JP2011113654A - Organic el element and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL (Electro Luminescence) element achieving homogenization of an organic light emitting medium layer to enable highly uniform display free from uneven emission and luminance reduction. <P>SOLUTION: In formation of the organic light emitting medium layer by printing, the printing is performed at a desired temperature obtained by applying a voltage to a heating wiring 2 of a printed circuit board 15. As a result, drying of ink immediately after printing is accelerated to suppress flowing of the ink. Thus, a meniscus form can be controlled and height difference among printed films can be reduced. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing an organic EL element capable of forming a high-definition pattern by printing an ink dissolved in a solvent on a substrate to be printed, and an organic EL element produced by the production method.

  2. Description of the Related Art In recent years, organic EL elements having features such as thinness, low power, and high luminance display have attracted attention as display elements in mobile phones, PDAs (personal digital assistants), mobile personal computers, in-vehicle navigation systems, and the like. In this organic EL element, for example, an anode (transparent conductive film, ITO film), a light emitting layer containing an organic light emitter, and a cathode (metal electrode) are laminated on a transparent substrate.

  The light emitting layer of the organic EL element is usually formed by vacuum vapor deposition of a low molecular organic light emitter. In this case, there is a limit to increasing the size of the element due to limitations on the equipment of the vapor deposition apparatus. Therefore, an attempt has been proposed to form a light emitting layer by a known printing method by dissolving a polymer organic light emitter in a solvent and dispersing it into an ink (see, for example, Patent Document 1). This printing method is excellent in mass productivity and can reduce the manufacturing cost. Patent Document 1 includes offset printing, gravure printing, and the like as specific printing methods.

Patent Document 2 discloses a technique for forming a light emitting layer using flexographic printing.
Flexographic printing is a printing method using a flexible relief printing plate made of rubber or resin, an inking roll called a anilox roll with engraved fine recesses on the surface, and solvent-drying ink. Widely used for printing simple prints. This flexographic printing is particularly suitable for forming a thin and stable printing layer having a film thickness of about 0.01 to 0.2 μm.

Further, in flexographic printing, the relief printing portion to which printing pressure is applied is flexible, and printing can be performed at a very low printing pressure called kiss touch. Therefore, it is also suitable for printing on a glass substrate or a substrate on which a transparent electrode or the like whose characteristics are destroyed by applying a high pressure is formed. That is, it is a printing method particularly suitable for forming a light emitting layer of an organic EL element.
And in the ink supply apparatus of the printing machine which prints the light emitting layer of the organic EL element of patent document 2, in order to suppress volatilization of an ink solvent, ink supply is performed by a closed system, and the ink of the anilox roll surface is carried out. In order to prevent drying, it is necessary to always wet the surface of the anilox roll by rotating the lower peripheral surface of the anilox roll while being immersed in the ink reservoir of the ink fountain. For this purpose, the ink is supplied to an ink fountain with a closed structure called a closed chamber, rotated while immersing the lower peripheral surface of the anilox roll therein, and on the upper peripheral surface of the anilox roll exposed from the closed chamber, A method of scraping excess ink with a doctor and applying the ink onto the flexographic plate has been used.

Further, in order to keep the ink density in the closed chamber constant, a system is provided in which a circulation mechanism for periodically supplying new ink and collecting old ink is used.
JP 2001-185352 A JP 2005-59348 A

  However, since the ink film formed by flexographic printing has a meniscus shape in the vicinity of the bank, there has been a problem that the flatness of the printed film is poor. This is because the flexographic printing method that forms organic EL requires a certain amount of ink fluidity, but it is drawn to the bank by the flow of ink immediately after transfer to the substrate to be printed, and the bank area is thickened. Is considered to be the cause.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to form a high-definition print pattern in which light is emitted uniformly within the pixels.

In order to solve the above-described problems, the invention described in claim 1 of the present invention is a method for manufacturing an organic EL element in which a pixel electrode and a counter electrode are stacked on a substrate via an organic light emitting medium layer. And
A first step of laminating a heating wiring and a pixel electrode in this order on a substrate and forming an insulating layer defining a light emitting region on the pixel electrode, and forming the organic light emitting medium layer on the pixel electrode A second step of forming the organic light-emitting medium layer by printing an ink in which a material is dissolved or dispersed in a solvent by a relief printing method, and the printing increases the temperature by applying a voltage to the heating wiring. It is characterized in that it is carried out in a state where

  Here, the process of applying a voltage to the heating wiring may be performed before printing, for example. In short, it is sufficient that printing can be performed in a state where the pixel electrode is heated to a predetermined temperature via the heating wiring by applying a voltage to the heating wiring.

Next, the invention described in claim 2 is the structure described in claim 1, wherein the organic light emitting medium layer includes at least two layers of a hole transport layer and an organic light emitting layer,
The second step includes a first printing step in which printing is performed using a hole transport material, and a second printing step in which printing is performed using an organic light emitting material as a material constituting the organic light emitting medium layer. And a voltage is applied to the heating wiring when printing using at least the organic light emitting material.

Next, the invention described in claim 3 is characterized in that, with respect to the configuration described in claim 1 or claim 2, the temperature of the heating wiring during the printing is set to 30 to 230 ° C. It is.
Next, the invention described in claim 4 is a method for manufacturing an organic EL element in which a pixel electrode and a counter electrode are stacked on a substrate via an organic light emitting medium layer,
An insulating layer that defines a light emitting region is formed on the pixel electrode stacked on the substrate, and then the material constituting the organic light emitting medium layer is dissolved or dispersed in the solvent while the pixel electrode is heated on the pixel electrode. The organic light-emitting medium layer is formed by printing the prepared ink by a relief printing method.

Next, the invention described in claim 5 includes at least a pixel electrode, a counter electrode disposed opposite to the pixel electrode, a hole transport layer and an organic light emitting layer interposed between the pixel electrode and the counter electrode. In an organic EL device that emits light from an organic light emitting layer by passing a current from the both electrodes to the organic light emitting layer,
It was manufactured by the manufacturing method of any one of Claims 1-4.

  Next, an invention described in claim 6 is an organic EL element in which a pixel electrode and a counter electrode are stacked on a substrate via an organic light emitting medium layer, and the pixel electrode is opposite to the counter electrode. The heating wiring is arranged with the insulating layer interposed therebetween.

According to the present invention, since the ink film is formed on the pixel electrode heated by the heating wiring, drying of the ink can be promoted and ink flow can be suppressed. As a result, the meniscus shape can be suppressed and the height difference of the printed film can be reduced.
That is, the film thickness of each organic light emitting medium layer of the manufactured organic EL element is made uniform, and it becomes possible to obtain a high-definition print pattern that emits light uniformly in the pixels.

It is sectional drawing which shows the structure of the organic EL element which concerns on embodiment based on this invention. It is the schematic which shows the whole structure of the flexographic printing machine suitable as a printing machine for organic EL based on embodiment based on this invention. It is the schematic which shows the operation | movement at the time of the ink transfer of the printing machine in this embodiment. It is an evaluation result of the display state of the display of an organic EL element.

Embodiments of the present invention will be described below with reference to the drawings.
(About the structure and manufacturing outline of organic EL elements)
FIG. 1 is a cross-sectional view showing the structure of the organic EL element in the present embodiment.
In the following embodiment, an example applied to a passive matrix type organic EL element will be described. Here, the passive matrix system is a system in which stripe-shaped electrodes are opposed to each other so as to be orthogonal to each other and light is emitted from the intersection. On the other hand, the active matrix method is a method of emitting light independently for each pixel by using a so-called thin film transistor (TFT) substrate in which a transistor is formed for each pixel. The present invention may be applied to the manufacture of an active matrix organic EL element.

As shown in FIG. 1, the organic EL element of this embodiment includes a substrate 1 and a heating wiring 2, a transparent insulating layer 3, a pixel electrode 4, an organic light emitting medium layer 70, and a cathode layer 8 constituting a counter electrode. Configured. As a result, the organic EL element has a configuration in which the pixel electrode 4 and the counter electrode are stacked via the organic light emitting medium layer 70. Reference numeral 9 denotes a glass cap.
The manufacture of the organic EL element includes a first step and a second step.

  In the first step, the heating wiring 2 and the pixel electrode 4 are laminated in this order on the substrate 1, and an insulating layer 5 that defines a light emitting region is formed on the pixel electrode 4. That is, in the first step, the patterned line-shaped heating wiring 2 is formed on the substrate 1, and the transparent insulating layer 3 is formed over the entire substrate. Further, a patterned line-shaped pixel electrode 4 is formed on the transparent insulating layer 3 so as to be positioned immediately above the heating wiring 2, and an insulating layer 5 is further formed between adjacent pixel electrodes. .

  In the second step, the organic light emitting medium layer 70 is formed on the pixel electrode 4 by printing an ink obtained by dissolving or dispersing the material constituting the organic light emitting medium layer 70 in a solvent by a relief printing method. Printing in the second step is performed in a state where the voltage is applied to the heating wiring 2 previously laminated to raise the temperature. The application of the voltage is adjusted so that the temperature of the heating wiring 2 becomes a desired temperature in the range of 30 to 230 ° C. Since the temperature of the heating wiring 2 is substantially equivalent to the temperature of the pixel electrode 4, the temperature of the pixel electrode 4 may be adjusted to a desired temperature in the range of 30 to 230 ° C. The process of applying a voltage to the heating wiring 2 may be performed immediately before printing. In short, the temperature at the time of printing should just be the temperature of the range of 30-230 degreeC.

Here, when the temperature is less than 30 ° C., the effect of suppressing the meniscus shape and reducing the height difference of the printed film is low. Moreover, since it will have a bad influence with respect to the organic light emitting medium layer 70 etc. which will be formed when it exceeds 230 degreeC, 230 degreeC was made into the upper limit.
The organic light emitting medium layer 70 includes at least two layers of a hole transport layer 6 and an organic light emitting layer 7. The second step includes a first printing step in which printing is performed using a hole transport material, and a second printing in which printing is performed using an organic light emitting material as a material constituting the organic light emitting medium layer 70. Process. That is, after forming the hole transport layer 6 in the first printing step, the organic light emitting layer 7 is formed in the second printing step. Note that printing in a state where the temperature is raised by applying a voltage to the heating wiring 2 is performed at least in the second printing step.

The above-described printing is performed by, for example, a flexographic printing machine which is a later-described organic EL printing machine. However, the printing press for organic EL that performs letterpress printing applicable to the present invention is not limited to the printing press of the embodiment described later.
Furthermore, each material, formation method, and others of the organic EL element will be described in detail.

About the board
As the substrate 1, a glass substrate or a plastic film or sheet can be used. If a plastic film is used, a polymer EL element can be produced by winding, and a display panel can be provided at a low cost. In addition, as the plastic in that case, for example, polyethylene terephthalate, polypropylene, cycloolefin polymer, polyamide, polyethersulfone, polymethyl methacrylate, polycarbonate, or the like can be used. Further, these films are barrier layers made of metal oxide such as silicon oxide showing water vapor barrier property and oxygen barrier property, oxynitride such as silicon nitride, polyvinylidene chloride, polyvinyl chloride, saponified ethylene-vinyl acetate copolymer. Is provided as necessary.

  Here, when the organic EL element is a bottom emission type organic EL element that extracts light from the substrate side, it is necessary to use a transparent substrate 1, but the top that extracts light from the opposite side of the substrate 1 is used. In the case of the emission method, the substrate 1 does not need to have translucency.

About heating wiring
A patterned heating wire 2 is provided on the substrate 1. As a material for the heating wiring 2, a transparent electrode material such as ITO (indium tin composite oxide), IZO (indium zinc composite oxide), tin oxide, zinc oxide, indium oxide, aluminum oxide composite oxide, or the like can be used. The material for the heating wiring 2 is required to have high resistance, solvent resistance, and transparency. That is, it is preferable that the heating wiring 2 has a higher resistance than the pixel electrode 2.

For example, when ITO is used as the material of the heating wiring 2, it is formed on the substrate 1 by the sputtering method and patterned by the photolithography method to form the line-shaped heating wiring 2.
In the case of the active matrix method, the pixel region for forming the light emitting medium layer is divided into rectangles. In this case, the heating wiring 2 may be formed in a line along one side.

"Transparent insulation layer"
After the line-shaped heating wiring 2 is formed, the transparent insulating layer 3 is formed over the entire region excluding the sealing region and the extraction electrode region by a photolithography method using a photosensitive material having transparency.

“About pixel electrodes”
A pixel electrode 4 patterned as an anode is provided on the film-like transparent insulating layer 3. As the material of the pixel electrode 4, transparent electrode materials such as ITO (indium tin composite oxide), IZO (indium zinc composite oxide), tin oxide, zinc oxide, indium oxide, and aluminum oxide composite oxide can be used. In addition, as a material of the transparent insulating layer 3, ITO is preferable because of its low resistance, solvent resistance, and transparency. When ITO is employed, the line-shaped pixel electrode 4 is formed on the substrate 1 by sputtering and patterned by photolithography.

“Insulation layer”
After the line-shaped pixel electrode 4 is formed, an insulating layer 5 is formed by photolithography using a photosensitive material between adjacent pixel electrodes. By providing the insulating layer 5 between the adjacent pixel electrodes, it is possible to suppress the spread of the ink printed on each pixel electrode 4 and to prevent color mixing due to the ink flowing into the adjacent pixels when a display is formed.

The insulating layer 5 in the present embodiment desirably has a thickness in the range of 0.5 μm to 5.0 μm. If the insulating layer 5 is too low, ink spreading cannot be prevented and ink flows into adjacent pixels, resulting in color mixing. From this point of view, the lower limit value of the thickness of the insulating layer 5 is defined as 0.5 μm.
On the other hand, for example, in a passive matrix type organic EL element, when the insulating layer 5 is provided between the pixel electrodes 4, the cathode layer 8 is formed orthogonal to the insulating layer 5. When the cathode layer 8 is formed so as to straddle the insulating layer in this way, if the insulating layer 5 is too high, the cathode layer 8 may be disconnected, resulting in a display failure. And it was confirmed by experiment that the disconnection of the cathode easily occurs when the height of the insulating layer 5 exceeds 5.0 μm. From this viewpoint, the upper limit of the thickness of the insulating layer 5 was set to 5.0 μm as described above.

  The photosensitive material for forming the insulating layer 5 may be either a positive resist or a negative resist, and may be a commercially available one, but it must have insulating properties. If the partition does not have sufficient insulation, a current flows to the adjacent pixel electrode 4 through the partition and a display defect occurs. Specific examples of the photosensitive material for forming the insulating layer 5 include, but are not limited to, polyimide-based, acrylic resin-based, novolac resin-based, and fluorene-based materials. Further, for the purpose of improving the display quality of the organic EL element, a light shielding material may be included in the photosensitive material.

  The photosensitive resin forming the insulating layer 5 is applied using a coating method such as a spin coater, bar coater, roll coater, die coater, or gravure coater, and is patterned by a photolithography method. Alternatively, the insulating layer 5 may be formed by using a gravure offset printing method, a reverse printing method, a flexographic printing method, or the like without using a photosensitive resin.

About the hole transport layer
After forming the insulating layer 5 as described above, the hole transport layer 6 is formed by relief printing. Examples of the hole transport material forming the hole transport layer 6 include polyaniline derivatives, polythiophene derivatives, polyvinylcarbazole (PVK) derivatives, poly (3,4-ethylenedioxythiophene) (PEDOT), and the like. These materials are dissolved or dispersed in a solvent to form a hole transport material ink, which is formed using a slit method. The volume resistivity of the formed hole transport layer 6 is preferably 1 × 10 ⁶ Ω · cm or less from the viewpoint of luminous efficiency.

  Solvents for dissolving or dispersing the hole transport material include, for example, toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methanol, ethanol, isopropanol, ethylene glycol, propylene glycol, polyethylene glycol, glycerin, ethyl acetate, acetic acid. Butyl, isopropyl acetate, methyl cellosolve, ethyl cellosolve, methyl cellosolve, ethyl cellosolve, butyl cellosolve, ethyl lactate, ethylene glycol diethyl ether, 1-propanol, methoxypropanol, ethoxypropanol, water alone or a mixed solvent thereof Can be mentioned. Moreover, surfactant, antioxidant, a viscosity modifier, a ultraviolet absorber, etc. may be added as needed.

  The viscosity of the hole transport layer ink is preferably 5 to 200 mPa · s. This is because, in the relief printing method used in this embodiment, the ink is first transferred from the anilox to the relief plate, but at a viscosity of 200 mPa · s or more, the ink is transferred from the anilox to the relief plate, and then sufficient on the relief plate. Ink does not level and causes unevenness. In addition, when the pressure is 5 mPa · s or less, the mottling unevenness is likely to occur in the pixel, causing the unevenness.

  The solid content concentration of the hole transport layer ink is preferably 0.5 to 7.0%. This is because, in the hole transport ink used in the present embodiment, when the concentration is 7.0% or more, the stability of the ink is deteriorated, which causes ink aggregation and unevenness of the hole transport layer 6.

About the organic light-emitting layer
Next, after forming the hole transport layer 6 as described above, the organic light emitting layer 7 is formed by letterpress printing. The organic light emitting layer 7 is a layer that emits light by passing an electric current. The organic light emitting material forming the organic light emitting layer 7 is, for example, a coumarin type, a perylene type, a pyran type, an anthrone type, a porphyrene type, a quinacridone type, N, N'-dialkyl-substituted quinacridone-based, naphthalimide-based, N, N'-diaryl-substituted pyrrolopyrrole-based, iridium complex-based luminescent dyes dispersed in polymers such as polystyrene, polymethyl methacrylate, polyvinyl carbazole, etc. And polyarylene-based, polyarylene vinylene-based, and polyfluorene-based polymer materials.

  These organic light emitting materials are dissolved or stably dispersed in a solvent to obtain an organic light emitting ink. Examples of the solvent for dissolving or dispersing the organic light-emitting material include toluene, xylene, acetone, anisole, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, or a mixed solvent thereof. Among these, aromatic organic solvents such as toluene, xylene, and anisole are preferable 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 organic luminescent ink as needed.

As described above, the relief printing method is used to form the organic light emitting layer 7. In this case, a resin letterpress suitable for organic light-emitting inks can be used, and among them, a water development type photosensitive resin letterpress is preferred.
As a method for forming the organic light emitting layer 7, in printing according to the present embodiment, a voltage is applied to the heating wiring 2 of the substrate to be printed by a DC power supply device, and the temperature of the heating wiring 2 is within a range of 30 to 230 ° C. To the desired temperature. At this time, the surface temperature of the heating wiring 2 is monitored with a thermocouple to control the voltage. The temperature monitoring may be performed on the surface of the pixel electrode 4, and the relationship between the voltage value and the application time and the above temperature is obtained in advance through experiments or the like, and the voltage and time to be applied while estimating the temperature based on the relationship. May be adjusted.

"Cathode layer (counter electrode)"
Next, after forming the organic light emitting layer 7 as described above, the cathode layer 8 is formed in a line pattern orthogonal to the line pattern of the pixel electrode 4. As the material of the cathode layer 8, materials corresponding to the light emission characteristics of the organic light emitting layer 7 can be used. For example, simple metals such as lithium, magnesium, calcium, ytterbium and aluminum, and stable metals such as gold and silver can be used. And alloys thereof. Alternatively, a conductive oxide such as indium, zinc, or tin can be used. Examples of the method for forming the cathode layer 8 include a method for forming by a vacuum evaporation method using a mask.

"Other"
Here, in the organic EL element of the present embodiment described above, the hole transport layer 6 and the organic light emitting layer 7 are laminated from the anode layer side (pixel electrode 4 side) between the pixel electrode 4 and the cathode layer 8 which are anodes. Although it is a structure, it has a laminated structure in which a layer such as a hole blocking layer, an electron transporting layer, and an electron injecting layer is selected as necessary in addition to the hole transporting layer 6 and the organic light emitting layer 7 between the anode layer and the cathode layer 8. be able to. In addition, when forming these layers, the forming method of the present invention can be used. That is, it is formed by printing by letterpress printing. In that case, it is preferable to print in the state which applied the voltage to the heating wiring 2 and heated.

Finally, these organic EL components are hermetically sealed using a glass cap 9 and an adhesive in order to protect them from external oxygen and moisture. Thus, an organic EL element can be obtained. In addition, when the board | substrate 1 has flexibility, you may seal using a sealing agent and a flexible film.
(Operational effect of this embodiment)
When an organic EL element is manufactured as described above, an ink film is formed on the pixel electrode 4 in a state heated by the heating wiring 2, so that drying of the ink can be promoted and ink flow can be suppressed. As a result, the meniscus shape can be suppressed and the height difference of the printed film can be reduced.

For example, by applying the above manufacturing method, the hole transport layer 6 is prevented from being thickened at the edge where the insulating layer 5 and the pixel electrode 4 are in contact with each other, and the uniformity in which unevenness of light emission and luminance reduction are eliminated. It becomes possible to manufacture an organic EL element capable of providing a good display.
That is, the thickness of each organic light emitting medium layer 70 of the manufactured organic EL element is made uniform, and it becomes possible to obtain a high-definition print pattern that emits light uniformly in the pixels.

Here, it is conceivable to apply the voltage directly to the pixel electrode 4 to perform the above heating, but from the following viewpoint, the heating wiring 2 is provided and heating is performed as described above.
That is, in order to heat to a desired temperature, it is necessary to use a material having a certain high resistance. However, since the pixel electrode 4 is a low resistance material, it is not suitable for heating. Conversely, if a high current is directly applied to the low-resistance pixel electrode 4 for heating, there is a possibility of adversely affecting the light emitting medium layer. The heating wiring 2 and the pixel region 4 are insulated by the transparent insulating layer 3.

  Moreover, since it heats with the wiring 2 for a heating, without heating the whole board | substrate, it can heat only just under an organic light emitting layer. Thus, there is an effect that deformation of the substrate due to heating can be minimized.

(About organic EL printers)
Next, a flexographic printing machine suitable for light-emitting layer printing of an organic EL element, which is an organic EL printing machine used when carrying out the above relief printing, will be described.

FIG. 2 is a schematic diagram showing the overall configuration of the flexographic printing machine. FIG. 3 is a schematic diagram showing the operation of the printing press during ink transfer.
As shown in FIGS. 2 and 3, the flexographic printing machine according to the embodiment is a rotary plate cylinder 11 that is rotatably supported at a fixed position, and a light emitting pattern forming unit that is mounted on the peripheral surface of the plate cylinder 11. A relief plate (flexo printing plate) 12, a support base 13 positioned below and located horizontally below the plate cylinder 11, and a rotation axis 11a of the plate cylinder 11 on the support base 13 via a guide 13a perpendicular to the rotation axis 11a. A surface plate 14 movably installed in the horizontal direction, a printing substrate 15 placed on the surface plate 14, an ink supply means 16 for supplying ink for the light emitting layer to the surface of the relief plate 12, And an ink replenishing means 17 for periodically supplying ink to the ink supplying means 16.

The ink supply means 16 has an angle of 90 ° from a contact point 12a (directly below the plate cylinder 11) between the relief plate 12 and the substrate 15 to a direction opposite to the rotation direction of the plate cylinder 11 (direction of arrow F). It is located within the range and is disposed so as to face the peripheral surface of the plate cylinder 11. Here, the contact point 12 a becomes the printing start end 12 a of the relief plate 12.
The ink supply means 16 is positioned within an angle range of 90 ° from the printing start end 12a in the direction opposite to the rotation direction of the plate cylinder 11 with the printing start end 12a of the relief plate 12 as a reference. The ink supply means 16 includes an anilox roll 161, an ink fountain 162, and a doctor 163.

  The anilox roll 161 is disposed so as to be parallel to the rotational axis of the plate cylinder 11 and in contact with the plate surface 12 b of the relief plate 12, and supplies the light emitting layer ink 10 to the plate surface 12 b of the relief plate 12. The position where the anilox roll 161 and the relief plate 12 are in contact with each other as long as the ink supply means 16 does not interfere with the surface plate 14 and the substrate 15, as much as possible below the plate cylinder 11, that is, with the rotation of the plate cylinder 11. The one closer to the contact point 12a with the printed board 15 is preferable. That is, the distance from the ink supply position to the relief plate 15 to the contact point 12a can be shortened, and at the same time, the time during which the ink is applied to the plate surface 12b of the relief plate 12 is advantageously reduced.

The anilox roll 161 is rotated at the same peripheral speed as that of the plate cylinder 11. On the outer peripheral surface of this anilox roll 161, as shown in FIG. A concave portion 161a is engraved.
The reason why the peripheral speeds of the anilox roll 161 and the plate cylinder 11 are the same is that the relief 161a is engraved on the outer peripheral surface of the anilox roll 161. This is to prevent damage.

In addition, the ink fountain 162 has an ink reservoir 162a that maintains the peripheral surface portion located below the entire peripheral surface of the anilox roll 161 in an immersed state.
The doctor 163 is for scraping off the ink 10 excessively adhering to the surface of the anilox roll 161 coming out of the ink reservoir 162 a by rotation, and leaving the ink only in the relief 161 a of the anilox roll 161. The doctor 163 has a blade-like shape or a roll-like shape, and any of them may be used. The doctor 163 is positioned between the ink reservoir 162a and the contact point with the relief plate 12 in the rotation direction of the anilox roll 161, and is particularly disposed closer to the ink reservoir 162a than the upper top of the anilox roll 161 and scrapes off. It is most preferable to make the ink fall into the ink reservoir 162a.

  The ink replenishing means 17 includes an ink tank 171 and an ink replenishing pump 172, and the ink tank 171 and the ink fountain 162 are connected by an ink replenishing tube 173 via the ink replenishing pump 172. The ink replenishing pump 172 is periodically driven according to the number of times of printing to supply ink from the ink tank 173 to the ink fountain 162 so that the ink amount and viscosity of the ink reservoir 162a can be maintained constant. . Conversely, a mechanism for sucking out the ink in the ink reservoir 162a from the ink fountain may be provided so that the ink in the ink reservoir 162a can be replaced.

(Ink transfer operation of flexo printing machine for organic EL)
Next, the ink transfer operation of the organic EL flexo printing machine according to the present embodiment will be described with reference to FIGS.
When the ink is transferred to the printing substrate 15, as shown in FIG. 2, the printing substrate 15 to which the ink is transferred is fixed on the surface plate 14, and the surface plate 14 is moved directly below the plate cylinder 11. In accordance with this operation, the plate cylinder 11 is rotated at the same peripheral speed as the moving speed of the surface plate 14. At this time, the relief plate 12 installed on the plate cylinder 11 comes into contact with the anilox roll 161 as the plate cylinder 11 rotates, and the ink in the relief 161 a on the surface of the anilox roll 161 is applied to the plate surface 12 b of the relief plate 12. Thereafter, the ink applied to the plate surface 12 b of the relief plate 12 is transferred onto the printing substrate 15 when it is rotated to a position immediately below the plate cylinder 11. Thereby, the transfer of the ink 10 from the ink supply means 16 to the relief plate 12 and the transfer of the ink 10 from the relief plate 12 to the printing substrate 15 can be performed simultaneously.

Ink transfer to the printed substrate 15 is performed when the hole transport layer 6 and the organic light emitting layer 7 are formed. Each ink to be used is as described above.
Here, in the printing by the flexographic printing machine, the surface of the anilox roll 161 exposed from the ink reservoir 162a is easily dried, and when the ink in the relief 161a is hardened, the ink supply amount becomes uneven. For this reason, it is desirable to continue the rotation of the anilox roll 161 during the standby time other than the time of ink transfer so that the surface of the anilox roll 161 is periodically immersed in the ink reservoir 162a to be wet.

  Therefore, it is preferable to provide a mechanism in which the anilox roll 161 or the entire ink supply means 16 is retracted from the plate cylinder 11 so that ink is not applied to the plate surface 12b of the relief plate 12 except during ink transfer. Alternatively, the surface of the plate cylinder 11 on which the relief plate 12 is not installed is configured in a shape that does not come into contact with the anilox roll 161, and during the standby time, the shape portion that does not come into contact with the anilox roll 161 is used. Alternatively, the plate cylinder 11 can be moved up and down, and during the standby time other than the time of ink transfer, the plate cylinder 11 is raised to separate the relief plate 12 from the anilox roll 161, and at the time of ink transfer, the plate cylinder 11 is lowered to remove the relief plate 12. A method of contacting the anilox roll 161 may be used.

  In the present embodiment, the method in which the surface plate 14 moves in the horizontal direction under the plate cylinder 11 has been described. However, the present invention is not limited to this, and the surface plate 14 is fixed, and the plate cylinder 11 and the ink supply means. Ink transfer can be performed in the same manner even when the 16 moves in the horizontal direction.

Next, examples will be described.
Here, trial production and measurement were performed for Example 1 based on the present invention as described below and Comparative Example 1 for comparison, respectively.
"Example 1"
First, an ITO (indium-tin oxide) thin film is formed on a 300 mm square glass substrate by sputtering, and the ITO film is patterned by photolithography and etching with an acid solution to obtain a 5 inch diagonal size. The heating wiring 2 was formed so that two displays could be taken. Thereafter, an acrylic transparent resist material was formed on the entire surface by spin coating, and then the transparent insulating layer 3 was formed on the entire surface excluding the sealing region and the extraction electrode region by photolithography. Thereafter, similarly to the case of the heating wiring 2, the pixel electrode 4 was formed. The line pattern of the pixel electrode 4 per display surface was a pattern in which 1950 lines were formed with a line width of 40 μm and a space of 20 μm.

  Next, the insulating layer 5 was formed as follows. First, a polyimide resist material was spin coated on the entire surface of the glass substrate on which the pixel electrode 4 was formed. The spin coating condition was rotated at 150 rpm for 5 seconds, and then rotated at 500 rpm for 20 seconds to form a single coating. The height of the insulating layer 5 was 1.5 μm. An insulating layer 5 having a line pattern was formed between the pixel electrodes 4 by photolithography using a photoresist material applied to the entire surface.

  Next, a PEDOT solution Vitron CH-8000 was prepared as a hole transport ink to prepare an ink having a solid content concentration of 1.5%, a viscosity of 15 mPa · s, and a vapor pressure of 1.1 kPa. After a voltage was applied to the heating wiring 2 and the heating wiring 2 reached a temperature of 80 ° C., the hole transport layer 6 was formed on the entire surface of the substrate by the slit method. Thereafter, unnecessary portions outside the pixel region were wiped with a waste cloth and dried in the air for 30 minutes to form the hole transport layer 6. The film thickness formed at this time was 50 nm.

  Next, a polyphenylene vinylene derivative as an organic light emitting material was dissolved in toluene to prepare an organic light emitting ink having a concentration of 2% and a viscosity of 50 mPa · s. Using an anilox roll of 750 lines / inch and a water-developable type photosensitive resin plate, a voltage is applied to the heating wiring 2 sandwiched between the insulating layers to reach a temperature of 60 ° C., and according to the line pattern. Then, the organic light emitting layer 7 was printed. As a result, the film thickness of the organic light emitting layer 7 after printing and drying was 80 nm.

  A cathode layer 8 made of Ca and Al was formed thereon by mask vapor deposition using a resistance heating vapor deposition method in a line pattern orthogonal to the line pattern of the pixel electrode 4. Finally, in order to protect these organic EL constituents from external oxygen and moisture, they were hermetically sealed using a glass cap and an adhesive to produce an organic EL display panel. In the peripheral part of the display part of the organic EL display panel obtained in this way, there are an extraction electrode on the anode side connected to each pixel electrode 4 and an extraction electrode on the cathode side, and these are connected to a power source, The lighting display confirmation of the obtained organic EL display panel was performed, and the number of dark spots generated due to foreign matters was counted.

"Comparative Example 1"
Next, an organic EL device for comparison was manufactured by the same manufacturing method as in Example 1. However, in the case of Comparative Example 1, the hole transport layer 6 and the organic light emitting layer 7 are not applied to the heating wiring 2 sandwiched between the insulating layers 5 of the printed substrate 15, that is, without heating. It was formed by printing. Other manufacturing conditions were the same as in Example 1.
"Evaluation"
In FIG. 4, the evaluation result which compared the height difference of the positive hole transport layer 6 on the pixel electrode 4 and the organic light emitting layer 7 in the above Example 1 and the comparative example 1 is shown.

  As can be seen from FIG. 4, it can be seen that the result of Example 1 based on the present invention is better than that of Comparative Example 1.

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Heating wiring, 3 ... Transparent insulating layer, 4 ... Pixel electrode, 5 ... Insulating layer, 6 ... Hole transport layer, 7 ... Organic light emitting layer, 8 ... Cathode Layer, 9 ... glass cap, 10 ... ink, 11 ... plate cylinder, 12 ... letterpress, 12a ... contact point between letterpress and printing substrate, 12b ... plate surface, 13 ... support base, 14 …… Surface plate, 15 …… Printed substrate, 16 …… Ink supply means, 161 …… Anilox roll, 161a …… Relief (recess), 162 …… Closed chamber, 17 …… Ink replenishment means, 171 …… Ink Tank, 172 ... Ink replenishment pump, 173 ... Ink supply tube

Claims (6)

A method of manufacturing an organic EL element, in which a pixel electrode and a counter electrode are stacked and disposed on a substrate via an organic light emitting medium layer,
A first step of laminating a heating wiring and a pixel electrode in this order on a substrate, and forming an insulating layer defining a light emitting region on the pixel electrode;
A second step of forming the organic light emitting medium layer on the pixel electrode by printing an ink in which a material constituting the organic light emitting medium layer is dissolved or dispersed in a solvent by a relief printing method. Is a method for producing an organic EL element, which is carried out in a state where a temperature is raised by applying a voltage to the heating wiring. The organic light emitting medium layer includes at least two layers of a hole transport layer and an organic light emitting layer,
The second step includes a first printing step in which printing is performed using a hole transport material, and a second printing step in which printing is performed using an organic light emitting material as a material constituting the organic light emitting medium layer. 2. The method of manufacturing an organic EL element according to claim 1, wherein a voltage is applied to the heating wiring when printing is performed using at least the organic light emitting material.   The method for producing an organic EL element according to claim 1 or 2, wherein the temperature of the heating wiring at the time of printing is set to 30 to 230 ° C. A method of manufacturing an organic EL element, in which a pixel electrode and a counter electrode are stacked and disposed on a substrate via an organic light emitting medium layer,
An insulating layer that defines a light emitting region is formed on the pixel electrode stacked on the substrate, and then the material constituting the organic light emitting medium layer is dissolved or dispersed in the solvent while the pixel electrode is heated on the pixel electrode. A method for producing an organic EL element, wherein the organic light-emitting medium layer is formed by printing the produced ink by a relief printing method. At least a pixel electrode, a counter electrode disposed opposite to the pixel electrode, and an organic light emitting medium layer interposed between the pixel electrode and the counter electrode and including a hole transport layer and an organic light emitting layer, In an organic EL element that emits light from an organic light emitting layer by passing a current from both electrodes to the organic light emitting layer,
An organic EL device manufactured by the manufacturing method according to claim 1. In the organic EL element in which the pixel electrode and the counter electrode are stacked on the substrate via the organic light emitting medium layer,
An organic EL element, wherein a heating wiring is disposed on the opposite side of the pixel electrode from the counter electrode with an insulating layer interposed therebetween.

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