.

The invention of claim 17 is the method of manufacturing an organic EL display device according to any one of claims 12 to 16, wherein the depth of the recess is 0.3 μm or more and 3.0 μm or less. After the second partition is formed on the first partition, at least one layer constituting the light emitting medium layer of the organic EL element is formed by a printing method.
The invention of claim 18 is the method of manufacturing an organic EL display device according to any one of claims 12 to 17, wherein at least one layer constituting the light emitting medium layer of the organic EL element is formed by a wet film formation method. It is characterized by forming using.

According to invention of Claim 1 and 12, the influence of the solvent volatilization vapor | steam generated when forming at least one layer which comprises the light emission medium layer of an organic EL element by a printing method can be reduced, Thereby, organic EL When at least one layer constituting the light emitting medium layer of the element is formed by a printing method, it can be formed with a uniform layer thickness.
According to invention of Claim 2 and 13, it becomes possible to planarize the surface of a 1st partition, and, thereby, a 2nd partition can be formed easily on a 1st partition.
According to invention of Claim 3 and 14, the leakage current from the adjacent 1st electrode can be suppressed.
According to the invention of claim 4, the surface of the first partition can be easily flattened, whereby the second electrode can be easily formed on the first partition.
According to invention of Claim 5 and 15, the leakage current from the adjacent 1st electrode can be suppressed.

According to invention of Claim 6 and 16, a 2nd electrode can be easily formed on a 1st partition.
According to the seventh and seventeenth aspects, the alignment pattern can be formed without impairing the insulating properties of the second partition. In addition, when at least one layer constituting the light emitting medium layer of the organic EL element is formed by a printing method, it is possible to prevent the solvent volatile vapor from flowing in from adjacent pixels without impairing the insulating properties of the second partition.
According to invention of Claim 8, it can prevent that the alignment convex part of a protective mask contacts the recessed part bottom face of a 2nd partition top, and a 2nd partition is damaged.
According to the invention of claim 9, the second partition can be easily formed on the first partition.

It is a figure for demonstrating the problem in the case of forming the light emitting medium layer of an organic EL element by the relief printing method. It is a figure which shows the cross section of the organic electroluminescence display which concerns on the 1st Embodiment of this invention. It is a figure which shows the cross section of the organic electroluminescence display which concerns on the 2nd Embodiment of this invention. It is a figure which shows typically the cross section of the organic EL element formed on the board | substrate of an organic EL display apparatus. It is a figure which shows the example of the recessed part formed in the top part of a 2nd partition. It is a figure for demonstrating the protective mask used when forming the 2nd partition of an organic electroluminescence display. It is a figure which shows schematic structure of the relief printing apparatus used when implementing this 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. 2 is a view showing a cross section of the organic EL display device according to the first embodiment of the present invention. An organic EL display device 50 shown in FIG. 2 includes a substrate 11 and a plurality of organic EL elements formed on the substrate 11, and these organic EL elements are formed on the substrate 11. An electrode (anode, pixel electrode) 12, a light emitting medium layer 19 formed on the first electrode 12, and a second electrode 17 facing the first electrode 12 with the light emitting medium layer 19 interposed therebetween It is configured to include.
The organic EL display device 50 also includes a partition wall 23 that partitions the first electrode 12 of the organic EL element. The partition wall 23 is formed on the first partition wall 23A formed on the substrate 11 and the first partition wall 23A. It consists of the formed 2nd partition 23B.

Further, the organic EL display device 50 includes a sealing body 28 that seals the organic EL element. The sealing body 28 is disposed on the substrate 11 so as to cover the partition wall 23.
The light emitting medium layer 19 of the organic EL element has a hole transport layer 14, and the hole transport layer 14 is formed on the first electrode 12. The light emitting medium layer 19 has a light emitting layer 16, and the light emitting layer 16 is formed on the hole transport layer 14.
The second electrode 17 of the organic EL element is formed on the light emitting medium layer 19 so as to cover the entire surface of the light emitting layer 16.
As the sealing body 28 of the organic EL display device 50, 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 is employed. A plate-like sealing plate similar to the substrate 1 may be used.

  Next, FIG. 3 shows a cross section of an organic EL display device according to the second embodiment of the present invention. An organic EL display device 51 shown in FIG. 3 includes a substrate 11 and a plurality of organic EL elements formed on the substrate 11, and these organic EL elements are formed on the substrate 11. The electrode 12 includes a light emitting medium layer 19 formed on the first electrode 12, and a second electrode 17 facing the first electrode 12 with the light emitting medium layer 19 interposed therebetween. .

The organic EL display device 51 includes a partition wall 23 that partitions the first electrode 12 of the organic EL element. The partition wall 23 is formed on the first partition wall 23A and the first partition wall 23A formed on the substrate 11. The second partition wall 23B. The organic EL display device 51 further includes a sealing body 28 that seals the organic EL element. The sealing body 28 includes a resin layer 21 formed on the second electrode 17 and a top surface of the resin layer 21. And a sealing plate 29 adhered to the substrate.
When the substrate 11 of the organic EL display devices 50 and 51 has a switching element (thin film transistor) for controlling the amount of current flowing through each pixel, the first electrode 12 is connected to the thin film transistor.

In the following description, a region where the light emitting medium layer 19 is formed 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.
The light emitting medium layer 19 of the organic EL element may include a hole injection layer, an electron transport layer, an electron injection layer, and the like in addition to the hole transport layer 14 and the light emitting layer 16. For example, in the organic EL display device 50 shown in FIG. 2, the hole transport layer 14 having the light emitting medium layer 19 formed on the first electrode 12, and the light emitting layer 16 formed on the hole transport layer 14. However, the luminescent medium layer 19 may be constituted by two layers of the hole injection layer and the luminescent layer 16.

Further, the light emitting medium layer 19 may be constituted by three layers in which the hole injection layer, the hole transport layer 14 and the light emitting layer 16 are sequentially laminated, or one layer has the function of each of the plurality of layers. You may do it. For example, 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. Further, in the present invention, at least one of the light emitting medium layers is formed by a relief printing method using a relief plate having line-shaped convex portions, so that at least one layer of the light emitting medium layer is formed in a line shape parallel to the printing direction. Has been.

  The layer 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 the light emitting medium layer 19 is composed of the light emitting layer 16 or a multilayer structure. When the thickness is less than 10 nm, when the arithmetic average roughness (hereinafter referred to as surface roughness) of the surface of the first electrode 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. When it exceeds 1000 nm, the light emitting medium layer 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 organic EL display devices 50 and 51 shown in FIGS. 2 and 3, the emission wavelengths of red (R), green (G), and blue (B) are increased for each electrode on which the light emitting layer 16 of the light emitting medium layer 19 is patterned. The light emitting layers 16R, 16G, and 16B are patterned so as to correspond to each other. 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.

FIG. 4 is a diagram schematically showing a cross section of the organic EL element formed on the substrate 11 of the organic EL display devices 50 and 51. FIG. 4A shows a case where the organic EL element is a bottom emission type. FIG. 4B shows a case where the organic EL element is a top emission type.
When the organic EL element formed on the substrate 11 is a bottom emission type, the first electrode 12 is a transparent electrode for taking out the light generated in the light emitting layer 16 of the light emitting medium layer 19 from the first electrode side. Formed from material. In this case, when the second electrode 17 is formed of an electrode material having a high reflectance such as a metal, light emitted toward the second electrode 17 is reflected by the second electrode 17. Since the light reflected by the second electrode 17 is transmitted through the light emitting layer 16, the interlayer 15, the hole transport layer 14, and the first electrode 12 and then emitted from the substrate 11, the light extraction efficiency is improved. Can do.

  When the organic EL element formed on the substrate 11 is a top emission type, the second electrode 17 is a transparent electrode for taking out the light generated in the light emitting layer 16 of the light emitting medium layer 19 from the second electrode side. Formed from material. In this case, when the reflective layer 31 is provided between the substrate 11 and the first electrode 12, the light generated in the light emitting layer 16 is reflected by the reflective layer 31 even if it passes through the first electrode 12. Can be efficiently extracted from the second electrode side.

Next, substrate materials and organic EL element materials used for the organic EL display devices 50 and 51 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 organic EL display device is a bottom emission type, the emitted light generated in the light emitting medium layer 19 is emitted to the outside of the organic EL display device through an electrode (first electrode 12) adjacent to the substrate 11. On the other hand, in the case of the top emission type, emitted light is emitted to the outside of the organic EL display device through an electrode (second electrode 17) facing the substrate 11. In the substrate 11 made of the above material, in order to prevent moisture and oxygen from entering the organic EL display device, 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, etc. It is preferable that moisture-proofing treatment or hydrophobic treatment is performed in advance. 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 is formed on the substrate 11 and is formed by patterning as necessary. The first electrode 12 is partitioned by the first partition wall 23A, and is a pixel electrode corresponding to each pixel (sub pixel). When an organic EL display device is used for a flat panel display or the like, a thin film transistor for controlling light emission is formed between the substrate 11 and the first electrode 12 by active matrix driving, and the first electrode 12 is connected to the thin film transistor. May be.

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. 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.
As the structure of the first electrode 12, a single layer structure or a laminated structure is adopted. The first electrode 12 can also 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 to the surface of the substrate 11.

  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.

When the organic EL display device is a bottom emission type, the light generated in the light emitting layer 16 is transmitted through the first electrode 12 and is emitted from the substrate 11, so that the first electrode 12 preferably has a high transmittance. The transmittance of the first electrode 12 is preferably 70% or more as a total average in the visible light wavelength region, and can be suitably used if it is 80% or more.
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. Among these, by using a printing method in particular, it is possible to form the extraction electrode 12 ′ (see FIGS. 2 and 3) electrically connected to the first electrode 12 in the same process. In the present invention, the present invention is not limited to the above method, and other methods may be used.

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.
When the organic EL display device is a top emission type, it is preferable to form the reflective layer 31 below the first electrode 12. As the material of the reflective layer 31, it is preferable to use a material with high reflectivity, and for example, Cr, Mo, Al, Ag, TA, Cu, Ti, and Ni are employed.

As the structure of the reflective layer 31, a structure in which a protective film such as SiO, SiO ₂ , TiO ₂ or the like is formed on a single film, a laminated film, an alloy film, or a film made of the above materials is used. . In addition, the reflectance of the reflective layer 31 is preferably 80% or more in terms of the total average in the visible light wavelength region, and can be suitably used if it is 90% or more.
Depending on the material, the reflective layer 31 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 forming method 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 for the reflective layer 31, 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 FIGS. 2 and 3, the partition wall 23 includes two types of partition walls, a first partition wall 23 </ b> A and a second partition wall 23 </ b> B. The first partition wall 23A is formed on the surface of the substrate 11 so as to partition a light emitting region corresponding to each pixel of the organic EL display device, and functions as a partition member that partitions each pixel of the organic EL display device. When the light emitting medium layer 19 is disposed in each pixel by the wet coating method, the partition wall 23 is provided as described above, so that it is possible to prevent color mixing between adjacent pixels.

  The partition wall 23 is preferably formed so as to cover the end of the first electrode 12. In general, in an active matrix driving organic EL display device, a first electrode 12 is formed in each pixel, and a pixel region of the first electrode 12 is exposed in order to enlarge the area of each pixel as much as possible. The area is 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 so as to divide adjacent pixel electrodes (first 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 photosensitive resin material include polyimide, acrylic resin, novolak resin, and fluorene materials. When the first partition wall 23A is formed of these materials, the first partition wall 23A may be formed from two or more types of photosensitive resins, and the type of photosensitive resin may be either a positive resist or a negative resist. . Further, in order to improve the display quality of the organic EL element, a material having a light-shielding property may be included in the photosensitive resin material to form a part or all of the bottom, top, side surface, etc. of the first partition wall 23A. good. In addition, in this invention, it is not limited to said material, Another material may be used.

  When the first partition wall 23A is formed of an inorganic material, the inorganic material includes inorganic oxides such as silicon oxide, tin oxide, aluminum oxide, and titanium oxide, inorganic nitrides such as silicon nitride, titanium nitride, and molybdenum nitride, Examples thereof include materials such as inorganic nitride oxides such as silicon nitride oxide. Among these inorganic materials, silicon nitride, silicon oxide, and titanium oxide are particularly suitable, but are not limited thereto. In addition, in order to improve the display quality of the organic EL element, a material having a light-shielding property may be included in the inorganic material to form a part or all of the bottom, top, side surface, etc. of the first partition wall 23A. good.

An optimum material for the first partition wall 23A is an inorganic material. This is because in the step of forming the second partition wall 23B on the first partition wall 23A, if the top of the first partition wall 23A is flat, the shape of the second partition wall 23B is stabilized.
When an inorganic material is used as the partition wall material of the first partition wall 23A, the surface of the substrate 11 is inorganic using a known vacuum film formation method such as a dry coating method typified by a sputtering method, a plasma CVD method, and a resistance heating vapor deposition method. A first partition wall 23A made of a material can be formed.

When a photosensitive resin material is used as the partition wall material of the first partition wall 23A, a photosensitive resin material is applied to the surface of the substrate 11 using a known coating method such as a spin coater, bar coater, roll coater, die coater, or gravure coater. Material can be applied.
When an ink containing an inorganic material is used as the partition wall material of the first partition wall 23A, after applying the ink, the solvent is removed by a firing process such as air drying and heat drying, and the inorganic film serving as the matrix of the partition wall Also good.

  As a method of patterning the first partition wall 23A, when the first partition wall 23A is formed of an inorganic material, a dry etching method represented by reactive ion beam etching, reactive gas etching, reactive ion etching, or the like is used. Can do. A photosensitive resin 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. A wet etching method using a liquid chemical having a corrosion-dissolving property can also be used, but the side surface shape is selectively formed by anisotropic etching rather than the wet etching method in which isotropic etching is dominant. An easy-to-use dry etching method can be preferably used.

  In the photosensitive resin material, the photosensitive resin material is patterned by an exposure process using a mask. 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.

  If the height of the first partition wall 23 </ b> A is less than 0.3 μm, the first partition wall itself may be covered with the light emitting medium layer 19 because it is thinner than the layer thickness of the light emitting medium layer 19. As a result, a current that does not contribute to light emission flows through the first partition wall 23A, and the light emission efficiency is likely to decrease. Further, when the height of the first partition wall 23A exceeds 5.0 μm, the second electrode 17 is likely to be disconnected. Accordingly, the height of the first partition wall 23A varies depending on the type of the partition wall material, the height of the second partition wall 23B, and the layer thickness of the light emitting medium layer 19, but is appropriately 0.3 μm or more and 5.0 μm or less.

  One of the characteristics required for the first partition wall 23A is that it has an insulating property. If the first partition wall 23A does not have sufficient insulation, a current flows between the first electrodes (pixel electrodes) 12 adjacent to each other through the first partition wall 23A, causing display defects. In order to ensure insulation between them, the height of the first partition wall 23A is preferably 0.5 μm or more and 3.0 μm or less, and more preferably 1.0 μm or more and 3.0 μm or less.

  Examples of the material constituting the second partition wall 23B include a photosensitive resin material and an inorganic material. 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. Materials. Among these inorganic materials, silicon nitride, silicon oxide, and titanium oxide are particularly suitable, but are not limited thereto. Further, in order to improve the display quality of the organic EL element, a material having a light-shielding property may be included in the inorganic material, and a part or all of the bottom, top, side surface, etc. of the second partition wall 23B may be formed. good.

  As the photosensitive resin material, polyimide, acrylic resin, novolac resin, fluorene, or the like can be used as the second partition material. When the second partition wall 23B is formed of these materials, the second partition wall 23B may be formed from two or more types of photosensitive resin, and the type of the photosensitive resin may be either a positive resist or a negative resist. . Further, in order to improve the display quality of the organic EL element, a material having a light-shielding property may be included in the photosensitive resin material to form a part or all of the bottom, top, side surface, etc. of the second partition wall 23B. good.

The shape of the second partition wall 23B is preferably a forward tapered shape. After the light emitting medium layer 19 is formed, a second electrode 17 that is a counter electrode is formed over the entire light emitting region. Although depending on the angle of the reverse taper shape, as the taper angle becomes obtuse, there is a higher possibility of disconnection unless the thickness of the counter electrode is increased and the thickness of the counter electrode is increased.
When a photosensitive resin material is used as the partition wall material of the second partition wall 23B, a photosensitive resin is formed on the first partition wall 23A by using a known coating method such as a spin coater, bar coater, roll coater, die coater, gravure coater or the like. Material can be applied. After applying the photosensitive resin material on the first partition wall 23A by these methods, the photosensitive resin material is patterned by an exposure process using a mask, and the exposed photosensitive resin material is developed. And the 2nd partition 23B which consists of photosensitive resin materials can be formed on the 1st partition 23A by baking the photosensitive resin material using the conventionally well-known method using oven, a hotplate, etc. . A positive photosensitive resin material can be easily formed in a forward tapered shape and can be suitably used.

  When an inorganic material is used as the partition wall material of the second partition wall 23B, an inorganic film is formed on the first partition wall 23A using a dry etching method typified by reactive ion beam etching, reactive gas etching, reactive ion etching, or the like. Can be formed. Then, after applying a photosensitive resin on the inorganic film, exposure and development are performed to pattern the photosensitive resin, and the inorganic film is etched using the patterned photosensitive resin as a mask to be made of an inorganic material. The second partition wall 23B can be formed on the first partition wall 23A. In this case, a wet etching method using a liquid chemical having a property of corrosive dissolution can be used. In addition, as the 2nd partition 23B, it is possible to use suitably the photosensitive resin material which is easy to form a forward taper shape.

  In order to form the top of the second partition wall 23B in a concave shape as shown in FIGS. 2 and 3, when a photosensitive resin material is used, a multi-tone such as a halftone mask or a gray tone mask is used if it is a positive resist. It is possible to form a concave shape by using the mask and setting the middle of the region sandwiched between the exposed portions to be the top as the intermediate exposed portions. Further, it is possible to form the top of the second partition wall 23B in a concave shape by using two of the normal partition pattern mask and the concave pattern mask. With respect to the negative resist, the top of the second partition wall 23B can be formed in a concave shape in the same process as the positive resist, and when an inorganic material is used, it can be formed by general dry etching. is there.

  FIG. 5 shows a cross-sectional view of the second partition wall 23B formed on the first partition wall 23A, and the second partition wall 23B has a recess 32 as shown in FIG. The recess 32 is formed on the top of the second partition wall 23B in order to facilitate alignment of the protective mask. Further, since the protective mask has a line-shaped opening having the same shape as the light emitting medium layer line, the recess 32 for aligning the protective mask is formed on the second partition wall 23B in a line shape parallel to the line of the light emitting medium layer. Is done. The line of the concave portion 32 may be a continuous concave shape, or the concave shape may be discontinuously arranged in a line.

As the shape of the recess 32, an arc shape (FIG. 5A) that can be formed using a multi-tone mask or a two-layer mask, or a triangle that can be formed using dry etching or the like. Examples of the shape and the quadrangular shape (FIGS. 5B and 5C) include an arc-shaped concave portion 32 with less interference with the alignment portion of the protective mask.
If the height of the second partition wall 23B is less than 0.1 μm, the thickness of the light emitting medium layer 19 becomes thinner, and the second partition wall itself may be covered with the light emitting medium layer 19. As a result, a current that does not contribute to light emission flows through the second partition wall 23B, and the light emission efficiency is likely to decrease. Further, when the height of the second partition wall 23B exceeds 5.0 μm, the second electrode 17 is likely to be disconnected. Accordingly, the height of the second partition wall 23B varies depending on the type of the partition wall material, the layer thickness of the light emitting medium layer 19, and the like, but is suitably 0.1 μm or more and 5.0 μm or less.

  One of the characteristics required for the second partition wall 23B is that it has an insulating property. When the second partition wall 23B does not have sufficient insulation, a current flows between the first electrodes (pixel electrodes) 12 adjacent to each other through the first partition wall 23A, causing display failure. In order to ensure insulation between them, the height of the second partition wall 23B is preferably 0.5 μm or more and 5.0 μm or less, and more preferably 1.0 μm or more and 5.0 μm or less.

The depth of the recess 32 varies depending on the type of the partition wall material and the thickness of the second partition wall, but is desirably 0.3 μm or more and 3.0 μm or less. In particular, since it is necessary to align with the alignment site provided on the protective mask, 0.3 μm or more is preferable, and a depth of 0.5 μm or more is more preferable. Further, if the depth of the concave portion 32 is too large, the insulating properties necessary for the partition wall cannot be secured, so that the depth is preferably 3.0 μm or less, and more preferably 2.0 μm or less.
The optimum width of the recess 32 can be suitably used as long as it is 50% or less of the line width of the second partition wall 23B. Here, the “line width” is the short side width of the partition wall portion perpendicular to the line parallel to the printing direction in the second partition wall 23B.

  In order to clean the surface of the first electrode used as an anode and adjust the work function after the partition wall 23 is formed, UV treatment, plasma treatment, or the like may be performed as a pretreatment step of the substrate 11. In order to inject holes into the luminescent medium layer 19 efficiently, the work function of the surface of the anode (first electrode 12) in contact with the luminescent medium layer 19 and the work function of the luminescent medium layer 19 should be close. preferable. 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 12, 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, depending on the material such as the photosensitive resin material, the etching effect on the partition wall 23 is considered in the surface treatment of the anode because some etching effect is generated in the partition wall 23 simultaneously with the surface treatment of the anode. It is necessary to adjust the processing conditions. 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.

  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 , FeOx (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. Can do.

In order to efficiently inject holes from the hole transport layer 14 into the upper light-emitting medium layer 19 (for example, the interlayer 15 or the light-emitting layer 16), the hole transport layer 14 has a physical property value of It is preferable to have 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 material. 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 light emitting layer materials 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.

  The second electrode (counter electrode) 17 is 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 17 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. Also, 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, YB, etc., which have 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, since the light generated in the light emitting medium layer 19 passes through the second electrode 17, the second electrode 17 needs to have light transmittance 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 of 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 19 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 peripheral portion of the sealing cap 26 and the peripheral portion 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. And the space between the sealing cap 26 and the substrate 11 is sealed. The sealing cap 26 and the substrate 11 are bonded with an adhesive. The inside of the sealing cap 26 is filled with an inert gas such as a hygroscopic agent or 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 sealing cap.

  Moreover, you may employ | adopt the structure where the flat sealing plate 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.

  A protective mask that can be suitably used in the present invention will be described. As a characteristic required for the protective mask, it is required that the change rate of the base material due to elongation or swelling in a room temperature environment such as in the air or in a nitrogen atmosphere is small. Therefore, as a material having a low coefficient of thermal expansion and a low coefficient of thermal expansion, an inorganic material substrate such as glass or a metal substrate such as stainless steel or invar can be raised. Since the convex part used as the alignment site | part for making it contact with the partition on the organic EL element board | substrate with which the concave part was provided as an alignment pattern was formed in these base-material surfaces, a metal base material can be used most suitably. .

  FIG. 6 shows the processing method and shape of a protective mask using a metal substrate. There is a wet etching method as a general processing method of a metal substrate. A protective mask 33 as shown in FIG. 6 (A) can be manufactured by processing once from the upper surface of the substrate and twice from the lower surface by wet etching. A protective mask 34 by electroforming as shown in FIG. 6B is also applicable.

  When the organic EL display device 50 shown in FIG. 2 is manufactured, first, the first electrode 12 of the organic EL element is formed on the surface of the substrate 11 by the known method described above. Next, after the first partition wall 23A is formed on the surface of the substrate 11 on which the first electrode 12 is not formed, the second partition wall 23B is formed by the above-described method so that the concave portion 32 is formed on the top of the second partition wall 23B. It is formed on the first partition wall 23A.

  If the second partition wall 23B is formed on the first partition wall 23A, the hole transport layer 14 and the interlayer 15 are sequentially formed on the surface of the first electrode 12 by sputtering or the like, and then the light emitting layer 16 is formed on the interlayer. For example, a relief printing apparatus 700 shown in FIG. Thereafter, after the second electrode 17 is formed on the light emitting layer 16, the surface of the substrate 11 on which the organic EL element is formed is sealed with a sealing body 28, whereby an organic EL having a structure as shown in FIG. A display device is obtained.

  In the case of manufacturing the organic EL display device 51 shown in FIG. 3, first, the reflective layer 31 is formed on the surface of the substrate 11 by the known method described above, and the first electrode 12 is formed on the reflective layer 31. . Next, after the first partition wall 23A is formed on the surface of the substrate 11 on which the first electrode 12 is not formed, the second partition wall 23B is formed by the above-described method so that the concave portion 32 is formed on the top of the second partition wall 23B. It is formed on the first partition wall 23A.

  If the second partition wall 23B is formed on the first partition wall 23A, the hole transport layer 14 and the interlayer 15 are sequentially formed on the surface of the first electrode 12 by sputtering or the like, and then the light emitting layer 16 is formed on the interlayer. For example, a relief printing apparatus 700 shown in FIG. Thereafter, the second electrode 17 is formed on the light emitting layer 16, and then the surface of the substrate 11 on which the organic EL element is formed is sealed with a sealing body 28, whereby an organic EL having a structure as shown in FIG. A display device is obtained.

Thus, when forming at least one layer (for example, the light emitting layer 16) which comprises the light emitting medium layer 19 of an organic EL element by a printing method, the 2nd partition 23B so that the recessed part 32 may be formed in the top part of the 2nd partition 23B. Is formed on the first partition wall 23A, and then the protective mask is installed so that the concave portion of the second partition wall 23B and the alignment part of the protection mask are aligned, and the light emitting layer 16 and the like are formed by the printing method. Inflow of the solvent volatile vapor is suppressed by the protective mask. Thereby, the influence by inflow of the solvent volatile vapor | steam can be reduced, Therefore When forming at least one layer which comprises the light emitting medium layer of an organic EL element by a printing method, it can form with uniform layer thickness.
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. 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. Thus, a pixel electrode (first electrode 12) having a plurality of line patterns was 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 positive photosensitive resist (manufactured by Zeon Corporation, ZEP520A) was spin-coated on the entire surface of the partition wall on the planarized first partition wall 23A. As spin coating conditions, the film was rotated at 4000 min ⁻¹ for 50 seconds, and then baked at 180 ° C. for 5 minutes using a hot plate to form a thin film. After the resist film was formed, the resist pattern was formed by performing exposure, development, and washing, leaving only the portion parallel to the long side of the pixel electrode 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 is adjusted, the flow rate of fluorine gas is 100 sccm (600 × 10 ⁻³ m ³ / h), the flow rate of oxygen gas is 400 sccm (400 × 10 ⁻³ m ³ / h), and the pressure in the chamber is 10 Pa. Adjustments were made to 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 tapered partition wall 23A. 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 min ⁻¹ for 5 seconds, and then the glass substrate was rotated at 900 min ⁻¹ for 20 seconds. The film thickness of the positive photosensitive polyimide is 1.5 μm. As a photomask, a halftone mask provided with an intermediate exposure portion of 3 μm at the center portion of the second partition wall 23B with a line width of 17 μm is prepared, and a photosensitive resin material applied to the entire surface of the substrate by photolithography is used as an i-line. The substrate was exposed to 200 mJ / cm ² using a 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 top concave shape after the development (concave portion 32) was an arc shape, and had a width of 3.5 μm and a depth of 1.5 μm.

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 / O3 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 11 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%. In the printing plate, a plate on which 96 line patterns that are half of the entire ITO pattern were formed was used. A substrate to be printed 702 was set in the relief printing apparatus 700 shown in FIG. The relief printing apparatus 700 includes an anilox roll 705, a doctor 706, a relief plate 707 formed of a photosensitive resin, and a plate cylinder 708. An ink layer 709 is applied to the surface of the anilox roll 705. A pixel electrode surrounded by a partition is formed on the substrate 702 to be printed, and a hole transport layer is formed on the pixel electrode. Using the ink and the printing plate, the interlayer 15 is formed on the hole transport layer using the relief printing method so as to coincide with the direction in which the first partition and the pixel electrode are arranged. Printed.

  In such a relief printing method, an anilox roll of 300 lines / inch and a printing plate were used. When printing 96 lines of the unprinted part, a protective mask made by processing a 100 μm thick stainless steel substrate by wet etching is placed so as to match the concave shape alignment pattern on the top of the second partition wall, and then 2 lines Eye printed. As for the thickness of the light emitting layer dried after the printing process, the minimum thickness was 100 nm for both the first line and the second line.

Next, a line pattern of a cathode layer (second electrode 17) made of CA and Al was formed on the light emitting layer 16. Specifically, the cathode layer was formed by mask vapor deposition using resistance heating vapor deposition so that the line pattern of the cathode layer (second electrode 17) and the line pattern of the pixel electrode (first electrode 12) 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 all the lines of the organic EL element thus obtained were 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. When the anode-side extraction electrode is selected and light is emitted only for the first printing (first line), 380 cd / cm ² with a driving voltage of 7 V, and when light is emitted only for the ^second printing (second line), 7 V is driven. Luminescence of 370 cd / cm ² was obtained at a voltage.

[Comparative Example 1]
First, a glass substrate was prepared in the same manner as in Example 1, and a pixel electrode, a partition, a surface treatment of ITO, and a hole transport layer were formed. Next, in Comparative Example 1, printing was performed without installing a protective mask during the second printing (second line). The printing conditions and drying conditions are the same as in Example 1. As for the thickness of the light emitting layer dried after the printing process, the minimum film thickness of the first line was 100 nm, but the minimum film thickness of the second line was 80 nm.

When all the lines of the organic EL element thus obtained were driven, a luminance of 630 cd / cm 2 was obtained at a driving voltage of 7 V, and the luminous efficiency was 10 cd / A. When the anode-side extraction electrode is selected and light is emitted only for the first printing (first line), 380 cd / cm ² with a driving voltage of 7 V, and when light is emitted only for the ^second printing (second line), 7 V is driven. The light emission was 250 cd / cm ^{2 at} a voltage. When the light emission state of the second line was confirmed, the light emission part was biased to one side and the light emission region was narrowed.

  The present invention is useful for a method for manufacturing an organic EL display device in which at least one layer constituting a light emitting medium layer of an organic EL element is formed by a printing method.

DESCRIPTION OF SYMBOLS 11 ... Board | substrate 12 ... 1st electrode 14 ... Hole transport layer 15 ... Interlayer 16 ... Light emitting layer 17 ... 2nd electrode 19 ... Light emitting medium layer 21 ... Resin layer 23 ... Partition 23A ... 1st partition 23B ... 2nd partition 26 DESCRIPTION OF SYMBOLS ... Sealing cap 28 ... Sealing body 29 ... Sealing plate 31 ... Reflective layer 32 ... Concave 33 ... Protection mask 34 ... Protection mask 50, 51 ... Organic EL display device 700 ... Letterpress printing device 702 ... Printed substrate 705 ... Anilox Roll 706 ... Doctor 707 ... Letterpress 708 ... Plate cylinder 709 ... Ink layer

Claims (18)

  A substrate, a plurality of organic EL elements formed on the substrate, a first partition partitioning a first electrode formed on the substrate out of two electrodes of the organic EL element, and the first And an organic EL display device in which at least one layer constituting the light emitting medium layer of the organic EL element is in a line shape, and the light emitting medium is formed on the top of the second partition. An organic EL display device, wherein a concave portion parallel to the line-shaped layer is formed.   The organic EL display device according to claim 1, wherein the height of the first partition is larger than the thickness of the first electrode.   The organic EL display device according to claim 1, wherein a height of the first partition wall is 0.3 μm or more and 5.0 μm or less.   The organic EL display device according to claim 1, wherein the first partition is made of an inorganic material.   The organic EL display device according to claim 1, wherein a height of the second partition wall is 0.3 μm or more and 5.0 μm or less.   6. The organic EL display device according to claim 1, wherein a line width of the second partition wall is narrower than a line width of the first partition wall.   7. The organic EL display device according to claim 1, wherein a depth of the concave portion is not less than 0.3 μm and not more than 3.0 μm.   The organic EL display device according to claim 1, wherein the concave portion has an arc shape.   The organic EL display device according to claim 1, wherein the second partition is made of a photosensitive resin.   The organic EL display device according to claim 1, wherein the first electrode is made of a transparent electrode material.   The second electrode facing the first electrode with the luminescent medium layer interposed between the two electrodes of the organic EL element is formed of a transparent electrode material. The organic EL display device according to any one of the above.   A substrate, a plurality of organic EL elements formed on the substrate, a first partition partitioning a first electrode formed on the substrate out of two electrodes of the organic EL element, and the first A method of manufacturing an organic EL display device comprising a second partition formed on a partition, wherein the second partition is placed on the first partition so that a recess is formed at the top of the second partition. Then, at least one layer constituting the light emitting medium layer of the organic EL element is formed by a printing method.   13. The method according to claim 12, wherein the second partition is formed on the first partition after the first partition is formed on the first electrode at a height greater than the thickness of the first electrode. The manufacturing method of the organic electroluminescence display of description.   14. The method of manufacturing an organic EL display device according to claim 12, wherein the first partition is formed on the first electrode at a height of 0.3 μm or more and 5.0 μm or less.   15. The organic EL display device according to claim 12, wherein the second partition wall is formed on the first partition wall with a height of 0.3 μm or more and 5.0 μm or less. Method.   The line width of the second partition is made smaller than the line width of the first partition, and the second partition is formed on the first partition. Manufacturing method of organic EL display device.   After the second partition is formed on the first partition so that the depth of the recess is 0.3 μm or more and 3.0 μm or less, at least one layer constituting the light emitting medium layer of the organic EL element is printed. The method of manufacturing an organic EL display device according to claim 12, wherein the organic EL display device is formed by:   18. The method for manufacturing an organic EL display device according to claim 12, wherein at least one layer constituting the light emitting medium layer of the organic EL element is formed by a wet film forming method.

Images